medwireNews: Dislocation risk following total hip replacement is declining with time and is associated with a number of surgical, hospital, and patient-related factors that are generally modifiable, UK researchers report.
“Early recognition of these factors, along with careful planning before and after surgery, along with a multidisciplinary approach, might represent an implementable strategy by which to prevent or minimise dislocations among patients at high risk,” write Setor Kunutsor (University of Bristol) and co-authors in The Lancet Rheumatology.
Their systematic review and meta-analysis of 125 longitudinal studies with data on 4,633,935 primary total hip replacements and 35,264 dislocations showed that the pooled incidence of dislocation over a weighted mean follow-up period of 6 years was 2.10%, with a range from 0.12% to 16.13%.
This was a significant decline from the incidence of approximately 3.50% observed in 1971, which is “likely to reflect advancements in surgical practice,” the researchers remark.
Among the patient-related factors explored, the risk for dislocation did not differ significantly between men and women but was a significant 27% higher in those aged 70 years and older compared with younger patients, 38% higher in obese patients relative to those with a BMI below 30 kg/m2, and 21% lower in those from high versus low income groups.
In addition, results from single studies showed significantly increased dislocation risks among patients with a high rather than low level of social deprivation (relative risk [RR]=5.30) and those with drug use disorder (RR=1.77), as well as a significantly decreased risk among Asian patients compared with White patients (RR=0.41)
Patients undergoing surgery for avascular necrosis, rheumatoid arthritis, inflammatory arthritis, or osteonecrosis all had a significantly increased risk for dislocation compared with those undergoing surgery for osteoarthritis, with RRs ranging from 1.45 to 1.94.
Other medical factors associated with increased dislocation risk included previous hip surgery (RR=3.43), previous spinal fusion (RR=2.19), neurologic disorder (RR=2.54), psychiatric disease (RR=1.35), as well as a number of other comorbidities and increased scores on comorbidity indices (RRs=1.20–3.20).
Kunutsor and team also found that at the surgical and implant levels, anterolateral, direct anterior, lateral, or lateral with trochanteric osteotomy approaches significantly reduced the risk for dislocation versus the posterior approach, as did the use of larger femoral head diameters, elevated acetabular liners, dual mobility cups, cemented fixations, specific bearing types, and standard femoral neck lengths.
Finally, the investigators found that having an experienced surgeon or a surgeon with a high procedure volume and receiving preoperative patient education were associated with a significantly reduced risk for dislocation.
Kunutsor et al conclude that their study provides “a detailed picture of the multifactorial causes of dislocation risk following primary total hip replacement.”
By Laura Cowen
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Lancet Rheumatol 2019; doi:10.1016/S2665-9913(19)30045-1