Webster, Kate E.

Background: After anterior cruciate ligament (ACL) reconstruction (ACLR), changes in the appearance of the ACL graft can be monitored using magnetic resonance imaging (MRI). Purpose: The purpose of this study was to evaluate and compare the MRI signal intensity (SI) of hamstring and quadriceps tendon grafts during the first postoperative year after ACLR. As a secondary aim, the relationship of SI to clinical and anatomic measurements was analyzed. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 78 patients who underwent ACLR with an autologous graft were reviewed; 55 received hamstring grafts and 23 received quadriceps tendon grafts. At 3 and 9 months postoperatively, 3-T MRI was performed using a dedicated knee coil, and the median SI of the intra-articular ACL graft was measured on sagittal-plane images. Postoperative lateral radiographs were analyzed to determine medial and lateral posterior tibial slope (PTS). Side-to-side difference in anterior knee laxity between injured and uninjured limbs was measured at 6 and 12 months postoperatively. Results: The median SI of quadriceps grafts was significantly greater than hamstring grafts at 3 months after ACLR ( P = .02). Between 3 and 9 months, the median SI of quadriceps grafts decreased ( P < .001), while that of hamstring grafts did not significantly change ( P = .55). The lateral PTS was significantly correlated with median SI measurements at 3 and 9 months such that greater lateral PTS values were associated with greater median SI. The side-to-side difference in anterior knee laxity decreased for the quadriceps group ( P = .04) between 6 and 12 months but did not change for the hamstring group ( P = .88). Conclusion: The median SI of quadriceps grafts significantly decreased on MRI between 3 and 9 months after ACLR, while the median SI of hamstring grafts did not significantly change. The change in MRI appearance of the quadriceps grafts was paralleled by a reduction in anterior knee laxity between 6 and 12 months after surgery. In the absence of standardized imaging techniques and imaging analysis methods, the role of MRI in determining graft maturation, and the implications for progression through rehabilitation to return to sport, remain uncertain.

Purpose The purpose of this meta‐analysis was to determine overall objective graft failure rate, failure rate by graft type (allograft vs autograft reconstruction), instrumented laxity, and patient outcome scores following revision anterior cruciate ligament (ACL) reconstruction. Outcomes of interest were collected for all studies meeting the study inclusion criteria, but lower‐level studies (level III/IV) were not pooled for quantitative synthesis due to high levels of heterogeneity in these study populations. Methods A comprehensive search strategy was performed to identify studies reporting outcomes of revision ACL reconstruction. The primary outcome reported was graft failure. A meta‐analysis comparing rate of failure by graft type was conducted using a random effects model. Studies also reported patient clinical outcome scores, including International Knee Documentation Committee (IKDC), Lysholm, and knee injury and osteoarthritis outcome scores (KOOS) and graft laxity. Results Eight studies with 3,021 patients (56% male, 44% female) with an average age of 30 ± 4 years and mean follow‐up time of 57 months were included. The overall objective failure rate was 6% (95% confidence interval [CI], 1.8%‐12.3%). Mean instrumented laxity as side‐to‐side difference was 2.5 mm (95% CI, 1.9‐3.1 mm). Mean IKDC subjective score was 76.99 (95% CI, 76.64‐77.34), mean KOOS symptoms score was 76.73 (95% CI, 75.85‐77.61), and mean Lysholm score was 86.18 (95% CI, 79.08‐93.28). The proportion of patients with IKDC grade A or B was 85% (95% CI, 77%‐91%). When the available data for failure rate were analyzed by graft type, autograft reconstruction had a failure rate of 4.1% (95% CI, 2.0%‐6.9%), similar to allograft reconstruction at 3.6% (95% CI, 1.4%‐6.7%). Conclusions In this meta‐analysis, revision ACL reconstruction had failure rates similar to autograft or allograft reconstruction. Overall outcome scores for revision reconstruction have improved but appear modest when compared with primary ACL reconstruction surgery. Level of Evidence Meta‐analysis of Level II studies, Level II.