This study was designed to analyze DRG reimbursements of elective total arthroplasty of hip and shoulder joint compared to acute fracture interventions with regard to LOS, OR time, implant and personnel costs.

Overall, fracture arthroplasty of the hip and shoulder showed the highest DRG remuneration and estimated contribution margins with 6.930 EUR and 5.833 EUR respectively for cemented HA of femoral neck fractures as well as 9.050 EUR and 6.339 EUR respectively for rTSA of proximal humeral fractures.

However, it should first be noted critically for the classification of the results that in our study, more complex cases with revenue-relevant secondary diagnoses and higher-value DRGs were excluded in all groups to allow better comparability of acute trauma patients and elective osteoarthritis patients. The exclusion of these cases may lead to an overestimation of the economic performance of acute fracture interventions. Since more complex trauma cases with higher PCCL values and DRG revenues, but also very high overall treatment costs, account for a significant portion of daily trauma care, our results do not comprehensively reflect clinical practice.

At the hip, the ratios DRG reimbursement/OR time of 111 EUR/minute and DRG reimbursement/implant costs of 15 EUR/EUR were highest for nail fixation of proximal femoral fractures followed by HA with 79 EUR/minute and 9 EUR/EUR respectively. In fracture scenarios, nail osteosynthesis seems to be better reimbursed due to the lower implant costs and shorter OR time compared to arthroplasty. The cost analysis of Liu et al. showed comparable results with a higher cost-effectiveness of internal fixation for femoral neck fractures compared to hemi-arthroplasty, since total costs were lower [13, 14].

Our results showed that implant costs for hip and shoulder arthroplasty are much higher than for osteosynthetic treatments. The DRG reimbursement regarding implant costs was lowest for fracture and elective rTSA at the shoulder with 3 EUR/EUR and second lowest for elective TA at the hip with 4 EUR/EUR. Implants represent a major cost driver in arthroplasty, with prices varying considerably internationally in recent years [1, 15]. Particularly in revision arthroplasty, certain complex procedures cannot be performed cost-effectively due to the high implant costs, as demonstrated by a cost-benefit analysis by Awwad et al. using mega-prostheses [16].

Reverse shoulder arthroplasty is considered a cost-intensive procedure for the treatment of proximal humeral fractures due to the high costs of prostheses. This is demonstrated by a study by Rosas et al., who found in a cost analysis of three standard surgical procedures for proximal humeral fractures, that rTSA had the highest initial and total treatment costs compared to hemiarthroplasty and plate osteosynthesis [17]. Packer et al. analyzed the treatment costs of rTSA for proximal humeral fractures and showed that implant and personnel costs are the primary cost drivers, with implants accounting for up to 40% of the total costs [18]. However, Politzer et al. concluded that despite the higher initial costs, reverse shoulder arthroplasty should be considered for the treatment of complex proximal humeral fractures, as it has similarly high total costs within the first postoperative year as hemi-arthroplasty [19]. Further studies have shown that reverse shoulder replacement can be a cost-effective strategy for fracture treatment in the long term compared to plate osteosynthesis [20,21,22,23].

Despite the high implant costs, elective rTSA is also considered a cost-effective arthroplasty procedure, as Bachman et al. demonstrated in a prospective study comparing reverse shoulder arthroplasty and total hip arthroplasty in osteoarthritis with regard to cost-effectiveness and quality of life [24]. Coe et al. and Cregar et al. found similar conclusions by cost-effectiveness analyses of elective reverse shoulder arthroplasty [25, 26].

Generally, surgical costs are largely influenced not only by implant costs but also by personnel costs, which depend on the OR time and the professional qualifications of the staff. In our study, we calculated the highest overall surgical costs of 4.100 EUR for rTSA in fracture scenarios due to the highest implant and personnel costs. The lowest total surgical costs of 685 EUR we found for nail fixation of proximal femoral fractures based on the lowest implant costs and the shortest OR time, which further underlines the results mentioned above.

In terms of length of stay in the hospital, elective hip and shoulder arthroplasty showed the highest DRG reimbursements. For elective total hip arthroplasty, the DRG remuneration per day was 723 EUR with a mean LOS of 8 days. Since patients with proximal femoral fractures had a LOS up to 5 days longer, the DRG reimbursement for cemented HA and nail osteosynthesis was approximately 200 EUR per day lower. Compared to elective hip patients, patients with proximal femoral fractures are usually older with many comorbidities and longer lengths of stay, often in specialized geriatric trauma centers, which can lead to higher treatment costs and revenue deficits for the hospitals [27, 28]. This is demonstrated by the results of Rohrer et al., who found a correlation between longer LOS for multimorbid orthopaedic patients and higher costs as well as revenue losses in the Swiss DRG system [4].

For the shoulder, in our study the DRG remuneration per day was even 1.641 EUR for elective rTSA with a mean length of stay of five days versus 786 EUR for rTSA in trauma cases with a much longer LOS of 12 days.

This confirms the data of Menendez et al., who found a correlation between total treatment costs and length of stay, but not with the operating time for reverse shoulder replacement [29]. In addition, Rosas et al. showed by retrospective cost analysis of shoulder arthroplasty that revenues are significantly influenced by comorbidities, which affect length of stay [30].

In the University Orthopaedic Trauma Department examined in the present study, both acute trauma patients and elective osteoarthritis patients are mobilized postoperatively through physiotherapy, and discharge goals are defined depending on the general condition, home care situation and mobility status, including transfer to an orthopedic or geriatric rehabilitation clinic or discharge home. For geriatric, frail patients, there is also a structured concept involving geriatricians and acute geriatric early complex treatment by an interdisciplinary team of specialized medical and nursing service and therapists within the framework of a certified geriatric trauma center. The management of postoperative care and mobilization generally has a significant structural influence on the length of hospital stay and thus on treatment costs, and should therefore be designed as efficiently as possible, taking into account the patients’ clinical condition.

Due to the longer LOS of patients with proximal femoral and proximal humeral fractures, the calculated total personnel costs for the ward in our study were highest with 2.520 EUR and 2.236 EUR compared to patients undergoing elective hip and shoulder arthroplasty with 1.462 EUR and 958 EUR respectively.

Despite the higher total ward personnel costs, our results showed higher estimated contribution margins for acute fracture interventions compared to elective arthroplasty procedures, especially at the hip. However, these are merely case-specific, approximately calculated contribution margins, which ultimately do not allow any conclusions about the profitability of the department. Since structural costs, such as emergency department infrastructure or the standby capacity of the operating room and intensive care unit, were not considered in the calculations in the present study, the significance of the results regarding the overall structural profitability of the clinic is limited.

To summarize, the classification of trauma cases with fractures into higher-rated DRG case-based flat rates is appropriate and justified, especially in older multimorbid patients with longer length of stay and costly inpatient treatment. Despite trauma cases seem to be better reimbursed, there is a considerable higher effort with 24-hour availability of emergency room and operating room in trauma surgery compared to elective orthopaedics, which can lead to a financial burden for the hospitals [31]. Furthermore, the above-mentioned fact that treatment of acutely injured and more fragile patients is most likely more expensive compared to elective orthopaedic patients justifies higher reimbursements in trauma and seems to be appreciated by the aG-DRG system.

This retrospective study is limited by several factors. First, there was no financial analysis of total hospital costs possible due to the structure of cost recording at the University Hospital with missing data of total treatment costs per case. Therefore, personnel costs were calculated by model and contribution margins were estimated. An assessment of the cost coverage rate from the hospital’s perspective was not possible. Another limitation is that personnel and implant costs can vary between hospitals, influencing the total treatment costs and the cost coverage rate. Furthermore, this study is certainly limited regarding generalizability, as the results are not universally applicable and the estimated contribution margins are institution-specific outputs, not system-level truths. Another limitation is the purely descriptive statistical analysis without formal statistical comparisons, which nevertheless allowed the extensive data set to be presented in an overview in terms of a health economic revenue analysis.