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Biomedical subjects

J Fridén

Publications and source records attributed to J Fridén.

At least 19 recordsLinked to original sources
PubMed2006

Activity performance and upper extremity function in cervical spinal cord injury patients according to the Klein-Bell ADL Scale.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: (1) To examine whether the Klein-Bell ADL Scale (K-B Scale) discriminates cervical spinal cord injury (SCI) patients in daily activities and to explore its applicability in this group of patients. (2) To examine the association between basic ADL and upper extremity function. (3) To investigate if grip ability can be discerned in the scale. SETTING: Spinal Cord Injury Unit, Sahlgrenska University Hospital, Göteborg, Sweden. METHODS: Fifty-five patients with cervical SCI with no prior reconstructive hand surgery were included in the study. Analyses of the patient's independence were made according to the K-B Scale. Three additional analyses were carried out, the first examined whether the use of assistive devices and house and car adaptations influenced independence. The last two used different approaches to investigate whether arm and grip function could be detected in the K-B scale. RESULTS: Raw score in the K-B Scale can discriminate for independence in daily activities but the scale's weight scheme does not function for cervical SCI patients. Assistive devices and car and house adaptations can compensate for dependence in daily activities. Lack of grip function decreases the patient's ability to become independent. Diagnosis-related activities cannot be assessed in all items. CONCLUSION: The K-B Scale's raw score was useful assessing daily activities in cervical SCI patients. Its reliability in conjunction with arm and grip function in patients with cervical SCI has yet to be proven.

Activities of Daily Living↗
PubMed2005

[New concepts in reconstruction of arm and hand function in tetraplegia--basic research and clinical application].

Reconstructive hand surgery improves the ability to meet the needs of daily life and the independence of patients who have lost their upper extremity function due to cervical spinal cord injury. Tendon transfer procedures provide the potential to restore key functions, such as elbow and wrist extension or hand grip control, ameliorate joint balance, reduce pain in spasticity and prevent joint contractures. The choice of the optimal donor muscle should be based on a thorough understanding of the biomechanical principles of the muscle-tendon unit. Intraoperative sarcomere length measurements allow to predict and set the optimal muscle-tendon unit length during reconstructive upper extremity surgery in order to prevent overstretch which may lead to insufficient active force generation. Macro-proteins and the extracellular matrix are in charge of the muscle ultrastructure, elasticity and thus passive muscle tension. Spastic muscles are characterized by greater stiffness, a shorter sarcomere length and an extracellular matrix with inferior mechanical properties. Basic science research and clinical studies in cooperation with international centers are of great importance to promote the development of refined techniques of surgical reconstruction and postoperative rehabilitation of upper extremity function in tetraplegic patients.

Arm↗
PubMed2001

Serum creatine kinase level is a poor predictor of muscle function after injury.

Serum creatine kinase and dorsiflexion torque levels were measured in New Zealand White rabbits 1, 2, 7, 14, or 28 days after a single bout of eccentric exercise (n=26). No significant correlation was observed between creatine kinase activity and torque across time periods (P>0.15) and the regression relationship described only about 8% of the experimental variability. These data demonstrate that there exists a poor correlation between serum creatine kinase levels and skeletal muscle function after eccentric exercise.

Animals↗
PubMed2001

Eccentric exercise-induced injuries to contractile and cytoskeletal muscle fibre components.

Exercise involving lengthening of an activated muscle can cause injury. Recent reports documented the mechanics of exercise-induced muscle injury as well as physiological and cellular events and manifestations of injury. Loss of the cytoskeletal protein desmin and loss of cellular integrity as evidenced by sarcolemmal damage occur early during heavy eccentric exercise. These studies indicate that the earliest events in muscle injury are mechanical in nature, while later events indicate that it may be more appropriate to conclude that intense exercise initiates a muscle remodeling process. We conclude that muscle injury after eccentric exercise is differently severe in muscles with different architecture, is fibre type-specific, primarily because of fibre strain in the acute phase, and is exacerbated by inflammation after the initial injury.

Cytoskeleton↗
PubMed2001

Quantitative evaluation of the posterior deltoid to triceps tendon transfer based on muscle architectural properties.

The architectural properties of the posterior deltoid muscle and the 3 heads of the triceps were measured using microdissection techniques to determine whether substitution of triceps function by the posterior deltoid is architecturally appropriate. Muscles from 10 fresh cadaver specimens were fixed by high-pressure perfusion using buffered formaldehyde. Muscle architectural properties, including pennation angle, fiber bundle length, sarcomere length, and physiologic cross-sectional area, were determined. Fiber bundle length varied significantly among the deltoid (123.1 +/- 7.8 mm), medial (64.5 +/- 3.8 mm), lateral (66.5 +/- 5.4 mm), and long (85.3 +/- 9.5) heads of the triceps. The physiologic cross-sectional area of the posterior deltoid was significantly less than the total triceps area and was predicted to provide only approximately 20% of the maximum isometric tension of the combined triceps heads. These data demonstrate that the long fibers of the posterior deltoid render it a very suitable transfer to provide elbow extension because of its tremendous excursion and also show why useful functional results seem relatively independent of posterior deltoid tension at the time of surgery.

Biomechanical Phenomena↗
PubMed2001

Vibration damage to the hand: clinical presentation, prognosis and length and severity of vibration required.

Exposure to vibrating hand-held tools can cause a variety of vascular and neuromuscular symptoms collectively named Hand-Arm Vibration Syndrome (HAVS). The clinical presentation of this syndrome includes paraesthesiae or tingling in digits, pain or tenderness in the wrist and hand, digital blanching, cold intolerance, weakness of the finger flexors or intrinsic muscles and discolouration and trophic skin lesions of the fingers. HAVS can be reversible, at least in the earlier stages, but resolution of symptoms is unusual in more severe cases, and continued use of vibrating tools in such cases is unwise. The duration of exposure needed to produce HAVS cannot be readily defined. This is due not only to different individual susceptibilities to vibration, but also to the different physical characteristics of the vibration exposure. There is a cumulative effect of vibration on both the vascular and sensorineural components of HAVS and these components appear to occur and progress independently of each other.

Arm↗
PubMed2001

Clinical significance of skeletal muscle architecture.

Skeletal muscle architecture is one of the most important properties that determines a muscle's force and excursion capability. In the current review, basic architectural terms first are reviewed and then specific examples relevant to upper extremity anatomy are presented. Specific examples of anatomic considerations required for surgical reconstruction after radial nerve palsy also are detailed. Together, these data show not only the wide variety of architectural designs in human muscles, but the importance of considering architectural design when making surgical decisions.

Biomechanical Phenomena↗
PubMed2001

Biomechanical analysis of the brachioradialis as a donor in tendon transfer.

Anatomic and biomechanical properties of the passive brachioradialis muscle were investigated to understand the limited excursion of this muscle seen during tendon transfer surgery. First, architectural measurements were performed on three fiber bundles obtained from four regions of the brachioradialis (10 specimens) chosen to represent the range of muscle fiber lengths across the brachioradialis. Next, in separate specimens (eight specimens), passive excursion was measured by securing the distal tendon stump to a servomotor. A constant load of 4.9 N was applied to the tendon, while the distal tendon was released from the surrounding tissue in 3-cm increments. Within the four regions studied, muscle fiber length varied significantly from 104.2 +/- 6.2 mm to 179.8 +/- 6.1 mm. As the brachioradialis was released, an average of 3 mm of mobility was obtained for each interval whereas for the succeeding three intervals, an average of 5.3 mm of mobility was obtained. This resulted in 22.2 +/- 2.3 mm of mobility when each specimen was fully released. These data show that there is no intrinsic muscle fiber length limitation to excursion, but that excursion is limited by other intermuscular connections to adjacent connective tissue and other muscles.

Biomechanical Phenomena↗
PubMed2001

Sarcomere number regulation maintained after immobilization in desmin-null mouse skeletal muscle.

The serial sarcomere number of skeletal muscle changes in response to chronic length perturbation. The role of the intermediate filament desmin in regulating these changes was investigated by comparing the architectural adaptations of the tibialis anterior, extensor digitorum longus (EDL) and soleus from wild-type mice with those of homozygous desmin knockout mice after hindlimb immobilization. After 28 days, serial sarcomere number increased significantly in the lengthened wild-type tibialis anterior (by approximately 9%) and EDL (by approximately 17%). Surprisingly, muscles from desmin knockout mice also experienced significant serial remodeling, with the serial sarcomere number of the tibialis anterior increasing by approximately 10% and that of the EDL by approximately 27%. A consistent result was observed in the shortened soleus: a significant decrease in sarcomere number was observed in the muscles from both wild-type (approximately 26%) and knockout (approximately 12%) mice. Thus, although desmin is not essential for sarcomerogenesis or sarcomere subtraction in mouse hindlimb muscles, the results do suggest subtle differences in the nature of sarcomere number adaptation. We speculate that desmin may play a role in regulating the optimal arrangement of sarcomeres within the muscle or in sensing the magnitude of the immobilization effect itself.

Animals↗
PubMed2000

[Hand transplantation and implantation of nerve chips. New developments within hand surgery].

Injuries and diseases of the hand naturally have an enormous impact on hand function and on quality of life, both occupational and social. The majority of hand-injury patients are under 30 years of age. Hand surgery, an established specialty in Sweden since 1969, is of great importance in terms of clinical developments, education and research. In the coming decade, scientific and clinical advances are to be expected in several fields such as nerve injuries including brachial plexus lesion, microsurgery, flexor tendon injuries and tendon transfer. Bioimplant research and new advances at the biotechnological interface will yield new options in nerve reconstruction, microchip implants in the nervous system, and the restoration of muscle-tendon function following injury. Artificial limbs with advanced motor and sensory functions will be important future aids in the rehabilitation of amputees. Transplantation of human hands is another promising reconstructive procedure which may open iup new perspectives in the coming millennium.

Amputation, Surgical↗
PubMed2000

Functional and clinical significance of skeletal muscle architecture.

Skeletal muscle architecture is the structural property of whole muscles that dominates their function. This review describes the basic architectural properties of human upper and lower extremity muscles. The designs of various muscle groups in humans and other species are analyzed from the point of view of optimizing function. Muscle fiber arrangement and motor unit arrangement is discussed in terms of the control of movement. Finally, the ability of muscles to change their architecture in response to immobilization, eccentric exercise, and surgical tendon transfer is reviewed. Future integrative physiological studies will provide insights into the mechanisms by which such adaptations occur. It is likely that muscle fibers transduce both stress and strain and respond by modifying sarcomere number in a way more suited to the new biomechanical environment.

Electromyography↗
PubMed2000

The influences of muscle fibre proportions and areas upon EMG during maximal dynamic knee extensions.

This study is an investigation of the relationship between muscle morphology and surface electromyographic (EMG) parameters [mean frequency of the power spectrum (MNF), signal amplitude (root mean square, RMS) and the signal amplitude ratio (SAR; i.e. the ratio between the RMS level during the passive part of the contraction cycle and the RMS level during the active part of the contraction cycle)] during 100 maximal dynamic knee extensions at 90 degrees. s(-1). Each contraction cycle comprised of 1 s of active knee extension and 1 s of passive knee flexion. The surface EMG was recorded from the vastus lateralis muscle. Twenty clinically healthy subjects participated in the study, and muscle biopsy samples of the vastus lateralis were obtained from 19 of those subjects. The relationships between muscle morphology and EMG were investigated at three stages of the test: initially, during the fatigue phase (initial 40 contractions), and at the endurance level (the final 50 contractions). Major findings on correlations are that SAR and MNF tended to correlate positively with the proportion of type 1 fibres, and RMS correlated positively with the proportion of type 2 muscle fibres. The muscle fibre areas showed little correlation with the EMG variables under investigation. The results of the present study showed that the three EMG variables of a dynamic endurance test that were investigated (RMS, MNF and SAR) were clearly correlated with the proportions of the different fibre types, but only to a small extent with fibre areas. These findings contradict some of the theoretical models of the EMG, especially for parameters in the frequency domain.

Adult↗
PubMed2000

Intramuscular pressure and electromyographic responses of the vastus lateralis muscle during repeated maximal isokinetic knee extensions.

The purpose of the study was to investigate changes in intramuscular pressure (IMP) (maximal during contraction - peak IMP, and between contraction, relaxation IMP - RxIMP) and surface electromyographic activity (EMG) parameters [mean frequency of the power spectrum (fmean), and signal amplitude, root mean square (RMS)] throughout 100 repetitive isokinetic contractions for six healthy subjects. Parameters were recorded simultaneously from the vastus lateralis muscle during maximal knee extension. Regression analyses revealed significant decreases for peak IMP and fmean, and an increase in RxIMP; RMS, however, did not change. All parameters demonstrated trends of change throughout the contractions that were non-linear. Details and inter relations for RxIMP and fmean were highlighted to express intramuscular fluid accumulation and fatigue development, respectively. Individual regression analyses for RxIMP revealed significant positive correlations for all subjects (range of r=0.62 to 0.89). At group level, mean RxIMP increased from 6.0 mmHg for the 1st contraction to 14.0 mmHg for the 100th contraction. For fmean, individual regressions were significantly negative for all subjects (r=-0.75 to -0.89). Fmean decreased from 89.2 Hz for the 1st contraction to 63.3 Hz for the 100th contraction. When the data were delineated between the fatigue (contractions 1-40) and endurance phases (41-100), the slopes of increase for RxIMP, and of decrease for fmean were significantly greater during the fatigue phase. RxIMP throughout the 100 contractions correlated negatively with fmean for each subject (r=-0.54 to -0.78); when delineated, the correlation between parameters was significantly greater for the fatigue as compared with the endurance phase. Relaxation IMP trends are mainly attributed to intramuscular water accumulations during repetitive contractions. In spite of consistent correlations between RxIMP and fmean a causal association could not be established. It may be suggested that a common factor occurring during the fatiguing process governs changes in RxIMP and fmean.

Adult↗
PubMed2000

Effect of muscle tension during tendon transfer on sarcomerogenesis in a rabbit model.

Sarcomere number change was investigated in an animal model of tendon transfer. In 9 adult New Zealand white rabbits, the flexor digitorum longus muscle was cut distally and transferred and woven into the tibialis anterior tendon. Ankles were then immobilized for 3 weeks in 75 degrees flexion. Transferred flexor digitorum longus muscles were harvested and complete architectural analysis was performed. Sarcomere lengths were measured using laser diffraction. Serial sarcomere number in transferred flexor digitorum longus fibers was a strong function of the sarcomere length at the time of transfer. A highly significant negative correlation between these 2 parameters was approximated by a linear relationship. Based on this finding, we conclude that serial sarcomere number is significantly affected by the degree of stretch during the transfer itself. This could easily compromise the purpose of surgical tendon transfer by reducing the procedure to little more than a tenodesis. (J Hand Surg 2000; 25A:138-143.

Analysis of Variance↗
PubMed2000

Protection of the deltoid to triceps tendon transfer repair sites.

The posterior deltoid muscle was used to replace lost elbow extension in 11 patients with C5 or C6 level tetraplegia. During surgery stainless steel sutures were inserted into the donor muscle, graft, and tendon insertion sites. Over the succeeding time periods (1 month to 2 years) the distances between the various markers were measured. Significant tendon elongation of 23.1 +/- 4.8 mm (mean +/- SEM; n = 6) was observed in patients receiving traditional postoperative care. To reduce the tendon elongation observed, a specially designed armrest was developed and applied the first postoperative day. The armrest was designed to maintain the elbow in 20 degrees flexion and to prevent shoulder adduction. The addition of this armrest to the traditional postoperative protocol resulted in a dramatic decrease of tendon elongation to only 8.4 +/- 3.0 mm (n = 5). Elongation occurred within the first 6 postoperative weeks in the armrest group; in the nonprotected group, elongation continued for several additional months. The majority of the elongation in both groups occurred in the proximal portion of the tendon-graft-tendon unit. Although this study did not explicitly measure strength, we conclude that preventing excessive muscle length change is required to protect repair sites in posterior deltoid to triceps transfer. (J Hand Surg 2000; 25A:144-149.

Adult↗
PubMed2000

Desmin knockout muscles generate lower stress and are less vulnerable to injury compared with wild-type muscles.

The functional role of the skeletal muscle intermediate filament system was investigated by measuring the magnitude of muscle force loss after cyclic eccentric contraction (EC) in normal and desmin null mouse extensor digitorum longus muscles. Isometric stress generated was significantly greater in wild-type (313 +/- 8 kPa) compared with knockout muscles (276 +/- 13 kPa) before EC (P < 0.05), but 1 h after 10 ECs, both muscle types generated identical levels of stress ( approximately 250 kPa), suggesting less injury to the knockout. Differences in injury susceptibility were not explained by the different absolute stress levels imposed on wild-type versus knockout muscles (determined by testing older muscles) or by differences in fiber length or mechanical energy absorbed. Morphometric analysis of longitudinal electron micrographs indicated that Z disks from knockout muscles were more staggered (0.36 +/- 0. 03 microm) compared with wild-type muscles (0.22 +/- 0.03 microm), which may indicate that the knockout cytoskeleton is more compliant. These data demonstrate that lack of the intermediate filament system decreases isometric stress production and that the desmin knockout muscle is less vulnerable to mechanical injury.

Age Factors↗
PubMed1999

[Hand transplantation and implantation of nerve chips. New developments within hand surgery].

Injuries and diseases of the hand naturally have an enormous impact on hand function and on quality of life, both occupational and social. The majority of hand-injury patients are under 30 years of age. Hand surgery, an established specialty in Sweden since 1969, is of great importance in terms of clinical developments, education and research. In the coming decade, scientific and clinical advances are to be expected in several fields such as nerve injuries including brachial plexus lesion, microsurgery, flexor tendon injuries and tendon transfer. Bioimplant research and new advances at the biotechnological interface will yield new options in nerve reconstruction, microchip implants in the nervous system, and the restoration of muscle-tendon function following injury. Artificial limbs with advanced motor and sensory functions will be important future aids in the rehabilitation of amputees. Transplantation of human hands is another promising reconstructive procedure which may open up new perspectives in the coming millennium.

Amputation, Surgical↗