plateau. The femoral trochlear groove is shallow or absent, with displacement of the quadriceps muscle group in the direction of luxation. Treatment Grades II, III, and IV require surgery to correct, if the animal has difficulty walking. The surgery required is governed by the type of abnormality present, but often involves a sulcoplasty, a deepening of the trochlear sulcus where the patella sits, a realignment of the attachment of the patella tendon on the tibia, and tightening or releasing of the capsule on either side of the patella, according to which side the patella is slipping. Some grade IV conditions may require more involved surgery to realign the femur and/or tibia. A therapeutic dosage of glucosamine can be used as a preliminary treatment to strengthen ligaments and the surrounding tissues of the joint and can delay or prevent surgery. Additional help can be given with the use of pet ramps, stairs, or steps. These can help the animal travel from one place to another, especially up and down, without adding any pain or damage to the patella. Dog & cat breeds affected Most cases of patellar luxation are medial, and this is frequently a congenital problem in toy- and miniature-breed dogs. Breeds showing a predisposition for medial patellar luxation include miniature and toy Poodles, Maltese, Jack Russell Terriers, Yorkshire Terriers, Pomeranians, Pekingese, Patterdale Terriers, Chihuahuas, Cavalier King Charles Spaniels, Papillons, Boston Terriers, Plummer Terriers and Teddy Roosevelt Terriers. Large-breed dogs are also affected, and the Labrador retriever seems particularly predisposed. Patellar luxation is less common in cats than in dogs. Predisposed breeds include the Devon Rex and the Abyssinian. Although the specific cause of patellar luxation is unknown in these cases, a defect in hind limb conformation is generally agreed to be the underlying cause. References External links Cat diseases Dog musculoskeletal disorders Patella