Poster 305: Hybrid Transtibial Technique for Femoral Tunnel Drilling in Anterior Cruciate Ligament Reconstruction: A Retrospective, Matched Comparison Study to Anteromedial Portal and Transtibial Approaches

Objectives: Improved biomechanical and clinical outcomes have been reported when femoral anterior cruciate ligament (ACL) tunnels are centered on the native footprint. The anteromedial portal (AMP) technique achieves improved aperture position when compared to a transtibial (TT) approach but sacrifices technical ease and creates a shorter more angulated tunnel. A hybrid transtibial technique (HTT) using medial portal guidance of a flexible transtibial guide wire may combine the strengths of both the AM and TT approaches while mitigating the technical challenges of both techniques. The purpose of our study was to evaluate the clinical efficacy of ACLR using a HTT technique for femoral tunnel drilling in comparison to matched cohorts of AMP and TT drilling approaches in terms of failure/revision requirements and patient-reported outcomes. Methods: A database consisting of all patients with isolated ACL tear and primary reconstruction at a single center between 2005 and 2020 was retrospectively reviewed. Inclusion criteria were patients age ³ 13 years at the time of index ACL reconstruction (ACLR), isolated ACL tear with/without concomitant meniscal/chondral pathology and had minimum 2 year ³ postoperative follow-up. Patients with open physes, prior surgical intervention on the ipsilateral knee, chondral pathology treated with high tibial osteotomy/distal femoral osteotomy, treated for other concurrent ligamentous pathology were excluded. Patients treated with the AMP, TT, and HTT approach meeting inclusion criteria were matched based on age ± 3 years, same sex, and body mass index (BMI) ± 3 Kg/m 2 . Demographical data (Table 1), surgical data, plain radiographic femoral tunnel angle measurements on anteroposterior and lateral films, postoperative complications and reoperation/revision rates, and patient reported outcome (PRO) scores were collected and reported for each of the three cohorts. Results: A total of 495 patients were included; 170 patients underwent ACLR using the HTT approach, 162 using AMP approach, and 163 using the TT approach. The most common graft of choice for HTT technique was bone patellar tendon bone (BPTB) (162/170 [95.3%]) and for AMP (131/162 [80.9%] and TT (158/163 [96.9%]) technique was hamstring (Table 2). The median (IQR) femoral tunnel angle on sagittal plane showed significant differences between HTT 40° (34°, 46°) and TT 32° (27°, 38°) cohorts ( P- value < 0.0001) (Table 3). On coronal plane the median (IQR) femoral tunnel angles showed significant differences between HTT 47° (42°, 52°) and for both AMP 44° (33°, 54°) and TT 55° (47°, 60°) cohorts ( P- value: 0.001 and <0.001 respectively. Recurrent ACL injury in the ipsilateral knee was experienced in 3/170 (1.8%) HTT patients, 6/162 (3.7%) AMP patients, and 6/163 (3.7%) TT patients at minimum 2-year clinical follow-up (Table 4). When patients were surveyed via phone or email questionnaires, 6/170 (7.4%) HTT, 11/163 AMP (20%), and 18/162 (24.3%) TT patients responded to having further ACLR procedures. The Knee injury and Osteoarthritis Outcome Score (KOOS) pain score and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) function and total scores were found to be statistically significant between HTT and TT technique patients. All other PRO scores showed comparable scores between HTT patients when compared with AMP and TT patients. Conclusions: Patients that underwent ACLR with HTT approach had lower failure/revision rates and comparable or better PRO scores at medium-term follow-up when compared to AMP and TT approach. [Table: see text][Table: see text][Table: see text][Table: see text]