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

We report a prospective series evaluating the incidence and degree of tunne l widening in a well-matched series of patients receiving a hamstring or pa tella tendon graft for anterior cruciate ligament (ACL) deficiency. The cor related tunnel widening with clinical factors, knee scores, KT-1000 and iso kinetic muscle strength to determine the clinical significance of this find ing. 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 underw ent a similar endoscopic procedure and accelerated postoperative rehabilita tion. Tunnel widening was determined using standardized anteroposterior (AP ) and lateral X-rays adjusted for magnification. A limited series of MRIs w as performed to validate these measurements. There was a significant differ ence in the degree of tunnel widening between the two groups. The mean incr ease 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 valida ted the plain film measurements. Tunnel widening did not correlate with the clinical findings, knee scores. KT-1000 or isokinetic muscle strength. Tun nel widening is marked in the hamstring group. Tunnel widening does not cor relate with instability or a poor clinical outcome in the short term. The l ong-term implications of this finding ale still to be determined.