Impact of short tibial length on the development of knee osteoarthritis

Background Osteoarthritis of the knee is the leading cause of disability worldwide. Previous studies showed association of bone diameter and bone length discrepancy as risk factors of knee osteoarthritis. However, few studies examine whether segmental discrepancy in the bones of lower limb have any association with knee osteoarthritis. Objective The purpose of this study was to investigate the effects of short tibia on the development of knee osteoarthritis. Methods Participants > 50 years of age who were treated with various knee complain were enrolled. Full length Anteroposterior view x-rays were used to assess the length of mechanical axis of tibia, femur and the anatomical axis of femur. Kellgren-Lawrence scale was used for selecting the case and control group. The two groups were compared based on the length of tibia, femur and on tibial femoral length ratio. Results N = 692 KL grade > 2 were enrolled in case and N = 369 KL < 2 in control. The average age was 67.35 ± 6.6 and 66.49 ± 4.7 years in case and control group, F = 1.277 and P = 0.0519. The average tibia mechanical axis length was 337.2 ± 26.50 mm in case and 346.1 ± 24.72mm in control, F = 1.155 and P < 0.0001. The mechanical axis of femur mean was 419.5 ± 29.9mm in case and 419.2 ± 30mm in control F = 1.009 and P = 0.234, the femur anatomical axis mean was 416.4 ± 29.85mm in case and 413.3 ± 29.48mm in control F = 1.022 and P = 0.1136. The ratio of Tibia mechanical axis to Femur mechanical axis was 0.802 ± 0.030mm in case and 0.829 ± 0.027mm in control F = 1.312, P value < 0.0001. And the ratio of tibial mechanical axis with that of femur anatomical axis was 0.808 ± 0.03mm in case and 0.836 ± 0.027mm in control with F = 1.272, P value < 0.0001. Conclusion This is to our knowledge, based on the findings of the present study the short tibial length relative to femur mechanical and anatomical length found to have significant impact to the development and progression of ipsilateral knee osteoarthritis. Level of Evidence: Clinical Level Ⅲ