Knee Hyperextension Greater Than 5° Is a Risk Factor for Failure in ACL Reconstruction Using Hamstring Graft
Tales Mollica Guimarães, Pedro Nogueira Giglio, Marcel Faraco Sobrado, Marcelo Batista Bonadio, Riccardo Gomes Gobbi, José Ricardo Pécora, Camilo Partezani Helito
Abstract
Background: The degree of knee hyperextension in isolation has not been studied in detail as a risk factor that could lead to increased looseness or graft failure after anterior cruciate ligament (ACL) reconstruction. Purpose: To analyze whether more than 5° of passive knee hyperextension is associated with worse functional outcomes and greater risk of graft failure after primary ACL reconstruction with hamstring tendon autograft. Study Design: Cohort study; Level of evidence, 3. Methods: A cohort of patients who had primary ACL reconstruction with hamstring tendon autografts was divided into 2 groups based on passive contralateral knee hyperextension greater than 5° (hyperextension group) and less than 5° (control group) of hyperextension. Groups were matched by age, sex, and associated meniscal tears. The following data were collected and compared between the groups: patient data (age and sex), time from injury to surgery, passive knee hyperextension, KT-1000 arthrometer laxity, pivot shift, associated meniscal injury and treatment (meniscectomy or repair), contralateral knee ligament injury, intra-articular graft size, follow-up time, occurrence of graft failure, and postoperative Lysholm knee scale and International Knee Documentation Committee subjective form scores. Results: Data from 358 patients initially included in the study were analyzed; 22 were excluded because the time from injury to surgery was greater than 24 months, and 22 were lost to follow-up. From the cohort of 314 patients, 102 had more than 5° of knee hyperextension. A control group of the same size (n = 102) was selected by matching among the other 212 patients. Significant differences in the incidence of graft failure (14.7% vs 2.9%; P = .005) and Lysholm knee scale score (86.4 ± 9.8 vs 89.6 ± 6.1; P = .018) were found between the 2 groups. Conclusion: Patients with more than 5° of contralateral knee hyperextension submitted to single-bundle ACL reconstruction with hamstring tendons have a higher failure rate than patients with less than 5° of knee hyperextension.