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

Massachusetts General Hospital · MGH Sports Medicine

Weight-Bearing

With osteotomy: touch-down WB in locked brace; without osteotomy: 25% WB immediately, 50% wk 2, 75% wks 3-4, WBAT in unlocked brace wks 5-6; brace locked at 0 deg for ambulation and sleep, unlock to 20-30 deg wks 4-6 if SLR without lag, discharge at 6 wks if SLR without lag; full WB by wks 8-9

Key Restrictions

No active knee extension 40-70 deg and no repetitive closed chain knee flexion 40-70 deg (patellofemoral contact zone) through Phase III; PROM only with flexion 0-40 deg wks 0-2, then increase per tolerance; CPM 0-40 deg wks 0-2 then +5-10 deg/day, 6-8 hrs/day in 2-hour blocks; flexion goals 90 deg by wk 4 and >120 deg by wk 6; Phase III loading limited to <40 deg flexion

Timeline & Phases

6 phases: Phase I (0-6 wks, PROM 0-40 deg wks 0-2, CPM, stationary bike with high seat from wk 4 if 90 deg flexion, pool walking from wk 4), Phase II (6-12 wks, WBAT to full WB by wks 8-9, exercises limited to 0-40 deg, short arc extension from wk 9, single-leg balance wk 8), Phase III (12-24 wks, leg press and single-leg squat <40 deg, flutter kick and aqua jogging), Phase IV (24+ wks, advanced strengthening, may perform knee flexion 40-70 deg), Phase V (9-12 months, return to running program), Phase VI (12 months, unrestricted return to sport: strength index and hop testing >90%, KOOS-sports >90%, IKDC >93)

Notes

Two-stage ACI for trochlea/patella lesions; more restrictive than femoral condyle ACI because of patellofemoral contact pressures, with no active extension or repetitive closed chain flexion through 40-70 deg; separate WB schedules with and without osteotomy; revised 12/2022

Surgeon / Author

MGH Sports Medicine

Published

December 2022