Effects of initial graft tension on femoral tunnel widening after anatomic anterior cruciate ligament reconstruction using a bone-patellar tendon-bone graft.

INTRODUCTION: The effects of initial graft tension upon tunnel widening (TW) following anatomic anterior cruciate ligament (ACL) reconstruction have not been elucidated. The purpose of this study was to retrospectively investigate the effect of two different graft-tensioning protocols upon femoral TW following anatomic ACL reconstruction using a bone-patellar tendon-bone (BPTB) graft and a three-dimensional (3D) computed tomography (CT) model. METHODS: Forty-three patients who underwent isolated ACL reconstruction using BPTB grafts were included in this study. In 18 out of the 43 patients, the graft was fixed at full knee extension with manual maximum pull (Group H). These patients were compared with 25 patients in whom the BPTB graft was fixed at full knee extension with 80-N pull (Group L). Tunnel aperture area was measured using 3D CT 1 week and 1 year postoperatively, thus enabling us to calculate the percentage change in the area of femoral tunnel aperture. Clinical assessment was performed 1 year postoperatively, corresponding to the time period of CT assessment, and involved the evaluation of Lysholm score, anterior knee stability using a KneeLax3 arthrometer, and the pivot-shift test. RESULTS: When measured at 1 year postoperatively, the mean area of the femoral tunnel aperture had increased by 78.6 ± 36.8% in Group H when compared with at 1 week postoperatively, whereas that of Group L had increased by 27.7 ± 32.3%. Furthermore, TW (%) in Group H was significantly greater than that of Group L (P < 0.001). No significant differences were detected between the two groups with regard to any of the clinical outcomes evaluated. CONCLUSION: High levels of initial graft tension resulted in greater TW of the femoral tunnel aperture following anatomical ACL reconstruction using BPTB grafts. However, such levels of graft tension did not affect clinical outcome.

Anatomic Single-Graft Anterior Cruciate Ligament Reconstruction Restores Rotational Stability: A Robotic Study in Cadaveric Knees.

PURPOSE: First, we aimed to investigate the ability of a single bone-patellar tendon-bone graft placed in the anatomic center of the femoral and tibial attachment sites to restore normal tibiofemoral compartment translations and tibial rotation. Second, we aimed to investigate what combination of anterior load and internal rotation torque applied during a pivot-shift test produces maximal anterior tibiofemoral subluxations. METHODS: We used a 6-df robotic simulator to test 10 fresh-frozen cadaveric specimens under anterior cruciate ligament (ACL)-intact, ACL-sectioned, and ACL-reconstructed conditions measuring anterior translations of the medial, central, and lateral tibiofemoral compartments and degrees of tibial rotation. Specimens were loaded under Lachman, anterior limit, and internal rotation conditions, as well as 3 different pivot-shift conditions. RESULTS: On ACL sectioning, compartment translations in the Lachman and 3 pivot-shift tests increased significantly and were restored to ACL-intact values after single-graft ACL reconstruction. In the pivot-shift tests, the single graft restored lateral and medial compartment translations (e.g., group 3, within 1.3 ± 0.6 mm and 0.8 ± 0.6 mm, respectively, of the ACL-intact state and internal rotation within 0.7° ± 1.2°). Anterior subluxation of the medial compartment during pivot-shift loading was reduced when internal rotation torque was increased from 1 to 5 Nm (P < .0001). CONCLUSIONS: A single-graft ACL reconstruction performed at the central femoral and tibial ACL attachment sites restored anterior-posterior translation and tibial rotation motion limits. In addition, rotational knee stability as defined by tibiofemoral compartment translations was restored under all simulated pivot-shift testing conditions. CLINICAL RELEVANCE: This study provides in vitro evidence to support the clinical use of single-graft ACL reconstructions in restoring tibiofemoral compartment translations. It also shows the advantage of describing ACL insufficiency in terms of medial and lateral compartment subluxations as compared with the common approach of describing changes in central tibial translations and rotations.

MRI volume and signal intensity of ACL graft predict clinical, functional, and patient-oriented outcome measures after ACL reconstruction.

BACKGROUND: Clinical, functional, and patient-oriented outcomes are commonly used to evaluate the efficacy of treatments after anterior cruciate ligament (ACL) injury; however, these evaluation techniques do not directly measure the biomechanical changes that occur with healing. PURPOSE: To determine if the magnetic resonance (MR) image-derived parameters of graft volume and signal intensity (SI), which have been used to predict the biomechanical (ie, structural) properties of the graft in animal models, correlate with commonly used clinical (anteroposterior [AP] knee laxity), functional (1-legged hop), and patient-oriented outcome measures (Knee Injury and Osteoarthritis Outcome Score [KOOS]) in patients 3 and 5 years after ACL reconstruction. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: Based on a subset of participants enrolled in an ongoing ACL reconstruction clinical trial, AP knee laxity, 1-legged hop test, and KOOS were assessed at 3- and 5-year follow-up. Three-dimensional, T1-weighted MR images were collected at each visit. Both the volume and median SI of the healing graft were determined and used as predictors in a multiple regression linear model to predict the traditional outcome measures. RESULTS: Graft volume combined with median SI in a multiple linear regression model predicted 1-legged hop test at both the 3- and 5-year follow-up visits (R(2) = 0.40, P = .008 and R(2) = 0.62, P = .003, respectively). Similar results were found at the 5-year follow-up for the KOOS quality of life (R(2) = 0.49, P = .012), sport/function (R(2) = 0.37, P = .048), pain (R(2) = 0.46, P = .017), and symptoms (R(2) = 0.45, P = .021) subscores, although these variables were not significant at 3 years. The multiple linear regression model for AP knee laxity at 5-year follow-up approached significance (R(2) = 0.36, P = .088). CONCLUSION: The MR parameters (volume and median SI) used to predict ex vivo biomechanical properties of the graft in an animal model have the ability to predict clinical or in vivo outcome measures in patients at 3- and 5-year follow-up. CLINICAL RELEVANCE: Results from this study may enhance clinical evaluation of graft health by relating the MR parameters of volume and median SI to traditional outcome measures and could potentially aid researchers in determining the appropriate timing for athletes to return to sport.