The multifunctional adhesion molecule CD44 is a major cell-surface receptor for hyaluronic acid (HUA). Recent data suggest that it may also bind the ubiquitous bone-matrix protein, osteopontin (OPN). Because OPN has been shown to be a potentially important protein in bone remodelling, we investigated the hypothesis that OPN interactions with the CD44 receptor on bone cells participate in the regulation of the healing of fractures. We examined the spatial and temporal patterns of expression of OPN and CD44 in healing fractures of rat femora by in situ hybridisation and immunohistochemistry. We also localised HUA in the fracture callus using biotinylated HUA-binding protein.

OPN was expressed in remodelling areas of the hard callus and was found in osteocytes, osteoclasts and osteoprogenitor cells, but not in cuboidal osteoblasts which were otherwise shown to express osteocalcin. The OPN signal in osteocytes was not uniformly distributed, but was restricted to specific regions near sites where OPN mRNA-positive osteoclasts were attached to bone surfaces. In the remodelling callus, intense immunostaining for CD44 was detected in osteocyte lacunae, along canaliculi, and on the basolateral plasma membrane of osteoclasts, but not in the cuboidal osteoblasts. HUA staining was detected in fibrous tissues but little was observed in areas of hard callus where bone remodelling was progressing.

Our findings suggest that OPN, rather than HUA, is the major ligand for CD44 on bone cells in the remodelling phase of healing of fractures. They also raise the possibility that such interactions may be involved in the communication of osteocytes with each other and with osteoclasts on bone surfaces. The interactions between CD44 and OPN may have important clinical implications in the repair of skeletal tissues.

We have studied fracture-dislocation of the fifth lumbar vertebra in seven patients and reviewed 50 previously reported cases. Based on this information, we have classified the injury into five types: type 1, unilateral lumbosacral facet-dislocation with or without facet fracture; type 2, bilateral lumbosacral facet-dislocation with or without facet fracture; type 3, unilateral lumbosacral facet-dislocation and contralateral lumbosacral facet fracture; type 4, dislocation of the body of L5 with bilateral fracture of the pars interarticularis; and type 5, dislocation of the body of L5 with fracture of the body and/or pedicle, with or without injury of the lamina and/or facet.

Conservative treatment of fracture-dislocation of L5 is generally not effective because the lesion is fundamentally unstable. Planning of the operation should be made on the basis of the various types of injury.

It has been thought that lumbar intervertebral discs were innervated segmentally. We have previously shown that the L5-L6 intervertebral disc in the rat is innervated bilaterally from the L1 and L2 dorsal root ganglia through the paravertebral sympathetic trunks, but the pathways between the disc and the paravertebral sympathetic trunks were unknown.

We have now studied the spines of 17 rats to elucidate the exact pathways. We examined serial sections of the lumbar spine using immunohistochemistry for calcitonin gene-related peptide, a sensory nerve marker. We showed that these nerve fibres from the intervertebral disc ran through the sinuvertebral nerve into the rami communicantes, not into the corresponding segmental spinal nerve.

In the rat, sensory information from the lumbar intervertebral discs is conducted through rami communicantes. If this innervation pattern applies to man, simple decompression of the corresponding nerve root will not relieve discogenic pain. Anterior interbody fusion, with the denervation of rami communicantes, may be effective for such low back pain.

We investigated 21 pairs of twins for zygosity and idiopathic scoliosis. DNA fingerprinting confirmed that 13 pairs were monozygotic and eight were dizygotic. There was concordance for idiopathic scoliosis in 92.3% of monozygotic and 62.5% of dizygotic twins.

Of the 12 pairs of monozygotic twins concordant for idiopathic scoliosis, six showed discordant curve patterns but eight had differences in Cobb angle of less than 10°. Seven of the ten pairs of monozygotic twins had similar back shapes.

Our findings suggest that there is a genetic factor in the aetiology of idiopathic scoliosis; they also indicate that there is a genetic factor in both the severity of the curve and the general shape of the back.

We performed a prospective study using MRI to evaluate early necrosis of the femoral head in 48 patients receiving high-dose corticosteroids for the treatment of various autoimmune-related disorders. The mean interval from the initiation of corticosteroid therapy to the first MRI examination was 2 months (0.5 to 6). MRI was repeated, and the mean period of follow-up was 31 months (24 to 69).

Abnormalities were found on MRI in 31 hips (32%). The initial changes showed well-demarcated, band-like zones which were seen at a mean of 3.6 months after initiation of treatment with steroids. In 14 of these hips (45%) there was a spontaneous reduction in the size of the lesions about one year after treatment had started, but there was no further change in size with a longer follow-up.

We reviewed 33 patients (35 hips) after open reduction of congenital dislocation of the hip using Ludloff’s medial approach. The mean age at the time of operation was 14 months (5 to 29) and at the time of final follow-up 20.1 years (15 to 24) giving a mean duration of follow-up of 19.4 years (14 to 23). We evaluated the radiological results by the Severin classification and the extent of avascular necrosis using the criteria of Kalamchi.

At the latest review 16 hips (45.7%) were in Severin groups I or II (acceptable results) and 19 (54.3%) in Severin groups III, IV or V (unacceptable results). There was evidence of avascular necrosis in 15 hips (42.9%). The radiological results began to become worse at about the age of ten years when type-II avascular changes presented.

We conclude that Ludloff’s medial approach for open reduction is unsatisfactory for the treatment of congenital dislocation since about half of our patients required additional operations.

The afferent pathways of discogenic low-back pain have not been fully investigated. We hypothesised that this pain was transmitted mainly by sympathetic afferent fibres in the L2 nerve root, and in 33 patients we used selective local anaesthesia of this nerve.

Low-back pain disappeared or significantly decreased in all patients after the injection. Needle insertion provoked pain which radiated to the low back in 23 patients and the area of skin hypoalgesia produced included the area of pre-existing pain in all but one. None of the nine patients with related sciatica had relief of that component of their symptoms.

Our findings show that the main afferent pathways of pain from the lower intervertebral discs are through the L2 spinal nerve root, presumably via sympathetic afferents from the sinuvertebral nerves. Discogenic low-back pain should be regarded as a visceral pain in respect of its neural pathways. Infiltration of the L2 nerve is a useful diagnostic test and also has some therapeutic value.

We carried out MRI studies of 74 patients with end-plate and vertebral bone-marrow changes associated with degenerative lumbar disc disease. Abnormalities were classified into type A, with decreased signal intensities, and type B, with increased signal intensities on T1-weighted spin-echo images. Twenty-seven (73%) of the 37 patients with type-A changes had low back pain, in contrast to only four (11%) of the 37 patients with type-B changes. Lateral flexion-extension radiographs showed hypermobility in 26 patients (70%) with type-A changes, and in only six (16%) with type-B changes. Type-A changes correlated with segmental hypermobility and low back pain, while type-B changes were more common in patients with stable degenerative disc disease.

We used hydroxyapatite blocks to keep open Salter innominate osteotomies in 19 children (21 hips), avoiding the need for an autograft taken from the anterior superior iliac spine. Our results were satisfactory, with less deformation of the iliac bone, and a reduction of both blood loss and operating time.

We studied the use of gadolinium diethylenetriaminepentaacetic acid-enhanced MRI in the detection of pathological changes in the nerve roots of 25 patients with unilateral sciatica due to lumbar disc herniation. Enhancement was observed in the affected nerve roots within the root sleeve at the caudal edge of the herniation and was classified into three categories: grade 0, none; grade 1, enhancement restricted to a focal region within the sleeve; and grade 2, diffuse and homogeneous. The grade of enhancement correlated well with the severity of the sciatica, and was considered to be due to a disruption of the blood-nerve barrier, leading to oedema.

The exact measurement of femoral head cover is essential for an assessment of reduction of congenital dislocation of the hip. We have compared standard anteroposterior radiographs with computerised tomograms and thereby classified the shape of the acetabular roof into four types. We found that the CE angle of Wiberg is a more reliable measure of head cover when the lateral point of bony condensation of the roof is chosen as the reference point rather than the edge of the bone, where these two points do not overlap. We conclude that head cover can be more accurately determined in younger children with dysplastic hips by our 'refined' CE angle, than by the original method of Wiberg.

Hip arthrography was performed in 19 patients in the initial stage of Perthes' disease. Sphericity and subluxation were measured and it was found that subluxation was independent of the femoral head deformity. We therefore tried to identify the cause of early subluxation: in seven patients a swollen ligamentum teres was thought to be responsible, and was associated with medial pooling of the contrast medium. A swollen ligamentum teres was seen in another seven cases; the other five arthrograms were normal. These findings were further clarified by enhanced CT scans, which confirmed that ligament swelling may be an important cause of early subluxation.