Entire Forearm Research Articles

Smaller radioulnar window is associated with a distal biceps tendon rupture in patients with limited forearm rotation: a 3-dimensional computed tomography comparison study of proximal impingement caused by radial tuberosity hypertrophy—a single-center case series

It has been suggested that hypertrophy of the radial tuberosity may result in impingements leading to either lesion of the distal biceps tendon or rotational impairment. The two studies on hypertrophy of the radial tuberosity had contradictory results and did not study the distance between the radius and ulna: the radioulnar window. Therefore, this comparative cohort study aims to investigate the radioulnar window in healthy subjects and compare them with subjects suffering from either non-traumatic onset rotational impairment of the forearm or non-traumatic onset distal biceps tendon ruptures with a rotational impairment of the forearm using dynamic 3D CT measurements in order to attain a comprehensive understanding of the underlying etiology of distal biceps tendon ruptures. We hypothesize that a smaller radioulnar window increases the risk of having a non-traumatic onset distal biceps tendon rupture and/or a rotational impairment compared to healthy individuals. This study measured the distance between the radius and ulna at the level of the radial tuberosity using entire forearm computed tomography (CT) scans of fifteen patients in the Amphia Hospital between 2019 and 2022. Measurements of healthy subjects were compared to subjects with non-traumatic onset rotational impairment of the forearm and subjects with a non-traumatic onset distal biceps tendon rupture with a rotational impairment of the forearm. The Wilcoxon signed-rank test was used for individual comparisons, and the Mann-Whitney U test was used for group comparisons. A significant difference was found between the radioulnar window in the forearms of the subjects with a distal biceps tendon rupture (mean: 1.4, SD 0.4 mm) compared to the radioulnar window in forearms of the healthy subjects (mean: 4.8, SD 1.4 mm, p = 0.018). A trend towards smaller radioulnar windows in the rotational impairment groups was also observed, although it was not significant (p > 0.05). The radioulnar window in the forearms of the subjects with a distal biceps tendon rupture with a rotational impairment was significantly smaller than in the forearms of the healthy subjects. Therefore, patients with a smaller radioulnar window have a higher risk of rupturing their distal biceps tendon. Non-traumatic onset rotational impairments of the forearm may also be caused by a similar mechanism. Future studies are needed to back this finding further.

Evaluation of the ulna lengthening by distraction osteogenesis in congenital radial deficiency

PurposePublications evaluating the results of the ulna lengthening in congenital radial deficiency are based only on small groups of subjects which yield statistical studies of low scientific value. The aim was to examine the effectiveness of ulna lengthening in radial longitudinal deficiency and determine the number and quality of complications based on one of the most numerous study groups described in the literature.MethodsThe material consists of a study group with 31 upper limbs of unmatured patients diagnosed with type III and IV radial longitudinal deficiency. The study group was evaluated based on the parameters known from the literature. The difficulties during elongation were classified according to Paley’s classification.ResultsThe study group contained patients with a mean age of 9 years, and the number of boys and girls was comparable. Ulna length significantly increased after elongation compared to the initial bone length. The patient’s age didn’t affect the ulna lengthening, and the amount of elongation didn’t significantly affect the total stabilization period. However, the total stabilization time increased with increasing patient age. Difficulties affected more than half of the cases.ConclusionsUlna elongation in congenital radial deficiency results in significant lengthening of the ulna, and thus the entire forearm, compared to the initial bone length. This technique has a high percentage of difficulty, so its use should be considered after cautious discussion with the parents and patients.

Bifid median nerve associated with superficial ulnar artery: case report

The median nerve constitutes one of the six terminal branches of the brachial plexus. It descends through the inner part of the arm, and in the forearm through the midline. Once it reaches the wrist, it travels the carpal tunnel and divides into its terminal branches. Different variations have been described regarding its most distal portion in relation to carpal tunnel syndrome, the most frequent neuropathy in the upper limb. We report an anatomical variation in the median nerve and the ulnar artery found in the upper left limb of a female cadaver. The median nerve, in the distal third of the forearm, splits leaving a muscular fascicle interposed between the two branches. The ulnar artery has a superficial course along the entire forearm. In 1977 Lanz grouped the different variations in the median nerve in four sections. Type III (median bifid nerve) was sub classified years later into six subtypes. The present case corresponds to type III of Lanz subtype V (bifid median nerve with abnormal muscular fascicle interposed). Although this nerve variation has been described, the coexistence of a superficial ulnar artery had not been previously reported. Thorough knowledge of median nerve anatomy is of utmost importance to diagnose and treat injuries and entrapment neuropathies affecting this nerve and its major branches in the upper extremity. Furthermore, knowledge of its anatomical variations such as bifurcation of the median nerve or superficial ulnar artery could prevent surgical complications.

Severe Skin Ulcer on the Hand Caused by Hemodialysis Shunt-related Venous Hypertension That Required a Skin Graft.

Summary:In dialysis patients, peripheral venous hypertension–induced hand ulcers are rare. We report a case in which a severe hand ulcer was treated with skin grafting after shunt ligation. The patient was a 60-year-old woman who been undergoing dialysis for 13 years. Twelve years ago, a shunt was created in her right wrist via a side-to-side anastomosis. Swelling and congestion occurred in the right hand, and skin ulcers developed on the dorsal proximal portions of the index, middle, ring, and little fingers. No central vein obstruction was apparent. The right wrist shunt was explored, and the distal vein was ligated. A new shunt was created at the right elbow, but the proximal end of the vein that was used for the wrist shunt had to be used, resulting in complete cephalic vein occlusion from the wrist to the elbow. The swelling extended to the entire forearm. Four weeks after the wrist and elbow shunts were ligated, conservative treatment had resulted in granulation tissue formation in the ulcers. Debridement and full-thickness skin grafting from the abdomen were performed. Overall, skin graft survival was 75%. In conclusion, in this patient, side-to-end anastomosis of the proximal vein might be appropriate for shunt creation. When venous hypertension is suspected, ensuring an appropriate alternative shunt, promptly detecting the cause of the problem, and appropriate treatment are important. Venous hypertension must be completely resolved before surgery for ulcers.

A wearable neural interface for detecting and decoding attempted hand movements in a person with tetraplegia.

We are developing a wearable neural interface based on high-density surface electromyography (HDEMG) for detecting and decoding signals from spared motor units in the forearms of people with tetraplegia after spinal cord injury (SCI). A lightweight, form-fitting garment containing 150 disc electrodes and covering the entire forearm was used to map the myoelectric activity of forearm muscles during a wide range of voluntary tasks of a person with chronic tetraplegia after SCI (C5 motor and C6 sensory American Spinal Injury Association Impairment Scale B spinal cord injury). Despite exhibiting no overt finger motion, myoelectric signals were detectable for attempted movements of individual digits and were highly discriminable. Motor unit decomposition was used to identify the activity of >30 motor neurons, active specifically during rotation, pronation of the wrist (4 units), and flexion of the elbow joint (7 units), and during attempted movements of individual hand digits (1-5 units). In addition, we performed a neural connectivity analysis based on the power of the common oscillations of the identified motor neurons in the delta (~5Hz), alpha (~6-12 Hz), and beta bands (~15-30 Hz). This analysis showed clear common synaptic inputs to the identified motor neurons in all the analyzed frequency bands. This neural interface offers a new potential for the control of assistive technologies, whereby the motor neurons spared after SCI may serve as a direct readout of motor intent that allows proportional control over several distinct degrees of freedom. Moreover, this framework can be used to study the reorganization and recovery of spinal networks after injury and rehabilitation.

Clinical repercussions of Martin-Gruber anastomosis: anatomical study

ObjectiveThe main objective of this study was to describe Martin-Gruber anastomosis anatomically and to recognize its clinical repercussions. Method100 forearms of 50 adult cadavers were dissected in an anatomy laboratory. The dissection was performed by means of a midline incision along the entire forearm and the lower third of the upper arm. Two flaps including skin and subcutaneous tissue were folded back on the radial and ulnar sides, respectively. ResultsNerve communication between the median and ulnar nerves in the forearm (Martin-Gruber anastomosis) was found in 27 forearms. The anastomosis was classified into six types: type I: anastomosis between the anterior interosseous nerve and the ulnar nerve (n=9); type II: anastomosis between the anterior interosseous nerve and the ulnar nerve at two points (double anastomosis) (n=2); type III: anastomosis between the median nerve and the ulnar nerve (n=4); type IV: anastomosis between branches of the median nerve and ulnar nerve heading toward the flexor digitorum profundus muscle of the fingers; these fascicles form a loop with distal convexity (n=5); type V: intramuscular anastomosis (n=5); and type VI: anastomosis between a branch of the median nerve to the flexor digitorum superficialis muscle and the ulnar nerve (n=2). ConclusionKnowledge of the anatomical variations relating to the innervation of the hand has great importance, especially with regard to physical examination, diagnosis, prognosis and surgical treatment. If these variations are not given due regard, errors and other consequences will be inevitable.

Repercussões clínicas da anastomose de Martin‐Gruber: estudo anatômico

ObjectiveThe main objective of this study was to describe Martin‐Gruber anastomosis anatomically and to recognize its clinical repercussions. Method100 forearms of 50 adult cadavers were dissected in an anatomy laboratory. The dissection was performed by means of a midline incision along the entire forearm and the lower third of the upper arm. Two flaps including skin and subcutaneous tissue were folded back on the radial and ulnar sides, respectively. ResultsNerve communication between the median and ulnar nerves in the forearm (Martin‐Gruber anastomosis) was found in 27 forearms. The anastomosis was classified into six types: Type 1: anastomosis between the anterior interosseous nerve and the ulnar nerve (n=9); Type 2: anastomosis between the anterior interosseous nerve and the ulnar nerve at two points (double anastomosis) (n=2); Type 3: anastomosis between the median nerve and the ulnar nerve (n=4); Type 4: anastomosis between branches of the median nerve and ulnar nerve heading towards the flexor digitorum profundus muscle of the fingers; these fascicles form a loop with distal convexity (n=5); Type 5: intramuscular anastomosis (n=5); and Type 6: anastomosis between a branch of the median nerve to the flexor digitorum superficialis muscle and the ulnar nerve (n=2). ConclusionKnowledge of the anatomical variations relating to the innervation of the hand has great importance, especially with regard to physical examination, diagnosis, prognosis and surgical treatment. If these variations are not given due regard, errors and other consequences will be inevitable.

Diffuse Hyperkeratosis in a Deaf and Blind 48-Year-Old Woman—Quiz Case

An 83-year-old man with a history of diabetes and chronic obstructive pulmonary disorder (COPD) (taking prednisone, 5 mg/d) was admitted to our facility with a monthlong history of persistent right arm swelling, erythema, and pain. He had multiple prior admissions for this issue and was treated with oral and intravenous antibiotics for a suspected “cellulitis.” His skin symptoms worsened despite treatment, and he developed an extensive superimposed pustular eruption with sinus tracts involving the entire forearm and a portion of the upper arm (Figure 1). Workup included ultrasonography, which showed no fluid collection, and magnetic resonance imaging, which showed soft-tissue swelling without evidence of any underlying myositis or osteomyelitis. A Tzanck smear failed to show multinucleated giant cells. Punch biopsy specimens for culture and histopathologic analysis were obtained (Figure 2 and Figure 3). What is your diagnosis?

Extensive skin color change caused by extravasation of indigo carmine

Extensive skin color change caused by extravasation of indigo carmine

Neuroprotection by Gene Therapy Targeting Mutant SOD1 in Individual Pools of Motor Neurons Does not Translate Into Therapeutic Benefit in fALS Mice

A major challenge in neurological gene therapy is delivery of the transgene to sufficient cell numbers in an atraumatic manner. This is particularly difficult for motor neuron (MN) diseases that have cells located across the entire spinal cord, brain stem, and cortex. We have used the familial mouse model of amyotrophic lateral sclerosis (ALS) to examine the feasibility of body-wide intramuscular injections of adeno-associated virus serotype 6 (AAV6), a vector capable of axonal retrograde transport, to deliver therapeutic genetic information across the lower MN axis. Neonatal muscle delivery of AAV expressing small hairpin RNAs (shRNAs) against the toxic transgene in this model, human mutant superoxide dismutase 1 (mSOD1), led to significant mSOD1 knockdown in the muscle as well as innervating MNs. This knockdown conferred neuroprotection and halted muscle atrophy in individually targeted MN pools. However, despite the vector being targeted to MNs that innervate muscle groups controlling eating, breathing, and locomotion, this approach was unable to therapeutically impact on disease progression in the ALS mouse model. These results stress the complexity of gene delivery for mSOD1 silencing and suggest that critical thresholds of protein knockdown and transduction across various cell types are required to translate local neuroprotective effects into functional improvements.

ACUTE PLASTIC BOWING OF THE RADIUS WITH A DISTAL RADIOULNAR JOINT INJURY: A CASE REPORT

Acute plastic bowing is an incomplete fracture with a deformation that shows no obvious macroscopic fracture line or cortical discontinuity. Although cases of acute plastic bowing of the ulna with a dislocation of the radial head have been previously reported, we present here a rare case of acute plastic bowing of the radius with a distal radioulnar joint injury in a 16-year-old boy. Internal fixation of the detached fragment to the ulnar styloid and repair of the triangular fibrocartilagenous complex resulted in the disappearance of wrist pain. In cases of distal radioulnar joint injuries in children or adolescents, radiographs of the entire forearm should be taken to evaluate the existence of radial bowing.

A primarily overlooked and incorrectly treated Essex-Lopresti injury: what can this lead to?

What result can one expect in treating an Essex-Lopresti lesion--a rare complex combination injury of the forearm consisting of a radial head fracture and a rupture of the interosseous membrane--which failed to be identified at first? We report on a 45-year-old poly traumatized patient in which a primary Essex-Lopresti injury was overlooked following a dislocated radial head fracture. A radial head resection followed by an ulna-shortening osteotomy was performed with disastrous consequences at another clinic. As a result of persistent instability in the distal radioulnar joint, we implanted a mono-polar radial head prosthesis, which was subsequently changed as a result of a loosening of the prosthesis and persistent complex instability and pain in the area of the entire forearm, while an ulna osteotomy had to be carried out to correct this. This prosthesis also loosened, which destroyed the capitulum humeri. It was only after a specially designed modular radial head prosthesis with a capitulum shield was implanted and an elapse of 5(1/2) years of the illness that permanent stability could be achieved on the forearm and the pain experienced by the patient eliminated while at the same time the patient regained a moderate degree of functioning and grip strength. An overlooked primary and ultimately initially incorrectly treated Essex-Lopresti injury can degenerate into a real therapeutic disaster. Years of illness and multiple corrective operations which only serve to limit the collateral damage caused by the wrong therapy strategy and ultimately only lead to restoration of moderate function. The crucial factor is an early diagnosis. Then a radial head prosthesis should first be implanted in an operation in order to prevent an additional proximal migration of the radius and to move the distal radioulnar joint into the proper anatomical position.

Fishy food for thought.

The article by Wu and colleagues in this issue describes an interesting case of asthma secondary to exposure to bloodworms in a laboratory setting. The use of bloodworms as a fish food has led to a number of differing manifestations dependent on the route of exposure. These include anaphylaxis, asthma, and urticaria/angioedema secondary to contact. A person who worked in an office setting in our hospital was referred to me after three admissions to our emergency department for marked angioedema and inflammation of the right side of the face, chemosis of the right eye, and blurred vision with onset in the morning at work. She had no atopic history and had eaten no food on the day of one of the reactions. Only after persistent questioning regarding what she may have transferred from her hand to her face (she was right-handed) did she divulge that she fed the fish in her aquarium in the office. She did not know the source of the fish food, and I requested that she place a tiny amount on her forearm the following day. This produced a swelling of the entire forearm. The fish food was freeze-dried bloodworms. Interestingly, at the annual meeting of the Canadian Society of Allergy and Clinical Immunology (CSACI) that same week, Dr. J. Roberts presented the case of a girl who had developed anaphylaxis after accidental ingestion of residual fish food that was on her hands when she was eating dinner. This individual had a striking reaction to a dilute preparation of the bloodworm fish food on skin testing and did not react to other fish food preparations. Subsequent to these cases, a colleague mentioned additional cases of asthma symptoms in employees at the Vancouver Aquarium, where bloodworms are raised and processed as a food source. The well-defined case presented in this issue and the others mentioned suggest that bloodworm may be a more common cause of allergic reactions than generally recognized and warrants consideration when the patient's history is reviewed. R. Robert Schellenberg, MD, FRCP

Surgical management of a high-flow arteriovenous malformation of the upper extremity producing severe hemodynamic impairment

Peripheral arteriovenous (AV) malformations may present with a plethora of clinical symptoms such as paradoxical emboli, severe hypertension, nerve palsies or pain syndromes. Hemodynamically compromising lesions of the limbs are rare and involve high-flow AV fistulae with marked arteriovenous shunting. A female patient with a high-flow arteriovenous malformation of the left upper-extremity is presented. Preoperative assessment by magnetic resonance imaging and magnetic resonance angiography together with a color duplex investigation revealed a hemodynamically compromising arteriovenous fistula (shunt volume 30%) involving the entire left forearm and hand. The lesion was managed operatively with a combination of selective ligation and sclerosing of the feeding artery. There was marked clinical improvement postoperatively. Magnetic resonance angiography confirmed a drastic decrease in the number and size of the arteriovenous fistulae. The shunt ratio was diminished to 10%. Although surgical treatment of arteriovenous fistulae is known to have high complication and recurrence rates, thorough preoperative planning and intraoperative monitoring, can supply the prerequisites for a favorable outcome in severe symptomatic cases.

EFFECTS OF PROLONGED HEAD-DOWN TILT (HDT) BED REST ON SWEAT GLAND FUNCTION AND MAXIMAL FOREARM CUTANEOUS VASCULAR CONDUCTANCE

The magnitude of cutaneous vasodilation and sweating is reduced during a thermal challenge following simulated or actual microgravity exposure. The effects of microgravity exposure on cutaneous vasodilator capacity and on sweat gland function are unknown. The purpose of this study was to test the hypothesis that simulated microgravity exposure using the 6° HDT model reduces maximal forearm cutaneous vascular conductance (CVC) and sweat gland function. To test this hypothesis six subjects were exposed to 14 days of strict HDT bed rest. Prior to and following HDT bed rest maximal forearm CVC was measured, via plethysmography, by heating the entire forearm to 42° C for 45 min. Forearm CVC was calculated as forearm blood flow/mean arterial blood pressure. Sweat gland function was assessed by administering 10−6 to 2 M acetylcholine (9 doses) via intradermal micordialysis while simultaneously monitoring sweat rate over microdialysis membranes. Maximal forearm CVC was reduced in five of the six subjects following HDT bed rest, however the overall reduction was not significant (21.3 ± 1.2 to 19.3 ± 2.3 units). Neither the concentration of acetylcholine causing 50% of the maximal sweating response (EC50; log acetylcholine concentration: −1.3 ± 0.2 to −1.3 ± 0.03 M; P = 0.04) nor maximal sweat rate (0.92 ± 0.06 to 0.79 ± 0.10 mg/cm2/min; P = 0.2) were significantly altered by HDT bed rest. These data suggest that 14 days simulated microgravity exposure using the HDT bed rest model may reduce maximal forearm CVC without altering sweat gland function. It remains unclear whether alterations in maximal cutaneous vasodilation, if present, are responsible for impaired cutaneous vasodilation observed after space flight or after simulated microgravity exposure. Supported by NASA:NAG9-1033 and NIH-HL61388

The exercise pressor response to sustained handgrip does not augment blood flow in the contracting forearm skeletal muscle.

Previous studies have advanced the concept that during sustained handgrip (SHG) reflex increases in blood pressure are able to partially offset increases in tissue pressure and thus effectively maintain increases in muscle blood flow during mild to moderate levels of sustained handgrip. However, this concept is based upon measurements of blood flow to the entire forearm. The aim of this study was to evaluate this concept by simultaneously measuring time-dependent changes in systemic arterial pressure and blood flow in an active muscle during the actual period of exercise. To accomplish this aim, we measured 133Xenon washout from the extensor carpi radialis longus muscle over 3 min of SHG at 15, 30 and 45% of maximal voluntary contraction (MVC). During sustained handgrip at 15% MVC, muscle blood flow increased more than 20 fold from rest to exercise (P < 0.05), even though mean arterial pressure increased by only 12 +/- 4 mmHg. This large exercise-induced hyperaemia was abolished during SHG at both 30 and 45% MVC, despite large and progressive increases in mean arterial pressure of 29 +/- 3 and 54 +/- 5 mmHg, respectively. We conclude that at levels of handgrip above 15% MVC blood pressure ceases to be an important determinant of blood flow in the active skeletal muscle. Importantly, the increases in forearm blood flow that have been reported previously with such levels of static handgrip do not appear to be directed to the most active muscle.

The Preexpanded Radial Free Flap

The experimental basis for free-flap preexpansion is briefly discussed. Two cases are reported in which the ankle/heel area was resurfaced and reinnervated with a preexpanded radial flap. The size of the first flap was half the surface area of the entire forearm. Direct closure of the secondary defect was possible with a single scar and without functional deficit in both cases. The flaps were well-vascularized and consisted of the sensory distribution of one peripheral nerve division, which was anastomosed in the recipient site. This preparation proved to be finer and to have better contouring capacity and skin quality than existing alternatives. It is clear that hydraulic tissue expansion facilitates great additional use of the radial flap as well as a range of other modified free flaps when there is time available for the flap to be developed prior to transfer.

Lower limb salvage using an extended free radial forearm flap

A case is reported of an unusual double injury, in which a lower limb salvage procedure employed a free radial forearm flap from an amputated upper limb. The use of amputated parts for salvage procedures is well documented but none has previously involved a free forearm flap. This clinical case shows that the entire forearm and hand skin can be adequately perfused on the radial artery along with the superficial palmar arch.

Measurement of water filtration in skeletal muscle in man by an osmotic transient method.

Water filtration in the human forearm was determined with a new method using a hyperoncotic transient of albumin solution infused into the brachial artery. Baseline dilution of labelled albumin in deep forearm vein plasma in excess of the contribution from arterial blood and from infusate was assumed to originate from extravascular water filtered into the blood by the transient. The filtration coefficient (Fc) was determined as the ratio between filtered water and increase in colloid osmotic pressure in the blood samples, and gives the filtrative water permeability in the exchange areas of the microcirculation. In 10 normal volunteers, Fc was 0.00082 ml (ml mmHg)-1 (SD=0.00007). Multiplication of Fc by plasma flow in the forearm gave a filtration capacity (Kf) of 0.0036 ml (100 ml tissue min mmHg)-1 (SD=0.00137). This filtration capacity (Kf) represents that of fast flowing regions in the forearm muscles, but it is of the same order of magnitude as the capillary filtration coefficient (CFC) determined plethysmographically for the entire forearm by the venous stasis technique.

Advances in the Diagnosis and Treatment of Stinging Insect Allergy

Allergic reactions to insect stings occur in approximately 0.4% of the general population.1,2 Severe anaphylactic reactions may occur in sensitive patients, and estimates suggest that 40 persons die during such reactions each year in the United States.3 From the standpoint of allergy the Hymenoptera order of insects is the most important; this order includes the bees (honeybees and bumblebees), vespids (wasps, yellow jackets, and hornets), and fire ants. CLASSIFICATION OF STING REACTIONS Insect sting reactions may be grouped into immediate (within two hours) or delayed (more than two hours) categories. Immediate reactions can be subdivided into local, large local, or systemic reactions, depending on the severity and extent of the reaction. Local reactions are normal reactions—a sting will cause transient pain, redness, and swelling at the sting site. In large local reactions the reaction is much more extensive, although all signs and/or symptoms produced are contiguous with the sting site. For example, a sting on the finger may produce swelling of the entire forearm or extremity. In a systemic reaction signs and/or symptoms occur at sites remote from the sting site. For example, a sting on the finger may produce angioedema of the eyelids or generalized urticaria. Toxic reactions are nonimmunologic reactions produced when an individual is stung by multiple insects within a short period of time; signs and symptoms are those of a systemic allergic reaction, but are due to the physiologic effects of vasoactive materials in the venom. Systemic allergic reactions are immunologic reactions produced by vasoactive materials released from the blood basophils or tissue mast cells as a result of interaction between venom components and specific IgE antibodies fixed to the basophils or mast cells.