J Shoulder Elbow Surg (2014) -, 1-6
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Does bony increased-offset reverse shoulder arthroplasty decrease scapular notching? George S. Athwal, MD, FRCSC*, Joy C. MacDermid, PhD, K. Murali Reddy, MD, FRACS, Jonathan P. Marsh, MD, FRCSC, Kenneth J. Faber, MD, MHPE, FRCSC, Darren Drosdowech, MD, FRCSC RothjMcFarlane Hand and Upper Limb Center, St. Joseph’s Health Care, University of Western Ontario, London, Ontario, Canada Background: The purpose of this cohort study was to compare scapular notching rates, range of motion, and functional outcomes between patients who underwent a standard Grammont-style reverse shoulder arthroplasty (RSA) and patients who underwent bony increased-offset reverse shoulder arthroplasty (BIO-RSA) at a minimum of 2 years’ follow-up. We hypothesized that the BIO-RSA cohort would have lower notching rates and improved rotational range of motion; however, validated outcome scores between cohorts would be no different. Methods: A comparative cohort study was designed after a sample size calculation. A total of 40 patients were studied with 20 in each cohort (RSA vs BIO-RSA). All patients underwent an interview and physical examination. Outcomes included range of motion; shoulder strength; Disabilities of the Arm, Shoulder and Hand (DASH) score; American Shoulder and Elbow Surgeons score; Simple Shoulder Test score; Constant score; and Global Rating of Change scale score. Radiographs were obtained for all patients and examined for scapular notching. Results: When we compared demographic characteristics between the standard RSA and BIO-RSA cohorts, including age, sex, and follow-up duration, there were no significant differences between groups (P > .05). In addition, there were no significant differences between cohorts when we compared forward elevation (P ¼ .418); external rotation (P ¼ .999); internal rotation (P ¼ .071); strength (P > .376); Disabilities of the Arm, Shoulder and Hand score (P ¼ .229); American Shoulder and Elbow Surgeons score (P ¼ .579); Simple Shoulder Test score (P ¼ .522); Constant score (P ¼ .917); or Global Rating of Change scale score (P ¼ .167). The frequency of scapular notching, however, was significantly higher (P ¼ .022) in the RSA cohort than in the BIO-RSA cohort: 75% versus 40%. Conclusions: Although the scapular notching rate was significantly higher in the standard RSA group, no other outcome measures were statistically different, including range of motion, strength, and validated outcome scores.
Institutional review board approval was obtained from Western University/ St. Joseph’s Health Care (file No. 103218).
*Reprint requests: George S. Athwal, MD, FRCSC, St. Joseph’s Health Care, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4L6, Canada. E-mail address: [email protected] (G.S. Athwal).
1058-2746/$ - see front matter Ó 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. http://dx.doi.org/10.1016/j.jse.2014.08.015
2
G.S. Athwal et al. Level of evidence: Level III, Retrospective Cohort Design, Treatment Study. Ó 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Reverse shoulder arthroplasty; BIO-RSA; scapular notching; complications; cuff tear arthropathy
The literature has shown that reverse shoulder arthroplasty (RSA) is an effective and safe surgical treatment option for the management of symptomatic rotator cuff tear arthropathy. RSA can predictably decrease pain and improve function in most patients. Unfortunately, a common problem after RSA is scapular notching. This is believed to occur because of impingement in adduction between the medial aspect of the humeral component and the lateral pillar of the scapula. Impingement in this location results in scapular bone loss, referred to as ‘‘scapular notching.’’ Scapular notching has been classified by Sirveaux et al7 into 5 grades: grade 0, no visible notching; grade 1, notching confined to the lateral pillar; grade 2, notching that contacts the inferior screw of the glenoid baseplate; grade 3, notching that extends past the inferior screw; and grade 4, notching that extends under the baseplate to involve the central post. The literature describing the impact of scapular notching on patient outcomes shows disagreement. Some studies have reported no difference in patient outcomes with notching,4,8 whereas others have identified worse outcomes with higher grades of notching.6,7 Several methods exist to decrease notching; one purported technique is the placement of structural bone graft beneath the glenoid baseplate to provide glenosphere lateralization. This technique has been referred to as bony increased-offset reverse shoulder arthroplasty (BIO-RSA).1 BIO-RSA has also been described as a technique to improve the arc of rotational range of motion, by limiting terminal impingement. This technique, however, has not been comparatively studied to determine whether it is more effective at limiting notching and improving range of motion than a standard RSA. Therefore, the purpose of this retrospective cohort study was to compare notching rates, range of motion, and functional outcomes between patients who have undergone standard RSA and patients who have undergone BIO-RSA at a minimum of 2 years’ follow-up. We hypothesized that the BIO-RSA cohort would have a lower notching rate and improved rotational range of motion; however, validated outcome scores between cohorts would be no different.
Methods A retrospective comparative cohort study was designed after a sample size calculation indicated that a total of 36 patients (18 in each cohort) would be required to show a 50% reduction in notching rates (a ¼ .05, l ¼ 7.99). This sample size would also allow detection of a minimal clinically important difference of 6.4
American Shoulder and Elbow Surgeons (ASES) points between cohorts5 (TB Edwards et al unpublished data March 2013). For enhancement, the total study group was increased to 40 patients, with 20 in each cohort. The first cohort consisted of patients undergoing a standard Grammont-style RSA. The second cohort consisted of 20 patients undergoing the BIO-RSA technique applied to the same Grammont-style implant. Patients with rotator cuff tear arthropathy who underwent RSA between 2008 and 2012 were identified for possible inclusion in the study. The inclusion criteria included the following: age between 65 and 85 years; clear mental status; postoperative period greater than 24 months; and the ability to return for comprehensive assessment including outcome scores, strength measurements, and radiographs. The exclusion criteria included rheumatoid and/or inflammatory arthritis, osteoarthritis, fracture, nonunion, malunion, prior open shoulder surgery, humeral or glenoid bone loss that normally would require bone grafting or augmented implants, workers’ compensation claims, and unresolved litigation. An independent research coordinator constructed the cohorts. The BIO-RSA cohort comprised consecutive cases, meeting the aforementioned inclusion and exclusion criteria, who underwent primary BIO-RSA conducted by a single surgeon (G.S.A.) during the study period. Each of these cases was then matched with a corresponding standard RSA case by age at the time of surgery, follow-up duration, and sex.
Surgical technique For the standard cohort, all patients underwent a Grammont-style RSA with the Tornier Aequalis system (Tornier, Bloomington, MN, USA). All standard RSA procedures were conducted by fellowship-trained shoulder surgeons (K.J.F. and D.D.). The operative procedure was conducted through a deltopectoral approach following the technical manual of the implant. The glenoid baseplate was placed on the inferior margin of the glenoid rim. A 36-mm glenosphere was used in 13 cases and a 42-mm glenosphere in 7 cases. The BIO-RSA procedure also used the Tornier Aequalis system, and all surgical procedures were conducted by a single fellowship-trained shoulder surgeon (G.S.A.). The BIO-RSA technique involved harvesting a 10-mm-thick cylindrical autograft from the humeral head as described by Boileau et al.1 A glenoid baseplate implant with an extended 25-mm central post was used to ensure host bone contact with the BIO-RSA. A 36mm glenosphere was used in 15 cases and a 42-mm glenosphere in 5 cases.
Clinical and radiographic outcomes All patients returned for follow-up specifically for this study. All patients underwent an interview and physical examination by an
Bony-increased offset reverse shoulder arthroplasty
Figure 1
3
Anteroposterior radiographs of 3 cases of BIO-RSA with Sirveaux grade 0 (A), grade 1 (B), and grade 2 (C) scapular notching.
experienced shoulder research coordinator. Standard shoulder ranges of motion (active forward elevation and active external rotation in adduction) were measured with a long-arm goniometer, and internal rotation was measured to the highest vertebral level reached with the patient’s extended thumb. Shoulder strength was measured with a handheld dynamometer (Lafayette Instrument, Lafayette, IN, USA). Flexion strength was measured at 90 of forward elevation, and abduction strength was measured with the arm in adduction initiating abduction. Rotational strength (internal and external) was measured with the arm in adduction and neutral rotation. Validated outcome scores were administered, including the Disabilities of the Arm, Shoulder and Hand (DASH) score; ASES score; Simple Shoulder Test (SST) score; Constant score; and Global Rating of Change (GRC) scale rating. The GRC scale allows a patient to rate how his or her health condition (rotator cuff tear arthropathy) has improved or deteriorated after surgery.3 The GRC scale progresses in a numeric analog fashion in 1-cm increments from a score of 5 to a score of þ5. A rating of 5 indicates that the patient is ‘‘very much worse,’’ 0 indicates ‘‘unchanged,’’ and þ5 indicates that the patient has ‘‘completely recovered.’’ Shoulder radiographs were obtained for all patients at final follow-up. The radiographs were reviewed independently by 2 fellowship-trained shoulder surgeons who were uninvolved with the primary surgical procedures (K.M.R. and J.P.M.). Scapular notching was rated on the anteroposterior scapular radiograph according to the system of Sirveaux et al7 (Figs. 1 and 2). For the BIO-RSA cohort, graft incorporation was graded according to the system of Boileau et al.1 This classification describes the bone graft as incorporated, partially incorporated, or resorbed.
Statistical analysis Descriptive statistics, including means and standard deviations, were reported for outcome variables. For statistical comparisons between cohorts, interval-scale variables were tested with the independent-samples t test and ordinal-scale variables with the Mann-Whitney U test as required. A weighted k value was used to test agreement between 2 raters for scapular notching grade and bone graft incorporation classification.
Results For the entire cohort of 40 patients, the mean age at surgery was 74 6 years and there were 17 male and 23 female patients. At a mean follow-up of 34 13 months (all patients had >24 months’ follow-up), the mean DASH score was 20 16, the mean ASES score was 69 11, the mean SST score was 9.6 2.4, the mean Constant score was 61 10, and the mean GRC scale rating was þ4.5 0.5. The mean range of motion at final follow-up was as follows: active forward elevation, 141 14 ; active external rotation, 23 16 ; and active internal rotation to the sacrum. The strength of the operative arm at follow-up was as follows: flexion strength, 5.9 1.9 kg; abduction strength, 4.7 1.9 kg; external rotation strength, 3.3 1.5 kg; and internal rotation strength, 4.9 1.7 kg. Overall, the scapular notching rate was 58%, with 19 of 40 patients showing grade 1 notching, 3 patients with grade 2 notching, and 1 patient with grade 4 notching. When we compared demographic characteristics between the standard RSA and BIO-RSA cohorts, including age, sex, and follow-up duration, there were no statistically significant differences between groups (P > .05) (Table I). In addition, there were no statistically significant differences at latest follow-up between cohorts when we compared the DASH score (P ¼ .229), ASES score (P ¼ .579), SST score (P ¼ .522), Constant score (P ¼ .917), or GRC scale rating (P ¼ .167). When we compared range of motion between cohorts, there were no statistically significant differences in active forward elevation (P ¼ .418), active external rotation (P ¼ .999), or active internal rotation (P ¼ .071). Finally, there were no statistically significant differences in strength between the cohorts (P > .376) (Table I). Scapular notching, however, was significantly different between cohorts (P ¼ .022): 75% of standard RSA patients (15 of 20 patients) exhibited notching, whereas only 40% of the BIO-RSA cohort (8 of 20
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Figure 2 Anteroposterior radiographs of 3 cases of standard Grammont-style RSA with Sirveaux grade 0 (A), grade 1 (B), and grade 2 (C) scapular notching.
patients) had evidence of notching (Table I, Figs. 1 and 2). In the standard RSA group, 12 patients (60%) had grade 1 notching, 2 patients (10%) had grade 2 notching, and 1 patient (5%) had grade 4 notching. In the BIO-RSA group, 7 patients (35%) had grade 1 notching, 1 patient (5%) had grade 2 notching, and no patients had grade 3 or 4 notching. The agreement between raters for the classification of scapular notching was considered good, with a weighted k value of 0.796 and a 95% confidence interval from 0.536 to 0.905. In the BIO-RSA cohort at final follow-up, 16 patients (80%) had complete incorporation of the bone graft and 4 patients had partial incorporation. The agreement between raters for bone graft incorporation was rated as fair, with a weighted k value of 0.307 and a 95% confidence interval from 0.016 to 0.690.
To determine whether the presence of scapular notching had an influence on outcomes, the entire cohort was divided into cases without notching (17 patients) and cases with notching (23 patients). Comparing the non-notching cohort with the notching cohort showed no statistically significant differences in age (P ¼ .349), follow-up (P ¼ .863), range of motion (P > .491), strength (P > .060), or functional scores (P > .556) (Table II).
Discussion Scapular notching has been described as a problem, rather than a complication, after RSA.9 The reported incidence of notching in the literature varies and has been associated with implant design characteristics. A recent systematic
Bony-increased offset reverse shoulder arthroplasty Table I Comparison of standard RSA versus BIO-RSA at mean of 2.8 years’ follow-up Standard RSA BIO-RSA Age, y 73 5 Follow-up, mo 36 11 DASH score 15 15 ASES score 70 10 SST score 9.8 2.2 Constant score 61 10 GRC scale rating 4.8 0.5 143 13 Active forward elevation, Active external 23 16 rotation, Active internal 45% rotation >T12 Strength flexion, kg 5.7 2.0 Strength abduction, kg 4.7 2.0 Strength external 3.5 1.4 rotation, kg Strength internal 5.0 2.1 rotation, kg Scapular notching 75% (15/20) (total) Grade 1 notching 60% (12/20) Grade 2 notching 10% (2/20) Grade 3 notching 0 Grade 4 notching 5% (1/20)
76 31 21 68 9.3 61 4.6 140
5 Table II Comparison of notching cohort versus nonnotching cohort at mean of 2.8 years’ follow-up
P value
6 15 17 12 2.6 12 0.4 16
.093 .251 .229 .579 .522 .917 .167 .418
23 15
.999
25%
.071
6.2 1.8 4.9 1.7 3.1 1.6
.357 .726 .376
4.7 1.3
.533
Non-notching cohort Age, y Follow-up, y DASH score ASES score SST score Constant score GRC scale rating Active forward elevation, Active external rotation, Strength flexion, kg Strength abduction, kg Strength external rotation, kg Strength internal rotation, kg
75 2.8 20 68 9 61 4.7 141
6 1 20 12 3 12 0.4 18
Notching cohort 74 2.8 17 69 10 60 4.7 142
P value
5 1 13 10 2 9 0.5 11
.349 .863 .556 .680 .573 .795 .969 .701
25 19
22 13
.491
6.6 2.2 5.4 2.2 3.5 1.8
5.5 1.5 4.3 1.5 3.2 1.2
.060 .070 .612
5.2 1.8
4.6 1.7
.256
40% (8/20) .022 35% (7/20) 5% (1/20) 0 0
review reported an overall notching rate of 35%, with a 50% notching rate with use of a Grammont-style implant.9 Several methods may be used to decrease the potential for impingement between the medial aspect of the humeral implant and the lateral scapular pillar, such as increased glenosphere size and increased glenosphere offset. Boileau et al1 described the BIO-RSA in 2011. In their article, they reported a 19% scapular notching rate. The rate of notching in our BIO-RSA cohort was higher, at 40%. In addition, our rate of complete graft incorporation was slightly lower than that of Boileau et al: 80% versus 98%. However, our ability to classify bone graft healing was only fair, with a weighted k value of only 0.307. This fair reliability may be the result of our method of assessment because we only used radiographic means. Boileau et al, in their study on the BIO-RSA, recommended the use of computed tomography in addition to radiographs. Other purported advantages of the BIO-RSA include improved range of motion, improved stability, and better shoulder contour. Although we did not specifically examine shoulder contour, we found no significant differences in patient satisfaction (P ¼ .167). In addition, when we compared active forward elevation and external rotation, no significant differences were identified between cohorts and our mean values for forward elevation and external rotation (140 and 23 , respectively) are similar to the range of motion reported by Boileau et al (146 and 23 ,
respectively). When we examined internal rotation, there were no statistically significant differences between cohorts (P ¼ .071). The effects of glenoid lateralization have been studied in biomechanical models.2 These models indicate that lateralization places the deltoid lever arm at a mechanical disadvantage when compared with a more medialized implant. The deltoid force required to attain active forward elevation is increased with greater lateralization. Although we hypothesized that glenoid lateralization that occurs in patients treated with BIO-RSA would diminish deltoid strength, our results did not show a significant difference in deltoid strength between cohorts (P > .376). The literature on the outcomes of scapular notching is variable, with some authors finding no difference4,8 and other authors stating that high degrees of notching negatively affect outcome scores.6,7 To determine the effect of notching on outcome scores and range of motion, we compared the notching cohort with the non-notching cohort. Interestingly, we found no significant differences with respect to range of motion (P > .491) or functional scores (P > .556). An observational trend of greater abduction strength (P ¼ .070) and flexion strength (P ¼ .060) in the non-notching cohort when compared with the notching cohort was noted during handheld dynamometer strength testing; however, we found it difficult to explain this slightly increased strength because other strength measurements and functional scoresdincluding the Constant score, which incorporates strengthdwere similar. This study has several strengths, including the inclusion of a control cohort of patients undergoing standard RSA. In addition, the sample size calculation was powered to show
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a clinically significant difference between groups. Moreover, all patients underwent RSA with the same implant. The limitations of this study include its retrospective nature. However, although patients were retrospectively identified, all returned for a comprehensive assessment using validated outcome measures. Another weakness is that we used standard radiographs to assess bone graft incorporation. The use of computed tomography or fluoroscopically assisted radiographs may have improved graft visualization and classification. Moreover, this study assessed patients at a mean of 34 13 months’ follow-up, and the results may change with longer-term follow-up when differences or similarities may become more apparent.
Conclusion This comparative cohort study showed no substantial differences between standard RSA and BIO-RSA with respect to range of motion, strength, or validated outcome scores at a minimum of 2 years’ follow-up, whereas the rate of scapular notching was significantly lower in the BIO-RSA cohort than in the standard Grammont-style arthroplasty cohort. However, at shortterm follow-up, the presence of scapular notching did not have a substantial effect on patient outcomes.
Acknowledgments We thank Dr T. Bradley Edwards for assistance with this research project.
Disclaimer A research foundation with which George S. Athwal, Kenneth J. Faber, and Darren Drosdowech are affiliated received research support from Tornier, which
manufactures the implant used in this study. Tornier had no input into this research project in any manner. The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
References 1. Boileau P, Moineau G, Roussanne Y, O’Shea K. Bony increased-offset reversed shoulder arthroplasty: minimizing scapular impingement while maximizing glenoid fixation. Clin Orthop Relat Res 2011;469:2558-67. http://dx.doi.org/10.1007/s11999-011-1775-4 2. Henninger HB, Barg A, Anderson AE, Bachus KN, Burks RT, Tashjian RZ. Effect of lateral offset center of rotation in reverse total shoulder arthroplasty: a biomechanical study. J Shoulder Elbow Surg 2012;21:1128-35. http://dx.doi.org/10.1016/j.jse.2011.07.034 3. Kamper SJ, Maher CG, Mackay G. Global rating of change scales: a review of strengths and weaknesses and considerations for design. J Man Manip Ther 2009;17:163-70. 4. Levigne C, Boileau P, Favard L, Garaud P, Mole D, Sirveaux F, et al. Scapular notching in reverse shoulder arthroplasty. J Shoulder Elbow Surg 2008;17:925-35. http://dx.doi.org/10.1016/j.jse.2008.02.010 5. Michener LA, McClure PW, Sennett BJ. American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, patient self-report section: reliability, validity, and responsiveness. J Shoulder Elbow Surg 2002;11:587-94. http://dx.doi.org/10.1067/mse.2002.127096 6. Simovitch RW, Zumstein MA, Lohri E, Helmy N, Gerber C. Predictors of scapular notching in patients managed with the Delta III reverse total shoulder replacement. J Bone Joint Surg Am 2007;89:588-600. http:// dx.doi.org/10.2106/JBJS.F.00226 7. Sirveaux F, Favard L, Oudet D, Huquet D, Walch G, Mole D. Grammont inverted total shoulder arthroplasty in the treatment of glenohumeral osteoarthritis with massive rupture of the cuff. Results of a multicentre study of 80 shoulders. J Bone Joint Surg Br 2004;86:38895. http://dx.doi.org/10.1302/0301-620X.86B3.14024 8. Werner CM, Steinmann PA, Gilbart M, Gerber C. Treatment of painful pseudoparesis due to irreparable rotator cuff dysfunction with the Delta III reverse-ball-and-socket total shoulder prosthesis. J Bone Joint Surg Am 2005;87:1476-86. http://dx.doi.org/10.2106/JBJS.D.02342 9. Zumstein MA, Pinedo M, Old J, Boileau P. Problems, complications, reoperations, and revisions in reverse total shoulder arthroplasty: a systematic review. J Shoulder Elbow Surg 2011;20:146-57. http://dx. doi.org/10.1016/j.jse.2010.08.001
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Does bony increased-offset reverse shoulder arthroplasty decrease scapular notching? George S. Athwal, MD, FRCSC*, Joy C. MacDermid, PhD, K. Murali Reddy, MD, FRACS, Jonathan P. Marsh, MD, FRCSC, Kenneth J. Faber, MD, MHPE, FRCSC, Darren Drosdowech, MD, FRCSC RothjMcFarlane Hand and Upper Limb Center, St. Joseph’s Health Care, University of Western Ontario, London, Ontario, Canada Background: The purpose of this cohort study was to compare scapular notching rates, range of motion, and functional outcomes between patients who underwent a standard Grammont-style reverse shoulder arthroplasty (RSA) and patients who underwent bony increased-offset reverse shoulder arthroplasty (BIO-RSA) at a minimum of 2 years’ follow-up. We hypothesized that the BIO-RSA cohort would have lower notching rates and improved rotational range of motion; however, validated outcome scores between cohorts would be no different. Methods: A comparative cohort study was designed after a sample size calculation. A total of 40 patients were studied with 20 in each cohort (RSA vs BIO-RSA). All patients underwent an interview and physical examination. Outcomes included range of motion; shoulder strength; Disabilities of the Arm, Shoulder and Hand (DASH) score; American Shoulder and Elbow Surgeons score; Simple Shoulder Test score; Constant score; and Global Rating of Change scale score. Radiographs were obtained for all patients and examined for scapular notching. Results: When we compared demographic characteristics between the standard RSA and BIO-RSA cohorts, including age, sex, and follow-up duration, there were no significant differences between groups (P > .05). In addition, there were no significant differences between cohorts when we compared forward elevation (P ¼ .418); external rotation (P ¼ .999); internal rotation (P ¼ .071); strength (P > .376); Disabilities of the Arm, Shoulder and Hand score (P ¼ .229); American Shoulder and Elbow Surgeons score (P ¼ .579); Simple Shoulder Test score (P ¼ .522); Constant score (P ¼ .917); or Global Rating of Change scale score (P ¼ .167). The frequency of scapular notching, however, was significantly higher (P ¼ .022) in the RSA cohort than in the BIO-RSA cohort: 75% versus 40%. Conclusions: Although the scapular notching rate was significantly higher in the standard RSA group, no other outcome measures were statistically different, including range of motion, strength, and validated outcome scores.
Institutional review board approval was obtained from Western University/ St. Joseph’s Health Care (file No. 103218).
*Reprint requests: George S. Athwal, MD, FRCSC, St. Joseph’s Health Care, University of Western Ontario, 268 Grosvenor Street, London, ON N6A 4L6, Canada. E-mail address: [email protected] (G.S. Athwal).
1058-2746/$ - see front matter Ó 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. http://dx.doi.org/10.1016/j.jse.2014.08.015
2
G.S. Athwal et al. Level of evidence: Level III, Retrospective Cohort Design, Treatment Study. Ó 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Reverse shoulder arthroplasty; BIO-RSA; scapular notching; complications; cuff tear arthropathy
The literature has shown that reverse shoulder arthroplasty (RSA) is an effective and safe surgical treatment option for the management of symptomatic rotator cuff tear arthropathy. RSA can predictably decrease pain and improve function in most patients. Unfortunately, a common problem after RSA is scapular notching. This is believed to occur because of impingement in adduction between the medial aspect of the humeral component and the lateral pillar of the scapula. Impingement in this location results in scapular bone loss, referred to as ‘‘scapular notching.’’ Scapular notching has been classified by Sirveaux et al7 into 5 grades: grade 0, no visible notching; grade 1, notching confined to the lateral pillar; grade 2, notching that contacts the inferior screw of the glenoid baseplate; grade 3, notching that extends past the inferior screw; and grade 4, notching that extends under the baseplate to involve the central post. The literature describing the impact of scapular notching on patient outcomes shows disagreement. Some studies have reported no difference in patient outcomes with notching,4,8 whereas others have identified worse outcomes with higher grades of notching.6,7 Several methods exist to decrease notching; one purported technique is the placement of structural bone graft beneath the glenoid baseplate to provide glenosphere lateralization. This technique has been referred to as bony increased-offset reverse shoulder arthroplasty (BIO-RSA).1 BIO-RSA has also been described as a technique to improve the arc of rotational range of motion, by limiting terminal impingement. This technique, however, has not been comparatively studied to determine whether it is more effective at limiting notching and improving range of motion than a standard RSA. Therefore, the purpose of this retrospective cohort study was to compare notching rates, range of motion, and functional outcomes between patients who have undergone standard RSA and patients who have undergone BIO-RSA at a minimum of 2 years’ follow-up. We hypothesized that the BIO-RSA cohort would have a lower notching rate and improved rotational range of motion; however, validated outcome scores between cohorts would be no different.
Methods A retrospective comparative cohort study was designed after a sample size calculation indicated that a total of 36 patients (18 in each cohort) would be required to show a 50% reduction in notching rates (a ¼ .05, l ¼ 7.99). This sample size would also allow detection of a minimal clinically important difference of 6.4
American Shoulder and Elbow Surgeons (ASES) points between cohorts5 (TB Edwards et al unpublished data March 2013). For enhancement, the total study group was increased to 40 patients, with 20 in each cohort. The first cohort consisted of patients undergoing a standard Grammont-style RSA. The second cohort consisted of 20 patients undergoing the BIO-RSA technique applied to the same Grammont-style implant. Patients with rotator cuff tear arthropathy who underwent RSA between 2008 and 2012 were identified for possible inclusion in the study. The inclusion criteria included the following: age between 65 and 85 years; clear mental status; postoperative period greater than 24 months; and the ability to return for comprehensive assessment including outcome scores, strength measurements, and radiographs. The exclusion criteria included rheumatoid and/or inflammatory arthritis, osteoarthritis, fracture, nonunion, malunion, prior open shoulder surgery, humeral or glenoid bone loss that normally would require bone grafting or augmented implants, workers’ compensation claims, and unresolved litigation. An independent research coordinator constructed the cohorts. The BIO-RSA cohort comprised consecutive cases, meeting the aforementioned inclusion and exclusion criteria, who underwent primary BIO-RSA conducted by a single surgeon (G.S.A.) during the study period. Each of these cases was then matched with a corresponding standard RSA case by age at the time of surgery, follow-up duration, and sex.
Surgical technique For the standard cohort, all patients underwent a Grammont-style RSA with the Tornier Aequalis system (Tornier, Bloomington, MN, USA). All standard RSA procedures were conducted by fellowship-trained shoulder surgeons (K.J.F. and D.D.). The operative procedure was conducted through a deltopectoral approach following the technical manual of the implant. The glenoid baseplate was placed on the inferior margin of the glenoid rim. A 36-mm glenosphere was used in 13 cases and a 42-mm glenosphere in 7 cases. The BIO-RSA procedure also used the Tornier Aequalis system, and all surgical procedures were conducted by a single fellowship-trained shoulder surgeon (G.S.A.). The BIO-RSA technique involved harvesting a 10-mm-thick cylindrical autograft from the humeral head as described by Boileau et al.1 A glenoid baseplate implant with an extended 25-mm central post was used to ensure host bone contact with the BIO-RSA. A 36mm glenosphere was used in 15 cases and a 42-mm glenosphere in 5 cases.
Clinical and radiographic outcomes All patients returned for follow-up specifically for this study. All patients underwent an interview and physical examination by an
Bony-increased offset reverse shoulder arthroplasty
Figure 1
3
Anteroposterior radiographs of 3 cases of BIO-RSA with Sirveaux grade 0 (A), grade 1 (B), and grade 2 (C) scapular notching.
experienced shoulder research coordinator. Standard shoulder ranges of motion (active forward elevation and active external rotation in adduction) were measured with a long-arm goniometer, and internal rotation was measured to the highest vertebral level reached with the patient’s extended thumb. Shoulder strength was measured with a handheld dynamometer (Lafayette Instrument, Lafayette, IN, USA). Flexion strength was measured at 90 of forward elevation, and abduction strength was measured with the arm in adduction initiating abduction. Rotational strength (internal and external) was measured with the arm in adduction and neutral rotation. Validated outcome scores were administered, including the Disabilities of the Arm, Shoulder and Hand (DASH) score; ASES score; Simple Shoulder Test (SST) score; Constant score; and Global Rating of Change (GRC) scale rating. The GRC scale allows a patient to rate how his or her health condition (rotator cuff tear arthropathy) has improved or deteriorated after surgery.3 The GRC scale progresses in a numeric analog fashion in 1-cm increments from a score of 5 to a score of þ5. A rating of 5 indicates that the patient is ‘‘very much worse,’’ 0 indicates ‘‘unchanged,’’ and þ5 indicates that the patient has ‘‘completely recovered.’’ Shoulder radiographs were obtained for all patients at final follow-up. The radiographs were reviewed independently by 2 fellowship-trained shoulder surgeons who were uninvolved with the primary surgical procedures (K.M.R. and J.P.M.). Scapular notching was rated on the anteroposterior scapular radiograph according to the system of Sirveaux et al7 (Figs. 1 and 2). For the BIO-RSA cohort, graft incorporation was graded according to the system of Boileau et al.1 This classification describes the bone graft as incorporated, partially incorporated, or resorbed.
Statistical analysis Descriptive statistics, including means and standard deviations, were reported for outcome variables. For statistical comparisons between cohorts, interval-scale variables were tested with the independent-samples t test and ordinal-scale variables with the Mann-Whitney U test as required. A weighted k value was used to test agreement between 2 raters for scapular notching grade and bone graft incorporation classification.
Results For the entire cohort of 40 patients, the mean age at surgery was 74 6 years and there were 17 male and 23 female patients. At a mean follow-up of 34 13 months (all patients had >24 months’ follow-up), the mean DASH score was 20 16, the mean ASES score was 69 11, the mean SST score was 9.6 2.4, the mean Constant score was 61 10, and the mean GRC scale rating was þ4.5 0.5. The mean range of motion at final follow-up was as follows: active forward elevation, 141 14 ; active external rotation, 23 16 ; and active internal rotation to the sacrum. The strength of the operative arm at follow-up was as follows: flexion strength, 5.9 1.9 kg; abduction strength, 4.7 1.9 kg; external rotation strength, 3.3 1.5 kg; and internal rotation strength, 4.9 1.7 kg. Overall, the scapular notching rate was 58%, with 19 of 40 patients showing grade 1 notching, 3 patients with grade 2 notching, and 1 patient with grade 4 notching. When we compared demographic characteristics between the standard RSA and BIO-RSA cohorts, including age, sex, and follow-up duration, there were no statistically significant differences between groups (P > .05) (Table I). In addition, there were no statistically significant differences at latest follow-up between cohorts when we compared the DASH score (P ¼ .229), ASES score (P ¼ .579), SST score (P ¼ .522), Constant score (P ¼ .917), or GRC scale rating (P ¼ .167). When we compared range of motion between cohorts, there were no statistically significant differences in active forward elevation (P ¼ .418), active external rotation (P ¼ .999), or active internal rotation (P ¼ .071). Finally, there were no statistically significant differences in strength between the cohorts (P > .376) (Table I). Scapular notching, however, was significantly different between cohorts (P ¼ .022): 75% of standard RSA patients (15 of 20 patients) exhibited notching, whereas only 40% of the BIO-RSA cohort (8 of 20
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Figure 2 Anteroposterior radiographs of 3 cases of standard Grammont-style RSA with Sirveaux grade 0 (A), grade 1 (B), and grade 2 (C) scapular notching.
patients) had evidence of notching (Table I, Figs. 1 and 2). In the standard RSA group, 12 patients (60%) had grade 1 notching, 2 patients (10%) had grade 2 notching, and 1 patient (5%) had grade 4 notching. In the BIO-RSA group, 7 patients (35%) had grade 1 notching, 1 patient (5%) had grade 2 notching, and no patients had grade 3 or 4 notching. The agreement between raters for the classification of scapular notching was considered good, with a weighted k value of 0.796 and a 95% confidence interval from 0.536 to 0.905. In the BIO-RSA cohort at final follow-up, 16 patients (80%) had complete incorporation of the bone graft and 4 patients had partial incorporation. The agreement between raters for bone graft incorporation was rated as fair, with a weighted k value of 0.307 and a 95% confidence interval from 0.016 to 0.690.
To determine whether the presence of scapular notching had an influence on outcomes, the entire cohort was divided into cases without notching (17 patients) and cases with notching (23 patients). Comparing the non-notching cohort with the notching cohort showed no statistically significant differences in age (P ¼ .349), follow-up (P ¼ .863), range of motion (P > .491), strength (P > .060), or functional scores (P > .556) (Table II).
Discussion Scapular notching has been described as a problem, rather than a complication, after RSA.9 The reported incidence of notching in the literature varies and has been associated with implant design characteristics. A recent systematic
Bony-increased offset reverse shoulder arthroplasty Table I Comparison of standard RSA versus BIO-RSA at mean of 2.8 years’ follow-up Standard RSA BIO-RSA Age, y 73 5 Follow-up, mo 36 11 DASH score 15 15 ASES score 70 10 SST score 9.8 2.2 Constant score 61 10 GRC scale rating 4.8 0.5 143 13 Active forward elevation, Active external 23 16 rotation, Active internal 45% rotation >T12 Strength flexion, kg 5.7 2.0 Strength abduction, kg 4.7 2.0 Strength external 3.5 1.4 rotation, kg Strength internal 5.0 2.1 rotation, kg Scapular notching 75% (15/20) (total) Grade 1 notching 60% (12/20) Grade 2 notching 10% (2/20) Grade 3 notching 0 Grade 4 notching 5% (1/20)
76 31 21 68 9.3 61 4.6 140
5 Table II Comparison of notching cohort versus nonnotching cohort at mean of 2.8 years’ follow-up
P value
6 15 17 12 2.6 12 0.4 16
.093 .251 .229 .579 .522 .917 .167 .418
23 15
.999
25%
.071
6.2 1.8 4.9 1.7 3.1 1.6
.357 .726 .376
4.7 1.3
.533
Non-notching cohort Age, y Follow-up, y DASH score ASES score SST score Constant score GRC scale rating Active forward elevation, Active external rotation, Strength flexion, kg Strength abduction, kg Strength external rotation, kg Strength internal rotation, kg
75 2.8 20 68 9 61 4.7 141
6 1 20 12 3 12 0.4 18
Notching cohort 74 2.8 17 69 10 60 4.7 142
P value
5 1 13 10 2 9 0.5 11
.349 .863 .556 .680 .573 .795 .969 .701
25 19
22 13
.491
6.6 2.2 5.4 2.2 3.5 1.8
5.5 1.5 4.3 1.5 3.2 1.2
.060 .070 .612
5.2 1.8
4.6 1.7
.256
40% (8/20) .022 35% (7/20) 5% (1/20) 0 0
review reported an overall notching rate of 35%, with a 50% notching rate with use of a Grammont-style implant.9 Several methods may be used to decrease the potential for impingement between the medial aspect of the humeral implant and the lateral scapular pillar, such as increased glenosphere size and increased glenosphere offset. Boileau et al1 described the BIO-RSA in 2011. In their article, they reported a 19% scapular notching rate. The rate of notching in our BIO-RSA cohort was higher, at 40%. In addition, our rate of complete graft incorporation was slightly lower than that of Boileau et al: 80% versus 98%. However, our ability to classify bone graft healing was only fair, with a weighted k value of only 0.307. This fair reliability may be the result of our method of assessment because we only used radiographic means. Boileau et al, in their study on the BIO-RSA, recommended the use of computed tomography in addition to radiographs. Other purported advantages of the BIO-RSA include improved range of motion, improved stability, and better shoulder contour. Although we did not specifically examine shoulder contour, we found no significant differences in patient satisfaction (P ¼ .167). In addition, when we compared active forward elevation and external rotation, no significant differences were identified between cohorts and our mean values for forward elevation and external rotation (140 and 23 , respectively) are similar to the range of motion reported by Boileau et al (146 and 23 ,
respectively). When we examined internal rotation, there were no statistically significant differences between cohorts (P ¼ .071). The effects of glenoid lateralization have been studied in biomechanical models.2 These models indicate that lateralization places the deltoid lever arm at a mechanical disadvantage when compared with a more medialized implant. The deltoid force required to attain active forward elevation is increased with greater lateralization. Although we hypothesized that glenoid lateralization that occurs in patients treated with BIO-RSA would diminish deltoid strength, our results did not show a significant difference in deltoid strength between cohorts (P > .376). The literature on the outcomes of scapular notching is variable, with some authors finding no difference4,8 and other authors stating that high degrees of notching negatively affect outcome scores.6,7 To determine the effect of notching on outcome scores and range of motion, we compared the notching cohort with the non-notching cohort. Interestingly, we found no significant differences with respect to range of motion (P > .491) or functional scores (P > .556). An observational trend of greater abduction strength (P ¼ .070) and flexion strength (P ¼ .060) in the non-notching cohort when compared with the notching cohort was noted during handheld dynamometer strength testing; however, we found it difficult to explain this slightly increased strength because other strength measurements and functional scoresdincluding the Constant score, which incorporates strengthdwere similar. This study has several strengths, including the inclusion of a control cohort of patients undergoing standard RSA. In addition, the sample size calculation was powered to show
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a clinically significant difference between groups. Moreover, all patients underwent RSA with the same implant. The limitations of this study include its retrospective nature. However, although patients were retrospectively identified, all returned for a comprehensive assessment using validated outcome measures. Another weakness is that we used standard radiographs to assess bone graft incorporation. The use of computed tomography or fluoroscopically assisted radiographs may have improved graft visualization and classification. Moreover, this study assessed patients at a mean of 34 13 months’ follow-up, and the results may change with longer-term follow-up when differences or similarities may become more apparent.
Conclusion This comparative cohort study showed no substantial differences between standard RSA and BIO-RSA with respect to range of motion, strength, or validated outcome scores at a minimum of 2 years’ follow-up, whereas the rate of scapular notching was significantly lower in the BIO-RSA cohort than in the standard Grammont-style arthroplasty cohort. However, at shortterm follow-up, the presence of scapular notching did not have a substantial effect on patient outcomes.
Acknowledgments We thank Dr T. Bradley Edwards for assistance with this research project.
Disclaimer A research foundation with which George S. Athwal, Kenneth J. Faber, and Darren Drosdowech are affiliated received research support from Tornier, which
manufactures the implant used in this study. Tornier had no input into this research project in any manner. The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
References 1. Boileau P, Moineau G, Roussanne Y, O’Shea K. Bony increased-offset reversed shoulder arthroplasty: minimizing scapular impingement while maximizing glenoid fixation. Clin Orthop Relat Res 2011;469:2558-67. http://dx.doi.org/10.1007/s11999-011-1775-4 2. Henninger HB, Barg A, Anderson AE, Bachus KN, Burks RT, Tashjian RZ. Effect of lateral offset center of rotation in reverse total shoulder arthroplasty: a biomechanical study. J Shoulder Elbow Surg 2012;21:1128-35. http://dx.doi.org/10.1016/j.jse.2011.07.034 3. Kamper SJ, Maher CG, Mackay G. Global rating of change scales: a review of strengths and weaknesses and considerations for design. J Man Manip Ther 2009;17:163-70. 4. Levigne C, Boileau P, Favard L, Garaud P, Mole D, Sirveaux F, et al. Scapular notching in reverse shoulder arthroplasty. J Shoulder Elbow Surg 2008;17:925-35. http://dx.doi.org/10.1016/j.jse.2008.02.010 5. Michener LA, McClure PW, Sennett BJ. American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, patient self-report section: reliability, validity, and responsiveness. J Shoulder Elbow Surg 2002;11:587-94. http://dx.doi.org/10.1067/mse.2002.127096 6. Simovitch RW, Zumstein MA, Lohri E, Helmy N, Gerber C. Predictors of scapular notching in patients managed with the Delta III reverse total shoulder replacement. J Bone Joint Surg Am 2007;89:588-600. http:// dx.doi.org/10.2106/JBJS.F.00226 7. Sirveaux F, Favard L, Oudet D, Huquet D, Walch G, Mole D. Grammont inverted total shoulder arthroplasty in the treatment of glenohumeral osteoarthritis with massive rupture of the cuff. Results of a multicentre study of 80 shoulders. J Bone Joint Surg Br 2004;86:38895. http://dx.doi.org/10.1302/0301-620X.86B3.14024 8. Werner CM, Steinmann PA, Gilbart M, Gerber C. Treatment of painful pseudoparesis due to irreparable rotator cuff dysfunction with the Delta III reverse-ball-and-socket total shoulder prosthesis. J Bone Joint Surg Am 2005;87:1476-86. http://dx.doi.org/10.2106/JBJS.D.02342 9. Zumstein MA, Pinedo M, Old J, Boileau P. Problems, complications, reoperations, and revisions in reverse total shoulder arthroplasty: a systematic review. J Shoulder Elbow Surg 2011;20:146-57. http://dx. doi.org/10.1016/j.jse.2010.08.001
