KSAH - Luxating Patella
Karrinyup Small Animal Hospital
5/207 Balcatta Road
Balcatta WA 6021 AU
08 9447 4644
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Luxating Patella

Patella luxation is one of the most common orthopaedic condition in dogs occurring in nearly 10% of all puppies.

Overview

Patella luxation commonly affects smaller dog breeds where the kneecap moves inwards (medial luxation) but can also occur in larger breed dogs where the kneecap moves outwards (lateral luxation). It is a condition whereby the kneecap (patella) intermittently or permanently stays outside the groove in which it should sit.

Unfortunately, in small breed dogs, this condition is often inherited from its parents. When the patella is out of the groove it may cause an unstable joint and the dog often holds its back leg up. Over time, this constant moving of the kneecap can cause arthritis and pain, and even lead to cruciate ligament disease.

Early diagnosis is best so that the condition can be managed. This may include pain medication, nutraceuticals, weight management, and surgery. Over 50% of dogs that suffer a luxating patella are affected in both legs.

Breeds commonly affected:

  • Pomeranian

  • Cocker Spaniel

  • Staffordshire Bull Terrier

  • Shar Pei

  • Chow chow

  • Pug

  • Dachshund

Signs

Common signs of luxating patella:

  • Little or intermittent limping

  • Skipping or stretching out of legs while running

  • Sudden limping while running

  • Lifting the affected leg off the ground intermittently

  • Bowlegged

  • Reluctance to jump

Causes

Common causes of luxating patella:

  • Genetics
  • Trauma

Diagnosis

Your Veterinarian will be able to diagnose a luxating patella on palpation of the knee joint. Your Veterinarian will palpate the knee, look for joint instability, pain and arthritis. Treatment depends on the severity of the condition.

Common grading of luxating patella:

  • Grade 1: the kneecap can be moved out of the joint but readily returns to normal position

  • Grade 2: the kneecap moves spontaneously during movement but returns to normal when the knee extends

  • Grade 3: the kneecap is out most the time but can be returned

  • Grade 4: the kneecap is out permanently and cannot be returned

Radiographs can be useful to show some of the bony deformities that may be causing the luxation, and will be required if surgery is indicated, as the surgeon will need to measure the bones for correct implant/wire size. Some dogs with luxating patellas will also have concurrent cruciate rupture, and will require an extra procedure performed at the same time as the patella repair. 

More complicated or higher-grade luxations may require CT scan, which can be performed at referral hospitals. 

Management

A dog with a Grade 1 luxating patella runs around happily, only intermittently lifts its leg off the ground and shows no pain. These dogs may only require rest and occasional pain relief.

Where the luxating patella is causing lameness and pain, especially in Grade 3 and Grade 4 luxation, treatment is warranted to help restore the joint so that the dog can move normally. In these cases, surgery is often the treatment of choice to help stabilise the joint (thus reducing risk of rupturing the cruciate ligament within the knee) and prevent early arthritis. There are many different surgical techniques depending on the severity of condition. Your Veterinarian or Specialist will be able to discuss the technique appropriate for your pet.

Types of surgery indicated for luxating patella include:

  • Deepening of the groove the patella should sit in

  • Tibial tuberosity transposition (cutting the part of the shin bone the patellar tendon attaches to and repositioning it below the groove).

  • Medial desmotomy (releasing the contracted tissue that stops the patella from returning to the groove).

Unfortunately with this condition, the higher the grade of luxating patella, the higher the risk of recurrence post surgery.

Post-surgery care may consist of:

  • Strict rest with only leash walking for the first 8 weeks

  • Post-surgery xrays are done 8 weeks following surgery

  • Slow transition to normal exercise after 8 weeks

NOTE: Intradermal sutures are dissolving sutures in the skin that do not require removal and are typically used in this surgery. In these cases, your pet will require post-surgery checkups but no sutures will be removed.

Prevention

Tips to help prevent a luxating patella due to trauma:

  • Avoid strenuous exercise including sudden turns, twisting movements and jumping off furniture

  • Always warm up with walking or massage prior to exercise

  • Consider non-weight bearing exercise such as swimming