Radiographic changes and clinical outcomes associated with an adjustable diaphyseal press-fit humeral stem in primary reverse shoulder arthroplasty

Radiological and Clinical Outcome Differences Between Standard and Short Stem in Reverse Total Shoulder Arthroplasty: A Systematic Review

BACKGROUND

In recent years, the use of short cementless humeral components in reverse total shoulder arthroplasty (RTSA) has increased. This systematic review aimed to compare the radiological and clinical outcomes of uncemented RTSA using short versus standard humeral stems and assess the impact of these radiological changes on clinical outcomes.

METHODS

A systematic electronic search was performed by two independent reviewers using PubMed, Scopus, and Cochrane Library databases on 10 December 2024. Inclusion criteria involved studies that assessed the radiological and clinical outcomes and overall complication rates of cementless RTSA with short or standard stems in patients with osteoarthritis, cuff tear arthropathy, post-traumatic, and rheumatoid arthritis with a follow-up of at least 1 year. The following data were extracted: radiological parameters of stems including implant subsidence, humeral loosening, and humeral osteolysis and clinical outcomes as Visual Analog Scale pain, American Shoulder and Elbow Surgeons score, Constant Score and Single Assessment Numeric Evaluation score.

RESULTS

A total of 13 studies including 1485 shoulders in 1460 patients were analyzed with a median age at surgery of 74.5 years. The short stem group recorded worse radiological outcomes examined such as humeral loosening, lucencies around the implants, and osteolysis. No significant differences were observed in the clinical outcomes and overall complications between the two types of stems.

CONCLUSIONS

Both short and standard stems are valid options in cementless RTSA. Minimal differences in radiological outcomes were found in favor of RTSA implanted with short stems, while postoperative clinical outcomes were similar between the two types of implants.

Stress shielding in reverse shoulder arthroplasty using a proximally coated stem for proximal humeral fractures: Does it have clinical relevance?

Objectives

To evaluate the clinical significance of stress shielding in patients who have undergone an uncemented reverse shoulder arthroplasty (RSA) with a proximally coated stem for complex proximal humeral fractures (PHF) comprising 3 or 4 parts, assessed at 2 years postoperatively. Additionally, this study aims to examine the correlation between tuberosity healing and clinical outcomes.

Methods

Setting: Single Centre.Patient Selection Criteria: 43 patients underwent surgery involving a cementless RSA with an anatomical stem (Mini Stem of Zimmer Biomet ® Comprehensive System) following an acute 3- or 4-part or 4-part with luxation PHF within 4 weeks of injury. Patients who were excluded from the study included those who passed away, did not have a minimum 2-year follow-up, or had undergone cemented RSAs or alternative humeral components, as well as those who required RSA due to fracture sequelae.Outcome Measures and Comparisons: Stress shielding, tuberosity healing and its positioning were evaluated. Clinical-functional assessments were made using the Constant and ASES scores. Furthermore, quality of life assessments, including QuickDASH score, SF-12, satisfaction test (SANE) and Visual Analogue Scale (VAS) were performed.

Results

Of the total shoulders, 6 (13.9%) were excluded, leaving 37 PHFs that met the inclusion criteria. The mean age at the time of surgery was 72 years (range, 61-85). Stress shielding was observed in 31 shoulders (83.8%). There was no observed correlation between stress shielding and clinical-functional or quality of life assessments. The greater tuberosity in patients without stress shielding was found to be above the tray (66.7%) (P < 0.05). Tuberosity healing was observed in 94.6% (35/37) of the shoulders.

Conclusions

No significant clinical difference was observed between patients with and without stress shielding in terms of short-term functional outcomes. Successful consolidation of the tuberosities can be attained even in cases with notable stress shielding.

Level of Evidence

Level IV; Case Series; Treatment study.

Humeral Stem Design in Reverse Total Shoulder Arthroplasty

PURPOSE OF THE REVIEW

There have been tremendous modifications to the humeral component since Paul Grammont first introduced the reverse total shoulder arthroplasty in 1985. The purpose of this article is to review historical design features and their drawbacks and to summarize the clinical outcomes of modern designs.

RECENT FINDINGS

Decreasing the neck-shaft angle and increasing humeral lateralization have helped address problems of scapular notching and limited internal and external rotation that were common with traditional designs. Advancements in proximal porous coatings have also facilitated the development of short-stem and stemless implants, which decreases the need for cement fixation and allows preservation of bone stock. Moreover, a reduction in stem length with smaller metaphyseal and diaphyseal filling ratios may limit stress shielding. Current humeral implants have an aseptic loosening rate less than 1%. Despite promising results, many of these new humeral design features do not have long-term data and continued surveillance of their performance is necessary. The humeral stem design significantly influences clinical and radiographic outcomes. Surgeons should be mindful of these design variables to increase impingement-free range of motion, minimize scapular notching, reduce stress shielding, and improve implant survivorship.

Radiographic Changes and Clinical Outcomes Associated with Two Different Press-Fit Humeral Stems in Primary Reverse Shoulder Arthroplasty

BACKGROUND

Reverse shoulder arthroplasty (RSA) is used commonly for a wide range of indications. The complications after the total shoulder replacements have been reported to be related with the prosthesis design. The type of the humeral stem is a consideration to reduce complication. Radiographic changes are seen at a high rate with new-generation press-fit stems.

AIM

This study aims to reduce proximal humeral bone loss after RSA could have been achieved with adjustable humeral stem when compared with monoblock stem.

METHODS

A retrospective analysis was made of 52 patients treated with RSA using a press-fit humeral stem prosthesis. The patients were separated into two groups according to the type of humeral stem. The first group included 26 patients (18 females, 8 males) who underwent RSA using adjustable humeral stem. The second group included of 26 patients (17 females, 9 males) for whom monoblock humeral stem was used. Clinical and radiological evaluations were made based on the information obtained at 1, 3, 6, 12, and 18 months postoperatively. The follow-up duration was at least 18 months.

RESULTS

There was no statistical difference between the adjustable and monoblock groups in respect to gender, age, height, and weight. According to the functional measurements at the final follow-up, no statistically significant difference was determined between the groups with respect to the Constant, UCLA, Oxford, DASH, and VAS values. In terms of radiographic changes, both groups were seen to have been similarly affected. It was found that, irrespective of the stem type used, the humeral side radiographic adaptation was found to be high, which negatively affected the functional results (P < 0.05).

CONCLUSION

The increased radiographic stress shielding adaptation leading to humeral osteolysis was found to have a negative effect on the functional results with the press-fit technique irrespective of stem design.

Stress shielding in stemmed reverse shoulder arthroplasty: an updated review

BACKGROUND

Reverse shoulder arthroplasty (RSA) is popular for the treatment of degenerative glenohumeral joint disease. Bone remodeling around the humeral stem related to stress shielding (SS) has been described. This review focuses on the specific radiological characteristics, risk factors, and clinical consequences of SS in RSA.

METHODS

A meticulous review was conducted of articles published between 2013 and 2023. Data on the definition, risk factors, and clinical impact of stress shielding were recorded.

RESULTS

Twenty-eight studies describing 2691 patients who had undergone RSA were included. The mean age of patients ranged from 63 to 80 years with mean follow-up periods of 12 months to 9.6 years. The prevalence of SS reached up to 39% at a 2-year follow-up. Females and elderly are typically at higher risk due to osteopenia. SS was more frequent with the use of long stems(>100 mm) compared to short stems(<100 mm). Stem design, onlay or inlay, and neck-shaft-angle did not influence SS. Frontal misalignment and a high filling ratio are riskfactors for SS. Biological factors also contribute to SS, associated with scapular notching. No correlation was found between SS and clinical outcomes.

CONCLUSIONS

SS is common in patients with cementless implants after RSA, especially in female and elderly patients. It can be limited by implanting stems with a low diaphyseal filling-ratio, in correct coronal alignment. Risk factors for polyethylene debris, primarily scapular notching, should be avoided. The authors found no clinical consequences of stress shielding, but longer-term follow-up studies are required to confirm these findings.

Association between the canal filling ratio and bone resorption in trabecular metal stems in reverse total shoulder arthroplasty: a radiographic analysis using tomosynthesis

Background

Several factors affect the incidence of osteopenia with cortical narrowing (CNO) in reverse shoulder arthroplasty. This study aimed to compare the incidence of CNO with different fixation methods (cemented or cementless) using a single implant (trabecular metal humeral stem) evaluated using tomosynthesis and to analyze the factors affecting the incidence of CNO for cementless stem fixation.

Methods

A total of 109 patients (cementless: 75 cases; cemented: 34 cases) who underwent reverse total shoulder arthroplasty were included in this study. The patients were divided into 2 groups (cementless or cemented), and the incidence of CNO was compared. In addition, patients in the cementless group were divided into 2 groups (canal filling ratio [CFR] of ≥ 0.7 or < 0.7), the incidence of CNO was compared, and the Cramer's coefficient of association between CNO and CFR > 0.7 (and 0.8) was calculated.

Results

No significant difference was observed in the incidence of CNO between the cementless and cemented groups (7/75 vs. 3/35, P value = 1.0). The association between CNO and the CFR using Cramer's coefficient of association showed that there were few correlations (coefficient: 0.14, P value = .59).

Conclusion

Cementless reverse total shoulder arthroplasty with a trabecular metal stem has a similar low incidence of CNO as cemented fixation, and the incidence of CNO with a trabecular metal stem was lower than that reported in previous studies. A CFR > 0.7 was not associated with the incidence of CNO.

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Medium-term clinical and radiographic outcomes of a cementless prosthesis with a 140° neck-shaft angle in reverse total shoulder arthroplasty

BACKGROUND

The design of humeral implants has evolved from the initial Grammont design, notably regarding the neck-shaft angle (NSA) and through the use of cementless prostheses. Stress shielding was frequently reported with cementless implants, the 2 main risk factors being humeral stem misalignment and high filling ratios. Our hypothesis was that standard length cementless stems with an NSA of 140° would facilitate good alignment with moderate filling ratios, thereby limiting stress shielding and ensuring good clinical outcomes.

METHODS

A single-center retrospective study was conducted of patients who underwent reverse total shoulder arthroplasty between January 2015 and August 2017, with at least 2 years' follow-up. Clinical evaluations included range of motion measurements and Constant and subjective shoulder values scores. Frontal alignment was assessed in terms of the angle (α) between axes of the stem and of the humerus. Filling ratios were measured in the metaphysis of the humerus, in the diaphysis, and at the distal end of the stem and considered excessive above 0.7. Stress shielding was evidenced radiographically by the observation of medial cortical narrowing, medial metaphysis thinning, lateral metaphysis thinning or under-the-baseplate osteolysis.

RESULTS

Eighty-two shoulders were included and 70 had radiographic follow-up data available. The mean patient age was 78 years and 63/81 patients (78%) were female. The mean follow-up time was 39 ± 7 months. The mean α angle was 1.4° ± 0.9° and was less than 5° in all cases. The mean metaphyseal, diaphyseal, and distal filling ratios were 0.61 ± 0.06, 0.70 ± 0.08, and 0.64 ± 0.09, respectively. The mean Constant score improved from 28 ± 11 preoperatively to 64 ± 14 at last follow-up. The mean subjective shoulder values score at last follow-up was 81 ± 12. Seventy-nine percent of patients (55/70) had at least 1 form of stress-shielding related, which were not associated with clinical outcomes, apart from lateral metaphysis thinning, which was associated with lower active anterior elevation (mean, 106° ± 30° vs. 126° ± 28°; P = .01) and lower Constant scores (mean, 56 ± 17 vs. 65 ± 14; P = .06).

CONCLUSION

The use of cementless reverse shoulder prostheses with a NSA of 140° was associated with good clinical outcomes at 2 years' follow-up. The prosthesis stem was correctly aligned with the humeral axis and the filling ratios were <0.7 in all cases. Stress-shielding was common but, apart from lateral metaphysis thinning, this had no impact on clinical outcomes.

How common is nerve injury after reverse shoulder arthroplasty? A systematic review

BACKGROUND

Nerve injury following reverse shoulder arthroplasty (RSA) is a known risk factor with wide ranging incidences reported. This systematic review evaluates the overall incidence of nerve injury following primary and revision RSA and summarizes the characteristics of the nerve injuries reported in the current literature.

METHODS

A systematic review was performed using separate database searches (Pubmed, Embase, Web of Science, Cochrane) following the PRISMA guidelines. Search criteria included the title terms "reverse shoulder," "reverse total shoulder," "inverted shoulder," and "inverted total shoulder" with publication dates ranging from 01/01/2010 to 01/01/2022. Studies that reported neurological injuries and complications were included and evaluated for primary RSA, revision RSA, number of nerve injuries, and which nerves were affected.

RESULTS

After exclusion, our systematic review consisted of 188 articles. A total of 40,146 patients were included, with 65% female. The weighted mean age was 70.3 years. The weighted mean follow-up was 35.4 months. The rate of nerve injury after RSA was 1.3% (510 of 40,146 RSAs). The rate of injury was greater in revision RSA compared to primary RSA (2.4% vs. 1.3%). Nerve injury was most common in RSAs done for a primary diagnosis of acute proximal humerus fracture (4.0%), followed by cuff tear arthropathy (3.0%), DJD (2.6%), and inflammatory arthritis (1.7%). Massive rotator cuff tears and post-traumatic arthritis cases had the lowest nerve injury rates (1.0% and 1.4%, respectively). The axillary nerve was the most commonly reported nerve that was injured in both primary and revision RSA (0.6%), followed by the ulnar nerve (0.26%) and median nerve (0.23%). Brachial plexus injury was reported in 0.19% of overall RSA cases.

CONCLUSION

Based on current English literature, nerve injuries occur at a rate of 1.3% after primary RSA compared with 2.4% after revision RSA. The most common nerve injury was to the axillary nerve (0.64%), with the most common operative diagnosis associated with nerve injury after RSA being acute proximal humerus fracture (4.0%). Surgeons should carefully counsel patients prior to surgery regarding the risk of nerve injury.

Humeral stem with low filling ratio reduces stress shielding in primary reverse shoulder arthroplasty

PURPOSE

Some patients show severe humeral bone stress shielding even one year after press-fit humeral stem, which can be a risk factor for implant durability. This study compared humeral stress shielding and clinical outcomes between high and low filling ratio (HFR and LFR) stems in primary reverse shoulder arthroplasty (RSA).

METHODS

From 2015 to 2020, 104 patients who underwent RSA with a non-cemented standard-length humeral stem were examined. The humeral stems included large press-fit stems (HFR group, 53 patients) or small non-press-fit stems with autogenous cancellous bone grafting (LFR group, 51 patients). The radiologic and clinical outcomes were compared between the groups one year post-operatively.

RESULTS

One patient in the LFR group with early infectious dislocation was excluded from the 1-one year evaluation. No stress shielding was observed in 27/50 (54.0%) and 5/53 (9.4%) of patients in the LFR and HFR groups, while 3/50 (6%) and 19/53 (35.8%) patients showed high-stress shielding, respectively. However, the stem alignment change, subsidence, complications and evidence of loosening did not differ between the groups. The final range-of-motion and functional scores were significantly poorer in the LFR group than those in the HFR group, although the difference was minimal.

CONCLUSION

Even at one year follow-up, patients receiving LFR stems with autogenous bone grafting had significantly less humeral stress shielding compared to patients with HFR stem with press-fit in primary RSA, without compromising stem stability.

Reverse shoulder arthroplasty for proximal humeral fracture in the elderly. Cemented or uncemented stem?

OBJECTIVE

The purposes of this study were to compare functional outcomes, radiographic stem changes and complication rate in patients with proximal humeral fractures operated with cemented or uncemented RSA.

METHODS

Retrospective review of 68 primary RSAs in PHF, 45 cemented/23 uncemented. Functional outcomes were evaluated according to constant, ASES scales and the range of motion (ROM). Radiographic assessment was performed at a minimum of two years post-operatively.

RESULTS

The mean follow-up cemented/uncemented was 37.8/26.5 months (p = .04) and the mean age 78/80 years old (p = .09). The functional outcome and range of movement were equivalent in the two groups except for the forward flexion that was significantly higher in the cemented group (p = .03). Stress shielding was seen in 30.4% of uncemented group and none in the cemented. Anatomic tuberosity healing was significantly higher with uncemented components compared with cemented components (64% vs 91%, p = .02). Cemented stems had radiolucent lines with a width of 2 mm or more in three or more Gruen zones in 9% vs 0% in the uncemented group and an evident change in the stem position was present in 4% vs 0% in the non-cemented group.

CONCLUSION

At mid-term follow-up, no differences in functional outcomes were detected depending on the stem fixation technique. Cemented stems, however, have a complication rate (including stem loosening) significantly higher than press-fit stems.

Does Humeral Component Version Affect Range of Motion and Clinical Outcomes in Reverse Total Shoulder Arthroplasty? A Systematic Review

BACKGROUND

Prosthesis selection, design, and placement in reverse total shoulder arthroplasty (RTSA) affect post-operative results. The aim of this systematic review was to evaluate the influence of the humeral stem version and prosthesis design (inlay vs. onlay) on shoulder function following RTSA.

METHODS

A systematic review of the literature on post-operative range of motion (ROM) and functional scores following RTSA with specifically known humeral stem implantations was performed using MEDLINE, Pubmed, and Embase databases, and the Cochrane Library. Functional scores included were Constant scores (CSs) and/or American Shoulder and Elbow Surgeons (ASES) scores. The patients were organised into three separate groups based on the implanted version of their humeral stem: (1) less than 20° of retroversion, (2) 20° of retroversion, and (3) greater than 20° of retroversion.

RESULTS

Data from 14 studies and a total of 1221 shoulders were eligible for analysis. Patients with a humeral stem implanted at 20° of retroversion had similar post-operative mean ASES (75.8 points) and absolute CS (68.1 points) compared to the group with humeral stems implanted at less than 20° of retroversion (76 points and 62.5 points; p = 0.956 and p = 0.153) and those implanted at more than 20° of retroversion (73.3 points; p = 0.682). Subjects with humeral stem retroversion at greater than 20° tended towards greater active forward elevation and external rotation compared with the group at 20° of retroversion (p = 0.462) and those with less than 20° of retroversion (p = 0.192). Patients with an onlay-type RTSA showed statistically significantly higher mean post-operative internal rotation compared to patients with inlay-type RTSA designs (p = 0.048). Other functional scores and forward elevation results favoured the onlay-types, but greater external rotation was seen in inlay-type RTSA designs (p = 0.382).

CONCLUSIONS

Humeral stem implantation in RTSA at 20° of retroversion and greater appears to be associated with higher post-operative outcome scores and a greater range of motion when compared with a retroversion of less than 20°. Within these studies, onlay-type RTSA designs were associated with greater forward elevation but less external rotation when compared to inlay-type designs. However, none of the differences in outcome scores and range of motion between the humeral version groups were statistically significant.

Radiological changes, infections and neurological complications after reverse shoulder arthroplasty related to different design types and their rates: Part II

Early reported complication rates with the Grammont-type reverse shoulder arthroplasty (RSA) were very high, up to 24%.A 'problem' is defined as an intraoperative or postoperative event that is not likely to affect the patient's final outcome, such as intraoperative cement extravasation and radiographic changes. A 'complication' is defined as an intraoperative or postoperative event that is likely to affect the patient's final outcome, including infection, neurologic injury and intrathoracic central glenoid screw placement.Radiographic changes around the glenoid or humeral components of the RSA are very frequently observed and described in the literature.High complication rates related to the Grammont RSA design led to development of non-Grammont designs which led to a dramatic fall in the majority of complications.The percentage of radiological changes after RSA is not negligible and remains unsolved, despite a decrease in its occurrence in the last decade. However, such changes should be now considered as simple problems because they rarely have a negative influence on the patient's final outcome, and their prevalence has dramatically decreased.With further changes in indications and designs for RSA, it is crucial to accurately track the rates and types of complications to justify its new designs and increased indications. Cite this article: EFORT Open Rev 2021;6:1109-1121. DOI: 10.1302/2058-5241.6.210040.

Radiographic changes around the glenoid component in primary reverse shoulder arthroplasty at mid-term follow-up

BACKGROUND

Some local events after reverse shoulder arthroplasty (RSA) occur without the patient experiencing symptoms and yet may be detected on diagnostic imaging, thereby serving as indicators of future complications that may require revision. Most of these events involve the glenoid component, but radiographic studies evaluating this component are scarce, especially medium- and long-term studies. This study aimed to analyze the radiographic changes around the glenoid component and determine the risk factors associated with the presence of these radiographic changes.

MATERIALS AND METHODS

A retrospective review of 105 primary Grammont-style RSAs implanted between 2003 and 2014 was conducted. Radiographic outcomes were evaluated in patients with ≥5 years of radiographic follow-up. Standardized digital radiographs obtained immediately postoperatively and at a minimum follow-up time of 5 years were analyzed to determine (1) glenoid component position (inclination and height) and (2) minor radiographic changes (Sirveaux grade 1 or 2 scapular notching; nondisplaced acromial fracture; radiolucent lines around 1 or 2 screws; Brooker grade 1a, 1b, or 2 heterotopic calcifications; or single screw rupture), as well as major radiographic changes (Sirveaux grade 3 or 4 scapular notching; radiolucent lines around ≥3 screws or central peg; Brooker grade 1c or 3 heterotopic calcifications; prosthetic dislocation; loosening or migration; or disassembly).

RESULTS

Major radiologic changes were identified in 14.3% of the cases. Bivariate analysis showed that more changes were associated with the arthroplasties implanted in the first years of the study (odds ratio [OR] = 0.81, P = .012). This time-related variable was also associated with inclination (OR = 0.88, P = .045) and height (OR = 0.75, P = .001), improving in arthroplasties implanted in the last years of the study. Multivariate analysis revealed an increased risk of severe scapular notching mainly associated with superior tilt (OR = 2.52, P = .036) and a high (OR = 2.68, P = .019) or excessively high (OR = 7.55, P = .013) position and an increased risk of loosening signs associated with superior tilt (OR = 8.92, P = 9.1 × 10^-6).

CONCLUSIONS

The percentage of radiologic changes of the glenoid component in RSA is considerable, despite the detection of a decrease in their presence among the arthroplasties implanted outside the initial period. Superior tilt and an excessively high position appear to be associated with a severe degree of scapular notching development and increased risk of radiographic loosening signs. Knowledge of the factors associated with major radiologic changes in the medium-term follow-up will help to optimize the primary surgical technique for each patient and indication, improving implant survival in primary RSA surgery.

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.

Press-fit reverse shoulder arthroplasty in case of advanced humeral bone loss - Is additional distal fixation necessary for primary stability?

BACKGROUND

Revision reverse shoulder arthroplasty (RSA) poses considerable surgical challenges. We hypothesized that a newly developed press-fit stem, which is modeled on the medullary canal of the supracondylar region of the distal humerus by a slight distal bend, achieve both correct fit and sufficient primary stability and that additional distal fixation by interlocking screws is favorable in case of advanced humeral bone loss.

METHODS

A modular tapered press-fit stem was implanted in 16 Sawbone humeri in three consecutively created defect situations (200 mm (experimental group type 3°), 160 mm (type 4°) and 120 mm (type 5°) bone length above the epicondylar line. In experimental groups type 4° and 5°, additional distal interlocking screw fixation with one to three screws was tested. Primary stability was investigated by measuring micromotions with a high-precision rotational setup.

FINDINGS

Highest relative micromotions were noted at the proximal end in experimental groups type 3° and type 4°, whereas in type 5° highest micromotions could be seen at the distal end. Overall micromotions were significantly lower in type 3° and increased with extended defect size. In experimental group type 5°, micromotions increased with reduced additional distal screw fixation.

INTERPRETATION

The examined press-fit stem did not provide sufficient primary rotational stability in all constructs without additional support. Advanced distal humeral bone loss had a strong impact on primary fixation. In experimental group type 5° with 120 mm bone remaining, it might be beneficial to use three distal interlocking screws in the supracondylar region in order to neutralize torque and to avoid early loosening.

Three-dimensional Volumetric Filling Ratio Predicts Stress Shielding in Short-stem Anatomic Total Shoulder Arthroplasty

INTRODUCTION

Three-dimensional (3-D) CT volumetric filling ratio (VFR) is a better predictor of proximal humerus stress shielding after short-stem anatomic total shoulder arthroplasty (aTSA) than using plain radiographs.

METHODS

Forty-four patients with short-stem aTSAs, preoperative CT scans, and a minimum 3-year radiographic follow-up were included. Patients were divided into group A (stress shielding) and group B (no stress shielding) based on the radiographic analysis. Standard implant filling ratios were measured on plain radiographs. The 3-D VFR of the metaphyseal and diaphyseal segments of the aTSA stem was measured using MIMICS (Materialise). The area under a receiver operator characteristic curve was used to determine the predictive strength of the 3-D VFR method.

RESULTS

The average age and radiographic follow-up was 69 years and 44 months. Group A had 19 patients and statistically higher filling ratios using 3-D VFR method than group B, whereas no notable differences were found between the groups using standard techniques. The 3-D VFR had an area under a receiver operator characteristic curve of 92%, which supports it as a good predictor of stress shielding.

CONCLUSIONS

These methods enable early identification of patients at risk for stress shielding and can also be valuable in improving humeral stem designs.

LEVEL OF EVIDENCE

Level III. Case-control study.

The modern reverse shoulder arthroplasty and an updated systematic review for each complication: part II

Background

Globally, reverse shoulder arthroplasty (RSA) has moved away from the Grammont design to modern prosthesis designs. The purpose of this study was to provide a focused, updated systematic review for each of the most common complications of RSA by limiting each search to publications after 2010. In this part II, the following were examined: (1) instability, (2) humerus/glenoid fracture, (3) acromial/scapular spine fractures (AF/SSF), and (4) problems/miscellaneous.

Methods

Four separate PubMed database searches were performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Overall, 137 studies for instability, 94 for humerus/glenoid fracture, 120 for AF/SSF, and 74 for problems/miscellaneous were included in each review, respectively. Univariate analysis was performed with chi-square and Fisher exact tests.

Results

The Grammont design had a higher instability rate vs. all other designs combined (4.0%, 1.3%; P < .001), and the onlay humerus design had a lower rate than the lateralized glenoid design (0.9%, 2.0%; P = .02). The rate for intraoperative humerus fracture was 1.8%; intraoperative glenoid fracture, 0.3%; postoperative humerus fracture, 1.2%; and postoperative glenoid fracture, 0.1%. The rate of AF/SSF was 2.6% (371/14235). The rate for complex regional pain syndrome was 0.4%; deltoid injury, 0.1%; hematoma, 0.3%; and heterotopic ossification, 0.8%.

Conclusions

Focused systematic reviews of recent literature with a large volume of shoulders demonstrate that using non-Grammont modern prosthesis designs, complications including instability, intraoperative humerus and glenoid fractures, and hematoma are significantly reduced compared with previous studies. As the indications continue to expand for RSA, it is imperative to accurately track the rate and types of complications in order to justify its cost and increased indications.

The modern reverse shoulder arthroplasty and an updated systematic review for each complication: part I

Background

Globally, reverse shoulder arthroplasty (RSA) has moved away from the Grammont design to modern prosthesis designs. The purpose of this 2-part study was to systematically review each of the most common complications of RSA, limiting each search to publications in 2010 or later. In this part (part I), we examined (1) scapular notching (SN), (2) periprosthetic infection (PJI), (3) mechanical failure (glenoid or humeral component), and (4) neurologic injury (NI).

Methods

Four separate PubMed database searches were performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Overall, 113 studies on SN, 62 on PJI, 34 on mechanical failure, and 48 on NI were included in our reviews. Univariate analysis was performed with the χ² or Fisher exact test.

Results

The Grammont design had a higher SN rate vs. all other designs combined (42.5% vs. 12.3%, P < .001). The onlay humeral design had a lower rate than the lateralized glenoid design (10.5% vs. 14.8%, P < .001). The PJI rate was 2.4% for primary RSA and 2.6% for revision RSA. The incidence of glenoid and humeral component loosening was 2.3% and 1.4%, respectively. The Grammont design had an increased NI rate vs. all other designs combined (0.9% vs. 0.1%, P = .04).

Conclusions

Focused systematic reviews of the recent literature with a large volume of RSAs demonstrate that with the use of non-Grammont modern prosthesis designs, complications including SN, PJI, glenoid component loosening, and NI are significantly reduced compared with previous studies. As the indications for RSA continue to expand, it is imperative to accurately track the rates and types of complications to justify its cost and increased indications.

Short-term evaluation of humeral stress shielding following reverse shoulder arthroplasty using press-fit fixation compared with cemented fixation

BACKGROUND

The purpose of this study was to compare the functional outcomes and humeral stress shielding of a reverse shoulder arthroplasty (RSA) placed with either cement or press-fit fixation. The hypothesis was that there would be no difference in functional outcomes or stress shielding.

METHODS

We performed a multicenter retrospective review of primary RSAs performed with standard-length stems. The stems were identical in geometry and coating with the only variable being whether the stems were secured with cement or by a press-fit technique. The functional outcomes and radiographs of 93 press-fit stems and 26 cemented stems were reviewed at a minimum of 2 years postoperatively.

RESULTS

Significant improvements were noted in all ranges of motion and functional outcomes from baseline (P < .001), but no difference was found between the groups (P > .05). Calcar osteolysis was seen in 43% of press-fit and 58% of cemented stems (P = .266). Proximal lateral stress shielding was more common in the press-fit group (68%) than in the cemented group (25%) (P = .045). Adaptive changes were considered low in 97% of press-fit stems, and there were no cases of tuberosity resorption. No evidence of loosening or humeral component shift was noted in either group.

CONCLUSION

At short-term follow-up, no differences in functional outcomes or stem loosening were found between press-fit fixation and cemented fixation of an RSA humeral stem. Proximal stress shielding was more common with press-fit fixation with the stem in this study, but the overall changes were considered low in 97% of cases. Further study is needed to evaluate the mid- to long-term differences regarding stress shielding.

Delta Xtend reverse shoulder arthroplasty - Results at a minimum of five years

BACKGROUND

Reverse shoulder arthroplasty provides predictable pain relief and improvements in function, but concerns remain regarding complication rates and there is little long-term outcome data. The aim of this study was to review the clinical and radiographic outcomes of the Delta Xtend reverse shoulder arthroplasty at a minimum of five years.

METHODS

Ninety-six Delta Xtend reverse shoulder arthroplasty procedures were performed in 93 patients. There were 41 males and 52 females with an average age of 74.9 years. All available patients returned for clinical and radiographic analysis, including completion of patient reported outcome measures.

RESULTS

The complication rate was 9.4%. There were three revisions (3.1%) and two other reoperations (2.1%). Fifty-nine shoulders were available for review at an average of 81 months. Average forward flexion was 142°. Average American Shoulder and Elbow Assessment Score improved from 27.6 to 78.5 (p<0.001). Radiolucent lines and/or proximal bone resorption was seen in 35.4%. Scapula notching was observed in 69.1%, with Grade III or IV notching in 20%. These findings had no effect on patient reported outcome measures.

DISCUSSION

This study confirms the clinical benefits of reverse shoulder arthroplasty, with improvements maintained out to 10 years. The high rate of scapula notching remains a concern. Further study is needed to fully understand the clinical significance of notching, as well as the potential benefits of newer implant designs.

Humeral bone resorption after reverse shoulder arthroplasty using uncemented stem

Background

Humeral stem loosening has gained attention as it has been identified as a cause of revision surgery in reverse shoulder arthroplasty (RSA). In RSA, humeral stem revision is very difficult if there is humeral bone loss because of stress shielding. Some studies of humeral bone resorption after anatomic shoulder arthroplasty have been published, but there are few detailed reports of humeral bone resorption after RSA. This study aimed to investigate the prevalence of humeral bone resorption after RSA procedures and to evaluate the risk factors for bone resorption.

Methods

This study included 48 shoulders that underwent RSA with an uncemented humeral stem from July 2014 to May 2017 and were followed up for more than 1 year. The prevalence of humeral bone resorption and risk factors were investigated. Logistic, multiple logistic, and multivariate logistic regression analyses were performed to evaluate the data.

Results

Grade 0 bone resorption, the most advanced grade, occurred in 8 shoulders (16.7%); grade 1, in 0 (0%); grade 2, in 17 (35.4%); grade 3, in 14 (29.2%); and grade 4, in 9 (18.8%). A high occurrence of bone absorption was observed in zones 1, 2, and 7. Grade 4 bone resorption did not occur in zones 3, 5, and 6. Female sex and an onlay-type stem were significant independent risk factors for grade 4 bone resorption.

Conclusions

Bone resorption was frequently observed in the greater tuberosity, lateral diaphysis, and calcar region. Significant risk factors included female sex and an onlay-type stem.

Humeral-sided Radiographic Changes Following Reverse Total Shoulder Arthroplasty

Background

We sought to characterize humeral-sided radiographic changes at a minimum of 2 years after reverse shoulder arthroplasty (RSA) to determine their association with specific implantation techniques.

Methods

The immediate and most recent postoperative anteroposterior radiographs of 120 shoulders with primary RSA and a minimum of 2-years of radiographic follow-up were analyzed (mean follow-up 35.2 months). Stress shielding was evaluated by measuring cortical thickness at 4 different locations. Three independent examiners evaluated radiographs for humeral osteolysis, radiolucent lines, stress shielding, stem loosening, and scapular notching.

Results

The cortical diameter, marker of external stress shielding, significantly decreased from initial to most recent measurement (P<0.001), but did not differ between cemented and uncemented groups. Cemented stems had significantly more osteolysis and radiolucent lines; uncemented stems had significantly more internal stress shielding (P<001). The presence of scapular notching was significantly correlated with the presence of humeral osteolysis (P<0.001). Three (2.5%) stems were deemed "at risk" for loosening and 2 (1.7%) were loose.

Conclusion

Cemented humeral stems were associated with an increased rate of radiolucent lines and osteolysis, whereas uncemented stems were associated with more internal stress shielding. Humeral cortical thickness significantly decreased over time regardless of fixation. There was an association between scapular notching and increased humeral osteolysis.

How common are acromial and scapular spine fractures after reverse shoulder arthroplasty?: A systematic review

AIMS

Acromial fractures following reverse shoulder arthroplasty (RSA) have a wide range of incidences in reported case series. This study evaluates their incidence following RSA by systematically reviewing the current literature.

MATERIALS AND METHODS

A systematic review using the search terms "reverse shoulder", "reverse total shoulder", or "inverted shoulder" was performed using PubMed, Web of Science, and Cochrane databases between 1 January 2010 and 31 March 2018. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. Studies were included if they reported on RSA outcomes and the incidence rate of acromial and/or scapular spine fractures. The rate of these fractures was evaluated for primary RSA, revision RSA, RSA indications, and RSA implant design.

RESULTS

The review included 90 articles out of 686 identified after exclusions. The incidence rate of acromial and/or scapular spine fractures was 2.8% (253/9048 RSAs). The fracture rate was similar for primary and revision RSA (2.8% vs 2.1%; p = 0.4). Acromial fractures were most common after RSA for inflammatory arthritis (10.9%) and massive rotator cuff tears (3.8%). The incidence was lowest in RSA for post-traumatic arthritis (2.1%) and acute proximal humerus fractures (0%). Lateralized glenosphere design had a significantly higher rate of acromial fractures compared with medial glenosphere designs.

CONCLUSION

Based on current English literature, acromial and/or scapular spine fractures occur at a rate of 2.8% after RSA. The incidence is slightly more common after primary compared with revision arthroplasty. Also, higher rates of acromial fractures are reported in RSA performed for inflammatory arthritis and in the lateralized glenoid design. Cite this article: Bone Joint J 2019;101-B:627-634.

Postoperative radiographic findings of an uncemented convertible short stem for anatomic and reverse shoulder arthroplasty

BACKGROUND

Several short-stemmed press-fit humeral components have been developed in recent years for anatomic total shoulder arthroplasty (TSA) as well as reverse shoulder arthroplasty (RSA). Varying radiographic outcomes have been reported, with some studies reporting concerning rates of aseptic loosening. This study analyzed the radiographic findings of a press-fit convertible short-stemmed humeral component in both TSA and RSA.

METHODS

There were 150 anatomic TSAs (group 1) and 77 RSAs (group 2) analyzed radiographically at a minimum follow-up of 2 years postoperatively. Plain radiographs were reviewed for stem loosening, alignment, signs of stress shielding, and the filling ratio.

RESULTS

At final follow-up, 49% of group 1 and 65% of group 2 had no evidence for radiographic changes. In those with radiographic changes, low bone adaptions were found in 83% and high adaptions in 17% in both groups. Larger stem sizes with higher filling ratios were associated with high radiographic adaptions in both groups (P = .02). The overall filling ratios were higher in group 2 (P = .002). Cortical contact of the stem led to higher bone adaptions (P = .014).

CONCLUSIONS

The short humeral component analyzed in this study showed encouraging survival rates without aseptic loosening. Radiographic changes are associated with a higher filling ratio and cortical contact of the stem. Surgeons should aim to achieve fixation with the minimal required canal filling to minimize radiographic changes with the uncemented humeral component used in this study.

Value comparison of humeral component press-fit and cemented techniques in reverse shoulder arthroplasty

BACKGROUND

Press-fit humeral fixation for reverse shoulder arthroplasty (RSA) has been shown to have loosening rates and outcomes similar to a cemented technique; however, increased value has not been reported. The purpose of this study was to determine whether the press-fit technique could improve the value of RSA using the procedure value index (PVI).

METHODS

Primary RSA patients with complete hospitalization cost data, preoperative and minimum 2-year postoperative Simple Shoulder Test (SST) scores, and postoperative satisfaction were included. The PVI was calculated as improvement in the SST score (in units of minimal clinically important difference) divided by total cost and normalized. Itemized cost data were obtained from hospital financial records and categorized. Radiographic complications, infections, and revisions were noted. Comparisons were made between the press-fit and cemented RSA cohorts.

RESULTS

A total of 176 primary RSA patients (83 cemented and 93 press fit) met the inclusion criteria (mean follow-up period, 44.6 months). Surgical indications (except failed rotator cuff repair), baseline SST scores, and demographic characteristics were similar. The calculated minimal clinically important difference for the SST score was 3.98. The average PVI was significantly greater in the press-fit cohort (1.51 vs 1.03, P < .001), representing a 47% difference. SST score improvement was not significantly different (P = .23). However, total hospitalization costs were significantly lower for the press-fit cohort ($10,048.89 vs $13,601.14; P < .001).

CONCLUSION

Use of a press-fit technique led to a 47% increase in value over a cemented technique. This appeared to be a function of decreased total costs rather than increased outcome scores.

Early outcomes of locked noncemented stems for the management of proximal humeral fractures: a comparative study

BACKGROUND

Proximal humeral fractures are common and a major concern in public health resources utilization. There is an increase in the use of reverse total shoulder arthroplasty (RTSA) as an option for complex fractures in the elderly. The complexity of the technique in RTSA is increased because of the fracture. To find an advantage of locking stems in RTSA for the treatment of proximal humeral fractures, we designed a comparative study between fracture-dedicated locking stems vs. cemented stems.

MATERIALS AND METHODS

We retrospectively studied 58 patients treated with an RTSA after a fracture. We compared how the implant design and the tuberosity consolidation affects patient outcome through measuring range of motion and the Constant score.

RESULTS

The groups were similar in age, sex, time to surgery, and Constant score in the uninjured side. Patients treated with a dedicated locking noncemented stem performed better, with an increased Constant score (P > .05) and reached more mobility with no statistical significance. We found that 13 of the 24 fractures (54%) treated with a cemented stem consolidated, and 26 of 34 tuberosities (76%) healed in the noncemented locked stems. Patients with tuberosity consolidation acquired better range of motion and Constant scores (P < .05).

CONCLUSIONS

A dedicated stem improves tuberosity healing and increases outcomes seen in Constant scores. Tuberosity consolidation is a main goal when treating proximal humeral fractures with RTSA.