Cartilage Restoration — Autologous Chondrocyte Implantation (ACI) — Trochlea / Patella

Massachusetts General Hospital · MGH Sports Medicine

Weight-Bearing

TTWB; more restrictive than femoral condyle ACI

Key Restrictions

No active knee extension 40-70 deg (patellofemoral compression zone); CPM limited to 0-40 deg wks 0-2; stricter ROM and WB limits than femoral condyle protocol

Timeline & Phases

Stage 1 (0-6 wks): TTWB, CPM 0-40 deg wks 0-2 then progress, no active ext 40-70 deg, quad sets; Stage 2 (6-12 wks): progressive WB, ROM progress, stationary bike (seat high); Stage 3 (3-6 mo): full WB, progressive strengthening, avoid PF compression; Stage 4 (6-18 mo): return to sport

Notes

More restrictive than ACI femoral condyle due to patellofemoral contact pressures; no active knee extension through 40-70 deg arc to protect graft; CPM range limited early. [Archived copy — original Massachusetts General Hospital URL retired in the Mass General Brigham site migration; Wayback snapshot 2025-02-16.]

Surgeon / Author

MGH Sports Medicine