Surgical treatment of pathological kyphosis

Abstracts

Foram estudados 13 pacientes com cifose patológica de diferentes etiologias (Doença de Scheuermann, espondilite anquilosante, congênita, tuberculose vertebral, sequela de laminectomia e síndrome de Morquio), que foram submetidos ao tratamento cirúrgico. A cifose pré-operatória variou de 75 a 100 graus (média 73,3 graus) e a média dos valores após o tratamento cirúrgico foi de 42,3 graus. O tipo de tratamento realizado estava relacionado com as características da cifose (raio longo ou curto, flexibilidade e magnitude), e são apresentadas as diferentes técnicas e filosofia de tratamento dos autores para o tratamento cirúrgico dessa modalidade de deformidade vertebral.

Deformidade vertebral; Cifose vertebral; Tratamento cirúrgico da cifose

ARTIGO ORIGINAL

Surgical treatment of pathological kyphosis

Helton Luiz Aparecido Defino^I; Andrés Edgard Rodriguez-Fuentes^II; Flávio P. Piola^III

^IAssociate Professor

^IIPhD Professor

^IIIAssistant Doctor

^{Correspondence}

SUMMARY

Thirteen patients with pathologic kyphosis from different ethiologies (Scheuermann's disease, ankylosing spondilitis, congenital, vertebral tuberculosis, post laminectomy and Morquio's syndrome) who underwent surgical treatment were studied. Preoperative kyphosis ranged from 75° to 100° (average 73.3°) and postoperatively averaged 42.3°.

The treatment performed was based on kyphosis characteristics (long or short radius, flexibility, magnitude). The different techniques are presented as well as authors' philosophy for surgical treatment of this kind of vertebral deformity.

Key words: Spinal deformity; Kyphosis; Surgical treatment

INTRODUCTION

The spine presents 4 balanced sagittal curves (cervical lordosis, thoracic kyphosis, lumbar lordosis and sacrum-coccigeal kyphosis), which presence has been interpreted from a biomechanical point of view as increasing mechanic resistance of the spine, increasing its ability to absorb shocks as well as its flexibility^(1,3).

Normal limits of vertebral sagittal curves is controversial. At thoracic spine, values above 50 to 55° are considered as a kyphotic deformity and at cervical or lumbar spine, any curve with a dorsal angulation may be considered as a pathologic kyphosis^(2,4,9).

Etiology of pathologic kyphosis includes a number of diseases (congenital, growth alterations, trauma, tumors, infectious processes, degenerative or iatrogenic) which disturb spine biomechanics in its basic functions.(Figure 1). Elements taking part in anterior portion of the spine (vertebral body and intervertebral disc) resist to compression forces and the posterior ones (lamina, joints, supra and interespinous ligaments) resist traction forces. A kyphotic deformity takes place when the spine is unable to resist to one or both forces (compression or traction)^{(10, 11)}.

Treatment of pathologic kyphosis is to be surgical, except in the case of Scheuermann's Disease with angles below 70 to 75°, which present good results with conservative treatment⁽⁶⁾. The surgical treatment chosen for each pathologic kyphosis is closely related to biomechanic characteristics of the deformity, and also to the presence of nervous structures compression, with many different technical options to solve it^{(5, 6)}.

The objective of this work is to report the results of surgical treatment of pathologic kyphosis from different etiologies based on evaluation parameters of clinical and radiographic nature, and to illustrate the surgical treatment methods we have been using.

MATERIAL AND METHODS

Thirteen patients who presented with pathologic kyphosis from different etiologies and underwent surgical treatment at Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto - USP were evaluated.

General characteristics of the patients are in Table 1. Pathologic kyphosis was due to Sheuermann's Disease in 5 patients, ankylosing spondilitis in 3, congenital in 2, vertebral tuberculosis in 1, post laminectomy (for resection of a neural tumor) in 1 and Morquio syndrome in 1 patient. Age ranged from 9 and 60 years (average 24 years); 6 were male, 7 female. The deformity was at thoracic spine in 3 patients, and thoracic and lumbar in 10 patients.

The degree of pre operative kyphosis ranged from 75 to 100° (average 73.3°) in this group of patients. In thoracic spine the kyphosis ranged from 75 to 100° and in thoracic and lumbar spine from 45 to 88°. The deformity was rigid in 4 patients and flexible in the remaining 9. Two patients had neurologic deficit (lower limbs paresis with piramidal release signs) (Figure 4).

The treatment was related to kyphosis characteristics (long intenor short radius, flexibility, magnitude). In long radius and flexible curves, a posterior instrumentation and arthrodesis was initially performed, followed by anterior arthrodesis, while in long radius rigid curves it was initially performed an anterior release followed by a posterior instrumentation and arthrodesis (Figure 1). In patients with ankylosing spondilitis a posterior osteotomy, uni or multisegmental was performed, followed by a fixation and posterior arthrodesis (Figure 2). Posterior arthrodesis followed by fixation and arthrodesis, according to the technique(7) was performed in one patient with Sheuermann’s disease (Figure 3).

In short radius curves, with an angular and rigid kyphosis, it was initially performed an anterior release and decompression of nerve structures as necessary, followed by anterior and posterior arthrodesis, and posterior fixation whenever allowed by bone tissue status.

In rigid curves where it was not intended an angular correction, the treatment was in three steps, starting with a posterior release, followed by an anterior release and arthrodesis, with a posterior fixation with arthrodesis (Figures 4 and 5).

Posterior instrumentation was used in 11 patients, using a pedicular screws system (USIS) in 6 patients; hooks and pedicular screws (Cotrel-Dubousset) in 5 patients. In two patients it was used no fixation, and in 1 patient only anterior arthrodesis was performed and anterior arthrodesis with decompression together with a posterior arthrodesis in another patient.

Anterior arthrodesis was performed in 6 patients, using cortico-cancellous grafting in 4 patients, and fibula in 3.

In postoperative period, 4 patients didn't use any external immobilization, 8 used a plaster cast, 1 used a Jewett vest for a period ranging from 3 to 9 months (average 4.7 months).

The principal parameters evaluated in this group of patients was radiographic correction of the deformity and maintenance of the results during follow-up, bone graft integration, improvement of neurologic evaluation and esthetic result.

RESULTS

Patients were followed-up for a period ranging from 12 to 36 months (average 23.5 months).

Radiographic correction of the deformity was achieved in 11 of the 13 patients, and the kyphosis, which averaged 73.3° degree pre operatively changed to 42.3° post operative. Correction was not observed in one patient with Morquio's syndrome, in who only an anterior arthrodesis was performed, and in another patient who presented with medullar compression and was submitted to anterior decompression, together with a posterior arthrodesis without instrumentation due to the status of the bone tissue.

The remaining patients displayed an important deformity correction, directly related to flexibility of the deformity, release of the involved tissues and instrumentation of the involved vertebral segment (Figures 6 and 7). Maintenance of the correction was observed, and a loss of 5° was observed in 4 patients, with no repercussion on the treatment results.

Neurologic deficit remitted after decompression of vertebral canal in both patients presenting with lower limb paresis with signs of pyramidal release.

Complications observed were a superficial infection in 1 patient, deep infection in 1 patient, rupture of pedicular screw in 1 patient, loosening of the implants and loss of correction in 1 patient (Figure 2) and pain at the place bone graft was removed (iliac bone) in 2 patients.

After surgical treatment patients were able to fully perform their professional activities, and the impairment found in some was related to the original disease, such as ankylosing spondilitis or Morquio's syndrome. In the remaining patients, after the surgery they could perform their usual professional activities, and were satisfied regarding correction of the deformity.

DISCUSSION

This study is composed by an heterogeneous group of kyphosis patients, and our main objective in presenting such an study to present some aspects of this kind of spinal deformity, as well as our treatment philosophy, which is directly related to the different variables linked to the deformity, such as flexibility, curve radius and presence of a neurologic deficit.

Pathologic kyphosis is the clinical and radiographic expression of an heterogeneous group of diseases affecting the spine due to a supportive failure of the anterior part of the spine, or loss of resistance of the posterior elements to traction stress, which can be present both as isolated as together, resulting in a progressive deformity of the spine, sometimes joined by neurologic deficit due to compression of nervous tissues inside the vertebral canal. As the kyphosis progresses, the weight bearing axis displaces towards the front, increasing the trend of progressive kyphosis, so making a vicious circle only interrupted by restoring of the balance^(1,8).

Understanding the concept of sagittal balance of spine, as well as the biomechanical aspects which are present in this kind of deformity are fundamental in planning its treatment which should also take into consideration special features of the curve, such as radius, flexibility and nerve tissue compression^(5,6,10).

The largest group in this series, and also our experience in surgical treatment, is represented by Scheuermann's disease kyphosis, where the classical treatment recommends release of anterior structures and placement of bone graft between the vertebral bodies, associated to posterior arthrodesis plus instrumentation, allowing correction of the deformity in very satisfactory degrees as reported in the literature as well in as observed in our patients^(5,6).

In this kind of kyphosis, an innovative treatment recently proposed⁽⁷⁾ recommends only a posterior approach, with deformity correction through a posterior osteotomy at several levels, plus a posterior arthrodesis and instrumentation. This technique is less diffused among us, and, nevertheless our limited experience, it looks very much promising, and we believe that its greatest advantage is the performance of a single procedure, without need of a torachotomy, even though this procedure may currently be made esdoscopically.

In patients with anky-losing spondilitis we noticed in current literature a trend to perform subtraction osteotomy at one single level^{(5, 6)}, however multiple osteotomies have been reaching excellent results in our patients, and we've been preferring this procedure where intervertebral discs are not ankylosed, keeping the indication of subtraction osteotomy with vertebral pediculum resection for those situations where intervertebral discs are ankylosed.

Development of new vertebral fixation devices has allowed a better correction and handling of the kyphotic deformity, once bone tissue nature and other variables related to deformity rigidity make its use possible. In some situations it is possible to reach a correction of the deformity through a previous posterior release, resulting in 3 surgical times, as illustrated in patient in (Figure 4). This procedure depends on the treatment philosophy of the surgeon, and the treatment target. We believe that it is valid to use a more complex treatment to reach better esthetic results, however we should recognize that there are situations where deformity correction may result in increased morbidity and treatment risk, when the treatment is performed aiming mostly recovery of neurologic deficit and interruption of progression of the deformity.

As new fixation systems, surgical and anesthesic techniques, use of evoked potential during the procedure, become available, limits of correction and treatment targets will be closely related to treatment philosophy and skills in correction techniques, and only long term results using these techniques would allow confirmation of the best treatment options in this spinal deformity.

REFERÊNCIAS BIBLIOGRÁFICAS

*Work performed at the Biomechanics Departament, Medicine and Rehabilitation of Locomotor System fron Faculdade de Medicina de Ribeirão Preto-USP.

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Publication Dates

• Publication in this collection
  21 Sept 2005
• Date of issue
  Mar 2002

History

• Received
  25 Feb 2000
• Accepted
  27 Nov 2001