Olavi Airaksinen

Local denervation atrophy of paraspinal muscles in postoperative failed back syndrome.

Impairment and disability after back surgery is a common diagnostic and therapeutic problem. For the most part the reasons are unclear. Of 178 patients who had undergone laminectomies 2-5 years earlier, 14 patients with good recovery and 21 patients with poor recovery but no evidence of restenosis on computed tomography were selected by the Oswestry index. According to radiologic, neurophysiologic, and muscle biopsy evidence most patients (13 of 15 studied) suffering from the severe postoperative failed back syndrome had dorsal ramus lesions in one or more segments covered by the scar and local paraspinal muscle atrophy at the corresponding segments. Disturbed back muscle innervation and loss of muscular support leads to the disability and increased biomechanical strain and might be one important cause to the failed back syndrome. It may be possible to develop operating techniques that save back muscle innervation better than the usual ones.

Back and hip extensor fatigability in chronic low back pain patients and controls

OBJECTIVE To compare the lumbar paraspinal and gluteus maximus muscle fatigability between chronic low back pain patients and healthy controls by using electromyographic (EMG) spectral analysis during a maximal isometric endurance task. DESIGN A cross-sectional comparative study between chronic low back pain patients and healthy control subjects. SETTING Physical medicine and rehabilitation clinic in Finland. SUBJECTS Twenty women with nonspecific chronic low back pain (longer than 3 months) and 15 healthy controls. INTERVENTION Subjects performed maximal voluntary isometric back extensions (MVC) at 30 degrees forward flexion in a specially designed measurement unit. A 50% MVC load was used in isometric endurance test. OUTCOME MEASURES Low back pain intensity was assessed by using the visual analogue scale and functional disability by the Oswestry disability index. Time to endurance was measured. Bipolar surface EMG recordings were made over the lumbar paraspinal muscles (L3-L4, L5-S1) and over the gluteus maximus muscles. Average EMG (aEMG%), and initial spectral median frequency (MFinit) and change over time (MFslope) were computed. RESULTS Pain intensity and functional disability were higher and MVC and time to endurance were lower in the chronic low back pain group (p < .05). Similar muscle activity levels (aEMG%) and MFinit indicated similar muscle loading in both groups at the beginning of the endurance test. EMG spectral decreases (MFslope) indicated that lumbar paraspinal muscle fatigability was similar in both groups. In the chronic low back pain group, the gluteus maximus fatigued faster than in the control group (greater MFslope, p < .05). However, the shorter endurance time indicated greater fatigability in the chronic low back pain group in general (p < .05). CONCLUSIONS The chronic low back pain patients were weaker and fatigued faster than the healthy controls. The EMG fatigue analysis results suggest that the gluteus maximus muscles are more fatigable in chronic low back pain patients than in healthy control subjects during a sustained back extension endurance test.

Surgical outcome of 438 patients treated surgically for lumbar spinal stenosis

Study Design. A retrospective, follow‐up study. Objectives. To investigate the overall outcome of surgery for lumbar spinal stenosis and to investigate the preoperative factors affecting outcome. Summary of Background Data. The success rates of surgical intervention for lumbar spinal stenosis vary, and few preoperative factors have been found to be significantly correlated to surgical outcome. Methods. A total of 438 patients (183 women, 255 men) who underwent decompressive surgery for lumbar spinal stenosis were re‐examined and evaluated for outcome 4.3 years after surgery. Outcome was based on subjective disability, which was assessed using the Oswestry low back pain questionnaire. The preoperative data (clinical documentation, length of laminectomy, and radiographs) were collected from patient records that had been stored in the hospital. Preoperative factors affecting outcome were reported. Results. The mean value of the Oswestry disability score of these 438 patients was 34 ± 18 (women, 36.3 ± 17; men, 32.3 ± 18; P < 0.05). Age did not influence general outcome. The proportion of good to excellent outcomes of all 438 patients was 62% (women, 57%; men, 65%). Diabetes, hip joint arthrosis, and preoperative fracture of the lumbar spine seemed to be associated with poor outcome. The ability to work before or after surgery and a history of no prior back surgery were predictive of good outcome. Conclusion. The results suggest that clear myelographic stenosis and no prior surgical intervention, no comorbidity of diabetes, no hip joint arthrosis, and no preoperative fracture of the lumbar spine are factors associated with a good outcome in surgical management of lumbar spinal stenosis.

Interexaminer reliability of low back pain assessment using the McKenzie method.

Study Design. A test–retest design was used. Objective. To assess interexaminer reliability of the McKenzie method for performing clinical tests and classifying patients with low back pain. Summary of Background Data. Clinical methods and tests classifying patients with nonspecific low back pain have been based mainly on symptom duration or extent of pain referral. The McKenzie mechanical diagnostic and classification approach is a widely used noninvasive, low-technology method of assessing patients with low back pain. However, little is known about the interexaminer reliability of the method, previous studies having yielded conflicting results. Methods. For this study, 39 volunteers with low back pain, mean age 40 years (range, 24–55 years), were blindly assessed by two physical therapists trained in the McKenzie method. The variability of two examiners for binary decisions was expressed by the kappa coefficient, and by the proportion of observed agreement, as calculated from a 2 × 2 contingency table of concordance. Results. On the basis of pure observation alone, agreement among clinical tests on the presence and direction of lateral shift was 77% (&kgr; = 0.2;P < 0.248) and 79% (&kgr; = 0.4;P < 0.003), respectively. Agreement on the relevance of lateral shift and the lateral component according to symptom responses was 85% (&kgr; = 0.7;P < 0.000) and 92% (&kgr;= 0.4;P < 0.021), respectively. Using the repeated movements and static end-range loading strategy to define the centralization phenomenon and directional preference, agreement was 95% (&kgr; = 0.7;P < 0.002) and 90% (&kgr; = 0.9;P < 0.000), respectively. When patients with low back pain were classified into the McKenzie main syndromes and into specific subgroups, agreement was 95% (&kgr; = 0.6;P < 0.000) and 74% (&kgr; = 0.7;P < 0.000), respectively. Conclusions. Interexaminer reliability of the McKenzie lumbar spine assessment in performing clinical tests and classifying patients with low back pain into syndromes were good and statistically significant when the examiners had been trained in the McKenzie method.

Age, sex, and body mass index as determinants of back and hip extensor fatigue in the isometric Sørensen back endurance test

OBJECTIVE To study the ability of a widely used isometric back endurance test to measure lumbar back erector muscle fatigue and to assess the influence of age, sex, and body mass index (BMI) on back and hip extensor muscle fatigability (EMG spectral indices). DESIGN Cross-sectional study of men and women without back problems. SETTING Occupational health center and rehabilitation clinic in Finland. SUBJECTS Experiment 1 consisted of 233 consecutive occupational health center customers (133 women, 100 men) without back problems. Experiment 2 consisted of 20 healthy women. INTERVENTION Subjects performed the isometric Sørensen back endurance test up to 240sec in experiment 1 and to the limit of endurance in experiment 2. OUTCOME MEASURES Raw surface EMG was recorded bilaterally over the belly of lumbar erector spinae muscles at L1-L2 and L4-L5 levels in experiment 1, and bilaterally over the medial paraspinal muscles at L1-L2, L3-L4, and L5-S1 levels and over the major hip extensor muscles (gluteus maximus and biceps femoris) in experiment 2. In both experiments, time to endurance was recorded (in experiment 1 up to 240sec). The EMG spectral median frequency (MF) decrease over time was used for the assessment of back and hip extensor fatigability. RESULTS In experiment 1, the rate of change in paraspinal MF was greater in men than in women, indicating greater paraspinal fatigability in men. Multiple regression analysis indicated that the rate of MF decrease (fatigue) during the test was dependent on age and BMI in both sexes and that the effects of age and BMI were more pronounced in women than in men. Correlation analysis revealed that the rate of paraspinal muscle MF decrease was associated with endurance time and BMI in women and with endurance time and age in men. In experiment 2, the paraspinal muscles, as well as the hip extensor muscles, biceps femoris, and gluteus maximus, showed clear decreases in MF during the isometric endurance test in women. MF decrease was highly related to endurance time and BMI in women. CONCLUSIONS Lumbar paraspinal muscle fatigability during the Sørensen test is influenced by subject characteristics. Further, the hip extensor muscles also significantly fatigue, indicating load sharing between back and hip extensor muscles during the test. According to these results, the validity of this widely used back endurance test in specifically measuring lumbar paraspinal muscle endurance is questionable, as is the direct comparison of test results between women and men.

Back and hip extensor activities during trunk flexion/extension: Effects of low back pain and rehabilitation

OBJECTIVE To compare lumbar paraspinal, gluteus maximus, and biceps femoris muscle function during sagittal trunk flexion and extension in patients with chronic low back pain and healthy control subjects, and to assess the influence of rehabilitation in the back pain patients. DESIGN A cross-sectional study comparing chronic low back pain patients and healthy controls, and a prospective follow-up in back pain patients during rehabilitation. SETTING Physical medicine and rehabilitation clinic. SUBJECTS Nineteen women with chronic low back pain, and 19 women without pain (controls). INTERVENTION Five-week active outpatient rehabilitation (1 hour three times a week) guided by a physiotherapist, followed by 5-week self-motivated exercise at home. OUTCOME MEASURES Subjects performed sagittal trunk flexion and extension while surface electromyogram was bilaterally recorded of paraspinal (L1-L2 level), gluteus maximus, and biceps femoris muscles. The muscle activity was assessed from the average electromyogram and the relative muscle activation onsets and their duration were calculated. RESULTS During early flexion, lumbar paraspinal and biceps femoris were activated simultaneously before gluteus maximus. At the end of flexion and during extension all investigated muscles were activated and relaxed in order. Lumbar paraspinal and biceps femoris muscles were activated in a similar order in low back pain patients and healthy controls during flexion and extension. However, the duration of gluteus maximus activity was shorter in the back pain patients than in controls during the trunk flexion (p<.05), and it ended earlier during extension. Active rehabilitation did not change the muscle activities of lumbar paraspinal and biceps femoris in the back pain patients, but in the measurements after rehabilitation the onset of gluteus maximus activity occurred later in flexion and earlier in extension. CONCLUSIONS The activity of the gluteus maximus muscle during the flexion-extension cycle was reduced in patients with chronic low back pain. The gluteal muscles should be taken into consideration in the rehabilitation of these patients.

Back and hip extensor muscle function during Therapeutic exercises

BACKGROUND Therapeutic exercises are widely used in the treatment of low back problems. Clinical knowledge about targeting the load in these exercises, however, is insufficient. This study assessed the L2 and L5 level paraspinal and gluteus maximus muscle activities in different therapeutic exercises. Intramuscular and surface electromyography (EMG) measurements were obtained to study whether surface EMG measurements can be used in the assessment of multifidus muscle function. METHODS Eleven healthy subjects (5 men, 6 women) 21 to 38 years of age volunteered for the study. The subjects performed 18 different therapeutic exercises. During the exercises paraspinal EMG was recorded using fine wire and surface electrodes. The normalized peak and average muscle EMG activities (percentage of amplitude in maximal voluntary contraction [MVC]) during each task were determined. RESULTS The correlations between the average intramuscular and surface activities of the normalized EMG (% of MVC) at the L2 and L5 levels were .928 and .950, respectively. The peak and average EMG amplitudes of the exercises were below 50% and 25% of MVC, respectively. At the L5 level, the multifidus peak and average EMG amplitudes (% MVC) were higher in women than in men, whereas no significant difference was found at the L2 level. In women, the normalized multifidus EMG amplitude was higher at the L5 level than at the L2 level, whereas no significant difference was found in men. In both sexes, the normalized EMG amplitude was higher in the multifidus than in the longissimus muscle. CONCLUSION Surface EMG measurements may be used in the assessment of multifidus muscle function. Simple therapeutic exercises are effective in activating the lumbar paraspinal muscles.

Long-term results of surgical treatment of lumbar spinal stenosis.

There are few data available regarding the long-term outcome of laminectomy for lumbar canal stenosis. Both in 1985 and in 1991 108 patients who had undergone surgery for lumbar spinal stenosis were reevaluated using the Oswestry disability questionnaire. There were 50 women and 58 men. The clinical diagnosis of stenosis was confirmed mainly by myelography. The mean follow-up time in 1985 was 6.8 years and in 1991 12.8 years, and the mean age of the patients at the time of surgery was 50.7 years. The mean Oswestry score in 1985 was 34.5 and in 1991 30.2 (P < 0.001). Men improved more than women. Laminectomy was performed on an average of 1.6 levels. Ten (9.3%) of the 108 patients underwent repeat decompression during the study period. The authors concluded that the results of the patients improved during the course of the longitudinal follow-up time of 7 and 13 years. The chances of a patient requiring reoperation after surgery for lumbar spinal stenosis were low.

Lumbar paraspinal muscle function, perception of lumbar position, and postural control in disc herniation-related back pain.

Study Design. A follow-up study evaluating postural control, lumbar movement perception, and paraspinal muscle reflexes in disc herniation-related chronic low back pain (LBP) before and after discectomy. Objectives. To assess the effect of discectomy on postural control, lumbar perception, and reflex activation of paraspinal muscles during sudden upper limb loading. Summary of Background Data. Impaired muscle function, postural control, and lumbar proprioception have been observed in LBP. However, they have not been studied in sciatica patients after surgery. Methods. The study included 20 patients selected for an operation for chronic LBP caused by disc herniation and 15 controls without chronic LBP. The paraspinal muscle responses for upper limb loading during unexpected and expected conditions were measured by surface electromyography. The ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in the seated position. The postural control was measured with a vertical force platform. Pain, disability, and depression scores were recorded. Results. Patients had poorer lumbar perception (P = 0.012) and postural control (P < 0.05) than did healthy controls. The postural control remained unchanged, but lumbar perception (P = 0.054) and the lumbar feed-forward control (P = 0.043) improved after the surgery. Conclusions. The results demonstrate impaired lumbar proprioception and postural control in sciatica patients. During short-term follow-up after operative treatment, postural control does not seem to change, but impaired lumbar proprioception and feed-forward control of paraspinal muscles seem to recover.

Reproducibility of infrared thermography measurements in healthy individuals

The aim of this study was to investigate the reproducibility of skin surface infrared thermography (IRT) measurements and determine the factors influencing the variability of the measured values. While IRT has been widely utilized in different clinical conditions, there are few available data on the values of the skin temperature patterns of healthy subjects and their reproducibility. We recorded the whole body skin temperatures of sixteen healthy young men with two observers on two consecutive days. The results were compared using intra-class correlations analyses (ICC). The inter-examiner reproducibility of the IRT measurements was high: mean ICC 0.88 (0.73-0.99). The day-to-day stability of thermal patterns varied depending on the measured area: it was high in the core and poor in distal areas. The reproducibility of the side-to-side temperature differences (deltaT) was moderately good between the two observers (mean ICC 0.68) but it was reduced with time, especially in the extremities, mean ICC 0.4 (-0.01-0.83). The results suggest that the IRT technique may represent an objective quantifiable indicator of autonomic disturbances although there are considerable temporal variations in the measured values which are due to both technical factors such as equipment accuracy, measurement environment and technique, and physiological variability of the blood flow, and these factors should be taken into account.