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The hip joint (coxofemoral joint) is made up the top (head which is ball shaped) of the thigh bone (femur), which normally sits snugly within the socket on one side of the pelvis (hip bone). The structure is held together by a strong ligament between the bones and a capsule that surrounds the joint. Hip dysplasia is a condition where the hip joint does not develop properly leading to a loose ligament and capsule causing the thigh bone not to sit securely within the pelvic bone.
The laxity of the hip joint gradually leads to inflammation of the joint, causing erosion of the smooth cartilage within the joint and within time, scar tissue and osteoarthritis (degenerative joint disease) will develop. In most cases of the hip dysplasia, eventually, the animal will experience pain and discomfort in the hip joint. Hip dysplasia is a condition that is caused by multiple factors which include genetics, exercise and nutrition.
Not all cases of hip dysplasia immediately result in pain or lameness of the leg. In severe cases, signs may begin to present from a young age e.g. 3-4 months. Signs can frequently improve as scar tissue develops and stabilizes the joint but eventually, as the osteoarthritis develops – animals will become progressively lame as the cartilage is destroyed.
Typically, affected animals may show a decreased range of motion in the hip joint (stiff gait – narrow stance), difficulty rising, jumping, climbing stairs and running, decreased activity, trembling or limping/lameness in hindlimbs. Often as the condition progresses, there is wasting of the backleg muscles. Pain is often worse after rest or strenuous activity.
A thorough physical examination by the veterinarian will often reveal pain and less mobility in the affected hip, especially when the hip is extended. Sometimes, sedation is needed examine looseness (laxity) in the joint by a test called an “Ortolani manoeuvre”.
Hip dysplasia is normally confirmed by x-rays of the hip joint under anaesthesia. Since this condition has a genetic component, it is often recommended not to breed from an affected animal.
Medical options of pain relief in the form of pain killers is a reasonable choice in older dogs, ones that are mildly affected or when there are financial limitations.
Conservative treatment may also involve the use of injections of polysulfated glycosaminoglycans (such as cartrophen – pentosan polysulfate), oral supplements such as green-lipped mussel extract and essential omega fatty acids (e.g. EPA and DHA) and strict weight management to minimize un-necessary load and stress on the joints. Acupuncture can also be used as an alternative means of improving the blood flow, decreasing the pain and inflammation of the affected joints.
Swimming is an excellent way of maintaining joint mobility and improving muscle tone while minimizing pressure on the joints. Hill walking can also help to build the muscles of the hindlimbs to give additional support to the joints.
In severe cases, surgery is often recommended. In Acorn hospital, for young animals that are still growing (less than 12 months of age), we may perform a surgical procedure called a TRIPLE PELVIC OSTEOTOMY, which involves rotating the acetabulum (socket) so the joint develops normally. We may also occasionally perform a surgery in immature animals called a JUVENILE PUBIC SYMPHYSIODESIS, which involves fusing part of the pelvic bone earlier than it occurs naturally to improve the joint shape and stability.
In adult animals, we perform one of two surgical procedures. The first is called a FEMORAL HEAD AND NECK OSTECTOMY, which is a straightforward surgery that eliminates the pain by removing the top part of the thigh bone and allowing scar (fibrous) tissue to fill in the void.
The other surgery performed in adult animals is a TOTAL HIP REPLACEMENT. This involves replacing the joint with a metal implant (similar to humans). This is an expensive surgery that can yield good results but complications such as infections, implants loosening/breaking are common.
A new option available to veterinarians is stem cell therapy. This involves using the fat of the affected animal to harvest stem cells, which are then injected into affected joint to help repair the damage joints (such as the cartilage). In the cases that have had stem cell treatment in Acorn hospital, we have so far been very impressed with the results leaving the animals pain-free with good mobility and needing no medication. This is a treatment option that so far is showing great promise for the future!