Transfixation in Slipped Capital Femoral Epiphysis: Long-Term Evidence for Femoro-Acetabular Impingement

Aim: It was the aim of this study to reveal whether and to what extent femoro-acetabular impingement (FAI) was present 10 to 20 years after transfixation of the gliding epiphysis in patients treated for unilateral slipped capital femoral epiphysis (SCFE). Method: Clinical and radiological evaluations were undertaken of 20 patients who were treated with a bilateral transfixation of the epiphysis with screws or Kirschner wires because of mild unilateral SCFE. The Harris hip score, the activity level according to Tegner and Lysholm and the range of motion of both hip joints were noted. An impingement provocation test was performed on both sides. The femoral head-neck junction was qualitatively and quantitatively assessed in anteroposterior radiographs of the pelvis and "cross table" lateral radiographs of both hip joints. Quantitative assessment was achieved by measuring the alpha angle according to Notzli et al. Results: All except one patient showed excellent results in the Harris hip score. The activity levels of the majority of patients, however, were mediocre. There was no difference for flexion, whereas internal rotation and abduction significantly differed between affected and non-affected hips (p = 0.135, p = 0.002 and p = 0.007, respectively). The impingement provocation test was found positive in eight affected and five non-affected hips (p = 0.004). The a angle was significantly different between affected and non-affected hips in the anteroposterior radiographs of the pelvis (86 vs. 61 degrees; p < 0.001), but not so, however, in the "cross table" lateral radiographs (52 vs. 46 degrees; p = 0.145). Conclusion: Clinical evaluation of 20 patients at a mean of 14.9 years after transfixation of the epiphysis revealed some evidence for the presence of FAI in affected hip joints. Radiological evaluation suggests that its localisation is more lateral and less anterior.