Internal rotation gait in spastic diplegia--critical considerations for the femoral derotation osteotomy

Functional knee joint axis calibration and outcome after femoral derotation in patients with cerebral palsy

BACKGROUND

Patients with cerebral palsy and increased femoral anteversion frequently show disturbing internal rotation gait which may be treated via femoral derotation osteotomy (FDO). A recent study monitored that hip rotation in gait may heavily depend on the procedure by which it is being determined. Traditional measures using the femoral epicondyles as reference for the knee axis (CONV) resulted in more severe transverse plane deviations compared to those using a functional method (FUNC) with relevant implications for treatment indication of FDO.

RESEARCH QUESTION

Is mean hip rotation in stance (mHipRotSt) as obtained via FUNC the more sensitive measure for explaining functional changes after FDO compared to CONV method taking the femoral epicondyles as reference for the knee axis?

METHODS

3D-gait analysis before and one year after FDO was performed in fourteen patients including functional joint axis determination of the knee of which MR imaging was available in eight patients both pre- and postoperatively. Transverse plane gait parameters were calculated using both approaches (CONV, FUNC). Differences between examinations as well as between methods were determined.

RESULTS

Changes in femoral anteversion as measured by MR reasonably well confirm the structural changes as measured clinically and intraoperatively. The average change in mHipRotSt across the group was substantially smaller than the structural change implies. Further, using the FUNC approach led to much smaller values compared to when using the CONV approach. We address this to a mismatch between the axes determined in each method.

SIGNIFICANCE

In the presence of femoral deformity, the knee joint axis as determined via a functional method together with the conventional method (femoral epicondyles for the knee axis) allows to quantify knee rotation independent of torsional parameters of the tibia. It may therefore help to better quantify rotational malalignments in gait and improve decision making of FDO.

Crouch Gait in Cerebral Palsy: Current Concepts Review

Background and Objective

Crouch gait is the most common pathological gait pattern in cerebral palsy and is commonly seen in patients with spastic diplegia. It is characterized by excessive knee flexion throughout the stance phase of gait cycle. The aim of this review is to discuss the current literature about CG for a more comprehensive understanding.

Methods

A literature review about various aspects of crouch gait in cerebral palsy was undertaken. This included its etiology and pathophysiology, biomechanics in crouch gait, natural history of untreated crouch gait, clinical and radiological evaluation and different modalities of available treatment.

Results

The etiology is multifactorial and the pathophysiology is poorly understood. This makes its management challenging, thereby leading to a variety of available treatment modalities. Inadvertent lengthening of muscle-tendon units is an important cause and can be avoided. A meticulous clinical and radiological evaluation of patients, supplemented by observational and instrumented gait analysis is mandatory in choosing correct treatment modality and improving the treatment outcome. Younger children can be managed satisfactorily by various non-operative methods and spasticity reduction measures. However, crouch gait in cerebral palsy has a progressive natural history and surgical interventions are needed frequently. The current literature supports combination of various soft tissue and bony procedures as a part of single event multilevel surgery. Growth modulation in the form of anterior distal femur hemiepiphysiodesis for correction of fixed flexion deformity of knee has shown encouraging results and can be an alternative in younger children with sufficient growth remaining.

Conclusions

In spite of extensive research in this field, the current understanding about crouch gait has many knowledge gaps. Further studies about the etiopathogenesis and biomechanics of crouch using instrumented gait analysis are suggested. Similarly, future research should focus on the long term outcomes of different treatment modalities through comparative trials.

Sex differences in linear bone measurements occur following puberty but do not influence femoral or tibial torsion

Torsional, angular, and linear measurements in a paediatric population are clinically important but not well defined and understood. Different methods of measurement and discrepancies between assessors leads to a lack of understanding of what should be defined as typical or atypical for the growing skeleton. From a large dataset of 333 paediatric CT scans, we extracted three-dimensional torsional, angular, and linear measurements from the pelvis, femur, and tibia/fibula. Sex differences in linear measurements were observed in bones of children aged 13+ (around puberty), but femoral and tibial torsion were similar between males and females. The rotational profile (femoral anteversion minus tibial torsion) tended to increase with growth. Epicondylar, condylar, and malleolar widths were smaller in females than males for the same bone length after the age of 13 years, which could explain why females may be more at risk for sport injuries during adolescence. This rich dataset can be used as an atlas for researchers and clinicians to understand typical development of critical rotational profiles and linear bone measurements in children.

Are we overestimating internal rotation gait by conventional modelling?

BACKGROUND

The determination of the knee joint axis (KJA) via specific calibration movements has become a promising alternative to the conventional approach to determine this axis based on regression equations or directly via marker placement on bony landmarks of the knee. Since the orientation of the KJA may differ between methods, it has direct influence on hip rotation and may therefore influence clinical decision making in context of transverse plane gait deviations.

RESEARCH QUESTION

Does a functional KJA calibration lead to clinically relevant differences in hip rotation estimates during gait compared to the conventional method?

METHODS

95 subjects (age: 19.9 years; BMI: 21.1 kg/m²), including 71 patients with potential rotation malalignment, were prospectively examined and underwent 3D gait analysis. For the conventional approach the KJA was determined by applying a knee alignment device, for the functional approach subjects were asked to perform two different calibration movements. Each procedure was performed twice. Mean hip rotation in stance (mHipRotSt) was determined following the conventional and the functional KJA calibration.

RESULTS

Deming regression analysis for the comparison of conventional and functionally measured hip rotation revealed a systematic and substantial difference between methods (slope: 0.63; intercept: 0.31°). Measurement repetition with the knee alignment device revealed typical errors around 5°, whereas the functional methods lead to profoundly smaller errors around 1-2° with slightly inferior results for SQUAT compared to FLEX. However, when compared to conventional frontal plane video-taping, the conventional method seemed to reflect the more consistent results.

SIGNIFICANCE

The systematic linear discrepancy in mHipRotSt obtained by a functional approach as compared to the conventional approach appears critical since patients with severe internal or external rotation gait may be misjudged in function when receiving corrective procedures such as femoral derotation osteotomy.

Cost savings for single event multilevel surgery in comparison to sequential surgery in ambulatory children with cerebral palsy

BACKGROUND

The purpose of this study was to determine the differences in billable provider charges between single event multilevel surgery (SEMLS) based on comprehensive gait analysis and a staged surgical approach (SSA) without comprehensive gait analysis for the orthopedic treatment of ambulatory children with cerebral palsy (CP).

METHODS

The charges associated with nine common orthopedic surgical combinations (both unilateral and bilateral, soft tissue or soft tissue plus bony) for children with CP were determined and compared between SEMLS and SSA. The charges included surgical, anesthesia, operating room, recovery room, hospital stay, physical therapy, and, for SEMLS only, comprehensive computerized gait analysis.

RESULTS

Total charges to complete each combination was higher for SSA than for SEMLS. The differential ranged from $10,247 to $75,069 with the percentage difference ranging from 20% to 47%. The mean difference was $43,606 (p = 0.0002). The dollar difference (r = 0.98, p < 0.0001) and percentage difference (r = 0.79, p = 0.01) were both related to the total charge of the SEMLS surgery.

SIGNIFICANCE

Financial costs are lower for SEMLS vs. SSA for the treatment of multilevel gait issues in children with CP. The cost of gait analysis is much smaller than the cost differential between SEMLS and SSA. Although some patients who have SEMLS may need additional orthopedic surgery with associated costs, this is also possible for SSA. Therefore, due to the many benefits of SEMLS, which also include more informed treatment decision-making as well as reduced time away from school and work (for caregivers), SEMLS guided by gait analysis is recommended over SSA for the treatment of gait disorders in children with CP.

Increased Femoral Anteversion Does Not Lead to Increased Joint Forces During Gait in a Cohort of Adolescent Patients

Orthopedic complications were previously reported for patients with increased femoral anteversion. A more comprehensive analysis of the influence of increased femoral anteversion on joint loading in these patients is required to better understand the pathology and its clinical management. Therefore, the aim was to investigate lower-limb kinematics, joint moments and forces during gait in adolescent patients with increased, isolated femoral anteversion compared to typically developing controls. Secondly, relationships between the joint loads experienced by the patients and different morphological and kinematic features were investigated. Patients with increased femoral anteversion (n = 42, 12.8 ± 1.9 years, femoral anteversion: 39.6 ± 6.9°) were compared to typically developing controls (n = 9, 12.0 ± 3.0 years, femoral anteversion: 18.7 ± 4.1°). Hip and knee joint kinematics and kinetics were calculated using subject-specific musculoskeletal models. Differences between patients and controls in the investigated outcome variables (joint kinematics, moments, and forces) were evaluated through statistical parametric mapping with Hotelling T2 and t-tests (α = 0.05). Canonical correlation analyses (CCAs) and regression analyses were used to evaluate within the patients’ cohort the effect of different morphological and kinematic predictors on the outcome variables. Predicted compressive proximo-distal loads in both hip and knee joints were significantly reduced in patients compared to controls. A gait pattern characterized by increased knee flexion during terminal stance (KneeFlex_tSt) was significantly correlated with hip and knee forces, as well as with the resultant force exerted by the quadriceps on the patella. On the other hand, hip internal rotation and in-toeing, did not affect the loads in the joints. Based on the finding of the CCAs and linear regression analyses, patients were further divided into two subgroups based KneeFlex_tSt. Patients with excessive KneeFlex_tSt presented a significantly higher femoral anteversion than those with normal KneeFlex_tSt. Patients with excessive KneeFlex_tSt presented significantly larger quadriceps forces on the patella and a larger posteriorly-oriented shear force at the knee, compared to patients with normal KneeFlex_tSt, but both patients’ subgroups presented only limited differences in terms of joint loading compared to controls. This study showed that an altered femoral morphology does not necessarily lead to an increased risk of joint overloading, but instead patient-specific kinematics should be considered.

Femoral derotation osteotomy-Does intraoperative electromagnetic tracking reflect the dynamic outcome?

Femoral derotation osteotomy (FDO) is a well-established procedure for the correction of internal rotation gait in children with cerebral palsy. Various studies have demonstrated good results for FDO both in short-term and long-term evaluation with some describing recurrence and over- or under-corrections. The present study evaluates the use of an objective intraoperative derotation measurement through electromagnetic tracking. We report the static and dynamic results of 11 cases with internal rotation gait (8 male, 3 female, mean age 22.2 years), that underwent FDO with intraoperative electromagnetic tracking and conventional goniometric measurement of the correction. The dynamic and static changes were assessed through three-dimensional gait analysis after a mean of 12 months after surgery and rotational imaging preoperative and after a mean of eleven days postoperatively. Mean hip rotation in stance significantly decreased from 20.9° (SD 5.9) to 5.8° (SD 4.7°) after FDO. The mean amount of derotation quantified by electromagnetic tracking was 23.2° (16.5°-28.8°) and 25.1° (20.0°-33.0°) for goniometric measurement. Both measurement modalities showed small differences to rotational imaging (electromagnetic bone tracking [EMT]: 0.72°; goniometer: 1.19°) but a large deviation when compared to three-dimensional gait analysis (EMT: 8.5°, goniometer: 9.1°). In comparison to the static changes and EMT measurement, the dynamic changes measured during 3-D-gait analysis reflected only 66% of the actual derotation performed during surgery. Although electromagnetic tracking allows a precise intraoperative assessment of the derotation during FDO, the amount of intraoperative correction is not reflected in the improvements in three-dimensional gait analysis.

Short-term causal effects of common treatments in ambulatory children and young adults with cerebral palsy: three machine learning estimates

Orthopedic and neurological impairments (e.g., muscle contractures, spasticity) are often treated in children and young adults with cerebral palsy (CP). Due to challenges arising from combinatorics, research funding priorities, and medical practicalities, and despite extensive study, the evidence base is weak. Our goal was to estimate the short-term effectiveness of 13 common orthopedic and neurological treatments at four different levels of outcome in children and young adults diagnosed with CP. The outcome levels considered were body structures, specific gait kinematic deviations, overall gait kinematic deviations, and functional mobility. We used three well-establish causal inference approaches (direct matching, virtual twins, and Bayesian causal forests) and a large clinical gait analysis database to estimate the average treatment effect on the treated (ATT). We then examined the effectiveness across treatments, methods, and outcome levels. The dataset consisted of 2851 limbs from 933 individuals (some individuals underwent multiple treatment episodes). Current treatments have medium effects on body structures, but modest to minimal effects on gait and functional mobility. The median ATT of 13 common treatments in children and young adults with CP, measured as Cohen's D, bordered on medium at the body structures level (median [IQR] = 0.42 [0.05, 0.60]) and became smaller as we moved along the causal chain through specific kinematic deviations (0.21 [0.01, 0.33]), overall kinematic deviations (0.09 [0.03, 0.19]), and functional mobility (-0.01 [-0.06, 0.13]). Further work is needed to understand the source of heterogeneous treatment effects, which are large in this patient population. Replication or refutation of these findings by other centers will be valuable to establish the generalizability of these results and for benchmarking of best practices.

Reporting and tracking objective functional outcome measures: implementation of a summary report for gait and balance measures

The aim of this manuscript is to describe knowledge gaps in the literature, future directions, and emerging applications of gait and balance analysis in spine surgery with regard to functional outcomes measurement. Functional outcome measurement has been established as a useful clinical and research investigational tool in musculoskeletal disease. Evidence currently supports its use in the diagnosis, treatment, and outcome measurement of multiple musculoskeletal disease states, including spinal disease, and its usefulness continues to grow as literature develops. Gait and balance analysis has proven to be broadly applicable, but most clinicians remain unfamiliar and untrained in its usage. The logistical and communication barriers are also described with the potential solutions that are on the near horizon of research. This article describes our methodology for improving conveyance of functional outcome measures in spine surgery. Additionally, we provide a case example of an adult patient with spinal deformity who is examined pre and post operatively using our methodology.

Proximal femoral derotation osteotomy in children with CP : long term outcome and the role of age at time of surgery

The femoral derotation osteotomy (FDO) is seen as the golden standard treatment in children with cerebral palsy and internal rotated gait. This study provides quantitative evidence in support of the beneficial effect of FDO after long term follow up. Retrospective clinical and kinematic evaluation of 31 CP patients (55 operated limbs) pre-, 1 and 3 years postoperatively after proximal FDO was conducted for a minimal follow-up of 3 years. This group con- sisted of 20 men and 11 women, aged 10.68±3.31 years at the time of surgery. Minimum follow up was 3 years (3.16±0.53 years), with 22 patients (38 operated limbs) having an additional follow up at 5 years (5.02±0.49 years). Age at FU3 and FU5 was 14.06±3.52 years and 15.39±3.08 years respectively. A set of clinical and kinematic parameters were ana- lyzed and showed a significant correction of mean hip rotation and femoral anteversion after FDO. Further plotting of individual data comparing 3 or 5 year postoperative values to 1 year postoperative values showed no further significant changes, indicating sustained correction of internally rotted gait until end of our follow up. Plotting mean hip rotation in stance as well as kinematic knee parameters according to age grouped cohorts could not show age at time of surgery to be a significant factor in recurrence of internally rotated gait or preoperative disturbances of knee motion in the sagittal plane. This study provides quantitative evidence on the beneficial effect of FDO, a surgical technique to improve internally rotated gait in cerebral palsy patients with spastic diplegia. Pre- and postoperative clinical and kinematic parameters are compared and results are discussed. Minimum follow up was 3 years with a mean follow up of 4.65±0.83 years. The effect of age at time of surgery on recurrence and kinematic parameters were studied.

Long-term functional outcomes after an external femoral derotation osteotomy in individuals with cerebral palsy

BACKGROUND

It is unknown how a femoral derotation osteotomy (FDO) during childhood affects functional outcomes in adulthood among individuals with bilateral cerebral palsy (CP).

RESEARCH QUESTIONS

How do long-term functional outcomes after an FDO compare to matched individuals who did not have an FDO? How do outcomes change over time?

METHODS

We queried the gait laboratory database for individuals who underwent an external FDO in childhood and were currently ≥25 years old. Participants returned for a long-term analysis (gait, physical examination, functional tests, imaging, questionnaires). The matched non-FDO group included only individuals in Gross Motor Function Classification System levels I-II, yielding three groups (non-FDO I-II, FDO I-II, FDO III-IV).

RESULTS

Sixty-one adults (11 non-FDO, 34 FDO I-II, 16 FDO III-IV) returned 13-25 years after baseline (non-FDO) or surgery (FDO). The non-FDO and FDO I-II groups were matched at baseline on most variables, except the FDO group had weaker hip abductors. At long-term, groups were similar on gait variables (median long-term hip rotation [primary outcome], non-FDO: -4°, FDO I-II: -4°, FDO III-IV: -5°), hip abduction test, fear of falling, and most pain measures despite anteversion being 29° greater in the non-FDO group. The FDO I-II group reported more falls than the non-FDO group. All groups improved on hip rotation, foot progression, and hip abductor strength. Speed and step length decreased/tended to decrease for all three groups. Hip abduction moment and gait deviation index did not change. Improvements in the FDO groups were maintained from short- to long-term.

SIGNIFICANCE

These results challenge the notion that an FDO is necessary to correct mean stance hip rotation for higher functioning individuals since nearly identical results were achieved by adulthood in the non-FDO I-II group. However, an FDO provides improvement earlier and maintenance from short- to long-term. This should factor into the shared decision-making process.

Efficacy and safety of a novel personalized navigation template in proximal femoral corrective osteotomy for the treatment of DDH

Background

This present study is aimed to retrospectively evaluate the efficacy and safety of a novel personalized navigation template in proximal femoral corrective osteotomy for the treatment of DDH.

Methods

Twenty-nine consecutive patients with DDH who underwent proximal femoral corrective osteotomy were evaluated between August 2013 and June 2017. Based on the different surgical methods, they were divided into the conventional group (n = 14) and navigation template group (n = 15). The osteotomy degrees, radiation exposure, and operation time were compared between the two groups.

Results

No major complications relating to osteotomy surgery such as redislocation or avascular necrosis occurred in the navigation template group, which had more accurate osteotomy degrees, less radiation exposure, and shorter operation time when compared with the conventional group (P < 0.05). Moreover, there was significant difference according to the McKay criteria between the two groups (P = 0.0362).

Conclusions

The novel personalized navigation template in proximal femoral corrective osteotomy is effective and safe, which could improve the femoral osteotomy accuracy, reduce radiation exposure, and shorten operation time.

Orthopedic treatment of the lower limbs in spastic paralysis

Spastic paralysis of the limb mainly results from the central lesion, in which spastic cerebral palsy is the common cause. Due to durative muscle spasm in spastic cerebral palsy, it is often accompanied by the formation of secondary musculoskeletal deformities, resulting in limb motor disability. Based on its pathogenesis, surgical treatment is currently applied: selective posterior rhizotomy (SPR) or orthopedic surgery. The primary purpose of early orthopedic surgery was simply to correct limb deformities, which usually led to the recurrence of deformity as a result of the presence of spasticity. With the application of SPR, high muscle tone was successfully relieved, but limb deformity was still present postoperatively. Therefore, this study aimed to elaborate on the management of orthopedic surgery, common deformities of the lower limb, and orthopedic operative methods; discuss the relationship between SPR and orthopedic procedure for limb deformity; and focus on the indications, timing of intervention, and postoperative outcome of different surgical methods.

Development and Validation of a Mobile Application for Measuring Femoral Anteversion in Patients With Cerebral Palsy

BACKGROUND

Computed tomography (CT) provides benefits for 3-dimensional (3D) visualization of femur deformities. However, the potential adverse effects of radiation exposure have become a concern. Consequently, a biplanar imaging system EOS has been proposed to enable reconstruction of the 3D model of the femur. However, this system requires a calibrated apparatus, the cost of which is high, and the area occupied by it is substantial. The purpose of this study was to develop a mobile application that included a new method of 3D reconstruction of the femur from conventional radiographic images and to evaluate the validity and reliability of mobile the application when measuring femoral anteversion.

METHODS

The statistical shape model, graph-cut algorithm, and iterative Perspective-n-Point algorithm were utilized to develop the application. The anteroposterior and lateral images of a femur can be input using the embedded camera or by file transfer, and the touch interface aids accurate contouring of the femur. Regarding validation, the CT scans and conventional radiographic images of 36 patients with cerebral palsy were used. To evaluate concurrent validity, the femoral anteversion measurements on the images reconstructed from the mobile application were compared with those from the 3D CT images. Three clinicians assessed interobserver reliability.

RESULTS

The mobile application, which reconstructs the 3D image from conventional radiographs, was successfully developed. Regarding concurrent validity, the correlation coefficient between femoral anteversion measured using 3D CT and the mobile application was 0.968 (P<0.001). In terms of interobserver reliability, the intraclass correlation coefficient among the 3 clinicians was 0.953.

CONCLUSIONS

The measurement of femoral anteversion with the mobile application showed excellent concurrent validity and reliability in patients with cerebral palsy. The proposed mobile application can be used with conventional radiographs and does not require additional apparatus. It can be used as a convenient technique in hospitals that cannot afford a CT machine or an EOS system.

LEVEL OF EVIDENCE

Level III-diagnostic.

Multilevel Surgery for Children With Cerebral Palsy: A Meta-analysis

CONTEXT

Multilevel surgery (MLS) is standard care for reducing musculoskeletal disorders among children with spastic cerebral palsy (CP).

OBJECTIVE

To summarize the literature examining effects of MLS and satisfaction with MLS for children with CP.

DATA SOURCES

Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, and Cochrane Central Register of Controlled Trials were searched.

STUDY SELECTION

Studies in which authors reported effects of or satisfaction with MLS in children with CP were selected.

DATA EXTRACTION

Two authors screened and extracted data on gross motor function, gait speed, gait (eg, Gait Profile Score), range of motion, strength, spasticity, participation, quality of life, satisfaction, and adverse events.

RESULTS

Seventy-four studies (3551 participants) were identified. One was a randomized controlled trial (RCT) (n = 19); the remainder were cohort studies. Pooled analysis of cohort studies revealed that MLS did not have a long-term effect on gross motor function (standardized mean difference [SMD]: 0.38; 95% confidence interval [CI]: -0.25 to 1.01) or gait speed (SMD: 0.12; 95% CI: -0.01 to 0.25) but did improve gait (SMD: -0.80; 95% CI: -0.95 to -0.65). The RCT also revealed no effect of MLS on gross motor function but improvements in the Gait Profile Score at 1 year. Participation and quality of life were reported in only 5 studies, and adverse events were adequately reported in 17 studies.

LIMITATIONS

Data were largely from cohort studies.

CONCLUSIONS

Findings reveal that gait, but not gross motor function, improves after MLS. RCTs and improved reporting of studies of MLS are required.

Supracondylar femoral rotation osteotomy affects frontal hip kinetics in children with bilateral cerebral palsy

AIM

To evaluate the influence of supracondylar femoral derotation osteotomy (FDO) on hip abduction muscle force and frontal hip moments in children with bilateral cerebral palsy.

METHOD

For this retrospective cohort study 79 children (36 females, 43 males; mean age at surgery 11y [SD 3y]; range 4-17y) with bilateral cerebral palsy and preoperatively and 1-year postoperatively documented frontal hip moments who received supracondylar FDO in 134 limbs were included. The control group consisted of eight children (two females, six males; mean age 11y [SD 4y]; range 5-17y) who received single-event multi-level surgery without FDO.

RESULTS

Hip joint impulse (p<0.001) and the first peak of frontal hip moments (p=0.003) increased, whereas the second peak decreased (p<0.001) from preoperatively to postoperatively. Hip abductor strength improved (p=0.001) from preoperatively to postoperatively.

INTERPRETATION

Despite the compensatory mechanism, frontal hip moments are decreased preoperatively. Supracondylar FDO results in increased frontal hip moments. Changes in anteversion directly influence hip kinetics, although no direct change of the proximal bony geometry is performed.

WHAT THIS PAPER ADDS

Internal rotation gait cannot fully restore the frontal hip moment. Supracondylar femoral derotation osteotomy (FDO) influences frontal hip kinetics in children with bilateral cerebral palsy. Supracondylar FDO changes the curve progression of frontal hip moments. Supracondylar FDO restores the hip abductor moment arm. Supracondylar FDO leads to an increase in hip abductor muscle force.

Estimating the effect size of surgery to improve walking in children with cerebral palsy from retrospective observational clinical data

Single-event multilevel surgery (SEMLS) is a standard treatment approach aimed at improving gait for patients with cerebral palsy, but the effect of this approach compared to natural progression without surgical intervention is unclear. In this study, we used retrospective patient history, physical exam, and three-dimensional gait analysis data from 2,333 limbs to build regression models estimating the effect of SEMLS on gait, while controlling for expected natural progression. Post-hoc classifications using the regression model results identified which limbs would exhibit gait within two standard deviations of typical gait at the follow-up visit with or without a SEMLS with 73% and 77% accuracy, respectively. Using these models, we found that, while surgery was expected to have a positive effect on 93% of limbs compared to natural progression, in only 37% of limbs was this expected effect a clinically meaningful improvement. We identified 26% of the non-surgically treated limbs that may have shown a clinically meaningful improvement in gait had they received surgery. Our models suggest that pre-operative physical therapy focused on improving biomechanical characteristics, such as walking speed and strength, may improve likelihood of positive surgical outcomes. These models are shared with the community to use as an evaluation tool when considering whether or not a patient should undergo a SEMLS.

Proximal versus distal femoral derotation osteotomy in bilateral cerebral palsy

AIM

Femoral derotation osteotomy (FDO) can be conducted either proximally or distally to correct internal rotation gait (IRG) and increased anteversion in children with cerebral palsy (CP). Previous studies with limited numbers of participants have presented comparable short-term static and kinematic outcomes for both techniques. The objective of this retrospective multicentre study was to verify this thesis with a larger number of patients.

METHOD

In total, 119 children with CP and IRG were included after matching the groups on preoperative mean stance hip rotation: 67 intertrochanteric (proximal group) FDO (average age at surgery 9y [SD 3y]); 52 supracondylar (distal group) FDO (average age at surgery 12y [SD 3y]). One random limb of each child was analyzed. Both transverse plane kinematic gait data and torsional parameters of clinical examination were assessed preoperatively and postoperatively.

RESULTS

On average, both groups' mean hip rotation and midpoint of hip rotation improved postoperatively, and groups did not differ preoperatively or postoperatively for these variables (p>0.05).

INTERPRETATION

The osteotomy location does not influence short-term gait kinematics nor static measurements. Therefore, the choice of performing proximal or distal FDO in children with CP for treatment of IRG and increased anteversion should be motivated by considerations other than these outcome parameters.

WHAT THIS PAPER ADDS

Femoral derotation osteotomy (FDO) location does not influence mean stance hip rotation in cerebral palsy (CP). FDO location does not influence mid-point hip rotation in CP. FDO location should be motivated by concomitant procedures performed.

Long-term outcomes over 10 years after femoral derotation osteotomy in ambulatory children with cerebral palsy

BACKGROUND

Femoral derotation osteotomy (FDO) is generally reported to be excellent for correcting the hip rotation and foot progression angles in children with cerebral palsy (CP). However, it is unclear how long the favorable outcomes are maintained.

RESEARCH QUESTION

This study was performed to evaluate the long-term outcomes at more than 10 years after FDO in children with CP.

METHODS

FDO, as part of single event multilevel surgery to improve gait function, was performed at the intertrochanteric level with the patient in the prone position. The goal of the index surgery was femoral anteversion of 15°, measured using a modified trochanteric prominence angle test intraoperatively. All patients underwent three-dimensional gait analysis preoperatively and at 1 year and over 10 years postoperatively.

RESULTS

Thirty-four ambulatory patients (53 hips) with CP undergoing FDO were included. The mean age at surgery was 7.8 years (SD = 3.0 years) and mean follow-up duration was 12.9 years (SD = 2.7 years). The mean hip rotation decreased significantly from 9.6° preoperatively to 3.1° at 1 year postoperatively (p = 0.004), and decreased significantly to -5.9° at the final follow-up (p < 0.001). The mean foot progression in stance decreased from 7.9° preoperatively to -7.4° at 1 year postoperatively (p < 0.001), and was maintained at -10.9° at the final follow-up. The GDI significantly improved from 68.2 preoperatively to 83.4 1 year postoperatively (p < 0.001), and was maintained at 82.3 at the final follow-up. No patients underwent revision surgery due to recurrence of rotation deformity.

SIGNIFICANCE

Proximal FDO performed in the prone position provides favorable long-term outcomes at more than 10 years postoperatively, without recurrence of rotation deformity. To avoid under-correction or recurrence due to insufficient derotation, surgeons should consider not only dynamic gait analysis findings but also the measurement of anatomic femoral anteversion during intraoperative derotation.

Changes in gait parameters after femoral derotational osteotomy in cerebral palsy patients with medial femoral torsion

Medial femoral torsion (MFT) is a common pathologic gait in cerebral palsy (CP) children that can be corrected by femoral derotational osteotomy (FDO). It is not clearly known as to how much various gait parameters change after FDO. The aim of this study was to quantify changes in gait parameters after FDO. The study group included 19 young CP patients (28 limbs, age<20 years, average age: 13.2 years) with symptomatic MFT, treated with distal FDO. The study group was divided into two groups: the unilateral FDO group (UG) and the bilateral FDO group (BG). The mean degree of derotation was 24.6° (25.0° for UG, 24.4° for BG). Pre-FDO and post-FDO values of Staheli's rotational profiles and kinematic data were compared. A paired t-test and Pearson's correlation were used for statistical analysis. The mean internal hip rotation was 71.4±6.9° before surgery and 48.6±10.7° after surgery in the UG (P<0.05) and it was 63.8±15.8° before surgery and 40.9±9.2° after FDO in the BG (P<0.05). The change in the foot progression angle (FPA) was 12.9° in the UG group (P<0.05) and 12.6° in the BG group (P<0.05). The degree of FPA had changed by about a half of the surgical derotation angle. Changes in the mean hip rotation during gait were 14.8° in the UG (P<0.05) and 6.7° in the BG (P<0.05) groups. The overall pelvic rotation was not changed after surgery. However, in patients with preoperative compensatory pelvic rotation of more than 5°, there was a change of 5.3±4.8° in the UG and 6.6±1.54° in the BG after surgery (P<0.05). There was also a trend showing that the younger the patient, the more the pelvic rotation changed (P=0.069). In-toeing gait because of MFT improved with FDO in CP patients. The expected degree of postoperative correction of FPA and hip rotation is about a half of the FDO degree. The degree of compensatory pelvic rotation should be considered to determine the correction angle of FDO, especially in young patients with preoperative pelvic rotation of more than 5°.

Quantitative Assessment of Knee Progression Angle During Gait in Children With Cerebral Palsy

BACKGROUND

Abnormal hip rotation is a common deviation in children with cerebral palsy (CP). Clinicians typically assess hip rotation during gait by observing the direction that the patella points relative to the path of walking, which is referred to as the knee progression angle (KPA). Two kinematic methods for calculating the KPA are compared with each other. Video-based qualitative assessment of KPA is compared with the quantitative methods to determine reliability and validity.

METHODS

The KPA was calculated by both direct and indirect methods for 32 typically developing (TD) children and a convenience cohort of 43 children with hemiplegic type CP. An additional convenience cohort of 26 children with hemiplegic type CP was selected for qualitative assessment of KPA, performed by 3 experienced clinicians, using 3 categories (internal, >10 degrees; neutral, -10 to 10 degrees; and external, >-10 degrees).

RESULTS

Root mean square (RMS) analysis comparing the direct and indirect KPAs was 1.14+0.43 degrees for TD children, and 1.75+1.54 degrees for the affected side of children with CP. The difference in RMS among the 2 groups was statistically, but not clinically, significant (P=0.019). Intraclass correlation coefficient revealed excellent agreement between the direct and indirect methods of KPA for TD and CP children (0.996 and 0.992, respectively; P<0.001).For the qualitative assessment of KPA there was complete agreement among all examiners for 17 of 26 cases (65%). Direct KPA matched for 49 of 78 observations (63%) and indirect KPA matched for 52 of 78 observations (67%).

CONCLUSIONS

The RMS analysis of direct and indirect methods for KPA was statistically but not clinically significant, which supports the use of either method based upon availability. Video-based qualitative assessment of KPA showed moderate reliability and validity. The differences between observed and calculated KPA indicate the need for caution when relying on visual assessments for clinical interpretation, and demonstrate the value of adding KPA calculation to standard kinematic analysis.

LEVEL OF EVIDENCE

Level II-diagnostic test.

Preoperative hip rotation moments do not predict long-term development after femoral derotation osteotomy in children with cerebral palsy

BACKGROUND

Femoral derotation osteotomy (FDO) is the standard treatment for internal rotation gait (IRG) in children with cerebral palsy (CP) although high rates of recurrence have been reported recently. Various factors associated with recurrence could be identified, but no predictor named.

RESEARCH QUESTIONS

Does FDO lead to a change of internal transversal hip moments? Are preoperative internal transversal hip moments a predictor for recurrence of IRG?

METHODS

41 children with spastic bilateral CP and 72 limbs that received a FDO (10.4 ± 2.7 years at surgery) were included retrospectively. Kinematic data were analyzed pre- (2 ± 3 months), postoperatively (12 ± 3 months) and at long-term follow-up (at least five years postoperatively; 84 ± 13 months), internal transversal hip moments were analyzed pre- and postoperatively.

RESULTS

The maximum peaks of the internal hip rotation moment during loading response decreased significantly (p = 0.003). The minimum during the second half of the stance phase increased significantly (p = 0.004) and the initially internal externally rotating moment changed to an internal internally rotating moment. No correlation between changes in hip rotation from postoperatively to the long-term follow-up and the preoperative internal hip rotation moment could be identified.

SIGNIFICANCE

FDO leads to changes in internal hip rotation moments. Preoperative internal hip rotation moments can't be used as predicting factor for recurrence of IRG. The data suggest, that recurrence of IRG depends less on patient specific motion patterns, but more on the time point of surgery and the therapy of all concomitant deformities during SEMLS.

Long-term development of overcorrection after femoral derotation osteotomy in children with cerebral palsy

BACKGROUND

Recent studies showed rates of recurrence of internal rotation gait (IRG) after femoral derotation osteotomy (FDO) up to 40%. Some surgeons even advice overcorrection during FDO to avoid a later recurrence.

RESEARCH QUESTION

Evaluation of the long-term development of limbs with initial overcorrection after FDO.

METHODS

29 limbs of 20 children (9.9 ± 3.2 years at surgery) with IRG, cerebral palsy (CP) and more than 5° external hip rotation postoperatively were included retrospectively. A gait analysis and clinical examination were performed preoperatively (less than one year, E0), postoperatively (9-23 months, E1) and at the long-term follow-up (at least five years postoperatively, E2). Differences between those children that remained overcorrected at E2 and those with a hip rotation within normal range at E2 were evaluated.

RESULTS

At E2 41% of these limbs remained overcorrected, 52% showed a hip rotation within normal range and 7% showed recurrence of IRG. A comparison of those limbs that remained overcorrected and those ending within normal range revealed neither a difference in age at surgery nor in static and dynamic torsional parameters at E0 and E1 except for pelvic rotation. A significantly larger pelvic internal rotation at E1 for those with remaining overcorrection could be identified.

SIGNIFICANCE

A general overcorrection during FDO in children with CP to avoid recurrence of IRG cannot be recommended, as 41% remain overcorrected. Preoperative predictors for long-term development couldn't be identified. If pelvic mal-rotation is corrected, hip rotation may change into normal range over the time in combination with the development of a flexed knee gait.

Persistence and Recurrence Following Femoral Derotational Osteotomy in Ambulatory Children With Cerebral Palsy

BACKGROUND

Excessive hip internal rotation is frequently seen in children with cerebral palsy (CP). Femoral derotational osteotomy (FDO) is effective in the short term, but factors associated with long-term correction remain unclear. The purposes of this study were to define the incidence of persistence and recurrence of hip internal rotation following FDO in ambulatory children with CP and to evaluate factors that influence outcome.

METHODS

Following IRB approval, kinematic and passive range of motion (PROM) variables were retrospectively evaluated in children with spastic CP who had FDO to correct hip internal rotation as part of clinical care at a children's specialty hospital. Children included had a preoperative evaluation (Vpre), a short-term postoperative evaluation (Vshort, 1 to 3 y post), and, in some cases, a long-term postoperative evaluation (Vlong, ≥5 y post). Age at surgery, physical exam measures, and kinematics variables were evaluated as predictors for dynamic and static recurrence.

RESULTS

Kinematic hip rotation improved from 14±12 degrees (Vpre; internal positive) to 4±13 degrees (Vshort) and relapsed to 9±15 degrees long term (P<0.05 Vpre/Vshort/Vlong; 99 limbs). Hip PROM midpoint improved from 23±9 degrees (Vpre) to 8±11 degrees (Vshort) and relapsed to 14±13 degrees (P<0.01 Vpre/Vshort/Vlong). Persistent hip internal rotation was noted in 41% (kinematics) and 18% (PROM) of limbs at Vshort (105 children, 178 limbs). Of limbs that showed initial improvement at Vshort (62 children, 95 limbs), recurrence was seen in 40% (kinematic hip rotation) and 39% (hip midpoint) at Vlong. Comparing children who had recurrent hip internal rotation and those who maintained long-term correction, we saw higher levels of spasticity and lower gait velocity in the recurrent group (P<0.05).

CONCLUSIONS

Although FDO is an accepted treatment in children with CP, persistence and recurrence of hip internal rotation can occur. Recurrence is associated with spasticity and slower gait velocity. Predictor variables may be useful for surgeons during preoperative discussions of expected outcome with families of FDO candidates.

LEVEL OF EVIDENCE

Level III.

Electromagnetic tracking for femoral derotation osteotomy-an in vivo study

Femoral derotation osteotomy delivers good to excellent results in the treatment of rotational gait abnormalities and especially in internal rotation gait. The outcome of the procedure has been evaluated in numerous short- and long-term studies. Although reasons for recurrence and over-/under-correction have been unveiled in earlier studies the mechanisms are still not fully understood. False intra-operative assessment of the derotation angle may contribute to imprecise outcomes. In a recent saw-bone study we evaluated an electromagnetic tracking system in comparison to conventional goniometer measurement and a CT reference measurement and found it to be extremely accurate, whereas the use of a conventional goniometer for derotation measurement showed a high inter- and intra-rater variability. The current study evaluates the electromagnetic tracking system for continuous intra-operative derotation control under real OR conditions. Adults (age: 18-40 years) with the diagnosis of internal rotation gait, independent of the underling pathology, undergoing a supracondylar deroation osteotomy were included. A rotational CT scan was conducted before and in close proximity after surgery and the difference served as reference for the electromagnetic tracking results. The results showed a mean deviation of 2.6° (1.2-5.5°) in comparison to the reference measurement of the pre- and post-operative CT scans. The system proved to be stable under OR conditions with a good usability and a small technical footprint. Electromagnetic tracking delivers a precise, reliable, and independent assessment of intra-operative derotation angles in femoral derotation osteotomies. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2652-2657, 2017.

Effects of multilevel surgery on a flexed knee gait in adults with cerebral palsy

Aims

A flexed knee gait is common in patients with bilateral spastic cerebral palsy and occurs with increased age. There is a risk for the recurrence of a flexed knee gait when treated in childhood, and the aim of this study was to investigate whether multilevel procedures might also be undertaken in adulthood.

Patients and Methods

At a mean of 22.9 months (standard deviation 12.9), after single event multi level surgery, 3D gait analysis was undertaken pre- and post-operatively for 37 adult patients with bilateral cerebral palsy and a fixed knee gait.

Results

There was a significant improvement of indices and clinical and kinematic parameters including extension of the hip and knee, reduction of knee flexion at initial contact, reduction of minimum and mean knee flexion in the stance phase of gait, improved range of movement of the knee and a reduction of mean flexion of the hip in the stance phase. Genu recurvatum occurred in two patients (n = 3 legs, 4%) and an increase of pelvic tilt (> 5°) was found in 12 patients (n = 23 legs, 31%).

Conclusion

Adult patients with bilateral cerebral palsy and a flexed knee gait benefit from multilevel surgery including hamstring lengthening. The risk of the occurence of genu recurvatum and increased pelvic tilt is lower than has been previously reported in children. Cite this article: Bone Joint J 2017;99-B:1256–64.

Changes in hip abductor moment 3 or more years after femoral derotation osteotomy among individuals with cerebral palsy

AIM

To examine the effect of femoral derotation osteotomy (FDO) on dimensionless hip abductor moment during gait in children with cerebral palsy.

METHODS

We retrospectively analyzed data from independent ambulators within our database. Postoperative visits 1 year (short-term) and at least 3 years (mid-term) were analyzed. We estimated the coronal plane hip abductor moment arm based on musculoskeletal modeling that accounted for anteversion and hip rotation.

RESULTS

There were 140 individuals with a short-term analysis (77 males, 63 females; age at surgery 9y 11mo [range 4y 5mo-17y 5mo]) and 29 with mid-term analysis (15 males, 14 females; age at surgery 8y 7mo [range 4y 5mo-13y 1mo]). At short-term, anteversion and internal hip rotation decreased 35° and 13° respectively, which increased median (IQR) moment arms from 20 (23) per cent below normal to 2 (12) per cent above normal. Dimensionless mean hip abductor moment remained unchanged at short-term. Mid-term anteversion did not change but hip rotation increased 8° and hip abductor moment increased to 0.040 (0.029). There was no change in pelvic and trunk obliquity, although hip abductor strength increased and walking velocity decreased at mid-term.

INTERPRETATION

The unexpected lack of improvement in hip abductor moment from pre- to short-term may be caused by gait compensations that unload the hip. The increase in hip abductor moment beyond 3 years postoperatively underscores the benefits of an FDO into adolescence for independent ambulating individuals with cerebral palsy.

Long-term outcomes of external femoral derotation osteotomies in children with cerebral palsy

External femoral derotation osteotomy (FDO) is an orthopaedic intervention to correct increased femoral anteversion and associated excessive internal hip rotation and internal foot progression during gait in children with cerebral palsy. The resulting functional issues may include clearance problems and hip abductor lever-arm dysfunction. The purpose of this study was to evaluate long-term gait outcomes of FDO. Twenty ambulatory patients (27 sides) with cerebral palsy who underwent pre-operative (P0) and a one year post-operative (P1) gait analysis as part of the standard of care had a second post-operative analysis (P2) approximately 11 years post-surgical intervention. Mean hip rotation in stance showed statistically significant decreases in internal rotation at P1 post-surgical intervention that were maintained long-term (mean hip rotation P0: 21±9, P1: 0±9 and P2: 6±12 degrees internal). Similar results were seen with mean foot progression (P0: 9±16 degrees internal, P1: 14±13 degrees external, P2: 13±16 degrees external). However, 2/27 sides (9%) showed a recurrence of internal hip rotation of >15° at the 11year follow-up. The reasons for this recurrence could include age, surgical location and ongoing disease process all of which need to be further examined. We conclude that FDO can show long-term kinematic and functional benefits when performed in the prepubescent child with cerebral palsy in comparison to the natural progression of of hip rotation in cerebral palsy.

Electromagnetic bone segment tracking to control femoral derotation osteotomy-A saw bone study

Correction of rotational gait abnormalities is common practice in pediatric orthopaedics such as in children with cerebral palsy. Femoral derotation osteotomy is established as a standard treatment, however, different authors reported substantial variability in outcomes following surgery with patients showing over- or under-correction. Only 60% of the applied correction is observed postoperatively, which strongly suggests intraoperative measurement error or loss of correction during surgery. This study was conducted to verify the impact of error sources in the derotation procedure and assess the utility of a newly developed, instrumented measurement system based on electromagnetic tracking aiming to improve the accuracy of rotational correction. A supracondylar derotation osteotomy was performed in 21 artificial femur sawbones and the amount of derotation was quantified during the procedure by the tracking system and by nine raters using a conventional goniometer. Accuracy of both measurement devices was determined by repeated computer tomography scans. Average derotation measured by the tracking system differed by 0.1° ± 1.6° from the defined reference measurement . In contrast, a high inter-rater variability was found in goniometric measurements (range: 10.8° ± 6.9°, mean interquartile distance: 6.6°). During fixation of the osteosynthesis, the tracking system reliably detected unintentional manipulation of the correction angle with a mean absolute change of 4.0° ± 3.2°. Our findings show that conventional control of femoral derotation is subject to relevant observer bias whereas instrumental tracking yields accuracy better than ±2°. The tracking system is a step towards more reliable and safe implementation of femoral correction, promising substantial improvements of patient safety in the future. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1106-1112, 2017.

Correlation between transverse plan kinematics and foot progression angle in children with spastic diplegia

In diplegic patients, the orientation of foot progression depends on multiple factors. We investigated the relationship between foot progression alignment, hip and pelvic rotations during gait, femoral anteversion, and tibial torsion. Kinematic and clinical parameters were evaluated for 114 children who walked independently and had not undergone previous surgery. Causes of intoeing presented combined in 72% of cases. Internal foot progression correlated with internal hip rotation and showed an inverse correlation with tibial torsion. Our results indicate that data from clinical examination and gait analysis should be evaluated carefully before making treatment recommendations, especially in terms of the correction of torsional problems, in patients with cerebral palsy.

Contribution of clinical gait analysis to single-event multi-level surgery in children with cerebral palsy

Clinical gait analysis (CGA) has been proven useful in understanding the gait disturbances seen in children and adolescents with cerebral palsy. Another major benefit provided by CGA is a clinical and scientific evaluation of how orthopaedic surgical procedures modify gait. The information provided by instrumented CGA complements the clinical data, and the two must be interpreted jointly. Although there is some variability in the surgical details of therapeutic strategies, CGA undoubtedly influences the planning of surgery. Although CGA improves surgical outcomes, these remain challenging to predict. CGA seems cost-effective. Internal hip rotation gait is used as an example to illustrate those benefits.

Dynamic motor control is associated with treatment outcomes for children with cerebral palsy

AIM

To estimate the impact of dynamic motor control on treatment outcomes in children with cerebral palsy.

METHOD

We used multiple regression on a retrospective cohort of 473 ambulatory children with cerebral palsy who underwent conservative treatment, single-level orthopaedic surgery, single-event multi-level orthopaedic surgery, or selective dorsal rhizotomy. Outcomes included gait pattern, gait speed, energy cost of walking, and the Pediatric Outcomes Data Collection Instrument. Explanatory variables considered were pre-treatment levels of each outcome, treatment group, prior treatment, age, and dynamic motor control computed from surface electromyography using synergy analysis. Effect sizes were estimated from the adjusted response.

RESULTS

Pre-treatment levels had effect sizes 2 to 13 times larger than the next largest variable. Individuals with milder pre-treatment involvement had smaller gains or actual declines. Dynamic motor control was significant in all domains except energy cost. The effect size of dynamic motor control was second only to pre-treatment level, and was substantially larger than the effect size of treatment group for outcomes where both were significant (gait pattern 2:1, gait speed 4:1). The effect of dynamic motor control was independent of treatment group.

INTERPRETATION

Dynamic motor control is an important factor in treatment outcomes. Better dynamic motor control is associated with better outcomes, regardless of treatment.

Long-term changes in femoral anteversion and hip rotation following femoral derotational osteotomy in children with cerebral palsy

BACKGROUND

Excessive femoral anteversion is common in cerebral palsy (CP), is often associated with internal hip rotation during gait, and is frequently treated with a femoral derotational osteotomy (FDO). Concerns exist regarding long-term maintenance of surgical outcomes. Past studies report varying rates of recurrence, but none have employed a control group.

METHODS

We conducted a retrospective analysis examining long-term (∼5 years) changes in anteversion and hip rotation following FDO in children with CP. We included a control group that was matched for age and exhibited excessive anteversion (>30°) but did not undergo an FDO. Anteversion, mean stance hip rotation, and rates of problematic remodeling and recurrence were assessed (>15° change and final level outside of normal limits).

RESULTS

The control group was reasonably well matched, but exhibited 9° less anteversion and 3° less internal hip rotation at the pre time point. At a five year follow-up, the FDO group had less anteversion than the control group (20° vs. 35°, p<0.05). The mean stance phase hip rotation did not differ between the groups (4° vs. 5°, p=0.17). Over one third of limbs remained excessively internal in both groups (FDO: 34%, Control: 37%). Rates of problematic recurrence and remodeling were low (0%-11%).

CONCLUSIONS

An FDO is an effective way to correct anteversion in children with CP. Long-term hip rotation is not fully corrected by the procedure, and is not superior to a reasonably well matched control group. Rates of problematic recurrence and remodeling are low, and do not differ between the groups.

Femoral derotation osteotomy in adults with cerebral palsy

BACKGROUND

Internal rotation gait constitutes a complex gait disorder in bilateral spastic cerebral palsy (BSCP) including static torsional and dynamic components resulting in lever arm dysfunction. Although femoral derotation osteotomy (FDO) is a standard procedure to correct increased femoral anteversion in children, unpredictable outcome has been reported. The effect of FDO when it is done as part of single-event multilevel surgery (SEMLS) in adulthood has not been investigated.

METHODS

In this study mid-term data of 63 adults with BSCP and internal rotation gait, undergoing SEMLS including FDO were analyzed pre- and 1.7 years postoperatively by clinical examination and 3D-instrumented gait analysis. All legs were categorized as the more or less involved side to consider asymmetry. The mean hip rotation in stance preoperatively and the intraoperative derotation was correlated with the difference pre- and postoperatively.

RESULTS

The group as a whole experienced the following results postoperatively: improved mean hip rotation in stance (p=0.0001), mean foot progression angle (p=0.0001) and a significant improvement of the clinical parameter: passive internal and external hip rotation, midpoint and anteversion (p=0.0001) for both legs separately. With regard to the less and more involved side, clinical and kinematic parameters showed comparable significant changes (p=0.0001). The anteversion improved significantly in proximal compared to distal FDO (p=0.03).

CONCLUSION

This study emphasizes an overall good correction of internal rotation gait in adults with bilateral involvement after FDO. However, the results are more predictable in adults compared to studies reporting outcome after FDO in children.

Computer assistance in femoral derotation osteotomy: a bottom-up approach

Severe gait abnormalities in patients with cerebral palsy are often treated by correction osteotomy. The established procedure of femoral derotation osteotomy (FDO) has proven effective to realign femur anteversion. Nevertheless, studies have revealed that therapy outcome is subject to substantial inter-patient variability and systematic loss of correction. Our previous work suggests that practical limitations in FDO may significantly contribute to this effect. In this work, we propose a novel computer assisted measurement system to support FDO with objective measurement (desired accuracy: ∼ ± 3°) and continuous monitoring of derotation. A prototype system based on the clinically emerging electromagnetic tracking technology is demonstrated which incorporates technical and operational considerations to enable continuous measurement in OR conditions while preserving the conventional workflow without disruptions. In phantom studies, the achieved measurement accuracy (standard error $\cong\pm 1.6{}^{\circ})$ proved high potential and may hugely benefit the quality of surgical execution. Currently, the prototype system is assessed under OR conditions in an in-vivo study with CP patients. Early experience shows high appreciation among surgeons and good potential for future application.

Measuring physiological and pathological femoral anteversion using a biplanar low-dose X-ray system: validity, reliability, and discriminative ability in cerebral palsy

OBJECTIVE

The aims of this study were to evaluate the concurrent validity and reliability of a low-dose biplanar X-ray system (Ld-BPR) for the measurement of femoral anteversion (FA) by comparing Ld-BPR-based three-dimensional measures with CT-scan-based measures and to assess the discriminative ability of this method in children with cerebral palsy.

MATERIALS AND METHODS

Fifty dry femora were scanned using both a CT scan and the Ld-BPR system. Ten femora were artificially modified to mimic a range of anteversion from -30° to +60° and scanned by both modalities. FA was quantified using the images from both modalities and statistically compared for concurrent validity. Intra- and inter-observer reliability of the Ld-BPR system was also determined. Further, Ld-BPR data from 16 hemiplegic and 22 diplegic children were analyzed for its discriminative ability.

RESULTS

The concurrent validity between the Ld-BPR and CT-scan measures was excellent (R (2) = 0.83-0.84) and no significant differences were found. The intra- and inter-trial reliability were excellent (ICCs = 0.98 and 0.97) with limits of agreement of (-2.28°; +2.65°) and (-2.76°; +3.38°) respectively. Further, no significant effects of angle or method were found in the sample of modified femora. Ld-BPR measures for FA were significantly different between healthy and impaired femora.

CONCLUSIONS

The excellent concurrent validity with the CT scan modality, the excellent reliability, and the ability to discriminate pathological conditions evaluated by this study make this radiological method suitable for a validated use across hospitals and research institutes.

Femoral derotation osteotomy with multi-level soft tissue procedures in children with cerebral palsy: Does it improve gait quality?

PURPOSE

Poor motor control and delayed thumb function and a delay in walking are the main factors which retard the natural decrease of the femoral anteversion (FA) with age. In addition, cerebral palsy (CP) patients usually have muscular imbalance around the hip as well as muscle contractures, both of which are main factors accounting for the increased FA which is commonly present in CP patients. The purpose of this retrospective study was to analyze the mid-term results of femoral derotational osteotomy (FDO) on the clinical findings, temporospatial and kinematic parameters of gait in children with CP.

METHODS

We performed a retrospective review of all patients diagnosed with CP and increased FA who were treated with FDO with multi-level soft tissue surgeries at a single institution between 1992 and 2011. FA assessment was done in the prone position, and internal (IR) and external rotation (ER) of the hip was measured in the absence of pelvis rotation. Surgical procedures were performed on the basis of both clinical findings and video analysis. Clinical findings, Edinburgh Visual Gait Scores (EVGS) and results from three-dimensional gait analysis were analyzed preoperatively and last follow-up.

RESULTS

A total of 93 patients with 175 affected extremities were included in this review. Mean age was 6.2 ± 3.1 (standard deviation) at initial surgery. The average length of the follow-up period was 6.3 ± 3.7 years. At the last follow-up, the postoperative hip IR had significantly decreased (73.9° vs. 46.2°; p < 0.0001), the hip ER had significantly improved (23.8° vs. 37°; p < 0.0001) and the popliteal angle had significantly decreased (64.2° vs. 55.8°; p < 0.0001). The total EVGS showed significant improvement after FDO (35.2 ± 6.4 vs. 22.5 ± 6.1; p < 0.001). Computed gait analysis showed significant improvement in the foot progression angle (FPA; 8.1° vs. -16.9°; p = 0.005) and hip rotation (-13.9° vs. 5.7°; p = 0.01) at the last follow-up. Stance time was improved (60.2 vs. 65.1 %; p = 0.02) and swing time was decreased (39.9 vs. 35.2 %; p = 0.03). Double support time and cadence were both decreased (p = 0.032 and p = 0.01).

CONCLUSIONS

Our data suggest that the FDO is an appropriate treatment strategy for the correction of FA and associated in-toeing gait in children with CP. Improvements in clinical and kinematic parameters were observed in both groups after FDO with multi-level soft tissue release. The most prominent effects of FDO were on transverse plane hip rotation and FPA.

Factors associated with recurrence after femoral derotation osteotomy in cerebral palsy

Femoral derotation osteotomy (FDO) as gold standard treatment for internal rotation gait in cerebral palsy (CP) leads to satisfying short-term results, whereas rates of recurrence up to 33% are reported in long-term outcome studies. The purpose of this study was therefore to identify factors contributing to recurrence of internal rotation gait in patients with CP who were treated with FDO in childhood. 70 patients (age: 10 (± 3.3) years at surgery) with bilateral CP and internal rotation gait were examined pre-, one year and at least five years (mean 8 ± 2 years) postoperatively after distal or proximal FDO, using standardized clinical examination and 3D gait-analysis. 27 patients had a good hip rotation one year postoperatively (between 5° external and 15° internal for both limbs) and were considered for the analysis of factors contributing to recurrence of internal rotation gait. Regarding all included patients both mean hip rotation and foot progression angle improved significantly (p < 0.001) from pre- to postoperative. A significant deterioration in hip rotation (more involved side) (p < 0.001) from one year postoperatively to the long-term follow-up can be observed. Younger age, reduced hip joint impulse, increased plantar flexion and internal foot progression angle postoperatively could be identified as factors for recurrence. FDO on average leads to a satisfactory correction of internal rotation gait. In order to improve the long-term outcome after FDO the time of multilevel surgery should be indicated as late as possible and the different factors leading to potential recurrence should be considered.

Correction of gait after derotation osteotomies in cerebral palsy: Are the effects predictable?

Derotation osteotomies of the femur and tibia are established procedures to improve transverse plane deformities during walking with inwardly pointing knees and in- and out toeing gait. However, effects of femoral derotation osteotomies on gait were reported to be small, and those for the tibia are not known. Therefore, the aim of the study was to show the relation between the amount of intraoperative rotation and the changes during gait for osteotomies at femur and tibia levels, and predict those for the femur from preoperative clinical and gait data. Forty-four patients with spastic cerebral palsy between 6 and 19 years were included, 33 limbs received rotation only at the femur, 8 only at the tibia and 12 limbs at both levels. Gait analysis and clinical testing was performed pre- and 21.4 (SD=1.8) months postoperatively. The amount of intraoperative derotation of the femur showed no significant correlation with the change in hip rotation during walking (R=-0.17, p=0.25), whereas the rotation of the tibia showed an excellent relationship (R=0.84, p<0.001) with the change in knee rotation. Preoperative hip rotation during walking explained only 18% of the variability of the postoperative change in hip rotation during gait. Strength and passive range of motion in hip extension and abduction as well as hip extension or abduction or foot progression during walking did not show any predictive significance. In conclusion changes of knee rotation during gait is directly predictable from the amount of tibial corrections, contrary the change in hip rotation was not related to the amount of femoral derotation, and prediction was only fair.

Asymmetric pelvic and hip rotation in children with bilateral cerebral palsy: uni- or bilateral femoral derotation osteotomy?

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 20° 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 25°. 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.

Superior functional outcome after femoral derotation osteotomy according to gait analysis in cerebral palsy

The femoral derotation osteotomy (FDO) is seen as the golden standard treatment in children with cerebral palsy and internal rotation gait. Variable outcomes with cases of over- and undercorrection mainly in the less involved patients have been reported. The determination of the amount of derotation is still inconsistent. 138 patients (age: 11 (± 3.3) years) with cerebral palsy and internal rotation gait were examined pre- and 1 year postoperatively after distal or proximal FDO, using standardized clinical examination and 3D gait analysis. Three groups were defined retrospectively depending on the amount of derotation in relation to the mean hip rotation in stance (MHR) during gait analysis: Group A (derotation angle > MHR + 10°), Group B (derotation angle = MHR ± 10°), Group C (derotation angle <MHR-10°), and compared according to their postoperative mean hip rotation. ANOVA with Bonferroni post hoc test was used for statistics (p < 0.05). Group B had the greatest benefit with the highest rate (86%) of good results (postoperative MHR = ± 15°). In contrast there were 14% cases of overcorrection and 5% cases of deterioration in Group A with only 81% good results and only 79% good results in Group C. It can be concluded, that it is less likely to have unsatisfactory outcomes if the amount of FDO is defined according to the findings of gait analysis compared with clinical examination.

Torsional force applied to the tibia of living lambs in an attempt to change the bone rotational axis

PURPOSE

To evaluate the effects of torsional force on the rotational axis of living lamb tibias.

METHODS

An external fixator device was designed to apply rotation to the tibias of lambs. Once a week, the bone distal extremity was rotated 2º. After achieving ~20º of internal rotation, the turning was discontinued and the device was maintained in situ for one month and euthanasia occurred in group A (n=10) after this. In group B (n=9) euthanasia occurred three months after removing the device. Computed tomography scans evaluated the rotational angle; dual-energy X-ray absorptiometry assessed the bone mineral density, and conventional and polarized light microscopy studied the bone microstructure.

RESULTS

In group A, the mean angle of the external rotation in the control tibias was 24º and 8º in the twisted tibias (p<0.0001); in group B, the angle was 23º (control) and 7º (twisted, p<0.0001), with no differences between groups A and B (p=0.9567). The BMD increased in the twisted tibias in group A (p<0.0001) and in group B (p=0.0023), with no between-group differences (p>0.05). Microscopically, the twisted tibias showed asymmetrical subperiosteal bone deposition on the lateral cortex surface.

CONCLUSION

Gradual torsion applied to the immature tibia significantly modified its rotational axis.

The effect of femoral derotation osteotomy on transverse plane hip and pelvic kinematics in children with cerebral palsy: a systematic review and meta-analysis

The purpose of this study was to systematically review the current literature to determine the effect of a femoral derotation osteotomy (FDRO) on hip and pelvic rotation kinematics during gait compared to no intervention in children with spastic cerebral palsy (CP). We performed a systematic search for prospective and retrospective cohort studies of children with CP, who were treated with a FDRO, and were assessed with pre and post surgery three-dimensional gait analysis. Medline, CINAHL, EMBASE, the Cochrane Library and Web of Science were searched up to December 2013. Data sources were prospective and retrospective studies. Mean differences were calculated on pooled data for both pelvic and hip rotation kinematics. Thirteen of 196 articles met the inclusion criteria (5 prospective, 8 retrospective). All included studies were of sufficient quality for meta-analysis as assessed using a customised version of the STROBE checklist. Meta-analysis showed that FDRO significantly reduced pelvic retraction by 9.0 degrees and hip internal rotation by 17.6 degrees in participants with unilateral CP involvement and hip internal rotation by 14.3 degrees in participants with bilateral CP involvement. Pelvic symmetry in children with unilateral spastic CP is significantly improved by FDRO. Patients with bilateral involvement do not improve their transverse plane pelvic rotation profiles during gait as a result to FDRO, although this result should be interpreted with caution due to the heterogeneous nature of these participants and of the methods used in the studies assessed.

Femoral derotational osteotomy: surgical indications and outcomes in children with cerebral palsy

Excessive femoral anteversion is common among children with cerebral palsy, and is, frequently treated by a femoral derotational osteotomy (FDO). It is important to understand surgical, indications for FDO, and the impact of these indications on the treatment outcomes. The Random Forest algorithm was used to objectively identify historical surgical indications in a large retrospective, cohort of 1088 limbs that had previously undergone single-event multi-level surgery. Treatment, outcome was based on transverse plane kinematics obtained from three-dimensional gait analysis. The, classifier effectively identified the historic indications (accuracy = .85, sensitivity = .93, specificity = .69, positive predictive value = .86, negative predictive value = .82), and naturally divided limbs into four, clusters: two homogeneous +FDO clusters (with/without significant internal hip rotation during gait), one homogeneous -FDO cluster, and a mixed cluster. Concomitant surgeries were similar among the, clusters. Limbs with excessive anteversion and internal hip rotation during gait had excellent outcomes, in the transverse plane. Limbs with excessive anteversion but only mild internal hip rotation had good, outcomes at the hip level; but a significant number of these limbs ended up with an excessive external, foot progression angle. The Random Forest algorithm was highly effective for identifying and, organizing historic surgical indications. The derived criteria can be used to give surgical decision making, guidance in a majority of limbs. The results suggest that limbs with anteversion and significant, internal hip rotation during gait benefit from an FDO, but limbs with excessive anteversion and only, mild internal hip rotation are at risk of developing an excessive external foot progression angle.

Impact of gait analysis on correction of excessive hip internal rotation in ambulatory children with cerebral palsy: a randomized controlled trial

AIM

The aim of this study was to determine if gait analysis improves correction of excessive hip internal rotation in ambulatory children with spastic cerebral palsy (CP).

METHOD

Children undergoing orthopedic surgery were randomized to receive or not receive a preoperative gait analysis report. This secondary analysis included all participants whose gait report recommended external femoral derotation osteotomy (FDRO). One-year postoperative, and pre- to postoperative change in femoral anteversion, mean hip rotation in stance, and mean foot progression in stance were compared between groups and in subgroups based on whether the recommendation for FDRO was followed.

RESULTS

Outcomes did not differ between the group which received a gait report (n=39; 19 males, 20 females; mean age 10y 4mo [SD 3y]; hemiplegia, 3; di/triplegia, 28; quadriplegia, 8; Gross Motor Function Classification System [GMFCS]: level I, 5; level II, 12; level III 19; level IV, 3) and the control group (n=26; 14 males, 12 females; mean age 9y 5mo [SD 2y 10mo]; hemiplegia, 1; di/triplegia, 21; quadriplegia, 4; GMFCS: level I, 4; level II, 1; level III, 9; level IV, 2; all p values >0.29), but improved more in the gait report subgroup in which the FDRO recommendation was followed (seven limbs; change in anteversion -32.9°, hip rotation -25.5°, foot progression -36.2°) than in the control group (anteversion -12.2°, hip rotation -7.6°, foot progression -12.4°; all p values ≤0.02) and the gait report subgroup in which FDRO was not performed (32 limbs; anteversion -1.0°, hip rotation 0.5°, foot progression -8.0°; all p values ≤0.003). Postoperative measures became normal only in the gait report subgroup in which the recommended FDRO was performed.

INTERPRETATION

Gait analysis can improve outcomes when its recommendations are incorporated in the treatment plan.

Do changes in torsional magnetic resonance imaging reflect improvement in gait after femoral derotation osteotomy in patients with cerebral palsy?

PURPOSE

Femoral derotation osteotomy (FDO) is commonly used to correct internal rotation gait (IRG) in spastic diplegia. The purpose of this study was to investigate whether the extent of intraoperative derotation is reflected in changes in static (clinical ROM and anteversion angle measured on torsional MRI) and dynamic parameters (transverse plane kinematics in three-dimensional gait analysis) after FDO in children with spastic diplegia.

METHODS

In a prospective study, 30 children with spastic diplegia and IRG were treated with FDO as part of a multilevel surgery and were examined pre- and postoperatively clinically, by three-dimensional gait analysis and by torsional MRI according to a standardised protocol.

RESULTS

A correlation (r = 0.317, p = 0.015) between the extent of intraoperative derotation and mean hip rotation in stance as well as the anteversion angle measured on torsional MRI (r = 0.454, p < 0.001) was found. However, no significant correlation was observed between anteversion angle (tMRI) and mean hip rotation in stance, either before or after FDO.

CONCLUSIONS

Significant improvements were found in IRG after FDO, confirming the results of previous studies. There was no correlation between the anteversion measured on MRI and the mean hip rotation in stance in 3D gait analysis before or after FDO. Thus, the data suggest that if the intraoperative extent of derotation is determined only by the anteversion angle, the result will not be better after FDO. It might only help to avoid retroversion and indicate the maximum amount of femoral derotation. In this study the extent of the intraoperative derotation was orientated at the preoperative midpoint of rotation. Based on the small, but significant correlation between the clinical midpoint and the mean hip rotation in stance in the gait analysis, determination of the intraoperative extent of derotation according to the mean hip rotation in stance seems to give the best results.

Long-term outcome of femoral derotation osteotomy in children with spastic diplegia

Satisfactory short-term results after femoral derotation osteotomy (FDO) for the treatment of internal rotation gait in cerebral palsy have been reported by various authors. However, there are only a few longer-term studies reporting results 5 years after FDO and these are not in agreement. There are no reports on the clinical course beyond the pubertal growth spurt. 33 children with diplegia (n=59 legs, age: 10.5±3.6 years) and internally rotated gait were examined pre- (E0), 1 year (E1), 3±1 (E2) and 9±2 (E3) years after distal (27 legs) or proximal (32 legs) FDO as part of multilevel surgery, using standardized clinical exam and 3D gait-analysis at all examinations. The amount of intra-operative derotation averaged 25°. ANOVA was used for statistics (p<0.05). Mean hip internal rotation in stance at E0 of 17.3° was significantly changed to 1.0° of external rotation at E1 and was maintained at 4.2° at E3. The same clinical course was found for foot progression angle. The mid-point of passive hip rotation at E0 was 21°. This was significantly decreased to 6° at E1 and showed a small but significant increase reaching 12° at E3. The results of this study showed a good overall correction of internally rotated gait following FDO. These improvements were maintained at long-term follow-up after the pubertal growth spurt. Recurrence was observed in some cases with overall severe deterioration. In those patients persistent dynamic factors leading to recurrence should be further investigated.

Gait parameters in a reference sample of healthy Spanish schoolchildren: multivariate descriptive statistics and asymmetries observed in left and right cycles

INTRODUCTION

Instrumental gait analysis is an emerging technology used increasingly to evaluate motor disorders in children. Normal reference data is necessary in order to evaluate patients, but there are few reference resources for the Spanish paediatric population.

OBJECTIVE

We aim to describe the values of 16 clinically relevant gait variables in healthy Spanish schoolchildren, and identify any linear associations or left-right asymmetries.

SUBJECTS AND METHODS

The values of 16 gait variables were determined in schoolchildren (n=27, aged 5-13 years) using instrumental gait analysis. We analysed asymmetries for each variable (Student's t-test for dependent samples) and calculated their confidence intervals (95% of the standardised difference in right and left means [SMD]). Values and associations between variables were represented using a heat map.

RESULTS

Our project presents normal values tables for 16 variables in the gait cycle. Significant asymmetries were detected in the mean values for minimum hip flexion (SMD: 0.25 95% CI, 0.11-0.39) and peak hip abduction in swing (SMD: -1.05 95% CI: -1.71--0.27). Functional associations among gait variables are present.

CONCLUSIONS

We present a reference dataset for Spanish school-aged children in which left-right asymmetries and functional associations may be observed for different variables.