Summary

We studied the risk for hip fracture before and after total knee replacement (TKR) in the entire population in Sweden. Women and men had a low risk for hip fracture before TKR but an increased risk the first year after TKR.

Purpose

It is known that osteoarthritis is associated with high bone mass. We therefore studied the risk of hip fracture before and after total knee replacement (TKR), risk of different hip fracture types, and risk subdivided in genders and age groups.

Methods

We followed the total Swedish population born between 1902 and 1952 (n = 4,258,934) during the period 1987–2002 and identified all patients with TKR due to primary OA (n = 39,291), and all patients with hip fracture (n = 195,860) in the Swedish National Inpatient Register. The risk time analyses were based on Poisson regression models.

Results

The hazard ratio (HR) for hip fracture the last year before TKR was 0.86 (95% CI 0.74 to 1.00) and the first year after 1.26 (95% CI 1.11 to 1.42) compared to individuals without TKR. The HR for femoral neck fracture 0–10 years after TKR was 0.95 (95% CI 0.89 to 1.01) and for trochanteric fracture was 1.13 (95% CI 1.06 to 1.21). The HR for hip fracture in the age group 50–74 was 1.28 (95% CI 1.14 to 1.43) and in the age group 75–90 years was 0.99 (95% CI 0.94 to 1.04) 0–10 years after TKR, compared to individuals without TKR.

Conclusion

Individuals had a low risk for hip fracture before TKR but an increased risk the first year after TKR. The risk in individuals below age 75 years and for trochanteric fractures was increased after TKR. Possible explanations include changed knee kinematics after a TKR, physical activity level, fall risk, and other unknown factors.

中文翻译：

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瑞典全膝关节置换术前后髋部骨折的风险

概要

我们研究了瑞典全体人群全膝关节置换术（TKR）前后髋部骨折的风险。男性和女性在TKR前发生髋部骨折的风险较低，但在TKR后的第一年中发生风险较高。

目的

众所周知，骨关节炎与高骨量有关。因此，我们研究了全膝关节置换术（TKR）前后髋部骨折的风险，不同类型髋部骨折的风险以及按性别和年龄组细分的风险。

方法

我们追踪了1987年至2002年间1902年至1952年之间出生的瑞典总人口（n = 4,258,934），并确定了所有因原发性OA而导致TKR的患者（n = 39,291），以及所有因髋骨骨折而导致的髋部骨折（n = 195,860）。瑞典国家住院登记簿。风险时间分析基于泊松回归模型。

结果

与没有TKR的个体相比，在TKR之前的最后一年髋关节骨折的危险比（HR）为0.86（95％CI为1.11到1.42），在TKR之后的第一年为1.26（95％CI为1.11到1.42）。TKR后0-10年股骨颈骨折的HR为0.95（95％CI为0.89至1.01），股骨转子骨折的HR为1.13（95％CI为1.06至1.21）。与TKR后相比，年龄在50-74岁组的髋部骨折的HR为1.28（95％CI 1.14至1.43），而在75-90岁组的髋部骨折的HR为0.99（95％CI 0.94至1.04）。没有TKR的个人。

结论

个体在TKR前发生髋部骨折的风险较低，但在TKR后第一年发生风险较高。TKR后，年龄在75岁以下的个体和股骨转子骨折的风险增加。可能的解释包括TKR后膝关节运动学改变，身体活动水平，跌倒风险和其他未知因素。