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Bilateral MPL in Dogs: What You Need to Know

Bilateral MPL in Dogs: What You Need to Know

Medial Patellar Luxation

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Owners

Learn what bilateral MPL in dogs means, how it’s diagnosed, treated, and what recovery looks like when both knees are affected by luxating patella

By 

Sustainable Vet Group

Updated on

June 25, 2025

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What Is a Luxating Patella in Dogs?

A luxating patella means the dog’s kneecap (patella) slips out of its normal groove in the thigh bone. Instead of gliding smoothly when the knee bends, the patella pops to the side. This causes pain, limping, or skipping during movement.

Medial patellar luxation (MPL) is the most common type, where the kneecap shifts inward toward the other leg. It’s more frequent than lateral luxation, which moves outward and is usually seen in larger breeds.

In bilateral MPL, both knees are affected. Dogs may show lameness in both hind limbs, bunny-hopping, or trouble rising and walking. Symptoms can appear on one side first but usually involve both knees over time. Bilateral cases can range from mild to severe and may require surgery to correct pain, improve limb use, and prevent long-term joint damage.

Why Do Some Dogs Get MPL in Both Knees?

Bilateral medial patellar luxation (MPL) often develops due to genetic and anatomical reasons. Some dogs are born with shallow grooves in their femur bones, which don’t hold the kneecap in place well. Over time, this leads to luxation—often in both legs.

Small breeds are more prone to bilateral MPL. Dogs like Pomeranians, Yorkshire Terriers, Chihuahuas, and Toy Poodles are commonly affected. These breeds tend to have inherited bone structures that don’t properly support the patella during movement.

Another major factor is limb alignment. If a dog’s legs are naturally bowed or rotated, it puts abnormal pressure on both knees. This uneven force allows the patella to move out of place in both limbs. Bone deformities in the femur or tibia, or tight soft tissues, also contribute.

Because these traits are often present in both hind limbs, it’s not unusual for both knees to develop MPL. In many cases, one side starts showing symptoms first, but the second knee usually follows. Early diagnosis helps prevent worsening on both sides.

Signs of Bilateral MPL You Should Watch For

When both knees are affected by MPL, the symptoms are often more noticeable and can affect your dog’s daily life. One of the most common signs is a skipping gait—your dog may hop with both back legs off the ground, especially during fast movement. This happens when both kneecaps slip out of place.

Other warning signs include:

  • Limping or stiffness in both hind legs
  • Bunny-hopping while walking or running
  • Difficulty getting up from rest or lying down
  • Reluctance to climb stairs or jump onto furniture
  • Occasional yelps when moving awkwardly

Some dogs may try to avoid using their hind legs altogether or shift more weight to their front limbs. This can lead to muscle loss in the back legs and an arched posture over time.

Because bilateral MPL affects both knees, these signs can be harder to spot than a limp on one side. Owners might think their dog is just lazy or tired, especially in small breeds that don’t show pain clearly. But early signs like bunny-hopping or hesitation with movement usually indicate both knees are involved. Timely vet evaluation can confirm the condition and guide treatment before it worsens.

How Vets Grade Bilateral MPL

Veterinarians use a grading system from 1 to 4 to assess the severity of patellar luxation in each knee. In bilateral MPL, both knees are evaluated separately, but treatment planning considers the overall effect on the dog.

  • Grade 1: The kneecap moves out of place with pressure but returns on its own. Dogs often show no signs.
  • Grade 2: The patella slips out more easily and may stay luxated briefly. Dogs may limp or skip occasionally.
  • Grade 3: The kneecap is out most of the time but can be pushed back manually. Dogs often have persistent limping.
  • Grade 4: The patella is permanently luxated and cannot be moved back. This causes severe lameness and structural changes.

Each grade reflects how unstable the joint is. Dogs with different grades on each leg may use one leg more than the other, but bilateral issues still impact both limbs over time. Grading helps determine whether surgery is needed and which leg to operate on first. It also guides rehab and long-term care planning.

How Bilateral MPL Is Diagnosed

Diagnosing bilateral medial patellar luxation (MPL) begins with a detailed physical exam. During the exam, the vet palpates both knees to feel how easily the kneecaps move out of place. The dog may be gently walked or trotted so the vet can observe signs like limping, skipping, or uneven gait.

Radiographs (X-rays) are commonly used to confirm the diagnosis. They show the alignment of the kneecap, femur, and tibia. In more complex or severe cases, especially with suspected bone deformities, CT scans may be recommended for a more detailed view of joint anatomy. Both knees are evaluated, even if symptoms appear worse on one side.

Early and accurate detection is key to successful treatment. Identifying the grade of luxation in each knee helps guide the right plan—whether that means monitoring, conservative care, or surgery. Since bilateral MPL can worsen over time, even mild cases should be regularly checked. Timely diagnosis helps prevent pain, joint damage, and complications in both knees, especially in young or small-breed dogs.

Treatment Options: Conservative vs Surgical

Not all cases of bilateral MPL require surgery. Mild or early-stage luxation (Grade 1 or 2) can often be managed conservatively—especially if the dog is not in pain and stays active.

Conservative treatment includes:

  • Weight management: Reducing excess weight lowers stress on the joints
  • Joint supplements: Products containing glucosamine and chondroitin may support cartilage health
  • Controlled activity: Limiting jumping and fast running helps avoid injury
  • Physical therapy: Light exercises can help build muscle and support knee stability

This approach works best for smaller dogs with low-grade luxation who aren’t showing consistent lameness. However, if symptoms worsen or if the patella dislocates frequently, surgery becomes necessary.

Vets typically recommend surgery for Grade 3 and 4 luxations or if both knees are causing discomfort and mobility issues. The decision depends on the dog’s quality of life, level of pain, and risk of long-term joint damage if left untreated.

Surgical Options for Bilateral MPL

When surgery is needed for bilateral MPL, the goal is to restore normal patella alignment and joint function. Surgeons may use one or more of these procedures:

  • Trochleoplasty: Deepening the groove in the femur to hold the patella in place
  • Tibial tuberosity transposition (TTT): Repositioning the bony attachment of the patellar tendon
  • Soft tissue balancing: Tightening or releasing tissues to improve kneecap tracking

Some dogs may also need bone reshaping or correction if limb deformities contribute to the luxation. Each knee is assessed individually, and the surgical plan is tailored to the severity on each side.

For bilateral cases, vets may stage the surgeries—correcting one knee first, then the second after initial recovery. This reduces stress during rehab and allows the dog to use one stable leg. In select cases, both knees may be operated on at once, but only if the dog’s health and recovery environment are well controlled. The decision depends on age, weight, support at home, and overall health.

What to Expect After Bilateral Surgery

Recovery from bilateral MPL surgery requires patience and planning. Whether surgeries are done together or separately, dogs need strict rest and restricted movement for the first 4 to 6 weeks. Crate rest, short leash walks, and avoiding stairs or furniture are essential.

  • Timeline: Weight-bearing usually starts within 1–2 weeks. Stronger walking returns by 4–6 weeks, and full recovery may take 3–4 months per leg.
  • Post-op care: Pain medication, anti-inflammatories, and ice therapy help in the early days.
  • Physical therapy: Gentle exercises and hydrotherapy build strength, restore motion, and prevent stiffness.

Follow-up visits are important to monitor progress, remove sutures, and assess healing through exams or X-rays. If only one leg is repaired first, the second surgery is often scheduled 6–8 weeks later, depending on the dog’s progress. Owners should be prepared for close monitoring and regular vet guidance during recovery.

Long-Term Outlook for Dogs With Bilateral MPL

With proper treatment, most dogs with bilateral MPL do very well long-term. The prognosis depends on the grade of luxation and treatment method. Dogs with mild cases managed conservatively can live comfortably with lifestyle changes and monitoring.

For those who undergo surgery:

  • Over 90% return to normal or near-normal activity, especially small to medium-sized breeds
  • Many regain the ability to walk, run, and play without pain
  • Regular rehab and weight control support long-term success

However, untreated or poorly managed bilateral MPL can lead to complications. Chronic luxation causes cartilage wear, arthritis, and even rupture of the cranial cruciate ligament (CCL). These issues make future treatment more complex and reduce quality of life.

Timely surgery, rehab, and follow-up care give the best outcomes. With the right plan, most dogs can enjoy a happy, active life—even after dealing with MPL in both knees.

FAQs

Is it common for dogs to have MPL in both legs?

Yes, it’s fairly common for dogs—especially small breeds—to develop medial patellar luxation (MPL) in both knees. Genetic factors and limb alignment often affect both legs equally. Even if signs appear on one side first, the second knee may develop symptoms later. Bilateral cases are more likely in breeds like Pomeranians, Yorkies, and Toy Poodles.

Can my dog walk normally after bilateral MPL surgery?

Most dogs regain normal or near-normal walking after bilateral MPL surgery, especially with good post-op care and physical therapy. Some dogs may have a mild limp during recovery, but this usually improves with time. Once healing is complete, many dogs return to regular activity, including running and playing, without ongoing pain.

How long is recovery if both knees are treated?

If both knees are treated (either together or one at a time), full recovery can take 4 to 6 months. Initial weight-bearing starts within 1–2 weeks. Dogs typically walk better by 4–6 weeks per leg. Physical therapy and vet follow-ups help track healing and speed up muscle strength return.

Should both knees be operated at the same time?

In some cases, yes—both knees can be operated on at the same time, especially in smaller, lighter dogs with strong home care support. However, most vets prefer staging the surgeries, treating one knee first and the other after recovery. This reduces stress and makes rehab easier for the dog and caregiver.

Is surgery always needed for bilateral MPL?

No, not always. Mild cases (Grade 1 or 2) in both knees may be managed with weight control, supplements, and activity changes. But if your dog shows frequent limping, pain, or reduced mobility, surgery becomes necessary. Your vet will grade both knees and recommend the best course based on your dog’s comfort and function.

What happens if I don’t treat MPL in both knees?

Untreated bilateral MPL can lead to chronic pain, joint damage, and arthritis. Over time, the abnormal movement wears down cartilage, affects muscle balance, and increases the risk of ligament injuries like cruciate tears. Delaying treatment can make surgery more complex and limit long-term success. Early intervention offers the best outcome.

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