FIRST METATARSAL HEAD RESURFACING WITH A CONTOURED ARTICULAR PROSTHETIC

Abstract

Introduction: Advanced stages of first metatarsophalangeal (MTP) arthritis have traditionally been treated with resection arthroplasty or arthrodesis. Total- and hemiarthroplasty using various prosthetic replacements of the MTP joint, or phalangeal base, have been reported with variable success. A new metatarsal resurfacing system allows for intraoperative joint geometry mapping and placement of a contoured prosthetic.

Methods: Twenty-five patients with advanced stage hallux rigidus were included in this investigation and have undergone metatarsal head resurfacing (HemiCAP® Prosthesis, Arthrosurface Inc., Franklin, MA). The average age of the patients was 51 years. All patients were assessed with the Short Form 36 Health Survey (SF-36) and the American Orthopedic Foot and Ankle Society (AOFAS) clinical rating system for the Hallux, physical examination and radiographic evaluation. The average follow up was 20 months (range: 8 to 28 months).

Results: Postoperative passive dorsiflexion increased on average by 31 degrees from 34 degrees at baseline to 65 degrees at last follow-up. The mean AOFAS score improved from 44.1 to 82.1. The average SF-36 score improved from 81.2 to 96.1. The preoperative visual analogue pain score was reduced from 6.8 to 1.4 at last follow-up. No radiographic evidence of implant loosening, subsidence, or periprosthetic radiolucency has been found to date. No device failures have been encountered. All patients stated they would undergo the procedure again. One patient had a superficial wound break down which resolved with conservative care.

Conclusion: Although long term follow up is still necessary, the current results are very promising providing effective pain relief and improvement in range of motion. Proper implant placement does not affect the sesamoid groove. The procedure is performed with minimal joint resection and preserves viable bone stock, therefore conversion to arthrodesis or resection arthroplasty is possible should the need for further treatment arise.