Austin Patellar Instability Doctor

What is patellar (kneecap) instability?

At the base of your thigh bone, also known as the femur bone, there is a slight V-shaped notch called the femoral groove, also known as the trochlear groove, where your patella bone (kneecap) normally rests. The patellar tendon attaches the kneecap to the shin bone (tibia), allowing smooth movement as the joint bends and straightens, which is essential for proper knee bends. During normal motion, the kneecap moves up and down within this groove, enabling you to sit, stand, walk, run, and move with ease.

Patellar instability occurs when the kneecap moves out of its normal position in the trochlear groove. This displacement can range from partial slipping (subluxation) to a complete patellar dislocation, often caused by traumatic injury, ligamentous laxity, tight ligaments, or anatomical abnormalities such as trochlear dysplasia (an anatomical defect) or patella alta. The medial patellofemoral ligament (MPFL), which attaches near the medial epicondyle and adductor tubercle on the femur, plays a crucial role in stabilizing the kneecap and preventing excessive lateral translation. When this ligament is damaged or lax, the risk of patellar instability increases, which can eventually lead to patellofemoral arthritis.

This condition commonly occurs in young athletes and individuals with an increased Q angle, genu valgum, or those affected by connective tissue disorders like Ehlers-Danlos syndrome. It may also be associated with the so-called miserable malalignment syndrome, involving femoral anteversion, genu valgum, and external tibial torsion, which together increase lateral forces on the patella and contribute to patellofemoral instability.

Understanding the anatomy and biomechanics behind patellar kneecap instability is essential for effective diagnosis and treatment by a fellowship-trained Austin patellar instability doctor, which may range from nonoperative management, including physical therapy and bracing, to surgical correction, such as MPFL reconstruction or tibial tubercle transfer in chronic patellar instability cases, often performed by surgeons specializing in knee sports medicine.

What causes patellar (kneecap) instability?

Patellofemoral instability occurs when the kneecap moves abnormally out of its normal position in the femoral groove, often due to a combination of factors affecting the joint’s stability, including abnormal tracking and damage to the underlying soft structures. Patellar instability can result from direct knee injuries, non-contact trauma, or abnormalities in key stabilizing structures such as the medial patellofemoral ligament (MPFL), patellar tendon, and other soft tissue restraints, which include thick fibrous material and nerves and blood vessels that may be affected. The MPFL, which originates near the femoral origin between the medial epicondyle and adductor tubercle, is the primary ligament preventing excessive lateral translation of the patella and helping to avoid dislocation. Damage or laxity in this ligament is a common cause of patellar instability and can lead to knee recurrent dislocations and patellofemoral arthritis that occurs over time.

In children and adolescents, because their patellofemoral joint is still developing and may have congenital abnormalities, even minor trauma like a knee-to-knee collision can cause the kneecap to slip partially or completely (subluxation or complete dislocation) out of its groove, leading to instability. Most patients with patellar instability often report a history of acute first-time dislocation or recurrent instability episodes, sometimes accompanied by severe pain, swelling, and visible deformity and loss of function. Even partial paralysis or numbness may occur due to pressure on the nerves and blood vessels during dislocation events.

Other important causes and risk factors include:

• Direct knee tear or trauma to the joint, including impact on the lateral side or a twisting injury with the knee extended and foot planted.
• Anatomical abnormalities, such as a shallow or flattened trochlear groove (trochlear dysplasia), fail to provide adequate bony constraint.
• Patella alta, where the patella sits higher than normal, prevents proper engagement with the femoral groove and increases the risk of patellar dislocation.
• An increased Q angle caused by conditions like genu valgum (knock knees), femoral anteversion, and external tibial torsion, collectively known as miserable malalignment syndrome, increases lateral forces on the patella and can be associated with an abnormal Q angle.
• Weakness or poor activation of the vastus medialis oblique muscle combined with overactivity of the vastus lateralis, leading to improper muscle balance that destabilizes the patella and the quadriceps mechanism.
• Ligamentous laxity or tightness in soft tissue restraints, which can be congenital or due to connective tissue disorders such as Ehlers-Danlos syndrome.
• Previous knee injuries, including ACL tears, may alter knee biomechanics and contribute to chronic patellar instability and damage the underlying soft structures.
• Abrupt changes in direction during activities with the foot firmly planted, causing the kneecap to slip laterally out of the groove, leading to partially subluxation or completely dislocation and increasing the risk of further damage.

Understanding these causes, including the role of the medial patellofemoral ligament and the importance of the lateral edge and anterior border of the trochlear groove, is essential for diagnosing and managing patellar instability effectively.

Nonoperative treatment with physical therapy focusing on strengthening the quadriceps, especially the vastus medialis oblique, and addressing biomechanical factors such as fallen arches or flat feet through stretching movements is typically reserved for first-time dislocations, while surgery such as MPFL reconstruction, patellar realignment surgery, including proximal re-alignment procedures and distal re-alignment procedures, or lateral retinacular release, may be necessary for recurrent or chronic instability.

Epidemiology of Patellar (Kneecap) Instability

Patellar instability is a relatively common knee condition, accounting for approximately 3% of all knee injuries. The incidence in the general population is about 5.8 per 100,000 individuals annually, with a higher prevalence among young people, especially those in their second and third decades of life. Adolescents, particularly females aged 10 to 17 years, are at increased risk, with female adolescent athletes showing a higher predilection for this condition.

Patients under the age of 16 tend to experience higher recurrence rates following an initial patellar dislocation, with recurrence rates after conservative treatment ranging from 15% to 44%. Moreover, those with a history of two or more dislocations face a 50% chance of further recurrent episodes. This higher risk in younger patients highlights the importance of early diagnosis through diagnostic tests and appropriate management to prevent chronic instability and its associated complications, such as patellofemoral arthritis that occurs over time and damage to the articular cartilage.

Understanding these epidemiological factors is crucial for clinicians to identify at-risk populations and tailor preventive and therapeutic strategies accordingly.

What are the symptoms of patellar instability?

Symptoms of knee instability may include:

• Stiff knee and knee pain, often worsened by activities that involve the front of the knee
• Pain around the medial border of the kneecap or patellar tendon attaches at the inferior pole
• Swelling of the patellofemoral joint, which may indicate inflammation where patellofemoral arthritis occurs
• Knee extended position discomfort or difficulty bending
• Kneecap slips partially, “cracking,” or passive patellar translation with movement, reflecting that the patella moves abnormally within the trochlear groove
• Feeling your knee buckle or being unable to carry your weight, often related to weak quadriceps muscles failing to properly hold the patella
• Feeling your knee catch or lock with movement (mechanical symptoms)
• Visible deformity if completely dislocated or a first-time patellar dislocation

Additional AI insights reveal that early recognition of these symptoms, combined with a detailed medical history and physical examination, improves diagnosis accuracy. Passive patellar translation assessment during the exam by your Austin patellar instability specialist helps detect excessive lateral movement of the patella, a key indicator of patellar instability. Prompt diagnosis and management can prevent chronic patellar instability and subsequent complications such as increased patellofemoral contact pressures and cartilage damage.

How is patellar instability diagnosed by an Austin Patellar Instability Doctor?

If you are experiencing symptoms of patellar instability, such as knee pain, swelling, or a sensation that your kneecap slips out of place on the inner and outer sides, an evaluation by an experienced surgeon is essential to determine the cause. Diagnosing patellar dislocation and recurrent instability begins with a thorough review of your medical history, including any previous episodes of patellar dislocation or subluxation.

During the physical examination, your specialist in Austin will assess for excessive passive patellar translation and perform maneuvers to evaluate knee stability, including checking how the patella engages within the trochlear groove during knee movement and whether it is properly realigned. The Austin patellar instability surgeon will also measure patellofemoral contact pressures and evaluate muscle strength, particularly focusing on the vastus medialis oblique and other thigh muscles that contribute to knee stability, which is crucial for patients with an active lifestyle or active individuals involved in sports.

Imaging studies play a crucial role in confirming the diagnosis and identifying underlying anatomical factors contributing to patellar instability. Standard X-rays help visualize the position of the patella relative to the femoral groove and detect any osteochondral fractures or loose bodies within the joint.

MRI scans provide detailed information about soft tissue structures, including the medial patellofemoral ligament, cartilage damage, and the presence of any ligamentous laxity that may contribute to chronic patellar instability. In some cases, CT scans may be used to assess bony alignment, measure the tibial tubercle to trochlear groove (TT-TG) distance, and evaluate the shape of the patella and trochlear groove, which is important in surgical planning.

Early and accurate diagnosis of patellar instability is vital to prevent recurrent instability episodes and potential long-term complications such as increased patellofemoral contact pressures, cartilage wear, and to optimize the healing process.

How is patellar instability treated?

Patellar instability can be treated via both nonsurgical and surgical treatment options. Depending on the severity of the dislocated kneecap, treatment will vary. If the kneecap is fully dislocated, treatment will involve moving the kneecap back to its correct position on the same day in a clinical setting. This process, known as reduction, can sometimes happen naturally, on its own. If the kneecap is unable to naturally fall back into the femoral trochlear groove, the doctor may encourage the process by gently and carefully pressing the kneecap into place, often while the patient is in a sitting position to facilitate the patella hold and proper alignment.

For partial dislocations, conservative or nonoperative treatment may include:

• Knee brace to stabilize the knee joint
• Crutches to reduce weight and protect the injured knee
• Physical therapy guided by a physical therapist to improve muscle strength and retrain the vastus medialis and anterior thigh muscles

When complete dislocation occurs, the kneecap often becomes damaged and worn. This leads to a “loose” kneecap that no longer fits as securely in the femoral groove as it did before the patellar dislocation. Because of this, even after the kneecap is repositioned back into place, patella dislocation may occur again. Your doctor may recommend that you engage in exercise routines that can help strengthen your leg muscles and prevent recurrent instability, especially focusing on restoring a normal pattern of muscle activation.

Here at our practice, whenever possible, we aim to first recommend nonsurgical treatments to help restore mobility, alleviate pain, and prevent the progression of damage that could lead to the need for hip replacements or other invasive procedures. However, for chronic patellar instability, we specialize in and offer surgical treatment options such as arthroscopy and open surgery to help restore knee function. Platelet-rich plasma therapy may also be used to help promote healing, alleviate pain, and enhance recovery time.

Early intervention and appropriate treatment choice are essential to reduce the risk of complications such as increased patellofemoral contact pressures, cartilage damage, and numbness or even partial sensory changes.

Nonsurgical treatment and rehabilitation for patellar instability

Nonoperative treatment is often the first line of management for patients experiencing patellar kneecap instability, especially following a first-time dislocation without significant bone injury or loose bodies. This approach focuses on restoring knee stability, reducing pain, and preventing recurrent dislocations through conservative measures.

Key components of nonoperative treatment include:

• Physical Therapy: A tailored rehabilitation program emphasizes strengthening the quadriceps muscles, particularly the vastus medialis oblique (VMO), which plays a critical role in stabilizing the patella and preventing excessive lateral translation. Exercises may include quad sets, straight leg raises, clamshells, and shallow squats. Core and hip muscle strengthening are also important to improve overall lower limb alignment and biomechanics.
• Knee Bracing: Use of a knee brace or patellar stabilizing sleeve helps support the knee joint during activities, providing external stabilization to the patella and increasing patient confidence during movement.
• Activity Modification: Patients are advised to avoid activities that place excessive stress on the knee or involve abrupt twisting motions until adequate strength and stability are regained.
• Pain Management: Nonsteroidal anti-inflammatory drugs (NSAIDs) may be used to control pain and inflammation during the acute phase.

This comprehensive nonoperative approach aims to improve muscle balance, enhance patellar tracking within the femoral groove, and reduce the risk of recurrent patellofemoral instability. Close monitoring by a healthcare professional ensures that patients progress safely through rehabilitation and helps identify those who may require surgical intervention if instability persists.

When it’s time to ask for an Austin patellar instability doctor’s help for patellofemoral instability

If you experience symptoms such as persistent knee pain, frequent episodes where the kneecap slips or feels unstable, swelling in the joint, or difficulty bearing weight on the leg bone, it is important to seek medical attention promptly. Early evaluation by a healthcare professional can help diagnose patellofemoral instability accurately and determine the most appropriate treatment plan.

Consulting a patellar instability specialist is especially crucial if you have had a first-time patellar dislocation or recurrent instability episodes despite nonoperative treatment. Signs such as excessive lateral translation of the patella during physical examination or a positive apprehension test indicate the need for further assessment and possible surgical intervention by a fellowship-trained Austin patellar instability doctor.

Medical evaluation often includes a detailed medical history, physical examination focusing on passive patellar translation, and imaging studies like X-rays, MRI, or CT scans to assess the alignment of the femoral groove, tibial tubercle, and to identify any loose body or cartilage damage. Early diagnosis and management can prevent chronic patellar instability and reduce patellofemoral contact pressures that contribute to long-term joint degeneration.

Nonoperative treatment, including physical therapy to strengthen the vastus medialis oblique and other thigh muscles, knee bracing, and activity modification, is typically the first step for first-time dislocations. However, if symptoms persist or recur, operative treatment such as medial patellofemoral ligament reconstruction (MPFL) may be necessary to restore stability. MPFL reconstruction is a surgical procedure performed under spinal or general anesthesia that repairs or replaces the damaged ligament on the inside or medial side of the knee to prevent excessive lateral translation of the patella.

In summary, seek a doctor’s help when experiencing:

• Recurrent patellar dislocations or subluxations
• Persistent knee instability or pain
• Difficulty walking or bearing weight on the affected leg bone
• Visible deformity or swelling around the joint

Timely medical intervention ensures proper care, whether through nonoperative treatment or surgical treatment, to restore knee function and prevent complications associated with chronic patellar instability.

Schedule a Consultation With a Patellar Instability Doctor in Austin

If you are experiencing symptoms of patellar instability, such as excessive lateral translation or passive lateral translation results during physical examination, consulting with a patellar instability specialist in Austin, TX, is an essential step towards accurate diagnosis and effective treatment.

M. Tyrrell Burrus, MD, an experienced fellowship-trained surgeon, specializes in managing patellofemoral instability using both nonoperative treatment and MPFL reconstruction and surgical treatment when necessary. Early intervention for patellofemoral instability means you can prevent chronic patellar instability and reduce the risk of complications like increased patellofemoral contact pressures and cartilage damage.

Whether your condition requires conservative care with a knee brace and physical therapy or advanced surgical options, including medial patellofemoral ligament reconstruction or lateral release procedures, Dr. Burrus provides personalized, high-quality, and holistic care tailored to your needs. The femoral groove and the bony section of the tibial tubercle alignment will be carefully evaluated the same day to ensure optimal outcomes.

Call (512) 324-9170 or fill out the form on this page to schedule an appointment and take the first step toward restoring your knee joint stability and function.