Abstract
Background
US Food and Drug Administration Investigation Device Exemption studies and academic journals emphasize the importance of two-year follow-up data in reporting outcomes of total shoulder arthroplasty, but there is limited data evaluating appropriate follow-up length. We aim to evaluate change in postoperative outcomes and complications between one and two years following anatomic and reverse total shoulder arthroplasties.
Methods
We retrospectively identified 250 patients who underwent anatomic and reverse total shoulder arthroplasties between 2013 and 2016 from a single surgeon arthroplasty registry. Patients without both one- and two-year follow-up data were excluded. We compared American Shoulder and Elbow Surgeons (ASES) score, Visual Analog Scale for pain, and goniometer-measured range of motion.
Results
Patient-reported outcome measurements (p > 0.05) did not change between one and two years postoperatively following both reverse (n = 146) and anatomic (n = 104) total shoulder arthroplasties. Range of motion increased slightly (p < 0.05), but this change was not clinically relevant. There were no additional complications.
Discussion
Minimum two-year clinical follow-up may not be necessary for future shoulder arthroplasty Investigation Device Exemption and other peer-reviewed investigations. Patient-reported outcomes (ASES and pain score) and range of motion plateau at one year postoperatively without additional complications. One-year follow-up is an acceptable minimum follow-up length.
Level of evidence
Level III—retrospective analysis.
Keywords: anatomic total shoulder arthroplasty, reverse total shoulder arthroplasty, patient-reported outcomes, range of motion, minimum follow-up, timeline of recovery
Introduction
Anatomic (TSA) and reverse (RSA) total shoulder arthroplasties are both effective treatments for a wide spectrum of shoulder pathologies providing improvement in pain and function.1–6 While demand for shoulder arthroplasty has increased over the past two decades3,7–12 there is a paucity of data tracking either the speed and process of recovery or the appropriate follow-up length.13,14 It is likely that the investigational minimum follow-up of two-years for Investigation Device Exemption (IDE) studies10,15 and peer-reviewed patient outcome-based studies is not grounded in literature involving shoulder arthroplasty-specific epistemology. This standard likely originated from hip and knee arthroplasty studies which suggest that patients continue to improve postoperatively through the two-year mark. 16
While longitudinal data should continue to be monitored, as a standard, minimum two-year follow-up represents an onerous burden on clinicians, researchers, and patients. The purpose of this study is to investigate the differences in the timeline of recovery between one and two years following primary TSA and RSA. We hypothesize that there will be little change in patient-reported outcomes, range of motion (ROM), and complication rates between one and two years postoperatively for both TSA and RSA.
Methodology
Study population
Following institutional review board approval, we retrospectively reviewed patient data from a prospectively maintained registry. The patient population was comprised of men and women who underwent primary TSA and RSA between 2013 and 2016. Goniometer-measured forward elevation, external and internal rotation in adduction, American Shoulder and Elbow Surgeons (ASES) score, Visual Analog Scale (VAS) for pain were recorded at each preoperative and postoperative visit.
All surgeries were performed by the senior author (AJ) using a standard deltopectoral approach. The postoperative rehabilitation protocol was identical for both TSA and RSA patients. Patients remained immobilized in a sling for six weeks postoperatively, and were encouraged to begin elbow, wrist, and hand ROM exercises immediately after surgery. Patients did not undergo formal physical therapy but were instructed to initiate forward flexion exercises at two weeks postoperatively, followed by internal and external rotation exercises at six weeks postoperatively, and strengthening at three months postoperatively.
Statistical analysis
Only patients with both one-year and two-year follow-up data were included. Paired t test and parametric analysis were used to evaluate the difference between one-year and two-year outcomes, where appropriate. Prior to analysis, internal rotation was converted to a numeric scale according to Levy et al. 13 In this scale, internal rotation measurements with the arm in adduction were converted to a 10-point scale. Two points were assigned if the patient could reach the buttock/greater trochanter level with active internal rotation. Additionally, the following points are assigned for active internal rotation: sacrum to L4: 4 points, L3–L1: 6 points, T12–T8: 8 points, T7–T1: 10 points. We analyzed TSA and RSA patients separately, as well as both patient populations combined. All comparisons were completed by a biostatistician.
Results
Patient characteristics
A total of 250 shoulders (104 TSA and 146 RSA) met the inclusion criteria. Full patient demographics are included in Table 1. RSA patients were more likely to be female, older, insured by Medicare, be prescribed narcotics preoperatively, and have an American Society of Anesthesiologist's (ASA) score of 3 (p = 0.001) when compared to their TSA counterparts. A total of 96.2% of patients undergoing TSA had a recorded diagnosis of degenerative joint disease (DJD) and 3.8% had other diagnoses (consisting of avascular necrosis and rheumatoid arthritis), whereas 53.4% of patients had DJD, 19.2% had rotator cuff arthropathy (RCA), 15.8% had irreparable rotator cuff tears following RSA, and 11.6% had other diagnoses (avascular necrosis, fracture nonunion, rheumatoid arthritis, and chronic dislocation; Table 1). There were no clinically or statistically significant differences in preoperative ASES scores between the two groups (Table 1).
Table 1.
Patient characteristics by surgery type.
| Anatomic total shoulder arthroplasty (TSA)
n = 104 |
Reverse total shoulder arthroplasty (RSA)
n = 146 |
||||
|---|---|---|---|---|---|
| N | % | N | % | p value* | |
| Sex | |||||
| Male | 52 | 50.0 | 52 | 35.6 | |
| Female | 52 | 50.0 | 94 | 64.4 | 0.019 |
| Age, years | |||||
| <55 | 10 | 9.6 | 4 | 2.7 | |
| 55–64 | 42 | 40.4 | 23 | 15.8 | |
| 65–74 | 46 | 44.2 | 71 | 48.6 | |
| 75+ | 6 | 5.8 | 48 | 32.9 | <.0001 |
| Body mass index (BMI), kg/m 2 | |||||
| Normal (<25) | 20 | 19.2 | 32 | 21.9 | |
| Overweight (25–29.9) | 31 | 29.8 | 51 | 34.9 | |
| Obese I (30–34.9) | 31 | 29.8 | 32 | 21.9 | |
| Obese II (≥35) | 22 | 21.2 | 30 | 20.5 | 0.296 |
| Primary diagnosis | |||||
| DJD | 100 | 96.2 | 78 | 53.4 | |
| RCA | 0 | 0.0 | 28 | 19.2 | |
| RCT | 0 | 0.0 | 23 | 15.8 | |
| Other | 4 | 3.8 | 17 | 11.6 | <.0001 |
| Insurance | |||||
| Private | 55 | 52.9 | 35 | 24.0 | |
| Medicare | 41 | 39.4 | 101 | 69.2 | |
| Medicaid/Worker's Compensation | 8 | 7.7 | 10 | 6.8 | <.0001 |
| ASA Classification | |||||
| 1 | 5 | 4.8 | 0 | 0.0 | |
| 2 | 81 | 77.9 | 103 | 70.5 | |
| 3 | 15 | 14.4 | 41 | 28.1 | 0.001 |
| Smoking | |||||
| Never | 43 | 41.3 | 67 | 45.9 | |
| Previous | 55 | 52.9 | 72 | 49.3 | |
| Current | 6 | 5.8 | 7 | 4.8 | 0.510 |
| Diabetes | 13 | 12.5 | 22 | 15.1 | 0.503 |
| Preoperative opioid use | 1 | 1.0 | 22 | 15.1 | 0.012 |
ASA: American Society for Anesthesiologists classification; DJD: degenerative joint disease; RCA: rotator cuff arthropathy; RCT: rotator cuff tears.
*For differences between RSA and TSA among patients with both one-year and two-year follow-up. p values derived from chi-square test or Fisher's exact test.
Outcomes
Patients who underwent TSA had average ASES scores of 82.7 and 82.0 (p = 0.530; Figure 1) and average VAS pain scores of 0.73 and 0.65 (p = 0.566), at one and two years postoperatively, respectively (Table 2). Forward elevation increased from 145.0° to 146.5° (p = 0.925), external rotation improved from 46.6° to 52.3° (p < 0.001), and internal rotation score had a small improvement from 5.5 to 6 (p = 0.008) between one and two years following TSA (Table 2). These improvements were not clinically significant.
Figure 1.
Graphical progression of American Shoulder and Elbow Surgeons (ASES) score from preoperative consultation through the two-year follow-up mark for patients undergoing TSA and RSA.
Table 2.
Outcome metrics one and two years after anatomic total shoulder arthroplasty (TSA).
| TSA | |||||
|---|---|---|---|---|---|
| Metric | Years Post-op | Mean | 95% CI | SD | p † |
| ASES | 1 year | 87.8 | (85.2, 90.3) | 13.1 | |
| 2 years | 87.6 | (84.7, 90.4) | 14.6 | ||
| Change | 0.2 | (−2.1, 2.5) | 12.0 | 0.866 | |
| VAS | 1 year | 0.73 | (0.49, 0.98) | 1.3 | |
| 2 years | 0.65 | (0.41, 0.89) | 1.2 | ||
| Change | 0.09 | (−0.16, 0.34) | 1.3 | 0.566 | |
| In-rotation | 1 year | 5.5 | (5.1, 5.9) | 1.8 | |
| 2 years | 6.0 | (5.6, 6.4) | 1.9 | ||
| Change | −0.5 | (−0.9, −0.1) | 1.9 | 0.008 | |
| Ex-rotation | 1 year | 46.6 | (44.3, 49.0) | 11.9 | |
| 2 years | 52.3 | (49.8, 54.7) | 12.3 | ||
| Change | −5.6 | (−8.1, −3.2) | 12.5 | <.0001 | |
| Elevation | 1 year | 145.0 | (141.0, 149.0) | 20.1 | |
| 2 years | 146.5 | (143.7, 149.3) | 14.2 | ||
| Change | −1.4 | (−4.9, 2.0) | 17.8 | 0.925 | |
†Wilcoxon rank sum test for ASES, VAS, Internal Rotation, External Rotation, and Elevation. ASES: American Shoulder and Elbow Surgeons; VAS: Visual Analog Scale.
Patients who underwent RSA reported average ASES scores of 87.8 and 87.6 (p = 0.866) and average VAS pain scores of 0.71 and 0.83 (p = 0.192) at one and two years postoperatively (Table 3). On average, forward elevation increased from 134.7° to 136.2° (p = 0.017), external rotation improved from 41.0° to 44.7° (<0.001), and internal rotation score improved from 4.2 to 4.8 (<0.001) between one and two years following RSA (Table 3). These changes in ROM between one and two years following RSA were not clinically significant.
Table 3.
Outcome metrics one and two years after reverse total shoulder arthroplasty (RSA).
| RSA | |||||
|---|---|---|---|---|---|
| Metric | Years Post-op | Mean | 95% CI | SD | p † |
| ASES | 1 year | 82.7 | (80.4, 85.0) | 13.9 | |
| 2 years | 82.0 | (79.4, 84.6) | 15.8 | ||
| Change | 0.7 | (−1.4, 2.8) | 13.1 | 0.530 | |
| VAS | 1 year | 0.71 | (0.50, 0.93) | 1.3 | |
| 2 years | 0.83 | (0.60, 1.06) | 1.4 | ||
| Change | −0.12 | (−0.36, 0.13) | 1.5 | 0.192 | |
| In-rotation | 1 year | 4.2 | (4.0, 4.5) | 1.7 | |
| 2 years | 4.8 | (4.5, 5.2) | 1.9 | ||
| Change | −0.6 | (−0.9, −0.3) | 1.8 | <0.0001 | |
| Ex-rotation | 1 year | 41.0 | (38.5, 43.5) | 14.8 | |
| 2 years | 44.7 | (42.2, 47.2) | 14.9 | ||
| Change | −3.7 | (−7.2, −2.3) | 14.6 | <.0001 | |
| Elevation | 1 year | 134.7 | (131.6, 137.8) | 18.3 | |
| 2 years | 136.2 | (132.8, 139.6) | 20.1 | ||
| Change | −2.7 | (−5.3, −0.1) | 15.5 | 0.017 | |
†Wilcoxon rank sum test for ASES, VAS, Internal Rotation, External Rotation, and Elevation. Wilcoxon rank sum test for ASES, VAS, Internal Rotation, External Rotation, and Elevation. ASES: American Shoulder and Elbow Surgeons; VAS: Visual Analog Scale.
Complications
There were four complications (1.6%) in the cohort: nerve injury (2), hematoma (1), and acromial stress fracture (1). Only the hematoma required surgical intervention, for which an incision and drainage was performed and the complication was resolved. All complications occurred within the first postoperative year. There were no complications that occurred between year one and two.
Discussion
Our objective was to evaluate change in patient-reported outcome measures, shoulder ROM, and complication rates between one and two years following total shoulder (TSA) and reverse shoulder arthroplasties (RSA). We hypothesized that there would not be significant changes in any of these measures of clinical outcomes for either cohort.
Using the ASES score and VAS pain score, 17 we found that patients in both groups achieved satisfactory outcomes without improvements or complications between year one and two. Forward elevation, external rotation, and internal rotation showed slight improvements that were not clinically relevant. These results are consistent with existing literature (Tables 2 and 3).13,14
Following TSA, forward elevation increased (mean) 1.4° (p = 0.925), external rotation increased 5.6° (p < 0.05), and internal rotation increased 0.5 (p = 0.05) between one and two years postoperatively; whereas following RSA, forward elevation increased 2.7° (p < 0.05), external rotation increased 3.7° (p < 0.05), and internal rotation increased 0.6 (p < 0.05) between one and two years postoperatively. While all improvements in ROM, except for forward elevation following TSA, between one and two years postoperatively were statistically significant, they were not clinically significant. Our findings suggest that postoperative pain appears to improve at a faster rate than function.
Interestingly, we observed greater variability in outcomes following RSA compared to TSA.13,14 The average ASES score following RSA had a larger standard deviation at both one and two years postoperatively. Additionally, our RSA population had a larger variation of primary diagnosis, which included massive rotator cuff tears,18–20 and a higher proportion of patients that were receiving preoperative narcotics21–24—both of which are known contributors to lower outcome scores.
Our findings are important because they help clinicians counsel patients on expectations of the timeline of recovery. Additionally, they challenge the antiquated standard of minimum of two year follow-up which acts as a burden to clinicians and an unnecessary hurdle for researchers. The need for two-year follow-up bogs down clinics, costs patients time and money, and limits publishable data because follow-up rates drop significantly at the two-year mark. 7 IDE studies have been adhering to this two-year minimum follow-up standard4,15 that does not appear to be based on shoulder arthroplasty-specific recovery timelines. Our data demonstrate that all relevant measurements and assessments plateau in terms of clinical significance at the one-year postoperative mark, making it an acceptable, efficient, and more attainable standard.
This study has several limitations. The populations of patients undergoing RSA and TSA varied in preoperative characteristics. RSA candidates were older, more likely to be female, and had lower preoperative shoulder function than TSA candidates. However, our patient population reflects previously described demographics of arthroplasty candidates and may represent patient outcomes more accurately than a controlled group.
Patient-reported outcomes and complication rates did not change between one and two years following TSA and RSA, and ROM did improve slightly, but the improvement was not clinically relevant. This information is important in counseling patients on the process of recovery following shoulder arthroplasty, and challenges the existing requirement of data sets with a minimum of two-year follow-up. One-year follow-up data should be the new minimum standard. This will allow studies with higher sample sizes, and thus increased power, to be published.
Footnotes
Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Andrew Jawa has been a paid speaker and consultant for DJO Global, a paid consultant for Ignite Orthopedics, receives royalties from Depuy Synthesis, and has equity in Boston Outpatient Surgical Suites.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
Ethical Review and Patient Consent: Approved by the Institutional Review Board of the New England Baptist Hospital Project Number: #1208307. All patients were consented to be part of our prospectively maintained data registry. The consent clearly indicated that their data may be used for future studies.
Guarantor: AJ (PI).
Contributorship: KAM, MPC, JG, SWG, FG, and AJ.
ORCID iD: Samuel W Golenbock https://orcid.org/0000-0001-7270-3643
Andrew Jawa https://orcid.org/0000-0002-1763-390X
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