Orthopedics

Feature Article 

Posterior Approach Total Shoulder Arthroplasty: A Retrospective Analysis of Short-term Results

R. Michael Greiwe, MD; Misti A. Hill, BSN; Maxwell S. Boyle, BS; Joseph Nolan, PhD

Abstract

Subscapularis dysfunction and failure are the leading causes of complications of total shoulder arthroplasty (TSA). An approach to shoulder arthroplasty has been described that may improve exposure to the retroverted glenoid and spare the rotator cuff. This article details the 6-month clinical outcomes of the first 26 patients who underwent TSA using a posterior approach. Thirty-one patients who underwent TSA using a posterior approach between September 2016 and October 2017 were identified retrospectively. Patients were assessed for American Shoulder and Elbow Surgeons (ASES) scores, Simple Shoulder Test (SST) scores, range of motion, complications, radiographic outcomes, and patient satisfaction. Statistical models were used to compare the means for each outcome variable over time. Of the initial 31 patients, 26 patients were available for follow-up at a minimum of 6 months; the remaining 5 patients did not return for follow-up at 6 months. Significant improvement in each outcome variable from baseline was noted by 6 weeks postoperatively. Further improvement was observed at 3 months for SST and external rotation, and at 6 months for ASES function and forward flexion. All outcome variables demonstrated some improvement from one time point to the next. Posterior TSA is a safe and efficacious procedure at 6 months. Compared with traditional TSA, posterior cuff-sparing approaches may improve posterior joint access, posterior soft tissue balancing, and long-term rotator cuff issues. [Orthopedics. 2020; 4x(x):xx–xx.]

Abstract

Subscapularis dysfunction and failure are the leading causes of complications of total shoulder arthroplasty (TSA). An approach to shoulder arthroplasty has been described that may improve exposure to the retroverted glenoid and spare the rotator cuff. This article details the 6-month clinical outcomes of the first 26 patients who underwent TSA using a posterior approach. Thirty-one patients who underwent TSA using a posterior approach between September 2016 and October 2017 were identified retrospectively. Patients were assessed for American Shoulder and Elbow Surgeons (ASES) scores, Simple Shoulder Test (SST) scores, range of motion, complications, radiographic outcomes, and patient satisfaction. Statistical models were used to compare the means for each outcome variable over time. Of the initial 31 patients, 26 patients were available for follow-up at a minimum of 6 months; the remaining 5 patients did not return for follow-up at 6 months. Significant improvement in each outcome variable from baseline was noted by 6 weeks postoperatively. Further improvement was observed at 3 months for SST and external rotation, and at 6 months for ASES function and forward flexion. All outcome variables demonstrated some improvement from one time point to the next. Posterior TSA is a safe and efficacious procedure at 6 months. Compared with traditional TSA, posterior cuff-sparing approaches may improve posterior joint access, posterior soft tissue balancing, and long-term rotator cuff issues. [Orthopedics. 2020; 4x(x):xx–xx.]

The number of patients requiring total shoulder arthroplasty (TSA) has increased during the past decade and continues to rise along with reverse total shoulder arthroplasty (rTSA). The glenohumeral joint is the third most common joint that requires arthroplasty surgery behind the hip and the knee.1 With good success, TSA has been shown to decrease pain and improve function in the glenohumeral joint.1,2

Traditional anatomic total shoulder arthroplasty (aTSA) approaches the shoulder through a deltopectoral approach and uses a subscapularis takedown through tenotomy, peel, or lesser tuberosity osteotomy to access the glenohumeral joint.3 This approach to TSA consists of 2 procedures in 1—the joint replacement and the subsequent rotator cuff repair.

Following aTSA, patients traditionally are placed in a sling and have limited mobility of the shoulder joint because of the concern for subscapularis healing. Healing may take 3 to 4 months, and full subscapularis healing remains an issue for osteotomy, tenotomy, and peel alike.3–6 In addition, patients who use assistive devices for ambulation, live alone, or require extra assistance postoperatively may not consent to the procedure due to the limitations of traditional surgery.

Recently, alternative approaches have been developed to spare the rotator cuff and potentially improve functional outcomes for patients.7 Rotator cuff-sparing, posterior approach anatomic total shoulder arthroplasty (pTSA) may improve pain, rehabilitation time, and subscapularis function and strength postoperatively.3 The pTSA was developed to reduce the level of disturbance to the rotator cuff, assist with exposure of the retroverted glenoid, improve access to inferior humeral osteophytes, and potentially minimize possible complications.

The goals of this retrospective analysis were to describe the approach to evaluate radiographic and clinical outcomes following pTSA and to report on early outcomes regarding patient-reported outcomes, range of motion, and patient satisfaction. The predetermined hypotheses were that patients undergoing pTSA would have short recovery times, high satisfaction rates, and few complications due to the rotator cuff-sparing nature of this approach.

Materials and Methods

Study Design

This retrospective study reviewed the first 31 patients who underwent pTSA at the authors' institution. Institutional review board approval was obtained to perform a retrospective chart analysis. Study procedures were carried out in accordance to the ethical standards of the responsible committee on human experimentation. The study was a single-center, multi-location data analysis study.

Participants

Eligible participants were older than 18 years who underwent pTSA by the principal investigator. Patients with severe arthritis and significant bony deformity or loose bone in the anterior recess of the shoulder are not currently indicated for pTSA.

Mean patient age was 69±11 years (range, 37–88 years). Surgery was performed on the left side in 19 (61.3%) patients and on the right side in 12 (38.7%) patients. Seventeen (54.8%) patients were male, and 14 (45.2 %) patients were female. Posterior approach TSA was performed using the Simplicity humeral component (30 cases) (Wright Medical, Memphis, Tennessee) and the Reunion (Stryker, Kalamazoo, Michigan) and Catalyst (OrthoScience, Naples, Florida) cemented glenoid components. One patient required a stemmed shoulder arthroplasty Aequalis Flex Stem (Wright Medical) because the bone quality was poor, and the surgeon believed stemless shoulder arthroplasty would not be appropriate. All patients received all-polyethylene keeled pegged glenoid components. Stemless arthroplasty allows this procedure to be performed in a technically easier fashion due to anatomical constraints present in the pTSA.

One patient died 5 months after the procedure due to a lengthy battle with an unrelated chronic illness. The last recorded follow-up for this patient was at 6 weeks and showed a 50% reduction in shoulder pain from baseline scores.

Postoperative Assessment

Recorded outcomes included range of motion (ROM), American Shoulder and Elbow Surgeons (ASES) scores, Simple Shoulder Test (SST) scores, and patient satisfaction. Patients were assessed at baseline, and 6 weeks, 3 months, and 6 months postoperatively, and patients did not have every time point visit available in the electronic health record. Patients who did not undergo follow-up at 6 months postoperatively were contacted and surveyed via telephone.

Statistical Analysis

Statistical analyses were performed using SAS version 9.4 software (SAS Institute Inc, Cary, North Carolina). Repeated-measure analysis of variance (RM-ANOVA) models were implemented to examine the mean for each outcome variable over time. Tukey adjusted differences were examined to identify statistically significant differences over time using a significance level of alpha=0.05.

Sample sizes differed by outcome variable due to missing data and ranged from 29 to 31. Missing data were handled by omission of the participant in cases where no data were available for an outcome variable after baseline. In cases where data were missing for only one or two time points, the participant was included in analysis because the RM-ANOVA model accommodates that level of missing values.

Surgical Technique

Surgery was performed using general anesthesia, and all patients were given an interscalene nerve block. Patients were positioned in the opposite lateral decubitus position (Figure 1). The interval between the posterior and middle third of the deltoid was identified, and a split was made at that level. The interval was most easily palpated underneath the muscle belly (Figures 23).

Lateral decubitus position of the shoulder. (Copyright Julie Ranels. Used with permission.)

Figure 1:

Lateral decubitus position of the shoulder. (Copyright Julie Ranels. Used with permission.)

Deltoid access incision. (Copyright Julie Ranels. Used with permission.)

Figure 2:

Deltoid access incision. (Copyright Julie Ranels. Used with permission.)

Deltoid split. (Copyright Julie Ranels. Used with permission.)

Figure 3:

Deltoid split. (Copyright Julie Ranels. Used with permission.)

The teres minor and the infraspinatus were identified and carefully reflected off the capsule. In this interval approach, the tendons are lifted up and split, instead of using a takedown approach. Undermining the rotator cuff more medially was not necessary (Figure 4).

Reflected teres minor and infraspinatus. (Copyright Julie Ranels. Used with permission.)

Figure 4:

Reflected teres minor and infraspinatus. (Copyright Julie Ranels. Used with permission.)

The exposed capsule was released in a T-shaped fashion both superiorly and inferiorly around the neck of the humerus (Figures 57). The inferior humeral osteophytes were removed, and an in-situ osteotomy was performed using a sagittal saw. The biceps tendon was tenotomized, the anterior shoulder capsule was released using electrocautery, and the labrum was excised. A retractor then was placed anteriorly to retract the shoulder to open direct access to the glenoid (Figure 8).

T-shaped capsule release. (Copyright Julie Ranels. Used with permission.)

Figure 5:

T-shaped capsule release. (Copyright Julie Ranels. Used with permission.)

Initial exposure of the humeral head. (Copyright Julie Ranels. Used with permission.)

Figure 6:

Initial exposure of the humeral head. (Copyright Julie Ranels. Used with permission.)

Continued exposure of the humeral head. (Copyright Julie Ranels. Used with permission.)

Figure 7:

Continued exposure of the humeral head. (Copyright Julie Ranels. Used with permission.)

Direct glenoid access. (Copyright Julie Ranels. Used with permission.)

Figure 8:

Direct glenoid access. (Copyright Julie Ranels. Used with permission.)

Additional retractors were placed, and reaming was performed. The glenoid was prepared, and the trial components were placed (Figure 9). Appropriate humeral osteotomy was confirmed using a mini C-arm. Retractors were placed around the humeral head, and the humeral head was instrumented, prepared, and real components placed (Figure 10). The shoulder was reduced, and glenohumeral stability and sizing were assessed; the capsule, rotator cuff split, and deltoid split then were repaired (Figures 1113).

Placement of the glenoid. (Copyright Julie Ranels. Used with permission.)

Figure 9:

Placement of the glenoid. (Copyright Julie Ranels. Used with permission.)

Humeral head implanted. (Copyright Julie Ranels. Used with permission.)

Figure 10:

Humeral head implanted. (Copyright Julie Ranels. Used with permission.)

Repaired capsule. (Copyright Julie Ranels. Used with permission.)

Figure 11:

Repaired capsule. (Copyright Julie Ranels. Used with permission.)

Repaired split rotator cuff. (Copyright Julie Ranels. Used with permission.)

Figure 12:

Repaired split rotator cuff. (Copyright Julie Ranels. Used with permission.)

Repaired split deltoid. (Copyright Julie Ranels. Used with permission.)

Figure 13:

Repaired split deltoid. (Copyright Julie Ranels. Used with permission.)

When necessary, imbrication of the posterior capsule was performed to improve postoperative soft tissue balancing. Postoperatively, patients were instructed to wear a sling for the first 2 days; the sling then was used only as needed, and patients began active motion as tolerated. Patients had no restrictions other than to avoid maximal cross-body adduction (Figures 1415).

Preoperative radiograph of the glenohumeral joint.

Figure 14:

Preoperative radiograph of the glenohumeral joint.

Postoperative radiograph of the glenohumeral joint after posterior approach total shoulder arthroplasty.

Figure 15:

Postoperative radiograph of the glenohumeral joint after posterior approach total shoulder arthroplasty.

Results

Twenty-six of the initial 31 patients were available for follow-up at a minimum of 6 months following pTSA. The remaining 5 patients did not return for clinical or telephone follow-up at 6 months; 1 of these patients died, and the other 4 patients could not be contacted. Repeated-measure analysis of variance models using Tukey post hoc comparisons showed statistically significant improvement for each outcome variable from baseline by 6 weeks (P<.001 for all comparisons). Further statistically significant improvement was observed at 3 months for SST (T=3.25, P=.0102) and external rotation (T=4.41, P=.0002), and at 6 months for ASES function (T=5.57, P<.0001) and forward flexion (T=4.05, P=.0007). Table 1 provides the mean outcome at each time point (and additionally estimated standard errors). Figures 1618 show improvement in outcomes for the first 6 months postoperatively.

Functional Outcomes

Table 1:

Functional Outcomes

Pre- and postoperative range of motion. Abbreviations: ER, external rotation; FF, forward flexion; IR, internal rotation.

Figure 16:

Pre- and postoperative range of motion. Abbreviations: ER, external rotation; FF, forward flexion; IR, internal rotation.

Pre- and postoperative American Shoulder and Elbow Surgeons scores.

Figure 17:

Pre- and postoperative American Shoulder and Elbow Surgeons scores.

Pre- and postoperative Simple Shoulder Test (SST) scores.

Figure 18:

Pre- and postoperative Simple Shoulder Test (SST) scores.

Radiographic Outcomes

Postoperatively, there was no evidence of glenoid loosening in any patient. The humeral head was superior of the greater tuberosity by more than 5 mm in 1 patient, and inferior humeral osteophytes were evident in 2 patients.

Patient Satisfaction

Of the 31 patients, 26 were contacted via telephone to assess patient satisfaction. All 26 patients reported being satisfied with the procedure and indicated they would recommend the surgeon to a friend or family member.

Complications

One patient reported weakness following pTSA. Forward flexion strength appeared to be limited to 90° for 3 months following the procedure, but the patient could forward flex more fully in the supine position. Electromyogram (EMG) and computed tomography (CT) arthrogram were used to assess for the presence of axillary nerve function and the presence or absence of a rotator cuff tear. The EMG showed full activity to the axillary nerve, and the CT arthrogram demonstrated a fully intact rotator cuff. By 6 months, the patient regained much of her strength and her range of motion improved.

Discussion

Posterior approach TSA has the potential benefits of improved visualization of the retroverted glenoid, better access to the inferior glenohumeral osteophytes, and preservation of the rotator cuff compared with other minimally invasive approaches. Compared with traditional TSA, pTSA allows for decreased sling wear and early active motion. In a previous report on 3 patients who underwent pTSA, the patients had uneventful operations and demonstrated promising results in functionality and pain in the immediate postoperative period.3

During aTSA, management of the subscapularis to access the glenoid may include tenotomy, subscapularis peel, lesser tuberosity osteotomy, and even subscapularis-sparing techniques.1 Clinical studies regarding the subscapularis function following aTSA surgery indicate anterior approaches using different subscapularis tendon take down or incision techniques may impair subscapularis recovery or carry the risk of iatrogenic damage to the subscapularis musculotendinous unit, which can negatively influence the final clinical outcome.1 Recent reports concur that inadequate healing or denervation of the rotator cuff can lead to postoperative pain, weakness, instability, and glenoid loosening.1,8 Subscapularis dysfunction and failure are the leading complications of TSA, occurring in 11% to 66% of patients.4–6,9

In addition, a 50% loss of the subscapularis muscle strength and significant fatty degeneration of the muscle has been noted in as many as 41% of patients who undergo an anterior approach to shoulder surgery.10 Irreversible changes of the muscle, including atrophy and fatty infiltration with or without failure of the tendon repair, may result in permanent loss of subscapularis function. Subscapularis function is critical to the forces and edge loading of the humeral component. Increased edge loading, as seen in patients with poor superior rotator cuff function, leads to glenoid loosening.10 Therefore, it is possible that preserved subscapularis function also may decrease glenoid loosening rates over time.

This case series was limited in part by the small number of participants. Although clear improvements were observed, with a larger number of participants, it may be possible to identify improvement for range of motion outcomes across all time points.

Posterior approach TSA is still in the early investigation phase. However, outcomes are promising and compare favorably with early results with traditional aTSA.

Conclusion

Posterior TSA is a safe and efficacious procedure at 6 months. Improvements in range of motion, SST, and ASES scores were demonstrated during the measured time period. Compared with traditional TSA, posterior cuff-sparing approaches may improve access to the posterior joint, posterior soft tissue balancing, and long-term issues with the rotator cuff. However, more research is needed to assess long-term efficacy, durability, and complications from the procedure, especially in comparison with traditional TSA.

References

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  2. Wolff A, Rosenzweig L. Anatomical and bio-mechanical framework for shoulder arthroplasty rehabilitation. J Hand Ther. 2017;30(2):167–174. https://doi.org/10.1016/j.jht.2017.05.009 doi:10.1016/j.jht.2017.05.009 [CrossRef]28641735
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  6. Qureshi S, Hsiao A, Klug RA, Lee E, Braman J, Flatow EL. Subscapularis function after total shoulder replacement: results with lesser tuberosity osteotomy. J Shoulder Elbow Surg. 2008;17(1):68–72. https://doi.org/10.1016/j.jse.2007.04.018 PMID: doi:10.1016/j.jse.2007.04.018 [CrossRef]
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  8. Giles JW, Langohr GDG, Johnson JA, Athwal GS. The rotator cuff muscles are antagonists after reverse total shoulder arthroplasty. J Shoulder Elbow Surg. 2016;25(10):1592–1600. https://doi.org/10.1016/j.jse.2016.02.028 PMID: doi:10.1016/j.jse.2016.02.028 [CrossRef]27107733
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Functional Outcomes

OutcomeMean±SE

Baseline6 Weeks3 Months6 Months
SST score3.0±0.45.7±0.5a7.9±0.5a9.3±0.4
FF120.3°±3.4°143.5°±3.5°a155.1°±3.8°165.2°±4.1°a
ER39.5°±2.1°60.4°±2.3°a75.0°±2.4°a80.0°±2.6°
IR4.0°±0.6°7.3°±0.6°a8.3°±0.7°9.4°±0.7°
ASES score
  Total38.4±2.679.9±11.1a74.9±5.083.1±3.3
  Function17.3±1.326.5±1.8a32.2±1.739.1±1.5a
  Pain21.1±1.643.4±3.9a43.1±2.4a43.0±2.1
Authors

The authors are from OrthoCincy Orthopaedics & Sports Medicine (RMG, MSB), Florence and Edgewood; the Clinical Research Institute (MAH, MSB), St Elizabeth Healthcare (RMG, MSB), Florence and Edgewood; The Orthopaedic Research & Innovation Foundation (RMG, MAH), Edgewood; and Northern Kentucky University (JN), Highland Heights, and Burkardt Consulting Center (JN), Highland Heights, Kentucky.

Mrs Hill, Mr Boyle, and Dr Nolan have no relevant financial relationships to disclose. Dr Greiwe is a paid consultant for Linvatec and Stryker.

Correspondence should be addressed to: R. Michael Greiwe, MD, 560 S Loop Rd, Edgewood, KY 41017 ( mikegreiwe@gmail.com).

Received: September 14, 2018
Accepted: January 02, 2019
Posted Online: November 26, 2019

10.3928/01477447-20191122-03

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