Arthrofibrosis after anterior cruciate ligament reconstruction in children and adolescents.

INTRODUCTION: Arthrofibrosis is a known complication after anterior cruciate ligament (ACL) reconstruction. ACL reconstruction is being performed with increased frequency in the pediatric population. The purpose of this study was to determine the prevalence of arthrofibrosis in children and adolescents and to identify risk factors for arthrofibrosis. METHODS: The study design was a retrospective case series. Medical records for 1016 consecutive ACL reconstructions in patients aged 7 to 18 years old between 1995 to 2008 at a major tertiary care children's hospital were reviewed to identify cases of postoperative arthrofibrosis. Arthrofibrosis was defined as a loss of 5 degrees or more extension compared with the contralateral knee that required a follow-up procedure or a loss of 15 degrees or more flexion compared with the contralateral knee that required a follow-up procedure. Patient data were recorded and analyzed using bivariate models to identify predictors for arthrofibrosis. Further, we reviewed the clinical course of patients with treated arthrofibrosis to assess functional outcomes of this complication. RESULTS: Nine hundred two patients with 933 knees met the inclusion criteria for this study, of which 60% were female. The mean age at the time of surgery was 15 years (range, 7 to 18 y), and the average follow-up from original ACL reconstruction was 6.3 years (range, 1.6 to 14.2 y). The overall prevalence of arthrofibrosis in our cohort was 8.3%, with 77 of the 933 knees had at least 1 procedure to treat arthrofibrosis after ACL reconstruction. Risk factors for arthrofibrosis were female sex (11.1% females, P = 0.0001), patients aged 16 to 18 years [11.6%; odds ratio (OR) 3.51; P = 0 .007], patellar tendon autograft (OR, 1.7; P = 0.026), and concomitant meniscal repair (OR, 2.08; P = 0.007). Prior knee surgery and ACL reconstruction within 1 month of injury were not significantly associated with arthrofibrosis after ACL reconstruction. Fifty-three patients had a minimum of 6 months clinical follow-up after the procedure for arthrofibrosis. Of these, 46 patients (86.8%) had full range of motion at follow-up. Thirty-two patients (60.4%) were asymptomatic at final follow-up. Eleven patients (20.8%) complained of some persistent pain. CONCLUSIONS: The rate of arthrofibrosis after ACL reconstruction in children and adolescents is 8.3%. Risk factors for arthrofibrosis are female sex, older adolescents, concurrent meniscal repair, and reconstruction with patellar tendon autograft. Surgical treatment for arthrofibrosis after ACL reconstruction in pediatric patients can satisfactorily regain motion in the reconstructed knee; however functional outcome may be compromised. LEVEL OF EVIDENCE: Level 4.

Effects of flexor-pronator muscle loading on valgus stability of the elbow with an intact, stretched, and resected medial ulnar collateral ligament.

BACKGROUND: The medial ulnar collateral ligament (MUCL) is an important passive stabilizer to the valgus stresses that athletes experience during overhead throwing motion. However, the role of the flexor-pronator muscles as active stabilizers to valgus stress is not well defined in the literature. The objectives of this study were to quantify the relative contribution of the individual flexor-pronator muscles to valgus stability of the elbow and how this relationship was affected by ligament status. METHODS: A custom elbow testing system and Microscribe 3DLX were used for biomechanical testing. Flexor-pronator muscles were loaded to simulate contraction, and the valgus angle of the elbow was measured in eight cadaveric specimens at 30 degrees , 60 degrees , and 90 degrees of elbow flexion with 3 different valgus torques applied to the forearm. Loads based on muscle cross-sectional area were applied to the flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), and pronator teres (PT). The effect of each muscle was evaluated by unloading the individual muscle while the other 2 remained loaded, resulting in 5 loading conditions: no muscles loaded, all muscles loaded, unloaded FCU, unloaded FDS, and unloaded PT. Valgus angle was measured for 3 MUCL ligament conditions: intact, stretched, and cut. RESULTS: The effect of muscle loading on valgus angle was similar for each ligament condition. Loading the flexor-pronator muscles significantly decreased valgus angle of the elbow in all testing conditions (P < .01). Unloading the FDS significantly increased valgus angle compared to all muscles loaded in all testing conditions (P < .016). Unloading the FCU and PT significantly increased valgus angle in less than half of the testing conditions. CONCLUSION: The FDS, PT, and FCU are all active stabilizers of the elbow to valgus stress. The FDS is the biggest contributor amongst the flexor-pronator muscles.