Small Medial Meniscocapsular Separations: A Potential Cause of Chronic Medial-Side Knee Pain

Purpose To describe clinical characteristics, surgical findings, and functional outcome after arthroscopic repair of a unique type of meniscocapsular separation. Methods We retrospectively reviewed office charts, magnetic resonance imaging (MRI) scans, operative reports, and arthroscopic images of 6 patients who underwent surgery between January 2007 and May 2009, in whom a medial meniscocapsular separation measuring less than 5 mm in length was identified and treated. Inclusion criteria were medial-side knee pain unresponsive to nonoperative management, negative MRI findings, and an isolated meniscocapsular separation injury detected on arthroscopy and repaired with 1 stitch. Patients were contacted and completed questionnaires that included subjective International Knee Documentation Committee, Tegner, and Marx scores. Results Of the 6 patients, 5 were female patients aged 14 to 18 years who were involved in sports. All patients recalled an acute twisting knee injury. Symptoms were related mainly to sports and were absent or very minimal during activities of daily living. On physical examination, the medial joint line was tender in all patients, whereas medial-side knee discomfort while squatting (i.e., baseball catcher's position) and McMurray tests were positive only in some. The negative MRI scans used a 3-T magnet in 5 cases and a 1.5-T magnet in 1 case. The duration of symptoms from injury to surgery was between 6 months and 9 years in 5 cases. On arthroscopy, all patients had a medial meniscocapsular separation measuring less than 5 mm in length that was identified when the tip of the arthroscopic probe was inserted into the lesion. This was repaired with a single all-inside stitch. The mean latest follow-up was 31 months (range, 15 to 38 months). The mean subjective International Knee Documentation Committee score was 87 at latest follow-up. Tegner and Marx scores showed that after surgery, 5 patients regained their preinjury level of activity. Conclusions Meniscocapsular separation can involve a segment of less than 5 mm in length, be occult on MRI, be challenging to visualize on arthroscopy, and lead to chronic medial-side knee pain. Critical evaluation with a history, physical examination, and careful arthroscopic inspection of the medial meniscus can lead to appropriate treatment with a good to excellent outcome after repair. Level of Evidence Level IV, therapeutic case series.