No abstract

Background: Mixed results for functional outcomes and long-term fixation have been reported for first metatarsophalangeal arthroplasty. This prospective study was designed to evaluate the migration of the BioPro metatarsophalangeal-1 (MTP-1) joint hemiprosthesis with Roentgen stereophotogrammetric analysis (RSA). Migration patterns of the prosthesis, prosthesis-induced erosion of the metatarsal bone, and clinical outcomes were evaluated sequentially to 5 years postoperation (PO). Methods: Eleven female patients received the BioPro-1 hemiprosthesis. Prosthesis translation and metatarsal erosion were measured with RSA at immediately PO, 6 weeks, and 3, 6, 12, 36, and 60 months postoperatively. Clinical assessment was done by patient questionnaires. Results: RSA data of 9 patients were available for analysis. Median (range) number of markers used in RSA analysis, condition number, and mean error of markers around the prosthesis were 4 (3-7), 320 (208-862), and 0.13 (0.02-0.28), respectively. Progressive subsidence was seen up to 3 years PO (mean 2.1 mm, SE 0.32). Progressive metatarsal erosion was found from 1 year PO (mean 0.49 mm, SE 0.15). Pain, function, and quality scores improved after surgery and did not deteriorate at later follow-up moments. Conclusion: Model-based RSA of the BioPro-1 prosthesis shows nonstabilizing medial and distal translation and metatarsal erosion. Despite the measured migration and erosion, clinical outcomes improved and remained similar up to 5 years postoperation.