| Posteromedial Corner Knee Injuries: Diagnosis, Management, and Outcomes A Critical Analysis Review Mark E. Cinque, MS Abstract » The posteromedial corner of the knee comprises the superficial Jorge Chahla, MD, PhD medial collateral ligament (MCL), deep MCL, posterior oblique Bradley M. Kruckeberg, BA ligament, oblique popliteal ligament, and posterior horn of the medial meniscus. The main medial knee structure is the superficial MCL. Nicholas N. DePhillipo, MS, ATC, OTC » Injuries to the medial knee are the most common knee ligament injuries. A comprehensive history and physical examination are key to Gilbert Moatshe, MD the diagnosis of a posteromedial corner injury. Patients often present Robert F. LaPrade, MD, PhD with swelling and pain over the medial joint line after an injury involving a valgus and external rotation force. The valgus stress and anteromedial drawer tests can aid the clinician in deciphering whether Investigation performed at the an isolated medial structure was injured or if a complete posterome- Steadman Philippon Research dial corner injury is likely. Institute, Vail, Colorado » Valgus stress radiographs can be utilized to quantify the amount of medial joint gapping. A side-to-side difference in gapping of 3.2 mm is consistent with an isolated superficial MCL tear, and a side-to-side difference of $9.8 mm is consistent with a complete posteromedial corner injury. Magnetic resonance imaging is also a useful tool in the detection of medial-sided injuries and has been reported to have an 87% accuracy. » Although a large number of medial knee injuries can be treated nonoperatively, complete posteromedial corner injuries may require surgical treatment to restore joint stability and biomechanics. There is heterogeneity between techniques with regard to the type of graft, the tibial and femoral tunnel position, and the tensioning protocol. Anatomic techniques have been reported to better restore knee kinematics and function. edial-sided knee injuries prompt identification and evaluation to are among the most improve long-term prognosis of the common knee ligament knee1,2. Grade-III medial-sided injuries, injuries encountered by as defined by LaPrade et al.3, have been orthopaedicM surgeons. These injuries often reported to have a concomitant cruciate occur when a valgus stress is applied to the ligament injury in as many as 78% of knee along with tibial external rotation. cases (47 of 60 patients)2. These ligament injuries can occur in isola- Recently, there has been increasing tion or with concomitant meniscal or interest in the posteromedial corner of the cruciate ligament injuries, which require knee that has led to better understanding of Disclosure: There was no external funding for this work. On the Disclosure of Potential Conflicts of which are provided with the online version of the article COPYRIGHT © 2017 BY THE Interest forms, , one or more of the authors JOURNAL OF BONE AND JOINT checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena SURGERY, INCORPORATED outside the submitted work (http://links.lww.com/JBJSREV/A250). JBJS REVIEWS 2017;5(11):e4 · http://dx.doi.org/10.2106/JBJS.RVW.17.00004 1 | Posteromedial Corner Knee Injuries: Diagnosis, Management, and Outcomes the anatomy and its role in knee kine- on the diagnosis and management of The posterior oblique ligament has matics. The posteromedial corner of the posteromedial corner knee injuries and 3 fascial attachments at the distal aspect knee includes 5 major components: the assesses current posteromedial corner of the semimembranosus tendon8. The superficial medial collateral ligament reconstruction techniques and out- main arm of the posterior oblique liga- (MCL), the deep MCL, the posterior comes. Current reconstruction tech- ment is the central arm, which arises oblique ligament, the oblique popliteal niques for the superficial MCL and from the main semimembranosus ten- ligament, and the posterior horn of the posterior oblique ligament have been don and reinforces the deep MCL and medial meniscus. Historically, the no- described in the literature and therefore then continues to attach to and blend menclature of the medial knee structures will be the focus in the anatomic and with the posteromedial joint capsule and has been inconsistent, leading to con- biomechanical sections. medial meniscal junction8. The femoral fusion and controversy4-6. In an attempt attachment of the central arm of the to standardize the nomenclature and to Quantitative Anatomy of the posterior oblique ligament is located accurately guide anatomic reconstruc- Posteromedial Corner 7.7 mm distal and 2.9 mm anterior to tions, LaPrade et al.3,7,8 reported on the The anatomy of the posteromedial cor- the gastrocnemius tubercle. quantitative anatomy of the medial ner of the knee is complex, which can The semimembranosus tendon has structures of the knee and identified render injuries to any combination of multiple tibial attachments that provide each of the structures in relation to reli- structures challenging to treat surgically. dynamic stabilization to the postero- able anatomic landmarks9,10. The posteromedial corner of the knee medial corner15,16. The anterior arm of Assessment of medial knee injuries comprises the superficial MCL, the deep the semimembranosus attaches to the can be challenging; therefore, in addi- MCL, the posterior oblique ligament, tibia deep to the proximal attachment of tion to a detailed physical examination, the oblique popliteal ligament, and the the superficial MCL, and the direct arm imaging studies are recommended to posterior horn of the medial meniscus attaches posteromedial to the medial assist in the diagnosis. The grade of (Fig. 1). To properly treat an injury to tibial crest8 (Fig. 1). the medial knee injury is based on the any combination of the structures in the number of structures that are torn, and posteromedial corner, it is necessary to Diagnosis of Posteromedial treatment options depend on the loca- understand not only anatomic relation- Corner Injuries tion of the tear and presence of concur- ships, but also the biomechanical roles Biomechanics of the rent ligament injury. The majority of of each structure both individually and Posteromedial Corner medial injuries will usually heal without as a unit. There is an intricate interplay between operative intervention2,11. However, a The main medial structure is the the posteromedial structures, and an subset of patients with grade-III medial superficial MCL, which averages 10 to important load-sharing distribution be- knee injuries will develop persistent pain 12 cm in length. The femoral superficial tween the superficial MCL and the and continued functional rotatory or MCL attachment is 3.2 mm proximal posterior oblique ligament has been valgus instability after nonoperative and 4.8 mm posterior to the medial epi- reported that depends on the knee flex- treatment. Identifying patients at risk for condyle. The superficial MCL has 2 ion angle17. The proximal superficial poor outcomes following conservative tibial attachments: the proximal tibial MCL is the primary knee valgus management is important but chal- attachment, which is a soft-tissue at- stabilizer across all knee flexion lenging because of inconsistent reports. tachment 1 cm distal to the joint line on angles8,10,18,19. The proximal superfi- There is still controversy in the literature the anterior arm of the semimembra- cial MCL acts as a secondary stabilizer on the treatment of combined postero- nosus tendon, and the distal attachment to external and internal rotation medial corner injuries with concomitant on the tibia, which is located 6 cm distal depending on the knee flexion angle9,20. cruciate ligament injuries. Some authors to the joint line. The deep MCL is a The distal superficial MCL acts as a have advocated for nonoperative treat- thickening of the medial joint capsule, primary stabilizer for both external and ment of all medial-sided injuries2; which is firmly adherent to, but separa- internal rotation. The posterior oblique however, because of the increased risk of ble from, the superficial MCL. The deep ligament and the posteromedial capsule developing persistent anteromedial ro- MCL femoral attachment site is ap- provide primary valgus restraint in ex- tatory instability, leading to increased proximately 1 cm distal to that of the tension, and the superficial MCL plays force on the reconstructed cruciate lig- superficial MCL and courses distally to a more dominant role in flexion because aments, most authors advocate for con- attach to the medial part of the menis- of relaxation of the posterior oblique current operative treatment of medial cus, which includes the meniscofemoral ligament in flexion9. Moreover, biome- structures in a knee with injury to mul- and meniscotibial divisions. On the chanical studies have demonstrated the tiple ligaments1,12,13. tibia, the deep MCL attaches approxi- role of the posterior oblique ligament as This article provides a critical mately 3 to 4 mm distal to the joint a primary stabilizer for internal rotation analysis of the current, relevant literature line14. and a secondary stabilizer for valgus 2 NOVEMBER 2017 · VOLUME 5, ISSUE 11 · e4 Posteromedial Corner Knee Injuries: Diagnosis, Management, and Outcomes | Fig. 1 Figs. 1-A and 1-B The posteromedial corner. AMT 5 adductor magnus tendon, VMO 5 vastus medialis obliquus muscle, SM 5 semimembranosus muscle, MPFL 5 medial patellofemoral ligament, MGT 5 medial gastrocnemius tendon, POL 5 posterior oblique ligament, sMCL 5 superficial medial collateral ligament, ME 5 medial epicondyle, AT 5 adductor tubercle, and GT 5 gastrocnemius tendon. Fig. 1-A Illustration. (Reproduced from: LaPrade RF, Engebretsen AH, Ly TV, Johansen S, Wentorf FA, Engebretsen L. The anatomy of the medial part of the knee. J Bone Joint Surg Am. 2007 Sep;89[9]:2000-10.) Fig. 1-B Cadaveric specimen showing soft-tissue attachments of the posteromedial side of the knee. and external rotation7,21. Valgus insta- The degree of valgus gapping is related to posterolateral tibial rotation with an in- bility, which is observed in the setting the severity of the injury.