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J Shoulder Elbow Surg (2014) 23, 782-790

1058-2746/$ - s

http://dx.doi.org

www.elsevier.com/locate/ymse

What is the effect of postoperative scapular

fracture on outcomes of reverse shoulderarthroplasty?

Matthew J. Teusink, MDa, Randall J. Otto, MDb, Benjamin J. Cottrell, BSc,Mark A. Frankle, MDd,*

aDepartment of Orthopaedic Surgery and Rehabilitation, University of Nebraska Medical Center, Omaha, NE, USAbPremier Care Orthopedics and Sports Medicine, Saint Louis, MO, USAcFoundation for Orthopaedic Research, Tampa, FL, USAdFlorida Orthopaedic Institute, Tampa, FL, USA

Background: Postoperative scapular fracture is a common complication after reverse shoulder arthroplasty(RSA). The purpose of this study was to determine its effect on RSA patient outcomes.Methods: A retrospective, case-control study of 25 nonoperatively treated postoperative scapular fracturesafter RSA were analyzed with a minimum 2-year follow-up from surgery and 1-year follow-up from frac-ture. Eligible patients were matched 1:4 to a control group for age, sex, follow-up time, surgery indication,and primary operation vs revision. Outcome measures, including American Shoulder and Elbow Surgeons(ASES) score and range of motion, were compared between fracture cases and controls. Also analyzedwere radiographic features, including fracture location (acromion vs scapular spine) and healing.Results: Incidence of scapular fracture after RSA in this series was 3.1%. Fractures occurred from 1 to94 months postoperatively. The revision rate was higher in the fracture group (8% vs 2%) but did notreach statistical significance (P ¼ .18). Fracture patients had improved (DASES, 21) but inferior clinicaloutcomes, with a postoperative ASES score of 58.0 compared with 74.2 (P � .001). Change in range ofmotion also diminished in the fracture group, with a mean gain of 26� forward elevation compared with76� (P < .001). Fracture location (P ¼ .54) or healing (P ¼ .40) did not affect outcome.Conclusion: Postoperative scapular fractures may occur at any point postoperatively; increasing incidence islikely as longer follow-up becomes available. This complication leads to inferior clinical results comparedwith controls. However, patients show improvement compared with their preoperative measurements, evenat longer-term follow-up. Patients with postoperative scapular fractures may have increased risk of revision.Level of evidence: Level III, Case-Control Study, Treatment Study.� 2014 Journal of Shoulder and Elbow Surgery Board of Trustees.

Keywords: Scapular fracture; acromial fracture; reverse shoulder arthroplasty; nonoperative treatment;

postoperative complication; outcomes

titutional Review Board determined this study was exempt

uests: Mark A. Frankle, MD, Florida Orthopaedic Institute,

m Pkwy, Tampa, FL 33637, USA.

ss: mfrankle@floridaortho.com (M.A. Frankle).

ee front matter � 2014 Journal of Shoulder and Elbow Surgery

/10.1016/j.jse.2013.09.010

Reverse shoulder arthroplasty (RSA) is a common pro-cedure for the management of difficult shoulder problems,such as massive and irreparable rotator cuff tears, with andwithout glenohumeral arthritis, rotator cuff deficiency

Board of Trustees.

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Figure 1 Incidence of postoperative scapular fracture at lengthof follow-up from surgery.

RSA outcomes with postoperative scapular fracture 783

secondary to proximal humeral fractures, and revisionshoulder arthroplasty.1-4,6-10,18-20,23,24,27,28 Approximately10,000 RSAs were performed in 2007, with estimates that30,000 were performed in 2012.14 Although RSA has beenshown to be a successful procedure at short-term andmidterm follow-up,1,3,4,6,7,10,18,19,23,24,27 complicationscontinue to be a concern, especially with increasingnumbers of the procedure being performed.

Scapular fractures after RSA have been reported in 0.8%to 7.2% in published studies.1-3,5-7,11,12,14,17,20,23,25,26,28 Astable fulcrum in RSA is provided by an appropriatelytensioned deltoid, which allows active shoulder elevationand a stable prosthesis. Failure to appropriately tension thedeltoid may lead to prosthetic instability, neurologic injury,deltoid insufficiency, or scapular fractures. The acromialorigin of the deltoid is important in deltoid tensioning andultimate performance of the implant. Fractures that disruptthe appropriate tension of the deltoid may lead to delete-rious consequences for the overall function of the implant.

Previous studies have reviewed the outcomes of scapularfractures after RSA at short-term follow-up. Hamid et al11

reported 8 fractures, all treated nonoperatively, at meanfollow-up of 35 months and found poor elevation andAmerican Shoulder and Elbow Surgeons (ASES) scores,with 6 of the 8 fractures going on to nonunion.11 Similarly,Hattrup reported 9 postoperative scapular fracturesmanaged nonoperatively and found decreased activeelevation and ASES scores compared with other patientsundergoing RSA who did not experience a fracture.12

Walch et al26 similarly showed poor outcomes in 4 pa-tients with postoperative scapular fractures; however, theyalso showed that preoperative lesions (os acromiale andacromial fragmentation) did not affect clinical outcomes in41 patients with preoperative scapular insufficiency. Theyconcluded that preoperative scapular lesions are an entirelydifferent entity from postoperative fractures, which havedeleterious consequences on outcomes.

Although these studies showed that postoperative acro-mial fractures likely lead to inferior outcome scores in theshort-term compared with patients who did not experiencethis complication, none of these studies demonstratedwhether these results remained consistent with longer-termfollow-up from the fracture. Whether revision rates areaffected by postoperative fractures, despite a report thatscapular fractures led to subsequent instability, has also notbeen shown.17 Although there has been speculation thatscapular spine fractures lead to inferior outcomes comparedwith acromial fractures,11,26 whether the fracture location isprognostic of outcome remains unclear. The 49 postoperativescapular fractures documented in previous reports occurredas early as 2 months and as late as 48 months.5,11,12,17,26

However, little information exists about the time period atwhich patients are at risk to develop this complication.

This study used case-control methods to determinewhether patients with nonoperatively treated postoperativescapular fractures have inferior outcomes after RSA. We

hypothesized that patients with postoperative scapularfractures would continue to have inferior clinical outcomescompared with matched controls without fractures atcomparable postoperative follow-up. We also hypothesizedthat scapular fractures would lead to an increased reoper-ation rate compared with controls.

Finally, we sought to determine which features ofscapular fractures might predict a poor outcome. We hy-pothesized that fracture healing would lead to improvedoutcomes compared with patients with nonunion and thatscapular spine fractures have inferior outcomes comparedwith acromial fractures.

Materials and methods

A retrospective analysis of a consecutive, nonselected series of allRSAs performed by the senior surgeon (M.A.F.) from February 1,2003, through May 31, 2010, was performed to evaluate for thecomplication of postoperative scapular fracture. During thisinterval, the senior author performed 1018 RSAs using theReverse Shoulder Prosthesis (DJO Surgical, Austin, TX, USA).All procedures were performed through a standard deltopectoralapproach.

The presence of a scapular fracture was determined by thesenior surgeon, with a clinical presentation of pain over theacromion or scapular spine and radiographic confirmation. A totalof 32 postoperative scapular fractures in 32 patients were identi-fied. Of these, 27 were diagnosed with clear identification on plainradiographs and 5 with plain radiographs and a confirmatorycomputed tomography (CT) scan.

Inclusion criteria were all patients undergoing RSA by thesenior author who sustained a postoperative scapular fracture andwere managed nonoperatively with a minimum of 2 years offollow-up from the time of arthroplasty and 1 year of clinicalfollow-up since the documented scapular fracture. The analysisexcluded patients who died or were lost to follow-up beforeclinical follow-up a minimum of 1 year from the fracture wasobtained.

All postoperative scapular fractures were managed non-operatively during the study period. Treatment consisted of slingimmobilization for 6 weeks and then advancing activities astolerated.

Table I (A) Demographic characteristics of patients with postoperative acromial fracture

Patient Age (y) Sex Pre-op diagnosis Time tofracture (mo)

Healed Revised ASESfinal24

1 79 M CTA 10 ) No 482 77 F CTA 4 Yes No 473 71 F Failed RCR 31 No No 804 75 F CTA 3 Yes No 285 74 F CTA 3 No No 556 65 M CTA 3 Yes No 907 70 F CTA 35 ) Yes8 74 F CTA 3 No No 639 81 F CTA 2 Yes No 7510 64 M CTA 6 No No 6011 78 F CTA 3 ) No 4512 66 F Failed hemiarthroplasty 4 No No 5713 56 F Failed TSA 5 Yes No 3514 62 F Failed hemiarthroplasty 20 Yes No 5515 83 F CTA 7 Yes No 5016 82 F CTA 4 Yes No 8217 65 F CTA 1 Yes No 88

ASES, American Shoulder and Elbow Surgeons; CTA, cuff tear arthropathy; F, female; M, male; RCR, rotator cuff repair; TSA, total shoulder arthroplasty.) Did not have radiographic follow-up greater than 1 year from time of fracture.

Table I (B) Demographic characteristics of patients with postoperative scapular body fracture

Patient Age (y) Sex Pre-op diagnosis Time tofracture (mo)

Healed Revised ASESfinal24

1 71 F CTA 4 ) No 782 74 F CTA 30 No No 853 70 F Failed TSA 3 ) Yes4 75 F Failed RCR 25 Yes No 805 71 F Failed RCR 82 Yes No 156 76 F CTA 94 ) No 337 72 F CTA 10 No No 408 75 M Failed TSA 11 ) No, but instability 45

ASES, American Shoulder and Elbow Surgeons; CTA, cuff tear arthropathy; F, female; M, male; RCR, rotator cuff repair; TSA, total shoulder arthroplasty.) Did not have radiographic follow-up greater than 1 year from time of fracture.

784 M.J. Teusink et al.

A total of 25 patients (25 shoulders) met the inclusion criteria.The analysis excluded 7 shoulders in 7 patients: 2 died beforeminimum 1-year follow-up data were obtained, 1 underwentresection of the implant for deep infection before clinical data wereobtained, and 4 patients were lost to follow-up before 1-yearfollow-up from the fracture was obtained. Demographic datacollected for each patient included age, sex, indications for surgery,history of previous surgery on the affected shoulder, and time fromsurgery to documented scapular fracture. Once the patients withpostoperative scapular fracture were identified, a control group ofpatients undergoing RSAwas matched for age, sex, total follow-uptime, indication for surgery, and primary vs revision surgery at aratio of 4:1 (control group:scapular fracture). A total of 100 patients(100 shoulders) were matched as controls. The control group wasused to test the hypothesis that postoperative scapular fracture has adeleterious effect on outcomes after RSA.

The primary clinical outcome measure was the change frompreoperative to postoperative total ASES score.20 The ASES scorehas not specifically been evaluated in this patient population but

has acceptable psychometric performance for outcomes mea-surements for patients with rotator cuff disease and glenohumeralarthritis.15 Additional analyses included revision rate, range ofmotion, and pain scores. Outcomes for patients with postoperativefractures were recorded at the most recent follow-up with greaterthan 1 year of follow-up after the diagnosis of scapula fracture anda minimum of 2 years from the surgical date. Outcomes forcontrol patients were obtained at the preoperative evaluation andthe follow-up visit, with the same length of follow-up as thefracture patient to which they were matched.

Range of motion was determined by evaluation of digitalvideos of each patient obtained preoperatively and post-operatively, as previously described,6 or by the patient’s self-reported range of motion on a standard questionnaire. Painscores were recorded from the patient’s self-reported level on avisual analog scale (VAS) at the most recent follow-up.13 Patientswho underwent revision surgery were excluded from the analysiscomparing clinical outcomes because they were considered fail-ures of nonoperative management.

Table II Demographic characteristics of patients withpostoperative scapular fractures and controls)

Variables Fractures Controls Pvalue(n ¼ 25) (n ¼ 100)

Age, mean (range) mo 72.2 (56-83) 71.9 (48-85) .84Sex, No. 1

Female 21 84Male 4 16

Indication, No. N/APrimary CTA 17 65Failed RCR 3 15Failed TSA 3 12Failed hemiarthroplasty 2 8

Length of follow-up 50 (24-106) 49.8 (24-121) .97

CTA, cuff tear arthropathy; N/A, not applicable; RCR, rotator cuff repair;

TSA, total shoulder arthroplasty.) No significant differences found between cases and controls for any

of the variables matched. Age was tested with the Student t test, sex

with the Fisher exact test, and length of follow-up with the Mann-

Whitney U test; significance at P < .05.

Figure 2 Example of an acromial fracture 3 months post-operatively, with excellent clinical outcome. American Shoulderand Elbow Surgeons score, 90.

Figure 3 Range of motion is shown in a patient with a post-operative acromial fracture, with excellent clinical outcome.Although this outcome is attainable in patients with postoperativeacromial fractures, it occurred in a minority of cases.

RSA outcomes with postoperative scapular fracture 785

A complete set of radiographs, including anteroposterior, trueanteroposterior in the plane of the scapula (Grashey), axillarylateral, and scapular Y, for each patient with postoperative scap-ular fracture were evaluated by 2 fellowship-trained shouldersurgeons not directly involved in the care of the patients (M.J.T.and R.J.O.) for evidence of healing at 1 year postoperatively oruntil fracture healing occurred (absence of fracture lucency).

Fractures were also classified according the location of thefracture: acromion or scapular spine based on Crosby’s classifi-cation.5 A previous report suggests that plain radiographs are notreliable for the diagnosis of these fractures, with only w80% ofknown fractures correctly diagnosed with plain radiographs alone.Also in this report, Crosby’s classification was only moderatelyreliable (k ¼ 0.422), suggesting the need for a more reliable

classification scheme.21 A recent report suggests that a CT scanprovides more reliable results at diagnosing these fractures;however, we did not obtain CT scans on all of these patients.16

The clinical outcome was evaluated with respect to fracturehealing and fracture location.

Statistical analysis

The Fisher exact test was used to test the hypothesis that patientswith scapular fractures would have a higher revision rate thancontrols. The Mann-Whitney U test was used to test the hypoth-esis that patients with scapular fractures would have inferioroutcomes than control patients and the hypothesis that patientswith postoperative scapular fractures would have diminishedsatisfaction compared with controls. The Student t test was used totest the hypothesis that patients with scapular fractures haveinferior range of motion compared with control patients, that pa-tients with healed fractures have improved outcomes comparedwith those with nonunions, and that patients with type 3 (scapularspine) fractures have inferior outcomes compared with type 2(acromial fractures). Statistical significance was set at <.05.

Results

The incidence of scapular fracture after RSA was 3.1% (32of 1018), and 25 patients (21 women, 4 men) met the in-clusion criteria. The average age at surgery was 72.2 years

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p=0.012

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Figure 4 Improvement in range of motion is shown in the fracture and control groups. ER, external rotation.

786 M.J. Teusink et al.

(range, 56-83 years). Indications for surgery included 17with massive rotator cuff tear, with or without arthritis, 3failed rotator cuff repairs, 3 failed total shoulder arthro-plasties, and 2 failed hemiarthroplasties. The average timeto diagnosis of scapular fracture was 16 months (range, 1-94 months). Average follow-up from time of surgery was50 months (range, 24-106 months; Fig. 1). Average follow-up from the time of the scapular fracture diagnosis was 45months (range, 12-63 months; Table I, A and B).

The control group consisted of 100 patients (84 women,16 men) who underwent a RSA and did not sustain apostoperative scapular fracture. Their average age was 71.9years (range, 48-85 years). Indications for surgery included65 patients with massive rotator cuff tear, with or withoutarthritis, 15 failed rotator cuff repairs, 12 failed totalshoulder arthroplasties, and 8 failed hemiarthroplasties.Average follow-up from time of surgery was 49.8 months(range, 24-121 months; Table II).

Clinical outcomes

There were 4 revisions in the study group: 2 in the scapularfracture group (8%) and 2 (2%) in the control group (P ¼.18). A statistical power analysis revealed that to demon-strate a significant difference in revision rates, 191 post-operative scapular fractures would be required. One patientwith a scapular spine fracture was revised 10 months afterthe fracture for glenoid loosening. A second patient with anacromial fracture was revised 2 weeks after the fracture forrecurrent instability. One patient in the control group wasrevised at 28 months for humeral loosening. The secondpatient was revised at 77 months, also for humeral

loosening. Of note, a third patient in with a scapular spinefracture noted recurrent instability 26 months after thefracture; however, this patient has not been revised.

The average preoperative total ASES score22 was 36.8(range, 3-65) in patients with scapular fractures and 37.2(range, 2-92) in the control group (P ¼ .94). The averagepostoperative total ASES score was 58.0 (range, 15-90) infracture patients (Figs. 2 and 3), whereas the average scorein the control patients was 74.2 (range, 10-100; P ¼ .001).

Average preoperative and postoperative range of motionin flexion, abduction, and external rotation for the fractureand control groups are shown in Figure 4. Flexion improved26� (range, �65� to 120�) in patients with scapula fracturesand 76� (range, �43� to 165�; Fig. 5 and Fig. 6) in thecontrol group (P � .001). Abduction improved 16� (range,�95� to 120�) in the fracture group and 72� (range, �20� to138�) in the control group (P � .001). Patients with frac-tures lost an average of 3� (range, �70� to 30�) of externalrotation, and controls gained 23� (range, �62� to 90�)external rotation (P < .001). Patients without scapularfractures had a greater level of satisfaction with the surgery(8.7; range, 1-10) than patients with scapular fractures (6.6;range 1-10; P ¼ .002).

Radiographic results

There were 17 acromial fractures and 8 scapular spinefractures. The average final ASES score was 59.9 (range,28.3-90; Figs. 7 and 8) of acromial fractures and 53.8 forscapular spine fractures (range, 15-85; P ¼ .54). Theaverage final VAS pain score was 2.4 (range, 0-10) foracromial fractures and 2.3 (range, 0-6) in scapular spine

Figure 5 Example of scapular spine fracture 30 months post-operatively, with excellent clinical outcome. American Shoulderand Elbow Surgeons score, 85.

Figure 6 Range of motion is shown in a patient with post-operative scapular spine fracture, with excellent clinical outcome.Although this outcome is attainable in patients with postoperativescapular body fractures, it occurred in minority of cases.

Figure 7 Example of healed scapular body fracture at20 months after the diagnosis of the fracture.

RSA outcomes with postoperative scapular fracture 787

fractures (P ¼ .96). The average increase in forwardelevation was 29� (range, �65 to 120�) for acromial frac-tures and 19� (range, �30� to 66�) for scapular spinefractures (P ¼ .66).

Only 10 of 18 fractures (55%) with greater than 1 yearof radiographic follow-up showed osseous union of thefracture, as evaluated by 2 independent blinded reviewerswith excellent agreement (Figs. 7 and 8). The union rate

was 57% (8 of 14) for acromial fractures and 50% (2 of 4)for scapular spine fractures.

The average ASES score was 56.3 (range, 15-90) infractures that healed and 65.2 (range, 40-85) in fracturesthat went on to nonunion (P ¼ .40). The average final VASpain score was 0.9 (range, 0-4) for healed fractures and 2.7(range, 0-8) in patients with nonunions (P ¼ .18). Theaverage increase in forward elevation was 26.4� (range,�18� to 95�) for healed fractures and 20.8� (range, �65� to93�) in patients with nonunions (P ¼ .79).

Discussion

Scapular fracture after RSA is a well-definedbut poorly understood complication. The incidence offracture in our series was 3.1%, which is consistent withprior studies that have reported rates from 0.9% to7.2%.1-3,5-7,11,12,20,23,25,26,28 Although this is an infrequentcomplication, it is undoubtedly under-reported due to dif-ficulty in diagnosis. Otto et al21 showed that only 79% ofthese fractures are identified by blinded reviewers withplain radiographs alone. To make this diagnosis, a highindex of suspicion must be maintained for patients whopresent with scapular pain after RSA. The incidence of3.1% in our series is likely an underestimate of the trueincidence of this complication and could possibly be closer

Figure 8 Example of acromial fracture nonunion at 14 months after the diagnosis of the fracture.

788 M.J. Teusink et al.

to 4% when estimating that 20% of these are missedradiographically.

This study demonstrates that patients with postoperativescapular fractures have inferior outcomes compared withcontrols.11,12,26 Although the long-term outcome of patientswith fractures is inferior, these patients still have clinicalimprovement from their preoperative functional level,noted by a preoperative ASES of 37 to postoperative ASESof 58 (change, 21 points). Similar to the ASES score,objectively decreased range of motion was found in pa-tients with fractures compared with controls; but again,range of motion was improved compared with preoperativevalues. Therefore, we can conclude that although post-operative scapular fractures have a negative effect on out-comes compared with controls, these patients still haveclinical improvement compared with their preoperativestate.

Although our data are consistent with previous reportsregarding clinical outcomes, no prior study has been able todemonstrate whether patients with scapular fractures are atincreased risk for revision surgery. Our study showed thatpatients with scapular fractures had an 8% revision ratecompared with 2% for controls, but this did not reach sta-tistical significance due to the infrequency of revisionsurgery in both groups (P ¼ .18). Previous authors havespeculated that scapular spine fractures are at increased riskfor instability and poorer outcomes requiring revision sur-gery,17,26 This was not our experience, however: one revi-sion was for glenoid baseplate loosening in a patient with a

scapular spine fracture and the other was for instability in apatient with an acromial fracture.

This study is the first with longer-term follow-up todemonstrate that scapular fractures can occur at any pointin the postoperative period. Previous reports on scapularfractures after RSA showed they occurred from 2 months to48 months postoperatively.11,12,17,26 Our data showed thatthese fractures can occur at any point in the postoperativeperiod, from as early as 4 weeks to nearly 8 years (94months). Therefore, the surgeon must maintain a high indexof suspicion for this complication whenever a patient pre-sents with scapular pain after RSA. As more RSA pro-cedures are being performed and longer-term follow-upbecomes available, the frequency of this complication willundoubtedly increase.14

One limitation of this study was the retrospective natureof identification of scapular fracture patients. Given thedifficulty of making this diagnosis clinically and radio-graphically, it is likely that not all patients sustaining thiscomplication were identified in the database, which mighthave influenced the results.

Second, all patients were managed nonoperatively fortheir scapular fracture; thus, the conclusions of this studyare only applicable to nonoperatively treated fractures.Whether improved outcomes may be obtained with opera-tive intervention remains unknown. This study provides abenchmark for outcomes of nonoperative management ofthis complication should other authors elect to pursueoperative fixation.

RSA outcomes with postoperative scapular fracture 789

The strengths of this study include the strict case-controlmethodology in a 4:1 manner to assess outcome differencesbetween scapular fracture patients and controls. Another isthe large number of fractures available for analysis.Compared with other studies, this is the largest study ofpostoperative scapular fractures in the literature todate,11,12,17,26 with the longest-term follow-up from frac-ture (average, 45 months), and provides conclusionsregarding the natural history of this complication.

Conclusion

Postoperative scapular fractures after RSA are becominga greater concern with the increasing use of RSAworldwide. Patients who experience this complicationmay be at increased risk for revision surgery and expe-rience inferior outcomes compared with patients withoutfractures. The location of the scapular fracture (acro-mion or spine)5 does not affect the results. Treatmentfocused at prevention of this complication is paramountto optimize outcomes after RSA.

Disclaimer

DJO Surgical provided research support to the Founda-tion for Orthopaedic Research and Education; however,DJO Surgical did not have input into this study becausethis was an investigator-initiated study.

Randall J. Otto, MD, received consulting fees orhonoraria for conducting lecture and cadaver teachingsessions from DJO Surgical, a designer and manufac-turer of orthopedic surgical products related to thesubject of this work. The research foundation thatBenjamin J. Cottrell, BS, is affiliated with receivedresearch support from DJO Surgical, a designer andmanufacturer of orthopedic surgical products related tothe subject of this work. Mark A. Frankle, MD, receivesroyalties from and is a paid consultant for DJO Surgical,a designer and manufacturer of orthopedic surgicalproducts related to the subject of this work. Matthew J.Teusink, MD, his immediate family, and any researchfoundations with which they are affiliated have notreceived any financial payments or other benefits fromany commercial entity related to the subject of thisarticle.

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