Variations in Varus/Valgus and Internal/External Rotational Knee Laxity and Stiffness Across the Menstrual Cycle

Abstract: Cyclic variations in genu recurvatum (GR), general joint laxity (GJL), varus-valgus (VV), and internal-external (IER) rotational laxities and stiffnesses were examined in 64 females and 43 males at two time points during the females' menstrual cycle [days of minimum (T1) and maximum (T2) anterior knee laxity (AKL)]. Cyclic increases in AKL (9.5%), GR (37.5%), and GJL (13.6%) were observed in females but not males from T1 to T2 (p < 0.001). Cyclic increases in VV and IER laxity were negligible (1.5-3.2%, p > 0.320). Females compared to males had lower overall VV stiffness at T2 (F 37% <M) vs. T1 (F 26.9% <M; p = 0.011), but no difference across time points for IER stiffness (p = 0.452). Across both time points, females had consistently greater VV (30.2%) and IER (20%) laxity and less VV (32.5%) and IER (24.3%) incremental stiffness (p < 0.001). Low-to-moderate associations were observed between AKL, GR, and GJL with VV and IER laxities and stiffnesses in females as measured at T1 and the change in values from T1 to T2. Whether these findings reflect ligament-specific responses to hormone changes, or implicate changes in injury risk potential across the menstrual cycle requires further study. Article: The potential consequences of varus-valgus (VV) and internal-external (IER) rotational laxity and stiffness of the tibiofemoral joint on knee joint biomechanics have recently been examined. Where rotational laxity is a measure of the rotation of the tibia relative to the femur between fixed torque magnitudes, torsional stiffness represents the torque-rotation response of the joint across a range of applied torques, which may be useful in determining where in the range the knee joint is more or less resistive to the applied torques

Accuracy and Reliability of Examiners’ Observations of Pre-Practice Warm-Up and FIFA 11+ Injury Prevention Program Exercises

Background: The Fédération Internationale de Football Association (FIFA) 11+ is an injury prevention program that decreases the incidence of lower extremity injuries. The purpose of the current study was to understand what specific exercises prevented injury from occurring. We thus developed and tested a form to identify these exercises. We hypothesize that trained examiners could accurately and reliably use this form to identify and record individual exercises performed during preparticipation warm-up. Methods: A repeated-measures study design was used in this investigation. After observing five prepractice warm-up videos obtained from multiple high schools, 11 examiners observed and recorded performed exercises at two different times. The videos included four soccer teams and one American football team. Accuracy, interexaminer reliability, and intraexaminer reliability were assessed. Sensitivity, specificity, accuracy, and percent agreement with a FIFA 11+ expert were measured for each exercise component. Results: The intraclass correlation coefficients between examiners and individually ranged from 0.22 to 1.00 and 0.58 to 1.00, respectively. Reliability was lowest for exercises with similar movements. The percent agreement across all examiners for individual exercises ranged from 20% to 100%. Additionally, the percent agreement between each examiner and the “gold standard” examiner was high (range, 69.6% to 90.4%). For exercises with similar movements, accuracy and reliability were considerably improved (97%) when combined into one category. Conclusion: We determined that trained examiners with different backgrounds and experience can make accurate and reliable observations of most exercises observed in warm-up programs. Using the proposed form, researchers can accurately record exercises and perform quality and fidelity assessments of warm-up exercise routines

Letter to the Editor - IKDC or KOOS? Which measures symptoms and disabilities most important to postoperative articular cartilage repair patients? Author's Response

Dear Editor: We have with interest read the article by Hambly and Griva titled “IKDC or KOOS? Which Measures Symptoms and Disabilities Most Important to Postoperative Articular Cartilage Repair Patients?” (September 2008, pages 1695-704) and the accompanying editorial by Bruce Reider. As pointed out in the article, there is no agreement regarding a gold-standard patient-assessed measure of the effect of cartilage repair surgery, and it is important to compare possible questionnaires. It would indeed improve interpretation of outcome in cartilage repair in particular, and in knee surgery in general, if consensus could be reached on a preferred patient-reported outcomes measure

Stabilizing effects of ankle bracing under a combination of inversion and axial compression loading

The combined effects of bracing, axial compression and inversion rotation on the ankle-subtalar complexes were evaluated. Ex vivo tests under the load-controlled condition were performed on six cadaver ankle specimens using a six degree-of-freedom fixture. Inversion rotation was measured while subjecting the ankle-subtalar complex to a 2.5 N-m inversion moment and a combination of the testing variables (brace type, no brace, 178 N axial compression load, no compression load, 0° and 20° of plantar flexion) for a total of 16 tests per specimen. Three commercially available braces (two semirigid types and one lace up type) were evaluated. An axial compression load significantly decreased ankle-subtalar motion in unbraced ankles for the tested inversion moment. The contribution of bracing to stabilization of the ankle was smaller in the axial loading condition than in the no axial loading condition. The semirigid braces had greater stabilizing effects in response to the inversion moment than the lace up brace. Stabilizing effects of bracing were significantly greater in 20° of plantar flexion than in 0° of plantar flexion. The most common mechanism for an ankle sprain injury is inversion rotation on a weight-bearing ankle. Therefore, we should not overestimate stabilizing effects of bracing from evaluations of bracing without axial compression loading