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Success Rates for Medial Patellar Luxation Surgery

Success Rates for Medial Patellar Luxation Surgery

Medial Patellar Luxation

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Explore success rates for medial patellar luxation surgery by grade, including complications, recovery outcomes, and key factors that affect surgical success

By 

Sustainable Vet Group

Updated on

June 21, 2025

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What Is Medial Patellar Luxation (MPL)?

Medial Patellar Luxation (MPL) is a knee condition in dogs where the kneecap (patella) slips out of its normal groove on the femur. Instead of staying in place, it moves toward the inside (medial side) of the leg. This can cause pain, limping, or long-term joint damage if not treated.

Grades of MPL

  • Grade I: Patella slips out but returns on its own
  • Grade II: Patella comes out easily and may stay out sometimes
  • Grade III: Patella is out most of the time but can be pushed back in
  • Grade IV: Patella is always out and cannot be returned manually

Common Breeds and Risk Factors

  • Small breeds like Pomeranians, Chihuahuas, Poodles, and Yorkies
  • Genetic traits, shallow femoral grooves, or injury increase the risk

What Does MPL Surgery Involve?

Medial Patellar Luxation (MPL) surgery is done to correct the position of a dog's kneecap. When the patella keeps slipping out of place, it causes pain and changes how your dog walks. Surgery helps keep the kneecap stable and prevents long-term damage to the joint.

Goals of the Procedure

  • Keep the patella inside its groove during movement
  • Restore normal leg alignment and function
  • Reduce pain, limping, and joint wear
  • Prevent arthritis and other joint issues in the future

Common Surgical Techniques

Veterinary surgeons choose one or more techniques based on the dog’s grade of MPL and joint shape:

  • Trochleoplasty: Deepens the femoral groove so the kneecap stays in place
  • Tibial Tuberosity Transposition (TTT): Realigns the patellar tendon by moving a small bone piece
  • Lateral Imbrication: Tightens tissue on the outer side of the joint to support the kneecap
  • Medial Release: Loosens tight inner tissues that pull the patella out of place

Recovery Timeline in Brief

  • Dogs can bear weight in a few days
  • Activity must be limited for 6–8 weeks
  • Full healing takes about 12–16 weeks, including rehab and follow-ups

Success Rates by MPL Grade

Grade I–II: Highest Success (Up to 100%)

Surgery for Grade I and II MPL cases has the best results. These are mild forms where the kneecap may slip occasionally (Grade I) or more often but still return on its own or with help (Grade II). In both cases, joint anatomy is mostly normal.

  • Success rate: Up to 100%
  • Common procedures: Soft tissue tightening, medial release, trochleoplasty
  • Complication rate: Very low
  • Recovery time: 8–12 weeks for full return to normal function

Most dogs regain full use of the leg after healing. They walk and run normally without pain. Surgery at this stage also helps prevent arthritis or worsening joint issues in the future. In many Grade I cases, surgery isn’t even needed unless symptoms worsen.

Follow-up care includes rest, anti-inflammatory meds, and light rehab. These dogs typically do not need revision surgery, and the long-term outcome is excellent. Early treatment means faster recovery and fewer risks overall.

Grade III: High Success (90–100%) but Higher Recurrence

Grade III MPL is more advanced. The patella stays out of place most of the time but can be manually repositioned. Dogs often show more lameness, and their joint structure may need stronger correction.

  • Success rate: Around 90–100%
  • Common procedures: Trochleoplasty, TTT, lateral imbrication, medial release
  • Complication risk: Moderate, especially reluxation
  • Recovery time: 10–14 weeks, including rehab and checkups

Surgery often involves both bone and soft tissue work. In some dogs, the joint may still loosen over time, leading to partial luxation again. This is more likely if recovery is rushed or if the dog is very active during healing.

While most dogs return to near-normal movement, some may show minor stiffness or a mild limp, especially during exercise. A small number of dogs may need revision surgery later in life.

With proper surgical planning, weight control, and good rehab, most Grade III cases have strong outcomes and can return to a happy, active lifestyle.

Grade IV: Variable Success (64–93%)

Grade IV MPL is the most severe form. The kneecap is always out of place and cannot be pushed back manually. Dogs often have serious skeletal changes, like rotated tibias or shallow grooves, which require more complex surgery.

  • Success rate: Ranges from 64% to 93%
  • Common procedures: TTT, deep trochleoplasty, rotational correction, staged surgeries
  • Complication risk: High, especially reluxation or implant failure
  • Recovery time: 12–16 weeks or longer, depending on case complexity

These surgeries are more challenging and may involve multiple steps. In some cases, staged correction is needed to slowly fix the bone alignment over time. Healing is slower, and strict rest is very important to avoid complications.

Some dogs improve but may not regain full, normal motion. A mild limp or stiffness can remain, especially in older dogs or those with long-standing luxation. However, pain relief and improved comfort are still strong outcomes.

With skilled surgery, proper follow-up, and careful rehab, many Grade IV dogs live more comfortable, mobile lives—even if their function isn't perfect.

Complication and Recurrence Rates

While most dogs recover well after Medial Patellar Luxation (MPL) surgery, there are some risks to be aware of. The chance of complications or the kneecap slipping again depends on the grade of MPL, the dog’s age, the surgeon’s technique, and how well post-surgery care is followed.

Average Rates

  • Recurrence (reluxation) rate: 10–21%
  • Major complication rate: 16–24%

These numbers are higher in dogs with Grade III and IV luxation, where the joint is more unstable or the bone structure is more deformed.

Common Complications

  • Swelling or seroma: Fluid may collect near the incision site
  • Implant issues: Pins or wires used in surgery may move or loosen
  • Infection: Can happen at the wound site if not kept clean
  • Joint stiffness: Especially if rest is not followed properly
  • Recurrence: The patella may slip out again if healing is poor

Rare but Serious Outcomes

  • Nerve damage or long-term lameness
  • Poor bone healing in very active or older dogs
  • Amputation (very rare): Only needed if the leg becomes non-functional due to severe infection or failure

Proper rest, weight control, and follow-up care reduce most risks.

Factors That Affect Surgical Success

Not all MPL surgeries have the same outcome. Several key factors can affect how well a dog recovers and how stable the knee stays after surgery.

Key Factors

  • Age of the dog: Younger dogs tend to heal faster and adapt better. Older dogs may have slower recovery and higher arthritis risk.
  • Weight/body condition: Overweight dogs have more pressure on their joints, which increases the risk of complications and slower healing.
  • Other joint issues: Dogs with a torn cranial cruciate ligament (CCL) or hip problems may need more complex surgery.
  • Breed-related anatomy: Some breeds have shallow grooves or bone rotation, making surgery more difficult.
  • Unilateral vs bilateral surgery: Dogs with both knees affected (bilateral MPL) may take longer to recover, especially if both surgeries are done together.

Each of these factors plays a role in the dog’s outcome. A well-planned surgery combined with personalized care improves the success rate, even in more complex cases. Pre-surgical exams and imaging help identify these factors early so the treatment can be tailored to each dog’s needs.

Long-Term Outcomes and Owner Satisfaction

Most dogs that undergo MPL surgery enjoy long-lasting relief from pain and improved movement. Long-term success depends on the surgery quality and how well the dog is cared for afterward.

What Owners Can Expect Long-Term

  • Pain control: Most dogs are more comfortable and pain-free after healing. Long-term pain is rare if the joint is stable.
  • Activity levels: Many dogs return to normal activity—walking, running, and playing—within 3–4 months.
  • Satisfaction rates: Over 90% of owners report high satisfaction with the surgery, especially in Grades I–III.

Some dogs may still show mild stiffness or avoid certain movements, especially if they had a high-grade luxation or other joint conditions. Regular exercise, weight control, and avoiding intense jumping or rough play help preserve joint health over time.

Overall, MPL surgery has a strong track record of improving quality of life. Dogs move more freely, show less pain, and become more active after recovery. When paired with proper follow-up care, most dogs remain stable for many years after surgery.

How to Maximize the Chances of a Successful Outcome

Good surgical technique is just one part of MPL recovery. What happens after surgery is just as important for a full and lasting recovery.

Key Steps for Better Results

  • Post-op care: Strict crate rest for 6–8 weeks is critical. It prevents implant movement and allows the joint to heal properly.
  • Rehabilitation: Gentle rehab like controlled leash walks, underwater treadmill, or physiotherapy helps regain strength and range of motion.
  • Follow-ups: Regular vet checkups ensure healing is on track. X-rays may be needed to confirm bone healing and implant position.

Owners play a big role in the recovery process. Keeping the dog calm, using medications as prescribed, and following rehab steps all support better outcomes. It’s also important to avoid running, jumping, or stairs until your vet gives the all-clear.

Feeding a balanced diet and keeping your dog at a healthy weight also reduces joint stress. With the right support at home and guidance from your vet, your dog has the best chance to heal fully and return to an active, pain-free life.

Conclusion

Medial Patellar Luxation (MPL) surgery is a highly effective treatment for dogs with kneecap instability. With proper surgical planning and careful post-op care, most dogs return to normal or near-normal function. Success rates are especially high in Grade I–III cases, and even dogs with Grade IV can show major improvement.

While complications are possible, they are often manageable with early attention. Owners who follow vet instructions—especially crate rest and rehab—help their dogs heal faster and avoid reluxation. With patience and proper care, most dogs enjoy a more active, pain-free life after surgery.

FAQs

What is the average success rate for MPL surgery in dogs?

The success rate for MPL surgery is high. For Grade I–III cases, it ranges from 90% to 100%. Grade IV cases have a slightly lower success rate, between 64% and 93%, due to complex joint changes. Most dogs regain good function and live comfortably with proper care and follow-up.

Does the grade of MPL affect the surgery results?

Yes, the grade of MPL directly affects the surgery outcome. Lower grades (I–II) have simpler issues and near-perfect success. Grade III surgeries are more complex but still have high success. Grade IV often needs advanced correction and has a higher risk of complications, though many dogs still improve significantly.

What are the chances of MPL coming back after surgery?

The chance of the kneecap slipping again, called reluxation, is around 10–21%. This depends on the grade of MPL, the dog’s activity level, and how closely post-op care is followed. Proper rest, weight control, and vet follow-ups can lower this risk and help keep the knee stable.

How long does it take for a dog to recover from MPL surgery?

Most dogs begin walking within a few days but need 6–8 weeks of crate rest. Full recovery can take 3–4 months, especially for higher-grade surgeries. During this time, rehab and regular checkups help rebuild strength and ensure healing is on track.

Can my dog walk normally after MPL surgery?

Yes, most dogs can walk and even run normally after MPL surgery. Once healing is complete, they often return to normal activity levels. Minor stiffness or a limp may remain in rare cases, especially in Grade IV or older dogs, but pain and lameness usually improve.

Is MPL surgery safe for older or overweight dogs?

MPL surgery can be done safely in older or overweight dogs, but the risks are slightly higher. These dogs may heal slower or face more stress on the joint. With proper planning, pain management, and weight control, they can still have excellent results and better comfort long-term.

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