Dog Luxating Patella Surgery Grades

Of course. Patellar luxation is one of the most common orthopedic conditions we see, particularly in small breeds. A successful outcome hinges on a correct diagnosis, proper grading, and a multi-faceted surgical plan that addresses the specific anatomical deformities of that patient.

Here is my approach to these cases.

Patellar Luxation Grading

The grade determines the clinical signs and surgical urgency. Assessment should be done on a standing patient and in lateral recumbency with the stifle in flexion and extension.

* Grade I: The patella is in the trochlear groove but can be manually luxated. It spontaneously returns to the groove when released. Patients are often asymptomatic or show an intermittent "skip" in their gait.
* Grade II: The patella luxates frequently, either spontaneously or with manual pressure, and remains luxated until it is manually reduced or the stifle is actively extended. A skipping lameness is common.
* Grade III: The patella is permanently luxated but can be manually reduced into the groove. However, it will re-luxate as soon as manual pressure is removed. This causes a persistent, abnormal "crouched" gait and significant internal rotation of the tibia.
* Grade IV: The patella is permanently luxated and cannot be manually reduced. There is severe tibial rotation (up to 90 degrees) and often a shallow or absent trochlear groove. These dogs have a persistent, crouching gait and significant functional lameness.

Breed Predispositions

* Medial Patellar Luxation (MPL): Overwhelmingly common in small and toy breeds (Yorkshire Terriers, Pomeranians, Chihuahuas, Miniature Poodles, Boston Terriers). It results from a complex of conformational abnormalities, including coxa vara, femoral varus, and internal tibial rotation.
* Lateral Patellar Luxation (LPL): Less common and typically seen in large and giant breeds (Great Danes, St. Bernards, Irish Wolfhounds). It's often associated with femoral valgus (knock-kneed stance).

Management and Surgical Indications

Conservative management is reserved for Grade I cases with no clinical signs. This involves weight management, controlled exercise, and physical therapy to strengthen the quadriceps.

Surgery is indicated for any patient with consistent clinical signs (lameness, skipping), and for all Grade III and IV luxations. In my experience, a Grade II that is becoming more frequent is also a surgical candidate, as chronic luxation leads to cartilage erosion and osteoarthritis.

Surgical Techniques

A successful repair almost always requires a combination of procedures to correct all underlying deformities. Relying on a single technique, like a lateral imbrication alone, often leads to failure.

Tibial Tuberosity Transposition (TTT): This is the cornerstone of the repair. It realigns the entire quadriceps mechanism. An osteotomy is performed on the tibial tuberosity, which is then moved laterally (for MPL) to straighten the pull of the quadriceps tendon. It's fixed in its new position with K-wires and a tension band.

Trochleoplasty: If the femoral groove is shallow, the patella has no "track" to sit in. A recession trochleoplasty (either a wedge or block technique) deepens the groove while preserving the articular cartilage.

Soft Tissue Reconstruction: This involves a medial release (releasing the contracted medial retinaculum) and a lateral imbrication (tightening the stretched lateral joint capsule and fascia).

Post-Operative Care & Prognosis

Post-op care is critical. We enforce 8 weeks of strict cage rest with short, controlled leash walks for elimination only. Passive range-of-motion exercises can begin after 3-5 days. At 8 weeks, I take radiographs to confirm healing of the TTT osteotomy before beginning a gradual, controlled return to normal activity over the next month.

* Prognosis: Excellent for Grade I-III cases, with over 90% returning to normal or near-normal function. For Grade IV, the prognosis is more guarded due to the severe, chronic bony changes. While surgery will improve function, some degree of gait abnormality may persist.

Bilateral Considerations

Many dogs have bilateral disease. I strongly recommend a staged approach, operating on the more severely affected leg first. After an 8-week recovery, we can proceed with the second surgery. Performing simultaneous bilateral TTTs makes for a very difficult recovery for the patient and the owner, and I generally avoid it.