Developmental dysplasia of the hip: A computational biomechanical model of the path of least energy for closed reduction

Abstract

This study utilized a computational biomechanical model and applied the least energy path principle to investigate two pathways for closed reduction of high grade infantile hip dislocation. The principle of least energy when applied to moving the femoral head from an initial to a final position considers all possible paths that connect them and identifies the path of least resistance. Clinical reports of severe hip dysplasia have concluded that reduction of the femoral head into the acetabulum may occur by a direct pathway over the posterior rim of the acetabulum when using the Pavlik harness, or by an indirect pathway with reduction through the acetabular notch when using the modified Hoffman–Daimler method. This computational study also compared the energy requirements for both pathways. The anatomical and muscular aspects of the model were derived using a combination of MRI and OpenSim data. Results of this study indicate that the path of least energy closely approximates the indirect pathway of the modified Hoffman–Daimler method. The direct pathway over the posterior rim of the acetabulum required more energy for reduction. This biomechanical analysis confirms the clinical observations of the two pathways for closed reduction of severe hip dysplasia. The path of least energy closely approximated the modified Hoffman–Daimler method. Further study of the modified Hoffman–Daimler method for reduction of severe hip dysplasia may be warranted based on this computational biomechanical analysis. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1799–1805, 2017.

Biomechanical evaluation of femoral anteversion in developmental dysplasia of the hip and potential implications for closed reduction

“…These muscles are relaxed and may not prevent reduction when the dislocated hip is flexed with the hip abducted in the Pavlik harness. A previous study analyzed the contributions of these muscles and confirmed negligible effects relative to the muscles included in the model (Ardila et al, 2013;Zwawi et al, 2016). For this study, musculoskeletal tissue was modeled using a straight-line muscle path representation since lines of action do not intersect in the range of motion of interest and it allowed usage of classic methods of vector analysis (Dostal and Andrews, 1981).…”

“…A patient-derived Rigid Body Dynamics computational model of the lower extremity of a ten-week old female infant previously developed Zwawi et al, 2016) was modified to include a range of FA angles. The infant age was selected because it represents an age where the lower limb is sensitive to deformation due to a severe dislocation.…”

“…The anatomical model was composed of the hip, femur, tibia, fibula, and foot. The behavior of muscles that were identified clinically as mediating muscles during reduction with the PH is implemented in the complete lower extremity assembly (Ardila et al, 2013;Suzuki, 1994;Zwawi et al, 2016). As previously determined these muscles are: (1) Pectineus, (2) Adductor Brevis, (3) Adductor Longus, (4) Adductor Magnus, and (5) Gracilis as seen in Fig.…”

“…Suzuki noted that the femoral head is located posterior to the acetabulum in the Pavlik harness in higher grades of dislocation and reduction may be prevented by the posterior wall of the acetabulum (Suzuki, 1994). To address such cases, recent computational studies utilizing patient-derived anatomy have shown that failure of the PH for a severe dislocation can be successfully quantified and have corroborated the impediment to reduction presented by the posterior wall of the acetabulum (Ardila et al, 2013;Zwawi et al, 2016). Although these studies have provided a state-of-the-art procedure to investigate the biomechanics of subtle and severe dislocations, relevant femoral pathoanatomy was idealized.…”

Stress-specific differences in Distal Femoral Epiphysis of Leg Length Discrepancy and Pelvic Tilt. A Finite-Element Analysis

“…And limit the displacement of the distal femur in three dimensions. To avoid the effect of asymmetric bones on the results, we did not model muscles and ligaments, Considering that we are simulating the conditions of static standing, a previous study analyzed the contributions of these muscles and con rmed negligible effects relative to the muscles included in the model (Ardila et al 2013;Zwawi et al 2017). The rest of the model C and D are obtained by similar methods.…”