Objective: Restoration of knee stability after rerupture of an anterior cruciate ligament (ACL) graft.
Indication: Acute and chronic functional instability with rerupture of an ACL graft with subjective instability with anatomical or non-anatomical bone tunnel without tunnel widening.
Contraindications: Partial anatomical bone tunnels of the previous operation, significant tunnel widening of anatomical bone tunnels, local infection of the knee joint, local soft tissue damage.
Surgical technique: Graft choices are hamstring tendons (semitendinosus muscle, gracilis muscle), the quadriceps tendon, patellar tendon and a peroneus tendon split graft. In cases with anatomical tunnels, careful debridement is performed down to the tunnel wall. In non-anatomical tunnels, a new femoral tunnel is drilled over a deep anteromedial portal with the knee flexed more than 110° in the insertion area of the ACL. Using drills and dilators, a tunnel is prepared. At the tibia, the anterior horn of the lateral meniscus serves as a landmark in the absence of an ACL stump. The cortical tibial tunnel aperture is probed with a guide wire and the tunnel is drilled stepwise until the tunnel wall is reached, which is debrided with a spoon or synovial resector to remove graft residues and implants from the tunnel. The femoral fixation can either be done with a flip button, an interference screw or in the case of a bone block graft implant-free. At the tibial side, the graft is fixed with a resorbable interference screw and fixation button.
Postoperative management: The rehabilitation program comprises 4-5 phases. Inflammatory phase (weeks 1-2): control of pain and swelling (cooling, isometric tension exercises, 20 kg partial load). Phase 2 (weeks 2-6): increasing load and range of motion with closed chain exercises (target: extension/flexion 0-0-120°). Phase 3 (from week 6): strength and coordination exercises. Phase 4: balance, strength and jump exercises. Return to competitive sport not before postoperative month 6-10.
Results: Included were 51 patients with recurrent instability after ACL surgery where primary ACL replacement was performed with ipsilateral bone quadriceps tendon graft or contralateral semitendinosus-gracilis graft. All patients had anatomical or non-anatomical tunnel locations without significant widening (>11 mm). After 2 years, the side-to-side difference for anterior tibial translation measured with the KT 1000 arthrometer was 2.0 ± 1.2 mm for the quadriceps group and 3.0 ± 2.9 mm for the semitendinosus-gracilis group (P = 0.461). No difference in the rate of positive pivot shift tests (P = 0.661); no significant difference in the individual Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores or in the frequency of anterior knee pain.
Keywords: Grafts; Joint instability; Knee joint; Revision surgery; Tendon transfer.