Radiologic maturation and tunnel changes after all-inside versus standard hamstring ACL reconstruction: a prospective...

To compare MRI-based graft maturation and tibial tunnel behavior in all-inside anterior cruciate ligament (ACL) reconstruction using either a quadrupled semitendinosus (ST4) graft or a standard doubled semitendinosus-gracilis (DSTG) technique and to assess mid-term clinical outcomes.

This is a single-center prospective comparative cohort with sequential, non-randomized allocation. Primary imaging endpoints were graft signal-to-noise quotient (SNQ, PD-FS) and tibial tunnel cross-sectional area (CSA) change; clinical endpoints included PROMs and laxity at ≥ 24 months. Reliability was assessed with two independent evaluators and reported using ICC (two-way random, absolute agreement) with 95% CIs.

Forty patients (n = 20 per group) completed MRI at 12 months and clinical follow-up at 24 months. SNQ was similar between groups (ST4 1.94 [95% CI 1.28-2.60] vs DSTG 2.84 [1.93-3.75]; difference - 0.90 [- 1.99 to 0.19], P = 0.39). Tibial tunnel widening was lower with ST4 (45.5% [23.7-67.3]) versus DSTG (106.7% [78.3-135.1]); difference - 61.2% [- 95.8 to - 26.6]; P = .02. PROMs and laxity were comparable.

AI-ST4 and DSTG ACL reconstruction demonstrated similar graft maturation at 12 months, with less tibial tunnel widening after AI-ST4. At 24 months, clinical outcomes were equivalent between groups; although SNQ and tibial tunnel CSA demonstrated good reproducibility, these imaging differences were not demonstrably associated with functional superiority.