Abstract
BackgroundFemoral malposition is the first cause for graft rupture during ACL reconstruction. Arthroscopic landmarks can be difficult to identify. So, landmark has to be found for reliable tunnel placement. A proximal-distal reference was described as “Apex reference” reported by Hart et al. but no posterior/anterior reference exists in the literature.The purpose of this study was to do a 3D CT-scan assessment of the femoral tunnel positioning using the Capsular Line Reference (CLR) as a landmark for posterior/anterior placement in ACL reconstruction. We hypothesized the CLR could provide a precise and reliable antero/posterior femoral tunnel positioning less than 2 mm from the Bernard & Hertel posterior quarter.MethodsSeven cadaveric knee specimens with a mean age of 79.2 ± 11 years were used. Using standard approaches, the CLR was identified corresponding to a white line (the capsule) appearing at the posterior border of the femoral condyle after bony debridement of the medial and posterior part of the lateral femoral condyle. The center of the tunnel was marked. An inside-out technique with anteromedial drilling technique was performed using an 8-mm diameter reamer. The distal femurs were sawed and a CT-scan was done for each specimen to obtain 3-dimensional image reconstructions. These 3D reconstructions were analyzed to measure the position tunnel center on the posterior/anterior axis and the distance from the posterior/anterior quadrant according to the Bernard & Hertel method.ResultsThe mean position for the posterior/anterior axis was 27.0 ± 1.8% (25–28.9) with a median of 26.9%. The position from the first quarter of the Bernard & Hertel method was 0.9 ± 0.8 mm (0–1.8) with a median of 0.8 mm.ConclusionThe CLR is a reliable and reproducible arthroscopic landmark to place the femoral tunnel for ACL reconstruction in the anterior/posterior axis. Proximal/distal position depends on the choice of the surgeon to reproduce anteromedial or posterolateral fibers.
Highlights
Femoral malposition is the first cause for graft rupture during anterior cruciate ligament (ACL) reconstruction
Full anatomic ACL reconstruction remains a challenge, and the best we can achieve is a compromise between anatomy, biomechanics and isometry
Some authors have shown that proper placement is related to the angle of knee flexion (Markolf et al, 2009), so the apex of posterior cartilage was recently reported as a better anatomical bony landmark for the proximal/ distal position (Hart et al, 2015)
Summary
Femoral malposition is the first cause for graft rupture during ACL reconstruction. Arthroscopic landmarks can be difficult to identify. Arthroscopic ACL reconstruction is a technically demanding surgery and surgeons need recognizable bony landmarks in order to secure the tunnel placement. Many surgeons use the “classic clock face” centered in the notch, to place the tunnel center in proximal and distal position This clock face technique is not precise enough and has been reported as lacking accuracy and precision for femoral tunnel placement (Azzam et al, 2011; Loriaut et al, 2017; Momaya et al, 2017). Some authors have shown that proper placement is related to the angle of knee flexion (Markolf et al, 2009), so the apex of posterior cartilage was recently reported as a better anatomical bony landmark for the proximal/ distal position (Hart et al, 2015). Proximal/distal positioning depends on the ACL fibers the surgeon wishes to reconstruct: Antero-medial (AM) fibers are in the proximal part of the notch while Postero-lateral (PL) fibers are distal and both are anatomical
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