summary Idiopathic chondromalacia patellae is a condition characterized by idiopathic articular changes of the patella leading to anterior knee pain. Diagnosis is clinical with a history of anterior knee pain made worse with squatting, prolonged sitting or ascending stairs and pain on patellar compression in knee extension. Treatment is generally nonoperative with resting, ice, activity modifications and physical therapy to focus on hamstring, quadriceps and core strengthening. Epidemiology Demographics most common occurs in adolescents and young adults women > men Etiology Pathophysiology pain generator is not clearly understood and multi-factorial may result from roughening or damage to the undersurface cartilage of the patella numerous factors have been proposed including limb malaligment muscle weakness chondral lesions patella maltracking patella maltracking can create narrow contact pressure points and further attenuate pain. elevated contact pressures between patella and femoral groove are associated with anterior knee pain Associated conditions miserable malalignment syndrome a term coined for anatomic characteristics that lead to an increased Q angle and an exacerbation of patellofemoral dysplasia. They include femoral anteversion genu valgum external tibial torsion / pronated feet Anatomy Patellofemoral joint articulation between patella and intracondylar groove of femur Pain receptors of the knee subchondral bone has weak potential to generate pain signals anterior fat pad and joint capsule have highest potential for pain signals Classification Outerbridge MRI Classification of Chondromalacia Grade 0 Normal Cartilage Grade I Surface intact and heterogenous; high signal intensity Grade II Fissures and fragmentation extending down to the articular surface Grade III Partial thickness defect, with focal ulceration Grade IV Exposed subchondral bone Presentation Symptoms diffuse pain in the peripatellar or retropatellar area of the knee (major symptom) insidious onset and typically vague in nature aggravated by specific daily activities including climbing or descending stairs prolonged sitting with knee bent (known as theatre pain) squatting or kneeling always consider the physical, mental and social elements of knee pain Physical exam quadricep muscle atrophy signs of patella maltracking increased femoral anteversion or tibial external rotation lateral subluxation of patella or loss of medial patellar mobility positive patellar apprehension test palpable crepitus pain with compression of patella with knee range of motion or resisted knee extension Imaging Radiographs recommended views AP, lateral and notch radiographs of knee findings may see chondrosis on xray shallow sulcus, patella alta/baja, or lateral patella tilt CT scan indications patellofemoral alignment fracture findings trochlear geometry TT-TG distance torsion of the limb MRI indications best modality to assess articular cartilage views T2 best sequence to assess cartilage abnormal cartilage is usually of high signal compared to normal cartilage Differential Quadriceps or patellar tendinitis Saphenous neuroma Post-operative neuromas Treatment Nonoperative rest, rehab, and NSAIDS indications mainstay of treatment and should be done for a minimum of one year technique NSAIDS are more effective than steroids activity modification rehabilitation with emphasis on vastus medialis obiquus strengthening core strengthening closed chain short arc quadriceps exercises strengthening of hip external rotators Operative arthroscopic debridement indications Outerbridge grade 2-3 chondromalacia patellofemoral joint techniques mechanical debridement radiofrequency debridment lateral retinacular release indications tight lateral retinacular capsule, loose medial capsule and lateral patellar tilt techniques open arthrotomy arthroscopy patellar realignment surgery indications severe symptoms that have failed to improve with extensive physical therapy techniques Maquet (anterior tubercle elevation) only elevate 1 cm or else risk of skin necrosis Fulkerson (anterior-medialization) indications (controversial) increased Q angle patellar instability contraindications superior medial arthrosis (scope before you perform the surgery) skeletal immaturity Elmslie-Trillat osteotomy MPFL reconstruction