Risk factors for failure of manipulation under anesthesia in posttraumatic knee stiffness

To determine the proportion of patients who fail manipulation under anesthesia (MUA) as a treatment for posttraumatic knee stiffness and determine the risk factors for MUA failure.

A retrospective cohort study was performed at a level I trauma center. We identified 213 knees in 199 patients with arthrofibrosis treated by MUA within 1 year of injury from 2007 to 2020. The primary outcome was MUA failure as defined by need for repeat MUA or surgical release after MUA. Multivariable logistic regression was used to determine the association between MUA failure and potential risk factors.

Overall, 111 knees (52%) failed treatment with MUA. An association was demonstrated between MUA failure and delay in treatment >90 days after injury (OR 3.6, p < 0.01), neurologic injury (OR 2.2, p = 0.02), and pre-procedure knee flexion <45° (OR 1.9, p < 0.01). The rate of failure for knees with no risk factors was 0% (0 of 14), 37% for knees with one risk factor (27 of 73), and 67% (84 of 126) for knees with two or more risk factors.

For patients whose MUA is delayed beyond 90 days postinjury, pre-manipulation knee flexion is <45°, or those with associated neurologic injury; odds of MUA failing to correct posttraumatic arthrofibrosis are significantly increased. The likelihood of obtaining adequate range of motion (ROM) with MUA alone is lower than reported in other populations, with a higher likelihood of being treated with surgical release or additional MUA to attempt to obtain adequate ROM.