Background: Knee osteoarthritis (OA) is a major health problem worldwide that affects lumbar spine.Objective: This study was conducted to determine the relationship between symmetrical versus asymmetrical bilateral knee OA and lumbar curvature in patients with knee OA. Subjects: Sixty male patients with knee OA were selected from outpatient clinic of the Faculty of Physical Therapy, Cairo University. Their ages ranged from 40 to 54 years old, with a mean value of 48 ± 3.59 years old. Methods: Patients were divided into three groups according to severity and symmetry of knee OA as follow; group A: Twenty patients with symmetrical bilateral knee OA (both knees grade II), group B: Twenty patients with symmetrical bilateral knee OA (both knees grade IV), and group C: Twenty patients with asymmetrical bilateral knee OA (one knee grade II and the other knee grade IV). Grades were determined according to Kellgren and Lawrence radiological classification system of OA. A Formetric II system was used to assess the lumbar curvature (lumbar lordotic angle and lateral deviation in the three groups). Results: Regarding lumbar lordotic angle and lateral deviation, there was a statistical significant difference between the three groups (F = 39.588; P = 0.001) and (F = 18.068; P = 0.001) respectively. Regression analysis revealed that there was a statistical significant positive correlation between disease severity of knee OA and both lordotic angle, where (R2 = 0.559; P = 0.001) and lateral deviation, where (R2 = 0.377; P = 0.001). Increasing disease severity of OA from the least grade to the next one led to an increase in lordotic angle degree by 4.30 (95% CI = 3.296-5.304) and an increase in lateral deviation by 2.625 mm (95% CI = 1.758-3.492). Conclusion: Patients with symmetrical bilateral knee OA (grade IV) have more lumbar lordotic angle and lateral deviation than those with symmetrical bilateral knee OA (grade II), however regarding symmetry, patients with asymmetrical bilateral knee OA had lumbar lordotic angle and lateral deviation more than those with symmetrical bilateral knee OA.
