relationship between knee malalignment and qangle with age at onset of disease in 260 chondromalacia patella patients

background: chondromalacia patella is the most common cause of mechanical knee pain in young women. q angle and knee alignment are important clinical parameters for biomechanics of the patellofemoral joint. objective: to identify the prevalence of knee malalignment and to find out if there is a correlation between knee mal alignment and q angle with age at onset of disease. methods: all patients under 40 years old complaining of mechanical knee pain with positive shrug sign and normal knee radiography who were referred to amir a'lam rheumatology clinic during the period of september 2000 to september 2002 were included in this study. the patients were examined by a rheumatologist for measuring q angle and detection of knee malalignment. age at onset of disease was defined as initiation of knee pain according to the patient's history. results: the cases were 260 with 189 females. prevalence of knee mal alignment was 32.4%. the mean age at onset of disease was 22.8 ± 7.08 years. the mean age at onset in patients with knee mal alignment (21.41 ± 5.66 years) was significantly lower than the mean age at onset in those without knee malalignment (23.6 ± 7.43 years) (p= 0.002). there was a positive correlation between q angle and age at onset of disease (r=0.17,p= 0.006). conclusion: it seems reasonable to identify knee malalignment in chondromalacia patella patients and perform proper management to postpone progression of disease. there are many other factors that influence age at onset of disease, so further investigation is recommended.