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Journal of Pediatric Orthopaedics B:
doi: 10.1097/BPB.0b013e3283571796
Cerebral Palsy

Does the level of proximal femur rotation osteotomy influence the correction results in patients with cerebral palsy?

de Morais Filho, Mauro Césara,b,c; Neves, Daniella L.a,b; Abreu, Fábio P.a; Kawamura, Cátia M.b; dos Santos, Carlos Albertoa,c

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Author Information

aDepartment of Pediatric Orthopaedic, Cerebral Palsy Clinic

bGait Laboratory, Association for the Care of Disabled Children (AACD)

cDepartment of Orthopedic, Palsy Group of the Institute of Orthopedics and Traumatology (IOT), Division of Rehabilitative Medicine (DMR), University of São Paulo (USP) São Paulo, SP, Brazil

The study was conducted at the Association for the Care of Disabled Children (AACD), São Paulo, SP, Brazil.

Correspondence to Mauro César de Morais Filho, MD, Rua Dr. Bacelar 317 apt 84, São Paulo, SP 04026001, Brazil Tel: +55 115 576 0920; fax: +55 115 576 0660; e-mail mfmorais@terra.com.br

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Abstract

Proximal femur external rotation osteotomy is a common procedure used for the correction of increased femur anteversion and hip internal rotation in cerebral palsy (CP). Different levels of osteotomy have been used at the proximal femur, but there are no studies in the literature comparing the results in CP. Patients with spastic CP, Gross Motor Function Classification System (GMFCS) I–III, who had undergone a femoral rotational osteotomy from August 1998 to August 2007, and with complete documentation at gait laboratory were included in the study. Patients were divided into two groups according to the level of osteotomy at the proximal femur. Group A [Dynamic Compression Plate (DCP) group] included 24 patients (36 osteotomies), and the osteotomy in this group was performed below the lesser trochanter. In Group B (Blade Plate group), 29 patients (35 osteotomies) were included and the level of osteotomy was above the lesser trochanter. Age at surgery, sex distribution, follow-up time, previous surgical procedures, surgical procedures performed in the same session as femur osteotomy, GMFCS level, topographic classification, clinical findings (internal and external hip rotation, and femur anteversion), and hip rotation at kinematics were analyzed and the results were compared between groups. Groups A and B were matched in terms of the sex distribution, follow-up time, GMFCS levels, and severity of clinical findings and hip internal rotation at kinematics before surgery. The mean age of the patients at surgery was 9.24 years in group A and 12 years in group B, and this difference was significant on performing statistical analysis (P=0.004). The number of patients who had undergone previous hip adductors’ tenotomy was higher in group B (P=0.036). Improvements in clinical and kinematics parameters were observed in both groups after femur osteotomy (P<0.001). The increase in hip external rotation at clinical examination and the reduction in hip internal rotation at kinematics did not show differences between groups A and B on performing statistical analysis. However, reduction of femoral anteversion (P=0.032) and hip internal rotation (P=0.002) were more remarkable in group B. In conclusion, reduction of hip internal rotation and femur anteversion at physical examination were more significant in patients with intertrochanteric osteotomies; however, improvement in kinematics was observed in both groups after surgical procedures.

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Introduction

Internal hip rotation (IHR) is a common problem in cerebral palsy (CP) and it is the major cause of intoeing gait 1–3. It is characterized by poor foot clearance in the swing phase and excessive shoe wear 4. Factors leading to IHR in patients with CP may be dynamic or static. Dynamic causes are generally related to spasticity or muscle imbalance, and hip adductors, medial hamstrings, glutei medius and minimus, and fascia lata tensor have all been implicated as potential causes of IHR 5–10. The persistence of muscle imbalance and deficient control, as well as the lack of regression of femur anteversion during early childhood, have been reported as causes of static IHR in CP 11.

Regression of IHR during musculoskeletal growth is unlikely in CP and the response to conservative management is poor, which makes surgical intervention a treatment option 1,12,13. Femur derotation osteotomy has been used frequently to correct static IHR in CP and the indications for this procedure are based on clinical and dynamic criteria 4,14,15.

Femur derotation osteotomy is generally performed at the proximal or the distal level. Proximal osteotomy has the potential biomechanical advantage of being closer to the deformity, whereas the distal approach is more simple and the use of a tourniquet can reduce blood loss 16,17. Kay et al. 18 and Pirpiris et al. 19 have reported similar results of correction of IHR in CP patients with proximal and distal femur derotation osteotomies. A minimally invasive technique for femur derotation osteotomy in CP, using closing corticotomy and fixation with titanium elastic nails, was described by Thompson et al. 20, with a reduction in the operation time and blood loss, and significantly improved time to mobilization when compared with conventional single-event multilevel surgery.

In our hospital, femur derotation osteotomy is performed proximally. If the hips do not show dislocation, surgeons can perform the osteotomy at intertrochanteric (internal fixation with a blade plate) or subtrochanteric (internal fixation with straight lateral dynamic compression plate) areas; however, so far no data are available comparing these approaches. Also, there are no reports in the literature.

The aim of the study was to compare the clinical and kinematic results of proximal femur derotation osteotomy (PFDO) performed at intertrochanteric and subtrochanteric areas to determine whether these techniques lead to similar results in the correction of IHR in CP.

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Materials and methods

This study was approved by our hospital committee for ethics in research under protocol number 046/2006. Medical records and gait laboratory data were reviewed retrospectively. Patients included had been diagnosed as having spastic CP, Gross Motor Function Classification System (GMFCS) levels I–III, who had undergone femur derotation osteotomy between August 1998 and August 2007, with complete documentation at the gait laboratory. Patients eligible for inclusion had been subjected to gait analysis no more than 18 months in advance of surgery and after discharge from rehabilitation.

Fifty-six patients fulfilled the inclusion criteria. Patients who had undergone osteotomy at the distal femur (n=3) were excluded and the final number of patients analyzed was 53. Patients were divided into two groups according to the level of osteotomy at the proximal femur. Group A [Dynamic Compression Plate (DCP)] included 24 patients (36 osteotomies) and the osteotomy in this group was performed below the lesser trochanter (subtrochanteric). In Group B (Blade Plate), 29 patients (35 osteotomies) were included and the level of osteotomy was above the lesser trochanter (intertrochanteric). Age at surgery, sex distribution, follow-up time, previous surgical procedures, surgical procedures performed in the same session as femur osteotomy, GMFCS level, topographic classification, clinical findings (internal and external hip rotation, and femur anteversion), and mean hip rotation during stance phase at kinematics were analyzed before and after the surgical procedures, and the results were compared between groups (Figs 1 and 2).

Fig. 1
Fig. 1
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Fig. 2
Fig. 2
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PFDO was chosen on the basis of clinical history, physical examination, and 3-D gait analysis. Patient complaints of falls, internal foot deviation, and shoe wear also played a role in the decision. Physical examinations were performed by a pediatric orthopedic surgeon (M.C.M.F.) and a physical therapist (C.M.K.) of the gait laboratory staff. The pediatric orthopedic surgeon evaluated clinical internal and external hip rotation, and femur anteversion (Ruwe’s test, 21) with the patient in the prone position and quantification of the range of motion was carried out by the physical therapist using a manual goniometer. IHR more than 60°, external hip external rotation less than 40°, and femoral anteversion more than 20° were indications for osteotomy.

During the 3-D gait analysis performed at our facility, patients were required to walk on an 8-m walkway at their own pace after photo-reflective marker placement 22. Kinematics was recorded using six VICON 370 systems (Vicon, Oxford, UK) cameras until August 2008. Thereafter, eight QUALISYS OQUS cameras (Qualisys, Gothenburg, Sweden) were used. For data processing, the VICON Clinical Manager software (Oxford Metrics, Oxford, UK) was used. Ten gait cycles were collected from each patient and a cycle average was used for analysis. A kinematics value more than 1 SD above the normal database (IHR>11°) was considered an increase.

All osteotomies involved a standard lateral approach for the proximal femur, and surgeons chose either a straight lateral DCP or a blade plate as the fixation device, according to their technical preference. With DCP, the osteotomy level was below the lesser trochanter (subtrochanteric), as opposed to above the lesser trochanter (intertrochanteric) with blade plates. The choice of the level of osteotomy was not random. The surgical approach in CP changed in 1995 in our hospital after Dr Gage’s visit. We started using gait analysis during the decision-making process and multilevel surgery as well. The use of a blade plate for fixation of femur osteotomy was a part of these changes. Surgeons trained at our hospital after 1994 are more familiar with multilevel surgery and the use of a blade plate for proximal femur rotation osteotomy.

The surgical technique of PFDO using a blade plate in our hospital involves the identification of the lesser trochanter and psoas insertion routinely. Femur osteotomy was performed proximal to the insertion of the psoas tendon, after it was identified. Two Kirschner wires on each side of the osteotomy served as guides to provide rotation control. The therapeutic goal was to achieve 10° more external than internal rotation by the end of the procedure. Any requirement for postoperative immobilization of lower limbs was determined by procedures performed concomitantly. With isolated PFDO, knee immobilizers were used routinely for 2 weeks after surgery to ensure alignment of lower limbs and to avoid secondary deformities. Rehabilitation and weight bearing were started 4 weeks after the surgical procedure.

The relative frequency and distribution of qualitative variables of the groups were compared using the two proportions equality test; for quantitative variables, the Mann–Whitney test was used. The Wilcoxon test was used for comparisons of quantitative variables before and after surgical procedures. Statistical significance was set at P equal to 0.05 for all tests.

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Results

In group A, 12 patients were males (50%) and 12 (50%) were females. In group B, there were 17 males (58.6%) and 12 (41.4%) females, respectively. The results did not differ significantly by groups (P=0.530). PFDO was performed at a mean age of 9.24 years (group A) and 12 years (group B), and this difference was significant on statistical analysis (P=0.004). The follow-up durations of 41 months (group A) and 44 months (group B) were comparable (P=0.844).

The topographic diagnosis of spastic diplegic CP, without lower limb asymmetry, was made in 50 and 17.2% of the patients in groups A and B, respectively. This difference was significant (P=0.011). Spastic diplegic CP with asymmetric lower limb impairment was diagnosed in 45.8% of the patients in group A and 69% of the patients in group B, whereas spastic hemiplegia was diagnosed in 4.2 and 13.8% of the patients in groups A and B, respectively. These intergroup variations did not differ significantly (spastic asymmetric diplegia, P=0.089; and spastic hemiplegia, P=0.233).

In terms of GMFCS levels of groups A and B, level I was found in 16.6 and 17.2% (P=0.956), level II in 41.7 and 41.4% (P=0.983), and level III in 41.7 and 41.4% (P=0.983) of the patients, respectively.

Hip adductors tenotomy was more prevalent in group B (22.9%) than group A (5.6%) before PFDO (P=0.036). The distribution of other previous procedures was similar for groups A and B. For 66.7% (24/36) of lower limbs in group A and 62.9% (22/35) in group B, no surgical procedures before PFDO were performed (P=0.737) (Table 1).

Table 1
Table 1
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Psoas lengthening over the pelvic brim (P=0.002) and rectus femoris transfer (P=0.001) were more frequent in group B than group A. PFDO as a single procedure was performed for 11.1% of the lower limbs of patients in group A and 11.4% in group B (P=0.966) (Table 2).

Table 2
Table 2
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No difference was found in preoperative clinical (hip internal rotation, hip external rotation, and femur anteversion) and kinematic (hip internal rotation) parameters between groups A and B before PFDO (Table 3).

Table 3
Table 3
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A significant (P<0.001) reduction was observed in hip internal rotation and femur anteversion on physical examination and hip internal rotation at kinematics, and increase in hip external rotation on physical examination after PFDO in groups A and B (Tables 4 and 5).

Table 4
Table 4
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Table 5
Table 5
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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).

Table 6
Table 6
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Discussion

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.

O’Sullivan 3 reported that the results of soft tissue procedures at hip internal rotation in CP are unpredictable and often unsatisfactory. Kay et al. 18 and Pirpiris et al. 19 reported in 2003 that the effect of soft tissue procedures in the transverse plane was mild and femur derotation osteotomy was the best option for the correction of IHR. However, in the present study, more significant reduction in clinical IHR was observed after hip adductor tenotomy and this could be related to improvement in muscle imbalance and easier fragment rotation during surgery after adductors’ release.

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.

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Conclusion

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.

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Acknowledgements
Conflicts of interest

There are no conflicts of interest.

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References

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Keywords:

cerebral palsy; femur osteotomy; internal hip rotation

© 2013 Lippincott Williams & Wilkins, Inc.

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