The Humeral Implant in Shoulder Arthroplasty

Humeral stem loosening is not always prosthetic joint infection

BACKGROUND

Aseptic humeral stem loosening is an uncommon complication of shoulder arthroplasty, and its presence has been considered a highly specific predictor of prosthetic joint infection (PJI). Literature on aseptic humeral stem loosening is sparse. The primary purpose of this study was to determine the rate of aseptic humeral loosening in revision shoulder arthroplasty. Secondarily, we sought to identify predictors of septic and aseptic humeral loosening.

METHODS

Our institutional revision shoulder arthroplasty database was reviewed. Inclusion criteria were patients with humeral stem loosening as indicated in the operative report. Patient demographics, index surgery and indication, revision surgery and indication, and operative data were recorded. Charts were manually reviewed, and PJI scores were calculated using the International Consensus Meeting scoring criteria. International Consensus Meeting classifications of PJI "unlikely" and "possible" were considered aseptic, and PJI "probable" and "definite" were considered septic. Statistical analysis was performed to determine associations between the abovementioned variables and aseptic humeral loosening.

RESULTS

Forty-six patients with 48 shoulders were included in our analysis. Ten cases (21%) were classified as definite PJI, 13 cases (27%) were classified as probable PJI, 4 cases (8%) were classified as possible PJI, and 21 cases (44%) were classified as PJI unlikely. On analysis of stem design, there were no statistically significant associations with aseptic loosening; although, a lack of proximal porous ingrowth surface trended toward higher rates of aseptic loosening in all patients and in anatomic total shoulder arthroplasty (ATSA) and reverse total shoulder arthroplasty (RTSA) subgroup analyses. In the index RTSA subgroup, aseptic loosening was associated with female sex (P = .005). Seventeen of 39 shoulders (44%) that underwent either index ATSA or RTSA demonstrated concomitant glenoid loosening. The absence of glenoid loosening was associated with aseptic humeral loosening in index ATSA and RTSA (P < .001).

CONCLUSION

Fifty-two % of revision shoulder arthroplasty cases with humeral loosening performed at our institution were aseptic. There appear to be distinct demographic and radiographic factors that are more commonly associated with aseptic as opposed to septic humeral loosening. Our data demonstrate that demographic predictors of aseptic loosening of RTSA include female sex. The absence of glenoid component loosening is associated with aseptic humeral loosening and concomitant glenoid loosening is associated with septic humeral loosening. Understanding of these factors can guide the preoperative index of suspicion for PJI in the setting of humeral stem loosening.

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Does the proximal humeral bone quality influence alignment after reverse total shoulder arthroplasty with short humeral stems?

PURPOSE

When compared to standard-length humeral stem in reverse total shoulder arthroplasty (RTSA), short humeral stems in RTSA require good proximal humeral metaphyseal bone quality to gain proper and secure fixation during prosthetic implantation. Shorter humeral stems potentially carry more risk of misalignment than standard or long humeral stems. The hypothesis was that misalignment of the short humeral stems is influenced by regional bone quality.

METHODS

RTSA with a short curved humeral stem with neck-shaft angle (NSA) default of 132.5° was reviewed. The study group included 35 cases at a mean age of 75.97 (± 6.23) years. Deltoid-tuberosity index (DTI) was measured to evaluate proximal humeral bone quality. The deltoid tuberosity index was measured at immediately above position of the upper end of the deltoid tuberosity. Stem alignment was given by the angle measured in degrees between the intramedullary humeral shaft axis and the axis of the humeral implant stem.

RESULTS

The patient's mean DTI was 1.37 ± 0.16 (median, 1.32; range, 1.12-1.80). 22 patients had poor bone quality (DTI < 1.4), compared to 13 patients with acceptable bone quality (DTI > 1.4). After RTSA, ten humeral components (29%) were neutrally aligned, whereas 25 humeral components (71%) were misaligned. There was no correlation between misalignment and DTI (r = 0.117; p = 0.504). But there was a strong correlation between misalignment and the patient's own NSA (r = - 0.47; p = 0.004). The postoperative stem position and stem misalignment are not associated with functional outcomes (p > 0.05).

CONCLUSION

The misalignment of the short curved humeral stem frequently occurs. Poor reginal humeral bone quality does not influence misalignment after RTSA with a short humeral stem. Postoperative stem alignment is associated with the patient's preoperative NSA and method of neck cut. The misalignment does not affect functional outcomes for midterm follow-up. Further long-term follow-up studies are needed to confirm its clinical relevance.

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

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

Great tuberosity fixation does not affect healing and clinical outcomes in RSA performed in proximal humeral fractures in elderly patients

PURPOSE

Aims of our study were to define whether the great tuberosity (GT) positioning fixation in reverse shoulder arthroplasty (RSA) after proximal humeral fracture (PHF) could predict tuberosity healing and its impact on clinical outcomes.

METHODS

We enrolled 59 patients treated with cementless reverse shoulder arthroplasty after PHF in our institute between 2012 and 2018. The mean follow-up was 57 months (± 23.4). We divided patients into two groups according to GT positioning after fixation: Group 1 GT in contact and Group 2 GT detached at least 1 mm from humeral diaphysis. Clinical and radiographic evaluations were conducted at last follow-up.

RESULTS

Overall GT healing rate was 64.4%, (Group 1 70.7%-Group 2 50%). A statistically significant difference (P = 0.047) was found in cortical thickness narrowing at one-third of stem length. We found a correlation between lateral cortical narrowing and GT fixation in non-anatomical position, but we observed no statistically significant differences about GT healing according to GT anatomical or non-anatomical fixation. No differences were found in shoulder function in patients whose tuberosity was healed or failed to heal.

CONCLUSION

GT reduction is not a predictive factor for GT healing; external stress shielding, instead, seems to be decreased in patients with postoperative anatomically reduced GT. In our study, GT healing did not affect clinical outcomes or patient's satisfaction in elderly low-demanding patients.

Best-Fit Circle for the Replication of Humeral Head Anatomy in Total Shoulder Arthroplasty

Background

Anatomic restoration of the humeral head is critical for successful shoulder replacement. Accurate measurements of the humeral head are essential for anatomic substitution.

Purpose

To evaluate whether a best-fit circle of the humeral head, as determined from different projections of plain radiographs, can predict the humeral head implant size for either the left or right shoulder.

Study Design

Descriptive laboratory study.

Methods

Bilateral shoulder radiographs of 200 patients without arthropathy or other abnormal findings of the humeral head were evaluated. The best-fit circle was obtained based on 3 points: the medial and lateral endpoints of the anatomic neck and the lateral cortex below the greater tuberosity. This circle was drawn on 5 different radiographic projections (shoulder anteroposterior [AP], glenoid AP, outlet, axillary, and 30° caudal tilt) of the left and right shoulders of each patient, and the radius of each circle was measured. Agreement in the best-fit circle radius between the left and right shoulders was statistically analyzed using the intraclass correlation coefficient (ICC). There were 2 independent blinded observers who performed each measurement twice to evaluate inter- and intraobserver reliability.

Results

Overall agreement in the radius between the right and left shoulders was excellent (all ICCs ≥0.990). The ICCs according to the radiographic view were 0.990 (95% CI, 0.986-0.993) for shoulder AP, 0.992 (95% CI, 0.989-0.995) for glenoid AP, 0.996 (95% CI, 0.994-0.997) for outlet, 0.994 (95% CI, 0.991-0.996) for axillary, and 0.993 (95% CI, 0.990-0.995) for 30° caudal tilt. Interobserver ICCs demonstrated a high level of precision: 0.987 (95% CI, 0.978-0.993) for shoulder AP, 0.986 (95% CI, 0.974-0.992) for glenoid AP, 0.974 (95% CI, 0.954-0.985) for outlet, 0.991 (95% CI, 0.984-0.995) for axillary, and 0.987 (95% CI, 0.977-0.993) for 30° caudal tilt. Intraobserver ICCs demonstrated excellent test-retest reliability: 0.983 (95% CI, 0.970-0.991) for shoulder AP, 0.989 (95% CI, 0.980-0.994) for glenoid AP, 0.987 (95% CI, 0.978-0.993) for outlet, 0.985 (95% CI, 0.973-0.991) for axillary, and 0.970 (95% CI, 0.947-0.983) for 30° caudal tilt.

Conclusion

The best-fit circle to calculate the ideal size of a humeral head implant was able to be determined from different projections of plain radiographs.

Clinical Relevance

Anatomic restoration of a deformed humeral head can be achieved using the best-fit circle of the contralateral humeral head as obtained from plain radiographs. This method can facilitate preoperative planning and postoperative evaluation in the anatomic restoration of the shoulder to avoid the problems of overstuffing.

Influence of muscle traction on the primary stability of a reverse humeral prosthesis

Background

Currently, the influence of muscle traction on the postoperative stability of humeral prostheses is not adequately researched. This study analyzed the prosthesis' stability in vitro during muscle traction considering different bone defect sizes.

Methods

The reverse humeral prosthesis "AEQUALIS™ ADJUSTABLE REVERSED" (Stryker) was implanted using press-fit into ten bones with a length of 200 mm and 160 mm. Subsequently, the models were torqued in 30 cycles using a universal testing machine (2 Nm - 6 Nm) and loaded axially to simulate muscle traction. The axial weight increased from 7.7 kg (pure muscle traction) over 40 kg (45-degree abduction) to 69.3 kg (90-degree abduction). The prosthesis' relative micromotion was simultaneously measured at three different measurement heights using high-sensitivity displacement transducers and compared to the relative micromotion without axial load.

Results

It was found that a larger torsional moment was associated with a larger relative micromotion in both bone defects studied. However, the influence became significant (P < 0.014) in bone models with predominantly larger defect.Furthermore, no significant influence of muscle traction on relative micromotion could be detected for the larger bone models at any of the measurement levels (P = 1.000). In contrast, smaller bones showed no significant differences in muscle traction until a torsional moment of 6 Nm (P < 0.028).

Conclusion

In conclusion, a larger torsional moment is associated with a higher relative micromotion and muscle traction, conclusively, has no effect on the primary stability of the reverse prosthesis for a 200 mm bone in vitro.

Reverse Total Shoulder Arthroplasty with a Cementless and Metaphyseal Stem Fixation Is a Viable Option for the Treatment of Proximal Humeral Fractures with Calcar Involvement

BACKGROUND

The purpose of the study was to evaluate the suitability of reverse total shoulder arthroplasty (RTSA) with a cementless and metaphyseal stem fixation as a treatment for complex proximal humeral fractures (PHFs) with a calcar fragment when this may be fixed with a steel wire cerclage. Clinical and radiographic outcomes were compared with the same RTSA for PHFs without a calcar fragment at a minimum of five-year follow-up.

METHODS

A retrospective analysis was performed on acute PHFs "with a medial calcar fragment" (group A) and "without a calcar fragment" (group B) treated with a RTSA and cementless metaphyseal stem fixation.

RESULTS

At an average follow-up of 6.7 years (5-7.8 years), no statistical difference was observed comparing group A (18 patients) to group B (50 patients) for active anterior elevation (141 ± 15° vs. 145 ± 10°, p = 0.67), active external rotation ER1 (49 ± 15° vs. 53 ± 13°, p = 0.55), and active internal rotation (5 ± 2 vs. 6 ± 2, p = 0.97). Similarly, a comparison of ASES score (89.2 ± 10 vs. 91.6 ± 9, p = 0.23) and Simple Shoulder Test score (91.1 ± 11 vs. 90.4 ± 10, p = 0.49) revealed no significant difference.

CONCLUSION

RTSA with a cementless and metaphyseal stem fixation represents a safe and feasible treatment for complex PHFs with a medial calcar fragment when this may be fixed with a steel wire cerclage.

Stemless components lead to improved radiographic restoration of humeral head anatomy compared with short-stemmed components in total shoulder arthroplasty

BACKGROUND

Restoring the native center of rotation (COR) in total shoulder arthroplasty (TSA) has been shown to improve postsurgical function, subjective outcomes, and implant longevity. The primary purpose of this study was to compare postoperative radiographic restoration of the humeral COR between short-stem and stemless humeral implants by evaluating the mean COR shift between the 2 techniques. Secondary outcomes evaluated were comparisons of COR shift outliers, humeral head implant thickness and diameter, direction of COR shift, and neck-shaft angle (NSA).

METHODS

This study was a multicenter retrospective comparative study using a consecutive series of primary anatomic TSA patients who received either a short-stem or stemless humeral implant. Radiographically, COR and NSA were measured by 2 fellowship-trained surgeons using the best-fit circle technique on immediate postoperative Grashey radiographs.

RESULTS

A total of 229 patients formed the final cohort for analysis that included 89 short stems and 140 stemless components. The mean COR shift for short stems was 2.7 mm (±1.4 mm) compared with 2.1 mm (±0.9 mm) for stemless implants (P < .001). The percentage of short-stem implant patients with a >2 mm COR difference from native was 66.0% (n = 62) compared with 47.4% (n = 64) for stemless (P = .006). The percentage of short-stem patients with a >4 mm COR difference from native was 17.0% (n = 16) compared with 3.0% (n = 4) for stemless (P < .001). The mean humeral implant head thickness for short stems was 18.7 ± 2.2 mm compared with 17.2 ± 1.3 mm for stemless implants (P < .001). The mean humeral head diameter for short stems was 48.7 ± 4.4 mm compared with 45.5 ± 3.5 mm for stemless implants (P < .001). The NSA for the short-stem cohort was 136.7° (±3.6°) compared with 133.5° (±6.0°) for stemless (P < .001).

CONCLUSIONS

Stemless prostheses placed during TSA achieved improved restoration of humeral head COR and were less likely to have significant COR outliers compared with short-stem implants.

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.

Use of a locking stem for reverse shoulder arthroplasty is a rare but reliable option

INTRODUCTION

RSA is widely used in the treatment of complex trauma or degenerative changes of the shoulder. Strong primary fixation of the stem is necessary to prevent any loosening of the stem and subsequent revision. Presently, cement fixation or press-fit fixation are two options for humeral fixation, though each has its own limitations and risks. The aim of the current study is to evaluate the effectiveness of an alternative option involving a distal screw interlocking system for fixation of the humeral stem from initial implantation.

METHODS

We performed a retrospective multicenter study of patients implanted with the Humelock Reversed® stem RSA that can be locked with distal humeral screws in cases of operative poor press fit or to modulate the lengthening of the arm via prosthetic humeral height. Seventy-two patients with a minimum two year follow-up were included, 13 for acute trauma, 42 for degenerative changes, and 17 for revision surgery.

RESULTS

No difference was seen in radiological or clinical results for patients with or without interlocking screw primary stabilization. For non-trauma patients, the mean raw Constant score improved significantly from 31 (± 12) to 71 (± 12). For trauma patients, the mean raw Constant score for trauma (63.4) was significantly lower than for non-trauma cases (72.1) (p < 0.001). Analysis of the filling ratio demonstrated that interlocking screws were not used for lower filling ratios and that midterm fixation of the stem is not negatively impacted by distal interlocking screw fixation.

DISCUSSION

Even if use of a distal interlocking screw fixation system is rare, it can be useful for patients with poor quality fixation of stemmed RSA.

CONCLUSION

Use of an interlocking screw system to stabilize the stem in RSA provides good immediate and midterm stability of the implant allowing for clinical and radiological outcomes comparable to those obtained with press-fit fixation alone.

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

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

Stemless reverse total shoulder arthroplasty: a systematic review

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Specific Design of a Press Fit Humeral Stem Provides low Stress Shielding in Reverse Shoulder Arthroplasty at minimum 5 Years FU

Press fit fixation is becoming more popular in RSA to preserve, in theory, bone capital. Several studies report that bone resorption can be very high around humeral stems depending on their size, shape and mode of fixation. The aim of the current study is to mid-term follow-up clinical and radiological result of a press fit ovoid regular stem RSA in non acute trauma cases.

Fracture-Dedicated Prosthesis Promotes the Healing Rate of Greater Tuberosity in Reverse Shoulder Arthroplasty: A Meta-Analysis

Introduction: Reverse shoulder arthroplasty (RSA) is becoming popular in the treatment of complex proximal humeral fractures (PHFs). Greater tuberosity healing may influence functional outcomes and range of motion (ROM) of shoulder after RSA. In addition, the design of prosthesis may impact the healing rate of greater tuberosity. The purpose of this study is to know: (1) does the healing of greater tuberosity affect the functional outcomes and ROM of shoulder? and (2) does the design of prosthesis affect the healing rate of greater tuberosity? Materials and Methods: PubMed, Ovid/Embase, and the Cochrane Library were searched for studies comparing the clinical outcomes between the healed groups and the non-healed groups after RSA. Results: For functional outcomes, the results showed that the healed group had better Constant scores (CSs) (p < 0.0001). For ROM, the healed group showed better flexion (p < 0.0001), abduction (p = 0.02), and external rotation (p < 0.00001) of shoulder. For the design of prosthesis, the mean healing rate of greater tuberosity (82.7%) in patients with fracture-dedicated prosthesis was higher than those (63.0%) in patients with standard prosthesis. Subgroup analyses showed that the CS (p = 0.12) and abduction (p = 0.96) of patients using fracture-dedicated prostheses were not different between the healed groups and the non-healed groups. Meta-regression showed that there was no significant relationship between the design of prosthesis and CS (p = 0.312), flexion (p = 0.422), or external rotation (p = 0.776). Conclusion: Our meta-analysis showed that the healed groups could obtain better functional outcomes and ROM than the non-healed groups. In addition, fracture-dedicated prostheses promoted the healing rate of greater tuberosity. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020157276, PROSPERO: CRD42020157276.

Failed Reverse Total Shoulder Arthroplasty: What Are Our Bailouts?

PURPOSE OF REVIEW

As the population continues to age and indications continue to expand, the number of reverse total shoulder arthroplasty (RSTA) procedures has increased significantly. While RTSA is an effective solution to many shoulder problems, it is not without complications. Furthermore, as the number of RTSA procedures increases, so will the number of complications following this procedure. While some complications can be managed with revision RTSA, there are some complications that, unfortunately, cannot. The purpose of this review is to discuss the revision options for failed RTSA.

RECENT FINDINGS

While there has been a significant amount of recent literature surrounding RTSA, much of this literature has been aimed at improving outcomes for primary RTSA by improving glenoid placement, maximizing range of motion, etc., or improving outcomes following conversion of another surgery to RTSA [1••, 2, 3]. There has been little evidence surrounding options for failed RTSA that cannot be salvaged to a revision RTSA. These options are limited and often involve resection arthroplasty and hemiarthroplasty, although neither option provides patients with significant function of the shoulder [4, 5•]. Complications following RTSA are becoming more common as the number of RTSA continues to increase. Furthermore, as the indications for RTSA expand, the complications will continue to increase as this implant is used to tackle more difficult problems about the shoulder. When possible, the etiology of the problem with the RTSA should be addressed and may involve component revision, bone grafting, etc. When the problem cannot be solved with revision RTSA, then the patient can be converted to a hemiarthroplasty, or have a resection arthroplasty, with the understanding that their shoulder function will be limited.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Biomechanics of anatomic and reverse shoulder arthroplasty

The biomechanics of the shoulder relies on careful balancing between stability and mobility. A thorough understanding of normal and degenerative shoulder anatomy is necessary, as the goal of anatomic total shoulder arthroplasty is to reproduce premorbid shoulder kinematics.With reported joint reaction forces up to 2.4 times bodyweight, failure to restore anatomy and therefore provide a stable fulcrum will result in early implant failure secondary to glenoid loosening.The high variability of proximal humeral anatomy can be addressed with modular stems or stemless humeral components. The development of three-dimensional planning has led to a better understanding of the complex nature of glenoid bone deformity in eccentric osteoarthritis.The treatment of cuff tear arthropathy patients was revolutionized by the arrival of Grammont's reverse shoulder arthroplasty. The initial design medialized the centre of rotation and distalized the humerus, allowing up to a 42% increase in the deltoid moment arm.More modern reverse designs have maintained the element of restored stability but sought a more anatomic postoperative position to minimize complications and maximize rotational range of motion. Cite this article: EFORT Open Rev 2021;6:918-931. DOI: 10.1302/2058-5241.6.210014.

A comparison of patient-specific instrumentation to navigation for conducting humeral head osteotomies during shoulder arthroplasty

Background

The humeral head osteotomy during shoulder arthroplasty influences humeral component height, version and possibly neck-shaft angle. These parameters all potentially influence outcomes of anatomic and reverse shoulder replacement to a variable degree. Patient-specific guides and navigation have been studied and utilized clinically for glenoid component placement. Little, however, has been done to evaluate these techniques for humeral head osteotomies. The purpose of this study, therefore, was to evaluate the use of patient-specific guides and surgical navigation for executing a planned humeral head osteotomy.

Methods

The DICOM images of 10 shoulder computed tomography scans (5 normal and 5 osteoarthritic) were used to print 3D polylactic models of the humerus. Each model was duplicated, such that there were 2 identical groups of 10 models. After preoperative planning of a humeral head osteotomy, Group 1 underwent osteotomy via a patient-specific guide, while group 2 underwent a real time navigated osteotomy with an optically tracked sagittal saw. The cut height (millimeters), version (degrees) and neck-shaft angle (degrees) were recorded and statistically compared between groups.

Results

There were no statistically significant differences between patient-specific guides and navigation for osteotomy cut height (P = .45) and humeral version (P = .059). Navigation, however, resulted in significantly less neck-shaft angle error than the patient specific guides (P = .023). Subgroup analysis of the osteoarthritic cases showed statistical significance for navigation resulting in less version error than the patient specific guides (P = .048).

Conclusion

No significant differences were found between patient specific guides and navigation for recreation of the preoperatively planned humeral head cut height and version. Neck-shaft angle, however, had significantly less deviation from the preoperative plan when conducted with navigation.

The effect of humeral implant thickness and canal fill on interface contact and bone stresses in the proximal humerus

Background

Stem size is an important element for successful time zero primary fixation of a press-fit humeral stem in shoulder arthroplasty. Little basic science research, however, has been conducted on the effects of implant thickness and canal fill on load transfer, contact, and stress shielding. The purpose of this finite element study was to determine the effects of varying stem thickness on bone contact, bone stresses, and bone resorption owing to stress shielding.

Methods

Three generic short-stem implant models were developed and varied based on cross-sectional thickness (thinner - 8 mm, medium - 12 mm, thicker - 16 mm). Using a finite element model, three outcome measures were determined (1) the amount of bone-to-implant contact, (2) changes in cortical and trabecular bone stresses from the intact state, and (3) changes in cortical and trabecular strain energy densities which can predict bone remodeling or stress shielding.

Results

Increasing the size of the humeral stem had no significant effects on bone-to-implant contact during loading (P > .07). The thinner implant with the lowest canal fill ratio produced significantly lower changes in stress from the intact state in both cortical and trabecular bone (P < .002). In addition, the thinner implant resulted in a substantially lower volume of bone predicted to stress shield and resorb when compared with the medium and thicker stems.

Discussion

The results demonstrate that thinner implants and lower canal fill may be beneficial over thicker sizes, provided equal initial fixation can be achieved. The thinner implant has a greater degree of load sharing and increases the mechanical load placed on surrounding bone, reducing the risk of stress shielding and bone resorption.

Factors Influencing Appropriate Implant Selection and Position in Reverse Total Shoulder Arthroplasty

Reverse shoulder arthroplasty has increased in popularity and has provided improved but somewhat variable results. These variable outcomes may be related to many factors, including implant design, component positioning, specific indication, and patient anatomy. The original Grammont design provided a solution to the high failure rate at the time but was found to have a high rate of scapular notching and poor restoration of rotation. Modern lateralized designs are more consistent in reducing scapular notching while improving range of motion, especially in regards to external rotation. This review article summarizes the effects of modern reverse shoulder prostheses on outcomes.

Radiographic humeral head restoration after total shoulder arthroplasty: does the stem make a difference?

BACKGROUND

Humeral stem designs for total shoulder arthroplasty have varied over the years, with a recent trend toward shorter stems. The purpose of this study was to examine the impact of humeral component stem length on the ability to restore the native humeral head anatomy.

METHODS

We performed a retrospective review including patients who underwent total shoulder arthroplasty for primary osteoarthritis between 2007 and 2017 with complete operative reports and adequate radiographs. Surgical data including stem design were collected. Preoperative and postoperative radiographic measurements of the center of rotation (COR), humeral head height (HH), and neck-shaft angle were performed. Restoration of the native humeral anatomy was deemed "acceptable" based on postoperative differences in the COR ≤ 3 mm, HH ≤ 5 mm, and neck-shaft angle > 130°. Deviations between preoperative and postoperative measurements were compared across stem types. All available 2-year stemless implant radiographs were also analyzed.

RESULTS

In total, 261 patients were included, with 31 stemless, 43 short-stem, and 187 standard-stem implants. There was no significant difference in COR restoration in the x-axis direction (P = .060) or y-axis direction (P = .579). There was no significant difference in restoration of acceptable HH by stem type (P = .339). Stemless arthroplasty implants were more likely to be placed in varus (22.6%) compared with short-stem (7.0%) and standard-stem (3.7%) designs (P < .001).

CONCLUSION

Restoration of humeral anatomic parameters occurred significantly less with stemless implants than with short- and standard-stem implants. The stem of a shoulder arthroplasty implant aids surgeons in accurately restoring patient-specific anatomy.

Simultaneous removal of a locking plate and implantation of a reversed shoulder prosthesis in elderly patients suffering from fracture sequelae of the proximal humerus

PURPOSE

Open reduction and internal fixation with a locking plate are performed frequently to treat fractures of the proximal humerus. Avascular necrosis and non-union or malunion are potential complications of this procedure, which lead to specific fracture sequelae. The aim of this study was to investigate the clinical and radiological results of patients treated by removal of a failed locking plate of the proximal humerus and simultaneous implantation of a reverse total shoulder prosthesis.

METHODS

Twenty-one patients (f = 17, m = 4; mean age 70 years) out of 29 patients were available for follow-up after a mean period of 45 (30-65) months. At follow-up, all patients were assessed with the constant score and the ASES score as well as plain radiographs.

RESULTS

In comparison with the preoperative values, abduction (31° vs. 115°; p < 0.001) and forward flexion (34° vs. 121°; p < 0.001) improved until follow-up, while the pain score on a visual analog scale decreased (6.7 vs. 0.9; p < 0.001). At follow-up, the mean ASES score rated 73 and the constant score rated 62. The radiologic findings included scapular notching (n = 7; 33%), radiolucency (n = 4; 19%), heterotopic ossifications (n = 3; 14%), and stress shielding (n = 4; 19%).

CONCLUSION

Reverse total shoulder arthroplasty is a useful instrument for the treatment of failed locking plate osteosynthesis of the proximal humerus in elderly patients. The patients benefit from both pain relief and improved shoulder function. The rate of radiologic changes like scapular notching, radiolucency, stress-shielding and heterotopic ossifications at follow-up is notable.

Eclipse stemless shoulder prosthesis vs. Univers II shoulder prosthesis: a multicenter, prospective randomized controlled trial

BACKGROUND

Total shoulder arthroplasty is an accepted treatment for glenohumeral osteoarthritis. The Arthrex Eclipse shoulder prosthesis is a stemless, canal-sparing humeral prosthesis with bone ingrowth capacity on the trunnion, as well as through the fenestrated hollow screw, that provides both diaphyseal and metaphyseal load sharing and fixation.

METHODS

Between 2013 and 2018, 16 sites in the United States enrolled 327 patients (Eclipse in 237 and Arthrex Univers II in 90). All patients had glenohumeral arthritis refractory to nonsurgical care. Strict exclusion criteria were applied to avoid confounding factors such as severe patient comorbidities, arthritis not consistent with osteoarthritis, and medical or prior surgical treatments that may have affected outcomes. Patients were randomized to the Eclipse or Univers II group via block randomization.

RESULTS

In total, 149 Eclipse and 76 Univers II patients reached 2-year follow-up (139 Eclipse patients [93.3%] and 68 Univers II patients [89.5%] had complete data). The success rate using the Composite Clinical Success score was 95% in the Eclipse group vs. 89.7% in the Univers II group. No patient exhibited radiographic evidence of substantial humeral radiolucency, humeral migration, or subsidence at any point. Reoperations were performed in 7 patients (3.2%) in the Eclipse group and 3 (3.8%) in the Univers II group.

CONCLUSION

The Arthrex Eclipse shoulder prosthesis is a safe and effective humeral implant for patients with glenohumeral arthritis at 2-year follow-up, with no differences in outcomes compared with the Univers II shoulder prosthesis.

Radial to Axillary Nerve Transfer Outcomes in Shoulder Abduction: A Systematic Review

Background

Brachial plexus and axillary nerve injuries often result in paralysis of the deltoid muscle. This can be functionally debilitating for patients and have a negative impact on their activities of daily living. In these settings, transferring the branch of the radial nerve innervating the triceps to the axillary nerve is a viable treatment option. Additional nerve transfers may be warranted. This study sought to determine the efficacy of nerve transfer procedures in the setting of brachial plexus and axillary nerve injuries and factors affecting clinical outcomes.

Methods

The U.S. National Library of Medicine's website "PubMed" was queried for "radial to axillary nerve transfer" and "brachial plexus nerve transfer." An initial review by two authors was performed to identify relevant articles followed by a third author validation utilizing inclusion and exclusion criteria. Individual patient outcomes were recorded and pooled for final analysis.

Results

Of the 80 patients, 66 (82.5%) had clinical improvement after surgical nerve transfer procedures. Significant difference in clinical improvement following nerve transfer procedures was correlated with patient age, mechanism of injury, brachial plexus vs isolated axillary nerve injuries, multiple nerve transfers vs single nerve transfers, and surgery within the first 7 months of injury. The branch of the radial nerve supplying the triceps long head showed improved clinical results compared with the branch of the radial nerve supplying the triceps medial head and anconeus.

Conclusion

Nerve transfers have been shown to be effective in restoring shoulder abduction in both isolated axillary nerve injuries and brachial plexus injuries.

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

Background

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

Methods

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

Results

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

Conclusions

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

Proximal humeral osteolysis and glenoid radiolucent lines in an anatomic shoulder arthroplasty: a comparison of a ceramic and a metal humeral head component

BACKGROUND

In vitro wear studies demonstrate decreased polyethylene wear with a ceramic compared with a metal humeral head. In this in vivo study, we analyzed prospectively collected 5-year data, comparing the outcomes of 2 types of humeral implants.

METHODS

Sixty-two anatomic total shoulder arthroplasties (TSAs) (59 patients) were performed using the same glenoid component and 2 types of modular humeral implants (metal-head long-stem prosthesis in group A vs. ceramic-head stemless prosthesis in group B). Radiographic analysis for proximal humeral osteolysis and glenoid component radiolucent lines was performed at an average of 5.5 years. Functional outcomes were prospectively evaluated according to the visual analog scale score for pain; satisfaction level; American Shoulder and Elbow Surgeons score; active elevation; Shoulder Pain and Disability Index score; and Disabilities of the Arm, Shoulder and Hand score.

RESULTS

There were 39 TSAs in group A (mean age, 68.1 years) and 23 TSAs in group B (mean age, 67 years). Clinical improvement was similar for both groups. Some proximal humeral osteolysis occurred in 56% of all TSAs. Group A showed increased osteolysis compared with group B (72% vs. 30%, P = .005). Glenoid radiolucent lines were far more frequent in group A, and group A showed a direct relationship between the extent of humeral osteolysis and the severity of glenoid radiolucent lines (P < .001).

CONCLUSION

The stemless ceramic-head replacements showed fewer glenoid radiolucent lines and less humeral osteolysis than the long-stem metal-head replacements. In the group with metal-head replacements, correlation was shown between glenoid radiolucent lines and humeral osteolysis.

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

Background

Humeral stem length in anatomic total shoulder arthroplasty (TSA) continues to decrease in an attempt to preserve bone. Outcomes following short-stem TSA are not well documented. The purpose was to systematically review and report the outcomes and revisions following short-stem humeral implants for TSA.

Methods

A systematic review was registered with PROSPERO and performed with PRISMA guidelines using 3 publicly available free databases. Therapeutic clinical outcome investigations reporting TSA outcomes of short-stem implants with levels of evidence I-IV were eligible for inclusion. All study, subject, and surgical technique demographics were analyzed and described.

Results

Thirteen studies were included (average follow-up: 33 months, range 24-84 months; 8 studies [62%] were multicenter and 6 [46%] were from Europe). All studies were published in the last 8 years, and almost all (12/13, 92%) reported results of uncemented components. Most of the studies (9/13, 70%) reported results from the Aequalis Ascend or Ascend Flex Stem (Tornier). Improvements were seen in all measured range of motion planes and patient-reported outcome scores. Complications were infrequent, with a 2% humeral loosening rate, a 3% overall revision rate, and a 1% rate of revision for aseptic humeral loosening. Radiographic results showed a 13% rate of radiolucent lines, a 16% rate of condensation lines, and a 22% rate of calcar osteolysis.

Conclusion

Short-stem TSA humeral implants provide excellent results, with low revision rates in the short term. Long-term follow-up will be necessary to understand the clinical impact of radiographic calcar osteolysis.

Shoulder and elbow arthroplasty after ipsilateral fractures of the proximal and distal humerus in the elderly

PURPOSE

The aim of this paper was to present our experience and the outcomes in 3 elderly patients who underwent combined shoulder and elbow arthroplasty after ipsilateral fractures of the proximal and distal humerus in our center. Also, we evaluate difficulties in their treatment and report their final follow-up.

MATERIAL AND METHODS

Three cases of elderly patients who underwent shoulder and elbow arthroplasty after ipsilateral fractures of the proximal and distal humerus were reviewed. Demographic, clinical, and radiological data were analyzed. Also, Constant Shoulder Score, Mayo Elbow Performance Score, Short-Form Health Survey, and four-point Likert scale were evaluated.

RESULTS

All patients were females (100%). Mean age was 75 years (range 73-78). Mean follow-up was 36.6 months (SD 11.5). Mean time between injury and surgery was 12 days (SD 7.6). The 3 patients had a displaced and comminuted fracture of the humeral head (4-part, by Neer classification) and a comminuted intraarticular fracture of the distal humerus (13-C3, by AO classification). One patient presented a wound infection that required debridement. Despite the complications, at final follow-up, all patients showed a sufficient capacity to perform comfortably in their daily activities. Radiographs showed good fixation of all components, without evidence of prosthetic loosening or migration. All evaluated scores had good or excellent results.

CONCLUSIONS

Our study provides further evidence that the shoulder and elbow arthroplasty could be a reliable management for ipsilateral fractures of the proximal and distal humerus in the elderly. In our study, this technique showed in the final follow-up patient's good outcomes.

Radiographic outcomes of impaction-grafted standard-length humeral components in total shoulder and ream-and-run arthroplasty: is stress shielding an issue?

BACKGROUND

The purpose of this study was to evaluate humeral stress shielding in shoulder arthroplasties performed with a smooth, standard-length humeral stem fixed with impaction autografting.

METHODS

Two-year outcomes were evaluated for 48 ream-and-run arthroplasties and 78 total shoulder arthroplasties (TSAs) performed at a single institution. Postoperative radiographs were analyzed for adaptive changes, calcar osteolysis, and component shift or subsidence. Radiographic outcomes were analyzed for associations with patient demographic characteristics, humeral stem filling ratios, and glenoid loosening; clinical outcomes were assessed using the Simple Shoulder Test.

RESULTS

At 2 years after surgery, the ream-and-run procedures showed partial calcar osteolysis in 9 cases (19%). The TSAs showed partial calcar osteolysis in 19 cases (24%) and complete calcar osteolysis in 2 (3%). Humeral component subsidence or component shift was observed in 3 ream-and-run procedures (6%) and in 8 TSAs (10%). These radiographic findings were not significantly associated with patient demographic characteristics, canal-filling ratios, or clinical outcomes.

CONCLUSION

When inserted with impaction autografting, a smooth, standard-length humeral stem offers a secure bone-preserving approach for humeral component fixation in shoulder arthroplasty. These results with a conventional prosthesis can serve as a basis for comparison for new component designs and fixation methods.

18F FDG-PET/CT has poor diagnostic accuracy in diagnosing shoulder PJI

PURPOSE

Chronic low-grade periprosthetic joint infection (PJI) of a shoulder replacement can be challenging to diagnose. 18F-FDG PET/CT is suggested as a modality to diagnose lower-limb PJI, but no studies on shoulder replacements exist. The aim of this study was therefore to determine the diagnostic accuracy of 18F-FDG PET/CT in diagnosing chronic PJI of the shoulder.

METHODS

Patients evaluated for a failed shoulder replacement during a 3-year period were prospectively included in the study. All patients underwent pre-operative 18F-FDG PET/CT, and were evaluated for signs of infection by three independent reviewers using shoulder-specific criteria. Interrater-agreement was calculated between the reviewers. If the patient had revision surgery, biopsy specimens were obtained and cultured with bacterial growth in the cultures serving as gold standard of infection.

RESULTS

A total of 86 patients were included in the study. Nine patients were 18F-FDG PET/CT positive for infection, with only three true positive. Using the gold standard, infection was diagnosed after revision surgery in 22 cases. All infections were chronic and caused by low-virulent microbes. The sensitivity of 18F-FDG PET/CT was 0.14 95% CI (0.03-0.36), specificity 0.91 95% CI (0.81-0.97), positive predictive value was 0.40 95% CI (0.15-0.71) and negative predictive value 0.71 95% CI (0.67-0.75). The inter-observer agreement was 0.56 (Fleiss' kappa), indicating moderate agreement of the visual FDG-PET evaluation using the shoulder-specific criteria.

CONCLUSION

18F-FDG PET/CT has poor diagnostic accuracy in diagnosing low-grade PJI of the shoulder. 18F-FDG PET/CT cannot be recommended as a part of the routine preoperative workup to diagnose low-grade infection of a shoulder replacement.

Primary Monoblock Inset Reverse Shoulder Arthroplasty Resulted in Decreased Pain and Improved Function

BACKGROUND

The first-generation, lateral-center-of-rotation reverse shoulder arthroplasty (RSA) modular design has demonstrated durable early-, mid-, and long-term outcomes. The second-generation monoblock implant shares a similar design but eliminates the modular junction and facilitates inset placement within the metaphysis to avoid humeral-sided junctional failures and facilitate metaphyseal press-fit. However, no paper has specifically examined the radiographic findings and improvements in pain and function after the use of this next generation design.

QUESTIONS/PURPOSES

(1) After second-generation, lateral-center-of-rotation monoblock RSA, what are the improvements in shoulder scores, general health scores, and ROM at a minimum of 2 years of followup? (2) Are the differences in shoulder scores, health scores, and ROM associated with fixation (cemented versus cementless components)? (3) How frequently do complications occur (defined as humeral loosening, dislocation, baseplate failure, scapular notching, acromial fractures, and revision surgery) after inset monoblock RSA?

METHODS

We retrospectively studied patients undergoing primary RSA between 2010 and 2015 with preoperative data and a minimum of 2 years of clinical followup. Of the 329 primary RSA performed during this period, 125 were excluded based on the use of a different generation humeral stem of the same design, three based on need for a nickel-free implant, and 39 due to a lack of preoperative shoulder scores. Of the remaining 162 patients, 137 patients (85%) met the inclusion criteria with a mean age of 74 years (range, 46-90 years). The predominant indications were osteoarthritis with a massive rotator cuff tear (74%) and fracture sequelae (16%). During the study, humeral implants were typically inserted using an uncemented press-fit technique (85%), with only 21 patients requiring a cemented humeral stem. The mean clinical and radiographic followup period was 37 months (range, 24-82 months). Patient-reported outcome measures (PROMs) including the Simple Shoulder Test, American Shoulder and Elbow Surgeons Total, VAS for pain, SF-12, Single Assessment Numeric Evaluation, and measured active motion (forward elevation and external and internal rotation) were recorded at pre- and postoperative intervals. Postoperative radiographs were evaluated for baseplate failure, glenoid and humeral loosening, scapular notching, and acromion fractures. Complications were recorded in the longitudinally maintained institutional repository.

RESULTS

At the most recent followup examination, there were improvements in measured motion, general health outcomes, and all PROMs. There were no differences between the cemented and press-fit techniques. Complications observed included 17 of 137 patients (12%) with scapular notching, six postoperative acromion fractures (4%), and two revision procedures (1%). No patients experienced gross humeral loosening or baseplate failure.

CONCLUSIONS

Primary RSA using a second-generation monoblock inset humeral component resulted in improvements in pain and functional outcomes as well as low rates of acromion fractures, humeral radiolucency, and complications. Future studies are needed to provide a more definitive analysis on the use of an uncemented technique for humeral stem fixation and the effect of an inset stem on postoperative acromion fractures.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

3D preoperative planning for humeral head selection in total shoulder arthroplasty

BACKGROUND

Recreation of glenohumeral biomechanics and humeral anatomy has been shown to improve outcomes in shoulder arthroplasty. Recent research has focused on utilizing simulation software and intraoperative instrumentation to improve glenoid implant selection and positioning, but no study had evaluated the reliability of new features in 3D preoperative planning software for humeral planning in total shoulder arthroplasty.

MATERIALS AND METHODS

Preoperative plans were created for 26 patients using three different simulation software programs: an independent preoperative planning simulation (IPPS) software (OrthoVis) and two automated manufacturers preoperative simulation systems: ArthrexVIP™ (AMPS I) and Tornier Blueprint™ 3D Planning (AMPS II). Preoperative plans were compared for reliability and consistency among different software systems based on available variables including humeral head diameter (HD) and head height (HH).

RESULTS

The measured HD was consistent between the three systems with a maximum mean difference of 0.2 mm for HD among IPPS, AMPS I, and AMPS II (p = 0.964). There was a significant difference in measured humeral HH with 1.7 mm difference between IPPS and AMPS II (p ≤ 0.001). The strongest correlation when comparing humeral head measurements (diameter or height) obtained from all systems was seen between IPPS and AMPS I for humeral HD (r = 0.8; p ≤ 0.001).

CONCLUSION

There was a high level of consistency between independent and manufacturer preoperative planning software for humeral head measurements. These preoperative planning systems can improve efficiency and workflow during surgery by guiding surgeons on implant size selection to optimally reconstruct the glenohumeral kinematics, in order to improve patient outcomes.

LEVEL OF EVIDENCE

Level III, study of nonconsecutive patients and without a universally applied "gold" standard study of diagnostic test.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Influence of uncemented humeral stem proximal geometry on stress distributions and torsional stability following total shoulder arthroplasty

Background

While surgeons tend to implant larger stems to improve torsional stability, numerous studies demonstrated that increasing humeral stem diameter could exacerbate stress-shielding and lead to bone resorption. We aimed to determine the influence of humeral stem proximal geometry on stress distributions and torsional stability following total shoulder arthroplasty.

Methods

Preoperative computed tomography scans were acquired from 5 patients and processed to form 3-dimensional models of the proximal humerus. Computer models of 3 generic implants were created based on three designs: predominantly oval, semi-angular, and predominantly angular. All stems shared identical head geometry and differed only in the proximal metaphyseal area. Finite element analyses were performed, with the humerus rigidly constrained distally, and loaded to simulate the joint reaction force. Implant torsional stability and proximal bone stress distributions were assessed for the three different stem designs with three sizes: oversized (stem making contact with the cortical diaphysis), normosized (one increment smaller) and undersized (two increments smaller).

Results

Considering the normosized stems, the angular design increased the physiologic bone stresses at the proximal section by 39–42%, while the oval and semi-angular designs reduced them by 5–9% and 8–13%, respectively. The oval design exhibited a median rotation of 2.1°, while the semi-angular and angular designs exhibited median rotations of 1.8°.

Conclusion

The semi-angular stem granted an adequate compromise between physiologic stress distributed by the oval stem and torsional stability of the angular stem. Surgeons should be aware of the various benefits and drawbacks of the different humeral stem designs to ensure adequate torsional stability and physiologic loading.

Preoperative Comorbidities and Postoperative Complications Do Not Influence Patient-Reported Satisfaction Following Humeral Head Resurfacing: Mid- to Long-term Follow-up of 106 Patients

Background

Humeral head resurfacing (HHR) has emerged as an alternative treatment for glenohumeral osteoarthritis. We investigated the outcomes of HHR using validated patient-reported outcome (PRO) measures.

Methods

A retrospective review was performed on 213 patients who underwent HHR. A PRO follow-up was performed by administering a questionnaire including the American Shoulder and Elbow Society (ASES) score, Brophy activity survey, short form of the Disabilities of the Arm, Shoulder and Hand (quickDASH) survey, and general shoulder function. PRO scores were stratified by comorbidities and complications.

Results

Survey responses were received from 106 patients (51%), with a mean follow-up of 5.6 ± 1.8 years (range: 9 months to 6.1 years). Preoperative comorbidities were associated with significantly higher quickDASH scores. Postoperative complications were associated with significantly higher rates of current pain, higher visual analog scale scores, night pain, lower subjective shoulder values, and lower ASES pain and total scores. No differences in patient satisfaction were identified between the cohorts with and without preoperative comorbidities and between the cohorts with and without postoperative complications.

Conclusion

In our cross-sectional analysis of mid- to long-term outcomes following HHR, preoperative comorbidities, or postoperative complications had no impact on patient-perceived postoperative satisfaction or most PROs. HHR is clinically viable in a wide variety of patients. Future work is necessary to compare the efficacy of HHR compared with more traditional total shoulder arthroplasty and stemmed hemiarthroplasty regarding long-term outcomes and appropriate indications.

Cementless metaphyseal reverse shoulder arthroplasty: our preliminary experience

Reverse shoulder arthroplasty (rTSA) is a largely used procedure with a wide variety of indications. The incidence of this surgery is increased in recent years and the literature expects similar trend for the future. Metaphyseal stem rTSA seems to be a promising solution considering major objectives the preservation of humeral bone stock and ease of revision. In our study we analyzed 19 patients treated with cementless metaphyseal stem rTSA for osteoarthritis (group A) and acute fractures (group B). In group A (7 patients) the average Constant score improved from 21,57 (16-29) to 56,85 (38-72), the average SST improved from 2,29 (1-4) to 9,43 (8-12) and the mean VAS score improved from 14,29 to 4,86. In group B (12 patients) the mean Constant-Murlay score at last follow up was 42,17; the average SST was 7 and average pain score was 8,92. Overall active range-of-motion (ROM) improved significantly. Surgical considerations, clinical (analyzing Constant score and Simple Shoulder Test) and radiological short-term outcomes are encouraging, with low rate of complications. Long term follow-up studies are necessary to confirm our findings and the potential benefits related to these implants. (www.actabiomedica.it)

Bleeding in primary shoulder arthroplasty

INTRODUCTION

The aim of this investigation was to analyse "total blood loss" (TBL), "blood transfusion rate" (BT) and the "amount of transfused blood units" (BU) between the different primary shoulder arthroplasty (SA) types: reverse, anatomical and stemless. Only primary SA was included. Further goal was to identify risk factors for TBL, amount of BU and BT rate.

METHODS

A retrospective charts analysis of patients who received primary SA for degenerative shoulder pathology in our institution between 2004 and 2016 was performed. The demographic data, co-morbidities, haemoglobin and hematocrit level, BT rate, amount of transfused BU etc. were collected. TBL was estimated. Linear regression, log-linear poisson regression and logistic regression were used to compare the outcomes TBL, amount of transfused BU and BT rate, respectively, between different prosthesis types.

RESULTS

Of 278 patients included in this study 209 received reverse, 57 anatomical and 12 stemless SA. Mean TBL was 392.7 ml in reverse, 394.6 ml in anatomical and 298.3 ml in stemless SA. The BT rate and mean amount of BU were, respectively, 14.4% and 0.32 in reverse and 8.77% and 0.23 in anatomical SA. None of the patients with stemless arthroplasty received BT. Significant risk factors for elevated TBL are operation time, higher BMI, male sex. Significant risk parameters for BT and higher amount of transfused BU are low BMI, cemented arthroplasty, coronary heart disease, ASA score > 2 and previous therapy with vitamin K antagonists.

CONCLUSION

Although there were little differences between the blood transfusion rates in reverse vs. anatomical arthroplasty, there was no difference in total blood loss between these different prosthesis types. None of the patients with stemless arthroplasty received blood transfusion. There are various risk factors affecting total blood loss and blood transfusion rate. However, risk parameters influencing blood transfusion may be different to them affecting total blood loss.