Abstract
Background
The purpose of this study was to describe trends in the incidence of open versus arthroscopic management of posterior shoulder instability (PSI) as well as the patients undergoing these procedures in the United States over time.
Methods
The PearlDiver Patient Records Database was utilized for this study. Cases of PSI and surgery were identified via the appropriate ICD-10-CM and CPT codes. Linear regression and two-sample Student's t-test were used to analyze incidence rates, procedure type, number of instability events, and patient age.
Results
A total of 5655 patients were identified as having PSI, undergoing a total of 686 capsulorraphies. The incidence of PSI treated surgically increased across the years of the study at a rate of 0.0293 per 100,000 person-years with an incidence in 2019–2020 greater than in 2016–2018 (p = 0.0151). Patients undergoing arthroscopic capsulorrhaphy were on average younger than those undergoing open capsulorrhaphy (p = 0.0021). Patients experienced a higher number of posterior instability events before open surgery compared to arthroscopic (p = 0.0274).
Discussion
The incidence of surgical treatment of PSI in the United States is steadily rising, with greater than 90% of cases being treated arthroscopically. Those undergoing arthroscopic posterior stabilization are both younger and face fewer instability events prior to surgery.
Keywords: Shoulder, instability, arthroscopy, repair
Introduction
As of yet, the true incidence of posterior shoulder instability (PSI) in the United States has not been well characterized. Various studies estimate that PSI makes up a relatively small portion of all shoulder instability occurrences, ranging between 2% and 10%.1–4 Although it is less common than anterior instability, posterior instability has become recognized as a significant and challenging clinical problem among athletes. 5 The first-line treatment for posterior glenohumeral instability is typically conservative and involves modifications in daily activity as well as physical therapy, barring some exceptions such as traumatic instability and bony pathology which may require surgery. Nevertheless, operative management is often indicated, especially with recurrent instability or in cases of unresponsiveness to nonoperative treatment. 1 A population-based study by Woodmass et al. including 143 patients found the incidence of PSI to be fairly stable over time, but reported an increase in the prevalence of surgical intervention from 53.1% to 87.5% between 1996 and 2015. 3
In recent years, with advances in technology, there has been a shift from open to arthroscopic approach to treatment of shoulder instability. Multiple studies have demonstrated success with arthroscopic posterior stabilization and repair of posterior labral lesions, with evidence of superior outcomes compared to patients undergoing an open procedure.5–7 In addition, arthroscopic posterior stabilization procedures have shown to provide low rates of recurrent instability as well as greater than 90% of patients returning to sport.6–8 In regards to prevalence, a previous study by Owens et al. found the rate of arthroscopic treatment of anterior shoulder instability to be 90% with a decline in the use of open repair over time. 9 Based on these positive outcomes, along with the trends seen in anterior instability treatment, we hypothesize a similar progression in PSI management.
This study uses a large healthcare database (PearlDiver) to examine the trends in surgical management of PSI. The purpose of this study was to determine the prevalence and trends in open versus arthroscopic management of PSI in the United States over time. Additionally, we aimed to explore the number of posterior instability events that preceded surgical intervention. We hypothesized that the majority of posterior instability events managed surgically would be treated arthroscopically, with a decline in use of the open approach; thus, leveraging the advancements made anteriorly.
Materials and methods
Data
The Mariners dataset of the PearlDiver Patient Records Database (www.pearldiverinc.com) was utilized for this study. PearlDiver is a national database containing de-identified medical records encompassing claims billed to all payer types including commercial insurance, Medicare, Medicaid, and self-pay, capturing a patient volume of over 144 million patients between 2010 and Q1 2020.
Patient cohort
Index cases of PSI were identified via the first instance of these ICD-10-CM codes for posterior subluxation (ICD-10-D-S43021A, ICD-10-D-S43022A, and ICD-10-D-S43023A) or posterior dislocation (ICD-10-D-S43024A, ICD-10-D-S43025A, and ICD-10-D-S43026A) of the humerus, identified for patients from 2016 to the first quarter of 2020. Patients with PSI that underwent surgery within 1 year of the diagnosis of their posterior instability were identified via CPT code for either open (CPT-23465) or arthroscopic (CPT-29806) capsulorrhaphy. The incidence of surgical management of posterior instability was computed as the number of surgeries in a given year divided by the number of patients captured in the entire database for that year. Mean ages and the number of posterior instability events preceding a surgery were computed for each surgical cohort of patients.
Statistical analysis
Linear regression was used to study whether the incidence of capsulorraphy or the percent of surgical cases that were arthroscopic increased across the years of the study. Two-sample Student's t-test was used to compare the number of posterior instability events preceding and the mean ages of those undergoing open versus arthroscopic capsulorraphy. Statistical analysis was performed using the PearlDiver software, built on R, Version 1.1.442 (RStudio Inc., Boston, MA, United States). A α value of .05 was set as the level of significance.
Results
Between 2016 and the first quarter of 2020, 5655 patients were identified as having PSI, undergoing a total of 686 capsulorraphies, either open or arthroscopic. In 2016, the incidence of surgical treatment of PSI was 0.37228 per 100,000 person-years, which rose to 0.46976 per 100,000 person-years in 2020 (Table 1), a 26% overall increase. The incidence of PSI treated surgically increased linearly across the years of the study at a rate of 0.0293 per 100,000 person-years with approaching significance (p = 0.0913). The average incidence in 2019–2020 was significantly greater than the incidence in 2016–2018 (p = 0.0151). The percent of surgically treated cases of PSI that were arthroscopic did not increase (p = 0.7300), ranging from 91.7% in 2016 to 95.6% in 2017 (Table 2) (Figure 1). Patients undergoing arthroscopic capsulorrhaphy were on average younger than those undergoing open capsulorrhaphy at 28 years old compared to 34 years old, respectively (p = 0.0021) (Table 3). Patients that had open surgery experienced a higher number of posterior instability events before compared to arthroscopic (2.06 vs. 1.66, p = 0.0274) (Table 4) (Figure 2). Of open surgeries, 7 out of 48 (14.6%) were revision cases and preceded by an arthroscopic capsulorrhaphy.
Table 1.
Percent of posterior shoulder instability (PSI)/dislocation events treated surgically.
| Year | Incidence of surgical treatment (per 100,000 person-years) | Percent surgical cases | Total surgical cases |
|---|---|---|---|
| 2016 | 0.37228 | 11.5 | 144 |
| 2017 | 0.40950 | 12.5 | 158 |
| 2018 | 0.38923 | 11.5 | 148 |
| 2019 | 0.50613 | 13.1 | 190 |
| 2020* | 0.46976 | 11.1 | 46 |
*Data includes only through Q1 of 2020.
Table 2.
Percent of surgically treated posterior shoulder instability (PSI)/dislocation events that are open versus arthroscopic.
| Year | Open cases | Arthroscopic cases | ||
|---|---|---|---|---|
| n | % | n | % | |
| 2016 | 12 | 8.3 | 132 | 91.7 |
| 2017 | a | a | 151 | 95.6 |
| 2018 | 12 | 8.1 | 136 | 91.9 |
| 2019 | 11 | 5.8 | 179 | 94.2 |
| 2020** | a | a | 43 | 93.5 |
The number of patients in a cohort size <11 is not reportable per Health Insurance Portability and Accountability Act (HIPAA).
**Data includes only through Q1 of 2020.
Figure 1.
Incidence of surgically treated posterior shoulder instability (PSI)/dislocation. The figure provides a trend line of the incidence of surgical treatment for PSI between 2016 and 2020. The bars represent the proportion of open stabilizations versus arthroscopic stabilizations for each respective year in the study.
Table 3.
Ages of patients undergoing open versus arthroscopic surgery.
| Open | |
|---|---|
| Mean | 34.09 |
| SD | 11.97 |
| Arthroscopic | |
| Mean | 28.19 |
| SD | 12.39 |
| P-value | 0.0021 |
Table 4.
Number of posterior instability/dislocation events that precede surgery.
| Number of prior instability/dislocation events | Total | Open | Arthroscopic |
|---|---|---|---|
| Mean | 1.69 | 2.06 | 1.66 |
| SD | 1.18 | 1.42 | 1.15 |
| Median | 1 | 1 | 1 |
| IQR | 1 | 2 | 1 |
| P-value | 0.0274 | ||
| Number of events | Number of patients | Open | Scope |
| 1 | 454 | 24 | 434 |
| 2 | 156 | 11 | 148 |
| 3 | 56 | a | 52 |
| 4 | 36 | a | 30 |
| 5 | a | a | a |
| 6 | a | 0 | a |
| 7 | a | a | a |
| 8 | a | 0 | a |
| 9 | 0 | 0 | 0 |
The number of patients in a cohort size <11 is not reportable per Health Insurance Portability and Accountability Act (HIPAA).
Figure 2.
Histogram of number of posterior instability/dislocation events preceding surgery. The figure displays the distribution of the number of posterior shoulder instability (PSI) events experienced by the patients in the study prior by undergoing (a) open stabilization, (b) arthroscopic stabilization, and (c) either open or arthroscopic stabilization.
Discussion
PSI is becoming an increasingly recognized pathologic condition in the shoulder, however, compared to anterior instability where patients typically have subjective complaints of shoulder apprehension and instability, patients with PSI present more frequently with insidious symptoms of pain and weakness. As a result, it is more frequently missed or misdiagnosed. 10 However, over the past decade as clinicians have become more familiarized with the diagnosis, it is being diagnosed at an increasing rate and subsequently treated surgically with promising outcomes. To better understand the trends in the management of PSI in the United States, in the present study we sought to examine the trends in the incidence of open and arthroscopic management of PSI using a nationally representative patient population. Our findings demonstrated a 26% increase in the number of patients undergoing operative intervention for PSI. Furthermore, we found the majority of patients to be managed arthroscopically versus open, accounting for 91.7% to 95.6% of all cases during the study period. In contrast to open stabilization, patients that underwent arthroscopic stabilization were more likely to be of younger age and experienced fewer instability events prior to surgical intervention.
To date, there have been many different operative procedures described for the management of PSI ranging from open stabilization with a capsular shift + /− osteotomy and bone block procedures, to arthroscopic stabilization. In contrast to anterior instability, historically outcomes following arthroscopic stabilization were less predictable, however, with the development of suture anchors and improved arthroscopic techniques, more surgeons are opting for arthroscopic procedures with promising results. 11 The findings in the present study are the first to confirm this with >90% of PSI patients managed with arthroscopic stabilization. While there continues to be a scarcity of long-term data investigating outcomes following arthroscopic stabilization, studies on smaller cohorts have demonstrated favorable results. In a series of 91 athletes, Bradley et al. demonstrated patients undergoing arthroscopic stabilization to have a 39% decline in pain scores, 32% increase in mean functional scores, and 35% increase in mean ASES scores. Furthermore, only 8% of patients did not believe their surgery was worthwhile and underwent revision surgery for continued pain, decreased function, or recurrent instability. 12 In 2015, Arner et al. demonstrated favorable outcomes in 56 American football players with a 93% RTP rate with 96% of athletes satisfied with their operation. 13
In the present study, we demonstrated open stabilization procedures to account for only 6.6% of all cases during the study period. In comparison to patients undergoing arthroscopic procedures, patients undergoing open stabilization were more likely to be of older age at a mean of 34 years, experienced an increased number of PSI events, and were more likely to have a history of previous arthroscopic stabilization. A majority of the data that exists to date regarding indications and outcomes for open stabilization for PSI comes from older case series with mixed results.6,11,14 Given the lack of randomized control trials comparing open versus arthroscopic stabilization for PSI, there is little data to suggest which patients may benefit from one approach versus the other, as well as when an osteotomy or bone block procedure may be indicated. Consequently, much of the decision making for PSI has been extrapolated based on the anterior instability data. Some authors suggest open capsulorrhaphy should be used following the failure of an arthroscopic procedure or when patients have no obvious labral detachment or when patients have associated inferior instability suggesting excessive capsular laxity.15,16 In a more recent meta-analysis of open and arthroscopic stabilization for PSI, DeLong et al. demonstrated a trend toward more favorable results following arthroscopic techniques for recurrence rate (8% vs. 19%), subjective stability (91% vs. 80%), patient satisfaction (94% vs. 86%), return to sport at any level (92% vs. 66%), and return to the previous level of play (67% vs. 37%). 6 However, to optimize outcomes in patients presenting with PSI, it is imperative that additional prospective studies be performed to better understand which patient and injury characteristics may benefit more from open rather than arthroscopic stabilization, such as age, activity level, sports played, and various soft tissue and boney abnormalities. Such information will allow surgeons to better define the indications for each approach and optimize patient outcomes.
Limitations
The present study is not without limitations. Inherent to all database studies, our data is dependent on accurate coding by providers and insurance companies, therefore it is possible that errors could have been made regarding patient diagnoses and the procedures performed. Furthermore, the present database lacks important clinical information that may influence how a provider manages a patient presenting with PSI. For example, the present study was unable to elucidate how associated pathoanatomy such as glenoid retroversion, glenoid bone loss, or reverse Hill–Sachs lesions influence providers’ decision regarding open versus arthroscopic stabilization. Additionally, in the present study, we looked at isolated open and arthroscopic capsulorrhaphy, however, we did not investigate trends in the number of boney augmentation procedures or osteotomies performed in patients with PSI. Despite the present limitations, we believe our study provides valuable information to readers as it is the only study to date which used a nationally representative sample to examine trends in the management of PSI and therefore avoids the limitations and biases observed in similar studies published based on data from a single institution.
Conclusion
In summary, we present the largest study to date examining trends in the surgical management of PSI using a nationally representative sample. In the present study, we observed a steady increase in the incidence of surgical management of PSI with a large majority of patients undergoing arthroscopic stabilization compared to open stabilization. Furthermore, patients in the present study that did undergo open stabilization were more likely to be of older age, have an increased number of instability events prior to surgical intervention, and were also more likely to have a previous history of arthroscopic stabilization. While the present study provides a valuable insight into the current landscape of surgically managed posterior instability, further prospective studies investigating injury-related and patient-related factors which increase the risk of failure following arthroscopic stabilization are required to better define surgical indications and optimize outcomes in patients presenting with PSI.
Footnotes
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
ORCID iDs: Nicholas J Lemme https://orcid.org/0000-0002-3136-7177
Ozair Meghani https://orcid.org/0000-0002-8295-3635
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