Position of the patella among emirati adult knees. Is insall-salvati ratio applicable to middle-easterners?

Background: Abnormal patellar height is associated with anterior knee pain and several conditions that affect the patellofemoral joint. The aim of this study was to 1) report the incidence of patella alta and patella baja and 2) investigate whether the normal limits of the Insall-Salvati ratio is applicable in adult Middle-Easterners. Methods: A radiographic review of the lateral radiographs of 736 Middle-Eastern knees were performed. Patellar tendon length (TL) and the patellar length (TP) was digitally measured and the ratios of these measures was used to calculate the Insall-Salvati ratio. Results: The overall mean TL/PL ratio was 1.20±0.17. The Insall-Salvati ratio was higher (p=0.0013) in males (1.22± 0.12) than in females (1.18±0.17). According to our measurement, the recommended levels for defining abnormal patellar position should be 0.86 for patella baja and 1.54 for patella alta. Conclusion: The use of TL/PL ratio demonstrated a higher incidence of patella alta and a higher mean TL/PL ratio compared to other techniques. The normal ranges for the TL/PL differs from western populations and may be attributed to lifestyle differences.