Novel press-fit technique of patellar bone plug in anterior cruciate ligament reconstruction is comparable to interference screw fixation

Abstract

Conventional press-fit technique for anterior cruciate ligament reconstruction (ACLR) is performed with extraction drilling of the femoral bone tunnel and manual shaping of the patellar bone plug. However, the disadvantages of this technique include variation in bone plug size and thus the strength of the press-fit fixation, bone loss with debris distribution within the knee joint, potential heat necrosis, and metal wear debris due to abrasion of the guide wire. To overcome these disadvantages, a novel technique involving punching of the femoral bone tunnel and standardized compression of the bone plug was introduced. In this study, the fixation strength was tested and compared to that of the gold-standard interference screw fixation technique in three flexion angle configurations (0°/ 45°/ 90°) in a porcine model. We hypothesized that the newly developed standardized press fit fixation would not be inferior to the gold standard method.Methods Sixty skeletally mature porcine knees (30 pairs) were used. Full-thickness central third patellar tendon strips were harvested, including a patellar bone cylinder of 9.5 mm in diameter. The specimens were randomly assigned to 10 pairs per loading angle (0°, 45°, 90°). One side of each pair was prepared with the press-fit technique, and the contra-lateral side was prepared with interference screw fixation. Equivalent numbers of left and right-sided samples were used for both fixation systems. A three-way multifactor ANOVA was carried out to check for the influence of a) fixation type, b) flexion angle, and c) side of the bone pair. ResultsThe primary fixation strength of femoral press-fit graft fixation with punched tunnels and standardized bone plug compression did not differ significantly from that of interference screw fixation (p=0.5128), which had mean loads to failure of 422.4±134.6 N and 445.4±135.8 N, respectively. The flexion angle had a significant influence on the maximal load to failure (p=0.0097). Load values were highest in 45° flexion for both fixations.The anatomical side R/L was not a statistically significant factor (p=0.7888). ConclusionThe primary fixation strength of femoral press-fit graft fixation with punched femoral tunnels and standardized bone plug compression is equivalent to that of interference screw fixation in a porcine model. Therefore, the procedure represents an effective method for ACL reconstruction with patellar or quadriceps tendon autografts including a patellar bone plug.

Tibial tunnel enlargement is affected by the tunnel diameter-screw ratio in tibial hybrid fixation for hamstring ACL reconstruction

“…At last, no statement regarding interference screw fixation of a bone plug ACL graft is possible. Future studies need to explore if there is a difference regarding tunnel widening in case of patellar bone plug fixation in press-fit technique or with an interference screw (gold-standard) [ 29 ], or in case of foreign material free ACL reconstruction (with a cortical-cancellous bone cylinder sutured into the hamstring autograft) [ 30 ].…”

Triple Hybrid Tibial Anterior Cruciate Ligament Graft Fixation

“… 4 , 6 , 7 Hardware-free press-fit techniques have been reported, showing promising outcomes comparable with traditional techniques with low rates of tunnel enlargement. 8 , 9 , 10 In terms of subjective patient-reported outcomes, recent meta-analyses showed no differences. 9 , 11 , 12 , 13 …”

Current trends in graft choice for anterior cruciate ligament reconstruction – part I: anatomy, biomechanics, graft incorporation and fixation

“…Hardware-free press-fit techniques have been reported, showing promising outcomes comparable to traditional techniques with low rates of tunnel enlargement [ 4 , 10 , 44 , 106 ].…”