Surgical management of herniated intervertebral disc in children: Running title: Pediatric disc herniation.

STUDY DESIGN: Retrospective literature review analysis OBJECTIVE: Analyze the risk factors, characteristics, outcome, and follow up of surgical management of disc herniation in children ≤15 years old (y.o) through a review of the literature. BACKGROUND: Disc herniation is a rare disease in the pediatric population. While conservative treatment if very often tried, some cases require surgical treatment. METHODS: A literature search was conducted using PubMed data base using the terms 'pediatric/children/adolescent disc herniation' and 'surgical management' as key words. Significant manuscripts i.e: case reports, case series, reviews were identified and analyzed. The exclusion criteria were: series and cases with patients >15 y.o, results non-individualizable and medical management. RESULTS: 49 studies were identified, 28 were retained. 69 children <15 y.o were identified with a median age of 13 y.o (SD 1-15). The mean FU was 3.3 years. Trauma and repeated micro traumatism were identified as the main causes of disc herniation in this population. It is mostly a lumbar disease, with very anecdotic cases of thoracic or cervical herniation described. In the absence of neurological deficit, conservative treatment should be tried. Different types of surgery exist (open, endoscopic, tubular), with no difference in outcome or complications. The post-operative outcome was very satisfactory, with no neurological sequalae described with excellent recovery. CONCLUSIONS: Pediatric disc herniation is often caused by precipitating factors such as trauma. In the absence of resolution with conservative treatment, surgical options yield favorable short term clinical outcomes with minimal complications and no neurological sequalae.

Efficacy of the pridie drilling technique in knee osteochondritis dissecans among children and young adults: follow-up of 41 cases.

PURPOSE: This study aims to examine whether Pridie drilling, a form of bone marrow stimulation, can expedite the healing process and enable a faster return to sports activity in patients with knee Osteochondritis dissecans (OCD). The primary objective is to assess the effectiveness of Pridie drilling in stable OCD lesions that do not respond to non-operative treatment, by evaluating the absence of painful symptoms 6 months after the procedure. Secondary objectives include evaluating radiographic reconstruction 6 months post-surgery and determining the time it takes to resume sports participation. MATERIALS AND METHODS: This single-center retrospective study included all cases of stable OCD in the knee that underwent anterograde chondral drilling between 2008 and 2020. Diagnosis of OCD was established using knee radiographs, and the surgical technique involved multiple multidirectional subchondral drilling. Treatment efficacy was defined by the absence of painful symptoms for 6 months postoperatively. RESULTS: A total of 41 knees were included in the study, and no complications were observed before or after surgery. At 6 months postoperatively, 32 knees (78%) showed complete resolution of symptoms. Complete radiographic reconstruction was observed in 66% of cases. Asymptomatic patients at 6 months returned to sports activity of similar intensity to that practiced previously in an average time of 7.9 months; while, patients who were symptomatic at 6 months returned in an average time of 16.5 months. CONCLUSION: This study provides evidence supporting the short-term efficacy of anterograde chondral drilling in stable lesion of OCD in children and adolescents after failed functional treatment. LEVEL OF EVIDENCE: Level III (retrospective cohort study).

Influence of the thoracolumbar junction flexibility on the risk of adding-on after posterior vertebral arthrodesis for thoracic idiopathic adolescent scoliosis.

PURPOSE: The objective was to analyze the role of the thoracolumbar sagittal flexibility on the outcome after posterior spinal fusion of Lenke 1 and 2 adolescent idiopathic scoliosis with last touched vertebra as the lowest instrumented vertebra. METHODS: We included 105 thoracic AIS patients who had a posterior spinal fusion with a 2 years minimum follow-up. Thoracolumbar junction flexibility was assessed on dynamic sagittal X-rays and compared to the standing position. Adding-on was defined according to radiographic Wang criteria. The junction was considered flexible if the variability from the static position to flexion and/or extension was greater than 10°. RESULTS: Mean age of the patients was 14 ± 2 years. The preoperative mean Cobb angle was 61 ± 12.7° and 27.5 ± 7.7° after surgery. Mean follow-up was 3.1 years. Twenty-nine patients (28%) developed an adding-on. Thoracolumbar junction range of motion was higher (p = 0.017) with higher flexibility in flexion (p < 0.001) in the no adding-on group. In no adding-on group, 53 patients (70%) had a flexible thoracolumbar junction, and 23 patients (30%) had a stiff thoracolumbar junction in flexion and flexible in extension. In adding-on group, 27 patients (93%) had a stiff thoracolumbar junction, and 2 patients (7%) had a flexible junction in flexion and stiff in extension. CONCLUSION: The flexibility of the thoracolumbar junction is a determining factor in the surgical outcome after posterior spinal fusion for AIS and should be considered in correlation with the frontal and sagittal alignment of the spine.

Outcomes of 53 thoracic outlet syndrome cases with confirmed neurological deficit.

INTRODUCTION: Neurogenic thoracic outlet syndromes (TOS) are dominated by the nonspecific forms. This study focuses only on the rarer true forms related to proximal nerve compression in the thoracic outlet, with the presence of motor (atrophy of the hand's intrinsic muscles) and/or sensory (hypoesthesia in the territory of the medial antebrachial cutaneous nerve) deficits. The objectives of this study were to define the clinical characteristics, anatomical causes and surgical results of this condition. PATIENTS AND METHODS: Single-center retrospective study of 53 consecutive cases in 50 patients with an objective clinical deficit confirmed by nerve conduction studies. The population consisted of 47 adults and 3 children, 9 males and 41 females, with a mean age of 39 years (9-80 years), diagnosed between July 1994 and December 2019. An objective motor deficit was present in 50 cases, with the remaining 3 having a sensory deficit only. Forty cases underwent surgery, most often via the supraclavicular approach, while 13 cases did not undergo surgery because their deficit was longstanding and non-progressive. RESULTS: One operated patient was lost in follow-up. An analysis of the medical records of 18 cases, including 15 operated cases found complete recovery in 4 cases, significant improvement in 9 cases and small improvement in 2 cases at a mean follow-up of 53 months (1-162 months). Thirty-four cases were reviewed in person, including 24 operated cases and evaluated with a mean follow-up of 135 months (36-284 months): the pain had disappeared in 21 cases, thenar atrophy persisted in 17 cases, which was associated with a claw-hand deformity in 3 cases, while 2 cases had an isolated claw-hand deformity. The patients were very satisfied with the procedure in 15 cases and satisfied in 9 cases. They evaluated the benefit of surgery at 87% and their upper limb function increased from 38% (10-60%) preoperatively to 77% (60-100%) at the review. CONCLUSION: Few studies in the literature have focused on true neurogenic TOS cases. The treatment is surgical in progressive cases; an anatomical anomaly is always present. Surgical treatment eliminates the pain and helps to stabilize or even partially resolve the deficit. Despite a moderate objective gain, the patients' feeling of functional improvement is important with a high satisfaction rate. LEVEL OF EVIDENCE: IV, retrospective.

Surgical outcomes of spinal osteochondroma in children: A multicentre observational study.

BACKGROUND: Spinal osteochondroma (or exostosis) is a rare benign tumour whose clinical manifestations are delayed due to their slow growth and location. Few studies have addressed the characteristics and the diagnostic and therapeutic peculiarities of spinal osteochondroma in children. The objective of this multicentre observational study was to assess the outcomes of a cohort of children after surgery for spinal osteochondroma. HYPOTHESIS: Surgical excision of spinal osteochondroma in children is not followed by complications or recurrences. MATERIAL AND METHODS: We included consecutive children who had surgery between 2010 and 2018 at any of eight participating centres to remove spinal osteochondromas. The cause, clinical manifestations, and location of the lesions were collected. The surgical outcomes were evaluated after at least 2 years' follow-up. RESULTS: We identified 22 patients who had surgery to remove 26 spinal osteochondromas at a mean age of 12.8±2.6 years. Among them, 7 had a solitary osteochondroma (SO group) and 15 had hereditary multiple osteochondromas (HMO group). At diagnosis, 72% of patients had clinical signs (spinal pain, n=4; one or more lumps, n=5; and neurological manifestations, n=3). In the HMO group, the diagnosis was made during routine MRI screening for tumours involving the spinal canal. Most osteochondromas involved the cervical spine (n=13), with no difference between the two groups (p=0.9). The lamina was the most common location but 54% of the tumours were growing within the canal (92% in the HMO group). After a mean follow-up of 5.2±4.4 years, no patients had experienced any recurrences or complications related to the disease or treatment. DISCUSSION: Surgical excision of spinal osteochondromas in children is effective, with no medium-term recurrences. Our results also confirm the low peri-operative morbidity, even when the canal is involved, and the absence of any effect at last follow-up on spinal alignment. All patients with neurological manifestations at diagnosis made a full recovery. LEVEL OF EVIDENCE: IV, retrospective observational cohort study.

High-grade L5-S1 spondylolisthesis with lumbosacral kyphosis: Long-term results of non-instrumented circumferential arthrodesis in children, adolescents.

INTRODUCTION: The choice of surgical technique for high-grade spondylolisthesis (HGS) associated with lumbosacral kyphosis remains controversial. Are non-instrumented techniques still relevant, what with the multiplicity and modernity of patient-specific instrumentation? HYPOTHESIS: Our hypothesis was that a non-instrumented circumferential arthrodesis performed after a period of gradual reduction of HGS, associated with lumbosacral kyphosis, provided satisfactory long-term functional and radiographic results in children and adolescents while minimizing the risk of complications. MATERIALS AND METHODS: Thirty-one L5-S1 HGS associated with a lumbosacral kyphosis operated by non-instrumented circumferential arthrodesis after a period of traction and suspension were included in our study. The first stage of this technique consisted of a gradual reduction using traction followed by immobilization in the corrected position. The second stage involved a posterior, followed by an anterior, surgical procedure and a spica cast immobilization for 4 months. The mean age at surgery was 13.9±2.3 years (6-18) and the mean follow-up was 10.3±4.5 years (2.1-17.8). RESULTS: The overall complication rate was 26% (n=8/31): 13% neurologic complications, 10% bone fusion defects and 3% skin complications. The reoperation rate was 13% (n=4/31). The mean ODI (/50) was 3±4.6 (0-22) and the SRS-30 126.7±15 (72-143). The Taillard index decreased by 25% (p<.001) and remained stable throughout the follow-up period (p=.65). The lumbosacral angle was corrected by 13.5% (p=.03) and the correction was maintained throughout the follow-up period (p=.71). At the last follow-up, the lumbosacral angle was significantly correlated with a low ODI score and a high SRS-30 score (p<.05). CONCLUSION: Even though this technique achieved a smaller reduction of the lumbosacral angle, it reduced by at least a factor of three the incidence of neurologic complications and resulted in satisfactory functional outcomes when compared to instrumented and intraoperative correction series. LEVEL OF EVIDENCE: IV.

Residual acetabular dysplasia in congenital hip dysplasia.

Residual hip dysplasia may exist despite appropriate treatment of congenital hip dysplasia (CHD). The abnormalities chiefly affect the acetabulum and can lead to premature osteoarthritis. Although the main cause is delayed treatment of CHD, primary lesions are also possible and may be worsened by the initial treatment itself. Residual hip dysplasia must be detected during the follow-up of patients with CHD. The antero-posterior radiograph of the pelvis is the main diagnostic tool. However, the importance of non-ossified anatomical structures requires additional investigations such as arthrography and magnetic resonance imaging. The risk of premature osteoarthritis is difficult to predict based only on the imaging-study findings. Hip dysplasia is best treated before 5 years of age. The work-up at this age should allow determination of the best treatment. Surgery is required but should not be performed unnecessarily. The decision rests on the absence of improvement in the radiographic criteria and on the findings from additional imaging studies. The usual treatment is Salter's osteotomy, during which excessive anterior displacement should be avoided. At adolescence, the information provided by radiography in the coronal plane should be completed by a three-dimensional evaluation of the acetabulum and an assessment of the quality of the labrum. The shelf procedure has been proven to relieve pain and to significantly postpone the need for hip arthroplasty, when performed early, before the development of visible osteoarthritis, and on a congruent hip. Chiari's osteotomy has a role to play in complex dysplasia affecting both the acetabulum and the femur. Periacetabular osteotomy is getting more used thanks to cooperation between paediatric and adult orthopaedic surgeons. This osteotomy provides optimal correction in all three dimensions.

Petit-Morel method for hip development dysplasia in toddlers: A retrospective observational study in 34 patients.

BACKGROUND: The Petit-Morel method allows the treatment of developmental hip dysplasia in toddlers by combining gradual traction to achieve reduction followed by immobilisation during which pelvic osteotomy is performed. The objective of this study was to assess the radiographic and clinical outcomes in a retrospective cohort of patients. HYPOTHESIS: The Petit-Morel method is associated with low rates of avascular necrosis and residual acetabular dysplasia at skeletal maturity, as well as with satisfactory medium-term clinical outcomes. MATERIAL AND METHODS: We conducted a single-centre retrospective study of 34 patients (35 hips) treated between 1997 and 2014. The radiological assessment criteria included an evaluation for avascular necrosis classified according to Kalamchi and MacEwan, the vertical centre edge (VCE) angle, femoral head sphericity according to Mose, and acetabular dysplasia at skeletal maturity according to Severin. Hip function was assessed by determining the Postel-Merle d'Aubigné (PMA) score. RESULTS: Mean age at treatment was 19±4 months (range, 14-29). Mean follow-up was 11 years (range, 5-20). There were two failures including one case of recurrent dislocation requiring surgical reduction. Group II avascular necrosis occurred in 1 (3%) patient. Tönnis Grade IV dysplasia was significantly associated with resolving irregularity of the ossification centre, seen in 19 (54%) cases (p=0.002). In the 18 patients followed-up to skeletal maturity, with a mean follow-up of 15 years (range, 12-20 years), 17 hips were Severin Class I. The mean VCE angle was 29° (range, 15°-38°), and the head was spherical for 34 (98%) hips. The PMA score at last follow-up was excellent (17-18). The mean VCE angle was greater in all 5 patients who experienced pain during long walks (35° [range, 32°-37°]) than in the asymptomatic patients (28° [range, 15°-38°]) (p=0.009). DISCUSSION: The Petit-Morel method is a reliable treatment that provides good clinical and radiological outcomes. Overcorrection of the VCE angle was noted in the patients who experienced walking-related pain in adulthood. LEVEL OF EVIDENCE: IV, retrospective observational cohort study.

Epidemiology of spinal fractures in children: Cross-sectional study.

INTRODUCTION: Epidemiological studies of fractures of the spine in children are all old, mostly single-centre, with series spanning periods of 5 to 20 years. HYPOTHESIS: As lifestyle is constantly changing, notably with an increase in sports activities and improvements in the prevention of road and household accidents, epidemiology has likely changed. OBJECTIVE: To update the description of spinal trauma in children and adolescents compared to the existing literature. MATERIAL AND METHOD: A multicentre cross-sectional study of spinal fracture, dislocation and spinal cord injury without radiological abnormality (SCIWORA) in children was carried out in 15 French university hospital centres, for a period of one year (2016). RESULTS: One hundred and sixty-five children were identified: 85 girls, 80 boys; mean age 11 years (range, 10 months-17 years); median, 12 years 6 months. One hundred and fifty-two children (92%) had fracture, 8 (5%) dislocation (including 7 C1-C2 rotary dislocations), and 5 (3%) SCIWORA. Fractures were multiple in 80 cases (49%), contiguous in 73 cases (91%) and non-contiguous in 7 (9%). Locations were cervical in 25 cases (15%), thoracic in 85 (52%), lumbar in 75 and sacral in 4 (2%). Fracture types comprised 234 vertebral compactions (78%), 25 burst fractures (8%), 5 chance fractures (2%), 2 odontoid fractures, and 33 other lesions. Causes comprised fall in 77 cases (47%), sports accidents in 56 (34%), road accidents in 29 (18%), and others in 3. In 52 cases (32%), there was ≥1 associated lesion: appendicular in 35 cases (67%), thoracic or abdominal in 31 (60%), and head in 16 (31%). Twenty-one cases had multiple lesions (40%). Eighteen cases showed neurological involvement (11%) including 5 SCIWORAs. Neurological complications were more frequent before 9 years of age. CONCLUSION: The epidemiology of spine fractures in children has slightly changed. There are now fewer cervical lesions. Causes are less often road accidents and more often sports accidents. Multi-level lesions remain frequent and the rate of neurological complications is around 10%. Compaction fracture is the most common type.

Thrombotic risk in children undergoing orthopedic surgery.

Children are physiologically protected against venous thromboembolism (VTE). Specific triggering events or contributing factors have been identified in the majority of reported cases, which differs from the adult pathology where 50% of the thromboses are considered "idiopathic". This is a rare disease in children with an estimated frequency of less than 1/1000. The risk is highest in neonates, then decreases and increases again around 13 years to reach the same level as adults at 16 years. The risk of VTE is clearly higher in certain situations: significant trauma, prolonged immobilization, central venous catheter, stay in intensive care unit, inherited thrombophilia, cancer, obesity, oral contraceptives, etc. Thromboprophylaxis should not be used systematically, even in adolescents. Proper hydration and early mobilization form the basis of mechanical thromboprophylaxis. A prescription is only given after careful analysis of the child's risk factors and the orthopedic context. Thrombotic risk assessment scores - which are based on expert opinion and large VTE registers but have not been evaluated in clinical studies - are currently the most reliable method to evaluate the thrombotic risk in children and to prescribe thromboprophylaxis. Low-molecular weight heparin are the most commonly used thromboprophylaxis agents in children, with good tolerance and efficacy.

Multidisciplinary surgical strategy for dumbbell neuroblastoma: A single-center experience of 32 cases.

INTRODUCTION: Prognosis of dumbbell neuroblastoma (NBL) is mainly determined by the sequelae induced by the tumor itself and the neurosurgical approach. However, after primary chemotherapy, surgical management of the residual tumor, especially the spinal canal component, remains controversial. METHODS: We conducted a single-center retrospective cohort study over the last 15 years (2002-2017) including patients treated for NBL with spinal canal extension focusing on timing and type of surgery, complications, and functional and oncological follow-up. RESULTS: Thirty-two children (14 M, 18 F) were managed for NBL, with the majority (26) presenting with NBL stroma poor while four had ganglioneuroblastoma intermixed, one nodular, and one ganglioneuroma. All but two patients received neoadjuvant chemotherapy. Upfront laminotomy for spinal cord decompression was performed in two patients; nine patients had extraspinal surgery with a follow-up neurosurgical procedure in seven cases; eight patients had initial neurosurgery followed by an extraspinal procedure, while six patients underwent a combined multidisciplinary approach. With a median follow up of 3.6 years (0.1-14.9), 29 patients (90.6) are alive and two out of three (19, 65.5%) have functional sequelae. CONCLUSION: Patients with NBL with persistent spinal canal extension of the tumor after neoadjuvant chemotherapy treated at our center had outcomes that compare favorably with the literature. This is likely due to the multidisciplinary approach to optimal surgical strategy and continuous evaluation of the respective risks of tumor progression. Neurological disability results from initial spinal cord compression or the radicular sacrifice required for tumor resection.

Proximal junctional kyphosis in thoracic adolescent idiopathic scoliosis: risk factors and compensatory mechanisms in a multicenter national cohort.

INTRODUCTION: Proximal junctional kyphosis (PJK) is a frequent complication, up to 46%, in adolescent idiopathic scoliosis surgical treatment (AIS). Several risk factors have been evoked but remain controversial. The purpose of this study was to analyze the incidence of PJK in a multicenter cohort of AIS patient and to determine risk factor for PJK. MATERIALS AND METHODS: Lenke I and II AIS patients operated between 2011 and 2015 (minimum of 2-years follow-up) were included. On fullspine X-rays, coronal and sagittal radiographic parameters were measured preoperatively, postoperatively and at final follow-up. Occurrence of radiological PJK corresponding to a 10° increase in the sagittal Cobb angle, measured between the upper instrumented vertebra (UIV) and UIV + 2, between postoperative and 2-years follow-up X-rays, was reported. RESULTS: Among the 365 patients included, 15.6% (n = 57) developed a PJK and only 10 patients required a revision surgery. Preoperatively, PJK patients had significantly larger pelvic incidence (57° ± 13° vs. 51° ± 12°), larger lumbar lordosis (LL) (63° ± 12° vs. 57° ± 11°) and bigger C7 slope. Postoperatively (3 months), in the non-PJK group, thoracic kyphosis (TK) was increased and LL was not significantly different. However, postoperatively, in the PJK group, no significant change was observed in TK, whereas C7 slope decreased and LL significantly increased. There was also a postoperative change in inflection point which was located at a more proximal level in the PJK group. Between postoperative time and final follow-up, TK and LL significantly increased in the PJK group. CONCLUSION: PJK is a frequent complication in thoracic AIS, occurring 16%, but remains often asymptomatic (less than 3% of revisions in the entire cohort). An interesting finding is that patients with high pelvic incidence and consequently large LL and TK were more at risk of PJK. As demonstrated in ASD, one of the causes of PJK might be postoperative posterior imbalance that can be due to increased LL, insufficient TK or inflection point shift during surgery. These slides can be retrieved under Electronic Supplementary Material.

Outcomes of Spinal Fusion for Cervical Kyphosis in Children with Neurofibromatosis.

BACKGROUND: Cervical kyphosis may occur with neurofibromatosis type I (NF1) and is often associated with vertebral dysplasia. Outcomes of cervical spinal fusion in patients with NF1 are not well described because of the rarity of the condition. We aimed to (1) characterize the clinical presentation of cervical kyphosis and (2) report the outcomes of posterior and anteroposterior cervical fusion for the condition in these children. METHODS: The medical records and imaging studies of 22 children with NF1 who had undergone spinal fusion for cervical kyphosis (mean, 67°) at a mean age of 11 years and who had been followed for a minimum of 2 years were reviewed. RESULTS: Thirteen children presented with neck pain; 10, with head tilt; 9, with a previous cervical laminectomy or fusion; and 5, with a neurologic deficit. Two patients had spontaneous dislocation of the mid-cervical spine without a neurologic deficit. Eleven had scoliosis, with the major curve measuring a mean of 61°. Nine patients underwent posterior and 13 underwent anteroposterior surgery. Twenty-one received spinal instrumentation, and 1 was not treated with instrumentation. Preoperative halo traction was used for 9 patients, and it reduced the mean preoperative kyphosis by 34% (p = 0.0059). At the time of final follow-up, all spinal fusion sites had healed and the cervical kyphosis averaged 21° (mean correction, 69%; p < 0.001). The cervical kyphosis correction was significantly better after the anteroposterior procedures (83%) than after the posterior-only procedures (58%) (p = 0.031). Vertebral dysplasia and erosion continued in all 17 patients who had presented with dysplasia preoperatively. Thirteen patients had complications, including 5 new neurologic deficits and 8 cases of junctional kyphosis. Nine patients required revision surgery. Junctional kyphosis was more common in children in whom ≤5 levels had been fused (p = 0.054). CONCLUSIONS: Anteroposterior surgery provided better correction of cervical kyphosis than posterior spinal fusion in children with NF1. Erosion of vertebral bodies continued during the postoperative follow-up period in all patients who had presented with dysplastic changes preoperatively. The cervical spine should be screened in all children with NF1. Fusion should include at least 6 levels to prevent junctional kyphosis. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Rigid fixation improves outcomes of spinal fusion for C1-C2 instability in children with skeletal dysplasias.

BACKGROUND: Upper cervical instability is common in many skeletal dysplasias, and surgical treatment can be difficult because of small, fragile osseous elements. In this study of children with skeletal dysplasia and upper cervical instability, we compared fusion rates and complications between (1) patients treated with no instrumentation or with wiring techniques and (2) those who underwent rigid cervical spine instrumentation. We also sought to characterize the presentation and common parameters of upper cervical instability in this population. METHODS: A multicenter study identified twenty-eight children with skeletal dysplasia who underwent surgery from 2000 through 2011 for C1-C2 instability and were followed for a minimum of two years. Fourteen children were treated with no instrumentation or with instrumentation with wires or cables (nonrigid-fixation group) and fourteen were treated with screws (or hooks) and rods (rigid-fixation group). All patients received autograft, and twenty (twelve in the nonrigid group and eight in the rigid group) were treated with a halo-body jacket. RESULTS: Fourteen children had C1-C2 fusion, and fourteen had occipitocervical fusion. Eleven (39%) underwent spinal cord decompression. The nonunion rate was significantly higher in the nonrigid-fixation group (six of fourteen) than in the rigid-fixation group (zero of fourteen; p = 0.0057). Complications, including nonunion, occurred in nine patients in the nonrigid group and one patient in the rigid group. However, two of the complications in the nonrigid-fixation group were vertebral artery bleeding episodes that actually occurred during an attempt at rigid fixation (the fixation was subsequently done with wiring). No new neurologic deficits were observed. Five of the seven children with a preoperative neurologic deficit showed at least partial recovery, with significant improvement in the Japanese Orthopaedic Association upper-extremity score (p = 0.047). CONCLUSIONS: The nonunion rate is relatively high after patients undergo spinal fusion for C1-C2 instability with nonrigid instrumentation, even if a halo-body jacket is applied. Rigid fixation with screws and rods improves fusion rates.

Internal fixation with occipital hooks construct for occipito-cervical arthrodesis. Results in 14 young or small children.

PURPOSE: Evaluation of effectiveness of internal rigid fixation for occipito-cervical fusion with occipital hooks and cervical screws and/or hooks to improve fusion in young or small children with various bone dysplasia or congenital abnormality. METHODS: Fourteen children with mean age of 8.4 years and height and weight below 140 cm and 35 kg, respectively, who underwent occipito-cervical fusion for miscellaneous pathologies reading to stenosis and/or instability were reviewed. The posterior instrumentation consisted of a precontoured titanium plate rod with an occipital fixation by hooks and a vertebral fixation by screws and/or hooks. Eight patients had cervical fixation with C2 pedicle screws. The mean follow-up was 48 months (27-81 months). RESULTS: Thirteen patients (92.8 %) had a complete fusion and no failure of the fixation was observed. We had two deep wound infections not related to implants. CONCLUSION: Instrumentation was technically feasible even in a very young child. Rigid internal fixation in the little children did not increase surgical complications and significantly increased the union rate of occipito-cervical arthrodesis.

Ischiovertebral dysplasia: a retrospective analysis of 30 consecutive cases pointing out the specifics and risks of the spine management.

STUDY DESIGN: A review of clinical publications, current knowledge, and recent developments regarding the etiology of ischiovertebral dysplasia was combined with a clinical review of the condition. OBJECTIVE: To acquaint orthopedic spine surgeons with identification patterns of ischiovertebral dysplasia in order to provide them with guidelines about spine management and which complications to expect. SUMMARY OF BACKGROUND DATA: Ischiovertebral dysplasia is a rare skeletal dysplasia that may appear in a sporadic fashion or be inherited with an autosomal dominant inheritance pattern. It is defined by the association of an ischiopubic ramus hypoplasia and a vertebral dysplasia. It leads to a specific spine deformity whose management and complications should be clarified. METHODS: Thirty consecutive patients from 0 to 31 years of age with ischiovertebral dysplasia were included from 5 centers specialized in congenital spinal deformities. Frontal and sagittal Cobb angles before treatment, natural history of the curves, therapeutic options, and their complications were systematically analyzed. RESULTS: All the patients had a vertebral dysplasia and 28 of them developed a spinal deformity. This deformity was an extremely severe thoracic kyphoscoliosis in 25 cases. The other deformities were a thoracolumbar scoliosis in 1 case and a thoracolumbar kyphosis in 2 cases. The management of the thoracic kyphoscoliosis was always challenging and complications included death by respiratory failure (3 cases) and neurological impairment (9 cases). CONCLUSION: Recognizing the occurrence of ischioverterbral dysplasia is very important to allow for dedicated treatment. The authors advocate preoperative distraction and circumferential fusion to prevent progression of the curve and to avoid the potentially fatal sequelae associated with this disorder. LEVEL OF EVIDENCE: 4.

Treatment of hip dysplasia in patients with mucopolysaccharidosis type I after hematopoietic stem cell transplantation: results of an international consensus procedure.

BACKGROUND: Mucopolysaccharidosis type I (MPS-I) is a lysosomal storage disorder characterized by progressive multi-organ disease. The standard of care for patients with the severe phenotype (Hurler syndrome, MPS I-H) is early hematopoietic stem cell transplantation (HSCT). However, skeletal disease, including hip dysplasia, is almost invariably present in MPS I-H, and appears to be particularly unresponsive to HSCT. Hip dysplasia may lead to pain and loss of ambulation, at least in a subset of patients, if left untreated. However, there is a lack of evidence to guide the development of clinical guidelines for the follow-up and treatment of hip dysplasia in patients with MPS I-H. Therefore, an international Delphi consensus procedure was initiated to construct consensus-based clinical practice guidelines in the absence of available evidence. METHODS: A literature review was conducted, and publications were graded according to their level of evidence. For the development of consensus guidelines, eight metabolic pediatricians and nine orthopedic surgeons with experience in the care of MPS I patients were invited to participate. Eleven case histories were assessed in two written rounds. For each case, the experts were asked if they would perform surgery, and they were asked to provide information on the aspects deemed essential or complicating in the decision-making process. In a subsequent face-to-face meeting, the results were presented and discussed. Draft consensus statements were discussed and adjusted until consensus was reached. RESULTS: Consensus was reached on seven statements. The panel concluded that early corrective surgery for MPS I-H patients with hip dysplasia should be considered. However, there was no full consensus as to whether such a procedure should be offered to all patients with hip dysplasia to prevent complications or whether a more conservative approach with surgical intervention only in those patients who develop clinically relevant symptoms due to the hip dysplasia is warranted. CONCLUSIONS: This international consensus procedure led to the construction of clinical practice guidelines for hip dysplasia in transplanted MPS I-H patients. Early corrective surgery should be considered, but further research is needed to establish its efficacy and role in the treatment of hip dysplasia as seen in MPS I.

Delayed bone age due to a dual effect of FGFR3 mutation in Achondroplasia.

Achondroplasia (ACH), the most common form of human dwarfism is caused by a mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene, resulting in constitutive activation of the receptor. Typical radiological features include shortening of the tubular bones and macrocephaly, due to disruption of endochondral ossification. Consequently, FGFR3 has been described as a negative regulator of bone growth. Studying a large cohort of ACH patients, a delay in bone age was observed shortly after birth (for boys p=2.6×10(-9) and for girls p=1.2×10(-8)). This delay was no longer apparent during adolescence. In order to gain further insight into bone formation, bone development was studied in a murine model of chondrodysplasia (Fgfr3(Y367C/+)) from birth to 6weeks of age. Delayed bone age was also observed in Fgfr3(Y367C/+) mice at 1week of age followed by an accelerated secondary ossification center formation. A low level of chondrocyte proliferation was observed in the normal growth plate at birth, which increased with bone growth. In the pathological condition, a significantly high level of proliferative cells was present at birth, but exhibited a transient decrease only to rise again subsequently. Histological and in situ analyses suggested the altered endochondral ossification process may result from delayed chondrocyte differentiation, disruption of vascularization and osteoblast invasion of the femur. All these data provide evidence that FGFR3 regulates normal chondrocyte proliferation and differentiation during bone growth and suggest that constitutive activation of the receptor disrupts both processes. Therefore, the consequences of FGFR3 activation on the physiological process of bone development appear to be dependent on spatial and temporal occurrence. In conclusion, these observations support the notion that FGFR3 has a dual effect, as both a negative and a positive regulator of the endochondral ossification process during post-natal bone development.

Influence of asymmetric tether on the macroscopic permeability of the vertebral end plate.

We implemented an experimental model of asymmetrical compression loading of the vertebral end plate (VEP) in vivo. The macroscopic permeability of the VEP was measured. We hypothesized that static asymmetrical loading on vertebrae altered the macroscopic permeability of the VEP. In scoliosis, solute transport to and from the disc is dramatically decreased especially at the apical intervertebral disc. The decrease in permeability could be induced by mechanical stress. Nine skeletally immature pigs were instrumented with left pedicle screws and compression rod at the T5/T6 and L1/L2 levels. After 3 months, three cylindrical specimens of the VEP were obtained from each of the tethered levels. A previously validated method for measuring permeability, based on the relaxation pressure due to a transient-flow rate was used. A pistoning device generated a fluid flow that fully saturated the cylindrical specimen. The decrease in upstream pressure was measured using a pressure transducer, which allowed the macroscopic permeability to be derived. A microscopic study completed the approach. Overall macroscopic permeability was lower for the tethered VEPs than for the VEPs of the control group, respectively -47% for flow-in (p = 0.0001) and -46% for flow-out (p = 0.0001). In the tethered group, macroscopic permeability of the specimens from the tethered side was lower than macroscopic permeability of those from the non-tethered side, -39% for flow-out (p = 0.024) and -47% for flow-in (p = 0.13). In the control group, the macroscopic permeability was greater in the center of the VEP than in its lateral parts for flow-out (p = 0.004). Macroscopic permeability of the center of the VEPs was greater for flow-out than for flow-in (p = 0.02). There was no significant difference between thoracic and lumbar. This study demonstrated that compression loading applied to a growing spine results in decreased permeability of the VEP. This result could be explained by local remodeling, such as calcification of the cartilage end plate or sclerosis of the underlying bone.