Manipulation under anesthesia for post traumatic stiff knee-pearls, pitfalls and risk factors for failure.

Background: Stiffness is common following fractures around knee. Manipulation under anesthesia (MUA) is the initial noninvasive procedure usually performed for such patients. Though MUA has been extensively evaluated for knee arthroplasty, there is paucity of literature regarding its benefits in trauma cases. The purpose of this study was to define the role of manipulation in post traumatic stiff knees.

Methods: Hospital inpatient and outpatient records from January 2010 to June 2014 were retrospectively reviewed to identify patients undergoing MUA at our institution. Patients with more than one year follow up and adequate data were included. Clinical and radiographic parameters were analyzed to assess outcomes, complications, effect of timing on flexion gain as well as identify risk factors associated with failure.

Results: Out of 45 patients undergoing manipulation, 41 patients with 48 knees (34 unilateral and 7 bilateral) met inclusion criteria. Thirty six manipulations were successful while 3 were abandoned due to tight tissues and 9 developed complications.Successful MUA resulted in immediate gain of 62.36° of flexion which decreased to 49.86° at 1year. There was statistically significant loss of flexion of 12.5° over a year (p value 0.0013). Arc of motion improved from 48.5° to 106.1° at 1year (p value <0.0001). Significant improvement was also seen in extension and fixed flexion deformity (p value <0.0001). No significant difference could be detected between early (<3 months) and late (>3 months) groups with respect to outcomes (p value 0.883)or complications (p value 0.3193). Failed group had significantly lower pre MUA flexion and pre MUA range of motion (p value 0.003). Univariate analysis showed that extensor mechanism ruptures during injury (p value <0.0001) and knees with Flexion <40° (p value 0.0022) or ROM<30° (p value 0.0002) were significantly associated with failures.

Conclusion: MUA is a suitable non invasive treatment option for post traumatic stiffness. There is no effect of timing on outcome and late manipulation also results in good outcome. Extensor mechanism rupture and pre manipulation ROM<30° or flexion <40° are associated with failure and such cases should be considered for alternative options for better outcome.