Popliteomeniscal fascicle tears causing symptomatic lateral compartment knee pain: diagnosis by the figure-4 test and treatment by open repair.

BACKGROUND Injuries to the popliteomeniscal fascicles of the lateral meniscus are difficult to identify from physical examination and magnetic resonance imaging scans. To our knowledge, there have been no described physical examination techniques to identify symptomatic isolated popliteomeniscal fascicle tears. The popliteomeniscal fascicles have been demonstrated to be important for lateral meniscus stability, and it has been reported that tears can lead to painful symptoms. HYPOTHESIS Popliteomeniscal fascicle tears cause symptomatic lateral compartment knee pain and can be diagnosed by physical examination. Surgical repair can improve patient function. STUDY DESIGN Case series; Level of evidence, 4. METHODS Six patients with isolated tears of the popliteomeniscal fascicles, which caused lateral joint line knee pain, were identified by positive figure-4 test results. RESULTS All patients were found to have replication of their symptoms while placing the affected knee in the figure-4 position and were found to have lateral meniscal hypermobility due to tears of the popliteomeniscal fascicles on arthroscopic examination. All patients had an open repair of the popliteomeniscal fascicles of the lateral meniscus with complete resolution of their symptoms at a mean follow-up of 3.8 years postoperatively. CONCLUSIONS The figure-4 test was found to be useful in identifying the source of lateral compartment knee pain due to popliteomeniscal fascicle tears. Open repair of isolated popliteomeniscal fascicle tears was also found to be effective in resolving lateral compartment knee pain due to popliteomeniscal fascicle tears.