tethered cord syndrome ( tcs ) is caused by abnormal traction of the spinal cord by several pathological conditions . adult tcs presents with two types of symptoms : de novo symptoms and recurrent symptoms after untethering in childhood . however , untethering surgery was reported to have a high rate of complications such as cerebrospinal fluid leakage and neurological deterioration . moreover , patients with recurrent symptoms lasting longer than 5 years exhibited less frequent neurological improvements than patients with recurrent symptoms lasting less than 5 years after untethering . therefore , spine - shortening osteotomy ( sso ) has recently been performed for patients with adult tcs , particularly in patients with symptoms that have recurred for more than 5 years . excellent clinical and radiological outcomes after sso have been reported previously ; however , we experienced the rare complication of the fracture of the grafted vertebra after implant removal . some surgeons advocate implant removal because of the perceived risks associated with retained implants , including stress shielding , the risk of late infection , allergy , toxicity , titanium deposition , and carcinogenic potential . in contrast , other surgeons do not advocate this surgery because of postoperative complications and consideration to cost effectiveness . the complications following spinal implant removal surgery have been rarely reported , and the risks associated with this procedure are unclear . to the best of our knowledge , a fracture of the grafted vertebra has not been reported previously . we report this case to demonstrate the risk of postoperative fracture after spinal implant removal . a 27-year - old female with a progressive history of lower back pain , gait disturbance , and delayed urination presented to our institution . she had a past history of spinal surgery for spina bifida with lipoma ( conducted 20 days after birth ) . the lipoma was reduced surgically at that time , and her skin was closed ; however , equinus foot and enuresis appeared later in her childhood the symptoms of lower back pain , gait disturbance , and urinary incontinence became severe after the age of 20 years , therefore , she was referred to our hospital . a physical examination revealed bilateral hyperreflexia of the patellar tendon , hypreflexia of the left ankle , and motor weakness in the left lower extremity ( manual muscle testing scores : iliopsoas , 3 ; hamstring , 3 ; quadriceps , 4 ; tibialis anterior , 2 ; gustro - cutaneous , 2 ) . magnetic resonance imaging of the patient s spine revealed tethering of the spinal cord to a lipoma - like abnormal tissue in the lumbar spine with high signal intensities on t1- and t2-weighted images ( figure 1a ) . ( a ) preoperative t1-weighted sagittal magnetic resonance image ; the black arrow shows tethering of the spinal cord . ( b ) lateral plain radiograph image on the initial visit to our hospital . the patient was diagnosed with adult tcs . we decided to perform vertebral osteotomy and spine - shortening surgery at the l1 vertebra level ( figure 1b ) . the laminae and transverse processes of the t12l2 vertebrae were exposed , and pedicle screws were placed bilaterally at the t11 and l3 vertebrae . then , temporary rods were fixed in place for column stability while we performed the osteotomy . the lower half of the t12 lamina , the bilateral lower articular processes at t12 , and bilateral l1 superior articular processes were resected , and the bilateral l1 pedicles and bilateral transverse processes were then removed . a t12l1 discectomy and l1 upper one - third vertebral body resection were performed thereafter . next , the t12 and l2 vertebrae were compressed gradually using a pedicle screw - rod construct with somatosensory and motor - evoked potential monitoring ; an 18-mm shortening was accomplished using this method . a posterior arthrodesis ( t11l3 ) subsequently , the anterior procedure was performed using the retroperitoneal or extrapleural approach in the right decubitus position . the lateral and anterior aspects of the l1 vertebral body were exposed , and the remaining l1 vertebral body was resected completely after the removal of the discs above and below . finally , anterior interbody fusion was performed after anterior decompression using a left iliac crest graft ( figure 1c ) . ( c ) a postoperative lateral plain radiograph at the initial spinal - shortening surgery . ( d ) a computed tomography sagittal reconstruction image when the grafted vertebral fracture ( arrow ) was found . after the surgery , the patient s low back pain subsided , and her proximal lower leg muscle weakness improved 6 months after surgery ( manual muscle testing scores : iliopsoas , 4 ; hamstring , 4 ; quadriceps , 5 ) . the achievement of bony fusion in both the anterior and posterior parts of the spine was confirmed using reconstruction computed tomography imaging 1 year after the surgery . we made the decision to remove the implant 2 years after the surgery after we explained the advantages and disadvantages of the procedure to the patient . however , 10 days after the implant removal surgery , the patient complained of severe lower back pain without any trigger such as trauma . reconstruction computed tomography images revealed a fracture of the grafted vertebral body ( figure 1d ) . this second posterior fixation relieved the patient s lower back pain , and fusion of the grafted vertebral body was observed 6 months after this surgery . the patient has not experienced any additional complications in the 5 years following the second surgery ( figure 1e ) . sss is an alternative technique for untethering surgery used to treat adult tcs , and excellent clinical outcomes have been reported . numerous studies have reported the potential complications associated with implants after orthopedic surgery , including stress shielding , the risk of late infection , allergy , toxicity , titanium deposition , and carcinogenic potential . overall , it is a common procedure , particularly in pediatric orthopedics ; it accounts for approximately 5% of all orthopedic procedures in the united states , and in one report , 81% of patients underwent implant removal after fracture healing in finland . in the field of spinal surgery , several orthopedic surgeons performed implant removal despite the lack of sufficient evidence regarding its safety and efficacy . in contrast , other surgeons doubted the benefit of implant removal because of postoperative complications and the cost of the procedure . as a result reported one case of potential large vessel injury during the removal of a broken pedicle screw . reported vertebral compression fractures of the instrumented vertebral body adjacent to the fractured vertebra due to removal of pedicle screws . however , there have been no previous reports of the fracture of the grafted vertebra after implant removal .   in the present case , we performed implant removal surgery after sso in accordance with the patient s insistence and in consideration of the benefits mentioned above . however , fracture of the grafted vertebra was observed soon after the surgery . when the sso was performed , osteotomy at the level of the l1 vertebra was selected because of the smaller spinal body size in this region , the easier approach secondary to the straight spinal alignment around the thoracolumbar area , and the lower risk of diminishing the lumbar range of motion compared with other lumbar levels . there have been no reports on spinal stability after posterior elements were removed from the thoracolumbar junction . however , it can be considered that there is insufficient stability for the bending or torsion of the spine in the absence of posterior spinal elements at this junction , which was the cause of the fracture of the grafted vertebra observed in the present case . surprisingly , in previous reports of postoperative fractures after implant removal , the fractured vertebrae were all in the thoracolumbar junction ( l1 in two cases and t12 in one case ) ; therefore , the thoracolumbar junction might have a higher risk of fracture after implant removal . because the necessity for implant removal surgery is controversial , we recommend that spinal implants not be removed , particularly in cases of sso or osteotomy surgery on a spinal posterior element such as total en - block spondylectomy . it is crucial to understand the inherent risks as well as to know the expected benefits of this procedure . further long - term and large - scale studies are needed to elucidate whether spinal implant removal surgery is necessary .
abstractwe experienced the rare complication of a vertebral fracture that was caused by implant removal after bony fusion had been achieved in a patient who underwent spine - shortening osteotomy ( sso ) for tethered cord syndrome ( tcs ) . 
 we propose that the removal of the implant used for sso should be contraindicated . 
 the patient ( a 27-year - old female ) presented to our institution with a history of progressive severe lower back pain , gait disturbance , and urinary incontinence . 
 as an infant , she had undergone surgery for spina bifida with lipoma . 
 magnetic resonance imaging of the spine revealed tethering of the spinal cord to a lipoma . 
 we performed sso at the level of the l1 vertebra level . 
 after spine shortening and fixation using a posterior approach , the l1 vertebral body was completely removed anteriorly and replaced with a left iliac bone graft . 
 the patient s symptoms improved after surgery . after bony fusion was achieved after surgery , we decided to remove the spinal implant after we explained the advantages and disadvantages of the procedure to the patient . 
 we performed implant removal surgery safely 2 years later ; however , the patient complained of severe lower back pain 10 days after the surgery without any history of trauma . 
 reconstruction computed tomography showed fracture of the grafted vertebra . 
 we performed a repeat posterior fixation , which relieved the lower back pain ; she has experienced no complications in the subsequent 5 years . in summary 
 , we report a case of a rare complication of the fracture of a grafted vertebra after removal of an implant used in sso for tcs . spinal stability 
 could not be maintained without the spinal posterior implant after sso . 
 postoperative fracture after spinal implant removal is rare but possible , and patients must be informed of this potential risk .