Medial meniscal stabilizers, variants, and injuries of the knee.

* The posteromedial corner of the knee comprises the superficial medial collateral ligament (MCL), deep MCL, posterior oblique ligament, oblique popliteal ligament, and posterior horn of the medial meniscus. The main medial knee structure is the superficial MCL.* Injuries to the medial knee are the most common knee ligament injuries. A comprehensive history and physical examination are key to the diagnosis of a posteromedial corner injury. Patients often present 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 an isolated medial structure was injured or if a complete posteromedial corner injury is likely.* 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.

To assess the prevalence of and factors associated with medial collateral ligament (MCL) complex injuries on magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) tears. Data were extracted from the Natural Corollaries and Recovery After ACL Injury (NACOX) multicenter longitudinal cohort study. Between May 2016 and October 2018, patients who presented to 1 of 7 health care clinics across Sweden with an ACL tear sustained no more than 6 weeks earlier and who were aged between 15 and 40 years at the time of injury were invited to participate. All the patients included in this study underwent MRI. The mean time from injury to MRI was 19.6 ± 15.2 days. An orthopaedic surgeon specializing in knee surgery and a musculoskeletal radiologist reviewed all MRI scans. Injuries to the superficial MCL (sMCL), deep MCL (dMCL), and posterior oblique ligament were identified. Stepwise forward multiple binary logistic regression analyses were used to evaluate patient characteristics (age, sex, body mass index, preinjury Tegner activity level, and activity at injury) and injuries on MRI (lateral meniscus [LM] injury, medial meniscus [MM] injury, pivot shift-type bone bruising, medial femoral condyle [MFC] bone bruising, and lateral femoral condyle [LFC] impaction) associated with the presence of MCL complex tears. In total, 254 patients (48.4% male patients) with a mean age of 25.4 ± 7.1 years were included. The overall prevalence of MCL (sMCL and dMCL) injuries and isolated dMCL injuries was 16.5% (42 of 254) and 24.8% (63 of 254), respectively. No isolated sMCL injuries were found. Posterior oblique ligament injuries were found in 12 patients (4.7%) with MCL (sMCL and dMCL) injuries. An LM injury (odds ratio [OR], 3.94; 95% confidence interval [CI], 1.73-8.94; P= .001) and LFC impaction (OR, 2.37; 95% CI, 1.11-5.07; P= .02) increased the odds of having an MCL injury, whereas an MM injury (OR, 0.26; 95% CI, 0.12-0.59; P= .001) reduced the odds. Isolated dMCL injuries were significantly associated with MFC bone bruising (OR, 4.21; 95% CI, 1.92-9.25; P < .001) and LFC impaction (OR, 3.86; 95% CI, 1.99-7.49; P < .001). The overall combined prevalence of MCL (sMCL and dMCL) injuries and isolated dMCL injuries in patients with ACL tears was high (16.5%+ 24.8%= 41.3%). The presence of an LM injury and LFC impaction increased the odds of having an MCL injury, whereas the presence of an MM injury reduced the odds. MFC bone bruising and LFC impaction were associated with the presence of isolated dMCL injuries. Level III, retrospective cohort study.

Ramp lesions or meniscocapsular separation are peripheral injuries that affect the posterior horn of the medial meniscus (PHMM) and the posteromedial capsule and are described as a tear or injury to the meniscocapsular junction or the meniscofemoral ligaments, particularly in the posteromedial aspect of the knee joint in the setting of pivot shift injuries. These almost always occur with a concomitant anterior cruciate ligament (ACL) tear. The meniscocapsular junction is the area where the peripheral attachment of the meniscus meets the joint capsule. In the context of ramp lesions, this region is susceptible to damage when there is an injury to the ACL. The medial meniscus serves as a firm attachment between the tibia and the femur, functioning as a stabilizer for the knee. It plays a crucial role in preventing anterior translation, particularly in knees with ACL deficiency, making it particularly prone to injuries. The ACL tear can cause the tibia to excessively translate anteriorly, leading to stress on the posterior aspect of the medial meniscus. Ramp lesions have significant biomechanical implications, and their occurrence is more prevalent than previously believed. Untreated ramp lesions may contribute to persistent knee symptoms, instability, and impaired function. These lesions are frequently underdiagnosed, leading to a lack of timely surgical intervention in standard knee arthroscopies. This limitation arises from the reliance on anterior portals, restricting a comprehensive evaluation of the posterior horn and attachment of the medial meniscus. Owing to its tendency to go unnoticed during magnetic resonance imaging interpretation and its "blind" spot in arthroscopic vision, achieving an accurate preoperative diagnosis is crucial. The objective of this article is to comprehensively present recent findings in the literature regarding meniscal ramp lesions, encompassing their anatomical, biomechanical, and diagnostic characteristics in an illustrative manner.

Tears of the posterior horn of the medial meniscus (PHMM) are very common in the ACL-deficient knee. Specific lesions of the PHMM have been described in the setting of ACL rupture: ramp lesions and injuries to the meniscotibial ligament. There are little data available regarding the role these lesions play in knee instability. The aim of this study is to analyse the biomechanical consequences of ramp and meniscotibial ligament lesions on knee stability. Our hypothesis was that these lesions would cause increased instability in the setting of ACL rupture. A cadaveric study was undertaken: ten knees were included for analysis. The biomechanical repercussions of different meniscoligamentous injuries were studied in four stages: stage 1 involved testing the intact knee, stage 2 after transection of the ACL, stage 3 following creation of a ramp lesion, and stage 4 after detachment of the meniscotibial ligament. Four parameters were measured during the experiment: anterior tibial translation under a force of 134N, internal and external tibial rotation under a torque of 5Nm, and valgus angulation under a torque of 10Nm. Measurements were taken in four knee flexion positions: 0° or full extension, 30°, 70°, and 90° of flexion. There was a statistically significant increase in anterior tibial translation for stage 2 (6.8±1.3mm, p≤0.001), stage 3 (9.4±1.3mm, p≤0.001), and stage 4 (9.3±1.3mm, p≤0.001) compared to stage 1. There was no significant difference between stage 2 and stage 3 (2.6mm, n.s.) or stage 4 (2.5mm, n.s.). We did, however, demonstrate an increase in anterior tibial translation of 2.6mm after the creation on a lesion of the PHMM compared to isolated division of the ACL, for all flexion angles combined. There was an increase in internal tibial rotation between stage 1 and stage 4 (3.2°±0.7°, p≤0.001) and between stage 2 and stage 4 (2.0°±0.7°, p=0.023). A significant difference was demonstrated for external rotation under 5Nm torque between stages 4 and 1 (2.2°±0.5°, p≤0.001) and between stages 4 and 2 (1.7°±0.5°, p=0.007) for all knee flexion angles combined. No created lesion had a significant effect on medial laxity under a 10-Nm valgus torque at any degree of knee flexion. Lesions of the posterior horn of the medial meniscus are frequent in cases of anterior cruciate ligament rupture. These lesions appear to play a significant role in knee stability. Ramp lesions increase the forces in the ACL, and the PHMM is a secondary restraint to anterior tibial translation. Lesions of the meniscotibial ligament may increase rotatory instability of the knee.

Background: The structural properties of the individual components of the superficial medial collateral ligament (MCL), deep MCL, and posterior oblique ligament (POL) have not been studied in isolation. To define the necessary strength requirements for an anatomical medial knee reconstruction, knowledge of these structural properties is necessary. Hypothesis: The components of the superficial MCL, POL, and deep MCL have significantly different structural properties. Study Design: Controlled laboratory study. Methods: This study used 20 fresh-frozen nonpaired cadaveric knee specimens with a mean age of 54 years (range, 27 to 68 years). These knees provided 8 samples for each tested medial knee structure, which was individually isolated and loaded to failure at 20 mm per minute. Specifically tested were the superficial MCL with intact femoral and detached proximal tibial attachments, the superficial MCL with intact femoral and detached distal tibial attachments, the central arm of the POL, and the isolated deep MCL. Load was recorded as a function of displacement. Stiffness of the ligament at failure was calculated from these measurements. Results: The mean load at failure for the superficial MCL with the intact femoral and distal tibial attachments was 557 N. Mean load at failure was 88 N for the intact femoral and proximal tibial divisions of the superficial MCL, 256 N for the POL, and 101 N for the deep MCL. Stiffness of the ligaments just before failure was 63, 17, 38, and 27 N/mm, in the same order as above. Conclusion: The proximal and distal tibial divisions of the superficial MCL, POL, and deep MCL produced loads of clinical importance. Clinical Relevance: Knowledge of the structural properties of these attachment sites will assist in reconstruction graft choices, fixation method choices, and overall operative treatment of medial knee injury.

*The superficial medial collateral ligament and other medial knee stabilizers-i.e., the deep medial collateral ligament and the posterior oblique ligament-are the most commonly injured ligamentous structures of the knee. *The main structures of the medial aspect of the knee are the proximal and distal divisions of the superficial medial collateral ligament, the meniscofemoral and meniscotibial divisions of the deep medial collateral ligament, and the posterior oblique ligament. *Physical examination is the initial method of choice for the diagnosis of medial knee injuries through the application of a valgus load both at full knee extension and between 20 degrees and 30 degrees of knee flexion. *Because nonoperative treatment has a favorable outcome, there is a consensus that it should be the first step in the management of acute isolated grade-III injuries of the medial collateral ligament or such injuries combined with an anterior cruciate ligament tear. *If operative treatment is required, an anatomic repair or reconstruction is recommended.

To evaluate and compare knee joint stability of grade Ⅲ medial collateral ligament (MCL) injury treated by single-bundle and anatomical double-bundle reconstruction methods, thus providing biomechanical basis for clinical treatment. Nine fresh cadaver specimens of normal human knee joints were randomly divided into 3 groups on average. In intact MCL group: The anterior cruciate ligament (ACL) was detached and reconstructed with single-bundle techniques, and the MCL was intact. In single-bundle and double-bundle reconstruction groups, the superficial MCL (sMCL), posterior oblique ligament (POL), and ACL were all detached to manufacturing grade Ⅲ MCL injury models. After single-bundle reconstruction of ACL, the sMCL single-bundle reconstruction and anatomical double-bundle reconstruction of sMCL and POL were performed, respectively. Biomechanical evaluation indexes included anterior tibial translation (ATT), internal rotation (IR), valgus rotation (VAL), and stresses of MCL and ACL under internal rotation and valgus torques at different ranges of motion of the knee joint. There was no significant difference in ATT at full extension and flexion of 15°, 30°, 45°, 60°, and 90° between groups ( P>0.05). At full extension and flexion of 15°, the IR and VAL were significantly higher in single-bundle reconstruction group than in double-bundle reconstruction group and intact MCL group ( P<0.05). At flexion of 30°, the VAL was significantly higher in single-bundle reconstruction group than in double-bundle reconstruction group and intact MCL group ( P<0.05). While there was no significant difference between double-bundle reconstruction group and intact MCL group ( P>0.05). There was no significant difference in the stresses of MCL and ACL between groups under the internal rotation and valgus torques at all positions ( P>0.05). MCL anatomical double-bundle reconstruction can acquire better valgus and rotational stability of the knee joint compared with single-bundle reconstruction.

This study aimed to determine the respective roles of the anterior cruciate ligament (ACL) and the different components of the medial plane in the control of anterior tibial translation and internal and external tibial rotation. Twenty-ninefresh lower limbs, disarticulated at the hip, were tested in the anatomy laboratory. The following structures were isolated: the ACL, the anteromedial retinaculum (AMR), the medial collateral ligament (superficial and deep MCL), the posterior medial capsule (PMC) and the posterior horn of the medial meniscus (PHMM). The lower limb was positioned at 30° of flexion on the Dyneelax® laximeter (0.1 mm and 0.1° accuracies) and underwent anterior loads up to 200 N and internal and external tibial rotations sectioned from front to back. and the knee was then retested. The results were presented as relative gains in translation and rotations for each structure. Student's t test and Wilcoxon tests were used. The relative gains in translation for the ACL, AMR, superficial MCL, deep MCL, PMC and PHMM, respectively, were42.9%, 6.7%, 7.4%, 6%, 7.5% and 11.6%. The relative gains in internal rotation for ACL, AMR, superficial MCL, deep MCL, PMC and PHMM, respectively, were13%, 6.9%, 4.6%, 3.9%, 13% and 8%. The relative gains in external rotation for ACL, AMR, superficial MCL, deep MCL, PMC and medial meniscus, respectively, were8.9%, 6%, 9.7%, 13.8%,11.2% and 8.5%. All the relative gains in translation, internal and external rotations were significant at each step of transection (p < 0.01). The ligamentous structures of the medial plane constitute a functional unit in which each component has a specific passive contribution. This study highlights the importance of recognising the extent of the medial ligament tears and performing a medial side anatomic and individual reconstruction and a suture of a ramp lesion, in addition to an ACL surgery.

8 - Repair and Reconstruction of the Superficial Medial Collateral Ligament and the Posteromedial Corner

To identify the posterior oblique ligament and assess incidence and patterns of injury to the ligament on MRI of acute knee trauma. One hundred twenty-three MRI studies met the study criteria. For each case, the posterior oblique ligament was identified and scored as injured or normal. Incidence of proximal and distal posterior oblique ligament tears was calculated. Fisher's tests were employed to determine significance of association between tears of the posterior oblique ligament and components of the posteromedial corner and other capsuloligamentous structures of the knee. The posterior oblique ligament was reliably identified as a distinct structure in 123 MRI scans that met the criteria and was consistently labeled as intact or torn. Posterior oblique ligament tear was seen in 61.7% of knee trauma with proximal injury in 56.5% and distal injury in 97.3% of positive cases. Posterior oblique ligament disruption was a part of multiligamentous injury in 94.7% of positive cases. Posterior oblique ligament injuries (n = 76) had an extremely significant relationship with oblique popliteal ligament tears (n = 27) (p = 0.0001), semimembranosus tendon insertion tears (n = 15) (p = 0.0005), and medial collateral ligament tears (n = 15) (p = 0.0005) and a highly significant association with medial meniscus tears (n = 68) (p = 0.0049) and posterior cruciate ligament tears (n = 12) (p = 0.0033). The association with anterior cruciate ligament tears (n = 53) was not significant. The posterior oblique ligament is a distinct radiological entity consistently identified in acute trauma MRI. Disruptions of the distal posterior oblique ligament are frequent in complex knee injury, notably in association with oblique popliteal ligament, medial collateral ligament, and semimembranosus tendon tears.

Background There is limited information regarding load responses of the posterior oblique and superficial medial collateral ligaments to applied loads. Hypotheses The degree of knee flexion affects loads experienced by the posterior oblique ligament and both divisions of the superficial medial collateral ligament. The posterior oblique ligament provides significant resistance to valgus and internal rotation forces near knee extension. Different load responses are experienced by proximal and distal divisions of the superficial medial collateral ligament. Study Design Descriptive laboratory study. Methods Twenty-four nonpaired, fresh-frozen cadaveric knees were tested. Buckle transducers were applied to the proximal and distal divisions of the superficial medial collateral and posterior oblique ligaments. Applied loads at 0°, 20°, 30°, 60°, and 90° of knee flexion consisted of 10 N.m valgus loads, 5 N .m internal and external rotation torques, and 88 N anterior and posterior drawer loads. Results External rotation torques produced a significantly higher load response on the distal superficial medial collateral ligament than did internal rotation torques at all flexion angles with the largest difference at 90° (96.6 vs 22.5 N). For an applied valgus load at 60° of knee flexion, loads on the superficial medial collateral ligament were significantly higher in the distal division (103.5 N) than the proximal division (71.9 N). The valgus load response of the posterior oblique ligament at 0° of flexion (19.1 N) was significantly higher than at 30° (10.6 N), 60° (7.8 N), and 90° (6.8 N) of flexion. At 0° of knee flexion, the load response to internal rotation on the posterior oblique ligament (45.8 N) was significantly larger than was the response on both divisions of the superficial medial collateral ligament (20 N for both divisions). At 90° of flexion, the load response to internal rotation torques reciprocated between these structures with a significantly higher response in the distal superficial medial collateral ligament division (22.5 N) than the posterior oblique ligament (9.1 N). Conclusion The superficial medial collateral ligament experienced the largest load response to applied valgus and external rotation torques; the posterior oblique ligament observed the highest load response to internal rotation near extension. Clinical Relevance This study provides new knowledge of the individual biomechanical function of the main medial knee structures in an intact knee and will assist in the interpretation of clinical knee motion testing and provide evidence for techniques involving repair or reconstruction of the posterior oblique ligament and both divisions of the superficial medial collateral ligament.

Background: Some authors have suggested that the semimembranosus tendon is involved in the pathophysiology of ramp lesions. This led us to conduct a gross and microscopic analysis of the posterior horn of the medial meniscus and the structures inserted on it. Hypothesis: (1) The semimembranosus tendon has a tendinous branch inserting into the posterior horn of the medial meniscus, and (2) the meniscotibial ligament is inserted on the posteroinferior edge of the medial meniscus. Study Design: Descriptive laboratory study. Methods: In total, 14 fresh cadaveric knees were dissected. From each cadaveric donor, a stable anatomic specimen was harvested en bloc, including the medial femoral condyle, medial tibial plateau, whole medial meniscus, cruciate ligaments, joint capsule, and distal insertion of the semimembranosus tendon. The harvested blocks were cut along the sagittal plane to isolate the distal insertion of the semimembranosus tendon on the posterior joint capsule and the posterior horn of the medial meniscus in a single slice. Histological slides were made from these samples and analyzed under a microscope. Results: In all knees, gross examination revealed a direct branch of the semimembranosus and a tendinous capsular branch ending behind the posterior horn of the medial meniscus. This capsular branch protruded over the joint capsule, over the meniscotibial ligament below and the meniscocapsular ligament above, but never ended directly in the meniscal tissue. The capsular branch was 14.3 ± 4.4 mm long (mean ± SD). The direct tendon inserted 11 ± 2.8 mm below the articular surface of the tibial plateau. The meniscotibial ligament inserted on the posteroinferior edge of the medial meniscus, and the meniscocapsular ligament insertion was on its posterosuperior edge. Highly vascularized adipose tissue was found, delimited by the posterior horn of the medial meniscus, meniscotibial ligament, meniscocapsular ligament, and capsular branch of the semimembranosus tendon. Conclusion: In all knees, our study found a capsular branch of the semimembranosus tendon inserted behind the medial meniscus. The meniscotibial ligament was inserted on the posteroinferior edge of the medial meniscus. Histological analysis of this area revealed that this ligament inserted differently from the insertion previously described in the literature. Clinical Relevance: This laboratory study provides insight into the pathophysiology of ramp lesions frequently associated with anterior cruciate ligament injury. To restore anatomy, it is mandatory to reestablish meniscotibial ligament continuity in ramp repairs.

Background:The primary goal of the present study was to investigate injury to the deep medial collateral ligament (MCL), specifically the meniscofemoral ligament (MFL) portion, and its association with medial femoral condyle (MFC) bone marrow edema in acute anterior cruciate ligament (ACL) ruptures. The secondary goal was to examine the association between MFL injury and medial meniscal tears (MMTs) in these same patients.Methods:Preoperative magnetic resonance imaging (MRI) scans of 55 patients who underwent ACL reconstruction surgery were retrospectively reviewed by 2 board-certified musculoskeletal radiologists. MRI scans were examined for MFC edema at the insertion site of the MFL. This site on the MFC was referred to as the central-femoral-medial-medial (C-FMM) zone based on the coronal and sagittal locations on MRI. The presence or absence of bone marrow edema within this zone was noted. The prevalence, grade, and location of superficial MCL and MFL injuries were also recorded on MRI. The correlations between MFL injuries and the presence of MFC bone marrow edema were examined. Lastly, the presence and location of MMTs were also recorded on MRI and were confirmed on arthroscopy, according to the operative notes.Results:On MRI, 40 (73%) of the 55 patients had MFL injuries. MFL injuries were significantly more common than superficial MCL injuries (p = 0.0001). Of the 27 patients with C-FMM bruising, 93% (25 patients) had MFL tears (p < 0.00001). In addition, of the 40 patients with an MFL injury, 63% (25 patients) had C-FMM bruising (p = 0.0251). Chi-square testing showed that MMTs and MFL injuries were significantly associated, with 12 (100%) of 12 patients with MMTs also having a concomitant MFL injury (p = 0.0164).Conclusions:The prevalence of MFL injury in ACL ruptures is high and MFC bone marrow edema at the MFL insertion site should raise suspicion of injury. MFL injuries can present with clinically normal medial ligamentous laxity in ACL ruptures. Additionally, MFL injuries were significantly associated with posterior horn MMTs, which have been shown in the literature to be a potential risk factor for ACL graft failure.Clinical Relevance:As deep MCL injuries are difficult to detect on physical examination, our findings suggest that the reported MFC edema in ACL ruptures can act as an indirect sign of MFL injury and may aid in the clinical detection. Additionally, due to the anatomical connection of the deep MCL and the meniscocapsular junction of the posterior horn of the medial meniscus, if an MFL injury is suspected through indirect MFC edema at the insertion site, the posterior horn of the medial meniscus should also be assessed for injury, as there is an association between the 2 injuries in ACL ruptures.

BackgroundFew studies have investigated the relationship between the chronicity of anterior cruciate ligament (ACL) tears and the incidence of ramp lesion subtypes. The purpose of this study was to evaluate the relationship between the chronicity of ACL tears and the new subtypes of ramp lesions for treatment selection.MethodsBetween May 2015 and April 2023, 367 patients who underwent primary ACL reconstruction were evaluated. Meniscal repair was performed in cases where a ramp lesion was identified. According to the exclusion criteria, 96 patients who underwent repair of ramp lesion were divided into three groups (PR type: pure ramp lesion, RR type: red–red ramp lesion, and DL type: double longitudinal ramp lesion), and the groups were compared for chronicity of ACL tears and time from injury (TFI).ResultsOf the 30 patients classified as having PR type lesions, 11 (36.7%) had chronic ACL tears. Likewise, of the 37 patients classified as having RR type lesions, 14 (37.8%) had chronic ACL tears. In contrast, among the 29 patients classified as having DL type lesions, 20 (69.0%) had chronic ACL tears, indicating a statistically significant difference (p < 0.05). This distinction was significant up to 12 months after injury.ConclusionsPure ramp lesions accounted for only 31% of all ramp lesions in ACL tears. In addition, chronic ACL tears are more frequently accompanied by double longitudinal tears than by red–red zone longitudinal tears or pure ramp lesions of the meniscus posterior horn.Study Design: case series, level of evidence IV.

Primary Repair of the Medial Collateral Ligament with a Double Row Suture Technique and Suture Tape Augmentation for Acute Tibial-Sided Injuries