Medial luxating patella in dogs: Graham’s story

Graham (not his real name) came in to the clinic as a limping puppy. His owner complained that he periodically held his right back leg up for short periods but it always suddenly “came right”. Graham was a very healthy Mastiff Cross puppy with no other issues.

Although Graham enjoyed his examination, I did find that his right kneecap was “loose”. It could be popped out of the groove at the end of the thigh bone in which it should sit. This problem is called medial luxating patella; a relatively common congenital or developmental problem in small breed dogs but seen less frequently in larger dogs. Graham was special in this sense.

Graham was not overly troubled by this at this time and we decided to wait and see what might develop as he grew.

Unfortunately, we saw him several more times over the next six months. He was not going to get better without surgery.

Graham’s big day arrived, and in addition to his knee surgery we were to neuter him – a very big day for Graham! This was routine, but his knee surgery was not. What we choose to do here depends on the patient’s age and the anatomy at the time of surgery. For Graham we decided to do a tibial transposition (cutting and realigning the front of his shin bone, where the tendon from the knee cap attaches), a medial fascial release (loosening the connective tissue to one side of the kneecap) and imbrication of the lateral fascia (tightening it on the other side of the kneecap).

Graham's knee

Transposing his patella insertion is the biggest and most influential part of the surgery (see image below). This allows the kneecap to articulate freely in the patella groove and requires some bone at the top of the tibia to be cut and moved 5-8 mm to the side and pinned in place. In some cases, wire is used to overcome the forces at the surface of the healing bone, wanting to pull it apart again.

Medial (toward the midline) fascial release removes pulling forces that have developed in the soft tissue sheath that draw the kneecap medially and lateral imbrication tightens the soft tissue laterally (toward the outside). Together these lead to a neutral supporting role  to allow the kneecap to sit nicely in its groove. His patella groove was very normal and functional, so we left that alone. In some patients this is quite shallow or even non-existent and a trochleoplasty is required to make the groove deeper.

Graham has recovered well from his surgery and he has now begun a physical therapy rehabilitation course with our Vet Nurses. Over eight sessions he and his owners will receive a tailored exercise and treatment plan that will speed his recovery and get him using the leg to its full potential. After orthopaedic surgery it takes two to three months for bone healing and rehabilitation to occur, and the physiotherapy and aftercare is just as important as the actual surgery.

 

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