Patella dislocation by Dr Bardet, at Abvet Clinic, Neuilly-sur-Seine
Dislocation of the patella is one of the most common causes of hind limb lameness in dogs. The patella is a small bone located in the extensor apparatus of the knee which serves as a lever for its extension.
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The patella normally slides normally harmoniously into a groove called the femoral trochlea in front of the knee. The dislocation of the patella is either medial (inside) or lateral (outside). The clinical consequence is the impossibility of correctly extending the knee as well as a mechanical deficiency. Over time, the dislocation of the patella can lead to arthrosis.
How can I tell if my dog has a dislocated patella?
Patellar dislocation mainly affects dogs but can also be observed in cats. Dogs of small breeds are mainly affected (Poodle, Yorkshire, Pinscher, Spitz, Chihuahua...) but all breeds can be affected. Patellar dislocation develops during growth. Animals may not be affected even if their gait is stiff. They may hop occasionally on the limb or present a continuous lameness more or less severe. The severity of the lameness is often related to the severity of the dislocation of the patella.
What causes patella dislocation?
The cause of patella dislocation is mainly genetic and is the result of breed selection with an arched conformation of the hind limbs. Animals are born with normal knees but develop bone and muscle deformities very early, sometimes after a few weeks, often after several months.
anatomical anomalies associated with medial dislocation of the patella
What are the anatomical abnormalities associated with patella dislocation?
The soft tissue and skeletal abnormalities associated with patella dislocation are medial displacement of the extensor quadricipital apparatus of the knee, lateral torsion of the distal femur and lateral curvature of the distal third of the femur.
How are patella dislocations classified?
Four types of patella dislocation are described according to severity:
- Grade 1: Patellar dislocation is rare and can only be dislocated manually.
- Grade 2: the patella is occasionally dislocated and may reposition spontaneously. It is reducible.
- Grade 3: Patella is dislocated most of the time but can be manually reduced with the knee in extension. However, manual reduction is not permanent as the patella will spontaneously reposition itself.
How is patella dislocation diagnosed by Dr Bardet, Clinic Abvet?
Patellar dislocations are often diagnosed during a routine examination or vaccination of young dogs. Orthopedic examination of the knee alone can detect the direction (medial or lateral) and grade of the dislocation.
The diagnosis of patella dislocation is multimodal at the ABVET veterinary clinic in Neuilly-sur-Seine. The orthopedic examination is completed by an X-ray examination of the knee and a CT scan for grade 3 and 4 patella dislocations.
It is now recognized that the best way to measure angles on bones is with a scanner. The purpose of these examinations is to eliminate other diseases that may cause the same symptoms first, to grade possible osteoarthritis and to plan the reconstructive surgery correctly.
How is a patella dislocation treated by Dr Bardet, Clinic Abvet?
The treatment of the patella can be conservative or surgical. When patella dislocation is discovered by chance during a routine examination, conservative treatment is most often appropriate. Surgical treatment is recommended for growing animals with discomfort and for adult animals with lameness.
Non-surgical conservative treatment
Non-surgical treatment of patellar dislocation in dogs uses hygienic treatment with weight loss, exercise modification and non-steroidal anti-inflammatory drugs. This treatment improves the symptoms but does not necessarily lead to a cure. It is also a waiting treatment for animals that will be operated on. It is not possible to treat a purely mechanical problem with simple medical treatment.
Surgical treatment of patella dislocation
Surgical treatment of patella dislocation is recommended for the last 3 grades of patella dislocation. Dislocations without bone deformity of the femur and tibia, usually grades 2 and 3, are treated by a combination of 3 techniques.
Sulcoplasty of the femoral trochlea consists of deepening the trochlea (throat), which is often flattened or even bulged.
Transposition of the tibial tuberosity allows the insertion point of the tibiorotulus tendon to be moved to align the knee extensor apparatus with the distal femur.
Soft-tissue reconstruction is used to release tension on the side of the dislocation and to ensure sufficient tension on the side opposite the dislocation.
What is the prognosis after treatment of patella dislocation at the ABVET specialist clinic in Neuilly-sur-Seine?
Recovery after the operation requires 4 to 6 weeks of rest with minimal activity. When recovery is noted after this period, your dog returns to completely normal activity without any after-effects. The prognosis is excellent since the bone corrections have been considered and practically all animals walk normally again.
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