Summary

Most of the cost of manipulation under anesthesia after total knee arthroplasty can be attributed to pre-procedure personnel costs, and length of stay was a risk factor for increased cost.

Abstract

Introduction

Manipulation under anesthesia (MUA) is an established treatment for postoperative stiffness after total knee arthroplasty (TKA). Since TKA is one of the largest health expenditures in the United States, it is important to understand the financial burden of MUA. Therefore, we sought to assess the costs associated with MUA after TKA.

Methods

We retrospectively reviewed 131 patients who underwent MUA after TKA at a single institution between December 21, 2015 and November 17, 2021. Medical records were reviewed for demographic information. Time-driven activity-based cost analysis was performed to calculate the time and cost associated with each stage of the MUA. Multiple linear regression was performed to determine risk factors for higher total cost. Significance was set at p<0.05.

Results

Mean age was 62.59 years and 65.6 percent (%) of patients were female. Average height was 165.99 centimeters and weight was 86.81 kilograms (kg). Mean body mass index (BMI) was 31.45 kg per meter squared. Mean duration of MUA was 3 minutes 26 seconds. Patients spent on average of 8 minutes 9 seconds before and 7 minutes 20 seconds after the MUA in the procedure room for a total of 18 minutes 55 seconds in the procedure room. All patients were discharged home with a mean length of stay of 4.68 hours. No patients sustained complications related to their MUA.
Average total cost of an MUA was 1172.25 dollars ($), with a mean of $15.87 attributed to supply costs and $1156.39 for personnel costs. Medications accounted for $8.94 of supply costs. All patients had a pre-procedure testing cost of $389.37 and a morning of surgery cost of $333.25, which, on average, accounted for 61.6% of the total cost for the MUA. Mean procedure personnel costs were $239.20 during the procedure, $114.53 in the post-anesthesia care unit (PACU), and $80.03 in phase two. On average, MUAs were found to cost $4.67 per minute throughout length of stay, with a rate of $13.03 per minute in the procedure room, $2.18 per minute in the PACU, and $0.70 per minute in phase two.
Multiple linear regression showed that the increased length of stay (p<0.001) predicted higher total cost for an MUA, but age (p=0.665), gender (p=0.051), height (p=0.644), weight (p=0.486), and BMI (p=0.503) were not associated with increased cost of MUA.

Discussion

61.6% of the cost of an MUA was attributed to personnel costs associated with the pre-procedure process. In addition, length of stay was significantly associated with increased cost of a MUA, and the most expensive part of the MUA occurred when the patient was in the procedure room. To limit the cost of MUAs, we recommend that hospitals attempt to minimize pre-procedure costs and minimize the time that patients are in the hospital, particularly in the procedure room, without sacrificing patient care.