Total shoulder arthroplasty: are the humeral components getting shorter? Curr Rev Musculoskelet Med. 2016;9:17-22. [PMID: 26801933 DOI: 10.1007/s12178-016-9313-3]

Preoperative 3-dimensional computed tomography bone density measures provide objective bone quality classifications for stemless anatomic total shoulder arthroplasty

BACKGROUND

Reproducible methods for determining adequate bone densities for stemless anatomic total shoulder arthroplasty (aTSA) are currently lacking. The purpose of this study was to evaluate the utility of preoperative computed tomography (CT) imaging for assessing the bone density of the proximal humerus for supportive differentiation in the decision making for stemless humeral component implantation. It was hypothesized that preoperative 3-dimensional (3-D) CT bone density measures provide objective classifications of the bone quality for stemless aTSA.

METHODS

A 3-part study was performed that included the analysis of cadaveric humerus CT scans followed by retrospective application to a clinical cohort and classification with a machine learning model. Thirty cadaveric humeri were evaluated with clinical CT and micro-CT (μCT) imaging. Phantom-calibrated CT data were used to extract 3-D regions of interest and defined radiographic scores. The final image processing script was applied retrospectively to a clinical cohort (n = 150) that had a preoperative CT and intraoperative bone density assessment using the "thumb test," followed by placement of an anatomic stemmed or stemless humeral component. Postscan patient-specific calibration was used to improve the functionality and accuracy of the density analysis. A machine learning model (Support vector machine [SVM]) was utilized to improve the classification of bone densities for a stemless humeral component.

RESULTS

The image processing of clinical CT images demonstrated good to excellent accuracy for cylindrical cancellous bone densities (metaphysis [ICC = 0.986] and epiphysis [ICC = 0.883]). Patient-specific internal calibration significantly reduced biases and unwanted variance compared with standard HU CT scans (P < .0001). The SVM showed optimized prediction accuracy compared with conventional statistics with an accuracy of 73.9% and an AUC of 0.83 based on the intraoperative decision of the surgeon. The SVM model based on density clusters increased the accuracy of the bone quality classification to 87.3% with an AUC of 0.93.

CONCLUSIONS

Preoperative CT imaging allows accurate evaluation of the bone densities in the proximal humerus. Three-dimensional regions of interest, rescaling using patient-specific calibration, and a machine learning model resulted in good to excellent prediction for objective bone quality classification. This approach may provide an objective tool extending preoperative selection criteria for stemless humeral component implantation.

Evolution of Stemless Reverse Shoulder Arthroplasty: Current Indications, Outcomes, and Future Prospects

Reverse total shoulder arthroplasty (rTSA) is increasingly being used as a reliable option for various shoulder disorders with deteriorated rotator cuff and glenohumeral joints. The stemless humerus component for shoulder arthroplasties is evolving with theoretical advantages, such as preservation of the humeral bone stock and decreased risk of periprosthetic fractures, as well as clinical research demonstrating less intraoperative blood loss, reduced surgical time, a lower rate of intraoperative fractures, and improved center of rotation restoration. In particular, for anatomical total shoulder arthroplasty (aTSA), the utilization of stemless humeral implants is gaining consensus in younger patients. The current systematic review of 14 clinical studies (637 shoulders) demonstrated the clinical outcomes of stemless rTSA. Regarding shoulder function, the mean Constant-Murley Score (CS) improved from 28.3 preoperatively to 62.8 postoperatively. The pooled overall complication and revision rates were 14.3% and 6.3%, respectively. In addition, recent studies have shown satisfactory outcomes with stemless rTSA relative to stemmed rTSA. Therefore, shoulder surgeons may consider adopting stemless rTSA, especially in patients with sufficient bone quality. However, further long-term studies comparing survivorship between stemless and stemmed rTSA are required to determine the gold standard for selecting stemless rTSA.

Techniques to Address Humeral Bone Insufficiency During Total Shoulder Arthroplasty With a Nonspherical Humeral Head and Inlay Glenoid

Total shoulder arthroplasty with a humeral head resurfacing (HHR) component and an inlay glenoid (OVOMotion; Arthrosurface) is a successful treatment option for patients with advanced glenohumeral arthritis, an intact rotator cuff, and adequate proximal humeral bone stock. In patients with poor proximal humeral bone, historically stemmed humeral components have been used instead of HHR. However, strategies can be used to successfully optimize HHR implant fixation in suboptimal bone without converting to stemmed implants or in surgical centers where stemmed prostheses are not available. This Technical Note describes 3 techniques-upsizing the humeral taper post, using humeral autograft, and cementation-to improve humeral implant fixation in patients with suboptimal bone stock when using the Arthrosurface OVOMotion implant.

Radiographic comparison of eccentric stemmed vs. concentric stemless prosthetic humeral head positioning after anatomic total shoulder arthroplasty

INTRODUCTION

Maintaining premorbid proximal humeral positioning is an essential consideration of anatomic total shoulder arthroplasty (aTSA), as malposition of the prosthetic humeral head can result in poor clinical outcomes. Stemless aTSA prosthetic heads are usually concentric, while stemmed aTSA prosthetic heads are typically eccentric in nature. Therefore, the purpose of this study was to compare the ability to restore native humeral head position between stemmed (eccentric) vs. stemless (concentric) aTSA.

MATERIALS AND METHODS

Postoperative anteroposterior radiographs of 52 stemmed and 46 stemless aTSAs were analyzed. A best-fit circle was created using previously published and validated techniques to represent the premorbid humeral head position and axis of rotation. This circle was juxtaposed with another circle following the arc of the implant head. Next, the offset in center of rotation (COR), radius of curvature (RoC), and humeral head height above the greater tuberosity (HHH) were measured. Additionally, based on prior studies, an offset of >3 mm at any point between the implant head surface and premorbid best-fit circle was considered significant and further classified as overstuffed or understuffed.

RESULTS

RoC deviation was significantly greater in the stemmed cohort than the stemless cohort (1.19 ± 1.37 mm vs. 0.65 ± 1.17 mm, P = .025). There was no statistically significant difference in deviation from premorbid humeral head between the stemmed and stemless cohorts for COR (3.20 ± 2.28 mm vs. 3.23 ± 2.09 mm, P = .800) or HHH (1.12 ± 3.27 mm vs. 0.92 ± 2.70 mm, P = .677). When comparing overstuffed implants to appropriately placed implants, there was a significant difference in overall COR deviation in stemmed implants (3.93 ± 2.51 mm vs. 1.92 ± 1.05 mm, P < .001). Superoinferior COR deviation (stemmed: 2.38 ± 3.01 mm vs. -0.61 ± 1.59 mm, P < .001; stemless: 2.70 ± 1.75 mm vs. -0.16 ± 1.87 mm, P < .001), mediolateral COR deviation (stemmed: 0.79 ± 2.65 mm vs. -0.62 ± 1.27 mm, P = .020; stemless: 0.40 ± 1.41 mm vs. -1.13 ± 1.96 mm, P = .020), and HHH (stemmed: 3.61 ± 2.73 mm vs. 0.50 ± 1.31 mm, P < .001; stemless: 3.98 ± 1.18 mm vs. 0.53 ± 1.41 mm, P < .001) were significantly different between overstuffed implants and appropriate implants in both the stemmed and stemless cohorts.

DISCUSSION

Stemless and stemmed aTSA implants have similar rates of reproducing satisfactory postoperative humeral head COR with both producing COR deviation most commonly in the superomedial direction. Deviation in HHH contributes to overstuffing in both stemmed and stemless implants, COR deviation contributes to overstuffing in stemmed implants, while RoC (humeral head size) is not associated with overstuffing. Based on this study, it appears that neither eccentric nor concentric prosthetic heads are superior in recreating premorbid humeral head position.

Two-year minimum survivorship and radiographic analysis of a pressfit short humeral stem for total shoulder arthroplasty

Background

Newer generation humeral stem designs in total shoulder arthroplasty (TSA) are trending towards shorter lengths and uncemented fixation. The goal of this study is to report a 2-yr minimum clinical and radiographic outcomes of an uncemented short-stem press-fit humeral stem in anatomic total shoulder arthroplasty (ATSA) and reverse total shoulder arthroplasty (RTSA).

Methods

A retrospective multicenter database review was performed of all patients who received an uncemented short-length press-fit humeral stem (Equinoxe Preserve humeral stem, Exactech, Inc., Gainesville, FL, USA) in ATSA and RTSA with a minimum two-year follow-up. The primary outcome was the prevalence of humeral stems at risk of radiographic loosening. Secondary outcomes included evaluation of functional outcome scores and prevalence of revision TSA for humeral stem loosening. Two blinded observers performed radiographic analyses, which included humeral stem alignment, canal filling ratio, radiolucent lines, stress shielding (calcar and greater tuberosity), and changes in component position (subsidence and stem shift). At risk stems were defined by the presence of one or more of the following: humeral stem with shifting or subsidence, scalloping of the humeral cortex, or radiolucent lines measuring 2 mm or greater in 3 or more zones.

Results

287 patients (97 ATSA and 190 RTSA) were included in this study. The mean follow-up was 35.9 (±6.1) months. There were significant improvements for all functional outcome scores (P < .05), range of motion (P < .05), and visual analogue pain scale pain (P < .05). The prevalence of humeral stem at risk of radiographic loosening was 1% in the ATSA group (1/97) and 18.4% in the RTSA group (35/190). Calcar resorption was seen in 34% of ATSA and 19% of RTSA, with severe resorption in 12.4% of ATSA and only 3.2% of RTSA. Greater tuberosity resorption was present in 3.1% of ATSA and 7.9% of RTSA. The mean canal filling ratio was 50.2% (standard deviation 11.2%). Using logistic regression, a significant positive correlation between canal filling ratio and stress shielding (P < .01) was seen for both calcar and tuberosity stress shielding. The revision surgery rate was 0% in ATSA compared to 1.6% in RTSA.

Conclusion

This retrospective study demonstrates a low revision rate and low prevalence of humeral stems at risk of radiographic loosening at two years with a press-fit short-stem humeral design in ATSA. Physiologic subsidence of humeral stems can account for higher prevalence of humeral stems at radiographic risk of loosening in RTSA compared to ATSA.

Anatomic total shoulder arthroplasty with a nonspherical humeral head and inlay glenoid: 90-day complication profile in the inpatient versus outpatient setting

BACKGROUND

Total shoulder arthroplasty (TSA) with a nonspherical humeral head component and inlay glenoid is a successful bone-preserving treatment for glenohumeral arthritis. This study aimed to describe the 90-day complication profile of TSA with this prosthesis and compare major and minor complication and readmission rates between inpatient- and outpatient-procedure patients.

METHODS

A retrospective review was performed of a consecutive cohort of patients undergoing TSA with a nonspherical humeral head and inlay glenoid in the inpatient and outpatient settings by a single surgeon between 2017 and 2022. Age, sex, body mass index, American Society of Anesthesiologists (ASA) score, Charlson Comorbidity Index (CCI), and 90-day complication and readmission rates were compared between inpatient and outpatient groups.

RESULTS

One hundred eighteen TSAs in 111 patients were identified. Mean age was 64.9 years (range, 39-90) and 65% of patients were male. Ninety-four (80%) and 24 (20%) patients underwent outpatient and inpatient procedures, respectively. Four complications (3.4%) were recorded: axillary nerve stretch injury, isolated ipsilateral arm deep venous thrombosis (DVT), ipsilateral arm DVT with pulmonary embolism requiring readmission, and gastrointestinal bleed requiring readmission. There were no reoperations or other complications. Outpatients were younger with lower ASA and CCI scores than inpatients; however, there was no difference in complications (1/24 vs. 3/94, P=1.00) or readmissions (1/24 vs. 1/94, P=0.37) between these two groups.

CONCLUSIONS

TSA with a nonspherical humeral head and inlay glenoid can be performed safely in both inpatient and outpatient settings. Rates of early complications and readmissions were low with no difference according to surgical setting. Level of evidence: IV.

Secondary Rotator Cuff Insufficiency After Anatomic Total Shoulder Arthroplasty

» Secondary rotator cuff insufficiency is a challenging complication after anatomic total shoulder arthroplasty.» Acute tears may be amenable to open or arthroscopic repair in some instances.» Chronic attritional tears are best managed with revision to reverse shoulder arthroplasty, especially in the elderly.» Increased glenoid inclination, larger critical shoulder angle, oversized humeral components, thicker glenoid components, and rotator cuff muscle fatty infiltration have all shown to contribute to tear risk.

A survey and biomechanical analysis of the feasibility of the thumb test for determining the cancellous bone quality for stemless shoulder prosthesis

BACKGROUND

The effect of the thumb test for assessing the cancellous bone quality at the resection plane of the proximal humerus on determining the application of a stemless shoulder prosthesis remains unclear. This study was conducted to survey the current utilization of the thumb test among surgeons and to investigate biomechanical features of the thumb test.

METHOD

A survey among shoulder surgeons who had experience with stemless prostheses was conducted to investigate the current utilization of preoperative assessments and intraoperative thumb test when applying stemless prosthesis. Biomechanical experiments for the thumb test using artificial bone models were performed to assess the compression force, contact pressure and area. According to the preliminary survey, three compression techniques were assessed: compression perpendicular to the surface with thumb pad (P-pad technique) or tip of the thumb (P-tip technique), or compression in the vertical direction simulating compression along the longitudinal axis of the humeral shaft with tip-pad of the thumb (H-axis technique). The contact area was separated into three subregions (proximal, middle and distal) to assess the distribution of contact pressure.

RESULTS

Among 38 surgeons, 66% utilized the thumb test intraoperatively. The P-pad technique was more frequently applied than the P-tip or H-axis techniques (80%, 4% and 16%, respectively). Although with wide variation among the examiners, biomechanical assessments revealed the P-pad technique showed larger contact area and less compression force than the P-tip technique. The P-pad technique provided no significant localized differences in the mean contact pressure on the compressed plane, whereas the P-tip and H-axis techniques showed significant differences among subregions.

CONCLUSION

This survey demonstrated relatively frequent application of the thumb test on applying the stemless shoulder prosthesis. Biomechanical assessment revealed the thumb test can hinder objective reproducibility among examiners; therefore, further investigations to identify feasible assessments of the bone quality is required.

The effect of shoulder prosthesis stem length on failure due to torsional loading. A biomechanical study in composite humeri

Background

Shoulder arthroplasty is becoming increasingly common. With evolving implant designs, multiple humeral stem options exist for the surgeon to choose from. New stemless and short-stem systems are modular, remove less native bone stock, and better adapt to patient anatomy. It has been suggested that shorter stem implants may be protective against periprosthetic fracture; however, this has not been mechanistically evaluated. Therefore, this study aimed to biomechanically test synthetic humeri with long-stem, short-stem, and stemless arthroplasty components in a torsional manner to evaluate their response to loading and characterize failure.

Methods

Twenty-four synthetic humeri were implanted with long stem, short stem, or stemless uncemented prosthesis, 8 in each group. Humeri were mounted in a custom testing jig with a morse taper interfacing with a mechanical testing system. After a 20N axial force, specimens were torsionally loaded to failure at 15 degrees/sec, with 50 Hz collection. Torque vs. rotation curves were generated for each specimen, and stiffness, yield, ultimate strength, and failure load were measured. ANOVA and post hoc pairwise comparisons were used to assess effect of stem type on mechanical test variable. The association of the stem type with fracture type was analyzed by a Fisher's Exact test. Statistical significance was set at P < .05.

Results

During torsional loading, long-stem implants were significantly stiffer than short or stemless implants. The angle of implant yielding was similar across stem designs; however, stemless implants had a lower yield torque. This correlated with a decreased yield energy in stemless compared to short stems as well. Maximum torque and failure torque was also significantly higher in short-stem and long-stem implants compared to stemless.

Discussion

Periprosthetic fractures in shoulder arthroplasty are a concern in low-energy trauma, and stem design likely plays a significant role in early implant-bone failure. Our results suggest stemless implants under torsional load fail at lower stress and are less stiff than stemmed implants. The failure mechanism of stemless implants through metaphyseal cancellous bone emphasizes the effect bone quality has on implant fixation. There is likely a balance of torsional stability to survive physiologic loads while minimizing diaphyseal stress and risk of diaphyseal periprosthetic fracture. This combined with revision and fixation options represent decisions the surgeon is faced with when performing shoulder arthroplasty.

Stress shielding following stemless anatomic total shoulder arthroplasty

Background

Finite element analysis has suggested that stemless implants may theoretically decrease stress shielding. The purpose of this study was to assess the radiographic proximal humeral bone adaptations seen following stemless anatomic total shoulder arthroplasty.

Methods

A retrospective review of 152 prospectively followed stemless total shoulder arthroplasty utilizing a single implant design was performed. Anteroposterior and lateral radiographs were reviewed at standard time points. Stress shielding was graded as mild, moderate, and severe. The effect of stress shielding on clinical and functional outcomes was assessed. Also, the influence of subscapularis management on the occurrence of stress shielding was determined.

Results

At 2 years postoperatively, stress shielding was noted in 61 (41%) shoulders. A total of 11 (7%) shoulders demonstrated severe stress shielding with 6 occurring along the medial calcar. There was one instance of greater tuberosity resorption. At the final follow-up, no humeral implants were radiographically loose or migrated. There was no statistically significant difference in clinical and functional outcomes between shoulders with and without stress shielding. Patients undergoing a lesser tuberosity osteotomy had lower rates of stress shielding, which was statistically significant (p = 0.021).

Discussion

Stress shielding does occur at higher rates than anticipated following stemless total shoulder arthroplasty, but was not associated with implant migration or failure at 2 years follow-up.

Level of evidence

IV, Case series.

Lesser Tuberosity Osteotomy Healing in Stemmed and Stemless Anatomic Shoulder Arthroplasty Is Higher with a Tensionable Construct and Affected by Body Mass Index and Tobacco Use

BACKGROUND

This study compared the healing rates of lesser tuberosity osteotomy (LTO) for anatomic total shoulder arthroplasty (TSA), repaired with either standard knot tying or a tensionable construct. Second, we evaluated LTO healing in stemmed and stemless prostheses and identified the patient characteristics associated with healing.

METHODS

An analysis of consecutive primary TSAs approached with an LTO performed by a single surgeon between 2016 and 2020 was conducted. In the first two years of the study period, the LTOs were repaired with four #2 polyblend sutures passed through drill tunnels and around a short press-fit stem, followed by manual knot tying. Subsequently, a tensionable construct with suture tapes (TCB) was universally adopted. The radiographic appearance of the LTO was evaluated at a minimum of six months postoperatively.

RESULTS

A total of 340 patients met the study criteria, including 168 with manual knot tying, 84 TCB repairs with a stemmed implant, and 88 TCB repairs with a stemless implant. There was no difference in the baseline demographics between the groups. The LTO healing rate of the manual knot tying group (85%) was lower than that of the stemmed (95%) and stemless (98%) TCB groups (p < 0.001). When directly comparing the LTO healing between the stemmed and stemless TCB groups, the differences were not significant (p = 0.44). Across all constructs, the body mass index (BMI) was higher in the displaced nonunion group (p = 0.04), with a failure rate of 9.4% for a BMI between 30 and 40, 12.5% for a BMI between 40 and 50, and 28.6% for a BMI > 50. The rate of tobacco use was higher in the displaced nonunion group (p = 0.037).

CONCLUSION

A tensionable construct improves LTO healing compared to manual knot tying, irrespective of the implant type. In addition to the surgical technique, the patient factors that influence tuberosity healing include a greater BMI and tobacco use.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Simple preoperative radiographic and computed tomography measurements predict adequate bone quality for stemless total shoulder arthroplasty

INTRODUCTION

Although there is increased utilization of stemless humeral implants in anatomic total shoulder arthroplasty (TSA), there are inadequate objective metrics to evaluate bone quality sufficient for fixation. Our goals are to: (1) compare patient characteristics in patients who had plans for stemless TSA but received stemmed TSA due to intraoperative assessments and (2) propose threshold values of bone density, using the deltoid tuberosity index (DTI) and proximal humerus Hounsfield units (HU), on preoperative X-ray and computed tomography (CT) to allow for preoperative determination of adequate bone stock for stemless TSA.

METHODS

This is an observational study conducted at an academic institution from 2019 to 2021, including consecutive primary TSAs templated to undergo stemless TSA based on 3-dimensional CT preoperative plans. Final implant selection was determined by intraoperative assessment of bone quality. Preoperative X-ray and CT images were assessed to obtain DTI and proximal humeral bone density in HU, respectively. A receiver operating characteristic curve was used to analyze the potential of preoperative X-ray and CT to classify patients as candidates for stemless TSA.

RESULTS

A total of 61 planned stemless TSAs were included, with 56 (91.8%) undergoing stemless TSA and 5 (8.2%) undergoing stemmed TSA after intraoperative assessment determined that the bone quality was inadequate for stemless fixation. There were no significant differences between the 2 groups in terms of gender (P = .640), body mass index (P = .296), and race (P = .580). The stem cohort was significantly older (mean age 69 ± 12 years vs. 59 ± 10 years, P = .029), had significantly lower DTI (1.45 ± 0.13 vs. 1.68 ± 0.18, P = .007), and had significantly less proximal humeral HU (-1.4 ± 17.7 vs. 78.8 ± 52.4, P = .001). The receiver operating characteristic curve for DTI had an area under the curve (AUC) of 0.86, and bone density in HU had an AUC of 0.98 in its ability to distinguish patients who underwent stemless TSA vs. short-stem TSA. A threshold cutoff of 1.41 for DTI resulted in a sensitivity of 98% and a specificity of 60%, and a cutoff value of 14.4 HU resulted in a sensitivity of 95% and a specificity of 100%.

CONCLUSIONS

Older age, lower DTI, and less proximal humeral bone density in HU were associated with the requirement to switch from stemless to short-stem humeral fixation in primary TSA. Preoperative DTI had good ability (AUC of 0.86) and preoperative HU had excellent ability (AUC of 0.98) to categorize patients as appropriate for stemless TSA. This can help surgeons adequately plan humeral fixation using standard preoperative imaging data.

Midterm results of stemless impaction shoulder arthroplasty for primary osteoarthritis: a prospective, multicenter study

Background

Stemless shoulder arthroplasty using 4 open-fin press-fit anchors has been showing promising short-term clinical and radiographic results for patients' primary osteoarthritis. This prospective, multicenter study presents 5-year postoperative clinical and radiological outcomes of a stemless shoulder arthroplasty for primary osteoarthritis.

Methods

Between November 2012 and December 2015, 100 patients were treated for primary osteoarthritis with the Sidus stem-free shoulder system at 7 European centers. Clinical assessment included the Constant-Murley Score, American Shoulder and Elbow Standardized Shoulder Assessment Form score, Subjective Shoulder Value, and range of motion. True anteroposterior, axial and lateral radiographs were reviewed for osteolysis, glenoid and humerus loosening, heterotopic ossification, radiolucent lines, component migration and humeral bone resorption. In addition to a Kaplan-Meier survival analysis, a comparative analysis between total shoulder arthroplasty and hemiarthroplasty was performed.

Results

Seventy-one patients (36 females) with a mean age of 63.8 years (range: 47-79 years) were available for the 5-year clinical and radiographic follow-up (range: 52-79 months). There was a significant increase (P < .0001) in all outcome scores compared to baseline values. Patients with total shoulder arthroplasty (n = 48) achieved significantly better functional outcome than patients with shoulder hemiarthroplasty (n = 23) with regard to the absolute and relative Constant-Murley Score, American Shoulder and Elbow Standardized Shoulder Assessment Form score, and Subjective Shoulder Value as well as greater abduction strength and range of motion in forward elevation and external rotation (P ≤ .004). There were no cases of osteolysis or humeral loosening. There were some cases of heterotopic ossification (1.4%), radiolucency around the humerus (1.4%) or glenoid (25%), glenoid migration (2.1%), inferior osteophytes (1.4%) or humerus bone resorption (9.9%). The 5-year survival was 94%.

Conclusion

Patients treated with the Sidus stem-free shoulder system for primary osteoarthritis continue to achieve good clinical and radiographic results without any signs of aseptic humeral implant loosening at 5 years postsurgery.

Short-term results of a new anatomic stemless shoulder arthroplasty - A prospective multicentre study

Background

Anatomic total shoulder arthroplasty (TSA) has been continuously developed and current designs include stemless or canal-sparing humeral components. In the literature stemless and canal sparing TSA showed good clinical and radiographic results, which were comparable to stemmed TSA.

Objective

The aim of this study was to determine the short-term clinical and radiological outcomes of a new stemless TSA design.

Methods

A prospective multicentre study including 154 total shoulder arthroplasty patients with a follow up of 12 months was performed. At the time of follow up 129 patients were available for review. The adjusted Constant Murley score,¹ Oxford Shoulder Score, EQ-5D-5L score and radiographs were examined preoperatively, 3 and 12 months after the implantation of the new stemless TSA implant GLOBAL ICON™ (DePuy Synthes, Warsaw, IN, USA). Complications were documented.

Results

Implant Kaplan-Meier survivorship was 98.7% at 12 months. From baseline to 12 months follow-up, all scores showed a progressive significant mean improvement. The mean adjusted Constant score increased from 42.3 to 96.1 points (p<0.001). The Oxford Shoulder Score showed an increase of 21.6 points (p<0.001). The postoperative radiographs showed no continuous radiolucent lines, subsidence, aseptic loosening or progressive radiolucency, but one osteolytic lesion was observed. Only 2 prostheses were revised.

Conclusion

The new GLOBAL ICON stemless TSA showed good clinical and radiographic results at short-term follow up which were comparable to early results of other stemless TSA. Further studies with longer follow up are needed in the future.

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.

Lesser Tuberosity Osteotomy Does Not Appear to Compromise Fixation or Function Compared With Peel in Short-Stem Anatomic Shoulder Arthroplasty

Several methods are available for subscapularis management in total shoulder arthroplasty (TSA). The goal of this study was to compare radiographic and clinical outcomes of short-stem TSA stratified by subscapularis management technique. A multicenter trial was completed evaluating primary short-stem TSA performed with a subscapularis peel (n=80) or lesser tuberosity osteotomy (LTO) (n=59). The primary outcome measure was subscapularis function, as measured by internal rotation and strength at 1 year postoperatively. Secondary outcomes included patient-reported outcomes, radiographic changes, and implant loosening. Patients in the peel group obtained better active internal rotation by spinal level (P=.004). No difference was seen between groups for internal rotation with 90° shoulder abduction (P=.862) or belly press (P=.903). Statistically significant improvements in functional outcomes were seen without clinical differences. Radiographic changes showed no difference in stem shift, subsidence, or at-risk loosening rate. Anterior subluxation of the humerus was observed among 2% of the LTO group vs 17% of the peel group (P=.006). At short-term follow-up, those in the peel group appear to have a better final spinal level of internal rotation, whereas those in the LTO group have a significantly lower rate of anterior humeral subluxation. Both LTO and subscapularis peel appear safe for short-stem TSA, with no radiographic evidence of loosening. [Orthopedics. 2022;45(3):151-155.].

Assessment of intraoperative bleeding in reverse shoulder arthroplasty - with or without a stem

INTRODUCTION

The functional results of stemless reverse shoulder prostheses are similar to those with stems. However, the operative time and the bleeding appear less significant because of the absence of humeral reaming. To date, the data amongst the literature regarding this subject is limited. Thus, we report a retrospective evaluation on these 2 types of prostheses by assessing their respective intraoperative blood loss.

HYPOTHESIS

Reverse shoulder arthroplasty without a stem leads to less blood loss, compared to arthroplasty with a stem.

MATERIALS AND METHODS

Twenty-three patients underwent an operation for a stemless prosthesis, while 37 patients had a prosthesis with a stem. The hemoglobin was measured preoperatively, as well as postoperatively. Drainage of the operative site was maintained for two to three days. In the stem group, the preoperative hemoglobin was 14g/dL (11.7-16.6), while it was 13.1g/dL (11-15.8) in the stemless group.

RESULTS

The intraoperative bleeding reached 223cm³ (80-530), with an operative duration of 81minutes (40-110) in the stemless group, compared to 260cm³ (50-1000) and 92minutes (33-110) in the stem group. On the first day postoperatively, 333cm³ (20-570) of blood had been collected by drainage for the stemless group, compared to 279cm³ (40-550) in the stem group. The amount decreased the second day, with 139cm³ (20-510) and 129cm³ (0-750) respectively. There was no difference between the two groups regarding the postoperative hemoglobin level (11g/dL).

DISCUSSION

There is no significant difference concerning the blood loss between reverse shoulder replacements with and without stems.

LEVEL OF EVIDENCE

III Retrospective case control study.

Stemless reverse total shoulder arthroplasty: a systematic review

BACKGROUND

The use of reverse total shoulder arthroplasty and stemless anatomic total shoulder replacement has been increasing in the United States every year. Stemless humeral components in reverse total shoulder arthroplasty are only approved for clinical trials in the United States with an investigational device exception with limited data.

METHODS

A systematic review on stemless reverse total shoulder arthroplasty was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A search was conducted on November 25, 2020, using the MEDLINE/PubMed, Cochrane, and Embase databases. All articles were reviewed by 2 independent evaluators, with any conflicts or issues resolved by consensus or a final decision by the senior author. The primary outcomes extracted were complications, radiographic results, and outcome scores.

RESULTS

We evaluated 10 studies that used either the Total Evolutive Shoulder System (TESS) or Verso implant. There were 430 total patients and 437 total procedures; 266 patients in the TESS group underwent a total of 272 procedures, and 164 patients in the Verso group underwent a total of 165 procedures. The mean age at the time of surgery was 73.8 years (range, 38-93 years). The mean follow-up period ranged from 6.4 to 101.6 months per study. There was an overall trend of improved clinical outcome scores, a 0.2% humeral component loosening rate, and an 11.2% complication rate.

CONCLUSIONS

This review shows that the clinical and functional outcomes following stemless or metaphyseal reverse total shoulder arthroplasty are quite promising, especially with the low rate of humeral-sided complications. There continues to be a need for additional long-term studies and randomized clinical trials.

A biomechanical comparison of subscapularis tenotomy repair techniques for stemless shoulder arthroplasty

BACKGROUND

One of the leading challenges for surgeons shifting to stemless anatomic total shoulder arthroplasty (TSA) is subscapularis repair. In the available literature reporting outcomes after stemless TSA, subscapularis tenotomy with side-to-side repair is the most common technique despite some concerns regarding this technique in the biomechanical and clinical literature. Accordingly, this study investigated subscapularis tenotomy repair with stemless TSA with 2 primary objectives: (1) to evaluate the subscapularis tendon dimensions with reference to subscapularis tenotomy to determine the amount of tendon remaining for side-to-side repair after shoulder arthroplasty and (2) to biomechanically compare 2 methods of subscapularis tenotomy repair after stemless TSA-side-to-side repair and anchor-based repair.

METHODS

We used 12 male shoulder specimens for this study. To address our first objective, measurements were made to calculate the dimensions of the subscapularis tendon at the superior, middle, and inferior levels to determine the amount of tendon remaining after tenotomy. These specimens were then divided into 2 groups (n = 6 in each group) to biomechanically compare subscapularis tenotomy repair with (1) traditional side-to-side repair and (2) anchor-based repair. The shoulders then underwent biomechanical testing with primary outcomes including load to failure and cyclic displacement.

RESULTS

The mean subscapularis tendon width measured from the medial insertion at the lesser tuberosity to the muscle-tendon junction varied depending on the level: 19.5 mm superiorly (95% confidence interval [CI], 16.2-22.8 mm); 18.3 mm at the midportion (95% CI, 13.6-23.0 mm); and 13.1 mm inferiorly (95% CI, 9.1-17.1 mm). With a tenotomy made 1 cm medial to the lesser tuberosity insertion, a mean of 3.1 mm of tendon remained medially at the inferior subscapularis, with one-third of specimens having no tendon left medially at this level. On comparison of tenotomy repair techniques, the anchor-based technique had a 57% higher ultimate load to failure compared with the side-to-side repair (448 N vs. 249 N, P < .001). There were no significant differences in cyclic displacement (6.1 mm vs. 7.1 mm, P = .751) and construct stiffness (38.1 N/mm vs. 42.9 N/mm, P = .461) between techniques.

CONCLUSIONS

With traditional techniques for subscapularis tenotomy for anatomic TSA, there is very little tendon remaining inferiorly for side-to-side repair. When subscapularis tenotomy is performed for stemless TSA, a double-row anchor-based repair has a better time-zero ultimate load to failure compared with side-to-side repair.

Clinical and radiological outcomes of a stemless reverse shoulder implant: a two-year follow-up in 56 patients

Background

Since the introduction of stemless anatomic shoulder arthroplasty, many studies have been published on anatomic implants. For reverse stemless implants, however, there are only a few clinical follow-up studies available. The current clinical case series aims to present clinical and radiological outcomes of a new stemless reverse prosthesis system (Lima Shoulder Modular Replacement stemless).

Methods

We prospectively evaluated the outcome of 56 stemless total shoulder arthroplasties in 56 patients with a mean age of 61.2 years (46-76 years) at the time of implantation at a minimum follow-up of 24 months (range 24-41 months). All patients were physically and radiologically examined. Clinical outcomes were evaluated by using the Constant-Murley Score and the Subjective Shoulder Value.

Results

The mean Subjective Shoulder Value was 84.27% at the latest follow-up. Significant improvements from preoperative to latest follow-up were documented for Constant-Murley Score (34.9 pts to 74.43 pts, P < .001) and active range of motion (abduction 72° to 130°, flexion 36° to 138°, and external rotation 16°to 28°). There was one complete loosening of the humeral component without reoperation. Radiolucency lines were observed in anteroposterior or axial radiographs at the humeral component in 23% of the cases, most of them in anteroposterior view at the calcar region. Radiolucency line findings did not affect clinical outcomes. Major complications or revisions did not occur so far.

Conclusion

At short-term follow-up, stemless reverse shoulder systems show comparable clinical and radiological outcomes compared to stemmed reverse implants in the literature.

Biomechanical evaluation of 2 techniques of repair after subscapularis peel for stemless shoulder arthroplasty

BACKGROUND

Stemless anatomic total shoulder arthroplasty (TSA) has been gaining significant popularity but poses unique challenges for subscapularis repair. Tenotomy with side-to-side repair has been the most frequently reported technique for subscapularis repair with stemless TSA but has the poorest biomechanical properties, and clinical failures have been reported. There is limited biomechanical evidence evaluating other subscapularis repair techniques for stemless TSA. Therefore, the goal of this study was to investigate 2 additional techniques using a subscapularis peel for subscapularis repair with a stemless TSA.

METHODS

We used 18 male cadaveric specimens to investigate the native subscapularis (n = 6) and 2 subscapularis repair techniques (n = 12) after stemless anatomic TSA (Eclipse). A subscapularis peel with double-row, knotless anchor-based repair (n = 6) was compared with a subscapularis peel with a "backpack" repair (n = 6). The specimens then underwent biomechanical testing, including cyclic displacement and load-to-failure testing. The mode of failure was also recorded.

RESULTS

The native tendon had the highest ultimate load to failure (mean, 1017.1 N). Load to failure was similar between the 2 study groups: 397.9 N for the peel and backpack repair and 593.7 N for the knotless anchor-based repair (P > .05 for all comparisons). Moreover, no significant differences in cyclic displacement or construct stiffness were found between the groups (P > .05 for all comparisons).

CONCLUSIONS

A double-row, knotless anchor-based repair of a subscapularis peel for stemless anatomic shoulder arthroplasty has similar biomechanical properties to a backpack repair technique; however, both techniques fail to reproduce the native biomechanical properties at time zero.

Radiological humeral adaptative changes five years after anatomical total shoulder arthroplasty using a standard-length cementless hydroxyapatite-coated humeral component

AIMS

The purpose of this study was to report bone adaptive changes after anatomical total shoulder arthroplasty (TSA) using a standard-length hydroxyapatite (HA)-coated humeral component, and to report on a computer-based analysis of radiographs to determine changes in peri-implant bone density objectively.

METHODS

A total of 44 TSAs, performed between 2011 and 2014 using a cementless standard-length humeral component proximally coated with HA, were included. There were 23 males and 21 females with a mean age of 65 years (17 to 65). All shoulders had good quality radiographs at six weeks and five years postoperatively. Three observers graded bone adaptive changes. All radiographs were uploaded into a commercially available photographic software program. The grey value density of humeral radiological areas was corrected to the grey value density of the humeral component and compared over time.

RESULTS

Stress shielding was graded as mild in 14 shoulders and moderate in three; the greater tuberosity was the predominant site for stress shielding. The mean metaphyseal and diaphyseal fill-fit ratios were 0.56 (SD 0.1) and 0.5 (SD 0.07), respectively. For shoulders with no radiologically visible stress shielding, the mean decrease in grey value in zones 1 and 7 was 20%, compared with 38% in shoulders with radiologically visible stress shielding.

CONCLUSION

The rate of moderate stress shielding was 7%, five years after implantation of a cementless standard-length HA-coated humeral component. Clinical observation of stress shielding identified on radiographs seems to represent a decrease in grey value of 25% or more. Cite this article: Bone Joint J 2021;103-B(5):958-963.

An update on reverse total shoulder arthroplasty: current indications, new designs, same old problems

Reverse total shoulder arthroplasty (RTSA) was originally developed because of unsatisfactory results with anatomic shoulder arthroplasty options for the majority of degenerative shoulder conditions and fractures.

After initial concerns about RTSA longevity, indications were extended to primary osteoarthritis with glenoid deficiency, massive cuff tears in younger patients, fracture, tumour and failed anatomic total shoulder replacement.

Traditional RTSA by Grammont has undergone a number of iterations such as glenoid lateralization, reduced neck-shaft angle, modular, stemless components and onlay systems.

The incidence of complications such as dislocation, notching and acromial fractures has also evolved.

Computer navigation, 3D planning and patient-specific implantation have been in use for several years and mixed-reality guided implantation is currently being trialled.

Controversies in RTSA include lateralization, stemless humeral components, subscapularis repair and treatment of acromial fractures.

Cite this article: EFORT Open Rev 2021;6:189-201. DOI: 10.1302/2058-5241.6.200085

Primary reverse shoulder replacement with a short stem: A systematic literature review

Background

Total shoulder arthroplasty implant designs have continued to evolve over the years. One recent change has been the shortening of the humeral component to preserve bone stock and to facilitate revision surgery. Despite promising clinical results, radiographic bone adaptions occur frequently in short-stem total shoulder arthroplasty, and limited data exist on short-stem reverse shoulder arthroplasty (RSA). The purpose of this systematic review was to provide an overview about the functional and radiographic outcomes after an uncemented short-stem RSA, as well as identify areas of clinical importance that are underreported in the current literature.

Methods

A systematic review of the literature was performed in accordance with the PRISMA guidelines using PubMed, Cochrane Central Register of Controlled Trials, and EMBASE. Clinical outcome studies reporting on short-stem RSA outcomes with evidence level I-IV were included. Demographics, clinical and radiological outcomes, as well as complications and revision data were systematically analyzed and described.

Results

Ten studies, published between 2014 and 2019, reporting on 555 shoulders with a mean follow-up of 32 months (range, 20-99.6 months) met the inclusion criteria. For all studies cuff tear arthropathy was the main indication for RSA (36%), followed by primary osteoarthritis (20%). Clinical outcome was reported in nine of ten studies, with range of motion improving in all studies. Six of the seven studies that used the Constant score (CS) demonstrated significant improvement (27.9 points to 69.3 points in weighted means). All studies reported on radiographic changes and bone adaptions. Among these, scapular notching was the most commonly observed (60 out of 327 cases, 18%) but without any described implication on clinical outcomes. No stem loosening was recorded at any final follow-up. A total of 63 complications (12.9%) were reported, with scapula fractures being the most commonly reported complication. Revision surgery was necessary in 24 cases (4.9%).

Conclusion

Good clinical results, comparable with long-stem RSAs, are reported at short-term follow-up for short-stem RSAs. Humeral bone adaptions occur frequently but aseptic stem loosening is not a matter of concern at short-term follow-up. An area of clinical importance that is under-reported is the relation between filling ratio and stem alignment in short-stem RSA.

Stemless Total Shoulder Arthroplasty With Orthobiologic Augmentation

Total shoulder arthroplasty (TSA) has evolved over the years and is used for a variety of indications, with arthritis being the most common. Stemless TSA is a unique bone-preserving design that can eliminate rotational malalignment. Additionally, recent literature has found utility in the use of biological mesh and a platelet-rich plasma injection to improve healing. The purpose of this article is to outline the process of TSA using a stemless system and how to incorporate the use of amnion matrix and platelet-rich plasma into the surgical technique.

Clinical results and survivorship of the Mathys Affinis Short, Short Stem Total Shoulder Prosthesis

AIMS

The Mathys Affinis Short is the most frequently used stemless total shoulder prosthesis in the UK. The purpose of this prospective cohort study is to report the survivorship, clinical, and radiological outcomes of the first independent series of the Affinis Short prosthesis.

METHODS

From January 2011 to January 2019, a total of 141 Affinis Short prostheses were implanted in 127 patients by a single surgeon. Mean age at time of surgery was 68 (44 to 89). Minimum one year and maximum eight year follow-up (mean 3.7 years) was analyzed using the Oxford Shoulder Score (OSS) at latest follow-up. Kaplan-Meier survivorship analysis was performed with implant revision as the endpoint. Most recently performed radiographs were reviewed for component radiolucent lines (RLLs) and proximal humeral migration.

RESULTS

Five shoulders underwent revision surgery (3.5%); three for rotator cuff failure, one for infection, and one for component malposition. Survivorship of the implant was 95.4% (95% confidence interval 90.1% to 97.9%) at five and nine years. Mean OSS improved significantly compared to preoperative values from 19.0 (1 to 35) to 43.3 (7 to 48) (p < 0.001). Radiological analysis was undertaken for 99 shoulders. This revealed humeral RLLs in one case (1%), glenoid RLLs in 15 cases (15.2%), and radiological rotator cuff failure in 22 cases (22.2%).

CONCLUSION

This prospective cohort study shows encouraging short- to mid-term survivorship and clinical and radiological results for the Mathys Affinis Short, Short Stem Total Shoulder Prosthesis.Level of Evidence: IVCite this article: Bone Jt Open 2021;2(1):58-65.

Stemless anatomic total shoulder arthroplasty: a systematic review and meta-analysis

BACKGROUND

Stemless anatomic total shoulder arthroplasty (TSA) is used in the treatment of osteoarthritis of the shoulder joint and other degenerative shoulder diseases. It has several proposed advantages over stemmed TSA including increased bone preservation, decreased operative time, and easier removal at revision.

METHODS

A systematic search was conducted using MEDLINE, Embase, PubMed, and CENTRAL (Cochrane Central Register of Controlled Trials) to retrieve all relevant studies.

RESULTS

The literature search yielded 1417 studies, of which 22 were included in this review, with 962 patients undergoing stemless TSA. Stemless TSA led to significant improvements in range of motion and functional scores in all included studies. Meta-analysis of comparative studies between stemless and stemmed TSA identified no significant differences in postoperative Constant scores (mean difference [MD], 1.26; 95% confidence interval [CI], -3.29 to 5.81 points; P = .59) or complication rates (odds ratio, 1.79; 95% CI, 0.71-4.54; P = .22). Stemless TSA resulted in a significantly shorter operative time compared with stemmed TSA (MD, -15.03 minutes; 95% CI, -23.79 to -6.26 minutes; P = .0008). Stemless TSA also resulted in significantly decreased intraoperative blood loss compared with stemmed TSA (MD, -96.95 mL; 95% CI, -148.53 to -45.36 mL; P = .0002).

CONCLUSION

Stemless anatomic TSA resulted in similar functional outcomes and complication rates to stemmed TSA with decreased operative time and lower blood loss. Further research is required to investigate the long-term durability of the stemless implant.

Current concept of shoulder replacement arthroplasty

Since the development of the first anatomic shoulder replacement in 1950, the technology has undergone substantial evolution, making it a viable option to manage variable shoulder problems, including severe osteoarthritis, rheumatoid arthritis, and fracture of the proximal humerus. However, the design of conventional total shoulder arthroplasty prostheses does not account for concomitant musculotendinous pathologies, including larger rotator cuff tears, which are associated with fatty infiltration of the infraspinatus muscle and substantially compromise the outcome of total shoulder arthroplasty. For patients without a rotator cuff or with rotator cuff tear arthropathy, hemiarthroplasty was the conventional treatment. Unfortunately, for these indications, hemiarthroplasty may provide little improvement in range of motion or function. Recently, radical changes in prosthetic design were made that transformed poorly performing reverse ball-and-socket total shoulder prosthesis into a highly successful salvage implant for pseudoparalytic and severe rotator cuff–deficient shoulders. The annual number of reverse total shoulder arthroplasties is increasing dramatically, and the indications also have expanded to include several conditions. In this review, the current concept of variable shoulder arthroplasty is discussed for clinical physicians.

Outcomes of reverse shoulder arthroplasty using a short stem through a superolateral approach

BACKGROUND

Reverse shoulder arthroplasties have progressed in recent decades to become the most popular type of arthroplasty. Short stems with metaphyseal fixation have been developed to preserve bone stock and facilitate possible revision. Accurate positioning of these implants can be challenging using the superolateral approach.

OBJECTIVE

This study aimed to evaluate the clinical and radiologic results of reverse short-stem arthroplasties using a superolateral approach with a minimum of 2 years' follow-up.

METHODS

Between January 2015 and December 2016, a total of 76 patients underwent reverse shoulder arthroplasty surgery (79 shoulders) using a short uncemented humeral stem for shoulder arthritis with irreparable rotator cuff tear. Arthroplasties for post-traumatic osteoarthritis were excluded. Functional outcomes were assessed using Constant Score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), visual analog scale (VAS), and range of motion. Radiographic analysis was used to evaluate component loosening, implant position, and implant filling ratio.

RESULTS

The mean age was 70.8 years. At a mean of 38.8-month follow-up, there were significant improvements in Constant score (44.2 to 87.9, P < .001), ASES score (36.2 to 84.3, P < .001), and VAS score (6.8 to 0.4, P < .001). Forward flexion improved from 89°to 131°(P < .001), and external rotation improved from 25° to 36°(P < .001). No evidence of periprosthetic loosening was visible. Mean varus of the humeral stem was 1°(±6°). The mean glenoidal inclination was 98°(±7°), which corresponds to a lower tilt of 8°. The average filling ratio was between 50% and 60% in both the metaphysis and the diaphysis.

CONCLUSION

The clinical results obtained in this study were satisfying, with a significantly low complication rate. Hence, short-stem reverse shoulder arthroplasty using a superolateral approach, while taking particular care to protect the deltoid, remains our method of choice.

Stemless Humeral Implants in Total Shoulder Arthroplasty

Through an iteration of various advancements, both short stem and stemless options for humeral fixation have been proposed and have shown clinical promise. The proposed benefits of a stemless humeral implant include greater bone preservation, less stress shielding, less risk of a diaphyseal stress riser, decreased surgical time, and less intraoperative blood loss. Potential downsides include the dependence on proximal bone quality for fixation, increased cost, the dependence on the strength of subscapularis fixation, and pending FDA approval for multiple implants. The purpose of this article is to review the evidence behind stemless implants including the biomechanical advantages and disadvantages, surgical technique, and clinical outcomes.

Do the radiological changes seen at mid term follow up of stemless shoulder prosthesis affect outcome?

Background

The Eclipse® (Eclipse® is a trademark of Arthrex, Naples, Florida) stemless shoulder prosthesis offers the surgeon the advantage of bone stock preservation and at the same time avoids the drawbacks of a resurfacing arthroplasty. Previous studies have shown radiographic changes on serial follow up of the Eclipse prosthesis. This study attempts to assess the significance of these radiographic changes and effect of cuff related pathology on the mid-term outcome of the Eclipse prosthesis.

Methods

Between July 2005 and October 2008, 29 shoulders underwent shoulder arthroplasty with the Eclipse prosthesis; 23 shoulders, (seven women and 16 men) were available for the final follow up. The range of motion, Constant Score; age adjusted Constant Score, Subjective Shoulder Value and radiographs were assessed at serial follow-ups.

Results

Significant improvements were seen in the Constant Score (78.9 ±20.1) compared to pre-operative score (32.9 ±5.2); also forward elevation, abduction and external rotation improved to 142.9 ± 36.6 °, 135.2 ± 40.5 ° and 49.8 ± 21.9 ° at 72 months (p < 0.001). Radiolucent lines and localised osteopenia, did not statistically impact on the clinical outcome. Partial tears of the supraspinatus and subscapularis had a negative impact on the Subjective Shoulder Value (p < 0.05) Partial or complete tears of the subscapularis led to worse Constant Score on follow up (p < 0.05).

Conclusions

The presence of radiolucent lines or localised osteopenia does not influence the mid term clinical outcome. Pre -operative partial supraspinatus tears or tears of the subscapularis lead to an inferior outcome.

Stemless shoulder arthroplasty: review of short and medium-term results

Background

The number of anatomic total shoulder (TSA), hemiarthroplasty (HA), and reverse total shoulder arthroplasties (RTSA) is rapidly increasing in the United States. Stemless shoulder arthroplasty has numerous theoretical advantages, including preserved bone stock, decreased operating time, reduced rate of intraoperative humerus fracture, and flexibility of anatomic reconstruction. Only recently studies with more than 5 years of mean follow-up have become available.

Methods

The MEDLINE database was systematically queried to identify all studies reporting outcomes regarding anatomic or reverse stemless shoulder arthroplasty. Studies were categorized according to mean reported follow-up. Outcome scores and range of motion measurements were compiled. Complication and revision rates due to failure of the humeral or glenoid components were summarized.

Results

Nineteen TSA and HA studies with a total of 1115 patients were identified, with 4 studies and 162 patients with a mean follow-up between 60 and 120 months. Six RTSA studies with a total of 346 patients were identified, all with a mean follow-up between 18 and 60 months. There was a reliable improvement in outcomes compared with preoperative scores across studies. A cumulative 0.7% (8 of 1115) humeral component complication rate was found for TSA and HA components. There was a cumulative 1.7% (6 of 346) humeral complication rate for RTSA prostheses.

Conclusions

In the studies reporting similar outcome measures, there were reliable improvements on par with stemmed counterparts. Aggregate complication rates appear similar to those published in the literature for stemmed components. Evidence supporting the utility and safety of stemless designs would be strengthened by longer-term follow-up and additional prospective comparative studies.

Does proximal porous coating in short-stem humeral arthroplasty reduce stress shielding?

CONTEXT

Short-stem humeral designs in shoulder arthroplasty have been introduced recently. A retrospective cohort study was conducted to determine if newer proximal porous titanium coating in humeral short stems produced clinical and radiologic improvements.

METHOD

Short-stem humeral implants (Tornier Ascend, Wright Medical) were used in 46 anatomical total shoulder replacements from October 2012 to December 2015. Clinical and radiologic measures were analyzed at one- and two-year follow-up.

RESULTS

Nineteen shoulders received earlier grit blasted stems (Ascend Monolithic), and 27 shoulders received the later stems with proximal titanium porous coating (Ascend Flex). At two-year follow-up, radiographic changes and stress shielding were similar. Medial cortical thinning were more frequently observed in Monolithic (18 of 19) compared to Flex stems (19 of 27) on the PA films, though this was not statistically significant (P = 0.061). Clinical outcome scores improved regardless of the stem type used and independent of the radiologic adaptations on plain films. One participant with the Ascend Flex developed glenoid component failure and rotator cuff tear and was subsequently revised.

DISCUSSION

Clinical and radiological outcomes are similar in both short-stem designs. Proximal titanium porous coating may reduce medial calcar cortical thinning but it does not prevent it.

KEY MESSAGE

When compared to similarly designed uncoated grit-blasted stems, proximally porous coated humeral short stems produced similar clinical and radiological results. The proximal titanium porous coating may reduce medial cortical thinning.

Mid-term radiological results of a cementless short humeral component in anatomical and reverse shoulder arthroplasty

AIMS

Shoulder arthroplasty using short humeral components is becoming increasingly popular. Some such components have been associated with relatively high rates of adverse radiological findings. The aim of this retrospective review was to evaluate the radiological humeral bone changes and mechanical failure rates with implantation of a short cementless humeral component in anatomical (TSA) and reverse shoulder arthroplasty (RSA).

PATIENTS AND METHODS

A total of 100 shoulder arthroplasties (35 TSA and 65 RSA) were evaluated at a mean of 3.8 years (3 to 8.3). The mean age at the time of surgery was 68 years (31 to 90). The mean body mass index was 32.7 kg/m² (17.3 to 66.4).

RESULTS

Greater tuberosity stress shielding was noted in 14 shoulders (two TSA and 12 RSA) and was graded as mild in nine, moderate in two, and severe in three. Medial calcar resorption was noted in 23 shoulders (seven TSA and 16 RSA), and was graded as mild in 21 and moderate in two. No humeral components were revised for loosening or considered to be loose radiologically. Nine shoulders underwent reoperation for infection (n = 3), fracture of the humeral tray (n = 2), aseptic glenoid loosening (n = 1), and instability (n = 3). No periprosthetic fractures occurred.

CONCLUSION

Implantation of this particular short cementless humeral component at the time of TSA or RSA was associated with a low rate of adverse radiological findings on the humeral side at mid-term follow-up. Our data do not raise any concerns regarding the use of a short stem in TSA or RSA. Cite this article: Bone Joint J 2019;101-B:610-614.

Comparison of revision rates and radiographic observations of long and short, uncoated and coated humeral stem designs in total shoulder arthroplasty

There is no consensus on outcomes of long versus short and uncoated versus coated uncemented stems in total shoulder arthroplasty (TSA).

We reviewed the literature to compare revision rates and adverse radiographic observations at ⩾ 2 years of various uncemented humeral stem designs.

We performed an electronic PubMed search for studies on uncemented primary TSA that reported one or more of the following observations at ⩾ 2 years for distinct stem designs: stem revision; subsidence; stress shielding; radiolucent lines; and humeral loosening.

The search returned 258 records, from which 20 articles (22 cohorts) met the inclusion criteria.

The most frequently reported designs were short uncoated stems (7/13 cohorts) at < 3 years and long uncoated stems (8/9 cohorts) at > 3 years.

The incidences of revisions and adverse radiographic observations were lower for short coated designs, compared with short and long uncoated designs, but these findings should be confirmed by prospective studies with a longer follow-up.

Cite this article: EFORT Open Rev 2019;4:70-76. DOI: 10.1302/2058-5241.4.180046.

The effect of stemless humeral component fixation feature design on bone stress and strain response: a finite element analysis

BACKGROUND

Since the advent of stemless implants, several different fixation feature designs have been used to improve primary implant stability. These stemless designs are diverse, and the rationale for their selection and design has not been thoroughly studied. Accordingly, this investigation assessed the effect of stemless implant geometry on the simulated stress and strain response of the proximal humerus.

METHODS

Five humeral finite element models were used to examine 10 generic stemless implants with variable fixation features (2 central, 4 peripheral, and 4 boundary crossing). Loads representing 45° and 75° of shoulder abduction were simulated. Implants were compared based on the percentage of implant-bone surface area that remained in contact, the change in bone stress relative to the intact state, and the simulated potential for bone to resorb, remodel, or remain unchanged after reconstruction.

RESULTS

The implant-bone contact area was greatest for peripheral, followed by central and boundary-crossing designs. All implants elicited similar bone stress variations, which were greatest 0 to 5 mm beneath the resection and laterally. The simulated potential cortical response was also similar for all implants, with the greatest simulated resorbing potential 0 to 15 mm beneath the resection, and very little expected remodeling. Differences between implants were most prominent within the simulated potential trabecular response, with the central implants having the least bone volume percentage expected to resorb.

CONCLUSIONS

Simulated humeral bone response after stemless anatomic shoulder replacement depends on fixation feature geometry. Trade-offs exist between implant types. Centrally pegged implants produced the lowest simulated resorbing potential, whereas peripheral implants had the greatest percentages of implant-bone contact area.

Mid-term results of anatomical total shoulder arthroplasty for primary osteoarthritis using a short-stemmed cementless humeral component

Aims

The aim of this study was to evaluate the clinical and radiological outcome of using an anatomical short-stem shoulder prosthesis to treat primary osteoarthritis of the glenohumeral joint.

Patients and Methods

A total of 66 patients (67 shoulders) with a mean age of 76 years (63 to 92) were available for clinical and radiological follow-up at two different timepoints (T1, mean 2.6 years, sd 0.5; T2, mean 5.3 years, sd 0.7). Postoperative radiographs were analyzed for stem angle, cortical contact, and filling ratio of the stem. Follow-up radiographs were analyzed for timing and location of bone adaptation (cortical bone narrowing, osteopenia, spot welds, and condensation lines). The bone adaptation was classified as low (between zero and three features of bone remodelling around the humeral stem) or high (four or more features).

Results

The mean Constant score improved significantly from 28.5 (sd 11.6) preoperatively to 75.5 (sd 8.5) at T1 (p < 0.001) and remained stable over time (T2: 76.6, sd 10.2). No stem loosening was seen. High bone adaptation was present in 42% of shoulders at T1, with a slight decrease to 37% at T2. Cortical bone narrowing and osteopenia in the region of the calcar decreased from 76% to 66% between T1 and T2. Patients with high bone adaptation had a significantly higher mean filling ratio of the stem at the metaphysis (0.60, sd 0.05 vs 0.55, sd 0.06; p = 0.003) and at the diaphysis (0.65 sd 0.05 vs 0.60 sd 0.05; p = 0.007). Cortical contact of the stem was also associated with high bone adaptation (14/25 shoulders, p = 0.001). The clinical outcome was not influenced by the radiological changes.

Conclusion

Total shoulder arthroplasty using a short-stem humeral component resulted in good clinical outcomes with no evidence of loosening. However, approximately 40% of the shoulders developed substantial bone loss in the proximal humerus at between four and seven years of follow-up. Cite this article: Bone Joint J 2018;100-B:603–9.

An analysis of proximal humerus morphology with special interest in stemless shoulder arthroplasty

BACKGROUND

Shoulder arthroplasty evolution has resulted in the shortening of traditional stemmed humeral components. Newer stemless implants rely on structures that maintain fixation in the metaphyseal region of the proximal humerus. Whereas the overall morphology of the proximal humerus is well understood, the advent of stemless implants requires that additional geometric measures be assessed. This study's purpose was to introduce new anatomic measures to assist with the design of stemless implants.

METHODS

Using computed tomography data from 98 subjects (nonarthritic [n = 41], B2 osteoarthritic [n = 26], and symmetric osteoarthritic [n = 31]), shifts in proximal canal direction, bounding diameters along the canal, and canal depth beneath the center of the humeral resection plane were quantified. Traditional articular aspect ratio terms (ie, resection diameter, humeral head height) were also quantified. All measures were reported relative to a humeral coordinate system relevant to stemless implants.

RESULTS

Humeral depth, gender, and osteoarthritis were found to have effects on the measured parameters. Of these factors, gender was the most prominent, as men presented with significantly larger canal diameters and depths than women did (P < .001). Osteoarthritis had less of a significant impact on results (P < .001), with the attributed differences in canal path direction and articular aspect ratio being small in absolute value. Canal diameter was found to change significantly as a function of depth beneath the resection plane (P < .001).

CONCLUSIONS

This work quantified 3 new morphologic terms relevant to proximal humerus stemless arthroplasty. Together, these outcome measures help define the spatial limits for stemless humeral arthroplasty in an implant-relevant coordinate system.

An assessment of proximal humerus density with reference to stemless implants

BACKGROUND

Shoulder arthroplasty humeral components have undergone several generational changes, with systems now offering shorter stems and stemless options. The stemless humeral implants obtain fixation in the trabecular bone of the proximal humerus through elaborate fixation features. To optimize implant design, the regional variations in bone density within the proximal humerus should be determined. As such, the purpose of this computed tomography-based study was to map the regional variations in bone density of the proximal humerus.

METHODS

The trabecular-canal of the proximal humerus was extracted from computed tomography scans of 98 subjects and divided into 13 slices and 5 subsections (central, anterior, posterior, medial, and lateral). The average apparent density (ρ_AVG) was then quantified in each subsection of the trabecular-canal.

RESULTS

Slice depth, subsection, and gender were all significant main effects, with additional significant interactions between slice depth, subsection, and osteoarthritic condition. The slices above the resection plane had the greatest ρ_AVG, with densities decreasing down the canal. The central subsection had significantly lower ρ_AVG than the peripheral sections, and the medial subsection tended to have the highest ρ_AVG (P < .001). Furthermore, the ρ_AVG of male subjects was significantly greater than that of female subjects (P < .001).

CONCLUSIONS

The apparent density of the proximal humerus' trabecular-canal is nonuniform. This has implications for the design of stemless implants, indicating that implants seeking purchase in higher density bone should take advantage of the peripheral regions of the trabecular-canal within the first 15-20 mm beneath the humeral head resection plane.

Humeral bone resorption after anatomic shoulder arthroplasty using an uncemented stem

BACKGROUND

Bone resorption around the femoral stem after total hip arthroplasty is a well-known phenomenon. However, only a few studies have evaluated bone resorption after shoulder arthroplasty. This study investigated the prevalence of humeral bone resorption after different shoulder arthroplasty procedures.

METHODS

The study included 147 shoulders that underwent total shoulder arthroplasty (TSA) or humeral head replacement (HHR) with an uncemented humeral stem from November 2008 to May 2015 and were monitored for more than 1 year. The prevalence of humeral bone resorption and risk factors were investigated.

RESULTS

The most advanced grade of bone resorption, grade 0, occurred in 21 shoulders (14.3%). Grade 1 bone resorption occurred in 10 (6.8%), grade 2 in 28 (19.0%), grade 3 in 61 (41.5%), and grade 4 in 27 (18.4%). High occurrence of bone absorption was observed in zones 1, 2, and 7. Grade 4 bone resorption did not occur in zones 3 and 5. HHR, on-growth type stem coating, and occupation ratio were significant independent risk factors for grade ≥3 bone resorption, whereas female sex and HHR were significant independent risk factors for grade 4.

CONCLUSION

Bone resorption was observed in 126 shoulders (85.7%), and full-thickness cortical bone resorption occurred in 27 shoulders (18.4%). Bone resorption was frequently observed at the greater tuberosity, lateral diaphysis, and calcar region (zones 1, 2, and 7). Significant risk factors included female sex, HHR with rotator cuff reconstruction, on-growth type stem coating, and high occupation ratio of the implant.

Restoration of the joint geometry and outcome after stemless TESS shoulder arthroplasty

AIM

To evaluate the joint geometry and the clinical outcome of stemless, anatomical shoulder arthroplasty with the TESS system.

METHODS

Twenty-one shoulders with a mean follow-up 18 of months were included. On scaled digital radiographs the premorbid center of rotation (CoR) was assessed and compared to the CoR of the prosthesis by using the MediCAD^® software. Additionally, the pre- and post-operative geometry of the CoR was assessed in relation to the glenoid, the acromion as well as to the proximal humerus. Radiological changes, such as radiolucencies, were also assessed. Clinical outcome was assessed with the Constant and DASH score.

RESULTS

Both, the Constant and DASH scores improved significantly from 11% to 75% and from 70 to 30 points, P < 0.01 respectively. There were no significant differences regarding age, etiology, cemented or metal-backed glenoids, etc. (P > 0.05). The pre- and postoperative humeral offset, the lateral glenohumeral offset, the height of the CoR, the acromiohumeral distance as well as neck-shaft angle showed no significant changes (P > 0.05). The mean deviation of the CoR of the prosthesis from the anatomic center was 1.0 ± 2.8 mm. Three cases showed a medial deviation of more than 3 mm. These deviations of 5.1, 5.7 and 7.6 mm and were caused by an inaccurate humeral neck cut. These 3 patients showed a relatively poor outcome scoring.

CONCLUSION

TESS arthroplasty allows an anatomical joint reconstruction with a very good outcome. Outliers described in this study sensitize the surgeon for an accurate humeral neck cut.

Proximal ingrowth coating decreases risk of loosening following uncemented shoulder arthroplasty using mini-stem humeral components and lesser tuberosity osteotomy

BACKGROUND

Mini-stem humeral component (MSHC) use during total shoulder arthroplasty (TSA) provides bone preservation and ease of revision. MSHCs rely solely on proximal metaphyseal fixation; some early reports have demonstrated an unacceptably high rate of early loosening. To our knowledge, no study analyzing the effect of proximal porous coating on MSHCs has been performed.

METHODS

We performed a retrospective review of consecutive patients who underwent anatomic TSA using coated or uncoated MSHCs with minimum 2-year follow-up. Postoperative radiographs were assessed for risk of or frank stem loosening, subsidence, and presence of radiolucencies. Range of motion, outcome scores (visual analog scale pain, American Shoulder and Elbow Surgeons, and Single Assessment Numeric Evaluation), and any complications were noted.

RESULTS

We analyzed 68 shoulders with a mean follow-up of 27.3 months (range, 24-50 months). Of these, 34 had proximal coating and 34 were uncoated. In the coated group, no stems loosened, 1 (2.9%) subsided, and 7 (20.6%) developed radiolucencies. In the uncoated group, 1 stem (2.9%) became aseptically loose (requiring revision after 26 months), 7 (20.6%) were judged at risk of loosening (2 because of subsidence), and 15 (44.1%) developed radiolucencies. There was also an increased risk of proximal medial humeral radiolucencies among uncoated MSHCs. There were no significant differences in final range of motion or outcome scores.

CONCLUSION

MSHC use is appropriate for TSA, achieving desired pain relief and functional improvement. Overall, component loosening appears uncommon at early follow-up; however, uncoated stems appear to be at greater risk of loosening and developing radiolucencies. Selecting an MSHC with proximal porous coating may decrease the risk of implant-related complications.