Hip Dysplasia

This is a condition that can range from the purely abnormal in terms of radiographic appearance to the clinically disabling. The key to management is differentiating between the two. The latter is the target of any therapeutic intervention, whilst the former needs monitoring.
The key then is learning how to differentiate one from the other and developing a strategy for monitoring the patient that does not appear to need intervention currently. Just as important is differentiation between the patient that has radiographic Hip Dysplasia but is lame due to other pathology.

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Differentiating Clinical from Non (sub) clinical Hip Dysplasia

The key to this is not necessarily as straight forward as it may sound! The obvious thing to assess is whether the patient is lame or not, but the observation of lameness in a patient with Hip Dysplasia does not necessarily indicate that this is due to the Hip Pathology. The commonest cause of hindlimb lameness in dogs, whether they have Hip Dysplasia or Hip Degenerative Joint Disease (DJD) is Cranial Cruciate Ligament Degeneration. The first step then is to palpate the stifle for effusion, instability and so forth. Even in the absence of palpable pathology, I will always take at least a mediolateral projection of the stifles. The presence of radiographic evidence of effusion or DJD would certainly make me revise the diagnosis for the cause of presenting lameness, stiffness or difficulty rising. Aspiration of Synovial (Joint) fluid and possibly arthroscopic evaluation may be required to elucidate the source of the effusion further.

Mediolateral Projection showing the presence of Stifle Effusion

Other conditions that should be ruled out in juvenile patients include:

  • Hock Osteochondrosis Dissecans.
  • Patellar Luxation.
  • Sesamoid Pathology.
  • Myopathies.
  • Septic Arthritis.
  • Panosteitis.

In the mature patient these additional conditions should be evaluated and excluded:

  • Immune Mediated Polyarthropathy.
  • Lumbosacral Pathology.
  • Intrapelvic Neoplasia causing compressive neuropathy.
  • Gastrocnemius Tendon Insertionopathies.

Having established that (non septic) hip pathology is the cause of lameness the next question is the nature of the hip based lameness. Hip based lameness in juveniles may result from instability, cartilage loss, periarticular soft tissue pain or micro fracture of the Dorsal acetabular rim.

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