Clinical and radiological results of a cementless short stem shoulder prosthesis at minimum follow-up of two years

Does improved resection plane coverage during shoulder arthroplasty influence proximal humeral bone stress? A comparison of circular vs. elliptical humeral heads

BACKGROUND

Stress shielding remains a concern following total shoulder arthroplasty using press-fit short humeral stems. While the effect of alterations in implant geometry, positioning, and sizing on stress shielding have been investigated, the effects of coverage of the cortical boundary of the resection plane have not yet been fully explored. The purpose of this study was to quantify the effect of improved cortical coverage using elliptical vs. circular humeral heads on changes in bone stress and resorbing potential. We hypothesized that better cortical coverage would reduce stress shielding potential.

METHODS

Finite element models of 8 cadaveric humeri were virtually reconstructed with a short stem implant and an optimally fitted circular or elliptical humeral head. Trabecular bone material properties were assigned based on computed tomography attenuation and cortical bone was assigned uniform properties. Loads were applied to mimic 45° and 75° of abduction, and the resulting changes in bone stress were compared to the intact state and the expected time-zero bone resorbing potential were ascertained.

RESULTS

The elliptical humeral heads significantly improved cortical coverage and load transfer in the medial and lateral quadrant resulting in less alteration in cortical bone stress compared to intact and significantly less cortical bone with resorbing potential. However, this came at the cost of significant but comparatively lower increases in cortical resorbing potential in the anterior and lateral quadrants. No significant effects were detected for trabecular bone in any quadrant.

DISCUSSION

The results of this work show that improvements in cortical coverage have a protective effect resulting in less bone volume with resorbing potential. However, in the case of spherical vs. elliptical heads these improvements in the medial and lateral cortex came with tradeoffs in the anterior and posterior cortex because of reduced load transfer in these regions.

Periprosthetic proximal humerus fractures require an individualized treatment approach-results of a multicenter retrospective study

BACKGROUND

In the last years, there has been increasing use of shoulder arthroplasty. As a result, an increasing incidence of periprosthetic humerus fractures (PPHF) is expected. Therefore, this retrospective, multicenter analysis aimed to collect demographic data from patients with PPHF, their treatment strategies, and associated complications.

METHODS

Demographics of patients with PPHF were collected retrospectively from the database of six trauma hospitals between January 2000 and December 2020. All fractures were categorized according to the Wright and Cofield, and Worland classifications. In addition, the type of treatment for PPHF, as well as subsequent complications, were evaluated.

RESULTS

A total of 72 patients with a PPHF were identified. The mean age of the 55 female and 17 male patients was 77 years. PPHF occurred a mean of 50 months after primary arthroplasty implantation, almost exclusively as a result of a fall from standing height (n = 67). In-situ implant was a RTSA in 40 patients and a hemiarthroplasty in 32 patients. More than half of the fractures (n = 38) were type B fractures, according to Wright and Cofield. According to Worland, the majority of patients also had a type B fracture (type B1 (n = 22), type B2 (n = 28), type B3 (n = 10)). Associated comorbidities were found in 21 patients. A total of 31 patients were treated non-operatively, 27 with Open Reduction Internal Fixation (ORIF), and 14 with a revision arthroplasty. Nine primary radial nerve palsies were found (pre-operatively), and seven secondarily (post-operatively). Nine patients suffered from non-union (ORIF 4, non operative 4, stem replacement 1).

CONCLUSION

The treatment strategy for PPHF is primarily tailored to the individual patient. Decisive factors such as patient's age, fracture type, and primary palsies have to be considered for optimal treatment. In type B1 fractures, there is a recommendation for ORIF because of high non-union rates under non-operative treatment. In contrast, in type B2 fractures, a non-operative approach should be preferred, provided there are no radial nerve lesions.

LEVEL OF EVIDENCE

Level IV, epidemiologic study.

Outcomes of a cementless onlay short stem reverse shoulder arthroplasty in elderly patients: a comprehensive analysis of clinical and radiological findings

OBJECTIVE

The objective of this study was to evaluate clinical and radiological outcomes of a short stem reverse shoulder prosthesis with metaphyseal fixation specifically in older patients.

METHODS

All patients, older than 70 years, submitted to a Reverse Shoulder Arthroplasty (RSA) using a cementless onlay short stem (Aequalis Ascend™ Flex Convertible Shoulder System (Stryker®)) from January 2017 to December 2021, with a minimum follow-up of 2 years, were included. Postoperative radiographs were assessed for stem loosening, subsidence, and varus-valgus tilt. Range of motion, visual analogue scale for pain, constant score, complication rate and revision rate were also analysed.

RESULTS

A total of 34 patients with a mean age of 75 years (range 71-83 years) were submitted to a cementless onlay short stem RSA with a Bone Increased Off-Set (BIO-RSA) construct. The mean follow-up period was 61 months (range 54-87). Significant improvements (p < 0.001) were observed for the constant score and range of motion from the preoperative state to final follow-up. One case exhibited a significant varus deviation (> 5˚) during the follow-up period. No case of stem loosening was identified. There was only one case of complication because of post-traumatic dislocation, but the stem didn't need revision.

CONCLUSION

Short stem RSA, even in patients older than 70 years, can yield a stable fixation with a good clinical and radiological outcome at short-medium term follow-up.

LEVEL OF EVIDENCE

Level III; Retrospective Study.

The effects of length and width of the stem on proximal humerus stress shielding in uncemented primary reverse total shoulder arthroplasty

INTRODUCTION

To preserve humeral bone during RTSA, stems have been made shorter and cement avoided whenever possible. However, with the increased use of uncemented RTSA, a phenomenon comparable to the stress shielding of the hip has been described for the proximal humerus. The aim of this study was to investigate the influence of stem length and width on proximal humeral bone resorption after primary uncemented RTSA.

MATERIALS AND METHODS

The prospective shoulder arthroplasty database of our institution was reviewed for all primary uncemented RTSAs from 2017 to 2020 in osteoarthritis and cuff tear arthropathy cases with > 2-year follow-up. We compared the clinical and the radiographic 2-year outcome of the short and standard length stems of the same prosthesis design. This allowed us to assess the effects of stem length and width with regard to stress shielding. Furthermore, we defined a cut-off value for the filling ratios to prevent stress shielding.

RESULTS

Fifty patients were included in the analysis, nineteen were in the short stem group (SHORT) and thirty-one in the standard stem group (STANDARD). After 2 years, SHORT showed a relative Constant Score of 91.8% and STANDARD of 98.3% (p = 0.256). Stress shielding was found in 4 patients (21%) in SHORT and in 16 patients (52%) in STANDARD (p = 0.03); it occurred more frequently in patients with higher humeral filling ratios (p < 0.05). The calculated cut-off to prevent stress shielding was 0.7 (± 0.03) for the metaphyseal and distal filling ratio.

CONCLUSION

While short and standard stems for RTSA have good results after 2 years, we found a significant negative effect of higher length and width of the stem with regard to stress shielding. Even though the clinical effects of stress shielding have to be assessed, short stems should be chosen with a filling ratio at the metaphyseal and distal position below 0.7.

LEVEL OF EVIDENCE (A RETROSPECTIVE CASE-CONTROL STUDY)

III.

The effect of humeral head positioning and incomplete backside contact on bone stresses following total shoulder arthroplasty with a short humeral stem

BACKGROUND

The use of uncemented humeral stems in total shoulder arthroplasty (TSA) is known to be associated with stress shielding. This may be decreased with smaller stems that are well-aligned and do not fill the intramedullary canal; however, the effect of humeral head positioning and incomplete head backside contact has not yet been investigated. The purpose of this study was to quantify the effect of changes in humeral head position and incomplete head backside contact on bone stresses and expected bone response following reconstruction.

METHODS

Three-dimensional finite element models of 8 cadaveric humeri were generated, which were then virtually reconstructed with a short-stem implant. An optimally sized humeral head was then positioned in both a superolateral and inferomedial position for each specimen that was in full contact with the humeral resection plane. Additionally, for the inferomedial position, 2 incomplete humeral head backside contact conditions were simulated whereby contact was defined between only the superior or inferior half of the backside of the humeral head and the resection plane. Trabecular properties were assigned based on computed tomography attenuation and cortical bone was applied uniform properties. Loads representing 45° and 75° of abduction were then applied, and the resulting differentials in bone stress versus the corresponding intact state and the expected time-zero bone response were determined and compared.

RESULTS

The superolateral position reduced resorbing potential in the lateral cortex and increased resorbing potential in the lateral trabecular bone, while the inferomedial position produced the same effects but in the medial quadrant. For the inferomedial position, full backside contact with the resection plane was best in terms of changes in bone stress and expected bone response, although a small region of the medial cortex did experience no load transfer. The implant-bone load transfer of the inferior contact condition was concentrated at the midline of the backside of the humeral head, leaving the medial aspect largely unloaded as a result of the lack of lateral backside support.

DISCUSSION

This study shows that inferomedial humeral head positioning loads the medial cortex at the cost of unloading the medial trabecular bone, with the same occurring for the superolateral position except that the lateral cortex is loaded at the cost of unloading the lateral trabecular bone. Inferomedial positioned heads also were predisposed to humeral head lift-off from the medial cortex, which may increase the risk of calcar stress shielding. For the inferomedial head position, full contact between the implant and resection plane was preferable.

Outcomes of different stem sizes in shoulder arthroplasty

Background

The successive refinement in implant design and operative technique alongwith improved understanding has resulted in increased incidence of total shoulder arthroplasty (TSA). Simultaneously, the indications of TSA have widened and include a range of shoulder pathologies.

Methods

Using the keywords and relevant literature, we have described an overview of the different stem sizes used in shoulder arthroplasty. Relevant description of clinical and radiological outcome is done with regards to different stem sizes.

Discussion

There are plethora of shoulder replacement systems, based on unique philosophy and having their own advantages and disadvantages. Additionally, the rise in ageing population had increased the need for revision TSA, thereby necessitating the judicious choice of implant at primary TSA. We further present the role of cemented and uncemented humeral stems and discuss the findings of finite element analysis. The choice of humeral stem size and use of cemented or uncemented stems have been reported to affect the clinical and radiological outcomes.

Humeral short stem varus-valgus alignment affects bone stress

The use of uncemented humeral stems in total shoulder arthroplasty (TSA) is associated with stress shielding. Shorter length stems have shown to decrease stress shielding; however, the effect of stem varus-valgus alignment is currently not known. The purpose of this study was to quantify the effect of short stem distal humeral endosteal contact due to varus-valgus angulation on bone stresses after TSA. Three-dimensional models of eight male cadaveric humeri were constructed from computed tomography data. Bone models were reconstructed with a short stem humeral component implant in three positions (standard, varus, and valgus). Modeling was performed at 45° and 75° of abduction and the resulting differentials in bone stress compared to the intact state and the expected time-zero bone response were determined. In cortical and trabecular bone, the standard position (STD) altered bone stress less than the valgus (VAL) and varus (VAR) positions relative to the intact state. For both cortical (p = 0.033) and trabecular (p = 0.012) bone, the VAL position produced a larger volume of bone with resorbing potential compared to the STD position.

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.

Anatomic total shoulder arthroplasty in rheumatoid arthritis: A systematic review

PURPOSE

Given the poor soft-tissue quality in rheumatoid arthritis patients, many believe that rheumatoid arthritis should be treated with reverse total shoulder arthroplasty (rTSA). The purpose of this paper is to systematically assess outcomes of anatomic total shoulder arthroplasty (aTSA) in rheumatoid arthritis to determine if aTSA remains a viable option.

METHODS

A comprehensive literature search was conducted identifying articles relevant to aTSA in the setting of rheumatoid arthritis with intact rotator cuff. Outcomes include clinical outcomes and rates of complication and revision.

RESULTS

Ten studies were included with a total of 279 shoulders with mean follow-up of 116 ± 69 months. The mean age was 68 ± 10 years. Survivorship was 97%, 97% and 89% at 5, 10 and 20 years, respectively. The overall complication rate was 9%. Radiolucency was present in 69% of patients, of which 34% were at risk of loosening at 79 months. The overall rate of revision was 8.4%. Studies generally reported clinically significant improvements in range of motion, Constant score and ASES score.

CONCLUSION

aTSA in the rheumatoid patient results in improvements in range of motion and patient-reported outcomes. Rates of complications and survivorship are generally good in this population. However, it should be noted that there is significant heterogeneity in outcome reporting amongst the literature on this topic and that many studies fail to adequately report complication and revision rates. When compared to rTSA in patients with rheumatoid arthritis, evidence suggests that aTSA is still a viable treatment option despite the shift in utilization to rTSA.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

RSA, TSA and PyC hemi-prostheses: comparing indications and clinical outcomes using a second-generation modular short-stem shoulder prosthesis

INTRODUCTION

The goal of this study was to provide an insight into the clinical results after modular short-stem shoulder arthroplasty for various indications.

MATERIALS AND METHODS

A consecutive cohort study of 76 patients followed up for 23-55 (mean 31.4) months. 23 anatomical (TSA), 32 reverse (RSA) and 21 hemi-prostheses with a pyrocarbon head (PyC), using a modular short stem with proximal porous coating were implanted. Range of motion, pain and Constant score (CS) were recorded. Comparisons of pre- vs postoperative outcomes, between prosthesis types and indications, were made.

RESULTS

All prosthesis types brought about a significant improvement (p < 0.05) in all measured outcomes. TSA had a significantly higher increase in the CS than PyC and RSA (p = 0.002 and 0.003, respectively). TSA produced superior gains in all ROM compared with RSA (p < 0.02). RSA brought about significantly smaller improvements in internal rotation than TSA and PyC (p = 0.0001 and 0.008, respectively). TSA had greater pain relief than PyC (p = 0.02). TSA with Walch A glenoids seemed to improve more than type B in the CS. PyC patients with Walch B glenoids improved more than Walch A (p = 0.03). When implanted due to Osteoarthritis (OA), PyC had a comparable final outcome to TSA (p = 0.95), although the preoperatively worse TSA patients had a greater improvement in the CS (p = 0.026). The outcome of RSA did not differ between indications, but Walch A glenoids tended to improve more.

CONCLUSIONS

Using a second-generation short-stem shoulder prostheses, TSA achieves the best clinical improvements overall, especially for OA with a Walch A glenoid. Despite refixation of the subscapularis tendon in all cases, RSA has inferior internal rotation than TSA and PyC, suggesting a mechanical limitation. OA, a Walch B glenoid and arthritis caused by instability seem to be ideal indications when considering PyC.

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.

Humeral stress shielding following cemented endoprosthetic reconstruction: An under-reported complication?

INTRODUCTION

The proximal humerus is a common location for primary and non-primary tumors. Reconstruction of the proximal humerus is commonly performed with an endoprosthesis with low rates of structural failure. The incidence and risk factors for stress shielding are under reported.

METHODS

Thirty-nine (19 male, 20 female) patients underwent resection of the proximal humerus and reconstruction with a cemented modular endoprosthesis between 2000 and 2018. The mean resection length was 12 ± 4 cm and was most commonly performed for metastatic disease (n = 26, 67%).

RESULTS

Stress shielding was observed in 9 (23%) patients at a mean of 29 (6-132) months postoperatively. Patients with stress shielding were noted to have shorter intramedullary stem length (87 vs. 107 mm, p < .001), longer extramedullary implant length (16 vs. 14 cm, p = .01) and a higher extramedullary implant to stem length ratio (2.1 vs. 1.1, p < .001). The incidence of stress shielding was higher (p = .003) in patients reconstructed with 75 mm stem (n = 6, 67%) lengths.

CONCLUSION

Stress shielding of the humerus was associated with the use of shorter stems and long extramedullary implants. The long-term ramifications of stress shielding on implant stability, complications at the time of revision surgery, and overall patient outcomes remain unknown.

Periprosthetic Fractures in Reverse Total Shoulder Arthroplasty: Current Concepts and Advances in Management

PURPOSE OF REVIEW

Expanded indications for reverse total shoulder arthroplasty (RSA) have raised awareness of associated complications, including periprosthetic fractures. The purpose of this article was to provide a comprehensive update on how, when, and why RSA-related periprosthetic fractures occur, as well as to describe the current treatment strategies.

RECENT FINDINGS

Periprosthetic acromial and scapular spine fractures occur in up to 4.3% of cases and periprosthetic humeral fractures occur in approximately 3.5% of RSA procedures. Fractures of the coracoid process and clavicle have also been reported. Current literature has identified several risk factors for intraoperative or postoperative fracture, including underlying osteoporosis, revision arthroplasty, use of a superiorly placed screw during metaglene fixation, and disruption of the scapular ring by transection of the coracoacromial ligament. Periprosthetic fracture associated with RSA is a clinically significant event that warrants prolonged postoperative vigilance, timely diagnosis, and shared patient decision-making regarding treatment. Further research is needed to identify optimal treatment strategies and characterize long-term clinical outcomes following RSA-related periprosthetic fracture.

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.

Long-Term Radiographic Changes in Stemless Press-Fit Total Shoulder Arthroplasty

INTRODUCTION

Stemmed humeral implants have represented the gold standard in total shoulder arthroplasty (TSA) for decades. Like many other joints, the latest trends in TSA designs aim at bone preservation. Current studies have demonstrated that native proximal humeral bone stresses are most closely mimicked by stemless implants. Nevertheless, there are concerns about the long-term performance of stemless designs. The aim of the present study was to evaluate the long-term radiographic changes at the proximal humerus in anatomical stemless press-fit TSA.

MATERIALS AND METHODS

Between 2008 and 2010, 48 shoulders in 43 patients were resurfaced using an anatomic stemless shoulder prosthesis (TESS, Biomet). Thirty shoulders in twenty-five patients who were aged 65.7 ± 9.9 (34 to 82) years were available for clinical and radiographic review at a mean follow-up of 94.0 ± 8.9 (78 to 110) months.

RESULTS

Radiographic changes of the proximal humerus due to stress shielding were found in 38.4% of the stemless TESS implants. Mild stress shielding accounted for 80% of the observed radiographic changes. Radiographs exhibited stable fixation of the stemless humeral press-fit implant at early and late follow-up. In contrast, radiolucent lines at the glenoid implant were found in 96.1% of the cases. Irrespective of the degree of radiographic changes, clinical scores (VAS, Quick-DASH, Constant score) significantly improved at follow-up.

CONCLUSIONS

The anatomic stemless press-fit implant seems to be favorable in terms of implant-related stress shielding. Clinical outcome was not affected by radiographic changes, demonstrating an 8-year clinical performance that seems to be comparable to conventional stemmed TSA.

Proximal humeral bony adaptations with a short uncemented stem for shoulder arthroplasty: a quantitative analysis

Background

Short uncemented stems have recently been proposed as an alternative to classic long stems for shoulder arthroplasty. The early results are promising, but bony adaptations of the proximal humerus have been reported. The aim of this study was to quantify these phenomena using the Ascend Flex stem and to determine the risk factors.

Materials and methods

In a retrospective, single-center study, 183 shoulder arthroplasties were evaluated at 2-year follow-up. All patients underwent clinical evaluations preoperatively and at last follow-up. Radiographs were obtained preoperatively, postoperatively, and at last follow-up. Four types of bony adaptations were analyzed: medial cortical narrowing (MCN), medial metaphysis thinning (MMT), lateral metaphysis thinning (LMT), and under-the-baseplate osteolysis. The risk factors were analyzed in a multivariate model.

Results

MCN was found in 72.6% of cases and was severe (>50%) in 4.4%. MMT was found in 46.4% of cases and was severe in 3.3%. LMT was found in 9.8% of cases and was severe in 2.8%. The risk factors for MCN were the distal filling ratio, osteoporosis, and female sex, whereas MMT and LMT were only influenced by stem axis deviation. Under-the-baseplate osteolysis was found in 34.4% of cases. No influence of bony adaptations on the clinical outcomes was observed. We found no complications related to the stem or to stem loosening.

Conclusion

The radiographic evolution was satisfactory at mid-term follow-up. Bony adaptations seemed to be limited phenomena, without any observed consequence. Avoiding excessive filling and axis deviation may limit these phenomena.

Shoulder arthroplasty using mini-stem humeral components and a lesser tuberosity osteotomy

PURPOSE

To determine whether lesser tuberosity osteotomy (LTO) and mini-stem humeral components (MSHCs) can be safely and effectively used together in total and hemi-shoulder arthroplasty (TSA/HHA).

METHODS

This is a retrospective review of consecutive patients who underwent anatomic TSA/HHA utilizing combined LTO/MSHC with minimum 2-year follow-up. Six-week and final radiographs, range of motion, pain scores, and selected outcome measures were assessed.

RESULTS

Seventy five shoulders with mean follow-up of 27.8 months (24-50 months) were analyzed. Sixty-seven (89.3%) shoulders had uneventful LTO healing. There were five (6.67%) LTO failures, one (1.33%) fibrous union, and two (2.67%) osteotomies that had displaced > 4 mm at 6 weeks; four of the five failures required open repair, including one converted to reverse TSA. The other failure, the fibrous union, and the two displaced osteotomies were without clinical deficits and elected for non-operative management. One patient required intraoperative conversion to a long stem due to concern that metaphyseal bone integrity was compromised, in part, by the LTO. Four (5.33%) stems subsided, with one of them also being frankly loose and requiring revision, while the other three were asymptomatic, not requiring treatment. No other stems were judged to be loose. Mean ASES, SANE, VAS, forward flexion, external rotation, and internal rotation all improved significantly (p < 0.001 for all).

CONCLUSIONS

LTO/MSHC use is appropriate for TSA/HHA, achieving pain relief and functional improvement. Component loosening appears uncommon at early follow-up. Long-stem components should be available in case the metaphyseal bone is compromised. When performed properly, LTO/MSHC use is a safe and effective surgical strategy.

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.

Short-term results of a second generation anatomic short-stem shoulder prosthesis in primary osteoarthritis

INTRODUCTION

The aim of the study was to evaluate the short-term clinical results of anatomic total shoulder arthroplasty with a short-stem prosthesis in primary osteoarthritis.

MATERIALS AND METHODS

65 shoulders with a mean age of 70 years (range 47-85 years) were available for minimum follow-up of 24 months. Clinical outcome was determined by range of motion, Constant score (CS) age and sex-adjusted Constant score (CS%), and subjective shoulder value (SSV). The influence of six different factors (high bone adaptations, age > 65 years, female gender, dominant side, atrophy of the supraspinatus tendon ≥ grade 2, glenoid type B2/B3) on the clinical outcome was assessed.

RESULTS

At mean follow-up of 37 months (range 24-58 months), the CS improved from 36 ± 8 to 75 ± 12 (p < 0.001). The shoulder flexion (100° ± 21° to 159° ± 19°) as well as the external rotation (3° ± 11° to 43° ± 18°) improved significantly (p < 0.001). Three complications were noted (transient neuropraxia of the radial nerve, subjective instability, hematoma with superficial wound infection) leading to one revision surgery (wound debridement). No stem loosening was observed. High bone adaptation was present in 19 out of 65 shoulders (29%). The clinical outcome was not influenced by high bone adaptations (p ≥ 0.095). Age > 65 years (n = 44) and female gender (n = 38) were associated with worse clinical outcome (p ≤ 0.043).

CONCLUSIONS

In the short term, the clinical results of this anatomical short-stem shoulder prosthesis are encouraging. A low prevalence of high bone adaptations was found without any influence on the clinical outcome and stem loosening was not observed.

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.

Short-term clinical outcome of an anatomic short-stem humeral component in total shoulder arthroplasty

BACKGROUND

Short-stem press-fit humeral components have recently been developed in an effort to preserve bone in total shoulder arthroplasty (TSA), but few studies have reported outcomes of these devices. The purpose of this study was to evaluate the short-term clinical outcomes of an anatomic short-stem humeral component in TSA. We hypothesized that the implant would lead to significant functional improvement with low rates of radiographic loosening.

METHODS

A multicenter retrospective review was performed of TSAs using an anatomic short-stem humeral component (Apex; Arthrex, Inc., Naples, FL, USA). The minimum follow-up was 2 years. Functional outcome was evaluated according to the American Shoulder and Elbow Surgeons score, Visual Analog Scale for pain, Single Assessment Numeric Evaluation, Simple Shoulder Test, and range of motion. A radiographic analysis was performed to evaluate component loosening.

RESULTS

Sixty-four patients with a mean age of 64.1 years were available for follow-up at a mean of 25 months postoperatively. There were significant improvements in the Visual Analog Scale (6 to 2; P < .001), Simple Shoulder Test (4 to 10; P < .001), Single Assessment Numeric Evaluation (32 to 84; P < .001), and American Shoulder and Elbow Surgeons (37 to 80; P < .001) scores. Forward flexion improved from 116° to 148° (P < .001), external rotation improved from 30° to 57° (P < .001), and internal rotation improved from an average spinal level of S1 to L2 (P < .001). On radiographic examination, 9% of stems were deemed at risk for loosening, but there was no gross loosening in any patient.

CONCLUSIONS

TSA with an anatomic press-fit short-stem humeral component is associated with significant improvements in clinical outcomes, without evidence of component loosening at short-term follow-up.

Clinical and radiographic outcomes after total shoulder arthroplasty with an anatomic press-fit short stem

BACKGROUND

There is limited information assessing outcomes after total shoulder arthroplasty (TSA) with a press-fit short stem. The purpose of this study was to evaluate early clinical and radiographic outcomes and complications after TSA with an anatomic press-fit short stem.

METHODS

We identified 118 TSAs completed with press-fit short stem and minimum 2-year follow-up; 85 of these patients had a grit-blasted (GB) short stem placed, whereas 33 patients had short stems with proximal porous coating (PPC). Shoulder function scores, active mobility measurements, and radiographs were assessed.

RESULTS

The average age at surgery was 66.7 years, with average follow-up of 3 years. Significant improvements were noted for all shoulder function scores and active mobility measurements from the preoperative state to final follow-up (P < .001). There was no stem loosening in any patients with minimum 2-year follow-up; however, 3 female patients with GB stems had gross loosening of their humeral components before 1 year, 2 requiring revision. Radiolucent lines around the humeral component were found in 5.9% without evidence of loosening. Osseous resorption at the medial cortex was noted in 9.3%. Of patients with PPC stems, no patients were observed to have radiolucent lines compared with 8.2% in the GB group (P = .09).

CONCLUSION

TSAs with anatomic press-fit short stem showed significant clinical improvements from the preoperative state to final short-term follow-up, with few complications and minimal radiographic changes. Lack of PPC may contribute to early loosening in patients with poor bone quality. The authors now use a short stem with PPC.

Stemless Prosthesis for Total Shoulder Arthroplasty

The fourth generation of humeral components currently are being used in anatomic shoulder arthroplasty. Anatomic shoulder arthroplasty implants have evolved to better re-create anatomy, improve fixation, preserve bone, and facilitate revision surgery. Most of the design changes for shoulder arthroplasty implants have centered on the humeral stem, with a transition to shorter, metaphyseal humeral stems. Many of these humeral component design changes may be beneficial; however, long-term studies are necessary to determine if the results of anatomic shoulder arthroplasty with the use of newer humeral components can match those of anatomic shoulder arthroplasty with the use of older humeral components.

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.

Short Stem Reverse Total Shoulder Arthroplasty Periprosthetic Type A Fracture

Alterations have been made over the years to the standard reverse total shoulder arthroplasty (RTSA) prosthetic components in an effort to decrease adverse events; this has led to the advent of a short humeral stem prosthesis. To the authors' knowledge, there are no reports describing the complication of a traumatic periprosthetic Wright and Cofield classification type A fracture with use of a short metaphyseal humeral stem component for RTSA. The authors describe a 49-year-old woman with this pathology who was treated with open reduction and internal fixation using a proximal humerus locking plate, unicortical and bicortical screw fixation, and a cerclage wire construct without the need to violate the shoulder joint or revise components. Three months postoperatively, she was instructed to begin active range of motion in physical therapy. At 13 months postoperatively, the patient rated her pain level at an average 5 of 10 in severity, with active assisted scaption to 125°, external rotation to 15°, and internal rotation to L5. Radiographs at this time revealed a well-healed fracture. This not only indicates the previously unreported occurrence of such a complication pattern, which was thought rare with the advent of the short humeral RTSA stem, but also provides a viable intraoperative strategy for open reduction and internal fixation with a proximal humerus locking plate, unicortical and bicortical screw fixation, and a cerclage wire construct without the need to violate the shoulder joint. [Orthopedics. 2017; 40(4):e721-e724.].

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.

The Humeral Implant in Shoulder Arthroplasty

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

Comparative study of total shoulder arthroplasty versus total shoulder surface replacement for glenohumeral osteoarthritis with minimum 2-year follow-up

BACKGROUND

Compared with total shoulder arthroplasty (TSA), total shoulder surface replacement (TSSR) may offer the advantage of preservation of bone stock and shorter surgical time, possibly at the expense of glenoid component positioning and increasing lateral glenohumeral offset. We hypothesized that in patients treated for osteoarthritis with a sufficient rotator cuff, TSA and TSSR patients have comparable functional outcome, glenoid component version, and lateral glenohumeral offset.

METHODS

We conducted a retrospective cohort study with a minimum of 2 years of follow-up. Patients in the TSA and TSSR groups received a cemented, curved, keeled, all-poly glenoid component. A cemented anatomical humeral stem was used in TSA. TSSR involved a humeral surface replacement (all components from Tornier Inc., St Ismier, France). Patients were assessed for functional outcome. Radiographs were assessed for radiolucent lines. Glenoid component position and lateral glenohumeral offset were assessed using computed tomography images.

RESULTS

After 29 and 34 months of mean follow-up, respectively, TSA (n = 29) and TSSR (n = 20) groups showed similar median adjusted Constant Scores (84% vs. 88%), Oxford Shoulder Scores (44 vs. 44), Disabilities of the Arm, Shoulder and Hand scores (22 vs. 15), and Dutch Simple Shoulder Test scores (10 vs. 11). Glenoid components showed similar radiolucent line counts (median, 0 vs. 0), similar anteversion angles (mean, 0° vs. 2°), and similar preoperative to postoperative increases in lateral glenohumeral offset (mean, 4 vs. 5 mm). One intraoperative glenoid fracture occurred in the TSSR group.

CONCLUSION

Short-term functional and radiographic outcomes were comparable for TSA and TSSR.

Impaction autografting: bone-preserving, secure fixation of a standard humeral component

BACKGROUND

When fixed with bone ingrowth, a tight diaphyseal press fit, or cement, the humeral component of a shoulder arthroplasty may present problems of malposition, stress shielding, or periprosthetic fracture or difficulty with removal at revision arthroplasty. We have avoided the need for these fixation methods by using impaction cancellous autografting of the humeral stem, minimizing contact between the prosthetic stem and the humeral cortex. This study presents the radiographic survivorship of impaction-autografted humeral implants using component subsidence as the primary endpoint.

METHODS

We reviewed 286 primary anatomic shoulder arthroplasties having an average follow-up of 4.9 ± 2.7 years. Initial postoperative radiographs and minimum 2-year follow-up radiographs were evaluated by 3 observers to assess subsidence.

RESULTS

Two different implants (Humeral Replacement Prosthesis [HRP] and Global Advantage prosthesis) were used. Of 286 stems, 267 (93.4%) had not subsided. The Global Advantage prosthesis had a subsidence-free survival rate of 98.5% at 5 years. The stiffer-stemmed HRP used early during the study had a higher rate of subsidence compared with the currently used Global Advantage stem (hazard ratio, 5.6; P = .001). Radiolucent lines of 2 mm or greater were less common for the Global Advantage prosthesis than for the HRP in each of 7 zones (P < .001). Total shoulder arthroplasty was associated with a higher rate of subsidence compared with hemiarthroplasty (hazard ratio, 2.6; P = .12).

CONCLUSIONS

Impaction autografting provides a secure, durable, bone-preserving means of humeral component fixation in anatomic shoulder arthroplasty.

Total shoulder replacement using a bone ingrowth central peg polyethylene glenoid component: a prospective clinical and computed tomography study with short- to mid-term follow-up

AIM OF THE STUDY

To assess the clinical and computed tomography (CT) outcomes of shoulder replacement with a novel bone ingrowth all-polyethylene glenoid component (APGC).

METHODS

Twenty-eight patients (30 shoulders) with osteoarthritis, mean age 62.3 years (range, 45-75), were implanted with the novel component between 2011 and 2013. Patients were evaluated by active range of motion (ROM), Constant-Murley score (CMS), simple shoulder test (SST), X-rays, and multidetector CT at two months and at a mean follow-up of 31 months (range, 24-39). Early and late follow-up CT scans were available for 21/30 shoulders.

RESULTS

Median ROM increased from 105 to 160° for anterior elevation, from 100 to 160° for lateral elevation, from 20 to 40° for external rotation, and from 2 to 10 points for internal rotation (all p < 0.001). CMS rose from 30 to 80.5 points and SST from 2.5 to 11 (both p < 0.0001). None of the glenoid components migrated. Progressive radiolucency was seen in 28/30 shoulders. There was a strong correlation between greater bone ingrowth (median Arnold score: 7) and lower radiolucency score (median Yian score: 2) at the last follow-up (p < 0.001). Osteolysis around the central peg was seen in two shoulders. There was no correlation between clinical scores and CT findings (p >0.05).

DISCUSSION

The partially cemented glenoid component for TSR assessed in this study resulted in satisfactory shoulder function at an early follow-up. The glenoid prosthesis was stable, with few radiolucent lines and good central peg bone ingrowth.

CONCLUSIONS

The satisfactory bone ingrowth documented on CT is encouraging and supports the use of the new prosthesis. Long-term follow-up studies can confirm if this device represents a rational alternative to fully cemented polyethylene glenoids.

Radiographic evaluation of short-stem press-fit total shoulder arthroplasty: short-term follow-up

BACKGROUND

Humeral loosening is an uncommon etiology for revision shoulder arthroplasty. We aimed to evaluate the radiographic and clinical outcomes of a short-stem press-fit humeral component after primary total shoulder arthroplasty.

METHODS

We reviewed our patient database, from January 2008 to December 2011, for primary total shoulder arthroplasties performed with a short-stem press-fit humeral component. Radiographs and clinical outcomes were evaluated in the immediate postoperative period and at the most recent follow-up, with at least 24 months of data for all patients.

RESULTS

There were 73 shoulders that met our inclusion criteria, but 4 underwent revision before 2 years' follow-up. Only 1 of these 4 was revised for aseptic humeral loosening. Sixty-nine shoulders had at least 24 months of radiographic follow-up, and 62 had radiographic and clinical follow-up. Of the 69 shoulders, 5 underwent revision for humeral loosening: 1 for aseptic loosening and 4 for infection. Two other shoulders with humeral loosening were asymptomatic, and the patients refused revision surgery. The overall revision rate for humeral loosening was 8.2% (6 of 73 shoulders). Radiolucent zones of any size were seen in 71.0%, with 8.7% of these shoulders identified as having humeral stems at risk of future loosening. Significant improvements were made in most of the measured clinical outcomes.

CONCLUSIONS

A high percentage of radiolucency was seen around the short-stem press-fit humeral components evaluated in this study at short-term follow-up. The overall rates of loosening and revision for the humeral implant examined in this study are higher than those noted in other recent studies evaluating press-fit stems. The cause of radiolucency and humeral loosening for this implant is not fully understood.

Radiologic bone adaptations on a cementless short-stem shoulder prosthesis

BACKGROUND

This study evaluated the timing and location of radiologic bone adaptations related to shoulder arthroplasty using a single type of cementless short-stem shoulder prosthesis.

METHODS

Uncemented short-stem shoulder arthroplasties were evaluated in 52 patients at a mean age of 71.6 years (range, 58.1-86.6) with a minimum clinical and radiologic follow-up of 2 years (mean, 32 months; range, 23-52 months). All radiographs were analyzed for inclination of the stem, filling ratio of metaphysis and diaphysis, bone remodeling around the stem, radiolucent lines around the glenoid, and subsidence of the humeral stem. Finally, the radiographic and clinical findings were compared between patients with low and high bone adaptations.

RESULTS

At final follow-up, no loosening, subsidence, or osteolysis was seen. High bone adaptations were present in 27 patients (51.9%). Cortical thinning and osteopenia in the medial cortex (82.7%) and spot welds in the lateral cortex (78.6%) were the most frequently occurring bone adaptations. Patients with high bone adaptations had significantly higher metaphyseal (0.60 ± 0.05 vs. 0.56 ± 0.06; P = .024) and diaphyseal filling ratio (0.66 ± 0.04 vs. 0.61 ± 0.06; P = .019) at 2-year follow-up than patients with low bone adaptations. Clinical outcome was not influenced by the radiographic changes.

CONCLUSION

The clinical and radiologic results of the short-stem shoulder arthroplasty are comparable to those with the third and fourth generations of standard stem arthroplasty. Higher filling ratios in the metaphysis and the diaphysis were significantly associated with the occurrence of high bone adaptations.