Laboratorial analysis of the myelomeningocele gait of lower lumbar level and unilateral hip instability

Abstracts

Este estudo examina a influência da instabilidade unilateral do quadril sobre a marcha de pacientes portadores de mielomeningocele, nível lombar baixo e instabilidade unilateral do quadril. Foram estudados através da análise laboratorial de marcha, 20 pacientes deambuladores comunitários utilizando goteiras e muletas, com luxação ou subluxação unilateral do quadril. , Os pacientes foram sub divididos em dois grupos. Grupo 1 (10 pacientes) , que não apresentavam contraturas do quadril (flexão e/ou adução) ou as apresentavam de forma simétrica entre os lados; e Grupo 2 (10 pacientes), que apresentavam contraturas assimétricas de quadril A cinemática do quadril e da pelve foi analisada no sentido de se avaliar a simetria entre o lado envolvido e o oposto. Sete pacientes do Grupo 1 e 2 do Grupo 2 apresentaram marcha simétrica. Marcha assimétrica foi encontrada em 3 pacientes do Grupo 1 e 7 pacientes do Grupo 2. A assimetria na marcha relacionou-se principalmente com a presença de contraturas de quadril unilaterais ou bilaterais mas assimétricas. Demonstrou-se que a assimetria da marcha não pode ser atribuída somente à instabilidade do quadril, mas parece estar mais relacionada com presença de contraturas unilaterais ou assimétricas e cujo tratamento deveria ser o objetivo em detrimento de reduções cirúrgicas do quadril.

Mielomeningocele; Luxação do quadril; Marcha

ORIGINAL ARTICLE

Laboratorial analysis of the myelomeningocele gait of lower lumbar level and unilateral hip instability

Ana Paula T. Gabrieli^I; Steve Vankoski^II; Luciano S. Dias^III; Carlo Milani^IV; Alexandre Lourenço^V; José Laredo Filho^VI

^IMaster of the Surgical Clinical Department

^IIBioengineer Laboratorial Bait Analysis, Children's Memorial Hospital, Chicago; IL, USA,

^IIIProfessor of the Orthopedics department, Laboratory of Bait Analyzes, Children's Memorial Hospital, Chicago, IL, USA,

^IVFull Professor Associate to the Orthopedics and Traumatology Department at UNIFESP/EPM,

^VDoctor Professor Associate to the Orthopedics and Traumatology Department at UNIFESP/EPM

^VIChairman of the Orthopedics and Traumatology Department at UNIFESP/EPM

^{Correspondence}

SUMMARY

This study examines the influence of unilateral hip dislocation or subluxation in the gait of 20 low-lumbar myelomeningocele patients, community ambulators with AFOs and crutches, utilizing gait analysis.

The patients were divided in two groups, Group 1 – 10 patients: complete absence or presence of symmetrical hip contractures (flexion and/or adduction) and Group 2 -10 patients : presence of unilateral or asymmetrical hip contractures. Pelvic and hip kinematics were analyzed to assess the symmetry of them, between the involved and the non-involved side. Gait was considered symmetrical in 7 studies in Group 1 and in 2 studies in Group 2. Assymmetrical gait was found in 3 studies of Group 1 and in 8 studies in Group 2. Gait symmetry was correlated with the absence of hip contractures or bilateral symmetrical hip contractures (Group 1). The asymmetrical pattern was related mainly to the presence of unilateral or unequal hip contractures. This study shows that gait assymetry can not be attributed only to the hip instability but seems to be more related to unequal hip contractures, thus gait symmetry could probably be achieved with the correction of the contractures involved, either by soft tissue or bone procedures.

Key words: Myelomeningocele; Hip dislocation gait; Contractures

INTRODUCTION

The myelomeningocele is one of the defects of the closure of the neural tube that results in distal neurological deficit to injury. The patients can be classified according to the neurological level in thoracic, upper lumbar, lower lumbar and sacral⁽⁸⁾. Patients of lower lumbar typically show muscular strength degree 3 or higher in quadriceps and medialis isquiotibials; however it does not show function in the gluteus muscles.

The advances in the neurosurgical and urological management of these patients have increased their perspective of life and development and maintenance of the gait during life became a real objective. The neurological level seems to be the most important factor to determine the deambulatory potential. Eighty percent of the children with lower lumbar should remain as community ambulators during their lives. Other factors that influence the deambulatory capacity are the lower limbs and vertebral column deformities⁽¹⁾.

Around half of the patients with myelomeningocele will show some hip instability degree during the first ten years life. This occurs due to the unbalancing between the flexor forces and extensors and adductors/abductors which act in the articulation is a characteristic of the lower lumbar patients. The correlation between hip dislocation or subluxation and the decreasing or loss of the walking ability in patients with myelomeningocele has been discussed in the literature. Some studies do not show correlation between the hip performance and the capacity of gait. Other authors, however; show that patients with reduced hips would have the benefits in the gait with the reduction, specially in the unilateral cases because of the possible development of discrepancy of the lower limbs length, pelvic obliquity and scoliosis⁽¹³⁾. Some studies support the idea of surgical reduction in case of patients with unilateral instability. It must be emphasized that only one of these studies were based in objective criteria of Laboratorial gait analysis and the surgical indication is still a controversy to be discussed. There is a high incidence in the surgical complications in these procedures, as stiffness, pathological fractures and recesive of stability for redislocation, which could, by itself, lead to the deambulatory decreasing capacity ^(3,410,12).

The laboratorial analysis of the gait allow the understanding of the of normal and pathological gait characteristics, as the neuromuscular diseases have been studied, mainly the cerebral palsy⁽⁷⁾. In the myelomeningocele, the studies described peculiar characteristics to the gait of the sacral and lower lumbar patients, being rarely approached the unilateral instability effect of the hips on the gait^(3,5,14,15). Considering on one hand the importance of developing and keeping the gait of these children, on the other hand, the problems related to the surgical treatments, it is important to establishing the exact way which factors influence the deambulatory capacity, in order to avoid unnecessary surgeries and treatments. Thus, this study purpose to analyze the patient's gait with myelomeningocele of lower lumbar level and unilateral hip instability, ambulators using solid ankle foot orthoses (AFO's) and crutches, comparing patients with unilateral contractures or asymmetrical flexion and/or abduction of the hips with the ones who do not have them, or show them in a symmetrical way. Our purpose is to study the influence of these contractures on the gait of these patients.

METHODS

Twenty patients with mylomeningocele in the lower lumbar level were analyzed, according to Hoffer definition (muscular force degree 3, at least in the adductors and flexors of the hip, flexors of the knee and dorsal-flexors of the feet). Thirteen patients were female and seven male, whose age average was 10,2 years old (ranging from 5 to 8 years old). All the patients were from community ambulators (according to Hoffer) and walk with the (AFO's) and crutches⁽⁸⁾. All the patients showed dislocation and sub-luxation (Definite by Index of Reimers⁽¹¹⁾ as migration percentage equal or higher of 33%)

Any of the patients showed scoliosis higher than 20 degrees or neurological complications related to mylomeningocele in at the time of the gait analysis. Any of the patients had had hip bone surgery before the studies.

The patients were sub-divided in two groups, according to the hips contractures – flexion and/or adduction. The flexion contractures were measured by the Thomas test and were considered to be severe when higher than 30 degrees, moderate, when between 20 and 30 degrees and mild if less than 20 degrees. The adduction contractures of the hips were measured with the hips flexed and were considered severe when below of 10 degrees abduction, moderate, if the abduction was between 10 and 30 degrees and mild when if more than 30 degree of the hip abduction was possible. Group 1 understood 10 patients who did not show contractures (flexion and/or adduction) of hips or show themselves in a symmetrical shape (Table 1). The average age in group 1 was of 9, 8 years old (ranging from 5 to 15 years old), there were 8 female patients, and 2 male. Nine patients showed the right hip instability and one in the left hip.

In group 2, there were 10 patients with contractures of unilateral or asymmetrical hips adduction and/or flexion, which were measured as already mentioned. The average of age of this group was 10, 5 years old (ranging from 5 to 18 years old). Five were male and five female. Eight patients had the right hip instability and two of the left hip (Table 2).

Two patients had discrepancy in the lower limbs length of more than 3 centimeters, in these analysis of the gait were done with the use of compensation of the shoe.

The three-dimensional analysis of the gait were done with the use of the Vicon system (Oxford Metrics Inc. USA). The patient was submitted to physical test and to the manual muscular test before the analysis, in order to evaluate the articular mobility and set up the presence and degree of contractures in the hips. To the analysis of the gait muscular electrodes surface were used and the patient was instructed to walk into a self determined speed. At least three taking were collected and the most representative was analyzed. Data of cinematic, kinetics and electromyography's were collected. In this study was selected only the cinematic data in relation of the pelvic obliquity, pelvic rotation, adduction/abduction and hip flexion/extension, in addition the linear parameters gait (speed, cadence and length of the step). The cinematic data were analyzed and classified into different or similar, depending if there was or not difference between the right and left sides, besides the alteration of degree was evaluated in relation of the normal gait. The gait was classified in symmetrical (if the right and left sides showed similarity in the pelvis and hips cinematic) (Figure 1) or asymmetrical (when the kinetic was different between the sides) (Figure 2).

As it is a retrospective study, based on the analysis of pronctuary and image exams of the patients, there was no permission to be informed. This study was approved by the Ethic Committee of Research at UNIFESP/EPM

RESULTS

The data of the patients and parameters of the gait and the hip nad pelvis cinametic in groups 1 na 2 are shown in the tables 1 and 2, respectively.

There was no statistical difference between the groups about age, length discrepance of the lower limbs, speed, cadence and length step. The gaits parameters, however; were slightly higher in group 1 (Table3)

Seven patients in group 1 were considered symmetrical due to the absence of differences between the affect side and non-affect side, in relation of the cinematic of the pelvis and hips. Four of them did not have contractures of adduction and/or flexion of the hips. Three patients showed differences in the pelvis and hips cinematic between the sides and were classified as asymmetrical; all of them showed adduction contractures and/or hip flexion (Table 1).

Two studies in group 2 showed symmetrical gait about the pelvis and hip cinematic. Both presented moderate contractures of adduction in the affected side. Eight patients showed asymmetrical gait, being the abduction/adduction of hips in the analysis was the most aterated side. Most of them presented moderate adduction contractures in the affected side. (Table 2).

There were significant satatistics differences in comparison to the number of patients with or not symmetry in the two groups, the symmetry of the gait was more related to the absence of contractures of the hip or with the presence of the same magnitude contractures, bilaterally (Group 1) (Table4).

Comparing the average of age, percentage of the head of the femoral migration, discrepancy in the lower limbs length, speed, cadence and length of the step between the cases with symmetrical and asymmetrical gait, there was not statistics difference in any of the groups. (Tables 5 and 6).

DISCUSSION

Around 80% of the patients with myelomeningocele of lower lumbar level are able to walk independently during the adult life⁽¹⁴⁾. The correlation between the subluxation or dislocation of the hips and the deambulatory capacity, however; needed objective demonstration in the literature. According to our knowledge there is only one study that evaluated the unilateral hip instability using the gait laboratorial analysis in patients with myelomeningocele, which showed flexion and/or adduction, even mild can lead to an aynmetric pattern.

In order to obtain and keep an efficient gait, it is necessary to find stability in the stance phase, showing good ways of progression and preserve⁽⁷⁾. In the neuromuscular diseases is common to have excessive vertical deviation center of the gravity, generally placed anteriorly to the second sacral vertebra. The gait asymmetry corresponds to the deviation center of the gravity, that can cause an increase of energetic waste⁽¹⁴⁾. It can be related to the difference of muscular strength or articular movement between the sides. Consequently, the to pursue the development of the gait symmetry of patients with myelomeningocele is a factor that can influence the deambulatory capacity maintenance of deambulatory capacity during life. Standard Symmetrical gaits patterns were the most found in patients of group 1, who did not show hips contractures or show them in the same magnitude between the sides, and this had statistics significance in our data. Asymmetrical patterns of standard of the kinetic of abduction/adduction rotation and pelvic obliquity were presented in the hips with unilateral contractures, particularly adduction, which can be led to the conclusion that the correction of these contractures should be the purpose of the treatment of these patients, idea which was already defended by other authors⁽¹⁰⁾.

1. Gait symmetry

In group 1, 7 patients showed symmetrical pattern of the gait and three, asymmetrical. Four of them did not show hips contractures and the other three showed them in a moderate or mild degree. The 3 patients with asymmetrical gait show difference in the pelvic obliquity or in the hip abduction/adduction and also showed hip contractures in the flexion and /or adduction.

In group 2, 8 patients showed differences in the kinematic of the hips between the sides, mainly in the hips abduction/adduction, most showed severe contractures in adduction at the affected side. The asymmetrical of the gait can be explained for the necessity of, in the mylomningocele, to be necessary abduct the hip in the swing phase during the gait with crutches, in order to easy the foot liberation. As showed by other authors, deformities which limited the abduction (as contractures in adduction) interfere negatively in the gait, leading to a asymmetry pelvis obliquity and consequent of the gait⁽¹⁵⁾. Both cases which showed the symmetrical gait in group 2 showed moderate hip aduction contractures at the affect side. These had speed, cadence and length of the step higher than the average of the group, suggesting that, even with the different hips contractures presence between the sides, if the gait pattern is symmetrical, the parameters of the gait are not harm. The literature shows a direct relation between the speed and energy expenditure in patients with myelomeningocele⁽⁶⁾. Our study revealed that the velocity was higher in patients of Group 1, but this demonstration did not have statistical significance, probably because of the small group of analyzed patients. In the two patients of group 2, who showed symmetrical gait, the linear parameters of the gait were above the average of the group. Other studies will be necessary, to confirm these data.

2. Linear parameters gait, leg length discrepancy and migration percentage.

In our groups, divided by the asymmetrical hip contractures, we could not demonstrate statistical significant diference about the discrepancy of the limbs length, percentage of the femoral head migration, velocity, cadence and step length, although these parameters were slightly superior on group 1, showing the absence of the hips contractures or its presence bilaterally at the same magnitude, does not influence negatively the gait (Table 3). Perhaps the lack of statistical significance can be attributed to the small number of analyzed cases.

3. Pelvic obliquity

In study 1, 8 patients showed the same bilateral pelvic obliquity pattern and two, different degree between the sides (both show asymmetrical pattern of gait and contractures in flexion and /or adduction). In group 2, 8 patients showed the bilateral obliquity pelvic degree, and two, different degree between both of them (both showing asymmetrical gait pattern).

Most of the patients of this study showed increase in the pelvic obliquity, not being this the cause of the hip instability. The excessive pelvic obliquity in myelomeningocele has also been shown in other studies and it is because the in Trendelenburg gait, characteristics of this population, due to the weakness of the gluteus medium muscle. Besides the lateral deviation of the trunk is the cause of loose of the feet in the terminal support phase, where there is paralisy of the dorsal-flexor foot muscle, what cause more pelvic obliquity^(5,15).

As showing in the literature, the maintance of the pelvic alignment is very important for the deambulatory capacity⁽⁹⁾. In the myelomeningocele two are the main causes of this alignment; the presence of scoliosis and the weakness of the medium gluteus, not including the unilateral hips instability. None of our patients showed important scoliosis, however all of them made part of the lower lumbar level, where the muscular strength of the medium glutinous is decreased or does not exist.

4. Anterior pelvic tilt

Only one patient of group 2 and none of group1 showed different anterior pelvic tilt degree between the sides. This homogeneous distribution of these alterations in the pelvis kinematic parameters between the groups can be likely explained with own characteristics of these patients, with extensor hips muscular paralysis, use of crutches and the contractures of the hips (in our study, most of the cases, were slight or moderate). Furthermore; the AFO's usually exarcebates the anterior pelvic tilt, because it decreased the anterior tibia advance that occur when the paralysis of the ankles dorsal-flexors exist. Thus, in order to keep the center of the gravity of the support base, the patient tends to bend the pelvis anteriorly^(5,15). It is possible that with the severe flexion contractures there is more alteration in the anterior pelvic tilt between the sides.

5. Pelvic rotation

Only three patients showed asymmetrical gait with different pelvic rotation pattern between the sides, all of group 2. All of them showed contractures in the hip flexion contractures on the affected side. The increase of the pelvic rotation is a factor which makes easier the body progression when there is weakness or paralysis of the extensor muscle of hips and ankles dorsal-flexor, therefore; a myelomeningocele characteristic. Excessive pelvis rotation was also seen after ilipsoas muscle transference that used to be the hips instability treatment⁽⁵⁾. In our study where any patients had had this surgery, this fact could be explained with the presence of the unilateral flexion of the hips in almost all cases.

6. Abduction/adduction

In group 1 there were only two patients who showed differences in the kinematic behavior in relation of the hips abduction / adduction, causing the gait asymmetry, probably because, if the adduction contractures were present, they were with the same magnitude bilaterally. In group 2, 7 cases showed different kinematic pattern between hips of abduction / adduction. Five of them showed unilateral hip adduction contractures in the affected side. This explains the asymmetrical gait, the most found in group 2. Other authors found kinematic abnormalities in adduction / abduction of the hips in myelomeningocele, although the presence in hips contractures were not mentioned^(5,15). They showed that the patients without contractures or the hips instability, generally there is an increase of the hip abduction in the swing phase of the hip abduction, due to the excessive pelvic rotation. According with our data, the abduction / adduction kinematic abnormality were more frequent in Group 2, possibly due to the hip unilateral contractures, especially in adduction, which helped in the creation of the asymmetrical gait pattern character.

7. Flexion / extension

Different pattern between the sides regarging kinematic of flexion / extension of the hips were found in 4 patients of Group 2 (three of them showed hip flexion contractures only in the affected sides). None of patients of Group 1 showed this difference between the sides, showing again the gait asymmetry due to the kinematic alteration of hips flexion and extension was related to the unilateral contractures presence.

CONCLUSION

Pacients with unilateral dislocation or subluxation hips can show a symmetrical gait, therefore effective in order to preserve energy as it is shown in the literature, but a little confirmed by the laboratorial gait analysis, the fact of the hips to be or not reduced, is not the cause of the gait asymmetry found in these patients, which is much more related with the unilateral or asymmetrical hip adduction and/or flexion contractures. Therefore, the hips reduction surgery, supported by some authors, seems not to be indicated. As it seems to be a big unbalancing between the hips muscular strength, even doing the open reduction and the femoral and pelvic osteotomies, the incidence of reluxation and other complications, such as, stifness, is very high. Our study shows that all the efforts must be directed in order to avoid and correct the unilateral contractures of the soft issues of the hips, especially the adduction and flexion ones, what have been showed in other studies^(2,12,13).

Procedure as adductors myotomy, or if necessary, femoral valgus proximal osteotomy, and lengthening of the psoas muscle, surgeries simpler than the hip reduction, could be necessary. In patients with myelomeningocele and unilateral luxation or subluxation hips, the orthopedics purpose should be the obtain a symmetrical gait pattern, preventing or avoiding hips contractures and ignoring the dislocation. Thus, much less complications will occur and these patients will keep walking into the adult life⁽⁹⁾.

REFERÊNCIAS BIBLIOGRÁFICAS

Study done in the Laboratory of Bait Analyzes at the Children's Memorial Hospital, Northwestern University Medical School, Chicago, IL, USA, Medical Paulista School /UNIFESP and Caxias do Sul University.

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Publication Dates

• Publication in this collection
  16 June 2004
• Date of issue
  June 2004

History

• Accepted
  09 Apr 2004
• Received
  06 Aug 2003