Combined Feedback Feedforward Control of a 3-Link Musculoskeletal System Based on the Iterative Training Method.

The investigation and study of the limbs, especially the human arm, have inspired a wide range of humanoid robots, such as movement and muscle redundancy, as a human motor system. One of the main issues related to musculoskeletal systems is the joint redundancy that causes no unique answer for each angle in return for an arm's end effector's arbitrary trajectory. As a result, there are many architectures like the torques applied to the joints. In this study, an iterative learning controller was applied to control the 3-link musculoskeletal system's motion with 6 muscles. In this controller, the robot's task space was assumed as the feedforward of the controller and muscle space as the controller feedback. In both task and muscle spaces, some noises cause the system to be unstable, so a forgetting factor was used to a convergence task space output in the neighborhood of the desired trajectories. The results show that the controller performance has improved gradually by iterating the learning steps, and the error rate has decreased so that the trajectory passed by the end effector has practically matched the desired trajectory after 1000 iterations.

A Matlab toolbox for scaled-generic modeling of shoulder and elbow.

There still remains a barrier ahead of widespread clinical applications of upper extremity musculoskeletal models. This study is a step toward lifting this barrier for a shoulder musculoskeletal model by enhancing its realism and facilitating its applications. To this end, two main improvements are considered. First, the elbow and the muscle groups spanning the elbow are included in the model. Second, scaling routines are developed that scale model's bone segment inertial properties, skeletal morphologies, and muscles architectures according to a specific subject. The model is also presented as a Matlab toolbox with a graphical user interface to exempt its users from further programming. We evaluated effects of anthropometric parameters, including subject's gender, height, weight, glenoid inclination, and degenerations of rotator cuff muscles on the glenohumeral joint reaction force (JRF) predictions. An arm abduction motion in the scapula plane is simulated while each of the parameters is independently varied. The results indeed illustrate the effect of anthropometric parameters and provide JRF predictions with less than 13% difference compared to in vivo studies. The developed Matlab toolbox could be populated with pre/post operative patients of total shoulder arthroplasty to answer clinical questions regarding treatments of glenohumeral joint osteoarthritis.

Relationship between the Branching Patterns of the Radial Nerve and Supinator Muscle.

The posterior interosseous nerve (PIN) innervates the posterior compartment muscle of the forearm and is a continuation of the deep branch of the radial nerve. The anatomic descriptions of PIN vary among different authors. This study investigated the distribution patterns of PIN and its relationships to the supinator muscle. This study investigated which nerves innervate the posterior compartment muscles of the forearm, the radial nerve, and the PIN, using 28 nonembalmed limbs. Also, the points where the muscle attaches to the bone were investigated. The measured variables in this study were measured from the most prominent point of the lateral epicondyle of the humerus (LEH) to the most distal point of the radius styloid process. For each specimen, the distance between the above two points was assumed to be 100%. The measurement variables were the attachment area of the supinator and branching points from the radial nerve. The attachment points of the supinator to the radius and ulna were 47.9% ± 3.6% and 31.5% ± 5.2%, respectively, from the LEH. In 67.9% of the specimens, the brachioradialis and extensor carpi radialis longus (ECRL) were innervated by the radial nerve before superficial nerve branching, and the extensor carpi radialis brevis (ECRB) innervated the deep branch of the radial nerve. In 21.4% of the limbs, the nerve innervating the ECRB branched at the same point as the superficial branch of the radial nerve, whereas it branched from the radial nerve in 7.1% of the limbs. In 3.6% of the limbs, the deep branch of the radial nerve branched to innervate the ECRL. PIN was identified as a large branch without divisions in 10.7% and as a deep branch innervating the extensor digitorum in 14.3% of the limbs. The anatomic findings of this study would aid in the diagnosis of PIN syndromes.

Estudio morfométrico del radio proximal en una población chilena / Morphometric study of the proximal radius in a Chilean population

RESUMEN: El objetivo de esta investigación fue determinar la morfometría del extremo proximal del radio, mediante mediciones efectuadas en la cabeza, cuello y tuberosidad del radio, en una población chilena y compararlas según sexo. Se efectuó un estudio transversal analizando exámenes de Tomografía Computarizada (TC) de codo, realizados entre enero de 2014 y diciembre de 2018. Se incluyó 32 TC, correspondientes a 16 hombres y 16 mujeres. Se transfirió las imágenes formateadas al software RadiAnt, para efectuar las mediciones en el radio proximal. El análisis estadístico de los resultados se realizó mediante el software SPSS 22. El diámetro de la cabeza del radio en hombres osciló entre 22,8±1,3 y 25,0±1,7 mm; en mujeres osciló entre 19,4±1,4 y 20,7±1,4 mm. El diámetro del cuello del radio proximal en hombres osciló entre 14,0±0,8 y 15,6±0,7 mm; en mujeres osciló entre 11,7±0,8 y 13,3±1,3 mm. El diámetro del cuello del radio distal en hombres osciló entre 14,4±1,0 y 16,0±1,2 mm; en mujeres osciló entre 12,5±1,0 y 13,8±1,5 mm. El diámetro de la tuberosidad radial en hombres osciló entre 15,1±1,5 y 17,7±1,8 mm; en mujeres osciló entre 13,2±1,1 y 15,5±1,8 mm. El promedio de altura de la cabeza del radio fue de 11,2±1,2 mm en hombres y de 9,5+0,8 mm en mujeres. El análisis comparativo entre sexos mostró diferencias estadísticamente significativas en todas las mediciones precedentes. El promedio de altura del cuello del radio fue de 11,2±1,2 mm en hombres y 10,1±1,6 mm en mujeres, sin diferencia significativa (p= 0,15). Los valores promedios de la morfometría del radio proximal de la población chilena difieren de los descritos para la población europea y presentan algunas similitudes con la población china. Nuestros resultados pueden ser de utilidad para el diseño de implantes y prótesis para el extremo proximal del radio y para una correcta planificación quirúrgica en ortopedia y traumatología.

SUMMARY: The aim of this research was to determine the morphometry of the proximal radius in a Chilean population, by means of measurements made in head of radius, neck of radius and radial tuberosity, and to compare them according to sex. A cross-sectional study was conducted analyzing Computed Tomography scans (CT) of elbows, performed between January 2014 and December 2018. Thirty-two CT corresponding to 16 men and 16 women were included. The formatted images were transferred to the RadiAnt software in order to perform measurements in the proximal radius. The statistical analysis of the results was performed using the SPSS 22 software. The diameter of the head of radius in men ranged between 22.8±1.3 and 25.0±1.7 mm; in women it ranged between 19.4±1.4 and 20.7±1.4 mm. The diameter of the proximal neck of radius in men ranged between 14.0±0.8 and 15.6±0.7 mm; in women, it ranged between 11.7±0.8 and 13.3±1.3 mm. The diameter of the distal neck of radius in men ranged between 14.4±1.0 and 16.0±1.2 mm; in women, it ranged between 12.5±1.0 and 13.8±1.5 mm. The diameter of radial tuberosty in men ranged between 15.1±1.5 and 17.7±1.8 mm; in women, it ranged between 13.2±1.1 and 15.5±1.8 mm. The mean height of the head of radius was 11.2±1.2 mm in men and 9.5±0.8 mm in women. Statistically significant sex differences were revealed in all the preceding measurements. The mean height of the neck of radius was 11.2±1.2 mm in men and 10.1±1.6 mm in women, with no significant difference (p= 0.15). The average values of morphometry of the proximal radius of the Chilean population differ from those describing the European population, and show some similarities with the Chinese population. Our results may be useful to design of implants and prostheses for the proximal radius, and to correct surgical planning in orthopedics and traumatology.

The origin structure of each finger in the flexor digitorum superficialis muscle.

PURPOSE: The flexor digitorum superficialis muscle (FDS) is considered the most important of the forearm flexors for maintaining elbow valgus stability. However, the relationships between the origin structure of each finger of the FDS and the anterior oblique ligament (AOL) of the ulnar collateral ligament and the common tendon (CT) in the proximal part, and morphological features are unclear. The purpose of this study was to clarify the relationships between the origin structure of each finger of the FDS and the AOL and the CT, as well as to clarify the morphological features of the muscle belly of each finger of the FDS. METHODS: This study examined 20 elbows. The origin of each finger was examined. Muscle mass, muscle fiber bundle length, and the pennation angle of each finger were also measured. RESULTS: In all cases, the third and fourth digits originated from the radius, the anterior common tendon (ACT), and the posterior common tendon (PCT). The second and fifth digits (18 elbows) or an independent fifth digit (2 elbows) originated from the ACT, the PCT, the AOL, and other soft tissues of the elbow. Muscle mass and muscle fiber bundle length in the muscle belly of the third and fourth digits were significantly heavier and longer, respectively, than in the muscle belly of the second and fifth digits. CONCLUSION: Because the second and fifth digits or an independent fifth digit originated from the AOL, their contraction may cause tension in the AOL.

Comorbidities, anthropometric, demographic, and lifestyle risk factors for ulnar neuropathy at the elbow: A case control study.

We performed a prospective multicenter case-control study to explore the association between ulnar neuropathy at elbow (UNE) and body and elbow anthropometric measures, demographic and lifestyle factors, and comorbidities. Cases and controls were consecutively enrolled among subjects admitted to four electromyography labs. UNE diagnosis was made on clinical and neurographic findings. The control group included all other subjects without signs/symptoms of ulnar neuropathy and with normal ulnar nerve neurography. Anthropometric measurements included weight, height, waist, hip circumferences, and external measures of elbow using a caliper. The participants filled in a self-administered questionnaire on personal characteristics, lifestyle factors, and medical history. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) by fitting unconditional logistic regression models adjusted by center and education level. We enrolled 220 cases (males 61.8%; mean age 51.7 years) and 460 controls (47.4% males; mean age 47.8 years). At multivariable analysis, UNE was associated to male gender (OR = 2.4, 95%CI = 1.6-3.7), smoking habits (>25 pack-years (OR = 2.3, 95%CI = 1.3-4.1), body mass index (OR = 1.05, 95%CI 1.01-1.10), polyneuropathies (OR = 4.1, 95%CI 1.5-11.5), and leaning with flexed elbow on a table/desk (OR = 1.5, 95%CI 1.0-2.2). Cubital groove width (CGW) turned out to be negatively associated with UNE (OR = 0.80, 95%CI = 0.74-0.85). Our study suggests that some personal factors especially anthropometric measures of the elbow may play a role in UNE pathogenesis as the measures of wrist in CTS. We demonstrated that for each millimeter of smaller CGW the risk of idiopathic UNE increases of 25%.

Sarcomas de partes blandas en la región del codo e influencia de sus particularidades anatómicas en su tratamiento. Experiencia en una Unidad de Tumores musculoesqueléticos / Soft tissue sarcomas in the elbow region and influence of their anatomical features in their treatment. Experience in the Unit of Musculoskeletal Tumours

ANTECEDENTES Y OBJETIVO: Los sarcomas de partes blandas se localizan excepcionalmente en la región del codo. El objetivo de este trabajo fue estudiar los sarcomas de partes blandas de la región del codo, sus características epidemiológicas e histopatológicas, particularidades anatómicas, tratamiento realizado y resultados obtenidos, en una Unidad de Tumores Musculoesqueléticos. MATERIALES Y MÉTODOS: Revisión retrospectiva de 10 pacientes con un seguimiento de 65,0 ± 11,9 (rango 21-132) meses con sarcoma de partes blandas situado en la región del codo, intervenidos en nuestro centro entre los años 2008 y 2016. RESULTADOS: La edad media fue de 60,8 ± 6,7 años. La histología más frecuente fue sarcoma pleomórfico indiferenciado. El 90% de los pacientes fueron sometidos a cirugía de preservación de extremidad. Tres pacientes fueron previamente intervenidos sin criterios oncológicos en otro centro, y esto se relacionó de forma estadísticamente significativa con requerir más de una cirugía para el control de la enfermedad. En cinco pacientes se obtuvo un margen R1 y en cinco R0. La radioterapia adyuvante se utilizó en siete casos. En cuatro pacientes se realizó cirugía posterior para control local o sistémico de la enfermedad. En tres casos se produjo recidiva local y en cinco se presentó enfermedad a distancia. CONCLUSIONES: La región del codo presenta dificultad para lograr márgenes amplios por la proximidad de estructuras neurovasculares, por lo que las terapias adyuvantes, neoadyuvantes (o ambas) podrían tener un papel importante para poder realizar una cirugía de preservación de la extremidad. Sería recomendable remitir estos tumores a unidades especializadas con equipos multidisciplinarios

BACKGROUND AND AIM: Soft tissue sarcomas are exceptionally located in the elbow region. The aim of this work was to study the soft tissue sarcomas of the elbow region, their epidemiological and histopathological characteristics, anatomical features, the treatment performed, and the results obtained, in a unit of musculoskeletal tumours. METHODS: Retrospective review of ten patients with a mean follow-up of 65.0 ± 11.9 (range 21-132) months with soft tissue sarcomas located in the elbow region operated in our centre between 2008 and 2016. RESULTS: Mean age was 60.8 ± 6.7 years. Undifferentiated pleomorphic sarcoma was the most frequent histological diagnosis. Limb preservation surgery was performed in 90% of patients. Three patients were previously operated without following surgical oncology guidelines in another hospital, and this was statistically related to the need for more than one surgery to control the disease. R1 margin was obtained in 5 patients and R0 in another 5. Adjuvant radiotherapy was used in 7 cases. In 4 patients, subsequent surgery was performed for local or systemic control of the disease. Local recurrence occurred in 3 cases and in 5 there was distant disease. CONCLUSION: The elbow region presents difficulty in achieving wide margins due to the proximity of neurovascular structures, adjuvant and / or neoadjuvant therapies could play an important role in performing limb preservation surgery. It would be advisable to refer these tumours to specialized units with multidisciplinary teams

Rama muscular hipertrófica de la arteria recurrente radial (Cuerda de Henry) en relación con el ramo profundo del nervio radial: reporte de caso / Hypertrophic muscular branch of radial recurrent artery (Leash of Henry), in relation to the deep branch of radial nerve: case report

La arteria recurrente radial nace en el extremo proximal de la arteria radial y desde ahí asciende oblicuamente para anastomosarse con la arteria colateral radial, entregando en ese trayecto una serie de ramas para los músculos cercanos. Dicha arteria junto con sus ramas fueron descritas (por su importancia en abordajes quirúrgicos) por Arnold K. Henry como "the radial leash". Actualmente en clínica se utiliza el nombre "leash of Henry" para referirse a una o más ramas musculares de la arteria recurrente radial, sobretodo cuando cuando se encuentran en relación con el ramo profundo del nervio radial, pudiendo llegar a causar compresiones de dicho nervio en algunos casos. Se realizó una descripción de caso de una leash of Henry atípica, encontrada en una muestra cadavérica del laboratorio de anatomía de la Universidad Católica del Maule, de sexo masculino y nacionalidad chilena. La arteria encontrada corresponde a la rama de mayor calibre de la arteria recurrente radial, que se dirige directamente al músculo extensor de los dedos, dibujando un trayecto horizontal y cruzando por anterior al ramo profundo del nervio radial. Esta hallazgo difere a lo descrito por Henry y otros autores más recientes, y por lo tanto aporta información potencialmente útil a la hora de realizar procedimientos quirúrgicos que requieran un abordaje posterior o lateral de la cabeza del radio, como también descompresiones del nervio radial en esta zona.

The radial recurrent artery originates at the proximal end of the radial artery and from there ascends obliquely to anastomosing with the radial collateral artery. It gives off several branches for nearby muscles on its path. This artery along with its branches were described (due to its importance in surgical approaches) by Arnold K. Henry as "the radial leash". Currently, in clinical terms, the name "Leash of Henry" is used to refer to one or more muscular branches of the radial recurrent artery, especially when they are in relation to the deep branch of the radial nerve, and may cause compression of the nerve in some cases. A case description of an atypical Leash of Henry was found, found in a Chilean, male cadaveric sample of the anatomy laboratory, Universidad Católica del Maule. The artery corresponds to the branch of greater caliber of the recurrent radial artery, which goes directly to the extensor digitorum muscle. It draws a horizontal path and crosses the deep branch of the radial nerve anteriorly. This finding differs from what was described by Henry and other more recent authors. Therefore, this is potentially useful information when performing surgical procedures that require a posterior or lateral approach to the radius head, as well as radial nerve decompressions in this area.

Injuries and Conditions Affecting the Elbow Flexor/Pronator Tendons.

Common flexor-pronator tendon injuries and medial epicondylitis can be successfully treated nonoperatively in most cases. Operative treatment is reserved for patients with continued symptoms despite adequate nonoperative treatment or in high-level athletes with complete rupture of the common flexor-pronator tendon. The physical examination and workup of patients with flexor-pronator tendon injuries should focus on related or concomitant pathologies of the medial elbow. The gold standard for surgical treatment of flexor-pronator tendon ruptures or medial epicondylitis includes tendon debridement and reattachment.

Distal biceps tendon insertional trifurcation and a new footprint configuration: Case report of an anatomical variant

Distal biceps tendon (DBT) insertion on the elbow bicipital tuberosity is usually bifurcated into distinct long and short head components, and oc-casionally the tendon may insert as a single unit. A previously undescribed trifurcate insertion of the DBT was observed during anatomical dissections; this new anatomical finding involved 3 distinct divisions of the distal biceps: (1) a distal short head insertion, (2) a proximal long head insertion, and (3) an extra / accessory head that bifurcated from the long head and inserted with an anterior and radial footprint. Recognition of this variant is necessary, as DBT insertional trifurcation may alter radiological interpretation of imaging scans and may obscure endoscopic visualization of the insertional area during diagnostic endoscopy

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Distal insertional anatomy of the triceps brachii muscle: MRI assessment in cadaveric specimens employing histologic correlation and Play-doh® models of the anatomic findings.

OBJECTIVES: Assess the insertional anatomy of the distal aspect of the triceps brachii muscle using magnetic resonance imaging (MRI) in cadavers with histologic correlation and Play-doh® models of the anatomic findings. MATERIALS: Elbows were obtained from twelve cadaveric arm specimens by transverse sectioning through the proximal portion of the humerus and the midportion of the radius and ulna. MRI was performed in all elbows. Two of the elbow specimens were then dissected while ten were studied histologically. Subsequently, Play-doh® models of the anatomic findings of the distal attachment sites of the triceps brachii muscle were prepared. RESULTS: MRI showed a dual partitioned appearance of the distal attachment sites into the olecranon in all specimens. In the deeper tissue planes, the medial head muscle insertion was clearly identified while superficially, the terminal portion of the long and lateral heads appeared as a conjoined tendon. Histologic analysis, however, showed continuous tissue rather than separate structures attaching to the olecranon. CONCLUSION: Although MRI appeared to reveal separate and distinct attachments of the triceps brachii muscle into the olecranon, histologic analysis delineated complex but continuous tissue related to the attachments of the three heads of this muscle. The Play-doh® models were helpful for the comprehension of this complex anatomy and might serve as a valuable educational tool when applied to the analysis of other musculoskeletal regions.

The external elbow measure as surrogate of the anatomical width of cubital groove and possible risk factor of ulnar neuropathy at the elbow.

Introduction: There are no studies on elbow anthropometry in ulnar neuropathy at the elbow (UNE). We aimed to test the interrater agreement of external elbow measurements with caliper, the matching of external width of cubital groove (WCG) measures with those obtained through conventional radiography (XR) and ultrasonography (US). The final aim was to evaluate the differences of anthropometric elbow and body measures between UNE cases and controls with multicenter prospective study.Materials and methods: After common training of five observers for external elbow and body anthropometric measurements, we assessed the interrater agreement of measures in a single blind measurement session in 16 healthy volunteers. Then we verified if external WCG measures in eight and four of the above 16 subjects matched with those obtained with US and XR. Finally, we enrolled 40 consecutive idiopathic UNE cases in four electromyographic labs matched for sex and age with 40 controls to evaluate the differences of anthropometric measures.Results: There was high interrater agreement of all anthropometric body and elbow measures (Kendal's and interclass correlation coefficients between 0.84 and >0.9). We found high relations between WCG caliper measures and those obtained with US and XR (r > 0.9). WCG was smaller in cases than in controls (13.2 vs.15.7 mm, p < 0.001). There were no differences in body anthropometric measures (BMI and waist-to-hip ratio).Conclusion: The external measurement of WCG is reliable and reproducible and may be risk factor of UNE. Future studies should be performed in lager samples evaluating the relations with lifestyle and occupational factors.

Acoustic Shadow Detection: Study and Statistics of B-Mode and Radiofrequency Data.

An acoustic shadow is an ultrasound artifact occurring at boundaries between significantly different tissue impedances, resulting in signal loss and a dark appearance. Shadow detection is important as shadows can identify anatomical features or obscure regions of interest. A study was performed to scan human participants (N = 37) specifically to explore the statistical characteristics of various shadows from different anatomy and with different transducers. Differences in shadow statistics were observed and used for shadow detection algorithms with a fitted Nakagami distribution on radiofrequency (RF) speckle or cumulative entropy on brightness-mode (B-mode) data. The fitted Nakagami parameter and entropy values in shadows were consistent across different transducers and anatomy. Both algorithms utilized adaptive thresholding, needing only the transducer pulse length as an input parameter for easy utilization by different operators or equipment. Mean Dice coefficients (± standard deviation) of 0.90 ± 0.07 and 0.87 ± 0.08 were obtained for the RF and B-mode algorithms, which is within the range of manual annotators. The high accuracy in different imaging scenarios indicates that the shadows can be detected with high versatility and without expert configuration. The understanding of shadow statistics can be used for more specialized techniques to be developed for specific applications in the future, including pre-processing for machine learning and automatic interpretation.

The usefulness of ultrasound and the posterior fat pad sign in pulled elbow.

INTRODUCTION: A pulled elbow is a common cause of acute elbow pain that is generally managed by a reduction maneuver without radiographic examination. However, children with atypical presentation with no history of abrupt longitudinal traction should undergo elbow imaging. This study aimed to investigate plain radiography findings and determine the usefulness of ultrasonography (US) in atypical pulled elbow. MATERIALS AND METHODS: We retrospectively reviewed the medical records and images of 37 (22 males) consecutive patients with pulled elbow who presented with an atypical history or failed reduction between April 2015 and September 2018. Mean age at presentation was 4.34 years (range, 1.25-9.5 years). Of the 37 elbows, 20 were left elbows. The injury mechanism, incidence of the posterior fat pad sign on plain radiographs, and characteristic US findings, pre- and post- reduction, were investigated. RESULTS: The original mechanisms of injury included slipping (n = 14), rolling over the arm (n = 7), vague history (n = 6), falling down (n = 6), abrupt longitudinal traction (n = 2), and direct injury (n = 2). On plain radiographs, six of the 37 elbows (16%) showed the posterior fat pad sign. Before the reduction, an entrapped supinator, a pathognomonic sign of pulled elbow, was identified on US in all cases. After reduction, the characteristic US findings showed a disentangled and swollen supinator (100%) and restored annular ligament (100%) in all successful cases. Although a click was not felt in three cases, the reductions were considered successful because the annular ligament was restored on US with free elbow motion. CONCLUSION: Pulled elbow may be caused by atypical mechanisms of injury, such as slipping and rolling over the arm. Clinicians should be aware of the possibility of the posterior fat pad sign on plain radiographs of pulled elbow to prevent unnecessary immobilization. In such circumstances, US is a useful method for detecting an entrapped supinator and confirming adequate reduction via restoration of the annular ligament in children with atypical pulled elbow.

A single simple position for ultrasound assessment of both common extensor and common flexor origin at the elbow.

OBJECTIVE: Is to evaluate the simplicity of 90° flexion/neutral position for ultrasonography assessment of both common extensor and common flexor origins in comparison with the standard position. MATERIAL AND METHODS: A standard questionnaire was distributed on 50 trainees, rheumatologists with No previous experience or training in ultrasonography. (They) were attending musculoskeletal training workshops at AL-Azhar rheumatology department musculoskeletal ultrasonography unit in 2016. Each participant then (was) asked to practice US examination of both common extensor and common flexor origins in both positions and then fill four questionnaires, two (of which are) for common flexor and (the other) two (are) for the common extensor origins, in the standard and the other proposed single position. Each questionnaire (whose) answer was graded on scale from 0 to 10, includes the following points: • Time needed to examine the tendon in minutes, • Difficulty in maintaining the probe contact to the skin, • Difficulty in getting good image of the tendon, • The overall impression of simplicity. RESULTS: Descriptive analysis of the questionnaire results shows that the participants favors the single position in all questionnaire parameters. Comparing means of the four questionnaire parameters in both positions shows highly significant difference in the four parameters at the level of both common flexor and extensor origins in favor of the single position as p > 0.005. CONCLUSION: The 90 degree flexion/neutral position appears to be simpler than the standard position for ultrasonography assessment of common extensor and common flexor tendons at the elbow.

Variations in Blood Supply From Proximal to Distal in the Ulnar Collateral Ligament of the Elbow: A Qualitative Descriptive Cadaveric Study.

BACKGROUND: The vascular supply of the ulnar collateral ligament (UCL) is unknown. Previous studies reported varying success in return-to-play rates after nonoperative management of partial UCL tears and suggested a varying healing capacity as possibly related to the location of the UCL injury. PURPOSE: To analyze the macroscopic vascular anatomy of the UCL of the elbow. STUDY DESIGN: Descriptive laboratory study. METHODS: Eighteen fresh-frozen male cadaveric elbows from 9 donors were sharply dissected 15 cm proximal to the medial epicondyle. Sixty milliliters of India ink was injected through the brachial artery of each elbow. Arms were then frozen at -10°C, radial side down, in 15° to 20° of elbow flexion. A band saw was used to section the frozen elbows into 5-mm coronal or sagittal sections. Sections were cleared for visualization with the modified Spalteholz technique. Images of the specimens were taken, and qualitative description of UCL vascularity was undertaken. RESULTS: The authors consistently found a dense blood supply to the proximal UCL, while the distal UCL was hypovascular. They also observed a possible osseous contribution to the proximal UCL from the medial epicondyle in addition to an artery from the flexor/pronator musculature that consistently appeared to provide vascularity to the proximal UCL. The degree of vascular penetration from proximal to distal in the UCL ranged from 39% to 68% of the overall UCL length, with a 49% mean length of vascular penetration of the UCL. CONCLUSION: This study found a difference in the vascular supply of the UCL. The proximal UCL was well vascularized, while the distal UCL was hypovascular. This difference in vascular supply may be a factor in the differential healing capacities of the UCL based on the location of injury. CLINICAL RELEVANCE: An improved understanding of the macroscopic vascular supply of the UCL may aid in the clinical management of partial UCL tears and suggests an indication for these treatments with respect to location of UCL injuries.

Imaging appearance following surgical decompression of the ulnar nerve.

Ulnar neuropathy at the elbow is the second most common entrapment neuropathy of the upper extremity. Yet, there is a paucity of literature focusing on the imaging appearance following surgical decompression of the ulnar nerve at the elbow. Diagnostic imaging studies obtained after surgical decompression at The University of Michigan were reviewed and imaging findings were documented. We aim to describe the various techniques of ulnar nerve decompression and corresponding post-operative appearance on imaging. Potential complications following decompression will also be described with imaging and clinical correlation of recalcitrant ulnar neuropathy. It is important for the radiologist who performs MRI or ultrasound of the elbow to be aware of the various ulnar nerve decompression procedures. This knowledge will facilitate rapid and accurate diagnosis of normal and abnormal appearance of the ulnar nerve in this context.

The 7 Structures Distal to the Elbow That Are Critical to Successful Anterior Transposition of the Ulnar Nerve.

Background: Ulnar nerve transposition (UNT) surgery is performed for the treatment of cubital tunnel syndrome. Improperly performed UNT can create iatrogenic pain and neuropathy. The aim of this study is to identify anatomical structures distal to the medial epicondyle that should be recognized by all surgeons performing UNT to prevent postoperative neuropathy. Methods: Ten cadaveric specimens were dissected with attention to the ulnar nerve. Intramuscular UNT surgery was simulated in each. Distal to the medial epicondyle, any anatomical structure prohibiting transposition of the ulnar nerve to a straight-line course across the flexor-pronator mass was noted and its distance from the medial epicondyle was measured. Results: Seven structures were found distal to the medial epicondyle whose recognition is critical to ensuring a successful anterior transposition of the ulnar nerve: (1) Branches of the medial antebrachial cutaneous (MABC) nerve; (2) Osborne's fascia; (3) branches from the ulnar nerve to the flexor carpi ulnaris (FCU); (4) crossing vascular branches from the ulnar artery to the FCU; (5) the distal medial intermuscular septum between the FCU and flexor digitorum superficialis (FDS); (6) the combined muscular origins of the flexor-pronator muscles; and (7) the investing fascia of the FDS. Measurements are given for each structure. Conclusions: Poor outcomes and unnecessary revision surgeries for cubital tunnel syndrome can be avoided with intraoperative attention to 7 structures distal to the medial epicondyle. Surgeons should expect to dissect up to 12 cm distal to the medial epicondyle to adequately address these and prevent kinking of the nerve in transposition.

Correlation between the length from the elbow to the distal interphalangeal joint of the little finger and the length of the intramedullary nail selected for femoral fracture fixation.

AIM: To determine whether there is a correlation between the length of forearm to the distal interphalangeal joint (DIPJ) of the little finger and length of antegrade intramedullary (IM) femoral nails in adults. STUDY DESIGN AND METHODS: Measurements from the tip of the olecranon to the DIPJ of the ipsilateral upper limb was taken in 30 patients undergoing antegrade IM femoral nails. The length of the IM nails inserted was determined by intra-operative measurements using a guide wire. The two measurements were analysed for correlation and mean difference. RESULTS: The mean forearm to DIP of little finger length was 38.86 with a standard deviation of 2.83. The mean IM length and standard deviation were 38.56 and 2.77 respectively. The difference between the two means 0.3 (95% CI). Correlation testing between the two variables shows a positive relationship (Pearson Correlation factor of 1). The scatter plot shows a positive linear relationship. CONCLUSIONS: Length of the forearm from the tip of the olecranon to the DIP joint of the little finger represents the ideal length of IM nail for the femur. It can be readily performed with the use of a tape measure and can serve as a useful adjunct to determining ideal length in cases where the contralateral femur cannot be used.