Femoral lengthening with lengthening over a nail has fewer complications than intramedullary skeletal kinetic distraction

PRECICE intramedullary limb lengthening system

The PRECICE(®) Intramedullary Limb Lengthening System (Ellipse Technologies Inc., CA, USA) is a remotely controlled, magnetically driven, implantable limb lengthening intramedullary nail system. It has both CE mark and US FDA clearance for its first- (2011) and second-generation (2013) implants. It is indicated for the treatment of limb length discrepancy and short stature. It has been used worldwide in over 1000 cases. Its reported and published results in over 250 cases has been excellent with less pain and lower complication rates than with external fixation methods or previous implantable nail systems.

Complications of the Intramedullary Skeletal Kinetic Distractor (ISKD) in distraction osteogenesis

BACKGROUND

The Intramedullary Skeletal Kinetic Distractor (ISKD) (Orthofix Inc, Lewisville, TX, USA) is an intramedullary device designed for more comfortable limb lengthening than that with external fixators; lengthening is achieved with this nail using rotational oscillation between two telescoping sections. However, the degree to which this device achieves this goal and its complication rate have not been fully documented.

QUESTIONS/PURPOSES

We determined (1) the frequency with which distraction was not achieved at the desired rate, (2) whether pain differed between patients with normally and abnormally distracting nails, (3) risk factors for abnormal nails, and (4) other complications.

METHODS

We analyzed 35 lengthening segments (26 femurs, nine tibias) in 19 patients. Mean length achieved was 47 mm. Femoral nails were categorized into four groups according to distraction rate: normal, runaway (unintentionally faster rate [> 1.5 mm/day]), difficult-to-distract (slower rate [< 0.8 mm/day] requiring manual manipulation but not requiring general anesthesia), and nondistracting (slower rate [< 0.8 mm/day] requiring manual manipulation under general anesthesia or reosteotomy). Possible risk factors, including age, BMI, preoperative thigh circumferences, degree of intramedullary overreaming, and length of the thicker portion of the nail within the distal fragment, were compared among groups. VAS pain scores were compared among groups under three conditions: rest, physiotherapy, and distraction motion. Complications were also analyzed. Minimum followup was 15 months (mean, 26 months; range, 15-38 months) after first-stage surgery.

RESULTS

Abnormal distraction rate was observed in 21 of 35 segments (60%; 17 femurs, four tibias). VAS pain scores showed no differences among groups during rest or physiotherapy but were higher (p = 0.02) in the problematic nails (7-8 points) versus normal nails (3 points) during distraction. Only mean length of the thicker portion of the nail within the distal fragment differed between normally and abnormally distracting nails (95 mm versus 100 mm; p = 0.03), although this was unlikely to be clinically important. Complications occurred in 10 patients (53%), including five with decreased ankle ROM during distraction, four with delayed bone healing, and one with mechanical device failure during distraction.

CONCLUSIONS

Rate control was difficult to achieve with the ISKD nail for femoral and tibial lengthenings, complications were relatively common, and among patients in whom rate control was not achieved, pain levels were high. Based on our findings, we believe that surgeons should avoid use of this nail.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Is the Intramedullary Skeletal Kinetic Distractor a Safe Measure for Bone Lengthening? A Systematic Review

Background

The intramedullary skeletal kinetic distractor (ISKD) is one of the relatively recent methods developed to overcome the complications of conventional bone lengthening methods, such as external fixators. These complications include pain, muscle transfixation, pin-tract infection, reduced joint motion, and prolonged fixation time. However, ISKD-specific complications such as uncontrollable lengthening and hardware failure make the outcomes of ISKD lengthening questionable. In this article, we review published literature on the efficacy and complications of the ISKD device.

Methods

A database search was conducted in PubMed, Ovid Medline, Ovid Full Text, Springer link, EBSCO Medline, Science Direct, ISI Web of Knowledge, and Google Scholar. We included English articles with extractable data about the study population and outcomes, reporting ISKD implantation in the femur or tibia of skeletally mature patients. The included studies were too heterogeneous for a metaanalysis to be performed.

Results

Fifteen of 89 potentially relevant citations were found to match the inclusion criteria. The most common causes of limb-length discrepancy indicating an ISKD implantation were traumatic and congenital. The average lengthening achieved, average patient discharge period, mean follow-up time, average consolidation time and index, average distraction time and index, and number of patients requiring additional operations as well as other outcome measures are discussed in this article. The most common complications were runaway nail, difficulty in achieving lengthening, and poor bone regenerate formation.

Conclusion

Even though the classic complications of external lengthening are virtually diminished, alterations to the current design of the ISKD are needed to avoid the distraction- related complications. Risk of unplanned surgery could be minimized through proper patient selection and proper surgical techniques.

Precision of the PRECICE internal bone lengthening nail

BACKGROUND

Previous designs of internal bone lengthening devices have been fraught with imprecise distraction, resulting in nerve injuries, joint contractures, nonunions, and other complications. Recently, a magnet-operated PRECICE nail (Ellipse Technologies, Inc, Irvine, CA, USA) was approved by the FDA; however, its clinical efficacy is unknown.

QUESTIONS/PURPOSES

We evaluated this nail in terms of (1) accuracy and precision of distraction, (2) effects on bone alignment, (3) effects on adjacent-joint ROM, and (4) frequency of implant-related and non-implant-related complications.

METHODS

We reviewed medical and radiographic records of 24 patients who underwent femoral and/or tibial lengthening procedures using the PRECICE nail from August 2012 to July 2013 for conditions of varied etiology, the most common being congenital limb length discrepancy, posttraumatic growth arrest, and fracture malunion. This group represented 29% of patients (24 of 82) who underwent a limb lengthening procedure for a similar diagnosis during the review period. At each postoperative visit, the accuracy and precision of distraction, bone alignment, joint ROM, and any complications were recorded by the senior surgeon (SRR). Accuracy reflected how close the measured lengthening was to the prescribed distraction at each postoperative visit, while precision reflected how close the repeated measurements were to each other over the course of total lengthening period. No patients were lost to followup. Minimum followup from surgery was 3 weeks (mean, 14 weeks; range, 3-29 weeks).

RESULTS

Mean total lengthening was 35 mm (range, 14-65 mm), with an accuracy of 96% and precision of 86%. All patients achieved target lengthening with minimal unintentional effects on bone alignment. The knee and ankle ROM were minimally affected. Of the complications requiring return to the operating room for an additional surgical procedure, there was one (4%) implant failure caused by a nonfunctional distraction mechanism and six (24%) non-implant-related complications, including premature consolidation in one patient (4%), delayed bone healing in two (8%), delayed equinus contracture in two (8%), and toe clawing in one (4%).

CONCLUSIONS

We conclude that this internal lengthening nail is a valid option to achieve accurate and precise limb lengthening to treat a variety of conditions with limb shortening or length discrepancy. Randomized, larger-sample, long-term studies are required to further confirm clinical efficacy of these devices, monitor for any late failures and complications, and compare with other internal lengthening devices with different mechanisms of operation.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Internal lengthening device for congenital femoral deficiency and fibular hemimelia

BACKGROUND

Patients with congenital limb shortening can present with joint instability, soft tissue contractures, and significant leg length discrepancy. Classically, lengthening is done with external fixation, which can result in scarring, pin site infection, loss of motion, and pain. We therefore developed an alternative to this approach, a new, controllable, internal lengthening device for patients with congenital limb shortening.

QUESTIONS/PURPOSES

We evaluated this device in terms of (1) healing index, (2) complications, (3) accuracy of the device's external controller, and (4) adjacent-joint ROM.

METHODS

Between January 2012 and May 2013, we treated 66 patients for congenital limb shortening, of whom 21 were treated using this device. During this period, general indications for using the device were patients with leg length discrepancies of 2 cm or more, with intramedullary canals able to withstand rods of at least 12.5-mm diameter and 230-mm length, without active infection in the affected bone, able to comply with the need for frequent lengthening, and without metal allergies or an implanted pacemaker. We included only those patients who had completed their course of treatment and were currently fully weightbearing, leaving 18 patients (21 bone segments) available for followup at a minimum of 6 months after limb lengthening (mean, 14 months; range, 6-22 months). Mean age was 19 years (range, 9-49 years). Sixteen femurs and five tibias were lengthened a mean of 4.4 cm (range, 2.1-6.5 cm). Mean distraction index was 1.0 mm/day (range, 0.5-1.8 mm/day). Healing index, complications, device accuracy, and ROM were recorded. To date, 10 of the 21 devices have been removed. This was typically done 12-24 months after insertion when the bone was solidly healed on all four cortices.

RESULTS

Mean healing index was 0.91 months/cm (range, 0.2-2.0 months/cm). There were seven complications requiring an additional unplanned surgery, including one hip flexion contracture, three femurs with delayed healing, one tibia with delayed healing, one hip subluxation/dislocation, and one knee subluxation. The external controller was accurate as programmed and actual lengthening amounts were consistent. ROMs of the hip, knee, and ankle were essentially maintained.

CONCLUSIONS

This device is completely internal, allowing for satisfactory joint motion during treatment in most patients. Lengthening was achieved in an accurate, controlled manner, and all patients reached their goal length. Complications remain a concern, as is the case with all approaches to this complex patient population. Both future comparative studies and longer-term followup are needed.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Lower Limb Core Scale: a new application to evaluate and compare the outcomes of bone and soft-tissue tumours resection and reconstruction

Several methods are used to evaluate the functional outcome of tumour resections and reconstructions in the lower limb. However, one of their most common limitations is that they are specifically developed to evaluate only oncological patients. We introduced the Lower Limb Core Scale (LLCS) to overcome this limitation. The aim of this study was to evaluate the functional and subjective results in the lower limb and to evaluate the use of the LLCS. We conducted a retrospective cohort study using various tools to investigate the outcomes. The results of the LLCS were correlated with the results of other functional tests. A total of 44 patients were included in the study. None of the demographic variables correlated with the functional or health-related quality of life (QoL) scores except for gender, whereby male patients had an increased functional score. The correlation between LLCS and other scores was positive (r (2) = 0.77). The satisfactory QoL scores, and functional outcomes scores indicated the LLCS to be a reliable option for general and specific evaluation of lower limb reconstructions. We suggest using the LLCS for comparisons of oncological reconstructions with lower limb reconstructions in different disciplines.

Motorized intramedullary nail for management of limb-length discrepancy and deformity

Distraction osteogenesis has been used for more than 50 years to address limb-length discrepancy and deformity. Intramedullary fixation has been used in conjunction with external fixation to decrease the time in the external fixator and prevent deformity and refracture. A new generation of motorized intramedullary nails is now available to treat limb-length discrepancy and deformity. These nails provide bone fragment stabilization and lengthening with reliable remote-controlled mechanisms, obviating the need for external fixation. Motorized intramedullary nails allow accurate, well-controlled distraction, and early clinical results have been positive.

How precise is the PRECICE compared to the ISKD in intramedullary limb lengthening? Reliability and safety in 26 procedures

BACKGROUND AND PURPOSE

The PRECICE intramedullary limb lengthening system uses a new technique with a magnetic rod and a motorized external remote controller (ERC) with rotational magnetic field. We evaluated the reliability and safety of the PRECICE system.

METHODS

We compared our preliminary results with PRECICE in 24 patients (26 nails) with the known difficulties in the use of mechanical lengthening devices such as the ISKD. We used the Paley classification for evaluation of problems, obstacles, and complications.

RESULTS

2 nails were primarily without function, and 24/26 nails lengthened over the desired distance. Lengthening desired was 38 mm and lengthening obtained was 37 mm. There were 2 nail breakages, 1 in the welding seam and 1 because of a fall that occurred during consolidation. ERC usage was problematic mostly in patients with femoral lengthening. Adjustment of the ERC was necessary in 10 of 24 cases. 15 cases had implant-associated problems, obstacles were seen in 5 cases, and complications were seen in each of 4 cases. INTERPRETAION: The reliability of the PRECICE system is comparable to that of other intramedullary lengthening devices such as the ISKD. The motorized external remote controller and its application by the patients is a weak point of the system and needs strict supervision.

Limb lengthening with fully implantable magnetically actuated mechanical nails (PHENIX(®))-preliminary results

Limb lengthening and deformity correction with fully implantable systems is becoming more and more widespread. Different actuation techniques are known and every system has its specific limitations in distraction control and/or stability. A new system with magnetic actuation offers outstanding options. The mechanism of the Phenix M2(®) bone lengthening nail (Phenix Medical, France) is driven by a strong external magnet. The device can provide lengthening, shortening and bone transport. Between December 2011 and November 2012 we applied the nail in 10 patients with an average age of 25 years (range 15-40 years). There were 6 femoral and 4 tibial procedures. The intended distraction goal was achieved in 8 of 10 patients. In three cases we simultaneously corrected malalignment. Average lengthening was 4.6 cm (range 1.3-7.6 cm). Average distraction index was 0.85 mm/day (range 0.6-1.3mm/day). Average weight bearing index was 27 days/cm (range 16-37 days/cm). Three patients had revisions due to early distraction arrest. The early results are comparable to those of other intramedullary systems in the literature like the ISKD(®), the Albizzia(®) or the Fitbone(®) system. All intramedullary procedures require accurate analysis and planning, advanced operative technique and close follow-up. The custom made design of the Phenix nail with unique options for size, stroke and locking provides new options for small bones and improved stability. The shortening option may be helpful for soft tissue problems, joint subluxation and additional stimulation of bone formation. Magnetic forces have to be considered and too much soft tissue around the nail might be a limiting factor. The magnetically actuated Phenix nail offers new therapeutic options in limb lengthening.

Biomechanical assessment of a novel bone lengthening plate system - a cadaveric study

BACKGROUND

Although many types of external fixators have been developed for distraction osteogenesis, all have some drawbacks. We recently developed a novel bone lengthening plate to overcome these problems. The purpose of this study is to conduct biomechanical analyses using cadavers to assess the stability of the bone lengthening plate in relation to distraction length and femoral bone mineral density.

METHODS

We used human cadaveric femurs (n=18) to assess the effects of distraction length and bone mineral density on the biomechanical stability of the bone lengthening plate. After establishing control (n=6, 0mm lengthening) and experimental groups (n=12, 30 mm lengthening), we measured biomechanical stability (structural stiffness, ultimate load, and displacement) under a compressive load. The experimental group was subdivided into a group with normal bone mineral density (n=6) and a group with osteoporosis (n=6), and the biomechanical stability of these groups was compared.

FINDING

Structural stiffness differed significantly between the control (417.6 N/mm) and combined experimental groups (185.6 N/mm, p=0.002). Ultimate load also differed significantly between the control (1327.8 N) and combined experimental (331.4 N, p=0.002) groups. Bone mineral density was unrelated to structural stiffness (p=0.204), ultimate load (0.876), or displacement (0.344). In all cases, failure of the bone lengthening plate occurred at the longitudinal connectors, such as the connecting columns between the upper and lower plates, and the lengthening shaft of the bone lengthening plate.

INTERPRETATION

The biomechanical stability of the bone lengthening plate was affected by the lengthening length but not by bone mineral density. In addition, biomechanical stability during lengthening was most strongly influenced by the longitudinal connectors.

Current concepts of leg lengthening

Any lower limb discrepancy may be equalised by conservative means (insoles, prosthesis and orthosis). However, their long-term acceptance is low in regard to function, costs, expenditure and appearance. Timely epiphysiodesis is the best option in uniplanar deformities with adequate remaining growth and for patients whose predicted final body height is above the 50th percentile. However, many patients present late or with multi-planar deformities, which warrant more sophisticated operative approaches. The history of surgical bone lengthening comprises 100 exciting years of struggling, development and ongoing learning. The initial strategy of acute or rapid incremental distraction had lasted almost half a century until Ilizarov recognised the benefits of biological periosteum-preserving osteotomies and incremental lengthening at slow rates (1 mm/day) at a 4 × 0.25-mm daily rhythm, well appreciated as callotasis. In parallel, ring and wire constructs made complex three-dimensional axial, translational and rotational bone moulding possible. Taylor Spatial Frames-built on hexapod strut-linked platform technology as known from flight simulators-took limb correction to a more reliable, more precise and aesthetical level, all the more that the whole process became web-based. It represents state-of-the-art methodology and technology for complex, multi-plane deformities. Due to the significant risk of secondary malalignment, indications for lengthening by unilateral fixation have shrunken to moderate amounts of length disparity and uni- to bi-planar deformities in patients with still open physes. Mechanical or motorised, minimally invasively placed nails prevent muscle fixation and, therefore, ease rehabilitation, increase patient comfort and potentially shorten the overall time of sick leave and refrain from sports activities. Hence, they offer a valuable alternative for low-grade complexity situations. It remains to be proved if the significantly higher implant costs are compensated by lower treatment costs. Overall, limb lengthening, particularly in combination with multi-planar deformity correction, can still be an arduous endeavour. In any case, wise judgement of the patient's deformity, medical and biological situation, psychosocial environment, selection of the appropriate method and hardware, as well as meticulous operating technique by an experienced surgeon are the cornerstones of successful outcomes.