Reduced Postoperative Functional Length Ratio Influences Patient Satisfaction in First Metatarsophalangeal Joint Replacement

Complications of first metatarsophalangeal joint metallic arthroplasty are well known. However, the resulting shortening of the metatarsals can lead to transverse metatarsalgia or medial column pain at the metatarsophalangeal joints by creating Morton's toe/foot, which increases pressure on the second metatarsal head. The effect of the functional length ratio of the first and second metatarsals on pain and patient satisfaction has not been rigorously evaluated. We evaluated the effect of the first/second metatarsal ratio on patient satisfaction with first metatarsophalangeal joint metallic arthroplasty. From October 2008 to February 2010, 34 patients (median age 66.2, range 55 to 70 years) with hallux rigidus were treated surgically using the Toefit-Plus(™) prosthesis. At a mean follow-up period of 27.5 (range 17 to 35) months, 30 patients (88.24%) underwent re-evaluation. The functional length of the first and second metatarsals and the lucency around the prosthesis were evaluated. Statistically significant (p ≤ .05) improvements were found for the mean modified American Orthopaedic Foot and Ankle Society score (from 44 to 80), pain (from 7 to 3 on a 10-cm visual analog scale), and mean total range of motion (from 42.2° to 59.4°). Also, 20 patients (58.82%) were fully satisfied with the procedure (scores of 8 to 10 on a 3-point Likert scale). Shortening the first metatarsal reduced the functional length ratio (r = 0.95; p < .001) and was associated with lower patient satisfaction (r = 0.66, p = .007). Preoperative consideration of the first/second metatarsal functional length ratio could be useful in preventing medial column pain due to a relatively short first metatarsal to a long second metatarsal axis in the transverse plane.