Patellar luxation

Patella is another name for the kneecap and luxation means dislocation, so a patellar luxation refers to a dislocated kneecap. Lameness may be noticed in the hind limb and reluctance to jump, depending on the degree of luxation this can be intermittent or constant, and may or may not be painful. As a prey species, rabbits don’t readily show signs of pain, so may conceal how painful it is. But, as the condition is painful in other species, such as dogs, we should assume it is in rabbits too, even if signs seem mild.

When a healthy knee bends in an animal the kneecap (patella) slides up and down a groove on the bottom of the thigh bone. The patella is a sesamoid bone; one that is embedded in a tendon, so if the patellar is luxating it means that it’s slipping out of the groove causing the leg to ‘lock up’ becoming painful. This dislocation of the kneecap can, over time, cause osteoarthritis. The patella may move in and out of the groove resulting in intermittent lameness, but if it moves out permanently this results in constant lameness often making the rabbit totally lame on the affected leg.

The condition is most likely genetic, so some rabbits are born with a defect. This means the patella is pulled out of the groove because the groove is too shallow or the ligament that attaches in the wrong place and pulls on the patella as the knee bends. The defect can affect one or both knees. A luxating patella can also be caused by an injury such as jumping and landing awkwardly, falling, or being dropped.

Lameness in a hindlimb is often the first sign of patellar luxation, or the rabbit may have a history of intermittent lameness and will be less likely to want to move about. A rabbit with a luxating patella will be less likely to jump and may carry its leg at an abnormal angle. It also may not be able to straighten the leg due to shortening of the muscles and muscle wastage from lack of use. If the rabbit is not treated osteoarthritis will often develop. This might prevent the rabbit from moving around properly and not being able to clean themselves properly. You may notice uneaten cecotrophs on the floor of their enclosure, or cecotrophs may accumulate around their back end.

Some rabbits with this problem can go through their life without any treatment or surgery, but if it’s causing the rabbit pain or a poor quality of life, then your veterinarian will recommend the best treatment for it. Your veterinarian may suggest conservative management such as restricting their environment to a much smaller area, removing ramps and shelves to avoid overuse of the affected leg. Anti-inflammatory medications might also be prescribed for a few weeks. However, if the condition doesn’t improve, surgery might be the only option. The aim of surgery is to stabilise the patella in its groove to allow normal limb function.

Some rabbits with this condition can go through their life without any treatment or surgery, but if it’s causing the rabbit pain or a poor quality of life, then your veterinarian will recommend the best treatment for it.

Your veterinarian may suggest conservative management such as restricting their environment to a much smaller area, removing ramps and shelves to avoid overuse of the affected leg. Anti-inflammatory medications might also be prescribed for a few weeks. However, if the condition doesn’t improve, surgery might be the only option. The aim of surgery is to stabilise the patella in its groove to allow normal limb function.

If you have a bonded pair of rabbits, they shouldn’t be separated, so if one rabbit has to be taken to the veterinarians, take its mate along for company. Often having their mate there will give the sick rabbit encouragement to carry on. Taking their friend away will only depress and upset both rabbits.

Rabbits generally recover quite quickly from surgery and could even be using the affected leg 12 hours later. Discharge time will vary depending on the rabbit’s ability to eat and drink independently, and their pain management. Once home, your rabbit might need cage rest for several weeks alongside continuation of anti-inflammatory medication and regular check-ups with your veterinarian.

Patellar surgery in rabbits is not often performed due to the delicate nature of the bones, the risks of general anesthesia and the costs involved. Although anesthesia in rabbits is fairly high risk, it shouldn’t be a major factor in deciding if the surgery is appropriate or not, nor should it put you off if surgery is the best treatment plan for your rabbit. As with any type of surgery, all associated risks should be discussed before agreeing to going through with it.

If surgery is performed successfully, this can provide a good long-term outcome for your rabbit.