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Hip Dysplasia Overview
Hip Image
Normal Pelvis
Dysplastic Pelvis
Severe Dysplasia Oa

Information on the condition and its management options.

The hips (pelvis)

The pelvis consists of two symmetrical sides; each has a ‘ball and socket joint’ where the hind limb articulates with the pelvis.

The femoral head (‘ball’) is the top of the thigh bone (femur), and fits into the acetabulum (‘socket’) of the pelvis.

In a normal joint, the femoral head sits tightly inside the acetabulum and when our pets walk, weight bearing forces are spread evenly throughout the femoral head and acetabulum. The femoral head remains inside the socket and is held in place by the surrounding supportive soft tissues.

Hip Dysplasia

Hip dysplasia is one of the most common orthopaedic conditions in dogs but can also be seen (less commonly) in cats.

It is a developmental condition meaning that the shape of the pelvis is normal at birth but becomes progressively abnormal as the animal grows. Hip dysplasia affects the shape of the ball and socket joint in the pelvis. The term ‘dysplasia’ just means an ‘abnormal development’. Hip loosening (laxity) develops early in life and the stabilising soft tissues around the joint loosen. The femoral head fails to fit tightly into the acetabulum (it is less congruent). As a result, when our pets move the weight is not distributed as evenly across the joint, and the forces concentrate on the outer rim of the acetabulum. This causes the acetabulum to ‘erode’ and become shallower, which in turn leads to the femoral head becoming misshapened and flattened (secondary changes). Joint laxity can lead to a partial dislocation (subluxation) of the ball and socket joint. Instability and the secondary changes cause degeneration of the joint as it develops, resulting in inflammation and finally osteoarthritis as bone and cartilage rub against each other instead of sliding smoothly.

This condition has genetic and environmental factors and susceptibility to the development of hip dysplasia is as a result of an inherited predisposition. Hip dysplasia generally affects large rapidly growing dogs with symptoms becoming apparent at 3-12 months of age. Studies have shown that degeneration in these dogs can be accelerated by other factors such as bodyweight, rate of growth and trauma during development.

Obesity can contribute hugely to the magnitude of symptoms as any additional weight increases the pressure applied to an already painful joint.

Symptoms

Dogs suffering with hip dysplasia present in two ways.

Most commonly, puppies present at 3-12 months of age and symptoms shown may include a reluctance to play, change in hind limb movements (two-legged ‘bunny hopping’ is commonly seen) or lameness, pain and stiffness after rest and early exhaustion. Symptoms do depend on the degree of joint laxity, inflammation and duration of the disease. Immature animals usually experience pain as a result of the instability of the joint and repetitive strain placed on the soft tissues surrounding the pelvis. In contrast, Adult pets develop secondary osteoarthritis and this is the main cause of their pain.

Diagnosis

A diagnosis of hip dysplasia can be achieved through an examination by your vet. Palpation or manipulation of the joint can reveal instability, pain and in some cases, subluxation.

Radiographs (x-rays) are often advised to confirm the diagnosis and to provide more information on the degree of laxity present and signs of osteoarthritis.

Treatment

The majority of pets suffering with hip dysplasia can be managed successfully by non-surgical means such as exercise control, physiotherapy or hydrotherapy, diet modifications and anti-inflammatory drugs. Long-term medication is not recommended however and if the patient requires this for a pain free life then surgery should be considered to correct the problem. These options are described in detail in our information sheet on management of osteoarthritis.

If conservative management is not successful surgical options include:

  • Total Hip Replacement (THR)
  • Femoral Head and Neck Ostectomy (FHNO)

Outlook

This can be variable depending on the treatment option. Please view our information sheets on the different surgical techniques for more detailed information regarding expectations on recovery.

KEY POINTS

· Developmental condition with an inherited factor.

· ‘Dysplasia’ means ‘abnormal development’.

· Degeneration of the ball & socket joint in the pelvis.

· Most common in large breed, rapidly growing dogs.

· Presents at 3-12 months of age.

· Can have a conservative approach but often will require surgery.

· Secondary osteoarthritis will develop.

· Obesity is a contributing factor.