Conversion Total Knee and Hip Arthroplasty Requires Increased Energy Expenditure Compared to Primary Knee Arthroplasty.

Abstract

Conversion total knee arthroplasty (TKA) requires increased preoperative planning, surgical time, and perioperative resources, yet there is currently no separate procedural code for conversion total knee arthroplasty (TKA) as there is for conversion total hip arthroplasty (THA). The purpose of this study was to compare energy expenditure for the surgeon when performing primary TKA/THA, conversion TKA/THA, and revision TKA/THA. Surgery was performed on 179 arthroplasty patients prospectively by five surgeons. There were 77 primary TKA, 10 conversion TKA, 18 revision TKA, 58 primary THA, four conversion THA, and 12 revision THA patients. Energy expenditure of five arthroplasty surgeons at a single institution was recorded via a smart garment. Demographic variables and energy expenditure were compared between TKA and THA cohorts using analysis of variance (ANOVA) tests. Overall, TKA patients were similar in age, sex, and laterality. Body mass index varied amongst TKA groups, with conversion TKA (28.2 ± 6.4) and primary TKA (31.1 ± 5.9) being lower than revision TKA (35.2 ± 9.3; P = 0.018). There were no differences in body mass index (BMI) and sex in THA patients. The conversion THA cohort (42 ± 15.9) was younger than the primary THA (63 ± 13) and revision THA (61 ± 14; P = 0.015) cohorts. Conversion TKA (467.2 ± 219.4 calories) required 152% higher energy expenditure than primary TKA (308.0 ± 109.2 cal), but less than revision TKA (703.8 ± 368.0 cal; P <0.001). Conversion THA (523.8 ± 117.9 cal) required 143% higher energy expenditure than primary THA (365.2 ± 112.5 cal), but less than revision THA (846.2 ± 435; P < 0.001). Conversion TKA is associated with significantly more physiologic stress for a surgeon. The increased energy expenditure seen in conversion TKA relative to primary TKA mimics the increase seen in conversion THA, which does have a conversion procedural code. This study highlights the need for payment reform to reflect the actual work done by arthroplasty surgeons.