Elbow Level Research Articles

Effect of body roll amplitude and arm rotation speed on propulsion of arm amputee swimmers

Only a limited amount of research has gone into evaluating the contribution made by the upper arm to the propulsion of elite swimmers with an amputation at elbow level. With assistance of computational fluid dynamics (CFD) modelling, the swimming technique of competitive arm amputee swimmers can be assessed through numerical simulations which test the effect of various parameters on the effectiveness of the swimming propulsion. This numerical study investigates the effect of body roll amplitude and of upper arm rotation speed on the propulsion of an arm amputee swimmer, at different mean swimming speeds. Various test cases are simulated resulting in a thorough analysis of the complex body/fluid interaction with a detailed quantitative assessment of the effect of the variation of each parameter on the arm propulsion. It is found that a body roll movement with an amplitude of 45° enhances greatly the propulsive contribution from the upper arm with an increase of about 70% in the propulsive force compared to the no roll condition. An increase in the angular velocity of the upper arm also leads to a concomitant increase in the propulsive forces produced by the arm. Such results have direct implications for competitive arm amputee front crawl swimmers and for those who coach them. One important message that emerges in this present work is that there exists, for any given swimming speed, a minimum angular velocity at which the upper arm must be rotated to generate effective propulsion. Below this velocity, the upper arm will experience a net resistive drag force which adversely affects swimming performance.

Influence of load type on presynaptic modulation of Ia afferent input onto two synergist muscles

The present work was designed to investigate presynaptic modulation of Ia afferents in the extensor (ECR) and flexor carpi radialis (FCR) when the two muscles acted as synergists during radial deviation to either support an inertial load (position task) or exert an equivalent constant torque against a rigid restraint (force task). H reflexes were evoked in the ECR and FCR by stimulating at the elbow level (1-ms duration) the radial and median nerves, respectively. Conditioning stimulation was applied to the median and radial nerves at the elbow level to assess presynaptic inhibition of homonymous Ia afferent input (D1 inhibition) from the ECR and FCR, respectively. The ongoing presynaptic inhibition of heteronymous Ia afferents that converges onto ECR and FCR motor neuron pools (heteronymous Ia facilitation) was assessed by stimulating the median nerve at the wrist level (palmar branch) prior to the stimulus applied over the radial or median nerve. The heteronymous monosynaptic Ia facilitation was greater (P < 0.05) during the position task (ECR 121%; FCR 147%) compared with the force task (ECR 115%; FCR 132%), and was paralleled by the depression of D1 inhibition (P < 0.05) during the position task (ECR 75.4%; FCR 79.0%) compared with force task (ECR 58.7%; FCR 58.8%). These data indicate that Ia presynaptic inhibition is reduced during the position task relative to the force task. Such differential modulation of Ia afferent input onto the motor neuron pool likely reflects the requirement to heighten reflex responsiveness during the unstable task of maintaining limb position.

Long-term results of major upper extremity replantations

The aim of this study was to evaluate long-term clinical and functional results of major upper extremity replantations. We retrospectively evaluated 26 male patients (mean age 27 years; range 3 to 69 years) who underwent major upper extremity replantations and had a mean follow-up of 11.3 years (range 5 to 19 years). The levels of the replantations were transmetacarpal (n=6), wrist (n=4), forearm (n=5), elbow (n=4), and arm (n=7). Amputations were of clean-cut, crush, and avulsion types in seven, eight, and 11 patients, respectively. Secondary operations were performed in 19 patients. Functional results were assessed using the Chen's criteria and the Turkish version of the DASH questionnaire (Disabilities of the Arm, Shoulder and Hand) was administered. The mean surgical shortening was 37.2 mm, and the final mean radiographic shortening was 52.2 mm. The mean grip and pinch strengths on the affected side were 12.3 kg and 3.6 kg, compared to the strengths of 37.6 kg and 8.7 kg on the normal side, respectively. Monofilament testing showed sensory recovery in 20 patients. Two-point discrimination could be made by 18 patients for the median nerve, and by 17 patients for the ulnar nerve. According to the Chen's criteria, the results were very good or good in 17 patients (65.4%), moderate in three patients (11.5%), and poor in six patients (23.1%). Functional results were correlated with the level (r=0.71) and type (r=0.65) of injury, with injuries at the elbow level and avulsion injuries being associated with a worse outcome. The mean DASH score was 6.7 (range 0 to 32.5) and the mean scores of Chen's grade I-II and grade III-IV patients differed significantly (p<0.05). Lower DASH scores show increased satisfaction of the patients and improved use of their replanted extremities as the helper arm whereby functional deficiency is somewhat compensated.

Ergonomic assessment of optimum operating table height for hand-assisted laparoscopic surgery

To investigate the influence of the working surface height on task performance and muscle workload in hand-assisted laparoscopic surgery. The standard task used was closure of 5-cm enterotomy inside a hand-assisted laparoscopic surgery trainer. Surgeons were instructed to place the sutures 3-5 mm apart and from the enterotomy edge. Ten surgeons participated in each experiment and one task was performed with each level. The first experiment compared the quality of task performance and muscle workload with the working surface at: elbow level, 10 cm above, 15 cm above and 10 cm below the elbow. Further narrower levels (5 cm below, at the elbow and 5 cm above the elbow) were investigated in the second experiment. Outcome measures were execution time (s), placement error score (mm), leakage pressure (mmHg), number of execution errors, muscle workload as measured by integrated electromyography (mV x s) and visual analogue score of back discomfort (mm). The first experiment showed that 15 cm above the elbow level was associated with the longest execution time and similar quality of task performance. This level resulted in a higher workload of the deltoid of the extracorporeal limb, the arm extensor of the intracorporeal side and the trapezius and paraspinal muscles of both intra- and extracorporeal limbs. Also, the 10 cm above the elbow level was associated with increased muscle workload of the deltoid of extracorporeal limb and the trapezius of both limbs compared with the elbow height. The 10 cm below the elbow level was associated with increased back discomfort. The second experiment showed that 5 cm below the elbow height was associated with increased muscle workload of the arm flexor group of the intracorporeal dominant limb. The optimum table height for hand-assisted laparoscopic surgery allows the working surface of the extracorporal instrument handle to be at or 5 cm above the elbow level.

Lack of pain in schizophrenia: a patient whose arm was burned and amputated

Diminished pain sensitivity or loss of pain sensation in schizophrenic patients has previously been reported. We report an interesting case of a schizophrenia patient who had the disease for 20 years and who had his forearm amputated below the elbow level due to severe burn injury to his muscles, tendons, nerve fibers and bone tissue, caused by direct exposure to flames from a liquefied petroleum gas cylinder, in an attempt to make himself warm during a medicine-free period with active symptoms and without pain sensation.

Prevention of upper limb symptoms and signs of nerve afflictions in computer operators: The effect of intervention by stretching.

BackgroundIn a previous study of computer operators we have demonstrated the relation of upper limb pain to individual and patterns of neurological findings (reduced function of muscles, sensory deviations from normal and mechanical allodynia of nerve trunks). The identified patterns were in accordance with neural afflictions at three specific locations (brachial plexus at chord level, posterior interosseous and median nerve on elbow level). We have introduced an intervention program aiming to mobilize nerves at these locations and tested its efficacy.Methods125 and 59, respectively, computer operators in two divisions of an engineering consultancy company were invited to answer a questionnaire on upper limb symptoms and to undergo a blinded neurological examination. Participants in one division were subsequently instructed to participate in an upper limb stretching course at least three times during workdays in a six month period. Subjects from the other division served as controls. At the end of the intervention both groups were invited to a second identical evaluation by questionnaire and physical examination. Symptoms and findings were studied in the right upper limb. Perceived changes of pain were recorded and individual and patterns of physical findings assessed for both groups at baseline and at follow-up. In subjects with no or minimal preceding pain we additionally studied the relation of incident pain to the summarized findings for parameters contained in the definition of nerve affliction at the three locations.ResultsSummarized pain was significantly reduced in the intervention group but unchanged in controls. After the intervention, fewer neurological abnormalities in accordance with nerve affliction were recorded for the whole material but no conclusion could be drawn regarding the relation to the intervention of this reduction. Incident pain correlated to findings in accordance with the three locations of nerve affliction.ConclusionA six month course of stretching seems to reduce upper limb symptoms in computer operators but we could not demonstrate an influence on neurological physical findings in this sample. The relation of incident symptoms to identified neurological patterns provides additional support to the construct validity of the employed neurological examination.

The superficial ulnar artery: development and clinical significance

The principal arteries of the upper limb show a wide range of variation that is of considerable interest to orthopedic surgeons, plastic surgeons, radiologists and anatomists. We present here a case of superficial ulnar artery found during the routine dissection of right upper limb of a 50-year-old male cadaver. The superficial ulnar artery originated from the brachial artery, crossed the median nerve anteriorly and ran lateral to this nerve and the brachial artery. The superficial ulnar artery in the arm gave rise to a narrow muscular branch to the biceps brachii. At the elbow level the artery ran superficial to the bicipital aponeurosis where it was crossed by the median cubital vein. It then ran downward and medially superficial to the forearm flexor muscles, and then downward to enter the hand. At the palm, it formed the superficial and deep palmar arches together with the branches of the radial artery. The presence of a superficial ulnar artery is clinically important when raising forearm flaps in reconstructive surgery. The embryology and clinical significance of the variation are discussed.

A cross-sectional study of the relation between symptoms and physical findings in computer operators.

BackgroundThe character of upper limb disorder in computer operators is subject to debate. A peripheral nerve-involvement is suggested from the common presence of a triad of symptoms consisting of pain, paraestesiae and subjective weakness, and from physical findings suggesting neuropathy. This study aimed to examine the outcome of a detailed neurological examination in computer operators and to compare findings with the presence of symptoms.Methods96 graphical computer operators answered a modified Nordic Questionnaire including information on perceived pain in the shoulder, elbow, and wrist/hand scored for each region on a VAS-scale 0 – 9. In addition, they underwent a physical examination including the subjective assessment of the individual function of 11 upper limb muscles, of algesia in five and vibratory threshold in three territories, respectively, and of mechanosensitivity of nerves at seven locations. In order to reflect an involvement of the brachial plexus (chord level), the posterior interosseous nerve and the median nerve at elbow level we defined three patterns of neurological findings illustrating the course of nerves and their innervation. The pain scores summarized for the three upper limb regions (min. = 0, max = 27) in the mouse-operating and contralateral limbs were compared by a Wilcoxon test and the relation to each physical item analyzed by Kendall's rank correlation. The relation of summarized pain to each pattern was studied by application of a test of the trend across ordered groups (patterns).ResultsPain, paraestesiae and subjective weakness was reported for 67, 23, and 7 mouse-operating limbs, respectively, with the summarized pain scores exceeding 4 in 33 limbs. Abnormal physical findings were prevalent. The summarized pain was significantly related to a reduced function in five muscles, to mechanical allodynia at one location and to elevated threshold to vibration in two territories. Brachial plexopathy was diagnosed in 9/2, median neuropathy in 13/5 and posterior interosseous neuropathy in 13/8 mouse operating/contralateral limbs, respectively. The summarized pain was significantly higher in the mouse-operating limbs and in limbs with any of the defined patterns. There was a significant trend between the summarized pain and the summarized scores for the items contained in each pattern.ConclusionThis small-scale study of a group of computer-operators currently in work and with no or minor upper limb symptoms has indicated in symptomatic subjects the presence of peripheral nerve-afflictions with specific locations.

Bicipital groove orientation: Considerations for the retroversion of a prosthesis in fractures of the proximal humerus

The bicipital groove anatomy is well documented, and this groove is used as a landmark to guide retroversion during implantation of a shoulder prosthesis. Whereas the proximal part of the groove is used in osteoarthritis, the distal part is used in fractures. If used in 4-part fracture cases, we must assume that the bicipital groove orientation is constant from proximal to distal. We measured the groove orientation in 40 cadaveric humeri using 3 superimposed computed tomography sections. The reference axis was the transepicondylar axis at the elbow level. The measured angle of the bicipital groove was 55.8 degrees +/- 4.5 degrees at the anatomic neck and 65.1 degrees +/- 3.5 degrees at the surgical neck. This difference (mean of 9.3 degrees, with extremes of -3 degrees and 22.5 degrees) was statistically significant. We confirmed a wide range of variation from 22 degrees to 89 degrees in the orientation of the groove. Because the values listed in the literature for lateral fin placement of a prosthesis have not been measured at the surgical neck level and because of the great variation in groove orientation, we caution surgeons about the use of the bicipital groove as a reliable landmark in shoulder replacement for fractures. Considering the risk of over- or under-retroversion of the prosthesis, we recommend the use of a fracture jig with retroversion set to 20 degrees.

The disynaptic group I inhibition between wrist flexor and extensor muscles revisited in humans

The present studies are designed to further characterise the interneuronal pathway mediating the disynaptic reciprocal group I inhibition between flexors and extensors at the wrist and the elbow levels in humans. In the first series of experiments, we compared the electrical threshold of the reciprocal group I inhibition at the wrist and the elbow level after a prolonged vibration aimed at raising the electrical threshold of the antagonistic activated Ia afferents. Prolonged vibration to the 'conditioning' tendon, which raised significantly the electrical threshold of the inhibition at the elbow level, did not alter it at the wrist level. These results suggest that the dominant input to the relevant interneurones is Ia in origin at the elbow level but Ib in origin at the wrist level. In the second series of experiments, using the spatial facilitation method, we compared the effects on the post-stimulus time histograms of single voluntarily activated motor units of two volleys delivered both separately and together to group I afferents in the nerves supplying the homonymous and antagonistic muscles. At the wrist, but not at the elbow level, the peak of homonymous monosynaptic group I excitation was reduced on combined stimulation, although the antagonistic IPSP was just at the threshold. Because the suppression did not involve the initial bins of the peak, it is argued that the suppression is not due to presynaptic inhibition of Ia terminals, but probably reflects convergence between the homonymous and antagonistic volleys onto the interneurones mediating the disynaptic inhibition. Taken together with the previously reported effects of recurrent inhibition on reciprocal inhibition, these results suggest that inhibition between flexors and extensors is differently organised at the elbow (reciprocal Ia inhibition) and the wrist (non-reciprocal group I inhibition) levels. It is argued that the particular connectivity at the wrist level might correspond to some functional requirements at this ball joint.

Load spatial pathway and spine loading: how does lift origin and destination influence low back response?

While heavy lifting has been identified as an important risk factor for low back disorders, little is known about workplace spatial layout – the relative positions of shelves and the impact of this on spine loads. The objective of the current study was to investigate how the relative positions of the load origin and destination impact three-dimensional spine loads. Seven females and seven males lifted an 11.4 kg box from an origin shelf to a destination shelf, each defined by height (elbow, knee and shoulder level) and asymmetry (60° clockwise, sagittally symmetric, 60° counter-clockwise) while their spine loading was assessed by an electromyographic-assisted model. The results indicated that the starting and destination heights and starting task asymmetry all had significant impact on spine compression (with an increase of between 400 and 1900 N when compared to the most neutral position) and lateral shear (with a 100 to 150 N increase) while the destination height impacted the anterior – posterior shear forces (with up to 400 N increase). The results of the current study emphasize the importance of proper workplace spatial layout, specifically the importance of specifying starting position of the load relative to the destination. Adjustment of the starting position will impact the three-dimensional spine loads while the destination height and asymmetry influence the shear forces. Furthermore, the influence of the specific pathway (origin relative to destination) indicates there may be a potential preparatory muscle response leading to the loads on the spine. Thus, the pathway of the box plays an important role in the spine responses during lifting, in that longer and non-neutral pathways increase spine loads – indicating the importance of the relative position of the origin and destination shelf.

Résections-reconstructions pour tumeurs osseuses malignes du membre supérieur

Malignant bone and soft-tissue tumours are less common in the upper limb than in the lower limb (ratio 1:2). They mainly affect the shoulder, particularly the proximal humerus. Limb-sparing surgery may be considered in about 80% of patients with malignant shoulder tumours. In contrast, in patients with more distal malignancies (at the elbow level, or below) that involve extraosseous tissue, amputation is frequently required. A biopsy must be performed prior to treatment of the tumour, together with investigations aimed at assessing the tumour extension in the bone and soft tissues, the relationships between the tumour and the joints, vessels and nerves, the regional spread, and potential metastatic disease. After scapulectomy, the proximal humerus is suspended to the clavicle or ribs. Massive scapular prostheses or allografts are rarely used. When the proximal humerus can be resected without removing the deltoid muscle, reconstruction can be achieved using a composite inversed Delta prosthesis, a massive allograft, or a composite humeral prosthesis. When deltoid excision is required, scapulohumeral arthrodesis with allogeneic and autologous grafting is performed. After resection of the humeral diaphysis, reconstruction relies on allogeneic and autologous graft implantation with internal fixation. For elbow reconstruction, arthrodesis, massive prosthesis, or massive allograft is generally used. For reconstruction of the distal radius, we usually perform arthrodesis of the distal radius to the first row of carpal bones. Alternatives include implantation of a vascularized fibular graft and massive allografting for arthrodesis or arthroplasty. After resection of the distal ulna, reconstruction is not necessary. Primary bone malignancies of the hand are more rare; they usually involve metacarpal bones. Conservative resection is rarely feasible, and most patients require complete or partial hand amputation to obtain tumour-free margins.

Effect of VDT Keyboard Height and Inclination on Musculoskeletal Discomfort for Wheelchair Users

This study investigated the effect of keyboard height and inclination on musculoskeletal discomfort for wheelchair users. Eight Taiwanese male wheelchair users (28.75 +/- 8.75 years) were recruited as participants to perform nine experimental combinations of data entry tasks. Three keyboard heights and three inclinations were evaluated. Musculoskeletal discomfort was estimated by Rating of Perceived Exertion and Subjective Preference Ranking. Each subject performed a data entry task for all nine experimental combinations in a random order. The seated posture of all participants during the data entry operation was the upright posture. The height of the screen's center was adjusted according to the eye level of each subject. Analysis showed the keyboard height and keyboard inclination significantly affected rating of musculoskeletal discomfort. It is suggested that the optimum keyboard height choice is elbow-level height or 5 cm below elbow level with the keyboard inclination horizontal to the seat of the wheelchair.

Fracture de tête radiale non synthésable : résection, implant de Swanson ou prothèse ? Étude rétrospective comparative

Treatment of unreconstructible comminuted fractures of the radial head remains a therapeutic challenge. Thirty two patients sustained unreconstructible radial head fracture between 1969 and 1999 and have been treated by resection (16 patients), by Swanson implant (8 patients), or by Judet prosthesis (8 patients). The three groups of patients were reviewed clinically and radiologically by two surgeons not involved in their treatment. Functional outcomes of the elbow (Morrey scoring-SOO scoring system, instability, cubitus valgus) and involvement of the wrist (pain, grasp, RUD instability) were evaluated with a mean follow up of 15 years (6-27.7). Elbow or wrist arthritis, ulnar variance, and evolution of Swanson implants were evaluated on standard radiographs. The Judet prosthesis group was evaluated with DASH scoring. Half of the patients were male and 1/3 had a work-related injury. Regarding the following criteria, there was no significant difference between the resection and the Swanson group: Morrey scoring 77/100, SOO scoring 7.4/11, mean flexion was 130 degrees, mean deficient extension was 18 degrees, mean pronation 60 degrees, mean supination 67 degrees, grasp reached 90% of the controlateral side. Arthritis was noted with the same frequency at the elbow (87%), and wrist levels (66%) in each group. Ninety four percent (94%) of patients in the resection group and 89% in the Swanson group were satisfied. Excellent and good results were reported more frequently in the Swanson group (37% resection group, 51% Swanson group). In the resection group the following complications were significantly more frequent: ulnar nerve irritation (2 x), ulnar head dislocation (2 x), ulnar head instability (3 x), para articular ossification (5 x), ulnar variance positive in all cases (mean value 3.20 mm). In the Swanson group only two implants were found to be destroyed at follow-up. In the prosthesis group function and satisfaction were higher than the two other groups but with a shorter follow up. Excellent and good results were reported in 62.5% cases with a DASH scoring between 0 and 16.7. Comminuted fractures of the radial head treated by resection or Swanson implant are both followed by fair results (same functional scoring). Only the level of complications differs between groups: at elbow level for Swanson group, at wrist level for the resection group. Patients in the Swanson group were most frequently satisfied. Metal radial head implant is an attractive solution yielding good functional outcomes in recent reported limited series and in our personal experience, but with a very short follow-up.

Kinematic strategies for lowering of upper limbs during suggestions of heaviness: a real-simulator design

The aim of the experiment was to study possible differences between the kinematic strategies for the "involuntary" arm lowering of hypnotized highly susceptible subjects (H-Highs) and for the voluntary movement of non-hypnotizable simulators (Sims) during suggestions of arm heaviness (Part I). In addition, a comparison between awake susceptible subjects (W-Highs) and H-Highs was carried out to clarify the specific role of the hypnotic state and hypnotizability (Part II). Subjects' absorption and attentional/imagery capabilities were evaluated through neuropsychological tests. Their arm movements were monitored three-dimensionally at hand, wrist and elbow level through a Polhemus Fastrack system. A final interview collected self-reports concerning the perception of movement involuntariness. Neuropsychological tests showed better "absorption" and imagery capabilities in Highs. In the interview, H-Highs perceived a higher involvement in the task and greater involuntariness and difficulties in contrasting the arm lowering than the Sims. Kinematic analysis showed significant differences between H-Highs and Sims for arm displacements along the vertical axis and on the horizontal plane. In fact, the former lowered the left arm earlier and to a greater degree than the right arm; on the horizontal plane, a forearm flexion was observed for H-Highs on the right side. On comparing W-Highs and H-Highs, hypnosis appeared to magnify the waking motor strategies, but also to induce specific changes, mainly concerning the horizontal plane. These results cannot be interpreted on the basis of "role playing" and socio-cognitive factors. They are believed to be due to a balance between the effectiveness of the frontal executive control towards the selection of behaviors and movement automaticity, which is in line with the neo-dissociation theory of hypnosis.

Upper limb neuropathy in computer operators? A clinical case study of 21 patients.

BackgroundThe character of upper limb disorder in computer operators remains obscure and their treatment and prevention have had limited success. Symptoms tend to be mostly perceived as relating to pathology in muscles, tendons or insertions. However, the conception of a neuropathic disorder would be supported by objective findings reflecting the common complaints of pain, subjective weakness, and numbness/tingling. By examining characteristics in terms of symptoms, signs, and course, this study aimed at forming a hypothesis concerning the nature and consequences of the disorder.MethodsI have studied a consecutive series of 21 heavily exposed and severely handicapped computer-aided designers. Their history was recorded and questionnaire information was collected, encompassing their status 1/2 – 1 1/2 years after the initial clinical contact. The physical examination included an assessment of the following items: Isometric strength in ten upper limb muscles; sensibility in five homonymously innervated territories; and the presence of abnormal tenderness along nerve trunks at 14 locations.ResultsRather uniform physical findings in all patients suggested a brachial plexus neuropathy combined with median and posterior interosseous neuropathy at elbow level. In spite of reduced symptoms at follow-up, the prognosis was serious in terms of work-status and persisting pain.ConclusionsThis small-scale study of a clinical case series suggests the association of symptoms to focal neuropathy with specific locations. The inclusion of a detailed neurological examination would appear to be advantageous with upper limb symptoms in computer operators.

Pronator Syndrome: A Retrospective Study of Median Nerve Entrapment at the Elbow in Female Machine Milkers

Pronator syndrome (median nerve entrapment at the elbow) is a rare condition, but it is more common among women than men. A long-term retrospective follow-up study evaluating the outcome of surgical release of the median nerve for female machine milkers has never been carried out before, nor has a long-term study of non-treated female milkers with pronator syndrome. In the present study, two groups of machine milkers (surgical and non-surgical) were compared. The clinical examination focused on two parameters: focal tenderness and individual muscle strength. The results showed that the surgical group had no focal tenderness on palpation over the median nerve at the elbow and no selective weakness in the muscles examined, as compared to what was found before surgery. In the non-surgical group, focal tenderness was found in 12 out of 14, and 10 out of 14 showed the same weakness as in an earlier examination. While this study has limitations in sample size, surgical release of the median nerve at the elbow level, in cases of pronator syndrome, appears to provide an immediate as well as long-term return to normal strength of FPL and FDP II, along with a significant improvement in subjective status. In the non-surgical group, spontaneous improvement of the strength of FPL and FDP II was found in only four out of the 14 cases.

Surgical outcomes of 654 ulnar nerve lesions.

In this article the authors present a retrospective analysis of 654 surgical outcomes in patients with ulnar nerve entrapments, injuries, and tumors during a 30-year period. Data were gathered between 1968 and 1998 at Louisiana State University Health Sciences Center. Mechanisms of injuries or lesions included 460 entrapments at the elbow level (70%), 76 lacerations (12%), 52 stretches/contusions (8%), 34 fractures/dislocations (5%), 12 gunshot wounds (2%), two injection-induced injuries (0.3%), and 13 nerve sheath tumors (2%). In cases of entrapment, direct operative recordings uniformly demonstrated a slowing of conduction at the elbow, even in cases in which preoperative noninvasive studies had been nondiagnostic. Intraoperative electrical "inching" studies also demonstrated significant conduction abnormalities that lie just proximal to and through the olecranon notch rather than distal, beneath the flexor carpi ulnaris muscle. There were only eight exceptions to this. Lesions not in continuity due to the injury required primary or secondary end-to-end sutures or graft repair. Aided by intraoperative nerve action potential recording, lesions in continuity received either external or internal neurolysis and split repair or resection followed by end-to-end suture or graft repair. Functional recoveries of Grade 3 or better were seen in 81 (92%) of 88 patients who underwent neurolysis, 42 (72%) of 58 patients who received suture repair, and 24 (67%) of 36 patients who received graft repair. Nevertheless, fewer Grade 4 or 5 recoveries were reached than those seen in patients with radial or median nerve injuries. Nerve sheath tumors were resected with preservation of preoperative function in five of seven patients. Although difficult to obtain, useful functional recovery can be achieved with proper surgical management of ulnar nerve entrapments and injuries.

How do anterior/posterior translations of the thoracic cage affect the sagittal lumbar spine, pelvic tilt, and thoracic kyphosis?

Anterior and posterior thoracic cage translations in the sagittal plane have not been reported for their range of motion and effects on the lumbar spine and pelvis. Twenty subjects volunteered for full-spine radiography in neutral, anterior, and posterior thoracic cage translation postures in a standing position. While grasping an anterior vertical pole, with hands at elbow level, subjects were instructed on how to translate their thoracic cage without any flexion/extension, utilizing a full-length mirror. On the radiographs, all four vertebral body corners of T1 through S1 and the superior margin of the acetabulum were digitized. Segmental and global angles of thoracic kyphosis, sagittal lumbar curvature, and pelvic flexion/extension in translation postures were compared to alignment in the neutral posture. Using the femur heads as an origin, the mean range of thoracic cage translation, measured as horizontal movement of T12 from neutral posture, was found to be 85.1 mm anterior and 73 mm posterior. In anterior translation, the thoracic kyphosis is hypokyphotic (Cobb T1-T12 reduced by 16 degrees). In posterior translation, the segmental angles at T12-L1 and L1-L2 flexed, creating an "S" shape in the sagittal lumbar spine, while the thoracic kyphosis increased by 10 degrees. Using posterior tangents from L1 to L5 and T12 to S1, and Cobb angles at T12-S1, the lumbar curve reduced slightly (by less than 3.3 degrees for all global angle measurements) in anterior translation and reduced by 7.4 degrees, 5.7 degrees, and 8.1 degrees respectively in posterior thoracic translation. The angle of pelvic tilt (measured as the angle of intersection of a line through posterior-inferior S1 to the superior acetabulum and the horizontal) reduced by a mean of 15.9 degrees, and Ferguson's sacral base angle to horizontal reduced by a mean of 13.1 degrees in posterior translation. In anterior translation, pelvic tilt and Ferguson's sacral base angle increased by 15.1 degrees and 12.8 degrees, respectively. The findings of this study show that thoracic cage anterior/posterior translations cause significant changes in thoracic kyphosis (26 degrees ), lumbar curve, and pelvic tilt. An understanding of this main motion and consequent coupled movements might aid the understanding of spinal injury kinematics and spinal displacement analysis on full spine lateral radiographs of low back pain and spinal disorder populations.

Upper extremity muscular load during machine milking

Epidemiological studies have shown a high prevalence of wrist and hand disorders associated with machine milking. The occurrence of tingling, numbness and reduced muscle strength indicates peripheral nerve involvement. This has been confirmed by clinical examination revealing median nerve entrapment at the carpal tunnel and/or the elbow level. In a previous study, we showed that machine milking implied high values of dorsiflexion and radial deviation of the wrist, which may be associated with an increased risk of developing such conditions as carpal tunnel syndrom. To evaluate the impact of the muscle tension on the nerve structures bilateral electromyographic recordings (EMG), of the biceps muscle and the flexor and extensor muscles of the forearm were performed in eleven healthy subjects milking both in a traditional and a more modern system. The peak loads for the flexor and extensor muscles were close to their maximum capacity which, in combination with positions and movements of the hand and forearm, might contribute to the development of nerve injuries in addition to other tissue lesions such as tendinitis. Milking in the traditional tethering system was associated with higher peak loads than milking in the more modern loose-housing system. On the other hand, the modern milking system, which had a considerably higher productivity, implied higher “static” load and a lower relative duration of muscular rest, as compared to the traditional system. Relevance to industry Electromyography (EMG) was used to assess the muscular load during milking in two different milking systems. The results of this study will provide the basis for developing new techniques adapted to the demands of the work and antropometrics of the female milkers in order to reduce the risk of injuries in the upper extremity.