Semi-automatic proximal humeral trabecular bone density assessment tool: technique application and clinical validation.

PURPOSE: This study aimed to apply a newly developed semi-automatic phantom-less QCT (PL-QCT) to measure proximal humerus trabecular bone density based on chest CT and verify its accuracy and precision. METHODS: Subcutaneous fat of the shoulder joint and trapezius muscle were used as calibration references for PL-QCT BMD measurement. A self-developed algorithm based on a convolution map was utilized in PL-QCT for semi-automatic BMD measurements. CT values of ROIs used in PL-QCT measurements were directly used for phantom-based quantitative computed tomography (PB-QCT) BMD assessment. The study included 376 proximal humerus for comparison between PB-QCT and PL-QCT. Two sports medicine doctors measured the proximal humerus with PB-QCT and PL-QCT without knowing each other's results. Among them, 100 proximal humerus were included in the inter-operative and intra-operative BMD measurements for evaluating the repeatability and reproducibility of PL-QCT and PB-QCT. RESULTS: A total of 188 patients with 376 shoulders were involved in this study. The consistency analysis indicated that the average bias between proximal humerus BMDs measured by PB-QCT and PL-QCT was 1.0 mg/cc (agreement range - 9.4 to 11.4; P > 0.05, no significant difference). Regression analysis between PB-QCT and PL-QCT indicated a good correlation (R-square is 0.9723). Short-term repeatability and reproducibility of proximal humerus BMDs measured by PB-QCT (CV: 5.10% and 3.41%) were slightly better than those of PL-QCT (CV: 6.17% and 5.64%). CONCLUSIONS: We evaluated the bone quality of the proximal humeral using chest CT through the semi-automatic PL-QCT system for the first time. Comparison between it and PB-QCT indicated that it could be a reliable shoulder BMD assessment tool with acceptable accuracy and precision. This study developed and verify a semi-automatic PL-QCT for assessment of proximal humeral bone density based on CT to assist in the assessment of proximal humeral osteoporosis and development of individualized treatment plans for shoulders.

Bone age assessment based on different MRI modalities of the proximal humerus epiphysis: the comparisons of T1WI, T2WI, and PDWI.

Bone age assessment (BAA) is crucial in various fields, including legal proceedings, athletic competitions, and clinical medicine. However, the use of X-ray methods for age estimation without medical indication is subject to ethical debate, especially in forensic and athletic fields. The application of magnetic resonance imaging (MRI) with non-ionizing radiation can overcome this limitation in BAA. This study aimed to compare the application value of several MRI modalities of proximal humeral in BAA. A total of 468 patients with shoulder MRIs were retrospectively collected from a Chinese Han population aged 12-30 years (259 males and 209 females) for training and testing, including T1 weighted MRI (T1WI), T2 weighted MRI (T2WI), and Proton density weighted MRI (PDWI). Optimal regression models were established for age estimation, yielding mean absolute error (MAE) values below 2.0 years. The MAE values of T1WI were the lowest, with 1.700 years in males and 1.798 years in females. The area under the curve (AUC) and accuracy values of different MRI modalities of 16-year and 18-year thresholds were all around 0.9. For the 18-year threshold, T1WI outperformed T2WI and PDWI. In conclusion, the three MRI modalities of the proximal humerus can serve as reliable indicators for age assessment, while the T1WI performed better in age assessment and classification.

Assessment and Validation of Anterior Humeral Line for Diagnosing Supracondylar Humerus Fractures in the Pediatric Population.

INTRODUCTION: Pediatric supracondylar humerus fractures are commonly evaluated using the anterior humeral line (AHL) on a lateral radiograph. Rotational variations in radiographic projection are common due to child discomfort and could lead to changes in management based on where the AHL intersects the capitellum. The purpose of this study was to establish whether rotational variations in elbow rotation leads to significant changes in AHL position and whether drawing the AHL based on the distal humerus versus shaft is more tolerant to rotation. METHODS: Fifty children with nonoperative supracondylar humerus fractures were identified with sub optimally positioned injury and well positioned follow-up lateral radiographs. The proportion of the bone anterior to the intersection of the AHL and the capitellum was measured using the humeral shaft versus distal humerus to guide position of the AHL. This process was repeated on ten pediatric humerus dry cadaveric specimens which were imaged in 5-degree rotational increments along the axis of the humeral shaft from -20 to +20 degrees. RESULTS: AHL position correlated poorly when measured on rotated lateral radiographs of clinical patients versus non-rotated lateral radiographs when using the distal humerus as a guide (intraclass correlation coefficient 0.14), compared with when using the humeral shaft as a guide (intraclass correlation coefficient 0.81). When assessing the pediatric humerus dry cadavers between the 2 techniques, there was greater statistically significant variation in rotated positions compared with the neutral position in the distal humerus AHL measurement approach compared with the humeral shaft AHL measurement approach, with the mean AHL within the central third of the capitellum for more rotational positions when using the shaft compared with the distal humerus. CONCLUSIONS: With rotated lateral elbow radiographs in supracondylar humerus fractures, utilizing the humeral shaft provides more consistent AHL measurements than utilizing the distal humerus, and thus drawing the line starting at the shaft of the humerus is recommended for surgical decision making.

Humeral torsional side differences after nonoperative treatment of proximal humerus fractures and humeral shaft fractures: clinical and ultrasonographic assessment.

BACKGROUND: The purposes of this study were to investigate (1) sonographic humeral torsion (SHT) and side differences (∆SHT), and (2) to determine the relationship between SHT and range of rotational motion (RORM) as well as functional outcome scores of nonoperatively treated proximal humerus fractures (PHF) and humeral shaft fractures (HSF). METHODS: Between October 2020 and July 2021, consecutive patients with radiographically healed nonoperatively treated PHF and HSF were included in this analysis. Subjective perception of torsional side difference, correlation between SHT and RORM, Subjective Shoulder Value as well as absolute and adjusted Constant Score were determined. Degree of humeral torsional side differences were classified as follows: 0°-15°: minor; > 15°-30°: moderate; > 30°: major. Factors including gender, hand dominance, fracture type, and displacement were also assessed in order to investigate any association between these variables and ∆SHT. RESULTS: Sixty-five patients with nonoperatively treated PHF (n = 47) and HSF (n = 18) were analyzed. Mean follow-up was 13.2 months (range, 2.1-72.6). The majority (80% (52)) resulted in only minor, 15.4% (10) in moderate, and 4.6% (3) in major torsional side differences. Patients with minor or moderate torsional differences did not perceive any subjective side difference. While RORM correlated fairly to highly with functional outcomes, only very low to low correlation was observed between these measures and SHT and ∆SHT. Gender, fracture displacement, and type of fracture were not related to SHT and ∆SHT. However, significantly greater torsional side differences were observed, when the dominant side was involved (p = 0.026). CONCLUSION: Nonoperative early functional treatment of proximal humerus and humeral shaft fractures results mainly in only minor humeral torsional side differences. Minor and moderate amounts of torsional side differences might not be perceived by patients.

Reconstruction by allograft-prosthetic composite reverse shoulder arthroplasty after proximal humerus tumor resection: Clinical and radiographic assessment at a minimum 2years' follow-up.

INTRODUCTION: Reverse shoulder arthroplasty (RSA) is an option to conserve limb function after resection of proximal humerus malignancy. An allograft-composite RSA is an alternative to a tumor prosthesis, and can restore proximal humeral bone stock. The aim of the present study was to assess medium-term radiographic and clinical results for such composite implants. METHODS: Patients with malignant proximal humerus tumor treated by resection and reconstruction by composite RSA were retrospectively analyzed at a minimum 24months' follow-up. Clinical assessment used Constant score, Subjective Shoulder Value (SSV) and ADLER score. Standard radiographic work-up assessed allograft absorption and screened for implant loosening. RESULTS: Eleven patients were included, with a mean age of 51years (range: 19-87years) and mean 30months' follow-up (range: 24-84months). Mean tumor resection was 10cm (range: 6-17cm). Etiologies comprised chondrosarcoma (n=6), osteosarcoma (n=2), B-cell lymphoma (n=1) and single metastasis (n=2). Bony increased-offset allograft was associated to humerus reconstruction in 8 cases, and latissimus dorsi tendon transfer in 5 cases. Mean Constant score was 49 points, SSV 52%, and ADLER score 20 points. Increased glenoid implant offset associated to tendon transfer significantly improved anterior elevation and external rotation. Radiographic allograft consolidation to the native humerus was acquired in 73% of cases, while osteolysis in the epiphyseal-metaphyseal zone was found in 64%. There were no cases of humeral implant loosening. Glenoid allograft absorption was systematic (8/8 cases), without inducing loosening of the implant baseplate. CONCLUSION: Composite reverse shoulder arthroplasty is functionally effective after massive resection. However, allograft absorption is a drawback, casting doubt on continued use on the glenoid side. LEVEL OF EVIDENCE: IV.

Humerus trochlear angle (HTa)-a possible alternative for Baumann angle in the reduction of supracondylar humerus fractures.

BACKGROUND: The supracondylar humerus fractures are the most common fracture in children's elbows. Generally, close reduction and percutaneous pinning can provide satisfactory outcomes after adequate reduction. Baumann angle is commonly used to evaluate reduction quality, however, it may fail to assess reduction well when the elbow is in flexion and/or when the patient is young. We conducted this study to evaluate the potential value of the humerus trochlear angle (HTa) for the reduction evaluation and compare it with the Baumann angle. METHODS: We retrospectively reviewed supracondylar humerus fractures in our trauma center from 2016 to 2019. Patients were grouped as followed: in the HTa group, an arthrogram was used to evaluate the HTa angle and reduction (HTa, defined by the intersection of the axis of the humerus shaft and the tangent of the articular surface of the trochlear); In the Baumann group, the Baumann angle was used to assess the reduction. Baumann angle ratio (BA of injured side/BA of contralateral side) was calculated to evaluate the reduction quality between groups. Flynn's grading criteria were utilized to evaluate both function and cosmetic outcomes in two groups during the follow-up. Operation time, fluoroscopy shots, complications and Flynn's grading scores were compared between groups. RESULTS: A total of 57 patients with an average age of 4.62 years and follow-up duration of 21.49 ± 5.40 months were included in the analysis. The gender and age distributions were similar in the two groups. Fluoroscopy shots in the HTa group were significantly less than in Baumann group (16.17 ± 0.73 vs. 21.85 ± 0.78, p < 0.0001), and operation time were also less in HTa group (45.78 ± 1.96 min vs. 62.21 ± 1.58 min, p < 0.0001). Baumann ratio showed no significant difference between the two groups (1.002 ± 0.023 in the Baumann group and 1.01 ± 0.023 in HTa group, p < 0.0001). Length of hospitalization, complications, and Flynn's grading scores were similar between groups. The HTa angle was positively correlated with Baumann angle in the HTa group (R-value is 0.71 and P = 0.0002). CONCLUSIONS: There was no significant difference in reduction quality and Flynn's scores between HTa and Baumann groups. Furthermore, HTa was associated with shorter operation time and less radiation exposure in this investigation. Therefore, HTa may be a convenient and reliable parameter that could guide the reduction of supracondylar humerus fractures, especially for young children.

Assessment of Lateral Rotation Percentage and Rotational Deformity of the Elbow in Type 3 Supracondylar Humerus Fractures: A Biomechanical Study.

BACKGROUND: Supracondylar humerus (SCH) fractures are the most common elbow fractures in children. Historically, displaced (Gartland type 3) SCH fractures have been treated with closed reduction and percutaneous pinning. Fluoroscopic imaging is used intraoperatively in order to assess adequate reduction of the fracture fragments before pinning. On lateral fluoroscopic and radiographic images, a lateral rotation percentage (LRP) can be estimated in order to assess rotational deformity. The purpose of this study was to determine the true rotational deformity of distal humerus fracture fragments in SCH fractures based upon the LRP using a clinically relevant laterally based pinning technique. METHODS: In this study, a sawbones model was used to examine the correlation between calculated LRP and the true degree of rotational deformity with 3 of the most common extension-type SCH fracture types (low transverse, high transverse, and lateral oblique). Because fracture stability was not the focus of this study, a single pin was used to hold the construct and allow for fragment rotation along a fixed axis. In this study, 2 of the authors independently measured rotational deformity and compared this with LRP on fluoroscopic lateral imaging of a sawbones model at 0 to 45 degrees of rotational deformity. RESULTS: The LRP of all 3 patterns demonstrated a near linear increase from 0 to 45 degrees with maximum LRP measured at 45 degrees for each of the 3 patterns. Univariate linear regression demonstrated an increase in LRP for the low transverse pattern of 2.02% for every degree of rotation deformity (R2=0.97), 2.29% for the lateral oblique pattern (R2=0.986), and 1.17% for the high transverse pattern (R2=0.971). Maximum LRP was measured at 45 degrees for all 3 patterns with a mean of 53.5% for the high transverse pattern, 93.5% for the low transverse pattern, and 111.2% for the lateral oblique pattern. A higher LRP was measured with increasing degrees of rotational displacement in the low transverse and lateral oblique patterns for all degrees of rotational deformity compared to the high transverse pattern. CONCLUSION: There is a near linear correlation between the degree of malrotation and the LRP with more superior metaphyseal fracture patterns demonstrating a lower LRP than inferior fracture patterns. CLINICAL RELEVANCE: Using our data one can estimate the degree of malrotation based on the LRP on radiographs in the clinical setting. LEVEL OF EVIDENCE: Not applicable (basic-science article).

Development and ex-vivo assessment of a novel patient specific guide and instrumentation system for minimally invasive total shoulder arthroplasty.

OBJECTIVE: To develop and assess a novel guidance technique and instrumentation system for minimally invasive short-stemmed total shoulder arthroplasty that will help to reduce the complications associated with traditional open replacement such as poor muscle healing and neurovascular injury. We have answered key questions about the developed system including (1) can novel patient-specific guides be accurately registered and used within a minimally invasive environment?; (2) can accuracy similar to traditional techniques be achieved? METHODS: A novel intra-articular patient-specific guide was developed for use with a new minimally invasive posterior surgical approach that guides bone preparation without requiring muscle resection or joint dislocation. Additionally, a novel set of instruments were developed to enable bone preparation within the minimally invasive environment. The full procedure was evaluated in six cadaveric shoulders, using digitizations to assess accuracy of each step. RESULTS: Patient-specific guide registration accuracy in 3D translation was 2.2±1.2mm (RMSE±1 SD; p = 0.007) for the humeral component and 2.7±0.7mm (p<0.001) for the scapula component. Final implantation accuracy was 2.9±3.0mm (p = 0.066) in translation and 5.7-6.8±2.2-4.0° (0.001

Magnetic Resonance Imaging in Osteochondritis Dissecans of the Humeral Capitellum: Preoperative Assessment of Lesion Size and Lateral Wall Integrity.

PURPOSE: Magnetic resonance imaging (MRI) is a helpful tool in the evaluation of osteochondritis dissecans (OCD) of the humeral capitellum. The relationship between MRI appearance and clinically relevant intraoperative findings is incompletely understood. The goal of this study was to evaluate capitellar OCD lesions via preoperative MRI and to determine its accuracy in predicting lesion characteristics including lesion size and capitellar lateral wall integrity. METHODS: Patients surgically treated for capitellar OCD between January 2010 and June 2018 were reviewed. Preoperative MRI images were assessed by a musculoskeletal radiologist with documentation of lesion size, location, violation of the lateral wall, and stage, in accordance with previously established criteria. These data were compared with intraoperative findings. Involvement of the lateral wall of the capitellum was defined using 2 methods: (1) subchondral edema or articular cartilage disruption in the lateral third of the capitellum (lateral third method) or (2) disruption of the proximal-distal subchondral line along the lateral border of the capitellum descending vertically before the subchondral bone turns horizontally to form the radiocapitellar articulation (capitellar lateral wall sign method). Diagnostic test characteristics were compared for both methods. RESULTS: We reviewed the preoperative MRIs of 33 elbows with capitellar OCD and found no significant difference in mean lesion size between preoperative MRI (1.12 cm2) and intraoperative measurement (1.08 cm2). For detection of lateral wall integrity, preoperative MRI evaluation using the capitellar lateral wall sign method had an accuracy of 93%, sensitivity of 80%, specificity of 96%, positive predictive value of 80%, and negative predictive value of 96%. CONCLUSIONS: Preoperative MRI is a valid predictor of lesion size. The capitellar lateral wall sign method is highly accurate in the identification of lateral wall involvement, which may influence preoperative planning. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

Reliable skeletal maturity assessment for an AIS patient cohort: external validation of the proximal humerus ossification system (PHOS) and relevant learning methodology.

STUDY DESIGN: Validation of classification system. OBJECTIVES: To externally validate the Proximal Humerus Ossification System (PHOS) as a reliable skeletal maturity scoring system and to assess the learning curve associated with teaching the procedure to individuals of varying levels of experience. BACKGROUND: Assessment of skeletal maturity is essential for treatment decisions in Adolescent Idiopathic Scoliosis (AIS). PHOS is a five-stage system that uses the proximal humeral physis in assessing skeletal maturity and has been shown to reliably grade skeletal age leading up to and beyond peak growth age (PGA). This system is advantageous in the AIS patient, as it is often captured in standard scoliosis films. METHODS: A medical student, an orthopedic surgery resident (PGY-2), spine fellow, and experienced scoliosis surgeon in his 25th year in practice were given a three-slide PHOS learning module. Each participant rated 100 X-rays on two separate occasions, separated by 1 week. Intra- and inter-observer reliability, as well as cross-institutional reliability, were calculated using intraclass correlation coefficients (ICC) with 95% confidence intervals [CI95]. RESULTS: Average intra-observer reliability ICC between scoring sessions was 0.94 [0.92, 0.96] and inter-observer reliability by level of training were 0.94 [0.91, 0.96], 0.93 [0.9, 0.95], 0.94 [0.91, 0.96], 0.96 [0.94, 0.97] for the medical student, PGY-2, fellow, and attending, respectively. Reliability across institutions was 0.99 [0.98, 0.99]. Combined rating observations (n = 400) showed 82% exact matches, as well as 17% and 1% mismatches by 1 and 2 stages, respectively. Similar to the PHOS developers, we found PHOS stage 3 to occur immediately after PGA. CONCLUSION: PHOS is easily learned and employed by raters with varying levels of training. It comprises a five-stage system to reliably measure bone age leading up to PGA and thereafter. This new system relies on visualization of the proximal humerus, which is readily available on standard scoliosis X-rays. LEVEL OF EVIDENCE: Level III.

Does cement augmentation of the screws in angular stable plating for proximal humerus fractures influence the radiological outcome: a retrospective assessment.

BACKGROUND: Screw-tip augmentation in angular stable plating offers new possibilities for the treatment of complex proximal humerus fractures. This retrospective analysis was performed to evaluate the radiological outcome of proximal humerus fractures treated with angular stable plates and additional screw-tip cement augmentation in patients over the age of 60. MATERIALS AND METHODS: A retrospective single centre analysis was conducted from June 2013 to December 2016. The minimum follow-up time was set to 6 months after surgery. Anatomical reduction and fixation were evaluated in respect to reattached tuberosities to the head fragment and the adequate restoration of the calcar area not showing any valgus or varus malalignment. Complete fracture healing was determined 3 months after surgery. Any failures such as secondary displacement, primary screw perforation, intraarticular cement leakage and avascular necrosis of the humeral head with concomitant screw cut-out were assessed. RESULTS: In total, 24 patients (21 females; 3 males) at a median age of 77.5 (62-96) years were included. Five 2-part, twelve 3-part and seven 4-part fractures were detected. The measured median BMD value of 23 patients was 78.4 mg/cm3 (38.8-136.9 mg/cm3). Anatomical reduction was achieved in 50% of the patients. In most cases, the A level screws and the B1 screw were augmented with bone cement by a median of 7 (5-9) head screws used. Postoperative varus displacement was not detected in any of the patients. One patient (4.2%) sustained an early secondary displacement. Intraarticular cement leakage was detected in 3 patients (2 head-split fractures). Avascular necrosis of the humeral head was observed in 4 patients (16.7%). Revision surgery was necessary in four cases, using hemiarthroplasty twice and reverse shoulder arthroplasty the other two times. CONCLUSION: Screw-tip augmentation in angular stable plating for proximal humerus fracture treatment showed a low secondary displacement rate of 4.2% in patients suffering from poor bone quality. Nevertheless, the occurrence of avascular necrosis of the humeral head with mainly severe fracture patterns observed in this study was higher compared to previously reported results in the literature. Cement augmentation in head-split fractures is not recommended, considering the high risk of an intraarticular cement leakage.

An assessment of proximal humerus density with reference to stemless implants.

BACKGROUND: Shoulder arthroplasty humeral components have undergone several generational changes, with systems now offering shorter stems and stemless options. The stemless humeral implants obtain fixation in the trabecular bone of the proximal humerus through elaborate fixation features. To optimize implant design, the regional variations in bone density within the proximal humerus should be determined. As such, the purpose of this computed tomography-based study was to map the regional variations in bone density of the proximal humerus. METHODS: The trabecular-canal of the proximal humerus was extracted from computed tomography scans of 98 subjects and divided into 13 slices and 5 subsections (central, anterior, posterior, medial, and lateral). The average apparent density (ρAVG) was then quantified in each subsection of the trabecular-canal. RESULTS: Slice depth, subsection, and gender were all significant main effects, with additional significant interactions between slice depth, subsection, and osteoarthritic condition. The slices above the resection plane had the greatest ρAVG, with densities decreasing down the canal. The central subsection had significantly lower ρAVG than the peripheral sections, and the medial subsection tended to have the highest ρAVG (P < .001). Furthermore, the ρAVG of male subjects was significantly greater than that of female subjects (P < .001). CONCLUSIONS: The apparent density of the proximal humerus' trabecular-canal is nonuniform. This has implications for the design of stemless implants, indicating that implants seeking purchase in higher density bone should take advantage of the peripheral regions of the trabecular-canal within the first 15-20 mm beneath the humeral head resection plane.

A Novel Registration-Based Approach for 3D Assessment of Posttraumatic Distal Humeral Deformities.

BACKGROUND: With current 3-dimensional (3D) computer-based methods for the assessment of deformities, a surface registration method is applied to superimpose a computer model of the pathological bone onto a mirrored computer model of the contralateral side. However, because of bilateral differences, especially in humeral torsion, such template-based approaches may introduce bias in the assessment of a distal humeral deformity. We hypothesized that a novel registration approach might prove superior to the current approach in reducing such bias, thus yielding improved accuracy of 3D assessment of distal humeral deformities. METHODS: Three-dimensional triangular surface models were generated from computed tomographic (CT) data of 100 paired humeri without a pathological condition. Humeral segments of varying, predetermined lengths, excluding the distal part of the humerus, were defined. A surface registration algorithm was applied to superimpose the humeral models of both sides based on each selected segment. Humeral contralateral registration (HCR) errors, defined as the residual differences in apparent 3D orientation between the distal parts, were evaluated. RESULTS: The mean HCR error (and standard deviation) using the distal-most humeral shaft segment to assess the angular orientation was 2.3° ± 1.1 (range, 0.5° to 5.8°). Including the humeral head in the surface registration algorithm, however, as is done currently, resulted in a higher HCR error (p < 0.001). The HCR error using the proximal-most segment was >10° in 20% of the cases and between 5° and 10° in an additional 50% of the cases. By comparison, using the proposed distal-most humeral shaft segment, the HCR error was between 5° and 10° in only 2% of cases, and was never >10°. The proximal segments are nevertheless used in the proposed method for registering humeral length. CONCLUSIONS: The proposed new approach yields a deformity assessment that is less prone to bias arising from inherent bilateral differences and therefore is more accurate than current surface registration approaches. CLINICAL RELEVANCE: Accurate 3D assessment is of fundamental importance if computer-based methods are applied in the correction of posttraumatic deformities.

The course of the radial nerve in the distal humerus: A novel, anatomy based, radiographic assessment.

METHODS AND FINDINGS: Measurements were done on both arms of ten specially embalmed specimens. Arms were dissected and radiopaque wires attached to the radial nerve in the distal part of the upper arm. Digital radiographs were obtained to determine the course of the radial nerve in the distal 20 cm of the humerus in relation to bony landmarks; medial epicondyle and capitellum-trochlea projection (CCT). Analysis was done with ImageJ and Microsoft Excel software. We also compared humeral nail specifications from different companies with the course of the radial nerve to predict possible radial nerve damage. RESULTS: The distance from the medial epicondyle to point where the radial nerve bends from posterior to lateral was 142 mm on AP radiographs and 152 mm measured on the lateral radiographs. The average distance from the medial epicondyle to point where the radial nerve bends from lateral to anterior on AP radiographs was 66 mm. On the lateral radiographs where the nerve moves away from the anterior cortex 83 mm to the center of capitellum and trochlea (CCT). The distance from the bifurcation of the radial nerve into the posterior interosseous nerve (PIN) and superficial radial nerve was 21 mm on AP radiographs and 42 mm on the lateral radiographs (CCT). CONCLUSIONS: The course of the radial nerve in the distal part of the upper arm has great variety. Lateral fixation is relatively safe in a zone between the center of capitellum-trochlea and 48 mm proximal to this point. The danger zone in lateral fixation is in-between 48-122 mm proximal from CCT. In anteroposterior direction; distal fixation is dangerous between 21-101 mm measured from the medial epicondyle. The more distal, the more medial the nerve courses making it more valuable to iatrogenic damage. The IMN we compared with our data all show potential risk in case of (blind) distal locking, especially from lateral to medial direction.

Three-dimensional assessment of curvature, torsion, and canal flare index of the humerus of skeletally mature nonchondrodystrophic dogs.

OBJECTIVE To assess 3-D geometry of the humerus of dogs and determine whether the craniocaudal canal flare index (CFI) is associated with specific geometric features. SAMPLE CT images (n = 40) and radiographs (38) for 2 groups of skeletally mature nonchondrodystrophic dogs. PROCEDURES General dimensions (length, CFI, cortical thickness, and humeral head offset), curvature (shaft, humeral head, and glenoid cavity), version (humeral head and greater tubercle), and torsion were evaluated on CT images. Dogs were allocated into 3 groups on the basis of the craniocaudal CFI, and results were compared among these 3 groups. The CT measurements were compared with radiographic measurements obtained for another group of dogs. RESULTS Mean ± SD humeral head version was -75.9 ± 9.6° (range, -100.7° to -59.4°). Mean mechanical lateral distal humeral angle, mechanical caudal proximal humeral angle, and mechanical cranial distal humeral angle were 89.5 ± 3.5°, 50.2 ± 4.5°, and 72.9 ± 7.8°, respectively, and did not differ from corresponding radiographic measurements. Mean humeral curvature was 20.4 ± 4.4° (range, 9.6° to 30.5°). Mean craniocaudal CFI was 1.74 ± 0.18 (range, 1.37 to 2.10). Dogs with a high craniocaudal CFI had thicker cranial and medial cortices than dogs with a low craniocaudal CFI. Increased body weight was associated with a lower craniocaudal CFI. Radiographic and CT measurements of craniocaudal CFI and curvature differed significantly. CONCLUSIONS AND CLINICAL RELEVANCE CT-based 3-D reconstructions allowed the assessment of shaft angulation, torsion, and CFI. Radiographic and CT measurements of shaft curvature and CFI may differ.

Radiographic assessment of humeroulnar congruity in a medium and a large breed of dog.

Elbow joint incongruity is recognized as an important factor in the development, treatment, and prognosis of canine elbow dysplasia. Elbow incongruity has been measured based on radiographic joint space widths, however these values can be affected by the degree of elbow joint flexion. Recent studies have reported radiographic curvature radii as more precise measures of humeroulnar congruity in dogs. The aim of this prospective observational study was to describe radiographic curvature radii measured from flexed and extended elbow radiographs for a sample of dogs representing a medium breed (Portuguese Pointing Dog) and a large breed (Estrela Mountain Dog). The curvature radii from the ulnar trochlear notch and humeral trochlea were measured in 114 mediolateral elbow extended radiographic views (30 Portuguese Pointing Dog and 27 Estrela Mountain Dog), and 84 mediolateral flexed views (22 Portuguese Pointing Dog and 20 Estrela Mountain Dog). The sampled animals' ages ranged from 12 to 84 months (34.6 ± 17.8 months). Good agreement was observed between curvature radii measurements for flexed vs. extended views in both breed groups. Ulnar trochlear notch curvature radii measurements were greater than humeral trochlea curvature radii measurements in both breed groups. Both curvature radii were greater in the large-breed dog group vs. the medium-breed dog group. Both breed groups had ulnar and humeral curves with similar typology. However, the large breed group had greater intermediate differences between the humeroulnar surface curvature radii. Results from this study supported the use of curvature radii as measures of humeroulnar congruity in mediolateral flexed elbow radiographs of medium and large breed dogs.

In vivo estimation of the shoulder joint center of rotation using magneto-inertial sensors: MRI-based accuracy and repeatability assessment.

BACKGROUND: The human gleno-humeral joint is normally represented as a spherical hinge and its center of rotation is used to construct humerus anatomical axes and as reduction point for the computation of the internal joint moments. The position of the gleno-humeral joint center (GHJC) can be estimated by recording ad hoc shoulder joint movement following a functional approach. In the last years, extensive research has been conducted to improve GHJC estimate as obtained from positioning systems such as stereo-photogrammetry or electromagnetic tracking. Conversely, despite the growing interest for wearable technologies in the field of human movement analysis, no studies investigated the problem of GHJC estimation using miniaturized magneto-inertial measurement units (MIMUs). The aim of this study was to evaluate both accuracy and precision of the GHJC estimation as obtained using a MIMU-based methodology and a functional approach. METHODS: Five different functional methods were implemented and comparatively assessed under different experimental conditions (two types of shoulder motions: cross and star type motion; two joint velocities: ωmax = 90°/s, 180°/s; two ranges of motion: Ɵ = 45°, 90°). Validation was conducted on five healthy subjects and true GHJC locations were obtained using magnetic resonance imaging. RESULTS: The best performing methods (NAP and SAC) showed an accuracy in the estimate of the GHJC between 20.6 and 21.9 mm and repeatability values between 9.4 and 10.4 mm. Methods performance did not show significant differences for the type of arm motion analyzed or a reduction of the arm angular velocity (180°/s and 90°/s). In addition, a reduction of the joint range of motion (90° and 45°) did not seem to influence significantly the GHJC position estimate except in a few subject-method combinations. CONCLUSIONS: MIMU-based functional methods can be used to estimate the GHJC position in vivo with errors of the same order of magnitude than those obtained using traditionally stereo-photogrammetric techniques. The methodology proposed seemed to be robust under different experimental conditions. The present paper was awarded as "SIAMOC Best Methodological Paper 2016".

Ultrasound assessment of the posterior circumflex humeral artery in elite volleyball players: Aneurysm prevalence, anatomy, branching pattern and vessel characteristics.

OBJECTIVES: To determine the prevalence of posterior circumflex humeral artery (PCHA) aneurysms and vessel characteristics of the PCHA and deep brachial artery (DBA) in elite volleyball players. METHODS: Two-hundred and eighty players underwent standardized ultrasound assessment of the dominant arm by a vascular technologist. Assessment included determination of PCHA aneurysms (defined as segmental vessel dilatation ≥150 %), PCHA and DBA anatomy, branching pattern, vessel course and diameter. RESULTS: The PCHA and DBA were identified in 100 % and 93 % (260/280) of cases, respectively. The prevalence of PCHA aneurysms was 4.6 % (13/280). All aneurysms were detected in proximal PCHA originating from the axillary artery (AA). The PCHA originated from the AA in 81 % of cases (228/280), and showed a curved course dorsally towards the humeral head in 93 % (211/228). The DBA originated from the AA in 73 % of cases (190/260), and showed a straight course parallel to the AA in 93 % (177/190). CONCLUSIONS: PCHA aneurysm prevalence in elite volleyball players is high and associated with a specific branching type: a PCHA that originates from the axillary artery. Radiologists should have a high index of suspicion for this vascular overuse injury. For the first time vessel characteristics and reference values are described to facilitate ultrasound assessment. KEY POINTS: • Prevalence of PCHA aneurysms is 4.6 % among elite volleyball players. • All aneurysms are in proximal PCHA that originates directly from AA. • Vessel characteristics and reference values are described to facilitate US assessment. • Mean PCHA and DBA diameters can be used as reference values. • Radiologists need a high index of suspicion for this vascular overuse injury.

The utility of bone scintigraphy in the assessment of mandibular metabolism during long-term bisphosphonate administration.

The duration of antiresorptive therapy is an important risk factor for medication-related osteonecrosis of the jaw. We performed a pilot study using quantitative analysis by bone scintigraphy to test the hypothesis that mandibular metabolism is affected by long-term bisphosphonate (BP) therapy. Our primary objectives were to assess changes in bone metabolism of the mandible in response to long-term BP therapy and compare the bone metabolism changes of the mandible with other bone sites. We compared the metabolic difference at the site in the mandible unaffected by disease, the humerus and the femur between 14 osteoporosis patients who were being treated with BP (BP group) and 14 patients who were not being treated with BP (control group) using a quantitative analysis and bone scintigraphy. Study endpoints were the mean and maximum bone uptake values (BUVs) quantified using bone scintigraphy images of the mandible, humerus and femur. Quantified images of the site in the mandible unaffected by disease had significantly higher mean and maximum BUVs compared to the controls (mean, 0.74 vs. 0.49, p = 0.019; max., 1.29 vs. 0.85, p = 0.009, respectively). The mean and maximum BUV of femur ROIs in the BP group were significantly lower than those in control patients (mean BUV, 0.23 vs. 0.30, p = 0.039; max. BUV, 0.43 vs. 0.53, p = 0.024, respectively). This is the first report of mandible changes in response to long-term BP treatment, using bone scintigraphy. The results using bone scintigraphy demonstrated that the bone metabolism of the intact mandible is affected by a long-term administration of BP.