External Remote Controller Research Articles

Is MAGEC X better than earlier designs of magnetically controlled growing rod: an explant study.

Determine the performance of MAGEC X rods through retrieval analysis and comparison with clinical data. A multicentre explant database was searched to identify cases using MAGEC X device. Clinical and surgical data was gathered prospectively. Prior to rod disassembly, rods underwent testing with an external remote controller to measure the force output. Eleven cases from 6 centres were identified. Implantation occurred at mean age 6.9years with mean duration of implantation 42months. Dual rod constructs were used in all but one case, providing 21 MAGEC X rods for explant analysis. Tissue metallosis was identified at revision surgery in 8/11 cases (73%). Of the 21 rods, 13/21 (62%) produced no force while 8/21 (38%) produced the force stated by the manufacturer. Endcap separation was seen in 5/21 (24%) rods. Where full disassembly was possible, 13/14 (93%) rods had an intact locking pin. Average rod growth was 18mm (range 2-45mm), equivalent to 5.1mm per year. Wear debris was found within 20/21 (95%) MAGEC X rods. Despite the substantial design changes with MAGEC X tissue metallosis was seen in most cases; most explanted MAGEC X rods had lengthened only partially and produced no force output. While the previous issue of locking pin fracture appears to have been mitigated with MAGEC X, there are multiple other and new failure modes, such as endcap separation. Overall MAGEC X appears to give little improvement over earlier iterations of the rod.

Development of Consensus-Based Best Practice Guidelines for the Perioperative and Postoperative Care of Pediatric Patients With Spinal Deformity and Programmable Implanted Devices.

Modified Delphi consensus study. To develop consensus-based best practices for the care of pediatric patients who have implanted programmable devices (IPDs) and require spinal deformity surgery. Implanted programmable devices (IPDs) are often present in patients with neuromuscular or syndromic scoliosis who require spine surgery. Guidelines for monitoring and interrogating these devices during the perioperative period are not available. A panel was assembled consisting of 25 experts (i.e., spinal deformity surgeons, neurosurgeons, neuroelectrophysiologists, cardiologists, and otolaryngologists). Initial postulates were based on a literature review and results from a prior survey. Postulates addressed the following IPDs: vagal nerve stimulators (VNS), programmable ventriculoperitoneal shunts (VPS), intrathecal baclofen pumps (ITBP), cardiac pacemakers and implantable cardioverter-defibrillators (ICD), deep brain stimulators (DBS), and cochlear implants. Cardiologist and otolaryngologist participants responded only to postulates on cardiac pacemakers or cochlear implants, respectively. Consensus was defined as ≥80% agreement, items that did not reach consensus were revised and included in subsequent rounds. A total of 3 survey rounds and 1 virtual meeting were conducted. Consensus was reached on 39 total postulates across 6 IPD types. Postulates addressed general spine surgery considerations, the use of intraoperative monitoring and cautery, the use of magnetically controlled growing rods (MCGRs), and the use of an external remote controller to lengthen MCGRs. Across IPD types, consensus for the final postulates ranged from 94.4% to 100%. Overall, experts agreed that MCGRs can be surgically inserted and lengthened in patients with a variety of IPDs and provided guidance for the use of intraoperative monitoring and cautery, which varied between IPD types. Spinal deformity correction surgery often benefits from the use of intraoperative monitoring, monopolar and bipolar cautery, and MCGRs. The final postulates from this study can inform the perioperative and postoperative practices of spinal deformity surgeons who treat patients with both scoliosis and IPDs. V-Expert opinion.

The magnetic field strength and the force distance dependency of the magnetically controlled growing rods used for early onset scoliosis

Magnetically controlled growing rods (MCGR’s) have revolutionized the treatment of early-onset scoliosis (EOS) because painless lengthenings can be done in the outpatient clinic without anesthesia. Untreated EOS leads to respiratory insufficiency and reduced life expectancy. However, MCGR’s have inherent complications like non-functioning of the lengthening mechanism. We quantify an important failure mechanism and give advice on how to avoid this complication. The magnetic field strength was measured on new/explanted rods at different distances between the external remote controller and the MCGR and likewise in patients before/after distractions. The magnetic field strength of the internal actuator decayed fast with increasing distances and plateaued at 25–30 mm approximating zero. Two new and 12 explanted MCGRs was used for the lab measurements of the elicited force using a forcemeter. At a distance of 25 mm, the force was reduced to approximately 40% (ca. 100 N) compared to zero distance (ca. 250 N), most so for explanted rods. This is used to point out the importance of minimizing the implantation depth to ensure proper functionality of the rod lengthening in clinical use for EOS patients. A distance of 25 mm from skin to MCGR should be considered a relative contraindication to clinical use in EOS patients.

Metallosis is commonly associated with magnetically controlled growing rods; results from an independent multicentre explant database.

Determine the incidence of metallosis around MAGEC rods. A multicentre explant database was searched to identify cases with complete intraoperative findings at rod removal. Surgeons removing rods detailed the presence or absence of tissue metallosis associated with rods. More recently surgeons measured the 'length' of tissue metallosis. Prior to rod disassembly, the majority underwent testing with an external remote controller (ERC). The impact of clinical and explant variables on metallosis was assessed. Sixty-six cases were identified. Mean age at insertion was 8.1 ± 2.3years with mean duration of implantation 37.6 ± 15.1months. Tissue metallosis was noted at revision surgery in 52/66 cases (79%). Metallosis was noted more commonly when rods were removed during fusion surgery than rod removal/exchange (97% vs. 58% (p = < 0.01)). The mass at insertion was greater in cases with metallosis (25.9 ± 7.8kg vs. 21.1 ± 6.2kg, p = 0.04). Length of tissue metallosis was reported for 45 rods, median 9cm (range 1-25). Metallosis was noted in 43/59 (73%) rods that produced no force and 22/30 (73%) rods that produced some force on ERC activation (p = 0.96). Wear debris was found within the actuator in all rods, and all but 3 rods had damaged O-rings. MAGEC rods are associated with tissue metallosis in the majority of cases. It is seen with functional rods as well as failed rods and appears related to wear debris within the actuator and high rates of O-ring failure. Until the implications of metal debris in children are known, we urge caution with the use of this implant.

Can You Stall a Baclofen Pump During a Magnetic Rod Lengthening?

Baclofen pumps are susceptible to magnetic forces because of the internal drug delivery mechanism. Magnetically controlled growing rods, sometimes implanted in the patients who have pumps, are lengthened using a device that generates a magnetic field. No previous study has determined if the external remote controller (ERC) can stall a baclofen pump during a rod lengthening. Two baclofen pumps were placed in proximity to the ERC while it generated a magnetic field. This process was repeated with variations in the distance between pump and ERC, speed (dose) of the pump, lengthening time, and position of the ERC relative to the pump. The presence or absence of a stall was recorded. To stall a baclofen pump, the ERC needed to be running consistently for at least 30 mm of lengthening. The pump would not stall if it was >1 cm away from the ERC. 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. As long as the baclofen pump is >1 cm away from the ERC, the pump will not stall, regardless of the length of time the ERC generates a magnetic field.

Does the external remote controller\u2019s reading correspond to the actual lengthening in magnetic-controlled growing rods?

PurposeMagnetic-controlled growing rods (MCGRs) are now routinely used in many centres to treat early-onset scoliosis (EOS). MCGR lengthening is done non-invasively by the external remote controller (ERC). Our experience suggests that there may be a discrepancy between the reported rod lengthening on the ERC and the actual rod lengthening. The aim of this study was to investigate this discrepancy.MethodsThis was a prospective series. Eleven patients who were already undergoing treatment for EOS using MCGRs were included in this study.ResultsOne hundred and ninety-two sets of ultrasound readings were obtained (96 episodes of rod lengthening on dual-rod constructs) and compared to their ERC readings. Only 15/192 (7.8%) readings were accurate; 27 readings (14.9%) were false positive; and 8 readings (4.2%) were an underestimation while 142 readings (74.0%) were an overestimation by the ERC. Average over-reporting by the ERC was 5.31 times of the actual/ultrasound reading. When comparing interval radiographs with lengthening obtained on ultrasound, there was a discrepancy with an average overestimation of 1.35 times with ultrasound in our series. There was a significant difference between ERC and USS (p = 0.01) and ERC and XR (p = 0.001). However, there was no significant difference between USS and XR (p > 0.99).ConclusionThe reading on the ERC does not equate to the actual rod lengthening. The authors would recommend that clinicians using the MCGR for the treatment of early-onset scoliosis include pre- and post-extension imaging (radiographs or ultrasound) to confirm extension lengths at each outpatient extension. In centres with ultrasound facilities, we would suggest that patients should have ultrasound to monitor each lengthening after distraction but also 6-month radiographs.Graphic abstractThese slides can be retrieved under Electronic Supplementary Material.

Spinal Lengthening With Magnetically Controlled Growing Rods: Data From the Largest Series of Explanted Devices.

Laboratory analysis of explanted MAGnetic Expansion Control (MAGEC) rods. The aim of this study was to identify the in vivo lengthening of MAGEC rods. Little data is available regarding the lengthening achieved by MAGEC rods. Cases were identified from the largest series of independently analyzed explanted MAGEC rods. The in vivo growth of rods was determined by the distance between the first "growth mark" and the actuator. The instrumented spinal lengthening was calculated for each construct. Constructs were considered functional if all rods could lengthen with external remote controller activation and no rods were "telescoping". Fifty-five MAGEC constructs (99 rods) from 53 patients treated at 10 centers were included. The mean age at insertion was 8.5 years with rods implanted a mean of 35 months. Sixty rods were suitable for analysis with mean lengthening 21.7 mm, 8.9 mm/year. Of these 60 rods, three were maximally distracted. Mean instrumented spinal lengthening for 38 suitable cases was 22.1 mm, 8.4 mm/year. This was positively correlated with the duration of implantation (r = 0.34, P = 0.04) but negatively with patient age at insertion (r = -0.35, P = 0.03). The rate of instrumented spinal lengthening was negatively correlated with duration of implantation (r = -0.47, P = 0.004). Of 55 constructs, 34 were nonfunctional at time of removal with nine functional and 12 indeterminate. Functional constructs had been implanted significantly less time (20.0 vs. 39.7 months, P < 0.001) and lengthened less than those nonfunctional (12.3 mm vs. 23.3 mm, P = 0.04). This multicenter explant study represents the largest cohort managed with MAGEC rods reported. Rods are very rarely removed having fully lengthened with mean instrumented spinal growth of 22 mm over the implant's life. This may be explained by a high rate of lengthening mechanism failure in received rods after around 3 years in vivo. Our findings question the effectiveness of the MAGEC system and mandate urgent comparative clinical studies. 4.

Standard and magnetically controlled growing rods for the treatment of early onset scoliosis.

Distraction based spinal instrumentation represents the most common and standard surgical technique to correct early onset scoliosis (EOS), i.e., scoliosis which has been diagnosed before the age of 10 years. Surgical treatment of EOS aims at controlling spinal deformity while maintaining spinal growth which is mandatory for the development of normal lung capacity. To achieve these goals the spinal instrumentation needs to be distracted to facilitate spinal growth during treatment. Distraction can be obtained by repeated surgical lengthenings (traditional growing rods, TGRs) or using magnetically controlled growing rods (MCGRs), which can be lengthened using external remote controller on an outpatient basis. The outcomes of TGR instrumentation for EOS are well described with follow-up until skeletal maturity: normal spinal growth can be maintained, 40-50% of the scoliosis can be corrected, but there is an over 50% risk of complications including deep wound infection, rod failure, and instrumentation pull-out. MCGR instrumentation may reduce the risk of wound related complications, provides similar deformity correction, but may not provide as much spinal growth. Metallosis around the instrumentation necessitates MCGR removal and definitive final instrumented fusion at the end of growth friendly management. Even severe EOS can be treated using distraction based spinal instrumentation.

High Correlation Between Achieved and Expected Distraction Using Magnetically Controlled Growth Rods (MCGR) With Rib to Pelvis Fixation in Pediatric Spine Deformity.

Magnetically controlled implant systems have been established to treat severe progressive spinal deformity in children. The purpose of this study was to evaluate (1) the ratio between achieved and expected distraction length, (2) the complication rate and its risk factors as well as (3) the correlation of the distraction length and the length of the spine. A total of 40 patients with an average follow-up of 34 (14 to 57) months were prospectively included in the study. Children underwent lengthening procedures every three months. The ratio between the distraction lengths was determined by comparing the measured distraction length of the rod on radiographs with the distraction length displayed on the external remote controller for the magnetically controlled growing rod (MCGR). Age, weight, height, and complications were repeatedly recorded. The analysis of 746 procedures showed the actual distraction to be 94.4% of the expected one. No difference between implants on the concave and convex spinal side was observed. The overall complication rate was 4.6% mainly because of failure of the implant or lack of implant extension, which was directly related to an increased BMI. There was also a strong correlation between achieved implant distraction length and gain in spinal length. Our study demonstrates a high ratio (0.94) between achieved and expected distraction length of magnetically controlled spinal rods. The complication rate was low (4.6%) and correlated to a high BMI. The correlation between the achieved implant distraction length and spinal length indicates the efficiency of the MCGR therapy. Therapeutic Level IV.

Can You Stall a Baclofen Pump During a Magnetic Rod Lengthening?

Introduction Baclofen pumps are susceptible to magnetic forces because of the internal drug delivery mechanism. Magnetically controlled growing rods, sometimes implanted in the patients who have pumps, are lengthened using a device that generates a magnetic field. No previous study has determined if the external remote controller (ERC) can stall a baclofen pump during a rod lengthening. Methods Two baclofen pumps were placed in proximity to the ERC while it generated a magnetic field. This process was repeated with variations in the distance between pump and ERC, speed (dose) of the pump, lengthening time, and position of the ERC relative to the pump. The presence or absence of a stall was recorded. Results To stall a baclofen pump, the ERC needed to be running consistently for at least 30 mm of lengthening. The pump would not stall if it was >1 cm away from the ERC. 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. Discussion As long as the baclofen pump is >1 cm away from the ERC, the pump will not stall, regardless of the length of time the ERC generates a magnetic field.

Magnetically Controlled Growing Rods: The Experience of Mechanical Failure from a Single Center Consecutive Series of 28 Children with a Minimum Follow-up of 2 Years.

Study DesignRetrospective observational study of a continuous series of 28 children.PurposeTo determine the mechanical failure rate in our cohort of children treated with magnetically controlled growth rods (MCGRs).Overview of LiteraturePrevious studies report a MCGR mechanical failure rate of 0%–75%.MethodsAll patients with MCGR implantation between 2012 and 2015 were examined and followed up for a minimum of 2 years. A retrospective evaluation of contemporaneously documented clinical findings was conducted, and radiographs were retrospectively examined for mechanical failure. The external remote controller (ERC)-specified length achieved in the clinic was compared to the length measured on subsequent radiographs.ResultsFourteen mechanical failures were identified in 28 children (50%) across a total of 52 rods (24 pairs and four single constructs). Mechanical failures were due to: failure to lengthen under general anesthesia (seven children), actuator pin fracture (four), rod fracture (one), foundation screw failure (one), and ran out of rod length (one). Of the 14 mechanical failures, six were treated with final fusion operations (reflecting limited further growth potential), and eight patients were treated with the intention for further lengthening. We therefore consider these eight patients to represent the true incidence of mechanical failure in our cohort (29%). The difference between the ERC length and radiographic length was found to be identical in 11% cases; 35% were overestimates, and 54% were underestimates. The median underestimate was 2.45 mm whereas the median overestimate was 3.1 mm per distraction episode. In total, 95% of all ERC distractions were within ±10 mm of the radiographic length achieved over a median of nine distraction episodes.ConclusionsOur series is the most comprehensive MCGR series published to date, and we present a mechanical failure rate of 29%. Clinicians should be mindful of the discrepancies between ERC length and radiographic measurements of rod length; other modalities may be more helpful in this regard.

A magnetically controlled lengthening nail: A prospective study of 31 individuals (The PRECICE™ intramedullary nail study)

Purpose: We studied 31 individuals whose femur or tibia was elongated with the PRECICE™ intramedullary lengthening nail in a protocol-controlled, multicentric, prospective series. Only skeletally mature individuals were included in the study. Materials and Methods: The protocol entailed 2-year follow-up after consolidation of the regenerate new bone in the distraction gap. Since the external remote controller (that powers the nail's internal rotating magnet) must be within a predetermined distance from the implant, body weight limitations applied to the individuals. Similarly, a history of active or prior bone infection in the involved limb segment, an offset medullary canal that could not be successfully reamed for the implant, an angular deformity that precluded insertion of a straight device, and any potential limitation on regenerate new bone formation (such as metabolic bone disease or vascular compromise) were causes for exclusion. The mean age ± standard deviation was 24.3 ± 15.0, and the median age was 18 years. There were 20 males and 11 females in the series, with 21 Caucasians, 5 Hispanics, and 5 African-American individuals. The mean body mass index was 24.2 ± 4.7. Twentythree (74.2%) cases involved the femur and 8 (25.8%) involved the tibia. Results: One participant died of medical causes during the study period, and one participant was lost to follow-up, but 29 of 29 participants followed at least to consolidation achieved union (100%) although one of these participants was treated with a supplementary cancellous bone graft and another participant was converted to trauma nail before consolidation, to permit full weight-bearing as a stimulus to regenerate consolidation. On an average, participants achieved 96.3% ± 23.2% of the preoperative target lengthening (3.5 cm; range 1.8–6.0 cm) over an average of 48.5 ± 15.6 days. The average time to full weightbearing (permitted when the regenerate was consolidated on three sides) was 141.1 ± 80.7 days. The knee joint, at consolidation, lost an average of 6.5° of flexion and 0.3° of extension. The ankle lost an average of 1.4° of dorsiflexion and 5.4° of plantar flexion. The hip joint lost, on average, 2° of flexion, and gained 1.6° of extension. There was one deep infection involving the implant, successfully treated with intravenous antibiotics and superficial debridement. Nearly 25.8% of the participants had pain issues during lengthening, often over prominent hardware. In one participant, the nail failed to elongate during lengthening at home and had to be exchanged. One interlock screw broke. The internal components separated during implant extraction in the one subject had his nail exchanged by a trauma nail. Only 17 participants exited the protocol by presenting to clinic for evaluation 2 years after consolidation. None experienced significant deterioration of outcome. Conclusion: The PRECICE™ IM nail is a well-tolerated, reliable, fully implantable limb lengthening device that will accurately elongate the femur or tibia in a variety of causes of limb length inequality, with a low implant failure rate, and few complications.

Recommendations for Lengthening of Magnetically Controlled Growing Rods in Children With Pacemakers.

Pacemakers are currently identified as a contraindication for the use of magnetic growth rods (MGRs). This arises from concern that magnetic fields generated by the MGR external remote controller (ERC) during lengthening procedures may induce pacemaker dysfunction. We investigated (1) whether MGR lengthening affects pacemaker function, and (2) if the magnetic field of a pacemaker affects MGR lengthening. MGRs were tested in conjunction with an magnetic resonance imaging-compatible pacemaker, which was connected to a virtual patient under continuous cardiac monitoring. To determine whether pacemaker function was affected during MGR lengthening, the electrocardiogram trace was monitored for arrhythmias, whereas an ERC was applied to lengthen the MGRs at varying distances from the pacemaker. To investigate if MGR lengthening was affected by the presence of a pacemaker, at the start and end of the experiment, the ability of the rods to fully elongate and shorten was tested to check for conservation of function. When the pacemaker was in normal mode, <16 cm away from the activated ERC during MGR lengthening, pacemaker function was affected by the ERC's magnetic forces. At this distance, prophylactically switching the pacemaker to tonic mode before lengthening prevented occurrence of inappropriate pacing discharges. No deleterious effect of the pacemaker's magnetic field on the MGR lengthening mechanism was identified. Magnetic resonance imaging-compatible pacemakers appear safe for concomitant use with MGRs, provided a pacemaker technician prophylactically switches the pacemaker to tonic function before outpatient lengthening procedures. This experiment was designed to provide the first safety information on MGR lengthening in children with pacemakers. Although currently a rare clinical scenario, with increasing use of MGRs, this clinical scenario may arise more frequently in the future.

Controlled Compression Nailing for At Risk Humeral Shaft Fractures.

Summary:Compression techniques seem to be the primary factor in determining the success of both plating and nailing techniques for the management of acute fractures and for delayed and nonunion management of these fractures. An intramedullary nail that can provide continual compression (like a plate) and mechanical manipulation of the callous throughout the course of treatment is an ideal device that provides all the advantages of plating and nailing and avoids the noted limitations of both. The UNYTE compression humeral nail is based on the PRECICE intramedullary limb lengthening system. This nail provides the ability to intraoperatively compress a humeral fracture immediately and continue compression in the outpatient setting with the external remote controller. This compression nail allows the surgeon to continually modulate stability through controlled compression and the ability to relengthen if necessary. The capacity to achieve constant compression at the fracture site has demonstrated rapid healing of the “at risk” humerus fracture in this series. We review the current indications for use of this device after its early introduction. In most cases, this was the failure of conservative brace management that presented with a progressive distraction gap and minimal callous formation or those fractures that could not be adequately controlled in the brace with malalignment greater than 20 degrees. The protocol for intraoperative compression using the external remote controller is detailed, as is the outpatient protocol for follow-up. The compression algorithm for progression to full fracture healing is also reviewed.

The role of the intramedullary implant in limb lengthening

Limb lengthening is now an accepted practice in orthopaedic surgery. The principles of distraction osteogenesis have become well established with the use of external fixators, utilizing both monolateral and ring fixators. Corticotomy technique, frame stability, lengthening rate and rhythm all contribute to the formation of bone regenerate and tissues. Complications are however common including pin-site infection, soft tissue tethering from the pins and wires resulting in pain, regenerate deformity from soft tissue forces or fracture following frame removal and patient intolerance of the frames during treatment.Surgical techniques have changed to try and minimise these complications. The use of intramedullary nails have been used in conjunction with an external fixator or inserted after lengthening has been achieved, to reduce fixator time and prevent regenerate deformity. Implant innovation has led to the production of intramedullary lengthening nails. The initial devices used ratchet mechanisms with rotation of the bone fragments to achieve lengthening (Bliskunov, Albizzia and ISKD). More accurate control of lengthening and a reduction in pain, resulting from the manual rotation of the leg required to achieve the ratchet progression, was achieved by the use of a transcutaneous electrical conduit powered by external high frequency electrical energy (Fitbone).The most recent implant uses an external remote controller which contains two neodymium magnets. These are placed over the nail on the skin and rotate which in turn rotates a third magnet within the intramedullary nail (Precice). This magnet rotation is converted by a motor to extend or retract the extendible rod. There are multiple nail sizes and lengths available, and early results have shown accurate control with few complications. With such promising outcomes the use of this lengthening intramedullary nail is now recommended as the implant of choice in femoral lengthening. This article is an historical account of the intramedullary device and the impact on limb lengthening.

Cost analysis of magnetically controlled growing rods compared with traditional growing rods for early-onset scoliosis in the US: an integrated health care delivery system perspective.

PurposeTraditional growing rod (TGR) for early-onset scoliosis (EOS) is effective but requires repeated invasive surgical lengthenings under general anesthesia. Magnetically controlled growing rod (MCGR) is lengthened noninvasively using a hand-held magnetic external remote controller in a physician office; however, the MCGR implant is expensive, and the cumulative cost savings have not been well studied. We compared direct medical costs of MCGR and TGR for EOS from the US integrated health care delivery system perspective. We hypothesized that over time, the MCGR implant cost will be offset by eliminating repeated TGR surgical lengthenings.MethodsFor both TGR and MCGR, the economic model estimated the cumulative costs for initial implantation, lengthenings, revisions due to device failure, surgical-site infections, device exchanges (at 3.8 years), and final fusion, over a 6-year episode of care. Model parameters were estimated from published literature, a multicenter EOS database of US institutions, and interviews. Costs were discounted at 3.0% annually and represent 2015 US dollars.ResultsOf 1,000 simulated patients over 6 years, MCGR was associated with an estimated 270 fewer deep surgical-site infections and 197 fewer revisions due to device failure compared with TGR. MCGR was projected to cost an additional $61 per patient over the 6-year episode of care compared with TGR. Sensitivity analyses indicated that the results were sensitive to changes in the percentage of MCGR dual rod use, months between TGR lengthenings, percentage of hospital inpatient (vs outpatient) TGR lengthenings, and MCGR implant cost.ConclusionCost neutrality of MCGR to TGR was achieved over the 6-year episode of care by eliminating repeated TGR surgical lengthenings. To our knowledge, this is the first cost analysis comparing MCGR to TGR – from the US provider perspective – which demonstrates the efficient provision of care with MCGR.

Evaluation of the first experience of intramedullary nail lengthening using PRECICE® in a South African limb lengthening and reconstruction unit

BACKGROUND: Limb lengthening is performed through distraction osteogenesis after osteotomy and has traditionally been performed using external fixation. The PRECICE® Limb Lengthening System has recently emerged as an alternative method to control distraction. In this study, the first experience of intramedullary nail lengthening using PRECICE®, in a South African limb lengthening and reconstruction unit, was evaluated in terms of the accuracy of distraction and the number of implant-related complications that were reported METHODS: A total of nine patients underwent the limb lengthening procedure in 11 limb segments. Distraction of the nail was initiated by ERC (external remote controller) around 10 days after surgery at a distraction rate of 1 mm/ day. The distraction was monitored every 2 weeks by clinical and radiographic examinations. Ongoing physiotherapy rehabilitation was performed until consolidation was achieved RESULTS: A mean target distraction length of 45.18 mm (15 to 65 mm range) was obtained over an average follow-up period of 266 days, with an accuracy of 103% ± 18%. All the distraction segments united. Two complications were reported that were successfully treated CONCLUSION: Limb lengthening using the PRECICE® nail system was found to have excellent accuracy of distraction, which is reproducible between different segments and indications. Acceptable complication rates were observed in this study

The MAGEC system for spinal lengthening in children with scoliosis: A NICE Medical Technology Guidance.

Scoliosis—structural lateral curvature of the spine—affects around four children per 1,000. The MAGEC system comprises a magnetically distractible spinal rod implant and an external remote controller, which lengthens the rod; this system avoids repeated surgical lengthening. Rod implants brace the spine internally and are lengthened as the child grows, preventing worsening of scoliosis and delaying the need for spinal fusion. The Medical Technologies Advisory Committee at the National Institute for Health and Care Excellence (NICE) selected the MAGEC system for evaluation in a NICE medical technologies guidance. Six studies were identified by the sponsor (Ellipse Technologies Inc.) as being relevant to the decision problem. Meta-analysis was used to compare the clinical evidence results with those of one conventional growth rod study, and equal efficacy of the two devices was concluded. The key weakness was selection of a single comparator study. The External Assessment Centre (EAC) identified 16 conventional growth rod studies and undertook meta-analyses of relevant outcomes. Its critique highlighted limitations around study heterogeneity and variations in baseline characteristics and follow-up duration, precluding the ability to draw firm conclusions. The sponsor constructed a de novo costing model showing that MAGEC rods generated cost savings of £9,946 per patient after 6 years, compared with conventional rods. The EAC critiqued and updated the model structure and inputs, calculating robust cost savings of £12,077 per patient with MAGEC rods compared with conventional rods over 6 years. The year of valuation was 2012. NICE issued a positive recommendation as supported by the evidence (Medical Technologies Guidance 18).

How precise is the PRECICE compared to the ISKD in intramedullary limb lengthening?

Background and purpose — The PRECICE intramedullary limb lengthening system uses a new technique with a magnetic rod and a motorized external remote controller (ERC) with rotational magnetic field. We evaluated the reliability and safety of the PRECICE system.Methods — We compared our preliminary results with PRECICE in 24 patients (26 nails) with the known difficulties in the use of mechanical lengthening devices such as the ISKD. We used the Paley classification for evaluation of problems, obstacles, and complications.Results — 2 nails were primarily without function, and 24/26 nails lengthened over the desired distance. Lengthening desired was 38 mm and lengthening obtained was 37 mm. There were 2 nail breakages, 1 in the welding seam and 1 because of a fall that occurred during consolidation. ERC usage was problematic mostly in patients with femoral lengthening. Adjustment of the ERC was necessary in 10 of 24 cases. 15 cases had implant-associated problems, obstacles were seen in 5 cases, and complications were seen in each of 4 cases.Interpretaion — The reliability of the PRECICE system is comparable to that of other intramedullary lengthening devices such as the ISKD. The motorized external remote controller and its application by the patients is a weak point of the system and needs strict supervision.