Stener-like lesion of the medial collateral ligament of the knee

A 32-year-old male presented to the emergency department with right knee pain, swelling, and deformity after jumping onto uneven ground. Physical examination showed weakness and limited range of motion in the right leg, and the patella was laterally displaced.

Initial knee radiographs (Figures 1a and 1b) show lateral subluxation of the tibia relative to the femur. There was lateral dislocation of the patella.

After successful joint reduction, a right knee MRI was performed (Figures 2a, 2b and 2c). The MRI revealed extensive medial ligamentous injury with complete tears of the medial collateral ligament (MCL). The torn MCL was retracted, with the distal end of the MCL entrapped and folding into the medial compartment joint space, a configuration resembling a Stener-like lesion.

There were also tears of the medial and lateral menisci, complete tears of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), and bone contusions in the lateral distal femur and proximal tibia. No vascular injury was seen.

The medial collateral ligament (MCL) is the most commonly injured ligament in the knee and is composed of superficial and deep fibres [1,2]. The superficial MCL (sMCL) fibres lie deep to the pes anserinus just proximal to the ligament’s tibial insertion. Grade 3 injuries are defined as full-thickness tears of the MCL. In one subset of grade 3 tears, the avulsed distal portion of the sMCL retracts and becomes displaced superficial to the pes anserinus. The interposing pes anserinus blocks ligament-to-bone contact and thus impairs healing of the torn sMCL fibres, necessitating surgical intervention [3,4]. This configuration is named after the analogous Stener lesion of the thumb.

In the setting of multi-ligament injury or trauma, physical examination of sMCL injury may present with tenderness over the tibial sMCL attachment, soft tissue swelling over the proximal tibia and ecchymosis over the anteromedial tibia. However, MRI studies are essential to establish a diagnosis of Stener-like lesion of the MCL, as clinical diagnosis may be difficult [4].

Stener-like lesion is usually seen well on coronal sequences, in which the proximal portion of the torn sMCL appears shortened, undulated, and irregular. The torn proximal portion is often seen bordering the pes anserinus, which may lead one to confuse the pes anserinus for the sMCL [5]. Less common findings include entrapment of the sMCL within the medial femorotibial compartment or beneath a reverse Segond fracture. Further, Stener-like lesions are highly correlated with ACL tears and multi-ligament injury, as was the case with our patient [4].

MCL repair or reconstruction is usually indicated for the treatment of Stener-like lesions. Surgical indications include multi-ligamentous knee injury, valgus instability, or sMCL that is entrapped in the femorotibial joint [4]. Prompt surgical intervention can facilitate anatomic healing and prevent chronic pain, osteoarthritis, and long-term valgus instability [6]. This patient underwent arthroscopic ACL and PCL reconstructions, partial meniscectomies, and open MCL repair, with a good functional outcome after one year of follow-up.

Take Home Message

In conclusion, Stener-like lesions should be considered in the differential diagnosis of MCL injuries. MRI is often required to establish a diagnosis of Stener-like lesion and aids clinicians in choosing the appropriate treatment. Tear of the MCL with a Stener-like lesion tends to require open surgical repair as the interposing pes anserinus tissue or osseous structures impair healing.

All patient data have been completely anonymised throughout the entire manuscript and related files.