A series of 123 patients suffering traumatic spondylolisthesis of the axis is reported. This lesion is associated with extension and axial loading injury, and there is a high incidence of injuries of the face or scalp and of associated fractures of the upper cervical spine. There is a low incidence of neurological injury, which seems paradoxical in the presence of what appears to be gross instability, but protection from extremes of flexion and extension may be adequate treatment. Union is usual regardless of displacement. Traction is a safe means of treatment, but early waking in a halo support reduces time in hospital without jeopardizing the result. Operation is needed only for chronic instability with or without pain, and anterior interbody fusion of C2--3 is than preferred in order to preserve rotation at the atlanto-axial joints.

The retrospective analysis of 131 patients suffering from a fracture of the ring of the axis is reported. The injury was classified into three types according to radiological displacement and stability. Associated injuries and neurological deficit are discussed and a theory of pathogenesis presented. Guidelines for the management of each type of fracture are proposed.

A thoracolumbar gibbus is an uncommon but potentially dangerous feature of achondroplasia. In a series of unselected South African Negro achondroplasts, nine out of 17 had an abnormality of this type. In contrast, only one girl out of 20 affected individuals of European or mixed ancestry had a gibbus. It is likely that the high frequency of this deformity in South African Negro achondroplasts is the result of the traditional practice by which an infant is carried on the mother's back, with the legs straddling her waist and the spine in flexion. Wedging on the vulnerable vertebral bodies in the Negro achondroplastic infant can probably be prevented by avoiding this custom.

Seventy-eight patients who had been operated on for bony entrapment of lumbar nerve roots were studied in an attempt to define the clinical syndrome, and to assess the results of a new technique of decompression which preserves spinal stability. The mean age of the patients was 45 years and 28 of them had previously undergone spinal operations. Pain in the leg was the predominant symptom, with evidence of motor involvement in half of the patients. Signs of nerve root tension were found in only one-third of the patients. The principal factor in the aetiology was degenerative change in the posterior facet joints. Decompression was achieved by a partial undercutting facetectomy. Fifty-nine per cent of the patients obtained a "good" result and 85 per cent were satisfied with the result of their operation. Successful partial facetectomy for bony entrapment of lumbar nerve roots produced rapid and lasting relief of pain.

This paper presents four patients with injuries to the thoracolumbar spine assessed by computerised tomography. This technique enabled an easy, quick and accurate diagnosis to be made, avoiding dangerous manipulation of the patient. The scans were analysed using the anatomical classification of Louis to evaluate the instability of the lesions. Control CT scans were used to monitor progress and to provide an accurate prognosis within acceptable limits of irradiation.

Exchange operation is recommended as the treatment of choice for most deep infections involving a total hip replacement. This revision arthroplasty comprises, in one stage, excision of soft tissue, removal of implant and cement, replacement with an appropriate implant using Palacos R acrylic cement loaded with an appropriate antibiotic and, more recently, systemic antibiotics. During our first 10 years without systemic antibiotics we have achieved an overall 77 per cent success rate from a first attempt in 583 patients and a 90 per cent success rate after subsequent exchange procedures. Morbidity is significant but acceptable. Success is defined as control of infection, no loosening, and useful function. The factors associated with failures include, in particular, specific infections (Pseudomonas group, Streptococcus group D, Proteus group, and Escherichia coli), delay in operation and inadequate antibiotic dosage in the cement.

A series of 400 patients (average age 57.7 years) with bilateral low-friction arthroplasties of the hip has been reviewed. Comparison was made with similar unilateral operations. The results showed that the bilateral arthroplasties can be carried out as a single operation without higher risk of local or general complications. However, this excludes the incidence of pulmonary embolism which is higher for the bilateral replacements.

A prospective randomised trial of surgical treatment for the displaced subcapital femoral fracture in patients of 70 years or more is presented. Two hundred and eighteen patients were randomly allocated into one of three treatment groups: manipulative reduction and internal fixation using Garden screws; Thompson hemiarthroplasty through a posterior (Moore) approach; and Thompson hemiarthroplasty through an anterolateral (McKee) approach. There is no significant difference in the mortality of the internal fixation and posterior arthroplasty groups. Both groups showed a significantly higher mortality than patients operated on through the anterior approach. The technical results of operation were worse in the internally fixed group, with only 40 per cent being satisfactory. Mobilisation was best achieved after the posterior approach. It is concluded that Thompson hemiarthroplasty, using an anterolateral approach, is the safest operation in this group of patients.

The treatment of fractures of the femoral shaft by traction may delay union and produce stiffness of the knee. The technique of Perkins' method is described and the results reported in 50 cases. All patients had at least 120 degrees of flexion of the knee when traction was discontinued, and 47 patients were considered to have clinical and radiological union of the fracture by 12 weeks. The main complications of the method was loosening of the Denham pin or infection of the pin-track in the proximal tibia. It is suggested that Perkins' traction is an excellent form of treatment for fractures of the femoral shaft, and has several advantages over other forms of traction.

Forty cases of congenital pseudarthrosis of the tibia were reviewed. The results were assessed so as to emphasise function rather than simply the presence or absence of union. At the time of review, 14 patients had undergone amputation; eight others had non-union or tenuous union. No surgical procedure except the Farmer operation (a composite skin and bone pedicle graft from the other leg) showed any clear superiority. Among the factors associated with a poor result were considerable shortening, older children, and rapid resorption of the bone graft. It is felt that congenital pseudarthrosis of the tibia is a biological problem and not merely a mechanical one; consequently biological approaches to its treatment are needed.

The diagnosis of acute osteomyelitis is often very difficult during the first 24 to 48 hours. Bone scanning has been a useful adjunct in this diagnosis by demonstrating increased uptake in the area or areas of involvement. Occasionally the pathological area is "cold" on scanning, which may lead to a misdiagnosis. This paper presents three cases demonstrating this unusual finding.

A prospective survey was carried out on all cases of irritable hip presenting at the Royal Liverpool Children's Hospital over a period of one year. All children had a radioisotope scan of the hips and were then followed for one year by serial radiography. Five of the 50 children seen during the one year had areas of ischaemia in the capital femoral epiphysis demonstrated on the scan. all five developed radiological signs of Perthes' disease within sic months. The remaining 45 had radiographically normal hips at one year.

Exposure of the prosthesis is one of the problems encountered after arthroplasty of the knee. Eight patients with nine exposed prostheses have been treated by using a gastrocnemius myocutaneous flap to provide cover. This preserved the prosthesis and closed the joint in six of the eight patients.l The factors leading to breakdown of the wound are discussed and the anatomy of the gastrocnemius myocutaneous flap and the operative procedure are described.

Seven children underwent partial meniscectomy for symptomatic discoid lateral meniscus. This procedure, modifying the discoid meniscus to the normal semilunar shape, was indicated only when degeneration or tear was minimal, when the meniscus was not abnormally thickened nor of Wrisberg type, when it was not hypermobile, when the capsular attachment was intact, and when the residual meniscus was free from abnormality. The results were excellent clinically, radiologically and arthroscopically, rehabilitation was shortened to half that required for total meniscectomy and the residual meniscus functioned entirely normally.

Measurements of tibial torsion using a tropometer were made in more than 1200 consecutive patients attending an adult knee clinic. In total 1672 readings from 836 patients in 11 diagnostic categories were analysed. Patients with either patellofemoral instability or Osgood-Schlatter disease had a significant increase in lateral tibial torsion. The most important finding was a significant reduction in this torsion in patients with panarticular disease.

Lateral instability of the patella was found after recurrent, habitual and permanent dislocations. Contracture of soft tissues lateral to the patella only occurred with habitual and permanent dislocations, but medial laxity was present in all cases. After adequate release of the lateral contracture, the medial stability was improved by transposition of the lower three-quarters of the pes anserinus to the medial border of the patella, and the patellar ligament. This created a relatively unstretchable physiological sling which ensured dynamic stability of the patella. Six recurrent, 21 habitual and nine permanent dislocations of the patella were treated by this method. Results were excellent in 21 patients, good in 13 and fair in two. The follow-up period varied from 21 to 84 months. There have been no recurrences to date.

The clinical results in a series of 131 patients with 134 brachial plexus injuries were analysed to determine the factors affecting prognosis. Isolated injuries to the upper trunk had the best prognosis, but the prognoses of isolated injuries to the cords, upper roots and lower trunk were not as good. Complete injuries of the plexus had the worst prognosis. Pain which persisted for more than six months was a bad prognostic sign for neurological recovery regardless of the location of the lesion. Horner's syndrome was not always accompanied by a bad prognosis. Operation did not affect the prognosis except in open lacerations. A pseudomeningocele detected by myelography usually precluded recovery in the root at the level of the pseudomeningocele.

Effective concentrations of antibiotic in the fluid bathing implanted hip prostheses are essential to prevent infection by micro-organisms. Twenty patients undergoing total hip replacement were given one gram of Cephradine intramuscularly one hour before operation and one other received a single bolus of Cephradine intravenously before operation and one other received a single bolus of Cephradine intravenously before operation. The concentrations of antibiotic were greater and persisted longer in the tissue fluid than in the blood. The antibiotic was sufficient to inhibit most micro-organisms causing contamination. We recommend that Cephradine is given intramuscularly one hour before operation and at six-hourly intervals after operation until the drainage tubes and intravenous lines have been removed.

A histochemical analysis was made of 103 muscle biopsies taken from 62 patients with idiopathic club feet. Any reduction in the diameter of the muscle fibres associated with wasting of the calf muscle was recorded. Histochemical abnormalities existing in these biopsies were revealed by comparison with normal biopsies obtained from the normal legs of 13 children with unilateral deformities. No significant difference was found between the diameter of the muscle fibres taken from normal and affected legs aged under six months. This indicates that wasting of the calf muscle is due to a reduction in the number of fibres rather than their size. The muscle structure was normal excluding denervation and reinnervation. The soleus muscle in patients aged under six months contained 61 per cent Type 1 fibres in the affected legs, compared to 44.3 per cent in normal legs. Similar values were found in the normal and abnormal tibialis posterior muscles, long flexors of the toe and peroneal muscles. The change in composition of the soleus muscle and the reduction in the number of fibres may be caused by a defective neural influence on the development of the limb in club foot.

Two cases of coccydynia are presented. Their definitive treatment was excision of the coccyx and the pericoccygeal tissues. The histology in both cases revealed a glomus tumour of the coccygeal body and the symptoms were completely relieved after operation. Glomus tumours of the coccygeal body may be the cause of some cases of coccydynia.

An experimental study is reported of fracture healing in the femora of 36 Beagle dogs, comparing the results of using stainless steel plates with those of using less rigid titanium alloy plates. The alloy plates led to the appearance of a small amount of periosteal callus without any histological evidence of fracture instability, thus allowing the radiological assessment of fracture union. This also produced less bone loss during the remodelling phase. Radiological measurements 24 weeks after osteotomy showed cortical thickness to be reduced by six per cent under titanium alloy and by 19 per cent under stainless steel, while histological measurements showed a total bone loss of 3.7 per cent under titanium alloy and of 11 per cent under stainless steel plates. Removal of the titanium alloy plates after eight weeks followed by a recovery period of 16 weeks produced an increase of cortical thickness of 69 per cent and a gain in total bone mass of 30 per cent. Titanium alloy plates also produced less soft-tissue reaction than stainless steel plates. It is concluded that this alloy is a promising material for internal fixation devices.

Some of the component metals of the alloys used for total joint prostheses are toxic and dissolve in the body fluids. It is important to establish how toxic these metals are and to assess the risk of localised tissue necrosis around the prostheses. This has been investigated by incubating primary monolayer cultures of human synovial fibroblasts with various preparations of metals for periods up to 18 days. Morphological changes were evident after exposure to cobalt chloride at a concentration of 50 nanomoles per millilitre and to nickel chloride at 200 nanomoles per millilitre. Chromic chloride, ammonium molybdate and ferric chloride produced no changes up to 500 nanomoles per millilitre. Cultures exposed to particulate pure metals were poisoned by cobalt and vanadium but were not affected under the same conditions by nickel, chromium, molybdenum, titanium or aluminium. Particulate cobalt and vanadium were probably toxic due to their relatively high solubility (four and one micromoles per millilitre respectively after seven days incubation). Particulate nickel also dissolved (three nanomoles per millilitre after seven days) but not in sufficient quantities to be toxic. It appears, therefore, that potentially the most harmful components are cobalt from cobalt-chromium alloy, nickel from stainless steel, and vanadium from titanium alloy. As far as can be estimated, the only combination of materials which is likely to give rise to toxic levels of metal under clinical conditions, is cobalt-chromium alloy articulating against itself to produce relatively high levels of cobalt.

It has been shown in experimental animals that the living cells in a bone autograft can make an important contribution to osteogenesis. However, some common clinical techniques, such as the topical use of antibiotic powders on grafts or on the graft bed, are likely to damage or kill the cells. In this experimental study in rats, bone isografts dusted with chloramphenicol or methicillin powder or with Polybactrin spray before subcutaneous implantation produced little or no new bone over a period of two weeks whereas untreated, control grafts showed abundant osteogenesis, as did grafts pretreated with solutions of antibiotics. The effect of short-term storage of the grafts for 3 to 24 hours in air, saline or culture medium before implantation was also examined. Grafts stored in culture medium generally did as well as, or better than, fresh control grafts whereas immersion in saline inhibited osteogenesis. The importance of these results for clinical bone grafting is discussed.