The Slipping Kneecap: Understanding Patellar Luxation

In this guide

Patellar luxation, where the kneecap slips out of its normal groove, is one of the most common orthopaedic problems in small and toy breeds, though larger breeds are not immune. Many Indian households with Pomeranians, Shih Tzus, Pugs, and other small breeds will encounter this at some point.

What causes it

Most cases are developmental, caused by a shallow or malformed groove in the thigh bone that fails to hold the kneecap securely in place, allowing it to slip sideways, usually inward. It can also result from trauma in dogs without an underlying predisposition.

Signs to watch for

• A sudden skip or hop in the back leg, followed by normal walking again
• Intermittent lameness that comes and goes
• Holding the leg up briefly and then shaking it out before walking normally
• In more advanced grades, a permanently bowlegged or crouched stance

How it is graded

• Grade 1: the kneecap can be manually pushed out of place but returns on its own
• Grade 2: the kneecap slips out occasionally during normal movement and pops back
• Grade 3: the kneecap is out of place most of the time but can be manually repositioned
• Grade 4: the kneecap is permanently displaced and cannot be repositioned

Treatment

Grade 1 and mild Grade 2 cases are often managed conservatively, with weight control, joint supplements, and physiotherapy. Grade 3 and 4, or any grade causing persistent lameness and discomfort, usually require surgery to deepen the groove and realign the supporting tissues. Left untreated, higher grade luxation increases the risk of early arthritis and, in some cases, a torn cruciate ligament in the same knee.

Common Questions

Q: Can patellar luxation affect both back legs? A: Yes, bilateral cases are common, and a vet will typically check both knees even if only one seems to be causing visible symptoms.

Q: Does surgery fully fix patellar luxation? A: In most cases yes, particularly when the correct surgical technique is matched to the grade of luxation and followed by proper rehabilitation.

Article content © Ravi Teja. All rights reserved.