After PFDO, hip internal rotation on physical examination was lower in group B (52.29°) than group A (60.97°), this was significant (P=0.002). Also, clinical femur anteversion was lower in patients in group B (21°) than in group A (25.42°) (P=0.032). Hip internal rotation at kinematics was similar in groups A (8.12°) and B (3.83°) (P=0.290). Finally, no difference (P=0.812) was observed in hip external rotation on physical examination in groups A (31.53°) and B (31.86°) after PFDO (Table 6).
Although various explanations and treatments for IHR in CP have been described in the last 40 years, femur derotation osteotomy is a well-established procedure that is used to correct excessive femoral anteversion 2–10. Proximal and distal levels of the femur have been used more frequently for derotation osteotomy in CP. The proximal osteotomy has the potential biomechanical advantage of being closer to the deformity, whereas the distal approach is more simple and the use of tourniquet can reduce blood loss 16,17. Kay et al.18 and Pirpiris et al.19 have reported similar results in the correction of IHR in CP patients who have undergone proximal and distal femur derotation osteotomies; however, in the literature, there is no comparison of the procedures performed above (intertrochanteric area) or below (subtrochanteric area) the lesser trochanter at the proximal femur.
In the present study, a significant improvement in the clinical and dynamic parameters was observed in both the groups after PFDO. Aiminian et al.23 reported a reduction in IHR and intoeing gait after PFDO in a group of nine hemiplegic CP patients. Saraph et al.24 reported a reduction in IHR after distal femur derotation osteotomy in a group of 24 patients with diplegic and hemiplegic CP. Õunpuu et al.25 have reported good outcomes after proximal and distal femur derotation osteotomy in 20 CP patients. Good outcomes were observed in the present study as well; however, the group analyzed had a larger number of patients (53) than the groups studied by Aiminian et al.23, Saraph et al.24, and Õunpuu et al.25.
In the present study, osteotomies performed on the intertrochanteric area resulted in better correction of clinical hip internal rotation and femur anteversion than procedures performed on the subtrochanteric area. These results may be attributed to the fact that surgical intervention above the lesser trochanter has a greater corrective potential because it is closer to the femoral neck. Static IHR in CP is related to excessive anteversion, which comes from the femoral neck 2,16. In the literature, we did not find any report on the influence of iliopsoas at hip rotation in CP; however, osteotomies performed above the lesser trochanter can produce some degree of elongation of the iliopsoas tendon. In our study, we observed better correction of clinical hip internal rotation when iliopsoas was potentially elongated.
The groups analyzed were matched in terms of the sex distribution, GMFCS and type of CP, follow-up time, and severity of clinical and kinematics parameters before surgery, except for the diagnosis of symmetric diplegic CP, which was more frequent in the patients in group A. The fact that previous hip adductor tenotomy was more frequent in patients who had undergone femur osteotomy above the lesser trochanter could be attributed to the better correction of hip internal rotation. Spasticity and contracture of hip adductors have been described as potential causes of hip internal rotation in CP, and tenotomy of these structures is a treatment option mentioned in the literature 5,6,10.
PFDO was performed later in group B than group A and this may have also influenced the results, because some degree of recurrence might have occurred in patients in group A. Kim et al.26 reported that recurrence of IHR in CP after femur osteotomy is more likely to occur when surgery is performed before the age of 10 years. However, Õunpuu et al.25 did not observe recurrence of IHR in a group of CP patients (mean age at osteotomy 8.1 years) who had undergone femur rotation osteotomy after 5 years of the index procedure.
The present study has limitations. As discussed above, the better results observed in group B could have been influenced by age at surgery and previous hip adductor procedures. Despite this, we believe that the present study has important contributions for the field, having determined outcomes after PFDO in a larger and more uniform group of patients.
Reduction in clinical hip internal rotation and femur anteversion was greater in patients who had undergone intertrochanteric osteotomies; however, significant improvement in kinematics was observed in both groups after the surgical procedures.
There are no conflicts of interest.
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