Modified Vertebral Column Resection Technique for Correcting Congenital Rigid Angular Kyphosis and its Effect on Functional Outcomes

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1 DOI: /JCDR/2016/ Orthopaedics Section Original Article Modified Vertebral Column Resection Technique for Correcting Congenital Rigid Angular Kyphosis and its Effect on Functional Outcomes Chaitanya Chikhale 1, Amey Swar 2, Ketan Khurjekar 3 ABSTRACT Introduction: Congenital angular kyphosis is progressive in nature and surgical intervention is required to prevent the progression and worsening of neurology. Aim: This study presents a modified technique of performing a single stage all posterior vertebral column resection and analyses its efficacy in correcting the deformity. It also deals with the impact of these deformities on health related quality of life of these patients and the effect of surgery on the same. Materials and Methods: Data was collected prospectively from 10 patients with thoracic and thoraco-lumbar rigid angular kyphosis. All deformities were congenital in origin. Five of them were females and five were males. Modified Vertebral Column Resection (MVCR) was performed in all patients. Patients were reviewed at three months, 6 months and final follow-up was done at one year. Results: The preoperative kyphosis angle average of 78.7 ±10.1(60-90) degrees which was postoperatively corrected to 19.7 ± 7.7 (5-30) degrees. There was significant improvement in SF-12 PCS scores at one year follow-up from (SD ±1.35) to (SD ±5.29) (p =<0.001). Two out of ten patients had complications. At final follow-up, all showed satisfactory healing and fusion mass. Conclusion: High degree rigid congenital kyphotic deformities demand early surgery. Single stage posterior only Vertebral Column Resection (VCR) is a safe and effective method to correct these deformities. MVCR is advantageous to surgeon and helps minimize the complications. Surgery helps to improve the health related quality of life of these patients. Keywords: Congenital kyphosis, Modified VCR, Osteotomy of spine, Quality of life, Sagittal imbalance Introduction The primary curve in spinal column is kyphosis and proper degree of kyphosis in the thoracic region which is normally in the range of 20 o -40 o is required for maintaining the sagittal balance of the body [1]. Sagittal balance enables a person to maintain erect posture and ambulate efficiently with minimum expenditure of energy. However, various pathologies can lead to increase in the kyphotic angulation at the thoracic region thereby impairing the sagittal balance viz., congenital kyphosis, post-traumatic, post-tubercular or infectious spondylodiscitis, post-laminectomy, pathological fractures leading to kyphosis, neuromuscular diseases, inflammatory spondyloarthropathy like ankylosing spondylitis which in particular causes round back kyphosis and Scheuermann s disease. This study deals with probably the most difficult of them to treat i.e., congenital kyphosis because these curves have the potential to progress rapidly and thereby cause internal cord compression and neurological deficit or even paraplegia [2]. Congenital kyphosis was classified by Mc Master and Singh into Failure of formation (Type 1); Failure of segmentation (Type 2) or a combination of Failure of formation and segmentation (Type 3) [3]. The exact cause though not clear Tsou PM have proposed that it is probably the failure of local vasculature that is the cause for these congenital defects [4]. In the developing part of the world where this study was performed clinicians often come across such cases but only a few get the proper desired treatment because of either the lack of knowledge on the part of the clinician, neglect by parents, false beliefs regarding this deformity, fear of undergoing surgical corrections, misconception of landing up in paralysis post spine surgery or financial constraints on the part of child s parents. If left untreated congenital angular kyphosis progresses and results in complications like rigid kyphotic deformity, respiratory insufficiency, neurological deficits and functional disabilities [2,3]. One of the objectives of this study was to bring forth the fact that such deformities are treatable in right hands and good cosmetic corrections with minimal risk if treatment is taken at proper time and at an equipped set up; so that the treatment procedures find acceptance not just by word of mouth but on a substantial clinical evidence. To correct these deformities surgical interventions are often required because orthotics and physiotherapy have often failed to provide any relief in terms of correction of deformity [5]. Various surgical approaches and techniques have been described which includes anterior approach alone or combined with posterior surgery or posterior surgery alone, to correct these deformities [5-10]. Various osteotomies that are used to treat the kyphotic curves include Vertebral Column Resection (VCR), Pedicle Subtraction Osteotomy (PSO) or multilevel Pontes or Smith Peterson osteotomies [11]. This study presents a modified technique of performing a single stage all posterior VCR and analyses its efficacy in correcting the deformity. It also deals with the impact of these deformities on health related quality of life of these patients and the effect of surgery on the same. MATERIALS AND METHODS The research protocol was approved by the institutional review board. In this prospective study 11 consecutive patients with congenital kyphosis admitted for surgical management at Sancheti Institute for Orthopaedics and Rehabilitation, Pune from May 2012 to November 2013 were registered. Informed consent was Journal of Clinical and Diagnostic Research Sep, Vol-10(9): RC17-RC22 V. 1 17

2 18 obtained from all the patients recruited in the study. After excluding one patient who was lost to follow-up, 10 subjects (follow-up ratio: 90%) were analysed for a mean follow-up of one year. There were five males and five females. The average age of the study group was 16.4 (7-25) years. Two patients were Frankel D and rest eight were Frankel E. five patients had the apex of their curve in thoracic region (D4-D9) and 5 had the apex in thoracolumbar region (D10-L2). The patients who had clinico-radiological diagnosis of congenital kyphosis were included in the study. Patients whose deformity was not congenital in origin were excluded from the study so were the patients who were previously operated for congenital kyphosis correction. All the patients were evaluated pre-operatively with whole spine scannograms in antero-posterior and lateral views as well as traction x-rays and push prone films were obtained to look for the flexibility of the curve. Severity of the curve was measured using the Cobb's method. Pre-operative MRI was done for all the patients to rule out spinal cord anomalies like tethering of the cord or meningo-myelocoele. CT-scan was done as a part of operative planning to see the bony morphology which is particularly difficult to see in these cases on plain x-rays due to the sagittal with or without coronal plane deformity. Also, all the patients were subjected to 2D echocardiogram, ultrasonography of the abdomen and pelvis and chest x-rays to rule out cardiac, renal and respiratory anomalies which are frequently found to be associated with congenital kyphosis. In our series one patient had a low lying tethered cord for which she was operated previously elsewhere. No other anomalies were found. All the patients were assessed preoperatively and postoperatively at three months, six months and then at end of one year with SF-12 score, VAS scale and Frankel s grading. Kyphosis angle was documented at every follow-up on lateral radiographs. The statistical analysis was done by an independent statistician. Correlation between pre and postoperative VAS scores, SF12 scores and Cobb's angle were analysed using the paired Students 't'-test. The p-value of less than 0.05 was considered significant. OPTUM TM SF-12 V2 software was used for analysing the SF-12 PCS questionnaire. Surgical Technique The patient was positioned prone under general anaesthesia on a standard radiolucent operating table, bolsters were placed and the table was adjusted such that adequate space for maneuvering the image intensifier was available. Proper positioning is very important to obtain useful C-arm images during the surgery particularly in these cases where the anatomy is distorted. With the patients placed in prone position, a straight posterior midline incision was given. Exposure was done and poly-axial pedicle screws are inserted according to the preoperative plan. In thoracic spine, three spinal segments above and three spinal segments below the vertebrae were instrumented with pedicle screw and rod construct. While at thoracolumbar junctional levels preferably 4 spinal segments above and 3 spinal segments below were included in fusion. Levels are confirmed on C-arm and usually a cephalad to caudad order is followed. All patients were operated with a single stage posterior only vertebral column resection but the technique used was the modification of the conventional VCR s. Temporary rod was placed on the convex side of the deformity to support the vertebral column. Vertebra causing the internal gibbus is removed along with the one healthy disc above and below. In thoracic region costotransversectomy was also added at the apex of the deformity. Vertebral resection is attempted from concave side of the deformity using modified VCR technique. Once the complete resection of the vertebral body is performed [Table/Fig-1], which is an integral part of VCR, the inter body cage is inserted from concave side which is a titanium mesh cage filled with bone graft. Temporary rod was [Table/Fig-1]: Osteotomy completed as shown by passage of gauze piece but the posterior midline is kept intact and removed only at time of closing the osteotomy. [Table/Fig-2]: Deformity correction done, interconnector rod can be seen at site of osteotomy. removed and definitive rods are put on both the sides. Anterior column was thus reconstructed by these titanium mesh cages. Till these steps posterior lamina at the site of VCR was not removed. Osteotomy site was then closed over anterior titanium mesh cage for which laminectomy was done at this stage. A 6 mm titanium rigid rods were used, which took anchorage in proximal segment and gradually they were fixed to the vertebral column distal to the osteotomy. Anterior cage prevented buckling of the spinal cord and subsequent neurological deficit. This is a Spine to rod technique where Rods are contoured as per anatomical curvature of the human body, i.e., thoracic kyphotic and lumbar lordotic curve was given to the rods. Vertebral column was realigned to the pre-bent anatomical titanium rods. Gradual fixation of the rods ensured safety of the procedure. Realignment of the rods and vertebral column was checked with intraoperative fluoroscopy. Bed for posterior fusion was prepared by decorticating the remaining posterior elements of the levels above and below. Local autograft was used for this purpose [Table/Fig-2]. During the surgery, absorbable haemostatic gauze and gelatin sponge were packed at the osteotomy sites for adequate haemostasis. Closure was done over a suction drain in layers. Postoperative Care Patient was kept in ICU under monitoring for first 24 hours after surgery. Drain removal and change of dressing done on post-op day two of surgery. Total contact orthoses were given to patients and were mobilized. Supervised rehabilitation was done initially. Patients were discharged after suture removal and if the progress on rehabilitation was satisfactory. RESULTS The study includes 10 patients (five males and five females). The average age of the study group was 16.4 (7-25) years. The average operating time was 230 minutes and average blood loss was 650 ml with three patients requiring post op packed cell transfusions [Table/Fig-3]. Journal of Clinical and Diagnostic Research Sep, Vol-10(9): RC17-RC22

3 Sr. no Diagnosis Sex Age Kyphosis angle 1 Kyphosis with apex at D12 2 Kyphosis with apex at D Kyphoscoliosis with apex at D4-5 4 Kyphoscoliosis with apex at D5-6 5 Kyphosis with apex at D 9 6 Kyphosis with apex D8-9 7 Kyphoscoliosis with apex at D 12 8 Kyphoscoliosis with apex at D11 9 Kyphosis with wedging at L2 10 Kyphoscoliosis with apex at D 9 Preop Postop VAS Score SF-12 (PCS) The average preoperative kyphosis angle was 78.7±10.1(60-90) degrees which improved postoperatively to 19.7±7.7 (5-30) degrees The average reduction of kyphosis angle was by 59±9.3(45-78) degrees with p-value of < Thus, there was a statistically significant correction of deformity obtained with the Modified vertebral column resection technique [Table/Fig-4]. The average VAS score pre-operatively was 7.8±1.03 (6-9) at 6 months post-operatively the average VAS score was 5.3 ± 1.15(4-7) and at one year post-operatively it was 2.7±1.15 (1-5). There was a significant improvement of VAS score when six month postoperative (p-value 0.004) and one year postoperative VAS score (p-value 0.005) was compared with pre-operative VAS score [Table/Fig-5]. The mean preoperative SF- 12 score was (SD ±1.35). The mean 6 months postoperative SF 12 score was (SD ±3.44) and mean 1 year postoperative SF12 score was (SD ±5.29). The p-value was significant suggesting there was significant Preop 6m 12m Preop 6/m 12/m M F F F M F F M M M [Table/Fig-3]: Patient demographics and parameters analysed. [Table/Fig-5]: VAS scores (Preoperative and postoperative follow ups). improvement postoperatively in the functional outcomes of the patients [Table/Fig-6]. When the correlation of kyphosis angle correction at one year follow-up was evaluated with SF 12 score at one year, then there was a significant correlation with p-value <0.01. Thus, there was improvement in quality of life of the patients with better correction obtained following surgery. [Table/Fig-6]: SF12 scores comparison (pre-op and post-op follow ups). Frankel s grading was used to assess postoperative neurological status. One patient had transient paraparesis which improved later without any active intervention. One patient had rod breakage at six months which was later revised with an additional rod and domino connectors. This patient recovered well after post revision surgery and showed good fusion and maintenance of correction at one year follow up. No patient had Post-operative wound healing problem and there was minimum surgical scar seen at subsequent follow-ups. CASE 1 The patient is 16 years old boy with severe kyphotic deformity. X-ray shows hemivertebra at D-12 with Cobb angle of 90 degrees [Table/Fig-7]. He underwent single stage procedure of D12 hemivertebra resection via posterior approach. His ultimate sagittal plane deformity correction was by 65 degrees with postoperative Cobb s angle of 25 degrees [Table/Fig-8]. [Table/Fig-4]: Comparison between pre-operative and post-operative kyphosis angle. CASE 2 A 16-year-old boy with apex at D9, D10 with angular kyphosis [Table/ Fig-9,10] operated with VCR with anterior cage reconstruction and fixation with pedicle screws from D5 L1 [Table/Fig-11]. Journal of Clinical and Diagnostic Research Sep, Vol-10(9): RC17-RC22 19

4 7 8 DISCUSSION This study was designed to answer some very basic questions which a spine surgeon comes across when he confronts a case of congenital kyphosis with or without scoliosis in their clinic. They are A) How should these cases be managed? B) What technique should be used for correcting the deformity? [Table/Fig-7]: Pre-operative X-ray and CT scan Apex at D12. [Table/Fig-8]: Post-op X-ray VCR and fixation from D9 TO L4. C) Is it worth taking the risk to correct severe rigid kyphotic deformities? D) How much will the surgery benefit the patients and improve their Quality of Life?(HRQL) Congenital sharp, angular and rigid kyphotic deformities are progressive and conservative treatment often fails. Patient with severe curves are prone to neurological deficits because of the internal bony compression particularly at the thoracic region where the canal is narrow and cord sensitive [2]. Many of these patients land up in neurological deficits including paraplegia, low back pain and significant cosmetic deformity [3]. These patients suffer from low self-esteem because the deformity is associated with social stigmata. Hence, these are often treated surgically with deformity correction and removal of the internal compressive pathology. [Table/Fig-9]: Preoperative clinical photo. Most surgeons are familiar with the posterior spinal approach and hence in this study a single stage posterior approach based vertebral column resection with anterior reconstruction using a titanium mesh cage and posterior fusion with pedicle screw instrumentation and bone graft was done. It is now well known that if a small amount of correction is required then Smith Peterson osteotomy suffices which could be done at multiple levels to obtain desired correction of kyphotic deformity. If moderate correction is required and the vertebra is large enough, then removal of the pedicle via transpedicular approach and opening closing wedge osteotomy i.e., Pedicle Subtraction Osteotomy (PSO) is sufficient. In cases of severe rigid deformity with a small vertebra at the apex removal of entire vertebra by vertebral column resection is the surgical procedure of choice [11]. The aims of surgery are correction of deformity, decompression of cord at the apex of deformity, restore sagittal balance, provide immediate stability for early mobilization and maintaining the correction by obtaining good solid fusion. [Table/Fig-10]: Preoperative X-ray AP and Lateral view Apex at D9-D10. Vertebral column resection surgeries are technically demanding and problems are expected even with utmost care in experienced hands. The main risk is of buckling of the cord and the associated risk of neuro deficit which is taken care of in VCR by using a cage as a pivot which prevents shortening of the middle column and doing a gradual closing of the osteotomy [12,13]. Neuro monitoring can be helpful at this step but we were not able to use it due to lack of its local availability and financial constraints. However, we support its use intraoperatively and believe that neuro monitoring makes surgeons life much easy particularly while closing the osteotomy [14-16]. Other problem envisaged is of large amount of bleeding during this surgery which could be bony as well as from the epidural veins. Though measures like good normotensive anaesthesia, use of tranexamic acid, local saline plus adrenaline infusion into paraspinal musculature are some of the measures used commonly, it is only good surgical technique which helps minimize bleeding. Hence, the senior author who was the operating surgeon used a modification of technique routinely used to do VCR s. [Table/Fig-11]: Postoperative X-ray AP and Lateral views. 20 The modified technique is actually a combination of traditional egg shell de-cancellation of vertebral body and vertebral column resection. In this technique after doing adequate exposure of planned levels the apex of the deformity is approached via a transpedicular approach. Decancellation of the body is carried out by using high speed burs initially and then the hallow is expanded Journal of Clinical and Diagnostic Research Sep, Vol-10(9): RC17-RC22

5 keeping the medial wall of pedicle intact to protect the nerve roots. The decancellation is continued till only a thin shell of bone is left intact but the anterior, posterior and lateral walls are all intact till this stage which is different from conventional VCR in which they are sacrificed early. Now the resection is done to roughen superior and inferior endplates along with removal of the intervertebral discs. Similar steps are repeated from the other side of pedicle. Then resection is started from the lateral elements, the walls of the body are broken, a cage filled with bone graft is inserted and lamina and spinous process are removed. These steps reduce the amount of intraoperative bleeding by minimal handling of the epidural venous region and also are safe as it protects the cord by keeping the posterior elements intact till the last step. Bone to bone contact should be aimed after closing the osteotomy and if the gap is large then it should be filled with additional bone grafts this will help reduce the rate of pseudoarthrosis as well reduce the stress on implants. This technique was similar to that described by Wang et al., and they labelled it as Modified Vertebral Column Resection (MVCR) [17]. To our knowledge this is the only prospective study in which efficacy of this Modified technique of doing VCR was analysed. The average kyphosis correction in our study was by 59±9.3(45-78) degrees which is comparable and even better to correction of 52.1 degrees obtained by Wang et al., 2 out of 10 patients (20%) had a complication, the average blood loss in our study was 650 ml and operating time was 260 minutes which was comparable to other studies [17-21]. The pain scores showed significant improvement postoperatively as compared to pre-op scores. This finding is similar to other studies published recently [22,23]. In VCR either a combined anterior posterior or only posterior approach is used. Posterior only approach has been associated with less complication as compared to combined approach. We have performed VCR and fusion using posterior only approach to get better correction with a much safer approach. Posterior VCR gives three column corrections, better cosmesis and avoids the morbidity associated with anterior surgery. However, posterior only surgery is technically demanding, involves cord handling while doing the resection as well as closing the osteotomy which can have deleterious effects especially in the thoracic region where there is a watershed area of blood supply to the cord making it prone for cord ischemia. Another disadvantage of posterior only surgery is inadequate visualization of the anterior column and incomplete removal of the apical vertebra [24,25]. Kyphosis which is rigid and severe affects the patient wellbeing by compromising the respiratory functions as the volume of the chest cavity is decreased. This may also affect their cardiac functions, forward gaze is affected as the sagittal balance is impaired and bowel problems are common due to increased pressure on the abdomen. Not only are the clinical problems pertinent to these patients but kyphosis affects their quality of life significantly. This study prospectively evaluated the health related quality of life of patients with congenital kyphosis by assessing them with SF-12 questionnaire [26]. The PCS component which included 8 items were asked to patients/their parents at preoperative evaluation and at 1 year follow-up. There was a significant improvement in the SF- 12 PCS score to at 1 year postoperatively as compared to before surgery. Ayvaz et al., reported significant improvement in SRS-22 questionnaire post-surgery which also talks about quality of life of patients [27]. Bridwell et al., reported in their study that none of the patients with spinal deformities would like to live their life as it is [12]. Thus surgery definitely improved the quality of life of patient not only in terms of ability to perform daily functions, relief from back pain, general health but also emotionally and psychological thereby enabling them to lead a more mainstream social and productive life. This is amongst the very few studies published which have evaluated prospectively the improvement in quality of life in patients operated for congenital kyphosis. Proper counselling regarding prognosis, timely intervention, awareness of anatomy, caution in dissection, diligent and skilful surgery and good collaborated team work are the key stones for successful outcomes in congenital kyphosis corrective surgeries. Though surgery desires cosmetic correction, over corrections should be avoided because sound fusion and maintenance of correction enough to get a good sagittal balance is all that is required. A small sample size, lack of long term follow-up to assess for loss of correction or implant failure, inclusion of deformities with apex at both thoracic as well as thoraco-lumbar region which may affect the average corrections obtained differently, assessment of quality of life by SF-12 PCS score which has questionnaire not relevant to some patients at their age, are the short comings of this study. A multi-centric study with larger number of patients with similar aetiology and clinical pictures treated by using the Modified Vertebral Column Resection Technique (MVCR) will help conclusively establish the efficacy of this technique. Also we realized that a more relevant questionnaire for this age group should be developed to assess their quality of life. CONCLUSION High degree rigid congenital kyphotic deformities demand early surgery. Single stage posterior only vertebral column resection is a safe and effective method to correct these deformities. Modified Vertebral Column Resection (MVCR) is advantageous to surgeon and helps minimize the complications. Surgery helps to improve the health related quality of life of the patients. ACKNOWLEDGEMENTS The authors would like to acknowledge the help of research department of the institute where the study was conducted for statistical analysis of the data. References [1] Roussouly P, Nnadi C. Sagittal plane deformity: an overview of interpretation and management. European Spine Journal. 2010;19(11): [2] Marks DS, Qaimkhani SA. The natural history of congenital scoliosis and kyphosis. Spine. 2009;34(17): [3] McMaster MJ, Singh H. Natural history of congenital kyphosis and kyphoscoliosis. A study of one hundred and twelve patients. J Bone Joint Surg Am. 1999;81(10): [4] Tsou PM. 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