Surgical trends in elderly patients with proximal humeral fractures in South Korea: a population-based study

Proximal humeral fractures (PHFs) account for approximately 5% of all fractures, and are the third most common fractures in patients older than 65 years following hip and distal radius fractures [1, 2]. Although nondisplaced or minimally displaced PHFs can be treated nonoperatively, displaced or unstable PHFs often require surgical treatment [3, 4]. The proportion of cases with PHFs undergoing surgical treatment has been growing over recent years, and in New York State approximately 30% of PHFs were treated surgically in 2010 [5–7].

Surgical treatments for PHFs include open reduction and internal fixation (ORIF), closed reduction and internal fixation (CRIF), hemiarthroplasty (HA), and reverse shoulder arthroplasty (RSA) (Fig. 1) [8]. Since the development of the biomechanically more advantageous locking plates and locking intramedullary nails, the surgical indications for ORIF have been extended to elderly patients with osteoporosis [9, 10]. However, for both devices, high implant-related complication rates and reoperation rates have been reported [11–13]. Although HA may be an attractive treatment method for comminuted fractures in elderly patients, it is known to have poor outcomes when nonunion or malunion of the tuberosity occurs [14, 15]. RSA has recently been used to treat PHFs in elderly patients and reported to produce satisfactory outcomes regardless of whether there is union of the tuberosity [16, 17]. However, there is still no clear evidence or consensus regarding the most appropriate method of surgery for different fracture types [18, 19]. Therefore, it is known that there are large regional variations in the methods used for treatment [7, 8]. To the best of our knowledge, there has not been any report on the treatment trends for PHFs in Asian populations.

Thus, the objective of this study was to investigate national surgical trends in elderly patients aged ≥65 years with PHFs in South Korea based on an analysis of nationwide data acquired from the Korean Health Insurance Review and Assessment Service (HIRA) database. Our hypotheses were as follows: first, the proportion of surgical treatments for PHFs would increase; and second, the use of HA would decrease while that of RSA would increase in the treatment of PHFs.

Conservative treatment was the most common treatment method (67.6%) followed by ORIF (26.2%), CRIF (3.3%), HA (2.1%), and RSA (0.7%). The overall operative rate for PHFs increased steadily from 24.6% in 2008 to 36.8% in 2016 (Fig. 2, p < 0.001). The rate of cases treated with ORIF tended to increase each year, from 71.5% of the overall surgeries in 2008 to 85.6% in 2016, while the rate of CRIF decreased from 19.9% in 2008 to 4.5% in 2016 (Fig. 3).

The rate of cases involving arthroplasty procedures increased slightly, from 8.6% of cases of operative PHFs in 2008 to 9.9% in 2016 (p < 0.001). In terms of type of arthroplasty procedure, the rate of cases treated with RSA tended to increase significantly each year, from 8.1% of the overall arthroplasty procedures performed in 2008 to 52.0% in 2016, while the rate of cases treated using HA decreased (Fig. 4, p < 0.001). The proportion of RSA of the overall procedures has shown to increase especially significant in patients aged 80 years or older (Table 3). In this population, the proportion of use of RSA increased dramatically, from 1% of the overall procedures in 2008 to 9% in 2016 (p < 0.001).

Years	Patients aged 65 to 79				Patients older than 80				p-valuea
	ORIF (%)	CRIF (%)	HA (%)	RSA (%)	ORIF (%)	CRIF (%)	HA (%)	RSA (%)
2008	73.4	18.4	7.6	0.6	65.9	24.1	9.0	1.0	0.036
2016	88.4	4.0	4.3	3.3	79.5	5.7	5.8	9.0	< 0.001
p-value	< 0.001				< 0.001

^ap values were estimated by comparing between age groups in the same year

The mean hospitalization cost was the highest for RSA (7017 USD), followed by HA (6124 USD), ORIF (3454 USD), and CRIF (2280 USD). The mean hospitalization cost for patients who underwent surgical treatment for PHFs significantly increased from 3244 USD in 2008 to 4125 USD in 2016 (r = 0.907, p < 0.001).

In this study, we used nationwide data to analyse surgical trends among patients aged 65 years or older with PHFs in South Korea. There were no significant changes in the age-adjusted incidence rates of PHF during the study period, and the proportion of surgical treatments increased annually. Among the different surgical methods, the proportion of use of ORIF gradually increased up to 85.6% of the overall procedures performed in 2016. Among arthroplasty procedures, the proportion of use of RSA increased annually whereas that of HA decreased; this trend was more evident among patients aged 80 years or older.

Although the number of cases of PHF per year significantly increased from 2008 to 2016, there were no significant changes in the age-adjusted incidence rates of PHFs. This may be because the incidence rates were calculated among the parent population, which consisted of persons aged 65 years or older; therefore, although the number of cases of PHF increased, the parent population also increased due to population aging. This resulted in no significant change in the incidence rates. In fact, according to the Statistics Korea website, the estimated total population size of persons aged 65 years or older significantly increased from 4,988,592 in 2008 to 6,762,842 in 2016. If the incidence rate of PHFs had been calculated in all age groups without age-adjusted in this study, it would have been expected to increase steadily during the study period as population aging continued [25].

Excellent outcomes can be obtained for nondisplaced or minimally displaced PHFs using conservative treatment [26]. There is insufficient evidence that surgical treatments produce better outcomes for displaced PHFs than conservative treatments [27, 28]. However, in this study, the proportion of use of surgical treatments was observed to gradually increase from 24.6% in 2008 to 36.8% in 2016. In other population-based studies, the proportion of surgical treatments for PHFs was also observed to increase over the years [5, 8]. It appears that the preference for surgical treatments increased due to various factors such as the development of new surgical techniques and instruments, better understanding about the importance of accurate reduction of the greater tuberosity, and an increased number of surgeons who can surgically treat PHFs [7, 20, 23, 29].

The rate of use of ORIF consistently increased during the study period, whereas that of CRIF decreased. Huttunen et al. [23] reported that the rate of ORIF using plates increased two-fold from 2002, when locking plates were introduced, to 2009. Locking plates produce greater angular stability and screw anchorage in osteoporotic bones [30], and thus, have stronger holding power on the humeral head than conventional plates [31]. In addition, the intramedullary nail can be also a useful tool for PHF fixation; its minimally invasive approach, secure tuberosity-specific locking screws, and ability for early rehabilitation often yields satisfactory clinical outcomes [10, 12]. Although CRIF has the advantage of less soft tissue injuries, the rate of reduction loss following CRIF has been reported to be up to 27%, and the rate of fixation failure is higher in elderly patients with osteoporosis [32]. It appears that the rate of use of ORIF has increased because many surgeons in South Korea prefer anatomic reduction and rigid fixation for early range of motion exercise.

Elderly patients with 3- and 4-part PHFs have increased rates of avascular necrosis of the humeral head and increased complication rates following ORIF [12, 33, 34]. Therefore, arthroplasty procedures may be a good alternative for these fracture types. In this study, the proportion of use of RSA increased whereas that of HA decreased among the arthroplasty procedures used. HA is known to have poor functional outcomes in elderly patients when nonunion or malunion of the tuberosity occurs [14, 15]. The rate of nonunion of the tuberosity has been reported to be as high as 65% [16, 35]. Conversely, RSA has excellent functional outcomes regardless of tuberosity union or malunion [16, 17], and according to other population-based studies, the preference for RSA has been increasing [8, 36]. The preference for RSA has also been increasing in South Korea; RSA was preferred over HA in 2016.

The preference for RSA over HA was especially high among patients aged 80 years or older. This may be because of the higher prevalence rotator cuff disease among older patients [37] and the criteria of insurance coverage for shoulder arthroplasty in South Korea. Before October 2017, only elderly patients aged ≥80 years with 3- or 4-part PHFs received insurance coverage for RSA in South Korea. This system was a major constraint for surgeons to choose the surgical treatment of patients aged < 80 with PHFs in South Korea. However, after October 2017, the criteria of insurance coverage for RSA was changed to include patients aged 70 years or older. Thus, the preference for RSA is expected to increase in younger age groups.

The mean hospitalization cost for patients who underwent surgical treatment for PHFs significantly increased from 2008 to 2016. One reason for this increase in cost may be the high costs of implants for ORIF and RSA, the preference for which has increased. To accurately analyze the cost-effectiveness of surgical methods, costs for reoperation, improving quality of life, and long-term patient satisfaction must be considered in addition to hospitalization costs. Additional research is needed to comprehensively analyze these factors.

Although this study employed a large sample size based on a nationwide database, it also had some limitations. First, we only included the data obtained when the ICD-10 code was first entered for each patient. Although we could avoid multiple counting using this method, PHFs that occurred twice or more in a single patient during the study period could be measured as a single PHF, resulting in the underestimation of the number of PHFs. Second, there is no separate operation code for RSA in South Korea. In South Korea, the same operation code is registered for total shoulder arthroplasty and RSA (Table 1). However, we believe that total shoulder arthroplasty is rarely performed for PHFs [6]. Third, because the HIRA data provided no information on clinical outcomes, the clinical outcomes between operative procedures were not comparable in this study. Fourth, the insurance coverage served as a bias that could have caused high preference for RSA over HA in only patients over 80 years of age. If there had been no insurance bias, the RSA preference might have been higher than HA even for those under 80 years of age in 2016. Finally, there are possibilities of some code errors in large databases.

In South Korea, the proportion of use of surgical treatments for PHFs tended to increase. In addition, ORIF had the highest proportion among surgical treatments, and this value increased every year. On the other hand, the use of CRIF for treatment of PHFs decreased. Among arthroplasty procedures, the proportion of use of RSA tended to increase; higher preference for RSA over HA was observed in 2016.