Quantifying the tolerance of chick hip joint development to temporary paralysis and the potential for recovery

Background Abnormal fetal movements are implicated in joint pathologies such as arthrogryposis and developmental dysplasia of the hip (DDH). Experimentally induced paralysis disrupts joint cavitation and morphogenesis leading to postnatal abnormalities. However, the developmental window(s) most sensitive to immobility-and therefore the best time for intervention-have never been identified. Here, we systematically vary the timing and duration of paralysis during early chick hip joint development. We then test whether external manipulation of immobilized limbs can mitigate the effects of immobility. Results Timing of paralysis affected the level of disruption to joints, with paralysis periods between embryonic days 4 and 7 most detrimental. Longer paralysis periods produced greater disruption in terms of failed cavitation and abnormal femoral and acetabular geometry. External manipulation of an immobilized limb led to more normal morphogenesis and cavitation compared to un-manipulated limbs. Conclusions Temporary paralysis is detrimental to joint development, particularly during days 4 to 7. Developmental processes in the very early stages of joint development may be critical to DDH, arthrogryposis, and other joint pathologies. The developing limb has the potential to recover from periods of immobility, and external manipulation provides an innovative avenue for prevention and treatment of developmental joint pathologies.