Low presurgical BMI and high physical activity improves function after total knee arthroplasty: JAMA

Norway: Preoperatively, high physical activity, osteoarthritis severity, and lower body mass index (BMI) are associated with improved function 12 months after total knee arthroplasty (TKA), reports an article published in the JAMA Network Open.

Total knee arthroplasty has evolved over the years since it was first in the early 1970s. The global demand for TKA is increasing at a dramatic rate due to the increased prevalence of osteoarthritis and the aging population. The number of primary TKA procedures is projected to grow immensely in the coming years.TKA is one of the most cost-effective and consistently successful surgeries in orthopedics, for restoring physical function in patients with end-stage osteoarthritis. However, more than 1 in 5 patients do not regain satisfactory physical function after TKA which leads to more expensive revision surgery and an immense burden on the individual, health care system, and socioeconomic levels.

Evidence on factors associated with physical function has been reviewed previously, but findings are contradictory, limited in scope, based on pooled data across short-term and longer-term outcomes, or did not address certainty of evidence. Identification of factors associated with physical function may be warranted to improve outcomes in the patients.

Olsen U., University of Oslo, Norway, and colleagues performed a systematic review and meta-analysis study to identify preoperative and intraoperative factors associated with physical function 12 months after TKA.

The research team searched Medline, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Library, and Physiotherapy Evidence Database (PEDro) for prospective observational studies or RCTs on factors associated with physical function after TKA in adult patients with osteoarthritis.

The team analyzed 20 studies, including 11 317 patients and 37 factors. The primary outcome was set as physical function 12 months after TKA. Secondary outcomes were physical function 3 and 6 months after TKA. All estimates were mean correlations between factors and postoperative function. Positive correlations corresponded to better function.

Key findings of the study,

• Mean correlation with higher BMI, better physical function, and more severe osteoarthritis was estimated to be −0.15, 0.14, and 0.10, respectively.

• In sensitivity analyses, the mean correlation with the better physical function was estimated to be 0.20, a larger coefficient than in the main analysis, while mean correlations were estimated to be similar for other factors (BMI: –0.17; osteoarthritis severity: 0.10).

The authors conclude that there is evidence (with moderate certainty) that higher BMI is correlated with worse physical function and that better physical function (low-certainty evidence) and more severe osteoarthritis (high-certainty evidence) are correlated with better physical function 12 months after TKA.

The present study findings suggest that these factors should be included when testing predictive models of TKA outcomes, the authors wrote.

Reference:

Olsen U, Lindberg MF, Rose C, et al. Factors Correlated With Physical Function 1 Year After Total Knee Arthroplasty in Patients With Knee Osteoarthritis: A Systematic Review and Meta-analysis. JAMA Netw Open. 2022;5(7):e2219636. doi:10.1001/jamanetworkopen.2022.19636