A Patella-Sided Tensioning Technique for Medial Patellofemoral Ligament Reconstruction.

Reconstruction of the medial patellofemoral ligament (MPFL) is a common procedure for treatment of recurrent patellofemoral instability. Over the last two decades, multiple surgical techniques for MPFL reconstruction have been described with no clear consensus on a superior reconstruction technique. Appropriate graft tensioning is one of the most important factors for a successful MPFL reconstruction. Overtensioning of the MPFL graft can lead to patellofemoral joint overload and undertensioning can lead to recurrent instability. Current literature demonstrates descriptions of MPFL reconstruction with final graft tensioning performed off of the femoral side. We describe a technique in this article for performing final graft tensioning from the patellar side, which gives the surgeon an option for intraoperative tension adjustments after evaluating patellar tracking.

Is fantasy baseball score a viable outcome measure for professional baseball pitchers after undergoing Tommy John surgery?

Hypothesis and Background: Although on-field performance metrics are useful in measuring overall success of ulnar collateral ligament (UCL) reconstruction (UCLR) in professional baseball pitchers, they may not comprehensively quantify athletic performance after returning to playing in the league. To utilize fantasy baseball score (FBS) as a novel and objective outcome to assess the quality of return to play in major league baseball (MLB) pitchers who went back to professional pitching after UCLR. Methods: This is a retrospective observational cohort study of 216 established MLB pitchers who underwent UCLR while in the MLB between the years 1974 and 2018. Pitchers who either started in at least 45 games or pitched 90 relief games in the 3 years leading up to injury were included. FBS was calculated using 3 different scoring methods: ESPN (Entertainment and Sports Programming Network) (FBS-ESPN), Yahoo (FBS-Yahoo), and CBS (Columbia Broadcasting System) (FBS-CBS). Return to play, games played, innings pitched, earned runs, strikeouts, walks, hits allowed, hit batsman, and quality starts were also collected. Performance records were compiled for 3 years prior to and after the return to MLB. Players' pre-injury performance was used as a historic control group. Multivariate linear regression analysis was used to detect trends between seasons, controlling for year of surgery, and number of games. Results: The mean age of the cohort at the time of surgery was 30.0 ± 3.5 years. One hundred seventy-nine of 216 players (83%) returned to MLB play, taking an average of 16.6 ± 5.8 months. One hundred thirty-six of 179 (76%) remained in the league for 3 seasons. After adjusting for year of surgery, pitchers earned significantly fewer points for FBS-CBS (616.45 ± 332.42 vs. 389.12 ± 341.06; P < .001), FBS-Yahoo (801.90 ± 416.88 vs. 492.57 ± 428.40; P < .001), and FBS-ESPN (552.76 ± 275.77 vs. 344.19 ± 300.45; P < .001) after their injury. Also pitchers played in fewer games, pitched fewer innings, and had a decline in all measured on-field performance statistics. Conclusion: FBS may represent a useful outcome measure to objectively assess the quality of return to play in a professional baseball pitcher who returned to play in MLB after UCLR.

Vaccines for immunoprevention of DNA mismatch repair deficient cancers.

The development of cancer vaccines to induce tumor-antigen specific immune responses was sparked by the identification of antigens specific to or overexpressed in cancer cells. However, weak immunogenicity and the mutational heterogeneity in many cancers have dampened cancer vaccine successes. With increasing information about mutational landscapes of cancers, mutational neoantigens can be predicted computationally to elicit strong immune responses by CD8 +cytotoxic T cells as major mediators of anticancer immune response. Neoantigens are potentially more robust immunogens and have revived interest in cancer vaccines. Cancers with deficiency in DNA mismatch repair have an exceptionally high mutational burden, including predictable neoantigens. Lynch syndrome is the most common inherited cancer syndrome and is caused by DNA mismatch repair gene mutations. Insertion and deletion mutations in coding microsatellites that occur during DNA replication include tumorigenesis drivers. The induced shift of protein reading frame generates neoantigens that are foreign to the immune system. Mismatch repair-deficient cancers and Lynch syndrome represent a paradigm population for the development of a preventive cancer vaccine, as the mutations induced by mismatch repair deficiency are predictable, resulting in a defined set of frameshift peptide neoantigens. Furthermore, Lynch syndrome mutation carriers constitute an identifiable high-risk population. We discuss the pathogenesis of DNA mismatch repair deficient cancers, in both Lynch syndrome and sporadic microsatellite-unstable cancers. We review evidence for pre-existing immune surveillance, the three mechanisms of immune evasion that occur in cancers and assess the implications of a preventive frameshift peptide neoantigen-based vaccine. We consider both preclinical and clinical experience to date. We discuss the feasibility of a cancer preventive vaccine for Lynch syndrome carriers and review current antigen selection and delivery strategies. Finally, we propose RNA vaccines as having robust potential for immunoprevention of Lynch syndrome cancers.

Impact of COVID-19 on Primary Care Quality Measures in an Academic Integrated Health System.

BACKGROUND: Access to primary care was hindered by the coronavirus disease 2019 (COVID-19) pandemic. OBJECTIVE: Evaluate changes in health screening rates before and during the pandemic. DESIGN: Retrospective analysis of health maintenance and disease management screening rates among primary care patients before and during the pandemic. PARTICIPANTS: Over 150,000 patients of a large, academic health system. MAIN MEASURES: Six quality measures were analyzed: colon cancer, breast cancer, cervical cancer, diabetes Hgb A1C, diabetes eye, and diabetes nephropathy monitoring. Based on US Preventative Services Task Force screening guidelines, we determined which patients were due for at least one of the quality measures. We tracked completion rates during three time periods: pre-pandemic (January 1-March 3, 2020), stay-at-home (March 4-May 8, 2020), and phased reopening (May 9-July 8, 2020). Differences in quality measure completion rates were evaluated using mixed-effects logistic regression models. KEY RESULTS: Compared to pre-pandemic rates, completion of all health screenings declined during the stay-at-home period: mammograms (OR: 0.34; 95% CI: 0.31-0.37), cervical cancer (OR: 0.83; 95% CI: 0.76-0.91), colorectal cancer (OR: 0.25; 95% CI: 0.23-0.28), diabetes eye (OR: 0.34; 95% CI: 0.29-0.41), diabetes Hgb A1c (OR: 0.41; 95% CI: 0.37-0.46), and diabetes nephropathy (OR: 0.46, 95% CI: 0.41-0.53). During phased reopening, completion of all quality measures increased compared to the stay-at-home period, except for cervical cancer screening (OR: 0.83; 95% CI: 0.76-0.92). There was a persistent reduction in completion of all quality measures, except for diabetic nephropathy monitoring (OR: 0.99; 95% CI: 0.89-1.09), during phased reopening compared to pre-pandemic. CONCLUSIONS: Healthcare screening rates were reduced during the early part of the COVID-19 pandemic and did not fully recover to pre-pandemic rates by July 2020. Future research should aim to clarify the long-term impacts of delayed health screenings. New interventions should be considered for expanding remote preventative health services.

Are Orthopaedic Trauma Surgeons Adequately Compensated for Longer Procedures? An Analysis of Relative Value Units and Operative Times From the American College of Surgeons National Surgical Quality Improvement Program Database.

BACKGROUND: The physician work relative value unit (wRVU) scale is the primary determinant of compensation. Operative time, technical skill, effort, and surgical complexity contribute to wRVU allocation. The aim of this study was to identify the relationship between these factors and reimbursement for trauma procedures. METHODS: The National Surgical Quality Improvement Program database was queried for orthopaedic trauma procedures from 2016 to 2018. Physician wRVU data were obtained from the 2020 Centers for Medicare & Medicaid Services fee schedule. The primary outcome measured was mean wRVU per minute of operative time (wRVU/min). Wilcoxon rank sum test and quantile regression were used to determine the association between wRVU, operative time, complication rate, upper or lower extremity procedure, and wRVU/min. RESULTS: Sixty-three current procedural terminology codes or 107,171 cases were queried. Median wRVU/min was significantly lower for longest 50% of procedures (0.119 vs. 0.160, P < 0.001) and higher for the top 50% with regard to complication rate (0.161 vs. 0.124, P < 0.001). Upper extremity procedures were reimbursed less than lower extremity (0.110 vs. 0.145, P < 0.001). Quintile regression showed that adjusted for complication rate, median wRVU/min decreased by 0.0005 (95% confidence interval: 0.0007-0.0003, R1 = 0.27, P < 0.001) for every additional minute of operative time. CONCLUSIONS: The 2020 wRVU scale does not allocate sufficient wRVUs to orthopaedic trauma procedures with longer mean operative time or to procedures performed on the upper extremity. There is a negative correlation between operative time and hourly reimbursement, equating to a decrease of $64.96/h per hour of operation.

Factors associated with response and remission from depression at 6-months of treatment in a retrospective cohort treated within an integrated care program.

BACKGROUND: Depression causes significant morbidity, which impacts mental health, overall general health outcomes, everyday functioning and quality of life. This study aims to contribute to knowledge in the field through enhanced understanding of factors that influence depression response and remission, with consideration for design of treatment services to optimize depression outcomes within integrated care programs. METHODS: Using routine behavioral health screening and electronic health record data, we identified a retrospective cohort consisting of 615 adult patients receiving depression treatment within an integrated care program. Cohort member Patient Health Questionnaire (PHQ-9) data was analyzed for the 6 months following initiation of treatment. Multinomial regression models were estimated to identify factors associated with depression treatment response (PHQ-9 < 10) and remission (PHQ-9 < 5). RESULTS: At 6 months, 47% of patients demonstrated treatment response and 16% demonstrated remission. Baseline trauma symptoms and suicidal ideation were significantly associated with decreased odds of achieving remission (Odds Ratio (95% CI) [OR] = 0.45 (0.23, 0.88) and OR = 0.49 (0.29, 0.82), respectively). In fully adjusted models, baseline suicidal ideation remained significant (OR = 0.53 (0.31, 0.89)) and some evidence of an association persisted for baseline trauma symptoms (OR = 0.51 (0.25, 1.01)). CONCLUSIONS: After controlling for baseline depression symptoms, the presence of suicidal ideation is associated with reduced likelihood of remission. Increased understanding of factors associated with depression treatment outcomes may be employed to help guide the delivery and design of clinical services. Alongside routine screening for co-morbid anxiety, suicidal ideation and traumatic stress should be assessed and considered when designing depression treatment services.

Using web-based technology to improve depression screening in primary care settings.

BACKGROUND: Given the high rates at which patients present with behavioural health (BH) concerns in primary care (PC), this setting has become the de facto mental health system. As a result, screening for depression and other BH conditions in PC has become a critical target for improving patient outcomes. However, integration of screening into busy PC workflows can be challenging due to barriers such as limited time and resources. METHODOLOGY: A digital, cloud-based BH assessment tool, which included electronic health record enhancements, was developed and implemented in two urban PC practices as a prelude to a planned larger-scale implementation. The implementation strategies included a reorganisation of workflows within the PC setting, comprehensive training for staff and PC physicians, and institution of an incentive programme for PC clinic managers. To examine whether the introduction of the cloud-based BH assessment tool and associated implementation strategies was associated with increased screening rates, we compared rates of screening from January through June 2017 to rates of screening from January through June 2018 (subsequent to implementation). We also examined BH symptomatology reported by patients in PC. RESULTS: Following the implementation process, rate of BH screening with Patient Health Questionnaire-2 (PHQ-2) increased from 50.5% to 57% (p<0.00000000000000022) and rates of subsequent screening with PHQ-9, for those scoring at risk, defined as a score of ≥1, on PHQ-2, increased from 34.5% to 91.4% (p<0.00000000000000022). Additionally, high rates of 'moderate' and 'severe' symptoms of depression (40.3%), anxiety (42.6%) and substance use (26.7% alcohol; 31.2% other substance use) were observed among PC patients. CONCLUSIONS: Results suggest that a comprehensive implementation plan, including digitisation of BH assessment, reduced the burden of systematic screening. High rates of BH symptomatology underscore the need for comprehensive BH assessment and systems planning to address the high need for BH services among PC patients.

John Dalton's "Aha" Moment: the Origin of the Chemical Atomic Theory.

In his only known historical sketch addressing the origin of the chemical atomic theory, John Dalton stated that different atoms have different sizes, a conclusion which led him to an investigation of combining number of atoms and relative weights. Although he stated the idea occurred to him in 1805, his laboratory notes show he developed the first table of atomic weights in 1803. Historians over the years have provided conflicting narratives to explain the different dates. In this paper, I examine Dalton's activities as a creative individual and a practicing chemist, arguing that Dalton's concept of atomic size was not an "aha" moment occurring in 1805, but one that he used right from the start in 1803 to develop his chemical atomic theory. The concepts of atomic size and relative atomic weights emerged in 1803 from his investigations into caloric and the composition of nitric acid, respectively, not from his studies on gaseous solubility. In 1805, Dalton applied his 1803 concept of atomic size to explain a different problem, one of gaseous diffusion. Dalton's 1805 epiphany should join the stage with other great insights in the history of science, such as those of Archimedes, Kekulé, and Poincaré.

Current Relative Value Unit Scale Does Not Appropriately Compensate for Longer Orthopedic Sports Surgeries.

PURPOSE: To assess whether reimbursement for orthopaedic sports procedures adequately compensates for operative time and surgical complexity. METHODS: The National Surgical Quality Improvement Program (NSQIP) database was queried for all orthopedic sports medicine procedures performed greater than 150 times from 2016 to 2018 with regard to operative time, preoperative risk factors, morbidity, and mortality data. Physician work relative value units (wRVU) data were obtained from the 2020 Centers for Medicare & Medicaid Services (CMS) fee schedule. The primary outcome was wRVU per minute operative time (wRVU/min). Linear regressions were used to assess wRVU, operative time, and wRVU/min. RESULTS: A total of 42 CPT codes, including 84,966 cases, were stratified into the top and bottom 50%, according to mean operative time, complications, mortality, reoperations, and readmissions. Mean wRVU/min was significantly lower for longer procedures (.153 vs .187; P = .02), and comparable with regard to ASA score, complications, mortality, readmissions, and reoperations. Arthroscopy reimbursed more (.187 vs .148 wRVU/min; P = .008), with lower complications (1.5 vs 2.6%; P = .115) and operative time (56.1 vs 82.8 min; P = .001) compared to open. Multivariate linear regression revealed that after adjusting for complication rate, there was a decrease of .054 wRVU/h (P = .026) and $116.90/hour less for every additional hour of operative time. CONCLUSION: The current 2020 RVU scale does not fairly compensate sports procedures with longer operative times. When examining the hourly reimbursement rates for the most commonly performed sports procedures, there is a significant trend toward lower reimbursement for longer procedures even after accounting for complication rates. Furthermore, procedures of the knee reimbursed at higher rates relative to the general pool of sports procedures and open procedures are compensated at a lower rate compared to arthroscopic procedures.

Suboptimal stimulation by weak agonist epitope variants does not drive dysfunction of HIV-1-specific cytotoxic T lymphocyte clones.

OBJECTIVE: To assess whether weakly recognized epitope variants induce anergy in HIV-1-specific CD8 T lymphocyte (CTL) clones as a mechanism of dysfunction. DESIGN: HIV-1-specific CTL clones were exposed to suboptimally recognized epitope variants, and screened for anergy and other T-cell dysfunction markers, and subsequent capability to kill target cells bearing index epitope. METHODS: In addition to the optimally recognized index epitope, two suboptimally recognized epitope variants were selected based on titration curves for killing of peptide-labeled target cells by three HIV-1-specific CTL clones targeting the epitopes SLYNTVATL (Gag 77-85, A02-restricted), RPAEPVPLQL (Rev 66-75, B07-restricted), and KRWIIMGLNK (Gag 263-272, B27-restricted). Consequences of suboptimal stimulation were assessed by cytokine secretion, gene expression, and capacity to kill index epitope-labeled target cells upon rechallenge. RESULTS: Suboptimal recognition of epitope variants reduced cytokine production by CTL similarly to reduction in killing of target cells. Gene expression profiles after suboptimal stimulation demonstrated no patterns consistent with T-cell dysfunction due to anergy, exhaustion, or apoptosis. Preexposure of CTL to epitope variants had no discernable impact on their subsequent capacity to kill index epitope-bearing target cells. CONCLUSION: Our data explore the hypothesis that poorly recognized epitope variants not only facilitate HIV-1 evasion of CTL recognition, but also induce CTL dysfunction through suboptimal signaling causing anergy. However, the results do not suggest that suboptimal signaling induces anergy (or exhaustion or apoptosis), indicating that the major role of CTL epitope variation is likely viral escape.

A Multi-Level Fit-Based Quality Improvement Initiative to Improve Colorectal Cancer Screening in a Managed Care Population.

INTRODUCTION: Colorectal cancer (CRC) is a common but largely preventable disease with suboptimal screening rates despite national guidelines to screen individuals age 50-75. Single-component interventions aimed to improve screening uptake only modestly improve rates; data suggest that multi-modal approaches may be more effective. METHODS: We designed, implemented, and evaluated the impact of a multi-modal intervention on CRC screening uptake among unscreened patients in a large managed care population. Patient-level components included a mailed letter with education about screening options and pre-colonoscopy telephone counseling. For providers, we facilitated communication of screening test results and work-flow for abnormal results. System-level modifications included establishment of a patient navigator, expedited work-up for abnormal results, and stream-lined colonoscopy scheduling. We measured the rate of screening uptake overall, screening uptake by modality, change in the proportion of the population screened, and positive fecal immunochemical test (FIT) follow-up rates in the 1-year study period. RESULTS: There were 5093 patients in the intervention cohort. Of these, 33.2% participated in FIT or colonoscopy screening within 1 year of the mailing. A total of 1078 (21.2%) participants completed a FIT and 611 (12.0%) completed a screening colonoscopy. The screening rate in the managed care population increased from 65.1 to 76.6%. Fifty-nine patients (5.5%) had a positive FIT, of which 30 (50.8%) completed a diagnostic colonoscopy. CONCLUSION: Multi-modal interventions can result in substantial improvement in CRC screening uptake in large and diverse managed care populations. TRANSLATIONAL IMPACT: Health systems should shift their focus from single-level to multi-level interventions when addressing barriers to CRC screening.

John Dalton and the origin of the atomic theory: reassessing the influence of Bryan Higgins.

During the years 1814-1819, William Higgins, an Irish chemist who worked at the Dublin Society, claimed he had anticipated John Dalton in developing the atomic theory and insinuated that Dalton was a plagiarist. This essay focuses not on William Higgins, but on his uncle Bryan Higgins, a well-known chemist of his day, who had developed his own theories of caloric and chemical combination, similar in many respects to that of Dalton. New evidence is first introduced addressing Bryan's disappearance from the scientific community after 1803. In his later years, Bryan apparently suffered from a condition resulting in a decline in his mental health, which explains why he never lodged any priority claims of his own against Dalton, or defended those of his nephew. Dalton's mention of Bryan's name in Part II of A New System of Chemical Philosophy, his laboratory notebook entries, and a fresh look at his correspondence with chemist Thomas Charles Hope indicate that Dalton adopted a Higgins-like caloric model in 1803. Together these factors provide evidence to support the argument that Dalton learned of Bryan's theories via a meeting he had with William Allen on 10 July 1803. Existing evidence related to the origin of the atomic theory is worthy of re-examination in light of Dalton's possible prior knowledge of Bryan's work.

Sequence-specific DNA binding by MYC/MAX to low-affinity non-E-box motifs.

The MYC oncoprotein regulates transcription of a large fraction of the genome as an obligatory heterodimer with the transcription factor MAX. The MYC:MAX heterodimer and MAX:MAX homodimer (hereafter MYC/MAX) bind Enhancer box (E-box) DNA elements (CANNTG) and have the greatest affinity for the canonical MYC E-box (CME) CACGTG. However, MYC:MAX also recognizes E-box variants and was reported to bind DNA in a "non-specific" fashion in vitro and in vivo. Here, in order to identify potential additional non-canonical binding sites for MYC/MAX, we employed high throughput in vitro protein-binding microarrays, along with electrophoretic mobility-shift assays and bioinformatic analyses of MYC-bound genomic loci in vivo. We identified all hexameric motifs preferentially bound by MYC/MAX in vitro, which include the low-affinity non-E-box sequence AACGTT, and found that the vast majority (87%) of MYC-bound genomic sites in a human B cell line contain at least one of the top 21 motifs bound by MYC:MAX in vitro. We further show that high MYC/MAX concentrations are needed for specific binding to the low-affinity sequence AACGTT in vitro and that elevated MYC levels in vivo more markedly increase the occupancy of AACGTT sites relative to CME sites, especially at distal intergenic and intragenic loci. Hence, MYC binds diverse DNA motifs with a broad range of affinities in a sequence-specific and dose-dependent manner, suggesting that MYC overexpression has more selective effects on the tumor transcriptome than previously thought.

Delivering On Accountable Care: Lessons From A Behavioral Health Program To Improve Access And Outcomes.

Patients with behavioral health disorders often have worse health outcomes and have higher health care utilization than patients with medical diseases alone. As such, people with behavioral health conditions are important populations for accountable care organizations (ACOs) seeking to improve the efficiency of their delivery systems. However, ACOs have historically faced numerous barriers in implementing behavioral health population-based programs, including acquiring reimbursement, recruiting providers, and integrating new services. We developed an evidence-based, all-payer collaborative care program called Behavioral Health Associates (BHA), operated as part of UCLA Health, an integrated academic medical center. Building BHA required several innovations, which included using our enterprise electronic medical record for behavioral health referrals and documentation; registering BHA providers with insurance plans' mental health carve-out products; and embedding BHA providers in primary care practices throughout the UCLA Health system. Since 2012 BHA has more than tripled the number of patients receiving behavioral health services through UCLA Health. After receiving BHA treatment, patients had a 13 percent reduction in emergency department use. Our efforts can serve as a model for other ACOs seeking to integrate behavioral health care into routine practice.

PHYSICAL THERAPY INTERVENTION FOR MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION AFTER REPEATED LATERAL PATELLAR SUBLUXATION/DISLOCATION.

BACKGROUND: The incidence of patellar subluxation or dislocation has been documented up to 43/100,000 with females more prevalent then males. There are many contributing factors involving the hip, knee, and ankle that lead to patellar subluxation. A patellar position of lateral tilt with lateral glide may indicate weakness of the vastus medialis oblique (VMO) and adductors, increased tightness in the iliotibial band, and overpowering of the vastus lateralis. Patella alta can predispose an individual to lateral dislocation due to the patella placement outside of the femoral trochlear groove with a disadvantage of boney stability. Other factors that may cause the patella to laterally sublux or dislocate during a functional activity or sporting activity include a position of femoral external rotation, tibial internal rotation, and excessive contraction of the vastus lateralis. The medial patellofemoral ligament (MPFL) aids in the prevention of a lateral patellar subluxation or dislocation. In cases where there is recurrent subluxation/dislocation and Magnetic Resonance Imaging confirms a MPFL tear, a reconstruction may be the treatment of choice. PURPOSE: The purpose of this case series is to describe the post-surgical physical therapy management of MPFL reconstructions, outcomes using the Modified Cincinnati Knee Outcome Measure (MCKOM) and to propose staged physical therapy interventions for this pathology in the form of a treatment progression. METHODS: Post-operative management data and outcomes were retrospectively collected using a detailed chart review methodology from seven subjects who underwent MPFL reconstruction. FINDINGS: The Modified Cincinnati Knee Outcome Measure (MCKOM) was analyzed for each participant in four sections that were most important to the return and maintenance of participation in sport. At follow-up the mean scores for the seven subjects in Section 3 (instability) was 19.3/20, Section 4 (overall activity level) was 17.3/20, Section 7 (running activity) was 4.5/5, and Section 8 (jumping and twisting) was 4.3/5. Overall all subjects scored over an 80 which indicated excellent results for return to activity/sport. CONCLUSIONS: In this case series, seven subjects after MPFL reconstruction returned to sport or functional activity following a physical therapy treatment progression including proprioceptive-focused, and dynamic rehabilitation, along with a home exercise program. Based on these positive results and a review of relevant literature regarding MPFL rehabilitation, a rehabilitation progression was presented. LEVEL OF EVIDENCE: Level 4- Case Series.

Effect of elbow flexion on the proximity of the PIN during 2-incision distal biceps repair.

The posterior interosseous nerve (PIN) is at risk for injury during surgical dissection for distal biceps repair, yet the optimal position of elbow flexion to avoid a PIN injury has never been established for the 2-incision approach. The purpose of this study was to determine the proximity of the PIN to the radial tuberosity during surgical dissection in different degrees of elbow flexion. Ten cadaveric specimens with an intact elbow and forearm were dissected in full pronation using a modified Boyd-Anderson approach. Half of the dissections were completed in 90° of flexion and the other half were completed in maximal flexion. To simulate the location of the PIN during a single-incision biceps repair, the distance of the PIN to the radial tuberosity was recorded in full extension and supination. Results from these measurements were assessed for differences using paired t tests, with differences deemed significant for P values less than .05. The PIN was not identified in any of the 2-incision surgical dissections. Based on these findings, the proximity of the PIN to the radial tuberosity is not significantly affected by the degree of elbow flexion in the muscle-splitting 2-incision approach. In addition, a safe zone exists for avoiding PIN injury in a single-incision technique for distal biceps repair because a drill bit exiting the radial tuberosity greater than 1 cm in a distal-radial direction would place the PIN at risk.

Single-row modified mason-allen versus double-row arthroscopic rotator cuff repair: a biomechanical and surface area comparison.

PURPOSE: The purpose of this study was to compare the time-zero biomechanical strength and the surface area of repair between a single-row modified Mason-Allen rotator cuff repair and a double-row arthroscopic repair. METHODS: Six matched pairs of sheep infraspinatus tendons were repaired by both techniques. Pressure-sensitive film was used to measure the surface area of repair for each configuration. Specimens were biomechanically tested with cyclic loading from 20 N to 30 N for 20 cycles and were loaded to failure at a rate of 1 mm/s. Failure was defined at 5 mm of gap formation. RESULTS: Double-row suture anchor fixation restored a mean surface area of 258.23 +/- 69.7 mm(2) versus 148.08 +/- 75.5 mm(2) for single-row fixation, a 74% increase (P = .025). Both repairs had statistically similar time-zero biomechanics. There was no statistical difference in peak-to-peak displacement or elongation during cyclic loading. Single-row fixation showed a higher mean load to failure (110.26 +/- 26.4 N) than double-row fixation (108.93 +/- 21.8 N). This was not statistically significant (P = .932). All specimens failed at the suture-tendon interface. CONCLUSIONS: Double-row suture anchor fixation restores a greater percentage of the anatomic footprint when compared with a single-row Mason-Allen technique. The time-zero biomechanical strength was not significantly different between the 2 study groups. This study suggests that the 2 factors are independent of each other. CLINICAL RELEVANCE: Surface area and biomechanical strength of fixation are 2 independent factors in the outcome of rotator cuff repair. Maximizing both factors may increase the likelihood of complete tendon-bone healing and ultimately improve clinical outcomes. For smaller tears, a single-row modified Mason-Allen suture technique may provide sufficient strength, but for large amenable tears, a double row can provide both strength and increased surface area for healing.

Biomechanical evaluation after five and ten millimeter anterior glenohumeral capsulorrhaphy using a novel shoulder model of increased laxity.

Anterior instability of the shoulder is classically treated with a capsulolabral repair, but in cases of capsular redundancy, shortening or shifting of the capsule is added. This study compared glenohumeral translations in intact shoulders after rotational stretching of the capsule and after progressive increasing of anterior-inferior capsular shifts. Seven cadaveric shoulders were mounted on a custom biomechanical testing apparatus. Rotational range of motion and glenohumeral translations were measured. To create laxity, the shoulders were rotationally stretched an additional 30% from the intact rotational range of motion about the axis of the humerus in external and internal rotation. Anterior-inferior capsular shifts of 5 and 10 mm were performed. Rotational stretching of the shoulder capsule created anterior laxity. A 5 mm capsular shift was ineffective, but a 10 mm shift restored anterior and total anteroposterior translation to the intact condition.

A cadaveric model of the throwing shoulder: a possible etiology of superior labrum anterior-to-posterior lesions.

BACKGROUND: It has been speculated that a shift of the throwing arc commonly develops in athletes who perform overhead activities, resulting in greater external rotation and decreased internal rotation caused by anterior capsular laxity and posterior capsular contracture, respectively. Osseous adaptation in the form of increased humeral and glenoid retroversion may provide a protective function in the asymptomatic athlete but cannot explain the pathological changes seen in the shoulder of the throwing athlete. Therefore, the objective of the present study was to examine the biomechanical effects of capsular changes in a cadaveric model. METHODS: Ten cadaveric shoulders were tested with a custom shoulder-testing device. Humeral rotational range of motion, the position of the humerus in maximum external rotation, and glenohumeral translations in the anterior, posterior, superior, and inferior directions were measured with the shoulder in 90 degrees of abduction. Translations were measured with the humerus secured in 90 degrees of external rotation. To simulate anterior laxity due to posterior capsular contracture, the capsule was nondestructively stretched 30% beyond maximum external rotation with the shoulder in 90 degrees of abduction. This was followed by the creation of a 10-mm posterior capsular contracture. Rotational, humeral shift, and translational tests were performed for the intact normal shoulder, after anterior capsular stretching, and after simulated posterior capsular contracture. RESULTS: Nondestructive capsular stretching resulted in a significant increase in external rotation (average increase, 18.2 degrees 2.1 degrees ; p < 0.001), and subsequent simulated posterior capsular contracture resulted in a significant decrease in internal rotation (average decrease, 8.8 degrees +/- 2.3 degrees ; p = 0.02). There also was a significant increase in anterior translation with the application of a 20-N anterior translational force after nondestructive capsular stretching (average increase, 1.7 +/- 0.3 mm, p = 0.0006). The humeral head translated posteroinferiorly when the humerus was rotated from neutral to maximum external rotation. This did not change significantly in association with anterior capsular stretching. Following simulated posterior capsular contracture, there was a trend toward a more posterosuperior position of the humeral head with the humerus in maximum external rotation in comparison with the position in the stretched conditions, although these differences were not significant. CONCLUSIONS: A posterior capsular contracture with decreased internal rotation does not allow the humerus to externally rotate into its normal posteroinferior position in the cocking phase of throwing. Instead, the humeral head is forced posterosuperiorly, which may explain the etiology of Type-II superior labrum anterior-to-posterior lesions in overhead athletes.