The Cost of Robot-assisted Total Hip Arthroplasty

Comparing Safety and Hospital Charges to Conventional Total Hip Arthroplasty

Gregory J. Kirchner, MD, MPH; Alexander M. Lieber, MD; Brett Haislup, MD; Yehuda E. Kerbel, MD; Vincent M. Moretti, MD


J Am Acad Orthop Surg. 2021;29(14):609-615. 

In This Article

Abstract and Introduction


Introduction: Utilization of robotic assistance is increasing for total hip arthroplasty (THA). However, few studies have directly examined the efficacy of this technique at reducing complications. This research aims to compare the rates of perioperative complications of robotic-assisted THA (RA-THA) with conventional THA (C-THA).

Methods: This study screened more than 35 million hospital discharges between 2010 to 2014 using the National Inpatient Sample. The International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure codes were used to identify 292,836 patients who underwent C-THA (ICD 81.51) and 946 patients who underwent RA-THA (ICD 81.51 and ICD 17.41, 17.49). Perioperative complications were identified using ICD-9-CM diagnosis codes. Patient mortality was determined using the Uniform Bill patient disposition. The RA-THA cohort was statistically matched 1:1 to C-THA about patient age, sex, race, comorbidities, hospital type, and calendar year. Mean cost and length of stay (LOS) for each cohort were calculated and compared using the Kruskal-Wallis H test. Logistic regression was used to compare the risks of major and minor complications between the cohorts.

Results: We matched 758 (80.13%) RA-THA patients with 758 patients who underwent C-THA. No patient in our sample died. When compared with the conventional group, multivariate analysis revealed that the risk of major complications was similar in RA-THA patients (odds ratio = 0.698, 95% confidence interval = 0.282 to 1.727). In addition, although the rate of minor complications was higher in the RA-THA cohort (21.6% versus 12.5%, P = 0.004), no difference was observed on multivariate analysis (odds ratio = 1.248, 95% confidence interval = 0.852 to 1.829). The average inpatient hospital cost of a RA-THA was $20,046 (SD = 6,165) compared with $18,258 (SD = 6,147) for C-THA (P < 0.001). The average LOS was for RA-THA was 2.69 days (SD = 1.25) compared with 2.82 days for C-THA (SD = 1.18, P < 0.001).

Discussion: In a statistically matched cohort, the risk of perioperative complication in patients who underwent RA-THA versus C-THA patients were similar. However, RA-THA was costlier despite shorter LOS.

Level of Evidence: Level III, retrospective cohort analysis


Total hip arthroplasty (THA) is one of the most common procedures in the United States with over 2.5 million hip arthroplasties performed annually.[1,2] Despite the substantial benefits of the operation, complications persist. A major obstacle for hip arthroplasty surgeons is an early hip revision.[3–6] THA revisions are costly and result in longer hospital stays than the initial procedure.[5] Over the past 20 years, advancements in technology reduced the rates of impingement and wear, although the rate of revision THA continues to increase.[7] According to Gwam et al,[6] the most common complications of THA include mechanical loosening and prosthetic dislocation, which account for over one-third of THA revisions. Intraoperative factors contribute to these outcomes, including improper acetabular and femoral implant placement.[8–10] Therefore, intraoperative navigation, such as robotic assistance, has been adopted to enhance precision, mitigate adverse patient outcomes, and prolong the life span of the implanted device.

Recently, robotic-assisted total hip arthroplasty (RA-THA) has increased in popularity among hip arthroplasty surgeons.[11] Utilization of robotic assistance requires advanced preoperative imaging to identify femoral and acetabular anatomy, as well as other distinctive landmarks for each patient. The robotic arm provides surgeons with "active" assistance. For example, the robotic arm will only activate when the surgeon is operating within the predetermined parameters to produce the ideal, computer-developed location for the acetabular and femoral implants. Recent studies have suggested that RA-THA provides greater accuracy for acetabular and femoral implant placement compared with conventional THA (C-THA).[12,13] However, the outcomes after RA-THA have not been extensively examined.

A paucity of literature exists when comparing the C-THA and RA-THA techniques. Because adoption of intraoperative navigation in THA continues to grow, the outcomes must be compared with those of the conventional technique. An appropriate first step is to compare RA-THA on the metrics of patient safety, such as perioperative morbidity and mortality, as well as the common care delivery metrics—cost and length of stay (LOS). To attain large sample sizes for comparison, we screened hospital discharges between 2010 and 2014 using the National Inpatient Sample (NIS) and the Nationwide Inpatient Sample. We hypothesize that using RA-THA markedly reduces perioperative morbidity and mortality while simultaneously increasing cost and prolonging LOS compared with the C-THA technique.