Figure 1: Anteroposterior view of knee 10 weeks after total knee replacement.
Figure 2. Lateral view of the knee.
A 65-year-old woman presents to the office with knee stiffness 10 weeks after right total knee arthroplasty (TKA). Despite physical therapy twice a week since surgery, she is still unable to bend the knee past 70° degrees of flexion. She has full knee extension and no evidence of malposition of the implants on radiographs (Figures 1-2). She has no knee effusion or signs of infection.
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Most patients who have a total knee arthroplasty (TKA) regain full extension and maximal level of flexion. Knee stiffness after TKA can be debilitating and is a common reason for poor outcome. Physical therapy and patient motivation are critical components of regaining motion after surgery.
The importance of regaining full knee flexion can be appreciated in many activities of daily living. The knee requires 83° of flexion to climb stairs foot over foot, 93° to sit in a chair without using hands, and 106° for tying shoes while seated. For patients who develop stiffness within 2 to 3 months of TKA, manipulation under anesthesia (MUA) is the best treatment option to regain motion.1,2
Patient risk factors for knee stiffness after TKA requiring MUA include younger patient age, history of smoking, and history of ipsilateral knee surgery.2 Criteria for MUA after TKA varies widely between surgeons. One common protocol includes MUA if patients fail to achieve 75° of flexion 3 weeks postoperatively or 95° at 3 months postoperatively.1,2
The average gain in knee flexion after MUA is 30°. Manipulation under anesthesia performed within 12 weeks postoperatively is associated with increased gains in knee flexion when compared to MUA performed after 3 months. For this reason, MUA is generally performed before the 3-month postoperative timeframe if necessary.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopaedics for Physician Assistants.
1. Issa K, Banerjee S, Kester MA, Khanuja HS, Delanois RE, Mont MA. The effect of timing of manipulation under anesthesia to improve range of motion and functional outcomes following total knee arthroplasty. J Bone Joint Surg Am. 2014;96(16):1349-1357. doi:10.2106/JBJS.M.00899.
2. Newman ET, Herschmiller TA, Attarian DE, Vail TP, Bolognesi MP, Wellman SS. Risk factors, outcomes, and timing of manipulation under anesthesia after total knee arthroplasty. J Arthroplasty. 2018;33(1):245-249. doi:10.1016/j.arth.2017.08.002