How To Treat Osteoarthritis Of The First MTPJ
Step-By-Step Insights On Performing The Hemi-Toe Implant Arthroplasty
To begin this procedure, you would start with a standard dorsal medial incisional approach. This not only facilitates joint exposure but allows you to preserve the joint capsule, which facilitates remodeling of the first metatarsal head including the resection of lateral and dorsal bone spurs. It is essential to release and mobilize the medial, lateral and plantar fibrous adhesions for intraoperative joint mobilization. Doing so enables you to use the instrumentation for placing the implant.
I find the McGlamry elevator invaluable in performing the soft tissue release and minimizing the amount of soft tissue dissection and trauma to that area. A good release will increase the first metatarsophalangeal joint space and allow for better exposure for soft tissue reflection at the base of the phalanx as you prepare for bone resection.
Proceed to perform a 5-mm to 10-mm resection at the base of the proximal phalanx when you release the capsular attachments. Exercise care in the area under the phalanx base so you can prevent a possible release of the flexor brevis tendon. I perform conservative but adequate resection that maintains hallux length and minimizes damage to the flexor tendon.
You can resect additional bone later when using the reamer to remodel the contour of the base to match the implant after broaching the canal. I find that using a 2.7-mm drill instead of the pointed broach helps create a pilot hole in the center of the bone since the sclerotic base is difficult to penetrate. The triangular shape of the stemmed broach enables you to correctly orient the right and left side appropriate implant.
Bear in mind that you will need to use a mallet to seat the device. While the 2.7-mm drill requires less force in driving the broach into place in a sclerotic base, you still need to have resistance and a firm grip on the great toe in order to prevent excessive tension on the capsule structures. At this point, you can place the trial implant with the impactor and subsequently reevaluate the patient’s range of motion.
If you find the implant to be tight in the joint space, you can resect additional bone with a sagittal saw or the shallow reamer. You must follow this with the stem broach in order to facilitate full seating of the implant. Now you can place the LPT Hemi-Toe Implant. The implant will have one perforated hole at the dorsal surface and one at the plantar surface. This allows for right and left great toe placement where the flexor tendon can be reinforced or reattached at your preference. I have found that this is not a common part of the procedure I perform, given the low profile size of the implant.
I also prefer not to handle the implant any more than necessary in order to minimize intraoperative complications or the occasional mistake that requires a new implant.
What You Should Consider In The Post-Op Evaluation
Proceed to close the soft tissue and reevaluate the patient’s range of motion and joint stiffness along with his or her skin. Occasionally, I may evaluate the trial implant with capsule closure to ensure appropriate range of motion prior to implanting the permanent implant. Pre-op and post-op implant placement should demonstrate corrected hallux position and preserved toe length.
As in any procedure, there may be potential complications. These include:
• a lack of hallux purchase;
• fracture of the metatarsal head or base of the proximal phalanx;
• loosening of the prosthesis;
• osteolysis or osteoproliferation around the implant system;
• blockage of the hallucal sesamoid position;
• unmasking of preexisting sesamoid pathology;
• recurrence of the deformity; and
• painful/limited MTPJ range of motion.
Although silastic implant arthroplasty has been performed for nearly 40 years, the metallic implant devices present a new era for use in the arthritic joint. Appropriate patient selection is essential and the procedure can be successful when the first metatarsal head has a restorable contour and a corrected intermetatarsal angle with no unaddressed biomechanical abnormalities. The thinner anatomic articulate design of the implant allows for a smaller resection of the proximal phalanx base and preserves the flexor hallucis brevis tendon.