Medial Patellar Luxation (MPL)

Medial Patellar Luxation (MPL) is a common orthopedic condition in pets, especially small-breed dogs, where the kneecap (patella) slips out of its normal position toward the inside (medial side) of the leg. This abnormal movement can cause pain, limping, and long-term joint damage if left untreated.

What Causes Medial Patellar Luxation
 MPL is most often a developmental condition, meaning pets are born with limb alignment that predisposes the kneecap to slip out of place. It can affect one or both hind limbs.

Contributing factors may include:
  • A shallow groove in the femur where the patella sits
  • Abnormal alignment of the femur or tibia
  • Tight or imbalanced soft tissues around the knee

Signs of Medial Patellar Luxation
 Pets with MPL may show:
  • Intermittent skipping or hopping on a hind leg
  • Sudden lameness that resolves quickly
  • Stiffness or difficulty rising
  • Decreased activity or reluctance to jump
  • Chronic limping in more advanced cases

How MPL Is Diagnosed
 Medial patellar luxation is diagnosed through a physical orthopedic exam. In many cases, X-rays are recommended to assess joint alignment, rule out arthritis, and help guide treatment planning.

MPL is graded from Grade I to Grade IV, based on how easily the patella moves out of place and whether it stays luxated.

Treatment Options

Medical Management

Mild cases may be managed with:

  • Weight management
  • Activity modification
  • Anti-inflammatory or pain medications
  • Joint supplements

However, medical management does not correct the underlying structural issue.

Surgical Treatment

Surgery is recommended for pets with:

  • Persistent or worsening lameness
  • Moderate to severe MPL (Grade II–IV)
  • Pain or progression of arthritis

The goal of surgery is to realign the knee so the patella stays in its normal position.

What Surgery Involves Medial patellar luxation repair is performed under general anesthesia. Depending on the severity, surgery may include one or more of the following:
  • Deepening the groove the patella sits in (trochlear block or wedge recession) (Trochleoplasty)
  • Realigning the attachment of the patellar tendon (Tibial Tuberosity Transposition)
  • Tightening or releasing surrounding soft tissues (Lateral Imbrication)
These procedures work together to stabilize the kneecap and improve limb function.

Incision and Suture Care Aftercare and Recovery Most pets go home the same day or within 24 hours after surgery. Your pet will be sent home with:
  • Pain medications
  • Anti-inflammatory medications
  • Antibiotic Medications
  • Detailed activity restriction and rehabilitation instructions
  • Keep the incision clean and dry
  • Prevent licking or chewing
  • An E-collar (cone) must be worn at all times when not directly supervised

  • Strict rest is required initially, with leash-only bathroom breaks
  • Gradual return to activity over several weeks
  • Physical rehabilitation and at-home exercises are strongly recommended to rebuild strength and improve outcome

The prognosis for medial patellar luxation surgery is generally excellent, especially when addressed early and followed by proper rehabilitation and weight management.

Contact a veterinarian if you notice:

  • Increased swelling, redness, or discharge at the incision
  • Persistent or worsening lameness
  • Signs of pain, lethargy, or fever
  • The incision opening or sutures coming loose

Our goal in treating medial patellar luxation is to reduce pain, improve mobility, and prevent long-term joint damage. If you have questions about MPL or whether surgery is right for your pet, please contact us, we’re happy to help guide you through the decision and recovery process.