Overview
Definition:
Patellofemoral pain syndrome (PFPS) is a common musculoskeletal condition characterized by anterior knee pain, often exacerbated by activities that load the patellofemoral joint
It is typically diagnosed clinically when other causes of anterior knee pain are ruled out.
Epidemiology:
PFPS is highly prevalent in adolescents and young adults, particularly females
It accounts for a significant proportion of knee complaints in sports medicine clinics and pediatric orthopedics
Incidence rates vary, but it is estimated to affect 10-25% of adolescents participating in sports.
Clinical Significance:
PFPS can significantly impact an adolescent's quality of life, participation in physical activities, and academic performance
Early and accurate diagnosis and management are crucial to prevent chronic pain and functional limitations, making it an important topic for pediatric and sports medicine practitioners preparing for board examinations.
Clinical Presentation
Symptoms:
Pain localized to the anterior aspect of the knee
Pain that worsens with activities such as stair climbing (especially descending), squatting, running, jumping, and prolonged sitting (theater sign)
A sensation of instability or catching may be reported
A dull ache is common.
Signs:
Tenderness on palpation of the peripatellar region, particularly the medial facet of the patella
Pain reproduction with provocative maneuvers such as the patellar grind test, eccentric quadriceps contraction test, or resisted extension
Mild effusion may be present
Crepitus may be elicited with patellar movement
Assess gait for any antalgic patterns or lower limb malalignment.
Diagnostic Criteria:
There are no universally accepted, strict diagnostic criteria for PFPS
Diagnosis is primarily clinical, based on a history of anterior knee pain reproducible with specific activities and the absence of objective findings suggestive of intra-articular pathology or significant structural abnormalities on imaging
Some diagnostic algorithms emphasize ruling out other causes first.
Diagnostic Approach
History Taking:
Detailed history of pain onset (gradual vs
sudden), location, character, intensity, aggravating and relieving factors
Inquire about previous injuries, training errors, changes in activity level, and biomechanical factors (e.g., foot pronation, hip abductor weakness)
Red flags include mechanical symptoms (locking, giving way), significant trauma, fever, night pain, or weight loss, which suggest other pathologies.
Physical Examination:
Comprehensive lower extremity examination, including observation of posture and alignment (e.g., Q-angle, genu valgum/varum, foot pronation)
Palpate the patella, patellar facets, and tibial tubercle
Assess range of motion (flexion/extension), patellar mobility (glide, tilt), and stability
Test for ligamentous laxity
Evaluate quadriceps strength and flexibility, hamstring flexibility, hip abductor and external rotator strength, and ankle dorsiflexion
Perform provocative tests.
Investigations:
Radiographs (AP, lateral, and skyline/merchant views of the patellofemoral joint) are often performed to rule out structural abnormalities like osteochondral defects, fractures, or significant malalignment, though they are frequently normal in PFPS
MRI may be indicated if significant intra-articular pathology (e.g., meniscal tear, ligamentous injury) or osteochondral lesions are suspected, or if symptoms persist despite conservative management
Ultrasound can be useful for evaluating soft tissues.
Differential Diagnosis:
Osgood-Schlatter disease, Sinding-Larsen-Johansson disease, patellar tendinitis, chondromalacia patellae, plica syndrome, meniscal tears, osteochondritis dissecans, referred pain from the hip, anterior cruciate ligament (ACL) injury, Hoffa's impingement, bursitis, stress fracture.
Management
Initial Management:
Activity modification to reduce aggravating activities
Rest, ice, and pain relief
Patient education regarding the condition and the importance of adherence to a rehabilitation program
Bracing or taping may provide temporary symptomatic relief for some patients.
Medical Management:
Non-steroidal anti-inflammatory drugs (NSAIDs) may be used judiciously for short-term pain relief, but are not a primary treatment
Gradual return to activity as pain subsides
Focus on a comprehensive, progressive rehabilitation program overseen by a physical therapist.
Surgical Management:
Surgery is rarely indicated for PFPS in adolescents and is reserved for cases with persistent, debilitating pain refractory to extensive conservative treatment, or for specific structural abnormalities identified on imaging (e.g., significant chondral defects, patellar instability requiring realignment)
Arthroscopic procedures may include chondroplasty, plica resection, or lateral release, but their long-term efficacy for PFPS alone is debated.
Supportive Care:
Physical therapy is the cornerstone of management
This includes strengthening exercises focusing on the quadriceps (especially vastus medialis oblique), hip abductors, and core muscles
Stretching exercises for tight structures (hamstrings, IT band, quadriceps, gastroc-soleus)
Proprioception and neuromuscular control training
Biomechanical assessment and correction (e.g., orthotics for foot pronation).
Complications
Early Complications:
Worsening of pain with aggressive rehabilitation
Lack of adherence to treatment
Development of compensatory movement patterns.
Late Complications:
Chronic anterior knee pain
Osteoarthritis of the patellofemoral joint
Functional limitations and decreased physical activity levels
Psychological impact (e.g., anxiety, depression related to pain and activity restriction).
Prevention Strategies:
Proper warm-up and cool-down routines
Gradual progression of training intensity and duration
Addressing biomechanical abnormalities early
Strengthening of core and lower extremity musculature
Maintaining flexibility
Education on proper technique during sports and activities.
Prognosis
Factors Affecting Prognosis:
Adherence to rehabilitation program
Severity and duration of symptoms
Presence of underlying biomechanical issues
Psychological factors
Return to sport status.
Outcomes:
The prognosis for PFPS in adolescents is generally good with appropriate conservative management, with most individuals experiencing significant improvement and return to pre-injury activity levels
However, a subset of patients may experience persistent pain or recurrent symptoms
Long-term studies show variable outcomes.
Follow Up:
Regular follow-up with the treating physician or physical therapist is important to monitor progress, adjust the rehabilitation program as needed, and ensure safe return to sport
Long-term monitoring may be necessary for individuals with persistent symptoms or those returning to high-demand activities.
Key Points
Exam Focus:
Remember PFPS is a diagnosis of exclusion
Key management is conservative rehabilitation focusing on VMO, hip abductors, and core strength
Differentiate from Osgood-Schlatter and Sinding-Larsen-Johansson
Understand the role of biomechanical factors.
Clinical Pearls:
Listen to the patient’s history of pain with specific activities
The theater sign is classic
Emphasize patient education and adherence to physical therapy
Don't rush return to sport
ensure functional capacity is restored
Consider gait analysis for subtle biomechanical issues.
Common Mistakes:
Over-reliance on imaging and premature surgical intervention
Neglecting hip and core strengthening in rehabilitation
Insufficient attention to biomechanical factors like foot pronation or muscle imbalances
Inadequate patient education leading to poor adherence.