Tibial slope changes following guided growth by the eight-plate: A retrospective comparative study.

OBJECTIVE The aims of this study were (1) to investigate the tibial slope (TS) changes following guided growth by the eight-plate and to determine the relationship between the TS change in the sagittal plane and the plate position. METHODS In this retrospective study, children who underwent guided growth by the eight-plate for genu varum or valgum were included. Thirty-eight extremities of 23 children (14 girls and 9 boys; mean age = 9.2 years, age range = 3-17 years) were then divided into two groups according to the plate location in the sagittal plane (anterior or midline). Preoperative and postoperative TS were measured from the medial and lateral tibial plateaus separately. RESULTS The mean follow-up was 34.3 (range = 12-96) months. The mean preoperative and postoperative medial TS were 4.05 ± 5.65 and 0.83 ± 3.91 degrees, respectively, in 18 patients in whom anterior epiphyseal plates were placed (P = 0.004). The mean preoperative and postoperative lateral TS were 4.88 ± 5.33 and 0.11 ± 3.34 degrees, respectively, in 18 patients in whom anterior epiphyseal plates were placed (P < 0.001). The mean preoperative and postoperative medial TS were 4.2 ± 5.19 and 4.9 ± 6.02 degrees, respectively, in 20 patients in whom midline epiphyseal plates were placed (P = 0.532). The mean preoperative and postoperative lateral TS were 5 ± 5.51 and 4.8 ± 5.7 degrees, respectively, in 20 patients in whom midline epiphyseal plates were placed (P = 0.871). Postoperative TS was decreased in anteriorly located eight-plates, and medial and lateral plateau measurement was significant (P = 0.004 and P < 0.001, respectively). Postoperative TS changes in midline-placed eight-plates were not significant regarding the medial and lateral plateaus (P = 0.532 and P = 0.871, respectively). CONCLUSION The results of this study have shown that TS decreases following guided growth by the eight-plate in children in whom plates are placed at the anterior epiphysis. To prevent TS changes, the eight-plate should be placed in the midline position at the sagittal plane. LEVEL OF EVIDENCE Level IV, Therapeutic Study.