Delayed diagnosis of developmental dysplasia of the hip in Northern Ireland: can we do better?

Developmental dysplasia of the hip (DDH) should be diagnosed as early as possible to optimise treatment. The current United Kingdom recommendations for the selective screening of DDH include a clinical examination at birth and at six weeks. In Northern Ireland babies continue to have an assessment by a health visitor at four months of age. As we continue to see late presentations of DDH, beyond one year of age, we hypothesised that a proportion had missed an opportunity for earlier diagnosis. We expect those who presented to our service with Tonnis grade III or IV hips and decreased abduction would have had clinical signs at their earlier assessments. We performed a retrospective review of all patients born in Northern Ireland between 2008 and 2010 who were diagnosed with DDH after their first birthday. There were 75 856 live births during the study period of whom 645 children were treated for DDH (8.5 per 1000). The minimum follow-up of our cohort from birth, to detect late presentation, was four years and six months. Of these, 32 children (33 hips) were diagnosed after their first birthday (0.42 per 1000). With optimum application of our selective screening programme 21 (65.6%) of these children had the potential for an earlier diagnosis, which would have reduced the incidence of late diagnosis to 0.14 per 1000. As we saw a peak in diagnosis between three and five months our findings support the continuation of the four month health visitor check. Our study adds further information to the debate regarding selective versus universal screening.

Pelvic kinematics and their relationship to gait type in hemiplegic cerebral palsy.

While there is general clinical consensus that children with Unilateral Spastic Cerebral Palsy (USCP) walk with an increased anterior pelvic tilt and the affected hemipelvis retracted, there is less agreement to observations in the coronal plane. Furthermore, the relationship of 3D pelvic kinematic parameters to the Winters, Gage and Hicks (WGH) hemiplegic gait classification has not been reported in the literature. Valid 3-D kinematic gait data were obtained in a representative population of 91 children with hemiplegia (56 M, mean age 10.8 yrs, age range 5-18 yrs; WGH classification Type I n=32, II n=5, III n=7, IV n=9, unclassified n=38). Deviations of symmetry and range of movement from our normative data set (n=48; 26F; mean age 9.9 yrs; age range 5-18 yrs) for mean tilt, tilt range, and difference between affected and unaffected sides for obliquity and rotation were defined as normal, mild, moderate or severe (<1 standard deviation (SD); >1<2 SD; >2<3 SD; >3 SD, respectively). Increased pelvic tilt range (>1 SD) was observed in 60.4% and pelvic retraction (>1 SD) was observed in 61.5% of USCP children in this study. Weak but significant correlations were found between WGH gait type and pelvic obliquity (ρ=0.29; p<0.01). No other correlations were found. Factors such as leg length discrepancy modify the functional leg length throughout the gait cycle contributing to the deviations observed. The evaluation of gait abnormalities in USCP should not be limited to the use of classifications based on sagittal plane kinematics but should seek to include 3D kinematics of the pelvis.

Further evidence of validity of the Gait Deviation Index.

In this paper, the relationship of the Gait Deviation Index (GDI) to gross motor function and its ability to distinguish between different Gross Motor Function Classification System (GMFCS) levels was determined. A representative sample of 184 ambulant children with CP in GMFCS levels I (n=57), II (n=91), III (n=22) and IV (n=14) were recruited as part of a population-based study. Representative gait cycles were selected following a 3D gait analysis and gross motor function was assessed using the Gross Motor Function Measure (GMFM). GDI scores were calculated in Matlab. Valid 3D kinematic data were obtained for 173 participants and both kinematic and GMFM data were obtained for 150 participants. A substantial relationship between mean GDI and GMFM-66 scores was demonstrated (r=0.70; p<0.001) with significant differences in mean GDI scores between GMFCS levels (p<0.001) indicating increasing levels of gait deviation in subjects less functionally able. The relationship between the GDI, GMFM and GMFCS in a representative sample of ambulators, lends further weight to the validity of the GDI scoring system. Furthermore it suggests that the subtleties of gait may not be wholly accounted for by gross motor function evaluation alone. Gait specific tools such as the GDI more likely capture both the functional and aesthetic components of walking.

The effects of industry standard averaging and filtering techniques in kinematic gait analysis.

INTRODUCTION: Conventional methods for determining normative gait patterns consist of filtering marker trajectories prior to processing with subsequent averaging of individual normalized data. This may result in temporal shifts of key parameters and potentially distort normative datasets. Nevertheless, this is the standard method employed by state of the art motion analysis systems. This study compared two different methods of averaging filtered and unfiltered kinematic data. METHODS: Forty-eight non-impaired children (22M, 26F, mean age 9.85 years, range 4.2-17 years) underwent three-dimensional gait analysis using a Vicon system (Vicon, Oxford, UK). Gait data were processed with and without the Woltring filtering routine, commonly used to minimize marker trajectory noise. Filtered data were imported into Matlab (MathWorks, Natick, MA) where a representative gait cycle (RGC) for each leg of all participants was selected. Mean and standard deviation values for left and right limbs (n=96) for filtered and unfiltered data were calculated for seven different parameters within the RGC, without respect to timing. Similar values were obtained using the standard method. The values from the different averaging methods with and without filtering were compared. RESULTS: Differences of up to 2.2 degrees were found between averaging methods and up to 3.31 degrees between filtered and unfiltered data. DISCUSSION: Both the Woltring filtering routine and the standard averaging method cause signal dampening. While a Matlab-based tool may afford greater scope when analysing kinematic gait data, the standard averaging method still returns representative values when utilising data from able-bodied subjects.

Arthrodiastasis in Perthes' disease. Preliminary results.

We have examined the effect of arthrodiastasis on the preservation of the femoral head in older children with Perthes' disease. We carried out a prospective trial in boys over the age of eight years and girls over seven years at the time of the onset of symptoms. The patients had minimal epiphyseal collapse and were compared with a conventionally treated, consecutive, historical control group. Arthrodiastasis was applied for approximately four months. The primary outcome measure was the extent of epiphyseal collapse at the end of the fragmentation phase. One of the 15 treated hips and nine of the 30 control hips showed a loss of height of 50% or more of the lateral epiphyseal column on the anteroposterior radiographs (Herring grade-C classification). On a Lauenstein view, one of the treated hips and 19 of the control hips showed at least a loss of height of 50% of the anterior epiphyseal column. The complications of arthrodiastasis included pin-site infection in most hips, transient joint stiffness in two, and breakage of a pin in two. The final outcome will be known when all the patients and the control group reach skeletal maturity.

Anterior physeal separation. A sign indicating a high risk for avascular necrosis after slipped capital femoral epiphysis.

A study of 78 children (110 hips) was undertaken in an attempt to assess the risk of avascular necrosis (AVN) after slipped capital femoral epiphysis based on the radiological appearances of the hip at the time of presentation. Physeal separation, which was defined as the amount of separation of the anterior lip of the epiphysis from the metaphysis on the frog lateral view, was assessed. Of the eight hips which developed AVN, seven had anterior physeal separation. We conclude that anterior physeal separation is associated with a high incidence of subsequent AVN after slipped capital femoral epiphysis and that screw fixation may not be appropriate in these patients.

Clinical screening for developmental dysplasia of the hip in Northern Ireland.

PROBLEM: The incidence of late diagnosed developmental dysplasia of the hip requiring surgery in Northern Ireland is high. The reported incidence was 1.14 per 1000 children born during 1983-7. DESIGN: Comparative retrospective study. BACKGROUND AND SETTING: Clinical screening programme in Northern Ireland. Key measure for improvement: Reduced rate of operative intervention in children with developmental dysplasia of the hip detected after 6 months of age. STRATEGIES FOR CHANGE: Increased emphasis on staff training, introduction of a centralised nurse led clinic to improve access to orthopaedic surgeons, and increased use of ultrasonography. EFFECTS OF CHANGE: The incidence of developmental dysplasia of the hip diagnosed after 6 months in children born between January 1991 and December 1997 fell to 0.59 per 1000, presumably due to improved early detection. Nevertheless, 29 (16%) of the affected hips were not diagnosed when the child was first referred in the first 3 months of life. In addition, for 27 affected hips in children diagnosed after the age of 6 months there was a known risk factor (family history or breech delivery). LESSONS LEARNT: Improvements to screening processes can reduce late incidence of developmental dysplasia of the hip. Further steps to improve detection in children with known risk factors and rate of detection at first referral could reduce late presentation further.

Effect of a rigid ankle-foot orthosis on hamstring length in children with hemiplegia.

Eighteen children with hemiplegia, mean age 8 years 5 months, underwent gait analysis and musculoskeletal modelling using specially designed software. The maximum lengths of the hamstrings were determined for each child walking in and out of an ankle-foot orthosis (AFO). The muscles were deemed to be short if shorter than the normal average -1SD. In bare feet 8 participants had short medial hamstrings with a higher proportion of these in the less involved individuals. All participants showed an increase in maximum hamstring length when wearing an AFO. In all but one child this was sufficient to restore hamstring length to within normal limits. These finding suggest that hamstring pathology in hemiplegic gait is usually secondary to more distal lower limb pathology.

Relevance of the popliteal angle to hamstring length in cerebral palsy crouch gait.

The popliteal angle is a widely used clinical means of assessing hamstring length in cerebral palsy patients. The relevance of the popliteal angle as a measure of hamstring length was assessed in this prospective study. Sixteen patients with cerebral palsy with crouch gait had their conventional and modified popliteal angles measured by nine observers on two separate occasions. With use of the conventional and modified forms of the test, 74 and 70%, respectively, of the observed variability was inter-and intraobserver related. The range of SDs for each observer using the conventional test was 7.1-13.6 degrees (average 10.9 degrees ), and with use of the modified form of the test, the range was 6.3-4.2 degrees (average 10.5 degrees ). The maximum hamstring length of each subject during gait was determined by three-dimensional modelling of their lower limbs. The modified popliteal angle measurements of the most repeatable observer demonstrated an inverse relationship between modified popliteal angle and maximum hamstring length (p < 0.01) and muscle excursion (p < 0.01). Only 10 of 32 limbs had short medial hamstrings.

The role of coagulation abnormalities in the development of Perthes' disease.

Recent reports have suggested an association between Perthes' disease and an underlying thrombophilic or hypofibrinolytic tendency. In Northern Ireland there is a high incidence of Perthes' disease (11.7 per 100,000 or 1 in 607 children) in a stable paediatric population. We reviewed 139 children with Perthes' disease and compared them with a control group of 220 aged- and gender-matched healthy primary schoolchildren with similar racial and ethnic backgrounds. There were no significant deficiencies of antithrombotic factors protein C, protein S, antithrombin III or resistance to activated protein C. A total of 53 (38.1%) of the children with Perthes' disease had a prolonged activated partial thromboplastin time (>38) compared with 13 (5.9%) of the control group (p < 0.001). Our findings have shown that using standard assays, thrombophilia secondary to antithrombotic factor deficiency or resistance to activated protein does not appear to be an aetiological factor for Perthes' disease. The cause of the prolonged activated partial thromboplastin time, usually associated with a clotting factor deficiency, is under further investigation.

The influence of ankle-foot orthoses on gait and energy expenditure in spina bifida.

We examined the effect of ankle-foot orthoses (AFOs) on gait and energy expenditure in children with spina bifida. Nine boys and three girls, 6 to 16 years of age, took part in the study. There were four children each with L4, L5, and sacral level lesions. Each child underwent gait analysis and energy consumption studies with and without AFOs. Walking speed was faster with AFOs (mean, 58 m/min) than without (mean, 50 m/min, p < 0.01). Stride length improved significantly (p < 0.001) from 0.89 m barefoot to 1.08 m with AFOs. Double support time was decreased from 0.32 seconds barefoot to 0.28 seconds with AFOs (p < 0.05). The oxygen cost of walking was significantly better with (0.33 mL/kg/m) than without AFOs (0.41 mL/kg/m, p < 0.001). Hip flexion at initial contact was increased. Ankle kinematics were unchanged, but ankle power generation showed a significant improvement; from 0.5 W/kg barefoot to 1.3 W/kg with AFOs. Increased ankle power generation results in improved hip flexion and stride length, which contributes to increased walking speed and reduced oxygen cost. The stability conferred by the AFOs is reflected in the reduced time spent in double support.

Deprivation, urbanisation and Perthes' disease in Northern Ireland.

It has been suggested that Perthes' disease is more prevalent in urban areas, and that the risk increases with deprivation. We present the findings of a preliminary analysis of Perthes' disease in Northern Ireland, which is shown to have one of the highest national annual rates of incidence in the world (11.6 per 100000). Of the 313 children diagnosed over a seven-year period, 311 were allocated to the enumeration districts of the 1991 census, thus allowing the incidence to be calculated using both spatial and non-spatial aggregation. The cases were grouped according to the size of the settlement from highly urbanised to open countryside and by level of area deprivation. While the incidence of Perthes' disease was found to be associated with indicators of the level of deprivation for areas, there was no evidence to suggest that there was an increased risk in urban areas; the highest rate was found in the most deprived rural category.

Botulinum toxin A in hamstring spasticity.

Hamstring injection of Botulinum toxin A (BtA) may have a role in the conservative management of flexed knee gait in cerebral palsy or in simulating the effect of surgery. Ten children who were likely to require future hamstring lengthening were injected. Short term outcome was assessed by clinical examination and 3-D gait analysis. Mean popliteal angle decreased by 16 degrees and maximum knee extension in stance increased by 8 degrees, the latter relapsing by 12 weeks. Mean pelvic tilt tended to increase suggesting that isolated hamstring weakening be approached with caution. Energy cost of walking was not significantly changed in six of the ten patients. A small increase in knee extension in stance was often associated with patient satisfaction. There are theoretical grounds for expecting an associated increased longitudinal muscle growth after BtA injection.

Musculoskeletal modelling in determining the effect of botulinum toxin on the hamstrings of patients with crouch gait.

This study aimed to determine the effect of hamstring botulinum toxin A (Btx-A) injection in 10 children with crouch gait in terms of changes in muscle length and lower-limb kinematics. Before Btx-A injection limb kinematics were recorded. Maximum hamstring lengths and excursions were calculated by computer modelling of the lower limb. Data were compared with the averaged hamstring lengths of 10 control children. Hamstrings were defined as short if their length was shorter than the average maximum length minus one standard deviation. Gait analysis was repeated 2 weeks after isolated hamstring Btx-A injection. Pre- and postinjection kinematic data and muscle lengths were then compared. Four of 18 injected limbs in three subjects had short medial hamstring before injection, none of the subjects had short lateral hamstrings. Muscle excursion was significantly reduced in the short and adequate maximum muscle length groups. A significant increase in the semimembranosus and semitendinosus length in all of the injected limbs was noted. Only in the short muscle group was a significant increase in muscle excursion observed. Knee extension improved by 13 degrees in the adequate muscle length group and by 15.6 degrees in the short muscle length group. Pelvic tilt and hip flexion increased in both groups non-significantly. Average walking speed postinjection increased from 0.60 ms(-1) to 0.71 ms(-1). Short hamstrings are over-diagnosed in crouch gait. Hamstring Btx-A injection in patients with crouch gait produces significant, repeatable muscle lengthening and improved ambulatory function.

Botulinum toxin A compared with stretching casts in the treatment of spastic equinus: a randomised prospective trial.

Conservative therapies for equinus in cerebral palsy may help to postpone calf surgery in younger children. This study reports a prospective randomised trial of intramuscular botulinum toxin A (BtA) as an alternative to serial casting in 20 children with a dynamic component to calf equinus. Outcome was assessed in the short term to show the effect of one treatment cycle. Assessments were by clinical examination, video gait analysis, and three-dimensional gait analysis. BtA was of efficacy similar to that of serial casting. Tone reduction in the BtA group allowed a more prolonged improvement in passive dorsiflexion, which may allow more opportunity for increase in muscle length. Gait analysis showed an improved mean ankle kinematic pattern in a subsection of both groups, which was maintained at 12 weeks in the BtA group, whereas the cast group relapsed. There were fewer side effects in the BtA group. Median time to reintervention was similar.

Botulinum toxin A in the hemiplegic upper limb: a double-blind trial.

In a randomised, double-blind study, the effects of intramuscular injection of botulinum toxin type A (BtA) into the upper limb were compared with those of normal saline solution in 14 patients with cerebral palsy; their mean age was 9 years. Range of movement and function were assessed before injection and at 2 and 12 weeks after injection. BtA injection significantly increased maximum active elbow and thumb extension and significantly reduced tone at wrist and elbow. The hand grasp-and-release score improved, representing a modest functional change, but fine motor function, assessed by the ability to pick up coins, did not improve and in some cases deteriorated temporarily. The most notable subjective change was the cosmetic benefit of reduced involuntary elbow flexion. The tone-reducing effect of BtA was clinically detectable in comparison with the placebo and patients and parents perceived the change as beneficial. The median of changes in the treatment group was small but the range was large, suggesting that BtA can be useful in selected patients.

Three-dimensional gait analysis in spina bifida.

This study was designed to determine gait patterns in children with lumbar and sacral neurologic level spina bifida. We studied a group of 28 children: 10 had L4-level lesions and a mean age of 11 years; eight had L5-level lesions and a mean age of 8 years; and 10 had S1-level lesions with a mean age of 12 years. A group of 15 normal children, mean age 10 years, was used for comparison. Each child underwent three-dimensional gait analysis using the Vicon system. We found that there were recognisable gait patterns for each level of spina bifida and that the abnormalities accurately reflected the muscle deficiencies present. The gait patterns approximated more closely to those of the normal group as the neurological level descended. The most important findings were of increased pelvic obliquity and rotation with hip abduction in stance (reflecting the gross Trendelenburg-type gait seen in these children) and persistent knee flexion throughout stance as a result of the absence of the plantar flexion-knee extension couple. We found that gait was not improved by tendon transfers performed either at the hip (posterolateral psoas transfer) or at the ankle (tibialis anterior transfer).

Energy consumption in children with spina bifida and cerebral palsy: a comparative study.

The authors looked for differences in the energy expenditure patterns of ambulant children with cerebral palsy and spina bifida. Oxygen consumption was measured according to type of cerebral palsy or level of spina bifida lesion, and in healthy children. The rate of oxygen consumption (mL/kg/min) was significantly higher in the children with diplegia than in those with hemiplegia or with spina bifida or the healthy children. Oxygen cost (mL/kg/m) was significantly higher and velocity was significantly slower in all the groups with disability than in the healthy children. The reason children with diplegia consumed more oxygen than other children when walking may be that their abnormal equilibrium reactions impaired their balance and their ability to control their walking speed.

Botulinum toxin A prevents the development of contractures in the hereditary spastic mouse.

The hereditary spastic mouse was studied as a model of cerebral palsy in childhood to test the hypothesis that intramuscular botulinum toxin A would prevent the development of calf-muscle contractures. A prospective randomised controlled trial of calf injection with botulinum A compared with injection of normal saline was performed on juvenile mice. At maturity, the calf muscles of the spastic mice were 16 per cent shorter than those of their normal siblings. The calf muscles of spastic mice injected with botulinum toxin A grew to within 2 per cent of normal length. This difference in mature muscle length was highly significant.