Illustration of the connection between the vastus medialis obliquus muscle and the superficial medial collateral ligament of the knee: A human knee cadaveric study

Background: While the anatomy of the medial part of the knee has been extensively described, the muscular connections to the superficial medial collateral ligament (sMCL) have not been sufficiently studied. The purpose of this study is to describe the anatomy of the musculo-ligamentous connection between the sMCL and the Vastus Medialis Obliquus muscle (VMO), and to describe its anatomy. Methods: Six Human Cadaveric knees were used in this study. Donors were 4 males and 2 females with a mean age of 49 years old. Dissection was performed in fixed knee extension and directed to show the area of the proximal attachment of the sMCL. Results: A musculo ligamentous connection between the distal portion of the Vastus medialis Obliquus muscle and the sMCL has been identified in our entire specimens. The mean mid substance width of this connection was 9.75 (8.7 -10.8) mm, the mean length was 29.3 (22.2-36.4) mm and the mean thickness was 1.3 (0.9-1.7) mm. Conclusion: The proximal femoral attachment of the sMCL is directly connected to the distal end of VMO. This connection may show that the sMCL can possibly assist in the dynamic stabilization of the knee during extension against valgus stress, through its tension by the contracted VMO muscle.

In Vivo biomechanical evaluations of suture anchors for repairing grade 3 superficial medial collateral ligament injury in a porcine model

Purpose: To clarify the biomechanical and radiological outcomes of superficial medial collateral ligament (sMCL) repair using suture anchors in a large animal model. Methods: The right sMCLs of nine male castrated pigs was completely detached at the femoral attachment. sMCL repair surgery was performed using two suture anchors. The same skin incision, sMCL exposure, and immediate wound closure were made at the left knee as a sham surgery. Magnetic resonance imaging was performed preoperatively and 4 weeks after surgery. The structural properties (upper yield load, maximum load, linear stiffness, and elongation at failure) of the femur-sMCL-tibia complex were determined. Results: During tensile testing, all the repaired sMCLs avulsed from the femoral attachment. There were no significant differences in the upper yield load, maximum load, linear stiffness, or elongation at failure between the groups 4 weeks after surgery or in the MRI-derived signal-to-noise quotients (SNQs) at the mid and tibial sMCL. The SNQs differed significantly at the femoral (2.7 ± 1.2 vs 0.3 ± 0.7; P = 0.00064) portions between groups. Conclusion: The injured sMCLs biomechanically recovered after surgery using suture anchors even though the SNQs were higher than those with native contralateral sMCLs. For clinical relevance, sMCL repair of grade 3 sMCL injuries using suture anchors was both safe and successful with less tissue dissection.

The Anterior Oblique Ligament description in the knee anteromedial compartment

Purpose: To describe a ligamentous structure in the anteromedial region of the knee identified in a series of anatomical dissections of cadaveric specimens.Methods: Sixteen cadaveric knees were dissected to study the medial compartment. Exclusion criteria were signs of trauma, previous surgery, signs of osteoarthritis and poor preservation state. The main structures of this region were identified during medial dissection. After releasing the superficial medial collateral ligament (sMCL) of the tibia, the Anterior Oblique Ligament (AOL), was isolated. The morphology of the structure and its relationship with known anatomical parameters were determined. For the statistical analysis, the means and standard deviations were calculated for continuous variables. A 95% confidence intervals was defined as significant. Student's t-tests were used for continuous variables.Results: After dissection a distinct ligamentous structure (AOL) was found in the medial region of the knee. This structure was found in 100% of the cases, was located extracapsularly and originated in the anterior aspect of the medial epicondyle, running obliquely toward the tibia. When crossing the joint, the ligament presented a fan-shaped opening, exhibiting a larger area at the tibial insertion. The AOL had a mean thickness of 6.83±1.34 mm at its femoral origin and 13.06±1.91 at its tibial insertion. It had a significantly (p = 0.0009) longer mean length with the knee at 90° of flexion (33.82±9.50 mm) than with the knee in total extension (26.56±9.48 mm), indicating that the ligament is tensioned in flexion.Conclusion: A structure was identified in the anteromedial compartment of the knee with a ligamentous appearance originating in the medial femoral epicondyle and with tibial insertion anterior to the sMCL. Clinical relevance: This study demonstrates the anatomy of a new medial structure of the knee. As a result, there will be a better understanding of the stability of the knee.

Length change pattern of the medial structures of the knee and related reconstructions

Introduction: Aim of the study was to investigate the length changes of the medial structures and related reconstructions. It was assumed that the three fibre sections (anterior/middle/posterior) of the superficial medial collateral ligament (sMCL) have different length change patterns, which cannot be imitated by current reconstructions. Hypotheses: The three fibre sections (anterior/middle/posterior) of the superficial medial collateral ligament (sMCL) cannot be imitated by current reconstructions. Methods: Measurements were made on eight cadaveric knees. The knee joints were clamped in a custom-made open chain extension structure. For this purpose, the portions of the quadriceps and the iliotibial tract were aligned according to their fibre direction and statically loaded using hanging weights. The respective tibial and femoral insertion points of the sMCL anterior/middle/posterior fibres were marked by small pins. Similarly, pins were inserted at the tibial and femoral attachment sites of the posterior oblique ligament (POL). In order to imitate the Lind reconstruction, a pin was additionally inserted on the tibial semitendinosus insertion site. Pin combinations accounting for the anterior/middle/posterior sMCL, the POL, and the Lind reconstruction were connected using a high resistant suture. Then the length change patterns were measured using a rotary encoder from 0-120° knee flexion. Statistical analysis was performed using 2-way repeated-measures ANOVA and a post-hoc Bonferroni correction (p <0.05). Results: The anterior and posterior fibres of the sMCL showed a reciprocal behaviour (p< 0.001). The anterior fibres showed a length reduction (2%) up to a flexion of 20°, followed by an elongation of 5% at 120° flexion, which means that the anterior fibres are tight in knee flexion. Conversely, the posterior fibres of the MCL showed an initial length reduction of 4% at 20° flexion. This was followed by an isometric range (20° - 80°) and a further length reduction of 8% in deep flexion (120°). Thus, the posterior fibres of the MCL were tight in extension. The three parts of the POL showed a constant reduction of 25% between 0° and 120°. The Lind reconstruction with the tibial pin at the semitendinosus insertion site showed similar length changes compared to the sMCL (n.s.). Furthermore, the Lind reconstruction was dependent on the femoral placement of the pins (p <.001). The tibial placement had no significant influence. Conclusion: The anterior portion of the sMCL was tight in flexion, whereas the posterior portion was tight in extension. This reciprocal behavior could not be imitated by a single point to point reconstruction. When surgically applying these reconstructions, special attention should be paid to the femoral insertion.