Surgical Treatment of Scoliosis in Osteogenesis Imperfecta With Cement-augmented Pedicle Screw Instrumentation

Orthopedic Surgery in Osteogenesis Imperfecta in Adults

Osteogenesis imperfecta is a genetic disorder, mainly characterized by bone fragility. In adult with osteogenesis imperfecta, surgical treatment may be indicated as an emergency procedure in the event of a fracture, or as a scheduled procedure in case of patient functional impairment due to many causes, such as persistent pain, complex bone deformities, and degenerative arthropathies. In all cases, a multidisciplinary approach is recommended. It is essential to consider the patient's characteristics and expectations regarding treatment, as well as the local conditions, which may be complex due to the poor bone quality, bone deformity, and the presence of hardware implanted during childhood. The procedure can be very complex and challenging and each patient is a unique case. An accurate preoperative planning is mandatory to select the appropriate surgical technique, which can be either conservative or prosthetic, and to evaluate its feasibility and the risk-benefit ratio. The aim is to improve the patient's quality of life and autonomy as long as possible.

Midterm Outcomes of Multimodal Approach to Treating Severe Scoliosis in Patients With Osteogenesis Imperfecta

INTRODUCTION

The surgical management of severe scoliosis in patients with osteogenesis imperfecta (OI) is challenging because of curve rigidity, small stature, and inherent bone fragility. This study evaluated the midterm outcomes of our multimodal approach to address these issues, integrating perioperative bisphosphonate therapy, preoperative/intraoperative traction, various osteotomies, segmental pedicle screw instrumentation with cement augmentation, and bone morphogenetic protein-2 application.

METHODS

A single-center retrospective review of 30 patients (average age 14.1 ± 2.2 years; 18 were female) diagnosed with OI and scoliosis was conducted. These patients underwent posterior spinal fusion between 2008 and 2020 and completed a minimum follow-up of 2 years. We measured radiographic parameters at each visit and reviewed the incidence of complications. A mixed-effects model was used to evaluate changes in radiographic parameters from preoperative measurements to the first and latest follow-ups.

RESULTS

The patient cohort consisted of 2 individuals with type I OI, 20 with type III, 6 with type IV, and 2 with other types (types V and VIII). Surgical intervention led to a notable improvement in the major curve magnitude from 76° to 36°, with no notable correction loss. In addition, the minor curve, apical vertical translation, lowest instrumented vertebra tilt, and pelvic obliquity were also improved. In the sagittal plane, thoracic kyphosis and lumbar lordosis remained unchanged while thoracolumbar kyphosis markedly improved. Two patients experienced proximal junctional kyphosis with screw pullout, one of whom required revision surgery. One patient developed a superficial infection that was successfully treated with oral antibiotics. No instances of neurologic deficits or cement extravasation were observed.

DISCUSSION

This study demonstrated the effectiveness and safety of our multimodal approach to treating scoliosis in patients with OI, achieving a 53% major curve correction with minimal complications over 2-year follow-up. These findings provide notable insights into managing scoliosis in this population.

LEVEL OF EVIDENCE

Level IV (case series).

Paediatric syndromic scoliosis: proceedings of the half-day course at the 57th annual meeting of the Scoliosis Research Society

There are some syndromes that present with unique manifestations pertaining to the spinal column. A good working understanding of these common syndromes is useful for the spinal deformity surgeons and related healthcare providers. This review attempts to encompass these unique features and discuss them in three broad groups: hypermobility syndromes, muscle pathology-related syndromes, and syndromes related to poor bone quality. This review explores the features of these syndromes underpinning the aspects of surgical and medical management. This review represents the proceedings of the Paediatric Half-Day Course at the 57th Annual Meeting of the Scoliosis Research Society.

Cement Augmented Pedicle Screw Instrumentation in Pediatric Spine Surgery

BACKGROUND

Osteoporosis in pediatric patients is rare. Osteomalacia and osteoporosis are known to develop in syndromic or neuromuscular scoliosis children. Spinal deformity surgery for pediatric patients with osteoporosis is challenging, associated with pedicle screw (PS) failure and compression fractures. Cement augmentation of PS is one several measures to prevent screw failure. It provides additional pull-out strength to the PS in the osteoporotic vertebra.

METHODS

In 2010-2020, an analysis of pediatric patients who had cement augmentation of PS with a minimum follow-up of 2 years was performed. Radiological and clinical evaluations were analyzed.

RESULTS

The study included 7 patients (4 girls, 3 boys) with a mean age of 13 years (range, 10-14 years) and mean follow-up of 3 years (range, 2-3 years). Only 2 patients underwent revision surgery. Total number of cement augmented PSs was 52 with an average of 7 per patient. Only 1 patient had lower instrumented vertebra vertebroplasty. There was no PS pull-out in the cement augmented levels, and there were no neurological deficits or pulmonary cement embolisms. One patient developed a PS pull-out in uncemented levels. Two patients developed compression fractures, one, with osteogenesis imperfecta, in the supra-adjacent levels (upper instrumented vertebra + 1 and upper instrumented vertebra + 2), and the other, with neuromuscular scoliosis, in the uncemented segments.

CONCLUSIONS

In this study, all cement augmented PSs provided satisfactory radiological outcomes without PS pull-out and adjacent vertebral compression fracture. In pediatric spine surgery, in osteoporotic patients with a poor bone purchase, cement augmentation may be used, especially in high-risk patients with osteogenesis imperfecta, neuromuscular scoliosis, and syndromic scoliosis.

Surgical outcomes for spinal deformity in osteogenesis imperfecta

STUDY DESIGN

IRB approved retrospective review of the the SHOnet (Shriners Health Outcomes Network).

OBJECTIVES

Osteogenesis imperfecta (OI) is the most prevalent genetic disorder of bone and connective tissue in the pediatric population, with an incidence of 1/15,000-20,000. Scoliosis has been reported to be present in 39-100% of OI patients and may continue to progress into adulthood but there is little information on the perioperative outcomes, rates of revision surgery and complications in this fragile population. The purpose of this study is to examine the prevalence of scoliosis in the OI population across a tertiary care multihospital system. The rate at which these patients progress to surgery, the perioperative complication rate and if there is an association between complications and age at surgical intervention, pre-operative Cobb angle, number of fractures, and type of OI. Incidence of scoliosis in OI may be lower than previously reported, many may never require surgical intervention and those that do require surgical intervention have an 8% reoperation rate at an average of 3.3 years postop.

METHODS

IRB approved retrospective review of the the SHOnet (Shriners Health Outcomes Network), electronic health record data warehouse from January 1, 2011 and December 31, 2017. Inclusion criteria included International Classification of Diseases (ICD) code for osteogenesis imperfecta and scoliosis. The data warehouse was queried for age, gender, presence of vertebral body fractures, proximal junctional kyphosis, basilar invagination, bisphosphonate use, and perioperative complications including postoperative infection.

RESULTS

There were 2372 patients with osteogenesis imperfecta, 429 or 18.1% also had a diagnosis of scoliosis, while 81.9% did not (see Table 1). Only 74 patients (17.2%) of the patients that had scoliosis underwent spine surgery, 12 of which had staged surgery with an average preop thoracic Cobb 58.18 (range 7-115), and thoracolumbar Cobb 59.83 (range 5-145). Six patients (8%) required revision spine surgery. Average time to revision was 3.88 years (6.9-69mo). Bisphosphonate use was present in 35.5% of patients that did not require surgery and in 40.5% that did.

CONCLUSION

With over 2300 patients, this is the largest study to date on scoliosis in patients with OI. We found that contrary to prior studies which had indicated the incidence of scoliosis ranges from 39 to 100% that it was only present in 18% of our patients. This indicates that the incidence of scoliosis in OI is potentially lower than previously reported, though due to the nature of this study it may be underreported. Furthermore, only 17% of those patients in our study with scoliosis eventually underwent surgery. It is important to note that many patients treated non-operatively had deformity within the operative range, which may indicate that they were not considered good candidates for surgical intervention. Lastly, we found that bisphosphonate use did not appear to affect the likelihood of progression to surgery in this group of patients, though this may be due to later initiation of the bisphosphonate use.

Scoliosis in osteogenesis imperfecta: results of posterior spinal fusion in 39 patients

PURPOSE

To evaluate the outcomes of scoliosis corrective surgery in Osteogenesis Imperfecta (OI) patients with primarily pedicles screw fixation in terms of correcting and maintaining the correction of the spinal deformity, and to assess for several peri-operative parameters and complications associated with this surgical treatment.

METHODS

Retrospective case series of 39 consecutive patients with OI treated surgically for scoliosis. The surgeries were performed between 2002 and 2020 by three different surgeons. All patients' medical peri-operative and post-operative charts were evaluated. Radiological assessment was performed by evaluation of the pre-operative, immediate post-operative and last follow-up plain radiographs.

RESULTS

There were 20 females and 19 males included in this review with a mean age of 14 years (range, 6-20 years) at the time of surgery. The median follow-up time was 7.9 years. The mean pre-operative cobb angle (CA) of the major curve was 76.5 degrees (SD ± 18.9), decreasing to 42.6 (SD ± 17.4) in the long-term post-operative follow-up (P < 0.001). A total of 21 adverse events in 16 patients were noted. Only 4 patients required subsequent invasive surgical treatment or prolonged hospital stay. All other patients were treated conservatively with no lasting complication.

CONCLUSION

Scoliosis surgical correction in OI patients seems to yield acceptable results, with maintained coronal plane surgical correction in the long-term follow-up. Even though a high peri-operative complications rate is observed in this series, there were no long-term sequelae or lasting complications.

LEVEL OF EVIDENCE

Level IV, Case series.

Cementless posterior spinal fusion for the treatment of OI patients with severe spine deformity-a case series

PURPOSE

The purpose of this study is to present the outcomes all patients with osteogenesis imperfecta (OI) who underwent cementless posterior spinal fusion for the treatment of severe spine deformity in our institution.

METHODS

All patients with OI who underwent surgical correction of their spine deformity in our institution between 2003 and 2020 were enrolled. The collected data included demographics, operative and follow-up findings, medical history, bisphosphonate therapy, HGT protocol, pre- and post-HGT and postoperative scoliosis and kyphosis curve measurements, hospitalization length, complications, and revision surgeries. General treatment strategies included cessation of bisphosphonate therapy around the surgery, 30-day HGT protocol, titanium rods, cementless screw technique, and a high implant density policy.

RESULTS

Eleven consecutive patients with OI who underwent surgery for spine deformity in our institution were identified. The mean age at surgery was 15.6 ± 2.3. Mean follow-up period was 6.6 ± 5.8 years. The mean pre- and postoperative scoliosis curves were 85.4 ± 19.3° and 43.1 ± 12.5°, respectively, representing a 49.5% correction rate. Five patients underwent HGT and achieved a mean correction of 27.6 ± 7.1° (31.6%) preoperatively. Implant density ratio was 1.5 (screw or hook/level). Mean postoperative hospitalization length was 5.9 ± 1.6 days. One patient had deep wound infection which resolved following treatment according to our protocol for surgical site infection, and one patient had skull penetration by one of the halo pins.

CONCLUSION

Surgical treatment of severe spine deformity in OI patients with cementless posterior spinal fusion is safe and effective after applying a specific preoperative strategy.

The Biomechanical Properties of Cement-Augmented Pedicle Screws for Osteoporotic Spines

STUDY DESIGN

This is a broad, narrative review of the literature.

OBJECTIVE

In this review, we describe recent biomechanics studies on cement-augmented pedicle screws for osteoporotic spines to determine which factors influence the effect of cement augmentation.

METHODS

A search of Medline was performed, combining the search terms "pedicle screw" and ("augmentation" OR "cement"). Articles published in the past 5 years dealing with biomechanical testing were included.

RESULTS

Several factors have been identified to impact the effect of cement augmentation in osteoporotic spines. These include the type of augmentation material, the volume of injected cement, the timing of augmentation, the severity of osteoporosis, the design of the pedicle screw, and the specific augmenting technique, among others.

CONCLUSIONS

This review elaborates the biomechanics of cement-augmented pedicle screws, determines which factors influence the augmentation effect, and identifies the risk factors of cement leakage in osteoporotic bone, which might offer some guidance when using this technique in clinical practice. Further, we provide information about newly designed screws and recently developed augmentation materials that provide higher screw stability as well as fewer cement-related complications.

Osteogenesis Imperfecta: Mechanisms and Signaling Pathways Connecting Classical and Rare OI Types

Osteogenesis imperfecta (OI) is a phenotypically and genetically heterogeneous skeletal dysplasia characterized by bone fragility, growth deficiency, and skeletal deformity. Previously known to be caused by defects in type I collagen, the major protein of extracellular matrix, it is now also understood to be a collagen-related disorder caused by defects in collagen folding, posttranslational modification and processing, bone mineralization, and osteoblast differentiation, with inheritance of OI types spanning autosomal dominant and recessive as well as X-linked recessive. This review provides the latest updates on OI, encompassing both classical OI and rare forms, their mechanism, and the signaling pathways involved in their pathophysiology. There is a special emphasis on mutations in type I procollagen C-propeptide structure and processing, the later causing OI with strikingly high bone mass. Types V and VI OI, while notably different, are shown to be interrelated by the interferon-induced transmembrane protein 5 p.S40L mutation that reveals the connection between the bone-restricted interferon-induced transmembrane protein-like protein and pigment epithelium-derived factor pathways. The function of regulated intramembrane proteolysis has been extended beyond cholesterol metabolism to bone formation by defects in regulated membrane proteolysis components site-2 protease and old astrocyte specifically induced-substance. Several recently proposed candidate genes for new types of OI are also presented. Discoveries of new OI genes add complexity to already-challenging OI management; current and potential approaches are summarized.

Surgical Outcome of Spinal Fusion for Osteogenesis Imperfecta With Scoliosis: Is the Hybrid System With Pedicle Screws Applicable to Weak, Tiny, and Fragile Vertebrae?

INTRODUCTION

Corrective surgery for spinal deformity associated with osteogenesis imperfecta (OI) is challenging due to the severe and rigid deformity combined with extreme bone fragility. However, surgical outcomes still remain unclear. In addition, the applicability of pedicle screws (PSs) to the tiny and fragile vertebrae in patients with OI is poorly understood. This study evaluated the surgical outcome, and the accuracy and safety of PS placement in patients with OI.

METHODS

Twenty-five patients with OI were included in this study. Mean age was 21.0±9.3 (10 to 49) years. Mean follow-up was 5.8±2.0 years. The Sillence classification showed 16 patients had the mildest type I, 1 patient had moderate type IV, and 8 patients had the most severe type III. Fifteen patients underwent anterior release followed by posterior fusion, and 10 patients underwent only posterior fusion. The accuracy of PS placement was evaluated with postoperative computed tomography.

RESULTS

Scoliosis was corrected from 95.6 to 65.8 degrees after surgery (correction rate 32.5%) and 68.1 degrees at final follow-up (both, P<0.01). Space available for the lung was improved from 76.3% to 84.9% (P<0.05). No implant dislodgement occurred after surgery. A total of 290 screws were placed, of which 213 screws (73.4%) were placed completely. However, 30 screws (10.3%) penetrated >2 mm. In particular, rates of >2 mm penetration was much higher in type III than type I and IV (27.8% vs. 3.0%; P<0.01). Complications related to spinal surgery included 2 transient neurological disturbances.

CONCLUSIONS

PSs were applicable to spinal fusion surgery in patients with OI. However special care should be taken in placing PSs because of the weakness of the pedicle cortex, which was easily penetrated especially in Sillence type III.

LEVEL OF EVIDENCE

Level IV.

The growth-friendly surgical treatment of scoliosis in children with osteogenesis imperfecta using distraction-based instrumentation

PURPOSE

The study was undertaken to determine the feasibility of growth-friendly distraction-based surgery in children with OI.

METHODS

Two multi-center databases were queried for children with OI who had undergone GR or VEPTR surgery. Inclusion criteria were a minimum 2-year follow-up and three lengthening procedures following the initial implantation. Details of the surgical techniques, surgical complications, and radiographic measurements of deformity correction, T1-T12 and T1-S1 elongation and growth were recorded.

RESULTS

Five patients were identified. There was one patient with type I OI and two patients each with type III and type IV. Four patients had GR constructs and one a VEPTR construct. The initial scoliosis deformity averaged 80° (70°-103°), and the subsequent corrections averaged 32% for initial correction, 48% at last follow-up, and 54% for the two patients that had a final fusion. The T1-T12 and T1-S1 growth averaged 31 mm and 44 mm respectively, and yearly growth averaged 4 mm and 6 mm, respectively. Growth was notably much less in those with more severe disease. There were 13 complications in 4 patients. Nine of the 10 surgical complications were anchor failures which were corrected in 7 planned and 2 un-planned procedures. Significant migration occurred in one patient with severe OI type III.

CONCLUSION

The results varied in this heterogeneous population. In general, satisfactory deformity corrections were obtained and maintained, modest growth was obtained, and complications were similar to those reported in other series of growth-friendly surgery. Limited growth and significant anchor migration are to be anticipated in this population.

LEVEL OF EVIDENCE

IV.

Growing Rod Surgery for Early-Onset Scoliosis in an Osteogenesis Imperfecta Patient

BACKGROUND

Osteogenesis imperfecta (OI) is characterized by bone fragility and is often accompanied by spinal deformity. Surgical treatment for early-onset scoliosis in patients with OI is hazardous and difficult due to the bone fragility and rigidity of the deformity. A case of early-onset scoliosis with OI that was treated using growing-rod surgery is presented.

CASE DESCRIPTION

The patient was an 11-year-old girl with type 4 OI. At the age of 4 years, she was noted to have scoliosis. Preoperative radiographs showed that the Cobb angle, thoracic kyphosis angle, and T1-S1 height were 94°, 77°, and 258 mm, respectively. One year before the operation, she underwent cyclic intravenous pamidronate disodium treatment. Three months after the pedicle screws were inserted, the growing rods were placed with pedicle screws and sublaminar polyethylene tape. The patient had intraoperative traction for correction. At 13 years and 11 months, the patients underwent posterior instrumentation and spinal fusion. Postoperative radiographs showed that the Cobb angle, thoracic kyphosis angle, and T1-S1 height were 29°, 29°, and 405 mm, respectively. Three months after the operation, she was well, and there have been no spine-related problems.

CONCLUSIONS

This case demonstrates the successful use of the growing rod for early-onset scoliosis in patients with OI. The treatment strategy, which included pedicle screw insertion as anchors to create the foundations in advance, sublaminar tape, intraoperative traction, and preoperative bisphosphonate administration, might have led to the good outcome.

Management of Catastrophic Proximal Junctional Failure Following Spinal Deformity Correction in an Adult with Osteogenesis Imperfecta: Case Report and Technical Note

BACKGROUND

Proximal junctional failure (PJF) is a major and sometimes devastating problem following adult spinal deformity (ASD) correction surgery. Common consensus still lags on guidelines for preventing and managing these complications. Surgical treatment of scoliosis in the presence of osteogenesis imperfecta (OI) in the pediatric population is well described. The complication rates are unusually higher in this special subset of patients owing to poor quality of bone. There is a paucity of literature focusing on surgical techniques, strategies, and problems involved in the management of ASD associated with OI.

CASE DESCRIPTION

We report a 59-year-old female with type 1 OI and adult scoliosis who underwent T10-to-pelvis fusion for ASD according to the principles of adult deformity correction. At a 1-year follow-up, she presented with asymptomatic proximal junctional kyphosis of 45° and 2 weeks later had PJF along with spinal cord injury after a fall. On computed tomography scan, kyphosis was increased to 60° at T9-T10. She underwent decompression and revision deformity correction using quadruple rods, with extension of instrumentation to T2 with soft landing using rib bands. At a 4-year follow-up, she had a good functional outcome after revision surgery.

CONCLUSIONS

This is the first report of successful management of PJF following ASD correction in the presence of OI using this technique. Suboptimal hold of implants due to poor bone quality must be at the focus of any surgical planning for these patients. All possible strategies to prevent PJF must be considered when planning the deformity correction in adults with OI.

Osteogenesis Imperfecta: A Pediatric Orthopedic Perspective

Osteogenesis imperfecta is a genetically and phenotypically heterogeneous disorder related to a defect or deficiency in the production of type I collagen. It is characterized by brittle bones, fractures, spine and extremity deformity, and a host of extraskeletal manifestations. Type I collagen is present in bone, tendons, ligaments, skin, dentin, and the sclera of the eye and other connective tissues. Osteogenesis imperfecta includes a multitude of disease manifestations that may be present at birth or develop over time and vary depending on the severity of the disease. This article describes the disease presentation and management considerations from a pediatric orthopedic perspective.

Complex spine deformities in young patients with severe osteogenesis imperfecta: current concepts review

The severity of osteogenesis imperfecta (OI), the associated reduced quality and quantity of collagen type I, the degree of bone fragility, ligamentous laxity, vertebral fractures and multilevel vertebral deformities all impair the mechanical integrity of the whole spinal architecture and relate to the high prevalence of progressive kyphoscoliotic deformities during growth. Bisphosphonate therapy may at best slow down curve progression but does not seem to lower the prevalence of deformities or the incidence of surgery. Brace treatment is problematic due to pre-existing chest wall deformities, stiffness of the curve and the brittleness of the ribs which limit transfer of corrective forces from the brace shell to the spine. Progressive curves entail loss of balance, chest deformities, pain and compromise of pulmonary function and eventually require surgical stabilization, usually around puberty. Severe vertebral deformities including deformed, small pedicles, highly brittle bones and chest deformities, short deformed trunks and associated issues like C-spine and cranial base abnormalities (basilar impressions, cervical kyphosis) as well as deformed lower and upper extremities are posing multiple peri- and intraoperative challenges. Hence, an early multidisciplinary approach (anaesthetist, pulmonologist, paediatric orthopaedic spine surgeon) is mandatory. This paper was written under the guidance of the Spine Study Group of the European Paediatric Orthopaedic Society. It highlights the most pertinent information given in the current literature and various practical aspects on surgical care of spine deformities in young OI patients based on the personal experience of the contributing authors.

Basilar impression in osteogenesis imperfecta treated with staged halo traction and posterior decompression with short-segment fusion

Basilar impression is a cranial base abnormality associated with osteogenesis imperfecta (OI) with serious neurologic implications but controversial treatment options. Combined anterior and posterior decompression with long-segment posterior fusion is often recommended. We report a patient with OI (Sillence type III) with basilar impression treated with halo traction followed by posterior surgery. The patient was a 12-year-old female with a presentation of hiccups and change in upper extremity function. Diagnostic imaging revealed syringomyelia, compensated hydrocephalus, basilar impression, and Chiari type I malformation. The patient was treated with halo traction followed by posterior decompression fusion from the occipital bone to C2. Bone fusion and improved syrinx were evident on images during the 5 years of follow-up. Five years after surgery, syrinx recurred and the fourth ventricular catheter was revised. The treatment with halo traction followed by posterior-only surgery of basilar impression associated with OI resulted in a good postoperative outcome.

A comparison of the biomechanical stability of pedicle-lengthening screws and traditional pedicle screws: an in vitro instant and fatigue-resistant pull-out test

Aims

The aim of this study was to compare the peak pull-out force (PPF) of pedicle-lengthening screws (PLS) and traditional pedicle screws (TPS) using instant and cyclic fatigue testing.

Materials and Methods

A total of 60 lumbar vertebrae were divided into six groups: PLS submitted to instant pull-out and fatigue-resistance testing (groups A1 and A2, respectively), TPS submitted to instant pull-out and fatigue-resistance testing (groups B1 and B2, respectively) and PLS augmented with 2 ml polymethylmethacrylate, submitted to instant pull-out and fatigue-resistance testing (groups C1 and C2, respectively). The PPF and normalized PPF (PPFn) for bone mineral density (BMD) were compared within and between all groups.

Results

In all groups, BMD was significantly correlated with PPF (r = 0.83, p < 0.001). The PPFn in A1 was significantly less than in B1 (p = 0.006) and C1 (p = 0.002). The PPFn of A2 was significantly less than in B2 (p < 0.001) and C2 (p < 0.001). The PPFn in A1, B1, and C1 was significantly greater than in A2 (p = 0.002), B2 (p = 0.027), and C2 (p = 0.003). There were no significant differences in PPFn between B1 and C1, or between B2 and C2.

Conclusion

Pedicle lengthening screws with cement augmentation can provide the same fixation stability as traditional pedicle screws and may be a viable clinical option. Cite this article: Bone Joint J 2018;100-B:516-21.

The use of magnetically controlled growing rods in paediatric Osteogenesis Imperfecta with early onset, progressive scoliosis

Osteogenesis Imperfecta (OI) is a condition of bone fragility and can present with early onset scoliosis that can cause respiratory complications in later life. The fear of instrumenting the spine in OI is the possibility of fracture either on primary insertion or subsequent lengthening. Magnetically controlled growing rods were inserted to control a scoliosis in a 6-year old with OI type IV. Fixation was obtained using pedicle screws proximally and distally with sublaminar bands around the ribs proximally. These rods have been remotely lengthened on multiple occasions over a 2-year period. This has controlled the scoliosis whilst also allowing the spine to grow. There are no complications to report. This case reports the use of magnetically controlled growth rods used to manage early onset scoliosis in OI. Frequent lengthening, achieving small increases in length on every occasion protects against the risk of fracture during the lengthening procedure.

Type V osteogenesis imperfecta undergoing surgical correction for scoliosis

PURPOSE

The objective of this article is to report a case of type V osteogenesis imperfecta (OI) undergoing posterior instrumented fusion for scoliosis. Type V OI is a moderately severe dysplasia causing primary defects in endochondral bone ossification or mineralisation. It is characterised by hyperplastic callus (HPC) formation, interosseous membrane calcifications, poor bone quality and spinal deformities including scoliosis. Data on the surgical management of spinal deformities in this patient group are lacking.

CASE REPORT

A 16-year-old patient with a confirmed diagnosis of type V OI presented with a progressive scoliosis. The patient underwent a T3-L4 posterior instrumented correction and fusion utilising pedicle screws, pedicle hooks and sub-laminar wiring. At 4 months after surgery, the pedicle hooks pulled out and required partial metalwork removal after CT scanning confirmed bony union and no evidence of HPC formation. The patient was successfully discharged with satisfactory correction, confirmed bony union, no neurologic complication and absence of any hyperplastic callus formation.

CONCLUSION

Type V OI patients requiring surgical intervention for scoliosis correction can safely undergo posterior instrumented fusion using sublaminar wiring and pedicle hook/screw constructs without apparent risk of HPC formation around neural elements. Surgery in this patient group remains challenging due to the associated poor bone quality.

LEVEL OF EVIDENCE

V.

[Biomechanical study of a newly-designed Y type pedicle screw in osteoporotic synthetic bone]

Objective

To evaluate the biomechanical stability of a newly-designed Y type pedicle screw (YPS) in osteoporotic synthetic bone.

Methods

The osteoporotic synthetic bone were randomly divided into 3 groups ( n=20). A pilot hole, 3.0 mm in diameter and 30.0 mm in deep, was prepared in these bones with the same method. The YPS, expansive pedicle screw (EPS), and bone cement-injectable cannulated pedicle screw (CICPS) were inserted into these synthetic bone through the pilot hole prepared. X-ray film examination was performed after 12 hours; the biomechanical stability of YPS, EPS, and CICPS groups was tested by the universal testing machine (E10000). The test items included the maximum axial pullout force, the maximum running torque, and the maximum periodical anti-bending.

Results

X-ray examination showed that in YPS group, the main screw and the core pin were wrapped around the polyurethane material, the core pin was formed from the lower 1/3 of the main screw and formed an angle of 15° with the main screw, and the lowest point of the inserted middle core pin was positioned at the same level with the main screw; in EPS group, the tip of EPS expanded markedly and formed a claw-like structure; in CICPS group, the bone cement was mainly distributed in the front of the screw and was dispersed in the trabecular bone to form a stable screw-bone cement-trabecular complex. The maximum axial pullout force of YPS, EPS, and CICPS groups was (98.43±8.26), (77.41±11.41), and (186.43±23.23) N, respectively; the maximum running torque was (1.42±0.33), (0.96±0.37), and (2.27±0.39) N/m, respectively; and the maximum periodical anti-bending was (67.49±3.02), (66.03±2.88), and (143.48±4.73) N, respectively. The above indexes in CICPS group were significantly higher than those in YPS group and EPS group ( P<0.05); the maximum axial pullout force and the maximum running torque in YPS group were significantly higher than those in EPS group ( P<0.05), but there was no significant difference in the maximum periodical anti-bending between YPS group and EPS group ( P>0.05).

Conclusion

Compared with EPS, YPS can effectively enhance the maximum axial pullout force and maximum rotation force in the module, which provides a new idea for the design of screws and the choice of different fixation methods under the condition of osteoporosis.

Surgical Treatment With Pedicle Screws of Scoliosis Associated With Osteogenesis Imperfecta in Children

STUDY DESIGN

Retrospective study.

OBJECTIVE

To assess results of posterior instrumented fusion using pedicle screws in 12 children with osteogenesis imperfecta (OI) with spinal deformity at a single institution from 2001 to 2012.

SUMMARY OF BACKGROUND DATA

This is the first case series of OI patients who underwent non-cement augmented screw-rod instrumented fusion published in the literature.

METHODS

Of a total of 54 children with spinal deformity associated with OI, 12 (22.2%) were submitted to posterior spinal fusion with pedicle screws (80% density) because of severe spinal deformity. Here we reported the results in seven females and five males.

RESULTS

Five thoracic (41.7%), five double (thoracic and lumbar 41.7%), and two lumbar (16.7%) curves were considered. The mean number of fused levels was 11.8 (range: 5 to 16). Mean age at surgery was 13 years 8 months. Mean follow-up was 7 years 11 months (range: 3 years 7 months to 16 years 1 month). The mean preoperative scoliosis angle was 75.6°, whereas the postoperative angle was 31.4° (58.5% correction rate). The mean preoperative kyphosis angle was 57.4° and the postoperative angle was 42.3°. We observed one superficial infection, one dural tear, and three cases of proximal junctional kyphosis; two patients required one revision surgery each (2 years and 4 months postoperatively on average).

CONCLUSIONS

To our knowledge, this is the first case series published in the literature regarding OI with instrumented fusion with non-cement augmented pedicle screws exclusively in children with spinal deformity. We found that posterior spinal fusion with the screw-rod system in OI deformity in children is feasible and reliable, and has acceptable clinical and imaging results in the long-term follow-up.

LEVEL OF EVIDENCE

Level IV.

The Spine in Patients With Osteogenesis Imperfecta

Osteogenesis imperfecta is a genetic disorder of type I collagen. Although multiple genotypes and phenotypes are associated with osteogenesis imperfecta, approximately 90% of the mutations are in the COL1A1 and COL1A2 genes. Osteogenesis imperfecta is characterized by bone fragility. Patients typically have multiple fractures or limb deformity; however, the spine can also be affected. Spinal manifestations include scoliosis, kyphosis, craniocervical junction abnormalities, and lumbosacral pathology. The incidence of lumbosacral spondylolysis and spondylolisthesis is higher in patients with osteogenesis imperfecta than in the general population. Use of diphosphonates has been found to decrease the rate of progression of scoliosis in patients with osteogenesis imperfecta. A lateral cervical radiograph is recommended in patients with this condition before age 6 years for surveillance of craniocervical junction abnormalities, such as basilar impression. Intraoperative and anesthetic considerations in patients with osteogenesis imperfecta include challenges related to fracture risk, airway management, pulmonary function, and blood loss.

Multiple Spinal Revision Surgery in a Patient with Parkinson's Disease

Parkinson's disease (PD) patients frequently have several spinal deformities leading to postural instabilities including camptocormia, myopathy-induced postural deformity, Pisa syndrome, and progressive degeneration, all of which adversely affect daily life activities. To improve these postural deformities and relieve the related neurologic symptoms, patients often undergo spinal instrumentation surgery. Due to progressive degenerative changes related to PD itself and other complicating factors, patients and surgeons are faced with instrument failure-related complications, which can ultimately result in multiple revision surgeries yielding various postoperative complications and morbidities. Here, we report a representative case of a 70-year-old PD patient with flat back syndrome who had undergone several revision surgeries, including anterior and posterior decompression and fusion for a lumbosacral spinal deformity. The patient ultimately benefitted from a relatively short segment fixation and corrective fusion surgery.

Influence of the intensity and loading time of direct current electric field on the directional migration of rat bone marrow mesenchymal stem cells

Exogenic electric fields can effectively accelerate bone healing and remodeling through the enhanced migration of bone marrow mesenchymal stem cells (BMSCs) toward the injured area. This study aimed to determine the following: (1) the direction of rat BMSC (rBMSC) migration upon exposure to a direct current electric field (DCEF), (2) the optimal DCEF intensity and duration, and (3) the possible regulatory role of SDF-1/CXCR4 axis in rBMSC migration as induced by DCEF. Results showed that rBMSCs migrated to the positive electrode of the DCEF, and that the DCEF of 200 mV/mm for 4 h was found to be optimal in enhancing rBMSC migration. This DCEF strength and duration also upregulated the expression of osteoblastic genes, including ALP and OCN, and upregulated the expression of ALP and Runx2 proteins. Moreover, when CXCR4 was inhibited, rBMSC migration due to DCEF was partially blocked. These findings indicated that DCEF can effectively induce rBMSC migration. A DCEF of 200 mV/mm for 4 h was recommended because of its ability to promote rBMSC migration, proliferation, and osteogenic differentiation. The SDF-1/CXCR4 signaling pathway may play an important role in regulating the DCEF-induced migration of rBMSCs.