Patellar dislocation occurs when the kneecap (patella) slips out of its normal position in the patellofemoral groove, usually shifting to the outside of the knee. This can result in intense pain, swelling, and a loss of stability in the knee joint. While it’s a common injury among athletes and individuals involved in high-impact activities, it can happen to anyone due to trauma, structural issues, or underlying conditions.
In this blog post, we’ll explore what patellar dislocation is, its causes, symptoms, and treatment options, as well as what to expect during recovery.
What is Patellar Dislocation?
The patella is a small, flat bone located at the front of the knee that sits within the patellofemoral groove of the femur (thigh bone). The patella plays a crucial role in the knee’s mechanics, aiding the quadriceps muscle in extending the knee. Patellar dislocation happens when the kneecap moves out of this groove, most often shifting laterally (to the outer side of the knee).
In some cases, the dislocated kneecap can pop back into place on its own, but it often requires medical intervention to realign the patella and assess any damage to the surrounding tissues, ligaments, or cartilage.
Causes of Patellar Dislocation
Patellar dislocation can result from a variety of factors, including traumatic injury, congenital abnormalities, or repetitive stress on the knee joint. Common causes include:
1. Trauma or Direct Impact
A sudden blow or direct impact to the knee, such as during a fall or collision in sports, can force the kneecap out of its normal position. This is one of the most frequent causes of patellar dislocation, particularly in contact sports like football, soccer, and basketball.
2. Sudden Twisting Movements
Activities that involve rapid twisting or pivoting motions can lead to a dislocation of the kneecap. This often happens when the foot is planted while the knee is twisted or turned sharply, a common scenario in sports like tennis or gymnastics.
3. Weak or Imbalanced Muscles
Weakness in the muscles around the knee, particularly the quadriceps, can cause improper tracking of the patella. When the muscles aren’t strong enough to keep the kneecap in place, it can shift out of the groove more easily.
4. Structural Abnormalities
Some individuals have anatomical factors that increase the likelihood of patellar dislocation. These may include:
- Shallow Patellofemoral Groove: If the groove where the kneecap sits is too shallow, the patella is more prone to dislocation.
- High-Riding Patella (Patella Alta): In some people, the kneecap sits higher than usual, making it more unstable and likely to dislocate.
- Ligament Laxity: Loose ligaments around the knee joint can make it easier for the patella to shift out of place.
5. Repetitive Stress
Over time, repetitive stress on the knee from activities like running, jumping, or kneeling can weaken the surrounding structures and lead to patellar instability, increasing the risk of dislocation.
Symptoms of Patellar Dislocation
The symptoms of patellar dislocation are typically immediate and severe, making it easy to identify the injury. Common symptoms include:
- Sudden Intense Pain: Dislocation is usually accompanied by sharp pain in the front of the knee.
- Swelling: The knee may swell quickly after the injury, due to damage to the surrounding tissues and the buildup of fluid.
- Visible Deformity: The kneecap will appear out of place, usually on the outer side of the knee.
- Difficulty Moving the Knee: Bending or straightening the knee can be extremely painful, and there may be a sensation of the knee giving way.
- Instability: The knee may feel unstable or unable to support weight, especially after multiple dislocations.
In cases where the kneecap relocates on its own, there may still be lingering pain, swelling, and a sensation of weakness in the knee.
Diagnosis of Patellar Dislocation
If you suspect a patellar dislocation, it’s important to seek medical attention immediately. A healthcare provider will perform a physical examination and may use imaging tests to confirm the diagnosis and assess the extent of the damage. Diagnostic tools may include:
- X-rays: X-rays help determine the position of the patella and rule out any fractures or other bone-related injuries.
- MRI (Magnetic Resonance Imaging): An MRI provides a detailed view of the soft tissues around the knee, including the ligaments, tendons, and cartilage, helping to identify any tears or damage caused by the dislocation.
- CT Scan: In some cases, a CT scan may be used to assess bone structure and alignment, especially if there are concerns about the shape of the patellofemoral groove.
Treatment Options for Patellar Dislocation
The treatment for patellar dislocation depends on the severity of the injury, whether the kneecap has relocated, and the extent of damage to the surrounding tissues. Treatment options range from conservative approaches to surgical intervention.
1. Non-Surgical Treatment
In many cases, especially for first-time dislocations, non-surgical treatments are effective in restoring stability and function to the knee. These treatments include:
Reduction
Reduction is the process of manually repositioning the kneecap back into its proper place. A healthcare provider will perform this procedure, often using gentle manipulation while the patient is under local anesthesia or sedation.
Immobilization
After the kneecap is realigned, the knee may be immobilized with a brace or splint to allow the damaged tissues to heal and prevent further dislocation. Immobilization usually lasts for a few weeks, during which time the knee is kept in a straight position.
Physical Therapy
Physical therapy is an essential part of the recovery process. A physical therapist will design a rehabilitation program to strengthen the muscles around the knee, particularly the quadriceps and hamstrings, and improve flexibility. Therapy also focuses on improving balance and alignment to prevent future dislocations.
- Benefits: Strengthens muscles, restores range of motion, and reduces the risk of re-injury.
Medications
Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can help reduce pain and inflammation in the knee during the healing process.
2. Surgical Treatment
Surgery may be necessary if:
- The dislocation caused significant damage to the ligaments, tendons, or cartilage.
- The kneecap frequently dislocates (recurrent dislocation).
- Structural abnormalities are contributing to repeated dislocations.
Common surgical procedures for patellar dislocation include:
Medial Patellofemoral Ligament (MPFL) Reconstruction
If the medial patellofemoral ligament (MPFL) is torn or weakened due to the dislocation, it can be reconstructed using a tendon graft. This ligament plays a key role in keeping the kneecap aligned, and reconstructing it helps prevent future dislocations.
Lateral Release
In cases where the patella is being pulled too far to the outside of the knee, a lateral release procedure may be performed. This involves cutting the tight lateral ligaments that are causing the misalignment.
Tibial Tubercle Transfer
This procedure involves repositioning the attachment of the patellar tendon on the shinbone (tibial tubercle) to improve the alignment of the kneecap. It’s commonly performed for individuals with recurrent dislocations or structural abnormalities.
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Recovery After Patellar Dislocation
The recovery process after a patellar dislocation depends on whether the treatment was surgical or non-surgical. Here’s what to expect:
1. Non-Surgical Recovery
- Immobilization: The knee is typically immobilized for 2 to 6 weeks to allow the soft tissues to heal.
- Physical Therapy: Physical therapy begins after the immobilization period and focuses on gradually restoring range of motion, building strength, and preventing further instability.
- Return to Activity: Most patients can return to normal activities within 6 to 8 weeks, but high-impact sports may require a longer recovery period.
2. Surgical Recovery
- Post-Surgery Rest: After surgery, patients may need to use crutches and wear a knee brace to limit movement and protect the knee while it heals.
- Physical Therapy: Rehabilitation is critical after surgery and involves a structured program to restore knee function and prevent re-injury. Recovery times vary based on the type of surgery, but most patients return to full activity within 3 to 6 months.
- Return to Sports: Athletes can typically return to their sport 4 to 6 months after surgery, depending on their progress and the type of surgery performed.
Preventing Patellar Dislocation
To reduce the risk of patellar dislocation or recurrence, consider the following preventive measures:
- Strengthen the Muscles: Focus on exercises that strengthen the quadriceps, hamstrings, and hip muscles to improve knee stability.
- Stretch Regularly: Maintaining flexibility in the muscles around the knee can help reduce tension and improve the alignment of the kneecap.
- Use Proper Technique: Athletes should pay attention to proper form and technique during sports, especially those involving jumping, twisting, or pivoting.
- Wear Knee Braces: For individuals prone to patellar dislocation, wearing a knee brace during physical activities can help provide support and prevent further injury.
Conclusion
Patellar dislocation is a painful and debilitating injury that can lead to long-term knee instability if left untreated. Whether caused by trauma, muscle weakness, or structural issues, timely treatment is essential to realign the kneecap, restore knee function, and prevent future dislocations. With the right combination of treatment—whether non-surgical or surgical—and a dedicated rehabilitation program, most patients can expect a full recovery and return to their normal activities.
If you’ve experienced a patellar dislocation or are dealing with chronic knee instability, consult with an orthopedic specialist to determine the best treatment options for your specific condition.
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FAQs
Recovery times vary depending on the severity of the dislocation and whether surgery is required. Non-surgical recovery typically takes 6 to 8 weeks, while surgical recovery can take 3 to 6 months.
Yes, many first-time dislocations can heal without surgery, especially if the kneecap is realigned promptly and followed by physical therapy. However, recurrent dislocations may require surgical intervention.
Strengthening the muscles around the knee, maintaining flexibility, and using proper technique during physical activities can help prevent future dislocations. Wearing a knee brace during high-impact activities may also provide added support.
Dr. Benoit is an assistant professor of surgery at the Université de Montréal and practices at the CIUSSS Nord-de-l’île de Montréal. He completed his medical degree at Université Laval in Quebec City in 2001 and did his orthopedic residency at the Université de Montreal, where he was on the Dean’s honour list. Following his residency, he completed two additional years of fellowship training; the first year in Geneva, Switzerland and the second year in Ottawa, Canada.
