Knee Manipulation Under Anesthesia (MUA) After TKA

Stiffness after TKA is time-sensitive: the window for a good manipulation result is measured in weeks, not months. Screen every slow knee early, exclude the causes manipulation cannot fix, and when MUA is indicated — do it promptly. Arthrofibrosis is a diagnosis of exclusion.

Step 1 · Confirm Stiffness & Exclude Secondary Causes

• Rule out prosthetic joint infection — ESR/CRP, aspiration if indicated.
• Rule out component malposition or oversizing, flexion–extension gap imbalance, and instability — weight-bearing and lateral/skyline radiographs; consider CT for rotation.
• Rule out extensor mechanism problems and complex regional pain syndrome.
• Mechanical or malposition-driven stiffness will not respond durably to MUA — direct these to revision, not manipulation.

Step 2 · Indications & Motion Thresholds

• Persistent stiffness despite adequate analgesia and supervised physical therapy.
• Common operational triggers: flexion < 90° at about 6 weeks, or flexion < 80° and/or a fixed flexion (extension) deficit > 20° at 6 weeks. Trials have used ROM < 90° at 4–12 weeks.
• Screen early: patients who are not progressing report weekly ROM so manipulation can be scheduled promptly rather than late.

Step 3 · Timing — the Strongest Modifiable Predictor

• Perform MUA early — ideally within 6–12 weeks of the index TKA.
• Early MUA (< 3 months) yields roughly double the flexion gain of delayed MUA (about 32° vs 19°), and the gain declines as the TKA-to-MUA interval increases.
• Delayed MUA carries significantly higher rates of surgical and medical complications and of subsequent revision TKA.
• Manipulation beyond about 6 months is associated with unsatisfactory outcomes; beyond 90 days, expected flexion gains fall to roughly 17°.

Step 4 · Technique

• General or spinal anesthesia with full muscle relaxation.
• Gentle, controlled flexion with a short lever arm — hand near the joint line, not the ankle — to minimize fracture and extensor-mechanism injury. No forceful torque.
• Document immediate post-manipulation flexion and extension. Intraoperative gains are typically large — mean immediate ROM improvement of about 46° in RCT data.
• For persistent stiffness beyond about 3 months or flexion < 90°, consider combining with arthroscopic lysis of adhesions (aLOA) — but isolated MUA gives more consistent gains with lower risk when performed early.

Step 5 · Adjuncts

• Adjuvant anti-inflammatory therapy is not routinely supported: a multicenter RCT found that adding IV dexamethasone 8 mg plus 14 days of oral celecoxib 200 mg to MUA + PT did not improve ROM or clinical outcomes at 6 weeks or 1 year.
• Optimize multimodal analgesia so the patient can do aggressive early rehabilitation — higher postoperative pain is itself a risk factor for stiffness requiring MUA.
• A regional block or catheter may be used to facilitate immediate post-MUA therapy (institution-dependent).

Step 6 · Post-MUA Rehabilitation

• Begin intensive supervised physical therapy immediately — same day — to preserve the gains achieved under anesthesia.
• Emphasize early, frequent active and passive flexion plus terminal extension work.
• No CPM. A dynamic splint may be considered for a residual flexion contracture (for example > 15°), per surgeon preference.
• Ensure analgesia is adequate to permit therapy.

Step 7 · Expected Outcomes — Counseling Numbers

• Sustained mean ROM gain of about 26–37°, with final ROM typically > 90–100°.
• RCT data: about 46° immediately, 28° at 6 weeks, 37° at 1 year. A French multicenter cohort showed about 36° of gain sustained at 5 years with 77.5% satisfaction.
• Low complication rate (about 2–3%): hematoma, wound dehiscence, infection, tibial tubercle fracture, patellar tendon rupture.

Step 8 · Failure & Escalation

• Failure = repeat MUA, revision for arthrofibrosis, or failure to retain at least 50% of the flexion achieved under anesthesia. Failure often declares itself by the first post-MUA visit.
• Options after failed MUA: repeat MUA (smaller expected gain — about 17–20° increment), arthroscopic or open lysis of adhesions, or revision TKA — individualized by whether the problem is persistent soft-tissue fibrosis or correctable mechanical pathology.

Quick Reference

• Screen: flexion < 90° at 6 weeks, not improving with PT.
• Act: MUA within 6–12 weeks of the index TKA.
• Escalate / consider aLOA: persistent flexion < 90° beyond about 3 months.
• Reassess for a mechanical cause / revision if MUA fails early.

References

1. Abdel MP, Salmons HI, Larson DR, et al. The Chitranjan S. Ranawat Award: Manipulation Under Anesthesia to Treat Postoperative Stiffness After Total Knee Arthroplasty: A Multicenter Randomized Clinical Trial. The Journal of Arthroplasty. 2024.
2. Gu A, Michalak AJ, Cohen JS, et al. Efficacy of Manipulation Under Anesthesia for Stiffness Following Total Knee Arthroplasty: A Systematic Review. The Journal of Arthroplasty. 2018.
3. Akhtar M, Razick D, Seibel A, et al. Outcomes of Early Versus Delayed Manipulation Under Anesthesia for Stiffness Following Total Knee Arthroplasty: A Systematic Review and Meta-Analysis. The Journal of Arthroplasty. 2024.
4. Issa K, Banerjee S, Kester MA, et al. The Effect of Timing of Manipulation Under Anesthesia to Improve Range of Motion and Functional Outcomes Following Total Knee Arthroplasty. The Journal of Bone and Joint Surgery, American Volume. 2014.
5. Roullet CA, Descamps S, Monadjemi S, et al. Manipulation Under Anesthesia for Stiffness After Total Knee Arthroplasty: A French Multicenter Study With 5 Years' Follow-Up Including 344 Cases. Orthopaedics & Traumatology, Surgery & Research (OTSR). 2026.
6. Walsh JM, Sullivan TC, Varghese B, et al. Manipulation Under Anesthesia After Primary Total Knee Arthroplasty. The Journal of Arthroplasty. 2025.
7. Sala J, Jaroma A, Sund R, et al. Manipulation Under Anesthesia After Total Knee Arthroplasty: A Retrospective Study of 145 Patients. Acta Orthopaedica. 2022.
8. Hosanee S, Elebo N, Sikhauli N, Pietrzak JRT. Reluctant Knee: Understanding and Managing Stiffness After Total Knee Arthroplasty. International Orthopaedics. 2026.
9. Ghirardelli S, Chan KCA, Valpiana P, et al. Artificial Intelligence-Driven Decision-Making for Knee Joint Manipulation Following Primary Total Knee Arthroplasty. The Journal of Arthroplasty. 2025.
10. Rantasalo MT, Palanne RA, Saini S, et al. Postoperative Pain as a Risk Factor for Stiff Knee Following Total Knee Arthroplasty and Excellent Patient-Reported Outcomes After Manipulation Under Anesthesia. Acta Orthopaedica. 2022.
11. Scott RD. Posterior Cruciate-Retaining Total Knee Arthroplasty. Journal of Medical Insight (JOMI). 2017.