Screw length in the guided growth method

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.

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.

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°).

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.