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Mid- to long-term clinical outcomes after press-fit short stem reverse shoulder arthroplasty

Open AccessPublished:September 07, 2022DOI:https://doi.org/10.1016/j.jseint.2022.08.004

      Background

      To date, a limited number of studies report mid- to long-term outcomes of press-fit short stem shoulder arthroplasty. The purpose of this study was to report and analyze mid- to long-term outcomes in a series of patients that received press-fit short stem reverse shoulder arthroplasty (RSA). The hypothesis was that press-fit short stem RSA would be a safe and effective treatment with satisfactory mid- to long-term outcomes.

      Methods

      The authors retrospectively reviewed the records of 60 patients that received RSA using press-fit uncemented short humeral stems by two surgeons between March 2014 and December 2015. The absolute Constant Score (CS), age-/sex-adjusted CS, and the American Shoulder and Elbow Surgeons (ASES) score were recorded preoperatively and postoperatively at a minimum follow-up of 6 years. The proportions of patients that achieved a satisfactory outcome after RSA were based on the substantial clinical benefit, as proposed for the absolute CS (net improvement ≥19.1).

      Results

      Of the initial cohort of 60 patients, 9 (15%) died of causes unrelated to RSA, 5 (8%) were revised with partial implant removal, and 4 (7%) were lost to follow-up. This left a final cohort of 42 patients (70%) with complete postoperative CS (absolute and age-/sex-adjusted) and ASES scores at a mean follow-up of 6.7 ± 0.5 years (range, 6.1-7.8). Of the final cohort, 11 (18%) had complications, of which 9 (15%) were treated conservatively, and 2 (3%) required reoperations without implant removal. Net improvements in functional outcomes were 34.7 ± 21.2 for the absolute CS, 54% ± 32% for the age-/sex-adjusted CS, and postoperative ASES scores were 87.9 ± 13.7. Of the 29 patients who had complete records for absolute CS, 22 (76%) received a substantial clinical benefit (net improvement ≥19.1).

      Conclusions

      Mean net improvements of absolute CS exceeded the substantial clinical benefit after press-fit short stem RSA at a follow-up of 6.1 to 8.6 years. While 5 patients (8%) experienced postoperative instability, none had fracture sequelae, which indicates that offset or angular adjustments may be required even in patients with normal bony anatomy. Press-fit short stem RSA is a safe and effective treatment with satisfactory mid- to long-term outcomes, with no stem revisions for aseptic reasons, which compares favorably to the literature that reports high rates of osteolysis and subsequent stem loosening.

      Level of evidence

      Keywords

      Stemmed humeral components remain the gold standard in total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA).
      • Batten T.J.
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      Compared to first-generation implants, manufacturers have short stems in subsequent generations,
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      Mid-term radiological results of a cementless short humeral component in anatomical and reverse shoulder arthroplasty.
      ,
      • Harmer L.
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      with the aim to reduce risks of malpositioning, loosening, and periprosthetic fractures.
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      • et al.
      Mid-term results of a stemless ceramic on polyethylene shoulder prosthesis - a prospective multicentre study.
      Recent years have seen a rise in the use of uncemented, press-fit short stems, <10 cm long,
      • Denard P.J.
      • Raiss P.
      • Gobezie R.
      • Edwards T.B.
      • Lederman E.
      Stress shielding of the humerus in press-fit anatomic shoulder arthroplasty: review and recommendations for evaluation.
      as their potential benefits include shorter surgery times, better bone stock preservation in cases of revision, and easier access in shoulders with substantial humeral deformity.
      • Abdic S.
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      Short stem humeral components in reverse shoulder arthroplasty: stem alignment influences the neck-shaft angle.
      ,
      • Aibinder W.R.
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      Mid-term radiological results of a cementless short humeral component in anatomical and reverse shoulder arthroplasty.
      ,
      • Dukan R.
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      • Rousseau M.A.
      • Boyer P.
      Outcomes of reverse shoulder arthroplasty using a short stem through a superolateral approach.
      Controversy remains regarding the best method for optimal humeral fixation. Traditionally, cemented fixation was mandatory, but studies have revealed adequate osseointegration for stability in second- and third-generation implants yielding good short-term function and lower complication rates.
      • Harmer L.
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      Total shoulder arthroplasty: are the humeral components getting shorter?.
      ,
      • Kleim B.D.
      • Garving C.
      • Brunner U.H.
      RSA, TSA and PyC hemi-prostheses: comparing indications and clinical outcomes using a second-generation modular short-stem shoulder prosthesis.
      Proximally coated short stems have been reported to demonstrate a loosening rate ranging from 0% to 8% that is mostly associated with infection.
      • Aibinder W.R.
      • Bartels D.W.
      • Sperling J.W.
      • Sanchez-Sotelo J.
      Mid-term radiological results of a cementless short humeral component in anatomical and reverse shoulder arthroplasty.
      Other potential complications include component malalignment and higher rates of mechanical failure.
      • Aibinder W.R.
      • Bartels D.W.
      • Sperling J.W.
      • Sanchez-Sotelo J.
      Mid-term radiological results of a cementless short humeral component in anatomical and reverse shoulder arthroplasty.
      To date, a limited number of studies report mid- to long-term outcomes of press-fit short stem shoulder arthroplasty.
      • Abdic S.
      • Athwal G.S.
      • Wittmann T.
      • Walch G.
      • Raiss P.
      Short stem humeral components in reverse shoulder arthroplasty: stem alignment influences the neck-shaft angle.
      ,
      • Dukan R.
      • Bahman M.
      • Rousseau M.A.
      • Boyer P.
      Outcomes of reverse shoulder arthroplasty using a short stem through a superolateral approach.
      The purpose of this study was to report and analyze mid- to long-term outcomes in a series of patients that received press-fit short stem RSA. RSA has been shown to be an effective treatment for patients with a variety of conditions including cuff tear arthropathy, massive rotator cuff tear, osteoarthritis, and rheumatoid arthritis.
      • Burden E.G.
      • Batten T.J.
      • Smith C.D.
      • Evans J.P.
      Reverse total shoulder arthroplasty.
      The hypothesis was therefore that press-fit short stem RSA would be a safe and effective treatment with satisfactory mid- to long-term outcomes.

      Materials and methods

      Cohort

      The authors retrospectively reviewed the records of 60 patients that received RSA using press-fit uncemented short humeral stems (Humeris Reversible, FX Solutions, Viriat, France) by two surgeons (GN and EL) between March 2014 and December 2015. The indications for RSA were cuff tear arthropathy (n = 35), primary osteoarthritis (n = 13), massive rotator cuff tear (n = 7), and trauma sequelae (n = 5). Contraindications for RSA were slightly dislocated or nondislocated fractures, dislocation fractures in elderly patients, severe muscular, neurological or vascular deficiencies affecting the joint, bone destruction or poor bone quality.

      Implant design

      The humeral stem, manufactured from Ti6Al4V ELI, has a stem length of 100 mm which was available in 4 diameters of 8, 10, 12, and 14 mm. The distal end of the stem is tapered medially to create a trapezoidal shape which facilitates insertion and reduces stress shielding on the lateral side (Fig. 1). The proximal surface has a layer of plasma-sprayed titanium coated with plasma-sprayed hydroxyapatite (Ti+HA). The humeral cup attaches to the stem by means of a 10 mm male taper, and consists of ultra-high molecular weight polyethylene (UHMWPE) net-shaped molded within a Ti6Al4V alloy disc. The asymmetric cups are offered in 2 diameters of 36 or 40 mm, and 3 thicknesses of 3, 6, or 9 mm, to obtain a reversed configuration at 145°.
      Figure thumbnail gr1
      Figure 1Graphical presentation of the humeral assembly of the press-fit short stem RSA system. RSA, reverse shoulder arthroplasty.
      A glenoid baseplate of 24 mm diameter, manufactured from Ti6Al4V ELI, has a 17 mm central tapered post which can be extended by 6 or 10 mm. Fixation is established by locking and/or compressing screws which have a ±12° angular tolerance. The screw at the top position has a fixed 10° angular offset. The glenospheres attach to the baseplate by a screw mechanism and peripheral taper, and are manufactured from cobalt chromium (CoCr). The glenospheres are 36 or 40 mm diameter, and are offered in a centered or eccentric option. All glenospheres are lateralized by 3.5 mm, and the articular surface extends 10° beyond the equator which lateralizes the center of rotation to help reduce the potential of scapular notching by the humeral cup.

      Surgical technique

      All patients were operated under general anesthesia in a beach chair position or prone position (surgeon choice) following a deltopectoral approach. The baseplate was impacted and screwed to the glenoid by compressive or locking screws depending on bone quality and surgeon experience. The glenosphere was then impacted and screwed to the baseplate. The humeral stem was impacted and positioned to respect the native retroversion of the humerus (Fig. 2).
      Figure thumbnail gr2
      Figure 2Radiograph illustrating postoperative implant positioning at 8 years follow-up.

      Rehabilitation

      The patients’ shoulders were immobilized in either internal or neutral rotation using a sling. Passive range of motion exercises were initiated on the first postoperative day. Depending on surgeon assessment, active range of motion exercises started after 4 to 6 weeks, under the supervision of physiotherapists.

      Functional outcomes

      The primary functional outcomes were the absolute Constant Score (CS), age-/sex-adjusted CS, and the American Shoulder and Elbow Surgeons (ASES) score. Functional outcomes were recorded preoperatively and postoperatively at a minimum follow-up of 6 years. The proportions of patients that achieved a satisfactory outcome after RSA were based on the substantial clinical benefit, as proposed for the absolute CS (net improvement ≥19.1).
      • Simovitch R.
      • Flurin P.H.
      • Wright T.
      • Zuckerman J.D.
      • Roche C.P.
      Quantifying success after total shoulder arthroplasty: the substantial clinical benefit.
      In addition, complications related to RSA as well as requirement for revision were also recorded. Patients were routinely followed-up at 1 and 12 months after surgery and exceptionally at the final follow-up for the study.

      Informed consent

      This study was performed in accordance with the ethical standards of the 1964 Declaration of Helsinki, and approved by the institutional review board (Ref: COS-RGDS-2022-02-006-NOURISSAT-G). All participants provided informed consent for the use of their data.

      Statistical analysis

      The cohort characteristics were summarized using descriptive statistics. For continuous variables, the mean, standard deviation, range, median and interquartile range were reported, and for categorical variables, the number and proportion were reported. Boxplots were used to visually compare medians and interquartile ranges of postoperative functional outcomes among patients: 1) different indications for surgery. Finally, Shapiro–Wilk tests were used to assess the normality of distributions. Differences between normally distributed groups were assessed using the student’s t test, whereas differences between skewed groups were evaluated using the Wilcoxon rank sum test (Mann–Whitney U test). A P value <.05 was considered statistically significant. All analyses were performed using R version 4.1.0 (R Foundation for Statistical Computing, Vienna, Austria).

      Results

      Of the initial cohort of 60 patients, 9 (15%) died of causes unrelated to RSA, 2 (3%) had revision for infection with the removal of all components, 3 (5%) had revision of the glenoid component for dislocation, and 4 (7%) were lost to follow-up (Fig. 3, Table I). This left a final cohort of 42 patients (70%) with complete postoperative CS (absolute and age-/sex-adjusted) and ASES scores at a mean follow-up of 6.7 ± 0.5 years (range, 6.1 to 7.8). It is worth noting that of the final cohort, 11 (18%) had complications, 9 (15%) of which were treated conservatively, and 2 (3%) required reoperations without implant removal (Table II). It was not possible to determine factors that could have led to instability in 5 patients due to small sample size and skewed distributions.
      Table ICohort characteristics.
      Baseline characteristics (n = 60)Study cohort characteristics (42)P value
      Mean ± SD n (%)(Range)Mean ± SD n (%)(Range)
      Age (y)74.1 ± 8.2(44-90)73.8 ± 7.7(58-87)n.s.
      BMI (kg/m2)28.6 ± 6.0(20-49)28.6 ± 6.0(20-49)n.s.
      Sex (women)46 (77)35 (83)n.s.
      Indications
       Cuff tear arthropathy35 (58)26 (62)n.s.
       Primary OA13 (22)8 (19)n.s.
       Massive rotator cuff tear7 (12)4 (10)n.s.
       Trauma sequelae5 (8)4 (10)n.s.
      Risk factors
       Overweight (BMI>25)31 (52)19 (45)n.s.
       Diabetes3 (5)3 (7)n.s.
       Hypertensive24 (40)17 (40)n.s.
       Dyslipidemia5 (8)4 (10)n.s.
       Osteoporosis1 (2)1 (2)n.s.
       Cardiovascular5 (8)2 (5)n.s.
       Musculoskeletal1 (2)1 (2)n.s.
      BMI, body mass index; OA, osteoarthritis; SD, standard deviation.
      Table IIComplications, reoperations, and revisions.
      ComplicationReoperationTreatmentImplant removed
      Fracture
       AcromionNoConservative
       AcromionNoConservative
       AcromionNoConservative
       Acromion, humerus, and scapulaNoConservative
       ClavicleNoConservative
      InfectionYesImplant removalStem and glenosphere
      InfectionYesImplant removalStem and glenosphere
      InfectionYesLavage
      Instability
       DislocationYesImplant removalGlenosphere
       DislocationYesImplant removalGlenosphere
       DislocationYesImplant removalGlenosphere
       DislocationNoMUA
       SubluxationNoPhysiotherapy
      Other
       Axillary nerveneurapraxia with partial deltoid palsyNoPhysiotherapy
       Bursitis painYesBursectomy
       Urinary tract infectionNoConservative
      MUA, manipulation under anesthesia.
      Net improvements in functional outcomes were 34.7 ± 21.2 for the absolute CS, 54% ± 32% for the age-/sex-adjusted CS, and postoperative ASES scores were 87.9 ± 13.7 (Table III). Patients indicated for surgery due to trauma sequelae had lower CS (absolute and age-/sex-adjusted) compared to patients indicated for surgery due to cuff tear arthropathy, primary osteoarthritis, or massive rotator cuff tear, but the differences did not reach statistical significance (Fig. 4, Table IV). Of the 29 patients who had complete records for absolute CS, 22 (76%) received a substantial clinical benefit (net improvement ≥19.1), whereas 7 patients, 3 treated for trauma sequelae and 4 treated for cuff tear arthropathy, did not receive a substantial clinical benefit (Table V). Two of the 3 patients (women aged 76, 80, and 81 years) that were treated for trauma sequelae had postoperative fractures. Of the 4 patients (3 women aged 69, 77, and 81 years and 1 man aged 69 years) that were treated for cuff tear arthropathy 1 received a bursectomy for bursitis and 1 had a postoperative fracture.
      Table IIIFunctional outcomes of the study cohort (n = 42).
      Mean ± SD n (%)(Range)|Median|(IQR)
      Follow-up (years)6.7 ± 0.5(6.1-7.8)
      Absolute CS
       Preoperative
      Complete preoperative records for only 29 patients.
      32.0 ± 8.5(18.5-50.0)|32.0|(24.0-36.0)
       Postoperative66.3 ± 22.4(19.0-94.0)|71.2|(57.0-82.5)
       Net improvement
      Complete preoperative records for only 29 patients.
      34.7 ± 21.2(−9.0-68.5)|37.0|(23.0-48.0)
       Substantial clinical benefit22 (76%)
      Age-/sex-adjusted CS
       Preoperative
      Complete preoperative records for only 29 patients.
      45% ± 12%(27%-71%)|43.4|(37.0-50.0)
       Postoperative100% ± 33%(30%-147%)|108.0|(85.7-122.0)
       Net improvement
      Complete preoperative records for only 29 patients.
      54% ± 32%(−14%-109%)|54.7|(40.7-77.4)
      ASES score
       Preoperative
      Complete preoperative records for only 10 patients (ASES was not systematically collected preoperatively).
      39.3 ± 6.9(31.7-55.0)|39.2|(34.6-41.2)
       Postoperative87.9 ± 13.7(55.0-100.0)|93.3|(81.2-98.3)
      CS, Constant Score; ASES, American Shoulder and Elbow Surgeons; SD, standard deviation; IQR, interquartile range.
      Complete preoperative records for only 29 patients.
      Complete preoperative records for only 10 patients (ASES was not systematically collected preoperatively).
      Figure thumbnail gr4
      Figure 4Comparison of clinical outcomes by indications for surgery. CS, Constant Score; ASES, American Shoulder and Elbow Surgeons.
      Table IVFunctional outcomes of the study cohort according to indication.
      CTA (n = 26)Primary OA (n = 8)Massive RCT (n = 4)Trauma sequelae (n = 4)
      Mean ± SDMean ± SDMean ± SDMean ± SD
      Absolute CS
       Preoperative34.3 ± 7.724.9 ± 6.732.5 ± 12.431.1 ± 6.4
       Postoperative65.7 ± 22.270.1 ± 20.484.4 ± 6.743.9 ± 24.5
       Net improvement30.8 ± 19.550.9 ± 14.234.7 ± 21.234.7 ± 21.2
      Age-/sex-adjusted CS
       Preoperative47% ± 12%36% ± 10%45% ± 19%43% ± 9%
       Postoperative99% ± 32%111% ± 30%122% ± 11%62% ± 26%
       Net improvement48% ± 29%82% ± 22%54% ± 32%54% ± 32%
      CTA, cuff tear arthropathy; OA, osteoarthritis; RCT, rotator cuff tear; CS, Constant Score; SD, standard deviation.
      Table VDemographics of patients who did not achieve the substantial clinical benefit for absolute CS.
      SexAge, yearsPrevious surgeryRisk factorsComplicationsFollow- up, yearsAbsolute CSAge-/sex-adjusted CS
      BMI >25DiabetesHypertensiveOsteoporosis# Risk factorsTypeTreatmentPreoperativePostoperativeNet improvementPreoperative (%)Postoperative (%)Net improvement (%)
      Trauma sequelae
       Woman81Failure of previous treatment for trauma using pin/nail07.4344511527017
       Woman76Failure due to necrosis following synthesis for treatment of proximal humeral fractureYesYes2Fracture: acromion humerus and scapulaConservative6.23235346558
       Woman80Failure of orthropedic treatment - malunion and pseudarthrosisYes1Fracture: clavicleConservative6.22219−33230−2
      Cuff tear arthropathy
       Man69YesYes26.24033−74844−4
       Woman77Yes1Bursitis painBursectomy6.8283810405919
       Woman69YesYes26.25069197110029
       Woman81YesYes2Fracture: acromionConservative6.84031−96348−14
      CS, Constant Score; ASES, American Shoulder and Elbow Surgeons; BMI, body mass index.

      Discussion

      The main finding of the present study was that at a follow-up of 6.1 to 8.6 years after press-fit short stem RSA, mean net improvements of absolute CS exceeded the substantial clinical benefit; however, 2 (3%) had revision for infection with the removal of all components, 3 (5%) had revision for dislocation with the removal of the glenoid component only, and 2 patients (3%) required reoperation without implant removal. The findings of this study revealed press-fit short stem RSA to be effective in patients treated for cuff tear arthropathy, massive rotator cuff tear, and primary osteoarthritis, but less effective in patients treated for trauma sequelae. It is also worth noting that 5 patients (8%) experienced postoperative dislocation or subluxation, none of which had fracture sequelae, which indicates that instability could occur even in shoulders without anatomic deformities. Of those 5 patients, only 3 required glenosphere revision without stem removal, while the other 2 were treated by manipulation under anesthesia or physiotherapy, which confirms that the stem position was not a contributing factor for revision. These findings therefore partly support the hypothesis that press-fit short stem RSA is a safe and effective treatment with satisfactory mid- to long-term outcomes, with no stem revisions for aseptic reasons.
      The popularity of RSA has increased in recent decades,
      • Dukan R.
      • Bahman M.
      • Rousseau M.A.
      • Boyer P.
      Outcomes of reverse shoulder arthroplasty using a short stem through a superolateral approach.
      and the most common primary indications are osteoarthritis (45%), followed by rotator cuff arthropathy (35%) and fracture (15%).
      • Bonnevialle N.
      • Geais L.
      • Müller J.H.
      • Berhouet J.
      Effect of RSA glenoid baseplate central fixation on micromotion and bone stress.
      While early studies on RSA showed relatively high rates of complications, better outcomes have been reported with newer designs and improved surgical technique
      • Giuseffi S.A.
      • Streubel P.
      • Sperling J.
      • Sanchez-Sotelo J.
      Short-stem uncemented primary reverse shoulder arthroplasty: clinical and radiological outcomes.
      ; however, complication rates could still range from 1% to 28%.
      • Dukan R.
      • Bahman M.
      • Rousseau M.A.
      • Boyer P.
      Outcomes of reverse shoulder arthroplasty using a short stem through a superolateral approach.
      ,
      • Kennedy J.
      • Klifto C.S.
      • Ledbetter L.
      • Bullock G.S.
      Reverse total shoulder arthroplasty clinical and patient-reported outcomes and complications stratified by preoperative diagnosis: a systematic review.
      The complication rate in the present series was 18%, of which 8% were serious requiring implant removal due to dislocation (n = 3) or infection (n = 2).
      Several studies report a high rate of bone resorption after press fit fixation in RSA,
      • Denard P.J.
      • Raiss P.
      • Gobezie R.
      • Edwards T.B.
      • Lederman E.
      Stress shielding of the humerus in press-fit anatomic shoulder arthroplasty: review and recommendations for evaluation.
      and bone remodeling still remains a hypothetical weakness of short stem designs.
      • Godenèche A.
      • Garret J.
      • Barth J.
      • Michelet A.
      • Geais L.
      • Shoulder Friends I.
      Comparison of revision rates and radiographic observations of long and short, uncoated and coated humeral stem designs in total shoulder arthroplasty.
      Short stems potentially protect proximal humeral bone stock by shifting the location of humeral fixation from the diaphysis to the metaphysis which could prevent stress shielding, subsidence, and loosening.
      • Abdic S.
      • Athwal G.S.
      • Wittmann T.
      • Walch G.
      • Raiss P.
      Short stem humeral components in reverse shoulder arthroplasty: stem alignment influences the neck-shaft angle.
      ,
      • Godenèche A.
      • Garret J.
      • Barth J.
      • Michelet A.
      • Geais L.
      • Shoulder Friends I.
      Comparison of revision rates and radiographic observations of long and short, uncoated and coated humeral stem designs in total shoulder arthroplasty.
      The findings of the present study are therefore encouraging as there were no symptoms of humeral stem loosening, although radiographs would be needed to ascertain the quality of implant fixation in the long term.
      The postoperative absolute CS (66.3) reported for the present series at a mean follow-up of 6.7 years compare favorably to those reported by other studies. Dukan et al
      • Dukan R.
      • Bahman M.
      • Rousseau M.A.
      • Boyer P.
      Outcomes of reverse shoulder arthroplasty using a short stem through a superolateral approach.
      reported a mean score of 87.9 at a mean follow-up of 3.2 years. Atoun et al
      • Atoun E.
      • Van Tongel A.
      • Hous N.
      • Narvani A.
      • Relwani J.
      • Abraham R.
      • et al.
      Reverse shoulder arthroplasty with a short metaphyseal humeral stem.
      reported a mean score of 56.2 at a mean follow-up of 3 years. Finally, Levy et al
      • Levy O.
      • Narvani A.
      • Hous N.
      • Abraham R.
      • Relwani J.
      • Pradhan R.
      • et al.
      Reverse shoulder arthroplasty with a cementless short metaphyseal humeral implant without a stem: clinical and radiologic outcomes in prospective 2- to 7-year follow-up study.
      reported a mean score of 59 at a mean follow-up of 4.2 years. The present study also revealed that patients with indication of trauma sequelae for RSA had lower absolute and age-/sex-adjusted CS compared to patients with indications of cuff tear arthropathy, massive rotator cuff tear, and primary osteoarthritis. Interestingly, Cowling et al
      • Cowling P.D.
      • Holland P.
      • Kottam L.
      • Baker P.
      • Rangan A.
      Risk factors associated with intraoperative complications in primary shoulder arthroplasty.
      found that patients undergoing RSA for trauma sequelae had higher risks for intraoperative complications, while Cho et al
      • Cho C.H.
      • Rhee Y.G.
      • Yoo J.C.
      • Ji J.H.
      • Kim D.S.
      • Kim Y.S.
      • et al.
      Incidence and risk factors of acromial fracture following reverse total shoulder arthroplasty.
      found higher risks for acromial fracture after RSA in patients that had prior surgery. It is noteworthy that 3 of the 7 patients that did not receive a substantial clinical benefit were treated for trauma sequelae after failed previous interventions, and 2 of the 3 also had postoperative fractures, one of the acromion and the other of the scapula. These findings suggest that surgeons should carefully consider treatment by RSA in this group of patients, which warrants future investigations to identify specific factors that could lead to suboptimal outcomes.
      The present study revealed encouraging results at mid- to long-term after press-fit short stem RSA, but these findings should be interpreted with the following limitations in mind. First, this was a retrospective analysis of clinical outcomes after RSA at mid- to long-term. Pooling of demographics, surgical data, and functional outcomes could be subject to high levels of heterogeneity. Second, the purpose of this study was to only report on mid- to long-term outcomes in a series of patients who received press-fit short stem RSA, and the study might not be adequately powered to draw any definitive conclusions from the comparisons made in terms of indications for surgery. Third, there were no preoperative or postoperative radiographs available to assess implant position, alignment, or signs of osteolysis. The final follow-up occurred during the COVID-19 pandemic, and it was inappropriate to recall asymptomatic elderly patients for radiographic follow-up, to avoid exposure to the disease as per national guidelines.

      Conclusion

      Mean net improvements of absolute CS exceeded the substantial clinical benefit after press-fit short stem RSA at a follow-up of 6.1 to 8.6 years. While 5 patients (8%) experienced postoperative instability, none had fracture sequelae, which indicates that offset or angular adjustments may be required even in patients with normal bony anatomy. Press-fit short stem RSA is a safe and effective treatment with satisfactory mid- to long-term outcomes, with no stem revisions, which compares favorably to the literature.

      Acknowledgments

      The authors are grateful to Sonia Dubreuil who assisted with the collection of postoperative outcomes.

      Disclaimers

      Funding: Statistical analysis and manuscript preparation were funded by FX Solutions.
      Conflicts of interest: Geoffroy Nourissat will receive fees from FX Solutions for data collection in relation to this study, but no other financial payments or other benefits from any commercial entity related to the subject of this article. Jacobus H Müller is employed by ReSurg. Mo Saffarini is employed by ReSurg. Eric Lenoble will receive fees from FX Solutions for data collection in relation to this study, but no other financial payments or other benefits from any commercial entity related to the subject of this article. The other author, his immediate family, and any research foundation with which he is affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.

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