Luxating Patella

The patella (kneecap) normally sits in a groove (the trochlear groove) at the bottom of the femur, gliding smoothly as the leg moves. In patellar luxation, the kneecap slips out of this groove - usually towards the inside (medial luxation, by far the most common in small breeds). The result is a characteristic intermittent skipping gait as the dog holds the leg up until the patella pops back into place.

The condition is most common in small breeds, and is usually developmental - the trochlear groove is too shallow to reliably retain the patella. It can also occur in larger breeds (typically lateral luxation) and may be associated with other skeletal abnormalities. It is often bilateral, affecting both hind legs to varying degrees.

The skipping gait: what to observe

The classic sign is a dog that takes several normal steps, then suddenly holds a hind leg up and skips for a stride or two before resuming normal gait - often with a little shake or kick to pop the patella back. Note:

• Which leg(s) are affected
• Frequency of the skipping episodes (how many times per walk)
• Duration - does the leg come back down quickly, or does the dog hold it up for longer?
• Whether the episodes are increasing in frequency over time
• Any change in willingness to exercise, jump, or climb stairs
• Whether you can hear or feel a click in the stifle

Grading

Patellar luxation is graded 1–4:

• Grade 1: Patella can be manually displaced but returns to groove immediately when released; dog rarely skips
• Grade 2: Patella luxates spontaneously during walking, causing intermittent skipping; can be manually replaced
• Grade 3: Patella is luxated most of the time but can be manually replaced; dog walks abnormally
• Grade 4: Patella is permanently luxated and cannot be manually replaced; significant lameness

Grades 1–2 are often managed conservatively (at least initially). Grades 3–4 generally require surgery.

Conservative management

For Grade 1–2 cases or dogs not yet suitable for surgery:

• Weight management - reduced joint load
• Controlled, low-impact exercise (avoiding jumping and repetitive stairs)
• Joint supplements (omega-3 fatty acids; glucosamine/chondroitin have limited evidence but are low-risk)
• Pain relief if the dog is showing discomfort
• Physiotherapy to strengthen the muscles supporting the joint

Log the frequency of skipping episodes weekly. If episodes are clearly increasing, surgery should be discussed.

Surgery

Surgery involves deepening the trochlear groove (trochleoplasty), repositioning the tibial crest (where the patellar tendon attaches), and tightening the joint capsule. In most cases, outcomes are excellent. Recovery is 6–8 weeks of controlled exercise followed by gradual return to normal activity.

Monitoring for complications

Luxating patella is associated with an increased risk of cranial cruciate ligament (CCL) disease - the abnormal mechanics of the stifle in a luxating patella case put abnormal stress on the CCL. Log any change in lameness character: a dog with known luxating patella who develops persistent lameness (not just the usual skipping) may have developed a CCL issue.

When to contact your vet

Contact your vet for a routine assessment if:

• You notice intermittent skipping in a small breed dog
• The frequency of episodes is increasing
• Your dog is showing pain or reluctance to use a leg

Contact your vet sooner if:

• A Grade 3–4 luxation is suspected (persistent or constant lameness)
• There is a sudden change in lameness quality suggesting possible CCL involvement

Frequently Asked Questions

My dog only skips occasionally - do we need to do anything? Grade 1–2 luxating patella that is genuinely occasional and not causing pain or increasing in frequency can be monitored rather than immediately treated. Log episode frequency, maintain lean body weight, and have the vet reassess annually. The key question is whether it's stable, improving, or worsening.

Is surgery always needed for luxating patella? No. Grade 1, and some Grade 2, cases are managed conservatively for years. Surgery is typically recommended when episodes are frequent, quality of life is affected, the dog is in pain, or the grade is 3–4.

Can both legs be operated on at once? Some surgeons prefer to address both legs in separate procedures to allow recovery on one leg while the other is being used. Others operate on both simultaneously, particularly in dogs where both legs are significantly affected. This is a surgical judgement call - discuss with the orthopaedic vet.

My small dog has been diagnosed with luxating patella - will they always have this? Yes, the underlying conformation doesn't change without surgery. However, many small dogs with Grade 1–2 luxation live comfortably for years with monitoring and conservative management. The condition may progress, stabilise, or remain mild.

Does luxating patella cause arthritis? Yes, over time. Repeated luxation causes cartilage damage and eventually osteoarthritis of the stifle. The rate of arthritis development depends on severity and how long the condition goes without management.