Kneecap (Patella) Anatomy, Function, and Common Disorders

Structure

• Sesamoid bone embedded in quadriceps tendon.
• Articular surface (posterior): cartilage-covered, articulates with femoral trochlea (patellofemoral joint).
• Non-articular surface (anterior): subcutaneous, attachment for patellar tendon.

Functions

• Protects knee joint anteriorly.
• Increases quadriceps lever arm → efficient extension.
• Centralizes patellar tendon, prevents lateral dislocation.
• Enhances joint stability.

Common Conditions

• Patellar tendinopathy (jumper's knee): Overuse, pain at inferior pole.
• Patellofemoral pain syndrome (runner's knee): Maltracking, overload, peripatellar pain.
• Dislocation/subluxation: Usually lateral; trauma or anatomic predisposition.
• Fracture: Direct blow, fall.
• Osteoarthritis: Cartilage wear, pain, crepitus.
• Chondromalacia patellae: Cartilage softening.

Management

Conservative: RICE, PT (quad/hip strengthening, tracking correction), bracing, NSAIDs. Surgical: realignment, cartilage repair, Patellectomy (rare). Prevention: weight control, conditioning, proper footwear, warm-up.