A REABSORBABLE SPACER FOR THE FIRST METATARSO-PHALANGEAL JOINT IN THE SURGICAL TREATMENT OF HALLUX RIGIDUS.

Abstract

Implantation of metatarso-phalangeal prostheses or spacers has been widely indicated for the replacement of the articular surfaces in severe hallux rigidus.

A reabsorbable device in poly(D-L-lactic acid) (PDLLA) which is dome-shaped with a stem for implantation into the first metatarsal, avoiding any resection of the base of the proximal phalanx, is proposed.

The rationale of the reabsorbable spacer is to maintain the distance between the articular surfaces and provide a sliding surface suitable for articulation. It is then reabsorbed and replaced by fibrous tissue, which allows motion and removes pain.

37 reabsorbable spacers have been inserted for severe hallux rigidus in 33 patients aged from 26 and 76 years (average 58). Patients were reviewed with a follow-up ranging between 36 and 96 months (average 59.5).

The results were assessed using the American Orthopaedic Foot and Ankle Society (A.O.F.A.S), hallux-metatatarsophalangeal-interphalangeal scale.

Anteroposterior and lateral weight-bearing X-rays were made preoperatively and at follow-up, evaluating the dimensions of the articular space and the length of the first metatarsal.

The chronology of device reabsorption was studied in 10 patients with M.R.I., assessing complete reabsorption within 4 months of the operation.

Excellent and good results were obtained in 91% of patients. The A.O.F.A.S. score was 43.7+/−20.6 pre-operatively and 82+/10.3 post-operatively.

The reabsorbable spacer confirmed the expectations of its protagonists. This procedure would appear to be an alternative to arthrodesis of the first metatarso-phalangeal joint or traditional permanent implants, and represents an intermediate technique between an implant and resection arthroplasty.