[Interpositioned metallic prosthesis for hallux rigidus: review of 42 cases with a metatarsophalangeal prosthesis]

We report outcome at a mean 4.8 years follow-up in 42 patients with hallux rigidus treated by metatarsophalangeal interposition thin prosthesis flat concave with a lateral capsular fixation.

The 42 patients were treated from 1987 to 1997. Sixtine prostheses were implanted for osteoarthritis was grade I (n=2), grade II (n=28), and grade III (n=12). Groulier's clinical criteria and Regnauld's radiologic criteria were used to assess outcome.

We observed 22 very good, 12 good, 4 fair, and 4 poor results. There was no significant modification in the forefoot morphology.

The Sixtine prosthesis provided a global improvement in pain and motion though there was an important difference between patients with grade I and grade II osteoarthritis, who experienced major improvement, and those with grade III disease. A good overall result requires proper prosthetic centering. Subluxation or translation does not appear to be compatible with good results. Among 3 cases with overt dislocation, 1 recovered an acceptable articular space with a good overall result. Two poor results and 3 fair results were observed in patients with condensation of the phalangeal base. These bone condensations appeared in postoperative Egyptian feet. The Sixtine prosthesis may protect the interphalangeal articular space of the great toe, avoiding damage and rearward displacement of sesamoid bones. It ensures primary stability and may be left in place.

We found that the Sixtine prosthesis is best indicated in hallux rigidus patients with grade II osteoarthritis.