Experimental study of progressive tibial lengthening in dogs using the Ilizarov technique. Comparison with and without associated intramedullary K-wires

Combined lengthening for acquired leg length discrepancy: Are there advantages of hydroxyapatite-coated intramedullary nails?

INTRODUCTION

The aim of this multicenter prospective study was to analyze the outcomes of bone lengthening by external fixator associated with flexible intramedullary nailing (FIN) in acquired limb length discrepancy (LLD).

HYPOTHESIS

Hydroxyapatite (HA)-coated FIN enables reduced External Fixation Index in limb lengthening for acquired leg length discrepancies in comparison to non-HA-coated FIN.

MATERIAL AND METHODS

This study included 54 patients (mean age, 17.9 years) operated on for femoral or tibial lengthening by combined technique (External fixator with FIN) for acquired length discrepancy. Titanium non-HA-coated FIN (29 cases) or HA-coated FIN (25 cases) were used. The factors that might influence external fixation index, complication occurrence and outcome were analyzed: age, amount of lengthening, nail diameter, HA-coating vs. non-HA-coated nails.

RESULTS

The mean External Fixation Indexes (EFI) of groups compared for non-HA-coated nails vs. HA-coated nails were not significantly different: 26.5 d/cm and 27.2 d/cm in femoral lengthening and 34.9 d/cm and 31.7 d/cm in tibial lengthening. Positive correlation between the "nail diameter/inner distance between cortices at osteotomy site" ratio and EFI in tibial lengthening was revealed (p=0.034). The nail types and the "nail diameter/medullary canal diameter" ratio interact and have significant simultaneous effect on EFI in femoral lengthening (p=0.021).

DISCUSSION

The results of this study revealed no differences with regards to EFI using HA-coated or non-HA-coated titanium FIN in lengthening for acquired leg-length discrepancies. Combined technique allowed reduced EFI and avoided major complications. Both non-HA-nail and HA-coated nail lengthening provided good and excellent outcomes.

LEVEL OF EVIDENCE

III; (controlled trial without randomization) prospective comparative study.

The role of external fixation in paediatric limb lengthening and deformity correction

Limb deformity and shortening remains a common presenting complaint in paediatric orthopaedics. The ability to restore length, alignment with consistent bone formation allows standardised treatment in these difficult conditions. The use of an external fixator produces a stable construct which allows manipulation of the bone segments, with a controlled rate and rhythm. Deformity analysis permits the surgeon to plan osteotomy levels and frame application to produce accurate correction. Complications, especially in congenital conditions remain an issue and modification of the treatment is required to try and reduce their incidence. New types of fixators, the latest being hexapod frames, have increased the versatility in deformity correction. The aim of this paper is to review the use of external fixators in elective paediatric orthopaedics and highlight the latest changes in technique and application for the limb reconstruction surgeon.

Bone Formation and Adaptive Morphology of the Anterior Tibial Muscle in 3-mm Daily Lengthening Using High-Fractional Automated Distraction and Osteosynthesis with the Ilizarov Apparatus Combined with Intramedullary Hydroxyapatite-Coated Wire

Purpose

We studied osteogenesis and morphofunctional features of the anterior tibial muscle using 3-mm high-frequency automated lengthening with the Ilizarov apparatus alone and in combination with intramedullary nailing.

Material and Methods

Tibia was lengthened with a round-the-clock automated distractor at a 3-mm daily rate for 10 days in 16 mongrel dogs. In group 1 (n = 8), a 1.8-mm intramedullary titanium wire coated with hydroxyapatite was introduced into the tibial canal followed by Ilizarov frame mounting and transverse osteotomy of the diaphysis. Distraction mode was 0.025 mm x 120 increments a day. In group 2 (n = 8), distraction mode was the same but nailing was not used. Bone formation and the anterior tibial muscle were studied at two time points: (1) upon distraction completion; (2) three months after the apparatus removal. Bone formation was studied radiographically. Muscle preparations were examined histologically and stereomicroscopically.

Results

There was a threefold reduction in the distraction time in both groups. Consolidation took 13.83±4.02 days in group 1 and 33.7±2.4 days in group 2. Muscle macropreparations of the experimental limb in group 1 at study time points did not show significant differences from intact tissues. Muscle histostructure in both groups was characterized by activation of angiogenesis and myohistogenesis, but the volumetric density of microvessels in the lengthening phase was three times higher in group 1.

Conclusion

Combined technology significantly reduces the total lengthening procedure and does not compromise limb functions. Intramedullary HA-coated wires promote faster bone formation. The muscle was able to exhibit structural adaptation and plasticity of a restitution type.

Evaluation of the external fixator TrueLok Hexapod System for tibial deformity correction in children

BACKGROUND

Tibial deformities are common in paediatric orthopaedic practice. Correcting multiplanar tibial deformities associated with lower limb length discrepancy can be challenging. Hexapod external fixation with gradual correction has been proven effective in this situation.

OBJECTIVE

To assess clinical and radiological outcomes of gradual tibial deformity correction using the external fixator TL-HEX™ (Orthofix) in children.

HYPOTHESIS

TL-HEX™ is effective in correcting tibial deformities in children.

PATIENTS AND METHODS

This multicentre retrospective study collected data from the medical files of 26 patients with 31 tibial deformities treated by gradual correction using TL-HEX™. The tibial deformities were due to congenital defects in 11 (35%) cases, Blount's disease in 9 (29%) cases, pseudo-achondroplasia in 4 (13%) cases, and other causes in 7 (23%) cases. Mean age at surgery was 11.9 years. In each patient, antero-posterior long leg radiographs obtained pre-operatively and at last follow-up were used to measure parameters including the mechanical axis deviation (MAD), medial proximal tibia angle (MPTA), and leg length discrepancy (LLD).

RESULTS

The mean healing index was 39.3 days/cm (range, 32-58 days/cm). The overall complication rate was 61%, with 11 unplanned visits. Superficial pin tract infection was the most common complication. Significant decreases between the pre-operative and post-operative assessments occurred in mean MAD (from 32.1mm to 10.2mm, P<0.001) and mean LLD (from 36.8mm to 9.1mm, P<0.001). Patients who underwent proximal tibial osteotomy had a significant improvement in MPTA, from 80.6° to 88.5° (P=0.006).

DISCUSSION

This is the first clinical study specifically designed to assess outcomes of TL-HEX™ limb lengthening and deformity correction. MAD, MPTA, and LLD were significantly improved at last follow-up. MAD was greater than 10mm at last follow-up in only 11patients. The complication rate was similar to those reported with other external fixators. TL-HEX™ is effective in the management of tibial deformities in children.

LEVEL OF EVIDENCE

IV (retrospective study).

Current approaches to flexible intramedullary nailing for bone lengthening in children

Limb-length discrepancies and extremity deformities are among the most common non-traumatic orthopaedic conditions for which children are hospitalised. There is a need to develop new treatment options for lower-limb length discrepancy in order to ameliorate treatment outcomes, avoid or reduce rates of complication and provide early rehabilitation. The authors report on the basic principles, experimental and clinical data, advantages, problems and complications of a combined technique associating the Ilizarov method and flexible intramedullary nailing (FIN) in limb lengthening and deformity correction in children. They describe features of the use of hydroxyapatite-coated intramedullary nails in patients with certain metabolic bone disorders and in cases where bone consolidation has been compromised. The advantages of bone lengthening using a combined technique (circular fixator plus FIN) are a lower healing index, quicker distraction-consolidation, a reduced rate of septic and bone complications, the ability to correct deformities gradually and the increased stability of bone fragments during the external fixation period and after frame removal.

Reamed Intramedullary Nailing has an Adverse Effect on Bone Regeneration During the Distraction Phase in Tibial Lengthening

BACKGROUND

The lengthening over nail (LON) technique has gained popularity because it enables shorter periods of external fixation, prevents deformities during lengthening, and reduces the risk of refracture after removal of the frame compared with the classic Ilizarov method. However, it is not clear if the violation of endosteal blood supply by reamed intramedullary nailing in the LON technique has a negative effect on bone regeneration or a positive effect by compensatory enhancement of periosteal circulation.

QUESTIONS/PURPOSES

The purposes of this study were to (1) compare the amount of regenerate bone during the distraction phase between two tibial lengthening techniques, the LON technique and lengthening and then nail (LATN) technique; and (2) compare callus shape at the end of the distraction phase using the classification of Li et al.

METHODS

This is a retrospective study comparing two treatment groups. Between September 2011 and June 2013, 120 patients underwent bilateral lower leg lengthening for familial short stature with either the LON or LATN technique, and were considered potentially eligible for inclusion in this retrospective, comparative study. During this same period, LON and LATN techniques were used in other patient populations, but all patients with familial short stature were considered for inclusion in the study. The specific contraindications for LON were diameter of the isthmus of the tibia narrower than 8 mm, length of the tibia shorter than 270 mm, and alignment of the lower extremity in valgus; in patients without these specific contraindications to LON, patients were offered either LATN or LON after counseling regarding the advantages and disadvantages of each procedure. The proposed advantages of LATN were shorter healing index and more stable internal fixation which might lead to earlier full weightbearing, whereas proposed disadvantages were a greater chance for deep infection, more deformity during lengthening, and subsequently longer external fixator period for correction. The groups were comparable in terms of age, sex distribution, smoking history, BMI, distraction rate, and final length gain. A longer period of external fixation was necessary in the LATN group, related to the relative stability of the segment without an intramedullary nail. Patients with tibial lengthening with the LON technique (31 patients, 62 tibiae) were compared with patients who had the LATN technique (89 patients, 178 tibiae) regarding the amount of bone regeneration at the anterior, posterior, medial, and lateral cortices of the lengthened area for each at 4, 8, and 12 weeks postoperatively using a pixel value ratio method. In addition, both groups were compared for callus shape and type at the end of the distraction phase (LON, 3.4 ± 0.06 months; LATN, 4.2 ± 0.05 months).

RESULTS

The pixel value ratios of the anterior, posterior, medial, and lateral cortices in the LON and LATN groups were 0.78 ± 0.06 and 0.74 ± 0.05; 0.82 ± 0.08 and 0.76 ± 0.05; 0.75 ± 0.06 and 0.72 ± 0.05; and 0.85 ± 0.06 and 0.82 ± 0.06, respectively at 4 weeks postoperatively(p value > 0.500 for all); 0.75 ± 0.05 and 0.77 ± 0.04; 0.78 ± 0.05 and 0.89 ± 0.04; 0.73 ± 0.05 and 0.82 ± 0.05; and 0.78 ± 0.06 and 0.88 ± 0.03, respectively at 8 weeks postoperatively (p value < 0.001 for the posterior, medial, and lateral cortices); 0.72 ± 0.05 and 0.76 ± 0.03; 0.75 ± 0.07 and 0.89 ± 0.03; 0.71 ± 0.05 and 0.82 ± 0.03; and 0.78 ± 0.06 and 0.91 ± 0.03, respectively at 12 weeks postoperatively (p value < 0.001 for the posterior, medial, and lateral cortices). A greater percentage of tibiae having the generally favored fusiform-shaped callus were seen with the LATN technique (61 of 178 segments) than with the LON technique (four of 62 segments; p < 0.001). There were no tibia showing the inferior concave, lateral, or central-shaped callus with the LATN technique, whereas eight tibiae (eight of 62 segments) showed concave-shaped callus with the LON technique (p < 0.001).

CONCLUSIONS

The potentially negative effect on callus regeneration from the concomitant use of reamed intramedullary nailing during the LON technique should not be overlooked. Based on our study, LATN may be a better choice for patients willing to accept the longer period of external fixation.

LEVEL OF EVIDENCE

Level III, therapeutic study.