Safety And Efficacy Of Spine-shortening Osteotomy For Congenital Scoliosis Associated With Tethered Cord

BackgroundTethered spinal cord is an abnormal attachment of the spinal cord to the tissues thatsurround it. The ascent of the spinal cord is limited and is disproportionate to the growthof the spinal column. The attachment limits the movement of spinal cord, and put tractionon it in progress. This traction on the spinal cord leads to decreased blood flow andoxidative metabolism, which may result in the clinical symptoms and signs of the tetheredcord syndrome（TCS）. In the end, stretching of the conus medullaris and nerve root mayinduce neurological condition such as back pain, foot deformity, scoliosis, sensory loss,and/or bowel or bladder dysfunction. It seems reasonable to recommend early surgicaltreatment for children with tethered cord, whether symptomatic or otherwise to prevent new or additional neurological deficits. In spite of the procedure employed, the point ofsurgery is to free all spinal cord and neural elements from tension to restore neurologicalfunction and prevent further deterioration.As many as13%-29%cases of congenital scoliosis maybe associated with tetheredcord. Scoliosis associated with a tethered cord is one of the most challenging spinaldeformities to manage. A tethered spinal cord may increase the chance of neurologicalinjury when undergoing surgical correction of scoliosis. Because simply correctingscoliosis may lead to excessive traction on a tethered spinal cord in theory. Many authorsrecommended conventional procedure in such patients. The approach is first to performuntethering for the tethered cord and then surgery for correction and stabilization ofdeformity3to6months later. Unfortunately, this procedure will subject the patient to therisk of a second anesthesia, the inconvenience of a second hospital stay, and an increasedtime to full recovery. On the other hand, some authors found that simultaneous surgerywas a safe alternative to staged surgeries. But both of the two procedures do not obviatethe procedure of detethering, which is associated with increased perioperative risks,including CSF leak, pseudomeningocele, neurological injury, wound complications, andspinal cord retethering.As an alternative to conventional untethering procedure, since1995, Kokubun haveperformed spine-shortening osteotomy in patients with TCS because it is believed toreduce the tension in the spinal cord indirectly. It was the first report of an entirelyextradural procedure for TCS treatment. Meanwhile, the osteotomy procedure was widelyused for deformity correction, especially for the treatment of congenital scoliosis.Theoretically, spine-shortening osteotomy can be used for patients with scoliosisassociated with tethered cord. However, to the best of our knowledge, there is no study onlarge clinical series of this kind. In the current study, we have retrospectively analyzed21consecutive patients who underwent spine-shortening osteotomy for congenital scoliosisassociated with tethered cord.Part I.：Safety and Efficacy of Vertebral Column Resection for Severe CongenitalScoliosis associated with Tethered Cord 1. MethodsThirteen patients (7females and6males, average age15.8years) were performedvertebral column resection to correct scoliosis deformity and decrease the tension of spinalcord simultaneously without extra untethering procedure. All of the patients had tetheredcord at the level of L4or below. Nine of them were associated with kyphosis. Vertebralcolumn resection was performed apical vertebral. All of the patients had VCR procedure.Data collection and analysis: The operation time, blood loss, postoperativecomplications, and the hospitalization time were noted and recorded. Patients’ data wascollected at pre-and postoperation, and3months,6months,12months,24months, andlast follow-up. The length of the spine-shortening was measured when the osteotomyprocedure was complete. The curves of scoliosis and kyphosis were measuredpreoperatively, soon after surgery, and at the final follow-up appointment. The angle wasmeasured using Cobb method. The neural condition was recorded when it changed. Weclassified neural changes as recovered function, improved function and residual deficits.Clinical outcomes were assessed using the JOA score and the Scoliosis ResearchSociety (SRS)-22questionnaires.2. ResultsMean operation time was619.6±80.9min with average blood lossof3061.5±1367.8ml. The deformity correction was59.0%±7%in the coronal plane and51.5°in the sagittal plane. Eleven patients had neurological deficit before surgery, thedeficits in10patients’ were cured or improved, while1of them stayed unchanged. At thefinal follow-up appointment, the result indicates a d a75%improvement in sensorydisturbance following vertebral column resection. Three patients with motor disturbancesand5patients with pain were all improved at the final follow-up. The urinary dysfunctionin1patient recovered at the final follow-up. Three patients got complications includingurinary tract infection in1patients, cerebrospinal fluid leakage in1patient and bloodloss>5000ml in1patient.3. ConclusionVertebral column resection is an excellent surgical procedure that helps to correct spine deformity and reduce spinal cord tension without causing direct neural damage. Inour research, this operation procedure does not involve significant complications andseems to be an attractive and safe treatment option. However, it should be kept in mindthat this is a technically demanding and exhausting procedure with possible risks for majorcomplications. More researches are needed on the indication and possibility ofcomplication. The vertebral column resection is a safe and effective alternative toconventional procedure for congenital scoliosis associated with tethered cord. It canachieve the goal of correction of the spine deformity without additional untetheringprocedure and the goal of releasing tethered cord to get the improvement of neurologicaldeficit simultaneously.Part II：Safety and Efficacy of Pedicle Subtraction Osteotomy for Mild-to-moderateCongenital Scoliosis associated with Tethered Cord1. MethodsEight patients (7females and1males, average age14.8years) were performedpedicle subtraction osteotomy to correct scoliosis deformity and decrease the tension ofspinal cord simultaneously without extra untethering procedure. All of the patients hadtethered cord at the level of L4or below. Five of them were associated with kyphosis.pedicle subtraction osteotomy was performed apical vertebral. All of the patients had PSOprocedure. Data collection and analysis: The operation time, blood loss, postoperativecomplications, and the hospitalization time were noted and recorded. Patients’ data wascollected at pre-and postoperation, and3months,6months,12months,24months, andlast follow-up. The curves of scoliosis and kyphosis were measured preoperatively, soonafter surgery, and at the final follow-up appointment. The angle was measured using Cobbmethod. The neural condition was recorded when it changed. We classified neural changesas recovered function, improved function and residual deficits.Clinical outcomes were assessed using the JOA score and the Scoliosis ResearchSociety (SRS)-22questionnaires.2. Results Mean operation time was449.4±73.1min min with average blood loss of2293.8±1060.5ml mL. The deformity correction was65.8±9.7%in the coronal plane and32.4°in the sagittal plane. At the final follow-up appointment, the deficits in7patients’were cured or improved, while1of them stayed unchanged. At the final follow-upappointment, the result indicates an83.3%improvement in motor disturbances. The painin three patients and sensory disturbance in one patient were all relieved. Two patient whohad bowel or urinary dysfunction all recovered. Two patients got complications includingtemporary neurological deterioration in1patient, who recovered at3monthspostoperatively; urinary tract infection in1patient.3. ConclusionPedicle subtraction osteotomy is an excellent surgical procedure that helps to correctspine deformity and reduce spinal cord tension without causing direct neural damage. Inour research, this operation procedure does not involve significant complications andseems to be an attractive and safe treatment option. The pedicle subtraction osteotomy is asafe and effective alternative to conventional procedure for congenital scoliosis associatedwith tethered cord. It can achieve the goal of correction of the spine deformity withoutadditional untethering procedure and the goal of releasing tethered cord to get theimprovement of neurological deficit simultaneously.