Knee Immobilizers After Knee Replacement
Do not use a knee immobilizer after total knee replacement surgery. Strong evidence from the American Academy of Orthopaedic Surgeons (AAOS) and multiple high-quality guidelines consistently demonstrate that postoperative knee immobilization provides no benefit and may actually impede rehabilitation progress. 1
Evidence Against Immobilization
The AAOS guidelines for surgical management of knee osteoarthritis explicitly state that current evidence does not support the use of immobilization devices following total knee arthroplasty (TKA). 1 This recommendation is based on strong evidence showing:
- No improvement in outcomes: Immobilization does not enhance pain control, functional recovery, range of motion, or complication rates 1
- Potential harm: Immobilizers may delay rehabilitation and impede early mobilization, which is critical for optimal outcomes 1
What You Should Do Instead
Start rehabilitation on the day of surgery. Strong evidence supports that immediate postoperative mobilization (day of surgery) reduces hospital length of stay and improves both pain and function compared to delayed mobilization. 1
Immediate Postoperative Protocol:
- Early mobilization: Begin sitting out of bed and walking on the day of surgery 1, 2
- Supervised physical therapy: Initiate a supervised exercise program during the first 2 months, which strongly improves physical function and reduces pain 1
- Full weight-bearing: Allow immediate full weight-bearing as tolerated 1
- Active range of motion: Start active knee flexion and extension exercises immediately rather than passive motion devices 1
Why Early Mobilization Matters
Research demonstrates that early mobilization within the first 24 hours after TKR significantly reduces the incidence of deep venous thrombosis—the greater the distance mobilized, the lower the risk of thromboembolic complications. 2 This represents a cheap and highly effective intervention that directly impacts morbidity. 2
Common Pitfall to Avoid
Do not use continuous passive motion (CPM) machines. Strong evidence from AAOS guidelines shows that CPM after knee arthroplasty does not improve outcomes and should not be used. 1, 3 CPM provides no clinically important effects on range of motion, pain, function, or quality of life. 3
Special Context: ACL Reconstruction
While your question asks about knee replacement, it's worth noting that the same principle applies to ACL reconstruction surgery. Multiple guidelines from the British Journal of Sports Medicine explicitly recommend against routine postoperative knee immobilizer use following ACL reconstruction, as immobilizers provide no additional benefit and may impede rehabilitation progress. 1, 4 Immediate knee mobilization should be implemented instead. 1, 4
Exception: Hip Arthroplasty
The only context where knee immobilizers have shown benefit is following hip arthroplasty via posterior approach, where a knee immobilizer on the operative side helps prevent hip dislocation by limiting hip flexion. 5 This is not applicable to knee replacement surgery.