Distraction osteosynthesis refers to a technique in which a limb is gradually lengthened at a controlled rate across the osteotomy site. The original limb lengthening procedure was first described in the English orthopedic literature by Codvilla (1905). In the 1960s, the Wagner method (limb lengthening with cancellous bone grafting and plating of the distraction gap) was introduced into North America, and became the mainstay of limb lengthening in the United States for many years. In this technique, an open mid-diaphyseal osteotomy is carried out across the periosteum, endosteum, and cortex resulting in a 0.5 to 1 cm diastasis; followed by the placement of an external fixation system secured by screws in both the proximal and distal metaphyses. Distraction commences immediately following placement of the fixator. The distraction rate is traditionally set at 1.5 to 2 mm per day. Following attainment of the desired distraction length, iliac crest cancellous bone is grafted into the diastasis in a second operation. The affected bone is plated, and the external distractor is removed. The operated limb does not bear weight for an extended period of time to allow for incorporation of the graft. In a third operation, the plate is removed, and the subject is put on protective weight bearing (Wagner, 1978; Hood and Riseborough, 1981).
A less invasive technique for distraction osteosynthesis was developed by a Russian orthopedist Gavriil Abramovich Ilizarov in the 1950s. His work was introduced to Italy in the 1980s as a result of the former Soviet Union's policy of glasnost, and later to the United States (Frankel et al, 1988). According to Ilizarov's principle of "tension stress", bone and soft tissue will heal and regenerate in a predictable fashion under tension. The Ilizarov procedure comprises 4 phases: (i) corticotomy (a special type of percutaneous osteotomy) and placement of an external fixation system, (ii) latency period, (iii) distraction, and (iv) consolidation. This method has been employed to treat a wide variety of bone defects including limb lengthening while correcting concurrent associated angular and rotational malalignments, transporting bone segments to fill fracture gaps, and healing non-union fractures. Compared to other alternatives such as the Wagner technique, the Ilizarov method requires only one surgical procedure and appears to have fewer complications. Additionally, the Ilizarov procedure allows for simultaneous correction of multiple deformities, early movement of adjacent joints, as well as early weight bearing (Do and Sadove, 1992; Simard et al, 1992).
Cattaneo et al (1993) described the use of the Ilizarov procedure to 97 humeri on 75 patients, with 68 lengthening in 46 patients (27 males and 19 females, average age of 16.5 years) and 29 treatments for non-union in 29 patients (17 males and 12 females, average age of 46 years). For patients who underwent humeral lengthening, results were considered excellent if the projected lengthening was attained, or in the cases of length discrepancy, less than a 3-cm length discrepancy remained, or if axial alignment was acceptable (less than 10 degrees angulation), and scars were minimal. Furthermore, pre-operative function had to be maintained. Outcomes were deemed good if there was only minimal functional loss, and poor if there was a limb discrepancy of greater than 5 cm, angulation of more than 10 degrees and significant loss of function, or a permanent neurological injury. For patients who had treatments for humeral nonunion, consolidation was considered an excellent result, whereas persistence or recurrence of nonunion was considered a poor result. Duration of treatment ranged from 5 to 14 months. Forty-two (91.3 %) of the 46 patients who had undergone humeral lengthening had excellent results, 3 (6.5 %) had good results, and the remaining 1 (2.2 %) had a poor result as a consequence of reduced shoulder motion. There were no major complications associated with this procedure. For patients who underwent treatments for humeral nonunion, 25 (86.2 %) of 29 humeri healed, and 4 (13.8 %) remained ununited. Of these, there were 3 patients aged 55, 70, and 79 years, and 1 patient with irradiated bone. Results of this study indicated that the Ilizarov procedure is effective in humeral lengthening as well as in the treatment of humeral non-union.
Cierny and Zorn (1994) compared conventional methods with the Ilizarov procedure in the treatment of 44 patients with segmental tibial defects. Patients were divided into 2 groups: (i) 21 long bone defects (segmental defects averaged 6.5 cm) were reconstituted by means of transport (part of the Ilizarov procedure that entails sliding a bone fragment internally, producing distraction osteogenesis behind the defect until it is bridged) or distraction methodologies according to the Ilizarov technique, and (ii) 23 subjects (segmental defects averaged 8.5 cm) underwent conventional treatment of reconstruction using tissue transfers and transpositions, massive cancellous grafts, and combinations of internal and external fixation. Total wound consolidation and infection arrest occurred after the first treatment in 71 % of the Ilizarov wounds, and 74 % of the conventionally treated wounds. The major complication rate for the Ilizarov group was 33 %, while that for the conventionally treated group was 60 %. The overall success rate (95 %) were the same for both groups. However, the Ilizarov group averaged 9 fewer hours in the operating room, 23 fewer days in the hospital, 5 fewer months of disability times, and a saving of nearly $30,000 per application. These findings indicated that the Ilizarov procedure is faster, safer, and less expensive approach than conventional methods for the treatment of segmental tibial defects.
Fadel and Hosny (2005) noted that the Taylor Spatial Frame (TSF) uses the slow correction principles of the Ilizarov system but adds a 6-axis deformity analysis incorporated within a computer program. These researchers used the TSF in lengthening and deformity correction of the lower limbs to treat 22 cases from 1999 to 2001. There were 14 females and 8 males (average age of 16.5 years). Their target was lengthening in 8 cases, correction of deformities in 8 and both in 6. The results were excellent in 18 cases, good in 2, and fair in 2. Despite the cost, patient profile and a steep learning curve, the results were encouraging but less favorable than with the traditional Ilizarov external fixator.
Kristiansen et al (2006) noted that different methods and devices are used to perform lengthening and deformity reconstruction in the tibia. Recently, the TSF has been introduced as a computer-assisted and versatile external ring fixator. Lengthening index (LI) and complications are important result parameters, and the aim of this study was to review our first 20 tibial segments operated with the TSF and compared the results with those of using the traditional Ilizarov external fixator (IEF). These researchers lengthened 20 tibial segments in 20 patients with the TSF. The results were compared with those of 27 tibial segments from 27 patients that were lengthened with the IEF. All segments were operated on with monofocal osteotomies. In the over-lapping zone of comparable lengthening distances between 2.4 and 6.0 cm, the LI of 2.4 and 1.8 months/cm was not significantly different between the TSF and IEF groups, respectively (p = 0.17). This non-significant difference was confirmed after adjustment for age. The authors found no difference between the TSF and IEF frames regarding LI and complication rate. However, rotational, translational, and residual deformity correction is easier to perform with the TSF.
Simpson et al (2008) stated that the TSF is a fixation device used to implement the Ilizarov method of bone deformity correction to gradually distract an osteotomized bone at regular intervals, according to a prescribed schedule. These researchers modified conventional technique by: (a) pre-operatively planning a virtual three-dimensional (3D) correction; (b) basing the correction on the actual location of the frame with respect to the anatomy, immediately compensating for frame mounting errors; and (c) calculating the correction based on 3D CT data rather than measurements from radiographs. They performed a laboratory study using plastic phantoms, and a pilot clinical study involving 5 patients. In 20 tibial phantom experiments, these investigators achieved average correction errors of less than 2 degrees total rotation and less than 0.5 mm total lengthening. They observed clinically acceptable corrections with no complications in this pilot clinical study. The authors concluded that their method achieved high accuracy and precision in a laboratory setting, and produced acceptable outcomes in a pilot clinical study.
Naqui et al (2008) noted that correcting multi-planar lower-limb pediatric deformities requires complex and, in many cases, staged procedures. The TSF is a sophisticated external fixator system that can be used to treat simple to complex multi-planar and multi-apical skeletal deformities. These researchers described its use in 53 children during the last 7 years in a variety of pathologies and demonstrate its ease of use and versatility. A review of medical and physiotherapy records, radiographs, and CT scans of all patients treated with a TSF between June 1999 and December 2005 at the Booth Hall Children's Hospital was conducted. Data recorded were etiology of deformity, sex, age, number of previous operations, pre-operative deformity parameters, operative records and frame constructs, treatment regime, frame duration, follow-up protocol, post-treatment deformity, complications, and clinical and radiological outcome. Fifty-three patients between the ages of 12 months and 16 years (mean of 10.7 years) underwent correction programs for 55 limbs (44 tibia and 11 femurs). The etiology of deformity was congenital in 39 cases and acquired in 14. These investigators were able to achieve an acceptable correction of deformity (leg length discrepancy less than 15 mm, angulation less than 5 degrees) in 52 limbs. A number of complications were encountered. The authors demonstrated the TSF's ease of use for both surgeon and patient and its versatility in a variety of pathologies. The advantages of the TSF system are many. It is a simple frame construct, and application is easy. The plan and execution are structured with precise end points; it is a single-stage correction and thus avoids frame modifications. Any residual deformity can be further corrected by use of the same frame. The authors concluded that the TSF is an effective and efficient way to correct a wide variety of simple and complex often obstinate pediatric limb deformities.
Marangoz et al (2008) stated that the TSF has been used commonly in children and young adults. Its use in the tibia is more extensively studied and applied than in the femur. These researchers examined if normal alignment can be achieved with accuracy during correction of femoral deformities while avoiding major complications in children and young adults. They retrospectively reviewed the clinical and radiographic records of 20 patients (22 limbs), aged 5.9 to 24.6 years, who underwent a TSF for femoral deformity. Etiology included a number of diagnoses of the pediatric age. Minimum follow-up was 4.5 months (mean of 15.7 months; range of 4.5-to 35 months). The mean time in frame was 6.2 months (range of 2.6 to 19 months). Frontal and sagittal plane deformities were corrected to within normal values. A mean limb lengthening of 4.9 cm (range of 1.5 to 9 cm) was performed in 8 femora; 7 of which the limb length discrepancy was a secondary concern. External fixation index in the lengthening subgroup was 2.2 months/cm. The 15 complications in 13 limbs included pin tract infection, knee stiffness, delayed union, skin irritation, and posterior knee subluxation. No complications occurred in 9 limbs. Computer-assisted femoral deformity correction with 6-axis deformity analysis and the TSF is an accurate and safe technique in children and young adults.
McCarthy and colleagues (2008) examined if a monolateral fixator, which allows for correction of angular deformity and displacement in 3 planes, can correct lower extremity deformities to within normal radiographic means (anatomic lateral distal femoral angle, anatomic medial proximal tibial angle, and tibial femoral angle). These researchers retrospectively reviewed the clinical records and radiographs of 22 consecutive patients (25 limbs) who underwent deformity correction using a new multi-axial monolateral external fixator. The patients were 4 to 16 years of age. The authors had a minimum 1.2-year follow-up (mean of 2.14 years; range of 1.2 to 3.1). Those with primary femoral and tibial deformities had improvements in the mean deviation from normal of the anatomic lateral distal femoral angle, anatomic medial proximal tibial angle and tibial femoral angle. Patients with Blount's disease had improvements in the mean anatomic medial proximal tibial angle from 59.9 masculine to 87.8 masculine. Five patients had complications (2 pin site infections, 1 premature consolidation, 1 knee flexion contracture, 1 recurrence of varus). Six patients developed secondary deformities, all of which were corrected using the primary or secondary hinge. The authors concluded that this fixator can produce satisfactory results with relatively few complications.
Wukich and Kline (2008) stated that patients with diabetes mellitus (DM) have higher complication rates following both open and closed management of ankle fractures. Diabetic patients with neuropathy or vasculopathy have higher complication rates than both diabetic patients without these co-morbidities and non-diabetic patients. Unstable ankle fractures in DM patients without neuropathy or vasculopathy are best treated with open reduction and internal fixation with use of standard techniques. Patients with neuropathy or vasculopathy are at increased risk for both soft-tissue and osseous complications, including delayed union and non-union. Careful soft-tissue management as well as stable, rigid internal fixation are crucial to obtaining a good outcome. Prolonged non-weight-bearing and subsequently protected weight-bearing are recommended following both operative and non-operative management of ankle fractures in patients with DM.
DiDomenico et al (2009) noted that patients who have a diagnosis of DM, diabetic peripheral neuropathy, peripheral vascular disease and experience an unstable ankle fracture present as difficult case scenarios for treating physicians. In addition, patients who have DM, along with the presence of multiple co-morbidities, have been shown to have higher complication rates than patients who do not have DM. These researchers described a relatively safe alternative surgical percutaneous technique using external circular ring fixation in the vascularly compromised diabetic patient with an unstable ankle fracture. This novel technique decreases the risk for soft tissue complications in the high-risk diabetic patient and serves as a definitive method of fixation without the need for additional surgery. It allows the patient to have early and full weight-bearing when indicated in the post-operative period.
The Intramedullary Skeletal Kinetic Distractor (ISKD) is an internal limb lengthening device consisting of a telescoping internal limb lengthener, locking screws, and an external hand-held monitor that tracks the rotation of an internal magnet on a daily basis. Implanted after osteotomy, the ISKD lengthens gradually in response to normal movements of the limb. The device allows lengthening to take place internally, thus the risk of infection and scarring from pins moving through the soft tissues is potentially reduced.
The ISKD requires a physical leg movement to "click" the device into lengthening. In this method, there is no risk of accidentally over-stretching the bone due to the lengthener being preset to the desired fully extended length. However, there is a risk of growing the bone too quickly. Bone growth is monitored by measuring changes in the magnetic field of the embedded magnet in the system. The poles of the magnet change as the device grows. However, if the motion of the leg makes the device grow too quickly, and the magnet switches poles twice between measurements, then that growth is not recorded. This leads to overly rapid growth which can cause a number of issues such as nerve damage or causing breaks in the bone.
Potaczek and colleagues (2008) presented their findings of limb elongation method with the ISKD. Subjects consisted of 5 patients, aged 14 to 16 years, 3 boys and 2 girls, who underwent femur lengthening with the ISKD nail between 2005 and 2007. Initial shortening, surgical procedure, complications, amount of lengthening, lengthening rate, distraction index, time of treatment and mobility of adjacent joints were evaluated. Initial shortening was 4 to 11 cm. No surgical complications were observed, mean time of surgery was 145 mins, mean blood loss was 200 ml. In 3 patients difficulties with initial distraction required manipulations under general anaesthesia. Distraction was complicated in 3 cases: in 2 patients premature consolidation was noted; in 1 case the distraction rate was too high. Mean lengthening rate in the study group was 0.7 mm/day (0.6 to 0.7 mm/day). Mean distraction index was 41.7 days/cm (26.2 to 55 days/cm). Full weight bearing was allowed after mean 234 days (210 to 275 days). Transient decrease of adjacent joint mobility was observed. The authors concluded that the fully implantable, telescopic ISKD eliminated the need of external fixation and associated complications. Early results of limb lengthening with ISKD are encouraging. The authors stated that careful patient selection and pre-operative planning is required; they also noted that further studies and longer follow-up periods are also needed.
Kenawey and associates (2011a) noted that mechanically activated intramedullary lengthening nails are advantageous over external fixator. However, difficulties with the control of the distraction rate are the main drawbacks, which may in turn cause insufficient bone regenerate. These investigators reviewed the findings of of 57 lengthening procedures using ISKD nail in 53 patients (femoral = 45 and tibial = 12). Average length gain was 4.3 +/- 1.6cm. The cause of shortening was post-traumatic (n = 33), congenital (n = 20), post-tumour resection (n = 1), cosmetic femoral lengthening (n = 2) and post-correction of distal femoral varus deformity (n = 1). The desired lengthening was achieved in all patients. The mean follow-up period was 23 +/- 12 months. The healing index for patients with normal bone healing was 1.2 +/- 0.32 months/cm. Complications in femoral lengthening were superficial wound infection (n = 1), premature consolidation (n = 4) and insufficient bone regenerate (n = 11), while in the tibial lengthening, 2 developed equinus contractures, 1 had compartment syndrome following implantation of the nail and 1 insufficient bone regenerate. Furthermore, 9 runaway nails and 3 non-distracting nails were present in the femoral lengthening. One non-distracting nail responded to manipulation under anaesthesia, 1 required exchange nailing and accidental acute lengthening of 3 cm took place while manipulating the third nail. Patients with femoral lengthening and those with insufficient regenerate had significantly higher distraction rates (p = 0.006 and 0.003, respectively). Six out of the 9 runaway nails developed insufficient bone regenerate. In addition, 10.7-mm tibial ISKD nails were found to have lower rates of runaway nails compared with other used diameters. The authors emphasized the rule of distraction rates above 1.5 mm/day in the development of insufficient bone regenerate. Distraction problems with these nails are mostly due to dysfunction within the ratcheting mechanism, which may be related to the diameter of the nail. They stated that new designs for mechanically activated nails with a better control mechanism for the distraction rate are required.
Kenawey and co-workers (2011b) stated that control of distraction rate with an ISKD may be problematic and a high distraction rate may result in insufficient bone regenerate. These researchers analyzed 37 consecutive ISKD femoral lengthening procedures in 35 patients with a mean age 33 +/- 11 years and minimum follow-up of 12 months (average of 27 +/- 9 months; range of 12 to 55 months). The average length gain was 42.8 +/- 12.9 mm. A total of 8 patients had problems during distraction: 7 had "runaway nails" and 1 had a non-distracting nail. Insufficient bone regenerate developed in 8 patients. Important risk factors were a distraction rate greater than 1.5 mm/day (9.1 times higher risk), age 30 years or older, smoking, and lengthening greater than 4 cm. Less important risk factors identified were creation of the osteotomy at the site of previous trauma or surgery and acute correction of associated deformities. The authors proposed a radiological classification for failure of bone regeneration: partial regenerate failure (Type I) or complete failure resulting in a segmental defect subdivided according to a length of 3 cm or less (Type IIa) or greater than 3 cm (Type IIb). They concluded that distraction problems with the ISKD were related mostly to internal malfunction of the lengthening mechanism. A distraction rate greater than 1.5 mm/day should be avoided in femoral intramedullary lengthening. Furthermore, smoking should be a contraindication for femoral lengthening.
Schiedel et al (2011) reported the results of intramedullary leg lengthening conducted between 2002 and 2009 using the ISKD in 69 unilateral lengthening involving 58 femora and 11 tibiae. These investigators identified difficulties that occurred during the treatment and examined if they were specifically due to the implant or independent of it. Paley's classification for evaluating problems, obstacles and complications with external fixators was adopted, and implant-specific difficulties were continuously noted. There were 7 failures requiring premature removal of the device, in 4 due to nail breakage and 3 for other reasons, and 5 unsuccessful outcomes after completion of the lengthening. In all, 116 difficulties were noted in 45 patients, with only 24 having problem-free courses. In addition to the difficulties arising from the use of external fixators, there was almost the same number again of implant-specific difficulties. Nevertheless, successful femoral lengthening was achieved in 52 of the 58 patients (90 %). However, successful tibial lengthening was only achieved in 5 of 11 patients (45 %).
Mahboubian et al (2012) noted that lengthening over a nail and internal lengthening nails have been developed to minimize or eliminate patients' time wearing a frame during femur lengthening. However it is unclear whether either of these 2 approaches results in faster times to union or fewer complications over the other. These investigators examined which technique better achieved: (i) the lengthening goals, (ii) the distraction rate control, (iii) quality of the regenerate bone, (iv) fewer complications, and (v) if SF-36 scores and American Academy of Orthopaedic Surgeons-Lower Limb Module (AAOS-LLM) scores differ in each treatment modality? They retrospectively reviewed the records and radiographs of 11 patients who had 12 ISKD procedures between 2002 and 2005, and 21 patients with 22 femoral lengthening performed as lengthening over nail procedures between 2005 and 2009. Details such as leg length discrepancies, operative time, time of removal of the external fixator or ISKD, and any complications encountered were recorded; SF-36 and AAOS-LLM scores also were compiled. The minimum follow-ups for the ISKD and the lengthening over nail cohorts were 62 months (average of 76 months; range of 62 to 93 months) and 13 months (average of 27 months; range of 13 to 38 months), respectively. These researchers observed no difference in achieving the lengthening goals between the 2 procedures. Distraction was not well-controlled in the ISKD group; the distraction rates were 1.7 mm per day for the fast group (distraction rate greater than 1 mm/day) and 0.84 mm per day for the slow group (less than 1 mm/day). The lengthening over nail group had an average distraction rate of 0.88 mm per day. One of 20 of the patients who had lengthening over a nail had complications requiring additional unanticipated surgeries whereas 6 of 12 patients who had femoral lengthening in the ISKD group had such complications. The authors concluded that based on their observations, they believe the lengthening over nail technique for femoral lengthening is associated with fewer complications than the ISKD.
In a systematic review of randomized controlled trials (RCTs), Busse and colleagues (2009) examined the effectiveness of low-intensity pulsed ultrasound (LIPUS) for healing of fractures. Electronic literature search without language restrictions of CINAHL, Embase, Medline, HealthSTAR, and the Cochrane Central Registry of Controlled Trials, from inception of the database to 10 September 2008 was performed. Eligible studies were RCTs that enrolled patients with any kind of fracture and randomly assigned them to LIPUS or to a control group. Two reviewers independently agreed on eligibility; 3 reviewers independently assessed methodological quality and extracted outcome data. All outcomes were included and meta-analyses done when possible. A total of 13 randomized trials, of which 5 assessed outcomes of importance to patients, were included. Moderate quality evidence from 1 trial found no effect of LIPUS on functional recovery from conservatively managed fresh clavicle fractures; whereas low quality evidence from 3 trials suggested benefit in non-operatively managed fresh fractures (faster radiographic healing time mean of 36.9 %, 95 % confidence interval [CI]: 25.6 % to 46.0 %). A single trial provided moderate quality evidence suggesting no effect of LIPUS on return to function among non-operatively treated stress fractures. Three trials provided very low quality evidence for accelerated functional improvement after distraction osteogenesis. One trial provided low quality evidence for a benefit of LIPUS in accelerating healing of established non-unions managed with bone graft. Four trials provided low quality evidence for acceleration of healing of operatively managed fresh fractures. The authors concluded that evidence for the effect of LIPUS on healing of fractures is moderate to very low in quality and provided conflicting results. Moreover, they stated that although overall results are promising, establishing the role of LIPUS in the management of fractures requires large, blinded trials, directly addressing patient important outcomes such as return to function.
In a prospective RCT, Dudda et al (2011) examined the effect of LIPUS during distraction osteogenesis. A total of 36 patients who underwent distraction osteogenesis (greater than 2 cm) were enrolled; 16 patients in the treatment group received LIPUS, and 20 patients as control group did not. Ultrasound treatment device was transcutaneously applied at the distraction gap for 20 mins daily (frequency 1.5 MHz, signal burst with 200 μs, signal repetition frequency 1.0 kHz, intensity 30 mW/cm(2)). Evaluation of patients was performed by standard radiographs every 3 weeks to 4 weeks. Average transport distance was 7.0 cm in the ultrasound group, and 6.3 cm in the control group. Mean Paley index for the ultrasound group was 1.09 months/cm and 1.49 months/cm for the control group. Mean distraction consolidation index for the ultrasound group was 32.8 days/cm and 44.6 days/cm for the control group. The calculated indices indicated no significant statistical difference between the 2 groups (p < 0.116) but the fixator gestation period could be decreased for 43.6 days in the treatment group. The authors concluded that therapeutic application of LIPUS during callus distraction constitutes a useful adjuvant treatment during distraction osteogenesis and has a positive effect on healing time with no negative effects.
Salem and Schmelz (2014) noted that LIPUS has been shown to improve callus maturation with distraction osteogenesis in animal trials. However, only few clinical studies are available to support its widespread use for the latter indication in humans. In this study, a total of 21 patients undergoing callus distraction for post-traumatic tibial defects were randomized into 2 groups: (i) the trial group (12 men; mean age of 32 years) received 20 minutes of LIPUS daily during treatment and (ii) the control group (6 men and 3 women; mean age of 29 years) with no LIPUS treatment. The Ilizarov ring fixator was used in all cases. Results were examined clinically and radiologically; callus maturation was analyzed with a computer-assisted measurement. Patients in the LIPUS group needed a mean of 33 days to consolidate every 1 cm of new bone in comparison to 45 days in the control group. The healing index was therefore shortened by 12 days/cm in the LIPUS group. This means that callus maturation was 27 % faster in the LIPUS group. The fixator time was shortened by 95 days in the LIPUS group. The overall daily increase in radiographic callus density was 33 % more in the LIPUS group than in the control group. The authors concluded that LIPUS treatment is an effective non-invasive adjuvant method to enhance callus maturation in distraction osteogenesis. With the help of this treatment, the healing time and the duration of external fixation can be reliably shortened. This was a small study (n = 12); its findings need to be validated by well-designed studies.
The PRECISE intramedullary limb lengthening system is used for lengthening procedures of the tibia and femur bones. Traditional lengthening of bones occurs via an external adjustable fixation system, namely, the Ilizarov method, attached to the leg bones through openings in the tissue. The PRECISE intramedullary limb lengthening system will enable leg lengthening via non-invasive methods through remote control technology that enables adjustment of previously surgically implanted rods. The system is essentially comprised of extension rods, a magnetic actuator, and a hand-held external remote controller (ERC). Once the magnetic actuator and extension rods have been surgically implanted in a sterile fashion, the ERC can be positioned against the skin to non-invasively shorten or lengthen the rods via the magnetic system. Limb lengthening is done for medical conditions such as major fractures, congenital abnormalities, or some forms of bone cancer. This non-invasive method hopes to reduce such complications as infections by eliminating the need for deep tissue exposure while lengthening bones over time. The device was cleared for marketing by the FDA in August 2011. http://earlsview.com/2011/08/24/fda-clearance-precice-remote-control-leg-limb-lengthening-device/. Also, there is currently a post-market study of the Ellipse PRECICE Intramedullary Limb Lengthening System to evaluate the performance and safety of this device. This study is currently recruiting participants; last verified August 2013. http://clinicaltrials.gov/show/NCT01601301.
Schiedel et al (2014) evaluated the reliability and safety of the PRECICE system. These researchers 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. They used the Paley classification for evaluation of problems, obstacles, and complications. 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. External remote controller 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. The authors concluded that the reliability of the PRECICE system is comparable to that of other intramedullary lengthening devices such as the ISKD. The motorized ERC and its application by the patients is a weak point of the system and needs strict supervision.
Currently, there is a lack of evidence regarding the safety and effectiveness of PRECISE intramedullary limb lengthening system.
Jain and Harwood (2012) performed a systematic review to evaluate tibial lengthening procedures with the use of an intramedullary nail. These researchers investigated the hypothesis that lengthening over a nail can reduce the time spent in an external fixator and increase the rate of consolidation, thereby reducing the risk of complications and improving patient satisfaction. These investigators conducted a comprehensive literature search using the MEDLINE, EMBASE and PubMed databases using the key words 'tibia' or 'tibial lengthening' and 'nail'. This search was performed in December 2011 and repeated by both authors. Specific outcome measures were the duration of external fixation, rate of consolidation and complication rates. A total of 6 comparative studies published between 2005 and 2011 consisting of 494 procedures met the inclusion and exclusion criteria and were eligible for critical appraisal. The methodological quality of the studies was variable, and they were not homogenous enough for meta-analysis. Patients who have tibial lengthening over an intramedullary nail spend significantly less time in an external fixator. However, there is no reliable evidence to suggest that the rates of consolidation or complication were any different to those lengthened without an intramedullary nail.
Kim and associates (2012) noted that lengthening over a nail was introduced to reduce the overall complication rate in the classic Ilizarov method. Previous studies reported that an intramedullary nail could decrease the time of external fixation, prevent anatomic mal-alignment and collapse; internal friction, damage to endosteal blood supply and infection rates, however, may be higher. Whether the approach achieves it goals with acceptable complication rates is unclear. These investigators described the results and complications of tibial lengthening over a nail. They retrospectively reviewed 40 patients with 80 lengthened tibial segments over an intramedullary nail between 2004 and 2009. The average age of the patients at the time of surgery was 22 years (range of 18 to 38 years). Functional and psychological outcomes were evaluated using the questionnaires. The average lengthening achieved was 7.73 cm, 23.5 % of initial length. The external fixation index was 1.1 months/cm, and bone-healing index was 1.7 month/cm. The most common complications were valgus angulations of tibia in 20 segments (25 %) and equinus contracture in 58 segments (72 %). Functional and psychological outcomes were satisfactory after surgery. The authors concluded that lengthening over a nail did not fully prevent axial deviation of regenerate. Equinus contracture was the most common complication but it could be rectified by early intervention such as intramuscular recession or an additional foot frame. Limb lengthening increased functional and psychological outcomes even though there were many complications after surgery.
In a prospective RCT, El-Husseini et al (2013) compared lengthening over an intramedullary nail to the conventional Ilizarov method with regard to percentage length increase, external fixation index, consolidation index and incidence of complications. A total of 31 limbs in 28 patients were included in the study; 15 were lengthened over an intramedullary nail, and 16 limbs were lengthened conventionally. The mean duration of external fixation in the lengthening over nail group was 52.2 days compared to 180.4 days in the conventional group. There was higher incidence of complications in the conventional method group. In comparison with conventional Ilizarov lengthening, lengthening over an intramedullary nail offers a shorter period of external fixation and fewer complications overall, but there is a high incidence of deep intramedullary infection which was serious.
Konofaos et al (2012) described a novel intramedullary device (M-Bone; Phenix, Paris, France) that contains a mechanism for internal osteodistraction and bone transport in patients with segmental bone defects or limb length discrepancy after limb salvage operations. A total of 5 patients with primary bone tumors were enrolled in the study. After implantation, daily lengthening was performed in an outpatient setting either by the patient or with the help of a therapist, without the use of anesthesia. This unique device offers a totally new approach for the treatment of segmental bone defects or limb length discrepancy. It was designed to expand the remaining native bone by a magnetically activated drive system to induce new bone formation using osteodistraction and bone transport.
Thaller and colleagues (2014) stated that 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 activation 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, these researchers applied the nail in 10 patients with an average age of 25 years (range of 15 to 40 years). There were 6 femoral and 4 tibial procedures. The intended distraction goal was achieved in 8 of 10 patients. In 3 cases these investigators simultaneously corrected mal-alignment. Average lengthening was 4.6 cm (range of 1.3 to 7.6cm). Average distraction index was 0.85 mm/day (range of 0.6 to 1.3 mm/day). Average weight bearing index was 27 days/cm (range of 16 to 37 days/cm). Three patients had revisions due to early distraction arrest. The early results were 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 provided 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 authors stated that magnetically activated Phenix nail offers new therapeutic options in limb lengthening. These preliminary findings need to be validated by well-designed studies.