Anatomical Dissection and CT Imaging of the Anterior Cruciate and Medial Collateral Ligaments in Skeletally Immature Cadaver Knees

OBJECTIVES: Combined anterior cruciate ligament (ACL) and medial collateral ligament (MCL) are increasingly recognized in skeletally immature patients. Although most MCL injuries heal, some may require reconstruction. The purpose of this study was to identify the origin and insertion of the ACL and MCL, and determine the attachment locations in relation to the physes in skeletally immature knees. METHODS: Seven skeletally immature cadaver knee specimens were dissected. These specimens were divided into two groups: Infants (ages-1, 11, and 11 months), and Children (ages 8, 10, 11, and 11 years). Metallic markers were placed at the midpoint of the femoral origins and tibial insertions of the ACL and MCL. CT scans with 1mm slices were obtained for each specimen and were analyzed using Osirix Imaging Software. The distance from both the ACL and MCL femoral origin midpoints to the distal femoral physis was measured. The distance from the ligaments’ insertion midpoints to the proximal tibial physis was measured. RESULTS: The mean distance from the ACL origin midpoint to the femoral physis was 0.63 cm (0.58-0.68 cm) and 0.85 cm (0.75-0.97 cm) distal to the physis for infants and children, respectively. The mean distance from the MCL origin midpoint to the lowest point of the femoral physis was 0.78 cm distal to the physis for one infant. For 2/3 children, this measurement was 0.60 cm distal to the physis, and 0.37 cm proximal to the physis for one child. In three specimens, this measurement could not be taken. The mean distance from ACL insertion midpoint to the proximal tibial physis was 0.39 cm (0.62-1.15 cm) and 1.74 cm (1.46-2.15 cm) proximal to the physis for infants and children, respectively. The mean distance from the MCL insertion midpoint to the tibial physis was 0.76 cm (0-2.28 cm) and 3.52 cm (2.29-4.60 cm) distal to the physis for infants and children, respectively. CONCLUSION: Pediatric cadaver tissue is very difficult to obtain for research, and many anatomic studies in skeletally immature patients are based on MRI sequences. This cadaveric dissection with CT scan clarifies the location of the ACL and MCL with respect to the femoral and tibial physes. This information may be useful to help surgeons avoid physeal injury during ACL/MCL reconstructions in skeletally immature patients.