Preoperative bone assessment by bone mineral density and bone turnover in patients undergoing total knee arthroplasty

The preoperative overall bone quality in patients undergoing total knee arthroplasty (TKA) might influence the development of postoperative bone-derived complications. This study was performed to simultaneously evaluate the baseline bone mineral density (BMD) and bone turnover in these patients.

We prospectively measured the lumbar spine, total hip, and femoral neck BMD using dual-energy X-ray absorptiometry (DXA) in 214 patients (239 knees; women, 199 knees; men, 40 knees) 1 day preoperatively. Women were stratified into three age groups: <70 years (60s), <80 years (70s), and ≥80 years (80s). We assessed bone turnover using the urinary level of N-telopeptide (NTx) normalized to creatinine (NTx/Cre).

The prevalence of osteoporosis as assessed by DXA (T-score of ≤ -2.5) was 22% in women and 5% in men. A decline in BMD with aging was found in the hip but not in the lumbar spine with significant differences among ages. Women showed a higher NTx/Cre level than men (p = 0.033). An NTx/Cre level suggesting a high fracture risk (>56.5 mmol BCE/mmol Cre) was present in 54% of women and 35% of men (p = 0.037). No significant differences were found in this prevalence among age groups in women. Seventeen percent of women and 0% of men had both osteoporosis and a high fracture risk simultaneously (p = 0.002). The proportion of women in this category was lower in the 60s than 70s age group (p = 0.019).

Preoperative bone health screening before TKA might be necessary for women aged ≥70 years to prevent complications caused by perioperative poor bone condition.