Notchplasty in anterior cruciate ligament reconstruction in the setting of passive anterior tibial subluxation

- Anterior tibial translation (ATT) occurs in the ACL deficient knee
- This study investigates ATT and intra-operative notchplasty in the various ACL deficient states
- ATT differs significantly among acute, chronic and failed ACL reconstructions
- Attention should be paid peri-operatively to the required volume and location of the notchplasty

PurposeIn an effort to minimize graft impingement among various ACL deficient states, we sought to quantitatively determine requirements for bone resection during notchplasty with respect to both volumetric amount and location.MethodsA validated method was used to evaluate Magnetic Resonance Imaging scans. We measured the ATT of the medial and lateral compartments in the following four states: intact ACL (27 patients), acute ACL disruption; < 2 months post-injury (76 patients), chronic ACL disruption; 12 months post-injury (42 patients) and failed ACL reconstruction (75 patients). Subsequently, 11 cadaveric knees underwent Computed Tomography (CT) scanning. Specialized software allowed virtual anterior translation of the tibia according to the average ATT measured on MRI. Impingement volume was analyzed by performing virtual ACLRs onto the various associated CT scans. Location was analyzed by overlaying an on-screen protractor. The center of the notch was defined as 0°.ResultsAverage impingement volume changed significantly in the various groups compared to the intact ACL group (acute 577 ± 200 mm3, chronic 615 ± 199 mm3, failed ACLR 678 ± 210 mm3, p = 0.0001). The location of the required notchplasty of the distal femoral wall border did not change significantly. The proximal femoral border moved significantly towards the center of the notch (acute 8.6° ± 4.8°, chronic 7.8° ± 4.2° (p = 0.013), failed ACLR 5.1° ± 5.9° (p = 0.002)).ConclusionOur data suggests that attention should be paid peri-operatively to the required volume and location of notchplasty among the various ACL deficient states to minimize graft impingement.