Hip Dislocations Often Underreported in Implant Registries: Study

The findings of a new study highlight the risk of hip locations following joint replacement surgery, which appears to occur much more often than previously believed.

Hip dislocation is a common and serious complication among total hip replacement patients, and is commonly a top reason for follow-up surgery. In some cases, dislocations can be treated without surgery or hospitalization, when detected early. However, the problems appear to be widely underreported, according to a report published last month in The Journal of Bone & Joint Surgery.

Researchers analyzed data from the Danish Hip Arthroplasty Registry, and the Danish National Patient Register, identifying more than 31,000 cases of dislocations which would otherwise have been missed between 2012 and 2014. The five-year study included all hospital contacts in Denmark within the first two years after total hip replacement.

Researchers found cases of hip dislocation which would have been missed if they had not linked the two patient databases to identify the unreported cases. The data indicates the rate of hip dislocations within two years after surgery was 3.5%, which is 50% higher than previous estimates.

According to the findings, more than 40% of patients with hip dislocations had at least two dislocations. Three-quarters of patients’ first dislocations occurred within three months of the initial hip replacement surgery.

The researchers noted that prior studies have found a wide range of dislocation rates. They suggest the rates differed because of differences in study methods and patient groups.

The risk of hip dislocation was lower in patients under the age of 65 and higher in patients over the age of 75. The rate of dislocation was also lower in men than in women, and in patients who were in better health.

Some surgical procedures were also linked to a lower risk of dislocation, including cemented fixation, lateral surgical approach, larger femoral head size, and use of dual-mobility cups.

Researchers believe this study is a more accurate depiction of hip dislocations than prior studies.