Patella Alta: Understanding Symptoms, Complications, and Management

What is Patella Alta Symptoms?

Patella alta, characterized by an abnormally high-riding kneecap, can lead to a range of distinct symptoms primarily stemming from altered patellofemoral joint mechanics and increased instability, often manifesting as anterior knee pain and a feeling of giving way.

Understanding Patella Alta

Patella alta, Latin for "high kneecap," is a anatomical variation where the patella (kneecap) sits higher than its typical position within the trochlear groove of the femur (thigh bone). This elevated position alters the biomechanics of the patellofemoral joint, which is the articulation between the patella and the femur.

From a biomechanical perspective, a high-riding patella:

• Reduces Engagement: It decreases the contact area and engagement of the patella within the trochlear groove, particularly in early knee flexion. This reduces the mechanical stability normally provided by the bony architecture.
• Alters Lever Arm: It can impact the effective lever arm of the quadriceps muscle, potentially reducing its mechanical advantage and requiring greater force production for knee extension.
• Increases Stress: The altered tracking and reduced contact area can lead to increased stress on specific areas of the patellar cartilage, predisposing it to wear and tear.

Key Symptoms of Patella Alta

The symptoms associated with patella alta are largely a result of the altered biomechanics and the subsequent stress on the patellofemoral joint and surrounding structures. While symptom severity can vary, common presentations include:

• Anterior Knee Pain: This is the most prevalent symptom, often described as a dull ache or sharp pain around or behind the kneecap.
  • Aggravating Factors: Pain typically worsens with activities that increase patellofemoral joint compression or require deep knee flexion, such as ascending or descending stairs, squatting, kneeling, running, or prolonged sitting with bent knees ("theater sign").
  • Mechanism: The pain arises from abnormal patellar tracking, increased pressure on specific areas of the patellar cartilage, and irritation of surrounding soft tissues.
• Patellar Instability and Feeling of "Giving Way": Due to its high position, the patella has less bony constraint from the trochlear groove, especially in the initial degrees of knee flexion.
  • Subluxation: Patients may experience a sensation of the kneecap "shifting" or "slipping out of place," often laterally. This is a partial dislocation (subluxation).
  • Dislocation: In more severe cases, complete dislocation of the patella can occur, where it fully moves out of the trochlear groove, usually to the lateral side. This is often accompanied by acute pain and visible deformity.
  • Functional Impact: This instability can lead to a feeling of the knee "giving way" or buckling, particularly during activities involving pivoting, twisting, or sudden changes in direction.
• Crepitus and Clicking/Popping Sensations: Patients frequently report audible or palpable grinding, cracking, or popping sounds during knee movement.
  • Mechanism: This is often attributed to abnormal friction between the patella and the femoral trochlea as the patella tracks incorrectly, or from other soft tissue impingements. While not always painful, persistent or painful crepitus warrants investigation.
• Difficulty with Deep Knee Flexion: Activities requiring full bending of the knee, such as deep squats or kneeling, may be painful or mechanically restricted.
  • Mechanism: The high patella may not engage properly into the trochlear groove at end-range flexion, or the altered mechanics can lead to increased localized pressure.
• Quadriceps Weakness or Inhibition: Chronic pain and altered biomechanics can lead to reflexive inhibition and subsequent weakness of the quadriceps muscles, particularly the vastus medialis obliquus (VMO), which is crucial for medial patellar tracking.
• Visible Appearance: In some cases, especially when the knee is extended and relaxed, the patella may appear visibly higher on the thigh compared to a typical position.

Related Conditions and Complications

The chronic symptoms of patella alta can predispose individuals to other knee conditions:

• Patellofemoral Pain Syndrome (PFPS): Patella alta is a significant risk factor for PFPS, a common condition characterized by pain around the kneecap, often due to multifactorial issues including maltracking.
• Chondromalacia Patellae: The increased and uneven pressure on the patellar cartilage can lead to softening and degeneration of the articular cartilage, known as chondromalacia patellae.
• Recurrent Patellar Dislocation: The inherent instability increases the risk of repeated subluxations or dislocations.
• Osteoarthritis: Long-term altered mechanics and cartilage wear can accelerate the development of osteoarthritis in the patellofemoral joint.
• Increased ACL Strain: Some research suggests that patella alta may be associated with increased strain on the anterior cruciate ligament (ACL) due to altered quadriceps mechanics.

When to Seek Professional Help

If you experience persistent anterior knee pain, a feeling of instability or "giving way" in your knee, or recurrent clicking/popping sounds, it is crucial to consult a healthcare professional. An accurate diagnosis is essential for effective management and to prevent the progression of symptoms or the development of more serious conditions.

Diagnosis

Diagnosis of patella alta typically involves a thorough clinical examination, including assessment of patellar height, tracking, and stability. Imaging studies, particularly X-rays (lateral view with the knee flexed to 30 degrees, or Merchant's view for tracking), are often used to confirm the diagnosis and measure the patellar height using specific indices (e.g., Insall-Salvati ratio, Caton-Deschamps index). MRI may be used to assess cartilage health and soft tissue structures.

Management Strategies

Management of patella alta focuses on alleviating symptoms, improving patellofemoral mechanics, and preventing further complications.

• Non-Surgical Approaches: These are typically the first line of treatment and include:
  • Physical Therapy: Exercises to strengthen the quadriceps (especially VMO), hip abductors, and core muscles; stretching of tight structures (e.g., hamstrings, IT band, lateral retinaculum); and gait retraining.
  • Activity Modification: Avoiding activities that exacerbate pain.
  • Bracing or Taping: Patellar bracing or taping can help improve patellar tracking and provide support.
  • Pain Management: NSAIDs or other pain relief modalities.
• Surgical Interventions: In cases of persistent pain, significant instability, or recurrent dislocations that do not respond to conservative management, surgical options may be considered. These can include procedures to realign the patella (e.g., tibial tubercle osteotomy to lower the patella) or address soft tissue imbalances.

Conclusion

Understanding the symptoms of patella alta is critical for individuals experiencing knee pain or instability. While the condition can lead to chronic discomfort and functional limitations, early recognition and appropriate, evidence-based management strategies, often involving a comprehensive physical therapy program, can significantly improve outcomes and help individuals maintain an active and healthy lifestyle.