Treatment options for canine hip dysplasia

Hip dysplasia is a common orthopaedic condition seen in dogs and is characterised by joint laxity and incongruency between the femoral head and the acetabulum (Smith et al, 2017). This results in inflammation, microfractures, secondary osteoarthritis and clinical signs of pain and lameness. Efforts to reduce the prevalence of this condition through breeding schemes have been implemented; however, because of the multifactorial nature of hip dysplasia, with a combination of environmental factors and a complex mode of inheritance, the prevalence within the canine population remains high (Smith et al, 2017). Therefore, knowledge of management options for this condition is important for the general practitioner.

A diagnosis of hip dysplasia can be made from a set of standard orthogonal hip radiographs (Figure 1). However, it is important to correlate imaging findings with the clinical signs demonstrated by the patient when determining the need for, and most appropriate course of, treatment. The prevalence of hip dysplasia is high and will often be diagnosed alongside other orthopaedic conditions that may be more relevant clinically, such as cranial cruciate ligament rupture (Powers et al, 2005). Although radiography is not 100% accurate for diagnosing hip dysplasia and false negatives can occur, this is less likely to occur in clinical cases. Stressed radiographic views can be used to further assess hip laxity, such as the PennHip method to obtain a distraction index (Smith et al, 1990). The distraction index remains constant from 16 weeks of age and appears to be a reliable indicator of the risk of developing hip dysplasia later in life (Smith, 1997; Smith et al, 1998). A lower distraction index correlates with reduced hip laxity, and values <0.3 have been associated with a reduced risk of developing hip dysplasia (Smith, 1997; Smith et al, 1998). Radiation safety rules in the UK do not allow for human restraint while performing radiography as part of a screening process but can be used where the clinical situation justifies it. As such, these views are not commonly performed in the UK (Ginja et al, 2010).