Fifteen-Year Follow-up of the Modified Oblique Keller Capsular Interposition Arthroplasty Compared to Arthrodesis for Treatment of Advanced First Metatarsophalangeal Joint Arthritis.

Background: Although metatarsophalangeal joint (MTPJ) arthrodesis is considered the "gold standard" for treatment of advanced MTPJ arthritis, a modified oblique Keller capsular interposition arthroplasty (MOKCIA) is an alternative treatment for hallux rigidus that retains MTPJ motion. We aim to retrospectively compare long-term patient-reported outcomes, radiographic alignment, MTPJ walking kinematics, and plantar pressure between the MOKCIA and MTPJ arthrodesis for advanced hallux rigidus.

Methods: Thirty-five patients were recruited from a retrospective chart review (MOKCIA [n = 15, average 15 years from surgery] or an arthrodesis [n = 20, average 13 years from surgery]). We measured visual analog scale (VAS) pain and satisfaction, Foot and Ankle Ability Measure (FAAM), Patient-Reported Outcomes Measurement Information System (PROMIS) physical function scores, radiographs, walking MTPJ sagittal plane kinematics, forefoot, and first toe peak plantar pressure during walking, MTPJ goniometer range of motion, and need for additional surgery. Two-sample t tests or χ² were used to compare groups. A Spearman correlation was used to examine the relationships between measured variables.

Results: Groups did not differ on demographic characteristics, FAAM activities of daily living scale (MOKCIA = 94 ± 8, arthrodesis = 94 ± 7, P = .93), PROMIS physical function T-score (MOKCIA = 50 ± 6, arthrodesis = 48 ± 6, P = .41), forefoot, and first-toe walking peak plantar pressure. The MOKCIA had small but significantly lower VAS pain (MOKCIA = 0.1 ± 0.3, arthrodesis = 1.0 ± 1.6, P = .02) and higher satisfaction scores (MOKCIA = 9.5 ± 0.9, arthrodesis = 8.4 ± 1.8, P = .03). MTPJ passive arc of excursion in the MOKCIA group was 44 ± 15 degrees, and greater goniometric measured flexion of the first MTPJ correlated with greater patient satisfaction in the MOKCIA group (ρ = 0.70, P < .01). No MOKCIA patient in our study group required additional surgery.

Conclusion: Patients in both the MOKCIA and arthrodesis groups reported high function with little limitation due to their toe surgery. Patients in the MOKCIA group had similar pain and satisfaction compared with the arthrodesis group. These results suggest MOKCIA is a joint range of motion-preserving alternative to MTPJ arthrodesis for long-term treatment of hallux rigidus.

Level of evidence: Level III, retrospective, cohort study.