'In-Out-In' K-wires sliding in severe tibial deformities of osteogenesis imperfecta: a technical note

Impact of telescopic intramedullary rodding on the growth of tibia: Comparative experimental study in dogs

INTRODUCTION

The most commonly accepted method of long bone deformity correction in children with osteogenesis imperfecta is surgical realignment with transphyseal telescopic intramedullary rodding. This approach ensures reinforcement of the bone throughout the growth period. Although longitudinal growth does occur with these implants there has been very little work carried out to calculate the effect of such factors as rod position or implant material on growth. We carried out a prospective comparative study on 12 puppies using titanium alloy telescopic tibial rods with and without hydroxyl-apatite coating. The aim of this non-randomized controlled experimental study was to assess the impact of telescopic intramedullary rodding on spontaneous growth of the tibia.

MATERIAL AND METHODS

Twelve mongrel puppies aged of 5 months underwent intramedullary transphyseal rodding of the right tibia. In group I (6 dogs) a titanium telescopic rod was used, in group II (6 dogs) a titanium rod with hydroxyapatite (HA)-coated threaded end was used. The following radiological criteria were assessed before surgery and every month until age of 12 months (natural fusion of physes in dogs): length of tibia, amount of superposition of inner (male) rod into external (female) rod; alteration of anatomy in terms of joint angles (mMPTA, mLDTA, mPPTA, mADTA); positioning of threaded ends in proximal and distal epiphyses and evidence of premature growth arrest. Parameters were compared with left tibia serving as control segment. The null hypothesis was that neither rod position nor implant material altered growth.

RESULTS

The transphyseal rods did not lead to irreversible epiphysiodesis in either group. In group II (HA-coated) some loss of residual length was found in all six dogs, over 7mm (5.9%) in comparison to left intact tibia. In contrast to that, in group I (titanium nail) only one animal (16.7%) demonstrated a tibia length discrepancy of 8mm (4.8%). Eccentric ( posterior) positioning of the rod in the distal epiphysis resulted in a procurvatum deformity (increased anterior distal tibial angle) in both groups. We found no failure of telescoping and no loss of fixation of threaded parts in either epiphyses.

DISCUSSION

The presence of telescopic rods with HA-coated threads parts clearly contributes to inhibition of spontaneous longitudinal growth. We hypothesize that HA stimulates maturation of chondrocytes of growth plate. Our findings regarding the potential adverse effect of thread position in the distal physis demonstrate the importance of attempting to place the rod as central as possible.

CONCLUSION

Titanium alloy telescopic rods did not reveal significant effect on physeal growth in puppies in comparison to HA-coated implants. Transphyseal HA-coated implants did however inhibit growth plate function with mean loss of length of 5.2% compared to the other side. Eccentric positioning of rods relative to center of physis resulted in angular deformity due to irregular growth. There were no cases of mechanical failure or loss of telescopic function with either group of titanium implant.

LEVEL OF EVIDENCE

II; prospective comparative experimental study.

Bone allografting: an original method for biological osteosynthesis and bone reinforcement in children with osteogenesis imperfecta

PURPOSE

Osteogenesis imperfecta (OI) is a genetic disorder responsible for various symptoms including deformities and frequent fractures. Bone allografting is poorly documented in this condition. The objective of this study was to describe our experience and assessments in a consecutive series of OI patients.

METHODS

Thirty-nine lower limb allograft procedures (28 femurs, 11 tibias) were performed in 26OI patients (mean age, 12.9 years). They were classified as type III of Sillence (17), type IV (6), and 3 recessive forms. The indications for surgery were correction of deformity (19), fracture (16), and non-union (4). In all cases, bone allografting was added to reinforce areas of fragility and in 28 cases for osteosynthesis to lock the rotations at the osteotomy site and to avoid screwed metallic plate. The duration of bone consolidation and allograft fusion was assessed. Complications and Gillette functional score were reported.

RESULTS

The mean follow-up was 6.7years (range, 2 to 10 years). On average, bone consolidation was achieved after 3.3 months and graft fusion after 7.7 months. No bone allograft-related complications were observed and there was any secondary displacement. The Gillette functional score was improved in 23 patients and stable in three cases. Complications were reported in two cases: one partial allograft resorption and one delayed consolidation of a non-union. One refracture was observed but after a significant trauma in a child who had regained significant physical activity.

CONCLUSIONS

Bone allografting in children with OI is a reliable method of biological fixation, allowing efficient fusion and contributing to increased bone capital and functional outcome.

Tibial Sliding Elastic Nailing Technique in Moderate-to-Severe Osteogenesis Imperfecta: Long-term Outcomes

BACKGROUND

Osteosynthesis of leg fractures and deformities in children with osteogenesis imperfecta should align the skeleton and overcome its fragility during growth with a telescopic effect. A high rate of mechanical complications is associated with various surgical techniques described in the literature.

PURPOSE

The objective of this work was to assess the long-term clinical and radiologic outcomes of tibial sliding elastic nailing technique.

METHODS

A total of 22 children with an average age of 4.7 years were operated using the technique between 2004 and 2018 unilaterally (6) or bilaterally (16), that is, 38 operations. They were listed according to the Sillence classification into type I (3), III (17), or V (2). The nails were introduced percutaneously at the distal tibial epiphysis through the medial malleolus, and in the prespinal area for the proximal tibial epiphysis. The stainless-steel rods diameter was 1.5 to 2.5 mm, adapted to the size and weight of the patient. Realignment osteotomies were performed if necessary. Radiographic data including the correction of the deformation in the frontal and sagittal planes, as well as the width at mid-shaft of the tibia in the frontal and sagittal planes, were reviewed. Gillette Functional Score, assessment of pain, mechanical and infectious complications were collected.

RESULTS

The average follow-up was 8.6 years. In the frontal plane, preoperative average varus was 8 degrees (maximum, 40 degrees), 5 degrees (maximum, 13 degrees) postoperatively, and 6 degrees (maximum, 12 degrees) at last follow-up. Preoperative valgus was 11 degrees (maximum, 22 degrees), 9 degrees (maximum, 15 degrees) postoperatively, and 9 degrees (maximum, 14 degrees) at the last follow-up. In the sagittal plane, the mean sagittal bowling of the tibia was 32 degrees (4 to 75 degrees) preoperatively, 9 degree (1 to 26 degrees) postoperatively, and 9 degrees (1 to 24 degrees) at last follow-up. The width at mid-shaft of the tibia in the frontal plane was 1.1 cm (0.6 to 1.8 cm) preoperatively and 1.3 cm at the last follow-up (0.7 to 2.0 cm). In the sagittal plane, it was 1.25 cm (0.7 to 2.7 cm) preoperatively and 1.27 cm (0.8 to 2.8 cm) at the last follow-up. Ten patients did not require revision surgery during their follow-up. Sixteen mechanical complications occurred in 12 patients (12 fractures or deformities following a lack of overlap of the 2 rods at an average time of 4.9 years after the initial surgery, 3 prominence of the nail, 1 pseudarthrosis). No infectious complication was reported. Gillette Functional Score was 20.54/65. Fifteen patients were able to walk at last follow-up, and 18 had no painful discomfort.

CONCLUSIONS

The tibial sliding elastic nailing technique provides satisfactory clinical and radiologic results over time. Performed in case of fracture or as a preventive treatment, it allows a good correction of angular deformations. It is particularly suitable for young patients with a narrow medullary shaft.

LEVEL OF EVIDENCE

Level IV-therapeutic study.