Excessive Lateral Pressure Syndrome

Excessive Lateral Pressure Syndrome (ELPS), also known as Lateral Patellar Compression Syndrome, is a condition characterized by abnormal and excessive pressure on the lateral aspect of the patellofemoral joint. This occurs when the lateral retinaculum, a network of connective tissue on the outer side of the knee becomes tight or shortened, altering the patella’s normal tracking pattern. The result is pain, restricted movement, and in chronic cases, structural changes within the patella itself.

 

Anatomical Concept

To understand this condition, it is important to recognize that the lateral retinaculum is not a single, uniform structure. Instead, it is a composite of several tissue layers that stabilize and connect the patella laterally. It consists of three distinct layers:

1. Superficial layer (deep fascia):

This layer is not directly attached to the patella but forms the outer fascial covering.

2. Intermediate layer:

It is composed of fibers from the iliotibial band (ITB) and quadriceps aponeurosis, which blend into the lateral border of the patella.

3. Deepest layer:

Represents the joint capsule, forming the innermost stabilizing layer adjacent to the patellofemoral joint.

Together, these layers maintain the patella’s lateral stability. However, when they become excessively tight, they limit normal medial patellar glide, leading to increased compressive forces on the lateral facet of the patella.

Biomechanical Concept

In ELPS, the tight lateral retinaculum exerts constant tension on the lateral side of the patella, preventing it from aligning properly within the trochlear groove during knee motion. This abnormal pressure distribution affects not only the joint capsule but also the ITB and quadriceps mechanism, leading to:

• Increased bone strain on the lateral patella
• Inflammation of the lateral retinaculum
• Iliotibial Band Friction Syndrome (ITBFS) due to mechanical overload

Over time, the repetitive stress can cause microtrauma and bony remodeling, resulting in pain and potential degenerative changes.

 

Etiology and Contributing Factors

• Repetitive knee flexion - extension activities (e.g., running, cycling)
• Poor lower limb biomechanics (genu valgum, femoral internal rotation, or pronated foot)
• Weakness of the vastus medialis oblique (VMO)
• Post-surgical or post-traumatic fibrosis (after lateral meniscectomy, etc.)
• Chronic overuse without proper flexibility or strengthening work

Clinical Features

Patients typically present with:

• Anterior or lateral knee pain, aggravated by squatting, stair climbing, or prolonged sitting
• Limited medial patellar glide on physical examination
• Tenderness along the lateral patellar border
• Occasionally, crepitus or a sense of tightness around the patellofemoral joint

 

Clinical Diagnosis

Include key clinical tests and findings:

• Patellar Tilt Test - limited medial lift of the lateral edge of the patella
• Medial Glide Test - decreased medial translation (<1 quadrant)
• Patellar Compression Test - pain on compressing patella against femur
• Observation of lateral patellar tilt in relaxed knee extension

 

Radiological Considerations

Chronic stress on the lateral patella may progress to the formation of a vertical stress fracture or even separation of a lateral patellar fragment. It is important to differentiate this from a congenital bipartite patella, which is an anatomical variant rather than a pathological finding. In ELPS, the separated fragment typically lies at the superolateral aspect of the patella.

Magnetic Resonance Imaging (MRI) is particularly valuable for visualizing soft tissue tension, retinacular thickening, and early subchondral changes.

Differential Diagnosis

Patellofemoral Joint Related

• PatellofemoralPain Syndrome (non-specific PFPS)
• Chondromalacia patella
• Patellar instability (subluxation / recurrent dislocation)
• Trochlear dysplasia
• Bipartite patella (important because this can look like a “fragment” on imaging)
• Osteochondritis dissecans of patella

Tendinous / soft tissue

• Quadriceps tendinopathy
• Patellar tendinopathy (jumper’s knee)
• Hoffa’s fat pad impingement
• Prepatellar bursitis (housemaid’s knee)
• Lateral meniscal anterior horn pathology (can cause similar lateral joint line discomfort)

Iliotibial Band Related

• ITB friction syndrome (especially when pain is slightly more lateral and distal)
• Lateral retinaculum inflammation from other causes (trauma, post-surgery scarring)

Other joint pathology around knee

• Early patellofemoral osteoarthritis
• Synovial plica syndrome (especially lateral plica)
• Loose bodies in knee

Management Approach

Conservative Management

The initial goal of treatment is to reduce lateral compressive forces and restore patellar mobility.

• Patellofemoral joint mobilization is essential to increase medial glide and reduce lateral tension.
• Soft tissue therapy directed toward the lateral retinaculum and ITB can help release fascial restriction.
• Although taping techniques are often used for patellar tracking disorders, their effectiveness in ELPS is limited because the underlying issue is structural tightness, not malalignment alone.

Rehabilitation Focus

• Stage 1: Pain relief and mobility restoration (manual therapy, cryotherapy)
• Stage 2: Stretching of ITB and lateral retinaculum, patellar mobilizations
• Stage 3: Strengthening VMO, hip abductors, and external rotators
• Stage 4: Functional retraining - squats, step-downs, gait correction

Surgical Management

When conservative measures fail, surgical options may be considered.

• A lateral retinacular release helps relieve the excessive lateral pull and decompress the patellofemoral joint.
• In cases with a separated lateral patellar fragment, surgical excision may be required to alleviate persistent pain.