What is the typical rehabilitation process after total knee replacement (TKR)?

Rehabilitation After Total Knee Replacement

Begin immediate knee mobilization and weight-bearing within the first week after TKR, combined with isometric quadriceps exercises, cryotherapy, and a structured progression through closed kinetic chain exercises starting at week 2, advancing to open kinetic chain exercises at week 4, with rehabilitation continuing for 9-12 months based on functional criteria rather than time alone. 1

Early Postoperative Phase (First Week)

Immediate mobilization is critical to prevent extension deficits and stiffness. 1 The first week establishes the foundation for successful recovery:

• Start isometric quadriceps exercises immediately in the first postoperative week to reactivate the quadriceps muscles, provided they cause no pain 1
• Implement immediate weight-bearing with correct gait pattern within the first week, ensuring no pain, effusion, or increased temperature 1
• Apply cryotherapy during the first postoperative week to reduce pain and swelling 1
• Begin knee mobilization within the first week to increase joint range of motion, reduce knee pain, and prevent complications like extension deficit 1
• Consider neuromuscular electrical stimulation (NMES) as an adjunct to isometric strength training for re-educating voluntary quadriceps contraction 1

Critical Pitfall to Avoid

Delaying mobilization leads to stiffness and extension deficits that significantly compromise long-term outcomes 1. Extension deficits present preoperatively are major risk factors for postoperative extension problems 2.

Weeks 2-4: Progression Phase

Transition from isometric to dynamic exercises once quadriceps reactivation occurs without effusion or increased pain. 1

• Begin closed kinetic chain (CKC) exercises from week 2 postoperatively 1
• Progress from isometric to concentric and eccentric exercises when the quadriceps is reactivated and the knee tolerates activity without effusion or pain 1
• Continue supervised rehabilitation with a physiotherapist, though home-based rehabilitation may be suitable for highly motivated patients with good access to monitoring 1

The evidence shows that supervised versus home-based rehabilitation produces similar outcomes in motivated patients, but supervision ensures proper progression and prevents adverse events 2.

Weeks 4-8: Strengthening Phase

Open kinetic chain exercises should be introduced carefully with range of motion restrictions. 1

• Start open kinetic chain (OKC) exercises from week 4 in a restricted ROM of 90-45° 1
• Gradually increase ROM in OKC exercises: to 90-30° in week 5, to 90-20° in week 6, to 90-10° in week 7, and to full ROM in week 8 1
• For bone-patellar tendon-bone (BPTB) grafts, extra resistance is allowed at this stage 1
• For hamstring (HS) grafts, avoid adding extra weight in the first 12 weeks to prevent graft elongation 1

Critical Pitfall to Avoid

Progressing too quickly with open kinetic chain exercises, particularly with hamstring grafts, can lead to graft elongation and compromise surgical outcomes 1.

Beyond 8 Weeks: Advanced Rehabilitation

Neuromuscular training must be added to strength training to optimize outcomes and prevent reinjuries. 1

• Add neuromuscular training to strength training to optimize self-reported outcomes and prevent reinjuries 1
• Continue rehabilitation for 9-12 months, depending on final return-to-work or play goals 1
• Measure quadriceps and hamstring strength regularly to track progress 1
• Evaluate psychological changes during rehabilitation using objective instruments 1

The evidence consistently shows that combining strength and neuromuscular training produces superior outcomes compared to strength training alone 2.

Assessment and Return to Activities Criteria

Use objective criteria rather than time alone to determine readiness for return to activities. 1

• Perform an extensive test battery for quantity and quality of movement before returning to sports or demanding activities 1
• Include strength tests, hop tests, and quality of movement assessments 1
• Achieve a Limb Symmetry Index (LSI) of >90% as a cut-off point for general activities 1
• Aim for an LSI of 100% for pivoting/contact sports 1

Additional return criteria include: no pain or swelling, full knee ROM, stable knee on examination, normalized subjective knee function and psychological readiness using patient-reported outcomes 2.

Delivery Methods and Supervision

Supervised rehabilitation should be continued for optimal outcomes, especially for complex cases. 1

• Supervised rehabilitation is preferred for most patients to ensure proper progression and prevent adverse events 1
• Home-based physiotherapy may be equally effective for highly motivated patients who live far from physiotherapy facilities, provided they have individualized prescribed programs and monitoring 2, 1

The evidence shows no significant differences in outcomes between supervised and unsupervised rehabilitation in motivated patients, but supervision provides safety monitoring and ensures appropriate progression 2.

Interventions to Avoid

Certain traditional interventions lack evidence for benefit and should not be routinely used. 1

• Continuous passive motion should be avoided as it is not recommended by most guidelines 1
• Postoperative functional bracing is generally not recommended 1

While continuous passive motion may provide minimal benefit for pain medication use and knee flexion in the first 3 postoperative days, it shows no difference compared to active motion exercises and is not cost-effective 2.

Adjunctive Modalities

Several adjunctive modalities can enhance recovery when used appropriately:

• Neuromuscular electrical stimulation can be beneficial in the initial 6-8 weeks for quadriceps re-education 1, 3, 4
• Cryotherapy is effective for pain control in the first postoperative week 1, 3
• Aquatic therapy may be incorporated as rehabilitation progresses 3, 5
• Balance training appears beneficial as an adjunct to conventional rehabilitation 3, 4

Common Pitfalls Summary

• Failing to address quadriceps strength deficits significantly impacts long-term functional outcomes 1
• Discontinuing rehabilitation too early (before 9-12 months) may compromise optimal functional recovery 1
• Neglecting neuromuscular training alongside strength training increases risk of reinjury 1
• Using time-based rather than criteria-based progression may lead to premature advancement or unnecessary delays 2, 1