PFPS is usually an overuse injury characterised by inflammation of the patello-femoral joint, caused by a new activity/an increase in intensity or load of activity (e.g. running), supporting muscle weakness, or prolonged kneeling.
Clinical features
Diffuse, achey anterior knee pain that is often posterior to the patella
Exacerbated by use - walking/running/climbing staris/kneeling
Examination:
Squatting reproduces anterior knee pain
Pain on palpation of the patellar edges
Osgood-Schlatter’s disease
Pathophysiology
An apophysitis - inflammation of the patellar ligament at the tibial tuberosity affecting the knee’s extensor mechanism
Clinical features
Patients are usually 10-16 years old, boys > girls
Gradually onset, progressive knee pain which starts during adolescence
Pain is worst over the tibial tuberosity
Exacerbated by kneeling or activity - worse after sport/walking etc, and relieved by rest
Examination
Tenderness on palpation of the tibial tuberosity, which may be swollen
Pain is reproduced on knee extension against resistance
Management
Conservative, analgesia, physiotherapy
Knee Bursitis
Prepatellar bursitis
Symptoms - pain at the front of the knee, with associated anterior knee swelling/history of trauma
Examination - warm, fluctuant swelling over the patella, may be tender
May be evidence of infection - fever, SIRS, cellulitis
Management - bursal aspiration - can relieve symptoms, and be sent for MCS if infection is suspected
Infrapatellar bursitis
Symptoms - anterior knee pain, often a history of prolonged kneeling (e.g. at work)
Examination - tenderness along the patellar tendon makes it difficult to differentiate from patellar tendonitis
Patellar Tendonitis
Pathophysiology
Overuse tendinopathy of the patellar tendon commonly associated with jumping sports - basketball, box-jumps etc.
Clinical features
Anterior knee pain which is exacerbated by activity - e.g. running, jumping, walking (esp. downhill where quadriceps are loaded)
Examination
Tenderness along the course of the patellar tendon
Reproducible pain on extension of the knee against resistance
Osteochondritis dissecans
Pathology
Reduced blood flow to an area of subchondral bone results in ischaemic necrosis.
The affected ‘dead’ bone subsequently breaks loose and causes pain/restricted ROM of the joint
The cause is unknown but can be triggered after an injury, or repeated high-impact activities such as running.
Clinical features
Knee pain/aching which is worse with activity
The knee can ‘lock’
Investigations
X-ray: loss of the sharp cortical line of the articular surface, and the presence of calcified loose bodies (dead bone fragments).
Iliotibial band syndrome
Pathophysiology
An overuse tendinopathy commonly triggered by activities involving repetitive knee flexion and extension, such as running or cycling.
Clinical Features
Lateral knee tenderness, most often just proximal to the joint line
Baker’s cyst
Pathophysiology
A distension of the gastrocnemius-semimembranosus bursa in the popliteal fossa
Can be idiopathic, or secondary to underlying joint disorders (osteoarthritis, meniscal injury etc.)
Clinical Features
A swelling behind the knee, often asymptomatic, sometimes can cause vague, posterior knee pain
Examination
A smooth, fluctuant bulge in the medial popliteal fossa, more prominent on standing
Complications: Ruptured baker’s cyst - a sudden pop, followed by pain, erythema and lower limb swelling
