Summary

Patellar luxation is a common orthopedic condition in dogs, especially smaller breeds. It occurs when the kneecap (patella) slips out of its normal position. This condition can cause pain and lameness and, in severe cases, may require surgical treatment. This article explains the causes, symptoms and treatment options for patellar luxation in dogs.

Temporary dislocation of the kneecap is a common condition in many small dog breeds . Symptoms are usually not very serious but may worsen over time. The disease is divided into four different levels of severity. Although an occasional kneecap dislocation without severe symptoms does not necessarily require surgery, in some cases a surgical approach is recommended.

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Causes of patellar luxation

Miniature or toy dogs (Chihuahuas, Yorkshire Terriers, French Bulldogs, etc.) are particularly affected by this disease. The reason for this is a misalignment of the back feet . While large dogs usually have very straight hind legs, dwarf breeds have a more or less pronounced curvature of the thigh and shin bones, which often leads to arched legs. Due to the position of the leg axis, muscle tension on the patellar tendon pulls the kneecap inward, which can cause it to pop out inward.

graph LR A[Axis misalignment] --> B[O-leggedness] B --> C[Pull on patellar tendon] C --> D[Patellar luxation] E[Trauma] --> D

Medial dislocation (shift to the inside of the knee) is the most common form. Even if there is a pop out to the outside. An accident that damages the ligamentous structures can also be a cause of a patellar luxation. Recognizing Symptoms Typically, the owner notices occasional lameness (walking on 3 legs at times). Only in traumatic patellar luxation (more common in large dogs) is lameness and pain during manipulations pronounced. Sometimes the diagnosis is a chance finding.

Patellar luxation
Classification of dislocation grades 1 to 4 by an experienced veterinarian. Graphics: Jonas Lauströr

Dislocation degrees in patellar dislocation

During the examination, the severity of the sprain is divided into 4 levels:

Grade I:
The patella is in its normal position but can be pushed out of the groove by manipulation with the knee in full extension and returns to its normal, unsupported position. Clinical symptoms are rare.

Grade II:
The patella dislocates spontaneously when the knee is extended or may be pushed out of its normal position and then remains in that position. This leads to typical temporary lameness. It returns to its original position after some time or through manipulation of the knee joint. Slight deformations of the limbs, such as: B. internal rotation of the tibia can be observed. If the patella is dislocated, the foot is extended to differentiate between grade II and III.

Severe degrees requiring surgery:

Grade III:
The kneecap is permanently dislocated (immobile), but can be manually pushed back into the normal position. In the case of a unilateral dislocation, the affected foot is constantly relieved. If both sides are affected, the lameness is not as noticeable, but the steps are rather short and the knees are bent. There is pronounced internal rotation of the tibia. A poorly developed, flat rolling ridge is often noticeable.

Grade IV:
The patella is permanently dislocated and can no longer be manually pushed back into its original position. The gait is very stiff. The tibia is clearly turned inward and the crest of the coil is often flat.

Mechanism of patellar luxation

To better understand the mechanism of patellar luxation in dogs, it is important to know the anatomy of the knee joint. The knee joint is made up of three main structures: the thigh bone (femur), the shinbone (tibia), and the kneecap (patella). The kneecap is a small, flat bone that lies in a groove at the end of the femur and is held in place by tendons and ligaments.

The main function of the kneecap is to act as a lever that transmits the force of the large thigh muscle (quadriceps) to the shinbone. This allows the dog to flex and extend the knee joint, which is necessary for normal movements such as running, jumping and climbing.

A patellar luxation occurs when the kneecap slips out of its normal position in the groove on the femur. This can be done either medially (inwards) or laterally (outwards). Medial patellar luxations are more common in small dog breeds, while lateral patellar luxations are more common in larger breeds.

The mechanism of patellar luxation can be divided into four main categories:

  1. Anatomical factors : A malformation or weakness in the structures that hold the kneecap in place, such as tendons, ligaments, or bones, can cause the kneecap to slip out of position more easily.
  2. Traumatic factors : Injuries such as impacts or falls can damage the structures in the knee joint and cause patellar luxation. A sudden impact or unusual stress on the leg can cause the kneecap to slip out of its groove.
  3. Degenerative factors : Long-term wear and tear on the knee joint, such as osteoarthritis or inflammation, can affect the stability of the kneecap and increase the risk of patellar luxation.
  4. Functional factors : Uneven loads or tensions on the knee joint, such as can occur when the legs are overweight or misaligned, can cause the kneecap to be more susceptible to slipping out of position.

Patellar luxation can cause pain, swelling, and limited mobility because the normal function of the knee joint is impaired. Over time, this can lead to further damage to the knee joint, such as: B. degenerative changes or osteoarthritis.

Mechanism of a patellar luxation as an example video

Symptoms and diagnosis

The disease can usually be adequately diagnosed during the examination. Although the diagnosis can be made by palpation alone, it is advisable to take an x-ray. On the one hand, osteoarthritis can be diagnosed, which occurs when the disease has existed for a long time. On the other hand, other differential diagnoses can be ruled out and the degree of malposition can be identified. In the case of particularly severe malformations, computer tomography can be useful in order to accurately measure the bone malformation and plan any necessary bone adjustment.

Symptoms of patellar luxation in dogs

The most common signs of patellar luxation in dogs are:

  1. Lameness : The dog limps or shows difficulty walking. This can occur suddenly or worsen over time.
  2. Pain : Dogs with a patellar luxation may exhibit pain in the affected knee. They may be sensitive when the leg is touched or moved and may have difficulty standing up or lying down.
  3. Swelling : The affected knee joint may be swollen and warm, especially if the patellar luxation was caused by an injury.
  4. Irregular movements : Dogs with a patellar luxation may exhibit unusual movements, such as: B. hold the leg in a twisted position or lift and lower the leg while running.

Here is an example video of a patellar luxation in a dog:

Example of a patellar luxation

Treatment options - patellar luxation therapy

For mild dislocations ( grade 1 and possibly grade 2 ), surgery is not always necessary. If pain occurs occasionally, painkillers can be given temporarily; rest is advisable. Some dogs with mild symptoms grow old without the owner noticing the condition.

graph LR A[Patellar dislocation] --> B(Grade 1) A --> C(Grade 2) A --> D(Grade 3) A --> E(Grade 4) B --> F[Conservative therapy] C --> FC --> G[Surgical therapy] D --> GE --> G

Conservative treatment options for patellar luxation include:

1. Weight Management:

  • Importance: Being overweight increases the strain on the joints. Reducing body weight can significantly relieve symptoms of patellar luxation.
  • Implementation: This can be achieved through a combination of a low-calorie diet and regular exercise. You often work closely with the veterinarian to create an individual nutrition plan.

2. Physiotherapy:

  • Goal: Improve muscle strength, joint mobility and general fitness.
  • Methods: This includes exercises to strengthen the muscles around the knee joint, joint mobilization and special range of motion exercises.
  • Meaning: Physical therapy can help stabilize the knee and reduce the likelihood of further dislocations.

3. Hydrotherapy:

  • Concept: movement in water, such as swimming or running on an underwater treadmill.
  • Benefits: The water provides resistance and promotes muscle strengthening while relieving stress on the joints.
  • Use: Particularly useful for dogs that have difficulty with normal movement due to pain or weakness.

4. Pain management:

  • Medication: Nonsteroidal anti-inflammatory drugs (NSAIDs) can be used to relieve pain and reduce inflammation.
  • Caution: Long-term use of NSAIDs should be done under veterinary supervision to avoid side effects.

5. Supplements:

  • Dietary Supplements: Glucosamine and Chondroitin can help support joint health.
  • Effect: They help to maintain cartilage tissue and can support joint function.

6. Changes in everyday life:

  • Home Adjustments: Non-slip mats and ramps can help prevent unnecessary stress on the knee.
  • Movement management: Avoiding activities that place excessive strain on the knee joint, such as jumping or jerky movements.

7. Regular Monitoring:

  • Veterinary checks: Regular visits to the vet are important to monitor progress and adjust treatment strategy if necessary.
  • Long-term perspective: Conservative treatments often require a long-term commitment and, when used correctly, can significantly improve the dog's quality of life.

Surgical therapy

In cases of frequent pain or dislocations, severe lameness and second or higher , surgery can lead to a significant improvement in quality of life. Typically several techniques are combined during the operation - what treatment methods are there?

Surgical treatment is necessary for dogs with grade 2 patellar luxation (when conservative measures are not sufficient), grade 3, and grade 4. The operation may involve different techniques, depending on the severity of the disease and the individual characteristics of the dog:

  1. Sulcoplasty: Deepening of the sliding groove (sulcus) in the knee joint to better hold the kneecap in position.
  2. Tibial tuberosity transposition: The insertion point of the patellar tendon on the tibia is relocated to correct the direction of tension of the tendon and prevent the kneecap from popping out.
  3. Lateral fascia tightening: Tightening of the outer joint capsule and ligaments to better hold the kneecap in position.
  4. Adjustment osteotomy: Correction of axial misalignments of the bones in order to evenly distribute the load on the joint and prevent the kneecap from popping out.

The best therapies are those that surgically restore the correct relative position of the kneecap and thigh. This means that the insertion of the right patellar ligament is released using a piece of leg bone and moved either outwards or inwards so that the kneecap lies correctly over the groove in the thigh again. The sawn-off piece of the lower leg is firmly secured with a so-called tension belt (two metal pins, wire). In addition, the guide groove of the kneecap on the thigh is deepened using the wedge or block technique. This means that the kneecap is less likely to pop out of the groove. The bone cuts are secured by soft tissue fixations. The prognosis is very good. Sometimes loose nails need to be pulled out later.

Our patellar dislocation surgical method - rapid dislocation

This is a surgical procedure in which the kneecap is returned to the natural direction of movement of the kneecap. A saw cut is the first step to being able to move the ball joint. A rapid dislocation implant is then screwed into the saw cut, initially on one side. With the special quick release, the ball joint can now be moved down with millimeter precision. At the same time as the pestle, the doctor can now move the leg and control the direction of movement of the kneecap. As soon as the patella bends, optimal patellar correction is achieved.

The doctor then screws the appropriate spacers under the implant and closes the wound. The advantage of the rapid dislocation method lies not only in the stability and accuracy of the correction, but also in the possibility of subsequent corrections, even in the postoperative phase, as long as the bone has not yet grown. The following video explains rapid dislocation surgery:

Patella dislocation surgery method using Rita Leibinger Rapid

After patellar luxation surgery - aftercare and rehabilitation

After the operation, you should keep the dog on a leash six weeks . During this time, the patient should not jump, run or play so that the bone can grow properly. After this time, an X-ray check is recommended. The prognosis after this operation is generally considered to be good. However, this becomes worse with particularly severe deformities of the hind legs and with a fourth degree dislocation.

After surgery, appropriate aftercare and rehabilitation is required for the dog. The most important measures include:

  • Pain management with appropriate medications
  • Limited activity for 6 to 8 weeks to aid the healing process
  • Physiotherapy to promote joint mobility and strengthen the muscles
  • Regular check-ups with the vet to monitor healing progress

Cruciate ligament tears often occur together and can be treated in one operation.

As a rule, surgical pet insurance covers this type of procedure - please check with your insurance company beforehand.

Common Questions FAQs about Patellar Luxation in Dogs

What exactly is meant by patellar luxation in dogs?

A patellar luxation is an orthopedic condition in which the kneecap (patella) slips out of its normal position in the knee joint. This can lead to pain, lameness and long-term joint problems. It is particularly common in small and toy breeds, but can also occur in larger dogs.

How long does a luxating patella take to heal?

After surgery, dogs should have limited activity and be kept on a leash for six to eight weeks. Pain management, physical therapy, and regular veterinary check-ups are also important for successful rehabilitation.

How does a patellar luxation occur?

The main causes of patellar luxation in dogs are axial misalignment, bow-leggedness, pull on the patellar tendon, and trauma. Miniature or toy dogs such as Chihuahuas, Yorkshire Terriers and French Bulldogs are particularly susceptible to this condition due to misalignment of their hind legs.

What does a patellar luxation feel like?

Patellar luxation in dogs can cause different sensations and symptoms depending on the severity of the condition.
In general, dogs may experience pain, discomfort, and lameness when they experience a patellar luxation. In milder cases (grades 1 and 2), the lameness may be intermittent and cause little pain. In such cases, the dogs can lead relatively normal lives despite the disease. However, in more severe cases (grades 3 and 4), patellar luxation can cause increased pain, permanent lameness, and limited mobility. These dogs may experience significant discomfort and their quality of life may be affected. In such cases, surgical treatment is usually necessary to relieve pain and restore normal function to the knee joint.

How is patellar luxation in dogs diagnosed?

Diagnosis is usually made through a combination of clinical examination and imaging techniques. The veterinarian will check the stability of the kneecap, observe the dog's gait, and may take x-rays to assess the condition of the knee joint.

Are there different degrees of patellar luxation?

Yes, patellar luxation is divided into four grades:
Grade I: The kneecap occasionally dislocates, but can be easily reset.
Grade II: More frequent dislocations;
however, the kneecap does not remain permanently out of position. Grade III: The kneecap usually remains out of its normal position, but can be repositioned manually.
Grade IV: The kneecap is permanently dislocated and can no longer be manually moved into the correct position.

How is the treatment carried out depending on the degree of patellar luxation?

Treatment depends on the severity of the dislocation. For mild cases (Grades I and II), non-surgical measures such as physical therapy, weight management, and anti-inflammatory medications may be sufficient. In more severe cases (grades III and IV), surgical correction is often necessary to stabilize the kneecap and improve knee joint function.

Can certain breeds be more prone to patellar luxation?

Yes, some small and toy breeds such as Yorkshire Terriers, Poodles and Chihuahuas are genetically more susceptible to this condition. But larger breeds can also be affected.

Is a full recovery possible from a patellar luxation?

In many cases, complete recovery is possible, especially if the condition is detected and treated early. Success depends on several factors, including the severity of the dislocation, the dog's health, and the treatment method chosen.

Prognosis and prevention

The prognosis for dogs with patellar luxation is generally good, especially if the condition is detected and treated early. However, in dogs with severe deformities or grade 4 patellar luxation, the prognosis may be less favorable.

To reduce the risk of patellar luxation in dogs, breeders should be careful to use only healthy animals with good leg and knee anatomy for breeding. Additionally, the following measures can help minimize the risk of patellar luxation in dogs:

  • Avoiding Obesity: A proper diet and regular exercise can help your dog maintain his ideal weight, thereby reducing stress on his joints.
  • Regular veterinary check-ups: Early detection of signs of patellar luxation allows for timely treatment and potentially prevents more serious problems.
  • Appropriate exercise and training: Dogs prone to patellar luxation may need to be protected from extreme stress or jumping to reduce the risk of dislocation.

It is important to note that some dogs may develop patellar luxation despite all precautions. In such cases, it is crucial to carefully follow your veterinarian's instructions regarding treatment and aftercare to provide your dog with the best possible prognosis.

In conclusion, patellar luxation in dogs is a common orthopedic condition that requires timely diagnosis and treatment. Through regular veterinary visits, a healthy lifestyle and appropriate preventative measures, dog owners can help reduce the risk of patellar luxation in their dogs and maintain the quality of life of their four-legged friends.

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