Reverse total shoulder arthroplasty

Do the humeral radiographic changes at 5-year follow-up affect the clinical outcomes of press-fit humeral stems in primary reverse shoulder arthroplasties?

INTRODUCTION

The purposes of this study were to analyze and compare the functional outcomes and radiological changes around the press-fit humeral components in two contemporary medialized reverse total shoulder arthroplasty (RTSA) systems at a minimum of 5-year follow-up.

MATERIALS AND METHODS

Between December 2003 and December 2015, 249 consecutive RTSAs were performed at our hospital. Of these, 68 primary uncemented RTSA met our inclusion criteria. The Constant-Murley score (CMS), the modified Constant score, a visual analog scale (VAS) and active shoulder range of motion (ROM) were measured pre- and postoperatively. Radiological assessment was performed by plain radiographs at a minimum of 5 years postoperatively.

RESULTS

At a mean follow-up of 80.2 months, there was no significant difference (p = .59) between the postoperative functional scores and range of motion of the two groups (Delta Xtend and Lima SMR). Radiological data of stress-shielding were observed in 38 patients (55.9%) being slightly more frequent in the Lima SMR group (21 patients) than in the Delta Xtend group (17 patients) (p = .62).

CONCLUSIONS

Our study shows that the good functional results are similar between the two uncemented RTSA systems used and that they do not depend on the presence of radiological changes (stress-shielding) in the humeral stem at a minimum 5-year follow-up.

Six-Item Modified Frailty Index independently predicts complications following total shoulder arthroplasty

Background

In the realm of orthopedic surgery, frailty has been associated with higher rates of complications following total hip and total knee arthroplasties. Among various measures of frailty, the Six-Item Modified Frailty Index (MF-6) has recently gained popularity as a predictor for postoperative complications. The purpose of this study was to investigate MF-6 as a predictor for early postoperative complications in the elderly patient population following total shoulder arthroplasty (TSA).

Methods

The authors queried the American College of Surgeons National Surgical Quality Improvement Program database for all patients who underwent TSA between 2015 and 2020. Patient demographics and comorbidities were compared between cohorts using bivariate logistic regression analysis. Multivariate logistic regression, adjusted for all significantly associated patient demographics and comorbidities, was used to identify associations between the MF-6 score and postoperative complications.

Results

Of total, 9228 patients were included in this study: 8764 (95.0%) had MF-6 <3, and 464 (5.0%) patients had MF-6 ≥3. Multivariate analysis found MF-6 ≥3 to be independently associated with higher rates of urinary tract infection (odds ratio [OR]: 2.79, 95% confidence interval [CI]: 1.49-5.23; P = .001), blood transfusion (OR: 1.53, 95% CI: 1.01-2.32; P = .045), readmission (OR: 1.58, 95% CI: 1.06-2.35; P = .024), and non-home discharge (OR: 2.60, 95% CI: 2.08-3.25; P < .001).

Conclusion

A high MF-6 score (≥3) in patients aged 65 and older is independently associated with higher rates of urinary tract infection, blood transfusion, readmission, and non-home discharge following TSA. The MF-6 score can be easily calculated preoperatively and may allow for better preoperative risk stratification.

Outcomes of Guided Personalized Surgery (GPS)-Navigated Reverse Polarity Total Shoulder Joint Replacement in a Low-Volume Hospital

Introduction Reverse polarity shoulder arthroplasty (RSA) is an evolving surgery, and its indications have expanded over time. Apart from cuff tear arthropathy (CTA), it is recommended for complex proximal humerus fractures in the elderly, inflammatory arthritis, primary osteoarthritis in the elderly, and revision for failed hemiarthroplasty. Glenoid base plate placement and fixation are important to prevent complications, especially glenoid base plate loosening, dislocation, and scapular notching, and to improve longevity. Guided personalized surgery (GPS)-navigated RSA was devised to optimize the glenoid base plate position and fixation. Methodology A retrospective study was carried out in a low-volume district general hospital in England. All the patients who underwent GPS-navigated RSA were included. Their preoperative glenoid version, bone stock, glenoid base plate, and glenoid screw lengths were analysed. Preoperative and post-surgery patient-reported outcomes were gathered using the Oxford Shoulder Score (OSS) at six months and annually thereafter. Results Fourteen patients have undergone GPS-navigated RSA in our institute since 2018. Ten patients were female. All of them had a retroverted glenoid with a mean value of 13.6 degrees. Ten out of 14 patients had an augmented glenoid base plate. This included six eight-degree posterior augmentations, three 10-degree superior augmentations, and one extended cage peg. The follow-up period was six months to five years, depending on the date of surgery, and none of the patients dropped out of follow-up. The OSS revealed statistically significant improvement from preoperative values to six months postoperative, an improvement of 21.64±7.175. It also showed progressive improvement over time during postoperative follow-up, and the three-year mean was 47. The commonest complication was fractures, which happened in four cases. There were no infections or dislocations. Discussion Guided personalized surgery-navigated RSA was performed on selected patients at our institution when they were not suitable for conventional RSA due to distorted glenoid anatomy. Glenoid base plate positioning and fixation are important to optimize the outcome of RSA. Guided personalized surgery navigation is helpful in achieving optimum glenoid base placement, especially when the normal glenoid anatomy is distorted. There were no dislocations, glenoid base plate loosening, or scapular notching in the study group. There were four reported fractures, which was comparable with the published literature.

The painful shoulder arthroplasty: appropriate work-up and review of interventional pain treatments

Shoulder arthroplasty is a successful surgical procedure for several conditions when patients become refractory to conservative management modalities. Unfortunately, some patients experience persistent chronic pain after shoulder arthroplasty. These individuals should undergo a comprehensive evaluation by an orthopedic surgeon to determine whether structural pathology is responsible for the pain and to decide whether reoperation is indicated. At times, a surgical solution does not exist. In these circumstances, a thorough and specific plan for the management of persistent chronic pain should be developed and instituted. In this article, we review common reasons for persistent pain after shoulder arthroplasty and outline the evaluation of the painful shoulder arthroplasty. We then provide a thorough review of interventional pain management strategies. Finally, we hypothesize developments in our field that might provide better outcomes in the future for patients suffering with chronic intractable pain after shoulder arthroplasty.

Rate of improvement in shoulder strength after anatomic and reverse total shoulder arthroplasty

Background

Methods

Results

Conclusion

Reverse shoulder arthroplasty with a cementless short metaphyseal humeral prosthesis without a stem: survivorship, early to mid-term clinical and radiological outcomes in a prospective study from an independent centre

INTRODUCTION

The use of reverse total shoulder arthroplasty has increased for the management of cuff-deficient glenohumeral joint arthritis and fractures. With bone preservation being a major target in reverse shoulder arthroplasty, metaphyseal humeral components without a stem were developed. The aim of this study is to present the survivorship, functional and radiological outcomes of a novel short metaphyseal prosthesis without a diaphyseal stem from an independent centre.

METHODS

Clinical function and radiological features of patients undergoing stemless reverse shoulder arthroplasty were prospectively recorded. Patients' demographics, indications for surgery, complications, functional and radiological assessment at the final follow-up as well as survivorship with the end point of revision for any reason were recorded.

RESULTS

Between 2009 and 2016, 36 patients received 37 reverse shoulder arthroplasties with the stemless Verso prosthesis. Mean age of the patients was 76.9 years. The most common indication for surgery was cuff tear arthropathy. Mean follow-up was 3 years (range 1-7 years). Oxford shoulder score improved from an average of 11 pre-operatively (range 2-19) to 44 post-operatively (range 29-48) (p < 0.0001). There was one case of a deep post-operative infection that needed washout, liner exchange with retention of the prosthesis. Radiographic analysis showed no lucencies, or stress shielding around the humeral or glenoid components. Constant score at the final follow-up was on average 63 (range 35-86). Activities of daily living with requirement for internal and external rotation score (ADLEIR) was on average 12 pre-operatively (range 0-27) and 31 post-operatively (range 18-36) (p < 0.0001). There was 100% survivorship of the prosthesis in this early to mid-term study.

CONCLUSION

This early to mid-term prospective study demonstrates excellent survivorship and radiological results of the Verso reverse shoulder replacement. It needs a simple reproducible technique, and the results have been replicated at an independent centre. This study underlines its survivorship in the early to mid-term and confirms lower incidence of complications such as instability, notching, loosening and the need for revision surgery. Most importantly, it conserves the humeral bone stock for revision arthroplasties in the future. Our results are similar to those of the currently published literature.

Reverse Shoulder Arthroplasty Using a Bone-preserving Glenoid Component: Clinical and Radiographic Outcomes

Introduction

Primary reverse shoulder arthroplasty has been reported to provide good outcomes. The majority of designs utilize a large portion of the glenoid. Some studies have reported worrisome rates of notching and stress fractures of the acromion or scapular spine. The purpose of this study was to determine the outcome and complications of a bone-preserving reverse prosthesis with limited ingrowth glenoid surface paired with an onlay humeral component.

Materials and methods

Between 2014 and 2015, 96 reverse arthroplasties were implanted using a bone-preserving reverse with a 135° onlay humeral bearing. Six patients died. The remaining 87 patients (90 shoulders) were followed for 2 years or until revision. Mean age was 69.3 years. The underlying diagnosis was cuff tear arthropathy (13), irreparable cuff tear (39), osteoarthritis (32), and other (6). Shoulders were followed for 2 years or until revision surgery.

Results

Reverse shoulder arthroplasty resulted in significant improvements in pain, motion, and function. At most recent follow-up, 74 shoulders had no or mild pain. Elevation was 131° ± 31° and external rotation 46° ± 21°. The mean American Shoulder and Elbow Surgeons (ASES) score was 76. There were 4 reoperations for deep infection (2), periprosthetic fracture, and glenoid loosening. None of the remaining arthroplasties were loose. There was one stress fracture of the acromion and one of the spine of the scapula. No radiographic notching or dislocation was observed.

Discussion

Primary reverse arthroplasty using a bone-preserving glenoid component and an anatomic onlay humeral bearing provides satisfactory clinical outcomes with a very low rate of failure and complications.

Reverse shoulder arthroplasty with a cementless short metaphyseal humeral implant without a stem: clinical and radiologic outcomes in prospective 2- to 7-year follow-up study

BACKGROUND

Reverse shoulder prostheses are increasingly used in recent years for treatment of glenohumeral arthropathy with deficient rotator cuff. Bone preservation is becoming a major goal in shoulder replacement surgery. Metaphyseal humeral components without a stem were developed to minimize bone resection and preserve bone. This study evaluated the clinical and radiologic outcomes at 2 to 7 years using a novel short metaphyseal reverse total shoulder arthroplasty (rTSA) prosthesis without a diaphyseal stem.

METHODS

Between 2005 and 2010, 102 consecutive patients underwent rTSA with this implant, and 98 (20 men, 78 women) were available for follow-up. Mean age was 74.4 years (range, 38-93 years). Indications were cuff tear arthropathy, 65; fracture sequelae, 12; rheumatoid arthritis, 13; failed rotator cuff repair, 3; cuff deficiency with loosening of anatomic prosthesis, 3; and acute trauma, 2; with 17 of these as revisions.

RESULTS

Patients' satisfaction (Subjective Shoulder Value) improved from 8 of 100 to 85 of 100. The Constant score improved from 14 to 59 (age- and sex-adjusted, 86; P < .0001). Range of motion improved from 47° to 129° in elevation, 10° to 51° in external rotation, and 21° to 65° in internal rotation. Radiographic analysis showed no lucencies, subsidence, or stress shielding around the humeral or glenoid components. Glenoid notching was found in 21 patients (18 grade 1-2; 3 grade 3).

CONCLUSIONS

The short metaphyseal rTSA design without a diaphyseal stem shows encouraging short- to midterm results, with excellent pain relief and shoulder function, restoration of good active range of motion, and high patient satisfaction scores. The design of this implant seems to result in improved rotational movements, low incidence of glenoid notching, and no implant loosening, subsidence, or stress shielding.

Reverse total shoulder arthroplasty with combined deltoid reconstruction in patients with anterior and/or middle deltoid tears

BACKGROUND AND HYPOTHESIS

Deltoid disruption has traditionally been an absolute contraindication to performing a reverse total shoulder arthroplasty (RTSA), and options available to patients have been limited. We present a series of patients with deltoid tears that underwent concomitant RTSA with deltoid reconstruction. We hypothesize that this combined procedure provides an acceptable, functional alternative for this complex patient population.

MATERIALS AND METHODS

We retrospectively identified all patients who were treated by a single surgeon with a concomitant RTSA and deltoid reconstruction from 2004 to 2012 with minimum 24-month follow-up. Six shoulders in 5 patients met these criteria. The mean age was 69 years (range, 61-79 years), and the mean follow-up period was 76.8 months (range, 24-133 months). We compared preoperative and postoperative range of motion and Penn Shoulder Scores, including subscores, using paired t tests.

RESULTS

Mean forward elevation and external rotation increased from 48° and 12°, respectively, to 120° and 22°, respectively. Penn scores increased from 45.2 to 77.8 postoperatively (P = .03). The Penn satisfaction subscore, in particular, improved from 1.1 (of 10) to 9.0 (P = .005). There was a low rate of recurrent deltoid failure (1 of 6 shoulders), and there were no infections or revisions.

DISCUSSION

Deltoid reconstruction at the same time as RTSA is a viable treatment option as a salvage procedure for patients with deltoid deficiency who otherwise need RTSA for treatment of massive rotator cuff deficiency. In this small series, simultaneous RTSA and deltoid reconstruction resulted in a functional shoulder with a high level of satisfaction and good motion.

LEVEL OF EVIDENCE

Level IV; Case Series; Treatment Study.

Combined effect of change in humeral neck-shaft angle and retroversion on shoulder range of motion in reverse total shoulder arthroplasty - A simulation study

BACKGROUND

We studied combined effect of change in humeral neck shaft angle and retroversion on shoulder ROM in reverse total shoulder arthroplasty using 3-dimensional simulations.

METHODS

Using a 3D model construct based on the CT scans of 3 males and a 3-dimensional analysis program, a humeral component of reverse total shoulder arthroplasty was implanted in 0°, 10°, 20°, 30°,40° retroversion and 135°, 145°, and 155° neck shaft angle. Total horizontal range of motion (sum of horizontal adduction and abduction) at 30° and 60° scaption, adduction in the scapular plane and IR behind the back were measured for various combinations of neck shaft angle and retroversion.

FINDINGS

Change in retroversion didn't show any effect on total horizontal range of motion. Total horizontal range of motion at both 30° and 60° scaption, showed maximum values at 135° neck shaft angle and minimum values at 155° neck shaft angle. With any combination of retroversion angles, adduction deficit was maximum at 155° neck shaft angle and no adduction deficit at 135° neck shaft angle. Every 10° decrease in neck shaft angle resulted in an average 10.4° increase in adduction. For every 10° increase in retroversion, there was loss of internal rotation behind the back up to at least one vertebral level.

INTERPRETATION

135° neck shaft angle resulted in maximum total horizontal range of motion both at 30° and 60° scaption regardless of retroversion angles. 135° neck shaft angle also reduced the chances of scapular impingement. Decrease in retroversion angle resulted in more amount of internal rotation behind the back.

Assessment of the optimal shoulder outcome score for reverse shoulder arthroplasty

BACKGROUND

With growing attention being paid to quality and cost-effectiveness in health care, outcome evaluations are becoming increasingly important. This determination can be especially difficult in reverse shoulder arthroplasty (RSA) given the complex pathology and extensive disabilities in this patient population. This study evaluated the use of 3 validated questionnaires used to assess outcomes for RSA.

METHODS

Using a database of patients treated with RSA, we assessed preoperative and postoperative Constant-Murley Scores, American Shoulder and Elbow Surgeons Scores, and Subjective Shoulder Values in 148 shoulders. The outcomes at each scoring period were described, and the scores were compared with one another as well as with active range of motion.

RESULTS

There were no significant differences in the mean improvement of any of the scores. Improvements in all of the outcome scales were correlated with each other and with improvement in forward elevation but not with external rotation. Multivariate regression analysis the 3 outcome measures was able to predict 38.9% of the variation in improvement in functional outcomes (forward elevation). This was only slightly greater than that provided by improvements in the outcome variable Constant-Murley score alone (36.7%).

CONCLUSIONS

The 3 shoulder outcome scores evaluated, regardless of whether they were patient reported or physician based, appear to appropriately reflect improvements after RSA with equal validity. The objective physician-assessed Constant-Murley score had the strongest correlation with function of the arm, and use of a combination of all 3 outcome scores did not increase the ability to predict range of motion compared with using the Constant-Murley score alone.

Computational reverse shoulder prosthesis model: Experimental data and verification

The reverse shoulder prosthesis aims to restore the stability and function of pathological shoulders, but the biomechanical aspects of the geometrical changes induced by the implant are yet to be fully understood. Considering a large-scale musculoskeletal model of the upper limb, the aim of this study is to evaluate how the Delta reverse shoulder prosthesis influences the biomechanical behavior of the shoulder joint. In this study, the kinematic data of an unloaded abduction in the frontal plane and an unloaded forward flexion in the sagittal plane were experimentally acquired through video-imaging for a control group, composed of 10 healthy shoulders, and a reverse shoulder group, composed of 3 reverse shoulders. Synchronously, the EMG data of 7 superficial muscles were also collected. The muscle force sharing problem was solved through the minimization of the metabolic energy consumption. The evaluation of the shoulder kinematics shows an increase in the lateral rotation of the scapula in the reverse shoulder group, and an increase in the contribution of the scapulothoracic joint to the shoulder joint. Regarding the muscle force sharing problem, the musculoskeletal model estimates an increased activity of the deltoid, teres minor, clavicular fibers of the pectoralis major, and coracobrachialis muscles in the reverse shoulder group. The comparison between the muscle forces predicted and the EMG data acquired revealed a good correlation, which provides further confidence in the model. Overall, the shoulder joint reaction force was lower in the reverse shoulder group than in the control group.

Uncemented versus cemented humeral stem fixation in reverse shoulder arthroplasty

PURPOSE

This study compares the radiographic and functional outcomes of uncemented and cemented humeral fixation in reverse total shoulder arthroplasty (RTSA).

METHODS

A prospective research database was reviewed for RTSA patients from 2007 to 2010. Inclusion criteria were primary RTSA from one manufacturer (Exactech Equinoxe®) with a grit-blasted metaphyseal humeral stem and two year minimum follow-up. Exclusion criteria included shoulder arthroplasty for fractures, fracture sequelae or inflammatory arthropathy. Radiographic and functional outcomes were compared between the uncemented and cemented groups.

RESULTS

A total of 97 patients (58 women, 39 men) with 100 RTSAs met the inclusion criteria. Radiographic and clinical two year follow-up was available in 80 % (51 RTSAs) of the uncemented group and 89 % (32 RTSAs) of the cemented group (mean follow-up 3.5 years). Average age at surgery was 72 years. Both groups showed significant improvements in the 12-item Simple Shoulder Test (SST-12), 12-item Short Form (SF-12), Shoulder Pain and Disability Index 130 (SPADI-130), American Society of Shoulder and Elbow Surgeons (ASES) score and normalised Constant scores. One humeral loosening was seen in each group (2 % uncemented, 3 % cemented). Both groups' overall component revision rate was 6 % (one in each group relating to humeral component failure). There were no significant differences in complication rates, change in functional scores and range of motion improvement.

CONCLUSIONS

Humeral component press-fitting in RTSA provides similar outcomes as cementation at a minimum two year follow-up.

Biomechanical effects of humeral neck-shaft angle and subscapularis integrity in reverse total shoulder arthroplasty

BACKGROUND

The variability in functional outcomes and the occurrence of scapular notching and instability after reverse total shoulder arthroplasty remain problems. The objectives of this study were to measure the effect of reverse humeral component neck-shaft angle on impingement-free range of motion, abduction moment, and anterior dislocation force and to evaluate the effect of subscapularis loading on dislocation force.

METHODS

Six cadaveric shoulders were tested with 155°, 145°, and 135° reverse shoulder humeral neck-shaft angles. The adduction angle at which bone contact occurred and the internal and external rotational impingement-free range of motion angles were measured. Glenohumeral abduction moment was measured at 0° and 30° of abduction, and anterior dislocation forces were measured at 30° of internal rotation, 0°, and 30° of external rotation with and without subscapularis loading.

RESULTS

Adduction deficit angles for 155°, 145°, and 135° neck-shaft angle were 2° ± 5° of abduction, 7° ± 4° of adduction, and 12° ± 2° of adduction (P < .05). Impingement-free angles of humeral rotation and abduction moments were not statistically different between the neck-shaft angles. The anterior dislocation force was significantly higher for the 135° neck-shaft angle at 30° of external rotation and significantly higher for the 155° neck-shaft angle at 30° of internal rotation (P < .01). The anterior dislocation forces were significantly higher when the subscapularis was loaded (P < .01).

CONCLUSIONS

The 155° neck-shaft angle was more prone to scapular bone contact during adduction but was more stable at the internally rotated position, which was the least stable humeral rotation position. Subscapularis loading gave further anterior stability with all neck-shaft angles at all positions.

Short-stem uncemented primary reverse shoulder arthroplasty

Short uncemented humeral stems can preserve humeral bone stock and facilitate revision surgery but may be prone to malalignment or loosening, especially when used in reverse total shoulder replacement (TSR). We undertook a retrospective review of 44 patients with a mean age of 76 years (59 to 92) who underwent primary reverse TSR with a short uncemented humeral stem. There were 29 females. The indications for joint replacement included cuff tear associated arthropathy (33), avascular necrosis (six), post-traumatic arthritis (two), and inflammatory arthritis (three). At a mean follow-up of 27 months (24 to 40), pain was rated as mild or none in 43 shoulders (97.7%). The mean active elevation improved from 54° (sd 20°) to 142° (sd 25°) and the mean active external rotation from 14° (sd 13°) to 45° (sd 9°). The outcome, as assessed by the modified Neer score, was excellent in 27 (61.3%), satisfactory in 15 (34.1%), and unsatisfactory in two shoulders (4.5%). Stems were well-positioned, without evidence of significant valgus or varus malalignment in 42 TSRs (95.5%). There was no radiological evidence of loosening of the humeral stem in any patient; 13 TSRs (29.5%) had evidence of proximal humeral remodelling and scapular notching was noted in three (6.8%).

Cite this article: Bone Joint J 2014;96-B:526–9.

Multibody System of the Upper Limb Including a Reverse Shoulder Prosthesis

The reverse shoulder replacement, recommended for the treatment of several shoulder pathologies such as cuff tear arthropathy and fractures in elderly people, changes the biomechanics of the shoulder when compared to the normal anatomy. Although several musculoskeletal models of the upper limb have been presented to study the shoulder joint, only a few of them focus on the biomechanics of the reverse shoulder. This work presents a biomechanical model of the upper limb, including a reverse shoulder prosthesis, to evaluate the impact of the variation of the joint geometry and position on the biomechanical function of the shoulder. The biomechanical model of the reverse shoulder is based on a musculoskeletal model of the upper limb, which is modified to account for the properties of the DELTA® reverse prosthesis. Considering two biomechanical models, which simulate the anatomical and reverse shoulder joints, the changes in muscle lengths, muscle moment arms, and muscle and joint reaction forces are evaluated. The muscle force sharing problem is solved for motions of unloaded abduction in the coronal plane and unloaded anterior flexion in the sagittal plane, acquired using video-imaging, through the minimization of an objective function related to muscle metabolic energy consumption. After the replacement of the shoulder joint, significant changes in the length of the pectoralis major, latissimus dorsi, deltoid, teres major, teres minor, coracobrachialis, and biceps brachii muscles are observed for a reference position considered for the upper limb. The shortening of the teres major and teres minor is the most critical since they become unable to produce active force in this position. Substantial changes of muscle moment arms are also observed, which are consistent with the literature. As expected, there is a significant increase of the deltoid moment arms and more fibers are able to elevate the arm. The solutions to the muscle force sharing problem support the biomechanical advantages attributed to the reverse shoulder design and show an increase in activity from the deltoid, teres minor, and coracobrachialis muscles. The glenohumeral joint reaction forces estimated for the reverse shoulder are up to 15% lower than those in the normal shoulder anatomy. The data presented here complements previous publications, which, all together, allow researchers to build a biomechanical model of the upper limb including a reverse shoulder prosthesis.

Glenoid screw position in the Encore Reverse Shoulder Prosthesis: an anatomic dissection study of screw relationship to surrounding structures

BACKGROUND

Fixation of the baseplate to the glenoid for the Reverse Shoulder Prosthesis (DJO Surgical, Austin, TX, USA) requires secure screw purchase to avoid excessive micromotion and baseplate failure. The best screw length for fixation is unknown. In addition, excessively long screws or a plunge of the drill bit during baseplate insertion could injure surrounding structures.

METHODS

Reverse Shoulder Prosthesis baseplates were inserted in 10 fresh-frozen shoulders by use of a 6.5-mm central screw and four 5.0-mm peripheral locking screws placed 90° to the baseplate. The top superior screw was placed into the base of the coracoid, corresponding to the 1-o'clock position in a right shoulder. The distances to surrounding vital structures were recorded, screws were removed, and screw hole lengths were measured to determine the most effective lengths in different parts of the glenoid scapula.

RESULTS

The screw length was 30 mm for the superior screw holes, 28 mm for the inferior screw holes, 13 mm for the anterior screw holes, and 15 mm for the posterior screw holes. The central screw trajectory was through the anterior cortex. The anterior screw trajectory violated the subscapularis belly in all specimens. The posterior screw touched the suprascapular nerve or artery in 3 of 10 specimens.

DISCUSSION

The superior and inferior screws have the longest bony fixation. Drill bit plunge during placement of the anterior screw poses a risk to the subscapularis muscle. Drilling for the posterior screw risks injury to the suprascapular nerve and artery at the spinoglenoid notch.

CONCLUSIONS

The posterior screw should be placed with care to avoid neurovascular complications.

Revision of an unstable hemiarthroplasty or anatomical total shoulder replacement using a reverse design prosthesis

Instability after arthroplasty of the shoulder is difficult to correct surgically. Soft-tissue procedures and revision surgery using unconstrained anatomical components are associated with a high rate of failure. The purpose of this study was to determine the results of revision of an unstable anatomical shoulder arthroplasty to a reverse design prosthesis. Between 2004 and 2007, 33 unstable anatomical shoulder arthroplasties were revised to a reverse design. The mean age of the patients was 71 years (53 to 86) and their mean follow-up was 42 months (25 to 71). The mean time to revision was 26 months (4 to 164). Pain scores improved significantly (pre-operative visual analogue scale (VAS) of 7.2 (sd 1.6); most recent VAS 2.2 (sd 1.9); p = 0.001). There was a statistically significant increase in mean active forward elevation from 40.2° (sd 27.3) to 97.0° (sd 36.2) (p = 0.001). There was no significant difference in internal (p = 0.93) or external rotation (p = 0.40). Radiological findings included notching in five shoulders (15%) and heterotopic ossification of the inferior capsular region in three (9%). At the last follow-up 31 shoulders (94%) were stable. The remaining two shoulders dislocated at 2.5 weeks and three months post-operatively, respectively. According to the Neer rating system, there were 13 excellent (40%), ten satisfactory (30%) and ten unsatisfactory results (30%). Revision of hemiarthroplasty or anatomical total shoulder replacement for instability using a reverse design prosthesis gives good short-term results.

Cite this article: Bone Joint J 2013;95-B:668–72.

Complications with reverse total shoulder arthroplasty and recent evolutions

Since its description by Paul Grammont from Dijon, France, several tens of thousands of reverse total shoulder arthroplasties (RTSA) have been performed for diverse conditions. The purpose of this analysis is to identify the complications of this procedure in the literature and in clinical practice. A total of 240 papers concerning RTSA published between 1996 and 2012 have been identified. Over 80 papers describe complications associated with this type of implant. A list of prostheses satisfying European and US standards, CE and FDA approved, has been produced on the basis of information provided by the manufacturers. Data from the literature do not support a meta-analysis. The inventory of best practices shows excellent results in the short and medium term in specific indications, while the number of complications varies between 10 and 65 % in long-term series. Complications can be classified into (A) non-specific including infections (superficial and deep), phlebitis, haematoma, neurological complications of the suprascapular, radial and axillary nerves and (B) specific complications associated with RTSA including (1) on the glenoid side: intraoperative fracture of the glenoid and acromion, late fracture of the scapula, impingement at the scapular neck (notching), glenoid loosening, dissociation of the glenoid component (snatching of the glenosphere) and fractures of the glenoid baseplate; (2) on the humeral side: metaphyseal deterioration, humeral loosening, instability of the shoulder, stiffness with limitation of external and/or internal rotation; and (3) muscular complications with fatty degeneration of the deltoid. Additionally we have identified specific situations related to the type of implant such as the disassembly of the humeral or the glenoid component, dissociation of the polyethylene humeral plate, dissociation of the metaphysis and osteolysis of the tuberosities. The integration of results from different clinical series is difficult because of the lack of a database and the multitude of implants used.

Functional and clinical outcome of total shoulder arthroplasty with oversized glenoid

BACKGROUND

The Epoca-Reconstruction-(Reco)®-Glenoid has been developed to treat patients with cuff-tear-arthropathy. The glenoid component of this system has a hemispheric shape that canopies the humeral head. This design is believed to provide a stable fulcrum and restore normal deltoid function. The purpose of this study was to analyse strengths and disadvantages of the Epoca-Reco®-Glenoid in cuff-tear-arthropathy patients. Changes in functional outcome using Constant-Murley-Scoring(CMS), CMS sub-scoring parameters and radiological outcome were analysed. For this purpose, a classification for radiologic lucency was proposed. Diverging results, influencing factors and alternative treatment options have been discussed to analyse weaknesses and enhance future development of this arthroplastic model.

MATERIALS AND METHODS

23 patients aged 68 ± 8.4 years with irreparable cuff-tear-arthropathy refractory to physiotherapeutic treatment were treated with Reco-Glenoid Total-Shoulder-Arthroplasty (TSA). Pre-operative standardized evaluations included history, physical examination, radiographs, computer tomography and clinical scorings. The post-operative controls included physical examination with CMS, video documentation and radiological evaluation.

RESULTS

After a median follow-up time of 38 ± 18 months, the CMS had been significantly improved (p < 0.001) from (17.4 ± 5.8) to (43.2 ± 19.2) points. Significant improvement in pain, activities of daily life, range of motion (p < 0.001) and power (p = 0.006) was achieved. Significantly, inferior results in functional outcome and higher lucency rates were observed in female patients and in patients treated with small glenoid components. The follow-up rate was 100 %.

CONCLUSION

The semi-constraint reconstruction glenoid prosthesis model in cuff-tear-arthropathy patients significantly improves shoulder function, however, it yields controversial results, with satisfactory results in male and poor results in female patients. Revision rate of the female cohort and loosening of the glenoid component in this short-term follow-up is of concern. Further investigations taking BMD, osteopenic conditions and influence of surface area in smaller individuals into consideration are recommended, to determine whether this is the underlying cause of the inferior results in females.

A cadaveric model for suprascapular nerve injury during glenoid component screw insertion in reverse-geometry shoulder arthroplasty

BACKGROUND

Reverse-geometry shoulder replacement requires fixation of a baseplate (called a metaglene) to the glenoid, to which a convex glenosphere is attached. Most systems use screws to achieve this fixation. The suprascapular nerve passes close to the glenoid and is known to be at risk of injury when devices and sutures are inserted into the glenoid. We investigate the risk posed to the suprascapular nerve by placement of metaglene fixation screws.

MATERIALS AND METHODS

Ten cadaveric shoulder specimens were used. A metaglene was inserted and fixed by use of 4 screws. The suprascapular nerve was dissected and its branches identified. The screw tips and their proximity to the nerve and branches were identified and recorded.

RESULTS

The superior and posterior screws posed the most risk to the suprascapular nerve. The nerve was engaged by the posterior screw on 4 occasions and was within 5 mm of the nerve or a branch of it in 5 others. The superior screw was extraosseous on 4 occasions, making contact with the nerve in 3 of those 4 specimens and being within 2 mm of it in the fourth specimen.

CONCLUSION

Metaglene fixation with screws poses a significant risk to the suprascapular nerve. Caution should be used when inserting the posterior and superior screws in particular. Short locking screws may allow adequate fixation while minimizing the risk of neurologic injury.

Acromial base fractures after reverse total shoulder arthroplasty: report of five cases

BACKGROUND

Most series of reverse total shoulder arthroplasty (rTSA) have reported acromial fractures, but they have not been shown to alter reported outcomes in most series. We present 5 patients with acromial base fractures where the entire deltoid origin was displaced from its anatomic location.

MATERIALS AND METHODS

Five patients with acromial base fractures after rTSA were identified and evaluated for functional outcomes and pain relief as well as results of fracture treatment. Three were treated operatively and 3 were treated nonoperatively. One nonoperative treatment eventually required open reduction and internal fixation.

RESULTS

Function was limited after fracture, with average forward elevation of only 43° but which improved to 84° after fracture union. Pain was significant after the fracture (6.8 of 10) and improved with fracture healing (0.8 of 10). Neer Functional Outcome scores after fracture union averaged 62 of 100, consistent with unsatisfactory results.

CONCLUSION

Acromial base fractures after rTSA are a painful and disabling complication. The outcomes appear different in this series than in other series describing acromial fractures. This may be a result of the different anatomic location of the fractures. Pain improves with fracture union, but functional returns are unpredictable.

Total shoulder arthroplasty

Shoulder arthroplasty has been the subject of marked advances over the last few years. Modern implants provide a wide range of options, including resurfacing of the humeral head, anatomic hemiarthroplasty, total shoulder arthroplasty, reverse shoulder arthroplasty and trauma-specific implants for fractures and nonunions. Most humeral components achieve successful long-term fixation without bone cement. Cemented all-polyethylene glenoid components remain the standard for anatomic total shoulder arthroplasty. The results of shoulder arthroplasty vary depending on the underlying diagnosis, the condition of the soft-tissues, and the type of reconstruction. Total shoulder arthroplasty seems to provide the best outcome for patients with osteoarthritis and inflammatory arthropathy. The outcome of hemiarthroplasty for proximal humerus fractures is somewhat unpredictable, though it seems to have improved with the use of fracture-specific designs, more attention to tuberosity repair, and the selective use of reverse arthroplasty, as well as a shift in indications towards internal fixation. Reverse shoulder arthroplasty has become extremely popular for patients with cuff-tear arthropathy, and its indications have been expanded to the field of revision surgery. Overall, shoulder arthroplasty is a very successful procedure with predictable pain relief and substantial improvements in motion and function.

Observations on retrieved humeral polyethylene components from reverse total shoulder arthroplasty

HYPOTHESIS

Analyses of polyethylene components retrieved at revision of total knee, hip, and shoulder replacements have been used to study the effect of design, patient, and surgical factors on initial implant performance, but no studies have reported similar types of findings in retrieved humeral polyethylene components in reverse total shoulder arthroplasty. Our hypothesis is that while the conforming surface of the humeral polyethylene may predispose it to surface wear modalities, as seen in total hip arthroplasty, the presence of clinical instability may also increase the occurrence of focal contact stresses leading to subsurface fatigue failure.

MATERIALS AND METHODS

Fourteen humeral polyethylene components were retrieved from revision surgery at a single institution. Each polyethylene was analyzed for 9 modes of damage in each of 4 quadrants into which the bearing surface was divided. For each implant, the most recent radiographs before removal were scored using an adapted radiolucency score, and glenosphere positioning was measured.

RESULTS

Despite the short mean length of implantation (0.46 ± 0.5 years), scratching and abrasion were seen in 14 and 13 components, respectively, followed by third-body debris and pitting. The modes of damage observed were most severe in the inferior quadrant of the humeral polyethylene. Scapular notching, glenoid, and humeral radiolucencies were prevalent on preoperative radiographs, but their long-term significance has not yet been elucidated. Increased glenosphere inclination was associated with decreased superior and total glenoid radiolucency, along with total polyethylene wear scores.

DISCUSSION

Promising early, functional results with the use of reverse total shoulder arthroplasty has led to the increased expansion of its use, but high complication and revision rates continue to raise concerns regarding implant longevity. The presence of a clinical, adduction deficit may predispose patients to inferior quadrant polyethylene wear.

CONCLUSIONS

Impingement of the humeral polyethylene at the lateral edge of the scapula leads to inferior quadrant wear and associated polyethylene failure, and implant instability may predispose the components to fatigue wear mechanisms. Analysis of retrieved humeral polyethylene components, along with patient, design, and surgical factors, provide important information on the causes of component failure.

The effect of component positioning on intrinsic stability of the reverse shoulder arthroplasty

HYPOTHESIS

Anterior instability is one of the most common complications in reverse shoulder replacement. This study hypothesized that intrinsic stability of a reverse prosthesis varies with the degree of version of the humerus and glenoid components. This should provide guidelines on how to best position the implant components to decrease the rate of dislocation.

MATERIALS AND METHODS

Resistance to anterior dislocation of a reverse implant was measured in a mechanical testing machine by means of the stability ratio (ratio of peak dislocation/axial compressive forces). Versions of the humeral and glenoid components were modified in 10 degrees steps in the 90 degrees abducted and resting positions.

RESULTS

In both tested positions, the effect of humeral component version was highly significant. Only a glenoid component retroversion of 20 degrees led to a statistically significant drop in stability ratio for the 20 degrees abducted position. Intrinsic stability in the typical component positioning (neutral glenoid version and 20 degrees humeral retroversion) yielded comparably low intrinsic stability, which could only be improved by increasing anteversion of the humeral component.

DISCUSSION

Version of the humeral component is the critical factor for intrinsic stability. Version of the glenoid component is less important for intrinsic stability, but special care should be given to avoid retroversions of more than 10 degrees . Within this range, the surgeon can concentrate primarily on other parameters critical for long-term outcome (range of motion, secure fixation) when choosing the appropriate glenoid version.

CONCLUSION

Anterior stability can be improved by implanting the humeral component in neutral or with some anteversion.

What is a Successful Outcome Following Reverse Total Shoulder Arthroplasty?

Background:

With variations in joint destruction, patient expectations and health status, it can be difficult to interpret outcomes following arthroplasty. The purpose of this study was to determine the relationships between different outcome indicators in 44 patients followed for two years after a reverse shoulder arthroplasty.

Methods:

Prospectively collected outcomes included the Constant-Murley score, Simple Shoulder Test (SST), range of motion (ROM), strength, patient satisfaction with their care and independent clinician case-review to determine global clinical outcome. Continuous outcomes were divided in two subgroups according to definitions of functional outcomes. Cohen’s kappa was used to evaluate agreement between outcomes. Pearson correlations were used to quantify interrelationships.

Results:

Although 93% of patients were substantially satisfied, fewer had good results on the other outcomes: 68% on global clinical outcome, 46% on SST and 73% on Constant-Murley score. The SST demonstrated better than chance agreement with Constant-Murley score, ROM in flexion, abduction and external rotation, and strength in external rotation. No agreement between satisfaction and other outcomes were observed. Significant correlations were observed between Constant-Murley score and SST (r = 0.78). The Constant-Murley score and SST demonstrated variable correlation with ROM and strength in flexion, abduction, internal and external rotation (0.38 < r < 0.73); the highest correlations being observed with shoulder elevation ROM (r > 0.50).

Conclusions:

Results show that outcome varies according to patient perspective and assessment methods. Patient satisfaction with their care was related to neither self-reported nor physical impairment outcomes. Positive patient ratings of satisfaction may not necessarily be evidence of positive outcomes.