Recent study results  indicate that the total number of knee replacement (TKR) surgeries has more than tripled between the years of 1993 and 2009; researchers have linked these results to the increasing rate of obesity in the US, with younger patients impacted to a greater degree. The number of total hip replacements (THRs) also doubled during the same time period, according to the study.

A news release from the American Academy of Orthopaedic Surgeons notes that during the study, researchers reviewed at least 10 years of national data through the year 2009 regarding TKR and THR volume, length of hospital stay, in-hospital mortality, and orthopaedic workforces trends.

Among the study results, researchers reportedly found that TKR volume outranked that of THR for patients with a body mass index (BMI) of ?25 kg/m² (persons with a BMI of ?25 kg/m² and <30 kg/m² are considered overweight; patients with a BMI of ?30 kg/m², obese), but not for patients with a BMI of <25 kg/m². Additionally, in 1993, surgeons performed 1.16 TKRs for every THR, yet this ratio grew to 1.60 by 2009, researchers say. The results also single out patients aged 18 to 64 years old, who experienced a more rapid rise in overweight and obesity, compared to patients over the age 65. The percentage of patients aged 18 to 64 years old undergoing TKR rose 56% from 1997 to 2009, the study states, compared to 35% for THR.

The results also suggest that surgeons per-case reimbursement for TKR fell from $3,000 in 1995 to $1,560 in 2009, and surgeon fees for THR from $2,840 to $1,460. The data represents a 48% drop in fees for both procedures, and as a result researchers say it does not appear that surgeons are performing more TKRs over THRs because of higher reimbursement. Lastly, hospital reimbursement, length of stay, and in-hospital mortality pertaining to TKR and THR also comparably declined between 1995 and 2009.

Peter Derman, MD, MBA, lead study author, orthopaedic surgery resident, Hospital for Special Surgery, explains that researchers “found that this differential growth rate in total knee replacement procedures could not be attributed to changes in physician or hospital payments, length of hospital stays, in-hospital death rates, or surgical work force characteristics. Because excess body weight appears to be more damaging to the knee than to the hip, the increasing prevalence of overweight and obesity may explain the growing demand for knee replacements over hip replacements.”

Derman adds that if the rates of overweight and obesity continue to rise, experts can expect to see a continued rise in the number of TKRs performed annually, with a more “modest increase in hip replacement volumes.”

Source(s): Science Daily, American Academy of Orthopaedic Surgeons