W Chow

Hereditary multiple exostoses of the hip

Purpose. To assess the radiographic features of 36 hips with hereditary multiple exostoses (HME). Methods. Hip parameters of 12 males and 6 females (36 hips) aged 2 to 28 years with HME were assessed using anteroposterior radiographs. The recorded features included the sites of osteochondromas, the femoral head/neck ratio, the Reimers migration percentage, Sharps acetabular angle, the centre edge angle, the femoral neck-shaft angle, and degenerative changes. Results. 15 of the 18 patients were asymptomatic; 3 complained of pain (2 underwent excision or bone biopsy); no lesion was malignant. Osteochondromas were most commonly located in the femur followed by the ilium; only one was intra-articular. 32 hips had coxa valga; 26 had an abnormal Reimers migration percentage; 17 had an abnormal Sharps acetabular angle; 12 had an abnormal centre edge angle; 32 had an abnormal femoral neck-shaft angle; and 6 had degenerative changes. Acetabular and femoral dysplasia as well as subluxation are common in patients with HME. Conclusion. Borderline subluxated hips and those with marked coxa valga and/or acetabular dysplasia should be closely monitored to determine the need for surgery in the future. Subluxated hips should be operated on early, particularly in children and symptomatic adults.

Screening for developmental dysplasia of the hip in Hong Kong.

Purpose. To review records of children referred to ousr hospital for developmental dysplasia of the hip (DDH) and evaluate the effectiveness of hip screening in Hong Kong. Methods. Records of children suspected of DDH and referred to our hospital between 1 January 2005 and 31 March 2010 were reviewed. The diagnosis was based on static and dynamic ultrasonography of the hips and/or radiographic features of hip subluxation, dislocation, and pelvic dysplasia. The age of the children at presentation was recorded. Late diagnoses were those presenting after the age of 6 months. Late presentations were those presenting after the walking age. Results. Of 213 referred children, 33 were diagnosed to have DDH. Their mean age at presentation was 90.8 (range, 9–559) days. The female-to-male ratio was 2.9:1, and the mean follow-up duration was 25.1 (range, 4.2–50.3) months. 30 of the DDH infants were diagnosed before the age of 6 months, one at 8 months, and 2 were late presenters. Hence, the failure rate of the hip screening was 0.09 per 1000 live births. The remaining 180 were confirmed to be normal and followed up until the walking age. The point prevalence of DDH on Hong Kong Island was 0.87/1000 live births. Conclusion. In light of the low point prevalence of DDH in Hong Kong born children, the protocol of universal clinical assessment and selective ultrasonographic screening of suspected cases is justified.

Genitopatellar syndrome: a case report of a rare entity with 11 years of follow-up.

Genitopatellar syndrome is one of the syndromes described in the last decade. It is characterized by agenesis of the corpus callosum, absent or hypoplastic patellae, extremity contractures, skeletal anomalies, urogenital anomalies, and facial dysmorphic features. While writing this report, only 15 cases have been reported in the literature. The etiology, clinical features, management, and natural history of this syndrome are not yet well established. Past reports in the literature have not been able to identify the exact genetic etiology but it somewhat coincides with nail patella syndrome and short patella syndrome. We would like to introduce this terminology to the orthopedic community and highlight the clinical features of the genitopatellar syndrome. To the best of our knowledge, this is a single case report with the longest follow-up of 11 years in the literature.

Radiographic assessment of congenital talipes equinovarus: strapping versus forced dorsiflexion.

Purpose. To compare 2 radiographic assessment methods for congenital talipes equinovarus: strapping the ankle with tapes versus dorsiflexion with a wooden block. Methods. Anteroposterior and lateral radiographs were taken with the ankle strapped by tapes or dorsiflexed by a wooden block. Talocalcaneal and tibiocalcaneal angles were measured and analysed. Results. 20 radiographic assessments were performed on 14 patients. From the anteroposterior view, the mean talocalcaneal angle with strapping was 19.4 degrees (range, 0–34.0; standard deviation [SD], 11.2 degrees). From the lateral view, the mean talocalcaneal angle with strapping was 22.0 degrees (range, 8.0–38.8; SD, 8.9 degrees) and with forced dorsiflexion was 21.0 degrees (range, 0–52.7; SD, 11.3 degrees), with a mean absolute difference of 9.4 degrees between the 2 groups. The mean tibiocalcaneal angle with strapping was 77.9 degrees (range, 43.2–120.0; SD, 18.8 degrees) and with forced dorsiflexion was 78.2 degrees (range, 29.5–134.0; SD, 24.7 degrees), with a mean absolute difference of 15.7 degrees between the 2 groups. The difference between the tibiocalcaneal measurements in the 2 groups was statistically significant (p=0.026). Conclusion. Similar results were obtained for talocalcaneal and tibiocalcaneal angles measured with strapping and forced dorsiflexion. However, the strapping method provides better stabilisation while radiographs are taken.

Normal radiographic parameters in paediatric pelvic radiographs from a Chinese population

Paediatric pelvic and hip radiographs are a common investigation used when assessing a child for suspected developmental dysplasia of the hip. This report describes an attempt to establish normal values of medial joint space, acetabular index and centre edge angle according to specific age groups and sex in a Chinese population. Patients who had undergone a pelvic radiograph as part of their assessment, but were subsequently found to have normal hips were recruited retrospectively. These patients were grouped according to sex and age; medial joint space, acetabular index and centre edge angle were measured in all radiographs. A mean±SD was calculated for each group, and then each age group was tested for statistical significance between the male and the female groups. A total of, 98 patients were recruited, who underwent 188 pelvic radiographs, resulting in images of 376 ‘normal’ hips. The results for medial joint space, acetabular index and centre edge angle for each age and sex group are described. Only the acetabular index requires different reference ranges for male and female patients because of consistent statistical significance between the two groups. It was found that medial joint space remained fairly constant throughout the age groups, whereas the acetabular index decreased and the centre edge angle increased slightly. The reference ranges for the parameters described here are quite different from those established previously in a population of Northern-European descent, which could be because of a variety of reasons including genetics, body habitus and measurement technique. We believe that it would be prudent to implement these different ranges when assessing patients of Chinese heritage to optimize care of patients who may suffer as a consequence of not receiving treatment for missed hip dysplasia. Level of Evidence: Diagnostic Study Level III – Study of nonconsecutive patients (without consistently applying the reference ‘gold’ standard).