Browsing by Subject "biomechanics"
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Item Open Access Association of Jump-Landing Biomechanics With Tibiofemoral Articular Cartilage Composition 12 Months After ACL Reconstruction.(Orthopaedic journal of sports medicine, 2021-07) Pfeiffer, Steven J; Spang, Jeffrey T; Nissman, Daniel; Lalush, David; Wallace, Kyle; Harkey, Matthew S; Pietrosimone, Laura S; Padua, Darin; Blackburn, Troy; Pietrosimone, BrianBackground
Excessively high joint loading during dynamic movements may negatively influence articular cartilage health and contribute to the development of posttraumatic osteoarthritis after anterior cruciate ligament reconstruction (ACLR). Little is known regarding the link between aberrant jump-landing biomechanics and articular cartilage health after ACLR.Purpose/hypothesis
The purpose of this study was to determine the associations between jump-landing biomechanics and tibiofemoral articular cartilage composition measured using T1ρ magnetic resonance imaging (MRI) relaxation times 12 months postoperatively. We hypothesized that individuals who demonstrate alterations in jump-landing biomechanics, commonly observed after ACLR, would have longer T1ρ MRI relaxation times (longer T1ρ relaxation times associated with less proteoglycan density).Study design
Cross-sectional study; Level of evidence, 3.Methods
A total of 27 individuals with unilateral ACLR participated in this cross-sectional study. Jump-landing biomechanics (peak vertical ground-reaction force [vGRF], peak internal knee extension moment [KEM], peak internal knee adduction moment [KAM]) and T1ρ MRI were collected 12 months postoperatively. Mean T1ρ relaxation times for the entire weightbearing medial femoral condyle, lateral femoral condyle (global LFC), medial tibial condyle, and lateral tibial condyle (global LTC) were calculated bilaterally. Global regions of interest were further subsectioned into posterior, central, and anterior regions of interest. All T1ρ relaxation times in the ACLR limb were normalized to the uninjured contralateral limb. Linear regressions were used to determine associations between T1ρ relaxation times and biomechanics after accounting for meniscal/chondral injury.Results
Lower ACLR limb KEM was associated with longer T1ρ relaxation times for the global LTC (ΔR 2 = 0.24; P = .02), posterior LTC (ΔR 2 = 0.21; P = .03), and anterior LTC (ΔR 2 = 0.18; P = .04). Greater ACLR limb peak vGRF was associated with longer T1ρ relaxation times for the global LFC (ΔR 2 = 0.20; P = .02) and central LFC (ΔR 2 = 0.15; P = .05). Peak KAM was not associated with T1ρ outcomes.Conclusion
At 12 months postoperatively, lower peak KEM and greater peak vGRF during jump landing were related to longer T1ρ relaxation times, suggesting worse articular cartilage composition.Item Open Access Changes in landing mechanics in patients following anterior cruciate ligament reconstruction when wearing an extension constraint knee brace.(Sports Health, 2014-05) Butler, Robert J; Dai, Boyi; Garrett, William E; Queen, Robin MBACKGROUND: Anterior cruciate ligament (ACL) reconstruction is associated with a high incidence of second tears (graft tears and contralateral ACL tears). These secondary tears have been attributed to asymmetrical lower extremity mechanics. Knee bracing is one potential intervention that can be used during rehabilitation that has the potential to normalize lower extremity asymmetry; however, little is known about the effect of bracing on movement asymmetry in patients following ACL reconstruction. HYPOTHESIS: Wearing a knee brace would increase knee joint flexion and joint symmetry. It was also expected that the joint mechanics would become more symmetrical in the braced condition. OBJECTIVE: To examine how knee bracing affects knee joint function and symmetry over the course of rehabilitation in patients 6 months following ACL reconstruction. STUDY DESIGN: Controlled laboratory study. LEVEL OF EVIDENCE: Level 3. METHODS: Twenty-three adolescent patients rehabilitating from ACL reconstruction surgery were recruited for the study. The subjects all underwent a motion analysis assessment during a stop-jump activity with and without a functional knee brace on the surgical side that resisted extension for 6 months following the ACL reconstruction surgery. Statistical analysis utilized a 2 × 2 (limb × brace) analysis of variance with a significant alpha level of 0.05. RESULTS: Subjects had increased knee flexion on the surgical side when they were braced. The brace condition increased knee flexion velocity, decreased the initial knee flexion angle, and increased the ground reaction force and knee extension moment on both limbs. Side-to-side asymmetry was present across conditions for the vertical ground reaction force and knee extension moment. CONCLUSION: Wearing a knee brace appears to increase lower extremity compliance and promotes normalized loading on the surgical side. CLINICAL RELEVANCE: Knee extension constraint bracing in postoperative ACL patients may improve symmetry of lower extremity mechanics, which is potentially beneficial in progressing rehabilitation and reducing the incidence of second ACL tears.Item Open Access In Vivo Assessment of Exercise-Induced Glenohumeral Cartilage Strain.(Orthopaedic journal of sports medicine, 2018-07-13) Zhang, Hanci; Heckelman, Lauren N; Spritzer, Charles E; Owusu-Akyaw, Kwadwo A; Martin, John T; Taylor, Dean C; Moorman, CT; Garrigues, Grant E; DeFrate, Louis EThe human shoulder joint is the most mobile joint in the body. While in vivo shoulder kinematics under minimally loaded conditions have been studied, it is unclear how glenohumeral cartilage responds to high-demand loaded exercise.A high-demand upper extremity exercise, push-ups, will induce compressive strain in the glenohumeral articular cartilage, which can be measured with validated magnetic resonance imaging (MRI)-based techniques.Descriptive laboratory study.High-resolution MRI was used to measure in vivo glenohumeral cartilage thickness before and after exercise among 8 study participants with no history of upper extremity injury or disease. Manual MRI segmentation and 3-dimensional modeling techniques were used to generate pre- and postexercise thickness maps of the humeral head and glenoid cartilage. Strain was calculated as the difference between pre- and postexercise cartilage thickness, normalized to the pre-exercise cartilage thickness.Significant compressive cartilage strains of 17% ± 6% and 15% ± 7% (mean ± 95% CI) were detected in the humeral head and glenoid cartilage, respectively. The anterior region of the glenoid cartilage experienced a significantly higher mean strain (19% ± 6%) than the posterior region of the glenoid cartilage (12% ± 8%). No significant regional differences in postexercise humeral head cartilage strain were observed.Push-ups induce compressive strain on the glenohumeral joint articular cartilage, particularly at the anterior glenoid. This MRI-based methodology can be applied to further the understanding of chondral changes in the shoulder under high-demand loading conditions.These results improve the understanding of healthy glenohumeral cartilage mechanics in response to loaded upper extremity exercise. In the future, these methods can be applied to identify which activities induce high glenohumeral cartilage strains and deviations from normal shoulder function.Item Open Access The Functional Significance of Early Homo Pelvis Morphology(2024) Cook, Rebecca WThe transition from the Pliocene to the Pleistocene appears to be a time of major transition in the hominin lineage with likely adaptive shifts in behavior. Homo erectus is a temporally broad species with apparent behavioral plasticity and potentially related morphological variability. Some H. erectus postcranial material exhibits traits that indicate a general trend of mechanical reinforcement at loadbearing sites across the pelvis and femur. One such fossil, KNM-ER 3228, is a presumed H. erectus os coxae that is representative of this morphological pattern of robusticity, which includes pronounced acetabulosacral and acetabulocristal buttresses and rugose musculoligamentous attachment sites. This femoropelvic complex represents an evolutionarily stable morphological pattern across a significant portion of the Pleistocene, but its biomechanical significance is not well understood. Moderate increases in encephalization combined with an increase in body size seen in H. erectus may be implicated in early Homo pelvic evolution, as the mechanical consequences of a larger body and expansion of the birth canal for parturition may have led to increased loads during locomotion. The retention of ancestral traits in the H. erectus pelvis (such as laterally flared ilia), coupled with derived traits (such as the expanded birth canal), may have necessitated greater robusticity in the pelvis to reduce strain magnitudes in the bone. Alternatively, this robusticity may be serving to reduce strains within the context of behavioral adaptations, such as endurance running or long-distance walking, that may have increased the magnitude or frequency of loads relative to australopiths. This dissertation addresses two objectives relative to the biomechanical significance of the femoropelvic complex of H. erectus. Objective 1 is to investigate the degree to which the patterns we see in some H. erectus pelves are due to body size scaling of bony features resulting from an evolutionary increase in body size. Objective 2 is to determine what, if any, functional significance may be assigned to the femoropelvic complex, beyond that which body size scaling to keep strain magnitudes within physiological limits may explain. A gait analysis study is conducted in which kinematic and kinetic data from modern humans are collected and used as input for a series of finite element models. These models are created from a sample of modern humans, an Australopithecus africanus pelvis (Sts 14), and a novel reconstruction of KNM-ER 3228 (early Homo) created using 3D geometric morphometrics. The results of these finite element models lead to the rejection of the hypothesis that higher magnitude loads in the H. erectus pelvis resulting from increased body size and modest encephalization resulted in the increased robusticity of pelvic features. This mechanical robusticity was hypothesized to maintain strain levels within manageable physiological levels in the context of the retention of ancestral states. Instead, the lower strains incurred during normal bipedal walking in the H. erectus pelvis suggest a pelvis adapted to bipedal walking, beyond that which strain maintenance can explain. Further, the results of finite element analyses of KNM-ER 3228 and modern humans while running provide evidence to support a hypothesis that mechanical buttressing of the H. erectus pelvis is an adaptation to an increased number of loading cycles (relative to australopiths) in the context of long-distance walking and/or endurance running, and/or high magnitude loads in the context of endurance running. This dissertation contributes to the investigation of unanswered questions in Homo pelvic evolution and highlights the value of comparative modeling in paleoanthropology.
Item Open Access Using ground reaction force to predict knee kinetic asymmetry following anterior cruciate ligament reconstruction.(Scand J Med Sci Sports, 2014-12) Dai, B; Butler, RJ; Garrett, WE; Queen, RMAsymmetries in sagittal plane knee kinetics have been identified as a risk factor for anterior cruciate ligament (ACL) re-injury. Clinical tools are needed to identify the asymmetries. This study examined the relationships between knee kinetic asymmetries and ground reaction force (GRF) asymmetries during athletic tasks in adolescent patients following ACL reconstruction (ACL-R). Kinematic and GRF data were collected during a stop-jump task and a side-cutting task for 23 patients. Asymmetry indices between the surgical and non-surgical limbs were calculated for GRF and knee kinetic variables. For the stop-jump task, knee kinetics asymmetry indices were correlated with all GRF asymmetry indices (P < 0.05), except for loading rate. Vertical GRF impulse asymmetry index predicted peak knee moment, average knee moment, and knee work (R(2) ≥ 0.78, P < 0.01) asymmetry indices. For the side-cutting tasks, knee kinetic asymmetry indices were correlated with the peak propulsion vertical GRF and vertical GRF impulse asymmetry indices (P < 0.05). Vertical GRF impulse asymmetry index predicted peak knee moment, average knee moment, and knee work (R(2) ≥ 0.55, P < 0.01) asymmetry indices. The vertical GRF asymmetries may be a viable surrogate for knee kinetic asymmetries and therefore may assist in optimizing rehabilitation outcomes and minimizing re-injury rates.