Elbow Interposition / Distraction Arthroplasty

Interposition arthroplasty is a joint- and bone-preserving alternative to total elbow arthroplasty for the young, high-demand patient with end-stage (usually post-traumatic) elbow arthritis, in whom TEA's high failure rate and strict lifelong lifting limit are unacceptable. The arthritic distal humerus is debrided and contoured and resurfaced with an interposed soft-tissue graft - fascia lata, or Achilles/dermal allograft - which biologically resurfaces the joint while preserving bone and motion. A hinged distraction external fixator (classically 3-4 weeks) may be added to unload and protect the graft and maintain the joint space while allowing early motion, especially where there is instability. The decisive factor is elbow STABILITY: instability before or after surgery predicts failure, so the ligaments and columns must be competent or reconstructed. Outcomes are modest (~60-70% satisfactory) and less reliable than TEA, but a failed interposition can be converted to TEA.

• Outcomes: roughly two-thirds satisfactory pain relief (e.g. ~69% satisfactory, ~62% excellent/good Mayo scores in the classic distraction-interposition series), similar for post-traumatic and inflammatory arthritis - less reliable than TEA.
• Stability is everything: competent or reconstructed collateral ligaments and bony columns; the distraction fixator protects an unstable elbow during healing; with good stability, immediate protected motion in a hinged brace without external distraction is feasible.
• Complications: ulnar nerve problems (consider decompression/transposition), instability, graft/fixator issues, pin-site problems, and the chance of persistent pain - more frequent in post-traumatic cases.
• Conversion: a failed interposition arthroplasty can be converted to a total elbow arthroplasty later, so it does not preclude future prosthetic replacement - a reasonable first step in the young arthritic elbow."