Short-term outcomes after lateral meniscus posterior root repairs in patients undergoing anterior cruciate ligament reconstructions

Objective To evaluate the clinical, radiological and arthroscopic outcomes after surgical repair for chronic lateral meniscus posterior root (LMPR) avulsion combined with anterior cruciate ligament (ACL) reconstruction. Methods From July 2015 to June 2017, a total of 33 patients who underwent transtibial pull-out suture repair for chronic LMPR avulsion combined with anatomic single-bundle ACL reconstruction with hamstring graft were retrospectively reviewed. There were 30 males and 3 females with an average age of 27.7±7.5 years (range 17-45 years) and a mean BMI of 25.2±3.7 kg/m2 (range 19.4-36.7 kg/m2). All patients were available for at least two years of follow-up. A second-look arthroscopy was performed to evaluate the healing status of the repaired meniscus. Subjective knee function was assessed through Lysholm and Tegner scores. Objective knee stability was evaluated using KT-1000 arthrometer side-to-side difference (SSD) and pivot shift test under anesthesia. The tibiofemoral relationship was evaluated by anterior tibial subluxation (ATS) measured on axial MRI. Between patients with preoperative ATS ≥6 mm (18 patients in the ATS positive group) and <6 mm (15 patients in the ATS negative group), the postoperative ATS and the reduction of ATS was also compared. Results After a mean follow-up of 27.5±4.0 months (range 24-39 months), the LMPR avulsion completely healed in 23 (70%) cases, partially healed in 9 (27%) cases, failed to heal in 1 (3%) case on second-look arthroscopy. The Lysholm score was increased from 60.4±13.6 to 82.7±11.1 at 1 year and to 91.4±9.1 at 2 years operatively (F=155.996, P<0.001). The Tegner score was increased from 3(2, 5) to 4(3, 5) at 1 year and 6(4, 6) at 2 years postoperatively (χ2=47.791, P<0.001). The KT-1000 SSD was decreased from 9.1±3.3 mm to 2.0±1.7 mm (t=11.197, P<0.001). The result of pivot shift test was also improved (10 grade I, 20 grade II, 3 grade III, preoperatively vs 30 grade 0, 3 grade I, postoperatively, U=5.161, P<0.001). The ATS was reduced from 5.7±3.9 mm to 3.5±3.2 mm (t=3.530, P=0.001). However, there was no statistically significant decrease in the ATS of the ATS negative group (t=0.400, P=0.695). The ATS of the ATS positive group was reduced from 8.7±1.8 mm to 5.0±3.3 mm (t=4.765, P<0.001), and the ATS reduction of the ATS positive group was greater than that of the ATS negative group (3.7±3.3 mm vs 0.3±2.8 mm, t=3.115, P=0.004). Conclusion In patients undergoing ACL reconstruction, the transtibial pull-out suture repair for chronic LMPR avulsion yielded meniscus healing rate of 97% with improved subjective knee function and objective knee stability and better restored the tibiofemoral relationship for patients with excessive ATS. Key words: Anterior cruciate ligament reconstruction; Menisci, tibial; Treatment outcome; Arthroscopy