Lengthening With Monolateral External Fixation Versus Magnetically Motorized Intramedullary Nail in Congenital Femoral Deficiency

Antegrade femoral lengthening and simultaneous hemiepiphysiodesis for congenital femoral deficiency

Purpose

Congenital femoral deficiency is characterized by limb length discrepancy and genu valgum. Lengthening of the femur along its anatomic axis increases valgus alignment by medial knee translation. Pairing limb lengthening with simultaneous medial distal femoral hemiepiphysiodesis can simultaneously correct two limb deformities.

Methods

All skeletally immature patients with congenital femoral deficiency who underwent antegrade femoral lengthening and concomitant guided growth over a 4-year period were reviewed. Length and alignment data were quantified during lengthening, consolidation, and for 1 year after guided growth implants were removed or the patient reached skeletal maturity. Digital simulation was performed for all lengthenings to assess the mechanical alignment that would have been achieved had lengthening been performed without medial distal femoral hemiepiphysiodesis.

Results

Nine patients (five males, four females, mean age = 12.3 ± 1.9 years) underwent 10 antegrade intramedullary femoral lengthenings with simultaneous medial distal femoral hemiepiphysiodesis. All had improvement in valgus alignment (average improvement in mechanical axis deviation was 18 ± 11 mm, average change in limb alignment was 6 ± 5°). In simulated lengthenings without guided growth, all limbs would have experienced increased lateral mechanical axis deviation of 5 ± 3 mm. The hemiepiphysiodesis implant and lengthening device were explanted simultaneously in 7 of 10 lengthenings.

Conclusion

Simultaneous medial distal femoral hemiepiphysiodesis with antegrade femoral lengthening for ongenital femoral deficiency can minimize the number of surgical episodes for the skeletally immature patient. The lengthening device and guided growth construct can be removed simultaneously in a majority of cases, saving children one or two additional surgical treatments.

Evaluation of simultaneous bilateral femoral distraction osteogenesis with antegrade intramedullary lengthening nails in achondroplasia with rhizomelic short stature: a retrospective study of 15 patients with a minimum follow-up of 2 years

BACKGROUND AND PURPOSE

Bilateral femoral distraction osteogenesis in patients with achondroplasia is insufficiently reported. We aimed to perform the first study that exclusively analyzed simultaneous bilateral femoral distraction osteogenesis with motorized intramedullary lengthening nails via an antegrade approach in patients with achondroplasia focused on reliability, accuracy, precision, and the evolving complications.

PATIENTS AND METHODS

In this retrospective singlecenter study we analyzed patients with achondroplasia who underwent simultaneous bilateral femoral lengthening with antegrade intramedullary lengthening nails between October 2014 and April 2019. 15 patients (30 femoral segments) of median age 14 years (interquartile range [IQR] 12-15) were available for analysis. The median follow-up was 29 months (IQR 27-37) after nail implantation.

RESULTS

The median distraction length per segment was 49 mm (IQR 47-51) with a median distraction index of 1.0 mm/day (IQR 0.9-1.0), and a median consolidation index of 20 days/cm (IQR 17-23). Reliability of the lengthening nails was 97% and their calculated accuracy and precision were 96% and 95%, respectively. The most common complication was temporary restriction of knee range of motion during distraction in 10 of 30 of the lengthened segments. 1 patient was treated with 2 unplanned additional surgeries due to premature consolidation.

CONCLUSION

The method is reliable and accurate with few complications.

Lengthening Patients Previously Treated for Massive Lower Limb Reconstruction for Bone Tumors with the PRECICE 2 Nail

The objective of this study was to determine the efficacy of the PRECICE 2® nail in the treatment of lower limb length discrepancy in patients with a history of bone tumors. This study reports on outcomes, complications, and the safety of the PRECICE 2 limb lengthening nail in a cohort of pediatric patients with limb length discrepancy after surgery for bone tumors. Seventeen patients were treated with intramedullary magnetic nails. The average patient age at the time of surgery was 19 (range 11-32). The PRECICE 2 nail was used on 14 femurs (6 retrograde and 8 anterograde) and 3 tibias. The average consolidation time was 141 days (range 50-360) with a mean CI of 31 ± 12 days/cm. The ASAMI bone score showed 14 (82%) excellent results, 1 (6%) good result, and 2 (12%) poor results. The ASAMI functional score showed 13 (84.6%) excellent results, 3 (11.5%) good results, and 1 (3.8%) fair result. Patients treated with chemotherapy for bone cancer did not show any increase in distraction time or consolidation time. A total of 3 (17%) problems, 1 obstacle (5.5%), and 1 complication (5.5%) were encountered in our case series. The PRECICE 2 nail allows for effective and accurate lengthening preserving the range of motion in patients treated for bone tumors.

How Much Does Paediatric Femoral Lengthening Cost? A Cost Comparison between Magnetic Lengthening Nails and External Fixators

Aim

Motorised intramedullary lengthening nails are considered more expensive than external fixators for limb lengthening. This research aims to compare the cost of femoral lengthening in children using the PRECICE magnetic lengthening nail with external fixation.

Methods

Retrospective analysis of 50 children who underwent femoral lengthening. One group included patients who were treated with PRECICE lengthening nails, the other group included patients who had lengthening with external fixation. Each group included 25 patients aged between 11 and 17 years. The patients in both groups were matched for age. Cost analysis was performed following micro-costing and analysis of the used resources during the different phases of the treatments.

Results

Each group's mean patient age was 14.7 years. Lengthening nails were associated with longer operative times compared with external fixators, both for implantation and removal surgery (p-values of 0.007 and < 0.0001, respectively). Length of stay following the implantation surgery, frequency of radiographs and frequency of outpatient department appointments were all lower with lengthening nails. The overall cost of lengthening nails was £1393 more than external fixators, however, this difference was not statistically significant (p-value = 0.088).

Conclusion

The difference in the mean costs between femoral lengthening with lengthening nails versus external fixators was not statistically significant. Further research to review the effectiveness of the devices and the quality of life during the lengthening process is crucial for robust health economic evaluation.

How to cite this article

Hafez M, Nicolaou N, Offiah A, et al. How Much Does Paediatric Femoral Lengthening Cost? A Cost Comparison between Magnetic Lengthening Nails and External Fixators. Strategies Trauma Limb Reconstr 2023;18(1):16-20.

Trends and Practices in Limb Lengthening: An 11-year US Database Study

Aim

Over the past couple of decades, limb lengthening has evolved to encompass various implants and techniques. The purpose of this study was to (1) determine trends in the utilisation of various limb lengthening techniques for the femur and tibia in the United States, (2) determine trends in 1-year readmission rate following limb lengthening procedures and (3) to study the relationship of limb lengthening implant used and payment method used with the underlying diagnosis associated with limb shortening.

Materials and methods

Inpatient data were acquired using the Healthcare Cost and Utilisation Project (HCUP) database from 2005 to 2015 from seven states in the United States. Patients with an International Classification of Diseases (ICD)-9 code for limb lengthening of the femur or tibia were included. A total of 2,563 patients were included. Data were analysed using descriptive statistics, and chi-square test was used for comparison of subcategories. Linear regression analysis was used to examine trends over time.

Results

There was a strong linear trend towards increasing proportional use of internal lengthening of the femur from 2011 to 2015 (R2 = 0.99) with an increase of 10.2% per year. A similar trend towards increasing proportional use of internal lengthening of the tibia was seen from 2011 to 2015 (R2 = 0.87) with an increase of 4.9% per year. There was a moderate correlation showing a decrease in readmission rate of 1.07% per year from 2005 to 2015 (R2 = 0.55). Patients with short stature had increased use of internal lengthening and self-payment compared to patients with congenital, post-traumatic or other diagnoses.

Conclusion

There was increasing use of internal lengthening techniques from 2011 to 2015. Patients with short stature had higher use of internal lengthening technique and self-pay for payment method.

Clinical significance

Intramedullary devices have seen increasing use for limb lengthening procedures. Lengthening technique and payment method may differ by underlying diagnosis.

How to cite this article

Mittal A, Allahabadi S, Jayaram R, et al. Trends and Practices in Limb Lengthening: An 11-year US Database Study. Strategies Trauma Limb Reconstr 2023;18(1):21-31.

Improvement of the sagittal alignment of the spine in patients with achondroplasia after subtrochanteric femoral lengthening

PURPOSE

Limb-lengthening surgery to treat short stature has undergone great development in recent years with the use of intramedullary telescopic nails (TIMNs). A limited number of studies have explored the impact of lower limb lengthening on the spine, though their conclusions are not consistent. The aim of this research is to analyze changes in spinopelvic sagittal alignment and balance after lower limb lengthening in achondroplastic patients.

METHODS

Prospective study of patients with achondroplasia treated with bilateral femoral lengthening using an TIMN. Different sagittal spinal and pelvic plane parameters were measured on pre- and 2 year postoperative lateral spine radiographs: cervical lordosis, thoracic kyphosis, TL junction, lumbar lordosis (LL), pelvic incidence, pelvic tilt (PT), sacral slope (SS), and sagittal vertebral axis (SVA). Similarly, information regarding the elongation procedure was recorded.

RESULTS

A total of 10 patients were included (60% male), with a median age of 13.39 (2.32) years at first surgery and a median height of 120.3 (5.75) cm. A 10 cm elongation was performed in all patients through femoral subtrochanteric osteotomy. Statistically significant changes were found in LL -15.2 (7.4-17.9)º (p = 0.028), PT 11.7 (10.3-13.4)º (p = 0.018), SS - 11.6 (- 13.4 to - 10.4)º (p = 0.018) and |SVA| - 34.3 (- 39.10 to - 1.7) mm (p = 0.043).

CONCLUSION

Bilateral lower limb lengthening in patients with achondroplasia not only increases their size, but also improves sagittal spinopelvic alignment and balance. This may be due to retroversion of the pelvis and subsequent decrease in SS and LL as a result of the increased tightness of the gluteus maximus and hamstring muscles after femoral lengthening through subtrochanteric osteotomy.

LEVEL OF EVIDENCE

II, prospective comparative cohort study, before and after intervention.

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.

What Factors Correlate With Length of Stay and Readmission After Limb Lengthening Procedures? A Large-database Study

BACKGROUND

Indications and techniques for limb lengthening procedures have evolved over the past two decades. Although there are several case series reporting on the complications and efficacy of these techniques, limited data are available on length of stay and hospital readmission rates after these procedures.

QUESTIONS/PURPOSES

(1) What is the median length of stay after lower limb lengthening procedures, and is variability in patient demographics, preoperative diagnosis, and surgical technique associated with length of stay? (2) What is the 1-year readmission rate after lower limb lengthening procedures? (3) Is variability in patient demographics, preoperative diagnosis, and surgical technique associated with varying rates of hospital readmission?

METHODS

Patients who underwent femoral or tibial lengthening from 2005 to 2015 in seven states were identified using the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases. These databases include a large, diverse group of patients across a wide range of hospitals and socioeconomic backgrounds with inclusion of patients regardless of payer. Between 2005 and 2015, there were 3979 inpatient admissions that were identified as involving femoral and/or tibial lengthening procedures based on ICD-9 procedure codes; of those, 2% (97 of 3979) of the inpatient admissions were excluded from analysis because they had ICD-9 procedure codes for primary or revision hip or knee arthroplasty, and 10% (394 of 3979) of the inpatient admissions were excluded because they involved repeated admissions of patients with previous hospitalization data within the database. This yielded 3488 patients for analysis. The median (interquartile range) age of patients was 18 years (12 to 41), and 42% (1481 of 3488) of patients were women. A total of 49% (1705 of 3469) of patients were children (younger than 18 years), 19% (675 of 3469) were young adults (18 to 34 years), 24% (817 of 3469) were adults (35 to 59 years), and 8% (272 of 3469) were seniors (60 years and older). Length of stay and rates of readmission at 1 year after the lengthening procedure were calculated. Univariate analysis was performed to examine associations between age, race, payment method, underlying diagnosis, bone lengthened, and lengthening technique with length of stay and readmission rate. Factors found to be significantly associated with the outcome variables (p < 0.05) were further examined with a multivariate analyses.

RESULTS

Included patients had a median (IQR) length of hospital stay of 3 days (2 to 4). Given the poor explanatory power of the multivariate model for length of stay (R 2 = 0.03), no meaningful correlations could be drawn between age, race, underlying diagnosis, lengthening technique, and length of stay. The overall 1-year readmission rate was 35% (1237 of 3488). There were higher readmission rates among adult patients compared with pediatric patients (odds ratio 1.78 [95% confidence interval 1.46 to 2.18]; p < 0.001), patients with government insurance compared with commercial insurance (OR 1.28 [95% CI 1.05 to 1.54]; p = 0.01), and patients undergoing lengthening via external fixation (OR 1.61 [95% CI 1.29 to 2.02]; p < 0.001) or hybrid fixation (OR 1.81 [95% CI 1.38 to 2.37]; p < 0.001) compared with lengthening with internal fixation only.

CONCLUSION

When counseling patients who may be candidates for limb lengthening, providers should inform individual patients and their caretakers on the anticipated length of hospital stay and likelihood of hospital readmission based on our findings. Adult patients, those with government insurance, and patients undergoing hybrid or external fixator limb lengthening procedures should be advised that they are at greater risk for hospital readmission. The relationship of specific patient-related factors (such as severity of deformity or associated comorbidities) and treatment-related variables (such as amount of lengthening, compliance with physical therapy, or surgeon's experience) with clinical outcomes after lower limb lengthening and the burden of care associated with hospital readmission needs further study.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Feasibility of Computer-Aided Design in Limb Lengthening Surgery: Surgical Simulation and Guide Plates

Objective

To evaluate the feasibility and utility of computer‐aided design (CAD) in surgical treatment of leg length discrepancy (LLD) using monorail external fixators.

Methods

In the present case series, we retrospectively analyzed seven patients diagnosed with LLD who were surgically treated using a monorail external fixator between June 2018 and August 2020. A personalized surgical emulation of each patient was designed using CAD based on preoperative CT scans to measure limb parameters. Through reverse engineering, a surgical guide plate was then designed to assist with correcting the limb deformity. Patient general information and clinical history, leg length, mechanical lateral distal femoral angle (mLDFA), anatomical anterior distal tibial angle (aADTA), and surgical parameters were recorded during the perioperative period. Three months after external fixator removal, distraction‐consolidation time (DCT), healing index (HI), and lower extremity function score (LEFS) were calculated, and statistically analyzed by paired T‐test.

Results

The mean limb lengthening achieved was 6.41 ± 2.54 (range, 3.30–10.54) cm with either varus or valgus correction. The mean operative duration was 151 ± 41.87 (84–217) minutes and mean blood loss was 53.58 ± 22.51(25–87) ml. The mean distraction‐consolidation time was 3.67 ± 1.13 (range, 2.5–6.0) months and mean external fixator duration was 11 ± 2.45 (range, 8–14) months. The mean healing index (HI) was 18.11 ± 3.58 (range, 12.8–22.7) days/cm. Mean LEFS scores improved postoperatively from 32.17 ± 8.57 (range, 24–45) to 61.17 ± 6.68 (range, 50–67) with a significant difference (T = –14.26,P < 0.001).

Conclusions

Simultaneous length and angular correction can be achieved by incorporating CAD into the surgical treatment of patients with LLD, without compromising postoperative lower limb function. CAD demonstrates utility in the surgical treatment of LLD by improving the functionality of monorail external fixators.

Proximal Femoral Focal Deficiency/Congenital Femoral Deficiency: Evaluation and Management

Proximal focal femoral deficiency is a congenital transverse deficiency in which the femur is globally smaller with a typical proximal deformity at the hip that may include distal involvement of knees, leg, and feet. Congenital femoral deficiency (CFD) describes a broader spectrum of longitudinal deficiency inclusive of proximal focal femoral deficiency. CFD may also include lateral distal femoral hypoplasia, knee cruciate ligament deficiency, rotational instability, patellar dislocation, fibular hemimelia, ray absence, and contralateral limb involvement. Treatment intends to maximize function by limb equalization and deformity correction ranging from nonsurgical management using prosthetics to amputation and may include lengthening, shortening, and complex limb reconstruction. Management decisions depend on overall severity and the patient and family's preferences and priorities. Owing to its complexity, CFD is best treated by clinicians with considerable deformity treatment experience who can help guide decision making and embark on a treatment course that will maximize the functional outcome.

Two-stage Bone Lengthening With Reuse of a Single Intramedullary Telescopic Nail in Patients With Achondroplasia

BACKGROUND

Patients with achondroplasia may benefit from limb-lengthening surgery with telescopic intramedullary nails (TIMNs). However, the 5-cm maximum length of the nails used in these patients in their original design may be insufficient. The aim of this research is to analyze the outcomes and complications after reusing the same TIMN for a second consecutive 5-cm lengthening in patients with achondroplasia.

METHODS

Retrospective study of 26 bones (16 femurs and 10 tibias) in 9 patients with achondroplasia treated for bilateral 2-stage sequential lengthening reusing the same TIMN. On completion of a first stage of 5 cm of elongation, the nail was unlocked, retracted, and re-locked; a second stage of 5 cm of distraction followed. Radiologic and clinical parameters were measured preoperatively and postoperatively, and complications were recorded.

RESULTS

The median age of patients at first surgery was 13.54 (12.9 to 16.3) years; 55% were males. The median preoperative height was 121 (117.5 to 127) cm, and the median healing index was 18.12 (14.5 to 32.8) and 26.96 (23.3 to 31.6) d/cm, while time to weight bearing was 185.5 (144.8 to 308.5) and 242.5 (208.5 to 293.8) days for femurs and tibias, respectively. Major complications included 3 cases of moderate ankle equinus, 2 cases of hardware failure (failure to relengthen), 2 premature consolidations, 1 common peroneal neurapraxia, and 2 valgus deformities. Femoral procedures had significantly fewer complications than tibial interventions (7 vs. 15, P=0.03), whereas patients who underwent lengthening of both the femur and tibia did not have significantly higher complication rates (14 vs. 8, P=0.6).

CONCLUSIONS

This study analyzes lower-limb lengthening in a series of achondroplastic patients using TIMN with the novelty of nail reuse to relengthen the bone. The complication rate found is acceptable, among which, potential damage to the internal lengthening mechanism must be considered, though this complication can usually be easily resolved. Overall, nail reuse seems advisable in cases where bone elongation is indicated, and the size and design of the nail limits the extent of lengthening.

LEVEL OF EVIDENCE

Level III, retrospective comparative study, before and after intervention.

Femoral Lengthening in Children: A Comparison of Motorized Intramedullary Nailing Versus External Fixation Techniques

BACKGROUND

Femoral lengthening is associated with high complication rates often related to the type of surgical device used to perform the lengthening. The advent of intramedullary lengthening devices has promised a reduction in complications when compared with external fixation systems. The purpose of this study was to compare the clinical outcomes of femoral lengthening in children using a motorized intramedullary nail (Precice) versus an external fixation system (Taylor Spatial Frame-TSF; or Monolateral Rail System-MRS) at a single institution, single surgeon practice.

METHODS

This study is a retrospective comparison of pediatric patients who had previously undergone femoral lengthening (±deformity correction). Patients ages 8 to 18 years of age were included and grouped based on whether they had undergone Precice nailing or external fixation (TSF or MRS) between 2010 and 2019.

RESULTS

Twenty-seven patients (32 femurs) were included. Thirteen patients (15 femurs) had undergone Precice nailing and 14 patients (17 femurs) had undergone external fixation. The Precice group had significantly fewer problems, obstacles, and complications than the external fixation group, Precice 6.6%, 0%, 0%, respectively, and external fixation 47.1%, 29.4%, 0% respectively (P<0.01). Unplanned return to the operating room occurred in 4 cases, solely in the external fixation group. There were no differences in percentage of goal length achieved, Precice (mean 93.6%, range: 66.7% to 114.3%), external fixation (mean 96%, range: 76.9% to 117.5%) P=0.31 and total length achieved, Precice (mean: 44 mm, range: 20 to 80 mm), external fixation (mean: 46 mm, range: 10 to 70 mm) P=0.72. There was no difference in consolidation index, Precice (24.1 d/cm), external fixation (28.5 d/cm) P=0.36. The Precice group had a significantly shorter length of stay (mean: 2.2 d, range: 1 to 4 d), compared with the external fixation group (mean: 3.7 d, range: 2 to 8), P=0.01.

CONCLUSIONS

Femoral lengthening in children using a motorized intramedullary nail was associated with a markedly reduced rate of complications and shorter length of stay compared with external fixation.

LEVEL OF EVIDENCE

Level III.

Quality of life of children during distraction osteogenesis: a comparison between intramedullary magnetic lengthening nails and external fixators

Background

Distraction osteogenesis is a very demanding process. For decades, external fixation was the only reliable option for gradual deformity correction. Recently, intramedullary magnetic nails have gained popularity. This research aimed to assess the quality of life in children during gradual deformity correction using intramedullary lengthening nails compared to external fixation.

Method

Prospective analysis included children who had gradual lower limb deformity correction between 2017 and 2019. Group A included children who had magnetic lengthening nails; patients in group B had external fixation devices. Child health utility 9D (CHU- 9D) and EuroQol 5D youth (EQ- 5D-Y) were used to measure the quality of life at fixed points during the distraction osteogenesis process. The results were used to calculate the utility at each milestone and the overall quality of life adjusted years (QALYs).

Results

Thirty-four children were recruited, group A had 16 patients, whilst group B had 18 patients. The average ages were 16.0 years and 14.7 years for groups A and B, respectively. Group A patients reported significantly better utility compared to group B. This was observed during all stages of treatment (P = 0.00016). QALYs were better for group A (0.44) compared to group B (0.34) (P < 0.0001).

Conclusion

The quality of life was generally better in group A compared to group B. In most patients, the health utility progressively improved throughout treatment. In the same way, QALYs were better with the lengthening nails compared to external fixators. The magnetic lengthening devices (PRECICE nails) which were used in this research were recently relabelled to restrict their applications in children; this study was conducted before these restrictions.

What Are the Potential Benefits and Risks of Using Magnetically Driven Antegrade Intramedullary Lengthening Nails for Femoral Lengthening to Treat Leg Length Discrepancy?

BACKGROUND

Limb lengthening with magnetically driven intramedullary lengthening nails is a fast-developing field and represents an alternative to external fixators. Although previous studies have assessed the application of magnetically driven intramedullary lengthening nails, these studies have been heterogenous regarding the nailing approach, the bone treated, and the implant type; they also have analyzed relatively small patient groups at short follow-up durations.

QUESTIONS/PURPOSES

(1) Is femoral lengthening with magnetically driven antegrade intramedullary lengthening nails accurate and precise? (2) What are the most common complications of treatment? (3) What factors are associated with unplanned additional surgery?

METHODS

We retrospectively analyzed the longitudinally maintained database of our orthopaedic teaching hospital to identify all patients who underwent surgery for leg length discrepancy (LLD) between October 2014 and April 2019. In total, we surgically treated 323 patients for LLD of 2 cm or more. Of those 55% (177 of 323) were treated with distraction osteogenesis with magnetically driven intramedullary lengthening nails, 18% (59 of 323) with external fixation, and 27% (87 of 323) with epiphysiodesis around the knee. Based on that, 29% (93 of 323) of patients underwent unilateral femoral distraction osteogenesis with magnetically driven antegrade femoral lengthening nails and were eligible for analysis. No patient was excluded, and 3% (3 of 93) were lost before the minimum study follow-up of 2 years, leaving 97% (90 of 93) for analysis. Patients with a distal femoral deformity were treated via a retrograde femoral approach (10% [33 of 323]) or with external fixators (3% [10 of 323]) and were not included in this study. Distraction osteogenesis with magnetically driven intramedullary lengthening nails was not considered for patients with deep tissue infection, those with bone dimensions considered to be too small in relation to the available implants, and for patients younger than 8 years. This study included 90 patients (44 females, 43 left femora) treated for a median (interquartile range) preoperative LLD of 39 mm (32 to 52) at a median age of 15 years (14 to 17). The same limb lengthening system was applied in all patients. The median (IQR) follow-up was 35 months (24 to 78). Data were acquired through a chart review performed by someone not involved in the surgical care of the included patients. Data acquisition was supervised and curated by two of the involved surgeons. Accuracy was calculated as 100 - [(achieved distraction in mm - planned distraction in mm) / (planned distraction in mm) x 100] and precision as 100 - (relative standard deviation of accuracy). Treatment-associated complications were summarized descriptively and characterized as complications resulting in unplanned additional surgery or those not resulting in unplanned surgery. To analyze the risk of unplanned additional surgery by entity, we calculated odds ratios (ORs) comparing the incidence of unplanned additional surgery in the different entity cohorts with the idiopathic LLD cohort as a reference. By calculating ORs, we analyzed the risk for unplanned additional surgery depending on sex, age, surgery time, and previous lengthening. Due to the lack of long-term evidence about motorized lengthening nails remaining in situ and concerns about potential implant-related adverse effects, removal was routinely scheduled 1 year after consolidation. For implant removal, 92% (83 of 90) of patients underwent planned additional surgery, which was not recorded as an adverse event of the treatment. Ninety-seven percent (87 of 90) of patients completed lengthening with the implant remaining in situ until the end of distraction. The median (IQR) distraction length was 37 mm (30 to 45) with a median distraction index of 0.9 mm/day (0.7 to 1.0) and median consolidation index of 31 days/cm (25 to 42).

RESULTS

The calculated accuracy and precision were 94% and 90%, respectively. In total, 76% (68 of 90) of our patients experienced complications, which resulted in 20% (18 of 90) of patients undergoing unplanned additional surgery. The most common complication overall was adjustment of the distraction rate in 27% (24 of 90) of patients (faster: 16% [14 of 90]; slower: 11% [10 of 90]) and temporary restriction of knee motion, which occurred in 20% (18 of 90) of our patients and resolved in all patients who experienced it. The most serious complications were bacterial osteomyelitis and knee subluxation, which occurred in 3% (3 of 90) and 1% (1 of 90) of our patients, respectively. With the numbers available, we found only one factor associated with an increased likelihood of unplanned additional surgery: Patients with postinfectious LLD had higher odds of unplanned additional surgery than patients with idiopathic LLD (7% [1 of 15] versus 50% [3 of 6], OR 14.0 [95% CI 1.06 to 185.49]; p = 0.02). However, we caution readers this finding is fragile, and the confidence interval suggests that the effect size estimate is likely to be imprecise.

CONCLUSION

Femoral distraction osteogenesis with magnetically driven antegrade intramedullary lengthening nails appears to be an accurate and reliable treatment for femoral lengthening. However, depending on the etiology, a high risk of unplanned additional surgery should be anticipated, and a high proportion of patients will experience temporary joint stiffness. We recommend close orthopaedic follow-up and physiotherapy during treatment. This treatment of LLD can be considered alongside other nails, external fixators, and epiphysiodesis. Multicenter studies comparing this with other approaches are needed.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Maximizing length with precice nail: a novel technique

Intramedullary magnetic lengthening nails represents a marked advance in the process of limb lengthening, reducing the complications associated with other methods, and improving patient's comfort. However, one important limitation is its lengthening ability, especially when it comes to short bones. Previous reports have shown techniques that may allow further lengthening but at a cost of having to carry out repeated procedures, requiring the use of other devices, and submitting the patient to long-winded surgical procedures. This report presents a novel technique to achieve lengthening beyond the initial reach of the nail, in a simple and quick procedure, without the need of implanting any additional devices.

Comparison of Intramedullary Magnetic Nail, Monolateral External Distractor, and Spatial External Fixator in Femur Lengthening in Adolescents with Congenital Diseases

The aim of this study is to evaluate the course of the treatment and clinical and functional outcomes of femur lengthening in adolescents with congenital disorders by the application of different surgical methods. This retrospective study comprised 35 patients (39 procedures). A total of 11 patients underwent femur lengthening with the use of the intramedullary magnetic nail (IMN) Precise 2 (NuVasive, San Diego, CA, USA), 7 patients (11 procedures) with the use of the monolateral external distractor Modular Rail System (MRS) (Smith and Nephew, Memphis, TN, USA), and 17 with the use of the computer-assisted external fixator Taylor Spatial Frame (TSF) (Smith and Nephew, Memphis, TN, USA). The inclusion criteria were as follows: (1) congenital femoral length deficiency without any axial deformities and (2), independently of the finally applied treatment, the technical possibility of use of each of the analyzed methods. The distraction index did not differ significantly between the groups (p = 0.89). The median lengthening index was the lowest in the IMN group (24.3 d/cm; IQR 21.8–33.1) and statistically different in comparison to the MRS (44.2 d/cm; IQR 42–50.9; p < 0.001) and the TSF groups (48.4 d/cm; IQR 38.6–63.5; p < 0.001). Similarly, the consolidation index in the IMN group (12.9 d/cm; IQR 10.7–21.3) was statistically lower than that in the MRS (32.9 d/cm; IQR 30.2–37.6; p < 0.001) and the TSF (36.9 d/cm; IQR 26.6–51.5; p < 0.001) groups. This study indicates that IMN is a more valuable method of treatment for femoral length discrepancy without axial deformity than MRS and TSF in complication rate and indexes of lengthening and consolidation.

An engineering review of external fixators

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Mechanical stability plays a key role in the effectiveness of external fixators.

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Strength and stiffness are the main factors which contributes towards stability.

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Modified configurations of linear, circular and hybrid fixators are investigated.

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Light weight composite materials are gradually replacing traditional metallic alloys.

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Existing research gaps in further optimizing external fixators are identified.

External Fixators are a common technique used to treat a variety of issues related to bones, predominantly due to its non-intrusive nature and versatility in terms of form and materials. While it is mainly used to treat open fractures, its other uses include limb lengthening, deformity correction, bone grafting, compression of non-unions and stabilization of dislocations. Its earliest use dates as far back as 400 BCE and has undergone significant improvements, focusing on both customization and optimization. These two aspects highlight the significance of complementing the orthopaedic requirements with engineering knowledge and its applications. Hence, this review paper aims to conduct an examination of recent developments of external fixators with a special focus on its structure, the usage of materials and biomechanical investigations using experimental and numerical techniques. The paper presents the existing level of engineering knowledge with regards to these aspects and identifies research gaps, which can improve the quality of the commonly used external fixators.

Comparison of forces generated using compression plating versus a magnetic lengthening nail in a sawbones femur model

BACKGROUND

The purpose of this study is to compare compression generated by a Precice magnetic lengthening intramedullary nail and a 5.0 mm limited contact dynamic compression plate.

METHODS

Transverse osteotomy sites were created in the femoral shaft of ten Sawbones fourth generation composite femurs. Antegrade 10-degree trochanteric Precice nails and 8-hole, 5.0 mm plates were used for fixation. The plates were compressed by placing a neutral screw and three eccentrically drilled compression screws on alternating sides of the osteotomy. Average compression and distribution of compression were compared, and P-values <0.05 were considered statistically significant.

FINDINGS

The Precice nail generated an average of 2.38 megapascal across the osteotomy sites. The plate generated an average of 0.70 megapascal (P < 0.001) with the initial compression screw, 0.93 megapascal (P < 0.001) after the second screw, and 1.04 megapascal (p < 0.001) after the final screw. The distribution of compression was assessed utilizing a polar transformation to compare pressure values. We found that the distribution of compression was more circumferentially uniform in the Precice nail group (P = 0.046).

INTERPRETATION

This study demonstrates that an electromagnetic intramedullary device is capable of generating significantly higher compression, in a more uniform distribution, than a 5.0 mm limited contact dynamic compression plate in a Sawbones model. The results indicate that electromagnetic intramedullary nail systems may be an ideal alternative to compression plating for treatment of at-risk fractures, nonunions, delayed unions, and intercalary allograft reconstruction.

Femoral lengthening in young patients: An evidence-based comparison between motorized lengthening nails and external fixation

BACKGROUND

Femoral lengthening is a procedure of great importance in the treatment of congenital and acquired limb deficiencies. Technological advances have led to the latest designs of fully implantable motorized intramedullary lengthening nails. The use of these nails has increased over the last few years.

AIM

To review and critically appraise the literature comparing the outcome of femoral lengthening in children using intramedullary motorized lengthening nails to external fixation.

METHODS

Electronic databases (MEDLINE, CINAHL, EMBASE, Cochrane) were systematically searched in November 2019 for studies comparing the outcome of femoral lengthening in children using magnetic lengthening nails and external fixation. The outcomes included amount of gained length, healing index, complications and patient reported outcomes.

RESULTS

Of the 452 identified studies, only two (retrospective and non-randomized) met the inclusion criteria. A total of 91 femora were included. In both studies, the age of patients treated with nails ranged from 15 to 21 years compared to 9 to 15 years for patients in the external fixation group. Both devices achieved the target length. Prevalence of adverse events was less in the nail (60%-73%) than in the external fixation (81%-100%) group. None of the studies presented patient reported outcomes.

CONCLUSION

The clinical effectiveness of motorized nails is equivalent or superior to external fixation for femoral lengthening in young patients. The available literature is limited and does not provide evidence on patient quality of life or cost effectiveness of the interventions.

Risk factors of pin tract infection during bone transport using unilateral external fixator in the treatment of bone defects

Background

The bone transport using the unilateral external fixator, one of the Ilizarov techniques, is widely practiced in lower limb reconstructive surgery. Pin tract infection (PTI), one of most common complication, has become the important postoperative problems which plague clinicians gradually.

Methods

A group of 130 patients who received bone transport surgery for tibia or femur defects using the unilateral external fixation (Orthofix limb reconstruction system, Verona, Italy) and met the inclusion criteria were selected for the study from 2015 to 2019. Regular pin tract care was performed twice a day, and the conditions of the pin tract were evaluated by the same observer using clinical appearance criteria. The Saw’s classification of PTI was used to assess the condition around screws. After the data were significant by the T-test or Pearson’s Chi-square test analyzed, odds ratios were calculated using logistic regression tests to describe factors associated with the diagnosis of PTI.

Results

Ninety-one males and thirty-nine females with a mean age of 43 years (range 28–58 years) were included in this cohort. 7816 observations were documented from 12 to 36 months, and 58 cases (44.6%) of PTI (thirty-nine cases in grade 1, 17 cases in grade 2, and 2 cases in grade 3). The top five risk factors were agricultural work (OR 1.86, CI 0.94–2.39), non-urban living (OR 1.75, CI 1.24–3.26), male (OR 1.71, CI 1.02–2.31), smoking (OR 1.53, CI 0.76–1.89), and diabetes (OR 1.26, CI 1.12–2.64). No long-term sequelae were observed at the latest clinical visit.

Conclusion

Occupation, gender, living environment (non-urban), smoking, and diabetes were the top five significant risk factors for PTI in the period of bone transport using unilateral external fixation. Awareness of predictable risk factors of PTI is beneficial to avoid or early detect the severe complications which can affect the effectiveness.

Limb lengthening with PRECICE magnetic nail in pediatric patients: A systematic review

BACKGROUND

Limb lengthening techniques play an increasingly important role in the pediatric orthopedic field. The principles of the osteogenesis distraction bonded traditionally with external fixators; however, the recent deployment of fully implantable systems has been able to overcome severities related to external fixators. The PRECICE^® is an implantable limb lengthening intramedullary nail system that is remotely controlled and magnetically driven.

AIM

To review the current literature available on this matter in order to assess the PRECICE clinical and radiological outcomes and its possible complications in a population of pediatric patients undergoing limb lengthening.

METHODS

Only five studies met the inclusion criteria and were consequently included in the review for a total of 131 patients and 135 femurs. The clinical and radiological outcomes of interest were: the main lengthening obtained, the distraction rate, the period of time to full weight bearing, the consolidation index, and the Association for the Study and Application of Methods of Ilizarov score.

RESULTS

In conclusion, data collected from the articles under investigation were comparable with the exception of the consolidation index. Unfortunately, the study population was too small and the patients’ follow-up was too short to make definitive conclusions.

CONCLUSION

This review shows that the PRECICE Nail System is still a therapeutic challenge in limb lengthening for pediatric orthopedic surgeons; however, careful pre-operative planning and an accurate surgical technique could allow the correction of more complex deformities with a low rate of complications.

International recognition of the Ilizarov bone reconstruction techniques: Current practice and research (dedicated to 100th birthday of G. A. Ilizarov)

The Ilizarov method is one of the current methods used in bone reconstruction. It originated in the middle of the past century and comprises a number of bone reconstruction techniques executed with a ring external fixator developed by Ilizarov GA. Its main merits are viable new bone formation through distraction osteogenesis, high union rates and functional use of the limb throughout the course of treatment. The study of the phenomenon of distraction osteogenesis induced by tension stress with the Ilizarov apparatus was the impetus for advancement in bone reconstruction surgery. Since then, the original method has been used along with a number of its modifications developed due to emergence of new fixation devices and techniques of their application such as hexapod external fixators and motorized intramedullary lengthening nails. They gave rise to a relatively new orthopedic subspecialty termed “limb lengthening and reconstruction surgery”. Based on a comprehensive literature search, we summarized the recent clinical practice and research in bone reconstruction by the Ilizarov method with a special focus on its modification and recognition by the world orthopedic community. The international influence of the Ilizarov method was reviewed in regard to the origin country of the authors and journal’s rating. The Ilizarov method and other techniques based on distraction osteogenesis have been used in many countries and on all populated continents. It proves its international significance and confirms the greatest contribution of Ilizarov GA to bone reconstruction surgery.

Focal osteolysis and corrosion at the junction of Precice Stryde intramedullary lengthening device : preliminary clinical, radiological, and metallurgic analysis of 57 lengthened segments

Aims

This study aims to enhance understanding of clinical and radiological consequences and involved mechanisms that led to corrosion of the Precice Stryde (Stryde) intramedullary lengthening nail in the post market surveillance era of the device. Between 2018 and 2021 more than 2,000 Stryde nails have been implanted worldwide. However, the outcome of treatment with the Stryde system is insufficiently reported.

Methods

This is a retrospective single-centre study analyzing outcome of 57 consecutive lengthening procedures performed with the Stryde nail at the authors’ institution from February 2019 until November 2020. Macro- and microscopic metallographic analysis of four retrieved nails was conducted. To investigate observed corrosion at telescoping junction, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) were performed.

Results

Adjacent to the nail’s telescoping junction, osteolytic changes were observed in bi-planar radiographs of 20/57 segments (35%) after a mean of 9.5 months (95% confidence interval 7.2 to 11.9) after surgery. A total of 8/20 patients with osseous alterations (40%) reported rest and ambulation pain of the lengthened segment during consolidation.

So far, 24 Stryde nails were retrieved and in 20 (83%) macroscopic corrosion was observed at the nail’s telescoping junction. Before implant removal 11/20 radiographs (55%) of lengthened segments with these 20 nails revealed osteolysis. Implant retrieval analysis by means of SEM showed pitting and crevice corrosion. EDX detected chromium as the main metallic element of corrosion.

Conclusion

Patients are exposed to the risk of implant-related osteolysis of unclear short- and long-term clinical consequences. The authors advocate in favour of an early implant removal after osseous consolidation.

Cite this article: Bone Joint Res 2021;10(7):425–436.

Tibial lengthening using a retrograde magnetically driven intramedullary lengthening device in 10 patients with preexisting ankle and hindfoot fusion

Background and purpose - Motorized intramedullary lengthening nails (ILNs) have been developed as an alternative to external fixators for long bone lengthening. The antegrade approach represents the standard method for tibial ILN insertion. In patients with preexisting ankle and hindfoot fusion a retrograde approach provides an alternative technique that has not been evaluated so far. We report the outcome of this method in 10 patients. Patients and methods - This retrospective study included 10 patients (mean age 18 years [13-25]) with preexisting ankle and hindfoot fusion who underwent tibial lengthening with a retrograde ILN (PRECICE). The mean leg length discrepancy (LLD) was 58 mm (36-80). The underlying conditions were congenital (n = 9) and post tumor resection (n = 1). The main outcome measures were: ILN reliability, distraction achieved, distraction index (DIX), time to bone healing, consolidation index (CIX), complications, and functional results. Results - All patients achieved the goal of lengthening (mean 48 mm [26-80]). Average DIX was 0.6 mm/day (0.5-0.7) and mean CIX was 44 days/cm (26-60). Delayed consolidation occurred in 2 patients and healed after ILN dynamization or nail exchange with grafting. Toe contractures in 2 other patients were resolved with physiotherapy or tenotomy. Until last follow-up (mean 18 months [12-30]) no true complications were encountered, knee motion remained unaffected, and full osseous consolidation occurred in all patients. Interpretation - In patients with LLD and preexisting ankle and hindfoot fusion distal tibial lengthening using a retrograde ILN is a reliable alternative to the standard approach with equivalent bone healing potential and low complication rates leaving the knee unaffected.

Complications of Limb Lengthening With Motorized Intramedullary Nails

Intramedullary limb lengthening (LL) is now achievable through motorized intramedullary devices. While this technology mitigates some complications of external-fixation-based lengthening, many complications common to all lengthening procedures persist. New challenges and complications exclusive to this newer technology are also presented. The LL surgeon should be aware of and ready to respond to complications involving device malfunctions, poor local bony and soft-tissue biology, patient compliance, neurovascular compromise, joint instability, regenerate problems, and others. While technology will continue to evolve, study of and adherence to foundational principles of LL will minimize risks and optimize patient outcomes.

What's New in Pediatric Limb Lengthening and Deformity Correction?

Over the past 5 years, published literature regarding treatment of pediatric limb deformity and limb length discrepancy demonstrates much interest in better understanding, categorizing and treating these challenging problems. Many studies explore expanding and refining indications for traditional treatment methods like guided growth techniques. Other studies have evaluated the results of new techniques such as lengthening via mechanized intramedullary nails. Additionally, series comparing older and newer techniques such as lengthening with external devices versus mechanized nails are becoming increasingly available.

Post-retrieval functionality testing of PRECICE lengthening nails: The "Sleeper" nail concept

INTRODUCTION

PRECICE intramedullary magnetic lengthening nails, introduced in 2011, have changed the landscape of long bone limb lengthening. The implants have a stroke ranging from 5 to 8 cm, but it may be desirable to perform part of the lengthening at one treatment, allow bone healing, leave the implant in place, dormant, and then return one or more years later to re-lengthen with the same implant. We call this the "sleeper" nail concept. This strategy may be gentler for the joints and soft tissues. Would the nail mechanism still be functional one or more years later?

METHODS

We tested 102 intact, consecutively explanted nails. Using a "fast magnet," the male part was lengthened to 5 mm short of its maximum stroke capacity and retracted back to 35 mm (all nails start with the male part exposed 30 mm). The nails passed the test if the male part succeeded in lengthening to 5 mm short of the maximum stroke capacity and back to 35 mm (or only retract in case fully deployed at testing). During our testing, the nails were prevented from reaching their full capacity of lengthening/retraction to avoid jamming the gears. Failure was defined as the inability or partial ability to complete the process.

RESULTS

Eighty-six nails (84.3%) performed successfully according to our testing standard. When comparing successful and failed nails in terms of nail type, generation, diameter, length and in vivo interval, there was no statistical significance. Comparing both groups in terms of status at testing (fully deployed or not) showed statistical significance with 9 of the 16 failed nails fully deployed at testing (p < 0.001).

CONCLUSION

Dormant PRECICE nails can be reactivated for further lengthening. The results imply that full deployment may damage the mechanism, making future re-use by retracting and then re-lengthening unsuccessful. The candidate nails for this purpose should not have any signs of clear damage (bending or breakage) and should not have been fully deployed. However, surgeons and patients should be aware of the need for possible nail exchange if the "sleeper" nail fails to wake up.

LEVEL OF EVIDENCE

Level IV case series analysis of retrieved surgical implants.