US 20050101887 A1
Orthoses with microprocessor control placed around the joint of a patient are used to perform and to monitor isometric, range-of-motion, proprioception and isotonic exercises of the joint. A variety of improved hardware elements result in an orthosis that is easier to use and interacts more efficiently with the controller to allow the monitoring of a greater range of motions while holding down cost and provide suitable accurate evaluation of the exercises. Efficient ways of programming the exercises, monitoring the exercises and evaluating the exercise provide a comprehensive program for the rehabilitation of an injured or weakened joint.
1. An orthosis comprising:
a first support portion that fits around a first body portion on a first side of a patient's joint;
a second support portion that fits around a second body portion, the second body portion being on the opposite side of the joint from the first body portion;
a flexible connection connecting the first support portion and the second support portion;
a position sensor operably connected to the flexible connection such that the position sensor detects the relative orientation of the first support portions with respect to the second support portion; and
a microprocessor based portable controller connected to the position sensor, where the first support portion and the second support portion each have a connection for attachment to a continuous passive motion device.
This application is a continuation of U.S. patent application Ser. No. 09/382,433 to Stark et al., Now U.S. Pat. No. ______, entitled “ORTHOSES FOR JOINT REHABILITATION, which claims priority to U.S. Provisional Application Ser. No. 60/098,779, entitled “ORTHOSES FOR JOINT REHABILITATION,” filed on Sep. 1, 1999, both of which are incorporated herein by reference.
The invention relates to orthoses useful for the rehabilitation of injured and/or weakened joints.
Both muscles and bones should be exercised to maintain strength. Also, bone fractures that are exposed to permissible weight bearing stress often heal more predictably and more rapidly than fractures that are not stressed at all. Improved healing based on application of appropriate stress is also believed to be true for connective tissue, such as ligaments and certain cartilage.
Suitable stress can be applied to the tissue by the performance of selected exercises. For example, isometric exercise generally involves the exertion of force against a relatively immovable object, which allows no motion of the limb. To perform isometric exercises, a restraining device can be used that has a substantially unchanging position for the duration of a particular exercise routine. Isotonic exercises involve exertion against the same weight or resistance through a range of motion. Isokinetic exercise is designed to mimic exertions that take place on a playing field or the like. When performing isokinetic exercises in a simulated environment, a machine is used to provide resistance in direct proportion to the exertion of the exerciser.
Isometric exercises are particularly useful with painful injuries to lower the risk of further injury. Also, because isometric exercises are performed in a static position, they allow very position specific therapy. For example, to climb stairs, a person needs more strength at an approximate 60° knee bend, when combined with the hip and ankle joints. Therefore, the isometric exercises can be designed to focus on the strengthening of a joint at optimum angles where additional strength is needed. If performed in a controlled manner, isometric exercises can be performed earlier in the recuperation period to speed recovery. As the patient's recovery progresses, isotonic exercises or other exercises can be used to reestablish a desired strength through a range of motion about a joint. As recovery progresses eventually the patient is able to perform a full range of exercises.
A difficulty with application of stress to an injured joint include a risk of inappropriately timed or excessive stress. This can impair healing and/or further injure the damaged tissues. Thus, exercises need to be carefully planned to provide appropriate amounts of stress. Also, the performance of the exercises should be monitored closely to reduce the risk of injury. Moreover, the need to carefully plan and closely monitor the exercises provides a cost and motivation barrier to accessing desirable amounts of exercise.
In a first aspect, the invention pertains to an orthosis comprising:
In another aspect, the invention pertains to an orthosis comprising:
Moreover, the invention pertains to a method of performing closed chain exercises, the method comprising:
In a further aspect, the invention features a method of performing coordination exercises for neuromotor training comprising:
Moreover, the invention pertains to an instrumented exercise device comprising:
Furthermore, the invention pertains to an instrumented exercise device comprising:
In a further aspect, the invention pertains to a kit comprising:
Additionally, the invention pertains to an orthosis comprising:
Moreover, the invention pertains to an orthosis comprising:
In addition, the invention pertains to an orthosis comprising:
In another aspect, the invention pertains to a strain measuring circuit comprising:
Furthermore, the invention pertains to a method of calibrating a strain measurement comprising:
In a further aspect, the invention pertains to a joint force applicator comprising:
In another aspect, the invention pertains to an orthosis comprising:
In addition, the invention pertains to a method of evaluating an exercise program or the patient's response to the injury comprising:
In another aspect, the invention pertains to a method for programming a portable controller to guide a patient through an exercise routine, the method comprising:
In a further aspect, the invention pertains to a monitoring station comprising:
In addition, the invention pertains to an instrumented hinge comprising:
Furthermore, the invention pertains to an orthosis comprising:
Orthoses can be used effectively to speed the rehabilitation of an injured and/or weakened joint of a patient. In particular, an orthosis can include a microprocessor to monitor and assist with the performance of exercises. The microprocessor can also track the patient's performance and provide a means of reporting the performance to a central collecting station or a health care professional. Important features have been identified that provide for efficient use of a microprocessor monitored orthosis. By simplifying the use of a rehabilitation orthosis through microprocessor instruction to the patient as well as simplifying and improving monitoring of the exercises, accessibility to useful levels of rehabilitative exercise is greatly enhanced. Some of the improved features can be used effectively in improved orthoses even without having microprocessor control.
Relevant orthosis fit around the joint of a patient, i.e., flexibly connected body portions. The orthosis can be designed to fit around any joint or series of joints including, for example, the knee, wrist, ankle, hip, elbow, shoulder, spine/back. Generally, the orthosis includes a plurality of support portions connected by a hinge or comparable connection. At least one support portion fits on one body portion on one side of a joint, while one or more other support portions fit on a second body portion on the other side of the joint. The hinge can have a conventional design or one of the improved designs described below. One or more support portions can be secured to the patient with the use of an external fixator or other similar attachment approach.
Relevant orthoses can be used to assist with one or more rehabilitation procedures. In particular, the orthosis preferably is useful to monitor the performance of isometric exercises. Isometric exercises generally can be performed relatively early in the rehabilitation of an injured and/or weakened joint. In other preferred embodiments, the orthosis also can monitor the performance of range-of-motion exercises, proprioception exercises, isotonic exercises and/or closed chain exercises. Similarly, the orthosis can be designed to apply and monitor selective pressure to reduce forces applied to worn components of joints.
Some preferred embodiments include an additional component to provide for closed chain exercises when used with the joint supporting component. Closed chain exercises involve muscular motion against resistance to mimic natural motions or to provide balanced stresses to the joint. Closed chain exercises can be contrasted with open chain exercises where a limb or the like is moved or stressed in space without any resistance against the motion other than perhaps the weight of the limb itself. Closed chain exercise may provide more balanced exercise of the various muscle groups within a patient's limb or trunk. The closed chain component may or may not be physically connected with the joint supporting orthosis components.
A strain sensor or strain gauge can be used to make measurements of isometric exercises by measuring stress within the orthosis. Several design features of the controller can be used to obtain useful strain measurements using relatively inexpensive hardware. These features are described below.
The coordination of the exercise routine preferably is handled by a microprocessor based controller that assists by prompting the patient for the performance of an exercise routine and by monitoring the routine. Generally, the controller is programmed with a target exercise routine selected by a health care professional. The controller assists the patient with the performance of the exercise by providing immediate feedback with respect to evaluating the performance of the exercises relative to the target routine. The controller may store selected information on the patient's performance of the exercises. This information can be downloaded for evaluation of compliance and performance by a health care professional.
Alternative instrumented exercise devices include an instrumented abduction/adduction exerciser and an instrumented therapeutic resistance (stretch) cord. These instrumented exercise devices can be used alone or in combination with an instrumented orthosis. Instrumentation of these exercise devices provides for the monitoring and evaluation processes used with the instrumented orthosis.
1. Orthosis Construction
A relevant orthosis includes a joint support component, one or more transducers, a control unit and, optionally, additional treatment component or components. Generally, the entire orthosis is portable in the sense that the joint support component can be supported completely by the corresponding body portions of the patient while the patient is mobile. Thus, the orthosis like a cast or the like is ambulatory, i.e., carried by the patient during their activities. Any additional treatment components may or may not be physically connected with joint support component. The joint support component includes support portions joined by a flexible connection or hinge.
A relevant orthosis generally includes, at least, one support portion attached on opposite side of the joint. The one or more support portions on one side of a joint are connected to the one or more support portions on the other side of the joint by a flexible connection. The flexible connection preferably is selectively flexible such that the flexible connection can be locked in a particular configuration. Of course, a suitable orthosis can cover more than a single joint, especially with a back orthosis. Nevertheless, elements can be identified as support portions if by no other feature than being the last on either end of a set of articulating elements comprising the orthosis. The support portions can have a variety of structures.
Frame members 120, 122 generally are constructed from rigid materials such as steel aluminum, other metals or alloys, fiberglass, composites, other similar materials, or combinations thereof Flexible straps 124, 126 preferably are adjustable such that the support portion 104 can be fit to the patient. Adjustment of flexible straps 124, 126 can be performed with hook and loop fasteners or any of a variety of other fasteners including conventional fasteners. Flexible straps 124, 126 can be replaced in alternative embodiments by sheets of fabric or the like which can be adjusted with hook and loop fasteners or other fasteners including conventional fasteners. Similarly, support portion 106 includes a left frame member 140 and a right frame member 142 connected by flexible straps 144, 146.
Support portions 104, 106 can include connections 148 for attachment to Continuous Passive Motion (CPM) devices, for example, on frame members 120, 122, 140 and 142. Any of a variety of possible connections can be used that can transfer the force from the CPM device to the frame of the orthosis without damaging the orthosis. Suitable connections can be made with any of a variety of releasable fasteners such as snaps, clips, pivots and the like. CPM devices are passive in the sense that motors are used to flex joints. CPM devices can be useful in combination with an isometric exercise device since CPM devices can flex the joint over a particular range of motion when the muscles have not yet healed sufficiently to perform comparable motions actively. The corresponding CPM machine would have the appropriate component of the connector for attachment to the orthosis. The CPM machine can be connected to the controller for orthosis 100. The controller can be used to control the motor speed and the like. The connection can be by way of a RS232 connection, infrared connection, radio connection or the like.
Another alternative embodiment for replacing straps 124, 126 is shown in
In an alternative embodiment of the orthosis 200, support portions 202, 204 involve extended elements that fit the appropriate body portion, as shown in
As shown in
Right frame elements 210, 212 and the corresponding left frame elements can be molded into the support portions 202, 204 when the support portions are formed. In some preferred embodiments, sheaths 220, 222 are molded into support portions 202, 204. Right frame elements 210, 212 lock into sheaths 220, 222 such that right frame elements 210, 212 are held firm relative to support portions 202, 204. For example, the sheath can include a flange that allows a series of ridges to pass in a single direction such that the frame element fits into the sheath but cannot be removed. Similar lock elements are used plastic ties. Alternatively, a reversible locking mechanism can be used, for example, where a lock pin or the like is inserted through the sheath and into the frame element.
Right frame elements 210, 212 can be disengaged from sheaths 220, 222 either by disengaging a locking mechanism or by destroying the sheath 220, 222. Sheath 220, 222 can be constructed from an inexpensive but durable polymer. Thus, frame elements 210, 212 and hinge 214 can be reused in another orthosis. Comparable attachments would be used to secure the left side of the support portions. Right hinge 214, right frame elements 210, 212, sheaths 220, 222 can be placed into a kit. Generally, the kit would further include the corresponding left elements and/or a strain sensor and controller, as described below. The kit preferably would be placed within a single package although multiple packages can be used if desired.
In preferred embodiments, the orthosis includes one or more strain sensors. The strain sensors are useful for the performance and monitoring of isometric exercises with a selectively flexible connection/hinge in a locked position. Also, the strain sensor is useful for the measurement of forces during isotonic exercises. The strain sensors generally are located on a rigid element that is under stress when torque is applied to the selectively flexible connection/hinge. Thus, the preferred locations for the strain sensors depend on the particular construction of the orthosis. Referring to
When forces are applied by the patient against the orthosis, the orthosis tends to change position relative to the patient's joint. This shifting reduces the effectiveness of exercises being performed with the orthosis and may necessitate realignment of the orthosis for proper fit. The orthosis can be designed to reduce or eliminate this shifting.
A first approach to prevent a knee orthosis from slipping during exercise is to construct the orthosis with indentations 250, 252 in the femur supracondylar area just above the knee, as shown schematically in
Another approach to securing the orthosis involves securing the orthosis 274 to a belt 275 by way of one or more straps 276. In preferred embodiments, straps 276 and belt 275 provide a path for electrical communication between electronic elements 277 and electronic elements 278 on belt 275. Straps 276 can be secured using hook and loop fasteners, hooks or any other reasonable fastener.
Still another approach involves increasing the friction of the surface contacting the orthosis or part of the orthosis. For example, in
With any of these approaches for inhibiting orthosis motion during use, the method preferably distributes the restraining forces sufficiently such that no portion of the skin is subject to excessive pressures that could bruise the skin as well as damage or interfere with neural or circulatory functions.
The instrumented orthoses described above involve an external framework that surrounds a patient's joint. The orthoses are appropriately designed to secure comfortably the orthosis around the joint and to resist movement of the orthosis when forces are applied to the orthosis. As an alternative to the use of an instrumented orthosis surrounding the respective body portions, the instrumented orthosis can include one or more rigid attachments to the patient. These alternative forms of the orthosis use structures such as external fixators or the like for attachment. External fixators have been used to secure broken bones and to reduce fractures by attaching an external rigid frame to a patient's bone with pins. When integrated into the instrumented orthoses described herein, the structure of an external fixator involves the attachment of the external frame to one or more hinge elements. Suitable hinge elements for use in orthoses with an external fixator structure are the same as those hinge elements that are suitable in orthoses with a purely external framework.
A first embodiment of an instrumented orthosis secured with features of an external fixator is depicted in
Clamps 287 are attached to each frame element 284, 285. As shown in
A variety of clamp and frame element structures can be used. Suitable clamps are described further in U.S. Pat. No. 5,674,221 to Hein et al., entitled “External Fixator With Improved Clamp And Methods For Use,” incorporated herein by reference, and in U.S. Pat. No. 5,891,144 to Mata et al., entitled “External Fixator,” incorporated herein by reference. Generally, transducers that are connected to controller 232 are attached to an orthosis with external fixator structures in a comparable way as with orthoses having purely external frameworks.
The external fixator generally includes one or more transducers 299. Transducer 299 can be a strain sensor such that strain within the lever arms can be measured. Alternatively, transducer 299 can be a position sensor if the connector is a hinge. The position sensor measures the relative orientation of the lever arms. Additional transducers 299 can be included to measure deforming bone/tissue forces. For example, a strain sensor can be added to the pins, such that strain within the pins is measured.
An alternative embodiment of an instrumented orthosis with external fixator type connections is shown in
Similar structures can be used for attachment to the spine. In these systems, pins can be replaced with spinal hooks or screws. Suitable spinal attachment systems are described further in U.S. Pat. No. 5,281,222 to Allard et al., entitled “Spinal Implant System,” incorporated herein by reference.
As described above with respect to
Furthermore, preferred flexible connections can be locked in selected orientations. If the flexible connection can be locked, isometric exercises can be performed at the locked orientation. The lock can be released and relocked at a new orientation to perform additional exercises at the new location. A couple of locking mechanisms are described in U.S. Pat. No. 5,052,375, supra. Similarly, it is useful for the flexible connection to be able to apply selected amounts of resistance to rotation. If selected amounts of resistance can be applied, the orthosis can be used more effectively for the performance of isotonic exercises. Copending U.S. patent application Ser. No. 08/442,945 to Stark, entitled “An Orthopedic Device Supporting Two or More Treatment Systems and Associated Methods,” incorporated herein by reference, describes the electronic selection of a desired amount of mechanical resistance using the control unit.
While electronic control of the rotational resistance in the flexible connection has advantages, cost and design simplicity favors a purely mechanical hinge. The strain sensor readings can be accurately calibrated to reflect the forces applied to move the hinge against a setting on the mechanical resistance applicator. Thus, the controller can be used to monitor the isotonic exercises even though the resistance is not electronically controlled. In this respect, a resistance applicator 300 (
Referring to 17-19, housing 304 includes base 326 and lock pins 328, 330. Lock pins 328, 330 provide releasable connection for attachment of resistance applicator 300 to a hinge. Alternative locking approaches can be used for the attachment of the friction applicator to the hinge. Base 326 includes threaded hole 332 for engaging knob 310 and threaded holes 334, 336 for engaging lock pins 328, 330, respectively. Base 326 further includes protrusion 338 for engaging compression structure 308. Lock pin 328 includes threads 340 for engaging threaded hole 334, and lock pin 330 includes threads 342 for engaging threaded hole 336. Alternatively, lock pins 328, 330 can be welded or the like to base 326.
Compression structure 308 provides for small changes in the resistance due to changes in the distance between washer 314 and housing 304 as knob 310 is rotated, thus amplifying resistance changes by way of the knob. Compression structure 308 generally produces friction as a result of shear forces within compression structure 308 due to relative motion of housing 304 and crank 306. In the embodiment in
Crank discs 370 include protrusions 374 that engage notches 354 such that crank discs 370 rotate with crank 306. Housing discs 372 have a central hole 376 shaped to engage protrusion 338 in housing 304 such that housing discs 372 rotate with housing 304. Compression spring 373 includes an elastic protruding section 378 with a central hole 379. Compression spring 373 can be replaced with an spring washer or the like. In one preferred embodiment, compression structure includes 7 housing discs 372 and 6 crank discs 370 in an alternating layers. Other quantities of crank discs 370 and housing discs 372 can be used as desired.
Washer 314 has a suitable inner diameter such that threaded shaft 382 can pass through the inner diameter but bearing unit 312 cannot pass. Washer 314 has an outer diameter such that washer 314 rests on center portion 350 of crank 306 covering the opening to compression unit 308 between housing 304 and crank 306. Two optional spacers 316 preferably are located with one on each side of compression unit 308. Spacers 316 have the shape of a washer but with a suitably larger inner diameter and smaller outer diameter than washer 314 such that spacers 316 fit within the cavity between crank 306 and housing 304 holding compression structures 308.
The primary components of the resistance applicator 300 preferably are made from metals and/or alloys. Aluminum alloys and stainless steel are suitable metals for the construction of housing and crank components. Rigid polymers can be used in place of metals for the housing and crank elements. The spacers preferably are made of brass. The housing disc preferably is made from spring steel and the crank disc preferably is made from spring tempered phosphor bronze. The bearing case can be made from Nylons.
Resistance applicator 300 is designed to attach to a hinge such that housing 304 moves with a frame member attached to one side of the hinge while crank 306 moves with a frame member attached to the other side of the hinge. Thus, rotation of the hinge results in rotation of housing 304 relative to crank 306. Tightening of knob 310 presses washer 314 down onto compression unit 308. Housing rings 372 and crank rings 370 rotate relative to each other when housing 304 moves relative to crank 306. Increasing the pressure on compression unit 308 results in increased resistance in the rotation of housing 304 relative to crank 306 because of friction between housing rings 372 and crank rings 370. Increasing the number of housing rings 372 and/or crank rings 370 increases the amount of resistance. This design provides for sensitive adjustment of rotational resistance provided by resistance applicator 300 by rotation of knob 310. Housing rings 372 and crank rings 370 can have non-uniform thickness or non-uniform shape such that the degree of resistance varies as a function of rotational angle.
A particular embodiment of a left hinge 400 for use with resistance applicator 300 is shown in
Hinge 400 includes a outer plate 402, washer 404, locking unit 406, ring lever 408, electrical resistance disc 410 and inner plate 412. Outer plate 402 is connected to a frame member 418. Strain sensor 230 can be attached to frame member 418. Outer plate 402 and inner plate 412 include concentric stop holes 420, bolt holes 422, connection holes 424 and slot 426. The corresponding holes are aligned between left outer plate 402 and inner plate 412.
One or two stop pins 430 (
Locking unit 406 includes control disc 446, slider 448, slider spring 450 and lock-out latch 452. Control disc 446 included a slit 454 in which slider 448 slides. Slider 448 has a groove 456 and an indentation 458 with a catch 460. Lock-out latch 452 has a knob 462 and a bar 464. Bar 464 slides within slots 426 and can fit within groove 456 to hold slider 448 in a depressed, unlocked, position.
Ring lever 408 is connected with a frame member 470. Ring lever 408 has an opening 472 with a diameter slightly larger than the diameter of control disc 446 such that control disc 446 can fit within opening 472. Control disc 446 preferably has a thickness slightly larger than ring lever 408. A set of concentric, notches 474 are located around the edge of opening 472 of ring lever 408. Catch 460 of slider 448 fits within the notches 474 to lock the hinge at a particular orientation when slider 448 is in an extended position. Depressing slider 448 against the force of spring 450 disengages catch 460 from one of the notches 474 such that hinge 400 is free to rotate within the bounds establishes by any stop pins 430. Ring lever 408 includes an electrical contact 476 set within a hole 478 that contacts electrical resistance disc 410. Electrical contact 476 is connected by wire 480 to controller 232 or alternative resistance meter. Washer 404 can be placed between outer plate 402 and control disc 446.
Outer plate 402, inner plate 412, ring lever 408, control ring 446, lock-out latch 452 and slider 448 preferably are made from rigid, durable materials. In particular, outer plate 402 and inner plate 412 are preferably made from an aluminum alloy, and ring lever 408, control ring 446, lock-out slide 452 and slider 448 preferably are made from stainless steel. Spring 450 generally would be made from resilient steel or the like. Washer 404 and stop pin 430 generally are made from polytetrafluoroethylene or the like. Electrical resistance disc 410 can be made from circuit board material with a resistance element screen-printed on its surface.
Frame members 418 and 470 extend to opposite sides of the hinge such that movement of frame member 418 relative to frame member 470 involves rotation of hinge 400. When hinge 400 rotates, outer ring 402 and inner ring 412 rotate relative to ring lever 408. Outer ring 402, inner ring 412 and control disc 446 are held fixed with respect to each other by way of bolts passing through bolt holes 422. The orientation of hinge 400 is locked unless slider 448 is depressed such that catch 460 is withdrawn from notches 472. Lock-out slide 452 can hold slider 448 in the depressed, unlocked position. The position of ring lever 408 relative to inner ring 412 can be measured by way of the position of electrical contact 476 along electrical resistance disc 410. The relative position of electrical contact 476 along electrical resistance disc 410 provides a variable electrical resistance useful for position/orientation sensing.
It may be convenient to provide for release of a hinge with a remote control. U.S. Pat. No. 5,052,375 provides for the release of the hinge using a command from the control unit. It may be desirable to have a simple mechanical remote release. A simple photographic shutter release 490 (
Certain joints such as the knee are cams that do not involve rotation about a single axis. A biaxal hinge can be used to more closely approximate the motion of the joint cam. A biaxial hinge 510 generalizing on the structure of hinge 400 is shown in
In simplified embodiments, controller 232 may just include analog circuits and a suitable display. In preferred embodiments, controller 232 includes a digital processor to provide a more sophisticated interface with the patient and to preform more involved monitoring functions. The digital processor preferably is a microprocessor. The digital processor can be programmed in any of a variety of computer languages including, for example, basic, assembler, C, C++ and the like. Preferably, controller 232 is portable, which in this context means that the controller is small enough to be held in the hand of a patient. More preferably, controller 232 is small enough to be placed in a standard shirt pocket.
A preferred microprocessor based controller 232 has several subsystems including a power supply such as a nine volt battery, a transducer bias circuit such as described below, A/D converters, a microprocessor, real time clock, RAM and non-volatile storage such as FLASH or EEPROM, a graphic display such as a 64×128 pixel LCD display with a corresponding driver, keypad, audible or tactile feedback device, data link to transducer, and RS232 standard output for serial connection or modem access.
In one particular embodiment, the microprocessor is a Motorola MC68HC11A1FN 8-bit microcontroller with built-in deep sleep shutdown mode for power conservation between active events, a programmable serial interface and an 8-channel, 8-bit A/D converter. In this embodiment, controller 232 can provide analog multiplexing and A/D conversion for up to 8 analog input signals over a voltage range from 0.0 to +5.0 volts. For example, three of the channels can be devoted to provide signal conditioning for up to three strain sensors, and three of the channels can be devoted to providing signal conditioning for up to three position (angle) sensors. The remaining two input channels then can be used for additional treatment devices.
The controller module memory is partitioned into FLASH, SRAM and EEPROM. Each section is independently addressable. In one particular embodiment, FLASH is 128K words, and EEPROM is 32K words with 8-bits (1 byte) per word. A 16K portion of SRAM is used for memory management. The EEPROM supports in-circuit reprogramming by way of the microcontroller serial channel for code updates. The SRAM has battery backup, and FLASH provides non-volatile storage of recorded data during times when the microprocessor is not powered. The real time clock also is battery powered to allow time keeping to continue when the microcontroller circuitry is off. The real time clock is capable of generating periodic interrupts at a programmable rate to power switching circuitry to activate the microcontroller during an alert mode of operation.
The RS-232 interface consists of three conductor (TxD, RxD and GND) jack type connector with a mechanical switch to automatically switch power on to all on-board electronics when the plug is inserted. The baud rate of the interface is programmable with standard rates such as 9600 and 19200. A suitable display is a Hantronix HGS13Y or Densitron™ LE3328 LCD with Hitachi HD61202 and HD61203 LCD controller chip sets. The display can be run with a five volt supply that can be separate or not from the power supply for the rest of controller 232. In this embodiment, a four key keypad is interfaced with the microcontroller.
All of the components of controller 232 can be placed on the orthosis or in a separate case. The components of controller 232 can be integrated into a single package or physically partitioned into portions mounted on the orthosis frame and/or portions placed into one or more small cases. This is shown schematically in
Controller 232 preferably stores a software program that manages the use of the device for patient rehabilitation. The software can provide for alerting the patient to scheduled times for the performance of exercises using audible and/or vibratory signals. Controller 232 preferably provides instructions on the exercises as well as feedback and reinforcement messages to the patient. Further details on the operation of the controller are provided below.
Stored information relating to the patient's performance of exercises generally is downloaded to the supervising health care professional at specified intervals. The download of the information can be performed in a variety of ways. If the patient goes to the office of the health care professional, controller 232 can be directly connected to the monitor station/computer using the RS232 port or other port using suitable protocols including standard protocols. Alternatively, controller 232 can be attached to a modem by way of the RS232 port or other suitable port. Since with certain embodiments the file sizes are relatively small, a single chip, 9 volt supply Rockwell® 2400 baud modem can be used. Controller 232 can be in radio communication with a monitor station. Controller 232 then would include a radio transmitter and, optionally, a receiver. Radio communication with a monitor station is described further in copending U.S. patent applications to Stark et al., 08/389,680 entitled “Communication System For an Instrumented Orthopedic Restraining Device and Methods Therefore” and Ser. No. 08/804,950 entitled “Local Monitoring System For an Instrumented Orthopedic Restraining Device and Methods Therefore,” both of which are incorporated herein by reference. The display or television set similarly can be in communication with controller 232 by way of radio transmissions or infrared communication such that a wire attachment is not necessary.
In order for the value of electrical resistance associated with a strain sensor to be useable as a measure of applied stress during isometric exercises, the values must be referenced to a “null” valve approximately corresponding to a value when no strain is applied to the orthosis. The null value can be set by a manual adjustment performed by the health care professional or by the patient. The “null” value, however, is preferably established automatically without the need for calibration by the user. Furthermore, the variations in the resistance due the strain sensor preferably are converted into a voltage value that is amplified to make efficient use of an analog-to-digital (A/D) converter with a specified number of binary digits.
An approach for performing this calibration is outlined schematically in the block diagram of
An embodiment of summing amplifier 610 is shown in
Second amplifier circuit 614 includes amplifier 638 and resisters R17 640, R18 642, R21 644 and R210 646. Resister R210 is further connected to ground. Second amplifier circuit 614 outputs voltage V02 and current i02 to A/D converter 604.
The output voltage for summing amplifier 610 can be calculated to be:
A flow chart 660 outlining the performance of the calibration is shown in
Additional treatment units can be combined with the exercise orthosis to assist with the rehabilitation of a joint. For example, the controller 232 can coordinate isometric and/or isotonic exercise treatments along with energy propagating transducer treatments. Exercise/transducer combined treatment approaches are described generally in copending U.S. patent application Ser. No. 08/442,945 to Stark, entitled “An Orthopedic Device Supporting Two or More Treatment Systems and Associated Methods,” incorporated herein by reference. Energy propagating transducer based treatments include, for example, ultrasonic treatments, pulsed electromagnetic treatments and electrical conductance treatments.
In addition, a treatment device for alleviating pain due to osteoarthritis can be monitored by controller 232 or comparable control unit. The osteoarthritis treatment device could be effectively used alone or combined with an exercise orthosis. Joins often wear unevenly. This results in pain due to bone on bone contact where cartilage has worn away. A support can be placed around the joint to shift the stresses to the less worn portions of the joint thus alleviating pain.
The amount of a force applied to the joint preferably is measured to avoid the application of excessive force and to monitor compliance. The applied lateral forces can be measured using a pressure sensor or strain sensor 686 in or on force applicator 6.84 and/or using a strain sensor 688 on restraint 682. Pressure sensors/strain sensors 686, 688 can be connected to the controller 232 by way of wires 690.
Suitable strain sensors were described above. Pressure sensor 686 can be any reasonable type. A variety of suitable pressure sensors are commercially available. Preferred pressure sensors include the MPX series of pressure sensors manufactured by Motorola because of their linear output and small size. Other suitable pressure sensors use silver oxide ink surfaces separated by a dielectric material or piezoelectric materials that produce a voltage when stressed. Suitable pressure sensors include strain sensors attached to the surface of a bladder since the surface strain is a function of the pressure in the bladder.
Osteoarthritis support 680 to alleviate osteoarhritis can be beneficially used with an exercise orthosis. The performance of isometric or isotonic exercises stimulates the secretion of natural lubricating fluids within the joint. Thus, the support can alleviate the pain sufficiently to perform the exercises, which lead to further pain alleviation due to the secretion of lubricating fluids. The combination of the exercise orthosis and osteoarthritis support 680 can provide considerable improvement in the condition of the patient. Osteoarthritis support 680 can be easily redesigned for other joints or to alleviate pain associated with unusual wearing of a particular joint.
Other instrumented exercise units can be used in conjunction with the orthosis/brace using a single controller 232 or multiple controllers, or alone as an alternative to the orthosis/brace. One such alternative exercise unit is an abduction/adduction exercise device. A first embodiment of an instrumented abduction/adduction exerciser 700 is shown in
Abduction/adduction exerciser 700 includes two lever arms 704, 706. Lever arms 704, 706 are joined at hinge 708. Lever arm 706 of exerciser 700 releasably attaches to hinge 710 of orthosis 702 with connector 712. Lever arm 704 is attached to a padded cuff 714 that can be secured around the patient's leg with a hook-and-loop fastener or the like.
Generally, hinge 708 can be released and locked at a selected orientation. Hinge 708 is locked at an orientation for the performance of isometric exercises. Alternatively, hinge 708 freely rotates, and lever arms 704, 706 are held at a nominal position by spring 716 and can be moved toward each other with the application of force. The amount of force needed to move lever arms 704, 706 can be varied by suitable selection of spring 716.
Instrumented abduction/adduction exerciser 700 includes a strain sensor 718 or the like to measure stresses within exerciser 700. Strain sensor 718 is connected to controller 232 or to a separate control unit. Thus, when the patient flexes or stresses and releases exerciser 700, as part of an exercise routine, the compressive forces applied by the patient can be measured, prompted and monitored similarly to forces applies to an orthosis.
In this particular embodiment, abduction/adduction exerciser 700 is designed to be flexed by a patient's legs. Straightforward modifications can be used to design a comparable exerciser for use with other flexible body parts, such as an exerciser flexed by movement of a patient's arm relative to their body trunk.
Abduction/adduction exerciser 730 includes suitable transducers, such as a strain sensor 742 and/or a position sensor 744 connected to hinge 736. Transducers 742, 744 are connected to controller 232 or to another suitable control unit/display. Measurements from the transducers can be used to monitor, prompt and evaluate the exercises by the patient.
Another alternative instrumented exercise device is an instrumented therapeutic cord, i.e., bands or tubes. The un-instrumented versions of these devices are sold under the tradenames of Thera-Band®, MediCordz® and StretchCordz®. Instrumented therapeutic cords provide a versatile, low cost exercise alternative, which can be used alone or in combination with an instrumented orthosis, as described herein. The unifying theme of these devices is the presence of an elastic cord that provides resistance against motion by the patient.
A embodiment of an instrumented therapeutic cord 750 is depicted in
Cord 756 is connected to a transducer 764 directly or indirectly by way of a handle or the like. As shown in
To perform exercises with an instrumented therapeutic cord, one of the handles/clamps 752, 754 can be attached to an immovable object such as a door knob of a closed door. The patient then stretches the cord, using the other handle/clamp 752, 754, a cuff 758 or the like, with a hand, foot, limb or other body part to exercise the corresponding muscles. Alternatively, the patient stretches cord 756 while contacting the therapeutic cord 750 at two or more points, such as two handles/clamps 752, 754. A large variety of exercises can be performed by appropriately selecting the arrangement of the therapeutic cord.
To adjust the exertion required in the exercises with the therapeutic cord, therapeutic cords are commercially available with different amounts of resistance. If desired, the different levels of resistance can be color coded by the color of the cord, the handle or a portion of the cord. Each cord with different levels of resistance need to be calibrated such that the transducer reading can be correlated with the exerted forces. Controller 232 can be programmed with separate look-up tables for each level of resistance. If the resistance level of the cord is input into the controller, the controller can make the suitable correlation.
For the performance of closed chain exercises, a body portion pushes against an essentially immovable surface. The surface can be a floor, a wall, a table top or the like. In order to monitor the forces being applied, a sensor is used that is placed between the body part and the surface. For example, in
As an alternative to using a foot support connected to an orthosis surrounding a joint, the force sensor can be a separate unit. In particular, foot support 800 can be replaced by a scale 810 or the like, as shown in
If closed chain exercises are to be performed with joints other than the knee, a suitable force sensor can be used. For example, a elbow can be exercised pushing with a hand against a pad sensor 818 on a table or pad sensor 820 against a wall, as shown in
A plurality of force sensors can be used for the performance of closed chain exercises. The controller can instruct the patient to vary the respective forces on the two force sensors. For example, two instrumented scales can be used with one scale having forces applied with an injured leg and the second scale having forces applied with an uninjured leg. the patient can be instructed to switch forces between the two legs at a prescribed rate.
A monitor station can be used by the health care professional to plan and monitor the treatment of the patient. Any computer can be used to perform this function. In particular, Windows® based systems are suitable although Unix®, Macintosh®, LINUX®, html-based or JAVA® systems could also be used. The monitor station should have suitable ports for connection with the controller 232.
With any of the additional treatment units including an osteoarthritis support, an abduction/adduction exerciser, a therapeutic cord and a closed chain exercise monitor, as with the instrumented orthosis itself, the display can be used to present various summaries and statistics to the patient. Suitable statistics to be displayed include, for example, exercise times, repetitions, calories expended, and curves where the area under the curve represents work exerted by the patient during an exercise cycle. Similarly, the variance between a target goal and actual performance during an exercise can be displayed.
2. Orthosis Control
The controllers described above preferably are programmed under the control of an appropriate health care professional. Selection of the desired program is described further below. In this section, the monitoring of selected types of treatments using a microprocessor based controller is described.
In one preferred embodiment, the controller has four modes of operation: OFF, STANDBY, ALERT and FULL ON. In the OFF mode, primary and backup battery power are removed, and no operations are taking place in the controller. In the STANDBY mode, no primary battery power is online, and backup battery power is used to maintain the real time clock and SRAM. Back-up power can be supplied by a coin cell or the like. STANDBY mode is generally used while the primary battery is being replaced or recharged.
In ALERT mode, the real time clock produces a signal at programmed, periodic intervals to activate all on-board electronic components. ALERT-ACTIVE submode has all circuits active. Exercises are generally performed during the ALERT-ACTIVE mode. In ALERT-SLEEP submode, only the real time clock and SRAM memory remain active. ALERT-SLEEP mode is the standard mode of operation between exercise prompts. To allow switching between submodes, primary and backup battery power should be available during the ALERT mode. A beeper function can be used to prompt the patient that an exercise time has been reached.
FULL-ON mode primarily is used during programming and data transfer operations. All on-board electronics and the display are active. FULL-ON mode can be activated automatically when an interface cable is connected.
In a preferred embodiment, the controller can prompt and monitor the performance of isometric exercises, range of motion exercises, proprioception exercises and/or isotonic exercises. When the health care professional programs the controller, the desired exercises from this set are selected along with the associated parameters and timing conditions for the selected exercises. Also, the controller preferably can store two or more sets of exercise routines that can be used in different time intervals relative to the start of rehabilitation. In other words, after a first set of exercise routines have been used for a certain period of time, the controller selects a second, generally more difficult, set of exercises for the patient to perform. These exercises can be performed for any selected joint.
Preferably, the controller prompts the patient at the time for performance of the selected exercises. In some embodiments, the patient presses a key when they are ready to proceed. The display on the monitor can graphically show the patient's motions with suitable coordinates for the particular exercise and compare them with a target, if suitable. The controller can store all of the data points or averages over a set of exercises performed over a period of time. In some embodiments, one button of the controller is a pain button that the patient hits when they feel pain during the exercises. Pain data points from the pressing of the button can be correlated with time, position and activity so that further information for evaluation of the exercise routine is available.
To perform the isometric exercises, the hinge/flexible connector is adjusted to a particular angle. If a manual hinge is used, the hinge is manually adjusted. The controller may instruct the patient if the hinge is set at the desired angle. At the correct angle, the patient applies stress against the fixed hinge in one direction or the other. The controller instructs the patient if the applied stresses are within tolerance values of a target value. The controller preferably prompts the patient regarding the timing of the exercises, including the repetition rate and the amount of time to hold an applied stress. After the selected number of repetitions are performed the exercises are terminated or a new angle of the hinge is selected. The process is repeated until exercises are performed at all of the desired angles.
Improvement in the joint benefits from attention to achieving a desirable range-of-motion (ROM). The ROM can be monitored using the orthosis with a suitable position sensing hinge/flexible connector, as described above. The hinge is set to allow rotation, at least over a portion of the possible rotation range. The performance of ROM exercises is plotted schematically in
Proprioception in this context refers to the patient's sense of position in space, such as the bend of a particular joint. This seeming innate knowledge is a learned phenomenon involving a complex interaction of nerve sensations from sensors that are processed and combined with feedback and correction. A joint has dozens of single-celled measurement sensors: Golgi tendon organs, Paninian-like receptors, Ruffini corpuscles and the like. The brain and spinal cord process the information from these cellular sensors. When a joint is damaged, dozens of sensors may be permanently lost. For example, the anterior cruciate ligament of a knee has over 60 sensor/receptor cells may be lost when the ligament tears. The body makes up for lost receptors by recruiting new sensor information from adjacent places. A new pathway and analysis must be relearned by the nervous system. With a properly designed orthosis this process can be accelerated and enhanced.
In one embodiment, the controller display prompts an action through a graphic display, for example, to get a ball back into a circle, and the patient must react quickly, reflexively with the rehabilitating joint in the orthosis to move the ball on the screen. The position of the ball on the screen is correlated with the position of the joint by way of the position sensor in the orthosis operably connected to the controller. By changing the position of the joint, e.g. knee, the patient can move the ball back into the circle or to another target of some kind. The patient has a limited amount of time to perform the action. As the patient progresses, generally she is given less and less time to respond until the joint has completed recovery. For a joint located on a limb, recovery can be evaluated relative to the joint on the contralateral limb. This exercise can be embedded into a wide variety of game-type environments, where the input comes from the orthosis rather than a joystick or the like. These exercises improve cooperation and coordination. A similar game format can be used to perform isometric exercises where the amount of strain measured by the strain sensor is used to move the cursor.
Because proprioception involves the whole body, a collateral, i.e., uninjured, limb may have significant impact on proprioception performance of the injured limb. It may be advantageous to train the limbs, such as an injured and uninjured leg, together. A simple brace can be placed on the uninjured limb. A suitable proprioception brace 780 is shown in
Hinge 786 preferably includes a position sensor 790 that can be connected to controller 232. In one application, the patient wearing an instrumented orthosis on the injured limb (e.g., leg) and a proprioception brace on the uninjured limb (e.g., leg) can be instructed to shift forces from one limb to the other with specific timing indicated by motion of an object shown on the screen of the controller. For example, the patient may be instructed to shift weight from one leg to the other in a series of closed chain, i.e., weight bearing, proprioception exercises.
Isotonic exercises are similar to the range-of-motion exercises except that selected resistance is provided in the hinge/flexible connection. Resistance is provided by a manual unit such as resistance unit 300 above or by an electrical resistance hinge actuated by the controller. In any case, a desired amount of resistance is set manually or automatically. The joint is then flexed over a prescribed range-of-motion. Controller can monitor the degree of flexing of the joint using the position sensor and the amount of forces applied during the flexing using the strain sensor. The strain sensor can be calibrated such that a strain reading can be matched with a corresponding torque applied to the hinge. If the instrumented orthosis includes both a strain sensor and a position sensor, the outputs relating to the two different transducers can be displayed with the two dimensional motion on the display of a cursor or the like, with the position in the respective dimensions being determined by the reading of a corresponding transducer.
As noted above, the controller can be attached to a variety of additional devices, such as closed chain exercise units, energy propagating transducers, condyle sensors and the like, to assist with treatment. Generally, the monitoring of the operation of these additional units can be performed with the controller in a straightforward manner. The use of the closed chain exercise units is described in more detail.
The performance of closed chain exercises can be performed in either a static/isometric mode or a dynamic isotonic mode. In the static mode, the patient flexes the knee or other joint to the desired angle and then leans against an opposing surface to apply a desired amount of force. The hinge can be locked or unlocked during the exercises. After performing a programmed number of repetitions, the patient is instructed to move the joint to a different orientation. At the new orientation, the patient again applies force according to a preprogrammed target amount of force. The process is repeated until the exercises are performed at all the selected orientations. Again, the exercise can be incorporated into a variety of game formats, such as a slalom skier, basketball free throws, a road race course, a simple moving bar graph, “Pong,” or the like.
This process is depicted schematically in
To perform dynamic closed chain exercises, the hinge of the orthosis is free to rotate during the exercises. The orthosis is first brought to a particular orientation. Then, a desired amount of force is applied at that orientation for a period of time. While the force is applied against the closed chain force sensor, the hinge is rotated to another selected orientation. At the new orientation, the amount of force applied is changed and held for a particular period of time. Again, the orientation is changed while the force is being applied. The process is repeated according to the programming in the controller. Dynamic closed chain exercises creates small but useful and controlled amounts of joint shear.
The procedure for a single dynamic closed chain exercise routine is depicted schematically in
The control unit can be programmed to accept other input from the patient. In particular, inquiries can be directed to the patient at the start of an exercise routine, at the end of an exercise routine or at other times. The answers are stored for downloading to a health care professional along with suitable information regarding the performance of programmed exercises. Additional information on the types of inquiries are described further below.
As part of the monitoring operation, the controller preferably, continuously monitors the performance of an exercise to prevent difficulties. On embodiment of this contingency processing is outlined in
If exercises have been started at step 904, the transducer parameters are evaluated to determine if the exercises are being performed 916 within specified parameters. If they are within tolerance ranges, it is evaluated if the exercises are complete 918. If the exercises are complete, the controller enters sleep mode 920. If the exercises are not complete, the evaluation of the performance 916 of the exercises is repeated.
If the exercises are not being performed within tolerance values, the exercises are evaluated to determine if excessive force is being applied 922. If excessive force is being applied, a sound warning is given 924, and the evaluation of the exercises 916 is repeated. If excessive force is not being applied, it is determined 926 if the patient was previously warned a maximum number of time that the exercise is not being performed correctly. If the maximum number of warning has not been given, the patient is notified 928 again, and the evaluation 916 is continued. If the patient has been warned a predetermined number of times previously, the exercise parameters are evaluated to determine 930 if they are at programmed limits. If not, the parameters are modified 932, and the evaluation 916 is repeated. If the parameters are at preprogrammed limits, it is determined 934 if an error warning has previously been given that the parameters are at their limits. If the error warning was not previously given, the warning is given 936, and the monitoring 916 is repeated. If the warning was previously given, the patient is instructed 938 to call the doctor, and the controller enter a sleep mode 940.
Periodically, the information stored by the processor is downloaded to a health care professional. Various methods for downloading the information were described above. In principle, the controller can store all of the information about the performance of particular sets of exercise routines and download all of this information for analysis. Alternatively, the controller can perform some initial data analysis to reduce the amount of data that must be stored and transferred. Thus, raw or analyzed data can be transferred.
The preliminary analysis, if any, performed by the controller can include grouping and/or averaging of groups of exercises over certain periods of time and/or performed at particular times of the day. This analysis can involve an evaluation of variation with the progress of time to assist the health care professional evaluate whether the patient is making sufficient improvement and to evaluate whether the exercise routine programmed into the controller is appropriate. In one embodiment, the controller downloads the date, time, number of repetitions of an exercise, force curves, range-of-motion end stops achieved, number of hits in a proprioception game, and number of times the patient pushed the pain button.
3. Use of Orthosis
To reduce the chance of the patient injuring themselves using the orthoses described herein, the patient preferably is examined by a trained health care professional prior to using the orthosis. Upon evaluating the condition of the patient, the controller is programmed for suitable exercises. In preferred embodiments, the monitor station assists the health care professional (HCP) with the programming process. In particular, the monitor station can lead the programmer through a set of questions to design to type of exercise routine desired. Based on the answers to the questions, the monitor station pieces together the program for the controller. Once the controller is connected to the monitor station by way of an RS232 connection, a modem connection, a radio connection, an IR connection or other suitable connection using an appropriate protocol, the program is downloaded into the controller.
Generally, the monitor station stores information on a particular patient, so the HCP initially instructs the monitor station whether the patient is a new patient or a continuing patient. Initial questions preferably include patient's age within a set of ranges, patient's sex, joint involved, and type of injury.
In one preferred embodiment, the monitor leads the HCP through a series of screens to fill in information related to the performance of exercises within up to five different time periods, as shown in
Additional screens can be used to provide additional input regarding additional treatment add ons and/or information regarding the controller and the means for communicating with the controller. Once the HCP has completed the specification of the exercise routine, the controller is connected to the monitor station and the controller is programmed with the exercise routine.
At prescribed periods of time, information stored in the controller regarding the performance of the exercises by the patient can be downloaded into the monitor station. The time interval can be determined based on the storage capacity of the controller, the suitable length for evaluation of progress by HCP or other similar issues. The download of information from the controller to the monitor station can be performed at the health care facility where the monitor station is located or at a remote location. If performed at the health care facility, the information can be downloaded by direct hook up of the controller with the monitor station or through a modem, radio connection, infrared connection or the like. Remote hook up can be performed with a modem connection, radio communication or other longer range connection including, for example, the internet.
Suitable analysis is performed of the data. for example, the downloaded data on the exercises can be plotted in raw form or following some form of data averaging or selection. Examples are shown in
To facilitate the monitoring function, real time telecommunication can be performed such that information on the exercises can be received by the health care professional as the exercises are being performed. Similarly, the patient and health care professional can exchange communications in real time. Real time telecommunications can involve teleconferencing or videoconferencing. In addition, the patient and/or health care professional can interface with a web site to access or maintain data base information and or as a communication portal. Additional information on these remote monitoring approaches is provided in U.S. patent application, Ser. No. 09/266,866 to Oyen et al., entitled REMOTE MONITORING OF AN INSTRUMENTED ORTHOSIS,” incorporated herein by reference.
One of several important functions of a microprocessor controlled orthosis is to monitor compliance with performance of exercises. A useful adjunct to the compliance monitoring function can be achieved by performing a psychological evaluation of the patient. The psychological test can be used to evaluate the suitability of the programmed exercises as well as indicate other potential problems with the healing process not directly linked to the exercises.
A relatively simple form of the psychological test can involve questions for the patient prior to the performance of the exercises regarding the patient's readiness to perform the exercises and after the exercises regarding the usefulness of the exercises. The inquiries can take the form of selecting from a selection of a representative graphical representations, such as a happy face, a frowning face etc. A more sophisticated test can involve questions regarding pain being felt by the patient. One systematic set of questions regarding pain have been developed at McGill University and are known as the McGill Pain Questionnaire. The questions relate to the degree of pain, the location of pain, changes in pain and the sensation of pain. The answers can be presented as numerical values that are scored according to a prescribed formula. A further description of the McGill Pain Questionnaire is described in R. Meizack, “The McGill Pain Questionnaire: Major Properties and Scoring Methods,” Pain 1:277-299 (1975), incorporated herein by reference. The questionnaire can be updated and modified as appropriate.
The psychological test can be used as part of the evaluation of the patient. In particular, the exercise routine can be modified in response partly to the to mental attitude of the patient to help assure further compliance with the exercises and to increase the comfort level of the patient. The balance of all of these factors can lead to faster rehabilitation of the patient. Additional description of the use of psychological evaluation as an adjunct to orthopedic treatment is provided in U.S. patent application Ser. No. 09/339,071 to Stark et al., entitled “REHABILITATIVE ORTHOSES,” incorporated herein by reference.
The embodiments described above are intended to be exemplary and not limiting. Further embodiments are within the claims below. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.