Background: The aim of this study was to evaluate the results following total first metatarsophalangeal (FMTP) joint replacement arthroplasty using a modular three component press fit prosthesis at two year follow up.
Methods: All patient data was collected in a prospective way in four study centres. Both preoperative and postoperative evaluation consisted of an assessment using the AOFAS-HMI score, visual analogue scale for pain, evaluation of the range of motion and patient satisfaction scores. Postoperative X-rays were reviewed for loosening and radiolucency up to two years.
Results: Fifty-five feet were available for analysis at 24 months. Two implants were removed during the study. Six more feet had additional surgery due to stiffness or malalignment. Postoperative AOFAS-HMI scores improved significantly by 32.4 points at two year follow-up (p<0.001). The visual analogue scale for pain improved significantly from 6.8 (std 1,6) preoperatively to 1.6 (std 1,9) postoperatively (p<0.0001). Mean dorsiflexion improved from 12.6 (std 10,1) degrees preoperatively to 31.2 (std 16,8) degrees postoperatively. Eighty-seven percent of patients were moderately to well satisfied with the end result. Eighteen prostheses showed radiolucency at 24 months.
Conclusion: Implantation of a Metis® modular three component press fit prosthesis for the metatarsophalangeal joint in hallux rigidus shows significant improvement in AOFAS-HMI scores and a decrease in pain. Concerns remain with regard to early reoperation rate (14.5%) and long term survival of the implant. Future studies will have to address these aspects.
Keywords: Case series; First metatarsophangeal joint replacement; Hallux rigidus; Level IV clinical evidence; Metis.
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