Trapeziometacarpal arthritis is a common condition, causing symptoms in up to ten percent of women and one percent of men¹. LRTI is the most commonly used surgical technique for this condition however, long-term studies have shown persistent weakness of pinch strength² after surgery. The Ascension® PyroDisk is a pyrocarbon disk shaped implant designed to articulate against the trapezium and metacarpal, preserving the height of the articulation. The objective of this study was to determine whether treatment with a pyrocarbon implant resulted in comparable pain relief and range of motion, whilst providing superior gains in pinch strength when compared to LRTI.

This is a prospective randomized control trial comparing pyrocarbon implant to LRTI. Surgeries were accomplished by a single surgeon in a standardized fashion. Patients were evaluated at six weeks, three, six and 12 months following surgery. Data on pain (VAS), function (Patient Rated Wrist Evaluation (PRWE)), mobility and strength (grip, key and lateral pinch) were obtained as well as radiographic assessment of the height of the arthroplasty space.

A total of 80 patients had surgery between July 2008 and November 2016. Forty patients were allocated to the PyroDisk group and 40 to the LRTI group. Seventy-four patients (92,5%) completed the one year follow-up. Mean age was slightly older in the PyroDisk group (64 vs 60,8 y.o., p=0,03). Surgical and tourniquet times were longer in the PyroDisk group. There was no difference between the groups in strength, pain or functional outcome at one year. However, VAS was significantly higher in the PyroDisk group at three and six months (4,5 vs 2,4, p < 0,001, 2,6 vs 1,7, p=0,02) and PRWE was also significantly better at three months in the LRTI group (53,7 vs 71,2, p=0,02). The overall complication rate was three times higher in the PyroDisk group (10% vs 30%).

Treatment of trapeziometacarpal arthritis with PyroDisk does not provide superior functional gains when compared to LRTI. On the contrary, it seems to result in more pain in the first few months following surgery. This difference in pain is not seen at 1 year after surgery. This may suggest that there is a period of adaptation to the Pyrodisk after its insertion. We also found a higher risk of complications with the use of the PyroDisk.