USE OF A HINGED SILICONE PROSTHESIS FOR REPLACEMENT ARTHROPLASTY OF THE 1ST METATARSOPHALANGEAL JOINT

A series of ninety consecutive total joint replacements of the first metatarsophalangeal joint with a flexible hinged prosthesis was reviewed after an average duration of follow-up of three years (range, twenty-four to sixty-one months). Although subjectively the results were satisfactory in most of the patients, and pain, the most common preoperative symptom, was reduced, mechanical failure of the implant was common, as determined radiographically. The frequency of failure of the implant and the extent to which it failed were related to the length of time that the implant had been in place. The range of motion of the metatarsophalangeal joint was decreased from normal. Dorsiflexion averaged 26 degrees and plantar flexion, 18 degrees. Callosities under at least one metatarsophalangeal joint were noted in fifty (69 per cent) of the feet that had a physical examination. Pedobarographic analysis of the distribution of plantar pressure revealed that none of the patients exerted weight-bearing pressures on the affected great toe. However, the subjective results were not significantly associated with radiographic evidence of failure of the implant. Despite its success in relieving the symptoms in our patients, we have abandoned this procedure because of the high and increasing rate of failure of the implant, as demonstrated radiographically.