Biomechanics and physical examination of the posteromedial and posterolateral knee: state of the art

All the menisco-ligamentary structures of the medial plane play a significant role in controlling anterior tibial translation and tibial rotation of the knee. Cadaveric study of 29 knees with the Dyneelax® laximeter

Purpose

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.

Methods

Twenty-nine fresh 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.

Results

The relative gains in translation for the ACL, AMR, superficial MCL, deep MCL, PMC and PHMM, respectively, were 42.9%, 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, were 13%, 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, were 8.9%, 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).

Conclusions

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.

Clinic and Home-Based Exercise with Blood Flow Restriction Resolves Thigh Muscle Atrophy after Anterior Cruciate Ligament Reconstruction with the Bone-Patellar Tendon-Bone Autograft: A Case Report

Anterior cruciate ligament reconstruction (ACLR) results in thigh muscle atrophy. Of the various interventions proposed to mitigate thigh muscle atrophy, exercise with blood flow restriction (BFR) appears safe and effective. Some literature suggests daily exposure to exercise with BFR may be indicated during the early phase of ACLR rehabilitation; this case report outlines the methodology utilized to prescribe clinic- and home-based BFR within an outpatient rehabilitation program. A 15-year-old male soccer player suffered a left knee injury involving the anterior cruciate ligament and both menisci. He underwent ACLR and completed exercise with BFR as part of his clinic- and home-based rehabilitation program, which included practical blood flow restriction during home-based rehabilitation. After 16 weeks of rehabilitation, surgical limb thigh girth values were objectively larger than the non-surgical limb (surgical, 52.25 cm; non-surgical 50 cm), as well as the multi-frequency bioelectrical impedance analysis of his lower-extremity lean body mass (surgical limb, 10.37 kg; non-surgical limb, 10.02 kg). The findings of this case report suggest that the inclusion of clinic- and home-based BFR within an outpatient rehabilitation program may be indicated to resolve thigh muscle atrophy early after ACLR.

Posterior oblique ligament of the knee: state of the art

The posterior oblique ligament (POL) is the predominant ligamentous structure on the posterior medial corner of the knee joint. A thorough understanding of the anatomy, biomechanics, diagnosis, treatment and rehabilitation of POL injuries will aid orthopaedic surgeons in the management of these injuries.

The resulting rotational instability, in addition to valgus laxity, may not be tolerated by athletes participating in pivoting sports. The most common mechanism of injury – accounting for 72% of cases – is related to sports activity, particularly football, basketball and skiing. Moreover, three different injury patterns have been reported: those associated with injury to the capsular arm of the semimembranosus (SM), those involving a complete peripheral meniscal detachment and those involving disruption of the SM and peripheral meniscal detachment.

The hallmark of an injury related to POL lesions is the presence of anteromedial rotatory instability (AMRI), which is defined as ‘external rotation with anterior subluxation of the medial tibial plateau relative to the distal femur’.

In acute settings, POL lesions can be easily identified using coronal and axial magnetic resonance imaging (MRI) where the medial collateral ligament (MCL) and POL appear as separate structures. However, MRI is not sensitive in chronic cases.

Surgical treatment of the medial side leads to satisfactory clinical results in a multi-ligamentous reconstruction scenario, but it is known to be associated with secondary stiffness.

In young patients with high functional demands, return to sports is allowed no earlier than 9–12 months after they have undergone a thorough rehabilitation programme.

Cite this article: EFORT Open Rev 2021;6:364-371. DOI: 10.1302/2058-5241.6.200127