Japan: Zone 7 BMD Loss after Total Hip Arthroplasty (THA)

BMD loss is seen after total hip arthroplasty (THA) in correlation with lower preoperative lumbar BMD on the lateral side and lower CFI, finds a recent study in the journal BMC Musculoskeletal Disorders. In order to prevent this, patients at risk of BMD loss may benefit from pre- or postoperative drug treatment.

Stress shielding after THA leads to bone mineral density (BMD) loss around the femoral implants, particularly in the proximal area. BMD loss around the implant is likely to occur one year following THA; however, its severity is dependent on the patient characteristics.

Naomi Kobayashi, Yokohama City University Medical Center, Yokohama, Japan, and colleagues aimed to evaluate preoperative factors correlated with the severity of zone 7 BMD loss after THA.

For the purpose, the researchers performed a retrospective cohort study. It included 48 patients who underwent primary THA from October 2011 to December 2015. All patients underwent implantation of a Zweymüller-type femoral component without any postoperative osteoporosis medications.

The objective variable was a change in zone 7 BMD after 1 year. Factors evaluated included age, body mass index, Japanese Orthopaedic Association score, Harris Hip Score, Canal Flare Index (CFI), and lumbar BMD on the frontal and lateral sides. Univariate and multivariate regression analyses identified factors correlated with loss of zone 7 BMD.

Key Findings of the Study

• Univariate regression analysis identified CFI and preoperative lumbar BMD on the anterior-posterior and lateral sides as being correlated with loss of zone 7 BMD.
• Multivariate regression analysis identified CFI and lumbar BMD on the lateral side as being correlated independently with loss of zone 7 BMD.

"Lower preoperative lumbar BMD on the lateral side and lower CFI were correlated with zone 7 BMD loss after THA," wrote the authors. "Patients with these characteristics should be monitored carefully for severe BMD loss after THA."

Reference

The study titled, "Preoperative factors predicting the severity of BMD loss around the implant after Total hip Arthroplasty," is published in the journal BMC Musculoskeletal Disorders.

DOI: https://bmcmusculoskeletdisord.biomedcentral.com/articles/10.1186/s12891-021-04161-4