Dislocation following primary total hip replacements has declined over time, and has a number of modifiable risk factors, research from the NIHR Bristol Biomedical Research Centre and published in The Lancet Rheumatology has found.

Dislocation following total hip replacement is associated with repeated admissions to hospital and substantial costs to the health system. However, the various factors influencing dislocation following primary total hip replacement are not well understood.

Researchers reviewed and analysed data from almost five million hip replacements to assess the association of patient-related, surgery-related, implant-related, and hospital-related factors with dislocation risk following surgery.

The research identified a significant decline in dislocation rates from 1971 to 2015.

They found that the risk of dislocation was higher in those aged 70 years and older, and in patients from low income groups. White ethnicity (when compared with Asian ethnicity), drug use disorder and social deprivation were significantly associated with increased dislocation risk. The risk of dislocation was higher in patients with body-mass index (BMI) of 30 kg/m2 or higher.

Several medical factors and those related to surgical history were significantly associated with increased dislocation risk. These included neurological disorder, psychiatric disease, comorbidity indices, previous surgery including spinal fusion, and surgical indications including avascular necrosis, rheumatoid arthritis, inflammatory arthritis and osteonecrosis.

Surgical factors such as the anterolateral, direct anterior, or lateral approach, and posterior approach with short external rotator and capsule repair were significantly associated with reduced dislocation risk.

At the implant level, larger femoral head diameters, elevated acetabular liners, dual mobility cups, cemented fixations, and standard femoral neck lengths significantly reduced the risk of dislocation.

Finally, hospital-related factors such as experienced surgeons and high surgeon procedure volume also significantly reduced the risk of dislocation.

Dr Setor Kunutsor, Research Fellow in Evidence Synthesis at the University of Bristol and a lead author of the study, says:

“Our research suggests that when clinicians undertake primary hip replacement surgery, there are several factors they can consider to reduce the risk of dislocation and these include surgical approaches. For patients at high risk of dislocation, large femoral head sizes or alternative bearings such as dual mobility can also be used.

“Having a high BMI or comorbidities also increases the chances of dislocation following surgery. Because these are modifiable risk factors, they may also be amenable to optimisation before the surgery takes place.”

Paper

Risk factors for dislocation after primary total hip replacement: a systematic review and meta-analysis of 125 studies involving approximately five million hip replacements

Setor K Kunutsor, Matthew C Barrett, Andrew D Beswick, Professor Andrew Judge, Professor Ashley W Blom, Vikki Wylde, Michael R Whitehouse. 9 September 2019
Published in The Lancet Rheumatology