Does Obesity Affect Outcomes in Patients Undergoing Innovative Multi-Modal Physical Therapy Following Primary Total Knee Arthroplasty?

INTRODUCTION

Knee stiffness following total knee arthroplasty (TKA) is a common complication, especially in obese patients. The initial, non-operative treatments for this complication includes splinting and physical therapy. If these measures fail, manipulation under anesthesia (MUA) or surgical exploration can be considered to restore range of motion (ROM). However, it is generally desirable to avoid these procedures. For these reasons, newer physical therapy protocols have been developed. However, it is unknown whether these protocols are efficacious for obese patients. Therefore, the purpose of this study was to evaluate and compare: 1) ROM; 2) the rate of MUA; 3) number of physical therapy visits; and 4) costs in patients who underwent innovative multimodal physical therapy (IMPT) and were either obese or non-obese.

MATERIALS AND METHODS

A review of a consecutive series of patients undergoing TKA at a single center within a three-year period was performed. All patients received IMPT post-TKA. Patients were divided into obese (body mass index (BMI >30kg/m2) and non-obese (BMI <30 kg/m2) groups. One-hundred and forty-nine patients underwent TKA and had a mean age of 67 years (range, 42 to 88 years). There were 48 patients in the non-obese group and 101 in the obese group. The obese group was significantly younger (mean, 60 years; range 38 to 54 years vs. mean, 69 years; range, 50 to 88 years), with a similar gender distribution. Comparisons of ROM, MUA, number of physical therapy visits, and costs were performed using Student's t-tests and Chi-square tests as appropriate. Cost-analysis was also performed based on the number of visits to physical therapy (PT).

RESULTS

At latest follow-up, there were no significant differences in mean flexion (mean, 115°, range, 90 to 130° vs. mean, 113°, range 60 to 130°) and extension (mean, 0.81°, range, 0 to 10° vs. 0.54°, range 0 to 10°, p=0.469) between the two groups. The obese group had a 14% (n = 12) rate of MUA compared to 2% (n=1) in the non-obese group (p=0.045). Obese patients had a significantly higher number of mean visits to PT. There was significantly higher mean healthcare costs in the obese (mean, $3,919, range $1,043 to $11,749) as compared to the non-obese (mean, $2,950, range $741 to $7,865) group.

DISCUSSION

Although both cohorts have similar mean ROM at final follow-up, the obese cohort had a significantly higher proportion of patients who underwent MUAs following TKA as compared to non-obese patients, despite IMPT. At latest follow-up, the ROM achieved between the two groups was similar. Obese patients required more PT visits resulting in significantly higher mean healthcare costs.