What is Medial Patellar Luxation (MPL) in Pets?

Medial Patellar Luxation occurs when the kneecap (patella) slips out of its normal groove on the inner side of the knee joint. This condition affects the stifle joint (knee) and can involve one or both hind legs. MPL is common in dogs but also occurs in cats, causing varying degrees of lameness and discomfort.

When the patella luxates, it disrupts the normal extension mechanism of the knee, preventing your pet from properly straightening their leg. Over time, this leads to pain, arthritis, and potential complications including cruciate ligament disease.

MPL Grading System

Veterinarians classify MPL into four grades based on severity:

Image from Brighton Veterinary Hospital

Grade 1 MPL

Patella can be manually luxated but returns to normal position when released. Pet shows minimal lameness.

Grade 2 MPL

Patella luxates spontaneously but can be manually repositioned. Occasional lameness or "skipping" gait observed.

Grade 3 MPL

Patella remains luxated most of the time but can be manually repositioned temporarily. Persistent lameness present.

Grade 4 MPL

Patella permanently luxated and cannot be repositioned manually. Severe lameness and inability to extend the knee.

Primary MPL in Dogs

Primary MPL is a developmental condition typically affecting:

  • Small Breed Dogs: Toy Poodles, Yorkshire Terriers, Chihuahuas, Pomeranians, Maltese, and Boston Terriers
  • Large Breed Dogs: Labradors, Golden Retrievers, Akitas, Malamutes, Boxers, and Huskies
  • Cats: Devon Rex and Abyssinian breeds (less common)

Usually diagnosed in young animals under 12 months of age, primary MPL results from congenital skeletal abnormalities affecting the femur and tibia alignment.

Secondary MPL in Dogs

Secondary MPL develops due to:

  • Trauma or injury to the knee joint
  • Infections causing joint inflammation
  • Other knee conditions creating instability
  • More common in larger dogs following injury

Treatment Options for MPL

Treatment depends on severity and underlying cause:

Non-Surgical Management

Limited to Grade 1 cases or when surgery is not feasible:
– Anti-inflammatory medications
– Weight management programmes
– Controlled exercise protocols
– Physiotherapy and muscle strengthening
– Joint supplements for cartilage health

Surgical Treatments

Surgery is the definitive treatment for Grade 2-4 MPL and some Grade 1 cases. The specific surgical procedure depends on your pet's anatomy and the severity of the condition.

More about Surgical Procedures

Soft Tissue Procedures:

  • Lateral imbrication (tightening the outer joint capsule)
  • Medial desmotomy (releasing tight inner structures)
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Bony Procedures:

  • Trochlear groove deepening (creating a deeper groove for the patella)
  • Tibial crest transposition (repositioning the attachment point of the patellar ligament)
  • Corrective osteotomies for severe angular deformities

Most cases require a combination of these techniques for optimal outcomes.

Fixed Price MPL Surgery

MPL Surgery for Small Dogs: $2,400*
MPL Surgery for Medium Dogs: $2,900*
MPL Surgery for Large Dogs: $3,200*

Prices are indicative only*

The above cost estimate includes:

  • Pre-surgical examination & consultation
  • General anaesthesia and monitoring
  • Pre-anaesthetic blood work
  • Surgical procedure and implants (if required)
  • Intravenous fluid therapy
  • Pain management medications
  • Post-operative monitoring
  • Initial follow-up consultation

Factors that influence the surgery cost:

  • Weight of the dog
  • The complexity of the surgery

Additional prices that may apply:

  • Advanced imaging (CT scan) only if required
  • Extended hospitalisation ($150-$300/day)
  • Rehabilitation therapy ($80-150/session)
  • Infections of any kind

Why Choose Animal Surgery Centre Centre for MPL Surgery?

  • Dr Jas has over 21 years of experience as a vet.
  • Dr Jas has performed over 1400+ orthopedic surgeries.
  • Quality care at affordable prices.
  • Advanced equipment and surgical techniques
  • Proven track record and exceptional patient outcomes
  • State-of-the-art surgical equipment and modern fixation methods

The MPL Surgical Process

Pre-Surgery Evaluation

  • Our experienced veterinarians conduct a comprehensive assessment including:
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  • Detailed orthopaedic examination
  • Range of motion testing
  • Gait analysis and lameness evaluation
  • Radiographs (X-rays) to assess bone structure
  • Pre-anaesthetic blood work
  • Discussion of surgical options and prognosis

Day of Surgery

MPL surgery is performed under general anaesthesia and typically takes 1-2 hours depending on complexity:

  • Anaesthetic induction with full monitoring equipment
  • Surgical site preparation with sterile draping
  • Soft tissue procedures to rebalance forces around the knee
  • Bony modifications if required for Grade 3-4 cases
  • Closure with absorbable sutures
  • Recovery monitoring until your pet is stable

Most pets can go home the same day.

Post-Operative Care and Recovery

Immediate Care (First 48 Hours)

  • Pain management: Prescribed medications given as directed
  • Rest and confinement: Crate rest or small room confinement
  • Incision monitoring: Check for excessive swelling or discharge
  • Elizabethan collar: Prevent licking of surgical site

Recovery Timeline

Weeks 1-2: Initial Healing

  • Strict rest and confinement
  • Short leash walks for toileting only (5 minutes)
  • No stairs, jumping, or off-leash activity
  • Most pets begin weight-bearing within 10 days
  • Suture removal at 10-14 days

    Weeks 3-4: Early Mobilisation

    • Recovery starts in second Gradual introduction of controlled walking
    • Lead walks increasing to 5 minutes twice a day
    • Gentle range of motion exercises
    • Swimming allowed under veterinary supervision
    • Continued strict supervision required

    Weeks 5-8: Progressive Activity

    • Increasing weight-bearing and improved mobility
    • Lead walks extending to 5-10 minutes, 2-3 times daily
    • Introduction of gentle inclines
    • Hydrotherapy and physiotherapy beneficial
    • No jumping or stairs until cleared by veterinarian

    Weeks 9-12: Return to Function

    • Good weight-bearing with minimal lameness
    • Walks extending to 30+ minutes
    • Gradual introduction of off-leash activity (short periods)
    • Return to stairs and normal household activities
    • Most pets achieve 90-95% normal function

    Further Readings:

    Rate of Success & Risks

    Success Rates and Prognosis

    MPL surgery has excellent success rates when performed by experienced surgeons:

    • Grade 1-2: 95-98% excellent outcomes
    • Grade 3: 90-95% good to excellent outcomes
    • Grade 4: 85-90% good outcomes with some functional limitation

    Most pets return to normal or near-normal activity levels within 12 weeks of surgery.

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    Risks and Complications

    While MPL surgery is generally safe, potential complications include:

    Anaesthetic Risks: Modern anaesthesia is very safe with proper monitoring and pre-surgical assessment.

    Infection: Rare but prevented with antibiotics and proper wound care. Signs include persistent swelling, discharge, or heat around the incision.

    Implant Issues: Loosening or migration of surgical implants occurs in less than 5% of cases.

    Incomplete Correction: Some high-grade cases may require revision surgery for optimal results.

    Arthritis Development: Long-term arthritis can develop regardless of surgery, but surgical correction significantly slows progression.

    Re-luxation: Recurrence is uncommon (less than 10%) when appropriate surgical techniques are used.

    Signs and Symptoms of MPL

    Signs and Symptoms of MPL

    Pet owners should watch for these indicators:

    Lameness Patterns:

    • Intermittent "skipping" or "hopping" on affected leg
    • Holding leg up while walking or running
    • Difficulty rising from sitting or lying position
    • Reluctance to climb stairs or jump

    Physical Signs:

    • Visible displacement of kneecap when examining the leg
    • Swelling around the knee joint
    • Muscle wasting in the affected leg
    • Bow-legged appearance in some cases

    Behavioural Changes:

    • Reduced activity levels
    • Reluctance to play or exercise
    • Sitting to one side to favour the affected leg
    • Pain when knee area is touched or manipulated

    Early diagnosis and treatment prevent progression to higher grades and reduce the risk of secondary complications.

    Preventing MPL Complications

    Preventing MPL Complications

    • Maintain ideal body weight to reduce stress on joints
    • Follow post-operative instructions precisely
    • Attend all follow-up appointments for monitoring
    • Gradually increase activity as directed by your veterinarian
    • Provide appropriate exercise throughout your pet's life
    • Consider early desexing to prevent some developmental issues

    Most pets with properly managed MPL surgery live completely normal, active lives without ongoing lameness or pain.

    Ready to restore your pet's mobility and eliminate their discomfort? Contact Animal Surgery Centre today to schedule a consultation with our experienced orthopaedic team.