Tibial tunnel expansion does not correlate with four-strand graft maturation after ACL reconstruction using adjustable cortical suspensory fixation

Abstract

PurposeAnterior cruciate ligament reconstruction (ACLR) using a short, quadrupled semitendinosus (ST‐4) autograft, fixed with an adjustable suspensory fixation (ASF), has several potential advantages. However, the construct is suspected to generate micromotion, tunnel widening and poor graft maturation. The aim of this study was to evaluate post‐operative tibial tunnel expansion, graft maturation and clinical outcomes for this type of ACLR. MethodsOne‐hundred and forty‐nine patients were reviewed at a minimum of 2 years following 4‐ST ACLR, mean 25.6 ± 3.5 months [24–55], with clinical follow‐up and MRI scans. Graft maturity of the intra‐articular part of the graft and the tibial tunnel portion was assessed using Signal‐to‐Noise Quotient (SNQ) and Howell score. Tibial tunnel expansion, bone–graft contact and graft volume in the tibial tunnel were calculated from the MRI scans. ResultsMean tibial tunnel expansion was 13 ± 16.5% [12–122]. Mean SNQ for graft within the tibial tunnel was 3.8 ± 7.1 [ – 7.7 to 39] and 2.0 ± 3.5 [ – 14 to 17] for the intra‐articular portion of the graft. The Howell score for graft within the tibial tunnel was 41% Grade I, 37% Grade 2, 20% Grade 3, 2% grade 4, and for the intra‐articular part 61% Grade 1, 26% Grade 2, 13% Grade 3 and 1% Grade 4. The mean tibial tunnel bone–graft contact was 81 ± 23% [0–100] and mean graft volume was 80 ± 22% [0–100]. No correlation was found between tibial tunnel expansion and graft maturity assessed at both locations. Graft maturity was correlated with higher graft‐bone contact and graft volume in the tibial tunnel (p < 0.05). ConclusionsST‐4 ACLR with ASF had low levels of tunnel enlargement at 2 years. No correlation was found between graft maturation and tibial tunnel expansion. Graft maturity was correlated with graft–bone contact and graft volume in the tibial tunnel. Level of evidenceLevel III.

Preserving the Semitendinosus Distal Attachment Is Associated With Improved Graft Remodeling After ACL Reconstruction

“…Fifth, the TTW was about 70% in the 2 groups, which is not consistent with the literature. 2,11,27 Although it is possible the measurement method was not accurate, our results are similar to other published measurements. 7,8 Sixth, this was a single-center study featuring a surgical technique practiced by a single surgeon.…”

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

“…Animal studies also suggest that higher graft-to-bone contact area has positive effects on tendon–bone healing, especially in the early period after ACL-R [ 12 , 23 , 132 ]. Additionally, healing is sensitive to dynamic changes in graft forces, with early high forces on the ACL graft appearing to impair graft-tunnel osseointegration [ 72 ].…”

Serial change of femoral and tibial tunnel width after anterior cruciate ligament reconstruction with allograft

“…It was aimed to investigate (1) serial changes in the femoral and tibial tunnels and (2) the correlation between tunnel widening and postoperative outcomes after ACL reconstruction using allografts. It was hypothesized that the amount of tunnel widening would decrease over time and that a large amount of tunnel widening is associated with inferior knee anterior stability.…”

“…Allograft-related factors associated with tunnel widening include biological factors and immune responses. Moreover, the toxicity of chemicals used during allograft processing is a potential risk factor for tunnel widening [1,25]. Most previous clinical studies measured tunnel widening in single follow-up studies with no serial evaluation [14,20].…”

“…Tunnel widening is an unexpected adverse event after anterior cruciate ligament (ACL) reconstruction. Since its conceptualization in the 1990s, numerous studies on tunnel widening after ACL reconstruction have been published [1, 3]. However, the aetiology of tunnel widening is not yet fully understood.…”