gms | German Medical Science

Objectives/Interrogation: We present 3 complications attributed to wear in a ball-and-socket metal-on-metal (MOM) or metal-on-polyetheretherketone (MOPEEK) wrist arthroplasty (Motec).

Methods: 3 patients/2 men age 51, 52 and 74 years had a Motec wrist implanted for radiocarpal degeneration due to radius fracture (2) or SLAC (1). Two had MOM articulation, one had a MOPEEK articulation. All three had 1, 2 and 5 prior wrist surgeries.

Results: Patient 1 had initial good pain relief and very good range of motion after Darrahcs and arthroplasty insertion. After 9 months she had increasing radial sided pain and an unstable distal ulna. During ulna shortening and additional bone removal the radiocarpal joint exhibited black particles and the PEEK cup was eroded about 20% of the circumference due to impingement dorsally between the cup and the ball neck. It was revised a MOM articulation. Patient 2 had initial good result but developed a dorsal lump after 4-5 months. Infection was excluded(punctured). MR and ultrasound suggested a pseudotumour. No metallosis was seen and the articulation occurred without any macroscopic changes on exploration. Histology revealed granulomatous tissue and chronic inflammation. The articulation was changed to MOPEEK. Patient 3 had multiple procedures prior to wrist arthroplasty surgery. He developed a fixed extension position of the wrist and reduced finger function. He had 2 extensor tenolysis procedures. He developed an extension position of the wrist again, increased pain, reduced finger function and symptoms CTS. Ultrasound exhibited massive flexor tendon synovitis from the distal forearm to the CMC joints. The extended position gave fretting dorsally between the distal screw and the cup (short head articulation). A complete tenolysis and arthrolysis was performed as well as shortening of the radius (removing the integrated radius implant and inserting a new implant more proximally) and changing the articulation to MOPEEK. Histology revealed foreign body giant cells and chronic inflammation. The patients had normal blood chrome and cobalt levels.

Conclusion: Modern wrist arthroplasties has performed well in many patients. We found unexpected side effects in three patients. On the articulation side the technology is still immature. Concepts which has proven its endurance in hip arthroplasties (highly crosslinked polyethylene and ceramics) has not been implemented in small joint arthroplasties, reducing the performance and survival of modern small joint arthroplasties.