The potential role of variations in juvenile hip geometry on the development of Legg-Calvé-Perthes disease: a biomechanical investigation

Abstract

Legg-Calvé-Perthes disease (LCP) is one of the most poorly understood diseases in paediatric orthopaedics. One common trait of LCP is the marked morphological difference between healthy and pathological hips, early deviations of which (i.e. prior to disease onset) have been suggested to lead to the overload and collapse of the epiphysis. Here, the impact of common variations in geometry is investigated with a finite element model of a juvenile femur under single leg standing and landing. Here, the impact of typical variations in geometry is investigated with a finite element model of a juvenile femur under single leg standing and landing. The variations appear to have only a limited effect on the stress distribution in the femoral epiphysis even during high impact activities. This suggests that, for this individual at least, they would be unlikely to cause epiphyseal overload and collapse, even in the presence of a skeletally immature epiphysis.

New insights into the biomechanics of Legg-Calvé-Perthes’ disease

“… 24 Muscle forces were obtained by considering the 24 muscles acting around the hip, using non-linear optimization. 16 The model was optimized for single-leg stance and predicted a hip joint reaction forces (HJR) of 3.36 BW, which compares well with previously reported values for juvenile subjects. 25 …”

“… 34 These observations support the results of our previous work. 16 Even with such significantly reduced bone stiffness, only 7.3% of the epiphysis was overloaded.…”

“… A full musculoskeletal model of the hip of a healthy 7.9-year-old male subject showing the muscle lines of action, with symmetry plane along the sagittal plane, described in a previous study by authors of this paper, 16 simulated in single-leg stance considering a healthy epiphysis and a small ossified epiphysis and different levels of bone and cartilage maturity. b) High-resolution computational model of the hip joint containing the three main superior retinacular vessels that constitute the main blood supply to the developing epiphysis.…”

“…We have previously proposed five mechanisms for the pathology of Perthes’ disease, 15 and the implications for the morphology of the juvenile hip and the biomechanics of the hip joint. 16 From these we suggested that fracture and collapse of the femoral head, even in an immature epiphysis, is unlikely. We now hypothesize that morphological changes of the femoral head, together with an alteration in the mechanical properties of the epiphyseal cartilage, may cause compression or occlusion of the retinacular vessels.…”

Physiologic and Pathologic Development of the Infantile and Adolescent Hip Joint: Descriptive and Functional Aspects

“…In 1892, Julius Wolff 21 was the first to state the idea that the shapes of bone and joints in some way reflect their mechanical loading during life. With regard to the hip, since this time some historical 22,23 and many actual mechanobiological [24][25][26][27][28][29][30][31][32][33] and paleontological 34,35 studies have dealt with the so-called Wolff's law. The mechanobiological concept that function influences external shape and internal architecture of bones and joints in the meantime has been supported by much experimental and observational data.…”