How to Avoid Graft-Tunnel Length Mismatch in Modified Transtibial Technique for Anterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone Graft

Abstract

BackgroundWe conducted this study to determine the optimal length of patellar and tibial bone blocks for the modified transtibial (TT) technique in anterior cruciate ligament (ACL) reconstruction using the bone-patellar tendon-bone (BPTB) graft.MethodsThe current single-center, retrospective study was conducted in a total of 64 patients with an ACL tear who underwent surgery at our medical institution between March 2015 and February 2016. After harvesting the BPTB graft, we measured its length and that of the patellar tendon, patellar bone block, and tibial bone block using the arthroscopic ruler and double-checked measurements using a length gauge. Outcome measures included the length of tibial and femoral tunnels, inter-tunnel distance, length of the BPTB graft, patellar tendon, patellar bone block, and tibial bone block and graft-tunnel length mismatch. The total length of tunnels was defined as the sum of the length of the tibial tunnel, inter-tunnel distance and length of the femoral tunnel. Furthermore, the optimal length of the bone block was calculated as (the total length of tunnels − the length of the patellar tendon) / 2. We analyzed correlations of outcome measures with the height and body mass index of the patients.ResultsThere were 44 males (68.7%) and 20 females (31.3%) with a mean age of 31.8 years (range, 17 to 65 years). ACL reconstruction was performed on the left knee in 34 patients (53%) and on the right knee in 30 patients (47%). The optimal length of bone block was 21.7 mm (range, 19.5 to 23.5 mm). When the length of femoral tunnel was assumed as 25 mm and 30 mm, the optimal length of bone block was calculated as 19.6 mm (range, 17 to 21.5 mm) and 22.1 mm (range, 19.5 to 24 mm), respectively. On linear regression analysis, patients' height had a significant correlation with the length of tibial tunnel (p = 0.003), inter-tunnel distance (p = 0.014), and length of patellar tendon (p < 0.001).ConclusionsOur results indicate that it would be mandatory to determine the optimal length of tibial tunnel in the modified TT technique for ACL reconstruction using the BPTB graft. Further large-scale, multi-center studies are warranted to establish our results.

Effect of Patient Height and Sex on the Patellar Tendon and Anterior Cruciate Ligament

“…Increasing height has been associated with greater IAL. 2 , 9 A previous study by Ko et al 9 on avoiding BTB allograft mismatch found a strong positive correlation between individual height and intra-articular length of the ACL with in situ measurements during surgery. Another MRI measurement study by Goldstein et al 5 on BTB allograft mismatch reported significantly shorter (3 mm) PTL in women compared with men; however, the mean height per group was not reported and analysis of the reported data suggested shorter height.…”

“…Increasing height has been associated with greater IAL. 2,9 A previous study by Ko et al 9 on avoiding BTB allograft Example of patellar tendon length, Caton-Deschamps Index (CDI), and intra-articular ACL length measurements performed on T1-weighted sagittal magnetic resonance imaging. Yellow lines refer to parameters measured on MRI.…”

“…Previous studies have shown that patient height is associated with the lengths of both intra-articular ACL 2 , 9 and patellar tendon. 5 A long patellar tendon has been associated with graft-tunnel mismatch.…”

Rule 50: A Reproducible Technique to Minimize Graft-tunnel Mismatch During ACL Reconstruction Using Bone-Tendon-Bone (BTB) Graft

“…This paper involved a single surgeon's review of 64 autologous BTB grafts used during ACL reconstruction where the surgeon would drill the femoral and tibial tunnels (tibial tunnel drilled at 50 degrees) before harvesting the graft. 10 It was not described how it was determined how long the femoral tunnel was drilled but the overall average was 29.2 mm. The length of the tunnels and intra-articular distance was measured and using these 3 measurements, the graft would be harvested according to that length.…”

“…One of the closest techniques to Rule 50 was described in 2018 for ACL reconstruction via modified transtibial technique. This paper involved a single surgeon’s review of 64 autologous BTB grafts used during ACL reconstruction where the surgeon would drill the femoral and tibial tunnels (tibial tunnel drilled at 50 degrees) before harvesting the graft 10. It was not described how it was determined how long the femoral tunnel was drilled but the overall average was 29.2 mm.…”