Validation of a Genu Valgum Model in a Rabbit Hind Limb

Abstract

Numerous techniques exist to correct pediatric angular deformity by asymmetrically inhibiting physeal growth. Despite decades of surgical experience, little is known about the determinants of success or failure of temporary hemiepiphysiodesis. We lack a basic understanding of tolerances and kinematics of the surgically restrained physis. Furthermore, little is known about the influence of implant design and placement on efficacy of deformity correction and rebound growth. We have undertaken a pilot research study with the goal of producing genu valgum in New Zealand white rabbits. This report comprises our initial experience and observations in performing hemiepiphysiodesis with staples and 2-hole plate techniques. The experimental hypotheses proposed by this article are as follows: (1) a staple or plate applied to the proximal lateral tibial physis of a rabbit hind limb will reliably create a valgus deformity of the knee; (2) the plate or staple will create this deformity without permanently damaging the proximal tibial physis; and (3) provided the implant remains in situ, there will be no difference between the plate and staple constructs with respect to the magnitude or rate of deformity produced. Further studies will aim to use this model to investigate technical issues related to physeal instrumentation.

Hemiepiphysiodesis: similar treatment time for tension-band plating and for stapling

“…One reason for the overall outcome of stapling and tension-band plating appearing equal could be that the biological effect of both techniques is quite similar, despite a theoretical advantage in favor of tension-band plating. Several experimental studies have compared the techniques in both rabbit and porcine models (Mast et al 2008, Goyeneche et al 2009, Burghardt et al 2011, Kanellopoulos et al 2011). Migration of staples was reported in several of these studies.…”

Rotational deformities of the long bones can be corrected with rotationally guided growth during the growth phase

“…According to various clinical and experimental studies investigating the effect of temporary epiphysiodesis on coronal plane deformities, changes that have been achieved may later return to baseline after implant removal, due to a rebound effect (Stevens 2007 , Mast et al. 2008 , Yilmaz et al. 2014 ).…”

“…Mast et al. ( 2008 ) created tibial valgus deformity in rabbits and they reported that the deformity began to develop 1 week after the implantation of the plate or staple. In our study, because the plates were oblique, they could have led to a coronal plane deformity once they became parallel to the long axis of the tibia.…”

Similar growth plate morphology in stapling and tension band plating hemiepiphysiodesis: A porcine experimental histomorphometric study

“…Four experimental animal studies have been published on the use of tension band plating 10–13. In one animal study rabbit hind limbs were allocated to either stapling, tension band plating, sham surgery, or no surgery 11. Staple migration was observed after 2 weeks treatment.…”

“…Tension band plating seems to be safe and an approximately 30% faster correction rate was noted in a recent article 9. Several experimental studies investigated the radiological effect of stapling and tension band plating10–13 and data are conflicting. The histomorphometric effect of the tension band plating technique is to our knowledge yet to be investigated.…”