The role of relaxin in anterior cruciate ligament injuries: a systematic review.

OBJECTIVE: Anterior cruciate ligament (ACL) tears are exceedingly common among the athletic population and are seen with higher incidence in females. Observational studies have noted peak ACL tear rates in the luteal phase of the menstrual cycle, a time in which the hormone relaxin peaks in serum concentration. METHODS: A systematic review of the literature was performed. Inclusion criteria specified all prospective and retrospective studies which included the role of relaxin in the pathogenesis of ACL tears. RESULTS: Six studies met inclusion criteria yielding 189 subjects from clinical studies and 51 in vitro samples. Included studies found that ACL samples exhibit selective relaxin binding. When pre-treated with estrogen prior to relaxin exposure, female ACL tissue samples exhibit increased expression of collagen degrading receptors. CONCLUSION: Relaxin displays binding specificity to the female ACL and increased serum concentrations are correlated with increased ACL tear rates in female athletes. Further research is needed in this area. LEVEL OF EVIDENCE: V.

The effects of timing of pediatric knee ligament surgery on short-term academic performance in school-aged athletes.

BACKGROUND: Orthopaedic injuries negatively affect the academic lives of children. HYPOTHESIS: The timing of anterior cruciate ligament (ACL) and medial patellofemoral ligament (MPFL) reconstructions affects academic performance in school-aged athletes. STUDY DESIGN: Cohort study; Level of evidence, 2. Methods Records of patients < or = 18 years old who underwent ACL or MPFL reconstructions from 2001-2007 were reviewed retrospectively. Subjects had been administered a unique questionnaire to evaluate school life in the immediate postoperative period as well as International Knee Documentation Committee (IDKC), Lysholm, and Kujala knee-specific questionnaires. Patients were in 1 of 3 study cohorts: group A (surgery during school year), group B (surgery during school holiday), and group C (surgery during summer break). RESULTS: There were 62 subjects (53 ACL and 12 MPFL reconstructions). A higher proportion of patients in group A required being driven to school (88.5%) than groups B (63.6%) or C (64.7%) (P < .05). A lower proportion of patients in group A returned to school immediately after surgery (3.8%) than groups B (36.4%) or C (88.2%) (P < .005). Among children who had never failed a test before surgery, a higher proportion of patients in group A failed a test (36.4%) after return to school than groups B (0%) or C (0%) (P < .05). Patients in group C had higher mean Likert scores (4.5) than groups A (3.8) or B (3.7) (P = .05) in response to the question "my grades suffered in my classes." Delay in surgery was negatively correlated with IKDC, Lysholm, and Kujala questionnaire scores (P < .05). CONCLUSION: In school-aged athletes with ligamentous knee injuries receiving operative treatment, surgery on a school day causes more academic difficulties than surgery during a holiday or summer break. Academic benefits of delaying surgery during the school year must be weighed against potentially worse outcomes encountered with prolonged surgical delay.