[An implantable femur distractor for operative leg lengthening (author's transl)]

[Research progress of intramedullary lengthening nail technology]

Objective

To review the research progress of intramedullary lengthening nail technology.

Methods

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

Results

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

Conclusion

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

Intramedullary lengthening nails: can we also correct deformities?

Unlike external fixators, the use of solid intramedullary lengthening nails is restricted to defined anatomical preconditions, such as an adequate bone length. Furthermore, all deformity corrections except the lengthening procedure have to be implemented intraoperatively and cannot be adjusted postoperatively. Conversely, even complex deformity corrections can be performed using intramedullary devices after a thorough preoperative planning. For preparation of the intramedullary cavity as well as positioning of the lengthening nail according to the preoperative planning, reaming the medullary canal with rigid reamers which don't follow the line of least resistance is inevitable. However, the application of solid lengthening nails might be limited, especially in children with ongoing epiphyseal growth, although a central perforation of the growth plate was shown to have no adverse effects on the growth potential. In cases with complex or multilevel deformities, an additional osteotomy and locking plate fixation could sometimes be a valuable solution in order to avoid external fixation. The low complication rate as well as the reduced compromising of soft tissues and periosteum render intramedullary lengthening nails the state-of-the-art procedure for limb lengthening in combination with deformity correction in patients who meet the anatomical preconditions.

Lengthening in Congenital Femoral Deficiency: A Comparison of Circular External Fixation and a Motorized Intramedullary Nail

BACKGROUND

Circular external fixation for limb-lengthening is associated with frequent and numerous complications. Intramedullary lengthening devices represent a potential advance in limb-lengthening. The purpose of this study was to compare the outcomes of femoral lengthening in pediatric patients treated by either circular external fixation or a motorized intramedullary nail.

METHODS

All patients with a diagnosis of congenital femoral deficiency who had undergone femoral lengthening with either circular external fixation or a motorized intramedullary nail were identified. The motorized intramedullary nail (FITBONE) was used with approval of the U.S. Food and Drug Administration on an individual compassionate-use basis.

RESULTS

Fourteen skeletally mature patients underwent fourteen femoral lengthening sessions using circular external fixation, and thirteen patients underwent fifteen lengthening sessions using the motorized nail. The amount lengthened was similar, with a mean of 4.8 cm (range, 1.0 to 7.4 cm) in the circular fixation group and 4.4 cm (range, 1.5 to 7.0 cm) in the motorized nail group. Complications occurred in all lengthening sessions in all fourteen patients managed with the circular external fixation and in 73% of fifteen lengthening sessions in the thirteen patients managed with the motorized nail. The circular external fixation group averaged 2.36 complications per lengthening session compared with 1.2 per session in the motorized nail group. Twenty-nine percent of the circular fixation group failed to achieve a lengthening goal of at least 4 cm compared with 27% of the motorized nail group who failed to reach the goal. Eight patients had undergone eleven femoral lengthening sessions with circular external fixation prior to undergoing ten lengthening sessions by motorized nail. These patients had a comparable rate of complications with both types of lengthening, but the total number of complications averaged 2.6 per lengthening session with circular external fixation compared with 1.6 per lengthening session with the motorized nail.

CONCLUSIONS

A decreased number of complications was noted with use of a motorized intramedullary nail compared with circular external fixation in pediatric patients undergoing femoral lengthening for congenital femoral deficiency.

LEVEL OF EVIDENCE

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

Adjustment of traumatic femur shortening assisted by an intramedullar skeletal kinetic distractor: a case report

Introduction

Distal comminuted femoral fractures with joint involvement are highly challenging for the surgeon. We present a potential therapeutic concept that aims especially at the treatment of posttraumatic leg length discrepancy.

Case presentation

This case report describes a polytraumatized 19-year-old German woman. Among other injuries she had a third grade open distal comminuted femoral fracture with a long distance metaphyseal osseous defect. As a primary care procedure an external fixation was applied at first. On day 13, an open reconstruction of her distal femur and the articular surface was performed by screw osteosynthesis, shortening and intramedullary nailing. Due to delayed osseous consolidation an autologous cancellous bone grafting was performed twice. In addition to the second cancellous bone graft an allogeneic cortical bone graft was implemented. A 6.5cm posttraumatic leg length shortening after osseous consolidation was the result. The entire leg length shortening was successfully treated 16 months after her accident with the help of an intramedullar skeletal kinetic distractor.

Conclusions

With the help of the current case report of a patient with polytrauma and a third grade open distal comminuted femoral fracture with joint involvement and a long distance osseous defect, we present a potential therapeutic concept that aims especially at the treatment of posttraumatic leg length discrepancy.

Complications of Albizzia femoral lengthening nail: an analysis of 36 cases

Thirty-six cases of femoral lengthening using the Albizzia nail were performed. The indication for lengthening was a congenital malformation, sequellae of trauma, of infection, of radiation therapy, short stature, and vascular malformation. The mean age of the patients was 16 years, the average lengthening achieved was 4.7 cm, and the follow-up period averaged 5.8 years. We found that bone consolidation was achieved faster than with external fixation. The patient's comfort during lengthening as well as the speed of functional restoration also improved. In three cases, the program failed, in six the lengthening was achieved with a second procedure, and eight patients required one ratcheting or more under general anesthesia. In our experience, the Albizzia nail is a simple and effective solution for uncomplicated femoral lengthening.

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.

Leg lengthening with a motorized nail in adolescents : an alternative to external fixators?

Leg lengthening by external fixation is associated with various difficulties. We evaluated eight adolescent patients who underwent leg lengthening with a motorized intramedullary lengthening device. We asked whether this method could reduce the time of hospitalization and rehabilitation and whether the incidence of complications commonly associated with external fixators could be reduced. We compared our preliminary results with those from other reports, with a focus on leg length achieved, time of rehabilitation, and rate of complications. The average leg-length discrepancy was 3.8 cm (range, 3-5 cm). The average lengthening distance was 3.8 cm (range, 2.9-4.7 cm). In six patients, leg lengthening was combined with successful correction of the mechanical axis alignment. The consolidation index averaged 26 days/cm (range, 19-41 days/cm). The average hospital stay was 9.6 days. No bone or soft tissue infections were observed. In comparison to other studies (1.0-2.8 complications/patient), our results suggest that the difficulties commonly associated with external fixators can be reduced with this method. It also allows good angular correction in patients with mechanical axis deviation. These features combined with a short time of hospitalization and rehabilitation make it a promising procedure for limb lengthening.

LEVEL OF EVIDENCE

Level IV Therapeutic study.

Limb lengthening over an intramedullary nail. An animal study and clinical report

With the goal of reducing the duration of external fixation in limb lengthening, the authors investigated the feasibility of limb lengthening over an intramedullary nail that could be statically locked when the desired length was achieved, permitting early removal of the external fixation device. In a preliminary study, 8 minigoats underwent 2.0-cm lengthening of the tibia by means of a uniplanar external fixator. Half of the goats had a reamed nail placed in the tibia at the initial surgery. By 10 weeks after lengthening, there no difference in radiographic, histologic, or biomechanical evidence of bone regeneration was found between the tibiae that were nailed and those that were not. In a following clinical series, 15 patients underwent tibial or femoral lengthening by means of a circular frame fixator with a reamed intramedullary nail in place. The postoperative course was uneventful except for 1 infection. The distraction gaps became ossified from 6 months to 1 year, and only 2 patients needed additional bone graftings. The joint function of the lengthened limb at last followup was good. Gradual limb lengthening with a reamed intramedullary nail in place is safe and effective and allows for early removal of the external fixation device.