By Celestini, M; Marchese, A; Serenelli, A; Graziani, G
Aim. Spinal instability is often disregarded as a cause of chronic low back pain and until now there has been no agreement as to its definition and on its nosologic importance or as to a conservative therapeutic protocol. The authors aim to verify whether possible symptomatological characteristics are reflected in radiological findings and, although there is no univocal opinion on the utilization of orthoses of containment for unstable segments, they also aim to verify their efficacy on pain control and neuromotor performance when employed in isolation or in association with the most reliable rehabilitation techniques.
Methods. Forty-eight patients between the ages of 30 and 50 were entered in the study, selected with special exclusion criteria and appropriately randomized to a group following kinesitherapy (KT) and orthoses (O) (O+KT group) and to a control group (orthoses [O] group); the symptomatological and instrumental characteristics were studied at time intervals 0 (to), 3 months (t3), 6 months (to), and 12 months (12t).
Results. The samples examined present homogeneous characteristics. Lumbar instability pain is related to the presence of shift and not to hypermobility, when the latter is guided by efficient neuromotor feedback. In the O+KT group, treatment achieves the two-fold results of reducing shift and increasing mobility in the absence of pain. Both groups tend to increase the utilization of a brace over time. Furthermore, in the O+KT group, a marked reduction in the use of medicine is noticed.
Conclusion. Following treatment both groups report a decrease in pain even though the results of neuromotor performance prove to be better in the group following KT.
Key words: Low back pain * Exercise therapy * Pain.
For many decades backache was considered to have a postural or a degenerative origin. Only recently a new nosographic entity, segmentary lumbar instability, has been discussed, which due to its symptomatological and instrumental characteristics, has not attracted many followers. In fact, more often in the rehabilitation sector, the identification of this pathology, due to its atypical manifestations, can be controversial in the best of hypotheses when not denied altogether. The attitude of its detractors seems justified by the examination of findings in part attributable to systemic and segmentary hypermobility and in part to rigidity in general. In its initial phases, in fact, instability is characterized by hypermobility due to the presence of abnormal oblique forces during trunk flexion. In the more advanced phases of the degenerative forms, the narrowing of the intervertebral discs and the development of osteophytes can determine a reduction in mobility.1
According to a definition by Panjabi.- instability “is a mechanical condition in which there is loss of spinal segment rigidity because the optimal equilibrium in which it should exist, by means of stabilizing elements, is lost due to acute or chronic degenerative laxity or damage; this situation can generate such pain and functional limitations that it paves the way for the progression of the ailment itself”. Among the definitions present in medical literature we find: low back pain condition with variable clinical symptomatology, appearance of symptoms of inconstant intensity, varying from moderate to severe, in response to minimum strain.s-4 loss of vertebral disc structural rigidity,5 accentuated anteroposterior translation, presence of combined pathological motions, increase in the neutral zone, pathological instantaneous rotation center.6 With instability we are in the presence of the loss of capacity to resist forces applied in physiological conditions on the part of the unit of spinal motion.7 It manifests itself with the appearance of an abnormal intersegmentary movement both in a quantitative way with hypermobility and/or shift and qualitatively with a pattern of altered motions.6
Many authors now agree with the existence of an osteoligamentous instability and a neuromuscular one,1, 8-10 the former can be helped with neuromuscular aid which, if not achieved, obliges us to intervene surgically; the latter, instead, almost always needs only conservative treatment.
O’Sullivan etal.n have tried to correlate the characteristics of the pain symptomatology with the observable clinical signs examined objectively and with diagnostic instrumental findings, but, without finding a close correspondence.
For a long time radiological diagnosis of instability has been controversial. Nonetheless, the dynamic radiographie examination in flexo-extension has generally been accepted as a sufficiently reliable method for the diagnosis of instability. The correlation between particular symptoms and specific types of instability is rather scarce.12 Initially, according to the criteria defined, there had to be the presence of at least a 3 mm shift on the radiographie image in lateral projection and at least a 10 inclination on the image in anteroposterior projection.
Indirect signs of instability consist of marginal osteophytosis, by traction, asymmetric collapse of the intervertebral disc during flexo-extension, vertebral disalignment on the frontal plane, fracturing of the annulus.13,14 A study conducted by Sihvonen et al.15 on patients with chronic low back pain, who underwent a radiographie examination using dynamic evaluation of the lumbar tract and a needle electromyography of the paravertebral muscles, pointed out the following elements: retrolisthesis was considered a rather rare form of instability. However, in patients not presenting degenerative damage, this state was slightly more frequent compared to anterolisthesis. This difference might suggest that retrolisthesis, in comparison to anterolisthesis, represents a primitive lesion or can be considered an early sign of degeneration and loss of mechanical functional abilities. A3 far as the association with the symptomatology of irradiated pain is concerned, when retrolisthesis occurs there is a posterior protrusion of the fibrous ring with narrowing of the intervertebral space.
The stabilization of the spinal segment is assured by 3 subsystems: the passive stabilizing system is represented by the vertebrae, the intervertebral rings and the ligaments; the active elements consist of muscles and tendons, and the neural control system, which monitors proprioceptive information. On the other hand, the overall dysfunction of the 3 subsystems can cause damage, which results in the appearance of painful symptoms. Cholewicki et al.16 have demonstrated that lumbar stability is kept viable by an increase in segmentai muscular tone, underlining the importance of motor control in coordinating muscular recruitment during the motion stages between the muscles with greater extension, which are the more superficial agents mainly for the more massive movements, and the small muscles, which are responsible for finer adjustments. The presence of 2 types of active muscles in stabilizing the spine has been pointed out by Bergmaark:17 1) the extrinsic muscle system, consisting of long lever muscles, like the ileocostal, 2) the intrinsic muscle system, represented by muscles which insert themselves directly on the lumbar vertebrae and have the task of stabilizing the segments and directly controlling their movement. Several authors 8-10 have attributed the responsibility for instability not only to the incapacity of adequately activating (preactivization) the transverse abdominus but to the incapacity on the part of the paravertebral, particularly of the multifidus, muscles to stabilize and coordinate the reciprocal movement of single vertebra in relation to their contiguous elements during the movements of the trunk as well. Specific dysfunctions of the multifidus and the low abdominal muscles, examined in patients suffering from chronic low back pain, are mainly represented by the alterallons of the synergic and coordinated activation pattern, which are often activated in order to give greater stability to spinal segments where osteoligamentous lesions from chronic strain or trauma has occurred. In these conditions muscular hyperactivation occurs. 18 This behavior has been interpreted both as a predisposing factor towards the lesions and as a result of soft tissue damage, which has necessarily caused the development of a different strategy toward neuromuscular control in order to improve stability in the damaged tract. This theory has already been put forward by Magnusson and Wilder.19,20
Obviously there is an objective difficulty in the assessment of instability when its cause Ls the alteration of the neuromuscular stabilizing system. Many studies published in recent years have emphasized the necessity for utilizing rehabilitative techniques to improve neuromuscular control. The methodologies, already elaborated by Knott21 and then by Bobath,22 which had their origin in works pertaining to neurologic pathology such as marrow lesions and strokes, developed back stabilization exercises, in which both facilitation and inhibition were inserted in the sequences of neuromotor development used by the authors themselves, instead of simple repetition of strengthening exercises,7, 23-25 or the denervation of paraspinal muscles in the presence of retrolisthesis.” Takin\g the cue from recent discoveries in the biomechanical field, all these works tend to insist on the primary need to re-educate the proprioceptive capabilities with particular regard not only to the anticipatory phase of the exertion and the control of the movement itself but to the reactions of equilibrium in the extension of the muscles in order to eliminate the contractures of the unstable segment as well, and finally, on the need to condition the transverse abdominus and multifidus as well as the small oblique and quadratus lumborum muscles in particular, integrating the proprioceptive capabilities with the global neuromotor action.
It must be remembered that while the long spinal extensor muscles perform the extensional component, the multifidus muscle behaves as a transducer of forces both due to its high content of spindle muscles and its nearness to the center of rotation, and as a highly efficient center of postural feedback as well, while the quadratus lumborum performs a stabilizing action during flexo-extensional movements of the lumbar spine. On the other hand, the internal oblique muscles, if activated in co-contraction transform themselves from rotatory spinal muscles to stabilizing ones; but the muscle with the best stabilizing characteristics on the lumbar vertebrae is undoubtedly the transverse abdominus. As Hodges et al.w have demonstrated, it anticipates all the movements of the trunk and limbs with its contraction. We are indebted to O’Sullivan ” for demonstrating that transverse abdominus’ activity occurs in antagonism to that of the rectus abdominus muscles. Furthermore, the former’s conditioning must be pursued without increasing the strength of the latter.
Lindgren etal.26 recommend performing stretching exercises for the muscles connecting the waist with the lower limbs in particular for the ileopsoas, the gluteals, and the ischiocrurals. They often noticed a retraction on the part of these muscles, which is explainable with the attempt of part of the body somehow to stabilize the waist and thus facilitate the achievement of postural stability. These exercises must obviously be practiced without overburdening the lumbar structures.
Previous studies support the orientations toward more suitable choices of rehabilitative techniques.
Through similar training lasting 4 weeks (3 sessions a week) Sung -” has assessed by means of the Oswestry score test and by electromyography that the variation in the contractability of the multifidus was statistically significant in male subjects, while in female subjects it was likely to take a longer period of time to achieve the same results. Arokoski et al.28 have reached similar conclusions, nonetheless underlining the greater ability of women to activate the stabilization of the trunk’s extrinsic muscle masses.
To this type of treatment McGiIl et al.29 add endurance exercises, when the patients’ reduced capacity in this component is demonstrated. The length of time of endurance in training flexors, extensors and lateroflexors as well as their relationships can represent a valid tool in assessing improvement and establishing training programs.
In postdiscectomy instability Yilmaz et al.30 have demonstrated statistically that the utilization of stabilization exercises are more effective than home exercises and those of the control group, assessing the following parameters: pain, functional disability, Shober, Pile Test, and endurance test of the trunk.
Unfortunately, there are no studies comparing the various techniques, if we exclude the disappointing results obtained with exercises whose sole intent was to strengthen the muscles.31-33
The authors intend to verify whether eventual symptomatological characteristics are reflected radiologically and, although there is no univocal opinion on the utilization of orthoses of containment for the unstable segments, they also intend to verify their efficacy on pain control and neuromotor performance when employed in isolation or in association with the most reliable rehabilitation techniques.
Materials and methods
Fortyeight patients were enlisted according to the following criteria. Inclusion criteria were: females, relapse of chronic low back pain, age between 30 and 50, positive to the systemic laxity test (systemic laxity evaluation by means of search for articular laxity pertaining to the following 9 districts: II and V finger in both left and right hands, elbow and knee bilaterally, back lumbar spine),34 at least one positive radiograph, medical history diagnosing at least 5 positive signs of instability among: history of recurrent low back pain instigated by minimum stress, central lumbar pain in standing position, protracted with application of strain, temporary relief from pain after manipulative treatment, improvement of symptoms through utilization of orthopaedic braces, prior traumas,35 and positive objective examination showing at least one sign of diagnosis of instability (a visible or palpable presence of a step at the level of the spinous apophysis level of the lumbar tract, and the so called “instability catch” represented by abnormal movements observed during active range of motion [ROM] evaluation 4). The exclusion criteria were: practice of high impact sports, menopause, endocrine metabolic disturbances, osteoporosis and/or vertebral collapse, prior emilaminectomy, specific or unspecific inflammations of the lumbar spine. The estimate of the size of the sample was based on a study of the vagueness of the Backill questionnaire regarding the Italian population, and with the choice of precision within 5%. The minimum number had to be at least 18 members per group, to which we added a 30% dropout average. We thus reached a total of 48 units.
After giving their informed consent, all the female patients had to answer a questionnaire (historical assessment), administered by a sole interviewer, which included the following: the date of first manifestation of pain, the way in which it appeared, the duration and the event that triggered the single episode, the number of episodes in a year, the number of episodes in the last 90 days, the appearance of symptoms in the intermediate levels of flexion- extension (the modifications of the neutral zone appeared to be more sensitive than those of the ROM in the corresponding segment; this therefore seems to be an important clinical measure of vertebral stability),36 lessening of the symptoms with an orthesis, the presence of central lumbar pain in standing position, accentuated pain from strain, relief with manipulative therapy, prior traumas, relation between pain and sloping position, irradiation of pain to the lower limbs, possible use of brace and medicine in presence of pain. The Backill scale 37 was given to all patients to assess their disability. The clinical assessment included classic clinical items such as the Dandi (test to assess the extensor efficiency pertaining to the toe), Lasegue, Wasserman, Vallelix osseo-tendinous reflexes (ROT), the strength of the lower limbs, tenderness, piriform test,38 Wolkman test (to test the endangering of the sacroiliac articulations, performed in lateral decubitus by an operator who applied pressure perpendicularly to the iliac crests), assessment of pain and rigidity according to Maigne;3? furthermore, there were clinically orientated items (these items were considered orientational since some of them had been described by the authors below and had been considered so by the clinical experience of the authors themselves), described as positivity to pince-roul,39 trigger and tender point,38-40 Delitala (stimulation of sciatic nerve at sacrum emergence), strength of abdominal muscles and spinal erectors, spinalgia, Shoeberg test,22 systemic laxity test,34 clinical step, abnormal motions in the active ROM according to Paris,4 guided straightening (the individual’s passage from a spinal flexed position to a standing position using the lower limbs as a pylon for straightening up), the disturbance test.18 Regarding this, Radebold etal. studied the activation pattern of 6 couples of spinal muscles in individuals suffering from chronic low back pain, who underwent sudden stress on their spinal chord in flexion, extension and lateroflexion, and compared this pattern with that of healthy individuals.18 In applying the disturbance, consisting in sudden removal of an obstacle against which the individuals had to exert pressure with their trunk, the healthy individuals reacted by, in quick sequence, disactivating the agonist muscles and activating the antagonist ones, while the patients showed a lesser tendency to disactivate the agonist muscles, which remained contracted even during the activation of the antagonist ones (co-contraction). Furthermore, their muscle recruitment was quantitatively inferior in comparison with that of the healthy individuals in the course of all the trials performed. Between the 2 groups examined there were also differences in the reaction times to the applied stimuli: the patients’ latency times in the appearance of muscular response both in disactivating the agonist and activating the antagonist muscles were greater than in the healthy ones. The following were examined in standard standing, dynamic and oblique X-rays: the presence of lyses or isthmic scleroses, spondylolisthesis, retrolisthesis, forward shift greater than 3 mm in dynamic radiographies, facette syndrome,41 the level and measurement of the discosomatic angle (parameter created by the authors, which represents the sum of the angles of the hypermobile interdise space in maximum flexion and extension). All these parameters have been the material of a specific correlational study of clinical observation and of repeatability about to be published.
The assessments were made at the beginning of the study (t0), at 3, 6, and 12 months (respectively t3, to, and t12). In particu\lar, all the assessments were made at tO, the anamnestic, clinical and radiological ones at to, and only the anamnestic ones at t3 and t!2.
The female patients selected were randomized on the basis of a sampling chart subdivided into 2 age classes (30-40 years and 40-50 years), into 2 therapeutic groups: orthoses only (O group); stabilizing kinesitherapy and orthoses (O+KT group). The O utilized was a cloth band with splints of the CAMP brand, prescribed for 90 days of continuous use to both groups without discrimination. The KT protocol was standardized beforehand in 12 applications, 3 times weekly for 4 weeks, consisting in diaphragm breathing exercises, proprioceptive trunk exercises, with particular attention given to the achievement and maintenance of the neutral zone at the level of lumbar lordosis, gluteal and ischiocrural stretching exercises performed in an unloaded way, contraction exercises of the lumbar stabilizing muscles (in particular of the transverse abdominus) both singly and in association with the other trunk muscles, gradually adding control during the motion of the limbs and reconditioning of endurance, exercises for trunk stabilizing on ever more reduced supporting surfaces and finally on unstable surfaces, selective strengthening exercises of the lower limbs and postural and occupational counselling/guidance.
Parametrical and non-parametrical tests(t-Student with two- tailed independent data, Levene’s test, χ^sup 2^ test by degrees) were utilized, preceding verification of the data distribution and statistical tests of correlation between variables. Significant differences were considered those with P
The groups studied proved to be homogeneous for the first display of events, for the characteristics of pathology, for the traditional clinical tests, as well as for those identified as specific by the authors, except for the spinalgia and straightening tests. Even for the radiological examinations, including discosomatic excursion between the maximum flexion and extension and for the Backill scale, the results show no significant differences between the groups. The characteristics of the patients who dropped out in both groups are furnished in Table I. Anamnestic, clinical and radiological items were monitored longitudinally in each group, of which the most interesting clinical results are set out in Table II. Table III, and Table IV.
The number of episodes of back pain (assessed by the patient in the last 90 days preceding the control) decreases progressively. At the first control 78% of the O+KT group affirmed having 6 acute episodes in the last 3 months; 6 months later the number of episodes had remarkably decreased, in fact, the percentage of patients affirming they had more than 6 episodes in the preceding 90 days had decreased to 27%. In the same group at to, 55% affirmed they had a complete remission of pain symptoms (Table II).
TABLE I.-Characteristics of dropout patients and moment of leaving. t0: start of study; t3: follow-up at 3 months; t6! follow- up at 6 months; t12: follow-up at 12 months.
TABLE II.-Anamnestic results. t0: start of study; t6: follow-up at 6 months; 112: follow-up at 12 months.
TABLE III.-Clinical data. t0: start of study; t6: follow-up at 6 months; t12: follow-up at 12 months.
TABLE IV.-Radiological findings. t0: start of study; t6:follow- up at 6 months; 112: follow-up at 12 months.
The O group finds relief in manipulative therapy (47% at t0) even if in later checks nobody is follows this kind of therapy (P
Backill’s functional and pain scale did not manifest a statistically significant modification trend either in time or in association with other parameters except for the pain alarm item in the O group, where the perception of pain perceived as “relatively severe” was reported in 63% of the population at tO, while it disappeared in subsequent checks, and was perceived exclusively as “light” as set out in Table II.
It is obvious that the use of a brace brings immediate relief to patients suffering from instability especially in the O group. Furthermore, we believe a positive response to its use can help a doctor formulate the right diagnosis. Both groups report a reduction in pain through exercise in the period preceding therapy, while at the end of the trial group O, conditioned by the use of a brace, they seem to look for stability through the absence of movement and rest to avoid pain. Instead, group O+KT finds relief and stability through muscular activation, by repeating the motions learned during treatment. While group O continues to take medicine, almost the whole of group O+KT tends not to take it anymore (77%) at to.
As regards the radiographie findings, the only important variations concern the O+KT group, in respect to the articular discosomatic excursion parameters superior or equal to 15 (the number of positive individuals increased) and shift superior to 3 mm (the number of positive individuals decreased). As regards both parameters a significant difference was also reported between groups. As to the use of medicine in the 2 groups at to, 77% of the O+KT group patients are remarkably orientated towards not taking medicine compared to 8% of the O group (PO.01 ).
The practice of self performed kinesitherapy was compared between the 2 groups and it turned out that 86% of the O+KT group did exercises at home when experiencing pain against 14% of the group utilizing only ortheses with P
Both therapies are efficient in pain control, as demonstrated by the anamnestic findings; VAS or other similar scales were not used because they were not considered valid for assessing a symptom with inconstant and unrepeatable characteristics-, even the Backill scale does not appear to be an adequate tool for assessing pain which Ls discontinuous or caused by behavior typical of instability since it does not highlight any significant variation in time, possibly also due to the smallness of the sample.
Between 40 and 50 years of age no individual appears to suffer from functional radiologie laxity. This is probably due to the occurrence of rigidity on a degenerative basis, which establishes itself in response to the repeated mechanical stress sustained by the structures of the mobile segment; from this it is possible to deduce that the pain symptom and hypermobility have preceded this phase.
A positive Lasegue is not a pathological indicator of clinical and radiologie positiveness of instability because there is no correlation between it and all the items considered significant for the diagnosis of instability.
The statistical investigation demonstrated a high index of correlation between the discosomatic delta and the other typical clinical parameters of instability when the difference passes 15. In particular, the discosomatic delta >15 is closely correlated to retrolisthesis (which in medical literature Ls pointed out as one of the initial signs of instability). Thus it can be deduced that this indication can be taken as a limit value for the radiologie diagnosis of lumbar segmentary instability (personal data).
Both therapies produce an increase in the discosomatic angle, in other words they remove the latent constitutional laxity together with the reduction of rigidity and pain connected to the contracture.
However, the differing results between the 2 therapies is displayed in the reduction of shift, which is achieved solely in patients who have undergone kinesitherapy treatment. What distinguishes the result between the 2 proposed therapies is not the reduction of pain or of contracture, but the quality of movement on the level of the unstable mobile segment. From the analysis comparing the trend of the data on shift and on the discosomatic delta in the O+KT group, and keeping in mind the literature on lumbar instability,23-25 it is possible to hypothesize: a) the body reacts to strain by protecting the hypermobile tract with a quantitative increase of rigidity by activating the contraction of the intrinsic paravertebral muscles, which pass bridge-like on the segment itself; b) the bracing aims to and achieves the result of containing the hypermobile tract, however, without supporting the local circuit in contracture; c) the KT treatment implements the capacities of neuromuscular activation, achieving active protection; consequently, it removes the latency of hypermobility (increase of delta) consenting a quantitative and qualitative increase in mobility (lessening of shift). In fact, by improving neuromuscular control, the KT treatment is capable of rendering the movement more harmonious, by reducing disturbances at the mobile segment level, which trigger the typical ailments of instability and the contractured response of the paravertebral muscles. Therefore, instability and rigidity are not in absolute contradiction and this renders the clinical diagnosis difficult as every pain stimulus at the segmentary level is expressed in a reflex circuit, whose final expression is contracture. Obviously even hypermobility and harmonious movement are not contradictory if the neuromuscular system, adequately stimulated, succeeds in controlling the motion even in a wider range and with less restraint on the part of the mechanical structures; all this confirms Panjabi’s “neutral zone” theory.7
Both groups found the experimentation helpful, the association of KT produces better effects on the symptomatology, neuromotor performance and life style, which is displayed in the tendency not only to take less medicine and use supports less, but to resort to home therapeutic exercises replacing bed re.st in case of recurrence of pain as well.
The results remain constant a year after treatment.
This study’s most original finding appears to be the discovery of the 15 limit as the summation of the \discosomatic angles of the hypermobile vertebral segment in establishing a correct clinical diagnosis of instability and, furthermore, the finding that the passing of this limit is closely correlated to retrolisthesis.
Because of the complexity and variability of behavior in this study, further randomized controlled trials are surely to be hoped for.
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M. CELESTINI. A. MARCHESE, A. SERENELLI. G. GRAZIANI
Department of Pb vsical Medicine and Rehabilitation RM/A-RM/E, S. Spirito in Sassia Hospital, Rome, Italy
Submitted for publication January 28. 2005.
Accepted July 3. 2005.
Address reprint requests to: Dr. A. Serenelli. Dipartimento di Medicina Fisica e Riabilituzione. Ospedale S. Spirito in Sassiu. Uingo Tevere in Sassia 1. 00193 Roma. E-mail: [email protected]
Copyright Edizioni Minerva Medica Sep 2005