Summary

Contrary to common belief that MCL complex needling creates opening of the medial compartment by microlesions comparable to pie crusting, our study reveals macroscopic transverse tear of the POL in 96% of patients, whose residual postoperative instability might be underestimated by existing literature.

Abstract

Introduction

Needling of medial collateral ligament (MCL) complex of the knee was first described by Bosch in 2006 to avoid iatrogenic cartilage damage and to improve visualization of the posteromedial compartment. This technique has been widely adopted over the past two decades. Although several authors have shown no remaining MCL instability on postoperative valgus stress radiographs at 20 degrees of knee flexion at 6 weeks, case reports described residual MCL microinstability in some patients, raising concerns about the true impact of needling on MCL complex integrity. The aim of this study is to describe in detail the anatomical lesion of the MCL complex created by the needling technique by means of a surgical exploration through the posteromedial approach that is used at the time of meniscal repair.

Methods

Between January 2021 and December 2023, 50 patients underwent posterior horn suture of the medial meniscus using an outside-in approach with systematic needling. The "magic point" as described by Chernchujit et al. guided percutaneous release directly over the meniscal wall with a maximum of 10 perforations using a 20-gauge needle until an audible pop indicated sufficient release under valgus stress. A posteromedial open approach was used to place the sutures under the sartorius fascia. Through this approach, a systematic surgical exploration of the superficial MCL and posterior oblique ligament (POL) was performed to look for potential macroscopic lesions.

Results

A macroscopically visible anatomic lesion was observed in 96% of patients (48/50). It consisted of a complete transverse rupture of the POL with an anteroposterior diameter of 1 to 1.5 cm. It was located 3 to 5 mm above the meniscal wall and 1 to 1.5 cm anterior to the tibial insertion of the semimembranosus. This POL tear was found between an intact layer of sartorius fascia and synovial membrane. The edges of the tear were sharply demarcated in all cases, allowing for direct suture repair. The rupture opened during intraoperative valgus stress in extension and not at 20° flexion in all cases. No macroscopic lesion of the superior MCL was observed.

Conclusion

Contrary to common belief that MCL complex needling creates opening of the medial compartment by microlesions comparable to pie crusting, our study reveals macroscopic transverse tear of the POL in 96% of patients. Existing literature may underestimate residual postoperative instability because studies were based on valgus stress knee radiographs at 20° of flexion, selectively testing the superficial and deep MCL rather than the POL. The lack of a validated method to objectively measure PMC laxity calls these conclusions into question. Further studies are needed to establish the relationship between PMC lesions and radiologic and clinical instability, in particular to better understand whether these lesions all heal spontaneously postoperatively and whether patient-related anatomic factors may impede this.