The Surgical Treatment of Proximal Humeral Fractures in Elderly Patients

An Analysis of the Long-Term Course of Locked Plate Fixation and Reverse Total Shoulder Arthroplasty Based on Health Insurance Data

Background: The goal of this study is to compare mortality, major adverse events, and complication rates after the surgical treatment of proximal humeral fractures with locked plate fixation (LPF) versus reverse total shoulder arthroplasty (RTSA) in elderly patients.

Methods: Health insurance data from patients aged 65 and above for the period January 2010 to September 2018 were retrospectively evaluated. The median follow-up duration after LPF (40 419 patients) or RTSA (13 552 patients) was 52 months. Hazard ratios adapted to the patients’ risk profiles were determined with the aid of multivariable Cox regression models. The p-values were adjusted using the Bonferroni–Holm method.

Results: After adaptation to the patients’ risk profiles, reverse shoulder replacement showed statistically significantly lower mortality (HR 0.92, 95% confidence interval [0.88; 0.95]; p <0.001) and fewer major adverse events (HR 0.92 [0.89; 0.95]; p<0.001). Eight years after surgery, the risk of surgical complications was twice as high for LPF (12.2% [11.9; 12.7]; HR for RTSA versus LPF 0.5 [0.46; 0.55]; p<0.001 for both), with 3.8% [3.6; 4.0] of the patients receiving a secondary RTSA. Surgical complications were more common (p<0.05) in patients with a diagnosis of osteoporosis, obesity, alcohol abuse, chronic polyarthritis, or frozen shoulder.

Conclusion: The long-term findings are in agreement with clinical short-term findings from other studies and support the current trend toward more liberal use of reverse shoulder replacements in elderly patients.

Proximal humeral fracture (PHF) is the third most commonly occurring fracture among the elderly and is often associated with osteoporosis (1, 2). A marked increase in osteoporotic fractures is expected in coming decades due to demographic change (3, 4). The surgical options for treatment of PHF include locked plate fixation (LPF) and reverse total shoulder arthroplasty (RTSA) (5, 6). In recent years, RTSA has become increasingly popular among trauma surgeons (7). To date, little information is available regarding the medium- or long-term results of these two treatment options to support clinical decision-making (8).

At present, open reduction and internal fixation by means of LPF is the most frequently performed operation following PHF (9). However, complications such as loss of reduction, consolidation in malunion, pseudarthrosis, or avascular necrosis can occur, particularly in elderly patients with reduced bone quality (10). Alternatively, RTSA offers good pain relief, function, and patient satisfaction (11). Recent studies—a multicenter, randomized controlled trail, a retrospective case- control study, and a retrospective matched pair analysis—suggest better short-term clinical outcomes of RTSA than of LPF (12, 13, 14). The rapidly rising number of RTSA implantations following PHF in the elderly reflects surgeon satisfaction with the procedure and the outcome (15). Another advantage of RTSA is less reliance on a functioning rotator cuff, as the deltoid muscle predominantly controls shoulder movement (Figure 1) (13). However, RTSA is a relatively novel, complex procedure requiring adequate facilities and appropriately trained staff (16). There is currently no consensus on the best surgical treatment even among experienced shoulder surgeons (17, 18). Hence, analysis of complications and mortality is necessary in order to identify both patients at high risk and those likely to benefit particularly from one or the other of the two procedures.

Figure 1

Reverse total shoulder arthroplasty (RTSA)

The objective of this study is therefore to evaluate and to compare overall survival and complications after RTSA and LPF for PHF in elderly patients. We hypothesized that RTSA is associated with higher mortality and more major adverse events (MAE) than LPF, but fewer surgical complications and lower readmission rates for revision surgery.

Materials and methods

Data pool and patient cohort

The German healthcare system is dominated by the statutory health insurance (GKV) sector, covering nearly 90% of the 82 million citizens. The remuneration of health care services is specified and regulated by mandatory coding instructions, including encoding of diagnoses (International Statistical Classification of Diseases, German Modification; ICD-10 GM) and procedures (German procedure classification; OPS).

For this study, data were obtained from the Federal Association of the Local Health Insurance Funds (Allgemeine Ortskrankenkasse, AOK), covering about 26.5 million insurance holders (almost 36.4% of the entire German population, as of January 2019). Within an index period from January 2010 to September 2018, all elderly patients (age at hospitalization ≥ 65 years) who were treated with LPF (OPS 5-794.k1 or 5-794.21) or RTSA (OPS 5-824.21) and had a coded diagnosis of PHF (ICD S42.2) were included for further analysis (n= 53 971, Figure 2). All patients discharged alive were followed up from discharge of the initial hospitalization to the end of the observation period (exit from database, death, or end of study). The median duration of follow-up was 52 months (IQR 81–26 months), with 42% of the patients observed for more than 5 years. Retrospective patient data were available for the period from January 2008 to December 2018. Baseline characteristics (e.g., osteoporosis, diabetes mellitus, dementia) were determined according to primary/secondary diagnoses and procedures during the index hospitalization together with inpatient and outpatient data from the previous 24 months (eTable 1). The Charlson comorbidity index (CCI) was calculated as defined by Quan et al. and adapted to the German ICD-10 as described by Strausberg and Hagn (e1, e2, e3). Data on pharmacotherapy before index surgery (any anticoagulants, vitamin D/calcium, and bisphosphonates) were defined using the Anatomical Therapeutic Chemical classification system (ATC).

Figure 2

Flow diagram

Table

Cumulative incidences/event rates (95% confidence intervals) of various endpoints by treatment group

eTable 1

Comorbidities, pharmacotherapy, and complications during index case depending on treatment group

The primary endpoints were defined as overall survival (OS), MAE (resuscitation, acute myocardial infarction, stroke, sepsis, acute renal failure, acute liver failure, acute respiratory distress syndrome, or death), thromboembolic events (or death), general complications (or death), any surgical complications, any reoperation, and minor outpatient complications. Details of surgical complications and secondary endpoints can be found in eTable 2.

eTable 2

Cumulative incidences (95% confidence interval) for subitems of surgical and general complications by treatment group, determined by Nelson- Aalen estimators

Statistical methods

Analysis of all primary endpoints was performed using multivariable Cox regression models including treatment group, age, sex, year of index surgery and comorbidities. A detailed description of the statistical analyses can be found in the eMethods.

Results

We identified n = 53 971 patients with a proximal humeral fracture who were treated with LPF or RTSA between January 2010 and September 2018 and were discharged alive. RTSA was performed in 13 552 patients (25.1%) and LPF in 40 419 patients (74.9%) (eTable 1), with RTSA showing a fivefold increase over the course of the observation period (19). The patients treated with RTSA were older (median age 80 [IQR 9] vs. 78 [IQR 10], p<0.001), a higher proportion of them were female (RTSA 87.0% vs. LPF 83.9%, p<0.001), and more of them had comorbidities (CCI>5: RTSA 17.5% vs. LPF 14.3%, p<0.001; eTable 1).

Overall survival and major adverse events

As shown in Table 1, patients treated with RTSA had higher mortality after the index operation (p<0.001). After adjustment for the patients’ risk profiles, however, those treated with LPF had significantly greater overall mortality (hazard ratio [HR] for RTSA vs. LPF 0.92, 95% confidence interval [0.88; 0.95]; p<0.001; Figure 3). Similar associations were found for the occurrence of MAE during follow-up. Patients treated with RTSA had significantly higher rates of MAE (Table; p<0.001), but after adjustment for the patients’ risk profiles the multivariable Cox regression model showed a significantly higher risk of MAE for patients treated with LPF (HR for RTSA vs. LPF: 0.92 [0.89; 0.95]; p<0.001; Figure 3). The survival probabilities estimated from the Cox regression for OS, MAE, thromboembolic event (or death) and general complications (or death), presented in eFigure 1, show an elevated risk for all events in patients initially treated with LPF (all p<0.001). The unadjusted (univariate) event rates were lower for patients with LPF, which can be explained by differences in sex, age, and comorbidities (all p<0.001; Table).

Figure 3

Association of treatment group with various endpoints during follow-up

eFigure 1

Adjusted survival curves

Surgical outcomes and risk profile

Patients initially treated with LPF had significantly higher rates of surgical complications during follow-up than those treated with RTSA (LPF: 1-year rate 9.5%, after 8 years 12.2%, RTSA: 1-year rate 4.0%, after 8 years 7.2% ; p<0.001). Including the initial hospital stay for fracture treatment, the rates for any surgical complications after RTSA and LPF were greater (Table), with higher rates for patients treated with LPF (p<0.001). By 5 years after discharge, 3.7% [3.5; 3.9] of patients initially treated with LPF had undergone secondary RTSA.

In a multivariable Cox regression analysis, RTSA was also associated with a significantly lower risk of surgical complications (HR for RTSA vs. LPF: 0.50 [0.46; 0.55]; p<0.001). The adjusted cumulative incidence function for surgical complications, plotted in eFigure 1, shows the twofold higher risk of surgical complications for LPF treatment. Similar results were found for reoperation during follow-up including only inpatient-coded OPS codes for surgical interventions on the same shoulder: LPF had higher event rates (p<0.001; Table), which is also confirmed by the results of the multivariable Cox regression analysis (p<0.001; Figure 3).

The multivariable Cox regression analysis was also used to identify unfavorable patient risk profiles (risk profile including comorbidities and medication at the time of the index surgery) for surgical complications during follow-up (eFigure 2). It emerged that patients with a coded diagnosis of osteoporosis (HR 1.12), obesity (HR 1.17), alcohol abuse (HR 1.26), chronic polyarthritis (HR 1.16) or frozen shoulder (HR 1.17) had an elevated risk of surgical complications (all p<0.05).

eFigure 2

Forest plot of patient’s risk profile for surgical complications

Of interest, surgical complications during the index treatment were associated with an increased risk of further surgical complications during follow-up (HR 1.64 [1.50; 1.79], p<0.001). Moreover, it was found that age (per year) at index surgery (HR 0.96, [0.96; 0.97], p<0.001) and dementia (HR 0.76, [0.68; 0.84], p<0.001) were associated with a decreased risk of surgical complications (eFigure 2), indicating that these patients less frequently received secondary surgery after their initial treatment.

Secondary osteoporosis-associated fractures during follow-up

By 8 years after discharge, 34.8% [34.2; 35.4] of the observed patients had experienced at least one secondary osteoporosis-associated fracture. Moreover, 9.1% [8.7; 9.4] of the patients had a third fracture associated with osteoporosis within 8 years of the index treatment (eTable 2).

Discussion

Proximal humeral fractures in the elderly cause not only pain and loss of function, autonomy, and quality of life, but also increased mortality (20). Studies comparing surgical treatment options show an obvious age distribution with younger patients receiving LPF and older patients being treated with RTSA (21). Therefore, it is unknown whether the reported death rates are the effect of treatment choice or of age distribution. While the data of the present study confirm higher absolute death rates after RTSA throughout all years of follow-up (Table), multivariable Cox regression analysis of 53,971 patients adjusting for age, sex, and comorbidity profiles revealed longer overall survival after RTSA. Hence, the presented long-term survival rates support the current trend towards more liberal use of RTSA in the elderly.

Postoperative nonsurgical complications after shoulder arthroplasty range between 1.2% and 8% and comprise mainly cardiovascular and cerebrovascular insults, pneumonia, and sepsis (22, 23). Alentorn-Geli et al. report stroke in 3% and myocardial infarction in 8% of cases after revision of RTSA in patients more than 80 years old; the rate of perioperative complications among patients above 80 years of age was summarized as between 0% and 9% (24). To the best of our knowledge, the present study is the first large-cohort, long-term analysis of real-world data systematically comparing the occurrence of major adverse events associated with RTSA and LPF.

In contrast to the above-mentioned studies, which focus on perioperative complications, the 12.9% rate of major adverse events in this study includes all events during the first year following discharge after index surgery. Of particular interest are the 5-year MAE rates of 44.7% and 50.0% for LPF and RTSA respectively, which again highlight the high morbidity of elderly patients with proximal humeral fracture (25, 26). With respect to thromboembolic events after surgical treatment of PHF, the literature reports rates between 0 and 5.1% with a maximum follow-up of 6 months (27, 28, 29). On long-term follow-up the rate of thromboembolic events in the presented study is 11.3% after 1 year, 41.8% after 5 years, and 59.5% after 8 years, showing the high vulnerability of the geriatric cohort. This observation is supported by the CCI, an important determinant of medical complications (30). In this long-term analysis, multivariable Cox regression reveals a lower risk of MAE and thromboembolic events after RTSA than after LPF. Analysis of MAE and thromboembolic events adjusted for patient comorbidities demonstrates better outcomes for RTSA than for LPF.

Surgical complications after LPF, such as screw cut-out, intra-articular screw perforation, avascular humeral head necrosis, reabsorption of tuberosities, loss of fixation, and malalignment remain unclarified. High average complication rates of 49% and revision rates of 25% are reported in the literature (5, 31). The surgical complications of RTSA include instability, infection, loosening, periprosthetic fractures and disengagement of components. The complication rates stated in literature vary widely and range as high as 68%, with the impact of the learning curve much discussed but ultimately unclear (32). For patients above 65 years of age there exist only small studies with an observation period of 2 years; these suggest higher complication rates for LPF (13, 33). The data of the present study, comprising 40 419 patients treated with LPF and 13 552 with RTSA, provide a clearer picture: over the whole 8-year period analyzed, patients treated with LPF have a twofold higher risk of surgical complications. Within those 8 years, 3.8% of the patients treated with LPF underwent conversion to RTSA, a procedure associated with worse clinical outcomes than primary RTSA (34). The rates of surgical complications and revision procedures observed in our study (Table; each around 10% or less after 2 years) were similar to those of the most recently published retrospective and prospective randomized comparative studies (8, 12). The factors associated with an increased risk of surgical complications are chronic polyarthritis, obesity, coded alcohol abuse, frozen shoulder, and hypertension, in agreement with the literature (35, 36, 37). Age and dementia, however, were associated with a decreased risk for surgical complications, which can only be explained by less frequent resort to secondary interventions (38).

One striking finding is the inadequacy in diagnosis and treatment of osteoporosis after fragility fractures (39). Despite the existence of established treatment guidelines for osteoporosis and the widespread awareness of the osteoporosis treatment gap, the rate of patients with at least one subsequent osteoporosis-associated fracture of the hip, wrist, or spine was almost 35% at 8-year follow-up. However, in order to avoid recoding, certain ICD codes were not taken into account, e.g., repeated proximal humeral fractures or osteoporosis with pathological fracture. The proportion of patients affected could therefore be even higher. Similar rates of osteoporotic refractures have recently been observed in Korea (40). These alarming findings show that awareness of osteoporosis and its treatment must be improved and that prevention strategies are imperative in order to decrease morbidity and mortality in the elderly.

Limitations

Due to the legal obligations in Germany, the data of German health insurance companies are characterized by their completeness and validity. However, they are insurance data collected for financial reasons and are not obtained explicitly for research purposes. Hence, upcoding might be a possible source of bias. However, this effect would apply similarly to both groups. Furthermore, the database provides no information on the reason for treating each individual patient with RTSA or LPF. Therefore, selection bias may exist. Furthermore, there may be a mismatch between the billing date of drugs and the time of their use.

The most important finding of this study is that after adjustment for each individual patient’s comorbidity profile, RTSA was associated with more favorable outcomes than LPF in terms of overall survival, major adverse events, general and surgical complications, and rate of revision procedures. However, prospective randomized studies are necessary to confirm our retrospective data.

Acknowledgments

We thank the AOK Research Institute (WIdO) for providing the data used in this analysis. Furthermore, we would like to express our sincere gratitude to Prof. Dr. Martin Langer for designing Figure 1.

Conflict of interest statement
J. Christoph Katthagen has received research funding from Arthrex.

The remaining authors declare that no conflict of interest exists.

Manuscript received on 23 April 2021, revised version accepted on
24 August 2021

Corresponding author
PD Dr. med. J. Christoph Katthagen
Klinik für Unfall-, Hand- und Wiederherstellungschirurgie
Universitätsklinikum Münster
Albert-Schweitzer-Campus 1, Gebäude W1, 48149 Münster, Germany

Cite this as:
Stolberg-Stolberg J, Köppe J, Rischen R, Freistühler M, Faldum A, Katthagen JC, Raschke MJ: The surgical treatment of proximal humeral fractures in elderly patients—an analysis of the long-term course of locked plate fixation and reverse total shoulder arthroplasty based on health insurance data. Dtsch Arztebl Int 2021; 118: 817–23. DOI: 10.3238/arztebl.m2021.0326

►Supplementary material

eReferences, eMethods, eTables, eFigures:
www.aerzteblatt-international.de/m2021.0326

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