M. K. D. Benson

The Oxford Knee for unicompartmental osteoarthritis. The first 103 cases.

The Oxford Knee, a resurfacing prosthesis with a meniscal bearing, can be used for either bicompartmental or unicompartmental arthritis. The first 103 unicompartmental cases are presented at a mean time since operation of 36 months (range 21 to 56 months). In those cases with surviving arthroplasties, pain was relieved in 96%. The full range of pre-operative flexion was maintained and flexion deformity was improved from a mean of 6.7 to 5.4 degrees. Stability and alignment were restored to normal in nearly all the knees. Absence of the anterior cruciate ligament was associated with a significantly greater incidence of failure. Six failures occurred in 37 knees lacking a normal anterior cruciate ligament (16.2%); three occurred in 63 knees with a normal anterior cruciate ligament (4.8%) (p less than 0.02). Criteria for the future selection of patients have been deduced from our experience. The operation is recommended for knees with severe unicompartmental osteoarthritis in which all the ligaments are still intact.

Dynamic foot movement in children treated for congenital talipes equinovarus.

The aim of this study was to define objectively gait function in children with treated congenital talipes equinovarus (CTEV) and a good clinical result. The study also attempted an analysis of movement within the foot during gait. We compared 20 children with treated CTEV with 15 control subjects. Clinical assessment demonstrated good results from treatment. Three-dimensional gait analysis provided kinematic and kinetic data describing movement and moments at the joints of the lower limb during gait. A new method was used to study movement within the foot during gait. The data on gait showed significantly increased internal rotation of the foot during walking which was partially compensated for by external rotation at the hip. A mild foot drop and reduced plantar flexor power were also observed. Dorsiflexion at the midfoot was significantly increased, which probably compensated for reduced mobility at the hindfoot. Patients treated for CTEV with a good clinical result should be expected to have nearly normal gait and dynamic foot movement, but there may be residual intoeing, mild foot drop, loss of plantar flexor power with compensatory increased midfoot dorsiflexion and external hip rotation.

The reliability of measurements of pelvic radiographs in infants.

We have evaluated the reliability of the measurement of radiological indicators in developmental dysplasia of the hip. Three observers each independently assessed 60 pelvic radiographs from infants aged from 3 to 36 months. Errors from the true value of a single measurement made by a single observer (E1), of the average of two measurements by a single observer (E2), and of the average of two single measurements by two different observers (E3) were established for the acetabular index of Hilgenreiner, for the assessment of superior and lateral femoral displacement and for indicators of pelvic alignment. The errors for the assessment of the acetabular index were E1 +/- 5 degrees, E2 +/- 5 degrees, and E3 +/- 3.5 degrees. There was a significant correlation between the presence of an acetabular notch on the radiograph and an increased error in measurement (p = 0.01). Yamamuros measurement of lateral femoral displacement was more reliable than the Hilgenreiner distance. The errors of indicators of pelvic alignment showed a correlation with the age of the infant; the quotient of pelvic rotation was more reliable after seven months of age (p < 0.0001). The errors of the measurement of the symphysis os-ischium angle tended to increase with age and those of the measurement of the index of pelvic tilt decreased with skeletal maturation (p = 0.002).

Evaluation of Internet use by paediatric orthopaedic outpatients and the quality of information available.

Parents use the Internet increasingly for information about their childrens medical problems. There is no quality control for medical information content. The goals of our study were to assess Internet awareness by families seen in paediatric orthopaedic outpatients departments and the type, quality and reliability of information available, using clubfoot as an example. Parents accompanying children to the outpatients clinic were surveyed regarding the use of the Internet for medical information. They were asked about their ability to use the Internet, and whether this helped the consultation. To assess the quality of information available, the search phrases ‘clubfoot’ and ‘club foot’ were placed in the five most commonly used World Wide Web search engines. Web sites were evaluated for authorship, content and informational value using our own agreed scoring system, ranging from 0–100 points. Sixty-one percent of the questionnaires were completed, the mothers completed 67%. Eighty-four percent reported access to the Internet. Most found their searches useful and 26% were reminded of questions to ask at consultation. When a search for ‘clubfoot’ was carried out we found 11% of web sites were affiliated to academic institutions. There was a significant difference when the terms ‘clubfoot’ or ‘club foot’ were searched. Twenty-eight percent offered conventional information. Thirty-six percent of web sites were not related to congenital talipes equinovarus. The average information value was 26 points (0–98). Parents frequently use the Internet for information about paediatric orthopaedic consultations, prior to consultation. The quality of clubfoot information on the Internet is variable. The development of academic-based websites should be encouraged, as these offer the most useful information.

Surgical treatment of late developmental displacement of the hip. Results after 33 years.

The outcome of displaced hips treated by Somerville and Scotts method was assessed after more than 25 years. A total of 147 patients (191 displaced hips) was reviewed which represented an overall follow-up of 65.6%. The median age at the index operation was two years. During the first five years, 25 (13%) hips showed signs of avascular change. The late development of valgus angulation of the neck, after ten years, was seen in 69 (36%) hips. Further operations were frequently necessary. Moderate to severe osteoarthritis developed at a young age in 40% of the hips. Total hip replacement or arthrodesis was necessary in 27 (14%) hips at a mean age of 36.5 years. Risk factors identified were high dislocation, open reduction, and age at the original operation. Two groups of patients were compared according to outcome. All the radiographic indices were different between the two groups after ten years, but most were similar before. It takes a generation to establish the prognosis, although some early indicators may help to predict outcome.

Ultrasound and congenital dislocation of the hip. The importance of dynamic assessment

One-hundred newborn children at high risk of hip instability were prospectively assessed clinically and by ultrasound. The decision to treat was based only on the clinical examination. At the age of three months all the children were evaluated clinically and with an anteroposterior radiograph of the pelvis. None of the standard ultrasound measurements of acetabular depth and femoral head cover correlated with the outcome at three months. Dynamic assessment of stability was the only ultrasound technique that had a significant relation with outcome.

Microanatomy of the acetabular cavity and its relation to growth

The anatomy and development of the growing acetabulum are not clearly understood. We dissected and studied histologically two acetabula from the pelvis of a three-month-old infant. Relative rates of growth at the different growth plates were assessed by comparing the height of the proliferative layer with that of the hypertrophic layer. The three bones which form the acetabulum are surrounded by growth plates on all sides except medially. These face towards the centre of the triradiate cartilage, the limbs of the triradiate cartilage and the articular surface and each may be divided into four distinct areas according to the orientation of its cell columns which reflect the direction of growth. Growth was particularly rapid at the ischial growth plates directed towards the centre and the articular cartilage, add on both sides of the anterior limb of the triradiate cartilage. These findings may explain the mechanism by which the acetabulum changes orientation and inclination with growth.

MRI AFTER OPERATIVE REDUCTION FOR DEVELOPMENTAL DYSPLASIA OF THE HIP

We performed MRI on 13 infants after operative reduction for developmental dysplasia of the hip (DDH). Using an axial gradient-echo sequence, MRI accurately depicted the acetabular anatomy and confirmed adequate reduction in 12 patients. The one patient with redislocation after surgery was correctly identified. MRI can be carried out quickly, inexpensively and without risk of radiation and is the investigation of choice to confirm adequate reduction in DDH.

Is there a place for shelf acetabuloplasty in the management of adult acetabular dysplasia? A SURVIVORSHIP STUDY

We followed up 76 consecutive hips with symptomatic acetabular dysplasia treated by acetabular shelf augmentation for a mean period of 11 years. Survival analysis using conversion to hip replacement as an end-point was 86% at five years and 46% at ten years. Forty-four hips with slight or no narrowing of the joint space pre-operatively had a survival of 97% at five and 75% at ten years. This was significantly higher (p = 0.0007) than that of the 32 hips with moderate or severe narrowing of the joint-space, which was 76% at five and 22% at ten years. There was no significant relationship between survival and age (p = 0.37) or the pre- and post-operative centre-edge (p = 0.39) and acetabular angles (p = 0.85). Shelf acetabuloplasty is a reliable, safe procedure offering medium-term symptomatic relief for adults with acetabular dysplasia. The best results were achieved in patients with mild and moderate dysplasia of the hip with little arthritis.

The ossific nuclei and the cartilage anlage of the talus and calcaneum

We studied the ossific nuclei on radiographs of the feet of three stillborn infants, two with club feet, relating the size, position and alignment of each nucleus to the cartilaginous talus or calcaneum in which it lay. Anteroposterior projections of the nucleus of the talus show deformity of that bone as well as subtalar malalignment. Lateral projections of the calcaneal nucleus may underestimate the degree of hindfoot equinus.