Bone Tunnel Enlargement After Anterior Cruciate Ligament Replacement

Abstract

Radiographic increase in the size of tibial and femoral tunnels has been observed. This retrospective study compared tibial tunnel diameter in 56 autograft and 87 allograft patellar tendon bone-tendon-bone anterior cruciate ligament replacements whose observed tunnel changes were correlated with clinical results at 1 year postoperatively. Tibial tunnel sclerotic margins were measured approximately 1 cm below the joint line. Exact tunnel dimension was calculated by using a magnification factor determined by the interference screw of known diameter within the same tunnel. Average allograft tunnel enlargement was 1.2 mm (-2.5 to 6.0) compared with the autograft tunnel enlargement of 0.26 mm (-2.5 to 2.7); the difference was significant (P > 0.0002). No significant difference was seen in KT-1000 arthrometer measurements between autograft or allograft groups, and no correlation was seen between increased tunnel size and clinical outcome as determined by the modified Hughston knee evaluation system. Tunnel measurement reproducibility was confirmed by independent repeated measurements. The significance of this tunnel enlargement is unknown and does not appear to adversely affect clinical outcome of allograft utilization. Possible explanations include an immune response with resorption, stress shielding proximal to the interference screw resulting in resorption, or an inflammatory response by synovium in the tunnel.

Evaluation of tibial bone-tunnel changes with X-ray and computed tomography after ACL reconstruction using a bone-patella tendon-bone autograft

“…The longer lever arm on the tibial side causes more mechanical stress Fig. 4 a, clinical results [1][2][3][4]14]. We have one explanation for this result: the bone-tunnel changes are not only circular.…”

“…Some reports customarily use the distance of the sclerotic outer margins of the bone tunnel as a sign of enlargement [1][2][3][4][5]. However, inclusion of the sclerotic area in the enlargement is controversial.…”

“…In recent years there have been some reports of bone-tunnel enlargement after ACL reconstruction using autografts [4,5]. Most reports have identified that the bonetunnel enlargement as evaluated with X-rays did not correlate with knee instability [1][2][3][4]14]. On the other hand, a few reports have shown that bone-tunnel enlargement was related to clinical results [7].…”

Radiological and clinical evaluation amongst types of tibial tunnel widening and choice of graft fixation implants in ACL reconstruction

“…In our study, we have used only hamstring tendon as a graft choice so that graft type doesn't become a confounding variable when we compare screw group and disc group. On the other hand, allografts were found to have greater amount of tunnel widening than the patellar tendon autograft [11] Graft fixation systems have been described with different names in literature like anatomic vs. nonanatomic, elastic vs. rigid, suspensory vs. cortical fixation or outlet fixation. Giovanni has classified graft fixation systems into following: [2] 1) Compression system like interference screw which holds the tendon graft tightly against the bone tunnels more rigidly.…”

Prospective randomised comparison of femoral transfix versus endobutton with constant tibial fixation in hamstring tendon ACL reconstruction: a preliminary study

“…7 However, bone tunnel enlargement has been reported after using this technique for ACL reconstruction, but the importance of tunnel enlargement is not clear, because clinically these patients did well after the ACL reconstruction. 8 As loosening and the failure of the neo ACL graft are more common at the femoral site, more information is needed about the femoral site fixation. 9 So keeping the tibial site fixation identical, a comparative study is needed, of the outcome of the two techniques of femoral site fixation i.e.…”