Combined FDG PET/MRI versus Standard-of-Care Imaging in the Evaluation of Cardiac Sarcoidosis.

Purpose: To compare combined cardiac fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/MRI with standard-of-care evaluation using cardiac MRI, 18F-FDG PET/CT, and SPECT perfusion imaging in suspected cardiac sarcoidosis (CS) with respect to radiation dose, imaging duration, and diagnostic test performance. Materials and Methods: Consecutive patients with suspected CS undergoing clinical evaluation with cardiac 18F-FDG PET/CT and gated rest technetium 99m sestamibi SPECT perfusion imaging were prospectively recruited between November 2017 and May 2021 for parallel assessment with combined cardiac 18F-FDG PET/MRI on the same day (ClinicalTrials.gov identifier, NCT03356756). Total effective radiation dose and imaging duration were compared between approaches (combined cardiac PET/MRI vs separate cardiac MRI, PET/CT, and SPECT). MRI findings were initially interpreted without PET data, and then PET and late gadolinium enhancement images were fused and interpreted together. Final diagnosis of CS was established using Japanese Ministry of Health and Welfare guidelines. Results: Forty participants (mean age, 54 years ± 14 [SD]; 26 [65%] male participants) were included, 14 (35%) with a final diagnosis of CS. Compared with separate cardiac MRI, PET/CT, and SPECT perfusion imaging, combined cardiac PET/MRI had 52% lower total radiation dose (8.0 mSv ± 1.2 vs 16.8 mSv ± 1.6, P < .001) and 43% lower total imaging duration (122 minutes ± 15 vs 214 minutes ± 26, P < .001). Combined PET/MRI had the highest area under the curve for diagnosis of CS (0.84) with 96% specificity and 71% sensitivity for colocalized FDG uptake and late gadolinium enhancement in a pattern typical for CS. Conclusion: In the evaluation of suspected CS, combined cardiac 18F-FDG PET/MRI had a lower radiation dose, shorter imaging duration, and higher diagnostic performance compared with standard-of-care imaging.Clinical trial registration no. NCT03356756Keywords: Cardiac Sarcoidosis, 18F-FDG PET/MRI, 18F-FDG PET/CT, SPECT Perfusion Imaging, Cardiac MRI, Standard-of-Care Imaging Supplemental material is available for this article. © RSNA, 2023.

Canadian Association of Radiologists/Canadian Association for Interventional Radiology/Canadian Society of Thoracic Radiology Guidelines on Thoracic Interventions.

Thoracic interventions are frequently performed by radiologists, but guidelines on appropriateness criteria and technical considerations to ensure patient safety regarding such interventions is lacking. These guidelines, developed by the Canadian Association of Radiologists, Canadian Association for Interventional Radiology and Canadian Society of Thoracic Radiology focus on the interventions commonly performed by thoracic radiologists. They provide evidence-based recommendations and expert consensus informed best practices for patient preparation; biopsies of the lung, mediastinum, pleura and chest wall; thoracentesis; pre-operative lung nodule localization; and potential complications and their management.

Development of a Machine Learning Algorithm for Prediction of Complications and Unplanned Readmission Following Primary Anatomic Total Shoulder Replacements.

Background: The demand and incidence of anatomic total shoulder arthroplasty (aTSA) procedures is projected to increase substantially over the next decade. There is a paucity of accurate risk prediction models which would be of great utility in minimizing morbidity and costs associated with major post-operative complications. Machine learning is a powerful predictive modeling tool and has become increasingly popular, especially in orthopedics. We aimed to build a ML model for prediction of major complications and readmission following primary aTSA. Methods: A large California administrative database was retrospectively reviewed for all adults undergoing primary aTSA between 2015 to 2017. The primary outcome was any major complication or readmission following aTSA. A wide scope of standard ML benchmarks, including Logistic regression (LR), XGBoost, Gradient boosting, AdaBoost and Random Forest were employed to determine their power to predict outcomes. Additionally, important patient features to the prediction models were indentified. Results: There were a total of 10,302 aTSAs with 598 (5.8%) having at least one major post-operative complication or readmission. XGBoost had the highest discriminative power (area under receiver operating curve AUROC of 0.689) of the 5 ML benchmarks with an area under precision recall curve AURPC of 0.207. History of implant complication, severe chronic kidney disease, teaching hospital status, coronary artery disease and male sex were the most important features for the performance of XGBoost. In addition, XGBoost identified teaching hospital status and male sex as markedly more important predictors of outcomes compared to LR models. Conclusion: We report a well calibrated XGBoost ML algorithm for predicting major complications and 30-day readmission following aTSA. History of prior implant complication was the most important patient feature for XGBoost performance, a novel patient feature that surgeons should consider when counseling patients.

Combined simultaneous FDG-PET/MRI with T1 and T2 mapping as an imaging biomarker for the diagnosis and prognosis of suspected cardiac sarcoidosis.

PURPOSE: To evaluate the diagnostic and prognostic significance of combined cardiac 18F-fluorodeoxyglucose (FDG) PET/MRI with T1/T2 mapping in the evaluation of suspected cardiac sarcoidosis. METHODS: Patients with suspected cardiac sarcoidosis were prospectively enrolled for cardiac 18F-FDG PET/MRI, including late gadolinium enhancement (LGE) and T1/T2 mapping with calculation of extracellular volume (ECV). The final diagnosis of cardiac sarcoidosis was established using modified JMHW guidelines. Major adverse cardiac events (MACE) were assessed as a composite of cardiovascular death, ventricular tachyarrhythmia, bradyarrhythmia, cardiac transplantation or heart failure. Statistical analysis included Cox proportional hazard models. RESULTS: Forty-two patients (53 ± 13 years, 67% male) were evaluated, 13 (31%) with a final diagnosis of cardiac sarcoidosis. Among patients with cardiac sarcoidosis, 100% of patients had at least one abnormality on PET/MRI: FDG uptake in 69%, LGE in 100%, elevated T1 and ECV in 100%, and elevated T2 in 46%. FDG uptake co-localized with LGE in 69% of patients with cardiac sarcoidosis compared to 24% of those without, p = 0.014. Diagnostic specificity for cardiac sarcoidosis was highest for FDG uptake (69%), elevated T2 (79%), and FDG uptake co-localizing with LGE (76%). Diagnostic sensitivity was highest for LGE, elevated T1 and ECV (100%). After median follow-up duration of 634 days, 13 patients experienced MACE. All patients who experienced MACE had LGE, elevated T1 and elevated ECV. FDG uptake (HR 14.7, p = 0.002), elevated T2 (HR 9.0, p = 0.002) and native T1 (HR 1.1 per 10 ms increase, p = 0.044) were significant predictors of MACE even after adjusting for left ventricular ejection fraction and immune suppression treatment. The presence of FDG uptake co-localizing with LGE had the highest diagnostic performance overall (AUC 0.73) and was the best predictor of MACE based on model goodness of fit (HR 14.9, p = 0.001). CONCLUSIONS: Combined cardiac FDG-PET/MRI with T1/T2 mapping provides complementary diagnostic information and predicts MACE in patients with suspected cardiac sarcoidosis.

Development of a Machine Learning Algorithm for Prediction of Complications and Unplanned Readmission Following Reverse Total Shoulder Arthroplasty.

Background: Reverse total shoulder arthroplasty (rTSA) offers tremendous promise for the treatment of complex pathologies beyond the scope of anatomic total shoulder arthroplasty but is associated with a higher rate of major postoperative complications. We aimed to design and validate a machine learning (ML) model to predict major postoperative complications or readmission following rTSA. Methods: We retrospectively reviewed California's Office of Statewide Health Planning and Development database for patients who underwent rTSA between 2015 and 2017. We implemented logistic regression (LR), extreme gradient boosting (XGBoost), gradient boosting machines, adaptive boosting, and random forest classifiers in Python and trained these models using 64 binary, continuous, and discrete variables to predict the occurrence of at least one major postoperative complication or readmission following primary rTSA. Models were validated using the standard metrics of area under the receiver operating characteristic (AUROC) curve, area under the precision-recall curve (AUPRC), and Brier scores. The key factors for the top-performing model were determined. Results: Of 2799 rTSAs performed during the study period, 152 patients (5%) had at least 1 major postoperative complication or 30-day readmission. XGBoost had the highest AUROC and AUPRC of 0.681 and 0.129, respectively. The key predictive features in this model were patients with a history of implant complications, protein-calorie malnutrition, and a higher number of comorbidities. Conclusion: Our study reports an ML model for the prediction of major complications or 30-day readmission following rTSA. XGBoost outperformed traditional LR models and also identified key predictive features of complications and readmission.

Outpatient Shoulder Arthroplasty-A Systematic Review.

OBJECTIVE: Recent reports have shown that outpatient shoulder arthroplasty (SA) may be a safe alternative to inpatient management in appropriately selected patients. The purpose was to review the literature reporting on outpatient SA. METHODS: A systematic review of publications on outpatient SA was performed. Included publications discussed patients who were discharged on the same calendar day or within 23 hours from surgery. Articles were categorized by discussions on complications, readmissions, and safety, patient selection, pain management strategies, cost effectiveness, and patient and surgeon satisfaction. RESULTS: Twenty-six articles were included. Patients undergoing outpatient SA were younger and with a lower BMI than those undergoing inpatient SA. Larger database studies reported more medical complications for patients undergoing inpatient compared to outpatient SA. Articles on pain management strategies discussed both single shot and continuous interscalene blocks with similar outcomes. Both patients and surgeons reported high levels of satisfaction following outpatient SA, and cost analysis studies demonstrated significant cost savings for outpatient SA. CONCLUSION: In appropriately selected patients, outpatient SA can be a safe, cost-saving alternative to inpatient care and may lead to high satisfaction of both patients and physicians, though further studies are needed to clarify appropriate utilization of outpatient SA.

Dual Versus Single-Plate Fixation of Midshaft Clavicular Fractures: A Retrospective Comparative Study.

BACKGROUND: Implant-related symptoms are the most common reason for reoperation after open reduction and internal fixation (ORIF) of midshaft clavicular fractures. Dual mini-fragment plate fixation is a relatively new solution that may decrease implant prominence while maintaining fixation strength and function. There are minimal published data comparing reoperation rates and clinical outcomes between single, superior-plate constructs and dual mini-fragment plate constructs in the fixation of midshaft clavicular fractures. We hypothesized that reducing plate size with the use of dual mini-fragment plating compared with standard, 3.5-mm, superior plating would minimize implant symptoms and the corresponding need for reoperation while still providing sufficient fixation to allow fracture-healing and return to function. METHODS: We retrospectively reviewed the cases of 44 consecutive patients who underwent ORIF of displaced midshaft clavicular fractures utilizing either a single, 3.5-mm, superior plate construct (21 patients) or a dual, 2.7-mm and 2.4-mm, plate construct (23 patients). Outcomes at a minimum of 2 years were assessed. Primary outcome measures included reoperation for any reason and the American Shoulder and Elbow Surgeons (ASES) Standardized Shoulder Assessment Form, patient self-report section. RESULTS: There was a 100% union rate in both groups. None (0%) of the 23 patients who received the dual (2.7-mm and 2.4-mm) plate construct and 6 (29%) of the 21 patients who received the single (3.5-mm) plate construct underwent reoperation for implant-related symptoms. Using a Fisher exact test, the rate of reoperation was compared between the groups, and the difference was found to be significant (p = 0.008). Using an unpaired t test, the difference in mean ASES scores was not significant (p = 0.138) between the dual-plate group (98 of 100) and the single superior plate group (96 of 100) with retained implants. CONCLUSIONS: In our comparative retrospective series, dual fixation utilizing a 2.7-mm superior plate and a 2.4-mm anterior plate for the treatment of displaced midshaft clavicular fractures was associated with a significantly lower rate of reoperation when compared with single, 3.5-mm, superior plate fixation. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Do glenoid retroversion and humeral subluxation affect outcomes following total shoulder arthroplasty?

BACKGROUND: Glenoid retroversion and humeral head subluxation have been suggested to lead to inferior outcomes after total shoulder arthroplasty (TSA). There are limited data to support this suggestion. We investigated whether preoperative glenoid retroversion and humeral head subluxation are associated with inferior outcomes after TSA and whether change of retroversion influences outcomes after TSA. METHODS: Patients undergoing TSA with minimum 2-year follow-up were included from a prospectively collected institutional shoulder arthroplasty database. Retroversion and humeral head subluxation before and after surgery were measured on axillary radiographs. Postoperative radiographs were -evaluated for glenoid component loosening and compared between groups. Spearman correlations were determined between retroversion measurements and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores. Patients were analyzed in groups based on retroversion and humeral head subluxation. RESULTS: There were 113 patients (50% follow-up rate) evaluated at 4.2 years postoperatively. The mean preoperative retroversion (15.3° ± 7.7°) was significantly higher than postoperative retroversion (10.0° ± 6.8°; P < .0001). There was no correlation between postoperative glenoid version or humeral head subluxation and ASES scores. For patients with preoperative retroversion of >15°, there was no difference in outcome scores based on postoperative retroversion. There were no differences in preoperative or postoperative version for patients with or without glenoid lucencies. DISCUSSION: We observed no significant relationship between postoperative glenoid retroversion or humeral head subluxation and clinical outcomes in patients following TSA. For patients with preoperative retroversion >15°, change of retroversion during TSA had no impact on their clinical outcomes at short-term follow-up.

Platelet-Rich Plasma, Bone Morphogenetic Protein, and Stem Cell Therapies.

The frequency of use of "biologics," including platelet-rich plasma (PRP), bone morphogenetic protein (BMP), and stem cell therapies in the treatment of orthopaedic conditions has significantly increased over the past few decades. The use of PRP and stem cells has been proposed for a wide variety of conditions including knee and hip osteoarthritis (OA), tendon strains and tendinopathies, muscle strains, and acute and chronic soft-tissue injuries. It has also been proposed for use in the enhancement of healing during surgical treatments. BMP has seen use in promoting fracture union and spinal fusion and has been researched as an adjunct in other procedures as well. The current state of the literature in the use and support of these biologics is outlined here.

Failed Reverse Shoulder Arthroplasty and Recommendations for Revision.

PURPOSE OF REVIEW: The most common complications warranting revision consideration in reverse shoulder arthroplasty (RSA) include instability and its associated causes: infection, periprosthetic fracture, and glenoid baseplate loosening. Management of complications can be challenging and the nuances of treatment are still being elucidated. The focus of this paper is to review the treatment of the failed RSA and discuss evidence-based recommendations for revision. RECENT FINDINGS: The most common complications requiring revision RSA are instability and infection. The causes for instability can be subdivided into three main subcategories: loss of compression, loss of containment, and impingement. Loss of compression is further broken down into 6 subcategories revolving around abnormal prosthesis positioning, undersized prostheses, or intrinsic soft-tissue tension loss leading to instability. Periprosthetic infection can also lead to instability, yet the most appropriate management for infected RSA remains controversial. Restoring stability by maximizing deltoid and soft tissue tension while avoiding impingement revolves around three basic methods: (1) lateralizing and/or upsizing the glenosphere to an inferior position on the glenoid, (2) use of a more constrained polyethylene insert, and (3) distalizing the humerus by increasing the polyethylene thickness and/or the thickness of the humeral tray. Management of periprosthetic joint infection can be performed in one-stage, two-stage, or "three-stage" procedures all showing good outcomes with two-stage procedures being the most commonly performed. However, persistent positive culture with propriobacterium acnes can occur in up to 25% of cases. In order to limit the associated morbidity from failed revision reverse shoulder arthroplasty, continued research on best management of associated complications is warranted.

Osteoarthritis and ACL Reconstruction-Myths and Risks.

PURPOSE OF REVIEW: Anterior cruciate ligament (ACL) injury is one of the most common ligamentous injuries suffered by athletes participating in cutting sports. A common misperception is that ACL reconstruction can prevent osteoarthritis (OA). The goal of this paper is to review and discuss the contributing factors for the development of OA following ACL injury. RECENT FINDINGS: There has been interesting new research related to ACL reconstruction. As understanding of knee biomechanics following ACL injury and reconstruction has changed over time, many surgeons have changed their surgical techniques to low anterior drilling to position their femoral tunnel in an attempt to place the ACL in a more anatomic position. Even with this change in the femoral tunnel position, 85% of knees following ACL reconstruction have abnormal tibial motion compared to contralateral non-injured knees. Studies have shown increases in inflammatory cytokines in the knee following ACL injury, and newer MRI sequences have allowed for earlier objective detection of degenerative changes to cartilage following injury. Recent studies have shown that injecting IL-1 receptor antagonist and corticosteroids can modulate the post-injury inflammatory cascade. ACL reconstruction does not prevent the development of OA but can improve knee kinematics and reduce secondary injury to the cartilage and meniscus. Advancements in imaging studies has allowed for earlier detection of degenerative changes in the knee, which has allowed researchers to study how new interventions can alter the course of degenerative change in the knee following ACL injury.

Do Preoperative and Postoperative Glenoid Retroversion Influence Outcomes After Reverse Total Shoulder Arthroplasty?

BACKGROUND: There are limited data on the effect of glenoid retroversion in clinical outcomes following reverse total shoulder arthroplasty (RTSA). The purpose of this study was to evaluate if surgical correction of retroversion affects outcomes following RTSA. METHODS: An institutional database was utilized to identify 177 patients (mean age: 68.2 ± 10.1 years) with minimum 2-year follow-up after primary RTSA. Glenoid version was measured on preoperative and postoperative radiographs. American Shoulder and Elbow Surgeons (ASES) scores and range of motion were collected before and after RTSA. Change in retroversion was determined by comparing preoperative and postoperative glenoid retroversion on radiographs using paired Wilcoxon signed-rank test. Spearman's rank correlation was used to investigate relationships between ASES scores and glenoid retroversion. RESULTS: The mean postoperative ASES composite score (75.5 ± 22.7) was significantly higher than preoperative (36.8 ± 19.2; P < .0001). The mean preoperative glenoid retroversion was 9.1 ± 6.7° compared to 6.5 ± 5.1° postoperatively (P < .0001). There was no correlation between postoperative ASES scores and preoperative retroversion (r = .014, P = .85) or postoperative retroversion (r = -.043, P = .57). There was no statistical relationship between postoperative retroversion and range of motion, though there is a risk of inadequate power given the sample size. CONCLUSIONS: Patient-reported outcomes and range of motion measurements following RTSA at short-term follow-up appear to be independent of either preoperative or postoperative glenoid retroversion.

Cyclic testing of tibialis tendon allografts for anterior cruciate ligament reconstruction using suture-post versus spiked washer tibial fixation.

BACKGROUND: The purpose of this study was to directly compare spiked washer and suture-post tibial-sided fixation techniques used for anterior cruciate ligament reconstruction by measuring anterior tibial translation during cyclic tests. METHODS: Fresh-frozen human knees were tested using a robotic system that applied 250 cycles of anterior-posterior tibial force (134 N) at 30° flexion, while recording tibial translation. Ten intact knees were tested to collect baseline data for native specimens. A single knee was selected to test ligament reconstructions using doubled tibialis tendon allografts. All grafts were fixed proximally using an EndoButton™, and the tibial end of the graft was fixed with either a spiked washer or with a suture post placed at two different locations (near and distant) relative to the tibial tunnel. FINDINGS: Mean first cycle translation for intact knees was 4.8 (sd 1.8) mm; means after reconstruction were 2.6 (sd 0.9) mm (spiked washer), 10.1 (sd 1.9) mm (suture post near), and 10.4 (sd 1.5) mm (suture post distant). Corresponding means for translation increase over 250 cycles were 0.3 (sd 0.2) mm, 3.6 (sd 1.3) mm, 7.2 mm (sd 0.9) mm, and 8.0 (sd 1.3) mm. All mean increases (first cycle and cyclic) after ACL reconstruction were significantly greater than those for the intact knees, and all means with a suture post were significantly greater than those with a spiked washer. There were no significant differences between mean translations for near and distant suture post locations. INTERPRETATION: Use of suture post fixation for anterior cruciate ligament reconstruction is questioned since increases in anterior tibial translation could lead to excessive post-operative knee laxity and possibly early clinical failure.

Use of Air Arthrograms to Aid in Joint Distraction During Hip Arthroscopic Surgery Decreases Postoperative Pain and Opioid Requirements.

BACKGROUND: Positive-pressure air arthrography and venting of the hip capsule are techniques used to decrease the traction forces needed for joint distraction during hip arthroscopic surgery. Little is known about the effects that these techniques have on postoperative pain. HYPOTHESIS: Positive-pressure air arthrography and venting during hip arthroscopic surgery will decrease patient-reported pain and narcotic requirements in the acute postoperative setting. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective cohort analysis was conducted to analyze 35 patients who underwent positive-pressure air arthrography and venting to aid joint distraction during hip arthroscopic surgery versus a group with similar demographics, pathologies, and treatments who did not undergo air arthrography. Numeric pain rating scale (NPRS) scores and medication administration including narcotic and nonnarcotic analgesia in the postanesthesia care unit (PACU) were tracked and compared. RESULTS: The maximum (7.17 vs 4.97, respectively), minimum (2.43 vs 1.09, respectively), and mean (5.15 vs 3.11, respectively) NPRS scores were all higher in the control group compared with the air arthrogram group (P < .001, P = .007, and P < .001, respectively). The administration of oral morphine equivalents (OMEs) during the PACU stay was significantly lower in the air arthrogram group, with a mean of 36.75 ± 11.37 OMEs, compared with 44.53 ± 16.06 OMEs in the control group (P = .023). There was no difference in postoperative nonopioid medications, such as ketorolac or acetaminophen, given between groups. CONCLUSION: Patients undergoing hip arthroscopic surgery with air arthrography and venting used to aid distraction had significantly less postoperative pain and required a lower total dosage of opioids during their PACU stay when compared with patients who underwent hip arthroscopic surgery without air arthrography.

Who Cares for Total Hip Arthroplasty Complications? Rates of Readmission to a Hospital Different From the Location of the Index Procedure.

INTRODUCTION: While the number of total hip arthroplasties (THAs) performed increases, so is the number of postoperative readmissions, resulting in costly episodes of care that may disproportionately affect certain hospitals. This study examines the rates of readmission of patients to the same hospital at which they underwent index THA, compared with readmission to a different hospital. METHODS: Data for all hospital discharges from 1995 to 2010 were obtained from the California Office of Statewide Health Planning and Development database. Patient outcomes, readmission data, demographic information, hospital teaching status, and location were analyzed. Regression modeling was used to evaluate the effect of hospital teaching status, location, and individual complications on the risk of readmission to the same hospital as opposed to a different hospital following the index procedure. RESULTS: The overall postoperative readmission rate for specific defined complications or all-cause 30-day readmissions was 3.92%, with 75.17% readmitted to the same hospital. Following index THA at a nonacademic or academic hospital, 95.9% and 84.6% of patients were readmitted to the same type of hospital, respectively. Patients who had their index procedure at an academic hospital had lower odds for readmission to the same hospital (odds ratio, 0.734; P < 0.0001) compared with nonacademic centers. Hospitals in midsize towns had higher odds of readmission to the same hospital (odds ratio, 1.735; P = 0.0012) compared with those in large metropolitan areas. DISCUSSION: Although more than 75% of patients with unplanned readmissions went to the same hospital as their index THA, academic and larger metropolitan hospitals had higher odds of postoperative readmissions to a different hospital.

A novel method for determining sagittal pediatric patellar height with the Blumensaat-Epiphyseal Containment of the Knee Angle.

Defining normal pediatric patellar height is complicated. Current methods use ratios calculated from lateral radiographs, but often provide inconsistent results and are time-consuming. It has been observed that the angle formed by Blumensaat's line and the distal femoral physis, when extended, form an area of patellar containment throughout a range of knee flexion. Deemed the Blumensaat-Epiphyseal Containment of the Knee (BECK) Angle, the objective of this study was to investigate this as a simple alternative to identify normal pediatric patellar height. Lateral radiographs were taken every 15° from 0° to 90° flexion on 10 fresh-frozen cadaveric knees. Patellar height was measured as the percentage of pole-to-pole patellar length contained within the BECK angle. The method was then applied to normal lateral radiographs of 105 pediatric knees, divided into age groups of 7-9, 10-12, and 13-16 years old. BECK angle patellar containment was compared with previously described methods. For cadaveric specimens, at least 50% patellar containment occurred between 0° and 71° flexion without quadriceps tension and between 21° and 81° flexion with 30 N of quadriceps tension. For pediatric radiographs, flexion ranged from 9° to 81°. At least 50% patellar containment occurred in 96% of knees in all three age groups. Knee flexion fell within a range of 15°-60° in 92 of the 105 pediatric knees. Limiting the analysis to this range, at least 50% patellar containment occurred in 99% of knees in all three age groups. On the basis of this study, normal pediatric knee lateral radiographs between 15° and 60° flexion should show at least 50% patellar containment within the BECK angle. LEVEL OF EVIDENCE: Diagnostic Level II study.

Effects of Anterior Closing Wedge Tibial Osteotomy on Anterior Cruciate Ligament Force and Knee Kinematics.

BACKGROUND: A certain percentage of patients undergoing anterior cruciate ligament (ACL) reconstruction will experience graft failure, and there is mounting evidence that an increased posterior tibial slope (PTS) may be a predisposing factor. Theoretically, under tibiofemoral compression force (TFC), a reduced PTS would induce less anterior tibial translation (ATT) and lower ACL force. HYPOTHESIS: Ten-degree anterior closing wedge osteotomy of the proximal tibia will significantly reduce ACL force and alter knee kinematics during robotic testing. STUDY DESIGN: Controlled laboratory study. METHODS: Eleven fresh-frozen human knees were instrumented with a load cell that measured ACL force as the knee was flexing continuously from 0° to 50° under 200-N TFC as our initial testing condition, followed by the addition of the following tibial loads: 45-N anterior force (AF), 5-N·m valgus moment (VM), 2-N·m internal torque (IT), and all loads combined. ACL force and knee kinematics were recorded before and after osteotomy. RESULTS: Osteotomy produced significant changes in the tibiofemoral position at full extension (as defined by a 2-N·m knee extension moment). This resulted in apparent knee hyperextension (9.4° ± 1.9°), posterior tibial translation (7.9 mm ± 1.6 mm), internal tibial rotation (3.2° ± 2.3°), and valgus tibial rotation (3.2° ± 1.5°). During straight knee flexion with TFC alone, osteotomy reduced ACL force to 0 N beyond 5° of flexion, and ATT was reduced between 0° and 45° ( P < .05). With TFC + AF, ACL force was reduced beyond 5° of flexion, and ATT was reduced between 5° and 45° ( P < .05). With TFC + VM, ACL force was less than 10 N beyond 5° of flexion, and ATT was reduced at all flexion angles ( P < .05). Under the loading conditions TFC + IT and TFC + IT + AF + VM, osteotomy did not significantly change ACL force or ATT at any flexion angle. CONCLUSION: In general, osteotomy lowered ACL force and reduced ATT when IT was not present. The benefits of osteotomy were negated when IT was included possibly because the dominant mechanism of ACL force generation was cruciate impingement from internal winding and not ATT. CLINICAL RELEVANCE: PTS-reducing osteotomy significantly decreased ACL force and reduced ATT for knee loads that did not include IT.