Review Question - QID 220016

For an anatomic reconstruction of the MCL, the graft should be placed at the anatomic origins and insertions of the sMCL. The sMCL origin is 3.2 mm proximal and 4.8 mm posterior to the medial epicondyle. The most distal insertion is 6 cm distal to the joint line. This is most depicted in the figure by locations B and 3 (answer choice 2).

The medial collateral ligament (MCL), or tibial collateral ligament, is the key structure to valgus stabilization of the knee. The MCL comprises a deep MCL (dMCL) and a superficial MCL (sMCL). The sMCL originates on the femur 3.2 mm proximal and 4.8 mm posterior to the medial epicondyle. On the tibia, the sMCL has 2 insertion sites, proximally 11.2 mm distal to the joint line and distally 6 cm directly onto the bone. Injuries to the MCL can occur with valgus stress or direct lateral trauma. Injuries are classified by severity into grade 1 (sprain), grade 2 (partial tear), and grade 3 (complete tear). Grade 3 injuries are often indicated for surgical intervention in the form of repair versus reconstruction. When reconstructing the sMCL anatomically, a graft is used to reconstruct the ligament to its anatomic footprints.

Wijdicks et al. performed a biomechanical study of superficial medial collateral ligament (sMCL) repair techniques. Using 18 matched-pair cadaveric knees, the authors compared the biomechanical efficacy of an anatomic augment repair and anatomic reconstruction techniques. In both techniques, the augmentation or reconstruction was placed at the anatomic footprint of the sMCL, 3.2 mm proximal and 4.8 mm posterior to the medial epicondyle proximally, and 6 cm distal to the joint line distally. The authors concluded that both techniques offer comparable improvement of knee stability in sMCL injuries, but both fell short of fully restoring native knee kinematics.

Laprade et al. published results of a surgical technique for anatomic reconstruction of medial-sided knee structures, the sMCL, and the posterior oblique ligament (POL). The study included 28 patients who underwent the medial knee reconstruction with follow-up of at least 6 months (avg. 1.5 years). The authors report reconstructing the sMCL from a point on the femur that was slightly proximal and posterior to the medial epicondyle to a point 6 cm distal to the joint line on the tibial. Postoperatively, patients had improved knee scores and decreased valgus gapping, indicating enhanced knee stability. The authors concluded that an anatomic reconstruction technique improves patient function and restores valgus stability in medial-sided knee injuries.

Figure A is a lateral radiograph of the knee with the medial epicondyle (ME) and adductor tubercle (AT) noted. Illustration 1 is an image from Laprade et al. demonstrating the anatomy of the medial side of the knee with labeled structures.

Incorrect Answers:
Answers 1, 3, 4, and 5: These locations do not demonstrate the correct origin or distal extent of sMCL. The sMCL origin is 3.2 mm proximal and 4.8 mm posterior to the medial epicondyle. It has been reported to be 1 cm anterior and distal to the adductor tubercle. Both descriptions place the origin between the adductor tubercle and the medial epicondyle, indicated by the letter B. The most distal insertion of the sMCL is 6 cm distal to the joint line. Location 1 on the tibia would indicate the proximal attachment of the sMCL on the tibia, not the distal attachment. Location 2 better represents the pes anserinus, or hamstring tendons, attachment on the anteromedial tibia.