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A 10-Year Prospective Outcome Study of Pi2 Pyrocarbon Arthroplasty for the Treatment of Thumb Metacarpal Joint Osteoarthritis

Introduction: The surgical management of rhizarthrosis may use many techniques. The implant interposition pyrocarbon Pi2 is one possible solution after total trapeziectomy. The aim of this study was to evaluate the clinical and radiological results of this implant with a minimum of 10 years follow-up. Material and Methods: Forty-two consecutive cases (34 women for 5 men; mean age, 63 years; 76% retired) of total trapeziectomies with free interposition implants in pyrocarbon, Pi2, placed between March 2003 and April 2005 for stage 3 or 4 osteoarthritis in the classification described by Dell. Clinical judgment criteria included satisfaction, pain (visual analogue scale [VAS]), mobility with opposition Kapandji index, strength (grip and pinch), and the QuickDASH functional score. The radiological analysis was performed on anterior-posterior (AP) and lateral Kapandji views. Results: With a mean follow-up of 125.49 months (10.5 years), 96.6% of patients were very satisfied or satisfied. The mobility was improved especially on the opposition (Kapandji = 9.60) with no major aggravation of the metacarpophalangeal extension of the thumb. The strength of the pinch after surgery was 5.9 kg and that of the grip was 24.2 kg. The mean time to resuming daily activities was 76 days (range, 30-240 days). The mean QuickDASH score was 19.9, and the overall Patient-Rated Wrist Evaluation (PRWE) score at the last follow-up was 16.4 out of 100. Bone remodeling, mainly in the scaphoid, was found in 48.2% of cases, stable between 5 and 10 years and with no clinical and functional significance. Two implant dislocations (4.6%) were suffered in our series but did not require surgical revision. The implant survival rate was 100%. Discussion: Subjective and objective clinical outcomes of Pi2 are good, thanks in part to the conservation of the height of the column of the thumb, protective factor against hyperextension of the metacarpophalangeal joint. The payback period is short, and dislocations in our series are related to the learning curve of the implant stabilization technique that must be rigorous. The evolution of radiological remodeling remains something to watch over the very long term. Conclusion: The results of more than 10 years of free interposition implant Pi2 confirm that it is a valid solution for the treatment of advanced rhizarthrosis subject to a very precise surgical technique.