High non-anatomic tunnel position rates in ACL reconstruction failure using both transtibial and anteromedial tunnel drilling techniques

Although it is well known from cadaveric and biomechanical studies that transtibial femoral tunnel (TT) positioning techniques are associated with non-anatomic tunnel positions, controversial data exist as so far no clinical differences could have been found, comparing transtibial with anteromedial techniques (AM). The purpose of the study was to analyze if graft failure following TT ACL reconstruction was more commonly associated with non-anatomic tunnel position in comparison with the AM technique. We hypothesized that, compared to AM techniques, non-anatomic tunnel positions correlate with TT tunnel positioning techniques. A total of 147 cases of ACL revision surgery were analyzed retrospectively. Primary ACL reconstructions were analyzed regarding the femoral tunnel drilling technique. Femoral and tibial tunnel positions were determined on CT scans using validated radiographic measurement methods. Correlation analysis was performed to determine differences between TT and AM techniques. A total of 101 cases were included, of whom 64 (63.4%) underwent the TT technique and 37 (36.6%) the AM technique for primary ACL reconstruction. Non-anatomic femoral tunnel positions were found in 77.2% and non-anatomical tibial tunnel positions in 40.1%. No correlations were found comparing tunnel positions in TT and AM techniques, revealing non-anatomic femoral tunnel positions in 79.7 and 73% and non-anatomic tibial tunnel positions in 43.7 and 35.1%, respectively (p > 0.05). Considerable rates of non-anatomic femoral and tibial tunnel positions were found in ACL revisions with both transtibial and anteromedial femoral drilling techniques. Despite the potential of placing tunnels more anatomically using an additional AM portal, this technique does not ensure anatomic tunnel positioning. Consequently, the data highlight the importance of anatomic tunnel positioning in primary ACL reconstruction, regardless of the applied drilling technique.