Peroneus Longus Tendon Autograft May Present a Viable Alternative for Anterior Cruciate Ligament Reconstruction: A Systematic Review.

PURPOSE: To examine the available literature to better understand the objective and patient-reported outcomes using peroneus longus tendon (PLT) autograft compared with more commonly used autografts, such as the quadrupled hamstring tendons (HT), in patients undergoing primary for anterior cruciate ligament reconstruction (ACLR). METHODS: A comprehensive search of published literature in PubMed, Web of Science, Cochrane Library, Ovid, and EMBASE databases was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Inclusion criteria included patients undergoing ACLR with PLT autograft, inclusion of patient-recorded outcome measures, and availability in English language. Publications that included only biomechanical analysis or ACLR with use of allograft or combination grafts were excluded. RESULTS: A total of 16 studies (Level of Evidence range: I-IV) met inclusion criteria, with follow-up ranging from 3 months to 5 years. In the available case series, patient-reported outcomes ranged from Lysholm = 80.7 to 95.1, International Knee Documentation Committee 78.1 to 95.7. In prospective cohorts and randomized controlled trials, PLT performance was comparable with HT autografts (PLT/HT: Lysholm = 88.3-95.1/86.5-94.9, International Knee Documentation Committee = 78.2-92.5/87.4-93.4). The majority of PLT grafts diameters were equal or greater than HT counterparts with a mean of >8 mm (PLT/HT: 7.0-9.0 mm/7.65-8.5 mm). There was minimal donor-site morbidity associated with PLT harvest. CONCLUSIONS: Although limitations exist within the available literature, existing evidence suggests that PLT autograft routinely produces adequately sized grafts with comparable early outcomes to HT autograft and low risk of donor-site morbidity. However, the PLT autograft is yet to demonstrate superiority to any of the more-traditional autograft selections. LEVEL OF EVIDENCE: Level IV, systematic review of Level I-IV studies.

A Posterior Acromial Bone Block Augmentation Is Biomechanically Effective at Restoring the Force Required To Translate the Humeral Head Posteriorly in a Cadaveric, Posterior Glenohumeral Instability Model.

PURPOSE: To assess the biomechanical utility of a posterior acromial bone block (PABB) for the treatment of posterior glenohumeral instability. METHODS: Ten fresh-frozen cadaveric specimens were obtained based upon an a priori power analysis. A 2.5-cm scapular spine autograft was harvested from all shoulders. A custom robot device was used to apply a 50-N compressive force to the glenohumeral joint. The humeral head was translated 10 mm posteroinferiorly at 30 degrees from the center of the glenoid at a rate of 1.0 mm/s in 6 consecutive conditions: (1) intact specimen, (2) intact with PABB, (3) posterior capsulolabral tear, (4) addition of the PABB, (5) removal of the PABB and repair of the capsulolabral tear (LR), and (6) addition of the PABB with LR. The maximum force required to obtain this translation was recorded. Paired t tests were performed to compare relevant testing conditions. RESULTS: Ten cadavers with a mean ± SD age of 54.4 ± 13.1 years and mean ± SD glenoid retroversion of 6.5 ± 1.0 degrees were studied. The PABB provided greater resistance force to humeral head translation compared to the instability state (instability, 29.3 ± 15.3 N vs PABB, 47.6 ± 21.0 N; P = .001; 95% confidence interval [CI], -27.6 to -10.0). When comparing PABB to LR, the PABB produced higher resistance force than LR alone (PABB, 47.6 ± 21.0 N; LR, 34.2 ± 20.5 N; P = .012; 95% CI, -23.4 to -4.1). An instability lesion treated with the PABB, with LR (P = .056; 95% CI, -0.30 to 20.4) or without LR (P = .351; 95% CI, -6.8 to 15.7), produced resistance forces similar to the intact specimen. CONCLUSIONS: A PABB is biomechanically effective at restoring the force required to translate the humeral head posteriorly in a cadaveric, posterior glenohumeral instability model. A posterior acromial bone block is a biomechanically feasible option to consider in patients with recurrent posterior instability. CLINICAL RELEVANCE: Augmentation of the posterior acromion may be a biomechanically feasible option to treat posterior shoulder instability.

Outcomes of Arthroscopic Stabilization for Posterior Shoulder Instability - A Systematic Review.

BACKGROUND: Posterior shoulder instability makes up approximately 10% of all shoulder instability cases and its diagnosis and treatment is less well understood. Recently, however, there has been increased recognition of posterior instability and posterior stabilization. The purpose of this study was to systematically review the literature to ascertain the outcomes on arthroscopic stabilization of posterior shoulder instability. METHODS: Two independent reviewers conducted a systematic literature search based on PRISMA guidelines, utilizing the MEDLINE database. Studies were eligible for inclusion if they reported postoperative outcomes for posterior shoulder instability following arthroscopic stabilization. RESULTS: A total of 48 studies met inclusion criteria for review including 2307 shoulders. Majority of patients were male (83.3%), with an average age of 26.1 years and a mean follow-up of 46.8 months. The functional outcome score primarily utilized for postoperative assessment was ASES with an average of 84.77. Overall, 90.9% of patients reported being satisfied with their arthroscopic stabilization. Recurrent instability occurred in 7.4% of patients. The total revision rate was 5.2%. 16.6% of patients reported residual pain postoperatively. The rate of return to play was 86.4% with 68.0% of patients returning to play at the same or higher level of play. CONCLUSION: Arthroscopic stabilization of posterior shoulder instability resulted in good outcomes with high patient satisfaction and low rates of recurrent instability, revisions, and residual pain.

Testosterone Therapy Is Associated With Increased Odds of Quadriceps Tendon Injury.

BACKGROUND: Anabolic steroid use at supraphysiologic doses has been associated with an increased risk of tendon injury. However, the musculoskeletal effects of testosterone therapy in the clinical setting are not well understood. QUESTIONS/PURPOSES: (1) Is prescription testosterone associated with a higher odds of subsequent quadriceps muscle or tendon injury? (2) Is prescription testosterone associated with a higher odds of surgical repair of the quadriceps tendon? METHODS: The PearlDiver Database, which contains data on Medicaid, Medicare, and commercially insured patients, allows for a large representative sample of the US population including both publicly and privately insured patients. The database was queried for all patients between 2011 and 2018 who filled a testosterone prescription. Additionally, all quadriceps injuries using ICD-9 and ICD-10 codes between 2011 and 2018 were queried. Propensity score matching based on age, sex, Charlson comorbidity index, and specific comorbidities allowed us to create matched control groups. We used the t-test and chi-square analysis to compare the unmatched and matched cohorts. A total of 151,797 patients (123,627 male patients and 28,170 female patients) with a history of filled testosterone prescriptions were included in the study after matching with the control group, which was of equal size and representation of age, male-female proportions, and comorbidities. Chi-square and logistic regression analyses were performed to compare odds of quadriceps injury and quadriceps tendon repair among the testosterone groups to that of their respective control groups by age and sex. RESULTS: Within 1 year of filling prescriptions for testosterone, 0.06% (97 of 151,797) of patients experienced a quadriceps injury compared with less than 0.01% (18 of 151,797) of patients in the control group (OR 5.4 [95% CI 3.4 to 9.2]; p < 0.001). Within the sex-specific matched groups, filling a testosterone prescription was associated with an increase in the odds of quadriceps injury in male patients within 1 year of the prescription (OR 5.8 [95% CI 3.5 to 10.3]; p < 0.001). Additionally, patients who filled a testosterone prescription were at increased risk of having quadriceps tendon repair within a year of the injury than were patients in the matched control group (OR 4.7 [95% CI 2.0 to 13.8]; p = 0.001). CONCLUSION: Considering these findings, it is important for physicians to counsel patients receiving testosterone replacement therapy of the substantially increased odds of quadriceps tendon injury. Future investigations into the mechanisms of influence of exogenous anabolic steroids on tendon injury remains of interest. LEVEL OF EVIDENCE: Level III, therapeutic study.

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Anterior Cruciate Ligament Tears and Reconstruction Failure.

PURPOSE: To characterize the association between a diagnosis of hypovitaminosis D and primary anterior cruciate ligament (ACL) tear, primary anterior cruciate ligament reconstruction (ACLR), and revision ACLR in different sex and age cohorts. METHODS: In this retrospective cohort study of the PearlDiver claims database, records were queried between January 1, 2011, and October 31, 2018 for all patients aged 10 to 59 years who received a diagnosis of hypovitaminosis D. Rates of primary ACL tears, primary reconstruction, and revision reconstruction were calculated for sex- and age-specific cohorts and compared with a control of patients without a diagnosis of hypovitaminosis D. Incidence rates for primary ACL injuries were calculated, and multivariable logistic regression was used to compare rates of ACL injury, primary reconstruction, and revision reconstruction while controlling for age, sex, Charlson Comorbidity Index, and several other comorbidities. RESULTS: Among the 328,011 patients (mean age 41.9 ± 12.6 years, 65.8% female) included in both the hypovitaminosis D and control cohorts, the incidence of ACL tears was 115.2 per 100,000 person-years (95% confidence interval [CI] 107.2-123.7) compared with 61.0 (95% CI 55.2-67.2) in the demographic- and comorbidity-matched control cohort. The study cohort was significantly more likely to suffer an ACL tear over a 1- (aOR 1.67, 95% CI 1.41-1.99, P < .001) and 2-year (aOR 1.81, 95% CI 1.59-2.06, P < .001) period. This trend remained for both male patients at the 1- (aOR 1.66, 95% CI 1.29-2.14, P < .001) and 2-year (aOR 1.68, 95% CI 1.37-2.06, P < .001) mark and female patients at the 1- (aOR 1.69, 95% CI 1.33-2.14, P < .001) and 2-year (aOR 1.80, 95% CI 1.51-2.14, P < .001) mark. Finally, patients with vitamin D deficiency had a significantly increased likelihood of undergoing a revision ACLR within 2 years of a primary reconstruction (aOR 1.28, 95% CI 1.05-1.55, P = .012). CONCLUSIONS: This study reports an association between patients previously diagnosed with hypovitaminosis D and significantly increased rates of both index ACL tears (81% increase within 2 years of diagnosis) and revision ACLR (28% within 2 years). These results identify a population with increased odds of injury and provide valuable knowledge as we expand our understanding of the relationship between vitamin D and musculoskeletal health. LEVEL OF EVIDENCE: Level III, retrospective database study.

Trends in Lower Extremity Injuries Presenting to Emergency Departments During the COVID-19 Pandemic.

BACKGROUND: During the emergence of the SARS-CoV-2 (COVID-19) pandemic, there were substantial changes in U.S. emergency department (ED) volumes and acuity of patient presentation compared with more recent years. OBJECTIVES: The purpose of this study was to characterize the incidence of specific lower extremity (LE) injuries presenting to U.S. EDs during the COVID-19 pandemic and to analyze trends across age groups and rates of hospital admission compared with previous years. METHODS: The National Electronic Injury Surveillance System database was queried to identify patients who presented to U.S. EDs for a LE orthopedic injury between 2016 and 2020. RESULTS: These queries returned 252,656 cases, representing a total estimate of 9,740,514 injuries presenting to EDs across the United States. The mean incidence of LE orthopedic injuries was 596.8 injuries per 100,000 person-years (95% confidence interval [CI] 594.9-598.7), with the greatest annual decrease in incidence occurring between 2019 and 2020 (24.96%). The largest number of estimated hospital admissions occurred in 2020, with a total 181,671 admissions (95% CI 178,032-185,311), a 25.74% increase from the average number of admissions between 2016 and 2019. CONCLUSION: The COVID-19 pandemic has placed immense stress on both emergency medical services and hospital systems around the United States. While there were decreased rates of ED utilization for LE orthopedic complaints during the first year of the pandemic, there was a concomitant increase in both the number and proportion of these injuries admitted to the hospital from the ED. This places an additional burden on already stressed emergency medicine services and overall hospital systems that could slow down the management of medical emergencies.

Reverse total shoulder arthroplasty in patients 80 years and older: a national database analysis of complications and mortality.

BACKGROUND: Although reverse total shoulder arthroplasty (RSA) is considered a safe surgical option in elderly patients, large-scale analyses of complications and mortality after RSA in patients 80 years and older are scarce. The goals of the current study were to identify revision, complication, and early mortality rates after RSA in patients 80 years and older and compare these to younger patients. METHODS: The PearlDiver Database, which contains services rendered to Medicare, Medicaid, and commercial insurance patients, was queried for patients undergoing RSA using International Classification of Diseases, Ninth/Tenth Revision (ICD-9/ICD-10) procedure codes. Patients were separated into 2 groups based on their age: 80 years and older and <80 years of age. The incidence of revision arthroplasty, medical, and surgical complications after RSA were extracted. Multivariate regression was used to compare revision arthroplasty and complication rates between groups. Statistical significance was set at P <.05. RESULTS: A total of 29,430 cases of RSA were included, with 486 cases in patients 80 years and older (median age, 80 years; age range, 2 years). Patients 80 years and older had 1- and 2-year revision rates of 3.9% and 5.1%, compared with the younger cohort at 3.0% and 3.1%, respectively. In patients 80 years and older, there were higher rates of deep venous thrombosis (DVT) (odds ratio [OR] 2.87, 95% CI 1.5-4.97), urinary tract infection (OR 1.42, 95% CI 1.01-1.94), acute renal failure (OR 2.18, 95% CI 1.44-3.17), and pneumonia (OR 1.75, 95% CI 1.09-2.68) within 90 days postoperatively. Ninety-day surgical complications were similar between the cohorts; however, younger patients experienced higher rates of dislocation, stiffness, periprosthetic fracture, and implant complications 1 year postoperatively. Patients 80 years and older had a significantly higher 90-day mortality rate at 2.7% compared with 1.5% in younger patients (P = .002). CONCLUSIONS: RSA is a generally safe procedure even in patients 80 years and older, with low complication and revision rates. Patients 80 years and older had higher early mortality and medical complication rates, including DVT, renal failure, and pneumonia than patients <80 years of age. However, patients 80 years and older had lower rates of dislocation, periprosthetic fracture, and implant-related complication at 1 year postoperatively.

Normal Humeral Head Ossification in Pediatric and Adolescent Shoulders Can Mimic Hill-Sachs Lesions: A Magnetic Resonance Imaging-based Study.

BACKGROUND: The sequential maturation of the humeral head (HH) as viewed on magnetic resonance imaging (MRI) has not been described to date. Proper assessment may be complicated by the presence of physeal tissue in pediatric patients. Past studies suggest that skeletally immature patients may also have a higher risk of a false-positive diagnosis of Hill-Sachs lesion on MRI. The purpose of this study was to define pediatric HH developmental patterns using MRI and to investigate for any associations with findings of known false-positive Hill-Sachs. METHODS: Picture Archiving and Communication System (PACS) records at an urban academic tertiary care musculoskeletal facility from 2014 to 2020 were queried for shoulder MRI in patients aged 0 to 15 years. Patients were excluded if they had a history of glenohumeral instability, fracture, growth arrest, brachial plexus injury, surgery, or infection. All images were independently evaluated by a musculoskeletal fellowship-trained radiologist. Each HH was staged based on skeletal maturity. RESULTS: For both sexes, HHs matured in a predictable manner with increasing chronological age associated with a higher ossification stage. False Hill-Sachs lesions were observed in girls aged 4 to 7 and boys aged 5 to 14, exclusively during stage I to II ossification. CONCLUSIONS: False Hill-Sachs lesions were visualized on MRI in stage I to II proximal humerus ossification. Due to differential timing of skeletal maturation, males present with false Hill-Sachs lesions at a later age than females on average. When interpreting shoulder MRI for glenohumeral instability, clinicians should be cautious of false Hill-Sachs lesions, especially in younger patients with distinct greater tuberosity and HH ossification centers (stage I to II ossification). LEVEL OF EVIDENCE: Level III.

Recurrent Instability and Surgery Are Common After Nonoperative Treatment of Posterior Glenohumeral Instability in NCAA Division I FBS Football Players.

BACKGROUND: In-season return to play after anterior glenohumeral instability is associated with high rates of recurrent instability and the need for surgical stabilization. We are not aware of previous studies that have investigated in-season return to play after posterior glenohumeral instability; furthermore, as posterior shoulder instability in collision athletes occurs frequently, understanding the expected outcome of in-season athletes may improve the ability of physicians to provide athletes with a better understanding of the expected outcome of their injury and their ability to return to sport. QUESTIONS/PURPOSES: (1) What proportion of athletes returned to play during the season after posterior instability in collegiate football players? (2) How much time did athletes lose to injury, what proportion of athletes opted to undergo surgery, and what proportion of athletes experienced recurrent instability after a posterior instability episode during a collegiate football season? METHODS: A multicenter, prospective, observational study of National Collegiate Athletic Association (NCAA) Division 1 Football Bowl Subdivision athletes was performed at three US Military Service Academies. Ten athletes who sustained a posterior instability event during the regular football season and who pursued a course of nonoperative treatment were identified and prospectively observed through the subsequent season. All athletes in the observed cohort attempted an initial course of nonoperative treatment during the season. All athletes sustained subluxation events initially identified through history and physical examination at the time of injury. None of the athletes sustained a dislocation event requiring a manual reduction. Intraarticular pathology consisting of posterior labral pathology was further subsequently identified in all subjects via MRI arthrogram. Return to play was the primary outcome of interest. Time lost to injury, surgical intervention, and subsequent instability were secondary outcomes. RESULTS: Of the 10 athletes who opted for a trial of initial nonoperative management, seven athletes were able to return to play during the same season. Although these seven athletes returned within 1 week of their injury (median of 1 day), 5 of 7 athletes sustained recurrent subluxation events with a median (range) of four subluxation events per athlete (0 to 8) during the remainder of the season. Seven athletes were treated surgically after the completion of their season, four of whom returned to football. CONCLUSION: This study suggests that although collegiate football players are able to return to in-season sport after a posterior glenohumeral instability event, they will likely sustain multiple recurrent instability events and undergo surgery after the season is completed. The results of this study can help guide in-season management of posterior shoulder instability by allowing more appropriate postinjury counseling and decision making through the identification of those athletes who may require additional attention from medical staff during the season and possible modifications to training regimens to minimize long-term disability. Further prospective studies involving a larger cohort over several seasons should be performed through collaborative studies across the NCAA that better assess function and injury risk factors before beginning collegiate athletics. This would better characterize the natural history and associated functional limitations that athletes may encounter during their collegiate careers. LEVEL OF EVIDENCE: Level IV, prognostic study.

Measurement of the coracohumeral distance on magnetic resonance imaging in a large patient cohort.

BACKGROUND: Coracoid impingement syndrome is an increasingly recognized etiology of anterior shoulder pain. Numerus studies have documented the coracohumeral distance (CHD) as a primary or secondary measurement in symptomatic individuals, but there lacks an evaluation of CHD in a large cohort of asymptomatic individuals. The purpose of this study was to quantify a normative distribution of the CHD in a large cohort of healthy, asymptomatic subjects with no history of impingement or shoulder instability. METHODS: Incoming first-year students in the United States Military Academy were offered enrollment in this study as part of a prospective cohort to assess the normal anatomic relationships of the shoulder girdle. Magnetic resonance images were obtained, and a board-certified, fellowship-trained musculoskeletal radiologist performed measurements of the smallest distance from the coracoid to the humeral head on axial images. RESULTS: Magnetic resonance images of 714 subjects were available for analysis, including 630 males and 84 females, with a total of 1120 individual shoulders with images of adequate quality. The mean CHD for all shoulders imaged was 13.7 mm. The mean CHD in male shoulders was 13.8 mm, and in female subjects the average was 12.4 mm. CONCLUSIONS: This study is the largest of its kind to evaluate the CHD in asymptomatic, healthy shoulders to date and demonstrates a mean CHD of 13.7 mm for all subjects. This information can help to standardize "normal" ranges and act as a comparison for future work, when taken in the context of age and imaging in neutral rotation.

Cost comparison of arthroscopic rotator cuff repair with arthroscopic vs. open biceps tenodesis.

PURPOSE: To use a nationwide database to determine differences in cost between patients who underwent arthroscopic rotator cuff tear with open vs. arthroscopic biceps tenodesis (BT). METHODS: The 2014 State Ambulatory Surgical and Services Databases from 6 US states was utilized. All cases with CPT codes 29827 (arthroscopic rotator cuff repair [RCR]) and either 23430 (tenodesis of long tendon of biceps) or 29828 (arthroscopic BT) were selected. Cases that included both 23430 and 29828 were excluded, as were those missing demographic data. Generalized linear models were used to model costs based on the surgical and patient variables that were significant in the initial bivariate analysis (P < .05). RESULTS: A total of 3635 RCR and BT cases were identified. There were 2847 (78.3%) with arthroscopic BT and 788 (21.7%) with open BT. Patients undergoing arthroscopic BT were 3.1 years older than patients undergoing open BT (P < .001). For arthroscopic BT, 39.2% of the cases were women compared with 22.6% of the open cases (P < .001). For operative variables, arthroscopic BT required 9 fewer minutes in the OR than open cases (P = .002). Concomitant distal clavicle resection was performed in 35.5% of arthroscopic BT cases compared with 29.8% of open cases (P = .004). While controlling for other significant factors, open BT was associated with $5542 lower costs than arthroscopic BT in the setting of RCR (P < .001). In either case, concomitant subacromial decompression added $10,669 (P < .001), and distal clavicle resection added $3210 (P < .001). High-volume surgical facilities were associated with $4107 lower costs (P < .001). CONCLUSIONS: In a large series of patients undergoing arthroscopic RCR with open vs. arthroscopic BT, open BT was associated with $5542 lower costs than arthroscopic. Given that both techniques have been shown to be similarly effective in long-term follow-up, surgeons should be aware of opportunities for cost saving, particularly with the advent of bundled surgical reimbursements.

Surgical treatment for recurrent shoulder instability: factors influencing surgeon decision making.

BACKGROUND: The optimal surgical approach for recurrent anterior shoulder instability remains controversial, particularly in the face of glenoid and/or humeral bone loss. The purpose of this study was to use a contingent-behavior questionnaire (CBQ) to determine which factors drive surgeons to perform bony procedures over soft tissue procedures to address recurrent anterior shoulder instability. METHODS: A CBQ survey presented each respondent with 32 clinical vignettes of recurrent shoulder instability that contained 8 patient factors. The factors included (1) age, (2) sex, (3) hand dominance, (4) number of previous dislocations, (5) activity level, (6) generalized laxity, (7) glenoid bone loss, and (8) glenoid track. The survey was distributed to fellowship-trained surgeons in shoulder/elbow or sports medicine. Respondents were asked to recommend either a soft tissue or bone-based procedure, then specifically recommend a type of procedure. Responses were analyzed using a multinomial-logit regression model that quantified the relative importance of the patient characteristics in choosing bony procedures. RESULTS: Seventy orthopedic surgeons completed the survey, 33 were shoulder/elbow fellowship trained and 37 were sports medicine fellowship trained; 52% were in clinical practice ≥10 years and 48% <10 years; and 95% reported that the shoulder surgery made up at least 25% of their practice. There were 53% from private practice, 33% from academic medicine, and 14% in government settings. Amount of glenoid bone loss was the single most important factor driving surgeons to perform bony procedures over soft tissue procedures, followed by the patient age (19-25 years) and the patient activity level. The number of prior dislocations and glenoid track status did not have a strong influence on respondents' decision making. Twenty-one percent glenoid bone loss was the threshold of bone loss that influenced decision toward a bony procedure. If surgeons performed 10 or more open procedures per year, they were more likely to perform a bony procedure. CONCLUSION: The factors that drove surgeons to choose bony procedures were the amount of glenoid bone loss with the threshold at 21%, patient age, and their activity demands. Surprisingly, glenoid track status and the number of previous dislocations did not strongly influence surgical treatment decisions. Ten open shoulder procedures a year seems to provide a level of comfort to recommend bony treatment for shoulder instability.

Human Cartilage-Derived Progenitors Resist Terminal Differentiation and Require CXCR4 Activation to Successfully Bridge Meniscus Tissue Tears.

Meniscus injuries are among the most common orthopedic injuries. Tears in the inner one-third of the meniscus heal poorly and present a significant clinical challenge. In this study, we hypothesized that progenitor cells from healthy human articular cartilage (chondroprogenitor cells [C-PCs]) may be more suitable than bone-marrow mesenchymal stem cells (BM-MSCs) to mediate bridging and reintegration of fibrocartilage tissue tears in meniscus. C-PCs were isolated from healthy human articular cartilage based on their expression of mesenchymal stem/progenitor marker activated leukocyte cell adhesion molecule (ALCAM) (CD166). Our findings revealed that healthy human C-PCs are CD166+, CD90+, CD54+, CD106- cells with multilineage differentiation potential, and elevated basal expression of chondrogenesis marker SOX-9. We show that, similar to BM-MSCs, C-PCs are responsive to the chemokine stromal cell-derived factor-1 (SDF-1) and they can successfully migrate to the area of meniscal tissue damage promoting collagen bridging across inner meniscal tears. In contrast to BM-MSCs, C-PCs maintained reduced expression of cellular hypertrophy marker collagen X in monolayer culture and in an explant organ culture model of meniscus repair. Treatment of C-PCs with SDF-1/CXCR4 pathway inhibitor AMD3100 disrupted cell localization to area of injury and prevented meniscus tissue bridging thereby indicating that the SDF-1/CXCR4 axis is an important mediator of this repair process. This study suggests that C-PCs from healthy human cartilage may potentially be a useful tool for fibrocartilage tissue repair/regeneration because they resist cellular hypertrophy and mobilize in response to chemokine signaling. Stem Cells 2019;37:102-114.

Likelihood of Return to Duty Is Low After Meniscal Allograft Transplantation in an Active-duty Military Population.

BACKGROUND: Meniscal allograft transplantation (MAT) is considered a viable surgical treatment option in the symptomatic, postmeniscectomy knee and as a concomitant procedure with ACL revision and articular cartilage repair. Although promising outcomes have recently been reported in active and athletic populations, MAT has not been well-studied in the high-demand military population. QUESTIONS/PURPOSES: (1) What proportion of active-duty military patients who underwent MAT returned to full, unrestricted duty? (2) What demographic and surgical variables, if any, correlated with return to full, unrestricted duty? METHODS: Between 2005 and 2015, three fellowship-trained sports surgeons (TMD, SJS, BDO) performed 110 MAT procedures in active-duty military patients, of which 95% (104 patients) were available for follow-up at a minimum 2 years (mean 2.8 ± SD 1.1 year). During the study period, indications for MAT generally included unicompartmental pain and swelling in a postmeniscectomized knee and as a concomitant procedure when a meniscal-deficient compartment was associated with either an ACL revision reconstruction or cartilage repair. Demographic and surgical variables were collected and analyzed. The primary endpoints were the decision for permanent profile activity restrictions and military duty termination by a medical board. The term "medical board" implies termination of military service because of medical reasons. We elected to set statistical significance at p < 0.001 to reduce the potential for spurious statistical findings in the setting of a relatively small sample size. RESULTS: Forty-six percent (48 of 104) of eligible patients had permanent profile activity restrictions and 50% (52 of 104) eventually had their military duty terminated by a military board. Only 20% (21 of 104) had neither permanent profile activity restrictions nor medical-board termination and were subsequently able to return to full duty, and only 13% (13 of 104) continued unrestricted military service beyond 2 years after surgery. Age, gender, tobacco use, and BMI did not correlate with return to full duty. Combat arms soldiers were less likely to have permanent profile activity restrictions (odds ratio 4.76 [95% confidence interval 1.93 to 11.8]; p = 0.001) and were more likely to return to full duty than soldiers in support roles (OR 0.24 [95% CI 0.09 to 0.65]; p = 0.005), although these findings did not reach statistical significance. Officers were more likely to return to full duty than enlisted soldiers at more than 2 years after surgery (OR 17.44 [95% CI 4.56 to 66.65]; p < 0.001). No surgical variables correlated with return-to-duty endpoints. CONCLUSIONS: Surgeons should be aware of the low likelihood of return to military duty at more than 2 years after MAT and counsel patients accordingly. Based on this study, MAT does not appear to be compatible with continued unrestricted military duty for most patients. LEVEL OF EVIDENCE: IV, therapeutic study.

Editorial Commentary: Treatment of Panlabral Shoulder Lesions: The Circle Concept Revisited.

Shoulder instability is common in athletes. Combined labral injuries are also common and appear more frequently in chronic cases, suggesting propagation of smaller tears with each event. Panlabral tears, or 270 tears, represent an extreme form of this phenomenon. Arthroscopy has allowed for improved appreciation of these combined patterns. Although it is essential to fix all labral lesions identified during arthroscopy, it is also crucial to enter surgical cases with a clear diagnosis (i.e., anterior, posterior, or combined instability) to adequately address symptoms.

Arthroscopic Versus Open Bankart Repairs in Recurrent Anterior Shoulder Instability: A Systematic Review of the Association Between Publication Date and Postoperative Recurrent Instability in Systematic Reviews.

PURPOSE: To systematically review the results of systematic studies regarding open versus arthroscopic Bankart repairs for recurrent anterior shoulder instability and quantitatively analyze the effect of primary-literature publication dates on reported outcomes in these systematic studies. METHODS: A systematic search was conducted to identify systematic studies reporting outcomes of both arthroscopic and open Bankart repairs for recurrent anterior shoulder instability. Patient-reported outcome measures, recurrent instability rates, definitions of instability, and procedure types reported by included study characteristics were qualitatively analyzed. Correlation coefficient analyses were performed to investigate if a systematic study's proportion of included primary literature published after 1999, 2000, 2001, or 2002 affected that study's reported mean difference in instability recurrence between open and arthroscopic procedures. The Assessment of Multiple Systematic Reviews criteria were used to assess the risk of bias of the included studies. RESULTS: Of 130 identified articles, 6 met the inclusion criteria. Patient-reported outcome measures were poorly reported. Among mean differences in instability recurrence rates, the results were indeterminate: Although 5 studies reported arthroscopic surgical procedures as having a higher recurrence rate, only 1 reported a statistically significant difference. Within the 5 included systematic reviews reporting the number of included studies, 37 of 56 observations were published after 2000. The proportion of studies published after 2000 (Pearson r = 0.88, P = .052) was positively associated with differences in instability recurrence rates between open and arthroscopic procedures. CONCLUSIONS: Systematic studies that included newer studies (published after 2000) were associated with more favorable arthroscopic outcomes. LEVEL OF EVIDENCE: Level IV, systematic review of Level III and IV studies.

High Case Volume Predicts Greater Odds of Autograft Use and Meniscal Repair for Anterior Cruciate Ligament Reconstruction.

PURPOSE: To evaluate how both annual surgeon and facility volume affect the cost and outcomes of anterior cruciate ligament reconstruction surgery. We also aimed to identify trends in how surgeon caseload predicts graft selection. METHODS: The 2014 State Ambulatory and Surgical Database from Florida was used. Every case with Current Procedural Terminology code 29888 ("Arthroscopic anterior cruciate ligament reconstruction") was selected. Surgeon and facility identifiers were used to separate high- and low-volume groups, defined as >25 cases for surgeons and >125 cases for facilities. Univariate analysis was performed for patient demographics and surgical characteristics. Multivariate analysis was performed on significant factors to determine how these variables impact cost and odds of allograft usage, postoperative admission, and meniscal repair. RESULTS: There were 7905 cases performed between January 1, 2014, and December 31, 2014 after excluding same-year revisions. High-volume surgeons had $6155 lower total charges, were 1.949 times more likely to use an autograft, and had 54.5% lower odds of postoperative admission (all P < .001). They were also 1.196 times more likely to perform a meniscal repair (P = .017). In patients younger than 18, low-volume surgeons were 3.7 times more likely to use an allograft (P < .001). Concomitant multiligamentous procedures were also performed at greater rates in the high-volume group. Postoperative admission added $18,698, and allografts added $9174 (both P < .001). CONCLUSIONS: We found that high-volume surgeons were more likely to perform a meniscal repair and less likely to have their patients admitted postoperatively, which was the second largest cost driver of anterior cruciate ligament reconstruction. They were also significantly less likely to use an allograft, especially in patients younger than the age of 18 years. High-volume surgeons had lower costs despite greater rates of concomitant procedures. LEVEL OF EVIDENCE: III, retrospective cohort study.

Risk of Revision Shoulder Surgery, Complications, and Prolonged Opioid Use in Patients Undergoing Shoulder Arthroscopy Who Have Previously Undergone Anterior Cervical Discectomy and Fusion.

PURPOSE: To compare postoperative complications, rates of revision, and opioid use of those who undergo shoulder arthroscopy with and without previous anterior cervical discectomy and fusion (ACDF). METHODS: The PearlDiver database from 2007 to 2017 was used to query all patients who underwent shoulder arthroscopy as determined by Current Procedural Terminology (CPT). Patients were then separated among those who had a previous instance of ACDF and those who did not as filtered by CPT. Postoperative complications within 30 days, readmission rates, opioid use, and revision procedures were assessed for each cohort using a mix of International Classification of Diseases Ninth and Tenth Revision Clinical Modification codes, CPT, as well as generic drug codes. RESULTS: A total of 91,029 patients undergoing shoulder arthroscopy were identified, of whom 1,267 (1.4%) had a history of ACDF. Compared with patients without previous ACDF, patients with a history of ACDF had significantly greater respiratory complication rates (1.3% vs 0.5%: adjusted odds ratio [aOR] 2.16, 95% confidence interval [CI]1.30-3.59, P = .003), 30-day complication rates (3.7% vs 2.2%: aOR 1.48, 95% CI 1.10-1.99, P = .011), 1-year revision rates (15.2% vs 7.7%: aOR 2.00, 95% CI 1.71-2.33, P < .0001), and greater opioid use at 1 month, 3 months, 6 months, and 12 months (P < .0001). CONCLUSIONS: This study revealed that patients who undergo shoulder arthroscopy with a history of ACDF are twice as likely to undergo revision arthroscopy within 2 years of surgery and are at an increased risk of complications within 30 days postoperatively as well as prolonged opioid use compared with those without a history of ACDF. With these findings, both spine and shoulder surgeons should aim to be more aware of surgical history, especially of the cervical spine, to better counsel patients' clinical course and expected outcomes following shoulder arthroscopy. LEVEL OF EVIDENCE: III, retrospective cohort study.

Incidence of Combat Sport-Related Mild Traumatic Brain Injuries Presenting to the Emergency Department From 2012 to 2016.

OBJECTIVES: We sought to investigate the incidence and characteristics of traumatic brain injuries [mild traumatic brain injury (MTBI)] presenting to the emergency department as a result of boxing, wrestling, and martial arts (MA). DESIGN: Retrospective cross-sectional study of MTBI in combat sport athletes who were evaluated in emergency departments in the United States. SETTING: Patient data were taken from the National Electronic Injury Surveillance System. PARTICIPANTS: All patients with MTBI from 2012 to 2016, which occurred during participation in boxing, MA, or wrestling. INTERVENTIONS: None. MAIN OUTCOME MEASURES: The incidence of combat sport-related MTBI presenting to emergency departments in the United States. RESULTS: The mean annual incidence of MTBI due to wrestling was significantly larger (269.3 per 100 000 person-years) than boxing (85.6 per 100 000 person-years) and MA (61.0 per 100 000 person-years) (P < 0.01). The average age at injury was significantly lower for wrestling compared with boxing and MA (15.0 years [SD ± 3.9] vs 21.7 years [SD ± 8.2] vs 19.9 years [SD ± 10.5]; P < 0.01). A significantly larger proportion of MTBIs (95.3%; P < 0.01) in patients younger than 20 years were related to wrestling, compared with boxing (55.8%) and MA (54.1%). Most patients with combat sport-related MTBIs were treated and discharged (96.3%), with only 1.7% of patients being admitted and 0.6% of patients being held for observation. CONCLUSION: Combat sports athletes are at high risk of sustaining an MTBI. Such athletes presenting to the emergency department for combat sport-related MTBI were more likely to be male and younger than 20 years. Of these athletes, wrestlers experience the highest incidence of MTBI-related emergency department visits.

Distal-Less Homeobox 5 Is a Therapeutic Target for Attenuating Hypertrophy and Apoptosis of Mesenchymal Progenitor Cells.

Chondrocyte hypertrophy is a hallmark of osteoarthritis (OA) pathology. In the present study, we elucidated the mechanism underlying the relationship between the hypertrophy/apoptotic phenotype and OA pathogenesis in bone marrow-derived mesenchymal stem cells (BM-MSCs) via gene targeting of distal-less homeobox 5 (DLX5). Our primary objectives were (1) to determine whether DLX5 is a predictive biomarker of cellular hypertrophy in human osteoarthritic tissues; (2) To determine whether modulating DLX5 activity can regulate cell hypertrophy in mesenchymal stem/progenitor cells from marrow and cartilage. Whole transcriptome sequencing was performed to identify differences in the RNA expression profile between human-cartilage-derived mesenchymal progenitors (C-PCs) and bone-marrow-derived mesenchymal progenitors (BM-MSCs). Ingenuity Pathway Analysis (IPA) software was used to compare molecular pathways known to regulate hypertrophic terminal cell differentiation. RT-qPCR was used to measure DLX5 and hypertrophy marker COL10 in healthy human chondrocytes and OA chondrocytes. DLX5 was knocked down or overexpressed in BM-MSCs and C-PCs and RT-qPCR were used to measure the expression of hypertrophy/terminal differentiation markers following DLX5 modulation. Apoptotic cell activity was characterized by immunostaining for cleaved caspase 3/7. We demonstrate that DLX5 and downstream hypertrophy markers were significantly upregulated in BM-MSCs, relative to C-PCs. DLX5 and COL10 were also significantly upregulated in cells from OA knee joint tissues, relative to normal non-arthritic joint tissues. Knocking down DLX5 in BM-MSCs inhibited cell hypertrophy and apoptotic activity without attenuating their chondrogenic potential. Overexpression of DLX5 in C-PCs stimulated hypertrophy markers and increased apoptotic cell activity. Modulating DLX5 activity regulates cell hypertrophy and apoptosis in BM-MSCs and C-PCs. These findings suggest that DLX5 is a biomarker of OA changes in human knee joint tissues and confirms the DLX5 mechanism contributes to hypertrophy and apoptosis in BM-MSCs.