Research letter
The Administrative Prevalence of In- and Outpatient Cruciate Ligament Surgery in Germany
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Ruptures of the anterior cruciate ligament (ACL) are among the most serious injuries in sports orthopedics and are associated with substantial short-term and long-term sequelae (1). However, data on the epidemiology of ACL injuries and their surgical care in the outpatient and inpatient setting in Germany are scarce. Such data are particularly valuable because in addition to a long convalescence period, a substantial socioeconomic burden arises in the sense of short-term and long-term costs for the healthcare system and the patients.
Our study aimed to describe the administrative prevalence of ACL injuries in Germany between 2019 and 2024 and to compare inpatient and outpatient treatments.
Methods
Our study was designed as a quantitative analysis of secondary data and investigated patients who underwent reconstructive surgery of the anterior cruciate ligament between January 2019 and December 2024. The analysis comprised surgical procedures of the ACL that were identified by OPS codes (Operationen- und Prozedurenschluessel [the German classification system for surgeries and procedures], codes 5–813.0, 5–813.3, 5–813.4, 5–813.5, 5–813.g, 5–813.j). Inpatient data obtained from the German Institute for the Hospital Remuneration System (InEK) were compared with outpatient data made available by the Central Institute for Statutory Health Insurance Physicians in Germany (ZI). These were identified on the basis of the coding of a relevant treatment identifier in the incidence quarter or the following quarter. In 2023, he statutory health insurance system covered 74.26 million people, which corresponds to 90% of Germany’s population.
The prevalence was calculated on the basis of the population, as provided by the German Federal Statistical Office (Destatis). Costs for persons treated as inpatients were reported by InEK for 2022. The ZI was not able to make available costs for patients treated as outpatients. For this reason we used as our reference a current publication from the Society for Arthroscopy and Joint Surgery (AGA) (2).
Results
In this study we analyzed 243 682 ruptures of the anterior cruciate ligament that were treated surgically between 2019 and 2024; 62 243 outpatient cases and 181 439 inpatient cases were included in the study. The arithmetic mean of the administrative prevalence between 2019 and 2024 for all cases was 48.39±6.63 surgically treated ACL ruptures per 100 000 population (Table).
Over the course of six years, the prevalence of surgically treated ACL injuries overall declined by 5.5%. During the study period, 25.6% of all cases were treated on an outpatient basis. Among outpatient cases, a rise of 70.8% was observed, whereas inpatient cases declined by 26.8% (Figure).
In inpatient cases the mean length of hospital stay fell from 2.8 (95% confidence interval: [2.78; 2.82]) days to 2.1 [2.06; 2.14] days between 2019 and 2024. For inpatient cases mean costs amounted to €5227.93 per case and for outpatient cases, €1184.40/case. This could potentially lead to annual overall costs of €154 149 457 for inpatient treatment and €15 561 831 for outpatient treatment.
Discussion
The prevalence of surgically treated ACL injuries declined between 2019 and 2024 by 5.5%, from 55.14 ruptures per 100 000 population to 51.25/100 000. Whereas a rise in outpatient ACL treatments by 70.8% was seen between 2019 and 2024, inpatient treatments declined by 26.8% over the same time period. In addition to political and structural changes in the healthcare system, increasing experience with outpatient procedures should be mentioned in the context of increasing outpatient care (2).
During the COVID-19 pandemic, both outpatient and inpatient cases declined; after the pandemic a notable increase was observed especially in outpatient procedures. Furthermore, the pandemic may be responsible for the decline in the overall rate by 5.5%) in procedures. Furthermore, the introduction of hybrid diagnosis related groups (DRGs) created new incentives for outpatient treatment. This trend is also seen in the international comparison (3). In this setting, it is in particular young patients without comorbidities and after relevant preoperative preparation who are suitable for outpatient treatment (2, 4).
The cost differences between outpatient and inpatient ACL reconstructions in our study amounted to €4043.53 per case. Since in 2024, 29,205 cases in Germany were still treated on an inpatient basis, a complete shift to outpatient procedures could yield some annual coast savings of €118 075 815. Ferrari et al. showed in an international meta-analysis cost savings of US$1371 to US$7390 per case for outpatient treatment, which translates into relevant savings for the healthcare system with similar or better postoperative results regarding pain and function, which the study investigated in outpatients and inpatients (5).
The study’s limitations include the fact that the quality depended on the completeness of the billing information. Cases of conservative treatment were not considered because of insufficient coding, as diagnoses without a surgical procedure were insufficiently documented.
Conclusions
While the total number of ACL injuries declined in Germany between 2019 and 2024, the proportion of ACL ruptures treated on an outpatient basis increased by more than 70%. Cost pressures in the healthcare system and the resultant shift of care into the outpatient setting in routine clinical practice have yielded savings of more than €4000 per case.
Dominik Szymski, Werner Krutsch, Johannes Weber, Gero Knapp, Lorenz Huber, Nike Walter, Christian Heiss, Volker Alt, Markus Rupp
Klinik und Poliklinik für Unfallchirurgie, Universitätsklinikum Regensburg, Regensburg (Szymski, Krutsch, Weber, Huber, Walter, Alt)
FIFA Medical Centre of Excellence, Universitätsklinikum Regensburg, Regensburg (Szymski, Krutsch, Weber, Huber, Alt)
SportDocs Franken, Nürnberg (Krutsch)
Klinik und Poliklinik für Unfall-, Hand- und Wiederherstellungschirurgie, Universitätsklinikum Gießen, Gießen (Knapp, Heiss, Rupp)
markus.rupp@chiru.med.uni-giessen.de
Conflict of interest statement
The authors declare that no conflict of interest exists
Manuscript received on 20 March 2025, revised version accepted on 24 July 2025.
Cite this as
Szymski D, Krutsch W, Weber J, Knapp G, Huber L, Walter N, Heiss C, Alt V, Rupp M: The administrative prevalence of in- and outpatient cruciate ligament surgery in Germany. Dtsch Arztebl Int 2025; 122: 623–4. DOI: 10.3238/arztebl.m2025.0141
