Dynamic function after anterior cruciate ligament ~ . reconstruction with autologous patellar tendon

ABSTRACT The purpose of this study was to dynamically assess the functional outcome of patients who had undergone successful anterior cruciate ligament reconstruction using an autologous patellar tendon technique and to determine whether their dynamic knee function was related to quadriceps and hamstring muscle strength. The knee kinematics and kinetics of 22 subjects who had undergone anterior cruciate ligament reconstruction (mean age, 27 Ϯ 11 years) and of 22 age-and sex-matched healthy control subjects were determined during various dynamic activities using a computerized motion analysis and force plate system. The differences in the sagittal plane angles and external moments between the two groups during light (walking), moderate (climbing and descending stairs), and higher-demand (jogging, jog and cut, jog and stop) activities were related to isokinetic strength measurements. Although patients who are asymptomatic and functioning well after anterior cruciate ligament reconstruction can perform normally in light activities, higher-demand activities reveal persistent functional adaptations that require further study. Injury to the ACL leads to knee instability and functional adaptations. Although many ACL-deficient patients display little or no visible impairment (primarily because of activity modification), previous studies have shown that patients with ACL deficiencies walk and perform more stressful activities differently than do uninjured subjects, with most of the differences occurring in the sagittal plane angles and moments. The purpose of our study was to determine whether functional adaptations during gait and other low-and high-demand activities were present in patients with an ACL bone-patellar tendon reconstruction and, if so, whether they were related to strength. More specifically, we examined how the sagittal plane joint angles and external moments during walking, stair-climbing, and jogging activities differed between healthy subjects and patients with a reconstructed ACL and whether those differences related to isokinetic quadriceps and hamstring muscle strength. MATERIALS AND METHODS Twenty-two subjects (mean age, 27 Ϯ 11 years) who underwent an autogenous patellar tendon reconstruction for ACL deficiency were tested and compared with a group of 22 uninjured control subjects. The ACL-reconstructed group consisted of 13 men and 9 women. Patients in the ACL-reconstructed group underwent surgery at an average of 8 months (range, 1 to 24) after injury and were examined at a mean follow-up of 22 Ϯ 12 months. Excluded from the study were those patients who had meniscal damage in which more than 25% of the meniscus was removed, posterior cruciate or collateral ligament injury, articular surface injury, symptomatic anterior knee pain, or objective instability at latest follow-up examination (positive pivot shift test results, positive Lachman † Address correspondence and reprint requests to Charles A. Bush-Joseph, MD, Rush-Presbyterian-St