Reverse Total Shoulder Arthroplasty with a Cementless and Metaphyseal Stem Fixation Is a Viable Option for the Treatment of Proximal Humeral Fractures with Calcar Involvement

BACKGROUND

The purpose of the study was to evaluate the suitability of reverse total shoulder arthroplasty (RTSA) with a cementless and metaphyseal stem fixation as a treatment for complex proximal humeral fractures (PHFs) with a calcar fragment when this may be fixed with a steel wire cerclage. Clinical and radiographic outcomes were compared with the same RTSA for PHFs without a calcar fragment at a minimum of five-year follow-up.

METHODS

A retrospective analysis was performed on acute PHFs "with a medial calcar fragment" (group A) and "without a calcar fragment" (group B) treated with a RTSA and cementless metaphyseal stem fixation.

RESULTS

At an average follow-up of 6.7 years (5-7.8 years), no statistical difference was observed comparing group A (18 patients) to group B (50 patients) for active anterior elevation (141 ± 15° vs. 145 ± 10°, p = 0.67), active external rotation ER1 (49 ± 15° vs. 53 ± 13°, p = 0.55), and active internal rotation (5 ± 2 vs. 6 ± 2, p = 0.97). Similarly, a comparison of ASES score (89.2 ± 10 vs. 91.6 ± 9, p = 0.23) and Simple Shoulder Test score (91.1 ± 11 vs. 90.4 ± 10, p = 0.49) revealed no significant difference.

CONCLUSION

RTSA with a cementless and metaphyseal stem fixation represents a safe and feasible treatment for complex PHFs with a medial calcar fragment when this may be fixed with a steel wire cerclage.

Increased Risk of Periprosthetic Fractures and Revision Arthroplasty in Patients Undergoing Shoulder Arthroplasty With a History of Prior Fragility Fractures: A Matched Cohort Analysis

INTRODUCTION

As rates of anatomic and reverse total shoulder arthroplasty (SA) continue to grow, an increase in the number of osteoporotic patients undergoing SA, including those who have sustained prior fragility fractures, is expected. The purpose of this study was to examine short-term, implant-related complication rates and secondary fragility fractures after SA in patients with and without a history of fragility fractures.

METHODS

A propensity score-matched retrospective cohort study was done using the PearlDiver database to characterize the effect of antecedent fragility fractures in short-term complications after SA. Rates of revision SA, periprosthetic fractures, infection, and postoperative fragility fractures were evaluated using multivariate logistic regression analysis. Risks of these complications were also studied in patients with and without preoperative osteoporosis treatment. Statistical significance was set at P < 0.05.

RESULTS

A total of 91,212 SA patients were identified, with 13,050 (14.3%) experiencing a fragility fracture within the 3 years before SA. Two years after SA, there were increased odds of periprosthetic fracture (odds ratio [OR] 2.24, 95% confidence interval [CI] 1.68 to 2.99), fragility fracture (OR 9.11, 95% CI 8.43 to 9.85), deep infection (OR 1.68, 95% CI 1.34 to 2.12), and all-cause revision SA (OR 1.68, 95% CI 1.44 to 1.96) within those patients who had experienced a fragility fracture within 3 years before their SA. Patients who were treated for osteoporosis with bisphosphonates and/or vitamin D supplementation before their SA had similar rates of postoperative periprosthetic fractures, fragility fractures, and all-cause revision SA to those who did not receive pharmacologic treatment.

CONCLUSION

Sustaining a fragility fracture before SA portends substantial postoperative risk of periprosthetic fractures, infection, subsequent fragility fractures, and all-cause revision SA at the 2-year postoperative period. Pharmacotherapy did not markedly decrease the rate of these complications. These results are important for surgeons counseling patients who have experienced prior fragility fractures on the risks of SA.

Finite element analysis to predict short and medium-term performance of the anatomical Comprehensive® Total Shoulder System

BACKGROUND

The number of Total Shoulder Arthroplasties (TSA) has increased in these last years with significant increase of clinical success. However, glenoid component loosening remains the most common cause of failure.

OBJECTIVE

In this study we evaluated the critical conditions to predict short and medium-term performance of the uncemented anatomical Comprehensive® Total Shoulder System using a finite element model that was validated experimentally.

METHODS

The finite element models of an implanted shoulder analysed included total shoulder components with pegs. The models were simulated in 3 phases of adduction: 45°, 60° and 90° to determine the most critical situation. Two different bone-implant fixation conditions were considered: post-surgery and medium term (2 years).

RESULTS

These show that the critical condition is for the shoulder in 90° adduction were the highest contact stress (70 MPa) was observed in the glenoid component. Relatively to the interface implant-bone strains, the maximum (-16000 µε) was observed for the short-term in the lateral region of the humerus. The highest micromotions were observed in the central fixation post of the glenoid component, ranging from 20 to 25 µm, and 325 µm in the lateral plane of the humeral component.

CONCLUSION

The predicted results are in accordance with clinical studies published and micromotions of the humeral component can be used to predict loosening and to differentiate shoulder implant designs.

Are short press-fit stems comparable to standard-length cemented stems in reverse shoulder arthroplasty? A prospective, randomized clinical trial

BACKGROUND

The literature comparing humeral implants in reverse shoulder arthroplasty is sparse. With minimal supporting literature, there has been a trend away from standard-length cemented humeral implants to press-fit stems and, recently, to shorter-stem implants. It is known that early implant migration, within the first 2 years postoperatively, is predictive of later implant loosening and possible revision surgery. Therefore, the purpose of this study was to compare clinical outcomes and implant migration between cemented standard-length humeral stems and press-fit short stems using model-based radiostereometric analysis.

METHODS

After a power analysis, 41 shoulders were prospectively randomized to receive either a cemented standard-length or press-fit short humeral stem for primary reverse shoulder arthroplasty between July 2017 and June 2019. Following surgery, participants were imaged with stereo radiographs acquired at 6 weeks (baseline), 3 months, 6 months, 1 year, and 2 years. Migration of the humeral stem at each time point was compared with baseline, with differences in migration between cohorts assessed using a mixed-effects model with the Bonferroni test for multiple comparisons. Patient-reported outcome measures (Subjective Shoulder Value; American Shoulder and Elbow Surgeons shoulder score; Simple Shoulder Test score; Disabilities of the Arm, Shoulder and Hand score; and Constant score) were also compared.

RESULTS

At 6 months (P = .025), 1 year (P = .004), and 2 years (P = .001) postoperatively, press-fit short stems migrated significantly more than cemented stems along the superior-inferior translation axis; in addition, they showed greater total translation at 2 years (P = .003). Mean total translation (± standard deviation) at 2 years was 0.4 ± 0.2 mm and 1.0 ± 1.1 mm for the cemented and press-fit cohorts, respectively. Mean migration between the 1- and 2-year time points was minimal for both stem fixation groups along all axes (<0.1 mm and 0.6°). There was no difference in active range of motion, pain, or validated outcome measures between the cohorts at 2 years (P ≥ .170).

CONCLUSION

This randomized clinical trial shows that press-fit short humeral stems subside substantially more than standard-length cemented stems but ultimately achieve stability from 1 year through 2 years. Conversely, no significant differences were observed in clinical outcomes between cohorts.

Biomechanics of anatomic and reverse shoulder arthroplasty

The biomechanics of the shoulder relies on careful balancing between stability and mobility. A thorough understanding of normal and degenerative shoulder anatomy is necessary, as the goal of anatomic total shoulder arthroplasty is to reproduce premorbid shoulder kinematics.With reported joint reaction forces up to 2.4 times bodyweight, failure to restore anatomy and therefore provide a stable fulcrum will result in early implant failure secondary to glenoid loosening.The high variability of proximal humeral anatomy can be addressed with modular stems or stemless humeral components. The development of three-dimensional planning has led to a better understanding of the complex nature of glenoid bone deformity in eccentric osteoarthritis.The treatment of cuff tear arthropathy patients was revolutionized by the arrival of Grammont's reverse shoulder arthroplasty. The initial design medialized the centre of rotation and distalized the humerus, allowing up to a 42% increase in the deltoid moment arm.More modern reverse designs have maintained the element of restored stability but sought a more anatomic postoperative position to minimize complications and maximize rotational range of motion. Cite this article: EFORT Open Rev 2021;6:918-931. DOI: 10.1302/2058-5241.6.210014.

Subsidence of Uncemented Short Stems in Reverse Shoulder Arthroplasty-A Multicenter Study

BACKGROUND

The radiological phenomenon of subsidence following the implantation of uncemented short-stem reverse prostheses (USSP) has not yet been described. The purpose of this study was to describe the rate and potential risk factors for subsidence. We hypothesized that subsidence may be a frequent finding and that a subsidence of >5 mm (mm) is associated with an inferior clinical outcome.

METHODS

A total of 139 patients with an average age of 73 ± 9 years were included. The clinical and radiological outcome was evaluated at a minimum follow-up (FU) of 12 months.

RESULTS

No humeral component loosening was present at a mean FU of 18 (range, 12-51) months. Mean Constant Score (CS) and Subjective Shoulder Value (SSV) improved significantly from 34.3 ± 18.0 points and 37.0 ± 19.5% preoperatively to 72.2 ± 13.4 points and 80.3 ± 16.5% at final FU (p < 0.001). The average subsidence of the USSP was 1.4 ± 3.7 mm. Subsidence of >5 mm was present in 15 patients (11%). No association between a subsidence >5 mm and CS or SSV was found (p = 0.456, p = 0.527). However, a subsidence of >5 mm resulted in lower strength at final FU (p = 0.022). Complications occurred in six cases (4.2%), and the revision rate was 3.5% (five cases).

CONCLUSIONS

Although subsidence of USSP is a frequent radiographic finding it is not associated with loosening of the component or a decrease in the clinical outcome at short term FU.

LEVEL OF EVIDENCE

Level 4, retrospective study.

Proximal humeral osteolysis and glenoid radiolucent lines in an anatomic shoulder arthroplasty: a comparison of a ceramic and a metal humeral head component

BACKGROUND

In vitro wear studies demonstrate decreased polyethylene wear with a ceramic compared with a metal humeral head. In this in vivo study, we analyzed prospectively collected 5-year data, comparing the outcomes of 2 types of humeral implants.

METHODS

Sixty-two anatomic total shoulder arthroplasties (TSAs) (59 patients) were performed using the same glenoid component and 2 types of modular humeral implants (metal-head long-stem prosthesis in group A vs. ceramic-head stemless prosthesis in group B). Radiographic analysis for proximal humeral osteolysis and glenoid component radiolucent lines was performed at an average of 5.5 years. Functional outcomes were prospectively evaluated according to the visual analog scale score for pain; satisfaction level; American Shoulder and Elbow Surgeons score; active elevation; Shoulder Pain and Disability Index score; and Disabilities of the Arm, Shoulder and Hand score.

RESULTS

There were 39 TSAs in group A (mean age, 68.1 years) and 23 TSAs in group B (mean age, 67 years). Clinical improvement was similar for both groups. Some proximal humeral osteolysis occurred in 56% of all TSAs. Group A showed increased osteolysis compared with group B (72% vs. 30%, P = .005). Glenoid radiolucent lines were far more frequent in group A, and group A showed a direct relationship between the extent of humeral osteolysis and the severity of glenoid radiolucent lines (P < .001).

CONCLUSION

The stemless ceramic-head replacements showed fewer glenoid radiolucent lines and less humeral osteolysis than the long-stem metal-head replacements. In the group with metal-head replacements, correlation was shown between glenoid radiolucent lines and humeral osteolysis.

Cemented humeral stem versus press-fit humeral stem in total shoulder arthroplasty: a systematic review and meta-analysis

AIMS

The aim of this study was to evaluate the differences in revision and complication rates, functional outcomes, and radiological outcomes between cemented and press-fit humeral stems in primary anatomical total shoulder arthroplasty (TSA).

MATERIALS AND METHODS

A comprehensive systematic review and meta-analysis was conducted searching for studies that included patients who underwent primary anatomical TSA for primary osteoarthritis or rheumatoid arthritis.

RESULTS

There was a total of 36 studies with 927 cemented humeral stems and 1555 press-fit stems. The revision rate was 5.4% (95% confidence interval (CI) 3.9 to 7.4) at a mean of 89 months for cemented stems, and 2.4% (95% CI 1.1 to 4.7) at a mean of 40 months for press-fit stems. A priori subgroup analysis to control for follow-up periods demonstrated similar revision rates: 2.3% (95% CI 1.1 to 4.7) for cemented stems versus 1.8% (95% CI 1.4 to 2.9) for press-fit stems. Exploratory meta-regression found that longer follow-up was a moderating variable for revision (p = 0.003).

CONCLUSION

Cement fixation had similar revision rates when compared to press-fit stems at short- to midterm follow-up. Rotator cuff pathology was a prevalent complication in both groups but is likely not related to fixation type. Overall, with comparable revision rates, possible easier revision, and decreased operative time, humeral press-fit fixation may be an optimal choice for primary anatomical TSA in patients with sufficient bone stock. Cite this article: Bone Joint J 2019;101-B:1107-1114.

The Humeral Implant in Shoulder Arthroplasty

Humeral hemiarthroplasty, anatomic total shoulder arthroplasty, and reverse total shoulder arthroplasty all rely on a prosthetic articular surface fixed to the proximal humerus. Humeral implant designs have changed considerably as a result of improved understanding of proximal humeral anatomy and prosthetic biomechanics. Fixed, monoblock implants have been superseded by modular implants with variable inclination, offset, version, and stem length. Press-fit designs now commonly have surface coatings that allow bony ingrowth. Metaphyseal fixation is often favored over diaphyseal fixation. Both cemented and noncemented fixation continue to be used, and each of these techniques has advantages and disadvantages. Although aseptic loosening rarely requires revision, complications, such as osteolysis, stress shielding, radiolucent lines, and proximal humeral bone loss, can occur. Humeral periprosthetic fractures continue to be a disabling complication and are difficult to manage. Innovations such as short-stemmed implants, stemless implants, and platform stems are currently under clinical investigation.

Long-term outcomes of cemented versus cementless humeral components in arthroplasty of the shoulder

Aims

In the initial development of total shoulder arthroplasty (TSA), the humeral component was usually fixed with cement. Cementless components were subsequently introduced. The aim of this study was to compare the long-term outcome of cemented and cementless humeral components in arthroplasty of the shoulder.

Patients and Methods

All patients who underwent primary arthroplasty of the shoulder at our institution between 1970 and 2012 were included in the study. There were 4636 patients with 1167 cemented humeral components and 3469 cementless components. Patients with the two types of fixation were matched for nine different covariates using a propensity score analysis. A total of 551 well-balanced pairs of patients with cemented and cementless components were available after matching for comparison of the outcomes. The clinical outcomes which were analysed included loosening of the humeral component determined at revision surgery, periprosthetic fractures, post-operative infection and operating time.

Results

The overall five-, ten-, 15- and 20-year rates of survival were 98.9%, 97.2%, 95.5%, and 94.4%, respectively. Survival without loosening at 20 years was 98% for cemented components and 92.4% for cementless components. After propensity score matching including fixation as determined by the design of the component, humeral loosening was also found to be significantly higher in the cementless group. Survival without humeral loosening at 20 years was 98.7% for cemented components and 91.0% for cementless components. There was no significant difference in the risk of intra- or post-operative fracture. The rate of survival without deep infection and the mean operating time were significantly higher in the cemented group.

Conclusion

Both types of fixation give rates of long-term survival of > 90%. Cemented components have better rates of survival without loosening but this should be weighed against increased operating time and the risk of bony destruction of the proximal humerus at the time of revision of a cemented humeral component. Cite this article: Bone Joint J 2017;99-B:666–73.

In vitro initial stability of a stemless humeral implant

BACKGROUND

Stemless humeral prostheses have been recently introduced. We measured for the first time their in vitro primary stability and analyzed the influence of three clinically important parameters (bone quality, implant size and post-operative loading) on micromotion. We also assessed if displacement sensors are appropriate to measure implant micromotion.

METHODS

A stemless humeral implant (Sidus® Stem-Free Shoulder, Zimmer GmbH, Winterthur, Switzerland) was implanted in 18 cadaveric humeri. Three-dimensional motion of the implant was measured under dynamic loading at three load magnitudes with displacement sensors. Additionally, the relative motion at the bone-implant interface was measured with an optical system in four specimens.

RESULTS

Micromotion values derived from the displacement sensors were significantly higher than those measured by the optical system (P<0.005). Analysis of variance (ANOVA) indicated that bone density (P<0.0005) and load (P<0.0001) had a significant effect on implant micromotion, however the effect of implant size was not statistically significant (P=0.123).

INTERPRETATION

Micromotion of this stemless design was shown to be significantly dependent on cancellous bone density. Patients must therefore have adequate bone quality for this procedure. The influence of load magnitude on micromotion emphasizes the need for controlled post-operative rehabilitation. Measurements with displacement sensors overestimate true interface micromotion by up to 50% and correction by an optical system is strongly recommended.

Results of uncemented hemiarthroplasty as primary treatment of severe proximal humerus fractures in the elderly

OBJECTIVES

The purpose of this study was to analyze functional and radiologic results of a consecutive series of elderly patients who underwent uncemented hemiarthroplasty as primary treatment of complex proximal humeral fractures.

METHODS

Twenty-one patients with severe proximal humerus fracture (three or four fragments and three- or four-fragment fracture dislocations) were treated with uncemented proximal humerus hemiarthroplasty. Patients were evaluated using the Constant-Murley Score, the Quick scale Disabilities of Arm, Shoulder and Hand (Quick-DASH) Score, range of motion, residual pain, radiographic parameters, and complications including clinical and radiologic data of mobilization.

RESULTS

After a mean postoperative period of 20.57 months (range 12-42 months), the mean Constant-Murley Score was 44 points (20-57), the mean Quick-DASH score was 24 points (16-39), postoperative pain according to a mean visual analogue scale was 1 (0-8), active abduction was 50° (30-135), and active flexion 70° (20-120). There were no cases of infection, deep vein thrombosis, dislocation, blood transfusions, or reoperation because of prosthetic loosening. Bivariate analysis of demographic data, radiologic findings, and other variables showed associations between duration of surgery and a higher Quick-DASH score (0.606; p = 0.037), and the number of sessions of rehabilitation with a higher Quick-DASH score (0.708; p = 0.015).

CONCLUSIONS

The results of treatment of severe proximal humerus fractures in the elderly with an uncemented hemiarthroplasty are safe and promising; however, a comparative cohort study (cemented vs. uncemented) and long-term follow-up are still needed.

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.

Primary uncemented hemiarthroplasty for severe fractures of the proximal humerus

OBJECTIVES

The purpose of this study is to evaluate a consecutive series of proximally porous-coated hemiarthroplasty for the treatment of severe proximal humeral fractures with special emphasis on aseptic loosening and functional outcome.

DESIGN

Observational cohort of a consecutive series of a single prosthetic design.

SETTING

Orthopaedic clinic, nonacademic institutional hospital.

PATIENTS/PARTICIPANTS

All patients (n = 30) treated with hemiarthroplasty for severe fractures of the proximal humerus with informed consent and at least 1 year follow-up were included. Follow-up averaged 37 months (range, 13-62 months).

INTERVENTION

Uncemented proximally porous-coated hemiarthroplasty.

MAIN OUTCOME MEASUREMENTS

We evaluated clinical and radiologic aseptic loosening, Constant score, patient satisfaction and visual analog scale score, range of motion, radiologic parameters such as head-to-tuberosity distance, lateral projection, and lateral offset.

RESULTS

: The overall Constant score was 68 (standard deviation [SD] 18), the mean patient satisfaction 7.1 (SD 1.8), and the average visual analog scale score 3.7 (SD 2.5). We observed no cases of radiographic tilting or subsidence. In 17 cases (57%), radiolucent lines 1.0 mm or less were observed in less than three zones. None of the cases met the criteria for radiographic loosening. No revision was performed for aseptic loosening. The average head-to-tuberosity distance was 7.6 (SD 8.7 mm). We found that traumatic neurologic deficit and head-to-tuberosity distance significantly influenced Constant score. Lateral projection significantly correlated with Constant score, active forward flexion, and abduction.

CONCLUSIONS

Proximally porous-coated hemiarthroplasty is a valuable alternative alongside cemented hemiarthroplasty for the treatment of severe fractures of the proximal humerus. The radiographic finding of increased lateral projection was associated with an improved range of motion.

Developments in shoulder arthroplasty

Indications for shoulder arthroplasty are numerous, mainly owing to glenohumeral osteoarthritis, rheumatoid arthritis, or fracture of the proximal humerus. However, the anatomy and the biomechanics of the shoulder are complex and shoulder arthroplasty has evolved significantly over the past 30 years. This paper presents the main recent evolutions in shoulder replacement, the questions not answered yet, and the main future areas of research. The review focuses firstly on the design, positioning, and fixation of the humeral component, secondly on the design, positioning, and fixation of the glenoid implant, and thirdly on other concepts of shoulder arthroplasty such as the reversed prosthesis, the cementless surface replacement arthroplasty, and the bipolar arthroplasty. This review demonstrates that more research is needed. Although, in the long term, large randomized trials are needed to settle the fundamental questions of what type of replacement and which kind of fixation should be used, biomechanical research in the laboratory should be focused primarily on the comprehension of glenoid loosening, which is a major cause of total shoulder arthroplasty failure, and the significance of radiolucent lines which are often seen but with no clear understanding about their relation with failure.