In, out, in, out... What is patella luxation and what can we do about it?

Background Patella luxation is a common orthopedic issue, approximately 1.3% of all dogs are living with this condition, and this increases to 75% in specific breeds. As we will discuss, there are grades to this pathology and it can be anything from a mild annoyance to extremely painful and debilitating. Seeing your four-legged best friend in any kind of discomfort is always horrible, and it’s difficult to know what’s happening and what to do about it. So, let’s unpick this condition and see if we can take some of the mystery away!

Anatomy

The patella (or kneecap) sits in a shallow groove at the front of the femur, where it can slide up and down when your dog bends or straightens its stifle (or knee). It is attached to the quadriceps muscle via the thick quadriceps tendon, and to the front of the tibia via the patella tendon. The patella acts to help  in straightening the leg by acting as a pulley, increasing the power of the quadriceps.

Pathology 

Luxation is another word for dislocation. Patella luxation occurs when the patella moves in and out of the groove where it is supposed to sit. It is more common that this occurs medially, with the patella moving toward the inner thigh, but it can also occur laterally. It may occur on one or both legs. Patella luxation can make it difficult for your dog to move their knee, and can be painful at times. Furthermore, this increases the risk of the development of osteoarthritis later in life.

There are four grades of patella luxation.

Grade I: Patella can be manually luxated (by the vet or physiotherapist) but returns to the normal position when released 

Grade II: Patella luxates with flexion of the stifle, or manually, and remains luxated until stifle extension or manually replaced 

Grade III: Patella constantly luxated, can be manually replaced but will luxate again when manual pressure is released

Grade IV: Patella constantly luxated and cannot be replaced

Signs and Symptoms 

• Signs of pain such as crying, yelping or licking the area 

• Skipping or hopping type gait

• Lameness (limping) with hind leg

• Reluctance to walk, run or jump 

• “Bow legged” or “knock kneed” posture 

• Decreased muscle mass of the affected leg

Risk Factors 

• Small breeds are more likely to develop patella luxation, including Pomeranians, Poodles, Cavalier King Charles Spaniels, French Bulldogs, Terriers and Chihuahuas

• Young dogs  

• Overweight dogs 

• Dogs with hip dysplasia

• Dogs with abnormal anatomy, such as curved femurs, poor alignment of the femur and tibia or shallow grooves on the femur

• Traumatic injury to the stifle

• Dogs with cruciate injuries or other causes of stifle instability 

Veterinary Input 

Vet input depends on the severity of the condition, and can range from rest to surgery. A period of rest, or a short course of pain relief may be appropriate for mild cases. It is important to keep your dog at a healthy weight, as excess kilos can exacerbate the condition, so your vet may chat to you about diet or exercise if your dog is on the heavier side. Joint supplements may also be recommended. For more severe cases, surgery may be required. This can involve deepening the groove the patella sits in, tightening up soft tissue to help stabilise the patella, or repositioning the patella tendon attachment site to improve alignment. Recovery from this type of surgery typically involves restricted activity for 6-12 weeks and referral to physiotherapy, but these procedures generally have a good prognosis.

Physiotherapy Input 

Physio takes a multifaceted approach when it comes to the management of patella luxation. First and foremost, your dog’s comfort is our complete priority. We can work alongside the vet to help relieve pain and inflammation, with treatment such as laser, TENS, PEMF, massage and gentle stretching. 

Once we have that pain under control, it’s time to get to work and build some muscle! By strengthening the muscles of the leg, we can help stabilise the patella and potentially reduce the frequency or degree to which the patella is luxating. At JDP, this usually means utilising both our underwater treadmill and creating a land-based strengthening program. If your dog is on the heavier side, these tools can simultaneously be used to help with weight management. 

We will also work at restoring normal gait patterns and function of the knee, helping your dog to feel comfortable to bend and straighten their stifle normally. It’s important we strengthen muscles in a correct movement pattern, rather than strengthen the movement dysfunction! 

 By decreasing pain, increasing strength and improving function, we can improve quality of life and provide you with a happier and healthier pooch. We may not necessarily be completely eliminating the luxation, but by keeping that limb moving and strong we can minimise the effect this has on your dog and hopefully delay or reduce the long term effects of patella luxation, such as osteoarthritis.

If you notice your dog skips while running, or you have felt their knee “click” when you’ve been cuddling them, come and see us for a chat (after consulting your veterinarian). Even if it is not currently affecting your dog - prevention is better than a cure! By catching it early, we can work alongside your veterinarian and set you up with the tools you need to make sure this doesn’t become a problem.

Let’s keep our four-legged buddies moving!

References:

Di Dona, F., Della Valle, G. and Fatone, G. (2018). Patellar luxation in dogs. Veterinary Medicine: Research and Reports, Volume 9(9), pp.23–32. doi:https://doi.org/10.2147/vmrr.s142545.

‌Engdahl, K., Bergström, A., Odd Viking Höglund and Hanson, J. (2023). The epidemiology of patellar luxation in an insured Swedish dog population. Preventive Veterinary Medicine, 220, pp.106034–106034. doi:https://doi.org/10.1016/j.prevetmed.2023.106034.

Roush, J.K. (1993). Canine Patellar Luxation. Veterinary Clinics of North America: Small Animal Practice, 23(4), pp.855–868. doi:https://doi.org/10.1016/s0195-5616(93)50087-6.