Osteoporosis May be Underestimated in TKA Patients

The prevalence of osteoporosis among patients undergoing total knee arthroplasty (TKA) may be higher than previously believed because it may go unrecognized in this population, according to recent findings.

“Poor bone health is common in total knee arthroplasty (TKA) patients and is associated with poorer outcomes. Furthermore, peri-prosthetic fractures are becoming epidemic and almost always have a fragility fracture mechanism. This suggests a relationship between peri-prosthetic fracture and osteoporotic bone,” the study authors wrote, adding, “The main study question is: what is the prevalence of osteoporosis in a healthy cohort of patients after TKA? Our hypothesis is that osteoporosis is highly prevalent and under-recognized.”

The cross-sectional study was published in the October issue of The Journal of Arthroplasty. A total of 30 patients—15 each of males and females—aged between 59 and 80 (mean, 67.9) years were included. Patients had no known history of bone health issues and underwent routine dual-energy X-ray absorptiometry between two and five (average 3.2 ± 0.8) years following primary unilateral TKA. Analysis of the X-ray in combination with clinical risk factors were used to determine fracture risk per the Fracture Risk Assessment Tool. The World Health Organization definition of skeletal status (normal, osteopenic, or osteoporotic) was used.

Osteoporosis Prevalent in More Than One-third of Patients

Of the total cohort, six (20%) patients had T-score ≤ −2.5, 18 (60%) had T-score between −1 and −2.5, and six (20%) patients had T-score ≥ −1. Occult vertebral fractures were observed in five patients with normal or osteopenic bone mineral density. Overall, 11 (36.7%) of patients met National Osteoporosis Foundation criteria for pharmacologic treatment.

The researchers posited that the 36.7% of patients meeting the National Osteoporosis Foundation criteria was a significant portion, and also suggested that this may be “a conservative estimate” because the study only included patients without a history of bone health problems.

“This indicates that greater than one-third of TKA patients are potentially at elevated risk for peri-prosthetic fracture and other complications related to osteoporosis. Based on [National Osteoporosis Foundation] guidelines, these patients would be indicated for anti-osteoporosis medications,” the study authors wrote.

The researchers suggested in their conclusion that National Osteoporosis Foundation screening criteria be applied to screen certain arthroplasty patients pre- and postoperatively.

“Further research is required to investigate the utility and cost-effectiveness of regular [bone mineral density] BMD screening after TKA. These data support the further study of post-operative osteoporosis and consideration of BMD screening after TKA,” they concluded.