Understanding Red Flags in Patellofemoral Pain

Original Editor - Carin Hunter based on the course by Claire Robertson
Top Contributors - Carin Hunter, Jess Bell and Kim Jackson

Introduction

Red flags are an important aspect of our assessments, but this often is overlooked in a patient with knee pain.

We need to know what might be a red flag for patient safety and for correct referral to the appropriate place. If there has been any trauma to the knee it is advisable to make sure the correct investigations have been carried out. This could mean imaging or special tests.

For more information on red flags please see Red Flags.

Non-Traumatic Masquerading Conditions

Osgood Schlatters

Signs and Symptoms:

• This condition is common in the 11-15 year old age group.
• It is prevalent in children participating in quadricep dominant sports, ie running, kicking and jumping
• It presents with an obvious bump at the tibial tubercle
• Pain is specific to tibial tubercle
• Inflammation and elevation of the growth plates are present in the tibial tuberosity
• An MRI to show level of inflammation can be used as confirmation but this will not change treatment plan
• Pain can worsen to a point that it can prevent any participation in sport if left untreated

Treatment:

• Education
• Activity modification - Try to eliminate the patients least favourite sport or change the playing position to a less active one to decrease load
• NSAIDS (Non-steroidal Anti-inflammatories)
• Ice Massage - This will provide symptomatic relief
• Address overload
  • Extrinsic factors
    • Load management of sport
    • Footwear
    • Landing technique
  • Intrinsic factors
    • Muscle length
    • Muscle strength

For more information, please see Osgood-Schlatters Disease

Sinding-Larsen-Johansson Disease

Sinding Larsen Johansson Syndrome (SLJS) is a juvenile osteochondrosis and traction epiphysitis affecting the extensor mechanism of the knee which disturbs the patella tendon attachment to the inferior pole of the patella. The tenderness of the inferior pole of the patella is usually accompanied by X-ray evidence of splintering of that pole. Most patients with SLJS also show a calcification at the inferior pole of the patella.

The syndrome usually appears in adolescence, during the growth spurt. It’s associated with localised pain which is worsened by exercise. Usually a localised tenderness and soft tissue swelling is observed. There is also a tightness of the surrounding muscles, the quadriceps, hamstrings and gastrocnemius in particular. This tightness usually results in inflexibilities of the knee joint, altering the stress through the patellofemoral joint.

Signs and Symptoms:

• Inflammation at the growth plate of the distal pole of the patella
• This condition is most likely to be seen during growth spurts
• Primary treatment tactics track growth for activity modification during a growth spurt
• Pain can worsen to a point that it can prevent any participation in sport

Treatment:

• Education
• Activity modification - Try to eliminate the patients least favourite sport or change the playing position to a less active one to decrease load
• NSAIDS (Non-steroidal Anti-inflammatories)
• Ice Massage - This will provide symptomatic relief
• Address overload
  • Extrinsic factors
    • Load management of sport
    • Footwear
    • Landing technique
  • Intrinsic factors
    • Muscle length
    • Muscle strength

For more information, please see Sinding-Larsen-Johansson Disease

Knee Effusion

There is no situation where a child should have a knee effusion without a cause. This should therefore always be investigated. A knee effusion can often lead to patellofemoral pain.

Possible Effusion Causes:

• Systemic autoimmune disease (eg. juvenile arthritis)
• Infective arthritis
• Osteochondritis Dissecans

Osteochondritis Dissecans/Osteochondral Defect

Osteochondritis Dissecans (OCD) is defined as an inflammatory pathology of bone and cartilage. This can result in localized necrosis and fragmentation of bone and cartilage. Cartilage and subchondral bone can break off and float in the joint. This irritates the synovium, which causes an effusion.

Osteochondritis Dissecans Treatment:

• Manage conservatively for stable lesions
• Possible debridement/knee wash out
• Possible surgical resection (resect back to a stable margin)
• Review the osteochondral defects with an MRI. Check for stability of the margins of the osteochondral defect and if the location is a weight-bearing zone.
• Monitor bone oedema around a defect. This should decrease when serially monitored.
• Physiotherapy advice: Load management
  • With a trochlear osteochondral defect, in the patellofemoral joint, avoid excessive deep loaded flexion

Autoimmune Disease Red Flags:

• Multiple joint involvement
• Joint was stiff on waking
• Fatigue

Infective Arthritis Red Flags:

• Temperature
• Recent Illness

For more information, please see Osteochondritis Dissecans and Osteochondritis Dissecans of the Knee

Slipped Capital Femoral Epiphysis

Slipped capital femoral epiphysis is not common but needs to be considered as a differential diagnosis. This condition has been known to refer to the anteromedial knee. A mild condition, with an early diagnosis has a better outcome as the condition will progress until the epiphysis is fused.

For more information, please see Slipped Capital Femoral Epiphysis

Others

Less common but more serious:

• Systemic Auto-Immune Disease
• Slipped Epiphysis
• FAI
• Leukaemia
• Metastatic Neuroblastoma
• Primary Bone Tumour
• Red Flags
• Night pain
• Weight loss
• Malaise

Posterior Cruciate Ligament Rupture

A rupture of the posterior cruciate ligament can be caused by a blow to the front of the knee. This can present with the only patient reported symptom being patellofemoral join pain. It is advised to assess all ligaments to see if surgery is necessary. Physiotherapy will often focus on Quadriceps rehabilitation.

For more information, please see PCL

Synovial Plica

A plica is a fold in the synovial membrane. They are common and are normally asymptomatic. A plica can often be palpated anteromedially, next to the superior half of the patella. Occasionally, they can get trapped into the patellofemoral joint, and can become impinged or inflamed and sore.

Diagnosis:

• Inject with local anaesthetic for symptomatic relief. If this is successful, it is a strong indication of an inflamed synovial plica.

Treatment:

• Steroid injections to decrease inflammation
• Plica resection
• Rehabilitation

Patella Tendinopathy

Tendinopathy is a failed healing response of the tendon, with haphazard proliferation of tenocytes, intracellular abnormalities in tenocytes, disruption of collagen fibers, and a subsequent increase in noncollagenous matrix.  The term tendinopathy is a generic descriptor of the clinical conditions ( both pain and pathological characteristics) associated with overuse in and around tendons.

Treatment:

• Heavy resistance loading
• Eccentric decline loading

For more information, please see Patella Tendinopathy

	Patella Tendinopathy	Patellofemoral Pain
Aggravating Factors	Being still Early morning	Being still if knee at end of range flexion
Description of Pain	Pinpoint to proximal tendon	Vague
Effect of Excercise	Pain decreases as tendon warms up	Worsens with repetitive load

Femoroacetabular Impingement

While femeroacetabular impingement is not common, it has been known to refer pain to the anteromedial knee. This can sometimes be confused with patellofemoral pain. One quick test that can be performed is the Quadrant Test. This involves flexion, adduction, internal rotation of this hip. A positive test would be that the knee pain is replicated.

For more information, please see Femoroacetabular Impingement

Assessment Tools

Load Assessment Table for Growth Tracking - Track volume of exercise in a week