Arthroscopic tissue biopsy as a preoperative diagnostic test for periprosthetic shoulder arthroplasty infections: a systematic review and meta-analysis.

BACKGROUND: The diagnosis of periprosthetic infection in shoulder arthroplasty remains a challenge. Conventional methods for evaluating periprosthetic joint infections are poor because of lower-virulence organisms affecting the shoulder. The aim of our systematic review was to evaluate the diagnostic accuracy of preoperative arthroscopic tissue cultures compared with tissue biopsy samples obtained at the time of revision surgery. MATERIALS AND METHODS: We conducted a systematic search of the MEDLINE, Embase, and Cochrane Central databases. The inclusion criteria consisted of studies that used arthroscopy to obtain preoperative tissue cultures for the diagnosis of shoulder arthroplasty infections. Studies were excluded if they obtained non-arthroscopic tissue samples. We reported the sensitivity, specificity, positive predictive value, and negative predictive value. Culture findings from the arthroscopic biopsy samples were also compared with conventional tests of fluoroscopy-guided joint aspiration and serum inflammatory marker testing (positive erythrocyte sedimentation rate or C-reactive protein) within the included studies. A meta-analysis was performed to assess the overall diagnostic accuracy of the studies. RESULTS: Our search strategy yielded 795 potentially relevant publications; 572 underwent title and abstract screening, and 14 studies underwent full-text review, of which 7 were included in our systematic review. The studies represented a balance of shoulder arthroplasty types, including anatomic total shoulder arthroplasty (n = 75, 38%), reverse total shoulder arthroplasty (n = 60, 30%), and hemiarthroplasty (n = 64, 32%). There were 56 of 120 arthroscopic procedures that returned positive tissue culture findings compared with 64 of 157 positive open biopsy culture findings obtained from revision surgery. The meta-analysis total for sensitivity and specificity for all studies combined indicated that arthroscopic tissue cultures (0.76 [95% confidence interval (CI), 0.57-0.88] and 0.91 [95% CI, 0.79-0.97], respectively) were superior to both aspiration (0.15 [95% CI, 0.03-0.48] and 0.93 [95% CI, 0.65-0.99], respectively) and a positive erythrocyte sedimentation rate or C-reactive protein level (0.14 [95% CI, 0.02-0.62] and 0.83 [95% CI, 0.56-0.95], respectively) in diagnosing periprosthetic shoulder infections. CONCLUSIONS: Our systematic review demonstrated that preoperative arthroscopic tissue biopsy used for microbiology cultures accurately predicts intraoperative culture findings obtained during revision surgery with high sensitivity and specificity. Additionally, arthroscopy appears to be superior to conventional techniques of joint aspiration and inflammatory marker testing. Therefore, arthroscopic tissue cultures may be an emerging useful tool to help guide the management of periprosthetic infections in shoulder arthroplasty.

Long-term survivorship of open débridement and débridement arthroplasty for elbow arthritis: a retrospective chart review.

BACKGROUND: Open débridement and Outerbridge-Kashiwagi (OK) débridement arthroplasty (OK procedure) are common surgical treatments for elbow arthritis, but little is known about their long-term survivorship. The purpose of this study was to determine whether survivorship until conversion to total elbow replacement and revision surgery was better for the OK procedure compared with open débridement. METHODS: We performed a retrospective chart review of patients who underwent open elbow surgical débridement (open débridement or OK procedure) between 2000 and 2015. Patients received a diagnosis of primary elbow osteoarthritis, post-traumatic arthritis, or inflammatory arthritis. A total of 320 patients underwent surgery including open débridement (n = 142) or the OK procedure (n = 178), and of these patients, 33 required secondary revision surgery (open débridement, n = 14; OK procedure, n = 19). The average time since surgery was 11.5 years (range, 5.5-21.5 years). Survivorship was analyzed with Kaplan-Meier curves and the log rank test. A Cox proportional hazards model was used to estimate the effect of the type of procedure, index diagnosis, age, and sex on survivorship. RESULTS: Kaplan-Meier survival curves showed survivorship rates until total elbow arthroplasty of 100.0% at 1 year, 99.3% at 5 years, and 98.5% at 10 years for open débridement and 100.0% at 1 year, 98.8% at 5 years, and 98.0% at 10 years for the OK procedure (P = .87). There was no difference in survivorship between procedures, even after adjustment for significant covariates. The rates of revision for open débridement and the OK procedure were similar, at 11.3% and 11.5%, respectively, after 10 years. Higher rates of revision surgery were observed in patients who underwent open débridement (hazard ratio, 4.84; 95% confidence interval, 1.29-18.17; P = .019) compared with those who underwent the OK procedure after adjustment for covariates. We performed a stratified analysis with radiographic severity as an effect modifier and showed that patients with grade 3 arthritis fared better after the OK procedure compared with open débridement in terms of survivorship until revision surgery (P = .05). However, such a difference was not found for grade 1 or grade 2 arthritis. CONCLUSION: We showed that both open elbow débridement and the OK procedure had excellent survivorship until conversion to total elbow arthroplasty and are viable options in the treatment of primary elbow osteoarthritis and post-traumatic cases that could help delay the need for total elbow arthroplasty. Patients with more severe radiographic arthritis, specifically grade 3 arthritis, were less likely to require revision surgery if treated initially with the OK procedure compared with open débridement.

Preoperative Exercise Rehabilitation in Cardiac and Vascular Interventions.

BACKGROUND: Exercise-based interventions have become part of the standard of care in rehabilitation programs for cardiovascular risk reduction and the promotion of a healthy lifestyle. The systematic review describes the current state of knowledge of the effects of preoperative exercise training (prehabilitation) on perioperative clinical outcomes in patients undergoing cardiac and vascular interventions. METHODS: Studies were systematically searched within 14 databases from inception to October 2016. Only studies that assessed a preoperative exercise program in adult patients undergoing cardiac or vascular interventions with clinical or patient-centered endpoints were included in the review. Two independent reviewers selected studies for inclusion, extracted data, and assessed quality using Cochrane Collaboration's tool for RCTs11111111111111111 and ROBINS-I tool for nonrandomized studies. RESULTS: Nine studies met our inclusion criteria and were stratified for qualitative analyses by cardiac (n = 7) and vascular (n = 2) procedures. Prehabilitation was associated with decreased length of stay, reduced postoperative complications, improved objective physical functioning, and improved subjective quality of life (SF-36 physical and mental health domains) measures in patients undergoing cardiac and vascular procedures. Given the amount of heterogeneity that was present in the designs, populations, and comparators among the included studies, we were unable to statistically pool data across trials. CONCLUSIONS: Our qualitative findings suggest that prehabilitation may improve clinical outcomes, physical performance, and health-related quality-of-life measures in patients undergoing cardiac and vascular surgery procedures.

Validation of color Doppler sonography for evaluating relative displacement between the flexor tendon and subsynovial connective tissue.

OBJECTIVES: A common pathologic finding in carpal tunnel syndrome is fibrosis and thickening of the subsynovial connective tissue. This finding suggests an etiology of excessive shear forces, with relative longitudinal displacement between the flexor tendon and adjacent subsynovial connective tissue. The purpose of this study was to validate color Doppler sonography for measurement of tendon displacement over time. METHODS: Eight unmatched fresh frozen cadaver arms were used to evaluate color Doppler sonography for measurement of tendon displacement. The middle flexor digitorum superficialis tendon was moved through a physiologic excursion of 20 mm at 3 different tendon velocities (50, 100, and 150 mm/s). RESULTS: We found that color Doppler sonography provided accurate measurement of tendon displacement, with absolute errors of -0.05 mm (50 mm/s), -1.24 mm (100 mm/s), and -2.36 mm (150 mm/s) on average throughout the tendon excursion range. Evaluating relative displacement between the tendon and subsynovial connective tissue during finger flexion-extension movements also offered insight into the gliding mechanism of the subsynovial connective tissue. During flexion, we observed a curvilinear increase in relative displacement, with greater differential motion at the end range of displacement, likely due to the sequential stretch of the fibrils between successive layers of the subsynovial connective tissue. In extension, there was a linear return in relative displacement, suggesting a different unloading mechanism characterized by uniform relaxation of fibrils. CONCLUSIONS: We demonstrated the validity of color Doppler displacement for use in the evaluation of relative motion. Color Doppler sonography is useful in our understanding of the behavior of the subsynovial connective tissue during tendon excursion, which may elucidate the role of finger motion in the etiology of shear injury.

Cycle to cycle variability in a repetitive upper extremity task.

The purpose of this study was to examine the variability in muscle activity at rest and work during a repetitive task. A total of 20 participants performed a bimanual push task using three frequencies (4, 8, 16 pushes/min), three loads (1 kg, 2 kg, 4 kg) and two grip conditions (no grip, 30% maximum). The coefficient of variation (CoV) of muscle activity was determined for the anterior deltoid, biceps brachii, extensor digitorum and flexor digitorum superficialis. Faster push frequencies and heavier loads had lower work-rest ratio CoV and higher mean muscle activity (p < 0.01). Sixteen pushes per minute produced the lowest CoV for the anterior deltoid (p < 0.01), while the 1- kg load produced the lowest CoV for the extensor digitorum and flexor digitorum superficialis (p < 0.01). Changes were driven by the rest phase rather than by the work phase, except for grip decreasing forearm muscle CoV. These findings underscore the importance of variability at rest and indicate that low variability of muscle activity is associated with ergonomic risk factors. PRACTITIONER SUMMARY: Decreased motor variability has been associated with pain and injury. A cyclical push task, evaluated in terms of work and rest phases, found that greater workloads increased variability primarily due to changes in the rest phase. Muscle variability, especially for the rest phase, may provide insight into injury risk.

Reverse Total Shoulder Arthroplasty for Acute Proximal Humerus Fractures: Is Delay Associated With an Increased Rate of Reoperation?

OBJECTIVES: To compare reoperation rates of acute versus delayed reverse total shoulder arthroplasty (RTSA) following a period of nonoperative treatment for proximal humerus fractures (PHFs). We also aimed to identify an optimal time interval from PHF to RTSA before the risk of reoperation significantly increased. METHODS: . DESIGN: Database review. SETTING: Ontario, Canada. PATIENT SELECTION CRITERIA: Adults aged 50 years and older who sustained a PHF (OTA/AO 11A-C) between 2004 and 2019 were included. Exclusion criteria included polytrauma, open fractures, non-Ontario residents, invalid health insurance, and any operative treatment before RTSA. OUTCOME MEASURES AND COMPARISONS: The primary outcome measure was reoperation within 2 years following RTSA. A risk-adjusted, restricted cubic spline was used to model the probability of reoperation according to the time elapsed between PHF and RTSA to identify a time point at which the risk of reoperation significantly increased. A multivariate logistics regression was used to identify predictors. RESULTS: In total, 891 patients (685 acute, 206 delayed) underwent RTSA for PHF. The acute cohort had a significantly lower reoperation rate (3.9%) compared with the delayed cohort (8.3%) (P = 0.02). The odds of reoperation increased with a delay to RTSA greater than 28 days and continued to rise until 100 days after fracture. Patients who underwent RTSA 28 days after PHF were found to have a significantly higher odds of reoperation by 2 years (P = 0.03). CONCLUSIONS: Among patients undergoing RTSA for acute PHFs, a delay to surgery greater than 28 days is associated with a greater odds of reoperation and may be useful when counseling patients. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Predicting Pathological Fractures at Metastatic Humeral Lesions.

The humerus is the second most common site of metastatic disease involving long bones, yet it is still unclear which patients are at high risk for a fracture and may require prophylactic surgical fixation. The goal of this study was to assess the validity of the Mirels score to predict fractures of metastatic lesions in the humerus. Methods: We performed a retrospective electronic chart review of patients with humeral metastases at our institution (2005 to 2021), with 188 patients meeting the inclusion criteria. Sixty-one of the patients developed a fracture during follow-up. The metastatic humeral lesions were scored according to the Mirels rating system and additional radiographic criteria (cortical breach, location within the humerus, number of lesions). The predictive value of each Mirels score cutoff for fracture was assessed using sensitivity, specificity, area under the receiver operating characteristic curve (AUC), and multivariate logistic regression. Survivorship until fracture was analyzed for each Mirels score cutoff using Kaplan-Meier curves and the log-rank test. Significance was set at p < 0.01. Results: There were no significant differences in age, sex, side of the lesion, type of malignancy, and radiation dose between the groups with and without fracture (all p > 0.01). A Mirels score of ≥8 points had the best predictive profile, with sensitivity of 83.6%, specificity of 79.5%, and AUC of 0.82 (95% confidence interval [CI], 0.75 to 0.88, p < 0.01). A logistic regression model also demonstrated that a Mirels score of ≥8 (odds ratio = 5.8, 95% CI = 1.9 to 18.2, p < 0.01) and a cortical breach (odds ratio = 21.0, 95% CI = 5.7 to 77.2, p < 0.01) were significant predictors of pathological fracture. No other radiographic characteristics were found to be significant predictors of fracture. Conclusions: This study indicated that a Mirels score of ≥8 points had the best predictive profile for anticipating fractures at a metastasis in the humerus. This is in contrast to the traditional Mirels definition of an impending pathological fracture that is used for the lower extremity, a score of ≥9. Additionally, the presence of a cortical breach was a significant predictor of fracture risk. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Inadequate proximal screw fixation increases risk of failure following plate fixation of diaphyseal humerus fractures.

BACKGROUND: Operative treatment of humeral shaft fractures (AO/OTA 12) is being performed more frequently. Accordingly, it is important to understand the complications associated with plate fixation. This study analyzes risk factors associated with mechanical failure following plate fixation of humeral shaft fractures in order to further elucidate the mode and location of failure. METHODS: A retrospective review of 351 humeral shaft fractures was completed at a single level I trauma center. Eleven of eighty-five humeral shaft fractures had aseptic mechanical failure requiring revision (12.9%), following initial plate fixation. Fracture characteristics (AO type, comminution, location) and fracture fixation (plate type, multiplanar, number of screws proximal and distal to the fracture) were compared between aseptic mechanical failure and those without failure. A forward stepwise logistic regression analysis was performed to determine any significant predictors of aseptic mechanical failure. RESULTS: There was significant differences in fixation between the aseptic mechanical failure group and those without failure, specifically in the number of screws for proximal fixation (p = 0.008) and distal fixation (p = 0.040). In the aseptic mechanical failure group, patients tended to have less than < 8 cortices of proximal fixation (82%) and less than < 8 cortices of distal fixation (64%). Conversely, in patients without mechanical failure there was a tendency to have greater than > 8 cortices in both the proximal (62%) and distal fixation (70%). A forward stepwise logistic regression analysis found that less than < 8 cortices of proximal fixation was a significant predictor of aseptic failure, OR 7.96 (p = 0.011). We think this can be accounted for due to the variable bone quality, thinner cortices and multiple torsional forces in the proximal shaft that may warrant special consideration for fixation. CONCLUSION: The current dogma of humeral shaft fracture stabilization is to use a minimum of 3 screws proximal and distal to the fracture, however the current study demonstrates this is associated with higher rates of mechanical failure. In contrast, 4 bicortical screws or more of fixation on either side of the fracture had lower failure rates and may help to reduce the risk of mechanical failure. Level of Evidence Level III.

Intraoperative Ultrasound in Spine Decompression Surgery: A Systematic Review.

STUDY DESIGN: Systematic review. OBJECTIVE: The aim of this study was to review the current spine surgery literature to establish a definition for adequate spine decompression using intraoperative ultrasound (IOUS) imaging. SUMMARY OF BACKGROUND DATA: IOUS remains one of the few imaging modalities that allows spine surgeons to continuously monitor the spinal cord in real-time, while also allowing visualization of surrounding soft tissue anatomy during an operation. Although this has valuable applications for decompression surgery in spinal canal stenosis, it remains unclear how to best characterize adequacy of spinal decompression using IOUS. METHODS: We conducted a systematic search of multiple databases including: Medline, Embase, and Cochrane Central Register of Controlled Trials Strategy. Our search terms were spine, spinal cord diseases, decompression surgery, ultrasonogra-phy, and intraoperative period. We were interested in studies that used intraoperative use of ultrasound imaging in spinal decompression surgery for the cervical, thoracic, and lumbar spine. Study quality was evaluated using the Methodological Index for Non-Randomized Studies (MINORS). RESULTS: Our search strategy yielded 985 of potentially relevant publications, 776 underwent title and abstract screening, and 31 full-text articles were reviewed. We found IOUS to be useful in spine surgery for decompression of degenerative cases in all regions of the spine. The thoracic spine was unique for IOUS-guided decompression of fractures, and the lumbar spine for decompressing nerve roots. Although we did not identify a universal definition for adequate decompression, there was common description of decompression that qualitatively described the ventral aspect of the spinal cord being "free floating" within the cerebrospinal fluid. Other measurable definitions, such as spinal cord diameter or spinal cord pulsatility, were not good definitions given there was insufficient evidence and/or poor reliability. CONCLUSION: The systematic review examines the current literature on IOUS and spinal decompression surgery. We identified a common qualitative definition for adequate decompression involving a "free floating" spinal cord within the cerebrospinal fluid which indicates that the spinal cord is free from contact of the anterior elements.Level of Evidence: 1.

Lateral Meniscus Height and ACL Reconstruction Failure: A Nested Case-Control Study.

Previous work has shown that the morphology of the knee joint is associated with the risk of primary anterior cruciate ligament (ACL) injury. The objective of this study is to analyze the effect of the meniscal height, anteroposterior distance of the lateral tibial plateau, and other morphological features of the knee joint on risk of ACL reconstruction failure. A nested case-control study was conducted on patients who underwent an ACL reconstruction surgery during the period between 2008 and 2015. Cases were individuals who failed surgery during the study period. Controls were patients who underwent primary ACL reconstruction surgery successfully during the study period. They were matched by age (±2 years), gender, surgeon, and follow-up time (±1 year). A morphological analysis of the knees was then performed using the preoperative magnetic resonance imaging scans. The anteroposterior distance of the medial and lateral tibial plateaus was measured on the T2 axial cuts. The nonweightbearing maximum height of the posterior horn of both menisci was measured on the T1 sagittal scans. Measurements of the medial and lateral tibial slope and meniscal slope were then taken from the sagittal T1 scans passing through the center of the medial and lateral tibial plateau. A binary logistic regression analysis was done to calculate crude and adjusted odds ratios (ORs) estimates. Thirty-four cases who underwent ACL revision surgery were selected and were matched with 68 controls. Cases had a lower lateral meniscal height (6.39 ± 1.2 vs. 7.02 ± 0.9, p = 0.008, power = 84.4%). No differences were found between the two groups regarding the bone slope of the lateral compartment (6.19 ± 4.8 vs. 6.92 ± 5.8, p = 0.552), the lateral meniscal slope (-0.28 ± 5.8 vs. -1.03 ± 4.7, p = 0.509), and the anteroposterior distance of the lateral tibial plateau (37.1 ± 5.4 vs. 35.6 ± 4, p = 0.165). In addition, no differences were found in the medial meniscus height between cases and controls (5.58 ± 1.2 vs. 5.81 ± 1.2, respectively, p = 0.394). There were also no differences between cases and controls involving the medial bone slope, medial meniscal slope, or anterior posterior distance of the medial tibial plateau. Female patients had a higher medial (4.8 degrees ± 3.2 vs. 3.3 ± 4.1, p = 0.047) and lateral (8.1 degrees ± 5.1 vs. 5.6 degrees ± 5.6, p = 0.031) tibial bone slope, and a lower medial (5.3 mm ± 1.0 vs. 6.1 mm ± 1.2, p = 0.001) and lateral (6.6 ± 1.0 vs. 7.0 ± 1.2, p = 0.035) meniscus height, and medial (4.3 ± 0.4 vs. 4.8 ± 0.4, p =0.000) and lateral (3.3 ± 0.3 vs. 3.9 ± 0.4, p = 0.000) anteroposterior distance than males, respectively.The adjusted OR of suffering an ACL reconstruction failure compared to controls was 5.1 (95% confidence interval [CI]: 1.7-14.9, p = 0.003) for patients who had a lateral meniscus height under 6.0 mm. The adjusted OR of suffering an ACL reconstruction failure was 2.4 (95% CI: 1.0-7.7, p = 0.01) for patients who had an anteroposterior distance above 35.0 mm. Patients with a lateral meniscal height under 6.0 mm have a 5.1-fold risk of suffering an ACL reconstruction failure compared to individuals who have a lateral meniscal height above 6.0 mm. Patients with a higher anteroposterior distance of the lateral tibial plateau also have a higher risk of ACL reconstruction failure.

Scapular Notching Following Ipsilateral Traumatic Clavicle Fracture in Reverse Total Shoulder Arthroplasty: A Case Report.

INTRODUCTION: Reverse total shoulder arthroplasty (RTSA) procedures are becoming increasingly more common. While the main complications are known, the management of clavicle fractures in patients with an ipsilateral RTSA is not well described. There are three case studies that document clavicular stress fractures following RTSA with an atraumatic etiology, and to our knowledge, no studies have described a traumatic clavicular fracture following RTSA. CASE: We describe the case of a 75-year-old woman with a traumatic clavicle fracture five years after RTSA for rotator cuff tear arthropathy. With minimal pain and subjective symptoms initially, the patient wished to pursue non-operative treatment. However, she eventually developed a painful non-union and pseudoparalysis of the shoulder with serial radiographs demonstrating progressive superior scapular tilting and scapular notching. Subsequent open reduction internal fixation of her clavicle fracture significantly improved her pain and function. CONCLUSION: We report a traumatic clavicle fracture in the setting of RTSA that not only failed to heal but also resulted in scapular notching and shoulder pseudoparalysis that was improved with surgical stabilization of the fracture. It is possible that the setting of a semi-constrained RTSA, the resulting biomechanical imbalance may predispose to impaired fracture healing and non-union of the clavicle fracture.

Three-Dimensional (3D) Animation and Calculation for the Assessment of Engaging Hill-Sachs Lesions With Computed Tomography 3D Reconstruction.

PURPOSE: To dynamically assess for Hill-Sachs engagement with animated 3-dimensional (3D) shoulder models. METHODS: We created 3D shoulder models from reconstructed computed tomography (CT) images from a consecutive series of patients with recurrent anterior dislocation. They were divided into 2 groups based on the perceived Hill-Sachs severity. For our cohort of 14 patients with recurrent anterior dislocation, 4 patients had undergone osteoarticular allografting of Hill-Sachs lesions and 10 control patients had undergone CT scanning to quantify bone loss but no treatment for bony pathology. A biomechanical analysis was performed to rotate each 3D model using local coordinate systems to the classical vulnerable position of the shoulder (abduction = 90°, external rotation = 0-135°) and through a functional range. A Hill-Sachs lesion was considered "dynamically" engaging if the angle between the lesion's long axis and anterior glenoid was parallel. Results: In the vulnerable position of the shoulder, none of the Hill-Sachs lesions aligned with the anterior glenoid in any of our patients. However, in our simulated physiological shoulder range, all allograft patients and 70% of controls had positions producing alignment. CONCLUSIONS: The technique offers a visual representation of an engaging Hill-Sachs using 3D-animated reconstructions with open-source software and CT images. In our series of patients, we found multiple shoulder positions that align the Hill-Sachs and glenoid axes that do not necessarily meet the traditional definition of engagement. Identifying all shoulder positions at risk of "engaging," in a broader physiological range, may have critical implications toward selecting the appropriate surgical management of bony defects. LEVEL OF EVIDENCE: level III, case-control study.

A Quantifiable Risk Factor for ACL Injury: Applied Mathematics to Model the Posterolateral Tibial Plateau Surface Geometry.

BACKGROUND: The mechanism for traumatic ruptures of the native anterior cruciate ligament (ACL) is frequently a noncontact injury involving a valgus moment with internal rotation of the tibia. The abnormal rotation and translation of the lateral femoral condyle posteroinferiorly relative to the lateral tibial plateau is thought to be related to the geometry of the tibial plateau. PURPOSE/HYPOTHESIS: The purpose of the study was to mathematically model the posterior tibial plateau geometry in patients with ACL injuries and compare it with that of matched controls. The hypothesis was that increased convexity and steepness of the posterior aspect of the lateral plateau would subject knees to higher forces, leading to a potentially higher risk of ACL injury. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: We mathematically modeled the posterior curvature of the lateral tibial plateau in 64 patients with ACL injuries and 68 matched controls. Using sagittal magnetic resonance imaging scans of the knee, points on the articular cartilage of the posterolateral tibial plateau were selected and curve-fitted to a power function (y = a × xn ). For coefficient a and coefficient n, both variables modulated the shape of the curve, where a larger magnitude represented an increase in slope steepness. Groups were compared using a Mann-Whitney test and α < .05. RESULTS: There was a significant difference in surface geometry between the patients with ACL injuries and matched controls. The equation coefficients were significantly larger in the patients with ACL injuries: coefficient a (ACL injury, 0.9 vs control, 0.68; P < .0001) and coefficient n (ACL injury, 0.34 vs control, 0.30; P = .07). For coefficient a, there was a 78.9% sensitivity, 77.5% specificity, and odds ratio of 12.6 (95% CI, 5.5-29.0) for ACL injury using a cutoff coefficient a = .78. CONCLUSION: Patients with ACL injuries had a significantly greater posterolateral plateau slope. The steeper drop off may play a role in higher anterior translation forces, coupled with internal rotation torques on the knee in noncontact injury, which could increase ACL strain and predispose to ACL injury.

A Prediction Model for Primary Anterior Cruciate Ligament Injury Using Artificial Intelligence.

BACKGROUND: Supervised machine learning models in artificial intelligence (AI) have been increasingly used to predict different types of events. However, their use in orthopaedic surgery has been limited. HYPOTHESIS: It was hypothesized that supervised learning techniques could be used to build a mathematical model to predict primary anterior cruciate ligament (ACL) injuries using a set of morphological features of the knee. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Included were 50 adults who had undergone primary ACL reconstruction between 2008 and 2015. All patients were between 18 and 40 years of age at the time of surgery. Patients with a previous ACL injury, multiligament knee injury, previous ACL reconstruction, history of ACL revision surgery, complete meniscectomy, infection, missing data, and associated fracture were excluded. We also identified 50 sex-matched controls who had not sustained an ACL injury. For all participants, we used the preoperative magnetic resonance images to measure the anteroposterior lengths of the medial and lateral tibial plateaus as well as the lateral and medial bone slope (LBS and MBS), lateral and medial meniscal height (LMH and MMH), and lateral and medial meniscal slope (LMS and MMS). The AI predictor was created using Matlab R2019b. A Gaussian naïve Bayes model was selected to create the predictor. RESULTS: Patients in the ACL injury group had a significantly increased posterior LBS (7.0° ± 4.7° vs 3.9° ± 5.4°; P = .008) and LMS (-1.7° ± 4.8° vs -4.0° ± 4.2°; P = .002) and a lower MMH (5.5 ± 0.1 vs 6.1 ± 0.1 mm; P = .006) and LMH (6.9 ± 0.1 vs 7.6 ± 0.1 mm; P = .001). The AI model selected LBS and MBS as the best possible predictive combination, achieving 70% validation accuracy and 92% testing accuracy. CONCLUSION: A prediction model for primary ACL injury, created using machine learning techniques, achieved a >90% testing accuracy. Compared with patients who did not sustain an ACL injury, patients with torn ACLs had an increased posterior LBS and LMS and a lower MMH and LMH.

Clinical applications of ultrasonography in the shoulder for the Orthopedic Surgeon: A systematic review.

BACKGROUND: Ultrasound imaging offers a non-invasive method to visualize the anatomy and function of the musculoskeletal system. Despite its benefits and widespread adoption in medicine, ultrasonography is still not well utilized by orthopaedic surgeons. The purpose of this systematic review was to provide a better understanding of the diagnostic accuracy and clinical utility of ultrasound of the shoulder for orthopaedic surgeons. METHODS: We searched Medline, Embase, Web of Science, and Scopus databases. Our search terms included orthopedic, orthopedic surgery, ultrasonography, and shoulder. Inclusion criteria consisted of studies that used bedside ultrasound for the diagnosis and therapy of patients with common clinical entities of the shoulder presenting to orthopedic clinics, to demonstrate the utility for orthopedic surgeons. We reported sensitivity, specificity, positive predictive value, negative predictive value. Studies were excluded if they used non-diagnostic ultrasound modalities (e.g. shock wave therapy, shear wave elastography, Doppler flowmetry, speckle tracking shear strain, vibro-acoustography). RESULTS: Our search strategy yielded 771 of potentially relevant publications, 41 studies were retrieved for full text screening, and 24 were included in this systematic review. We found that ultrasound used in orthopedic clinics has good sensitivity and high specificity for the assessment of partial and full rotator cuff tears of the shoulder, including post-operative cuff repairs. There was some evidence that it may also be useful for the diagnosis of subacromial-subdeltoid bursitis, AC joint arthropathy, and labral tears; however further investigations are still required. Ultrasound improves that accuracy of injections into spaces of the shoulder (subacromial bursa, acromioclavicular joint, glenohumeral joints, and the long head of biceps tendon sheath) compared to landmark guided injections, that can be helpful for diagnostic purposes, but do not improve long term clinical outcomes. DISCUSSION: We reviewed the literature for orthopaedic surgeons and show that ultrasound of the shoulder can be a useful diagnostic tool for orthopedic surgeons in outpatient clinics. We found no difference in sensitivity or specificity when ultrasound was performed at bedside by orthopedic surgeons or by radiologists for patients referred to orthopedic clinic.

Distal Biceps Repair With Flexible Instrumentation and Risk of Posterior Interosseous Nerve Injury: A Cadaveric Analysis.

BACKGROUND: Current repair techniques using cortical button fixation cannot achieve anatomic reconstruction of the distal biceps when performed through a single-incision anterior approach. We recently introduced a single-incision technique that uses flexible guide pins and flexible reamers to allow for an insertion point on the tuberosity that more closely approximates the anatomic footprint of the distal biceps. PURPOSE: To investigate the safety of this technique with regard to nerve injury by comparing the guide pin position relative to the posterior interosseous nerve in 16 cadaveric elbows through use of a flexible versus rigid reamer. STUDY DESIGN: Descriptive laboratory study. METHODS: A standard single-incision anterior approach was performed in all cadaveric specimens, and the biceps tendon was dissected off the tuberosity. In 8 specimens, a traditional straight guide pin was used with a cortical button repair inserted through the bicipital tuberosity as close to the anatomic tendon footprint as possible. In the remaining 8 specimens, a curved guide was used to insert a flexible guide wire through the tuberosity within the native footprint. Dissection was carried out to measure the distance from the exit point of the guide pin to the posterior interosseous nerve. The 2 groups were compared by use of nonparametric Wilcoxon rank-sum test (significance threshold, P < .05). RESULTS: The mean distance of the guide wire to the posterior interosseous nerve was 11.6 mm (SD, 3.4 mm; range, 6.5-16.9 mm) in the standard rigid instrument group compared with 8.6 mm (SD, 4.2 mm; range, 1.0-13.9 mm) in the flexible instrumentation group; the difference between groups was not statistically different (P = .19; 95% CI, -1.1 to 7.1). CONCLUSION: Based on our cadaveric testing, the use of flexible instrumentation in a single-incision repair of the distal biceps presents with no significant difference in risk of damage to the posterior interosseous nerve compared with standard rigid instruments. In view of the relatively small number of specimens, however, some caution should be observed when applying these results clinically. CLINICAL RELEVANCE: As contemporary techniques in sports medicine strive to re-create each patient's native anatomic characteristics, the use of flexible instruments allows for a more anatomic repair of the distal biceps, and our study demonstrates that it is a safe option. The next step is to evaluate its safety in vivo.

Anatomic Single-Incision Repair of Distal Biceps Tendon Ruptures Using Flexible Reamers.

Distal biceps tendon ruptures are treated operatively in active healthy individuals. Treatment consists of either single- or double-incision techniques, each with its own set of advantages and complications. The double incision was traditionally preferred for a more anatomic reattachment of the distal biceps tendon, but there has been renewed interest in the single-incision anterior approach given its lower risk for heterotopic ossification. However, current single-incision techniques cannot achieve anatomic reconstruction of the distal biceps because of a restricted operational angle with standard rigid instruments. The purpose of this study was to introduce a single-incision technique using flexible instrumentation, flexible guide pins, and flexible reamers that allows for an insertion point that better approximates the anatomic footprint of the distal biceps on the tuberosity. This offers the theoretical advantage of restoring forearm supination mechanics, while still maintaining the benefits of a single limited anterior exposure.

Effects of Wrist Posture and Fingertip Force on Median Nerve Blood Flow Velocity.

Purpose. The purpose of this study was to assess nerve hypervascularization using high resolution ultrasonography to determine the effects of wrist posture and fingertip force on median nerve blood flow at the wrist in healthy participants and those experiencing carpal tunnel syndrome (CTS) symptoms. Methods. The median nerves of nine healthy participants and nine participants experiencing symptoms of CTS were evaluated using optimized ultrasonography in five wrist postures with and without a middle digit fingertip press (0, 6 N). Results. Both wrist posture and fingertip force had significant main effects on mean peak blood flow velocity. Blood flow velocity with a neutral wrist (2.87 cm/s) was significantly lower than flexed 30° (3.37 cm/s), flexed 15° (3.27 cm/s), and extended 30° (3.29 cm/s). Similarly, median nerve blood flow velocity was lower without force (2.81 cm/s) than with force (3.56 cm/s). A significant difference was not found between groups. Discussion. Vascular changes associated with CTS may be acutely induced by nonneutral wrist postures and fingertip force. This study represents an early evaluation of intraneural blood flow as a measure of nerve hypervascularization in response to occupational risk factors and advances our understanding of the vascular phenomena associated with peripheral nerve compression.

Reduced common carotid artery longitudinal wall motion and intramural shear strain in individuals with elevated cardiovascular disease risk using speckle tracking.

Longitudinal motion of the intima-media and adventitia layers of the common carotid artery (CCA) wall were assessed with ultrasound speckle tracking in seven individuals with spinal cord injury (SCI), who are considered at increased risk of cardiovascular disease, and in seven able-bodied participants. CCA longitudinal wall displacement and intramural shear strain were compared to traditional markers of arterial health, including CCA stiffness and intima-media thickness (IMT). For each cardiac cycle, longitudinal CCA wall motion was characterized by bidirectional movement patterns containing motion retrograde to blood flow during systole, followed by antegrade motion during diastole. Relative displacement of the intima-media versus the adventitia was used to calculate longitudinal intramural shear strain and provided insight to local arterial wall properties. The retrograde intramural shear strain was smaller in individuals with SCI by 60·2% (P<0·05) compared to able-bodied participants, showing smaller peak displacements in both the intima-media (P<0·05) and adventitia (P<0·05). In the antegrade direction, there were no group differences in either longitudinal displacements or shear strain. The group differences observed in the retrograde wall motion phase were greater than those observed for CCA stiffness or IMT and were found to be independent of both indices, indicating indices of the retrograde phase intramural shear strain may be a novel and sensitive marker of vascular health. Our findings demonstrate that assessment of longitudinal arterial wall shear strain may provide valuable insight into vascular structure and function and may hold potential for the early detection of cardiovascular disease.

Relative displacement of the tendon and subsynovial connective tissue using ultrasound captures different phenomena than mechanical tendon shear.

The most common finding in carpal tunnel syndrome is fibrosis and thickening of the subsynovial connective tissue (SSCT). While the SSCT mediates tendon gliding in the carpal tunnel, this histopathology suggests excessive shear forces are involved in injury development. Ultrasound is often used to quantify relative motion between the finger flexor tendons and SSCT as an indirect measure of "shear-strain"; however, the underlying mechanical implications of using ultrasound are not well understood. The middle flexor digitorum superficialis (FDS) tendon of 8 cadavers was moved in a combination of 2 wrist postures (neutral, flexed), 3 velocities (5, 10, 15cm/s), and 3 forces (10, 20, 30N) to assess ultrasound-based FDS-SSCT relative displacement while simultaneously quantifying tendon frictional work in the carpal tunnel. We found independent velocity effects for both constructs (relative displacement, ηp2=0.862, p<0.05; frictional work, ηp2=0.937, p<0.05), indicating ultrasound captured viscous gliding resistance owing to the gel-like inter-fibrillar matrix of the SSCT. FDS-SSCT relative displacement also increased independently in a flexed wrist posture (p=0.010) and with greater tendon force (p=0.036), likely representing strain dependant changes with tendon position. Alternatively, we found a significant posture×force interaction on tendon frictional work (p<0.01), due to, in part, greater surface friction against the transverse carpal ligament with a flexed wrist and high force. While ultrasound provided a different interpretation compared to direct measurement of mechanical shear, FDS-SSCT relative displacement successfully localized viscoelastic shear-strain, which may help elucidate the role of hand motion in SSCT pathology and CTS.