Risk of hip fracture rises in decade following total knee replacement
Swedish researchers have published preliminary results of a fracture risk study, which was based on analysis of 15 years of medical records (1987–2002), covering the entire Swedish population born between 1902 and 1952.
They were able to show that individuals with total knee replacement (TKR) due to primary osteoarthritis had a low risk for hip and vertebral fracture in the decade before surgery; however, after total knee replacement, the risk for hip fracture increased by 4 per cent and the risk for vertebral fracture increased by 19 per cent compared with the population without TKR.
A total of 3221 patients had both total knee replacement and hip fracture during the period studied. The hazard ratio (HR) for patients with knee osteoarthritis to have sustained a hip fracture during the ten years preceding TKR averaged 0.58, whereas in the ten years following surgery it increased to an average of 1.04. The HR for a vertebral fracture rose from 0.55 during the ten years preceding TKR to 1.19 during the ten years after surgery. The lower risk of hip or vertebral fracture before and the increasing risk of hip or vertebral fracture after TKR remained after adjustment for age, gender, calendar year and latitude. (The HR for mortality in the first year after TKR averaged 0.40, rising to 1.06 ten years after TKR.)
Lead author C.H. Vala, of the Sahlgrenska Academy in Molndal, Sweden, said: “Studies have shown that osteoarthritis is associated with higher bone mass, and, as well, there may be a decreased physical activity level due to pain. The increasing risk for hip and vertebral fracture in the ten years after knee replacement may be explained by pain, increase of physical activity due to rehabilitation, and other biomechanical factors. With approximately 13,000 total knee replacements carried out in Sweden annually, further research on the increased fracture risk in this population group is needed.”