Aims. This study examined whether systemic administration of melatonin would have different effects on osseointegration in ovariectomized (OVX) rats, depending on whether this was administered during the day or night. Methods. In this study, a titanium rod was implanted in the medullary cavity of one femoral metaphysis in OVX rats, and then the rats were randomly divided into four groups: Sham group (Sham, n = 10), OVX rat group (OVX, n = 10), melatonin day treatment group (OVX + MD, n = 10), and melatonin night treatment group (OVX + MN, n = 10). The OVX + MD and OVX + MN rats were treated with 30 mg/kg/day melatonin at 9 am and 9 pm, respectively, for 12 weeks. At the end of the research, the rats were killed to obtain bilateral femora and blood samples for evaluation. Results. Micro-CT and histological evaluation showed that the bone microscopic parameters of femoral metaphysis trabecular bone and bone tissue around the titanium rod in the OVX + MD group demonstrated higher bone mineral density, bone volume fraction, trabecular number, connective density, trabecular thickness, and lower trabecular speculation (p = 0.004) than the OVX + MN group. Moreover, the biomechanical parameters of the OVX + MD group showed higher pull-out test and three-point bending test values, including fixation strength, interface stiffness, energy to failure, energy at break, ultimate load, and elastic modulus (p = 0.012) than the OVX + MN group. In addition, the bone metabolism index and oxidative stress indicators of the OVX + MD group show lower values of Type I collagen cross-linked C-telopeptide, procollagen type 1 N propeptide, and malondialdehyde (p = 0.013), and higher values of TAC and SOD (p = 0.002) compared with the OVX + MN group. Conclusion. The results of our study suggest that systemic administration with melatonin at 9 am may improve the initial osseointegration of titanium rods under osteoporotic conditions more effectively than administration at 9 pm. Cite this article: Bone Joint Res 2022;11(11):751–762

Aims. Magnetically controlled growing rods (MCGR) have been gaining popularity in the management of early-onset scoliosis (EOS) over the past decade. We present our experience with the first 44 MCGR consecutive cases treated at our institution. Methods. This is a retrospective review of consecutive cases of MCGR performed in our institution between 2012 and 2018. This cohort consisted of 44 children (25 females and 19 males), with a mean age of 7.9 years (3.7 to 13.6). There were 41 primary cases and three revisions from other rod systems. The majority (38 children) had dual rods. The group represents a mixed aetiology including idiopathic (20), neuromuscular (13), syndromic (9), and congenital (2). The mean follow-up was 4.1 years, with a minimum of two years. Nine children graduated to definitive fusion. We evaluated radiological parameters of deformity correction (Cobb angle), and spinal growth (T1-T12 and T1-S1 heights), as well as complications during the course of treatment. Results. The mean Cobb angles pre-operatively, postoperatively, and at last follow-up were 70° (53 to 103), 35° (15 to 71) and 39° (15 to 65) respectively (p < 0.001). Further, there was a mean of 14° (-6 to 27) of additional Cobb angle correction upon graduation from MCGR to definitive fusion. Both T1-T12 and T1-S1 showed significant increase in heights of 27 mm and 45 mm respectively at last follow-up (p < 0.001). Ten children (23%) developed 18 complications requiring 21 unplanned operations. Independent risk factors for developing a complication were single rod constructs and previous revision surgery. Conclusion. MCGR has the benefit of avoiding multiple surgeries, and is an effective tool in treatment of early-onset scoliosis. It also maintains the flexibility of the spine, allowing further correction at the time of definitive fusion. Cite this article: Bone Joint Open 2020;1-7:405–414

Background. Established hip and knee arthroplasty registers exist in many countries but this is not the case with spinal implants. Moreover, in the case of a rod intended to guide spinal growth in a child and then be removed, the definition of ‘failure’ (revision) used for hip or knee arthroplasty is inappropriate. How can the performance of such spinal implants be judged?. Methods. Ninety-six MAGnetic Expansion Control (MAGEC) spinal rods were obtained from multiple centres after removal from the spines of 52 children with scoliosis. Clinical details were assessed and divided between unplanned revision operations (‘failures’) and those which were planned. Of the explanted rods, 49 were tested for the amount of force they could output, using the manufacturer's supplied test jig. Sixty-five rods were cut apart so that the internal components (bearings, O-ring seals, drive pins) could be assessed, alongside if there was evidence of internal wear. Results. Seventy-four per cent of revision operations were unplanned. Eighty per cent of explanted rods were unable to produce the force expected from a new rod. All rods (100%) that were successfully cut open showed signs of internal wear. Non- functional bearings were seen in 74% of cases, obvious seal damage in 57% of cases and broken drive pins in 47% of cases. Conclusion. Despite potential clinical benefits, explanted MAGEC rods showed consistent and substantial damage. The majority of rods showed zero force output and most revision operations were unplanned. Independent explant analysis allows appraisal of new technology in arthroplasty for patient benefit

Introduction. In daily clinical practice, progression of spinal fusion is typically monitored during clinical follow-up using conventional radiography and Computed Tomography scans. However, recent research has demonstrated the potential of implant load monitoring to assess posterolateral spinal fusion in an in-vivo sheep model. The question arises to whether such a strain sensing system could be used to monitor bone fusion following lumbar interbody fusion surgery, where the intervertebral space is supported by a cage. Therefore, the aim of this study was to test human cadaveric lumbar spines in two states: after a transforaminal lumbar interbody fusion (TLIF) procedure combined with a pedicle-screw-rod-construct (PSR) and subsequently after simulating bone fusion. The study hypothesized that the load on the posterior instrumentation decreases as the segment stiffens due to simulated fusion. Method. A TLIF procedure with PSR was performed on eight human cadaveric spines at level L4-L5. Strain sensors were attached bilaterally to the rods to derive implant load changes during unconstrained flexion-extension (FE), lateral bending (LB) and axial rotation (AR) loads up to ±7.5Nm. The specimens were retested after simulating bone fusion between vertebrae L4-L5. In addition, the range of motion (ROM) was measured during each loading mode. Result. The ROM decreased in the simulated bone fusion state in all loading directions (p≤0.002). In both states, the measured strain on the posterior instrumentation was highest during LB motion. Furthermore, the sensors detected a significant decrease in the load induced rod strain (p≤0.002) between TLIF+PSR and simulated bone fusion state in LB. Conclusion. Implant load measured via rod strain sensors can be used to monitor the progression of fusion after a TLIF procedure when measured during LB of the lumbar spine. However, further research is needed to investigate the influence of daily loading scenarios expected in-vivo on the overall change in implant load

A growing number of children are being implanted with magnetically controlled growing rods. Some also have baclofen pumps, a device that delivers a neuromodulating medication using a magnet. There has been no previous testing to determine if the External Remote Controller (ERC) would stall the baclofen pump during magnetic rod lengthening, a potentially life-threatening event. Two baclofen pumps, 20 mL and 40 mL, were placed in varying proximity to the ERC while the magnetic field was generated. The speed (dose) of the baclofen pump, the distance from the ERC, the length of time the ERC was run, the position of the pump in relationship to the magnetic field, and the presence or absence of a stall were recorded. To stall a baclofen pump, the ERC needed to be running continuously for at least 30 mm of lengthening (about 3 minutes). The pump would not stall if it was more than 1 cm away from the ERC, even if the ERC generated a field for 3 minutes. The speed of the pump did not affect the instance of a motor stall. The pump was more likely to stall if it was positioned in front of or behind the magnetic field, as opposed to the center of the field. Baclofen pumps are always more than 1 cm away from the magnetic rods when both are implanted in a child. The typical lengthening interval is under 10 mm, much less than what was required to stall a baclofen pump. The ERC is highly unlikely to stall a baclofen pump during a magnetic rod lengthening, making a life-threatening event almost impossible

In orthopaedic spine surgery pedicle screw systems are used for stabilisation of the spine after injuries or disorders. With an percutaneous operation method surgeons are faced with huge challenges compared to an open surgery, but it's less traumatic and the patient benefits with a faster rehabilitation and less traumatic injuries. The screw positions and the required rod dimensions for the stabilising connection between the screws are hard to define without an open view on the operating field. Because of these facts a new smart device based system for rod shape determination was invented. Therefore, an application was developed, which integrates a localiser module to get the position data of the pedicle screws, with help of rigid bodies placed on top of the pedicle screws down-tubes. An algorithm was developed to choose the best fitting rod to connect the pedicle screws with help of calculating the rod length and the rod radius. The system was tested in a test scenario where four pedicle screws were drilled into a wooden plate. The positions of the screws were adjusted to fit a curved and a straight rod. In the test scenario the application chose always the rod correctly

Despite the myriad new spinal instrumentation systems, scoliosis can rarely be fully corrected, especially when the curves are stiff. A novel superelastic nickel-titanium (nitinol) rod that maximises the ability to slowly correct spinal deformities by utilising the viscoelastic properties of the spine has been developed. This parallel, double-blinded, randomised controlled trial compared the safety and efficacy of these new rods to conventional titanium rods in 23 patients with adolescent idiopathic scoliosis. The superelastic nitinol rods were found to be safe, could gradually correct scoliosis curves, and ultimately resulted in better coronal and sagittal alignments compared to traditional rods. Despite the myriad new spinal instrumentation systems, scoliosis can rarely be fully corrected, especially when the curves are stiff. A novel superelastic nickel-titanium (nitinol) rod that maximises the ability to slowly correct spinal deformities by utilising the viscoelastic properties of the spine has been developed. This parallel, double-blinded, randomised controlled trial compared the safety and efficacy of these new rods to conventional titanium rods in 23 patients with adolescent idiopathic scoliosis. The superelastic nitinol rods were found to be safe, could gradually correct scoliosis curves, and ultimately resulted in better coronal and sagittal alignments compared to traditional rods

Aim. A retrospective study was undertaken to evaluate and compare the results of telescoping (group I) versus non-telescoping rods (group II) in the treatment of osteogenesis imperfecta. Materials and Methods. Thirty-three lower limb segments in ten patients were studied (14 segments in group I and 19 segments in group II). The surgical techniques of Sofield and Miller (1959) and Lang-Stevenson and Sharrard (1984) for rod insertion were used. All cases were assessed clinically regarding mobility status, growth and limb-length, refracture, and infection. They were also assessed radiologically regarding rod migration, bone outgrowing the rod, incorrect T-piece placement, breakage and bending of rods. Results. The average duration of follow-up was 86.2 months (range : 6 to 8 years). Mobility status and bone growth were better in group I than in group II patients. The overall implant related complication rate was 28.6% in group I in comparison to 68.4% in group II. Rod migration was twice more common in group II than in group I. Bone outgrowing the rod and breakage of rods with fracture was seen in group II only. The three-year survival rate for telescoping rods was 92.9% in contrast to 68.4% for non-telescoping rods. The reoperation rate was 7.2% in group I and 31.6% in group II. Conclusions. From this comparative study it was clear that the results were significantly better after Sheffield rods with regard to mobility status, longevity of the rod, and the frequency of complications requiring reoperations. Also most of the complications were related to the technique of rod insertion and the type of rod

Aim:. To evaluate the effect of a stiffer rod in normalising thoracic hypokyphosis in adolescent idiopathic scoliosis (AIS). Methods:. A retrospective review of AIS cases performed at our institution was carried out. In order to reduce variability, the analysis included only Lenke 1 cases which had all pedicle screw constructs, with similar constructs and implant density. Cases that underwent anterior release were excluded. All cases had the same implant (Expedium 5.5, Depuy-Synthes, Raynham, USA). The rod material differed in that some cases had 5.5 titanium, whilst others had 5.5 cobalt chrome. The preoperative and postoperative sagittal Cobb angle was measured. Results:. 35 patients met the inclusion criteria. 15 had titanium rods and 20 had cobalt chrome rods. The mean fulcrum correction index was similar between groups. The preoperative coronal and sagittal Cobb was similar between the two groups. There was no statistically significant difference in the postoperative sagittal Cobb between the two groups (ANOVA one way test). Discussion:. Despite the theoretical advantage of a stiffer construct improving the sagittal profile in AIS, this study identified no such benefit despite closely matching the two groups. All pedicle screw constructs do not seem to improve the sagittal profile despite the use of a stiffer rod. Conflict of interest:. Depuy-Synthes fund a fellow in this unit. Conflict Of Interest Statement: No conflict of interest

Purpose. Failure resulting from a recurrent infection in total knee arthroplasty (TKA) is a challenging problem. Knee arthrodesis is one treatment option, however fusion is not always successful, as there is huge bone defect. The authors reports a new arthrodesis technique that uses a bundle of flexible intramedullary rods and an antibiotic-loaded cement spacer. Methods. There were 13 cases of arthrodesis due to recurrent periprosthetic joint infection, which were performed by the first author (WS Cho) at Asan Medical Center in Seoul from 2005 to 2014. All previous prosthetic components were removed and cement was thoroughly excised using a small osteotome. Two stage operation was done in most of cases. After thorough debridement, antibiotics loaded cement was inserted in first stage, flexible intramedullary rods were inserted retrogradely in the femoral side with the knee in flexion under fluoroscopy guidance. After filling the femoral intramedullary canal, the rods were then driven back securely into the tibial medullary canal. We aimed for as much rod length as possible to maximize stability. After 6 weeks of first stage operation, the rods of the femoral and tibial sides were arranged such that they overlapped and interdigitated to maximize mechanical strength, maintain the limb length and keep the rotational alignment. The interdigitating rod ends were tightly fixed using two (or three) cerclage wires. Antibiotic-loaded cement was filled into the knee joint space so that the cement is fit to the irregular contour of the femur and tibia, which was resulted from the severe bone loss. Postoperatively, patients were allowed to weight bear as tolerated. Results. The procedure was successful in every cases with no evidence of rod or cement failure at least 1 year follow up. Also there was no recurrence of infection. Conclusion. Although this simple method was not for bony union, the authors could achieve stable knee joint without recurrence of infection

Introduction: Non union of the humerus in the ostoeportic bone is a great challenge for the orthopedic surgeon. The non weight bearing nature of this bone together with extreme osteoporosis seen in the elderly had rendered a high degree of failure in different modes of internal fixation of established humeral non union. Tantalum is a trabecullar metal with biomechanical properties similar to bone with a high modulus of elasticity and low rigidity. It is proved both in vitro and in vivo to induce excellent bone and vascular in growth and have been used successfully treating other application in orthopedics. We have introduced the tantalum rod for the treatment of humeral non union in the elderly. Patients and Methods: Six patients with humeral non-union were selected for tantalum rod implantations. All were above 60 years old. All patients had established non and 4 had failures after previous osteosynthesis. The surgical technique was exploration of the fracture site via a posterior or an anterolateral approach, debridement of the fracture site and intramedullary insertion of a 100 mm x 10 mm tantalum rod. No bone grafting was used. Ancillary fixation included a 4.5 broad DCP plate with screws drilled into both bone and rod or screws alone drilled into the bone and tantalum construct. Follow up period was up to one year. Results: All fractures united clinically and radiographicaly up to 3 months. All patients achieved satisfactory shoulder and elbow range of motion and regained functional activity. No infection or foreign body reaction was noted. Conclusion: Intramedullary tantalum rodding is a viable treatment option for the cases in both primary and secondary non union of the humeral shaft in osteoporotic bone

Introduction: Duchenne’s Muscular Dystrophy (DMD) is a progresssive sex linked recessive disorder predominantly involving skeletal muscle. Scoliosis is almost universal in patients with DMD. Surgical stabilisation carries significant risks and complications with per-operative mortality of < 6%. Cardiopulmonary complications along with severe intraoperative blood loss requiring massive nlood transfusion are the major cause of morbidity. Aim: To evaluate the efficacy of single rod fusion technique in reducing the peroperative and post operative complications especially blood loss, duration of surgery and progression of curve. Materials and Methods: Retrospective review- 32 patients with scoliosis secondary to DMD with an average age of 14 years (range, 11–18) underwent either single rod fusion technique (19 patients) using Isola rod system or Hartshill rectangle/double rod fusion technique (13 patients). Blood loss was measured directly from the peroperative suction and postoperative drainage, indirectly by weighing swabs. Vapour free hypotensive anaesthesia was used in all cases. Progression of curve was followed up in the outpatients. Results: The mean operative time was 130 minutes (range, 80–180) for the single rod fusion technique in comparison to 250 minutes (range, 170–300) for the Hartshill/Double rod technique. The average blood loss for the single rod fusion technique was reduced, 2.2 L (range 0.4–4) versus 3.1L (0.8–4). The mean follow up was 35 months (range, 5–72). The inpatient stay was 12 days (range, 6–23). Seven patients developed complications: 3 ileus, 2 respiratory tract infections, one patient had loosening and migration of the rod, which required revision under LA, and one patient developed a superficial wound infection, which resolved with intravenous antibiotics. Conclusion: In our experience, single rod stabilisation is a safe and quick method of correcting the DMD scoliotic spine, with less blood loss and complications compared to traditional methods

Purpose of study. The aim is to assess the use of non-fusion instrumentation “growth rods” in early onset scoliosis (EOS). Methods. A retrospective review of 12 consecutive patients who had undergone a growth rod procedure for EOS was performed. Six patients had neuromuscular scoliosis, 5 had juvenile idiopathic scoliosis while one had a congenital aetiology. Growth constructs were predominately constructed from modular commercially available sets using hooks, screws and connection blocks. One VEPTR was used in a severe kyphoscoliosis. Patients returned to theatre at 6 monthly intervals for a lengthening procedure. Patients were assessed with regards to age at presentation, age at surgery, indications for surgery, initial Cobb angle, post- operative Cobb angle, number of lengthening's done, instrumentation used, amount of spine growth achieved and complications. Results. The average age at presentation was 3 yrs 8 months (birth – 7 years 5 months). The average Cobb angle was 55 (38–90). Age at index surgery ranged from 2yrs 9 months to 8 years 2 months. The Cobb angle after the first procedure averaged 37 (range 20–90). The average lengthening over 51 lengthening procedures was 8 mm. Four patients have reached the end of the process and under gone a definitive fusion with pedicle screws and growth rods. Their final Cobb angle averaged 32 (26–48). Definitive surgery was performed earlier than planned in one patient due to repetitive rod breakage. Lengthening was abandoned in one patient whose implants became septic and required removal. Two patients required revision for superior construct failure. Conclusion. The growth rod procedure allows spinal deformity correction and control as well as on-going growth in trunk height. It is a labour intensive process with a significant incidence of complications. There is however very little choice in these patients due to concerns of fusion restricting pulmonary development. NO DISCLOSURES

High complication rates and technical difficulties of intramedullary fixation in children with osteogenesis imperfecta have prompted the modification of existing rod systems. The Sheffield telescoping intramedullary rod system was introduced to reduce the complications. It has a T-piece which is permanently fixed to prevent its separation and is expanded to reduce the migration. This study analyses the outcome of this rod system over a 12-year period in two specialist centres. Sixty rods were inserted in the lower limbs of 19 children with osteogenesis imperfecta. All children had multiple fractures of the bones before rod insertion. 39 rods were inserted into the femur, of which 3 were exchange and 4 revision procedures. 21 rods were inserted in the tibia. Eight children had intramedullary rodding of all the four lower limb long bones. The outcome was measured in terms of mobility status, incidence of refractures and rod-related complications. Our series demonstrates that there is significant reduction in refractures and improvement in the mobility status in children with osteogenesis imperfecta following intramedullary fixation. The frequent complication of T-piece separation and the need for reoperation has been overcome with the Sheffield modification of rod design. But the extracortical and metaphyseal migration of the rod continues to be a problem and further improvement in the design is desirable

Introduction:. One method of femoral head preservation following avascular necrosis (AVN) is core decompression and Tantalum Rod insertion. There is, however, a published failure rate of up to 32% at 4 years. The purpose of the present study was to document the clinical and radiological outcome following Total Hip Arthroplasty (THA) subsequent to failed Tantalum Rod insertion. Methods:. Twenty-five failed Tantalum Rod insertions subsequently requiring THA were identified from a prospectively updated database. Seventeen patients met minimum 2 year clinical and radiographic follow-up criteria. St. Michael's Hip (SMH) scores were compared to a matched cohort of patients with THA for AVN without prior Tantalum Rod insertion. Postoperative radiographs were reviewed assessing component alignment, linear wear (Dorr & Wan) and presence of tantalum residue within the joint space. Results:. Nine females and eight males underwent removal of a Tantalum Rod with subsequent THA between May 2005 and March 2010. The mean time between Tantalum Rod insertion and conversion to THA was 23 months (range 6–48) with a mean follow-up of 3.5 years (range 2–5). At each follow-up interval the mean SMH scores were comparable between the two groups (p = 0.445). Femoral stem alignment (p = 0.428) and acetabular cup inclination (p = 0.723) were comparable between groups. Articular tantalum residue was identified in 12 of 17 articulations (7 mild, 3 moderate, 2 severe). Linear wear rates were comparable between the tantalum group (0.07 mm/yr, range 0.01–0.40) and controls (0.07 mm/yr, range 0.02–0.21, p = 0.951). There was no evidence of catastrophic wear. Conclusion:. Tantalum rod conversion to THA in the young adult patient with AVN reveals no early catastrophic sequelae. In the short term, Tantalum Rod insertion does not demonstrate a deleterious effect on subsequent total joint replacement surgery. There is, however, a high rate of retained tantalum debris within the effective joint space with the procedure and thus there is an unknown risk of accelerated articular wear necessitating longer term study

Objective: To assess the results of using multisegmental fixation with single rod for the treatment of scoliotic deformities. Subjects: There were 120 patients treated in this study by single rod technique for scoliosis of different aetiologies. A group of 80 patients treated by double rod technique was used for comparison. Outcome measures: Scoliosis is a complex 3-dimensional and segmental deformity of the spine. Surgical treatment is indicated mainly for a growing child with increasing curve or in already severe deformity. Multisegmental 3 dimensional correction gave better correction and fixation than the older systems. But it increased significantly the cost and difficulty of the procedure.(. 1. ,. 2. ). Results: There were 120 patients (age: 3 to 19 years) treated by the single rod technique (group I) and compared with 80 patients treated by double rods (8 to 20 years) (group II). The preoperative curve for groups “I” ranged from 45 to 110 degrees with a mean of 61.4 degrees and 35 to 95 degrees with a mean of 54.7 degrees for group II. Group I curves showed flexibility range 21% to 78% with a mean of 47.8% and group II: 15% to 83% flexibility with a mean of 41.6%. The postoperative correction for group I ranged from 47.4% to 85.7% with a mean correction of 64.7% and for group II: 25% to 88.9% with a mean correction of 60.6%. Conclusion: The use of a single rod for multisegmental fixation for scoliotic deformities reduced the operative time, blood loss and cost. The implant was less bulky with increased surface area available for grafting which gives a better fusion mass. The correction obtained was comparable with double rod technique

In selected patients, knee arthrodesis is a well-recognised salvage procedure after infected total knee arthroplasty (TKA). Several procedures of arthrodesis have been introduced and should be adapted to the individual situation of the patient. In our center we regularly treat elderly patients after multiple revision operations; in 36% defects of the bone, soft tissue or the extensor mechanisms are present. In these cases we prefer arthrodesis to reimplantation. Because of the high rate of non-unions when using an external fixator, we perform arthrodesis by use of an intramedullary rod system. The objective of this study was to compare the results of different rod systems for knee arthrodesis after TKA infection. We reviewed the results of 3 rod systems in 34 patients: cementless system (Brehm; n=9), cement rod usually used in tumor patients (Mutars; n=7) and a regular cement rod system (Link; n=18). In the group of cementless rods we had to explantate 3 rods because of a relapse of the infection. This is most propably due to the technical design of the system: in poor soft tissue situation the tissue is compressed by the voluminary docking part which causes continuous necrosis. This problem can be avoided by an early tissue flap. Of the Mutars rod system we had to explantate 2 systems; one because of an infection, the other one due to telescoping, which can be avoided by use of a longer stem with the option to interlock. In the group of the Links system no revision was necessary. In our opinion, arthrodesis of the knee using a rod system is a satisfactory salvage procedure following an infected TKA, especially in elderly patients, and can provide reliable, painless extremity and satisfactory quality of life

Introduction. The change of position of the distal pedicle screws with growing rods in relation to vertebral bodies was described as pedicle screws migration. Pedicle screws are subjected to serial distractive forces pushing them down with every distraction; additionally there is continuous growth of the vertebral bodies during the treatment period. These two factors can affect the change of position of the pedicle screws in relation to the vertebrae during the use of growing rods. To our knowledge, this finding has never been studied, confirmed, or quantified. Methods. This is a retrospective review of the radiographs and operative notes of 23 consecutive cases of early-onset scoliosis treated with single growing rods. Age at index surgery ranged from 4 years 2 months to 8 years 9 months, and the number of distractions was four to 11 per patient. Measurements were done on post-index and latest follow-up true lateral radiographs. With optimum initial position of the screws in the pedicle, we calculated the distance between the upper end plate and the pedicle screw (distance superior to the screw [SS]) and the distance between the screw and lower-end plate (distance inferior to the screw [IS]). We expressed this ratio as a percentage: SS/IS x 100%. Any increase in this percentage with time denoted a more caudal position; however, a change in the percentage of less than 10% was regarded as insignificant. Results. Seven cases were excluded because of inadequate radiographs for measurements. Within the distal construct, measurements of the upper pedicle screw showed that six cases had a change of less than 10% and were regarded as insignificant. Ten cases had changes of more than 10%, five had changes between 10% and 50%, three between 50% and 100%, and two more than 100%. We identified two types of migration: the first within the pedicle with pedicle elongation, and the second through and distal to the pedicle. None of the patients had adverse clinical consequences related to this change. Conclusions. Change of screw position with time is a frequent occurrence in the distal pedicle screws with single growing rods. Two different types were identified. With growing rods some degree of distal pedicle screw migration in this paediatric age group may not be regarded as a complication of treatment

High complication rates and technical difficulties of intramedullary fixation in children with osteogenesis imperfecta has prompted the modification of existing rod systems. The Sheffield telescoping intramedullary road has T-piece which is permanently fixed and is expanded to reduce metaphyseal migration. This study analyses the outcome of this rod system over an 11 year period in two tertiary referral hospitals. 60 rods were inserted in the lower limbs of 19 children with osteogenesis imperfecta. All children had multiple fractures of the bones before rod insertion. 39 rods were inserted into femur, of which 3 were exchange and 4 revision procedures. 21 rods were inserted into tibia. Eight children had intramedullary rodding of both femur and tibia bilaterally. The outcome was measured in terms of incidence of refractures, mobility status, functional improvement and rod related complications. Our series demonstrates that there is significant reduction in refractures and improvement in the functional status of children with osteogenesis imperfecta following intramedullary fixation. The frequent complication of T-piece separation and the need for re-operation has been overcome with Sheffield modification of rod design. But the incidence of the rod, particularly at the proximal end of femur remains high and further improvement in the design is desirable

Purpose. Management of early onset scoliosis (EOS) can be very challenging. Surgery is indicated when orthotics and casting fail. Growing rod instrumentation has become an effective approach in controlling the deformity while allowing spinal growth. However, as with any surgery, there are known complications including failure of the proximal foundation. We analyzed our patients who underwent growing rod instrumentation and identified factors that were correlated with proximal foundation failure. Method. Our Pediatric Orthopaedic Spine Database (1992–2010) was reviewed for all patients who underwent growing rod instrumentation. Sixty-six patients with EOS were identified and divided into two groups: Group 1 – proximal foundation failure; and Group 2 – no incidents of proximal failure. The two groups were evaluated for differences in age, sex, weight, upper vertebral level in construct, presence of apical fusion, and pre-operative curve magnitude. Results. Eight of the 66 patients (12%) had proximal foundation failure. When comparing Group 1 and Group 2, only age, pre-operative kyphosis, and presence of apical fusion were significant differences between the two groups. The mean age of Group 1 patients was 4.9 years (range, 2.6 to 9.2 years) and the mean age of Group 2 patients was 7.5 years (range, 2.4 to 11.6 years) (p <0.006). The mean pre-operative kyphosis in Group 1 was 71 degrees compared to 50 degrees in Group 2 (p=0.049). Among the 12 patients with apical fusion, four (33%) had proximal failure. The presence of apical fusion was also a significant difference between the groups (p=0.003). Linear regression demonstrated a significant correlation between kyphosis and failure (k=0.005, p-value 0.016) as well as age and pullout (k=−0.005, p-value <0.01). Conclusion. Our data indicates that younger patients with increased pre-operative kyphosis are at a higher risk for proximal failure of their growing rods resulting in increased incidence of unplanned surgeries. The presence of an apical fusion was also correlated to increased failure rates possibly due to stress at the proximal construct. Further research is needed to determine if stronger constructs decrease the pullout rate in the at-risk patients