gms | German Medical Science

Objectives: Temporary Epiphysiodesis (tED) of the distal femur and/or proximal tibia is frequently employed to correct leg length discrepancy (LLD). The procedure may also be applied bilaterally in the treatment of tall stature. However, it remains unclear whether tED may produce epiphyseal deformity and changes in knee joint morphology, and thus lead to secondary malalignment of the lower limb [1].

Methods: We conducted a retrospective analysis of 86 children (33 girls, 53 boys) who had undergone tED between 2009 and 2021. tED was either employed by implantation of eight-Plates™(Orthofix, Verona, Italy) or RigidTacks™ (Merete, Berlin, Germany). Radiological parameters (femoral notch-intercondylar distance (FNID), width of femoral physis (WFP), tibial roof angle (TRA), femoral floor angle (FFA) (Figure 1 [Fig. 1]) [2], as well as the established parameters JLCA, mLDFA, MPTA, and MAD [3]) were evaluated on anteroposterior long-leg standing radiographs carried out prior to implantation and prior to device removal, respectively. The mean follow-up time was 3.4±1.9 years.

Results and conclusion: Mean age at the time of surgery was 12.5±1.7 years. In 75 patients tED was carried out unilaterally to correct LLD. Devices were implanted medially and laterally either at the distal femur (n=18), the proximal tibia (n=10), or both sites (n= 47), according to the origin of the LLD. Eight-Plates™ were employed in 37 (49%) and RigidTacks™ in 38 (51%) of these 75 procedures. Bilateral tED was conducted in 11 patients to reduce excessive predicted height by implantation of RigidTacks™ at the medial and lateral distal femur and proximal tibia, respectively.

In the eight-Plate™ group, the radiological assessment showed a significant change of the WFP (p=0.021), the FNID (p=0.006) and the MAD (p=0.004) after tED, with an absolute change of the MAD of 3.6±4.9 mm. In the RigidTack™ group a significant change was only found for the FNID (p=0.011). Clinically, five revision surgeries had to be performed in the eight-Plate™ group to correct secondary coronal malalignment (four conversions to temporary hemiepiphysiodesis, one correction osteotomy). In the RigidTack™ group surgical conversion to temporary hemiepiphysiodesis was required in six cases.

Distinct changes in joint morphology were more pronounced in the eight-Plate™ group. However, secondary coronal deformities were observed in both groups. Further studies will have to investigate whether these findings may be attributed to differences in the operation technique and implant positioning, and whether the effects are clinically relevant. Nevertheless, tED should cautiously be applied as it may produce significant alterations in coronal alignment and intraarticular deformity.