The effect of concurrent cervical spine degenerative disease on the outcome of rotator cuff repair: a national database study.

BACKGROUND: Cervical spine degenerative disease (CSD) can cause shoulder pain, potentially confounding the management of patients with rotator cuff tears. This study aimed to investigate the relationships between CSD and rotator cuff repair (RCR). METHODS: A national administrative database (PearlDiver) was used to study 4 patient cohorts: (1) RCR only (RCRo), (2) RCR with concurrent CSD (RCRC), (3) RCR after a cervical spine procedure (RCRA), and (4) RCR before a cervical spine procedure (RCRB). The outcomes of RCR were compared using multivariable logistic regression, controlling for age, sex, and Elixhauser Comorbidity Index, as well as preoperative opioid utilization in the analysis of opioid use. RESULTS: Between 2010 and 2021, a total of 889,977 patients underwent RCR. Of these patients, 784,230 (88%) underwent RCRo whereas 105,747 (12%) underwent RCRC, of whom 21,585 (2.4%) underwent cervical spine procedures (RCRA in 9670 [1.1%] and RCRB in 11,915 [1.3%]). At 2 years after RCR, compared with RCRo patients, RCRC patients had an increased risk of surgical-site infection (adjusted odds ratio [aOR] = 1.25, P = .0004), deep vein thrombosis (aOR = 1.17, P = .0002), respiratory complications (aOR = 1.19, P = .0164), and ipsilateral shoulder reoperations (débridement [aOR = 1.66, P < .0001], manipulation under anesthesia or arthroscopic lysis of adhesions [aOR = 1.23, P < .0001], distal clavicle excision [aOR = 1.78, P < .0001], subacromial decompression [aOR = 1.72, P < .0001], biceps tenodesis [aOR = 1.76, P < .0001], incision and drainage [aOR = 1.34, P = .0020], synovectomy [aOR = 1.48, P = .0136], conversion to shoulder arthroplasty [aOR = 1.62, P < .0001], revision RCR [aOR = 1.77, P < .0001], and subsequent contralateral RCR [aOR = 1.71, P < .0001]). At 2 years, compared with RCRC patients who did not undergo cervical spine procedures, RCRC patients who underwent cervical spine procedures had an increased risk of incision and drainage (aOR = 1.50, P = .0255), conversion to arthroplasty (aOR = 1.40, P < .0001), and revision RCR (aOR = 1.11, P = .0374), as well as a lower risk of contralateral RCR (aOR = 0.89, P = .0469). The sequence of cervical spine procedures did not affect the risk of shoulder reoperations. At 1 year, the risk of opioid use after RCR was less for RCRA patients compared with RCRB patients (aOR = 1.71 [95% confidence interval, 1.61-1.80; P < .0001] vs. aOR = 2.01 [95% confidence interval, 1.92-2.12; P < .0001]). CONCLUSION: Concurrent CSD has significant detrimental effects on RCR outcomes. Patients with concurrent CSD undergoing cervical spine procedures have a greater risk of ipsilateral shoulder reoperations but a decreased risk of contralateral RCR. The risk of prolonged opioid use was lower if RCR followed a cervical spine procedure. Concurrent CSD must be considered and possibly treated to optimize the outcomes of RCR.

Trends in reported outcomes and patient reported outcome measures (PROMs) in humeral shaft fracture literature: a systematic review.

PURPOSE: With a lack of standardization among outcome measures in fracture literature, cross-study comparisons remain limited. This systematic review aimed to identify trends in outcome measures reported by studies of the treatment of humeral shaft fractures. METHODS: A systematic review was performed of studies reporting clinical outcomes of humeral shaft fractures indexed in PubMed. Extracted data included demographics, fracture characteristics, treatment modalities, outcomes, patient reported outcome measures (PROMs), and journal characteristics. Cochran-Armitage tests and linear regressions were used to identify data trends. Pearson chi-square and Kruskal-Wallis tests were used for comparisons between studies. RESULTS: This review included 197 studies with outcomes of 15,445 humeral shaft fractures. 126 studies reported PROMs and 37 different PROMs were used. The Constant Score was most commonly reported (34% of studies), followed by ASES Score (21%), MEPS (21%), and DASH Score (20%). There was a significant increase in PROM usage over time (p = 0.016) and in articles using three or more PROMs (p = 0.005). The number of PROMs were significantly greater in prospective cohort studies and RCTs (p = 0.012) compared to retrospective cohort studies and case series (p = 0.044 for both). Post-treatment shoulder motion was reported in 43% of studies and 34% reported elbow motion. 86% of studies reported complications as an outcome parameter. Time to union and nonunion rate were published in 69% and 88% of studies, respectively. CONCLUSION: This study identified increasing PROM usage over time and disparities in the reporting of outcomes in humeral shaft fracture literature requiring further validation and standardization of available outcome measures.

Biomechanical Comparison of Dual and Posterior Locking Plates in an Ex Vivo Comminuted Olecranon Fracture Model.

PURPOSE: Comminuted olecranon fractures are commonly fixed with posterior locking plates (PLPs). Though biomechanically validated, this method comes with risks of symptomatic implant prominence and wound breakdown. Dual locking plates (DLPs) placed on the medial and lateral surfaces of the olecranon theoretically avoid these risks and allow for fixation of proximal fracture fragments in multiple planes. A biomechanical comparison of DLP and PLP fixation would help to validate the use of DLPs in comminuted olecranon fractures. METHODS: Seven matched pairs of cadaveric upper extremities were evaluated with quantitative computed tomography scans to evaluate bone mineral density (BMD). Osteotomies simulating comminuted olecranon fractures (Mayo Type IIB) were created and the specimens were fixed either with variable angle PLPs or variable angle DLPs. The specimens were then cyclically loaded and loaded to failure. The ultimate strength, fracture displacement, and mechanism of failure were recorded and compared across groups. The correlation between BMD and ultimate strength was analyzed. RESULTS: The mean total BMD was 0.79 g/cm2 (SD, 0.14 g/cm2). No specimen failed during cyclic testing. Five of 7 PLP specimens and 5 of 7 DLP specimens failed by fracture through the proximal screws though in different planes (sagittal vs axial splits, respectively). The mean ultimate strengths of the PLP (1077 N [SD, 462 N]) and DLP (1241 N [SD, 506 N]) groups were similar. There was a linear relationship between ultimate strength and BMD (R2 = 0.33). CONCLUSION: Dual locking plates display biomechanical properties that suggest that they can be used in the fixation of comminuted olecranon fractures. Catastrophic failure of the fixation constructs occurs around stress risers at the proximal screws rather than due to displacement at the fracture itself. CLINICAL RELEVANCE: Dual locking plate constructs can be considered for use in the fixation of comminuted olecranon fractures.

Early outcome of humeral head replacement with glenoid reaming arthroplasty (Ream and Run) for treatment of advanced glenohumeral osteoarthritis.

INTRODUCTION: Long-term outcomes of anatomic total shoulder arthroplasty (aTSA) can be compromised by glenoid loosening and failure. The purpose of this study was to evaluate the short- and midterm outcomes of humeral head replacement with glenoid reaming arthroplasty (Ream and Run) for the treatment of advanced glenohumeral osteoarthritis, and to identify associations between preoperative factors and outcomes. METHODS: Forty-nine shoulders (mean age 60 ± 7 years) with minimum 2-year follow-up (mean 4.6 ± 1.7) were evaluated. Forty-three (87.8%) were male. Thirteen (26.5%) had previous nonarthroplasty shoulder surgery. There were 19 (38.8%) Walch type A and 30 (61.2%) type B glenoids. Pre- and postoperative shoulder motion, patient-reported outcomes (PROMs), and health-related quality of life (HRQoL) were assessed. Pre- and postoperative plain radiographs were evaluated. Mixed effects models were used to investigate factors associated with outcomes. RESULTS: Active forward elevation and active external rotation improved from 111.7° ± 23.8° to 139.2° ± 21.1° and 13.3° ± 20.7° to 38.7° ± 14.7°, respectively (P < .001). The mean American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH), Simple Shoulder Test (SST), and visual analog scale (VAS) shoulder pain scores at the most recent follow-up were 86.6 ± 19.9, 10.1 ± 14.1, 10.5 ± 2.2, and 1.5 ± 2.3, respectively. The mean changes of PROMs were significant and exceeded the minimal clinically important difference for aTSA. The percentage maximal possible improvement for ASES, DASH, and SST were greater than 75%. Male sex (P < .008) and not having prior shoulder surgery (P < .04) were significantly associated with better absolute and greater change in PROMs. Age, preoperative shoulder motion, and Walch glenoid classification were not associated with PROMs. Five (10.2%, 95% confidence interval [CI] 1.8%-18.6%) patients underwent revision for pain. Three additional patients were dissatisfied at final follow-up without undergoing revision, resulting in 16.7% (95% CI 6.1%-27.2%) of patients being dissatisfied with their outcome after their initial RnR. Mean Short Form-6 Dimensions scores improved from 0.66 ± 0.12 to 0.77 ± 0.13 and mean EuroQol-5 Dimensions scores improved from 0.68 ± 0.20 to 0.85 ± 0.17 (P < .001). Improvement in HRQoL was significantly associated with nondominant arm treatment, increased age, and greater preoperative SST score. Annual medialization of the humeral head center of rotation was 0.56 ± 1.6 mm/yr. No radiographic measure was associated with long-term PROMs. CONCLUSION: Ream and Run can provide significant and clinically important improvement in PROMs and HRQoL for a high percentage of patients at short- and midterm follow-up. This procedure is an appropriate alternative to aTSA in select patients.

Equal opportunity for all? An analysis of race and ethnicity in fertility preservation in New York City.

PURPOSE: To compare the racial and ethnic make-up of patients who accessed medically indicated fertility preservation services (MIFP) against the overall racial diversity (including Hispanic origin) across women of reproductive age diagnosed with cancer in New York City (NYC). METHODS: All patients who completed at least one MIFP between January 2017 and December 2018 were reviewed. Race was self-reported. A calculation of the expected racial distribution across women of reproductive age with cancer in NYC was determined using the most recent NYC census data. Statistical analysis included chi-square goodness of fit and test for independence and Kruskal-Wallis H test, with p < 0.05 considered significant. RESULTS: A total of 107 patients who accessed MIFP were included. A total of 55 (51.4%) identified as White, 3 (2.8%) as Black, 13 (12.2%) as Asian, 6 (5.6%) as Hispanic, 3 (2.8%) as other, and 27 (25.2%) did not report. A total of 78.5% of patients had insurance. There was no significant difference in racial distribution by cancer type (p = 0.255). A subgroup analysis excluding the BRCA+ patients and races not reported by the census (n = 69) was then performed, showing a statistically significant difference between observed (O) and expected (E) cases of fertility preservation (FP) by race at our center-White 47O/32E, Black 3O/15E, Asian 13O/7E, and Hispanic 6O/15E (p < 0.001). A statistically significant difference in racial distribution by FP type was observed. CONCLUSIONS: There is a difference in the observed vs expected racial distribution of patients accessing MIFP. Further studies are needed to identify modifiable factors to better ensure equal opportunity to all patients.

Outcome measures reported for the management of proximal humeral fractures: a systematic review.

BACKGROUND: The American Shoulder and Elbow Surgeons multicenter taskforce studying proximal humerus fractures reached no consensus on which outcome measures to include in future studies, and currently no gold standard exists. Knowledge of commonly used outcome measures will allow standardization, enabling more consistent proximal humerus fracture treatment comparison. This study identifies the most commonly reported outcome measures for proximal humerus fracture management in recent literature. METHODS: A systematic review identified all English-language articles assessing proximal humerus fractures from 2008 to 2018 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Review articles, meta-analyses, revision surgery, chronic injuries, studies with <15 patients, studies with <12 month follow-up, anatomic/biomechanical studies, and technique articles were excluded. Included studies were assessed for patient demographics and outcome scores, patient satisfaction, complications, range of motion, and strength. RESULTS: Of 655 articles, 74 met inclusion criteria. The number of proximal humerus fractures averaged 74.2 per study (mean patient age, 65.6 years). Mean follow-up was 30.7 months. Neer type 1, 2, 3, and 4 fractures were included in 8%, 51%, 81%, and 88% of studies, respectively. Twenty-two patient-reported outcome instruments were used including the Constant-Murley score (65%), Disabilities of the Arm, Shoulder, and Hand score (31%), visual analog scale pain (27%), and American Shoulder and Elbow Surgeons score (18%). An average of 2.2 measures per study were reported. CONCLUSION: Considerable variability exists in the use of outcome measures across the proximal humerus fracture literature, making treatment comparison challenging. We recommend that future literature on proximal humerus fractures use at least 3 outcomes measures and 1 general health score until the optimal scores are determined.

Projected increase in total knee arthroplasty in the United States - an alternative projection model.

OBJECTIVE: The purpose of our study was to estimate the future incidence rate (IR) and volume of primary total knee arthroplasty (TKA) in the United States from 2015 to 2050 using a conservative projection model that assumes a maximum IR of procedures. Furthermore, our study compared these projections to a model assuming exponential growth, as done in previous studies, for illustrative purposes. METHODS: A population based epidemiological study was conducted using data from US National Inpatient Sample (NIS) and Census Bureau. Primary TKA procedures performed between 1993 and 2012 were identified. The IR, 95% confidence intervals (CI), or prediction intervals (PI) of TKA per 100,000 US citizens over the age of 40 years were calculated. The estimated IR was used as the outcome of a regression modelling with a logistic regression (i.e., conservative model) and Poisson regression equation (i.e., exponential growth model). RESULTS: Logistic regression modelling suggests the IR of TKA is expected to increase 69% by 2050 compared to 2012, from 429 (95%CI 374-453) procedures/100,000 in 2012 to 725 (95%PI 121-1041) in 2050. This translates into a 143% projected increase in TKA volume. Using the Poisson model, the IR in 2050 was projected to increase 565%, to 2854 (95%CI 2278-4004) procedures/100,000 IR, which is an 855% projected increase in volume compared to 2012. CONCLUSIONS: Even after using a conservative projection approach, the number of TKAs in the US, which already has the highest IR of knee arthroplasty in the world, is expected to increase 143% by 2050.

Shoulder arthroplasty options in young (<50 years old) patients: review of current concepts.

BACKGROUND: Prosthetic shoulder arthroplasty provides excellent pain relief and functional restoration for patients with glenohumeral arthritis, but concerns of survivorship have limited its use in younger patients. DISCUSSION: Despite general reports of high long-term survivorship, implant failure and functional deterioration after total shoulder arthroplasty are major concerns in the management of younger patients. In addition to having a longer life expectancy, younger patients also tend to be more active and can be expected to place greater demands on their shoulder arthroplasty. CONCLUSION: Alternative strategies have been developed and used for shoulder arthroplasty in younger patients. This manuscript reviews current concepts of shoulder arthroplasty in young patients.

Leukocyte esterase in the diagnosis of shoulder periprosthetic joint infection.

BACKGROUND: Shoulder periprosthetic joint infection (PJI) is difficult to diagnose with traditional methods. Leukocyte esterase (LE) has recently proven to be reliable in knee arthroplasty; however, its value in the shoulder has not been explored. We hypothesized that LE would display high sensitivity and specificity in shoulder PJI. METHODS: Two groups were prospectively evaluated: 45 primary and 40 revision shoulder arthroplasties. Synovial fluid and soft tissue cultures were obtained at surgery. Synovial fluid was evaluated with LE test strips. Any aspiration that contained erythrocytes was centrifuged and retested. Shoulder PJI was defined by modified Musculoskeletal Infection Society (MSIS) criteria. RESULTS: Of 5 primaries with positive tissue cultures (11%), only 1 was positive for LE. Of 16 revisions with positive cultures (40%), 4 had positive LE results. Among all patients with bacterial isolates, 6 aspirates were not interpretable (29%), despite centrifugation. LE had sensitivity of 25% and specificity of 75% to predict positive cultures in revisions. Ten revision patients met modified MSIS criteria for PJI. The sensitivity of LE in these patients was 30%, and the specificity was 67% (positive predictive value, 43%; negative predictive value, 83%). If bloody aspirates were considered positive, LE sensitivity in MSIS PJI increased to 60%, but the positive predictive value fell to 37.5%. CONCLUSION: LE is an unreliable diagnostic measure in shoulder PJI. The presence of erythrocytes within aspirates further decreased its accuracy. We conclude that LE should not be used for the routine identification of shoulder PJI.

Use of reverse total shoulder arthroplasty in the Medicare population.

BACKGROUND: Reverse shoulder arthroplasty (RSA) has been Food and Drug Administration approved in the United States since 2004 but did not obtain a unique code until 2010. Therefore, the use of this popular procedure has yet to be reported. The purpose of this study was to examine the use and reimbursement of RSA compared with total shoulder arthroplasty (TSA) and shoulder hemiarthroplasty (SHA). METHODS: We analyzed the 100% sample of the 2011 Medicare Part A claims data for patients aged 65 years or older. Patient demographic characteristics, diagnoses, provider information, reimbursements, and lengths of stay were extracted from the claims data. RESULTS: In 2011, a total of 31,002 shoulder arthroplasty procedures were performed; 37% were RSAs, 42% were TSAs, and 21% were SHAs. Osteoarthritis was the primary diagnosis code in 91% of TSAs, 37% of SHAs, and 45% of RSAs. A primary diagnosis of osteoarthritis with no secondary code for rotator cuff tear was found in 22% of patients undergoing RSA. The mean length of stay for RSA (2.6 days; SD, 2.1 days) was longer than that for TSA (2.1 days; SD, 1.5 days) and shorter than that for SHA (3.5 days; SD, 3.6 days) (P < .001). Lower-volume surgeons (<10 arthroplasties per year) performed most shoulder arthroplasties: 57% of RSAs, 65% of TSAs, and 97% of SHAs. Seventy percent of RSAs were implanted by surgeons who performed more RSAs than TSAs and SHAs combined. CONCLUSIONS: RSA is performed with similar frequency to TSA and almost twice as much as SHA in the Medicare population. Lower-volume surgeons perform most RSAs, and a majority of surgeons perform more RSAs than all anatomic shoulder arthroplasties combined.

Factors affecting hospital charges after total shoulder arthroplasty: an evaluation of the National Inpatient Sample database.

BACKGROUND: The number of total shoulder arthroplasties (TSA) performed in the United States increases yearly. At the same time, cost containment in health care continues to be a major concern. Therefore, it is imperative to identify specific variables that affect the cost of shoulder arthroplasty. METHODS: The U.S. National Inpatient Sample database was queried (1993-2010) to evaluate total hospital charges for shoulder arthroplasty. Etiology of arthritis, multiple medical comorbidities, and patient and hospital demographics were evaluated for their effect on total inpatient hospital charges by a multivariate analysis. RESULTS: Hospital charges for TSA increased from 1993 to 2010. Gender, race, and obesity were not associated with these differences in hospital charges. Post-traumatic and rheumatoid arthritis resulted in increased hospital charges; however, osteoarthritis resulted in decreased charges from the baseline. Multiple comorbidities (diabetes, lung disease, heart disease, and kidney disease) resulted in increased hospital charges after TSA. Regionally, the western and southern United States had the highest total charges above baseline. Larger hospitals and private urban hospitals also showed charges above baseline. CONCLUSIONS: The factors related to increased hospital charges after TSA are multifactorial and include medical comorbidities, patient demographics, and regionalization. As the future of health care continues to evolve, it is important for practitioners, legislators, insurance administrators, and hospitals to recognize factors that increase costs.

Optimizing Visualization in Shoulder Arthroscopy: An Evidence-Based Guide.

Advances in arthroscopy have contributed toward improved understanding and management of diverse pathological conditions in the shoulder. As a result, arthroscopy is often preferred by both patients and surgeons. However, surgery can be complicated by limited visualization. Techniques to improve visualization include patient and portal positioning, mechanical débridement, radiofrequency ablation, epinephrine added to irrigation fluid, tranexamic acid administration, and controlled hypotensive anesthesia. Despite published literature on each, a thorough understanding of the evidence supporting these techniques and adjuvants is essential to interpret the clinical utility of each.

Acute-on-Chronic Axillary Artery Thrombus After Reverse Total Shoulder Arthroplasty for Failed Proximal Humerus Open Reduction and Internal Fixation: A Case Report.

CASE: A 71-year-old woman presented with post-traumatic arthritis 11 months after open reduction and internal fixation for a left proximal humerus fracture (PHF) dislocation. After revision to reverse total shoulder arthroplasty (rTSA), the patient's left upper extremity was found to be avascular. An emergent thrombectomy was performed with restoration of arterial flow after removal of an acute-on-chronic axillary artery thrombus. CONCLUSION: Although rare, as rTSA becomes more common for management of PHF, incidence of associated vascular injuries is likely to rise. Screening methods and clinical vigilance in diagnosis are advised for patients with anterior PHF dislocations and arterial injury risk factors.

Female sex and ipsilateral reoperation risk following mesh-based inguinal hernia repair: a cohort study including 131,626 repairs in adults from an integrated healthcare system over a 10-year period.

PURPOSE: We sought to compare females and males for the risk of reoperation following different inguinal hernia repair approaches (open, laparoscopic, and robotic). METHODS: We conducted a retrospective cohort study including all patients aged ≥ 18 who underwent first inguinal hernia repair with mesh within a US integrated healthcare system (2010-2020). Data were obtained from the system's integrated electronic health record. Multiple Cox proportional-hazards regression was used to evaluate the association between sex and risk for ipsilateral reoperation during follow-up. Analysis was stratified by surgical approach (open, laparoscopic, and robotic). RESULTS: The study cohort was comprised of 110,805 patients who underwent 131,626 inguinal hernia repairs with mesh, 10,079 (7.7%) repairs were in females. After adjustment for confounders, females had a higher risk of reoperation than males following open groin hernia repair (hazard ratio [HR] = 1.98, 95% CI 1.74-2.25), but a lower reoperation risk following laparoscopic repair (HR = 0.70, 95% CI 0.51-0.97). The crude 5-year cumulative reoperation probability following robotic repair was 2.8% in males and no reoperations were observed for females. Of females who had a reoperation, 10.3% (39/378) were for a femoral hernia, while only 0.6% (18/3110) were for femoral hernias in males. CONCLUSION: In a large multi-center cohort of mesh-based inguinal hernia repair patients, we found a higher risk for reoperation in females after an open repair approach compared to males. Lower risk was observed for females through a minimally invasive approach (laparoscopic or robotic) and may be due to the ability to identify an occult femoral hernia through these approaches.

Implant-related and medical complications in patients with sarcopenia undergoing total shoulder arthroplasty: A retrospective matched-cohort analysis.

Background: In the continually aging United States population, the number of patients with sarcopenia who undergo shoulder arthroplasty may concomitantly increase. This retrospective cohort study aims to evaluate the rates of short-term implant-related and medical complications following shoulder arthroplasty in patients with and without a recent diagnosis of sarcopenia. Methods: An exact 1:3 matched analysis of 4177 patients was performed using the PearlDiver database. Multivariable logistic regression was used to compare complications, Kaplan-Meier failure analysis was used to compare the cumulative hospital readmission rates. Two-sample T-testing was used to compare the 90-day cost of care. Results: Sarcopenic patients were significantly more likely to experience postoperative shoulder instability (odds ratio (OR) = 2.32, 95% confidence interval (CI), 1.21-4.39) and periprosthetic infection (OR = 3.83, 95% CI, 1.74-8.67) within 1 year of their arthroplasty. Sarcopenic patients were at 25% and 41% greater risk of emergency department presentation and hospital readmission 1-year post-arthroplasty, respectively. Ninty-day total costs were greater among sarcopenics ($16 112.23 vs. 10 679.58, p < 0.001). Conclusion: These results are important for orthopaedic surgeons counselling patients with a low muscle mass on the potential for increased complications after undergoing a total shoulder arthroplasty procedure.

Staged Repair of Bilateral Isolated Teres Major Tears: A Case Report.

CASE: A 58-year-old, very active man sustained bilateral isolated teres major (TM) tendon tears when his arms were forcefully elevated overhead while wakeboarding. Staged surgical repair was performed. A progressive rehabilitation protocol was followed, and he returned to high-level activities 7 months postoperatively. At 1-year follow-up, outcome measures for bilateral shoulders were DASH 0, SST 12, ASES 100, and EQ-5D 1.0. CONCLUSION: Despite literature supporting conservative treatment, this case demonstrates that operative treatment of acute, isolated TM tears can result in highly successful outcomes for motivated active patients.

Shoulder arthroscopy: basic principles of positioning, anesthesia, and portal anatomy.

Advances in modern arthroscopy have contributed significantly to greater flexibility and efficacy in addressing shoulder pathology. Advantages of arthroscopy include less invasive approaches, improved visualization, decreased risk of many postoperative complications, and faster recovery. As a result, arthroscopy is often preferred by both orthopaedic surgeons and patients. Common shoulder conditions that can be managed arthroscopically include rotator cuff tears, shoulder instability, and labral pathology. A thorough understanding of anatomic principles in conjunction with proper patient positioning and portal selection and placement are essential for successful arthroscopic shoulder surgery.

Periodic orbits in chaotic systems simulated at low precision.

Non-periodic solutions are an essential property of chaotic dynamical systems. Simulations with deterministic finite-precision numbers, however, always yield orbits that are eventually periodic. With 64-bit double-precision floating-point numbers such periodic orbits are typically negligible due to very long periods. The emerging trend to accelerate simulations with low-precision numbers, such as 16-bit half-precision floats, raises questions on the fidelity of such simulations of chaotic systems. Here, we revisit the 1-variable logistic map and the generalised Bernoulli map with various number formats and precisions: floats, posits and logarithmic fixed-point. Simulations are improved with higher precision but stochastic rounding prevents periodic orbits even at low precision. For larger systems the performance gain from low-precision simulations is often reinvested in higher resolution or complexity, increasing the number of variables. In the Lorenz 1996 system, the period lengths of orbits increase exponentially with the number of variables. Moreover, invariant measures are better approximated with an increased number of variables than with increased precision. Extrapolating to large simulations of natural systems, such as million-variable climate models, periodic orbit lengths are far beyond reach of present-day computers. Such orbits are therefore not expected to be problematic compared to high-precision simulations but the deviation of both from the continuum solution remains unclear.

Short-term clinical and radiographic outcomes in patients treated with a modern intramedullary nailing system for 2-part proximal humerus fractures.

OBJECTIVES: The optimal surgical treatment of displaced proximal humerus fractures (PHFs) remains controversial. There are advocates for both open reduction and internal fixation with plate and screws (ORIF) and intramedullary nailing (IMN). The purpose this study was to evaluate the early-term clinical and radiographic outcomes of IMN for isolated, displaced 2-part surgical neck PHFs using a modern, straight nail system and to determine the effect of preoperative patient and fracture characteristics on outcome. METHODS: This was a case series of 23 patients with displaced 2-part surgical neck PHFs who were treated with ORIF using a straight IMN with minimum follow-up of 1 year (mean 2.5 years [range, 1.1-4.6]). Patients were identified retrospectively and contacted for measurement of active range of motion (AROM) and patient reported outcome measures (PROMs) including the American Shoulder and Elbow Surgeons (ASES) score, Oxford Shoulder Score (OSS), and Single Assessment Numeric Evaluation (SANE), EuroQol-5D (EQ-5D), and Visual Analog Scale Pain score (VAS Pain). Plain radiographs were evaluated to assess the quality of the reduction and failure of fixation. Complications and reoperations were identified. RESULTS: Reduction was anatomic in 12 (52%) patients, acceptable in 9 (39%), and 2 (9%) were malreduced. There were no differences in reduction quality based on sex (p = 0.37), age at surgery (p = 0.68), calcar comminution (p = 0.68), number of screws in the head (p = 0.99), or medial hinge disruption (p = 0.06). At final follow-up, the mean ASES score was 92 ± 10, OSS was 45 ± 4, SANE was 93 ± 7, EQ-5D of 0.85 ± 0.17, and VAS Pain was 0 ± 1. The mean active forward flexion was 143° ± 16°, active external rotation was 68° ± 20°, and internal rotation was T11 ± 4 vertebrae. Two (9%) patients underwent reoperation and 2 (9%) patients experienced clinical failure not requiring reoperation. CONCLUSIONS: Straight IMN is a reliable treatment for displaced 2-part surgical neck PHFs with excellent radiographic and clinical outcomes in early follow-up. The implant facilitated anatomic or acceptable alignment of the fracture in the vast majority of patients.