Complications of Limb Lengthening With Motorized Intramedullary Nails

Finite element analysis of distraction osteogenesis with a new extramedullary internal distractor

Distraction osteogenesis (DO) is a bone regenerative maneuver, which is conventionally done with external fixators and, more recently, with telescopic intramedullary nails. Despite the proven effectiveness, external approaches are intrusive to the patient's life while intramedullary nailing damages the growth plates, making them unsuitable for pediatric patients. An internal DO plate fixator (IDOPF) was developed for pediatric patients to address these limitations. The objective of this study was to test the hypothesis that the IDOPF can withstand a partial weight bearing scenario and create a favorable mechanical microenvironment at the osteotomy gap for bone regeneration as the device elongates. A finite element model of a surrogated long bone diaphysis osteotomy fixation by means of the IDOPF was created and subjected to axial compression, bending and torsion. As the osteotomy gap increased from 2 mm to 20 mm, under compression, The average axial interfragmentary strains decreased from 2.33% to 0.35%. Stress increased from 179 MPa to 281 MPa at the contact interfaces of the telescopic compartments, which exceeded the endurance limit of stainless steel (270 MPa) but was below its yield limit (415 MPa). These results demonstrate, that the IDOPF can withstand a partial load bearing scenario and provide a stable biomechanical environment conductive to bone healing. However, high contact stresses at the telescopic interfaces of the device are likely to cause wear, as is frequently reported in telescopic fixators. This study is a step towards refining the IDOPF design for clinical use.

Outpatient limb lengthening using magnetic intramedullary nails: A single Institution's experience

Introduction

The advantages of outpatient surgery have been shown in other orthopedic subspecialities to be a means of driving down costs and reducing the average length of hospital stay. However, there is a scarcity of literature examining the utility of a specific, hospital-based facility performing such procedures for limb lengthening. Considering this, we aimed to investigate surgical factors, patient characteristics, and the incidence of outpatient postoperative complications for patients undergoing surgery and subsequent distraction osteogenesis utilizing the Precice® nail, a state-of-the-art magnetic intramedullary nail (MILN).

Methods

We performed a retrospective review of medical records pertaining to outpatient limb lengthening procedures occurring between January 2012 and September 2023 at a single institution, as performed by three surgeons. Variables of interest included baseline demographics, type of anesthesia, operative bone, laterality, preoperative diagnosis, osteotomy level, procedure performed, prosthesis, point of entry, nail diameter/length, goal length, goal achieved, postoperative complications, and elective nail removal.

Results

The cohort comprised 20 limbs, with an average age at index surgery of 24.8 (SD 7.96). There were no complications related to the outpatient nature of the procedure. Five of the 20 limbs had postoperative complications, including deep vein thrombosis (DVT), screw backout, and nail breakage.

Conclusion

Our initial investigation of outpatient limb lengthening at a specific, hospital-based facility demonstrated favorable postoperative outcomes for those patients undergoing limb lengthening procedures with an MILN. The field would certainly benefit from future research assessing outcomes of pediatric surgeries in the outpatient setting on a larger scale, as well as across hospital systems, the country, and globally. With the proven advances and benefits of MILNs, prioritizing examination of their efficacy in an outpatient population is imperative. Furthermore, the success of outpatient procedures in other orthopedic subspecialities, such as total joint arthroplasty, is a logical, driving precedent for this rationale.

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.

Tibial Bone Transport With a Single Implant All-Internal Bone Transport Nail

SUMMARY

A single implant all-internal magnet-driven bone transport nail (BTN-NuVasive Specialized Orthopaedics Inc) has recently been introduced as a treatment method for segmental tibial bone defects. This innovation provides promise in the management of segmental bone defects because it negates numerous complications associated with circular external fixation and the need for multiple implants when considering hybrid plate-assisted bone segment transport constructs. Given the novelty of the BTN, description of the surgical application and patient outcome measures are scarce in the current literature. To date, we have treated 4 patients with an average age of 27 years (range 19-44 years) using the BTN for segmental tibial defects ranging from 50 to 128 mm. We have accumulated data over an average follow-up of 18.07 months (range 12.96-25.13 months), demonstrating good patient tolerance of the device. Three patients successfully completed their treatment course with a calculated average bone healing index of 41.4 days/cm (range 31.41-54.82 days/cm). One patient was noted to experience an asymptomatic docking site nonunion requiring subsequent surgery for nonunion repair. Implant-associated complications included symptomatic implant, axial malalignment, docking site nonunion, and external remote control technical malfunction. Injury-related complications were encountered and noted to include: superficial infection, wound dehiscence, peroneal tendonitis, and joint rigidity. In this study, the authors present a case series using this implant to date and discuss our experiences with the BTN with reference to clinical indications, tibial bone preparation, BTN implantation, transport protocol, docking site procedure, and clinical/radiographic outcomes.

No osteolysis at the telescopic junction of 128 FITBONE lengthening nails

BACKGROUND

Motorized lengthening nails are the treatment standard for bone lengthening of the lower limbs. However, bony changes namely osteolysis and periosteal hypertrophy have been described after certain type of magnetically driven lengthening nails. The aim of this study was to estimate the proportion rate of radiological bone abnormalities of Fitbone TAA femoral or tibial lengthening nails with a minimum follow-up time of 1 year.

HYPOTHESIS

The bone surrounding the telescopic junction of Fitbone lengthening nails does not exhibit osteolysis or periosteal reactions. The bone surrounding the locking screws exhibits cortical hypertrophy.

PATIENTS AND METHODS

Single-centre retrospective case series of patients treated with a Fitbone nails with a minimum follow-up of 1 year after implantation. Standard orthogonal radiographs were obtained postoperatively, weekly during the distraction phase, and then monthly for 6 months, and before removal of the equipment. We looked for bone abnormalities at the telescoping junction of the nail and at the locking screws before removal.

RESULTS

In total, 101 patients (58 males, 43 females) with a mean age of 21 years (range: 11.8-53.5) had 128 (101 femoral and 27 tibial) limb lengthening nails implanted between 2010 and 2021. The mean follow-up period was 925 days (range: 371-3587). The mean lengthening was 4.7cm (range: 1.5-8.0). No bones exhibited focal osteolysis or periosteal reactions at the telescopic junction of the lengthening nail. Cortical hypertrophy at the locking screws was observed in significantly more Fitbone nails than previously reported, i.e., 101/128 (79%).

DISCUSSION

Neither focal osteolysis, nor periosteal reactions were observed at the bone surrounding the telescopic junction of 128 Fitbone lengthening nails. Cortical hypertrophy around the single diaphyseal locking screw was observed in 101/128 (79%) of the cases. These absences of osteolytic changes after long term observation are reassuring for both surgeons and patients alike.

LEVEL OF EVIDENCE

IV.

Motorized Plate Lengthening of the Femur in Children: A Preliminary Report

BACKGROUND

Limb lengthening by distraction osteogenesis can be performed with motorized internal devices, but intramedullary implants risk avascular necrosis of the femoral head in young children. A method of internal limb lengthening using a motorized expandable plate has been developed and preliminary results are presented.

METHODS

Seven skeletally immature patients (ages 2.7 to 9.7 y) with congenital femoral deficiencies underwent femoral lengthening with the use of a magnetic expandable plate. Surgical details, lengthening parameters, Limb Lengthening and Reconstruction Society-Angular deformity, Infection, Motion index, and complications were reviewed and classified according to the modified Clavien-Dindo system.

RESULTS

An average lengthening was 4.1 cm (range, 3.3 to 4.4 cm) comprising 18% of initial femoral segment length (range, 14% to 21%). The average lengthening phase was 50.2 days (range, 40 to 57 d) and weight-bearing was initiated at an average of 13 weeks from surgery (range, 8 to 18 wk). Limb deformities and length discrepancies were of moderate complexity, with an Limb Lengthening and Reconstruction Society-Angular deformity, Infection, Motion score of 6.57 (range, 6 to 7). Complication rates were comparable to previously reported methods of femoral lengthening. One patient underwent reoperation for patellar instability and 1 patient experienced radiographic hip subluxation which was observed. Small magnitude varus was observed in regenerate in 3 of 7 cases, none requiring treatment. Preoperative planning consisted of careful localization of the corticotomy site, acute deformity correction at the lengthening site in 3 cases, and implant orientation.

CONCLUSIONS

Limb lengthening with motorized internal plates is feasible for young children with congenital femoral deficiency for whom intramedullary lengthening is unsafe or if external fixation is to be avoided. However, the fundamental principles of distraction osteogenesis and risks of lengthening for congenital discrepancies remain unchanged. Specific considerations herein include: careful planning of implant length and positioning, adjacent joint protection with adjunctive means, and mitigating deformity of the regenerate during distraction.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

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.

Experiences in the Use of Motorized Intramedullary Nails after Complex Injuries to the Extremities

The treatment of complex injuries of the extremities after comminuted fractures or non-unions is a challenging area in the field of trauma surgery. Internal, motorized implants nowadays enable a patient-oriented and progressive treatment of these cases. The present article aims to present modern treatment strategies of complex injuries of the extremities, support the use of novel, motorized intramedullary nails and provide experiences for the handling with lengthening nails or transport nails. For this purpose, the preoperative planning including selection of patients, presentation of internal lengthening and transport systems and the most important factors during preparation of the surgery are described. Moreover, critical steps during the implantation of motorized nails and also during potential follow-up interventions are highlighted and the postoperative protocol including precise recommendations for the transport und consolidation phase are provided. Finally, the experiences are illustrated by presentation of the four different cases. The use of internal, motorized implants represents the latest step in the treatment of complex injuries of the extremities. These implants improve the quality of life and the authors recommend its use. However, these implants require a high expertise and adaption of established treatment protocols in these challenging trauma cases. Follow-up analyses with a considerably large number of cases are necessary and the research on implants to solve persisting problems in the area of complex injuries of the extremities has to be pursued intensively.

The STRYDE limb lengthening nail is susceptible to mechanically assisted crevice corrosion: an analysis of 23 retrieved implants

Background and purpose - We noted several adverse events in patients in whom the first version of the STRYDE limb-lengthening nail (NuVasive Specialized Orthopaedics, San Diego, CA) had been implanted. Pain, osteolysis, periosteal reactions, and cortical hypertrophy at the nail junction were noted. Here, we present the analysis of 23 retrieved STRYDE implants.Materials and methods - We undertook visual inspection of the retrieved nails and screws, mechanical evaluation of the junction, micro-CT analyses, microscopic inspection of the bushing, screws, screw holes, and separated parts of the implants. Positive material identification (PMI) and energy-dispersive X-ray spectroscopy (EDS) were used to analyze the chemical composition. The hardness of the material was also investigated.Results - 20/23 retrieved nails had visible signs of corrosion, i.e., discoloration at the telescopic junction. Micro-CT verified corrosion attacks in 12/12 scanned bushings. Corrosion, predominantly mechanically assisted crevice corrosion, was observed at the locking screws and screw holes in 20/23 nails. Biological material inside the nail was observed in addition to oozing from the junction of 2 nails during hardware removal, which was experimentally reproducible. Notably, the mechanical construction of the bushing changed from PRECICE P2 to STRYDE nails.Interpretation - STRYDE nails are not hermetically sealed, and liquid can pass the bushing. Biodur 108 itself is corrosion resistant; however, mechanically assisted crevice corrosion of the bushing, locking screws, and screw holes may be aggravated due to manufacturing aiming for increased strength and hardness of the alloy.Observing several adverse events, we recently published a nationwide cross-sectional analysis of all 30 STRYDE limb- lengthening nails (NuVasive, Specialized Orthopedics, San Diego, CA) that were implanted in Denmark (Rölfing et al. 2021a). 27/30 STRYDE nails have now been removed and we present data from metallurgical analysis of 23 of the retrieved implants.

Radiographs of 366 removed limb-lengthening nails reveal differences in bone abnormalities between different nail types

AIMS

Limb-lengthening nails have largely replaced external fixation in limb-lengthening and reconstructive surgery. However, the adverse events and high prevalence of radiological changes recently noted with the STRYDE lengthening nail have raised concerns about the use of internal lengthening nails. The aim of this study was to compare the prevalence of radiological bone abnormalities between STRYDE, PRECICE, and FITBONE nails prior to nail removal.

METHODS

This was a retrospective case series from three centres. Patients were included if they had either of the three limb-lengthening nails (STYDE, PRECICE, or FITBONE) removed. Standard orthogonal radiographs immediately prior to nail removal were examined for bone abnormalities at the junction of the telescoping nail parts.

RESULTS

In total, 306 patients (168 male, 138 female) had 366 limb-lengthening nails removed. The mean time from nail insertion to radiological evaluation was 434 days (36 to 3,015). Overall, 77% of STRYDE nails (20/26) had bone abnormalities at the interface compared with only 2% of FITBONE (4/242) and 1% of PRECICE nails (1/98; p < 0.001). Focal osteolysis in conjunction with periosteal reaction at the telescoping interface was only observed in STRYDE nails.

CONCLUSION

Bone abnormalities at the interface of telescoping nail parts were seen in the majority of STRYDE nails, but only very rarely with FITBONE or PRECICE nails. We conclude that the low prevalence of radiological changes at the junctional interface of 242 FITBONE and 98 PRECICE nails at the time of nail removal does not warrant clinical concerns. Cite this article: Bone Joint J 2021;103-B(11):1731-1735.

Pain, osteolysis, and periosteal reaction are associated with the STRYDE limb lengthening nail: a nationwide cross-sectional study

Background and purpose - Observing serious adverse events during treatment with the Precice Stryde bone lengthening nail (NuVasive, San Diego, CA, USA), we conducted a nationwide cross-sectional study to report the prevalence of adverse events from all 30 bone segments in 27 patients treated in Denmark.Patients and methods - Radiographs of all bone segments were evaluated regarding radiographic changes in February 2021. We determined the number of bone segments with late onset of pain and/or radiographically confirmed osteolysis, periosteal reaction, or cortical hypertrophy in the junctional area of the nail.Results - In 30 bone segments of 27 patients we observed radiographic changes in 21/30 segments of 20/27 patients, i.e., 19/30 osteolysis, 12/30 periosteal reaction (most often multi-layered), and 12/30 cortical hypertrophy in the area of the junction between the telescoping nail parts. Late onset of pain was a prominent feature in 8 patients. This is likely to be a prodrome to the bony changes. Discoloration (potential corrosion) at the nail interface was observed in multiple removed nails. 15/30 nails were still at risk of developing complications, i.e., were not yet removed.Interpretation - All Stryde nails should be monitored at regular intervals until removal. Onset of pain at late stages of limb lengthening, i.e., consolidation of the regenerate, should warrant immediate radiographic examination regarding osteolysis, periosteal reaction, and cortical hypertrophy, which may be associated with discoloration (potential corrosion) of the nail. We recommend removal of Stryde implants as early as possible after consolidation of the regenerate.

Lengthening the Lower Extremities of Children with Ollier's and Maffucci's Enchondromatosis Using Implantable Lengthening Nails

There are multiple forms of enchondromatosis with Ollier's and Maffucci's being the most prevalent types. Limb length discrepancy is a common problem in patients with Ollier's and Maffucci's enchondromatosis. There are multiple reports about lengthening bones in patients with enchondromatosis using external fixators. However, there are no case series regarding the use of implantable lengthening technology. The purpose of this paper is to describe our experience with implantable nail lengthening in patients with enchondromatosis. A retrospective chart and radiographic review of patients with enchondromatosis who underwent implantable nail limb lengthening was performed. Seven patients with 14 bony segments were reviewed. A total of 11/14 lengthenings were completed without difficulty. There were no issues in terms of fixation location in patients with Ollier's disease. One patient with Maffucci's syndrome experienced migration of the nail during two lengthenings due to a combination of intralesional fixation and preconsolidation. One patient with Ollier's disease developed a knee extension contracture requiring manipulation under anesthesia. No other complications were recorded. The use of implantable nail lengthening to resolve limb length discrepancies in patients with Ollier's disease appears to be safe and effective.

Dissociation of a Femoral Intramedullary Magnetic Lengthening Nail During Routine Hardware Removal: A Case Report

CASE

A 15-year-old boy with a right femur length discrepancy secondary to infection underwent hardware removal 1-year status-post right femur osteotomy with placement of an antegrade intramedullary magnetic lengthening nail after successful lengthening of 4.2 cm. During hardware removal, dissociation between the proximal (outer) and distal (inner) components of the device was observed. The distal component was removed using an endoscopic pituitary rongeur after considering multiple possible techniques.

CONCLUSIONS

In the event of nail disconnection during removal of an intramedullary implant, we recommend use of a long pituitary rongeur to retrieve the distal nail component.