Differential diagnosis of knee pain following a surgically induced lumbosacral plexus stretch injury. A case report.

Background and Purpose: Knee joint biomechanics requires an understanding of lower extremity (LE) segmental interactions. In some cases, knee pain may arise as a result of altered LE biomechanics; while in other cases, knee pain may stem from other causes, such as a peripheral nerve injury. Case Description: A 33-year-old woman presented via direct access for physical therapist (PT) examination with a chief complaint of left knee pain. The day after undergoing a dilation and curettage (D&C) procedure the patient had an acute onset of gait dysfunction. Over the next few days, the patient developed left anterior knee pain (7/10 at worst) in addition to a significant change in physical functioning (Lower Extremity Functional Scale [LEFS] 38/80). Physical examination revealed left LE weakness, altered sensation, and an absent Achilles deep tendon reflex. Outcomes: The patient's presentation was consistent with a lumbosacral plexus stretch injury, with S1 being most affected. A physiatrist was consulted and recommended initiating PT treatment with bi-weekly re-examination. The 6-week (14 visits) re-examination revealed abolished left knee pain and improved physical functioning (LEFS 66/80). Conclusion: Stretch injuries are a known complication of lithotomy positioning. Knowledge of this and the addition of a thorough examination allowed the PT to identify the possible cause of the patient's abrupt onset of left LE dysfunction. Regardless of mode of patient access, screening for referral is crucial and may include referral or, as in this case, consultation with other professionals.