A bilateral four-headed brachialis muscle with a variant innervation: a cadaveric report with possible clinical implications.

PURPOSE: Anterior compartment muscles of the arm present high morphological variability, with possible clinical significance. The current cadaveric report aims to describe a bilateral four-headed brachialis muscle (BM) with aberrant innervation. Emphasis on the embryological background and possible clinical significance are also provided. METHODS: Classical upper limb dissection was performed on an 84-year-old donated male cadaver. The cadaver was donated to the Anatomy Department of the National and Kapodistrian University of Athens. RESULTS: On the left upper limb, the four-headed BM was supplied by the musculocutaneous and the median nerves after their interconnection. On the right upper limb, the four-headed BM received its innervation from the median nerve due to the musculocutaneous nerve absence. A bilateral muscular tunnel for the radial nerve passage was identified, between the BM accessory heads and the brachioradialis muscle. CONCLUSION: BM has clinical significance, due to its proximity to important neurovascular structures and frequent surgeries at the humerus. Hence, knowledge of these variants should keep orthopedic surgeons alert when intervening in this area. Further dissection studies with a standardized protocol are needed to elucidate the prevalence of BM aberrations and concomitant variants.

Demystifying the Radial Nerve The Management of Radial Nerve Palsy in the Setting of Humeral Shaft Fracture.

The association of radial nerve palsy and humeral shaft fracture is well known. Primary exploration and fracture fixation is recommended for open fractures and vascular injury while expectant management remains the standard of care for closed injuries. In the absence of nerve recovery, exploration and reconstruction is recommended 3 to 5 months following injury. When direct repair or nerve grafting is unlikely to achieve a suitable outcome, nerve and tendon transfers are potential options for the restoration of wrist and finger extension.

The Accessory Muscular Head of the Triceps Brachii Muscle with Tendinous Attachment / Cabeza Muscular Accesoria del Músculo Triceps Braquial con Inserción Tendinosa

SUMMARY: Variations in the triceps brachii muscle are uncommon, and especially limited reports exist on the accessory heads of tendinous origin that attach near the upper medial part of the humerus. During anatomical training at Nagasaki University School of Medicine, the accessory head of the triceps brachii muscle was observed on the right upper arm of a 72-year-old Japanese female. It arose tendinously from the medial side of the upper humerus, then formed a muscle belly and joined the distal side of the long head. This accessory head had independent nerve innervation, and the innervating nerve branched from a bundle of the radial nerve, which divided the nerve innervating the long head and the posterior brachial cutaneous nerve. The origin of the innervation of the accessory head was the basis for determining that this muscle head was an accessory muscle to the long head of the triceps brachii muscle. Embryologically, we discuss that part of the origin of the long head of the triceps brachii muscle was separated early in development by the axillary nerve and the posterior brachial circumflex artery, and it slipped into the surgical neck of the humerus and became fixed there. The accessory head crossed the radial nerve and deep brachial artery. When clinicians encounter compression of the radial nerve or profunda brachii artery, they should consider the presence of accessory muscles as a possible cause.

Las variaciones en el músculo tríceps braquial son poco comunes y existen informes especialmente limitados sobre las cabezas accesorias de origen tendinoso que se insertan cerca de la parte medial superior del húmero. Durante un entrenamiento anatómico en la Facultad de Medicina de la Universidad de Nagasaki, se observó la cabeza accesoria del músculo tríceps braquial en la parte superior del brazo derecho de una mujer japonesa de 72 años. Se originaba tendinosamente desde el lado medial de la parte superior del húmero, luego formaba un vientre muscular y se unía al lado distal de la cabeza larga. Esta cabeza accesoria tenía inervación nerviosa independiente, cuyo nervio se ramificaba a partir de un ramo del nervio radial, que dividía el nervio que inervaba la cabeza larga y el nervio cutáneo braquial posterior. El origen de la inervación de la cabeza accesoria fue la base para determinar que esta cabeza muscular era un músculo accesorio de la cabeza larga del músculo tríceps braquial. Embriológicamente, discutimos que parte del origen de la cabeza larga del músculo tríceps braquial se separó temprananamente en el desarrollo por el nervio axilar y la arteria circunfleja braquial posterior, y se deslizó hacia el cuello quirúrgico del húmero y quedó fijado allí. La cabeza accesoria cruzaba el nervio radial y la arteria braquial profunda. Cuando los médicos encuentran compresión del nervio radial o de la arteria braquial profunda, deben considerar la presencia de mús- culos accesorios como una posible causa.

Clinical efficacy analysis of minimally invasive intramedullary nailing in the treatment of humeral shaft fractures combined with radial nerve injury.

OBJECTIVE: The aim of this study was to research the therapeutic effectiveness of radial nerve damage paired with a humeral shaft fracture and intramedullary nailing. PATIENTS AND METHODS: Retrospective research was performed on the medical records of 58 individuals who had humeral shaft fractures and radial nerve injuries. The admission period was between June 1, 2020, and June 31, 2022. All study subjects that satisfied the requirements for inclusion were separated, using the random number table approach, into two groups: one for internal fixation (group N), which included 29 cases, and one for minimally invasive procedures (group W), which included 29 patients. Group W received minimally invasive intramedullary nail treatment, and group N received internal fixation with compression plates. The changes in the clinical effects, surgery-related indicators, joint function, nerve function, and levels of stress indicators of the two groups of treatment were analyzed. The changes in adverse reactions and satisfaction of patients were compared. RESULTS: The effective rate of group W was 89.66% (26/29), and that of group N was 72.41% (21/29). Although group W's effective rate was higher than group N's, there was no discernible disparity between the two groups (p>0.05). Surgical blood loss and incision length were much smaller in group W than in group N, and overall operation duration and length of stay were considerably shorter in group W than in group N (p<0.05). The excellent and good rate of elbow joint function in group W was 93.10% (27/29), whereas the excellent and good rate of group N was 65.52% (19/29). The excellent and good rate of elbow joint function in group W was considerably greater than that of group N (p<0.05). In group W, the excellent and good rate of shoulder joint was 96.55% (28/29), and that in group N was 68.97% (20/29), and group W had a considerably greater probability of excellent shoulder joint function than group N (p<0.05); the excellent and good rate of neurological function was 82.76% (24/29) in group W and 58.62% (17/29) in group N, and group W had much greater rates of excellent and good neurological function than group N (p<0.05). prostaglandin E-2 (PGE2), C-reactive protein (CRP) and Substance P (SP) levels in the W group and the N group were substantially higher after the surgery than they were prior to it (p<0.05), and in the W group, the aforementioned stress markers were much lower than they were in the N group (p<0.05). Group W experienced a 3.45% (1/29) rate of adverse events, while group N saw a 24.14% (7/29) incidence. The incidence of adverse responses was substantially lower in group W than in group N (p<0.05). The contentment rate of group W was 93.10% (27/29), and that of group N was 72.41% (21/29). Group W had a much greater contentment percentage than group N (p<0.05). CONCLUSIONS: Minimally invasive intramedullary nailing is a successful therapeutic approach for humeral shaft fractures with radial nerve damage, which may successfully enhance patients' shoulder and elbow joint function and nerve function, reduce patients' stress response, and has the characteristics of minimal adverse responses and high contentment, which is worthy of popularization and deployment.

Rare Median Nerve and Digital Nerve Tumor Resection and Distal Nerve Transfers: A Report of 2 Cases.

CASES: We present 2 cases of median nerve reconstruction using distal nerve transfers after resection of unusual benign median nerve tumors. Critical sensation was restored in case 1 by transferring the fourth common digital nerve to first web digital nerves. Thumb opposition was regained by transferring the abductor digiti minimi ulnar motor nerve branch to the recurrent median motor nerve branch. Critical sensation was restored in case 2 by transferring the long finger ulnar digital nerve to the index finger radial digital nerve. CONCLUSION: Distal nerve transfers, even with short grafts, are reliable median nerve deficit treatments, sparing the need for larger autologous nerve grafts and late tendon opponensplasties.

Anatomical considerations for nerve transfer in axillary nerve injury.

This study investigated the anatomical details of the axillary and radial nerves in 50 upper limbs from 29 adult formalin-embalmed cadavers, and ten fresh upper limbs. The focus was on understanding the course, division, and ramifications of these nerves to improve treatment of shoulder dysfunction caused by axillary nerve damage. The axillary nerve divided anteriorly and posteriorly before passing the quadrangular space in all specimens, with specific distances to the first ramifications. It was found that the deltoid muscle's clavicular and acromial parts were always innervated by the anterior division of the axillary nerve, whereas the spinous part was variably innervated. The longest and thickest branches of the radial nerve to the triceps muscles were identified, with no statistically significant differences in fiber numbers among triceps branches. The study concludes that nerve transfer to the anterior division of the axillary nerve can restore the deltoid muscle in about 86% of shoulders, and the teres minor muscle can be restored by nerve transfer to the posterior division. The medial head branch and long head branch of radial nerve were identified as the best donor options.

Neuropathic pain of the superficial branch of the radial nerve - Factors influencing surgical outcome and patient satisfaction.

BACKGROUND: Due to its partially superficial course, the superficial branch of the radial nerve is vulnerable to injury by trauma or surgery, potentially leading to painful neuroma. Surgical treatment is difficult. Among other factors, smoking and duration of pain before revision surgery have been suggested as risk factors for persistent pain after surgical revision, without concrete evidence. The aim of this study was therefore to identify factors influencing the outcome of revision surgery in SBRN neuropathic pain in our department. METHODS: All 51 patients receiving revision surgery of the superficial branch of the radial nerve for neuropathic pain from 2010 to 2020 were contacted; 19 agreed to return for assessment. A medical chart review was performed to collect patient-, pain- and treatment-specific factors. Outcomes were recorded. In an outpatient consultation, clinical follow-up was performed and patients filled out the DASH, MHQ and painDETECT questionnaires. RESULTS: After revision surgery, all patients experienced persistent pain. On multivariate logistic regression evaluating the risk of persistent pain, only smoking emerged as an independent risk factor. Age, gender, dominant side, location, time between trigger and surgery or diagnosis did not emerge as risk factors. No predictor for successful return to work could be identified. CONCLUSIONS: Treatment of painful neuroma of the superficial branch of the radial nerve is a challenge. Patients with neuropathic pain should be coached toward smoking cessation before neuroma surgery. Surgery can show benefit even after long symptom duration. No correlations between study clinical variables or test results and return to work could be identified, suggesting that other factors play a role in return to work.

Anatomy of the Superficial Radial Nerve and Its Target Nerves for Targeted Muscle Reinnervation: An Anatomical Cadaver Study.

BACKGROUND: Targeted muscle reinnervation (TMR) is a surgical procedure for treating symptomatic neuroma, in which the neuroma is removed and the proximal nerve stump is coapted to a donor motor branch innervating a nearby muscle. This study aimed to identify optimal motor targets for TMR of the superficial radial nerve (SRN). METHODS: Seven cadaveric upper limbs were dissected to describe the course of the SRN in the forearm and motor nerve supply-number, length, diameter, and entry points in muscle of motor branches-for potential recipient muscles. RESULTS: The radial nerve provided three (three of six) motor branches, two (two of six) motor branches, or one (one of six) motor branch to the brachioradialis muscle, entering the muscle 21.7 ± 17.9 to 10.8 ± 15 mm proximal to the lateral epicondyle. One (one of seven), two (three of seven), three (two of seven), or four (one of seven) motor branches innervated the extensor carpi radialis longus muscle, with entry points 13.9 ± 16.2 to 26.3 ± 14.9 mm distal from the lateral epicondyle. In all specimens, the posterior interosseous nerve gave off one motor branch to the extensor carpi radialis brevis, which divided into two or three secondary branches. The distal anterior interosseus nerve was assessed as a potential recipient for TMR coaptation and had a freely transferable length of 56.4 ± 12.7 mm. CONCLUSIONS: When considering TMR for neuromas of the SRN in the distal third of the forearm and hand, the distal anterior interosseus nerve is a suitable donor target. For neuromas of the SRN in the proximal two-thirds of the forearm, the motor branches to the extensor carpi radialis longus, extensor carpi radialis brevis, and brachioradialis are potential donor targets.

Rehabilitation Following a Triceps Branch to Axillary Motor Nerve Transfer-A Pragmatic Therapy Guide.

Peripheral motor nerve transfer surgery is a technique that may be used to restore motor function to paralyzed muscles. Motor nerve transfer involves harvesting an expendable motor nerve branch, and transfer to the motor branch of the denervated target muscle, using microsurgical coaptation. To date, a standardized rehabilitation protocol does not exist. The 6 stages of rehabilitation after motor nerve transfer surgery were outlined by colleagues in the Birmingham Peripheral Nerve Injury service in 2019. This article aims to provide a practical therapy perspective on the rehabilitation stages of motor nerve transfer surgery outlined in that paper, focusing on the radial to axillary nerve transfer. Timeframes for each stage along with exercise prescription and rationale are provided.

Comparison of nerve versus tendon transfer for radial nerve palsy.

OBJECTIVE: This study aims to investigate the choice of intervention time and operation mode between nerve and tendon transfer for the treatment of radial nerve palsy (RNP). METHODS: 46 RNP patients underwent nerve transfer (n = 22) and tendon transfer (n = 24). The intraoperative blood loss, main incision length, operation duration, and length of hospital stay and follow-up period of patients in these two groups were recorded and compared. The range of motion (ROM) of the elbow, wrist, fingers, and thumb, the hand grip and pinch strength, the Disabilities of Arm, Shoulder, and Hand (DASH) and the 36-Item Short Form Health Survey (SF-36) scores were measured and compared preoperatively and postoperatively between the two groups. RESULTS: The ROM of thumb and the hand grip strength of patients in the nerve transfer group were greater than that in the tendon transfer (P < 0.05). Both of the two groups indicated significant improvements in the ROM of elbow, wrist, finger, thumb and the hand grip and pinch strength (P < 0.05) postoperatively. The DASH scores decreased significantly at 6 months (P < 0.05) and 12 months (P < 0.05) after surgery in both groups, while the postoperative SF-36 scores significantly increased (P < 0.05). There was no significant difference in postoperative DASH and SF-36 scores between the two groups (P > 0.05). CONCLUSION: In summary, both nerve and tendon transfer techniques are effective treatments for RNP. Nerve transfer is particularly advantageous for early RNP, while tendon transfer is suitable for patients with radial nerve injury more than one year.

Anterior transposition of the radial nerve to achieve primary suture for its reconstruction: Anatomical feasibility study.

INTRODUCTION: Radial nerve palsy after humeral shaft fractures is often associated with formation of a neuroma in continuity. The current standard of treatment is neuroma resection and nerve grafting with contentious results. Anterior transposition of the radial nerve may reduce the length of its path, allowing reconstruction by primary suture. The aim of this study was to determine the maximum length of radial nerve defect that can be treated by the anterior transposition to allow primary suture to be performed. METHODS: We use 10 arms from five fresh cadavers. The radial nerve was dissected in the lateral inter-muscular septum and along the anterior aspect of the forearm. The radial nerve was transected at the level of the spiral groove and both stumps were than transposed anterior to the medial inter-muscular septum. The length of tension-free overlap that could be achieved was measured. RESULTS: The average length of the overlap at zero degrees of elbow flexion was 10.00 ± 1.84 mm. Theoretically, this will allow a defect of 20 ± 3.69 mm SD to be treated by primary suture. CONCLUSION: Our results suggest that anterior transposition can be used for radial nerve defects up to 2 cm; however, dissection of both stumps proved to be challenging.

Causes, symptoms, and treatments of nerve entrapments around the elbow: Current concepts.

The elbow is a joint extremely susceptible to stiffness, even after a trivial trauma. As for other joints, several factors can generate stiffness such as immobilisation, joint incongruity, heterotopic ossification, adhesions, or pain. Prolonged joint immobilisation, pursued to assure bony and ligamentous healing, represents the most acknowledged risk factor for joint stiffness. The elbow is a common site of nerve entrapment syndromes. The reasons are multifactorial, but peculiar elbow anatomy and biomechanics play a role. Passing from the arm into the forearm, the ulnar, median, and radial nerves run at the elbow in close rapport with the joint, fibrous arches and through narrow fibro-osseous tunnel. The elbow joint, in fact, has a large range of flexion which exposes nerves lying posterior to the axis of rotation to traction and those anterior to compression.

A Fresh Cadaver Study on the Innervation of Brachioradialis and Extensor Carpi Radialis Longus Muscles.

PURPOSE: Distal nerve transfers have revolutionized peripheral nerve surgery by allowing the transfer of healthy motor nerves to paralyzed ones without causing additional morbidity. Radial nerve branches to the brachialis (Ba), brachioradialis (Br), and extensor carpi radialis longus (ECRL) muscles have not been investigated in fresh cadavers. METHODS: The radial nerve and its branches were dissected in 34 upper limbs from 17 fresh cadavers. Measurements were taken to determine the number, origin, length, and diameter of the branches. Myelinated fiber counts were obtained through histological analysis. RESULTS: The first branch of the radial nerve at the elbow was to the Ba muscle, followed by the branches to the Br and ECRL muscles. The Ba and Br muscles consistently received single innervation. The ECRL muscle showed varying innervation patterns, with one, two, or three branches. The branches to the Br muscles originated from the anterior side of the radial nerve, whereas the branches to the Ba and ECRL muscles originated from the posterior side. The average myelinated fiber counts favored the nerve to Br muscle over that to the ECRL muscle, with counts of 542 versus 350 and 568 versus 302 observed in hematoxylin and eosin and neurofilament staining, respectively. CONCLUSIONS: This study provides detailed anatomical insights into the motor branches of the radial nerve to the Ba, Br, and ECRL muscles. CLINICAL RELEVANCE: Understanding the anatomy of the radial nerve branches at the elbow is of utmost importance when devising a reconstructive strategy for upper limb paralysis. These findings can guide surgeons in selecting appropriate donor or recipient nerves for nerve transfer in cases of high tetraplegia and lower-type brachial plexus injuries.

Clinical anatomy of the lateral antebrachial cutaneous nerve: Is there any safe zone for interventional approach?

INTRODUCTION: The lateral antebrachial cutaneous nerve (LACN) is a somatosensory nerve coursing in the lateral portion of the forearm. The nerve is located in a close proximity to the cephalic vein (CV) all along its course with a danger of being injured during venipuncture. The LACN also overlaps and communicates with the superficial branch of the radial nerve (SBRN) in the distal forearm and hand, making the awareness of their relationship of great importance in the treatment of neuroma. The aim of the study was to observe the relationship of the LACN to surrounding structures as well as its branching pattern and distribution. MATERIALS AND METHODS: Ninety-three cadaveric forearms embalmed in formaldehyde were dissected. The relationship of the LACN to surrounding structures was noted and photographed, and distances between the structures were measured with a digital caliper. The cross-sectional relationships of the LACN and SBRN to the CV were described using heatmaps. RESULTS: The emerging point of the LACN was found distally, proximally or at the level of the interepicondylar line (IEL). The LACN branched in 76 cases (81.7 %) into an anterior and posterior branch at mean distance of 47.8 ± 34.2 mm distal to the IEL. The sensory distribution was described according to the relationship of the LACN branches to the medial border of the brachioradialis muscle. The LACN supplying the dorsum of the hand was observed in 39.8 % of cases. The LACN and the SBRN intersected in 86 % of upper limbs with communications noticed in 71 % of forearms. The LACN was stated as the most frequent donor of the communicating branch resulting in neuroma located distal to the communication and being fed from the LACN. The relationship of the LACN and the CV showed that the IEL is the most appropriate place for the venipuncture due to maximal calibers of the CV and deep position of the LACN. The LACN was adjacent to the cubital perforating vein and the radial artery in all cases. The medial border of the brachioradialis muscle was observed less than 1.8 mm from the LACN. CONCLUSION: The study provides morphological data on the LACN distribution, branching pattern and relationship to surrounding structures in a context of clinical use in different spheres of medicine. The branching pattern of the LACN appears to be more constant compared to data provided by previous authors. We emphasized the meaning of cross-sectional relationship of the LACN to the CV to avoid venipuncture outside the cubital fossa if possible. The posterior branch of the LACN was predicted as appropriate donor of the graft for a digital nerve. The LACN appeared to be in a close proximity within the whole length of the brachioradialis muscle what the orthopedic surgeons must be concerned of. The meaning of the donor-nerve of the communicating branch in neuroma treatment was also introduced.

Radial Nerve Palsy Associated with Humeral Shaft Fractures in Children.

Background: This is the first systematic review of the relationship between humeral shaft fractures and radial nerve palsy in children. The present comprehensive review is aimed at identifying important clinical findings between humeral diaphysis fractures and radial nerve injuries and assessing the effects of treatment. Methods: We searched electronic bibliographic databases, including PubMed, the Cochrane Library, Scopus, and Web of Knowledge, until March 2022. This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the patients, interventions, comparisons, outcomes guidelines. Results: We identified 23 original papers, of which 10 were eligible for further analysis. Cases of 32 young patients with radial nerve palsy were identified and analyzed. The prevalence of radial nerve palsy was 4.34% (eight cases out of 184 patients with humeral shaft fractures). The radial nerve was most often associated with a simple transverse fracture (12A3, 17 cases (65.4%)). Conclusions: Radial nerve injury in humeral shaft fractures in children is rare, with a frequency of 4.34%. We highly recommend early surgical nerve exploration with transverse fractures in the distal third segment combined with primary radial palsy. Furthermore, we recommend making thoughtful decisions regarding early nerve exploration in the Holstein-Lewis fractures. In addition, consideration of early surgical nerve exploration in fractures resulting from high-energy trauma and open fractures despite their morphology is recommended.

Versatilidad anatómica del colgajo lateral del brazo. Estudio cadavérico en una muestra de población colombiana / Anatomical versatility of the lateral arm flap. Cadaver study in a sample of the Colombian population

Introducción y objetivo: El colgajo lateral del brazo es un recurso de cobertura para el cirujano de mano que tiene una amplia variedad de usos y aplicaciones por su versatilidad y facilidad de recolección con poca morbilidad del sitio donante. El objetivo de este estudio es documentar las principales variantes anatómicas y establecer puntos de referencias para el desarrollo y mejoramiento de las técnicas quirúrgicas actuales en una muestra de población colombiana. Material y métodos: Estudio descriptivo anatómico de 10 miembros superiores de cadáveres frescos congelados en los que realizamos disecciones para documentar las principales perforantes del colgajo lateral del brazo en población colombiana. Tomamos mediciones de distancia de las perforantes al epicóndilo lateral y sacamos proporciones según porcentajes del tamaño de la extremidad. Igualmente, cuantificamos número de perforantes en cada cuadrante y diámetro de los pedículos. Resultados: En el colgajo lateral del brazo, el orden de aparición de las perforantes de distal a proximal correspondió al 13, 19, 26 y 35% de la distancia del brazo (entre el epicóndilo y el acromion); en el segundo cuadrante encontramos la mayoría de las perforantes, la segunda y la cuarta, tuvieron menor variación con respecto a las demás perforantes, los pedículos proximales presentaron un mayor diámetro que los distales. Encontramos el nervio radial a la salida del tabique intermuscular en promedio a 14.08 cm (+/- 0.83) del epicóndilo, siendo esta referencia clave para una disección cuidadosa con el fin de evitar la lesión del mismo. Conclusiones: En nuestra población de estudio, el colgajo lateral del brazo posee una gran versatilidad, con un buen número de perforantes para su nutrición que le permite al cirujano múltiples opciones de cobertura...(AU)

Background and objective: The lateral arm flap is a coverage resource for the hand surgeon that has a wide variety of uses and applications due to its versatility and ease of collection with little morbidity from the donor site. The aim of this research is to carry out dissections of the lateral arm flap in cadavers of the Colombian population to describe the main anatomical vari-ants and establish reference points for the development and improvement of current surgical techniques. Methods: Anatomical descriptive study of 10 upper limbs from fresh-frozen cadavers in which dissections were performed to document the main perforators of the lateral flap of the arm in the Colombian population. Distance measurements were taken from the perforators to the lateral epicondyle and ratios were obtained according to percentages of limb size. Likewise, the number of perforators in each quadrant and the diameter of the pedicles were quantified. Results: The results showed that in the lateral arm flap the order of appearance of the perforators from distal to proximal corresponds to 13, 19, 26 and 35% of the distance of the arm (between the epicondyle and the acromion); most of the perforators were found in the second quadrant, the second and fourth have less variation compared to the other perforators, the proximal pedicles have a larger diameter than the distal ones, the radial nerve was found at the exit the intermuscular septum on average 14.08 cm (+/- 0.83) from the epicondyle, this is a key reference for a careful dissection in order to avoid injury to it. Conclusions: In our study population, the lateral arm flap is highly versatile with a good number of perforators for its nutrition, which allows the surgeon multiple coverage options. The bone perforators of the distal humerus must be protected in the most distal portion to avoid complications such as bone necrosis, especially in children...(AU)