[Application of pie-crusting the medial collateral ligament release in arthroscopic surgery for posterior horn of medial meniscus in knee joint].

To explore the effectiveness and safety of pie-crusting the medial collateral ligament release (MCL) in treating posterior horn of medial meniscus (PHMM) tear in tight medial tibiofemoral compartment of knee joint.
 Methods: Thirty-two consecutive patients with PHMM tear in tight medial tibiofemoral compartment of knee joint were admitted to our department from January, 2013 to December, 2014. All patients were performed pie-crusting the MCL release at its tibial insertion with 18-gauge intravenous needle. All patients were evaluated by valgus stress test and bilateral valgus stress radiograph at postoperative 1st day, 4th week and 12th week. Visual Analogue Scales (VAS), Lysholm scores, Tegner scores and International Knee Documentation Committee (IKDC) scores were recorded at the 1st, 3th, 6th month follow-up, then follow-up every 6 months.
 Results: The mean follow-up was 28 (24-36) months. All cases were negative in valgus stress test. MCL rupture, femoral fracture, articular cartilage lesion and neurovascular injury were not found at the last follow-up. The median medial joint space width of affected side and unaffected side for valgus stress radiographs were 6.8 mm and 4.3 mm (P<0.05) at the 1st day, 5.5 mm and 4.2 mm 
(P<0.05) in the 4th week and 4.8 mm and 4.3 mm (P>0.05) at the 12th week, respectively. VAS scores was changed from 4.5±1.5 preoperatively to 1.7±1.0 at the final follow-up (t=16.561, P<0.05). Lysholm scores was changed from 52.3±5.8 preoperatively to 93.2±6.3 at the final follow-up (t=-41.353, P<0.05). Tegner scores was changed from 4.1±1.1 preoperatively to 5.5±0.6 at the final follow-up (t=-18.792, P<0.05). IKDC scores was changed from 54.5±6.2 preoperative to 93.8±4.5 at the final follow-up (t=-38.253, P<0.05).
 Conclusion: Pie-crusting the medial collateral ligament release is a safe, minimal invasive and effective surgical option for posterior horn of medial meniscus tear in tight medial tibiofemoral compartment of knee joint.