Current state of short-stem implants in total shoulder arthroplasty: a systematic review of the literature

Insertion sites of latissimus dorsi tendon transfer performed during reverse shoulder arthroplasty: A systematic review and meta-analysis

BACKGROUND

Reverse shoulder arthroplasty (RSA) with concurrent latissimus dorsi transfer (LDT) is a potential treatment option for restoration of external rotation (ER). Biomechanical studies have emphasized the importance of the insertion site location for achieving optimal outcomes. In this systematic review and meta-analysis, we aimed to describe what insertion sites for LDT are utilized during concomitant RSA and their associated clinical outcomes.

METHODS

A systematic review and meta-analysis were performed per PRISMA guidelines. We queried PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify articles reporting on patients who received RSA with LDT to restore ER and specified the site of tendon transfer insertion on the humerus. We first describe reported insertion sites in the literature. Secondarily, we present preoperative and postoperative range of motion and Constant score for different insertion sites as well as reported complications.

RESULTS

Sixteen studies, analyzed as 19 separate cohorts (by insertion site and tendon-transfer), reporting on 264 RSAs with LDT (weighted mean age 66 years, follow-up 39 months, 61% female) were evaluated. Of these, 143 (54%) included a concomitant teres major transfer (LDT/TMT) and 121 (46%) were LDT-only. Fourteen cohorts (14/19, 74%) reported insertion at the posterolateral aspect of the greater tuberosity, four cohorts (4/19, 21%) reported insertion site at the lateral bicipital groove, and one cohort (1/19, 5%) reported separate LDT and TMT with insertion of the TMT to the posterolateral aspect of the greater tuberosity and LDT to the lateral bicipital groove. Meta-analysis revealed no differences in range of motion or Constant score based on humeral insertion site or whether the LDT was transferred alone or with TMT. Leading complications included dislocation, followed by infection and neuropraxia. No discernible correlation was observed between postoperative outcomes and the strategies employed for tendon transfer, prosthesis design, or subscapularis management.

CONCLUSION

The posterolateral aspect of the greater tuberosity was the most-utilized insertion site for LDT performed with RSA. However, in the current clinical literature, LDT with or without concomitant TMT result in similar postoperative ROM and Constant score regardless of insertion site. Analysis of various proposed transfer sites reinforce the ability of LDT with RSA to restore both FE and ER in patients with preoperative active elevation and external rotation loss. Meta-analysis revealed significant improvements in range of motion and Constant score regardless of humeral insertion site or whether the LDT was transferred alone or with TMT, although future studies are needed to determine whether an ideal tendon transfer technique exists.

LEVEL OF EVIDENCE

IV.

The effect of lateralization and distalization after Grammont-style reverse total shoulder arthroplasty

BACKGROUND

The purpose of this study was to evaluate the relationship between multiple radiographic measures of lateralization and distalization and clinical outcome scores after a reverse total shoulder arthroplasty (RTSA).

METHODS

We retrospectively evaluated all RTSAs performed by the senior author between January 1, 2007, and November 1, 2017. We then evaluated the visual analog scale for pain (VAS pain), Simple Shoulder Test (SST), and American Shoulder and Elbow Surgeons (ASES) scores and complication and reoperation rates at a minimum of 2-year follow-up. We measured preoperative and postoperative (2-week) radiographs for the lateralization shoulder angle (LSA), the distalization shoulder angle (DSA), lateral humeral offset, and the distance from the glenoid to the lateral aspect of the greater tuberosity. A multivariable analysis was performed to evaluate the effect of the postoperative radiographic measurements on final patient-reported outcomes (ASES scores, SST, and VAS pain).

RESULTS

The cohort included 216 shoulders from unique patients who had patient-reported outcome scores available at a minimum of 2-year follow-up (average, 4.0 ± 1.9 years) for a total follow-up rate of 70%. In the multivariable models, more lateralization (LSA) was associated with worse final ASES scores -0.52 (95% confidence interval [CI]: -0.88, -0.17; P = .004), and more distalization (DSA) was associated with better final ASES scores 0.40 (95% CI: 0.11, 0.69; P = .007). More lateralization (LSA) was associated with worse final SST scores -0.06 (95% CI: -0.11, -0.003; P = .039). Finally, greater distalization (DSA) was associated with lower final VAS pain scores, ratio = 0.98 (95% CI: 0.96, 1.00; P = .021).

CONCLUSIONS

Greater distalization and less lateralization are associated with better function and less pain after a Grammont-style RTSA. When using a Grammont-style implant, remaining consistent with Grammont's principles of implant placement will afford better final clinical outcomes.

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.

Developing and Validating a Model of Humeral Stem Primary Stability, Intended for In Silico Clinical Trials

In silico clinical trials (ISCT) can contribute to demonstrating a device's performance via credible computational models applied on virtual cohorts. Our purpose was to establish the credibility of a model for assessing the risk of humeral stem loosening in total shoulder arthroplasty, based on a twofold validation scheme involving both benchtop and clinical validation activities, for ISCT applications. A finite element model computing bone-implant micromotion (benchtop model) was quantitatively compared to a bone foam micromotion test (benchtop comparator) to ensure that the physics of the system was captured correctly. The model was expanded to a population-based approach (clinical model) and qualitatively evaluated based on its ability to replicate findings from a published clinical study (clinical comparator), namely that grit-blasted stems are at a significantly higher risk of loosening than porous-coated stems, to ensure that clinical performance of the stem can be predicted appropriately. Model form sensitivities pertaining to surgical variation and implant design were evaluated. The model replicated benchtop micromotion measurements (52.1 ± 4.3 µm), without a significant impact of the press-fit ("Press-fit": 54.0 ± 8.5 µm, "No press-fit": 56.0 ± 12.0 µm). Applied to a virtual population, the grit-blasted stems (227 ± 78µm) experienced significantly larger micromotions than porous-coated stems (162 ± 69µm), in accordance with the findings of the clinical comparator. This work provides a concrete example for evaluating the credibility of an ISCT study. By validating the modeling approach against both benchtop and clinical data, model credibility is established for an ISCT application aiming to enrich clinical data in a regulatory submission.

A comparison of revision rates for stemmed and stemless primary anatomic shoulder arthroplasty with all-polyethylene glenoid components: analysis from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

We compared the rate of all-cause revision of 2 classes of primary anatomic shoulder arthroplasty, stemmed (stTSA) and stemless (slTSA), undertaken with cemented all-polyethylene glenoid components.

METHODS

A large national arthroplasty registry identified 2 cohort groups for comparison, stTSA and l undertaken for all diagnoses between January 1, 2011, and December 31, 2021. A subanalysis from January 1, 2017, allowed capturing of additional patient demographics including American Society of Anesthesiologists score, body mass index, and glenoid morphology. The cumulative percent revision (CPR) was determined using Kaplan-Meier estimates of survivorship and hazard ratios (HR) from Cox proportional hazard models adjusted for age and gender.

RESULTS

Of the 7995 stTSA procedures, the CPR at 9 years was 5.6% (95% confidence interval [CI]: 5.0, 6.4), and for 3156 slTSA procedures, the CPR was 4.4% (95% CI: 3.6, 5.5). There was no significant difference in the rate of revision between the study groups (HR = 0.76 [95% CI: 0.51, 1.14], P = .189, adjusted for age, gender, humeral head size, humeral fixation, bearing surface, glenoid design, and mean surgeon volume [MSV]). There was an increased rate of revision for stTSA and slTSA undertaken with humeral head sizes <44 mm (stTSA <44 mm vs. 44-50 mm, HR = 1.56 [CI: 1.18, 2.08], P = .001; slTSA <44 mm vs. 44-50 mm, HR = 2.08 [CI: 1.32, 3.33], P = .001). MSV as a continuous predictor was not a revision risk to stTSA vs. slTSA, but categorically, a low MSV (<10 stTSA + slTSA cases per annum) was associated with a higher revision rate for stTSA (10-20 cases/yr vs. <10 cases/yr, HR = 0.72 [CI: 0.55, 0.95], P = .019) but was not in slTSA. Revision rates were increased for stTSA with non-crosslinked polyethylene (XLPE) glenoids vs. XPLE after 2 years (HR = 2.20 [CI: 1.57, 3.08], P < .001) but did not significantly differ for slTSA. Metal/XPLE (humeral/glenoid) bearing surface of stTSA rate of revision was not different from each combination of slTSA bearing surface. Instability/dislocation was a revision risk for slTSA vs. stTSA (HR = 1.93 [CI: 1.28, 2.91], P = .001), but from 2017, neither of American Society of Anesthesiologists score, body mass index, and glenoid morphology changed the rate of revision.

CONCLUSIONS

Revision rates of stTSA and slTSA did not significantly differ and were associated with humeral head size but not patient characteristics. Surgeon inexperience of anatomic shoulder arthroplasty and non-XLPE glenoids were risk factors for stTSA revision but not slTSA. The metal/XLPE stTSA rate of revision was not found to differ significantly from slTSA regardless of polyethylene or humeral head bearing type. Revision for instability/dislocation was more common for slTSA.

Lesser Tuberosity Osteotomy for the Management of the Subscapularis During Total Shoulder Arthroplasty

Subscapularis integrity is critical after anatomic total shoulder arthroplasty, with failure leading to potential instability, loss of function, and revision surgery. The three well-described subscapularis mobilization techniques during total shoulder arthroplasty include tenotomy, peel, and lesser tuberosity osteotomy (LTO). While several comparative studies exist, the optimal approach remains controversial. LTO has been associated with the highest healing rates, but techniques and repair constructs are highly variable. The purpose of this article was to provide an overview of LTO with attention on radiographic assessment, repair options, and clinical outcomes.

Anatomic glenohumeral arthroplasty: State of the art

Anatomical total shoulder arthroplasty in its modern form where it reproduces the normal shoulder has been utilized clinically for more than half a century. As the technology and the designs have changed to recreate the humeral and glenoid sides of the joint, the sophistication of design has resulted in the growing number of cases annually worldwide. This increase is due in part to the increasing number of indications that the prosthesis can treat with successful results. On the humeral side, there have been design changes to better reflect the proximal humeral anatomy, and humeral stems are increasingly placed safely without cement. Platform systems which allow conversion of a failed arthroplasty to a reverse configuration without stem extraction is another design change. Similarly, there has been increasing utilization of short stem and stemless humeral components. Extensive experience with shorter stem and stemless devices, however, has yet to demonstrate the purported advantages of these devices, as recent studies have demonstrated equivalent blood loss, fracture rates, operative times, and outcome scores. Easier revision with these shorter stems remains to be definitively established, with only one study comparing the ease of revision between stem types. On the glenoid side, hybrid cementless glenoids, inlay glenoids, cementless all-polyethylene glenoids, and augmented glenoids have all been investigated; however, the indications for these devices remain unclear. Lastly, innovative surgical approaches to implanting shoulder arthroplasty and the use of patient specific guides and computerized planning, while interesting concepts, still await validation before they are utilized on a widespread basis. While reverse shoulder arthroplasty has been increasingly used to reconstruct the arthritic shoulder, anatomic glenohumeral replacement maintains a significant role in the armamentarium of the shoulder surgeon.

Outcomes of Reverse Total Shoulder Arthroplasty with Latissimus Dorsi Tendon Transfer for External Rotation Deficit: A Systematic Review and Meta-Analysis

BACKGROUND

Latissimus dorsi transfer (LDT) has been purported to restore motion in patients undergoing reverse shoulder arthroplasty (RSA) who have preoperative combined loss of forward elevation (FE) and external rotation (ER). This systematic review summarizes the available evidence for the functional outcomes and complications after RSA with LDT. Furthermore, the effect of implant design and whether a concomitant teres major transfer (TMT) was performed were studied.

METHODS

A systematic review was performed per Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We queried PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases to identify articles reporting on LDT with RSA to restore ER. Our primary outcomes were ER, FE, Constant score, and complication incidence. Secondarily, we reported postoperative internal rotation (IR) and compared ER, FE, and Constant score based on lateralized versus medialized global implant design and whether concomitant TMT was performed.

RESULTS

Nineteen studies were evaluated; functional outcomes were assessed in 16 articles reporting on 258 RSAs (123 LDT, 135 LDT-TMT). Surgical indication was most commonly cuff tear arthropathy and massive irreparable cuff tear. Mean ER was -12° preoperatively and 25° postoperatively, FE was 72° preoperatively and 141° postoperatively. Mean postoperative Constant score was 65. Of 138 patients (8 studies) describing IR, only 25% reported a mean postoperative IR ≥L3. Subanalysis comparing lateralized versus medialized implants and whether TMT was concomitantly performed demonstrated no significant difference in postoperative ER, FE, and Constant score, nor preoperative to postoperative improvement in ER and FE. The complication rate was 14.1% (of 291 shoulders from 16 studies), including tear in the tendon transfer (n = 3), revision tendon repair (n = 1), nerve-related complication (n = 9), and dislocation (n = 9).

CONCLUSIONS

RSA with LDT is a reliable option to restore motion, with a comparable complication rate with standard RSA. The use of medialized versus lateralized implants and whether the TM was concomitantly transferred may not influence clinical outcomes.

LEVEL OF EVIDENCE

Level IV. See Instructions for Authors for a complete description of levels of evidence.

Implant selection for successful reverse total shoulder arthroplasty

Reverse total shoulder arthroplasty (RTSA) emerged as a new concept of arthroplasty that does not restore normal anatomy but does restore function. It enables the function of the torn rotator cuff to be performed by the deltoid and shows encouraging clinical outcomes. Since its introduction, various modifications have been designed to improve the outcome of the RTSA. From the original cemented baseplate with peg or keel, a cementless baseplate was designed that could be fixed with central and peripheral screws. In addition, a modular-type glenoid component enabled easier revision options. For the humeral component, the initial design was an inlay type of long stem with cemented fixation. However, loss of bone stock from the cemented stem hindered revision surgery. Therefore, a cementless design was introduced with a firm metaphyseal fixation. Furthermore, to prevent complications such as scapular notching, the concept of lateralization emerged. Lateralization helped to maintain normal shoulder contour and better rotator cuff function for improved external/internal rotation power, but excessive lateralization yielded problems such as subacromial notching. Therefore, for patients with pseudoparalysis or with risk of subacromial notching, a medial eccentric tray option can be used for distalization and reduced lateralization of the center of rotation. In summary, it is important that surgeons understand the characteristics of each implant in the various options for RTSA. Furthermore, through preoperative evaluation of patients, surgeons can choose the implant option that will lead to the best outcomes after RTSA.

Complications and revisions in anatomic and reverse short stem shoulder arthroplasty

INTRODUCTION

One current trend in the field of shoulder arthroplasty is a design shift to shorter and metaphyseal fixed humeral stem components. The aim of this investigation is to analyze complications resulting in revision surgery after anatomic (ASA) and reverse (RSA) short stem arthroplasty. We hypothesize that complications are influenced by the type of prosthesis and indication for arthroplasty.

MATERIALS AND METHODS

A total of 279 short stem shoulder prostheses were implanted by the same surgeon (162 ASA; 117 RSA), and 223 of these prostheses were implanted as primary procedures; in 54 cases, arthroplasty was performed secondary to prior open surgery. Main indications were osteoarthritis (OA) (n = 134), cuff tear arthropathy (CTA) (n = 74) and posttraumatic deformities (PTr) (n = 59). Patients were evaluated at 6 weeks (follow-up 1; FU1), 2 years (FU2) and the time span of the last follow-up defined as FU3 with a minimum FU of 2 years. Complications were categorized into early complications (within FU1), intermediate complications (within FU2) and late complications (> 2 years; FU3).

RESULTS

In total, 268 prostheses (96.1%) were available for FU1; 267 prostheses (95.7%) were available for FU2 and 218 prostheses (77.8%) were available for FU3. The average time for FU3 was 53.0 months (range 24-95). A complication leading to revision occurred in 21 prostheses (7.8%), 6 (3.7%) in the ASA group and 15 (12.7%) in the RSA group (p < 0.005). The most frequent cause for revision was infection (n = 9; 42.9%). After primary implantation, 3 complications (2.2%) occurred in the ASA and 10 complications (11.0%) in the RSA group (p < 0.005). The complication rate was 2.2% in patients with OA, 13.5% in CTA and 11.9% in PTr.

CONCLUSIONS

Primary reverse shoulder arthroplasty had a significantly higher rate of complications and revisions than primary and secondary anatomic shoulder arthroplasty, respectively. Therefore, indications for reverse shoulder arthroplasty should be critically questioned in each individual case.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

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.

Mechanical behavior of hybrid glenoid components compared to all-PE components: a finite element analysis

Purpose

The purpose of this finite element study was to compare bone and cement stresses and implant micromotions among all-polyethylene (PE) and hybrid glenoid components. The hypothesis was that, compared to all-PE components, hybrid components yield lower bone and cement stresses with smaller micromotions.

Methods

Implant micromotions and cement and bone stresses were compared among 4 all PE (U-PG, U-KG, A-KG, I-KG) and 2 hybrid (E-hCG, I-hPG) virtually implanted glenoid components. Glenohumeral joint reaction forces were applied at five loading regions (central, anterior, posterior, superior and inferior). Implant failure was assumed if glenoid micromotion exceeded 75 µm or cement stresses exceeded 4 MPa. The critical cement volume (CCV) was based on the percentage of cement volume that exceeded 4 MPa. Results were pooled and summarized in boxplots, and differences evaluated using pairwise Wilcoxon Rank Sum tests.

Results

Differences in cement stress were found only between the I-hPG hybrid component (2.9 ± 1.0 MPa) and all-PE keeled-components (U-KG: 3.8 ± 0.9 MPa, p = 0.017; A-KG: 3.6 ± 0.5 MPa, p = 0.014; I-KG: 3.6 ± 0.6 MPa, p = 0.040). There were no differences in cortical and trabecular bone stresses among glenoid components. The E-hCG hybrid component exceeded micromotions of 75 µm in 2 patients. There were no differences in %CCV among glenoid components.

Conclusions

Finite element analyses reveal that compared to all-PE glenoid components, hybrid components yield similar average stresses within bone and cement. Finally, risk of fatigue failure of the cement mantle is equal for hybrid and all-PE components, as no difference in %CCV was observed.

Level of evidence

IV, in-silico.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00494-8.

A 135° Short Inlay Humeral Stem Leads to Comparable Radiographic and Clinical Outcomes Compared to a Standard-Length Stem for Reverse Shoulder Arthroplasty

Background

Humeral stem length in reverse total shoulder arthroplasty (RTSA) has decreased in recent years in an attempt to preserve more bone and facilitate stem removal in the revision setting. The purpose of this study was to compare the clinical and radiographic outcomes of a short- to standard-length stem RTSA. The authors hypothesized that there would be no difference in radiographic or clinical outcomes at short-term follow-up.

Methods

Patients who underwent RTSA using a press-fit standard- or short-length humeral component with a consistent geometry (Univers Revers, or Revers Apex; Arthrex, Inc., Naples, FL, USA) were evaluated in a multicenter retrospective review. The minimum clinical follow-up was 2 years. Immediate postoperative radiographs were used to assess initial alignment and filling ratios. In addition, radiographs at 2 years were evaluated for signs of stress shielding and/or loosening. Clinical outcome scores and range of motion were evaluated at the final follow-up and compared between groups.

Results

A total of 220 patients with short-stem RTSA and 357 patients with standard-length stem RTSA were analyzed. There was no difference in baseline function between short- and standard-length stem patients. Patients in the short stem group had higher postoperative American Shoulder and Elbow Surgeons (84.6 vs. 80.8; P = .014) and Western Ontario Osteoarthritis of the Shoulder (86.5 vs. 82.7; P = .025). Patients in the short stem group also had greater postoperative active forward flexion (139° vs. 132°; P = .003) and internal rotation with the arm at 90° of abduction (43° vs. 32°; P < .001) than patients in the standard-length group. Radiographically, there was a higher metaphyseal (P = .049) and diaphyseal (P < .001) fill ratio in the short stem group, although there was no difference in postoperative alignment, radiographic signs of loosening, or revision for loosening between groups (all P > .05).

Conclusion

A short inlay stem leads to comparable radiographic findings and revision-free survival compared with a standard-length stem when placed with a press-fit technique for RTSA. Clinical outcomes are also equivalent or slightly improved with a short stem compared with a standard-length stem.

A comprehensive evaluation of the association of radiographic measures of lateralization on clinical outcomes following reverse total shoulder arthroplasty

BACKGROUND

Although reverse total shoulder arthroplasty (RTSA) has excellent reported outcomes and satisfaction, patients often have postoperative limitations in range of motion (ROM), specifically internal rotation. Increased lateralization is thought to improve ROM following RTSA. The purpose of this study was to evaluate the association between radiographic measurements of lateralization and postoperative ROM and clinical outcome scores following RTSA. The authors hypothesized that increased radiographic lateralization would be associated with improved postoperative ROM, specifically internal rotation, but have no significant association with clinical outcome scores.

METHODS

Patients who underwent RTSA with a 135° neck-shaft angle prosthesis and minimum 2-year clinical and radiographic follow-up were included and retrospectively reviewed. Postoperative radiographs were evaluated for several lateralization measurements including the lateralization shoulder angle (LSA), distance from the lateral border of the acromion to the lateral portion of the glenosphere, distance from the glenoid to the most lateral aspect of the greater tuberosity, and the distance from the lateral aspect of the acromion to the most lateral aspect of the greater tuberosity. Linear regression analyses were used to evaluate the independent association of each radiographic measurement of lateralization on forward flexion, external rotation, internal rotation, and the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) index score at 2 years postoperation. Receiver operating characteristic (ROC) curves were constructed to identify significant thresholds of each radiographic lateralization measurement.

RESULTS

A total of 203 patients were included. For internal rotation, a greater LSA (P = .007), shorter acromion to glenosphere distance (meaning more glenoid lateralization) (P = .005), and a greater acromion to greater tuberosity distance (with the tuberosity more lateral to the acromion) (P = .021) were associated with improved internal rotation. Overall, ROC analysis demonstrated very little significant data, the most notable of which was the LSA, which had a significant cutoff of 82° (sensitivity 57%, specificity 68%, P = .012).

CONCLUSION

Of the numerous radiographic measures of lateralization after RTSA, the LSA is the most significantly associated with outcomes, including improved internal rotation and a decrease in forward flexion and ASES score. The clinical significance of these statistically significant findings requires further study, as the observed associations were for very small changes that may not represent clinical significance.

Fabrication and Optimisation of Ti-6Al-4V Lattice-Structured Total Shoulder Implants Using Laser Additive Manufacturing

This work aimed to study one of the most important challenges in orthopaedic implantations, known as stress shielding of total shoulder implants. This problem arises from the elastic modulus mismatch between the implant and the surrounding tissue, and can result in bone resorption and implant loosening. This objective was addressed by designing and optimising a cellular-based lattice-structured implant to control the stiffness of a humeral implant stem used in shoulder implant applications. This study used a topology lattice-optimisation tool to create different cellular designs that filled the original design of a shoulder implant, and were further analysed using finite element analysis (FEA). A laser powder bed fusion technique was used to fabricate the Ti-6Al-4V test samples, and the obtained material properties were fed to the FEA model. The optimised cellular design was further fabricated using powder bed fusion, and a compression test was carried out to validate the FEA model. The yield strength, elastic modulus, and surface area/volume ratio of the optimised lattice structure, with a strut diameter of 1 mm, length of 5 mm, and 100% lattice percentage in the design space of the implant model were found to be 200 MPa, 5 GPa, and 3.71 mm⁻¹, respectively. The obtained properties indicated that the proposed cellular structure can be effectively applied in total shoulder-replacement surgeries. Ultimately, this approach should lead to improvements in patient mobility, as well as to reducing the need for revision surgeries due to implant loosening.

Symptomatic aseptic loosening of a short humeral stem following anatomic total shoulder arthroplasty

INTRODUCTION

The rate of aseptic humeral component loosening with standard-length stems is historically so low (0.3%) that presence of humeral loosening was given substantial weight in defining periprosthetic shoulder infection by the International Consensus Meeting (ICM) in 2018. This study aims to confirm that the historically low rate of humeral stem aseptic loosening is not affected by the adoption of a novel short humeral stem.

METHODS

Following institutional review board approval, this retrospective multi-institutional study was undertaken. A review of anatomic total shoulder arthroplasty (TSA) cases at 3 institutions provided 184 shoulders that received TSA with a grit-blasted, rectangular short humeral stem without ingrowth coating (Univers Apex; Arthrex). The average patient age was 62.1 years (range: 30-84), and 57.1% (105/184) were male. One-year radiographic follow-up was achieved in 64.7%. Patient clinical charts were reviewed for onset of newly painful shoulders, radiographic evidence of loosening, and return to the operating room for any reason. All patients with concern for clinically significant humeral loosening underwent workup for periprosthetic shoulder infection. Immediate postoperative films were reviewed to identify any differences in prosthetic canal fit. The definition of periprosthetic shoulder infection used was provided by the recent ICM shoulder guidelines.

RESULTS

Twenty-three (12.5%) patients presented with a painful shoulder and radiographic concern for potential humeral loosening at a mean follow-up of 1.5 years (range: 1.5 months-3.4 years). Thirteen (7.1%) of these underwent revision shoulder arthroplasty where a loose stem was confirmed. All revisions underwent tissue culture, and 3 cases were consistent with probable or possible periprosthetic infection at the time of revision arthroplasty. The rate of symptomatic aseptic humeral loosening in this series was 10.9% (20/184), with 5.4% undergoing revision surgery. Patients with symptomatic aseptic humeral loosening were more likely to be male (90.5%) than those patients without symptoms (52.8%, P < .001). There were no differences in canal fit between patients with concern for symptomatic loosening and those with pain-free, stable implants.

CONCLUSION

In this multisurgeon, multicenter study, the early humeral loosening rate for this stem design far outpaces previously reported rates, and this study likely under-reports the true incidence of clinically significant loosening as it only contains limited short-term follow-up. The perception that humeral loosening is nearly pathognomonic for periprosthetic shoulder infection should be reconsidered for certain short humeral stem designs.

Midterm clinical and radiologic survivorship of a stemless total shoulder arthroplasty

AIM

The aim of this study was to evaluate the clinical and radiologic outcomes of stemless total shoulder arthroplasty (TSA) in patients with glenohumeral arthritis.

PATIENTS AND METHODS

This is a retrospective case series of all patients who underwent a TSA with Affinis Short prosthesis during the period 2010-2017. Seventy-two TSAs were performed within our unit, in 62 patients (45 females and 17 males), with 10 patients having bilateral TSAs with this prosthesis. The mean follow-up was 3.9 years (2-8.7 years). Patients were evaluated clinically with the Oxford Shoulder Score, range of movement assessment, and a numerical patient satisfaction score. Follow-up radiographs were evaluated by 2 reviewers assessing for lucency and assigned a Lazarus grade.

RESULTS

Six patients were lost to follow-up prior to their 2-year review. At last follow-up, the mean forward elevation was 157° (80°-180°), abduction was 150° (60°-180°), and external rotation was 39° (20°-60°). The mode internal rotation was to the lumbar spine, with 95% of patients achieving internal rotation to L5 or higher. The mean Oxford Shoulder Score was 45 (18-48). The mean patient satisfaction score was 4.93/5. No humeral lucencies were observed. Sixty-four percent (n=47) of the glenoids were Lazarus grade 0, showing no evidence of radiolucency. The remaining patients were Lazarus grade 1-3, although none were progressive and all patients were asymptomatic. No patients were revised for aseptic loosening. Four patients underwent revision: 1 for infection, 1 for heterotrophic ossification and stiffness, and 2 for rotator cuff failure.

CONCLUSION

Midterm follow-up results indicate good clinical and radiologic survivorship for this stemless TSA. Our findings suggest good patient function and satisfaction, and no patients have required revision for aseptic loosening. Further follow-up is required to determine long-term survivorship.

Inlay total shoulder arthroplasty for primary glenohumeral arthritis

Background

Anatomic total shoulder arthroplasty with a nonspherical humeral head and inlay glenoid replacement has been introduced in the past; however, clinical evidence remains limited. We hypothesized that patients with advanced glenohumeral arthritis demonstrate significant improvements in pain and function.

Methods

Prospective patient-reported outcomes (PROs) included the American Shoulder and Elbow Surgeons score, a pain visual analog scale, and satisfaction. Range of motion was compared to the preoperative status. A sensitivity analysis examined responder rates and compared them to literature thresholds using the minimal clinically important difference and substantial clinical benefit. The preoperative glenoid morphology was determined using the Walsh classification. Zone-specific periprosthetic radiolucent lines were quantified at the last follow-up.

Results

Thirty-nine shoulders in 36 patients (3 bilateral) with a mean age of 65.9 years (26 males, 13 females) and a mean follow-up of 41.0 months were included. Ninety-three percent had grade III osteoarthritis, and 7% grade II. The glenoid Walsh classification included A1 (25%), A2 (25%), B1 (22%), B2 (25%), and C (3%). All PROs improved significantly (P < .001) with a mean American Shoulder and Elbow Surgeons score from 30.4 to 77.1, a pain visual analog scale from 8.1 to 1.5, and excellent (9.1/10) patient satisfaction. PRO-related responder rates for minimal clinically important difference and substantial clinical benefit were ≥85%. Forward elevation improved from 107° to 155°, and external rotation from 22° to 51°. One intraoperative glenoid rim fracture led to advanced radiolucency; no other clinically relevant lucency was observed.

Conclusion

Treatment with inlay total shoulder arthroplasty demonstrated significant functional improvement, excellent pain relief, and patient satisfaction in patients with advanced shoulder arthritis and various glenoid morphology types. Our initial results provide further support for this new option in primary shoulder replacement.

Subscapularis management in stemmed and stemless total shoulder arthroplasty: a surgeon decision-making analysis study

Background

Stemless total shoulder arthroplasty (TSA) continues to grow in popularity as an evolution of stemmed humeral implants. Proposed advantages include bone preservation and ease of potential revision. However, absence of a stem may necessitate a change in subscapularis takedown approach. Specifically, there is theoretical concern about violation of supportive bone with lesser tuberosity osteotomy when using a stemless device. Therefore, the goal of this study was to identify if surgeons change their subscapularis takedown preference when performing stemless vs. stemmed TSA.

Methods and materials

Data from a consecutive series of patients who underwent stemmed and stemless TSA at an academic institution were collected. The subscapularis management technique was documented. Subscapularis takedown techniques were divided into 2 groups: soft-tissue approach (subscapularis tenotomy or peel) and bony approach (lesser tuberosity osteotomy). Historical preference for each surgeon was determined by evaluating techniques employed using stemmed TSA. A Cramers V analysis was run to determine the strength of association between this historical preference and subscapularis management technique used for stemless TSA.

Results

One hundred and fifty-four patients were included in this analysis. There were 72 and 82 stemmed and stemless arthroplasty cases performed, respectively. Of the 154 patients, 50.6% were women. The average age of patients was 64.2 years. Four surgeons were included in this study. In all, there were 79 and 75 bony and soft-tissue subscapularis techniques, respectively. The historical preference for 3 of the surgeons was a subscapularis bony approach, and the historical preference for one of the surgeons was a soft-tissue approach. A Cramer's V analysis was used to measure the relative strength of association between patient factors, historical subscapularis management preference, and subscapularis takedown approach in stemless TSA. Our analysis yielded a value of 0.65 (P < .01), indicating a redundant association between subscapularis management approach used between stemmed and stemless implant per surgeon.

Conclusion

In determining subscapularis tendon management strategy, in surgeons who performed stemmed TSA before stemless TSA, the subscapularis takedown approach used for stemless TSA is strongly associated with surgeon's historical preference for stemmed TSA. Future research will be needed to determine the clinical ramifications of this finding.

Osteolysis at the insertion of L'Episcopo tendon transfer: Incidence and clinical impact

INTRODUCTION

During a L'Episcopo transfer procedure, the tendons of the latissimus dorsi and teres major are reinserted on the posterolateral side of the humeral shaft to restore active external rotation. The aim of this study was to monitor the radiological changes at the insertion point of this transfer and to evaluate its impact on the clinical outcomes.

MATERIALS AND METHODS

In this retrospective, single-center study, 13 patients (mean age 56 years; 19-84) were reviewed after a minimum follow-up of 2 years. The L'Episcopo transfer was done either alone (n=2) or in combination with reverse shoulder arthroplasty (n=11). The same transfer technique was used in both instances, with reattachment by transosseous sutures. The clinical assessment consisted of the Constant score (CS), the Activities of Daily Living Requiring Active External Rotation (ADLER) score and the Subjective Shoulder Value (SSV). Radiographs were used to look for signs of osteolysis of the cortical bone in the tendon transfer areas and classified as grade 1 (minor erosion), grade 2 (moderate erosion) and grade 3 (major erosion).

RESULTS

At a mean follow-up of 37 months (24-72), the mean CS was 60 points (32-75), the ADLER was 21 points (15-30) and the SSV was 77% (10-95). In the radiographic analysis, 10/13 patients had osteolysis visible in the transfer area: 2 were grade 1 (15%), 1 was grade 2 (8%), 7 were grade 3 (54%). There was no statistical correlation between the presence of osteolysis and the clinical outcomes. Nevertheless, external rotation with elbow at side and forward flexion were better in the patients who had osteolysis≥grade 2.

CONCLUSION

The L'Episcopo transfer is associated with frequent osteolysis of the humeral cortex where the transfer is attached, even though the transfer appears effective. Long-term follow-up will be needed to evaluate the impact of this osteolysis on the stability of any shoulder arthroplasty implants.

LEVEL OF EVIDENCE

IV; retrospective study.

Short-stem uncemented anatomical shoulder replacement for osteoarthritis in patients older than 70 years: is it appropriate?

Background

Despite a new trend to systematically use reverse shoulder arthroplasty (RSA) in elderly population regardless of the indication, total anatomical shoulder arthroplasty can get good functional results in this population. The purpose of this study was to evaluate clinical and radiological outcomes of uncemented short-stem anatomic total shoulder arthroplasty (TSA) for primary glenohumeral osteoarthritis in patients older than 70 years and to compare these results to a matched population with an uncemented short-stem RSA.

Methods

In this retrospective monocentric study, clinical outcomes were based on constant score (Cst), subjective shoulder value (SSV) score, and range of motion. The aim of radiographic analysis was to identify glenoid component loosening and humeral bone remodeling around the uncemented short stem.

Results

At an average follow-up of 44 ± 12.5 months, 32 uncemented short-stem TSA in 31 patients with a minimum of 2 years of follow-up were included and were compared to 32 uncemented RSA. Fifty three percent of the patients had “a forgotten prosthesis”. ROM was significantly improved in all cases. Cst reached 73 ± 9 pts and SSV 90 ± 10.8% (P < .001). In 8 patients with repairable supraspinatus tendon tears, clinical outcomes were not statistically different from patients with an intact rotator cuff: Cst (77 ± 6.2 points vs 72 ± 9.6 points, P = .3) and SSV (88 ± 11.5% vs. 91 ± 10.5%; P = .59). The type of glenoid wear (A vs B) did not influence the constant score: 73 ± 9 points versus 74 ± 11 points respectively; P = .81. Despite a complication rate of 6% (n = 2), no prosthesis revision was performed. At last follow-up, range of motion was better in the TSA group compared to the RSA group for internal (7.8 ± 1.3 vs 6.25 ± 2; P = .001) and external (47 ± 14 vs 24 ± 21; P < .001) rotations. The postoperative SSV score was also better in the TSA group (91.3 ± 10% vs 82.2 ± 13%; P = .002).

Conclusions

At medium-term, uncemented short-stem anatomic TSA in patients older than 70 years provided satisfactory clinical results. Patients have forgotten their prosthesis in over 50% of cases. This prosthetic design is still indicated in this patient population in case of primary osteoarthritis with a functional rotator cuff with an almost normal rotator cuff muscle trophicity.

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.