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Haruo Tsuji - One of the best experts on this subject based on the ideXlab platform.

  • Back Muscle injury after posterior lumbar spine surgery topographic evaluation of intramuscular pressure and blood flow in the porcine Back Muscle during surgery
    Spine, 1996
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Shoji Yabuki, Jorma Styf, Kjell Olmarker, Bjorn Rydevik, Haruo Tsuji
    Abstract:

    STUDY DESIGN: Intramuscular pressure and blood flow of the Back Muscles were evaluated topographically during posterior lumbar spine surgery. The topographic damage of the Back Muscle after surgery was studied. OBJECTIVE: To investigate the relationship between intramuscular pressure or blood flow during posterior lumbar surgery and the Back Muscle injury after surgery. SUMMARY OF BackGROUND DATA: Latrogenic Back Muscle injury in an animal and human model has been reported previously. Changes of intramuscular pressure and blood flow during surgery might be related to the Muscle injury. No previous study on this issue has been published. METHODS: The contact pressure between the retractor blade and Muscle tissue was monitored in 10 pigs during posterior surgery of the lumbar spine. On one side, intramuscular pressure at 5, 10, and 20 mm lateral to the retractor and on the other side blood flow of the Back Muscle at 5 and 20 mm during surgery were measured. Histologic changes of the Back Muscle at 5, 10, and 20 mm to the midline were evaluated 3 hours after surgery. RESULTS: The contact pressure decreased exponentially with time. Intramuscular pressure 5 mm lateral to the retractor was 114 +/- 31 mm Hg and was significantly higher than at 10 mm and 20 mm. Blood flow markedly decreased during surgery and recovered incompletely after releasing the retractor at 5 mm and 20 mm lateral to the retractor. Blood flow at 5 mm was significantly lower than at 20 mm throughout surgery. The Muscle damage 3 hours after surgery was more severe near the retractor blade. CONCLUSIONS: The Back Muscles were exposed to pathophysiologic condition by a retractor during posterior lumbar spine surgery. External compression by a retractor increases intramuscular pressure to levels that impede local Muscle blood flow. The Muscle degeneration after surgery could be explained by direct mechanical damage and by the increased intramuscular pressure of Muscle tissue by the retractor.

  • Back Muscle injury after posterior lumbar spine surgery a histologic and enzymatic analysis
    Spine, 1996
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    Study Design. Back Muscle injury after posterior lumbar surgery was studied by Muscle histology and serum creatine phosphokinase MM isoenzyme activity. Objectives. To investigate intraoperative factors influencing the magnitude of Back Muscle injury after posterior lumbar surgery. Summary of Background Data. The authors previously have reported iatrogenic Back Muscle injury in an animal model and in humans. Serious injury of the Back Muscle has been shown by short-term and longterm follow-up evaluation. Methods. The retraction pressure was monitored, and the retraction pressure-time products were calculated in 24 patients. Early histologic changes of multifidus Muscle, which were taken at completion of surgery, and serum creatine phosphokinase MM isoenzyme activity changes were examined. Results. The magnitude of Back Muscle injury was significant as the pressure-time product increased. Creatine phosphokinase MM isoenzyme activity increased after surgery and reached a plateau 1 day after surgery, followed by recovery to the normal value 1 week after surgery. Creatine phosphokinase MM isoenzyme activity tended to be high in cases with multilevel exposure and with high pressure-time product. Conclusions. Back Muscle injury occurs in all patients who underwent posterior lumbar surgery, and these injuries are related to the retraction pressure, time, and extent of exposure.

  • Back Muscle injury after posterior lumbar spine surgery part 2 histologic and histochemical analyses in humans
    Spine, 1994
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    STUDY DESIGN: Back Muscle injury caused by retractor application during posterior spine surgery in rats was examined histologically and histochemically according to the postoperative time with reference to the retraction time-pressure relationship. OBJECTIVES: The results were correlated to provide the risk factors for Back Muscle injury during posterior spine surgery. SUMMARY OF BackGROUND DATA: Back Muscles were examined histologically and histochemically after application of quantitative pressure and retraction time. No previous study has assessed this relationship. METHODS: Five groups were studied: Group 1, 1-hour low-pressure load group; Group 2, 1-hour high-pressure load group; Group 3, 3-hour low-pressure load group; Group 4, 3-hour high-pressure load group; and sham group. In each group, the multifidus Muscle was evaluated 3 hours, 48 hours, 1 week, 3 weeks, and 6 weeks after surgery. RESULTS: In all groups except the sham group, degeneration of the Muscle and neuromuscular junction was found at a very early postoperative time, but regeneration began at 1 week, and recovery was attained by 6 weeks. The extent of Muscle fiber necrosis and the severity of degeneration of the neuromuscular junctions showed a parallelism with the magnitude of the pressure load and retraction time. As the duration and pressure load increased, the time required for regeneration also increased. The fiber type grouping in group 3 and 4 was consistent with the severity of degeneration of neuromuscular junctions. CONCLUSIONS: The muscular degeneration and the regeneration was largely dependent on the retraction pressure-time product. These results suggest that denervation Muscle injuries are likely secondary responses to Muscle retraction injury in any case of posterior spine surgery.

  • Back Muscle injury after posterior lumbar spine surgery part 2
    Spine, 1994
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    Study Design The histologic and histochemical changes in Back Muscle were studied in virgin surgery patients with lumbar spine disorders and in patients who underwent repeat posterior lumbar surgery. Objectives The results were correlated to provide the evidences of histologic changes of Back Muscle after posterior lumbar surgery. Summary of Background Data Back Muscles were examined histologically and histochemically after posterior lumbar surgery. No previous study has assessed these changes. Methods Back Muscles were obtained before and after retraction from 18 virgin surgery cases with lumbar spine disorders. In four patients, the retraction pressure was monitored and the retraction pressure-time products ([P][T]) were calculated. In 21 repeat lumbar surgery cases, Muscle samples were obtained before Muscle retraction. Samples were evaluated by histologic and histochemical methods. Results Abnormal findings were slight in virgin surgery cases. Early Back Muscle injury tended to depend on operation time and ([P][T]) products. Late Back Muscle injury in reoperated patients was marked. Various types of neurogenic changes were observed more than 10 months after the first operation. Conclusions Histologic damages of Back Muscle due to previous surgical intervention were long-lasting. To avoid permanent Muscle injury, the retraction time and pressure should be shortened or the pressure on the Back Muscle should be monitored during posterior surgery.

Yoshiharu Kawaguchi - One of the best experts on this subject based on the ideXlab platform.

  • Back Muscle injury after posterior lumbar spine surgery topographic evaluation of intramuscular pressure and blood flow in the porcine Back Muscle during surgery
    Spine, 1996
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Shoji Yabuki, Jorma Styf, Kjell Olmarker, Bjorn Rydevik, Haruo Tsuji
    Abstract:

    STUDY DESIGN: Intramuscular pressure and blood flow of the Back Muscles were evaluated topographically during posterior lumbar spine surgery. The topographic damage of the Back Muscle after surgery was studied. OBJECTIVE: To investigate the relationship between intramuscular pressure or blood flow during posterior lumbar surgery and the Back Muscle injury after surgery. SUMMARY OF BackGROUND DATA: Latrogenic Back Muscle injury in an animal and human model has been reported previously. Changes of intramuscular pressure and blood flow during surgery might be related to the Muscle injury. No previous study on this issue has been published. METHODS: The contact pressure between the retractor blade and Muscle tissue was monitored in 10 pigs during posterior surgery of the lumbar spine. On one side, intramuscular pressure at 5, 10, and 20 mm lateral to the retractor and on the other side blood flow of the Back Muscle at 5 and 20 mm during surgery were measured. Histologic changes of the Back Muscle at 5, 10, and 20 mm to the midline were evaluated 3 hours after surgery. RESULTS: The contact pressure decreased exponentially with time. Intramuscular pressure 5 mm lateral to the retractor was 114 +/- 31 mm Hg and was significantly higher than at 10 mm and 20 mm. Blood flow markedly decreased during surgery and recovered incompletely after releasing the retractor at 5 mm and 20 mm lateral to the retractor. Blood flow at 5 mm was significantly lower than at 20 mm throughout surgery. The Muscle damage 3 hours after surgery was more severe near the retractor blade. CONCLUSIONS: The Back Muscles were exposed to pathophysiologic condition by a retractor during posterior lumbar spine surgery. External compression by a retractor increases intramuscular pressure to levels that impede local Muscle blood flow. The Muscle degeneration after surgery could be explained by direct mechanical damage and by the increased intramuscular pressure of Muscle tissue by the retractor.

  • Back Muscle injury after posterior lumbar spine surgery a histologic and enzymatic analysis
    Spine, 1996
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    Study Design. Back Muscle injury after posterior lumbar surgery was studied by Muscle histology and serum creatine phosphokinase MM isoenzyme activity. Objectives. To investigate intraoperative factors influencing the magnitude of Back Muscle injury after posterior lumbar surgery. Summary of Background Data. The authors previously have reported iatrogenic Back Muscle injury in an animal model and in humans. Serious injury of the Back Muscle has been shown by short-term and longterm follow-up evaluation. Methods. The retraction pressure was monitored, and the retraction pressure-time products were calculated in 24 patients. Early histologic changes of multifidus Muscle, which were taken at completion of surgery, and serum creatine phosphokinase MM isoenzyme activity changes were examined. Results. The magnitude of Back Muscle injury was significant as the pressure-time product increased. Creatine phosphokinase MM isoenzyme activity increased after surgery and reached a plateau 1 day after surgery, followed by recovery to the normal value 1 week after surgery. Creatine phosphokinase MM isoenzyme activity tended to be high in cases with multilevel exposure and with high pressure-time product. Conclusions. Back Muscle injury occurs in all patients who underwent posterior lumbar surgery, and these injuries are related to the retraction pressure, time, and extent of exposure.

  • Back Muscle injury after posterior lumbar spine surgery part 2 histologic and histochemical analyses in humans
    Spine, 1994
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    STUDY DESIGN: Back Muscle injury caused by retractor application during posterior spine surgery in rats was examined histologically and histochemically according to the postoperative time with reference to the retraction time-pressure relationship. OBJECTIVES: The results were correlated to provide the risk factors for Back Muscle injury during posterior spine surgery. SUMMARY OF BackGROUND DATA: Back Muscles were examined histologically and histochemically after application of quantitative pressure and retraction time. No previous study has assessed this relationship. METHODS: Five groups were studied: Group 1, 1-hour low-pressure load group; Group 2, 1-hour high-pressure load group; Group 3, 3-hour low-pressure load group; Group 4, 3-hour high-pressure load group; and sham group. In each group, the multifidus Muscle was evaluated 3 hours, 48 hours, 1 week, 3 weeks, and 6 weeks after surgery. RESULTS: In all groups except the sham group, degeneration of the Muscle and neuromuscular junction was found at a very early postoperative time, but regeneration began at 1 week, and recovery was attained by 6 weeks. The extent of Muscle fiber necrosis and the severity of degeneration of the neuromuscular junctions showed a parallelism with the magnitude of the pressure load and retraction time. As the duration and pressure load increased, the time required for regeneration also increased. The fiber type grouping in group 3 and 4 was consistent with the severity of degeneration of neuromuscular junctions. CONCLUSIONS: The muscular degeneration and the regeneration was largely dependent on the retraction pressure-time product. These results suggest that denervation Muscle injuries are likely secondary responses to Muscle retraction injury in any case of posterior spine surgery.

  • Back Muscle injury after posterior lumbar spine surgery part 2
    Spine, 1994
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    Study Design The histologic and histochemical changes in Back Muscle were studied in virgin surgery patients with lumbar spine disorders and in patients who underwent repeat posterior lumbar surgery. Objectives The results were correlated to provide the evidences of histologic changes of Back Muscle after posterior lumbar surgery. Summary of Background Data Back Muscles were examined histologically and histochemically after posterior lumbar surgery. No previous study has assessed these changes. Methods Back Muscles were obtained before and after retraction from 18 virgin surgery cases with lumbar spine disorders. In four patients, the retraction pressure was monitored and the retraction pressure-time products ([P][T]) were calculated. In 21 repeat lumbar surgery cases, Muscle samples were obtained before Muscle retraction. Samples were evaluated by histologic and histochemical methods. Results Abnormal findings were slight in virgin surgery cases. Early Back Muscle injury tended to depend on operation time and ([P][T]) products. Late Back Muscle injury in reoperated patients was marked. Various types of neurogenic changes were observed more than 10 months after the first operation. Conclusions Histologic damages of Back Muscle due to previous surgical intervention were long-lasting. To avoid permanent Muscle injury, the retraction time and pressure should be shortened or the pressure on the Back Muscle should be monitored during posterior surgery.

Virny Dwiya Lestari - One of the best experts on this subject based on the ideXlab platform.

Hisao Matsui - One of the best experts on this subject based on the ideXlab platform.

  • Back Muscle injury after posterior lumbar spine surgery topographic evaluation of intramuscular pressure and blood flow in the porcine Back Muscle during surgery
    Spine, 1996
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Shoji Yabuki, Jorma Styf, Kjell Olmarker, Bjorn Rydevik, Haruo Tsuji
    Abstract:

    STUDY DESIGN: Intramuscular pressure and blood flow of the Back Muscles were evaluated topographically during posterior lumbar spine surgery. The topographic damage of the Back Muscle after surgery was studied. OBJECTIVE: To investigate the relationship between intramuscular pressure or blood flow during posterior lumbar surgery and the Back Muscle injury after surgery. SUMMARY OF BackGROUND DATA: Latrogenic Back Muscle injury in an animal and human model has been reported previously. Changes of intramuscular pressure and blood flow during surgery might be related to the Muscle injury. No previous study on this issue has been published. METHODS: The contact pressure between the retractor blade and Muscle tissue was monitored in 10 pigs during posterior surgery of the lumbar spine. On one side, intramuscular pressure at 5, 10, and 20 mm lateral to the retractor and on the other side blood flow of the Back Muscle at 5 and 20 mm during surgery were measured. Histologic changes of the Back Muscle at 5, 10, and 20 mm to the midline were evaluated 3 hours after surgery. RESULTS: The contact pressure decreased exponentially with time. Intramuscular pressure 5 mm lateral to the retractor was 114 +/- 31 mm Hg and was significantly higher than at 10 mm and 20 mm. Blood flow markedly decreased during surgery and recovered incompletely after releasing the retractor at 5 mm and 20 mm lateral to the retractor. Blood flow at 5 mm was significantly lower than at 20 mm throughout surgery. The Muscle damage 3 hours after surgery was more severe near the retractor blade. CONCLUSIONS: The Back Muscles were exposed to pathophysiologic condition by a retractor during posterior lumbar spine surgery. External compression by a retractor increases intramuscular pressure to levels that impede local Muscle blood flow. The Muscle degeneration after surgery could be explained by direct mechanical damage and by the increased intramuscular pressure of Muscle tissue by the retractor.

  • Back Muscle injury after posterior lumbar spine surgery a histologic and enzymatic analysis
    Spine, 1996
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    Study Design. Back Muscle injury after posterior lumbar surgery was studied by Muscle histology and serum creatine phosphokinase MM isoenzyme activity. Objectives. To investigate intraoperative factors influencing the magnitude of Back Muscle injury after posterior lumbar surgery. Summary of Background Data. The authors previously have reported iatrogenic Back Muscle injury in an animal model and in humans. Serious injury of the Back Muscle has been shown by short-term and longterm follow-up evaluation. Methods. The retraction pressure was monitored, and the retraction pressure-time products were calculated in 24 patients. Early histologic changes of multifidus Muscle, which were taken at completion of surgery, and serum creatine phosphokinase MM isoenzyme activity changes were examined. Results. The magnitude of Back Muscle injury was significant as the pressure-time product increased. Creatine phosphokinase MM isoenzyme activity increased after surgery and reached a plateau 1 day after surgery, followed by recovery to the normal value 1 week after surgery. Creatine phosphokinase MM isoenzyme activity tended to be high in cases with multilevel exposure and with high pressure-time product. Conclusions. Back Muscle injury occurs in all patients who underwent posterior lumbar surgery, and these injuries are related to the retraction pressure, time, and extent of exposure.

  • Back Muscle injury after posterior lumbar spine surgery part 2 histologic and histochemical analyses in humans
    Spine, 1994
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    STUDY DESIGN: Back Muscle injury caused by retractor application during posterior spine surgery in rats was examined histologically and histochemically according to the postoperative time with reference to the retraction time-pressure relationship. OBJECTIVES: The results were correlated to provide the risk factors for Back Muscle injury during posterior spine surgery. SUMMARY OF BackGROUND DATA: Back Muscles were examined histologically and histochemically after application of quantitative pressure and retraction time. No previous study has assessed this relationship. METHODS: Five groups were studied: Group 1, 1-hour low-pressure load group; Group 2, 1-hour high-pressure load group; Group 3, 3-hour low-pressure load group; Group 4, 3-hour high-pressure load group; and sham group. In each group, the multifidus Muscle was evaluated 3 hours, 48 hours, 1 week, 3 weeks, and 6 weeks after surgery. RESULTS: In all groups except the sham group, degeneration of the Muscle and neuromuscular junction was found at a very early postoperative time, but regeneration began at 1 week, and recovery was attained by 6 weeks. The extent of Muscle fiber necrosis and the severity of degeneration of the neuromuscular junctions showed a parallelism with the magnitude of the pressure load and retraction time. As the duration and pressure load increased, the time required for regeneration also increased. The fiber type grouping in group 3 and 4 was consistent with the severity of degeneration of neuromuscular junctions. CONCLUSIONS: The muscular degeneration and the regeneration was largely dependent on the retraction pressure-time product. These results suggest that denervation Muscle injuries are likely secondary responses to Muscle retraction injury in any case of posterior spine surgery.

  • Back Muscle injury after posterior lumbar spine surgery part 2
    Spine, 1994
    Co-Authors: Yoshiharu Kawaguchi, Hisao Matsui, Haruo Tsuji
    Abstract:

    Study Design The histologic and histochemical changes in Back Muscle were studied in virgin surgery patients with lumbar spine disorders and in patients who underwent repeat posterior lumbar surgery. Objectives The results were correlated to provide the evidences of histologic changes of Back Muscle after posterior lumbar surgery. Summary of Background Data Back Muscles were examined histologically and histochemically after posterior lumbar surgery. No previous study has assessed these changes. Methods Back Muscles were obtained before and after retraction from 18 virgin surgery cases with lumbar spine disorders. In four patients, the retraction pressure was monitored and the retraction pressure-time products ([P][T]) were calculated. In 21 repeat lumbar surgery cases, Muscle samples were obtained before Muscle retraction. Samples were evaluated by histologic and histochemical methods. Results Abnormal findings were slight in virgin surgery cases. Early Back Muscle injury tended to depend on operation time and ([P][T]) products. Late Back Muscle injury in reoperated patients was marked. Various types of neurogenic changes were observed more than 10 months after the first operation. Conclusions Histologic damages of Back Muscle due to previous surgical intervention were long-lasting. To avoid permanent Muscle injury, the retraction time and pressure should be shortened or the pressure on the Back Muscle should be monitored during posterior surgery.

Anne F Mannion - One of the best experts on this subject based on the ideXlab platform.

  • the relationship between psychological factors and performance on the biering sorensen Back Muscle endurance test
    The Spine Journal, 2011
    Co-Authors: Anne F Mannion, David Oriordan, Jiri Dvorak, Youssef Masharawi
    Abstract:

    Abstract Background context Many studies report an association between low Back pain (LBP) and reduced Back Muscle endurance and consider this to indicate muscular dysfunction. However, few have investigated the potentially confounding influence of psychological factors on performance during such endurance tests. Purpose This study examined whether psychological factors were associated with “underperformance” on the Biering-Sorensen (BS) test (ie, not performing as well as one is physiologically capable of). Study design/setting Cross-sectional study of the baseline data of patients with chronic (>3 months) nonspecific LBP (cLBP) before participation in a clinical trial of exercise therapy. Patient sample One hundred forty-eight patients with cLBP (43% men; age, 45±10 years). Outcome measures The time for which the modified BS isometric endurance test could be performed to exhaustion minus the time that would have been predicted based on the rate of decline in median frequency of the surface electromyographic (EMG) signal recorded bilaterally from the erector spinae at L3 and L5. Methods Back pain and disability, psychological disturbance, catastrophizing, fear-avoidance beliefs, Back beliefs, and exercise self-efficacy were measured using validated questionnaires. Patients performed the BS test to exhaustion while physiological Muscle fatigability was measured from continuous surface EMG recordings. Results Multivariable regression analysis controlling for gender revealed that greater psychological disturbance (p=.003) and more negative Back beliefs (p=.015) were unique predictors of the extent of “underperformance,” accounting for 22.3% variance in expected endurance time minus actual time. Conclusions It is important that the underlying nature (psychological or physiological) of performance deficits be identified during such tests because this may influence the interpretation of prospective studies reporting risk factors for LBP and dictate the particular treatment or interventional approach required to remedy the situation in individuals with LBP.

  • active therapy for chronic low Back pain part 1 effects on Back Muscle activation fatigability and strength
    Spine, 2001
    Co-Authors: Anne F Mannion, Simo Taimela, Markus Muntener, Jiri Dvorak
    Abstract:

    DESIGN Randomized prospective study of the effects of three types of active therapy on Back Muscle function in chronic low Back pain patients. OBJECTIVES To quantify the effects of 3 months active therapy on strength, endurance, activation, and fatigability of the Back entensor Muscles. SUMMARY OF BackGROUND DATA Many studies have documented an association between chronic low Back pain and diminished muscular performance capacity. Few studies have quantified the changes in these measures following interventions using objective measurement techniques or related them to changes in clinical outcome. METHODS A total of 148 individuals (57% women) with chronic low Back pain (age, 45.0 +/- 10.0 years; duration of low Back pain, 10.9 +/- 9.5 years) were randomized to a treatment that they attended for 3 months: active physiotherapy, Muscle reconditioning on devices, or low-impact aerobics. Before and after therapy, assessments were made of the following: trunk Muscle strength (in flexion, extension, lateral bending, and axial rotation), erector spinae activation (maximal, and during forward bending movements), Back extensor endurance (Biering-Sorensen test), and erector spinae fatigability (determined from changes in the median frequency of the surface electromyographic signal) during isometric and dynamic tests. RESULTS A total of 132 of 148 patients (89%) completed the therapy. Isometric strength in each movement direction increased in all groups post-therapy (P < 0.0008), most notably in the devices group. Activation of the erector spinae during the extension tests also increased significantly in all groups and showed a weak, but significant, relationship with increased maximal strength (P = 0.01). Pretherapy 55% of the subjects showed no relaxation of the Back Muscles at L5 when in the fully flexed position; no changes were observed in any group post-therapy. Endurance time during the Biering-Sorensen test increased significantly post-therapy in all groups (P = 0.0001), but there were no significant changes in EMG-determined fatigability. Fatigability of the lumbar Muscles at L5 (EMG median frequency changes) during the dynamic test increased post-therapy (P = 0.0001) without group differences. CONCLUSION Significant changes in Muscle performance were observed in all three active therapy groups post-therapy, which appeared to be mainly due to changes in neural activation of the lumbar Muscles and psychological changes concerning, for example, motivation or pain tolerance.

  • active therapy for chronic low Back pain part 2 effects on paraspinal Muscle cross sectional area fiber type size and distribution
    Spine, 2001
    Co-Authors: Lorenzo Kaser, Anne F Mannion, Jiri Dvorak, Astrid Rhyner, Elisabeth Weber, Markus Muntener
    Abstract:

    DESIGN Randomized prospective study to compare the effects of three types of active therapy on the Back Muscle structure of chronic low Back pain patients. OBJECTIVES To analyze the effects of 3 months active therapy on gross Back Muscle size and Muscle fiber type characteristics and their relationship to changes in Muscle function. SUMMARY OF BackGROUND DATA Many studies have documented a diminished muscular performance capacity in cLBP patients, but few have supported this with evidence of alterations in either the macro- or microscopic structure of the paraspinal Muscles. Investigations of the changes in Muscle structure following active rehabilitation are even rarer. METHODS Assessments of trunk Muscle cross-sectional area (using MRI), erector spinae fiber size/type distribution and pathology (percutaneous biopsy), and Muscle function (see Part 1) were made in a group of 59 individuals with cLBP, who were participating in a randomized trial of active therapies for cLBP (physiotherapy, Muscle training on devices, aerobics). RESULTS Fifty-three out of 59 patients (90%) completed the therapy. At baseline, significant correlations were observed between the size of the paraspinal Muscles and isometric Back extension strength (P=0.0001), and between the proportional area of the Muscle occupied by each fiber type and the fatigability of the Muscle (P=0.012). Following therapy, there were small (few percent) increases in trunk Muscle size in the aerobics and physiotherapy groups and a similarly slight decrease in the devices group. Changes in erector spine size correlated only weakly and nonsignificantly with changes in Back extension strength. There were no major changes in fiber type proportion or fiber size in any group following therapy. CONCLUSION Three months active therapy is not sufficient to reverse the typical "glycolytic" profile of the Muscles of cLBP patients or to effect major changes in BackMuscle size. The alterations in Muscle performance observed (increased strength and endurance; Part 1) werenot explainable on the basis of structural changes within the Muscle.

  • the influence of Muscle fiber size and type distribution on electromyographic measures of Back Muscle fatigability
    Spine, 1998
    Co-Authors: Anne F Mannion, Genevieve A Dumas, Joan M Stevenson, R G Cooper
    Abstract:

    STUDY DESIGN: This was a cross-sectional study carried out on a group of 31 healthy, consenting volunteers with no history of low Back pain (17 men, 14 women). OBJECTIVES: To evaluate the relationship between electromyographic measures of erector spinae fatigability and the Muscle's fiber type characteristics. SUMMARY OF BackGROUND DATA: Using electromyographic techniques, a pronounced fatigability of the Muscles of patients with low Back pain has been identified. It has been postulated that this is the result of an unfavorable Back Muscle fiber type distribution, although an association between electromyographic measures of fatigue and the Muscle's fiber type characteristics has never been established. METHODS: Two tests of Back extensor fatigability were performed (on separate days), each to the limit of endurance: 1) maintenance of 60% total maximum voluntary contraction of the Back extensors, and 2) performance of the Biering-Sorensen test. Pairs of surface electrodes were attached to the skin overlying the belly of the erector spinae, bilaterally, at T10 and L3. The median frequency was computed from the electromyographic power spectrum, and fatigability was given by the slope of the linear regression of median frequency on time (MFgrad; %.s-1). One week later, two percutaneous erector spinae Muscle biopsy samples were obtained from the same sites described for electromyography (left side only). Samples were prepared for histochemistry for the identification of Muscle fiber types. Fiber sizes (cross-sectional areas) were quantified using computerized image analysis. RESULTS: The mean fiber size at each erector spinae region showed a significant correlation with maximum Back extensor strength. In the thoracic region, the relative area of the Muscle occupied by Type I fibers (which accounts for the relative size and distribution of the fiber types) showed a significant relationship with MFgrad recorded during each fatigue test. A similar relationship was observed for the lumbar region, but for the Biering-Sorensen test only. CONCLUSIONS: The electromyographic changes recorded in Back Muscles during fatigue appear to be related to the underlying Muscle fiber type area distribution. This confirms the usefulness of electromyography in reflecting such Muscle characteristics in a noninvasive manner, when monitoring changes in function consequent to the development of, or rehabilitation from, low Back pain.