Tunnel widening in anterior cruciate ligament reconstruction: a prospective evaluation of hamstring and patella tendon grafts

Abstract

We report a prospective series evaluating the incidence and degree of tunnel widening in a well-matched series of patients receiving a hamstring or patella tendon graft for anterior cruciate ligament (ACL) deficiency. We correlated tunnel widening with clinical factors, knee scores, KT-1000 and isokinetic muscle strength to determine the clinical significance of this finding. Seventy-three patients at least 12 months post-ACL reconstruction were evaluated. Thirty-eight patients had received a doubled semitendinous and gracilis graft and 35 a bone-patella tendon-bone graft. All patients underwent a similar endoscopic procedure and accelerated postoperative rehabilitation. Tunnel widening was determined using standardized anteroposterior (AP) and lateral X-rays adjusted for magnification. A limited series of MRIs was performed to validate these measurements. There was a significant difference in the degree of tunnel widening between the two groups. The mean increase in femoral tunnel area in the hamstring group was 100.4% compared with a decrease of 25% in the patella tendon group (P = < 0.0001). In the tibial tunnel the mean increase in the hamstring group was 73.9% compared with a decrease of 2.1% in the patella tendon group (P = < 0.0001). The MRIs validated the plain film measurements. Tunnel widening did not correlate with the clinical findings, knee scores, KT-1000 or isokinetic muscle strength. Tunnel widening is marked in the hamstring group. Tunnel widening does not correlate with instability or a poor clinical outcome in the short term. The long-term implications of this finding are still to be determined.

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].…”

Differences in Tendon Graft Healing between the Intra-articular and Extra-articular Ends of a Bone Tunnel

“…Several prior studies have demonstrated a reduction in construct stiffness and secondary increases in graft-tunnel motion with increased distance between fixation points (Fig. 8) [21,[30][31][32][33][34][35][36]. Progressively greater graft-tunnel motion occurs as the distance between the fixation point increases, resulting in greater graft-tunnel motion at the tunnel aperture than at the extra-articular end of the tunnel for grafts fixed with suspensory fixation.…”

Improved outcomes after anterior cruciate ligament reconstruction with quadrupled hamstring autografts and additional bone plug augmentation at five year follow-up

“…However, significant bone tunnel widening (TW) has been observed for this fixation method at short-term follow-up [3]. Although the overall amount of tunnel widening was not found to be correlated with functional outcomes in terms of knee stability and function [4,5], it seems reasonable to try to avoid or at least to reduce it.…”