US 20050229433 A1
Methods and devices are disclosed for manipulating alignment of the foot to treat patients with flat feet, posterior tibial tendon dysfunction and metatarsophalangeal joint dysfunction. An inflatable implant is positioned in or about the sinus tarsi and/or first metatarsal-phalangeal joint of the foot. The implant is insertable by minimally invasive means and inflatable through a catheter or needle. Inflation of the implant alters the range of motion in the subtalar or first metatarsal-phalangeal joint and changes the alignment of the foot.
1. A method for treating a patient, comprising:
providing an inflatable subtalar implant;
inserting said implant into the sinus tarsi of a foot; and
inflating said implant with an inflation material.
2. The method of
3. The method of
4. The method of
5. The method of
6. The method of
7. The method of
8. The method of
9. The method of
10. The method of
11. A method for treating a patient, comprising:
providing an inflatable subtalar implant;
identifying a foot having a first range of motion;
inserting said implant into the sinus tarsi of said foot; and
adapting said foot to a second range of motion by inflating said implant.
12. A method for treating a patient, comprising:
providing an inflatable subtalar implant;
identifying a foot having a first weight-bearing alignment;
limiting said foot to a second weight-bearing alignment;
inserting said implant into a sinus tarsi of a foot; and
securing said foot in said second weight-bearing alignment by inflating said implant.
13. The method of
14. The method of
15. The method of
16. The method of
17. A minimally invasive method for treating a patient, comprising:
providing an inflatable subtalar implant;
inserting said implant into a sinus tarsi of a foot;
inflating said implant;
changing the range of motion of the subtalar joint of said foot; and
conforming the implant to the shape of the sinus tarsi thereby.
18. A method for treating a patient, comprising:
identifying a cyma line in a foot of a patient;
smoothing said cyma line; and
securing said smoothing by inflating an implant in the sinus tarsi of said foot.
19. A method of treating a patient, comprising the steps of:
accessing a sinus tarsi of a foot through an access path having a cross sectional diameter of no more than about 0.5 inches, the sinus tarsi having a talus and calcaneus spaced apart by a first minimum distance;
increasing the space between the talus and calcaneus to a second minimum distance; and
restraining the talus and calcaneus at said second minimum distance.
20. A method for treating a patient, comprising:
providing an inflatable first metatarsal-phalangeal joint implant;
inserting said implant into a first metatarsal-phalangeal joint of a foot; and
inflating said implant with a fluid.
21. A subtalar joint implant, comprising:
an inflatable balloon adapted for positioning in the sinus tarsi of a foot.
22. A foot implant, comprising:
an inflatable balloon, wherein said inflatable balloon is adapted for extra-articular positioning in the sinus tarsi of the foot.
The present application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 60/549,767 filed on Mar. 3, 2004, the disclosure of which are incorporated by reference herein in its entirety.
1. Field of the Invention
This invention relates generally to the field of subtalar joint and first metatarsal-phalangeal implants for treating foot conditions including flat feet, adult posterior tibial tendon dysfunction and metatarsophalangeal joint dysfunction.
2. Description of the Related Art
Pes valgo planus, or flat foot, is a common condition where the arch of a foot is weakened and is unable to properly support the weight of the body. With a flat foot, shock absorption is reduced and misalignment of the foot occurs. These changes may eventually result in foot and ankle pain, tendonitis, plantar fasciitis and hallux valgus, hallux limitus and functional disorders of the knees, hips and back. Although there are several causes of flat feet, one frequent cause is excessive motion in the subtalar joint of the foot.
As early as 1946, surgeons have been attempting to apply the arthroereisis concept to the subtalar joint. Arthroereisis is a surgical procedure for limiting motion in a joint in cases of excessive mobility. One early method was to remedy abnormal excursion of the talus on the calcaneus with the talus contacting the floor of the sinus tarsi by using an “abduction block” procedure. During the abduction block procedure, a wedge-shaped bone graft was impacted into the anterior leading edge of the posterior facet of the calcaneus. Impacting such a bone graft prevented excessive inferior displacement of the talus upon the calcaneus, thus limiting the amount of excess pronation of the subtalar joint.
A pronation limiting osteotomy in the form of a lateral opening wedge of the posterior facet was developed for treatment of “flatfoot” in cerebral palsy patients in 1964. In order to prevent interfering with subtalar joint motion, a wedge-like bone graft was used to improve the weight-bearing alignment of the calcaneus. In 1970, an accessory bone graft placed in the sinus tarsi was developed as a corrective procedure. Later, the bone graft was replaced with a silastic plug. As early as 1976, a high molecular weight polyethylene plug was developed. The plug is cemented into the calcaneal sulcus against a resected portion of the posterior calcaneal facet. This procedure, known as “STA-peg” (subtalar arthroereisis-peg), is a commonly used subtalar joint arthroereisis procedure. STA-peg does not block excessive pronation, but rather alters the axis of motion of the subtalar joint.
In addition, in 1976, a high molecular weight, polyethylene, threaded device known as a “Valenti Sinus Tarsi Arthroereises Device” was invented. The procedure used to implant the Valenti device is commonly referred to as the “Valenti” procedure. Unlike the STA-peg procedure, the Valenti procedure is an extra-articular procedure that involves placing the Valenti device into the sinus tarsi to block the anterior and inferior displacement of the talus. Such placement of the Valenti device does not restrict normal subtalar joint motion, but does block excessive pronation and resulting sequelae. The Valenti device has a frusto-conical shape and threads on the outer surface of the device, which allow it to be screwed into the sinus tarsi. Because of the shape of the Valenti device, the greater the penetration of the device into the sinus tarsi, the more the sinus is dilated and the more calcaneal eversion is eliminated.
However, several problems reduce the desirability of the Valenti procedure and device. Because of its frusto-conical shape and the manner in which it is inserted, the Valenti device is difficult to precisely position in the subtalar joint and difficult to ensure that the proper amount of calcaneal eversion has been eliminated. Furthermore, it is generally difficult to locate the device properly within the tarsal canal because the implant must be threaded at least 3 to 5 millimeters medial to the most lateral aspect of the posterior facet for correct placement. Because of its polyethylene construction, the device cannot be imaged using radiography (X-ray) to determine whether the proper position has been achieved.
More recent attempts to control subtalar motion in the hyperpronated foot include the Maxwell-Brancheau arthroereisis (MBA), the Kalix subtalar prosthesis and the Futura arthroereisis. The MBA is a titanium alloy implant where the implantation procedure involves insertion “trial” implants to determine the proper size of the actual implant used. The MBA implant procedure requires either general anesthesia or local anesthesia with sedation. It also requires up to a ¾ inch incision on the lateral portion of the foot. The MBA implant uses a metal guide pin for positioning the implant. The guide pin must be positioned with extreme care to prevent damage to the calcaneus. A two-week period of crutch use and foot immobilization typically follows the procedure. The Kalix implant is a cone-shaped implant with limited expansion ability. The operator can use a double screwdriver to increase the diameter of the implant. The Kalix implant requires two weeks of non-weight bearing and three to four weeks of immobilization following implantation of the device.
Another site of frequent foot problems is the first metatarsal-phalangeal joint. The first metatarsal-phalangeal joint (MTP) is a complex joint of the foot where bones, tendons and ligaments work together to transmit and distribute the body's weight, especially during movement. Bunions are the first MTP joint disorder most frequently treated by podiatric surgeons. First-line treatment involves educating patients about the condition and evaluating their footwear. Providers can direct their patients to wear wider, low-heeled shoes, use bunion pads, apply ice and take over-the-counter analgesic medications. These options are designed to relieve pain and make it easier to walk and engage in physical activities, but they do not address the underlying cause of bunions.
Bunions usually occur from inherited faulty biomechanics that put abnormal stress on the first MTP joint. Contrary to popular belief, bunions are aggravated, not caused, by shoes. Various non-surgical approaches can help prevent aggravation of bunions and other MTP-related problems. For some patients, non-surgical treatment is sufficient, but surgical intervention is considered if the bunions are progressive or if non-operative treatments provide inadequate improvement.
Bunion surgery is performed to repair tendons and other soft tissue and remove a small amount of bone. Procedures to correct more severe bunions may involve removal of the bump or minor realignment of the big toe joint. The most severe and disabling bunions often require extensive joint realignment, reconstruction, implants or joint replacement. Significant morbidity and recuperation time is required for such procedures.
First MTP-related problems also occur from repetitive trauma to the area and from arthritis. Over time, active persons can put continuous stress on the first MTP joint that eventually wears out the cartilage and lead to the onset of arthritis. This condition, known as hallux rigidus, causes loss of movement and pain in the joint. In most situations, non-operative treatments can be prescribed to provide relief, but those with advanced disease might need surgery, especially when the protective covering of cartilage deteriorates, leaving the joint damaged and with decreased range of motion. Again, significant morbidity results from these procedures and an extended recovery time is required.
In one embodiment, the invention is a subtalar joint implant, comprising an inflatable balloon adapted for positioning in the sinus tarsi of a foot. In another embodiment, the invention is a foot implant comprising an inflatable balloon, wherein the inflatable balloon is adapted for extra-articular positioning in the sinus tarsi of the foot.
In one embodiment of the invention, a method for treating a patient is provided. The method comprises providing an inflatable subtalar implant for the procedure, inserting the implant into the sinus tarsi of a food, inflating the implant with an inflation material and changing the alignment of the hindfoot. Furthermore, the insertion of the implant into the sinus tarsi may be performed through a cannula inserted into the sinus tarsi. The inflation material may be a fluid or a solid. One example of a solid inflation material are microspheres. In other embodiments of the invention, multiple agents may be used to inflate the implant, such as a substrate and catalyst capable of solidifying. In some embodiments, the multiple agents are combined before inflation of the implant. In other embodiments, the multiple agents are combined during inflation of the implant.
In another embodiment of the invention, another method for treating a patient is provided. This method comprises providing an inflatable subtalar implant for the procedure, identifying a foot having a first range of motion, inserting the implant into the sinus tarsi of the foot and adapting the foot to a second range of motion by inflating the implant.
In still another embodiment of the invention, another method for treating a patient is provided. This method comprises providing an inflatable subtalar implant, identifying a foot having a first weight-bearing alignment, changing the foot to a second weight-bearing alignment, inserting the implant into the sinus tarsi of the foot and securing the foot in the second weight-bearing alignment by inflating the implant. The first and second weight-bearing alignments may be defined by the angle formed between a first line connecting the edges of an articular surface of the talus and a second line connecting the edges of an articular surface of a navicular bone. Alternatively, the first and second weight-bearing alignments may be defined by the angle between the long axis of the talus and a second line along the long axis of the first metatarsal bone. Still another alternative is to define the first and second weight-bearing alignments by the angle between the first line between most plantar point of a calcaneus and the most inferior point of the distal articular surface of the calcaneus, and a second line within a horizontal plane of the patient. Still another alternative is to define the first and second weight-bearing alignments by the angle between a first line along the plantar border of the calcaneus and a second line along a first midpoint in the body of a talus and a second midpoint in the neck of the talus.
Several embodiments of the invention provide a minimally invasive method for treating a patient. This method comprises providing an inflatable subtalar implant, inserting the implant into the sinus tarsi of a foot, inflating the implant, changing the range of motion of the subtalar joint of the foot and conforming the implant to the shape of the sinus tarsi thereby.
Some embodiments of the invention provide a method for treating a patient, comprising identifying a cyma line in a foot of a patient, smoothing the cyma line and securing the smoothing by inflating an implant in the sinus tarsi of the foot.
In another embodiment of the invention, a method for treating a patient is provided, comprising accessing the sinus tarsi of a foot through an access path having a cross sectional diameter of no more than about 0.5 inches, where the sinus tarsi have a talus and calcaneus spaced apart by a first minimum distance. The space between the talus and calcaneus is increased to a second minimum distance and the talus and calcaneus is then restrained at the second minimum distance.
In another embodiment, another method for treating a patient is provided, comprising providing an inflatable first metatarsal-phalangeal joint implant, inserting the implant into a first metatarsal-phalangeal joint of a foot and inflating the implant with a fluid.
Several embodiments of the invention provide these advantages, along with others that will be further understood and appreciated by reference to the written disclosure, figures, and claims included herein.
The structure and method of making the invention will be better understood with the following detailed description of embodiments of the invention, along with the accompanying illustrations, in which:
The talus and calcaneus form the bones of the hindfoot. The talus is a bone with no muscular attachments, but is stabilized by ligaments and cradled by the tendons passing from the leg to the foot. As shown in
Subtalar motion is generally described as a rotational motion of the talus around the calcaneus.
When an excessive range of motion exists in the subtalar joint, misalignment of the foot can occur. Compared to a person with a neutrally aligned foot, shown in
Alignment of the foot can be assessed on plain film x-ray imaging by examining the cyma lines of the foot. The term “cyma line” refers to the joining of two curved lines. A neutrally aligned foot forms a smooth cyma line (shown with dots) between the talonavicular joint and the calcaneocuboid joint on radiographs in both the lateral and AP views, as shown in
Other radiographic methods of assessing foot alignment are also available.
Accordingly, one embodiment of the present invention provides an implant 60 which can be easily located within the tarsal canal, which may or may not deform under post-operative compressive forces, which would ensure that the desired amount of calcaneal eversion has been provided after insertion of the implant 60 and which can be imaged using radiography to determine whether the implant has been properly positioned during the procedure. By placing a device into the tarsal space between talus 10 and calcaneus 2, hindfoot motion and stability may be favorably modified. Such a device may further provide midfoot stability because midfoot-stability is co-dependent on hindfoot stability. Dysfunction of the posterior tibial tendon that supports the foot arch may also be treated by restoring the arch of the foot and relieving the excessive tension on the tendon.
By developing a minimally invasive, catheter-deliverable subtalar implant, disruption of the joint capsule and the ligamentous structures in and around the lateral portion of the foot can be reduced. Current subtalar implants require either transection of the ligaments overlying the sinus tarsi or the dilation of an opening up to about 3/4 inch diameter through the ligaments. Dilation of this magnitude will stretch and disrupt the ligaments. In general, the implant in accordance with the present invention may be advanced through a tissue opening of no greater than about 7 mm, and preferably no greater than about 2 mm to about 3 mm.
The development of an inflatable, non-metallic implant will allow the creation of an in-situ customized prosthesis that will also minimize trauma to the surrounding tissue during the implantation procedure and with long-term use. This will considerably shorten the postoperative recuperation period compared to existing devices and reduce postoperative pain and swelling. Moreover, because the integrity of the tissue overlying the sinus tarsi is preserved through minimally invasive implantation, the intact tissue is able to assist in anchoring the implant in the sinus tarsi. By customized, the inventor contemplates an implant that is at least partially conformable to the anatomical cavity in which it resides, at least prior to any polymerization or other curing step.
In one embodiment of the invention, illustrated in
Generally, the area of the lateral-proximal surface 68 of the implant will be at least about twice the cross-sectional area of the dilated tissue access tract. Often, the lateral surface area will be at least 5×, 8×, 10× or 20× or more than the access tract to resist migration of the implant.
In another embodiment, the implant is semi-customizable. The surgeon is able to limit certain dimensions or features of the semi-customizable implant by selecting a balloon having a shorter length, diameter and/or volume. The implant shape is further adjusted by allowing a variable degree of inflation. Variable inflation may allow deeper positioning of the implant within the sinus tarsi by providing implant 60 with a smaller diameter for deeper insertion into the narrow tarsal canal.
In still another embodiment, the implant shape is preselected by the surgeon. The implant is compressible onto a catheter for minimally invasive delivery, but assumes a preconfigured shape with inflation. A preconfigured shape may be advantageously used to force a particular foot alignment or to facilitate anchoring of the implant. One indication for this implant and procedure is the hyperpronated, flexible and reducible flatfoot. The most common patient with this indication is pediatric, but adults with posterior tibial tendon dysfunction or hyper-pronation in the absence of subtalar joint and mid tarsal joint arthritis are also eligible.
The outer surface 90 of implant 60 may be smooth, textured or comprise any of a variety of protrusions or indentations to reduce the risk of implant migration.
If more aggressive anchoring of the implant is desired, the inflatable member may be further configured to facilitate attachment of implant 60 to soft tissue or bone. In one embodiment, sutures, clips, staples, tacks, pins, hooks, barbs, or other securing structures that can at least partially penetrate the surrounding tissue or bone are used. These securing structures may be made from a variety of materials, including metals, polymers, ceramics or absorbable materials. Absorbable materials include but are not limited to polylactic acid (PLA) or copolymers of PLA and glycolic acid, or polymers of p-dioxanone and 1,4-dioxepan-2-one. A variety of absorbable polyesters of hydroxycarboxylic acids may be used, such as polylactide, polyglycolide and copolymers of lactide and glycolide, as described in U.S. Pat. Nos. 3,636,956 and 3,297,033, which are hereby incorporated in their entirety herein by reference. The use of absorbable materials allows the securing structure to dissolve or resorb into human tissue after a known or establishable time range, from a week to over a year.
In one non-limiting example, shown in
In one embodiment of the invention, implant 60 comprises any of a variety of flexible materials that resist stretching. These materials include but are not limited to polyethylene, polyolefins, polyvinyl chloride, polyester, polyimide, polyethylene terephthalate (PET), polyamides, nylon, polyurethane and other polymeric materials. One skilled in the art can select the material based upon the desired compliance, biocompatability, rated burst pressure and other desired characteristics. In one embodiment, the inflatable member has a wall thickness of about 0.001 cm to about 0.05 cm. In another embodiment, the inflatable member has a thickness of about 0.02 cm to about 0.03 cm. Generally, the inflatable member has a rated burst pressure of greater than 60 atmospheres (ATM) for resisting bursting and extrusion of inflation material under physiologic loading. In another embodiment, the inflatable member has a rated burst pressure of at least about eight ATM or more. A lower burst pressure can be used where a curable material is used to inflate the inflatable member and will bear the loading of the subtalar joint. In a further embodiment of the invention, implant 60 is integrally formed with deformable wire supports within the material used to form the inflatable member. One possible function of the wire support to provide some stiffness to the implant during the insertion process to allow the operator to insert the implant into distal sulci or crevices of the sinus tarsi. A wire support can also comprise a shape memory metal, such as nitinol. Upon insertion of the implant into the sinus tarsi, the body heat of the patient will cause the wire support to change shape and expand to the borders of the sinus tarsi. Those skilled in the art understand that any of a variety of biocompatible, deformable metals may be used to form the skeleton.
In addition to providing access to inflate the inflatable compartment, the inflation port may comprise other features to facilitate use of the implant. The inflation port may be self-sealing or have a one-way valve to obviate the need for a separate sealing of the implant after inflation. Valve configurations include but not limited to hemostatic-type valves, flap valves or duckbill valves. In some embodiments, a pierceable septum may be used. A flap valve 100 is shown in
The material used to inflate inflatable compartment 62 includes any of a variety of biocompatible materials, including but not limited to saline, silicone polymers, polyurethane polymers, linear or branched polyols, PMMA or others known in the art. Solid materials, such as small polymeric metallic microspheres, microtubules or microdiscs can also be used as a filling agent. The material can also be a combination of materials, such a curable liquid substrate and a catalyst, that can solidify within implant 60. Several U.S. patents disclose various types of polymers or proteins that, assertedly, can be injected into a joint as a liquid or semi-liquid composition that subsequently harden into a solidified material. For example, U.S. Pat. No. 5,556,429 (Felt 1996), herein incorporated by reference, discloses injection of a fluidized mixture of a biocompatible polymer (such as a silicone or polyurethane polymer) and a biocompatible “hydrogel” (a hydrophilic polymer, formed by steps such as using an agent such as ethylene dimethacrylate to cross-link a monomer containing a hydroxyalkyl acrylate or methacrylate), into a space. After injection, the polymer and hydrogel mixture can be set into solidified form by means such as ultraviolet radiation, which can be introduced into the space by a fiber optic device. Other articles on surgically implantable polymers is contained in numerous published items; recent review articles include Peppas et al 1994, Hubbell 1995, Stokes 1995, Burg et al 1997, Lewis 1997, Kim and Mooney 1998, and Ambrosio et al 1998, herein incorporated by reference. Other discussions of biocompatible implantable materials are also available in various textbooks, such as Silver 1994, herein incorporated by reference. Other combinations of inflation materials may include the addition of iodine, barium or other radio-opaque component. One skilled in the art can select the desired material based upon the viscosity, density, cure time, degree of exothermic cure reaction, radio-opacity and other characteristics. For curable materials, one skilled in the art may consider the load-bearing strength, tensile strength, shear strength, fatigue, impact absorption, wear characteristics and other factors of the cured material.
In another embodiment, implant 60 has multiple inflation ports and multiple compartments such that different portions of implant 60 can be independently inflated.
Implant 60 further comprises a coupling interface 108 that releasably attaches implant 60 to the delivery system. Coupling interface 108 is generally located on or about inflation port 66 and allows for inflation of implant 60 through the delivery system without leakage of material into the surrounding tissue. Coupling interface 108 also allows transmission of force, including torque, from the delivery system to the implant to facilitate positioning of implant 60. Coupling interface 108 is configured to allow detachment of implant 60 from the delivery system and, optionally reattachment of the delivery system.
One embodiment of the delivery system is illustrated in
Sizing catheter 124, shown in
Alternatively, sizing balloon 126 may comprise a high-compliance material that is capable of conforming to the surrounding anatomical structures. By filling sizing balloon 126 with a radio-opaque fluid under fluoroscopy or with radiography, the surgeon can determine the proper three-dimensional shape and of the cavity 26. An implant 60 can be selected to correspond with the predetermined shape and/or size.
In an alternative embodiment of the delivery system, sizing catheter 124 is omitted because the inflation characteristics of the implant allow implant 60 to be adapted to structural variations of the anatomy. Selection of a particular size or shape of implant is not required in this alternative embodiment. In this embodiment, the surgeon can partially inflate the implant, evaluate the effect on the foot alignment and flexibility, and continue to inflate, deflate and/or position the implant until a desired result is achieved. The delivery catheter 114 may then be detached and withdrawn, leaving the implant 60 in place.
Distal end 144 of delivery catheter 114 comprises an inflation lumen 158 and a coupler for attaching to coupling interface 108 of implant 60. In the embodiment of the invention seen in
If outer sheath 146 is further extended, inner surface 150 of sheath 146 will contact base 116 of coupling interface 108. Base 116 of implant 60 has a polygonal cross-section capable of forming a mechanical interfit with a polygonal cross-section of inner surface 150 of outer sheath 146. Distal portion 156 of sheath 146 will also exert a distally directed counterforce on implant 60 in opposition to the proximally directed force on the implant from the prongs 112 to firmly attach implant 60 to the delivery catheter 114. If sheath 146 is retracted, the mechanical interfit with base 116 is relieved and radially inward forces on prongs 112 are removed. Prongs 112 will resume their outward bias and distract from flange 110 of implant 60, causing release of implant 60. As previously mentioned, delivery catheter 114 shown in
In the embodiment of implant 60 shown in
In an alternative embodiment of the delivery system, a guidewire or guide pin having a diameter of about 0.010 inch to about 0.038 inch and a length of about four inches to about eight inches is provided for insertion into the sinus tarsi. The guidewire is insertable through a needle inserted into the sinus tarsi. The needle is withdrawn after the guidewire is positioned. An introducer may be passed to further dilate the passage to the sinus tarsi. The sizing and delivery catheters are adapted for passage over the guidewire into the sinus tarsi. In this embodiment, both catheters would each have at least two lumens. One lumen is used to pass the catheter over the guidewire and the other lumen would be used to inflate the sizing balloon or implant. These lumens may be oriented in a dual concentric configuration or adjacent to each other.
One indication for this embodiment of the implant and implantation procedure is a reducible, hyperpronated, flexible flatfoot. These patients are commonly pediatric, but adults with posterior tibial tendon dysfunction and/or hyper-pronation in the absence of subtalar joint and mid tarsal joint arthritis are also potential candidates.
In an alternative implantation procedure, the material used to inflate implant 60 to the desired volume is removed from the implant and its volume is measured. An equal or similar volume of another material having a different density or characteristics is used to reinflate the implant. This alternative procedure may be used to obtain a more accurate measurement of the sinus tarsi and the volume of final inflation material to be used where the final inflation material changes volume as it cures. The volume of the initial fluid used to assess the sinus tarsi is used to calculate the volume of uncured final inflation material to be delivered.
In another alternate method of implanting the device using a guidewire, the patient is placed on a table and the lateral side of the foot is draped in the usual sterile fashion known in the art. The insertion site for the device is identified by palpation of bony markers, including but not limited to the fibular head, cuboid, talus and calcaneus bones. Local anesthesia is injected into the skin and connective tissue overlying the insertion site. Anesthetics with epinephrine may be used to limit bleeding at the insertion site. A large bore needle is inserted at the desired site and a guidewire is passed through the needle. Optionally, a small dilator is passed over the guidewire for enlarging the pathway to the sinus tarsi. The foot with the inserted guidewire is radiographically imaged to confirm positioning of the guidewire in the sinus tarsi. A catheter with the inflatable implant at the catheter tip is passed over the guidewire and into the sinus tarsi. The implant is inflated to the desired volume. The talo-calcaneal relationship is checked by physical exam and/or radiographic imaging. The inflation volume of the implant may be adjusted based upon the results of the exam and/or the imaging until the desired talo-calcaneal position is achieved. The surgeon may use the cyma line, in contradistinction to an anterior displaced talo-navicular joint, as an indication that a pronated foot has been reduced to a more neutral alignment. The delivery catheter is detached from the implant and both the catheter and guidewire are withdrawn from the patient. The insertion site is closed by either suturing or adhesives and dressed.
The implant and delivery system described above can also be adapted for insertion into the first MTP joint of the foot. Referring to
While this invention has been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention. For all of the embodiments described above, the steps of the methods need not be performed sequentially.