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Asymmetric pelvic and hip rotation in children with bilateral cerebral palsy: Uni- or bilateral femoral derotation osteotomy?
Gait & Posture 41 (2015) 670–675
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Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Asymmetric pelvic and hip rotation in children with bilateral cerebral palsy: Uni- or bilateral femoral derotation osteotomy? M. Niklasch a, L. Do¨derlein b, M.C. Klotz a, F. Braatz c, S.I. Wolf a, T. Dreher a,* a
Pediatric Orthopaedics and Foot Surgery, Clinic for Orthopedics and Trauma Surgery, Center for Orthopedics, Trauma Surgery and Spinal Cord Injury, Heidelberg University Hospital, Schlierbacher Landstr. 200a, 69118 Heidelberg, Germany b Orthopaedic Hospital for Children, Behandlungszentrum Aschau GmbH, Bernauerstr. 18, 83229 Aschau i. Chiemgau, Germany c Klinik fu¨r Unfallchirurgie und Orthopa¨die, Universita¨tsmedizin Go¨ttingen, Robert-Koch-Str. 40, 37075, Go¨ttingen, Germany
A R T I C L E I N F O
A B S T R A C T
Article history: Received 19 July 2014 Received in revised form 14 January 2015 Accepted 23 January 2015
Internal rotation gait is common among children with bilateral cerebral palsy. However, despite bilaterally increased femoral anteversion asymmetric internal rotation gait is often found. Femoral derotation osteotomy (FDO) is commonly performed bilaterally. Variable functional outcomes are reported especially in cases with mild internal hip rotation during gait and abnormal preoperative pelvic rotation. A major question is if a unilateral treatment of the more involved side in asymmetric cases leads to a comparable or even superior outcome. One hundred and nine children with spastic bilateral CP treated with FDO with pre- and 1-year postoperative 3D gait analysis were retrospectively collected. The asymmetry was calculated from the preoperative difference between both limbs in hip rotation obtained by 3D gait analysis. Twenty-eight children with asymmetry larger than 208 were selected and classified into two groups, according to whether they obtained a unilateral or bilateral FDO. Preoperative clinical examination and pre- and postoperative hip and pelvic rotation in gait analysis on the more and the less involved side did not differ significantly between both groups. Interestingly, in both groups, hip rotation did not change significantly in less-involved limbs, although intraoperative derotation averaged 258. After unilateral FDO a significant change in pelvic rotation resulted, whereas this was not found after bilateral FDO. The results of this study suggest that unilateral FDO in children with asymmetric internal rotation gait leads to a comparable functional outcome compared to bilateral treatment. Furthermore, it was shown for the first time that considering the asymmetry has a positive effect on pelvic rotation. ß 2015 Elsevier B.V. All rights reserved.
Keywords: Cerebral palsy Femoral derotation osteotomy Asymmetric internal rotation gait Pelvic rotation
1. Introduction Internal rotation gait (IRG) is common among children with cerebral palsy (CP) [1]. It is often thought to be a bilateral problem, as it is in the normal population [2], and associated with bilaterally increased femoral anteversion [3]. However, it could be demonstrated, that IRG is predominantly a unilateral phenomenon in patients with bilateral CP [4]. IRG often causes problems with foot clearance in the contralateral leg and tripping. A primary cause of IRG is transverse plane deformity of the pelvis, femur, tibia, and/or foot [4].
* Corresponding author. Tel.: +49 6221 5626384; fax: +49 6221 5626348. E-mail addresses: [email protected], [email protected] (T. Dreher). http://dx.doi.org/10.1016/j.gaitpost.2015.01.024 0966-6362/ß 2015 Elsevier B.V. All rights reserved.
Femoral derotation osteotomy (FDO) is seen as the golden standard for the treatment of increased femoral internal rotation [3,5–9]. The osteotomy can be performed either proximally as intertrochanteric osteotomy or distally as supracondylar osteotomy with comparable static and functional results [3,7,9,10]. FDO corrects increased femoral anteversion and is commonly performed bilaterally since the anteversion angle is often increased bilaterally. However, many authors reported variable outcomes after FDO, especially in cases with mild IRG [5,11] and abnormal pelvic rotation preoperatively [3,9,12,13]. A major issue in the treatment is how to identify and address cases with asymmetric internal hip rotation during gait. In patients with asymmetrical forms of bilateral CP the most frequent pattern is an increase in internal hip rotation and pelvic retraction on the more involved side [9,13,14]. Kay et al. [12] reported, that children with bilateral CP and bilateral IRG, who were derotated bilaterally
M. Niklasch et al. / Gait & Posture 41 (2015) 670–675
tended to be undercorrected on the side with preoperative pelvic retraction and overcorrected on the other side. A correction of pelvic retraction could be achieved after unilateral FDO in patients with unilateral CP [9,13,15], but not after bilateral FDO in patients with bilateral CP [3,13]. Previous investigations could outline that in patients with mild IRG overcorrection is a major problem and considered FDO to be done only if at least 158 of internal rotation are present in gait analysis [5,16]. It remains unresolved if in the patients with asymmetric IRG, where the mild-involved side has 158 or less of hip internal rotation but a bilaterally increased femoral anteversion should undergo bilateral FDO. The purpose of the current study was therefore to evaluate if unilateral treatment is comparable or even superior to bilateral treatment in patients with asymmetric internal hip rotation during gait. 2. Materials and methods Standardized 3D gait analysis and clinical examination are routinely performed for all ambulatory patients with CP both before and 1 year after surgery. For the present cohort study, all ambulatory children with bilateral CP (GMFCS level I–III), increased femoral anteversion, and IRG, who were treated with FDO in the context of single-event multilevel surgery between 2000 and 2011, were selected retrospectively from the gait laboratory database. The amount of intra-operative derotation is routinely measured with derotational K-wires and documented in the surgical report. Patients who underwent additional tibial (de-)rotational osteotomy were excluded from this study. One hundred and eight children with a mean age of 10.7 (3.2) years [range: 3.8–17.8] matched these criteria. The asymmetry between both limbs of each subject was calculated from the preoperative difference between the two limbs concerning hip rotation in stance obtained by 3D gait analysis. All children with bilateral CP and an asymmetry in hip rotation larger than 208 were selected. Twenty-eight children fit these criteria and were retrospectively classified into two groups: one group obtained a unilateral FDO (12 patients); the other group underwent bilateral FDO (16 patients). Accordingly, improvement in asymmetry was calculated as the difference between pre- and postoperative asymmetry. FDO was performed either distally as supracondylar osteotomy or proximally as intertrochanteric osteotomy. The indication for FDO and the determination of the derotation angle changed over the course of the study. Whereas in the past, the aim of FDO was mainly to correct increased femoral anteversion and to achieve a neutral clinical midpoint [17] between passive internal and external rotation, over time the results of 3D gait analysis became more important for the planning of derotation amount as reported in an earlier study [5]. The amount of derotation was measured intraoperatively by using K-wires placed proximally and distally to the osteotomy. In 10 of the 16 patients with bilateral FDO, derotation was performed with respect to the slight asymmetry in clinical examination and femoral anteversion. The derotation angle differed between 58 and 208 between both sides. The evaluation of all subjects in this study included a physical examination, videotaping, and instrumented gait analysis according to a standardized protocol. For 3D gait analysis a six-camera Vicon system was used (Oxford Metrics, Oxford, UK) (Vicon 370 until 2002, since then Vicon 612; equivalency of both systems in Heidelberg was meticulously checked). Skin-mounted markers were applied to bony landmarks of the patients according to the protocol of Kadaba et al. [18] and a knee alignment device was used to reduce mistakes in the transversal plane. Two static trials were
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carried out and, in cases of a more than 58 difference in the frontal plane, an additional third trial was recorded. The patients were asked to walk down a 7 m walkway barefoot at self-determined speed. The examinations were all performed by a physiotherapist and a study nurse, who were specially trained in pediatric neurodevelopmental therapy and had more than 8 years of experience with gait analysis. Postoperative management consisted of early mobilization with weight-bearing transfers after the first 2–6 weeks and subsequent ambulation, depending on the patient’s body weight and concomitant procedures. 2.1. Statistical methods The outcome variables examined in this study were hip rotation and pelvic rotation in the stance phase of gait, asymmetry and the improvement in asymmetry. Statistical analysis was performed using IMB SPSS Statistics 19. First, the normal distribution of the outcome variables was confirmed by Shapiro–Wilk test. All tests were two-tailed, and the significance level was set at p < 0.05. Then, outcomes were compared between the pre- and postoperative gait analysis parameters for each of both defined groups using Student’s ttest. Then an analysis of variance (ANOVA) was performed to compare the parameters between both groups. 3. Results Twelve children were treated with a unilateral FDO; 16 patients with a bilateral FDO. There were no significant differences concerning the age of the patients (p = 0.588), the functional level (GMFCS; p = 0.416), the proportion of right to left limbs as more involved sides (p = 0.586) and the proportion of distal to proximal femoral osteotomies (p = 0.464). Concomitant procedures are listed in Table 1. Neither groups had any significant differences in the preoperative clinical examination including clinical mid-point of hip rotation measured with extended legs [17] (less involved side: p = 0.175; more involved side: p = 0.095) and anteversion (TPAT [19]) (less involved side: p = 0.439; more involved side: p = 0.973). Preoperative hip rotation in stance and pelvic rotation did not differ significantly on the more (hip rotation: p = 0.112, pelvic rotation: p = 0.399) or on the less involved side (hip rotation: p = 0.831, pelvic rotation: p = 0.406). There was no significant difference in asymmetry between both groups (p = 0.067). The derotation angle on the more involved side did not differ significantly as well (p = 0.103). The results of preoperative examination are listed in Table 2. Between the two groups, there were not any significant differences in the postoperative hip rotation (p = 0.282) and pelvic rotation (p = 0.545) in stance during gait analysis of the more involved limb. Surprisingly, there were no significant differences in the postoperative hip rotation (p = 0.119) and pelvic rotation (p = 0.876) in stance during gait analysis of the less involved limbs between the group with a unilateral FDO and the group with a bilateral FDO. Both groups presented a significant improvement in asymmetry (difference between pre- and postoperative asymmetry in hip rotation in stance obtained through gait analysis) (unilateral DO: p < 0.001; bilateral DO: p < 0.001). Hip rotation in the stance phase of the limb with less IRG did not change significantly from pre- to postoperatively in either group (unilateral DO: p = 0.631; bilateral DO: p = 0.051), even though the derotation angle averaged 25.38 7.68 in the group with bilateral FDO. Although the postoperative asymmetry does not differ (p = 0.453), there is a significant difference in postoperative mean hip rotation between both limbs after bilateral FDO (p = 0.036). Conversely, these two parameters do not differ significantly in the group with unilateral FDO (p = 0.493). For gait analysis graphs please refer to Fig. 1. The pelvic rotation changed significantly on the more (p = 0.035) and less involved side (p = 0.001) from pre- to postoperative after unilateral FDO. In contrast there was no significant change on the more (p = 0.083) or on the less involved side (p = 0.234) after bilateral FDO. The difference between pelvic rotation on the more and less involved side changed from pre- to postoperative significantly in the group with unilateral FDO (p = 0.038), whereas a significant change could not be measured in the group with bilateral FDO (p = 0.941) (Fig. 2). For gait analysis graphs please refer to Fig. 3.
3.1. Over- and Undercorrection In the group with bilateral FDO there were seven cases of overcorrection (more than 58 of external rotation in stance phase during gait analysis) on the less involved side and three on the more involved side. Additionally, there were three cases of
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Table 1 Demographic data: distribution of the GMFCS level, age range and more involved limb in the different groups and number of surgical procedures performed in single event multilevel surgery; unilateral DO = group with unilateral derotation osteotomy; bilateral DO = group with bilateral derotation osteotomy. Unilateral DO more involved GMFCS I GMFCS II GMFCS III Age Left Right Procedures FDO (proximal) FDO (distal) Intramuscular psoas lengthening Proximal rectus femoris release Adductor lengthening Hamstring lengthening Distal rectus femoris transfer Patella tendon shortening Calf muscle lengthening Bony foot stabilization Soft tissue procedures, foot
Unilateral DO less involved
Bilateral DO more involved
Bilateral DO less involved
0 9 3 10.3 2.9 7 5
5 7
3 9 4 11.1 4.0 11 5
5 11
7 5 2 5 1 7 10 1 6 3 5
0 0 0 6 1 7 10 2 7 2 4
7 9 4 4 1 7 10 1 10 6 2
7 9 4 4 1 7 8 1 11 7 3
Table 2 Preoperative gait analysis and clinical examination; DO = derotation osteotomy. Less involved side
Mean hip rotation Clinical midpoint Anteversion Asymmetry Derotation amount
More involved side
Unilateral DO
Bilateral DO
Unilateral DO
Bilateral DO
2.18 14.88 14.08 10.38 21.38 16.78 35.98 13.88 –
3.18 8.88 19.78 6.98 26.98 14.08 27.68 4.48 25.38 7.68
38.08 10.28 17.98 12.28 21.78 17.68 35.98 13.88 29.28 2.98
31.98 9.38 26.98 10.48 30.58 14.08 27.68 4.48 31.98 5.48
Fig. 1. Mean hip rotation obtained through 3D gait analysis pre- (red) and postoperatively (blue) for the less- and more involved side in the group with unilateral and the group with bilateral femoral derotation osteotomy (DO); the transparent areas represent the standard deviation; prep = preoperative; postop = postoperative; norm = normally developed children; int = internal rotation; ext = external rotation; [deg] = degree (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).
undercorrection (more than 158 of internal rotation in stance phase during gait analysis) on the more involved side. In contrast there were five cases of overcorrection and one case of undercorrection on the more involved side after unilateral FDO. There were two cases with more than 158 internal rotation on the less involved side 1 year postoperative. In one case the hip rotation changed from 508 internal to 68 internal on the side with FDO and from 238 internal to 188 internal on the side without surgery. The pelvic rotation was 48 pre- and 78 postoperatively on the more involved side. In the other case the hip rotation changed from 518 internal to 148 external on the rotated side and from 28 internal to 208 internal on the side without surgery. The pelvic rotation increased from 48 preoperatively to 138 postoperatively on the more involved side.
4. Discussion The purpose of this study was to evaluate if unilateral FDO leads to a comparable or even superior outcome when compared to bilateral FDO in children with bilateral spastic CP and bilaterally increased femoral anteversion, but with a large asymmetry in hip and pelvic rotation during walking. A high rate of over- and undercorrection and a high variance of results in hip rotation after FDO have been reported, with poorer
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Fig. 2. Asymmetry in pelvic rotation from pre- to postoperative in both groups Asymmetry in pelvic rotation = difference in pelvic rotation between the more and less involved side; preop = preoperative; postop = postoperative; unilateral DO/bilateral DO 0 group with unilateral/bilateral derotation osteotomy (DO); *significant difference (p = 0.038); additional p-values: comparison preto postoperative in the group with bilateral DO: p = 0.941; comparison between both groups (unilateral/bilateral DO) preoperative: p = 0.252, postoperative: p = 0.260.
outcome in the less involved limbs [5]. Previous studies suggested that decision-making based on physical evaluation or anteversion angle measurements, does not result in satisfying outcomes and that dynamic evaluation is necessary to optimize the outcome [5,12,20]. Clinical measurement methods for the femur (TPAT [19], mid-point of hip rotation [17]) were determined to have poor correlations to gait analysis results and CT scan [21,22]. The current study shows, that the FDO on the less involved side, performed in order to obtain a neutral clinical midpoint of passive rotation [17] and to restore normal anteversion, did not have a functional benefit during walking for the patients concerning transversal plane motion. Unilateral treatment even has the potential to correct pelvic mal-rotation. An additional osteotomy means additional loss of blood for the children, prolongation of the time of the surgical procedure, a higher risk of infection, a potential subsequent non-union, additional pain, and difficulties in recovery
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with, for example, handicapped transfers and difficulties using the bathroom. Also present is an increased risk of overcorrection with potentially increased foot progression angle [5,16]. Following the results of this study, the indication for FDO on the less-involved side should be critically analyzed. Limbs with internal hip rotation of less than 158 in gait analysis should not undergo FDO [5]. In patients with concomitant hip dysplasia, the indication for an additional FDO is different from just correcting IRG and therefore in these cases the suggestions above are of minor importance. The preoperative mean hip rotation of the less involved limb averaged 2.18 14.88 in the group with unilateral FDO and 3.18 8.88 in the group with bilateral FDO. According to gait analysis, FDO was not indicated on this side in either group, however it was done to correct increased femoral anteversion in the bilateral FDO group. Hip rotation did not change significantly from pre- to postoperative in these cases (bilateral DO) although the derotation angle averaged 25.38 7.68. This result confirms the findings of Schwartz et al. [16], who describe a missing change in transverse plane kinematics after FDO in a group of CP patients with increased anteversion and without increased internal hip rotation in gait analysis. Corroborating previous findings [5,12] in the group with bilateral FDO, hip rotation tended to be undercorrected in three cases on the side with more internal hip rotation and external pelvic rotation preoperatively and overcorrected in seven cases on the other side. Overcorrection on the less involved side remains the major problem after bilateral FDO. Overcorrection should be avoided as it leads to a severe impairment of lever-arm function with increased foot progression angle and a corresponding reduction of the foot lever arm, altered moment arms at the knee and weakness of hip muscles [23,24] in most of the cases. Because a change in pelvic rotation is not expected, overcorrection will not be balanced. An overcorrection on the more involved side in nearly 50% of the cases with unilateral FDO indicates that the derotation angle should be defined conservatively in these cases as an additional normalization of the pelvic rotation is to be expected. Undercorrection may result in an enduring IRG with foot clearance problems in the contralateral leg and tripping. The postoperative internal rotation in stance phase in two cases with ‘‘undercorrection’’ have to be discussed critically. In the first case, the pelvic rotation rarely changed from pre-(48) to postoperatively (78). The derotation on the more involved side led to a good result with 68 internal rotation postoperatively and similarly reduced the internal rotation on the untreated side from
Fig. 3. mean pelvic rotation obtained through 3D gait analysis pre- (red) and postoperatively (blue) for the less- and more involved side in the group with unilateral and the group with bilateral femoral derotation osteotomy (DO); the transparent areas represent the standard deviation; prep = preoperative; postop = postoperative; norm = normally developed children; int = internal rotation (pelvic protraction); ext = external rotation (pelvic retraction); [deg] = degree. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).
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238 to 188. Although an improvement can be seen on the more involved side, the less involved side has a relevant internal rotation postoperatively. Retrospectively, in this case, a bilateral FDO should have been done, since the preoperative internal rotation exceeded 158 and this was shown in past studies to be a relevant indication to carry out FDO [5]. In the second case, the preoperative pelvic rotation (48) was as well normal. FDO led to a moderate overcorrection in the more involved side (148 of external rotation) and as a consequence the pelvic rotation (138) worsened. Correspondingly, the contralateral untreated limb had to compensate and therefore an increase in internal rotation resulted (28 internal preoperatively to 208 internal postoperatively). Contrary to the first case, the overtreatment of the more involved limb is responsible for the worsening of the less involved side. Thus, the amount of derotation should have been chosen more conservatively in this case underlining the findings of prior studies [16,25] However, in selected cases where the contralateral limb shows residual or increased internal hip rotation on the less involved side at follow-up, a secondary FDO may be carried out during hardware removal surgery. According to recent work, the impact of the surgical correction of internal hip rotation on pelvic rotation in patients with bilateral CP remains inconsistent [13]. In patients with unilateral CP preoperative pelvic retraction is thought to be a compensatory mechanism to maintain foot progression angle and to keep the sagittal knee axis aligned physiologically [13]. In contrast, preoperative pelvic rotation is not assumed to be compensatory in patients with bilateral CP. It is explained as a primary deformity and an impaired motor control on both sides is presumed to inhibit the ability to change the dynamic compensation [13]. However, the results of this study suggest, that pelvic rotation in children with bilateral CP is relevantly influenced by asymmetry in dynamic hip rotation. Contrary to previously published papers, pelvic retraction can be significantly influenced if the asymmetry of internal hip rotation is considered in treatment and the mildly involved side is not addressed with a derotation osteotomy. Previous studies did not find any significant changes in pelvic kinematics and this can be explained since diplegic patients in past studies were mostly treated bilaterally and asymmetry in pelvic and hip rotation was not taken into account primarily. In contrast to this study, recent studies regarded both limbs independently, preoperative pelvic rotation was not asymmetrical [13,26], a bilateral FDO was performed [13,27,28] and the rotation of the pelvis for both sides was included. Further prospective studies are needed to support the results of this study. 4.1. Limitations This study has some limitations due to the retrospective design. The small sample size might mask a possibly existing significant difference in preoperative pelvic rotation between both groups (post hoc power: 0.459). Further (prospective) studies are needed to understand the causes of pelvic asymmetry in children with bilateral CP. The reported outcome may be influenced by other procedures that were performed at the time of multilevel surgery. Therefore, the results of the present study should be interpreted as being affected by concomitant procedures of multilevel surgery, with FDO presenting the one central procedure for hip and pelvic rotation. The indication for FDO and the determination of the derotation angle changed over the course of the study and the gait analysis advice became more important compared to the clinical examination, following the current state of research. This aspect has to be
considered because the derotation angle is believed to be greater determined by physical examination than by gait analysis [22]. In this study the patients of both retrospectively defined groups underwent surgery during the same period of time and there were not any differences concerning the preoperative examination and the derotation angle on the more involved side. Correspondingly, this change in determination of the derotation angle is related to both groups in the same way and will not relevantly influence the comparison. 4.2. Conclusion Unilateral FDO in asymmetric internal rotation gait leads to comparable functional outcome compared to bilateral treatment and has a positive effect on pelvic rotation additionally leading to a more symmetrical gait pattern.
Funding None.
Conflict of interest None declared. References [1] Wren TA, Rethlefsen S, Kay RM. Prevalence of specific gait abnormalities in children with cerebral palsy: influence of cerebral palsy subtype, age, and previous surgery. J Pediatr Orthop 2005;25(1):79–83. [2] Svenningsen S, Terjesen T, Auflem M, Berg V. Hip rotation and in-toeing gait. A study of normal subjects from four years until adult age. Clin Orthop Relat Res 1990;251:177–82. [3] Ounpuu S, DeLuca P, Davis R, Romness M. Long-term effects of femoral derotation osteotomies: an evaluation using three-dimensional gait analysis. J Pediatr Orthop 2002;22(2):139–45. [4] O’Sullivan R, Walsh M, Hewart P, Jenkinson A, Ross LA, O’Brien T. Factors associated with internal hip rotation gait in patients with cerebral palsy. J Pediatr Orthop 2006;26(4):537–41. [5] Dreher T, Wolf S, Braatz F, Patikas D, Doderlein L. Internal rotation gait in spastic diplegia–critical considerations for the femoral derotation osteotomy. Gait Posture 2007;26(1):25–31. [6] Tylkowski CM, Rosenthal RK, Simon SR. Proximal femoral osteotomy in cerebral palsy. Clin Orthop Relat Res 1980;(151):183–92. [7] Pirpiris M, Trivett A, Baker R, Rodda J, Nattrass GR, Graham HK. Femoral derotation osteotomy in spastic diplegia. Proximal or distal? J Bone Joint Surg Br Vol 2003;85(2):265–72. [8] Dreher T, Wolf SI, Heitzmann D, Swartman B, Schuster W, Gantz S, et al. Longterm outcome of femoral derotation osteotomy in children with spastic diplegia. Gait Posture 2012;36(3):467–70. [9] Saraph V, Zwick EB, Zwick G, Dreier M, Steinwender G, Linhart W. Effect of derotation osteotomy of the femur on hip and pelvis rotations in hemiplegic and diplegic children. J Pediatr Orthop Part B 2002;11(2):159–66. [10] Kay RM, Rethlefsen SA, Hale JM, Skaggs DL, Tolo VT. Comparison of proximal and distal rotational femoral osteotomy in children with cerebral palsy. J Pediatr Orthop 2003;23(2):150–4. [11] Rutz E, Donath S, Tirosh O, Graham HK, Baker R. Explaining the variability improvements in gait quality as a result of single event multi-level surgery in cerebral palsy. Gait Posture 2013;38(3):455–60. [12] Kay RM, Rethlefsen S, Reed M, Do KP, Skaggs DL, Wren TA. Changes in pelvic rotation after soft tissue and bony surgery in ambulatory children with cerebral palsy. J Pediatr Orthop 2004;24(3):278–82. [13] Carty CP, Walsh HP, Gillett JG, Phillips T, Edwards JM, deLacy M, et al. The effect of femoral derotation osteotomy on transverse plane hip and pelvic kinematics in children with cerebral palsy: a systematic review and meta-analysis. Gait Posture 2014;40(3):333–40. [14] de Morais Filho MC, Kawamura CM, Andrade PH, Dos Santos MB, Pickel MR, Neto RB. Factors associated with pelvic asymmetry in transverse plane during gait in patients with cerebral palsy. J Pediatr Orthop B 2009;18(6):320–4. [15] Chung CY, Lee SH, Choi IH, Cho TJ, Yoo WJ, Park MS. Residual pelvic rotation after single-event multilevel surgery in spastic hemiplegia. J Bone Joint Surg 2008;90(9):1234–8. [16] Schwartz MH, Rozumalski A, Novacheck TF. Femoral derotational osteotomy: surgical indications and outcomes in children with cerebral palsy. Gait Posture 2014;39(2):778–83.
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Asymmetric pelvic and hip rotation in children with bilateral cerebral palsy: Uni- or bilateral femoral derotation osteotomy? M. Niklasch a, L. Do¨derlein b, M.C. Klotz a, F. Braatz c, S.I. Wolf a, T. Dreher a,* a
Pediatric Orthopaedics and Foot Surgery, Clinic for Orthopedics and Trauma Surgery, Center for Orthopedics, Trauma Surgery and Spinal Cord Injury, Heidelberg University Hospital, Schlierbacher Landstr. 200a, 69118 Heidelberg, Germany b Orthopaedic Hospital for Children, Behandlungszentrum Aschau GmbH, Bernauerstr. 18, 83229 Aschau i. Chiemgau, Germany c Klinik fu¨r Unfallchirurgie und Orthopa¨die, Universita¨tsmedizin Go¨ttingen, Robert-Koch-Str. 40, 37075, Go¨ttingen, Germany
A R T I C L E I N F O
A B S T R A C T
Article history: Received 19 July 2014 Received in revised form 14 January 2015 Accepted 23 January 2015
Internal rotation gait is common among children with bilateral cerebral palsy. However, despite bilaterally increased femoral anteversion asymmetric internal rotation gait is often found. Femoral derotation osteotomy (FDO) is commonly performed bilaterally. Variable functional outcomes are reported especially in cases with mild internal hip rotation during gait and abnormal preoperative pelvic rotation. A major question is if a unilateral treatment of the more involved side in asymmetric cases leads to a comparable or even superior outcome. One hundred and nine children with spastic bilateral CP treated with FDO with pre- and 1-year postoperative 3D gait analysis were retrospectively collected. The asymmetry was calculated from the preoperative difference between both limbs in hip rotation obtained by 3D gait analysis. Twenty-eight children with asymmetry larger than 208 were selected and classified into two groups, according to whether they obtained a unilateral or bilateral FDO. Preoperative clinical examination and pre- and postoperative hip and pelvic rotation in gait analysis on the more and the less involved side did not differ significantly between both groups. Interestingly, in both groups, hip rotation did not change significantly in less-involved limbs, although intraoperative derotation averaged 258. After unilateral FDO a significant change in pelvic rotation resulted, whereas this was not found after bilateral FDO. The results of this study suggest that unilateral FDO in children with asymmetric internal rotation gait leads to a comparable functional outcome compared to bilateral treatment. Furthermore, it was shown for the first time that considering the asymmetry has a positive effect on pelvic rotation. ß 2015 Elsevier B.V. All rights reserved.
Keywords: Cerebral palsy Femoral derotation osteotomy Asymmetric internal rotation gait Pelvic rotation
1. Introduction Internal rotation gait (IRG) is common among children with cerebral palsy (CP) [1]. It is often thought to be a bilateral problem, as it is in the normal population [2], and associated with bilaterally increased femoral anteversion [3]. However, it could be demonstrated, that IRG is predominantly a unilateral phenomenon in patients with bilateral CP [4]. IRG often causes problems with foot clearance in the contralateral leg and tripping. A primary cause of IRG is transverse plane deformity of the pelvis, femur, tibia, and/or foot [4].
* Corresponding author. Tel.: +49 6221 5626384; fax: +49 6221 5626348. E-mail addresses: [email protected], [email protected] (T. Dreher). http://dx.doi.org/10.1016/j.gaitpost.2015.01.024 0966-6362/ß 2015 Elsevier B.V. All rights reserved.
Femoral derotation osteotomy (FDO) is seen as the golden standard for the treatment of increased femoral internal rotation [3,5–9]. The osteotomy can be performed either proximally as intertrochanteric osteotomy or distally as supracondylar osteotomy with comparable static and functional results [3,7,9,10]. FDO corrects increased femoral anteversion and is commonly performed bilaterally since the anteversion angle is often increased bilaterally. However, many authors reported variable outcomes after FDO, especially in cases with mild IRG [5,11] and abnormal pelvic rotation preoperatively [3,9,12,13]. A major issue in the treatment is how to identify and address cases with asymmetric internal hip rotation during gait. In patients with asymmetrical forms of bilateral CP the most frequent pattern is an increase in internal hip rotation and pelvic retraction on the more involved side [9,13,14]. Kay et al. [12] reported, that children with bilateral CP and bilateral IRG, who were derotated bilaterally
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tended to be undercorrected on the side with preoperative pelvic retraction and overcorrected on the other side. A correction of pelvic retraction could be achieved after unilateral FDO in patients with unilateral CP [9,13,15], but not after bilateral FDO in patients with bilateral CP [3,13]. Previous investigations could outline that in patients with mild IRG overcorrection is a major problem and considered FDO to be done only if at least 158 of internal rotation are present in gait analysis [5,16]. It remains unresolved if in the patients with asymmetric IRG, where the mild-involved side has 158 or less of hip internal rotation but a bilaterally increased femoral anteversion should undergo bilateral FDO. The purpose of the current study was therefore to evaluate if unilateral treatment is comparable or even superior to bilateral treatment in patients with asymmetric internal hip rotation during gait. 2. Materials and methods Standardized 3D gait analysis and clinical examination are routinely performed for all ambulatory patients with CP both before and 1 year after surgery. For the present cohort study, all ambulatory children with bilateral CP (GMFCS level I–III), increased femoral anteversion, and IRG, who were treated with FDO in the context of single-event multilevel surgery between 2000 and 2011, were selected retrospectively from the gait laboratory database. The amount of intra-operative derotation is routinely measured with derotational K-wires and documented in the surgical report. Patients who underwent additional tibial (de-)rotational osteotomy were excluded from this study. One hundred and eight children with a mean age of 10.7 (3.2) years [range: 3.8–17.8] matched these criteria. The asymmetry between both limbs of each subject was calculated from the preoperative difference between the two limbs concerning hip rotation in stance obtained by 3D gait analysis. All children with bilateral CP and an asymmetry in hip rotation larger than 208 were selected. Twenty-eight children fit these criteria and were retrospectively classified into two groups: one group obtained a unilateral FDO (12 patients); the other group underwent bilateral FDO (16 patients). Accordingly, improvement in asymmetry was calculated as the difference between pre- and postoperative asymmetry. FDO was performed either distally as supracondylar osteotomy or proximally as intertrochanteric osteotomy. The indication for FDO and the determination of the derotation angle changed over the course of the study. Whereas in the past, the aim of FDO was mainly to correct increased femoral anteversion and to achieve a neutral clinical midpoint [17] between passive internal and external rotation, over time the results of 3D gait analysis became more important for the planning of derotation amount as reported in an earlier study [5]. The amount of derotation was measured intraoperatively by using K-wires placed proximally and distally to the osteotomy. In 10 of the 16 patients with bilateral FDO, derotation was performed with respect to the slight asymmetry in clinical examination and femoral anteversion. The derotation angle differed between 58 and 208 between both sides. The evaluation of all subjects in this study included a physical examination, videotaping, and instrumented gait analysis according to a standardized protocol. For 3D gait analysis a six-camera Vicon system was used (Oxford Metrics, Oxford, UK) (Vicon 370 until 2002, since then Vicon 612; equivalency of both systems in Heidelberg was meticulously checked). Skin-mounted markers were applied to bony landmarks of the patients according to the protocol of Kadaba et al. [18] and a knee alignment device was used to reduce mistakes in the transversal plane. Two static trials were
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carried out and, in cases of a more than 58 difference in the frontal plane, an additional third trial was recorded. The patients were asked to walk down a 7 m walkway barefoot at self-determined speed. The examinations were all performed by a physiotherapist and a study nurse, who were specially trained in pediatric neurodevelopmental therapy and had more than 8 years of experience with gait analysis. Postoperative management consisted of early mobilization with weight-bearing transfers after the first 2–6 weeks and subsequent ambulation, depending on the patient’s body weight and concomitant procedures. 2.1. Statistical methods The outcome variables examined in this study were hip rotation and pelvic rotation in the stance phase of gait, asymmetry and the improvement in asymmetry. Statistical analysis was performed using IMB SPSS Statistics 19. First, the normal distribution of the outcome variables was confirmed by Shapiro–Wilk test. All tests were two-tailed, and the significance level was set at p < 0.05. Then, outcomes were compared between the pre- and postoperative gait analysis parameters for each of both defined groups using Student’s ttest. Then an analysis of variance (ANOVA) was performed to compare the parameters between both groups. 3. Results Twelve children were treated with a unilateral FDO; 16 patients with a bilateral FDO. There were no significant differences concerning the age of the patients (p = 0.588), the functional level (GMFCS; p = 0.416), the proportion of right to left limbs as more involved sides (p = 0.586) and the proportion of distal to proximal femoral osteotomies (p = 0.464). Concomitant procedures are listed in Table 1. Neither groups had any significant differences in the preoperative clinical examination including clinical mid-point of hip rotation measured with extended legs [17] (less involved side: p = 0.175; more involved side: p = 0.095) and anteversion (TPAT [19]) (less involved side: p = 0.439; more involved side: p = 0.973). Preoperative hip rotation in stance and pelvic rotation did not differ significantly on the more (hip rotation: p = 0.112, pelvic rotation: p = 0.399) or on the less involved side (hip rotation: p = 0.831, pelvic rotation: p = 0.406). There was no significant difference in asymmetry between both groups (p = 0.067). The derotation angle on the more involved side did not differ significantly as well (p = 0.103). The results of preoperative examination are listed in Table 2. Between the two groups, there were not any significant differences in the postoperative hip rotation (p = 0.282) and pelvic rotation (p = 0.545) in stance during gait analysis of the more involved limb. Surprisingly, there were no significant differences in the postoperative hip rotation (p = 0.119) and pelvic rotation (p = 0.876) in stance during gait analysis of the less involved limbs between the group with a unilateral FDO and the group with a bilateral FDO. Both groups presented a significant improvement in asymmetry (difference between pre- and postoperative asymmetry in hip rotation in stance obtained through gait analysis) (unilateral DO: p < 0.001; bilateral DO: p < 0.001). Hip rotation in the stance phase of the limb with less IRG did not change significantly from pre- to postoperatively in either group (unilateral DO: p = 0.631; bilateral DO: p = 0.051), even though the derotation angle averaged 25.38 7.68 in the group with bilateral FDO. Although the postoperative asymmetry does not differ (p = 0.453), there is a significant difference in postoperative mean hip rotation between both limbs after bilateral FDO (p = 0.036). Conversely, these two parameters do not differ significantly in the group with unilateral FDO (p = 0.493). For gait analysis graphs please refer to Fig. 1. The pelvic rotation changed significantly on the more (p = 0.035) and less involved side (p = 0.001) from pre- to postoperative after unilateral FDO. In contrast there was no significant change on the more (p = 0.083) or on the less involved side (p = 0.234) after bilateral FDO. The difference between pelvic rotation on the more and less involved side changed from pre- to postoperative significantly in the group with unilateral FDO (p = 0.038), whereas a significant change could not be measured in the group with bilateral FDO (p = 0.941) (Fig. 2). For gait analysis graphs please refer to Fig. 3.
3.1. Over- and Undercorrection In the group with bilateral FDO there were seven cases of overcorrection (more than 58 of external rotation in stance phase during gait analysis) on the less involved side and three on the more involved side. Additionally, there were three cases of
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Table 1 Demographic data: distribution of the GMFCS level, age range and more involved limb in the different groups and number of surgical procedures performed in single event multilevel surgery; unilateral DO = group with unilateral derotation osteotomy; bilateral DO = group with bilateral derotation osteotomy. Unilateral DO more involved GMFCS I GMFCS II GMFCS III Age Left Right Procedures FDO (proximal) FDO (distal) Intramuscular psoas lengthening Proximal rectus femoris release Adductor lengthening Hamstring lengthening Distal rectus femoris transfer Patella tendon shortening Calf muscle lengthening Bony foot stabilization Soft tissue procedures, foot
Unilateral DO less involved
Bilateral DO more involved
Bilateral DO less involved
0 9 3 10.3 2.9 7 5
5 7
3 9 4 11.1 4.0 11 5
5 11
7 5 2 5 1 7 10 1 6 3 5
0 0 0 6 1 7 10 2 7 2 4
7 9 4 4 1 7 10 1 10 6 2
7 9 4 4 1 7 8 1 11 7 3
Table 2 Preoperative gait analysis and clinical examination; DO = derotation osteotomy. Less involved side
Mean hip rotation Clinical midpoint Anteversion Asymmetry Derotation amount
More involved side
Unilateral DO
Bilateral DO
Unilateral DO
Bilateral DO
2.18 14.88 14.08 10.38 21.38 16.78 35.98 13.88 –
3.18 8.88 19.78 6.98 26.98 14.08 27.68 4.48 25.38 7.68
38.08 10.28 17.98 12.28 21.78 17.68 35.98 13.88 29.28 2.98
31.98 9.38 26.98 10.48 30.58 14.08 27.68 4.48 31.98 5.48
Fig. 1. Mean hip rotation obtained through 3D gait analysis pre- (red) and postoperatively (blue) for the less- and more involved side in the group with unilateral and the group with bilateral femoral derotation osteotomy (DO); the transparent areas represent the standard deviation; prep = preoperative; postop = postoperative; norm = normally developed children; int = internal rotation; ext = external rotation; [deg] = degree (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).
undercorrection (more than 158 of internal rotation in stance phase during gait analysis) on the more involved side. In contrast there were five cases of overcorrection and one case of undercorrection on the more involved side after unilateral FDO. There were two cases with more than 158 internal rotation on the less involved side 1 year postoperative. In one case the hip rotation changed from 508 internal to 68 internal on the side with FDO and from 238 internal to 188 internal on the side without surgery. The pelvic rotation was 48 pre- and 78 postoperatively on the more involved side. In the other case the hip rotation changed from 518 internal to 148 external on the rotated side and from 28 internal to 208 internal on the side without surgery. The pelvic rotation increased from 48 preoperatively to 138 postoperatively on the more involved side.
4. Discussion The purpose of this study was to evaluate if unilateral FDO leads to a comparable or even superior outcome when compared to bilateral FDO in children with bilateral spastic CP and bilaterally increased femoral anteversion, but with a large asymmetry in hip and pelvic rotation during walking. A high rate of over- and undercorrection and a high variance of results in hip rotation after FDO have been reported, with poorer
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Fig. 2. Asymmetry in pelvic rotation from pre- to postoperative in both groups Asymmetry in pelvic rotation = difference in pelvic rotation between the more and less involved side; preop = preoperative; postop = postoperative; unilateral DO/bilateral DO 0 group with unilateral/bilateral derotation osteotomy (DO); *significant difference (p = 0.038); additional p-values: comparison preto postoperative in the group with bilateral DO: p = 0.941; comparison between both groups (unilateral/bilateral DO) preoperative: p = 0.252, postoperative: p = 0.260.
outcome in the less involved limbs [5]. Previous studies suggested that decision-making based on physical evaluation or anteversion angle measurements, does not result in satisfying outcomes and that dynamic evaluation is necessary to optimize the outcome [5,12,20]. Clinical measurement methods for the femur (TPAT [19], mid-point of hip rotation [17]) were determined to have poor correlations to gait analysis results and CT scan [21,22]. The current study shows, that the FDO on the less involved side, performed in order to obtain a neutral clinical midpoint of passive rotation [17] and to restore normal anteversion, did not have a functional benefit during walking for the patients concerning transversal plane motion. Unilateral treatment even has the potential to correct pelvic mal-rotation. An additional osteotomy means additional loss of blood for the children, prolongation of the time of the surgical procedure, a higher risk of infection, a potential subsequent non-union, additional pain, and difficulties in recovery
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with, for example, handicapped transfers and difficulties using the bathroom. Also present is an increased risk of overcorrection with potentially increased foot progression angle [5,16]. Following the results of this study, the indication for FDO on the less-involved side should be critically analyzed. Limbs with internal hip rotation of less than 158 in gait analysis should not undergo FDO [5]. In patients with concomitant hip dysplasia, the indication for an additional FDO is different from just correcting IRG and therefore in these cases the suggestions above are of minor importance. The preoperative mean hip rotation of the less involved limb averaged 2.18 14.88 in the group with unilateral FDO and 3.18 8.88 in the group with bilateral FDO. According to gait analysis, FDO was not indicated on this side in either group, however it was done to correct increased femoral anteversion in the bilateral FDO group. Hip rotation did not change significantly from pre- to postoperative in these cases (bilateral DO) although the derotation angle averaged 25.38 7.68. This result confirms the findings of Schwartz et al. [16], who describe a missing change in transverse plane kinematics after FDO in a group of CP patients with increased anteversion and without increased internal hip rotation in gait analysis. Corroborating previous findings [5,12] in the group with bilateral FDO, hip rotation tended to be undercorrected in three cases on the side with more internal hip rotation and external pelvic rotation preoperatively and overcorrected in seven cases on the other side. Overcorrection on the less involved side remains the major problem after bilateral FDO. Overcorrection should be avoided as it leads to a severe impairment of lever-arm function with increased foot progression angle and a corresponding reduction of the foot lever arm, altered moment arms at the knee and weakness of hip muscles [23,24] in most of the cases. Because a change in pelvic rotation is not expected, overcorrection will not be balanced. An overcorrection on the more involved side in nearly 50% of the cases with unilateral FDO indicates that the derotation angle should be defined conservatively in these cases as an additional normalization of the pelvic rotation is to be expected. Undercorrection may result in an enduring IRG with foot clearance problems in the contralateral leg and tripping. The postoperative internal rotation in stance phase in two cases with ‘‘undercorrection’’ have to be discussed critically. In the first case, the pelvic rotation rarely changed from pre-(48) to postoperatively (78). The derotation on the more involved side led to a good result with 68 internal rotation postoperatively and similarly reduced the internal rotation on the untreated side from
Fig. 3. mean pelvic rotation obtained through 3D gait analysis pre- (red) and postoperatively (blue) for the less- and more involved side in the group with unilateral and the group with bilateral femoral derotation osteotomy (DO); the transparent areas represent the standard deviation; prep = preoperative; postop = postoperative; norm = normally developed children; int = internal rotation (pelvic protraction); ext = external rotation (pelvic retraction); [deg] = degree. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).
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238 to 188. Although an improvement can be seen on the more involved side, the less involved side has a relevant internal rotation postoperatively. Retrospectively, in this case, a bilateral FDO should have been done, since the preoperative internal rotation exceeded 158 and this was shown in past studies to be a relevant indication to carry out FDO [5]. In the second case, the preoperative pelvic rotation (48) was as well normal. FDO led to a moderate overcorrection in the more involved side (148 of external rotation) and as a consequence the pelvic rotation (138) worsened. Correspondingly, the contralateral untreated limb had to compensate and therefore an increase in internal rotation resulted (28 internal preoperatively to 208 internal postoperatively). Contrary to the first case, the overtreatment of the more involved limb is responsible for the worsening of the less involved side. Thus, the amount of derotation should have been chosen more conservatively in this case underlining the findings of prior studies [16,25] However, in selected cases where the contralateral limb shows residual or increased internal hip rotation on the less involved side at follow-up, a secondary FDO may be carried out during hardware removal surgery. According to recent work, the impact of the surgical correction of internal hip rotation on pelvic rotation in patients with bilateral CP remains inconsistent [13]. In patients with unilateral CP preoperative pelvic retraction is thought to be a compensatory mechanism to maintain foot progression angle and to keep the sagittal knee axis aligned physiologically [13]. In contrast, preoperative pelvic rotation is not assumed to be compensatory in patients with bilateral CP. It is explained as a primary deformity and an impaired motor control on both sides is presumed to inhibit the ability to change the dynamic compensation [13]. However, the results of this study suggest, that pelvic rotation in children with bilateral CP is relevantly influenced by asymmetry in dynamic hip rotation. Contrary to previously published papers, pelvic retraction can be significantly influenced if the asymmetry of internal hip rotation is considered in treatment and the mildly involved side is not addressed with a derotation osteotomy. Previous studies did not find any significant changes in pelvic kinematics and this can be explained since diplegic patients in past studies were mostly treated bilaterally and asymmetry in pelvic and hip rotation was not taken into account primarily. In contrast to this study, recent studies regarded both limbs independently, preoperative pelvic rotation was not asymmetrical [13,26], a bilateral FDO was performed [13,27,28] and the rotation of the pelvis for both sides was included. Further prospective studies are needed to support the results of this study. 4.1. Limitations This study has some limitations due to the retrospective design. The small sample size might mask a possibly existing significant difference in preoperative pelvic rotation between both groups (post hoc power: 0.459). Further (prospective) studies are needed to understand the causes of pelvic asymmetry in children with bilateral CP. The reported outcome may be influenced by other procedures that were performed at the time of multilevel surgery. Therefore, the results of the present study should be interpreted as being affected by concomitant procedures of multilevel surgery, with FDO presenting the one central procedure for hip and pelvic rotation. The indication for FDO and the determination of the derotation angle changed over the course of the study and the gait analysis advice became more important compared to the clinical examination, following the current state of research. This aspect has to be
considered because the derotation angle is believed to be greater determined by physical examination than by gait analysis [22]. In this study the patients of both retrospectively defined groups underwent surgery during the same period of time and there were not any differences concerning the preoperative examination and the derotation angle on the more involved side. Correspondingly, this change in determination of the derotation angle is related to both groups in the same way and will not relevantly influence the comparison. 4.2. Conclusion Unilateral FDO in asymmetric internal rotation gait leads to comparable functional outcome compared to bilateral treatment and has a positive effect on pelvic rotation additionally leading to a more symmetrical gait pattern.
Funding None.
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