Accuracy of the Lesser Trochanter Profile as a Marker of Femoral Rotation: Computed Tomography-Based Study of 1,722 Femora.

BACKGROUND: The lesser trochanter (LT) profile is an often-used marker for proximal femoral rotation, particularly during the operative fixation of femoral fractures. Previous studies have come to conflicting conclusions about its reliability for this purpose. METHODS: The SOMA (Stryker Orthopaedic Modeling and Analytics) database (Stryker) was used to identify 1,722 computed tomographic (CT) scans of whole femora. Each femur was taken through an 80° rotational arc in 2.5° increments, and the LT profile was constructed for each position. These 56,826 LT profile measurements were then correlated with the femoral rotation. RESULTS: Across the arc of motion studied, the LT correlated weakly with proximal femoral rotation (R 2 = 0.32). There was a 35° arc, between 10° and 45° relative external rotation of the proximal femur, within which the LT profile only changed by 1 mm. The mean overall femoral anteversion was 21.2°, and women tended to have more femoral anteversion (23.9°) than men (19.2°). On average, men had a 1.6-mm more prominent LT than women. Side-to-side differences in femoral anteversion as well as LT position and size were not significant or were clinically unimportant. CONCLUSIONS: A large-scale, CT-based study shows that the LT profile is a less reliable marker of proximal femoral rotation than previously thought. This is true particularly if there is relative external rotation of the proximal femur, where the proximal femur can undergo up to 35° of rotation before 1 mm of change in the LT profile occurs. Care must be taken to check other markers of rotation such as by clinical examination during fixation of femoral fractures and not rely solely on the LT profile. CLINICAL RELEVANCE: In the largest study of its kind, this CT-based study of 56,826 LT profile measurements found that when the proximal femur is externally rotated, the LT profile becomes an unreliable marker of rotation, which can lead to excessive internal rotation of the distal fracture fragment. The LT profile should be used with caution, and confirmation of rotation by other means is recommended.

Thermal Damage in Orthopaedics.

There are numerous potential sources of thermal damage encountered in orthopaedic surgery. An understanding of the preclinical mechanisms of thermal damage in tissues is necessary to minimize iatrogenic injuries and use these mechanisms therapeutically. Heat generation is a phenomenon that can be used to a surgeon's benefit, most commonly for hemostasis and local control of tumors. It is simultaneously one of the most dangerous by-products of orthopaedic techniques as a result of burring, drilling, cementation, and electrocautery and can severely damage tissues if used improperly. Similarly, cooling can be used to a surgeon's advantage in some orthopaedic subspecialties, but the potential for harm to tissues is also great. Understanding the potential of a given technique to rapidly alter local temperature-and the range of temperatures tolerated by a given tissue-is imperative to harness the power of heat and cold. In all subspecialties of orthopaedic surgery, thermal damage is a relevant topic that represents a direct connection between preclinical and clinical practice.

Digital Epidemiological Approaches in HIV Research: a Scoping Methodological Review.

PURPOSE OF REVIEW: The purpose of this scoping review was to summarize literature regarding the use of user-generated digital data collected for non-epidemiological purposes in human immunodeficiency virus (HIV) research. RECENT FINDINGS: Thirty-nine papers were included in the final review. Four types of digital data were used: social media data, web search queries, mobile phone data, and data from global positioning system (GPS) devices. With these data, four HIV epidemiological objectives were pursued, including disease surveillance, behavioral surveillance, assessment of public attention to HIV, and characterization of risk contexts. Approximately one-third used machine learning for classification, prediction, or topic modeling. Less than a quarter discussed the ethics of using user-generated data for epidemiological purposes. User-generated digital data can be used to monitor, predict, and contextualize HIV risk and can help disrupt trajectories of risk closer to onset. However, more attention needs to be paid to digital ethics and the direction of the field in a post-Application Programming Interface (API) world.

Improved functional status in patients undergoing cement and rebar reconstruction with total hip arthroplasty for uncontained metastatic tumors of the acetabulum.

BACKGROUND AND OBJECTIVE: Metastatic cancer of the acetabulum can produce marked pain and disability for patients. Several reconstruction techniques for such lesions have been described, with variable outcomes. The purpose of this study was to determine functional outcomes and complication rate for patients undergoing cement rebar reconstruction using posterior column screws with total hip arthroplasty for large, uncontained lesions of the acetabulum. METHODS: Twenty-two consecutive patients who underwent cement rebar reconstruction with posterior column screws and total hip arthroplasty for metastatic tumors of the acetabulum between 2014 and 2017 were identified. All cases were reviewed for patient demographics, surgical parameters, implant survival, complications, and functional status following these procedures. RESULTS: There was a significant increase in the proportion of patients able to ambulate post-surgery (95.5%) compared with presurgery (22.7%) (p < 0.001). Mean musculoskeletal tumor society score postoperatively was 17.9 (60%). Average operative time was 174 min and average estimated blood loss was 689 mL. Seven patients required an intraoperative or postoperative blood transfusion. Three patients had postoperative complications (14%), two of whom required revision (9%). CONCLUSION: Reconstruction using cement rebar with posterior column screws and total hip arthroplasty is a safe, reproducible approach that may greatly improve functional outcomes with a low rate of intraoperative or postoperative complications.

Effect of Insurance Status on Mortality in Adults With Sarcoma of the Extremities and Pelvis: A SEER-Medicare Study.

INTRODUCTION: Previous studies have highlighted the association between insurance status and poor outcomes after surgical treatment of sarcomas in the United States.1-3 It is unclear how much of this disparity is mediated by confounding factors such as medical comorbidities and socioeconomic status and how much can be explained by barriers to care caused by insurance status. METHODS: Surveillance, Epidemiology, and End Results-Medicare linkage data were procured for 7,056 patients undergoing treatment for bone and soft-tissue sarcomas in the extremities diagnosed between 2006 and 2013. A Cox proportional hazards model was used to assess the relative contributions of insurance status, medical comorbidities, tumor factors, treatment characteristics, and other demographic factors (race, household income, education level, and urban/rural status) to overall survival. RESULTS: Patients with Medicaid insurance had a 28% higher mortality rate over the period studied, compared with patients with private insurance (hazard ratio, 1.28; 95% confidence interval, 1.03 to 1.60, P = 0.026), even when accounting for all other confounding variables. The 28% higher mortality rate associated with having Medicaid insurance was equivalent to being approximately 10 years older at the time of diagnosis or having a Charlson comorbidity index of 4 rather than zero (hazard ratio, 1.27). DISCUSSION: Insurance status is an independent predictor of mortality from sarcoma, with 28% higher mortality in those with pre-expansion Medicaid.4,5 This association between insurance status and higher mortality held true even when accounting for numerous other confounding factors. Additional study is necessary into the mechanism for this healthcare disparity for the uninsured and underinsured, as well as strategies to resolve this inequality.

Reference Axes for Tibial Component Rotation in Total Knee Arthroplasty: Computed Tomography-Based Study of 1,351 Tibiae.

BACKGROUND: Many anatomic landmarks have been described for setting tibial component rotation intraoperatively. There is no consensus as to which axis is best for reducing outliers and preventing malrotation. METHODS: The SOMA (Stryker Orthopaedic Modeling and Analytics) database (Stryker) was used to identify 1,351 computed tomography (CT) scans of the entire tibia. Several reference axes for the tibia (including the Mayo axis, Akagi line, Insall line, anterior condylar axis [ACA], posterior condylar axis [PCA], lateral tibial cortex [LTC], Cobb axis, tibial crest line [TCL], and transmalleolar axis [TMA]) were constructed according to published guidelines. The Berger method served as the reference standard. RESULTS: The Mayo method (involving a line connecting the medial and middle one-thirds of the tibial tubercle and the geometric center of the tibia) and the Insall line (involving a line connecting the posterior cruciate ligament [PCL] insertion and the intersection of the middle and medial one-thirds of the tibial tubercle) both had low variability relative to the Berger method (7.8° ± 1.0° and 5.1° ± 2.2°, respectively) and a low likelihood of internal rotation errors (0.7% and 1.8%, respectively). No clinically significant gender-based differences were found (<0.7° for all). The same was true for ethnicity, with the exception of consistently greater tibial intorsion in Asian versus Caucasian individuals (mean difference in TCL position, +4.5° intorsion for Asian individuals; p < 0.001). CONCLUSIONS: This CT-based study of 1,351 tibiae (which we believe to be the largest study of its kind) showed that the Mayo and Insall methods (both of which reference the medial and middle one-thirds of the tibial tubercle) offer an ideal balance of accuracy, low variability, and a reduced likelihood of internal rotation errors. Setting rotation on the basis of distal landmarks (tibial shaft and beyond) may predispose surgeons to substantial malrotation errors, especially given the differences in tibial torsion found between ethnic groups in this study. LEVEL OF EVIDENCE: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Complex Reconstruction for Acetabular Pathologic Fracture in Unusual Chondroblastoma With Aneurysmal Bone Cyst.

Treating bone loss with complex arthroplasty poses a significant challenge for the arthroplasty surgeon. When considering a reconstructive case after pathologic fracture and oncologic excision, a multidisciplinary approach with reliance on arthroplasty principles is critical. An 18-year-old patient presented with a complex acetabular pathologic fracture through a chondroblastoma with a secondary aneurysmal bone cyst. An outside institution performed a biopsy and placed a hip-spanning external fixator. Multidisciplinary planning led to tumor excision, complex acetabular arthroplasty reconstruction including structural bone grafting, and internal fixation. At the third year of follow-up, there was no evidence of mechanical loosening of the hip arthroplasty, reoperation, or tumor recurrence. The structural graft was completely osseointegrated, confirmed by a computed tomography scan obtained at 2 years postoperatively. This report demonstrates an unusual location of chondroblastoma, presenting with acetabular fracture definitively treated with complex multidisciplinary reconstruction leading to an excellent outcome in a young patient.

Where horizontal and vertical surveillances meet: Sense-making of US COVID-19 contact-tracing apps during a health crisis.

Analyzing user reviews of seven US digital contact-tracing apps for COVID-19, this article unpacks how the new form of surveillance technology is understood and experienced by individuals during a global health crisis. The findings suggest that the app users felt empowered via self-tracking capacity and expressed community-level care and concerns, including those regarding the marginalized. At the same time, the users were raising doubts over technical effectiveness, navigating varying levels of voluntary choice available, and negotiating privacy concerns depending on the (dis)trust they held of institutional entities behind the governance of the apps. We argue that it is critical to investigate how surveillance technologies are situated across horizontal and vertical relationships in people's everyday lives to fully understand the individual and societal acceptance and/or refusal of the very systems during crises.

Effect of Resident and Fellow Involvement on Outcomes of Sarcoma Surgery: A NSQIP Database Cross-Sectional Study.

BACKGROUND: The complexity of sarcoma surgery often justifies surgical assistants of higher levels of academic training: senior residents, fellows, or co-surgeons. The association between the level of training of assistants and outcomes of these procedures has yet to be studied. METHODS: The Current Procedural Terminology (CPT) codes comprising the "core" procedures for musculoskeletal oncology fellowships were gathered. After CPTs primarily capturing nononcologic procedures were excluded, the National Surgical Quality Improvement Program (NSQIP) database was used to find procedures with these CPTs. The severity of complications was assessed using the Severity Weighting of Postoperative Adverse Events in Orthopedic Surgery (SWORD) score. Resident/fellow presence was analyzed both as a binary variable and stratified by level of training. RESULTS: In 159 cases meeting inclusion criteria, higher-level assistants were associated with increased rate of any complication (p=0.006) and greater need for transfusion (p=0.001) but also tended to be used in cases of longer duration (p=0.001) and with higher total work relative value units (wRVUs) (p=0.001). Multivariate analysis showed that while higher-wRVU procedures persisted as an independent predictor of increased complications (OR 1.028 per RVU unit, p=0.002), neither the presence nor level of training of assistants had an independent effect on complication rates. Other independent predictors of 30-day complications were treatment comorbidity (OR 3.433, p=0.010) and lower extremity location of the tumor (OR 4.393, p=0.006). Severity of complications did not differ between any of the groups on either univariate or multivariate analysis. CONCLUSIONS: Trainees of higher levels of academic training tend to be present for longer, higher-complexity musculoskeletal oncology cases, but the overall severity of complications from these do not significantly differ from lower-risk cases without trainees. Orthopedic oncologists may reassure patients that the presence of trainees and co-surgeons is not only safe but it may also help reduce the severity of complications in more complex procedures.

Statistical Fragility of Surgical Clinical Trials in Orthopaedic Trauma.

INTRODUCTION: The Fragility Index (FI) and the Fragility Quotient (FQ) are powerful statistical tools that can aid clinicians in assessing clinical trial results. The purpose of this study was to use the FI and FQ to evaluate the statistical robustness of widely cited surgical clinical trials in orthopaedic trauma. METHODS: We performed a PubMed search for orthopaedic trauma clinical trials in high-impact orthopaedics-focused journals and calculated the FI and FQ for all identified dichotomous, categorical outcomes. RESULTS: We identified 128 studies with 545 outcomes. The median FI was 5, and the median FQ was 0.0482. For statistically significant and not statistically significant outcomes, the median FIs were 3 and 5, and the mean FQs were 0.0323 and 0.0526, respectively. The FI was greater than the number of patients lost to follow-up in most outcomes. CONCLUSIONS: The orthopaedic trauma literature is of equal or higher quality than research in other orthopaedic subspecialties, suggesting that other orthopaedic subspecialties may benefit from modeling their clinical trials after those in orthopaedic trauma.

A Current Concepts Review of Clavicle Injuries in Ice Hockey From Sternoclavicular to Acromioclavicular Joint.

Clavicle injuries are common in ice hockey, and a number of high-profile fractures and dislocations have occurred in elite hockey players in recent years. Acromioclavicular joint injuries, clavicle fractures, and sternoclavicular joint injuries are some of the most frequent hockey-related injuries treated by orthopaedic surgeons, and familiarity with the management of these injuries and sport-specific considerations for treatment and recovery are critical. Injuries involving the clavicle can sometimes be life-threatening, and subtle findings on physical examination and radiographic studies can have profound implications for treatment. The recent literature pertinent to the diagnosis and treatment of clavicle-related injuries in ice hockey players was reviewed and compiled into a clinical commentary. For ice hockey players, the upper extremity was traditionally considered a relatively well-protected area. However, given the evolution of the game and its protective equipment, the upper extremity now accounts for the majority of youth ice hockey injuries, of which clavicle injuries comprise a significant proportion. Acromioclavicular joint injuries are the most common injury in this population, followed closely by clavicle fractures. Sternoclavicular joint injuries are rare but can be associated with serious complications. The treatment of these injuries often differs between athletes and the general population, and surgical indications continue to evolve in both groups. Although the evidence regarding clavicle injuries is ever-increasing and the treatment of these injuries remains controversial, clavicle injuries are increasingly common in ice hockey players. Rule and equipment changes, most notably the increased use of flexible boards and glass, have been shown to significantly decrease the risk of clavicle injuries. We also recommend compulsory use of shoulder pads, even at a recreational level, as well as continued enforcement and evolution of rules aimed at reducing the rate of clavicle injuries. Future research should focus on equipment design changes directed toward clavicle injury prevention, standardized return-to-play protocols, and studies weighing the risks and benefits of nonoperative management of controversial injuries, such as type III acromioclavicular joint dislocations and diaphyseal clavicle fractures.

Statistical Fragility of Surgical and Procedural Clinical Trials in Orthopaedic Oncology.

The fragility index (FI) is a powerful tool that can be used to assess the statistical strength of a study outcome. This metric is defined as the number of patients who would need to have an alternative outcome to convert a clinical trial result from statistically significant to not statistically significant, or vice versa. No studies to date have used the FI to evaluate surgical and procedural clinical trials in the orthopaedic oncology literature. The primary purpose of this study was to use the FI to evaluate the statistical strength of widely cited surgical and procedural clinical trials in orthopaedic oncology. Methods: We performed a PubMed search for orthopaedic oncology clinical trials in high impact orthopaedics-focused, oncology-focused, and general medicine journals. For each study included in this analysis, we calculated the FI for all identified dichotomous, categorical outcomes. Results: We identified 23 studies with 48 outcomes. Twelve of these outcomes were statistically significant, with a median FI of two. Nine studies addressed the number of patients lost to follow up, and the FI was less than the number of patients lost to follow up for most outcomes (60%) in these studies. Conclusions: The orthopaedic oncology literature has substantial statistical fragility, likely explained by a high number of patients lost to follow up and small sample sizes. More multicenter, cooperative studies are necessary to increases the robustness of clinical research in orthopaedic oncology.

Evaluation and Management of Hand, Wrist and Elbow Injuries in Ice Hockey.

Ice hockey continues to be a popular, fast-paced, contact sport enjoyed internationally. Due to the physicality of the game, players are at a higher risk of injury. In the 2010 Winter Olympics, men's ice hockey had the highest injury rate compared to any other sport. In this review, we present a comprehensive analysis of evaluation and management strategies of common hand, wrist, and elbow injuries in ice hockey players. Future reseach focusing on the incidence and outcomes of these hand, wrist and elbow injuries in ice hockey players is warranted.

Risk Factors for Surgical Site Infection in Orthopaedic Oncology.

INTRODUCTION: Surgical site infections (SSIs) are common complications after surgeries involving musculoskeletal tumors, but we know little about SSI risk factors unique to orthopaedic oncology. A greater understanding of these factors will help risk-stratify patients and guide surgical decision-making. METHODS: A retrospective review at a single-institution identified 757 procedures done on 624 over 6 years. The patients had a preoperative diagnosis of a malignant or potentially malignant neoplasm of the bone or soft tissues. Patient-specific and procedure-specific variables and diagnosis of SSI were recorded for each case. Data were analyzed through univariate analysis and multiple logistic regression. RESULTS: On univariate analysis, significant patient-specific risk factors for SSI included malignancy (P < 0.001), smoking history (P = 0.041), and American Society of Anesthesiologists Score (P = 0.002). Significant procedure-specific risk factors for SSI on univariate analysis included surgery time (P < 0.001), estimated blood loss (P < 0.001), blood transfusion volume (P < 0.001), neoadjuvant chemotherapy (P < 0.001), neoadjuvant radiation therapy (P < 0.001), inpatient surgery (P < 0.001), and number of previous surgeries within the study period (P < 0.001). The two factors that independently predicted risk of SSI when controlling for all other variables in a multiple logistic regression were whether the surgery was done on an inpatient basis (P = 0.005) and the number of previous surgeries done on the same site (P = 0.001). CONCLUSIONS: We found a number of risk factors that correlate markedly with SSI after orthopaedic oncology surgery. The surgeon can use these risk factors to aid in surgical decision-making.

Is There an Association Between Insurance Status and Survival and Treatment of Primary Bone and Extremity Soft-tissue Sarcomas? A SEER Database Study.

BACKGROUND: Several recently published population-based studies have highlighted the association between insurance status and survival in patients with various cancers such as breast, head and neck, testicular, and lymphoma [22, 24, 38, 41]. Generally, these studies demonstrate that uninsured patients or those with Medicaid insurance had poorer survival than did those who had non-Medicaid insurance. However, this discrepancy has not been studied in patients with primary bone and extremity soft-tissue sarcomas, a unique oncological population that typically presents late in the disease course and often requires referral and complex treatment at tertiary care centers-issues that health insurance coverage disparities could aggravate. QUESTIONS/PURPOSES: (1) What is the relationship between insurance status and cause-specific mortality? (2) What is the relationship between insurance status and the prevalence of distant metastases? (3) What is the relationship between insurance status and the proportion of limb salvage surgery versus amputation? METHODS: The Surveillance, Epidemiology, and End Results database (SEER) was used to identify a total of 12,008 patients: 4257 patients with primary bone sarcomas and 7751 patients with extremity soft-tissue sarcomas, who were diagnosed and treated between 2007 and 2014. Patients were categorized into one of three insurance groups: insured with non-Medicaid insurance, insured with Medicaid, and uninsured. Patients without information available regarding insurance status were excluded (2.7% [113 patients] with primary bone sarcomas and 3.1% [243 patients] with extremity soft-tissue sarcomas.) The association between insurance status and survival was assessed using a Cox proportional hazards regression analysis adjusted for patient age, sex, race, ethnicity, extent of disease (lymph node and metastatic involvement), tumor grade, tumor size, histology, and primary tumor site. RESULTS: Patients with primary bone sarcomas with Medicaid insurance had reduced disease-specific survival than did patients with non-Medicaid insurance (hazard ratio 1.3 [95% confidence interval 1.1 to 1.6]; p = 0.003). Patients with extremity soft-tissue sarcomas with Medicaid insurance also had reduced disease-specific survival compared with those with non-Medicaid insurance (HR 1.2 [95% CI 1.0 to 1.5]; p = 0.019). Patients with primary bone sarcomas (relative risk 1.8 [95% CI 1.3 to 2.4]; p < 0.001) and extremity soft-tissue sarcomas (RR 2.4 [95% CI 1.9 to 3.1]; p < 0.001) who had Medicaid insurance were more likely to have distant metastases at the time of diagnosis than those with non-Medicaid insurance. Patients with primary bone sarcomas (RR 1.8 [95% CI 1.4 to 2.1]; p < 0.001), and extremity soft-tissue sarcomas (RR 2.4 [95% CI 1.9 to 3.0]; p < 0.001) that had Medicaid insurance were more likely to undergo amputation than patients with non-Medicaid insurance. Patients with primary bone and extremity soft-tissue sarcomas who were uninsured were not more likely to have distant metastases at the time of diagnosis and did not have a higher proportion of amputation surgery as compared with patients with non-Medicaid insurance. However, uninsured patients with extremity soft-tissue sarcomas still displayed reduction in disease-specific survival (HR 1.6 [95% CI 1.2 to 2.1]; p = 0.001). CONCLUSIONS: Disparities manifested by differences in insurance status were correlated with an increased risk of metastasis at the time of diagnosis, reduced likelihood of treatment with limb salvage procedures, and reduced disease-specific survival in patients with primary bone or extremity soft-tissue sarcomas. Although several potentially confounding variables were controlled for, unmeasured confounding played a role in these results. Future studies should seek to identify what factors drive the finding that substandard insurance status is associated with poorer survival after a cancer diagnosis. Candidate variables might include medical comorbidities, treatment delays, time to first presentation to medical care and time to diagnosis, type of treatment received, distance travelled to treatments and transportation barriers, out-of-pocket payment burden, as well as educational and literacy status. These variables are almost certainly associated with socioeconomic deprivation in a vulnerable patient population, and once identified, treatment can become targeted to address these systemic inequities. LEVEL OF EVIDENCE: Level III, therapeutic study.

Sarcoma Surveillance: A Review of Current Evidence and Guidelines.

After initial treatment of sarcoma, disease progression may occur in the form of local recurrence, pulmonary metastases, or extrapulmonary metastases. As such, surveillance is an important aspect of management, but no universally accepted practice standards are found. In the absence of strong evidence, and to allow for individualized care, existing guidelines contain flexibility in terms of both the frequency and modality of surveillance. In general, they agree that follow-up should be more intense in the early years after treatment, especially for high-grade sarcomas, and continue for at least 10 years. For local recurrence, data suggest that physical examination is usually sufficient for monitoring; in addition, some guidelines endorse imaging routinely, whereas others only as clinically indicated. For pulmonary metastasis, either radiograph or CT is recommended, with the latter having theoretical advantages but no proven survival benefit to date. Extrapulmonary metastases are rare in most sarcoma types, so the literature only supports extrapulmonary surveillance for certain diagnoses. This topic is complicated by the diversity of sarcomas, the limited evidence, and the indefinite, often conflicting recommendations; therefore, it is critical for providers to understand the existing research and guidelines to determine optimal surveillance strategies for their patients.

Accuracy of Reference Axes for Femoral Component Rotation in Total Knee Arthroplasty: Computed Tomography-Based Study of 2,128 Femora.

BACKGROUND: Many reference axes are used to evaluate rotation of the femoral component during total knee arthroplasty, including the Whiteside line, surgical transepicondylar axis (sTEA), anatomical transepicondylar axis (aTEA), posterior condylar axis externally rotated 3° (PCA+3°ER), sulcus line, and femoral transverse axis (FTA). There is no consensus about which of these axes is most accurate. METHODS: The Stryker Orthopaedic Modeling and Analytics (SOMA) database was used to identify 2,128 entire-femur computed tomography (CT) scans. The Whiteside line, aTEA, PCA+3°ER, sulcus line, and FTA were constructed according to published guidelines. Every axis was compared with the sTEA, which is widely regarded as the gold standard reference axis for rotation of the distal part of the femur but has low intraobserver and interobserver reliability intraoperatively. RESULTS: The PCA+3°ER differed from the sTEA by a mean (and standard deviation) of 0.60° ± 1.64°; it was the most accurate but also had the highest degree of intersubject variability. The mean PCA-sTEA angle was 2.40°, close to the accepted "rule of thumb" of 3°. This value was significantly higher in women (2.64° ± 1.74°) than in men (2.18° ± 1.52°; p < 0.001). The Whiteside line differed from the sTEA by a mean of 1.90° ± 1.38°, and the sulcus line differed from the sTEA by a mean of 1.94° ± 1.49°; neither of these values varied significantly with sex or ethnicity. The FTA differed from the sTEA by a mean of 2.04° ± 1.50°. Least accurate was the aTEA, which differed from the sTEA by a mean of 2.05° ± 1.33°. The combination of 3 axes that are readily available intraoperatively (the Whiteside line, aTEA, and PCA+3°ER) differed from the sTEA by a mean of 1.80° ± 0.70°. CONCLUSIONS: In the largest study of its kind, analysis of CT scans of 2,128 femora revealed that no 1 axis could serve as a marker of femoral component rotation with both high accuracy and low variability. Utilizing a combination of 3 methods (PCA+3°ER, the Whiteside or sulcus line, and aTEA) to maximize accuracy and sex and ethnic generalizability when positioning the femoral component is recommended. CLINICAL RELEVANCE: A large-scale study using a CT-based biomorphometric database demonstrated that use of a combination of 3 axes (PCA+3°ER, the Whiteside or sulcus line, and aTEA) was the optimal strategy for judging femoral component rotation.

The effect of c-arm tilt on accuracy of intraoperative fluoroscopy in assessing acetabular component position during direct anterior approach for hip arthroplasty.

Intraoperative fluoroscopy can improve the precision of acetabular component positioning during direct anterior hip arthroplasty. However, changes in pelvic tilt with c-arm positioning may compromise accuracy. A geometric model of an acetabular component's projection onto fluoroscopy images was created and manipulated to simulate c-arm tilt. An apparently ideally-placed cup will have its effective anteversion changed by 7.5° with just 10° of caudal/cephalad tilt of the c-arm. This effect is greater in cups that are more horizontally placed or less anteverted. Accurate c-arm positioning is crucial, as small errors in tilt can have considerable effects on final cup position.

Prevalence of Asymptomatic Achilles Tendinosis.

BACKGROUND: Most patients who sustain Achilles tendon ruptures (ATRs) have no clinical symptoms prior to ATR. The objective of this study was to define the prevalence of ultrasound-detectable Achilles tendinopathy in asymptomatic patients in an at-risk group. METHODS: This was a cross-sectional study that collected data from a group of volunteers. All participants were given IPAQ questionnaires to gauge daily activity level, in addition to a demographic form. Participants underwent a physical examination, Silfverskiold test, and an ultrasonographic examination to evaluate for presence of Achilles tendinopathy. Fifty-one volunteers (30 female, 21 male) and 102 Achilles tendons were assessed in this study. The mean age was 27.4±6.3, with an average BMI of 23.5±3.9. Ninety-two percent of participants were categorized as having moderate or high activity levels per the iPAQ questionnaire. RESULTS: Sixteen tendons had at least 1 abnormality: 10 (9.8%) had hypoechoic foci, 9 (8.8%) had calcifications, 1 (0.9%) had increased vascularity, and 1 (0.9%) had a low-grade interstitial tear. Approximately 40% of patients were noted to have a gastroc equinus contracture on Silfverskiold testing. In addition, 14.7% of patients with a gastroc equinus had a hypoechoic focus compared to 8.6% of patients without gastroc equinus ( P = .5003). Logistic regression analysis demonstrated that an increased BMI was a significant risk factor for having an Achilles tendon abnormality on ultrasonography ( P < .01, odds ratio = 1.41). CONCLUSION: In this study, 16% of the Achilles tendons were abnormal and had at least 1 abnormality on ultrasonography. This group of patients was generally young, healthy, and active, thus a group at risk for ATRs. Only 40% of patients had gastrocnemius equinus, although a slightly higher non-significant percentage of those with hypoechoic foci had gastrocnemius equinus. It may be advantageous to prophylactically treat these patients with rehabilitation exercises to minimize the risk of ATR. LEVEL OF EVIDENCE: Level II, comparative prognostic study.