Is obesity related with periprosthetic fractures around the knee?

Periprosthetic fracture (PPF) is a devastating complication following primary total knee arthroplasty. Obesity is currently considered a risk factor for many complications in orthopaedics, but there is no evidence in literature about the relationship between obesity and PPF around the knee. The objective of this study was to determine whether obesity is associated with a higher incidence of PPF.

All patients diagnosed of a PPF around the knee from January 2010 to December 2013 were enrolled. Forty-nine PPF (47 women and 2 men) were included, and a total of 97 patients (80 women and 17 men) were randomly obtained as a control group. Body mass index (BMI) was obtained in both groups and classified as <25 (normal), overweight (25-29.9), obese (30-34.9), very obese (35-39.9), or morbid obesity (≥40). Both groups, were also divided into subpopulations depending on the age as follows: <70, 70-75, 75-80 and ≥80. Statistical analysis was performed to determine any difference in BMI ≥30 kg/m² distribution between groups.

In the PPF group 61.22 % of the patients had a BMI over 30 kg/m² and likewise 62.88 % of the patients in the control group. No association was found between obesity and a higher risk of PPF (p < 0.05).

As a conclusion, obesity (BMI ≥30 kg/m²) does not have any clinical relationship with the appearance of a periprosthetic fracture around the knee (p < 0.05).