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Do individualized humeral retroversion and subscapularis repair affect the clinical outcomes of reverse total shoulder arthroplasty?
J Shoulder Elbow Surg (2019) -, 1–9
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Do individualized humeral retroversion and subscapularis repair affect the clinical outcomes of reverse total shoulder arthroplasty? Joo Han Oh, MD, PhDa, Nikhil Sharma, MDb, Sung Min Rhee, MD, PhDc, Joo Hyun Park, MDd,* a
Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea b Holy Cross Hospital, Mumbai, India c Shoulder & Elbow Clinic, Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, Seoul, Republic of Korea d Bundang Jesaeng General Hospital, Daejin Medical Center, Seongnam, Republic of Korea Background: This study aimed to evaluate the effects of an individualized angle of humeral retroversion and subscapularis repair on clinical outcomes after reverse total shoulder arthroplasty (RTSA) using a lateralized prosthesis. Methods: A retrospective analysis of 80 patients who underwent RTSA and had a minimum of 2 years’ follow-up was performed. Individualization was based on the native retroversion angle, quantified from computed tomography images. Clinical outcomes (forward flexion, external rotation at the side, internal rotation at the back, functional scores, and pain) were compared between patients with individualized retroversion (group I, n ¼ 52) and patients with a fixed retroversion angle of 20 (group II, n ¼ 28). Group I was further subdivided into patients with a retroversion angle of 20 or less (subgroup A, n ¼ 21) and patients with a retroversion angle greater than 20 (subgroup B, n ¼ 31). We also compared outcomes in group I between patients with (n ¼ 40) and without (n ¼ 12) subscapularis repair. Results: Ranges of motion including external rotation and internal rotation, functional scores, and pain relief were significantly better in group I than in group II (P < .05 for all). No differences in clinical outcomes were found between subgroups A and B, although outcomes for both of these subgroups were better than those for group II (P < .05 for all). Subscapularis repair was not correlated with superior clinical outcomes. Conclusions: Individualized humeral retroversion may provide superior clinical outcomes to those of implantation of the humeral component at a fixed angle of 20 of retroversion. Repair of the subscapularis may not be essential for superior clinical outcomes in patients treated using a lateralized RTSA prosthesis.
The Seoul National University Bundang Hospital Institutional Review Board approved an exemption for this study because of its retrospective design (no. B-1808/487-107). *Reprint requests: Joo Hyun Park, MD, Department of Orthopaedic Surgery, Bundang Jesaeng General Hospital, Daejin Medical Center, 20,
Seohyeon-ro 180beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 13590, Republic of Korea. E-mail address: [email protected] (J.H. Park).
1058-2746/$ - see front matter Ó 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. https://doi.org/10.1016/j.jse.2019.08.016
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J.H. Oh et al. Level of evidence: Level III; Retrospective Cohort Design; Treatment Study Ó 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. Keywords: Shoulder; cuff tear arthropathy; reverse total shoulder arthroplasty; humeral retroversion; range of motion; subscapularis repair; subscapularis repair
Reverse total shoulder arthroplasty (RTSA) has become a standard treatment for cuff tear arthropathy (CTA) in older individuals, with documented good midterm clinical and radiologic outcomes.9,14,23 In addition, excellent clinical outcomes of RTSA have been reported in patients younger than 65 years, with a 10-year survival rate of 88%.9 RTSA was developed in response to the early failure of total shoulder arthroplasty, largely due to glenoid loosening, among patients with severe rotator cuff deficiency.26,33 RTSA reliably and effectively restores forward flexion (to 130 in shoulders with pseudoparalysis due to irreparable rupture of the rotator cuff) and provides shoulder pain relief.15,34,36,42 However, the selection of the ideal configuration and placement of the components to optimize shoulder function outcomes remains an issue of debate. Several studies have documented drawbacks of medialization of the center of rotation (COR), including glenoid notching and loss of shoulder rotation,4,16,22,27,29,36 with placement of the implant with a more lateral COR recently being preferred by many surgeons; the resultant position of the COR with this lateral offset more closely approximates that of the normal glenohumeral joint, decreasing scapular notching and improving rotation force.11 Range of motion (ROM) after RTSA can be influenced by 2 categories of factors: surgical factors that are considered modifiable (version of the humeral component, balancing of soft tissues, and so on) and prosthetic factors that are considered nonmodifiable (size of the implant, neck-shaft angle of the humeral component, and so on). Neer28 suggested that implants with a design that mimicked the normal anatomy would provide the best function and durability. In this regard, the importance of humeral retroversion and subscapularis repair for better clinical outcomes after RTSA is an issue of debate. In their biomechanical study, Stephenson et al37 concluded that placing the humeral component at between 20 and 40 of retroversion most closely restores the functional arc of motion of the shoulder without impingement whereas anteversion can significantly decrease the amount of external rotation achievable after RTSA. Gulotta et al17 reported that increased retroversion improved external rotation at the expense of decreased internal rotation but without affecting the scapular plane of elevation. In a clinical study, Kontaxis et al24 reported a preferred angle of 0 of version to prevent impingement with activities of daily living. Edwards et al8 reported a 2-fold increase in the relative rate of dislocation after RTSA when the subscapularis was not repaired. Dedy et al7 reported that
subscapularis integrity did not appear to have a measurable effect on the functional scores but was important for internal rotation ability after RTSA. However, Rhee et al35 concluded that ROM was not statistically significantly affected by retroversion of the humeral component between 0 and 20 , with no statistically significant effect of the status of the subscapularis (ruptured or repaired) on ROM. The issue of the difference between native and component-fixed humeral retroversion and subscapularis repair regarding the clinical outcomes of RTSA is unclear, and most previous studies were biomechanical cadaveric or computer simulation studies. There are limited data available to guide clinicians regarding the most appropriate approaches to optimize outcomes. Therefore, the purpose of our study was to investigate the effect of individualized humeral retroversion and subscapularis repair on clinical outcomes after lateralized RTSA. We assumed that clinical outcomes would be improved by considering native humeral version and repairing the subscapularis.
Materials and methods Patient selection The study group included patients who had undergone RTSA with a lateralized prosthesis (Biomet Comprehensive Reverse Shoulder System; Biomet, Warsaw, IN, USA) between January 2007 and January 2015; all procedures were performed by a single surgeon. The inclusion criteria were as follows: irreparable massive rotator cuff tear with pseudoparalysis, CTA, static superior migration of the humeral head, and failed rotator cuff repair. Patients with post-traumatic secondary osteoarthritis, assessed from patients’ medical records or anamnesis, as well as those with systemic inflammatory diseases, such as rheumatoid arthritis, and those undergoing revision for a failed shoulder arthroplasty or being treated with a prosthesis other than that for RTSA, were excluded. We retrospectively analyzed data from 80 patients who satisfied the inclusion and exclusion criteria and had a minimum follow-up period of 2 years after RTSA. For analysis, patients were classified into 2 groups based on the retroversion position of the humeral component relative to native humeral version, measured on computed tomography (CT) images: group I (n ¼ 52) had a range of retroversion from 10 to 40 in 5 increments, whereas group II (n ¼ 28) had fixed retroversion of 20 . A fixed retroversion position of the humeral components of 20 was used from January 2007 to January 2012, per the surgical protocol at our institution. After January 2012, we started individualizing the position of retroversion of the humeral component with respect to native version, estimated by CT.
Individualized humeral retroversion in RTSA
Preoperative and postoperative evaluation Each patient was followed up at 1, 3, and 6 months postoperatively and then annually. Pain was assessed at each visit using a visual analog scale for pain (pVAS), with anchors at 0 (no pain) and 10 (worst pain). Active ROM in forward flexion (scapular abduction) and external rotation (with the arm by the side) was measured by a handheld goniometer, with the patient in the supine position or the scapula’s position maintained by hand. Internal rotation was measured as the vertebral level reached by the tip of the thumb, with the patient in a sitting position, scored per a standard technique, with a score of 1 to 12 for reaching the first to 12th thoracic vertebra, a score of 13 to 17 for reaching the first to fifth lumbar vertebra, and a score of 18 for reaching the sacrum.5,30 ROM at the 2-year time point (or close to it) was compared between the 2 groups. Functional scores, including the American Shoulder and Elbow Surgeons (ASES) score and Simple Shoulder Test (SST) score, were obtained before surgery and at every annual follow-up visit.
Radiologic workup Preoperative radiographs were obtained in the true anteroposterior, axillary, and scapular Y views and in 30 of external rotation. Magnetic resonance imaging was performed to determine the status of the rotator cuff, with fatty degeneration and CTA confirmed and classified based on the Hamada classification.19 CT with 3-dimensional image reconstruction was performed to estimate the individual native version of the glenoid and humerus, on both the affected and contralateral sides, including assessment of glenoid wear or bone stock of the proximal humerus. Humeral retroversion on the affected side was calculated in relation to the contralateral side, using the standard method described by Boileau et al.3 CT scans from the elbow through the shoulder were performed on both sides in all patients. Elbow and humeral scans were separately performed to reduce radiation hazards. The central axis of the humeral head was defined on axial 2-dimensional CT scans as the perpendicular axis of the boundaries of the articular surface of the humeral head determined using the limits of the subchondral bone in the largest circle of the humeral head. The elbow transepicondylar axis was defined as the line between the most medial extension and most lateral extension of the distal humerus. Humeral retroversion was determined as the angle between the central axis of the humeral head and the elbow transepicondylar axis. If the articular surface of the humeral head was deformed or collapsed, owing to severe arthritic changes, the midline of the bicipital groove and the posterior margin of the bicipital groove were used as landmarks to assist with the determination of humeral head retroversion.25,31,38 Humeral retroversion was measured using the bicipital groove as a landmark in 24 patients (30%). The radiologist and surgeon separately measured the humeral retroversion angle of both shoulders as described earlier, and the average value of the 2 measurements was used. Intraobserver or interobserver reliability was not estimated in this study. According to Oh et al,31 all of alternative methods showed excellent reliability (interobserver reliability > 0.890) compared with the standard method. Because it was difficult to apply the exact measured angle of humeral retroversion in the operative field at the time of stem insertion, the retroversion angle could be applied in 5 increments with consideration of
3 the measurement of the contralateral side. The postoperative status of the implant was evaluated for scapular notching and implant loosening using radiography through the final follow-up visit.
Operative technique All procedures were performed by a single senior orthopedic surgeon using a single implant (Biomet Comprehensive Reverse Shoulder System). The glenohumeral joint was exposed through a standard deltopectoral approach. If the subscapularis muscle needed to be taken down to approach the joint, subscapularis tenotomy was performed longitudinally at 1 cm medial to the bicipital groove. After dislocation of the humeral head, sequential manual reaming, using 1-mm increments, was performed according to the diameter of the humeral shaft. A rotational guide was attached to the broach to determine the retroversion of the humeral component to be implanted. The humeral neck was then cut using a cutting guide. An intraoperative decision regarding retroversion was made by the senior author (J.H.O.) with the help of surgical assistants (fellows) using a retroversion guide attached to the handle that was parallel to the forearm during reaming, broaching, and implantation. Subsequently, glenoid preparation was completed using the standard method, with a guide pin placed at the center of the glenoid with a 10 inferior tilt. Glenoid reaming was performed over the guide pin to make neutral version. The glenoid baseplate was fixed to the glenoid using a central screw with 3 to 4 peripheral screws. A standard glenosphere (diameter, 36 mm) with a 3.5-mm inferior offset was implanted over the baseplate. If the preoperative version exceeded 15 , implantation of autogenous bone taken from the humeral head was performed with baseplate fixation. After reduction of humeral stem trial, we assessed implant stability and muscle tension. Massive irrigation was performed, and 3 drill holes were made on the lesser tuberosity of the humerus for subscapularis repair, using a bone-tunneling suture technique. After the humeral component was inserted, final reduction was performed with assessment of joint stability. In cases of a reparable subscapularis, the tendon was reattached to the lesser tuberosity using No. 2 Ethibond sutures (Ethicon, Somerville, NJ, USA). The long head of the biceps tendon was repaired, along with the subscapularis, as a soft-tissue tenodesis. A suction drain was inserted, with layerby-layer suturing. The shoulder joint was immobilized in a sling with a pillow for 4 weeks. Passive forward flexion exercise using a continuous passive motion machine was permitted in all patients during brace wearing (3-5 times a day, 20 minutes per time, with a step-by-step increment in angles) if implants were stably implanted. Activeassisted ROM exercise was performed for 6 to 8 weeks after weaning of sling immobilization. Usually, muscle-strengthening exercises were started at 3 months postoperatively, and all sports activities were allowed at 6 months after surgery.
Statistical analysis Continuous data are presented as mean (standard deviation) and categorical data, as number (percentage). Statistically significant differences in metrics were evaluated using independent and paired t tests for data with normal distributions. Nonparametric analysis (Mann-Whitney U and Wilcoxon signed rank tests) was used to
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J.H. Oh et al. Table I
Preoperative demographic data for individualized (group I) and fixed (group II) retroversion groups
Variable
Group I (n ¼ 52)
Group II (n ¼ 28)
P value
Age, yr Sex: M/F Indication for surgery: CTA/failed rotator cuff repair Preoperative shoulder stiffness: Y/N Follow-up period, mo Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
71.5 10/42 48/4 48/4 29.0 97.5 37.3 12.4 6.8 36.7 1.5
73.1 5/23 26/2 24/4 35.9 96.4 27.5 11.1 6.3 33.4 2.1
.253 .881 .999 .441 .032 .924 .055 .137 .395 .257 .159
6.9
8.3 49.8 21.1 3.8 2.1 16.6 1.7
4.8
15.2 43.2 22.3 3.8 3.1 18.2 1.9
M, male; F, female; CTA, cuff tear arthropathy; Y, yes; N, no; ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation or number of patients.
compare data found not to be normally distributed. The c2 test or Fisher exact test was used to analyze categorical variables such as patients’ sex and surgical indication; P < .05 was defined as statistically significant. All statistical analyses were performed using SPSS software (version 19.0; IBM, Armonk, NY, USA).
Results The study group included 15 men and 65 women, with a mean age at the time of surgery of 72.1 6.2 years (range, 60-87 years) and a mean follow-up period of 31.4 11.6 months (range, 24-70 months). Preoperatively, no difference regarding sex, age, pVAS scores, shoulder stiffness, or functional scores was found between the 2 groups (Table I). The average pVAS score improved from 6.6 2.5 before surgery to 1.5 1.9 at the final follow-up; the functional scores also improved, from 35.2 16.5 to 77.8 15.5 for the ASES score and from 1.8 1.8 to 6.8 2.8 for the SST score (P < .05 for all). Compared with the native retroversion angle of 27.8 (range, 10 -45 ), the mean individualized angle of humeral retroversion (group I) was 26.8 (range, 10 -40 ), with the following distribution: 10 in 1 patient, 15 in 1 patient, 20 in 19 patients, 30 in 25 patients, and 40 in 6 patients (P ¼ .235). Patients in group I were further classified into those with retroversion of 20 or less (subgroup A, n ¼ 21; mean, 19.3 2.4 ) and those with retroversion greater than 20 (subgroup B, n ¼ 31; mean, 31.9 4.0 ) for analysis. Clinical outcomes were better, overall, in group I than in group II at the final follow-up, as reported in Table II: forward flexion (scapular abduction), 141.9 (range, 110 160 ) vs. 128.9 (range, 90 -170 ) (P ¼ .029); external rotation, 52.3 (range, 40 -80 ) vs. 38.9 (range, 20 -80 ) (P ¼ .001); internal rotation, 10.3 (range, 8-15) vs. 12.1 (range, 7-15) (P ¼ .004); and pVAS score, 1.1 1.5 vs. 2.2
2.2 (P ¼ .022). Functional scores (ASES and SST) were also better in group I than in group II (P < .05). No differences in ROM, pVAS scores, and functional scores were found between the 2 subgroups in group I (Table III). Outcomes in subgroups A and B were compared with those in group II. ROM and pVAS scores were better in subgroup A (20 of retroversion) than in group II (fixed retroversion of 20 ; Table IV), whereas functional scores, ROM, and pVAS scores were better in subgroup B (>20 of retroversion) than in group II (Table V). No complications, such as infection, instability, or scapular notching, were observed postoperatively in any cases. The effect of subscapularis repair was compared between patients in group I who underwent subscapularis repair using the tunneling technique (n ¼ 40) and those in whom repair was impossible because of a massive tear (n ¼ 12). No differences in ROM, pVAS scores, and functional scores were found between these 2 groups (Tables VI and VII).
Discussion The principal finding of this study was that after lateralized RTSA, individualized humeral retroversion improved all outcomes at the final follow-up compared with implantation at a fixed angle of 20 of retroversion. Individualization of humeral retroversion using CT scans was reliable, with a mean individualized angle of 26.8 7.1 compared with the native angle of 27.8 9.5 . Individualized humeral retroversion provided superior outcomes to those of the fixed 20 angle, regardless of whether the individualized angle was greater than 20 or was 20 or less. However, subscapularis repair was not correlated with superior clinical outcomes. Clinical outcomes, especially ROM, depend on surgical and prosthetic factors,40 with nonanatomic implantation of the RTSA prosthesis contributing to postoperative loss of
Individualized humeral retroversion in RTSA
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Table II Clinical outcomes between individualized (group I) and fixed (group II) retroversion groups at final follow-up Variable
Group I (n ¼ 52)
Group II (n ¼ 28)
P value
Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
141.9 14.6
128.9 28.2
.029*
52.3 10.3 1.1 80.4 7.3
15.9 2.4 1.5 16.6 3.1
38.9 12.1 2.2 73.0 5.9
16.0 2.7 2.2 15.3 1.8
.001* .004* .022* .025* .017*
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation. * Statistically significant (P < .05).
Table III Clinical outcomes between subgroup with 20 of retroversion or less (subgroup A) and subgroup with greater than 20 of retroversion (subgroup B) in group I (individualized retroversion group) at final follow-up Variable
Subgroup A (n ¼ 21)
Subgroup B (n ¼ 31)
P value
Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
142.4 14.5
141.6 14.9
.576
.130 .116 .885 .226 .101
49.0 9.9 1.1 78.2 6.4
17.0 2.5 1.2 17.7 3.0
54.5 10.7 1.0 81.9 7.8
15.0 2.3 1.7 16.0 3.1
Table IV Clinical outcomes between subgroup with 20 of retroversion or less (subgroup A) and group with fixed retroversion of 20 (group II) at final follow-up Variable
Subgroup A (n ¼ 21)
Group II (n ¼ 28)
P value
Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
142.4 14.5
128.9 28.2
.035*
.038* .016* .035* .251 .516
49.0 9.9 1.1 78.2 6.4
17.0 2.5 1.2 17.7 3.0
38.9 12.1 2.2 73.0 5.9
16.0 2.7 2.2 15.3 1.8
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation. * Statistically significant (P < .05).
Table V Clinical outcomes between subgroup with greater than 20 of retroversion (subgroup B) and group with fixed retroversion of 20 (group II) at final follow-up P value
Variable
Subgroup B (n ¼ 31)
Group II (n ¼ 28)
Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
141.6 14.9
128.9 28.2
54.5 10.7 1.0 81.9 7.8
15.0 2.3 1.7 16.0 3.1
38.9 12.1 2.2 73.0 5.9
16.0 2.7 2.2 15.3 1.8
.040*
<.001* .034* .032* .019* .005*
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation.
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation. * Statistically significant (P < .05).
external and internal rotation, as well as functional limitations.43 Humeral version, defined as the position of the humeral head component relative to the transepicondylar axis of the elbow joint, directly influenced rotation and, thus, clinical outcomes.10,35,37 As the RTSA prosthesis is not designed to re-create normal glenohumeral joint anatomy or mechanics, the optimal angle of retroversion for implantation is not yet known. Biomechanical evaluation of the angle of retroversion for RTSA prostheses has only been performed in cadaveric studies. Gulotta et al17 concluded that 0 to 20 of humeral retroversion allows maximum internal rotation, with no effect on muscle force with increasing retroversion angle, whereas Stephenson et al37 suggested that placing the humeral component at
between 20 and 40 of retroversion provides greater external rotation before impingement. Berhouet et al2 indicated that increasing the angle of retroversion decreased internal rotation (while significantly increasing external rotation), with the optimal balance in rotations obtained with the average native angle of 17.5 . In a clinical study, Rhee et al35 did not identify a difference in ROM for retroversion angles of 20 and 0 , with internal rotation being facilitated by 0 of retroversion. Moreover, Kontaxis et al24 reported a preferred angle of 0 of version to prevent impingement with activities of daily living. De Boer et al6 did not report differences between 0 and 20 of retroversion regarding external and internal rotation, as well as strength or functional outcome scores. However,
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J.H. Oh et al. Table VI
Preoperative demographic data according to reparability of subscapularis in group I
Variable
Reparable and repaired (n ¼ 40)
Irreparable (n ¼ 12)
P value
Age, yr Sex: M/F Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points P/Ex of subscapularis muscle (positive findings) Bear-hug test Belly-press test IR lag sign Liftoff test
70.8 8/32 99.3 38.0 12.5 6.8 35.1 1.4
73.8 2/10 91.7 35.0 12.0 6.8 42.0 2.0
.191 .797 .648 .670 .678 .963 .215 .300
7.1 50.5 21.9 3.8 2.2 16.2 1.5
37 of 40 24 of 40 2 of 40 0 of 40
5.7 49.1 18.9 3.9 2.0 17.7 2.3
12 of 12 12 of 12 5 of 12 5 of 12
.999 .010 .005 .002
M, male; F, female; ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test; P/Ex, physical examination. Data are presented as mean standard deviation or number of patients.
Table VII
Clinical outcomes according to reparability of subscapularis in group I at final follow-up Reparable and repaired (n ¼ 40)
Variable Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
142.0 52.5 10.2 1.0 81.1 7.3
15.4 15.3 2.5 1.5 17.3 3.2
Irreparable (n ¼ 12) 141.7 51.7 10.8 1.2 78.2 7.2
11.9 18.5 2.2 1.6 14.6 3.1
P value .945 .875 .515 .779 .601 .918
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation.
only the specific angles such as 0 , 20 , or 40 of retroversion have been compared without individualizing humeral retroversion in those previous studies. Our study is unique in this aspect, with comparison of individualized humeral retroversion vs. fixed retroversion of 20 , providing evidence of the superiority of individualized retroversion in improving pain, ROM, and functional scores postoperatively. This result may be explained as follows: Individualizing retroversion may restore the native anatomy, to which the patient has adapted over decades. In addition to humeral component positioning, soft-tissue tension and muscular balance can directly influence clinical outcomes. As soft tissues have adapted to the native retroversion angle, the angle of retroversion and the neck-shaft angle of the humeral component should be cautiously considered during shoulder arthroplasty. Because of soft-tissue adaptations, it is not surprising that clinical outcomes were better for individualized rather than fixed humeral retroversion. The integrity of the subscapularis may also be a contributing factor for postoperative instability.8,18 The
advantages of subscapularis repair, such as joint stability or anatomic preservation of the rotator cuff, have been defined from cadaveric studies.20,32 However, from a clinical perspective, Friedman et al12 reported that a lateralized RTSA humeral prosthesis was associated with a low risk of instability, regardless of subscapularis repair. Likewise, Vourazeris et al41 reported similar clinical outcome scores, ROM, and strength, as well as a similar rate of complications, including dislocation, over a follow-up period of 3 years, for primary RTSA with or without subscapularis repair. These findings are in agreement with ours. The lateralization of the COR lengthens the moment arms of the internal and external rotators compared with the conventional RTSA design, which would restore the transverseplane force couple, regardless of the status of the subscapularis. Moreover, the lateralized COR increases deltoid wrapping and provides more anatomic tensioning of the rotator cuff, both of which contribute to stability. Therefore, it would be expected that the rate of instability, if any, would not be affected by repair or non-repair of the subscapularis.
Individualized humeral retroversion in RTSA The limitations of this study need to be acknowledged in the interpretation of findings for clinical practice. First, this study was not randomized; it was a chronologic study with separate cohorts obtained with a change in practice with a relatively short-term follow-up period of just over 2 years, on average. Because no similar studies related to the clinical outcomes after individualized humeral retroversion or subscapularis repair using a lateralized RTSA implant exist, it was not possible to perform power analysis for sample size calculation. Moreover, the power of subgroup analysis of subscapularis repair would be inadequate given the inherent nature of a retrospective study. Therefore, a longterm prospective, comparative clinical trial would be needed to confirm our data. Second, as we divided patients into 2 groups depending on whether individualized humeral retroversion had been used at the time of surgery, timedependent bias was present. However, all procedures were performed by 1 senior surgeon, who was sufficiently experienced and standardized all steps during the arthroplasty procedure. There were also no significant differences in the indications for surgery, surgical techniques, and implants between the 2 groups despite the time-dependent bias. As our experience with the RTSA prosthesis might have an influence on clinical outcomes, however, prospective studies on this topic will be needed in the future. Third, intraobserver or interobserver reliability between the 2 retroversion angles measured by the radiologist and surgeon was not estimated in this study, as there were small differences of less than 5 between the 2 measurements in all cases. Even though individualization of humeral retroversion was based on the native angle measured by CT scans, the measured angle was limited to 5 increments between the range of 10 to 40 rather than the exact angle. Furthermore, application of the exact angle was limited, and the rotational guide and forearm were used for setting humeral retroversion. However, we believed that 5 increments would be acceptable as subgroup A (19.3 2.4 ) and subgroup B (31.9 4.0 ) had better ROM and pVAS scores than group II (fixed retroversion of 20 ). Fourth, we tried to compare the status of the subscapularis on physical examination in 2 subgroups regarding the subscapularis repair; however, it was difficult to achieve statistical power because of the small number of patients in each group. A comparison of the physical examination findings as well as ROM might be helpful to evaluate the effect of subscapularis repair, and a long-term prospective study is needed to determine the effect of subscapularis repair. Fifth, regarding ROM, internal rotation was measured using semiquantitative spine levels and not a quantitative angular parameter in this study, which could be influenced by the elbow flexion angle. However, none of the patients were affected by elbow problems such as osteoarthritis and contracture; therefore, we thought that internal rotation measurements were minimally affected by elbow problems. Furthermore, internal rotation at the back has been a generally accepted measurement method in many
7 publications.6,12,35 Finally, humeral retroversion relative to the forearm axis was determined intraoperatively using the alignment guide supplied with the prosthesis. This method to confirm the native humeral version angle in the operative field was a subjective assessment, which might not yield the exact retroversion angle. Surgeons have usually used specific alignment guides on the handle of the humeral component to assess version, with the forearm used as a reference in some studies.1,6 We used the alignment guide relative to the forearm axis for exact humeral retroversion, but a postoperative CT scan would have been necessary to confirm the inserted humeral retroversion. As we could not perform CT measurements postoperatively, we could not detect repetitive errors or confirm that the position of humeral retroversion was maintained as planned after surgery. On the basis of emerging evidence of the importance of humeral retroversion regarding clinical outcomes after shoulder arthroplasty, there has been a recent increase in patient-specific instrumentation for setting an exact angle,13,21,39 with continued development and evaluation of such instruments being warranted. As a correlation between superior clinical outcomes and individualized humeral retroversion was found in this study, further large-scale, long-term prospective studies will be needed to determine the effect of individualized humeral retroversion and subscapularis repair in patients undergoing RTSA with a lateralized prosthesis.
Conclusion Individualized humeral retroversion may provide superior clinical outcomes to those of implantation of the humeral component at a fixed angle of 20 of retroversion. Repair of the subscapularis may not be essential for superior clinical outcomes in patients treated using a lateralized RTSA prosthesis.
Disclaimer 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.
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Individualized humeral retroversion in RTSA 39. Verborgt O, Hachem AI, Eid K, Vuylsteke K, Ferrand M, Hardy P. Accuracy of patient-specific guided implantation of the glenoid component in reversed shoulder arthroplasty. Orthop Traumatol Surg Res 2018;104:767-72. https://doi.org/10.1016/j. otsr.2018.01.010 40. Virani NA, Cabezas A, Gutierrez S, Santoni BG, Otto R, Frankle M. Reverse shoulder arthroplasty components and surgical techniques that restore glenohumeral motion. J Shoulder Elbow Surg 2013;22:179-87. https://doi.org/10.1016/j.jse.2012.02.004 41. Vourazeris JD, Wright TW, Struk AM, King JJ, Farmer KW. Primary reverse total shoulder arthroplasty outcomes in patients with
9 subscapularis repair versus tenotomy. J Shoulder Elbow Surg 2017;26: 450-7. https://doi.org/10.1016/j.jse.2016.09.017 42. Wall B, Nove-Josserand L, O’Connor DP, Edwards TB, Walch G. Reverse total shoulder arthroplasty: a review of results according to etiology. J Bone Joint Surg Am 2007;89:1476-85. https://doi.org/10. 2106/JBJS.F.00666 43. 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. https://doi.org/10.2106/JBJS.D. 02342
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Do individualized humeral retroversion and subscapularis repair affect the clinical outcomes of reverse total shoulder arthroplasty? Joo Han Oh, MD, PhDa, Nikhil Sharma, MDb, Sung Min Rhee, MD, PhDc, Joo Hyun Park, MDd,* a
Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea b Holy Cross Hospital, Mumbai, India c Shoulder & Elbow Clinic, Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, Seoul, Republic of Korea d Bundang Jesaeng General Hospital, Daejin Medical Center, Seongnam, Republic of Korea Background: This study aimed to evaluate the effects of an individualized angle of humeral retroversion and subscapularis repair on clinical outcomes after reverse total shoulder arthroplasty (RTSA) using a lateralized prosthesis. Methods: A retrospective analysis of 80 patients who underwent RTSA and had a minimum of 2 years’ follow-up was performed. Individualization was based on the native retroversion angle, quantified from computed tomography images. Clinical outcomes (forward flexion, external rotation at the side, internal rotation at the back, functional scores, and pain) were compared between patients with individualized retroversion (group I, n ¼ 52) and patients with a fixed retroversion angle of 20 (group II, n ¼ 28). Group I was further subdivided into patients with a retroversion angle of 20 or less (subgroup A, n ¼ 21) and patients with a retroversion angle greater than 20 (subgroup B, n ¼ 31). We also compared outcomes in group I between patients with (n ¼ 40) and without (n ¼ 12) subscapularis repair. Results: Ranges of motion including external rotation and internal rotation, functional scores, and pain relief were significantly better in group I than in group II (P < .05 for all). No differences in clinical outcomes were found between subgroups A and B, although outcomes for both of these subgroups were better than those for group II (P < .05 for all). Subscapularis repair was not correlated with superior clinical outcomes. Conclusions: Individualized humeral retroversion may provide superior clinical outcomes to those of implantation of the humeral component at a fixed angle of 20 of retroversion. Repair of the subscapularis may not be essential for superior clinical outcomes in patients treated using a lateralized RTSA prosthesis.
The Seoul National University Bundang Hospital Institutional Review Board approved an exemption for this study because of its retrospective design (no. B-1808/487-107). *Reprint requests: Joo Hyun Park, MD, Department of Orthopaedic Surgery, Bundang Jesaeng General Hospital, Daejin Medical Center, 20,
Seohyeon-ro 180beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 13590, Republic of Korea. E-mail address: [email protected] (J.H. Park).
1058-2746/$ - see front matter Ó 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. https://doi.org/10.1016/j.jse.2019.08.016
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J.H. Oh et al. Level of evidence: Level III; Retrospective Cohort Design; Treatment Study Ó 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved. Keywords: Shoulder; cuff tear arthropathy; reverse total shoulder arthroplasty; humeral retroversion; range of motion; subscapularis repair; subscapularis repair
Reverse total shoulder arthroplasty (RTSA) has become a standard treatment for cuff tear arthropathy (CTA) in older individuals, with documented good midterm clinical and radiologic outcomes.9,14,23 In addition, excellent clinical outcomes of RTSA have been reported in patients younger than 65 years, with a 10-year survival rate of 88%.9 RTSA was developed in response to the early failure of total shoulder arthroplasty, largely due to glenoid loosening, among patients with severe rotator cuff deficiency.26,33 RTSA reliably and effectively restores forward flexion (to 130 in shoulders with pseudoparalysis due to irreparable rupture of the rotator cuff) and provides shoulder pain relief.15,34,36,42 However, the selection of the ideal configuration and placement of the components to optimize shoulder function outcomes remains an issue of debate. Several studies have documented drawbacks of medialization of the center of rotation (COR), including glenoid notching and loss of shoulder rotation,4,16,22,27,29,36 with placement of the implant with a more lateral COR recently being preferred by many surgeons; the resultant position of the COR with this lateral offset more closely approximates that of the normal glenohumeral joint, decreasing scapular notching and improving rotation force.11 Range of motion (ROM) after RTSA can be influenced by 2 categories of factors: surgical factors that are considered modifiable (version of the humeral component, balancing of soft tissues, and so on) and prosthetic factors that are considered nonmodifiable (size of the implant, neck-shaft angle of the humeral component, and so on). Neer28 suggested that implants with a design that mimicked the normal anatomy would provide the best function and durability. In this regard, the importance of humeral retroversion and subscapularis repair for better clinical outcomes after RTSA is an issue of debate. In their biomechanical study, Stephenson et al37 concluded that placing the humeral component at between 20 and 40 of retroversion most closely restores the functional arc of motion of the shoulder without impingement whereas anteversion can significantly decrease the amount of external rotation achievable after RTSA. Gulotta et al17 reported that increased retroversion improved external rotation at the expense of decreased internal rotation but without affecting the scapular plane of elevation. In a clinical study, Kontaxis et al24 reported a preferred angle of 0 of version to prevent impingement with activities of daily living. Edwards et al8 reported a 2-fold increase in the relative rate of dislocation after RTSA when the subscapularis was not repaired. Dedy et al7 reported that
subscapularis integrity did not appear to have a measurable effect on the functional scores but was important for internal rotation ability after RTSA. However, Rhee et al35 concluded that ROM was not statistically significantly affected by retroversion of the humeral component between 0 and 20 , with no statistically significant effect of the status of the subscapularis (ruptured or repaired) on ROM. The issue of the difference between native and component-fixed humeral retroversion and subscapularis repair regarding the clinical outcomes of RTSA is unclear, and most previous studies were biomechanical cadaveric or computer simulation studies. There are limited data available to guide clinicians regarding the most appropriate approaches to optimize outcomes. Therefore, the purpose of our study was to investigate the effect of individualized humeral retroversion and subscapularis repair on clinical outcomes after lateralized RTSA. We assumed that clinical outcomes would be improved by considering native humeral version and repairing the subscapularis.
Materials and methods Patient selection The study group included patients who had undergone RTSA with a lateralized prosthesis (Biomet Comprehensive Reverse Shoulder System; Biomet, Warsaw, IN, USA) between January 2007 and January 2015; all procedures were performed by a single surgeon. The inclusion criteria were as follows: irreparable massive rotator cuff tear with pseudoparalysis, CTA, static superior migration of the humeral head, and failed rotator cuff repair. Patients with post-traumatic secondary osteoarthritis, assessed from patients’ medical records or anamnesis, as well as those with systemic inflammatory diseases, such as rheumatoid arthritis, and those undergoing revision for a failed shoulder arthroplasty or being treated with a prosthesis other than that for RTSA, were excluded. We retrospectively analyzed data from 80 patients who satisfied the inclusion and exclusion criteria and had a minimum follow-up period of 2 years after RTSA. For analysis, patients were classified into 2 groups based on the retroversion position of the humeral component relative to native humeral version, measured on computed tomography (CT) images: group I (n ¼ 52) had a range of retroversion from 10 to 40 in 5 increments, whereas group II (n ¼ 28) had fixed retroversion of 20 . A fixed retroversion position of the humeral components of 20 was used from January 2007 to January 2012, per the surgical protocol at our institution. After January 2012, we started individualizing the position of retroversion of the humeral component with respect to native version, estimated by CT.
Individualized humeral retroversion in RTSA
Preoperative and postoperative evaluation Each patient was followed up at 1, 3, and 6 months postoperatively and then annually. Pain was assessed at each visit using a visual analog scale for pain (pVAS), with anchors at 0 (no pain) and 10 (worst pain). Active ROM in forward flexion (scapular abduction) and external rotation (with the arm by the side) was measured by a handheld goniometer, with the patient in the supine position or the scapula’s position maintained by hand. Internal rotation was measured as the vertebral level reached by the tip of the thumb, with the patient in a sitting position, scored per a standard technique, with a score of 1 to 12 for reaching the first to 12th thoracic vertebra, a score of 13 to 17 for reaching the first to fifth lumbar vertebra, and a score of 18 for reaching the sacrum.5,30 ROM at the 2-year time point (or close to it) was compared between the 2 groups. Functional scores, including the American Shoulder and Elbow Surgeons (ASES) score and Simple Shoulder Test (SST) score, were obtained before surgery and at every annual follow-up visit.
Radiologic workup Preoperative radiographs were obtained in the true anteroposterior, axillary, and scapular Y views and in 30 of external rotation. Magnetic resonance imaging was performed to determine the status of the rotator cuff, with fatty degeneration and CTA confirmed and classified based on the Hamada classification.19 CT with 3-dimensional image reconstruction was performed to estimate the individual native version of the glenoid and humerus, on both the affected and contralateral sides, including assessment of glenoid wear or bone stock of the proximal humerus. Humeral retroversion on the affected side was calculated in relation to the contralateral side, using the standard method described by Boileau et al.3 CT scans from the elbow through the shoulder were performed on both sides in all patients. Elbow and humeral scans were separately performed to reduce radiation hazards. The central axis of the humeral head was defined on axial 2-dimensional CT scans as the perpendicular axis of the boundaries of the articular surface of the humeral head determined using the limits of the subchondral bone in the largest circle of the humeral head. The elbow transepicondylar axis was defined as the line between the most medial extension and most lateral extension of the distal humerus. Humeral retroversion was determined as the angle between the central axis of the humeral head and the elbow transepicondylar axis. If the articular surface of the humeral head was deformed or collapsed, owing to severe arthritic changes, the midline of the bicipital groove and the posterior margin of the bicipital groove were used as landmarks to assist with the determination of humeral head retroversion.25,31,38 Humeral retroversion was measured using the bicipital groove as a landmark in 24 patients (30%). The radiologist and surgeon separately measured the humeral retroversion angle of both shoulders as described earlier, and the average value of the 2 measurements was used. Intraobserver or interobserver reliability was not estimated in this study. According to Oh et al,31 all of alternative methods showed excellent reliability (interobserver reliability > 0.890) compared with the standard method. Because it was difficult to apply the exact measured angle of humeral retroversion in the operative field at the time of stem insertion, the retroversion angle could be applied in 5 increments with consideration of
3 the measurement of the contralateral side. The postoperative status of the implant was evaluated for scapular notching and implant loosening using radiography through the final follow-up visit.
Operative technique All procedures were performed by a single senior orthopedic surgeon using a single implant (Biomet Comprehensive Reverse Shoulder System). The glenohumeral joint was exposed through a standard deltopectoral approach. If the subscapularis muscle needed to be taken down to approach the joint, subscapularis tenotomy was performed longitudinally at 1 cm medial to the bicipital groove. After dislocation of the humeral head, sequential manual reaming, using 1-mm increments, was performed according to the diameter of the humeral shaft. A rotational guide was attached to the broach to determine the retroversion of the humeral component to be implanted. The humeral neck was then cut using a cutting guide. An intraoperative decision regarding retroversion was made by the senior author (J.H.O.) with the help of surgical assistants (fellows) using a retroversion guide attached to the handle that was parallel to the forearm during reaming, broaching, and implantation. Subsequently, glenoid preparation was completed using the standard method, with a guide pin placed at the center of the glenoid with a 10 inferior tilt. Glenoid reaming was performed over the guide pin to make neutral version. The glenoid baseplate was fixed to the glenoid using a central screw with 3 to 4 peripheral screws. A standard glenosphere (diameter, 36 mm) with a 3.5-mm inferior offset was implanted over the baseplate. If the preoperative version exceeded 15 , implantation of autogenous bone taken from the humeral head was performed with baseplate fixation. After reduction of humeral stem trial, we assessed implant stability and muscle tension. Massive irrigation was performed, and 3 drill holes were made on the lesser tuberosity of the humerus for subscapularis repair, using a bone-tunneling suture technique. After the humeral component was inserted, final reduction was performed with assessment of joint stability. In cases of a reparable subscapularis, the tendon was reattached to the lesser tuberosity using No. 2 Ethibond sutures (Ethicon, Somerville, NJ, USA). The long head of the biceps tendon was repaired, along with the subscapularis, as a soft-tissue tenodesis. A suction drain was inserted, with layerby-layer suturing. The shoulder joint was immobilized in a sling with a pillow for 4 weeks. Passive forward flexion exercise using a continuous passive motion machine was permitted in all patients during brace wearing (3-5 times a day, 20 minutes per time, with a step-by-step increment in angles) if implants were stably implanted. Activeassisted ROM exercise was performed for 6 to 8 weeks after weaning of sling immobilization. Usually, muscle-strengthening exercises were started at 3 months postoperatively, and all sports activities were allowed at 6 months after surgery.
Statistical analysis Continuous data are presented as mean (standard deviation) and categorical data, as number (percentage). Statistically significant differences in metrics were evaluated using independent and paired t tests for data with normal distributions. Nonparametric analysis (Mann-Whitney U and Wilcoxon signed rank tests) was used to
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J.H. Oh et al. Table I
Preoperative demographic data for individualized (group I) and fixed (group II) retroversion groups
Variable
Group I (n ¼ 52)
Group II (n ¼ 28)
P value
Age, yr Sex: M/F Indication for surgery: CTA/failed rotator cuff repair Preoperative shoulder stiffness: Y/N Follow-up period, mo Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
71.5 10/42 48/4 48/4 29.0 97.5 37.3 12.4 6.8 36.7 1.5
73.1 5/23 26/2 24/4 35.9 96.4 27.5 11.1 6.3 33.4 2.1
.253 .881 .999 .441 .032 .924 .055 .137 .395 .257 .159
6.9
8.3 49.8 21.1 3.8 2.1 16.6 1.7
4.8
15.2 43.2 22.3 3.8 3.1 18.2 1.9
M, male; F, female; CTA, cuff tear arthropathy; Y, yes; N, no; ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation or number of patients.
compare data found not to be normally distributed. The c2 test or Fisher exact test was used to analyze categorical variables such as patients’ sex and surgical indication; P < .05 was defined as statistically significant. All statistical analyses were performed using SPSS software (version 19.0; IBM, Armonk, NY, USA).
Results The study group included 15 men and 65 women, with a mean age at the time of surgery of 72.1 6.2 years (range, 60-87 years) and a mean follow-up period of 31.4 11.6 months (range, 24-70 months). Preoperatively, no difference regarding sex, age, pVAS scores, shoulder stiffness, or functional scores was found between the 2 groups (Table I). The average pVAS score improved from 6.6 2.5 before surgery to 1.5 1.9 at the final follow-up; the functional scores also improved, from 35.2 16.5 to 77.8 15.5 for the ASES score and from 1.8 1.8 to 6.8 2.8 for the SST score (P < .05 for all). Compared with the native retroversion angle of 27.8 (range, 10 -45 ), the mean individualized angle of humeral retroversion (group I) was 26.8 (range, 10 -40 ), with the following distribution: 10 in 1 patient, 15 in 1 patient, 20 in 19 patients, 30 in 25 patients, and 40 in 6 patients (P ¼ .235). Patients in group I were further classified into those with retroversion of 20 or less (subgroup A, n ¼ 21; mean, 19.3 2.4 ) and those with retroversion greater than 20 (subgroup B, n ¼ 31; mean, 31.9 4.0 ) for analysis. Clinical outcomes were better, overall, in group I than in group II at the final follow-up, as reported in Table II: forward flexion (scapular abduction), 141.9 (range, 110 160 ) vs. 128.9 (range, 90 -170 ) (P ¼ .029); external rotation, 52.3 (range, 40 -80 ) vs. 38.9 (range, 20 -80 ) (P ¼ .001); internal rotation, 10.3 (range, 8-15) vs. 12.1 (range, 7-15) (P ¼ .004); and pVAS score, 1.1 1.5 vs. 2.2
2.2 (P ¼ .022). Functional scores (ASES and SST) were also better in group I than in group II (P < .05). No differences in ROM, pVAS scores, and functional scores were found between the 2 subgroups in group I (Table III). Outcomes in subgroups A and B were compared with those in group II. ROM and pVAS scores were better in subgroup A (20 of retroversion) than in group II (fixed retroversion of 20 ; Table IV), whereas functional scores, ROM, and pVAS scores were better in subgroup B (>20 of retroversion) than in group II (Table V). No complications, such as infection, instability, or scapular notching, were observed postoperatively in any cases. The effect of subscapularis repair was compared between patients in group I who underwent subscapularis repair using the tunneling technique (n ¼ 40) and those in whom repair was impossible because of a massive tear (n ¼ 12). No differences in ROM, pVAS scores, and functional scores were found between these 2 groups (Tables VI and VII).
Discussion The principal finding of this study was that after lateralized RTSA, individualized humeral retroversion improved all outcomes at the final follow-up compared with implantation at a fixed angle of 20 of retroversion. Individualization of humeral retroversion using CT scans was reliable, with a mean individualized angle of 26.8 7.1 compared with the native angle of 27.8 9.5 . Individualized humeral retroversion provided superior outcomes to those of the fixed 20 angle, regardless of whether the individualized angle was greater than 20 or was 20 or less. However, subscapularis repair was not correlated with superior clinical outcomes. Clinical outcomes, especially ROM, depend on surgical and prosthetic factors,40 with nonanatomic implantation of the RTSA prosthesis contributing to postoperative loss of
Individualized humeral retroversion in RTSA
5
Table II Clinical outcomes between individualized (group I) and fixed (group II) retroversion groups at final follow-up Variable
Group I (n ¼ 52)
Group II (n ¼ 28)
P value
Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
141.9 14.6
128.9 28.2
.029*
52.3 10.3 1.1 80.4 7.3
15.9 2.4 1.5 16.6 3.1
38.9 12.1 2.2 73.0 5.9
16.0 2.7 2.2 15.3 1.8
.001* .004* .022* .025* .017*
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation. * Statistically significant (P < .05).
Table III Clinical outcomes between subgroup with 20 of retroversion or less (subgroup A) and subgroup with greater than 20 of retroversion (subgroup B) in group I (individualized retroversion group) at final follow-up Variable
Subgroup A (n ¼ 21)
Subgroup B (n ¼ 31)
P value
Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
142.4 14.5
141.6 14.9
.576
.130 .116 .885 .226 .101
49.0 9.9 1.1 78.2 6.4
17.0 2.5 1.2 17.7 3.0
54.5 10.7 1.0 81.9 7.8
15.0 2.3 1.7 16.0 3.1
Table IV Clinical outcomes between subgroup with 20 of retroversion or less (subgroup A) and group with fixed retroversion of 20 (group II) at final follow-up Variable
Subgroup A (n ¼ 21)
Group II (n ¼ 28)
P value
Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
142.4 14.5
128.9 28.2
.035*
.038* .016* .035* .251 .516
49.0 9.9 1.1 78.2 6.4
17.0 2.5 1.2 17.7 3.0
38.9 12.1 2.2 73.0 5.9
16.0 2.7 2.2 15.3 1.8
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation. * Statistically significant (P < .05).
Table V Clinical outcomes between subgroup with greater than 20 of retroversion (subgroup B) and group with fixed retroversion of 20 (group II) at final follow-up P value
Variable
Subgroup B (n ¼ 31)
Group II (n ¼ 28)
Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
141.6 14.9
128.9 28.2
54.5 10.7 1.0 81.9 7.8
15.0 2.3 1.7 16.0 3.1
38.9 12.1 2.2 73.0 5.9
16.0 2.7 2.2 15.3 1.8
.040*
<.001* .034* .032* .019* .005*
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation.
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation. * Statistically significant (P < .05).
external and internal rotation, as well as functional limitations.43 Humeral version, defined as the position of the humeral head component relative to the transepicondylar axis of the elbow joint, directly influenced rotation and, thus, clinical outcomes.10,35,37 As the RTSA prosthesis is not designed to re-create normal glenohumeral joint anatomy or mechanics, the optimal angle of retroversion for implantation is not yet known. Biomechanical evaluation of the angle of retroversion for RTSA prostheses has only been performed in cadaveric studies. Gulotta et al17 concluded that 0 to 20 of humeral retroversion allows maximum internal rotation, with no effect on muscle force with increasing retroversion angle, whereas Stephenson et al37 suggested that placing the humeral component at
between 20 and 40 of retroversion provides greater external rotation before impingement. Berhouet et al2 indicated that increasing the angle of retroversion decreased internal rotation (while significantly increasing external rotation), with the optimal balance in rotations obtained with the average native angle of 17.5 . In a clinical study, Rhee et al35 did not identify a difference in ROM for retroversion angles of 20 and 0 , with internal rotation being facilitated by 0 of retroversion. Moreover, Kontaxis et al24 reported a preferred angle of 0 of version to prevent impingement with activities of daily living. De Boer et al6 did not report differences between 0 and 20 of retroversion regarding external and internal rotation, as well as strength or functional outcome scores. However,
6
J.H. Oh et al. Table VI
Preoperative demographic data according to reparability of subscapularis in group I
Variable
Reparable and repaired (n ¼ 40)
Irreparable (n ¼ 12)
P value
Age, yr Sex: M/F Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points P/Ex of subscapularis muscle (positive findings) Bear-hug test Belly-press test IR lag sign Liftoff test
70.8 8/32 99.3 38.0 12.5 6.8 35.1 1.4
73.8 2/10 91.7 35.0 12.0 6.8 42.0 2.0
.191 .797 .648 .670 .678 .963 .215 .300
7.1 50.5 21.9 3.8 2.2 16.2 1.5
37 of 40 24 of 40 2 of 40 0 of 40
5.7 49.1 18.9 3.9 2.0 17.7 2.3
12 of 12 12 of 12 5 of 12 5 of 12
.999 .010 .005 .002
M, male; F, female; ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test; P/Ex, physical examination. Data are presented as mean standard deviation or number of patients.
Table VII
Clinical outcomes according to reparability of subscapularis in group I at final follow-up Reparable and repaired (n ¼ 40)
Variable Forward flexion (scapular abduction), ER at side, IR at back, level pVAS score, points ASES score, points SST score, points
142.0 52.5 10.2 1.0 81.1 7.3
15.4 15.3 2.5 1.5 17.3 3.2
Irreparable (n ¼ 12) 141.7 51.7 10.8 1.2 78.2 7.2
11.9 18.5 2.2 1.6 14.6 3.1
P value .945 .875 .515 .779 .601 .918
ER, external rotation; IR, internal rotation (scored as 1 to 12 for first to twelfth thoracic vertebra, 13 to 17 for first to fifth lumbar vertebra, and 18 for sacrum); pVAS, visual analog scale for pain; ASES, American Shoulder and Elbow Surgeons; SST, Simple Shoulder Test. Data are presented as mean standard deviation.
only the specific angles such as 0 , 20 , or 40 of retroversion have been compared without individualizing humeral retroversion in those previous studies. Our study is unique in this aspect, with comparison of individualized humeral retroversion vs. fixed retroversion of 20 , providing evidence of the superiority of individualized retroversion in improving pain, ROM, and functional scores postoperatively. This result may be explained as follows: Individualizing retroversion may restore the native anatomy, to which the patient has adapted over decades. In addition to humeral component positioning, soft-tissue tension and muscular balance can directly influence clinical outcomes. As soft tissues have adapted to the native retroversion angle, the angle of retroversion and the neck-shaft angle of the humeral component should be cautiously considered during shoulder arthroplasty. Because of soft-tissue adaptations, it is not surprising that clinical outcomes were better for individualized rather than fixed humeral retroversion. The integrity of the subscapularis may also be a contributing factor for postoperative instability.8,18 The
advantages of subscapularis repair, such as joint stability or anatomic preservation of the rotator cuff, have been defined from cadaveric studies.20,32 However, from a clinical perspective, Friedman et al12 reported that a lateralized RTSA humeral prosthesis was associated with a low risk of instability, regardless of subscapularis repair. Likewise, Vourazeris et al41 reported similar clinical outcome scores, ROM, and strength, as well as a similar rate of complications, including dislocation, over a follow-up period of 3 years, for primary RTSA with or without subscapularis repair. These findings are in agreement with ours. The lateralization of the COR lengthens the moment arms of the internal and external rotators compared with the conventional RTSA design, which would restore the transverseplane force couple, regardless of the status of the subscapularis. Moreover, the lateralized COR increases deltoid wrapping and provides more anatomic tensioning of the rotator cuff, both of which contribute to stability. Therefore, it would be expected that the rate of instability, if any, would not be affected by repair or non-repair of the subscapularis.
Individualized humeral retroversion in RTSA The limitations of this study need to be acknowledged in the interpretation of findings for clinical practice. First, this study was not randomized; it was a chronologic study with separate cohorts obtained with a change in practice with a relatively short-term follow-up period of just over 2 years, on average. Because no similar studies related to the clinical outcomes after individualized humeral retroversion or subscapularis repair using a lateralized RTSA implant exist, it was not possible to perform power analysis for sample size calculation. Moreover, the power of subgroup analysis of subscapularis repair would be inadequate given the inherent nature of a retrospective study. Therefore, a longterm prospective, comparative clinical trial would be needed to confirm our data. Second, as we divided patients into 2 groups depending on whether individualized humeral retroversion had been used at the time of surgery, timedependent bias was present. However, all procedures were performed by 1 senior surgeon, who was sufficiently experienced and standardized all steps during the arthroplasty procedure. There were also no significant differences in the indications for surgery, surgical techniques, and implants between the 2 groups despite the time-dependent bias. As our experience with the RTSA prosthesis might have an influence on clinical outcomes, however, prospective studies on this topic will be needed in the future. Third, intraobserver or interobserver reliability between the 2 retroversion angles measured by the radiologist and surgeon was not estimated in this study, as there were small differences of less than 5 between the 2 measurements in all cases. Even though individualization of humeral retroversion was based on the native angle measured by CT scans, the measured angle was limited to 5 increments between the range of 10 to 40 rather than the exact angle. Furthermore, application of the exact angle was limited, and the rotational guide and forearm were used for setting humeral retroversion. However, we believed that 5 increments would be acceptable as subgroup A (19.3 2.4 ) and subgroup B (31.9 4.0 ) had better ROM and pVAS scores than group II (fixed retroversion of 20 ). Fourth, we tried to compare the status of the subscapularis on physical examination in 2 subgroups regarding the subscapularis repair; however, it was difficult to achieve statistical power because of the small number of patients in each group. A comparison of the physical examination findings as well as ROM might be helpful to evaluate the effect of subscapularis repair, and a long-term prospective study is needed to determine the effect of subscapularis repair. Fifth, regarding ROM, internal rotation was measured using semiquantitative spine levels and not a quantitative angular parameter in this study, which could be influenced by the elbow flexion angle. However, none of the patients were affected by elbow problems such as osteoarthritis and contracture; therefore, we thought that internal rotation measurements were minimally affected by elbow problems. Furthermore, internal rotation at the back has been a generally accepted measurement method in many
7 publications.6,12,35 Finally, humeral retroversion relative to the forearm axis was determined intraoperatively using the alignment guide supplied with the prosthesis. This method to confirm the native humeral version angle in the operative field was a subjective assessment, which might not yield the exact retroversion angle. Surgeons have usually used specific alignment guides on the handle of the humeral component to assess version, with the forearm used as a reference in some studies.1,6 We used the alignment guide relative to the forearm axis for exact humeral retroversion, but a postoperative CT scan would have been necessary to confirm the inserted humeral retroversion. As we could not perform CT measurements postoperatively, we could not detect repetitive errors or confirm that the position of humeral retroversion was maintained as planned after surgery. On the basis of emerging evidence of the importance of humeral retroversion regarding clinical outcomes after shoulder arthroplasty, there has been a recent increase in patient-specific instrumentation for setting an exact angle,13,21,39 with continued development and evaluation of such instruments being warranted. As a correlation between superior clinical outcomes and individualized humeral retroversion was found in this study, further large-scale, long-term prospective studies will be needed to determine the effect of individualized humeral retroversion and subscapularis repair in patients undergoing RTSA with a lateralized prosthesis.
Conclusion Individualized humeral retroversion may provide superior clinical outcomes to those of implantation of the humeral component at a fixed angle of 20 of retroversion. Repair of the subscapularis may not be essential for superior clinical outcomes in patients treated using a lateralized RTSA prosthesis.
Disclaimer 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.
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