Profiling migration of human monocytes in response to chemotactic and barotactic guidance cues.

Monocytes are critical to innate immunity, participating in chemotaxis during tissue injury, infection, and inflammatory conditions. However, the migration dynamics of human monocytes under different guidance cues are not well characterized. Here, we developed a microfluidic device to profile the migration characteristics of human monocytes under chemotactic and barotactic guidance cues while also assessing the effects of age and cytokine stimulation. Human monocytes preferentially migrated toward the CCL2 gradient through confined microchannels, regardless of donor age and migration pathway. Stimulation with interferon (IFN)-γ, but not granulocyte-macrophage colony-stimulating factor (GM-CSF), disrupted monocyte navigation through complex paths and decreased monocyte CCL2 chemotaxis, velocity, and CCR2 expression. Additionally, monocytes exhibited a bias toward low-hydraulic-resistance pathways in asymmetric environments, which remained consistent across donor ages, cytokine stimulation, and chemoattractants. This microfluidic system provides insights into the unique migratory behaviors of human monocytes and is a valuable tool for studying peripheral immune cell migration in health and disease.

Bacterial metallothionein, PmtA, a novel stress protein found on the bacterial surface of Pseudomonas aeruginosa and involved in management of oxidative stress and phagocytosis.

Metallothioneins (MTs) are small cysteine-rich proteins that play important roles in homeostasis and protection against heavy metal toxicity and oxidative stress. The opportunistic pathogen, Pseudomonas aeruginosa, expresses a bacterial MT known as PmtA. Utilizing genetically modified P. aeruginosa PAO1 strains (a human clinical wound isolate), we show that inducing pmtA increases levels of pyocyanin and biofilm compared to other PAO1 isogenic strains, supporting previous results that pmtA is important for pyocyanin and biofilm production. We also show that overexpression of pmtA in vitro provides protection for cells exposed to oxidants, which is a characteristic of inflammation, indicating a role for PmtA as an antioxidant in inflammation. We found that a pmtA clean deletion mutant is phagocytized faster than other PAO1 isogenic strains in THP-1 human macrophage cells, indicating that PmtA provides protection from the phagocytic attack. Interestingly, we observed that monoclonal anti-PmtA antibody binds to PmtA, which is accessible on the surface of PAO1 strains using both flow cytometry and enzyme-linked immunosorbent assay techniques. Finally, we investigated intracellular persistence of these PAO1 strains within THP-1 macrophages cells and found that the phagocytic endurance of PAO1 strains is affected by pmtA expression. These data show for the first time that a bacterial MT (pmtA) can play a role in the phagocytic process and can be found on the outer surface of PAO1. Our results suggest that PmtA plays a role both in protection from oxidative stress and in the resistance to the host's innate immune response, identifying PmtA as a potential therapeutic target in P. aeruginosa infection. IMPORTANCE: The pathogen Pseudomonas aeruginosa is a highly problematic multidrug-resistant (MDR) pathogen with complex virulence networks. MDR P. aeruginosa infections have been associated with increased clinical visits, very poor healthcare outcomes, and these infections are ranked as critical on priority lists of both the Centers for Disease Control and Prevention and the World Health Organization. Known P. aeruginosa virulence factors have been extensively studied and are implicated in counteracting host defenses, causing direct damage to the host tissues, and increased microbial competitiveness. Targeting virulence factors has emerged as a new line of defense in the battle against MDR P. aeruginosa strains. Bacterial metallothionein is a newly recognized virulence factor that enables evasion of the host immune response. The studies described here identify mechanisms in which bacterial metallothionein (PmtA) plays a part in P. aeruginosa pathogenicity and identifies PmtA as a potential therapeutic target.

Porcine computational modeling to investigate developmental dysplasia of the hip.

While it is well-established that early detection and initiation of treatment of developmental dysplasia of the hip (DDH) is crucial to successful clinical outcomes, research on the mechanics of the hip joint during healthy and pathological hip development in infants is limited. Quantification of mechanical behavior in both the healthy and dysplastic developing joints may provide insight into the causes of DDH and facilitate innovation in treatment options. In this study, subject-specific three-dimensional finite element models of two pigs were developed: one healthy pig and one pig with induced dysplasia in the right hindlimb. The objectives of this study were: (1) to characterize mechanical behavior in the acetabular articular cartilage during a normal walking cycle by analyzing six metrics: contact pressure, contact area, strain energy density, von Mises stress, principal stress, and principal strain; and (2) to quantify the effect on joint mechanics of three anatomic abnormalities previously identified as related to DDH: variation in acetabular coverage, morphological changes in the femoral head, and changes in the articular cartilage. All metrics, except the contact area, were elevated in the dysplastic joint. Morphological changes in the femoral head were determined to be the most significant factors in elevating contact pressure in the articular cartilage, while the effects of acetabular coverage and changes in the articular cartilage were less significant. The quantification of the pathomechanics of DDH in this study can help identify key mechanical factors that restore normal hip development and can lead to mechanics-driven treatment options.

Outcomes of Concomitant Glenohumeral Stabilization After Arthroscopic Rotator Cuff Repair in Military Patients Younger Than 40 Years.

Background: While concomitant rotator cuff and inferior labral tears are relatively uncommon in young civilians, military populations represent a unique opportunity to study this injury pattern. Purpose: To (1) evaluate the long-term outcomes after combined arthroscopic rotator cuff and inferior labral repair in military patients <40 years and (2) compare functional outcomes with those after isolated arthroscopic rotator cuff repair. Study Design: Cohort study; Level of evidence, 3. Methods: Military patients who underwent arthroscopic rotator cuff repair between January 2011 and December 2016 and had a minimum of 5-year follow-up data were included in this study. The patients were categorized into those who had undergone combined arthroscopic rotator cuff and inferior labral repair (RCIL cohort) and those who had isolated arthroscopic rotator cuff repair (ARCR cohort). Pre- and postoperative outcome measures-visual analog scale for pain, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons shoulder score, Rowe Instability Score, and range of motion-were compared between the groups. Results: A total of 50 shoulders (27 in the RCIL cohort and 23 in the ARCR cohort) were assessed. The RCIL and ARCR groups were similar in terms of age (mean, 33.19 years [range, 21-39 years] vs 35.39 years [range, 26-39 years], respectively) and sex (% male, 88.46% vs 82.61%, respectively). All patients were active-duty military at the time of surgery. The mean final follow-up was at 106.93 ± 16.66 months for the RCIL group and 105.70 ± 7.52 months for the ARCR group (P = .75). There were no differences in preoperative outcome scores between groups. Postoperatively, both groups experienced statistically significant improvements in all outcome scores (P < .0001 for all), and there were no significant group differences in any final postoperative outcome measures. At the final follow-up, 26 (96.30%) patients in the RCIL cohort and 20 (86.96%) in the ARCR cohort had returned to unrestricted active-duty military service (P = .3223). Conclusion: The study findings indicate that concomitant glenohumeral stabilization does not prevent worse outcomes after arthroscopic rotator cuff repair in this military cohort. Combined repair produced statistically and clinically significant improvements in outcome scores at the long-term follow-up, indicating that simultaneous repair of combined lesions was an appropriate treatment option in this patient population.

Extracellular metallothionein as a therapeutic target in the early progression of type 1 diabetes.

Type 1 diabetes (T1D) is characterized by lymphocyte infiltration into the pancreatic islets of Langerhans, leading to the destruction of insulin-producing beta cells and uncontrolled hyperglycemia. In the nonobese diabetic (NOD) murine model of T1D, the onset of this infiltration starts several weeks before glucose dysregulation and overt diabetes. Recruitment of immune cells to the islets is mediated by several chemotactic cytokines, including CXCL10, while other cytokines, including SDF-1α, can confer protective effects. Global gene expression studies of the pancreas from prediabetic NOD mice and single-cell sequence analysis of human islets from prediabetic, autoantibody-positive patients showed an increased expression of metallothionein (MT), a small molecular weight, cysteine-rich metal-binding stress response protein. We have shown that beta cells can release MT into the extracellular environment, which can subsequently enhance the chemotactic response of Th1 cells to CXCL10 and interfere with the chemotactic response of Th2 cells to SDF-1α. These effects can be blocked in vitro with a monoclonal anti-MT antibody, clone UC1MT. When administered to NOD mice before the onset of diabetes, UC1MT significantly reduces the development of T1D. Manipulation of extracellular MT may be an important approach to preserving beta cell function and preventing the development of T1D.

Establishing the Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient Acceptable Symptomatic State After Arthroscopic Posterior Labral Repair for Posterior Glenohumeral Instability.

BACKGROUND: Posterior glenohumeral instability is an increasingly recognized cause of shoulder pain and dysfunction among young, active populations. Outcomes after posterior stabilization procedures are commonly assessed using patient-reported outcome measures including the Single Assessment Numeric Evaluation (SANE), the Rowe instability score, the American Shoulder and Elbow Surgeons (ASES) score, and the visual analog scale (VAS) for pain. The clinical significance thresholds for these measures after arthroscopic posterior labral repair (aPLR), however, remain undefined. PURPOSE: We aimed to define the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) for the SANE, Rowe score, and ASES score as well as the VAS pain after aPLR. Additionally, we sought to determine preoperative factors predictive of reaching, as well as failing to reach, clinical significance. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: This study was a retrospective analysis of patient-reported outcome scores collected from patients who underwent aPLR between January 2011 and December 2018. To determine the clinically significant threshold that corresponded to achieving a meaningful outcome, the MCID, SCB, and PASS were calculated for the SANE, Rowe score, ASES score, and VAS pain utilizing either an anchor- or distribution-based method. Additionally, univariate and multivariate logistic regression analyses were performed to determine the factors associated with achieving, or not achieving, the MCID, SCB, and PASS. RESULTS: A total of 73 patients with a mean follow-up of 82.55 ± 24.20 months were available for final analysis. MCID, SCB, and PASS values for the VAS pain were 1.10, 6, and 3, respectively; for the ASES score were 7.8, 34, and 80, respectively; for the SANE were 10.15, 33, and 85, respectively; and for the Rowe score were 11.3, 60, and 90, respectively. To meet the MCID, male sex (odds ratio [OR], 1.1639; P = .0293) was found to be a positive predictor for the VAS pain, and a lower preoperative SANE score (OR, 0.9939; P = .0003) was found to be a negative predictor for the SANE. Dominant arm involvement was associated with lower odds of achieving the PASS for the ASES score (OR, 0.7834; P = .0259) and VAS pain (OR, 0.7887; P = .0436). Patients who reported a history of shoulder trauma were more likely to reach the PASS for the SANE (OR, 1.3501; P = .0089), Rowe score (OR, 1.3938; P = .0052), and VAS pain (OR, 1.3507; P = .0104) as well as the SCB for the ASES score (OR, 1.2642; P = .0469) and SANE (OR, 1.2554; P = .0444). A higher preoperative VAS pain score was associated with higher odds of achieving the SCB for both the VAS pain (OR, 1.1653; P = .0110) and Rowe score (OR, 1.1282; P = .0175). Lastly, concomitant biceps tenodesis was associated with greater odds of achieving the SCB for the ASES score (OR, 1.3490; P = .0130) and reaching the PASS for the SANE (OR, 1.3825; P = .0038) and Rowe score (OR, 1.4040; P = .0035). CONCLUSION: To our knowledge, this study is the first to define the MCID, SCB, and PASS for the ASES score, Rowe score, SANE, and VAS pain in patients undergoing aPLR. Furthermore, we found that patients who reported a history of shoulder trauma and those who underwent concomitant biceps tenodesis demonstrated a greater likelihood of achieving clinical significance. Dominant arm involvement was associated with lower odds of achieving clinical significance.

Subacromial Balloon Placement Demonstrates No Advantage Over Debridement in the Treatment of Massive Irreparable Rotator Cuff Tears: A Dual-Armed Systematic Review and Meta-analysis of Over 1000 Patients.

BACKGROUND: In recent years, the placement of a subacromial balloon (SAB) spacer has emerged as a treatment option for massive irreparable rotator cuff tears (MIRCTs); however, there is significant controversy regarding its utility in comparison with other surgical interventions. PURPOSE: To compare outcomes after SAB spacer placement versus arthroscopic debridement for MIRCTs. STUDY DESIGN: Dual-armed systematic review and meta-analysis (level IV evidence). METHODS: A literature search of PubMed (MEDLINE), Scopus, and CINAHL Complete databases for articles published before May 7, 2022, was conducted to identify patients with MIRCTs undergoing the 2 procedures. For the SAB arm, 14 of 449 studies were considered eligible for inclusion, while 14 of 272 studies were considered eligible for inclusion in the debridement arm. RESULTS: In total, 528 patients were eligible for inclusion in the SAB arm and 479 patients in the debridement arm, and 69.9% of patients undergoing SAB placement also underwent concomitant debridement. Decreases in the visual analog scale (VAS) pain score and increases in the Constant score were found to be significantly larger after debridement (-0.7 points [P < .001] and +5.5 points [P < .001], respectively), although the Patient Acceptable Symptom State for the VAS was not achieved after either procedure. Both SAB placement and debridement significantly improved range of motion in forward flexion/forward elevation, internal and external rotation, and abduction (P < .001). Rates of general complication were higher after debridement versus SAB placement (5.2% ± 5.6% vs 3.5% ± 6.3%, respectively; P < .001); however, there were no significant differences between SAB placement and debridement in rates of persistent symptoms requiring a reintervention (3.3% ± 6.2% vs 3.8% ± 7.3%, respectively; P = .252) or reoperation rates (5.1% ± 7.6% vs 4.8% ± 8.4%, respectively; P = .552). The mean time to conversion to reverse total shoulder arthroplasty was 11.0 versus 25.4 months, respectively, for the SAB versus debridement arm. CONCLUSION: While SAB placement was associated with acceptable postoperative outcomes in the treatment of MIRCTs, there was no clear benefit over debridement alone. Shorter operative times coupled with better postoperative outcomes and longer times to conversion to reverse total shoulder arthroplasty rendered debridement a more attractive option. While there may be a role for SAB placement in poor surgical candidates, there is burgeoning evidence to support debridement alone without SAB placement for the treatment of MIRCTs.

Concomitant Biceps Tenodesis Does Not Portend Inferior Outcomes After Anterior Glenohumeral Stabilization.

BACKGROUND: Military patients are known to suffer disproportionately high rates of glenohumeral instability as well as superior labrum anterior to posterior (SLAP) tears. Additionally, a concomitant SLAP tear is frequently observed in patients with anterior shoulder instability. Even though biceps tenodesis has been demonstrated to produce superior outcomes to SLAP repair in military patients with isolated SLAP lesions, no existing studies have reported on outcomes after simultaneous tenodesis and anterior labral repair in patients with co-existing abnormalities. PURPOSE: To evaluate outcomes after simultaneous arthroscopic-assisted subpectoral biceps tenodesis and anterior labral repair in military patients younger than 40 years. We also sought to compare these outcomes with those after repair of an isolated anterior labral tear. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This study is a retrospective analysis of all military patients younger than 40 years from a single base who underwent arthroscopic anterior glenohumeral stabilization with or without concomitant biceps tenodesis between January 2010 and December 2019. Patients with glenoid bone loss of >13.5% were not eligible for inclusion. Outcome measures including the visual analog scale (VAS) for pain, the Single Assessment Numeric Evaluation (SANE), the American Shoulder and Elbow Surgeons (ASES) shoulder score, the Rowe instability score, and range of motion were administered preoperatively and postoperatively, and scores were compared between groups. RESULTS: A total of 82 patients met inclusion criteria for the study. All patients were active-duty service members at the time of surgery. The mean follow-up was 87.75 ± 27.05 months in the repair + tenodesis group and 94.07 ± 28.72 months in the isolated repair group (P = .3085). Patients who underwent repair + tenodesis had significantly worse preoperative VAS pain (6.85 ± 1.86 vs 5.02 ± 2.07, respectively; P < .001), ASES (51.78 ± 11.89 vs 62.43 ± 12.35, respectively; P = .0002), and Rowe (26.75 ± 7.81 vs 37.26 ± 14.91, respectively; P = .0002) scores than patients who underwent isolated repair. Both groups experienced significant improvements in outcome scores postoperatively (P < .0001 for all), and there were no statistically significant differences in postoperative outcome scores or range of motion between groups. There were no differences in the percentage of patients who achieved the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptom state for the VAS pain, SANE, ASES, and Rowe scores between groups. Overall, 37 of the 40 (92.50%) patients in the repair + tenodesis group and 40 of the 42 (95.24%) patients in the isolated repair group returned to unrestricted active-duty military service (P = .6045). In addition, 38 (95.00%) patients in the repair + tenodesis group and 40 (95.24%) patients in the isolated repair group returned to preinjury levels of sporting activity (P = .9600). There were no significant differences in the number of failures, revision surgical procedures, or patients discharged from the military between groups (P = .9421, P = .9400, and P = .6045, respectively). CONCLUSION: The findings of this study indicate that simultaneous biceps tenodesis and labral repair was a viable treatment option for the management of concomitant SLAP and anterior labral lesions in young, active military patients younger than 40 years.

Long-Term Outcomes in Female Patients With Carpometacarpal Arthroplasty and Metacarpophalangeal Fusion Compared With the Unoperated Side or Carpometacarpal Arthroplasty.

PURPOSE: Patients with carpometacarpal (CMC) osteoarthritis (OA) often present with metacarpophalangeal (MP) hyperextension and/or thenar atrophy. This study hypothesizes that MP fusion (MPF) performed at the time of CMC arthroplasty (CMCA) for patients who have moderate-to-severe thenar atrophy, MP hyperextension >30°, or MP arthritis will have greater long-term pinch strength and improvements in the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score from preoperative values when compared with the unoperated side or those who had CMCA only. METHODS: This study involved a retrospective review of long-term results from patients who underwent either CMCA or CMCA/MPF. The QuickDASH score, the pain visual analog scale (VAS), and an average of three pinch readings from each thumb were measured on the Baseline pinch gauge and recorded with a correction for hand dominance in right-handed patients. RESULTS: Fifty-three female patients with 70 operated thumbs were included in the study. The mean age was 67.2 years. There were 29 CMCAs and 41CMCA/MPFs. The mean follow-up was 6.3 years (range 2-16.9 years). At the latest follow-up, the mean CMCA/MPF pinch strength (11.3 lbs) was significantly stronger than that of CMCA (8.0 lbs) and carpometacarpal osteoarthritis thumbs (8.9 lbs). There was no significant difference in pinch strength between patients who underwent a CMCA and CMCOA thumbs (8.0 lbs vs 8.9 lbs, respectively). Preoperative QuickDASH demonstrated worse function in the CMCA/MPF group (55.8 vs 36.5). At the latest follow-up, QuickDASH and VAS revealed similar values in both the CMCA/MPF (10.5 and 0.66) and CMCA (18.5 and 0.52) groups. CONCLUSION: Long-term results demonstrate stronger pinch and greater improvement in QuickDASH scores in patients who underwent CMCA/MPF compared with those who underwent a CMCA or untreated carpometacarpal osteoarthritis thumbs. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Risk Factors for Glenoid Bone Loss in the Setting of Posterior Glenohumeral Instability.

Background: Posterior instability has been reported to account for up to 24% of cases of shoulder instability in certain active populations. However, there is a paucity of data available regarding the risk factors associated with posterior glenoid bone loss. Purpose: To characterize the epidemiology of, and risk factors associated with, glenoid bone loss within a cohort of patients who underwent primary arthroscopic shoulder stabilization for isolated posterior-type glenohumeral instability. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This was a retrospective analysis of patients who underwent primary arthroscopic shoulder stabilization for posterior-type instability between January 2011 and December 2019. Preoperative magnetic resonance arthrograms were used to calculate posterior glenoid bone loss using a perfect circle technique. Patient characteristics and revision rates were obtained. Bone loss (both in millimeters and as a percentage) was compared between patients based on sex, age, arm dominance, sports participation, time to surgery, glenoid version, history of trauma, and number of anchors used for labral repair. Results: Included were 112 patients with a mean age of 28.66 ± 10.07 years; 91 patients (81.25%) were found to have measurable bone loss. The mean bone loss was 2.46 ± 1.68 mm (8.98% ± 6.12%). Significantly greater bone loss was found in athletes versus nonathletes (10.09% ± 6.86 vs 7.44% ± 4.56; P = .0232), female versus male patients (11.17% ± 6.53 vs 8.17% ± 5.80; P = .0212), and patients dominant arm involvement versus nondominant arm involvement (10.26% ± 5.63 vs 7.07% ± 6.38; P = .0064). Multivariate regression analysis identified dominant arm involvement as an independent risk factor for bone loss (P = .0033), and dominant arm involvement (P = .0024) and athlete status (P = .0133) as risk factors for bone loss >13.5%. At the conclusion of the study period, 7 patients had experienced recurrent instability (6.25%). Conclusion: The findings of this study are in alignment with existing data suggesting that posterior glenoid bone loss is highly prevalent in patients undergoing primary arthroscopic stabilization for posterior-type shoulder instability. Our results suggest that patients with dominant arm involvement are at risk for greater posterior glenoid bone loss. Athlete status and dominant arm involvement were identified as independent risk factors for bone loss >13.5%.

Increased deformations are dispensable for cell mechanoresponse in engineered bone analogs mimicking aging bone marrow.

Aged individuals and astronauts experience bone loss despite rigorous physical activity. Bone mechanoresponse is in-part regulated by mesenchymal stem cells (MSCs) that respond to mechanical stimuli. Direct delivery of low intensity vibration (LIV) recovers MSC proliferation in senescence and simulated microgravity models, indicating that age-related reductions in mechanical signal delivery within bone marrow may contribute to declining bone mechanoresponse. To answer this question, we developed a 3D bone marrow analog that controls trabecular geometry, marrow mechanics and external stimuli. Validated finite element (FE) models were developed to quantify strain environment within hydrogels during LIV. Bone marrow analogs with gyroid-based trabeculae of bone volume fractions (BV/TV) corresponding to adult (25%) and aged (13%) mice were printed using polylactic acid (PLA). MSCs encapsulated in migration-permissive hydrogels within printed trabeculae showed robust cell populations on both PLA surface and hydrogel within a week. Following 14 days of LIV treatment (1g, 100 Hz, 1 hour/day), type-I collagen and F-actin were quantified for the cells in the hydrogel fraction. While LIV increased all measured outcomes, FE models predicted higher von Mises strains for the 13% BV/TV groups (0.2%) when compared to the 25% BV/TV group (0.1%). Despite increased strains, collagen-I and F-actin measures remained lower in the 13% BV/TV groups when compared to 25% BV/TV counterparts, indicating that cell response to LIV does not depend on hydrogel strains and that bone volume fraction (i.e. available bone surface) directly affects cell behavior in the hydrogel phase independent of the external stimuli. Overall, bone marrow analogs offer a robust and repeatable platform to study bone mechanobiology.

Diagnosis of Posterior and Combined-Type Shoulder Instability: A 10-Year Cross-sectional Study From a Single Military Base.

Background: Large variations exist in the reported frequency and etiology of posterior and combined shoulder instability in the active-duty military population. Purpose: To compare imaging and clinical examination findings as well as reoperation rates between active-duty military patients who underwent surgery for anterior, posterior, and combined-type shoulder instability. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A retrospective review was conducted on patients treated surgically for shoulder instability from a single military base from January 2010 to December 2019. Each case was characterized as isolated anterior, isolated posterior, or combined, according to arthroscopic findings. Information was collected on patient characteristics, history of trauma, time to surgery, associated pathological findings, and survivorship at a minimum 2-year follow-up. Results: Overall, 416 patients (n = 394 men; n = 22 women), with a mean age of 29.1 years, underwent primary shoulder stabilization surgery during the study period. There were 158 patients (38%) with isolated anterior instability, 139 (33%) with isolated posterior instability, and 119 (29%) with combined instability. A history of trauma was more prevalent with isolated anterior instability (129 [81.7%]) than with either isolated posterior (95 [68.4%]) or combined instability (73 [61.3%]) (P = .047 and P = .001, respectively). Patients with anterior instability were significantly more likely to be diagnosed on the preoperative physical examination when compared with patients with posterior instability (93% vs 79.1%; P < .001) or combined instability (93% vs 75.6%; P < .001) and were also more likely to have a discrete labral tear detected on a preoperative magnetic resonance arthrogram than patients with posterior instability (82.9% vs 63.3%; P < .001). There was no significant difference in the rate of medical discharge or recurrent instability requiring reoperation between groups. Conclusion: The study findings indicated that young, active-duty military patients are at increased risk for isolated posterior and combined-type shoulder instability, with posterior and combined instability collectively accounting for over 60% of instability cases in this cohort. Orthopaedic surgeons should be aware of instability when evaluating and treating young, active-duty military patients with shoulder pain, even in the absence of diagnostic physical examinations or imaging findings.

Prevalence and Risk Factors of Glenoid Bone Loss in Combined Shoulder Instability in Young, Active-Duty Military Patients.

Background: US military servicemembers experience higher rates of posterior and combined-type instability as compared with their nonmilitary peers. Purpose: (1) To determine the prevalence of glenoid bone loss (GBL) in young, active-duty military patients with combined-type shoulder instability who underwent operative shoulder stabilization; (2) to evaluate whether GBL is associated with differences in postoperative outcomes; and (3) to identify factors associated with larger defects. Study Design: Case series; Level of evidence, 4. Methods: This study included active-duty military patients who underwent primary surgical shoulder stabilization for combined anterior and posterior capsulolabral tears between January 2012 and December 2018. Preoperative magnetic resonance arthrograms were used to calculate anterior, posterior, and total GBL using the "perfect circle" technique. We recorded patient characteristics, revisions, complications, return to duty, range of motion, and scores on multiple outcome measures (visual analog scale for pain, Single Assessment Numeric Evaluation, American Shoulder and Elbow Surgeons, and Rowe). GBL prevalence was compared by time to surgery, glenoid version, history of trauma, and number of anchors used for labral repair. Outcome scores, return to active duty, and revision procedures were compared by degree of anterior or posterior GBL: <13.5% (mild) versus ≥13.5% (subcritical). Results: GBL was noted in 28 (77.8%) of the 36 patients. Nineteen (52.8%) patients had anterior GBL, 18 (50.0%) had posterior, and 9 (25.0%) had combined. Four (11.1%) patients had subcritical anterior or posterior GBL. Increased posterior GBL was associated with history of trauma (P = .041), time to surgery >12 months (P = .024), and glenoid retroversion ≥9° (P = .010); increased total GBL was associated with longer time to surgery (P = .023) and labral repair requiring >4 anchors (P = .012); and increased anterior GBL was associated with labral repair requiring >4 anchors (P = .011). There were statistically significant improvements on all outcome measures, with no changes in range of motion postoperatively. No significant difference on any outcome score was observed between patients with mild and subcritical GBL. Conclusion: In our analysis, 78% of patients had appreciable GBL, suggesting that GBL is highly prevalent in this patient population. Longer time to surgery, traumatic cause, significant glenoid retroversion, and large labral tears were identified as risk factors for increased GBL.

Pedicle Screw Placement Accuracy in Robot-Assisted Spinal Fusion in a Multicenter Study.

Pedicle screw fixation is a spinal fusion technique that involves the implantation of screws into vertebral pedicles to restrict movement between those vertebrae. The objective of this research is to measure pedicle screw placement accuracy using a novel automated measurement system that directly compares the implanted screw location to the planned target in all three anatomical views. Preoperative CT scans were used to plan the screw trajectories in 122 patients across four surgical centers. Postoperative scans were fused to the preoperative plan to quantify placement accuracy using an automated measurement algorithm. The mean medial-lateral and superior-inferior deviations in the pedicle region for 500 screws were 1.75 ± 1.36 mm and 1.52 ± 1.26 mm, respectively. These deviations were measured using an automated system and were statistically different from manually determined values. The uncertainty associated with the fusion of preoperative to postoperative images was also quantified to better understand the screw-to-plan accuracy results. This study uses a novel automated measurement system to quantify screw placement accuracy as it relates directly to the planned target location, instead of analyzing for breaches of the pedicle, to quantify the validity of using of a robotic-guidance system for accurate pedicle screw placement.

Outcomes Following Combined Posterior Labral and SLAP Repair in Military Patients Younger Than 35 Years.

BACKGROUND: Members of the military are known to experience disproportionately high rates of both glenohumeral instability and superior labrum anterior-posterior (SLAP) tears when compared with civilian populations. Although the outcomes after simultaneous repair of Bankart and SLAP lesions have been well described, there is a paucity of literature available regarding the operative management of posterior instability with concomitant superior labral pathology. PURPOSE: To compare outcomes of combined arthroscopic posterior labral and SLAP repair with those of isolated posterior labral repair. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: All consecutive patients younger than 35 years who underwent arthroscopic posterior labral repair from January 2011 to December 2016 with a minimum follow-up of 5 years were identified. From this cohort of eligible patients, all individuals who had undergone combined SLAP and posterior labral repair (SLAP cohort) versus posterior labral repair alone (instability cohort) were then identified. Outcome measures including the visual analog scale score, Single Assessment Numeric Evaluation (SANE), American Shoulder and Elbow Surgeons (ASES) score, Rowe instability score, and range of motion were collected pre- and postoperatively and scores were compared between groups. RESULTS: In total, 83 patients met the inclusion criteria for the study. All patients were active-duty military at the time of surgery. The mean follow-up was 93.79 ± 18.06 months in the instability group and 91.24 ± 18.02 months in the SLAP group (P = .5228). Preoperative SANE and ASES scores were significantly worse in the SLAP group. Both groups experienced statistically significant improvements in outcome scores postoperatively (P < .0001 for all), and there were no significant differences in any outcome scores or range of motion between groups. In total, 39 patients in the instability cohort and 37 in the SLAP cohort returned to preinjury levels of work (92.86% vs 90.24%, respectively; P = .7126), and 38 instability patients and 35 SLAP patients returned to preinjury levels of sporting activity (90.48% vs 85.37%, respectively; P = .5195). Two patients in the instability group and 4 patients in the SLAP group were medically discharged from the military (4.76% vs 9.76%; P = .4326), and 2 patients in each cohort had experienced treatment failure at the final follow-up (4.76% vs 4.88%; P > .9999). CONCLUSION: Combined posterior labral and SLAP repair led to statistically and clinically significant increases in outcome scores and high rates of return to active-duty military service that did not differ significantly from the results after isolated posterior labral repair. The results of this study indicate that simultaneous repair is a viable treatment option for the management of combined lesions in active-duty military patients <35 years of age.

Midterm Outcomes Following Combined Biceps Tenodesis and Anterior Labral Repair in Active Duty Military Patients Younger Than 35 Years.

BACKGROUND: Superior labrum anterior-posterior (SLAP) lesions and anterior instability are common causes of shoulder pain and dysfunction among active-duty members of the United States military. However, little data have been published regarding the surgical management of type V SLAP lesions. PURPOSE: To compare the outcomes of arthroscopic-assisted subpectoral biceps tenodesis and anterior labral repair with those of arthroscopic SLAP repair (defined as contiguous repair spanning from the superior labrum to the anteroinferior labrum) for type V SLAP tears in active-duty military patients younger than 35 years. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: All consecutive patients from January 2010 to December 2015 who underwent arthroscopic SLAP repair or combined biceps tenodesis and anterior labral repair for a type V SLAP lesion with a minimum 5-year follow-up were identified. The decision to perform type V SLAP repair versus combined biceps tenodesis and anterior labral repair was based on the condition of the long head of the biceps tendon (LHBT). Labral repair was performed in patients who had a type V SLAP tear with an otherwise clinically and anatomically healthy LHBT. Combined tenodesis and repair was performed in patients with evidence of LHBT abnormalities. Outcomes including the visual analog scale (VAS) score, the Single Assessment Numeric Evaluation (SANE) score, the American Shoulder and Elbow Surgeons (ASES) shoulder score, the Rowe instability score, and range of motion were collected preoperatively and postoperatively, and scores were compared between the groups. RESULTS: A total of 84 patients met the inclusion criteria for the study. All patients were active-duty service members at the time of surgery. A total of 44 patients underwent arthroscopic type V SLAP repair, and 40 patients underwent anterior labral repair with biceps tenodesis. The mean follow-up was 102.59 ± 20.98 months in the repair group and 94.50 ± 27.11 months in the tenodesis group (P = .1281). There were no significant differences in preoperative range of motion or outcome scores between the groups. Both groups experienced statistically significant improvements in outcome scores postoperatively (P < .0001 for all); however, compared with the repair group, the tenodesis group reported significantly better postoperative VAS (2.52 ± 2.36 vs 1.50 ± 1.91, respectively; P = .0328), SANE (86.82 ± 11.00 vs 93.43 ± 8.81, respectively; P = .0034), and ASES (83.32 ± 15.31 vs 89.90 ± 13.31, respectively; P = .0394) scores. There were no differences in the percentage of patients who achieved the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptom state for the SANE and ASES between the groups. Overall, 34 patients in each group returned to preinjury levels of work (77.3% vs 85.0%, respectively; P = .3677), and 32 patients (72.7%) in the repair group and 33 patients (82.5%) in the tenodesis group returned to preinjury levels of sporting activity (P = .2850). There were no significant differences in the number of failures, revision surgical procedures, or patients discharged from the military between the groups (P = .0923, P = .1602, and P = .2919, respectively). CONCLUSION: Both arthroscopic-assisted subpectoral biceps tenodesis combined with anterior labral repair and arthroscopic SLAP repair led to statistically and clinically significant increases in outcome scores, marked improvements in pain, and high rates of return to unrestricted active duty in military patients with type V SLAP lesions. The results of this study suggest that biceps tenodesis combined with anterior labral repair produces comparable outcomes to arthroscopic type V SLAP repair in active-duty military patients younger than 35 years.

The Effect of the Overweight Condition on Arthroscopic Rotator Cuff Repair Outcomes.

This study sought to investigate the influence of a preexisting overweight condition (body mass index [BMI], 25-29.9 kg/m2) on functional outcomes after arthroscopic rotator cuff repair surgery. A retrospective review was performed examining the outcomes of arthroscopic rotator cuff repair in a normal-weight (BMI, 18.5-24.9 kg/m2) and an overweight (BMI, 25-29.9 kg/m2) population. Functional outcomes were assessed to include the American Shoulder and Elbow Surgeons (ASES) score, the Single Assessment Numeric Evaluation score, and the visual analog scale (VAS) pain score, as well as range of motion in forward flexion, external rotation, and internal rotation. A total of 52 normal-weight patients (mean BMI, 23.7±2.1 kg/m2) and 57 overweight patients (mean BMI, 28.4±1.4 kg/m2) were included. Both groups demonstrated statistically and clinically significant improvements in VAS score, Single Assessment Numeric Evaluation score, and ASES score at final follow-up (P<.0001), with no difference in range of motion (P>.05). Overall, when comparing outcomes between the groups, there were significantly better outcomes in the normal-weight group's VAS scores (mean, 0.56±0.96 vs 1.3±1.7; P=.0064), ASES scores (mean, 96.1±5.8 vs 92.4±9.7; P=.0187), and internal rotation (mean thoracic vertebrae, 9.2±3.0 vs 10.4±2.6; P=.0289). However, these differences did not reach clinical significance regarding the threshold of patients meeting standard minimal clinically important difference, substantial clinical benefit, and patient-acceptable symptomatic state for rotator cuff repairs. Over-weight patients have improved outcomes after arthroscopic rotator cuff repair surgery with noninferior clinical results when compared with normal-weight patients. More data regarding outcomes of overweight patients will help physicians make better-informed decisions when considering rotator cuff repair. [Orthopedics. 2023;46(4):242-249.].

Computational comparison of medializing tibial tubercle osteotomy and trochleoplasty in patients with trochlear dysplasia.

Medial patellofemoral ligament reconstruction (MPFLR) has emerged as the procedure of choice for recurrent patellar dislocation. This addresses soft tissue injury but does not address underlying anatomic factors, including trochlear dysplasia, that are commonly present and increase risk of dislocation. Quantification of the stability offered by other surgical interventions, namely, medializing tibial tubercle osteotomy (mTTO) and trochleoplasty, with and without MPFLR, may provide insight for surgical choices in patients with trochlear dysplasia. We developed subject-specific finite element models based on magnetic resonance scans from a cohort of 20 patients with trochlear dysplasia and recurrent patellar dislocation. The objectives of this study were (1) to compare patella stability after mTTO and trochleoplasty procedures; (2) to evaluate whether it is necessary to perform an MPFLR in combination with the mTTO or trocheoplasty procedure; and (3) to quantify the robustness of patellar stability to variability in knee kinematics. Trochleoplasty performed better than mTTO at stabilizing the patella between 5° and 30° flexion. For both mTTO and trochleoplasty procedures, it was beneficial to also perform MPFLR-inclusion of MPFLR halved the magnitude of patellar laxity predicted in the simulations. Simulations that did not include any medial patellofemoral ligament restraint were also more sensitive to variation in tibiofemoral internal-external kinematics.

Instantaneous Generation of Subject-Specific Finite Element Models of the Hip Capsule.

Subject-specific hip capsule models could offer insights into impingement and dislocation risk when coupled with computer-aided surgery, but model calibration is time-consuming using traditional techniques. This study developed a framework for instantaneously generating subject-specific finite element (FE) capsule representations from regression models trained with a probabilistic approach. A validated FE model of the implanted hip capsule was evaluated probabilistically to generate a training dataset relating capsule geometry and material properties to hip laxity. Multivariate regression models were trained using 90% of trials to predict capsule properties based on hip laxity and attachment site information. The regression models were validated using the remaining 10% of the training set by comparing differences in hip laxity between the original trials and the regression-derived capsules. Root mean square errors (RMSEs) in laxity predictions ranged from 1.8° to 2.3°, depending on the type of laxity used in the training set. The RMSE, when predicting the laxity measured from five cadaveric specimens with total hip arthroplasty, was 4.5°. Model generation time was reduced from days to milliseconds. The results demonstrated the potential of regression-based training to instantaneously generate subject-specific FE models and have implications for integrating subject-specific capsule models into surgical planning software.