Maximizing length with precice nail: a novel technique.

Intramedullary magnetic lengthening nails represents a marked advance in the process of limb lengthening, reducing the complications associated with other methods, and improving patient's comfort. However, one important limitation is its lengthening ability, especially when it comes to short bones. Previous reports have shown techniques that may allow further lengthening but at a cost of having to carry out repeated procedures, requiring the use of other devices, and submitting the patient to long-winded surgical procedures. This report presents a novel technique to achieve lengthening beyond the initial reach of the nail, in a simple and quick procedure, without the need of implanting any additional devices.

Histological differences between various methods of hemiepiphysiodesis: is guided growth really different?

Traditional systems of hemiepiphysiodesis are based on the application of asymmetrical compression to the physis to correct angular deformities. The guided growth method claims to act as a tension plate avoiding compression. The aim of this study was to confirm or refute this claim. Twenty-four White New Zealand rabbits were subjected to a proximal tibial hemiepiphysiodesis using either staples or a plate and two-screws method. Both methods succeeded in producing deformity. The initial existent histological differences between systems became less apparent after 6 weeks of hemiepiphysiodesis, when histological results were very similar. The findings suggest that the eight-plate system produces, like staples, compression of the physis, but the forces are applied more gradually.

Guided growth: the importance of a single tether. An experimental study.

BACKGROUND: During the last few years, the use of the 8-plate as a technique for hemiepiphysiodesis has gained wide acceptance, as it has been shown that it works in a more physiological way than other methods such as staples or transphyseal screws. It has mechanically been compared with a tension band plate, and for this reason, only a single plate is needed. The following study was undertaken to test the 8-plate against the staples and assess factors that can influence the difference in results. METHODS: A prospective experimental study was designed to compare the ability of 2 hemiepiphysiodesis methods, the 8-plate and the double staple, to produce angular deformity in the rabbit's tibia (group I). The variable studied was the variations in the articular line-diaphysis angle at 6 weeks. As the results showed that the 8-plate produced a bigger deformity, a second group was designed (group II) comparing single against double staple, under the hypothesis that the differences observed in the first group could be related to the number of anchors put across the physis and consequently depend on the volume of physis involved by the staples. RESULTS: In group I, the 8-plate produced a bigger angulation at 6 weeks' time than the 2 staples (a difference of 6.5 degrees, P = 0.03). Similarly, in group II, the single staple produced a greater angulation than the 2 staples (difference 6 degrees, P = 0.08). When both groups were compared, no differences in the angulation produced by the 8-plate and the single staple with respect to the 2 staples were found. CONCLUSIONS: These results suggest that one of the reasons why the 8-plate may act in a more "physiological way" (vs. the traditional 2-staple or 3-staple hemiepiphysiodesis) could be the fact that the growth plate is tethered only at a single point. Therefore, the physis retains a major potential for growth and deformity. CLINICAL RELEVANCE: The 8-plate is superior in producing/correcting angular deformity when compared with the traditionally used staples (2 or more) but not when compared with a single staple.

Screw length in the guided growth method.

BACKGROUND: The appearance of the 8-plate as a method for hemiepiphysiodesis has renewed the interest for the use of this technique. However, many questions remain unanswered about the way of action of the guided growth method. Although screw length has been said to play no role, to our knowledge, no clinical or experimental evidence exists. METHODS: An experimental prospective randomized study with 40 WNZ Rabbits aged 8 weeks was conducted. Four experimental groups were established. Each tibia was randomly allocated to one of the following groups: Staples (group 1), 8-plate either using self-taping screws of 9 mm (group 2), or 5 mm lengths (groups 3) and control (group 4). Radiological assessment of the tibial deformity was done in a weekly fashion, and ALDA (articular line-diaphyseal angle) variations at 6 weeks were used as the control variable. RESULTS: The 8-plate as a whole produced a significant bigger deformity than the staples (10°). No significant differences between the two models of the 8-plate were found along the study (3.7°). CONCLUSIONS: The 8-plate has shown to be more efficient in producing angular deformity than staples. However, the length of the screw has showed no role in the 8-plate function.