Femoral lengthening and deformity correction using the Fitbone motorized lengthening nail

Clinical compatibility of magnetic resonance imaging with magnetic intramedullary nails: a feasibility study

INTRODUCTION

The use of magnetic resonance imaging (MRI) with a magnetic intramedullary lengthening nail in place is contraindicated per the manufacturer due to the concern of implant activation and migration. A prior in vitro study did not confirm these complications only noting that a 3.0 T MRI weakened the internal magnet. Therefore, a retrospective analysis of patients who underwent an MRI with a magnetic nail in place was performed to determine if any adverse effects occurred in the clinical setting.

MATERIALS AND METHODS

A retrospective review of all patients who underwent an MRI with a magnetic lengthening nail in place was performed. The time spent being imaged in the MRI, number of times the patient entered the MRI suite, and the images obtained were recorded. Radiographs were performed before and after the MRI to determine if any hardware complications occurred. The patients were monitored for any adverse symptoms while they were in the suite.

RESULTS

A total of 12 patients with 13 nails were identified. Two patients underwent imaging with a 3.0 T MRI while the remaining 10 underwent imaging with a 1.5 T MRI. Each patient entered the MRI suite 2.1 times and spent an average of 84.7 min being imaged in the MRI (range 21-494). No patients noted any adverse symptoms related to the nail while in the suite and no hardware complications were identified.

CONCLUSION

MRI appears to be safe with a magnetic nail in place and did not result in any complications. Given the manufacturer's recommendations, informed consent should be obtained prior to an MRI being performed and a 3.0 T MRI should be avoided when possible if further activation of the nail is required.

Treatment of Angular Deformity and Limb Length Discrepancy With a Retrograde Femur Magnetic Intramedullary Nail: A Fixator-assisted, Blocking Screw Technique

BACKGROUND

Fixator-assisted nailing techniques that incorporate magnetic internal lengthening nails (MILNs) permit acute deformity correction and then gradual limb lengthening without needing postoperative external fixators.

PURPOSES

We sought to investigate the safety and accuracy of a fixator-assisted, blocking screw technique using retrograde MILNs for the correction of LLD and limb malalignment.

METHODS

Forty-one patients (13 patients with genu varum and 28 patients with genu valgum) with LLD treated with fixator-assisted, blocking screw retrograde MILN reconstruction were included. Preoperative LLD, mechanical axis deviation, and joint orientation angles were compared with values at the end of treatment, and bone healing indices were calculated. Perioperative complications were tracked.

RESULTS

Preoperatively, the mean mechanical lateral distal femoral angle of the varus cohort was 98 ± 12°, whereas the mean lateral distal femoral angle of the valgus cohort was 82±4°. Both cohorts had an average 3-cm LLD. 99% of the planned limb lengthening was achieved. Final LDFAs were 91 ± 6° and 89 ± 4° in the varus and valgus cohorts, respectively, and the limb mechanical axis angles were normalized. 10 patients underwent a total of 21 returns to the operating room. Most commonly, this involved percutaneous injection of bone marrow aspirate concentrate to bone regenerate exhibiting delayed union (6 patients).

CONCLUSIONS

The use of a retrograde MILN with a fixator-assisted, blocking screw technique is an effective means of acute deformity correction and gradual limb lengthening through minimal incisions. The accuracy of deformity correction relies on intraoperative execution of the appropriate nail start site, osteotomy location, and placement of blocking screws.

An update on the intramedullary implant in limb lengthening: A quinquennial review Part 1: The further influence of the intramedullary nail in limb lengthening

The goal of limb lengthening is to restore length to bone, safely stretch soft tissues and improve quality of life with minimal complications. Traditionally this was achieved with the use of external fixators, associated with complications related to pin site tethering and infections, joint stiffness and regenerate deformity and fracture following frame removal. The duration of treatment also impacts on patient mental health and well-being. In order to reduce external fixator time, intramedullary nails have been introduced as an adjunct, either at the initial surgery or after completion of lengthening. Complications related to the external fixator still remained and innovation has led to the popularisation of the intramedullary lengthening nail. The lengthening mechanism of the nail can be divided into those with ratchet systems and those driven by motors. In the ratchet group, patients are required to manually rotate their limb, with movement at the osteotomy site, in order to create forward movement. This was often associated with pain, and in some cases led to the requirement of general anaesthesia to enable rotation and continuation of lengthening. Further issues were reported related to lengthening rate control. Once the nail had lengthened sufficiently for the osteotomy to disengage, rapid lengthening termed a 'runaway' nail could occur. The nails were limited to forward movement, and once length was gained it could not be retracted, leading to poor regenerate formation and soft tissue contractures. The introduction of the Fitbone implant utilised a transcutaneous electrical conduit, powered by a high frequency electrical signal, enabling more control over the lengthening. The Precice intramedullary lengthening system is controlled by the use of an external device with two rotating neodymium magnets, which produce rotation of a third magnet in the nail. By altering the direction of the magnet rotation, the lengthening can be controlled both forwards and backwards with sub-millimetre precision. Following initial excellent outcomes published, the use of the lengthening intramedullary nail has become accepted by many as the implant of choice in limb lengthening. The aim of this article comes in two parts. The first to highlight the latest research and clinical results in the last five years using an intramedullary implant during limb lengthening, and the second to report the outcome in extended surgical indications and further implant innovation.

Combined lengthening for acquired leg length discrepancy: Are there advantages of hydroxyapatite-coated intramedullary nails?

INTRODUCTION

The aim of this multicenter prospective study was to analyze the outcomes of bone lengthening by external fixator associated with flexible intramedullary nailing (FIN) in acquired limb length discrepancy (LLD).

HYPOTHESIS

Hydroxyapatite (HA)-coated FIN enables reduced External Fixation Index in limb lengthening for acquired leg length discrepancies in comparison to non-HA-coated FIN.

MATERIAL AND METHODS

This study included 54 patients (mean age, 17.9 years) operated on for femoral or tibial lengthening by combined technique (External fixator with FIN) for acquired length discrepancy. Titanium non-HA-coated FIN (29 cases) or HA-coated FIN (25 cases) were used. The factors that might influence external fixation index, complication occurrence and outcome were analyzed: age, amount of lengthening, nail diameter, HA-coating vs. non-HA-coated nails.

RESULTS

The mean External Fixation Indexes (EFI) of groups compared for non-HA-coated nails vs. HA-coated nails were not significantly different: 26.5 d/cm and 27.2 d/cm in femoral lengthening and 34.9 d/cm and 31.7 d/cm in tibial lengthening. Positive correlation between the "nail diameter/inner distance between cortices at osteotomy site" ratio and EFI in tibial lengthening was revealed (p=0.034). The nail types and the "nail diameter/medullary canal diameter" ratio interact and have significant simultaneous effect on EFI in femoral lengthening (p=0.021).

DISCUSSION

The results of this study revealed no differences with regards to EFI using HA-coated or non-HA-coated titanium FIN in lengthening for acquired leg-length discrepancies. Combined technique allowed reduced EFI and avoided major complications. Both non-HA-nail and HA-coated nail lengthening provided good and excellent outcomes.

LEVEL OF EVIDENCE

III; (controlled trial without randomization) prospective comparative study.

Bone Lengthening with a Motorized Intramedullary Nail in 34 Patients with Posttraumatic Limb Length Discrepancies

The Fitbone® motorized nail system has been used to correct limb length discrepancies (LLD) for several years. This study focuses on its application in posttraumatic limb lengthening surgery, its outcome and challenges.

MATERIALS AND METHODS

A prospective, single center study was conducted between 2010 and 2019 in patients treated with motorized lengthening nails. The inclusion criteria were symptomatic LLD of 20 mm or more. An imaging analysis was done using TraumaCad® software (Brainlab AG, Munich, Germany) to compare frontal alignment angles and limb length discrepancy (LLD) on preoperative and latest follow-up radiographs of the lower limbs.

RESULTS

Thirty-four patients were included with a mean age of 28.8 ± 9.7 years, a mean follow-up of 27.8 ± 13 months and a mean hospital stay of 4.4 ± 1.7 days. The mean LLD was 44 ± 18 mm in 29 femoral and 32 ± 8 mm in 4 tibial cases, which was reduced to less than 10 mm in 25/34 (74%) patients. The mean healing index was 84.6 ± 62.5 days/cm for femurs and 92 ± 38.6 days/cm for tibias. The mean time to resume full weight-bearing without walking aids was 226 days ± 133. There was no significant difference between preoperative and final follow-up alignment angles and range of motion. The mechanical lateral distal femoral angle (mLDFA) was corrected in the subgroup of 10 LLD patients with varus deformity of the femur (preoperative 95.7° (±5.0) vs. postoperative 91.5° (±3.4), p = 0.008). According to Paley's classification, there were 14 problems, 10 obstacles and 2 complications.

DISCUSSION

Six instances of locking screw pull out, often requiring reoperation, raise the question of whether a more systematic use of blocking screws that provide greater stability might be indicated. Lack of compliance can lead to poor outcomes, patient selection in posttraumatic LLD patients is therefore important.

CONCLUSION

Limb lengthening with a motorized lengthening nail for posttraumatic LLD is a relatively safe and reliable procedure. Full patient compliance is crucial. In-depth knowledge of lengthening and deformity correction techniques is essential to prevent and manage complications.

[Research progress of intramedullary lengthening nail technology]

Objective

To review the research progress of intramedullary lengthening nail technology.

Methods

The foreign literature on the development history, types, advantages and disadvantages, indications and contraindications, complications, and effectiveness of intramedullary lengthening nail were reviewed and analyzed.

Results

The intramedullary lengthening nail system mainly includes mechanical type, electric motor drive type, and magnetic drive type. Compared with traditional external fixation and lengthening technology, the intramedullary lengthening nail technology has certain advantages in incidence of complications, bone healing, postoperative functional rehabilitation, incision aesthetics, convenience, and patient satisfaction. However, there are also shortcomings, such as pain, uncontrollable distraction rate, device failure, etc. In the clinical application of intramedullary lengthening nails for limb lengthening, the indications should be grasped reasonably, and the related complications should be prevented and treated.

Conclusion

Intramedullary lengthening nails provide a new option for limb lengthening, and the initial effectiveness is good. It is one of the development direction of limb lengthening technology.

Systematic review of complications with externally controlled motorized intramedullary bone lengthening nails (FITBONE and PRECICE) in 983 segments

Background and purpose - In recent years motorized intramedullary lengthening nails have become increasingly popular. Complications are heterogeneously reported in small case series and therefore we made a systematic review of complications occurring in lower limb lengthening with externally controlled motorized intramedullary bone lengthening nails.Methods - We performed a systematic search in PubMed, EMBASE, and the Cochrane Library with medical subject headings: Bone Nails, Bone Lengthening, and PRECICE and FITBONE nails. Complications were graded on severity and origin.Results - The search identified 952 articles; 116 were full text screened, and 41 were included in the final analysis. 983 segments were lengthened in 782 patients (age 8-74 years). The distribution of nails was: 214 FITBONE, 747 PRECICE, 22 either FITBONE or PRECICE. Indications for lengthening were: 208 congenital shortening, 305 acquired limb shortening, 111 short stature, 158 with unidentified etiology. We identified 332 complications (34% of segments): Type I (minimal intervention) in 11% of segments; Type II (substantial change in treatment plan) in 15% of segments; Type IIIA (failure to achieve goal) in 5% of segments; and Type IIIB (new pathology or permanent sequelae) in 3% of segments. Device and bone complications were the most frequent.Interpretation - The overall risk of complications was 1 complication for every 3 segments lengthened. In 1 of every 4 segments, complications had a major impact leading to substantial change in treatment, failure to achieve lengthening goal, introduction of a new pathology, or permanent sequelae. However, as no standardized reporting method for complications exists, the true complication rates might be different.

Combined antegrade femur lengthening and distal deformity correction: a case series

Background

Leg length discrepancy is often associated with distal femur angular deformities such as valgus or flexion. This study aims to report a new technique for simultaneous limb lengthening and acute distal femoral angular correction.

Methods

A retrospective chart review of patients undergoing a single procedure was conducted. Patients included had a single operation where they underwent distal femur osteotomy stabilized with a plate followed by antegrade nailing with a magnetically controlled intramedullary lengthening nail (PRECICE, Ellipse Technologies, Inc., Irvine, CA, USA) using a trochanteric entry.

Results

Seven femurs from 7 patients were included. The average age at operation was 13.6 years, and the leg length difference was 51 mm (range 30–105 mm). Associated deformities were valgus (4), knee flexion contracture (2), and both valgus and flexion contracture (1). Lengthening achieved was 43 mm (P = 0.0036), with a consolidation index of 27 days/cm and reliability of 0.87 (6/7). The 5 patients with angulation had an improvement of valgus from 12 to 4° (P = 0.006) and of the mechanical axis deviation from 34 to 3 mm (P = 0.0001). The range of motion also improved in the 3 patients with contractures. Preoperative gait disturbance, hip and knee pain, and functional scoliosis resolved after the limb deformities were corrected.

Conclusion

Combining a magnetic internal lengthening nail with a second distal osteotomy stabilized with a plate can successfully correct limb length and distal femur deformity acutely without altering the expected result of each procedure.

Leg Length Discrepancy- Treatment Indications and Strategies

BACKGROUND

Many people have leg-length discrepancies of greater or lesser severity. No evidence-based studies on the need for treatment are currently available.

METHODS

This review is based on publications retrieved by a selective search in the PubMed database, as well as on published recommendations from Germany and abroad and on the authors' own clinical experience.

RESULTS

If the two legs are of different lengths, this is generally because one leg is too short. It is debated whether leg-length discrepancy causes pain or long-term musculoskeletal disturbances. A direct connection to back pain is questionable, but a mildly elevated incidence of knee arthritis seems likely. The evidence base on the indications for treatment of leg-length discrepancy is poor; only informal consensus recommendations are available. There are a wide variety of conservative and surgical treatment options. The final extent of a leg-length discrepancy first noted during the growing years can be estimated with predictive algorithms to within 2 cm. The treatments that can be considered include a shoe insert, a high shoe, or an orthosis, surgically induced slowing of growth by blockade of the epiphyseal plates around the knee joint, or leg lengthening with osteotomy and subsequent distraction of the bone callus with fully implanted or external apparatus. Changes in leg length exert marked mechanical stress on the soft tissues. If the predicted leg-length discrepancy exceeds 5 cm, initial leg-lengthening treatment can already be considered during the patient's growing years.

CONCLUSION

It must be discussed with each patient individually whether the treatment should be conservative or surgical. The extent of the discrepancy is not the sole determining factor for the mode of treatment. The decision to treat is always elective.

Combined Technique for the Treatment of Infected Nonunions of the Distal Femur With Bone Loss: Short Supracondylar Nail-Augmented Acute Shortening/Lengthening

OBJECTIVE

To evaluate a combined technique for treating distal femoral bone defects after debridement of osteomyelitis, using an external fixator together with a short supracondylar nail.

DESIGN

Retrospective study.

SETTING

Single tertiary referral center.

METHODS

Between 2003 and 2018, 23 patients with a mean age of 37.2 years (26-56) underwent surgery with the same technique to manage postdebridement defects in the distal femur due to osteomyelitis. This involved acute shortening and intramedullary fixation of the defect site, together with relengthening from a proximal osteotomy using simultaneous external fixation. Radiographic union, range of motion of the hip and knee, external fixation time and external fixation index, and limb length discrepancy were assessed.

RESULTS

The mean follow-up was 51 months (18-192). Union was achieved in all patients without recurrence of infection during this follow-up period. The mean knee flexion was 120 degrees, and the mean extension deficit was 5 degrees at final follow-up. The mean limb length discrepancy improved from 5.5 cm (3-7) to 0.5 cm (0-2). The mean external fixation index was 29.2 d/cm (20-50), and the mean external fixation time was 115 days (90-150). Radiographic scores were excellent in 15 cases, good in 6, and fair in 2. Functional scores were excellent in 14 cases, good in 7, and fair in 2.

CONCLUSION

This combined strategy was an effective method for treating distal femoral segmental bone defects after debridement of osteomyelitis, with a high rate of union and acceptable complication rates.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Limb lengthening with one Precice nail over its capacity

The Precice nail is used to treat limb length discrepancies and has a low complication rate and a high patient satisfaction rate. While the Precice nail can be used for lengthening, unlike other lengthening nails, it can also be used for shortening. We report a 37-year-old female patient with a 14 cm limb length discrepancy that was treated with a new surgical technique using the shortening feature of the Precice nail. Following maximum possible lengthening using the nail and without waiting for union on the osteotomy line, the distal interlocking screws were removed, and the nail was shortened by external remote control with the help of the fixator. The distal interlocking screws were then reattached to continue lengthening. This surgical technique can be used safely and satisfactorily in cases with more shortness as we can correct the extremity length discrepancy using only one nail.

Complications and Effectiveness of Intramedullary Limb Lengthening: A Matched Pair Analysis of Two Different Lengthening Nails

Background

Intramedullary limb lengthening has become an accepted concept in reconstructive surgery, but as yet comparative clinical studies are missing. We compared the complications and effectiveness of two types of intramedullary limb lengthening devices (ISKD®; Fitbone®).

Materials and methods

In a retrospective series of 278 consecutive patients with internal limb lengthening, we found 17 matching pairs in terms of predefined matching parameters (group I with ISKD® and group II with Fitbone®). The surgeries were all performed with the same technique and managed with equivalent pre- and postoperative treatment protocols. The performance of the implants was evaluated using the distraction index and the weight-bearing index. Complications were rated according to Paley's classification for external lengthening.

Results

The distraction index in group I (ISKD®) was 0.99 mm/day (range 0.55-1.67) and in the group II (Fitbone®) 0.55 mm/day (range 0.14-0.92) (p value = 0.001). The mean weight-bearing index differed between group I and group II from 32.0 day/cm (range 16.4-64.0) to 51.6 day/cm (25.8-95.0) (p value = 0.001). There were 17 recorded incidents in group I and 19 in group II during lengthening.

Conclusion

Specific technical handicaps of the two systems, such as the so-called runaway of the ISKD® and backtracking of the Fitbone® nails seem to result in different distraction index and weight-bearing index. Further comparative studies might induce technical progress in intramedullary limb lengthening.

How to cite this article

Thaller PH, Frankenberg F, Degen N, et al. Complications and Effectiveness of Intramedullary Limb Lengthening: A Matched Pair Analysis of Two Different Lengthening Nails. Strategies Trauma Limb Reconstr 2020;15(1):7-12.

Limb lengthening and deformity correction with externally controlled motorized intramedullary nails: evaluation of 50 consecutive lengthenings

Background and purpose - Limb lengthening with an intramedullary motorized nail is a relatively new method. We investigated if lengthening nails are reliable constructs for limb lengthening and deformity correction in the femur and the tibia. Patients and methods - 50 lengthenings (34 Precice and 16 Fitbone devices) in 47 patients (mean age 23 years [11-61]) with ≥12 months follow-up are included in this study. 30 lengthenings were done due to congenital and 20 because of posttraumatic deformity (21 antegrade femora, 23 retrograde femora, 6 tibiae). Initial deformities included a mean shortening of 42 mm (25-90). In 15 patients, simultaneous axial correction was done using the retrograde nailing technique. Results - The planned amount of lengthening was achieved in all but 2 patients. 5 patients who underwent simultaneous axial correction showed minor residual deformity; unintentionally induced minor deformities were found in the frontal and sagittal plane. The consolidation index was 1.2 months/cm (0.6-2.5) in the femur and 2.5 months/cm (1.6-4.0) in the tibia. 2 femoral fractures occurred in retrograde femoral lengthenings after consolidation due to substantial trauma. There were 8 complications, all of which were correctable by surgery, with no permanent sequelae. Interpretation - Controlled acute axial correction of angular deformities and limb lengthening can be achieved by a motorized intramedullary nail. A thorough preoperative planning and intraoperative control of alignment are required to avoid residual and unintentionally induced deformity. In the femur relatively fast consolidation could be observed, whereas healing was slower in the tibia.

A new technique for correction of leg length discrepancies in combination with complex axis deformities of the lower limb using a lengthening nail and a locking plate

PURPOSE

Intramedullary lengthening nails are an accepted alternative to external fixators but are limited by anatomical preconditions. Therefore, to date the use of external fixators is sometimes inevitable. We report on a new technique for correction of combined limb length discrepancies and complex axis deformities using solely internal devices - a lengthening nail and a locking plate.

METHODS

Between October 2008 and November 2011 five patients (two femora, three tibias) with a mean leg length discrepancy of 36 mm (25 to 50) and a complex angular deformity were treated with a fully implantable motorized lengthening nail (Fitbone) and a locking plate. All patients were evaluated with regards to the pre- and postoperative leg length as well as axis alignment, functional outcome, lengthening indices and complications.

RESULTS

A successful leg length equalization was achieved in all cases and physiological joint orientation angles in all but one case. The mean distraction index was 1.2 mm/day, the maturation index 24 days/cm and the consolidation index 35 days/cm. The functional outcome was very encouraging in all cases with bilateral free range of movement. In total, two complications were observed, one nonunion and one loss of leg length after an early locking bolt removal in a peripheral hospital.

CONCLUSION

The combination of a fully implantable motorized lengthening nail and a locking plate is a valuable alternative option for treating selected cases with limb length discrepancies in combination with a complex deformity of the lower leg. However, the reported technique puts high demands on the preoperative planning, operative technique as well as surgeon's skills.

LEVEL OF EVIDENCE

IV (retrospective series).

Retrograde magnetic internal lengthening nail for acute femoral deformity correction and limb lengthening

INTRODUCTION

The Precice magnetic internal lengthening intramedullary nail is being used with great success in femur lengthening and deformity correction with a retrograde approach. Areas Covered: Our personal history of limb lengthening and the Precice nail will be reviewed. Several technical aspects are discussed including design updates, pre operative planning, selection of nail length, the use of blocking screws and intra operative temporary external fixation, osteotomy practice, post operative management, and cost analysis. Expert Commentary: The phenomenal bone healing ability for the retrograde Precice nail after femoral osteotomy for lengthening, even after acute deformity correction, is recognized throughout the growing body of scientific publications on this topic. The few failures that have occurred appear to be attributable to excessive loading of the femur and implant during a vulnerable time of bone healing. Further studies with more uniform outcome criteria need to be conducted to better standardize user's experiences. The higher one time cost of the implant is offset by the reduced number of surgeries needed when compared with the gold standard of lengthening-over-nail-technique, and we suspect that patients return to work sooner due to the ability to wear normal clothing and the reduction in pain throughout the entire lengthening process.

Limb lengthening and deformity correction of congenital and acquired deformities in children using the Taylor Spatial Frame

Background and purpose - Hexapod ring fixators such as the Taylor Spatial Frame (TSF) have shown good outcomes. However, there have only been a few studies comparing the use of TSF with various etiologies of the deformity. We compared the use of TSF in congenital and acquired deformities in children. Patients and methods - We reviewed 213 lower extremity reconstructive procedures with the TSF in 192 patients who were operated between October 2000 and October 2015. 128 procedures (67 proximal tibiae, 51 distal femora, and 10 distal tibiae) in 117 children (median age 14 (4-18) years; 59 girls) fulfilled the inclusion criteria. 89 procedures were done in children with congenital deformities (group C) and 39 were done in children with acquired deformities (group A). Outcome parameters were lengthening and alignment achieved, lengthening index, complications, and analysis of residual deformity in a subgroup of patients. Results - Mean lengthening achieved was 3.9 (1.0-7.0) cm in group C and 3.7 (1.0-8.0) cm in group A (p = 0.5). Deformity parameters were corrected to satisfaction in all but 3 patients, who needed further surgery for complete deformity correction. However, minor residual deformity was common in one-third of the patients. The mean lengthening index was 2.2 (0.8-10) months/cm in group C and 2.0 (0.8-6) months/cm in group A (p = 0.7). Isolated analysis of all tibial and femoral lengthenings showed similar lengthening indices between groups. Complication rates and the need for secondary surgery were much greater in the group with congenital deformities. Interpretation - The TSF is an excellent tool for the correction of complex deformities in children. There were similar lengthening indices in the 2 groups. However, congenital deformities showed a high rate of complications, and should therefore be addressed with care.

Lengthening and deformity correction about the knee using a magnetic internal lengthening nail

Introduction: The introduction of the internal lengthening nail (ILN) has changed the treatment of complex malalignment and shortening about the knee. Acute correction of the deformity and gradual lengthening through this osteotomy site has greatly simplified postoperative recovery. This manuscript is a review of the techniques that are currently being used in surgery.

Methods: The article is broken into two sections: distal femur osteotomy and tibia osteotomy. Each is addressed separately since they have different personalities. Also included are topics of particular interest that surface in ongoing conferences regarding the ILN. This work is a mix of expert opinion and best practice supported by peer reviewed publications on the topic.

Results: Most published series demonstrate excellent results with the ILN. Certain precautions are reiterated including avoiding mechanical failure, need for a percutaneous osteotomy, need for over-reaming, and the need for blocking screws.

Discussion: Current controversies will be brought to light and discussed. The reader should find this aspect particularly helpful in navigating this rapidly evolving field.

Use of a magnetic bone nail for lengthening of the femur and tibia

PURPOSE

To report our experience with the PRECICE nail for limb lengthening in 23 patients.

METHODS

Records of 15 female and 8 male patients aged 14 to 38 (mean, 23.6) years who underwent lengthening of the tibia (n=6) or femur (n=21) using the PRECICE nail were reviewed. The reasons for lengthening included trauma (n=7), hemihypertrophy (n=2), focal femoral deficiency (n=2), Ellis-van Creveld syndrome (n=1), hip septic arthritis sequelae (n=1), hereditary multiple exostosis (n=1), club foot sequela (n=1), congenital tibial pseudoarthrosis (n=1), fibrous dysplasia (n=1), idiopathic limb length discrepancy (n=7), and cosmetic (n=1).

RESULTS

The mean follow-up duration was 20.72 months. The mean lengthening was 48.20 mm, and the mean acute angular correction was 15.5º. The mean time to full weight-bearing was 5.15 months, and the mean consolidation index was 1.12 months/cm. The mean maturation index was 0.78 months/cm. One patient had nail breakage during the consolidation phase. The nail was replaced by an intramedullary nail until consolidation, after which another PRECICE nail was used to treat the residual shortening. Eight patients had over-lengthening and the nails were driven back to the desired length. No patient had infection.

CONCLUSION

The PRECICE nail is a viable option for lengthening of the femur and tibia.

Bone lengthening using the Fitbone(®) motorized intramedullary nail: The first experience in France

INTRODUCTION

Intramedullary limb lengthening systems include mechanical systems (the Albizzia nail and the ISKD nail) as well as motorized systems with the Fitbone(®) (Wittenstein, Igersheim, Germany) and the Precice(®) (Ellipse Technologies, Irvine, CA, USA) nails. We hypothesized that limb lengthening using the Fitbone(®) nail was reliable, reproducible, and comfortable for the patient.

PATIENTS AND METHODS

Between 2010 and 2013, a prospective single-center, single-operator (FA) study was conducted on patients who had undergone limb lengthening using the Fitbone(®) nail. The inclusion criteria were length discrepancy of the limbs equal to or greater than 25 mm or a short stature. The exclusion criteria were indications for cosmetic reasons and/or growth plates that were still open. The lengthening parameters were assessed postoperatively and at the last follow-up. Lengthening was considered achieved when the lengthening objective did not differ by more than 5 mm. All complications were noted. A statistical analysis was performed.

RESULTS

Twenty-six Fitbone(®) nails were implanted in 23 patients, in the femur in 15 cases and the tibia in 11 cases. The patients' mean age was 22.5 years (range: 15-53 years) and the mean follow-up was 3.4 years (range: 2-5.3 years). The limb lengthening targeted was obtained in 23 cases (88%) and the mean lengthening was 45.3±18 mm (range: 20-80 mm). The mean time to healing was 277±167 days (range: 86-638 days). The mean healing index was 73±57 days/cm for the femurs and 83.5±65 days/cm for the tibias. The mean complication rate was 15.4%.

DISCUSSION

This study emphasizes the good short-term results of this motorized intramedullary lengthening system. An evaluation over the longer term and with a higher number of patients remains necessary.

LEVEL OF EVIDENCE

IV: uncontrolled, prospective, continuous study.

Reamed Intramedullary Nailing has an Adverse Effect on Bone Regeneration During the Distraction Phase in Tibial Lengthening

BACKGROUND

The lengthening over nail (LON) technique has gained popularity because it enables shorter periods of external fixation, prevents deformities during lengthening, and reduces the risk of refracture after removal of the frame compared with the classic Ilizarov method. However, it is not clear if the violation of endosteal blood supply by reamed intramedullary nailing in the LON technique has a negative effect on bone regeneration or a positive effect by compensatory enhancement of periosteal circulation.

QUESTIONS/PURPOSES

The purposes of this study were to (1) compare the amount of regenerate bone during the distraction phase between two tibial lengthening techniques, the LON technique and lengthening and then nail (LATN) technique; and (2) compare callus shape at the end of the distraction phase using the classification of Li et al.

METHODS

This is a retrospective study comparing two treatment groups. Between September 2011 and June 2013, 120 patients underwent bilateral lower leg lengthening for familial short stature with either the LON or LATN technique, and were considered potentially eligible for inclusion in this retrospective, comparative study. During this same period, LON and LATN techniques were used in other patient populations, but all patients with familial short stature were considered for inclusion in the study. The specific contraindications for LON were diameter of the isthmus of the tibia narrower than 8 mm, length of the tibia shorter than 270 mm, and alignment of the lower extremity in valgus; in patients without these specific contraindications to LON, patients were offered either LATN or LON after counseling regarding the advantages and disadvantages of each procedure. The proposed advantages of LATN were shorter healing index and more stable internal fixation which might lead to earlier full weightbearing, whereas proposed disadvantages were a greater chance for deep infection, more deformity during lengthening, and subsequently longer external fixator period for correction. The groups were comparable in terms of age, sex distribution, smoking history, BMI, distraction rate, and final length gain. A longer period of external fixation was necessary in the LATN group, related to the relative stability of the segment without an intramedullary nail. Patients with tibial lengthening with the LON technique (31 patients, 62 tibiae) were compared with patients who had the LATN technique (89 patients, 178 tibiae) regarding the amount of bone regeneration at the anterior, posterior, medial, and lateral cortices of the lengthened area for each at 4, 8, and 12 weeks postoperatively using a pixel value ratio method. In addition, both groups were compared for callus shape and type at the end of the distraction phase (LON, 3.4 ± 0.06 months; LATN, 4.2 ± 0.05 months).

RESULTS

The pixel value ratios of the anterior, posterior, medial, and lateral cortices in the LON and LATN groups were 0.78 ± 0.06 and 0.74 ± 0.05; 0.82 ± 0.08 and 0.76 ± 0.05; 0.75 ± 0.06 and 0.72 ± 0.05; and 0.85 ± 0.06 and 0.82 ± 0.06, respectively at 4 weeks postoperatively(p value > 0.500 for all); 0.75 ± 0.05 and 0.77 ± 0.04; 0.78 ± 0.05 and 0.89 ± 0.04; 0.73 ± 0.05 and 0.82 ± 0.05; and 0.78 ± 0.06 and 0.88 ± 0.03, respectively at 8 weeks postoperatively (p value < 0.001 for the posterior, medial, and lateral cortices); 0.72 ± 0.05 and 0.76 ± 0.03; 0.75 ± 0.07 and 0.89 ± 0.03; 0.71 ± 0.05 and 0.82 ± 0.03; and 0.78 ± 0.06 and 0.91 ± 0.03, respectively at 12 weeks postoperatively (p value < 0.001 for the posterior, medial, and lateral cortices). A greater percentage of tibiae having the generally favored fusiform-shaped callus were seen with the LATN technique (61 of 178 segments) than with the LON technique (four of 62 segments; p < 0.001). There were no tibia showing the inferior concave, lateral, or central-shaped callus with the LATN technique, whereas eight tibiae (eight of 62 segments) showed concave-shaped callus with the LON technique (p < 0.001).

CONCLUSIONS

The potentially negative effect on callus regeneration from the concomitant use of reamed intramedullary nailing during the LON technique should not be overlooked. Based on our study, LATN may be a better choice for patients willing to accept the longer period of external fixation.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The importance of reaming the posterior femoral cortex before inserting lengthening nails and calculation of the amount of reaming

BACKGROUND

Lengthening nails have been used to correct limb length discrepancy caused by different etiologies, as well as for post-traumatic reasons. Two important lengthening nail-related complications are damage to the distraction mechanism and femoral fractures around the nail tip. As a result of the curved anatomy of the femur, straight nails impinge on the anterior cortex. Therefore, proper reshaping of the medullary canal to accommodate straight lengthening nails is crucial for the prevention of this problem. Reaming the dense posterior cortex is important when aiming to insert a lengthening nail without incurring anterior cortex nail tip impingement-related complications. Posterior femoral cortex over-reaming is a solution to this situation.

METHODS

Sixty patients received lengthening nails during 2008-2013, (ISKD, Fitbone, Precice). Posterior cortex rigid-reaming technique was used successfully in 45 retrograde femoral lengthening cases. The preoperatively planned posterior cortex amount was reamed until the impingement was overcome during the operation under fluoroscopic control for each case. Since the preoperative determination of posterior cortex reaming amount is time consuming and operator dependent, we evaluated the X-rays of the patients with computer software and conventional paper-based measurements. The effect of reaming the posterior cortical wall on the inclination of the nail tip to the anterior femoral cortex was detected with measurements on the preoperative and postoperative lateral femoral X-rays by using the CorelDRAW® Graphic Suite X6 software package (Corel, Inc., Ottawa, Ontario, Canada) software. On the same software, X-rays and the posterior reaming amount were also calculated.

RESULTS

The mean age of the patients was 27 years (11-42), while the mean lengthening was 5.9 cm (2-14). The mean consolidation index was 1.05 (0.75-1.62), and the mean follow-up period was 31 months (range, 18-45 months). The mean distance of the osteotomy site to the intercondylar notch of the femur was 81.2 mm (± 16.92). The mean displacement of the nail tip position was 15.42 mm (± 4.77) on the measurements on the postoperative X-rays after nail insertion compared to the preoperative simulations on the templates. The mean posterior cortex reaming thickness was 3.68 mm (± 1.02).

CONCLUSIONS

We derived a formula that allows the required amount of optimal posterior cortex reaming to be determined. No impingement-related complications or nail damage were observed.

Premature Consolidation with Resultant Implant Failure Using PRECICE Femoral Nail Lengthening: A Case Report

CASE

Posttraumatic limb-length discrepancies secondary to femoral malunion can be treated with a variety of external or internal lengthening systems. The PRECICE nail is an intramedullary device featuring an external remote control to activate a magnetically driven internal distraction mechanism. While this intramedullary system avoids the soft-tissue complications common to external lengthening, it has unique mechanisms of failure that are difficult to diagnose and that require a systematic approach.

CONCLUSION

In this case report, we describe a failure to lengthen with the PRECICE femoral nail and the subsequent steps taken to determine the root cause. We believe that this failure represents the first reported case of malfunction of the PRECICE femoral nail distraction mechanism since its 2013 redesign.