This article is more than 5 years old. Information may no longer be current.
Morbidly obese THA patients show increased risk of instability, dislocation
Click Here to Manage Email Alerts
Morbidly obese patients who have total hip arthroplasty risk hip instability and dislocation because of their size compared to patients with a normal body mass index, and researchers from the University of Iowa suggest the procedure should be modified for larger patients, according to a study in Clinical Orthopaedics and Related Research.
“We have shown that morbidly obese patients’ thighs are so large they are actually pushing each other outward and forcing the implant out of its socket,” Jacob M. Elkins, MS, a graduate student from the University of Iowa, stated in a press release. “Studies have shown up to a 6.9-fold higher dislocation rate for morbidly obese patients compared to normal weight patients.”
In 146 healthy adults and six cadaver pelvises, Elkins and colleagues measured a variety of hip implants in patients performing movements such as sitting and standing. They assessed dislocation risk with 28-mm and 36-mm heads, for multiple cup abduction angles and in normal and high-offset necks, according to the abstract.
Patients increased their risk of dislocation if they had a body mass index of 40 or greater. While larger diameter heads did not decrease the dislocation rate, implants with high-offset necks were effective, according to the abstract.
Reference:
Elkins JM, Daniel M, Pedersen DR, et al. Morbid obesity may increase dislocation in total hip patients: a biomechanical analysis. Clin Orthop Rel Res. Published online ahead of print Aug. 21, 2012. doi:10.1007/s11999-012-2512-3.
Disclosure: Research for this study was funded by the National Institutes of Health, the Veterans Administration and the National Center for Research Resources.