Abstract
Developmental dysplasia of the hip (DDH) is the most common post-natal skeletal abnormality. It is widely acknowledged that conditions which cause or result in reduced movement in utero are contributing factors to the incidence of DDH. However, the hypothesis that prenatal movement plays a role in normal development of the hip joint has not been tested using embryonic model systems. This research investigates the effects of immobilization in chick embryos on hip joint morphogenesis. Embryonic chicks were treated in ovo using a neuromuscular blocking agent from embryonic days 5 to 9. Limbs were stained for cartilage using alcian blue, and were scanned in 3-D. Standardized virtual sections of the femur were taken and a number of virtual sections from age-matched limbs were overlaid in order to compare between control and immobilized limbs. The results show that not all immobilised limbs were equally affected, with some immobilised embryos having almost normal joint shapes, and other immobilised embryos displaying decreased protuberance of the femoral head and decreased indentation at the femoral neck. Our results demonstrate that the mechanobiological response to immobilisation can vary between individuals, but also that preventing movement during embryonic development can lead to abnormal morphogenesis of the developing proximal femur in some individuals, providing evidence that reduced movement during development can lead to features of DDH.
