Morphology of the knee after guided growth using tension-band devices: a retrospective multicenter study of 222 limbs and 285 implants

Abstract

Background and purpose: Temporary hemiepiphysiodesis by tension-band devices is commonly applied to correct angular limb deformities in children. We aimed to evaluate knee joint morphology after guided growth using these devices.Patients and methods: In a retrospective multicenter study we analyzed standardized anteroposterior long-leg radiographs of 222 limbs (285 implants) of patients treated by temporary hemiepiphysiodesis with either eight-Plates or FlexTacks for coronal angular deformities of the knee joint between 2013 and 2019. Femoral floor angle (FFA), femoral notch–intercondylar distance (FNID), and tibial roof angle (TRA) were measured pre- and postoperatively to assess the central knee joint morphology. Statistical exploratory analyses were performed using linear mixed models, t-tests, Wilcoxon signed-rank test, and Mann–Whitney U test.Results: 217 FlexTacks (femur 106, tibia 111) in 104 children and 68 eight-Plates (femur 61, tibia 7) in 35 children were identified. Median time period under growth guidance was 11 months (range 4–42). No statistically significant change in the FFA was detected (eight-Plate: P = 0.2; FlexTack: P = 0.3). A statistically significant difference of the FNID was found in the eight-Plate group (P = 0.02), but not in the FlexTack group (P = 0.3). While TRA increased in both groups, a statistical significance was observed only in the FlexTack group (P < 0.01).Conclusion: We found minor but clinically irrelevant changes in knee morphology after the treatment.