A complete system designed specifically for replacing the
base of the proximal phalanx. This complete system contains everything the surgeon will need to perform the replacement procedure. Vilex introduced the first cannulated hemi implant,
CHI, to the orthopedic and podiatry surgeons.
*Patent Pending
Introduction
Vilex
offers two types of cannulated hemi implants, CHI™: elliptical and
concave to replace the base of the proximal phalanx and spherical and convex to
replace the head of a metatarsal. Ten concave and ten convex sizes
are available to replace the first or lesser joints. Each CHI is
individually machined. The articular surface is mirror finished to
minimize friction and shaped to maintain range of motion without
inducing pain or altering the foot biomechanics. However, under no
circumstance should both ends of a joint be replaced. Without any
condition or equivocation Vilex does not recommend the replacement
of both the base of the phalanx and the metatarsal head of the same
joint.
The cannulation provides a mechanism for precise positioning of the implant. A special driver is used to screw the implant into the desired position. The two positioning holes provide a mechanism for suturing (optional) the implant to the soft tissue while osseous integration proceeds naturally.
Indications
• Hallux limitus, hallux
rigidus, or stiff joint.
• Pain due to impacted joint.
• Joint
deterioration.
Contraindication
• Osteoporotic or poor bone stock
• Inadequate skin or
musculotendinous system
• Unrealistic patient expectations
• Poor overall patient health
• History of bone infection
• Poor or inadequate neurovascular status
Features
• Anatomically compatible
• Elliptical/spherical shape
for articular surface
• Cannulation for precise positioning
• CoCrMo or titanium
Before Proceeding
The surgeon
should evaluate the overall health of the patient. An implant site
may become infected, painful, swollen, or inflamed. The status of
the adjacent bone and soft tissue may be inadequate to support the
implant, resulting in instability, deformity, or both.
The
benefits from implant surgery may not meet patient's expectations or
may deteriorate with time, requiring revision surgery, which is
common with implants. Vilex does not recommend a particular
surgical procedure. The information and protocol provide an
approach and not a required procedure.
Typical 1st MPJ Procedure
A
longitudinal incision is made on the dorsal aspect of the MPJ or PIP
joint. The incision is deepened to the level of the joint, with
sharp and blunt dissection while avoiding the exterior tendon, and
the vital structures are retracted. A longitudinal capsulotomy is
performed and the joint is resected free. All hypertrophic bone is
resected from both the metatarsal and phalanx. The recipient bone is
completely freed of its attachments on the medial, dorsal, and
lateral aspects.
Depending on the condition of the joint, the surgeon has the option to replace either the head of the metatarsal or the base of the phalanx, but not both. If both ends are equally damaged, Vilex recommends the replacement of the base of the phalanx. If the metatarsal head is not salvageable, the head should be replaced.
For conventional first MPJ hemi implants, the base of the proximal phalanx is resected at the appropriate level. The resection line should bypass any tendon or critical tissue. The cut should be neutral without lateral or medial orientation.
A slight dorsal-plantar inclination is desirable. The width of the resected bone should be 4-5mm to allow room for the implant and to decompress the joint. If the metatarsal head is being replaced, again make a neutral cut and remove 1-1.5mm beyond the width of the implant (see table below), which ranges between 4 and 5mm.
After the base or metatarsal head is resected, a trial sizer (elliptical) is placed over the exposed surface to determine the correct size of the prosthesis. The sizer should cover the entire surface without protruding beyond the bone. With the sizer in position, manually insert a K-wire to mark the center. Remove the sizer and drive the wire into the phalanx, making sure the wire is in the center of and parallel to the axis of the proximal phalanx. Insert the implant over the K-wire and drive the implant into the intramedullary canal. The surgeon may adjust the orientation of the implant by turning it as much as one half turn.
For metatarsal head replacement, a trial sizer (circular) is placed over the metatarsal to determine the correct size. With the sizer in position, manually insert a K-wire to mark the center. Remove the sizer and drive the wire into the metatarsal shaft, making sure the wire is in the center of and parallel to the axis. Insert the implant over the K-wire and drive the implant into the intramedullary canal.
Lesser-Joint Procedures
The procedure for lesser joints is very similar to the first MPJ, except that the implants are smaller and the amount of bone resected is 2-2.5mm for either end. After the implant is seated and the range of motion checked, the joint capsule is closed over the prosthesis and sutured with a suture of the surgeon's choice. Bandaging and post-operative management corresponds to other arthroplasty procedures.
Post-Operative Considerations
Patient
should be warned that the prosthesis device is not a substitute for
the natural joint and will not enable the patient to function as if
the joint is restored. The patient should avoid an active lifestyle.
Excessive motion will accelerate the unavoidable wear and tear of
the implant and may loosen the prosthesis. Serious consequences such
as fracture or shattering of the bone, metal fatigue, or dislocation
of the device
are possible.
Precautions
The
implants are provided non-sterile. Sterilize the implants in their
tray as you would any bone screw. Steam sterilization at 270°F for
20 minutes is recommended. Implants should only be handled with
blunt instruments to avoid scratching, cutting, or nicking the
device. Meticulous preparation of the implant site and selection of
the proper size implant increase the potential for successful
outcome.
Adverse Results
Potential
adverse events reported with toe joint prostheses include pain,
loosening, fracture, dislocation, or infection. There have been some
reports of patients with allergic reaction to certain metals.
Implantation of materials such as cobalt chrome and/or titanium may
result in foreign body reaction in tissue adjacent to the implant
site. Injury to the surrounding nerves, blood vessels, tendons, or
soft tissues can occur as a consequence of implanting this
device.
Limited Warranty
Vilex warrants
that this product meets the manufacturer's specifications and is
free from manufacturing defects at the time of delivery. This
warranty specifically excludes defects resulting from misuse or
abuse. Surgery involving Vilex small joint implants may be performed
solely by qualified foot surgeons in a normal hospital setting.
Available Hemi Sizes
| Product Number | D | Stem Length | Stem D | Thick |
|---|---|---|---|---|
| Lesser Joint: Titanium Only | ||||
| MCHI-09 | 9.0 | 11.5 | 2.5 | 0.8 |
| MCHI-10 | 10.0 | 11.5 | 3.0 | 0.8 |
| MCHI-11 | 11.0 | 12.0 | 3.0 | 0.8 |
| MCHI-12 | 12.0 | 12.0 | 3.0 | 0.8 |
| MCHI-13 | 13.0 | 12.0 | 3.0 | 0.8 |
| First MPJ: Titanium or CoCr, (Cobalt Chrome) Oval | ||||
| CHI-1 | 13 x 15 | 9.0 | 6.5 | 1.0 |
| CHI-2 | 15 x 17 | 10.0 | 6.5 | 2.0 |
| CHI-3 | 17 x 19 | 11.0 | 7.5 | 2.1 |
| CHI-4 | 19 x 22 | 12.0 | 7.5 | 2.2 |
| CHI-5 | 21 x 24 | 13.0 | 7.5 | 2.3 |
Available Met Head Sizes, all CoCr (Cobalt Chrome)
| Product Number | D | Stem Length | Stem D | Thick |
|---|---|---|---|---|
| Lesser Joint | ||||
| MMCI-09 | 9.0 | 11.5 | 2.5 | 3.0 |
| MMCI-10 | 10.0 | 11.5 | 3.0 | 3.0 |
| MMCI-11 | 11.0 | 12.0 | 3.0 | 3.0 |
| MMCI-12 | 12.0 | 12.0 | 3.0 | 3.0 |
| MMCI-13 | 13.0 | 12.0 | 3.0 | 3.0 |
| First MPJ | ||||
| CMHI-14 | 14.0 | 8.0 | 6.5 | 4.0 |
| CMHI-16 | 16.0 | 10.0 | 6.5 | 4.0 |
| CMHI-18 | 18.0 | 12.0 | 7.5 | 5.0 |
| CMHI-20 | 20.0 | 13.0 | 7.5 | 5.0 |
| CMHI-22 | 22.0 | 14.0 | 7.5 | 5.0 |
Download Reorder Forms
FDA Authorization
Click on the link below to go to the United States Department of Health and
Human Services FDA 510(k) website.
Limited Warranty
Vilex warrants that this product meets the manufacturer's specifications and is free from manufacturing defects at the time of delivery. This warranty specifically excludes defects resulting from misuse, abuse or improper handling of the product subsequent to receipt by the purchaser. Vilex does not warrant the outcome of the surgical procedure.
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