Revision total elbow replacement using the Souter-Strathclyde prosthesis.
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The Souter-Strathclyde prosthesis was used in 52 evisions of total elbow replacements (TERs) between August 1986 and May 1997. Of these, 50, carried out in 45 patients, were prospectively followed for a mean of 53 months (14 to 139). The procedure produced reliable relief of pain, and the range of movement was preserved. There was a considerable incidence of adverse events associated with revision (30%), and 12 further procedures have been required. Nonetheless, a revision is the preferred salvage procedure for failed primary arthroplasty in the absence of sepsis. (+info)
Treatment of severe osteochondritis dissecans of the elbow using osteochondral grafts from a rib.
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We treated a patient with extensive osteochondritis dissecans of the elbow by an osteochondral graft from a rib. It had consolidated seven months after operation. When seen at follow-up, after seven years and eight months, the elbow was free from pain with an improvement in the range of movement of 24 degrees. (+info)
Anthropometry and clinical features of Kashin-Beck disease in central Tibet.
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We compared two different populations living in central Tibet with the purpose of establishing standard values for different anthropometric parameters in a rural population. Later on, these values were used as references for a similar study on a KBD population. One group (KBD) (n=1,246) came from the endemic areas, and the other group, serving as the control population (n=815), came from non-endemic areas. Both groups included children and adults and were of the Mongoloid type; they were farmers or semi-nomads. Height, weight, segment length, joint perimeter, joint diameter, joint movement were recorded. Also more subjective information such as general feeling of tiredness, rapid fatigue at work, work limitation, joint pain, muscle weakness, muscular atrophy, dwarfism, flatfoot, and waddling gate was also collected. Those variables were compared between the two groups. (+info)
Normalized force, activation, and coactivation in the arm muscles of young and old men.
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The purpose of this study was to determine whether the loss of muscle strength in the elderly could be explained entirely by a decline in the physiological cross-sectional area (PCSA) of muscle. Isometric force, muscle activation (twitch interpolation), and coactivation (surface electromyograph) were measured during maximal voluntary contractions (MVCs) of the elbow flexors (EFs) and extensors (EEs) in 20 young (23 +/- 3 yr) and 13 older (81 +/- 6 yr) healthy men. PCSA was determined using magnetic resonance imaging, and normalized force (NF) was calculated as the MVC/PCSA ratio. The PCSA was smaller in the old compared with the young men, more so in the EEs (28%) compared with the EFs (19%) (P < 0.001); however, the decline in MVC (approximately 30%) with age was similar in the two muscle groups. Muscle activation was not different between the groups, but coactivation was greater (5%) (P < 0.001) in the old men for both muscles. NF was less (11%) in the EFs (P < 0.01) and tended to be unchanged in the EEs of the old compared with young subjects. The relative maintenance of NF in the EEs compared with the EFs may be related to age-associated changes in the architecture of the triceps brachii muscle. In conclusion, although the decline in PCSA explained the majority of strength loss in the old men, additional factors such as greater coactivation or reduced specific tension also may have contributed to the age-related loss of isometric strength. (+info)
Which primary shoulder and elbow replacement? A review of the results of prostheses available in the UK.
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To assist surgeons select a suitable prosthesis, we have undertaken a detailed review of all shoulder and elbow replacements currently marketed in the UK. Twenty shoulder and 8 elbow implants, manufactured by 16 companies, have been identified. Twelve of the shoulder and one of the elbow implants have been introduced or modified in the last 8 years and have no clinical results published in peer-reviewed journals. Only the Biomodular, Bipolar, Copeland, Isoelastic, Neer hemi, Neer II, Roper-Day and Select shoulders accounting for less than 40% of the UK shoulder market, possess published results. The Capitello-condylar, Coonrad-Morrey, GSB III, Kudo, Liverpool, Roper-Tuke and Souter-Strathclyde elbows all have published results. These account for over 95% of all UK elbow replacements. The implications of these findings in an era of evidence-based medicine is discussed. Reviewing the clinical results should be of primary importance in the selection of a suitable prosthesis. Implants with a proven long-term record must represent the 'gold standard'. New or modified implants should only be used if they are part of a properly conducted clinical trial. (+info)
Reflex and intrinsic changes induced by fatigue of human elbow extensor muscles.
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Fatigue-induced changes in intrinsic and reflex properties of human elbow extensor muscles and the underlying mechanisms for fatigue compensation were investigated. The elbow joint was perturbed using small-amplitude and pseudorandom movement patterns while subjects maintained steady levels of mean joint extension torque. Intrinsic and reflex properties were identified simultaneously using a nonlinear delay differential equation model. Intrinsic joint properties were characterized by measures of joint stiffness, viscous damping, and limb inertia and reflex properties characterized by measures of dynamic and static reflex gains. Fatigue was induced using 15 min of intermittent voluntary isometric (submaximal) exercise, and a rest period of 10 min was taken to allow the fatigued muscles to recover from acute fatigue effects. Identical experimental and data analysis procedures were used before and after fatigue. Our findings were that after fatigue, joint stiffness was significantly reduced at higher torque levels, presumably reflecting the reduced force-generating capacity of fatigued muscles. Conversely, joint viscosity was increased after fatigue potentially because of the reduced crossbridge detachment rate and prolonged relaxation associated with intracellular acidosis accompanying fatigue. Static stretch reflex gain decreased significantly at higher torque levels after fatigue, indicating that the isometric fatiguing exercise might be associated with a preferential change in properties of spindle chain fibers and bag(2) fibers. For matched pre- and postfatigue torque levels, dynamic reflexes contributed relatively more torque after fatigue, displaying higher dynamic reflex gains and larger dynamic electromyographic responses elicited by the controlled small-amplitude position perturbations. These changes appear to counteract the fatigue-induced reductions in joint stiffness and static reflex gain. The compensatory responses could be partly due to the effects of increasing the number of active motoneurons innervating the fatiguing muscles. This shift in operating point gave rise to significant compensation for the loss of contractile force. The compensation could also be due to fusimotor adjustment, which could make the dynamic reflex gain much less sensitive to fatigue than intrinsic stiffness. In short, the reduced contribution from intrinsic stiffness to joint torque was compensated by increased contribution from dynamic stretch reflexes after fatigue. (+info)
Unexpected reflex response to transmastoid stimulation in human subjects during near-maximal effort.
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1. In human subjects, a high-voltage electrical pulse between electrodes fixed over the mastoid processes activates descending tract axons at the level of the cervico-medullary junction to produce motor responses (cevicomedullary evoked responses; CMEPs) in the biceps brachii and brachioradialis muscles. 2. During isometric maximal voluntary contractions (MVCs) of the elbow flexors, CMEPs in the biceps brachii and brachioradialis muscles are sometimes followed by a second compound muscle action potential. This response can be observed in single trials (amplitude of up to 60 % of the maximal M wave) and follows the CMEP by about 16 ms in both muscles. The response only occurs during very strong voluntary contractions. 3. The second response following transmastoid stimulation appears with stimulation intensities that are at the threshold for evoking a CMEP in the contracting muscles. The response grows with increasing stimulus intensity, but then decreases in amplitude and finally disappears at high stimulation intensities. 4. A single stimulus to the brachial plexus during MVCs can also elicit a second response (following the M wave) in the biceps brachii and brachioradialis muscles. The latency of this response is 3-4 ms longer than that of the second response observed following transmastoid stimulation. This difference in latency is consistent with a reflex response to stimulation of large-diameter afferents. 5. The amplitude of the second response to transmastoid stimulation can be reduced by appropriately timed subthreshold transcranial magnetic stimuli. This result is consistent with intracortical inhibition of the response. 6. We suggest that transmastoid stimulation can elicit a large transcortical reflex response in the biceps brachii and brachioradialis muscles. The response travels via the motor cortex but is only apparent during near-maximal voluntary efforts. (+info)
Greater movement-related cortical potential during human eccentric versus concentric muscle contractions.
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Despite abundant evidence that different nervous system control strategies may exist for human concentric and eccentric muscle contractions, no data are available to indicate that the brain signal differs for eccentric versus concentric muscle actions. The purpose of this study was to evaluate electroencephalography (EEG)-derived movement-related cortical potential (MRCP) and to determine whether the level of MRCP-measured cortical activation differs between the two types of muscle activities. Eight healthy subjects performed 50 voluntary eccentric and 50 voluntary concentric elbow flexor contractions against a load equal to 10% body weight. Surface EEG signals from four scalp locations overlying sensorimotor-related cortical areas in the frontal and parietal lobes were measured along with kinetic and kinematic information from the muscle and joint. MRCP was derived from the EEG signals of the eccentric and concentric muscle contractions. Although the elbow flexor muscle activation (EMG) was lower during eccentric than concentric actions, the amplitude of two major MRCP components-one related to movement planning and execution and the other associated with feedback signals from the peripheral systems-was significantly greater for eccentric than for concentric actions. The MRCP onset time for the eccentric task occurred earlier than that for the concentric task. The greater cortical signal for eccentric muscle actions suggests that the brain probably plans and programs eccentric movements differently from concentric muscle tasks. (+info)