Dog Patellar Luxation: Grading System and Treatment Options

Does your dog occasionally "skip" while walking or suddenly lift a hind leg? This may be a sign of patellar luxation. This is one of the most common orthopedic problems in dogs, affecting at least 7% of puppies and particularly prevalent in small breeds. Understanding the grading system and treatment options helps you make the best decisions for your pet.

## What is Patellar Luxation?

A dog's knee joint consists of the femur, tibia, and patella (kneecap). Normally, the patella sits stably in the femoral groove and slides up and down as the leg bends and straightens.

Patellar luxation occurs when the patella dislocates from its normal position, sliding toward the inside (most common) or outside of the leg, causing abnormal joint movement, pain, and even lameness.

## Predisposed Breeds

Small dogs are more prone to patellar luxation. Common breeds include:

* Yorkshire Terrier
* Poodle (especially Miniature and Toy)
* Chihuahua
* Pomeranian
* Maltese
* Boston Terrier
* French Bulldog

Large dogs can also be affected, but it's relatively less common.

## Causes

### Congenital Factors

* Genetic heredity (primary cause)
* Shallow femoral groove at birth
* Abnormal bone development angles

### Acquired Factors

* Trauma (falls, jumping injuries)
* Obesity causing excessive joint stress
* Lack of exercise weakening muscles and ligaments
* Malnutrition affecting bone development

## Four Grades of Patellar Luxation

Veterinarians classify severity into four grades based on patella stability:

### Grade 1 (Mild)

* Patella normally stays in proper position
* Can be manually pushed out of groove but springs back automatically
* Usually no obvious symptoms
* Often discovered during routine checkups

### Grade 2 (Moderate)

* Patella occasionally slips out and doesn't spring back automatically
* Can easily be manually pushed back into position
* May show intermittent lameness or "skipping"
* Mild arthritis beginning to develop

### Grade 3 (Severe)

* Patella is out of position most of the time
* Can be manually pushed back but quickly slips out again
* Abnormal hind leg angle, obvious lameness
* Moderate to severe arthritis

### Grade 4 (Most Severe)

* Patella is completely dislocated and cannot be repositioned
* Severe hind leg deformity, may be unable to walk normally
* Over half of cases have concurrent cranial cruciate ligament rupture
* Surgery required for improvement

## Common Symptoms

Symptoms become more obvious as grade increases:

**Mild Symptoms:**
* Occasional "skipping" or lifting of hind leg while walking
* Leg shaking followed by return to normal walking
* May have no symptoms at all

**Moderate Symptoms:**
* Intermittent lameness
* Hopping movement with hind legs
* Abnormal sitting posture
* Reluctance to jump or climb stairs

**Severe Symptoms:**
* Persistent lameness
* Bowed or curved hind legs
* Hunched back when standing
* Pain, reluctance to move

## Treatment Options

### Conservative Treatment (Medical Management)

Suitable candidates:
* Grade 1 or some Grade 2 cases
* No obvious clinical symptoms
* Older dogs unsuitable for anesthesia
* Heart disease or other surgical contraindications

**Treatment Focus:**

* **Weight management**: Maintain appropriate weight to reduce joint stress
* **Moderate exercise**: Strengthen muscle support without overdoing it
* **Environmental adjustments**: Avoid overly hard or slippery surfaces
* **Nutritional supplements**: Joint health products as support
* **Regular monitoring**: Watch for condition deterioration

### Surgical Treatment

Suitable candidates:
* Grade 3 and Grade 4
* Grade 2 with obvious clinical symptoms
* Young dogs (surgery recommended even with mild symptoms)

The goal of surgery is to stabilize the patella in its normal position.

**Common Surgical Procedures:**

| Procedure Name | Purpose |
|----------------|---------|
| Trochleoplasty | Deepens the patellar groove to increase stability |
| Tibial tuberosity transposition | Adjusts tendon angle to realign patella |
| Joint capsule tightening | Tightens joint capsule for added support |
| Corrective osteotomy | Corrects bone curvature or angle abnormalities |

Clinical experience shows that patellar luxation surgery has a success rate exceeding 90%.

## Post-Operative Care Essentials

The golden rehabilitation period after surgery lasts up to six months, and care quality directly affects recovery outcomes.

**Early Post-Op (1-2 weeks):**
* Strict activity restriction, cage rest primarily
* Take medications on schedule (pain relief, anti-inflammatory, antibiotics)
* Check wound daily, keep dry and clean
* Use e-collar to prevent wound licking

**Mid Post-Op (2-8 weeks):**
* Gradually increase activity, but still restricted
* Can perform passive range of motion exercises
* Physical therapy or hydrotherapy rehabilitation
* Avoid jumping, running, sudden turns

**Long-Term Post-Op:**
* Continue joint health maintenance
* Maintain appropriate weight
* Regular follow-up appointments

## Daily Joint Care

Whether or not surgery is performed, daily care is important:

**Nutritional Supplements:**
* Glucosamine, chondroitin: Support cartilage health
* Hyaluronic acid: Joint lubrication
* Omega-3: Reduce inflammation
* Collagen: Maintain cartilage structure
* Curcumin: Natural anti-inflammatory

**Lifestyle Adjustments:**
* Maintain healthy weight
* Avoid running on slippery floors
* Provide non-slip mats
* Use pet stairs or ramps
* Moderate walks, avoid intense exercise

## When to See the Vet?

See a vet promptly if you notice:

* Frequent intermittent lameness
* Abnormal hind leg walking posture
* Reluctance to jump or decreased activity
* Pain response when hind leg is touched
* Hind legs appear curved or deformed

Even mild Grade 1 or 2 cases should be monitored regularly. If young dogs have patellar luxation and it's left untreated long-term, it may lead to cartilage wear, arthritis, and even cranial cruciate ligament rupture.

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**References:**
* [狗狗膝關節異位認識與治療 - 木入森Moreson](https://www.moreson.com.tw/moreson/blog-detail/furkid-knowledge/pet-Illness-and-medical/dog-patella-luxation/)
* [膝蓋骨異位手術判斷 - 博愛動物醫院](https://www.poaipets.com.tw/膝蓋骨膝關節異位脫位到底要不要手術呢？/)
* [狗狗膝蓋骨脫位 - Vetopia](https://www.vetopia.com.hk/zh/blogs/news/patella-luxation)
* [膝蓋骨異位 - Dog Being](https://dogbeing.com/tw/blogs/20c047a1)
* [狗狗膝關節異位全解析 - 奧沛OurPet](https://www.ourpet.com.tw/blogs/blogs/189539)

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