Callus formation and the rate of union of nailed fractures of the femur has been determined in 22 patients with associated head injuries and compared with that in a group of patients with similarly treated fractures but without head injuries. The comparison confirms the widely held view that, in patients with head injuries, fractures frequently heal with excessive callus and at a faster rate than normal.

Using a simple method of quantifying fracture healing, 53 patients who had limb fractures and also severe head injuries were studied; they were compared with 30 patients who had limb fractures but no head injury. Those with head injuries had a greater healing response and united more rapidly. Radiological and histological analysis revealed that the terms "myositis ossificans" and "heterotopic bone" may be more appropriate than "fracture callus" to describe the healing response in these patients.

Ischaemia resulting from increased joint pressure may play a role in the pathogenesis of necrosis of the femoral head epiphysis. We studied the effect of temporary vascular occlusion on this epiphysis in young rabbits. Occlusion for six hours resulted in necrosis of trabecular bone and of intertrabecular marrow and vascular tissue, later followed by revascularisation and repair, as has been demonstrated previously. In contrast, raised intra-articular pressure lasting for only two hours resulted in a more complex picture: trabecular osteocytes were dead, whereas the bone-forming marrow was shown by fluorochrome labelling to remain viable, and to form appositional repair bone throughout the epiphysis. We concluded that transient vascular occlusion may cause the death of trabeculae despite intact perfusion of the bone. This type of change may be important in the pathogenesis of Perthes' disease.

The pressure distribution between the cartilaginous surfaces in the human hip joint was measured using pressure-sensitive film. Five cadaveric hip joints (aged between 58 and 87 years) were measured at three positions and loads, representing three instants in the stance phase of the walking cycle. The pressure distribution was not uniform, indicating that the cartilage did not, to any great extent, distribute the applied load. The maximum pressures recorded were about 10 MN/m2. The anterosuperior surface of the cartilage was identified as an area of high pressure.

We describe a surgical approach to the upper thoracic spine which allows an adequate exposure of the vertebral bodies from T1 to T3. The approach causes little functional disturbance and is especially useful in older patients with spinal tumours causing spinal cord compression.

We present the results of 506 consecutive Howse hip arthroplasties with a minimum follow-up of 10 years. The mortality within one month of surgery was 0.79%. The early dislocation rate was 1.38%, two hips requiring revision. Nine hips developed deep sepsis (1.78%), eight of which required revision. At 10 years 42 hips (8.3%) had required revision, including 14 with aseptic acetabular loosening and 11 with femoral stem fractures. We feel that as judged by the dislocation rate and the need for subsequent revision, the Howse arthroplasty is an acceptable form of total hip replacement, particularly in the older patient and in those requiring total replacement for femoral neck fractures.

We report the clinical and radiographic results of the Chiari pelvic osteotomy in 49 hips (45 patients) at an average of 14 years after operation. Of these hips, over half had minimal or no pain, had good or excellent results as assessed by the Harris hip score, and could walk at least three miles; three-quarters, however, had a positive Trendelenburg sign. A younger age at operation and a painless hip with no radiographic evidence of degeneration before operation were associated with a higher hip score at review. The percentage of hips without degenerative changes fell from 68% before operation to 15% at final review. There were no major complications and it was found that a Chiari osteotomy need not interfere with normal childbirth.

We have reviewed 19 consecutive patients admitted to the Odense University Hospital after traumatic dislocation of the hip. We aimed to perform computerised tomography as soon as possible after closed reduction; this was accomplished in 15 patients. The CT scans revealed intra-articular fragments of bone in five hips, and fractures of the femoral head or acetabulum in six. In two cases the CT scans excluded fractures or intra-articular fragments which had been suspected on conventional radiography. CT scanning is a useful diagnostic tool in traumatic dislocation of the hip; we consider that it makes an important contribution to management.

Mechanical and biomechanical testing of a new bone cement suggests that improved load transfer to the proximal femur could be achieved with the combination of a cement having a lower modulus, a greater ductility and a lower creep resistance than polymethylmethacrylate and a suitably shaped femoral component.

We report eight cases of sacrococcygeal chordoma treated by high sacral resection through S2 by a posterior approach, with the intention of achieving radical removal. The technique we describe is easier than the combined abdominosacral approach, and there have been no serious intra-operative or postoperative complications. The major technical problems were the margins of excision in the sacrum itself (one recurred) and in the perirectal soft tissues (four recurred), and the preservation of sacral nerve roots. When both S2 roots were preserved, sphincter problems were mild and reversible. One patient died from recurrence 32 months after operation and one was lost to follow-up at eight months. Six patients are alive with a median survival of three years; three of them are free of disease after 22, 36 and 80 months respectively. These results indicate the possibility of surgical cure of this malignant tumour.

We report 14 cases of symptomatic ossification of the posterior longitudinal ligament (OPLL) diagnosed in non-oriental men between 1978 and 1985. All 14 patients had incomplete spinal cord syndromes due to OPLL in the cervical spine and had been referred undiagnosed from other institutions. Twelve had severe myelopathy and seven were wheelchair-bound before OPLL was diagnosed, while six patients had had operations elsewhere for their neurological dysfunction. There was a close association between OPLL and diffuse idiopathic skeletal hyperostosis (Forestier's disease) on plain radiographs, seven patients having both disorders. Enhanced CT scans proved to be the best diagnostic method for the localisation of cord compression, and magnetic resonance imaging, used on four recent cases, provided the best visualisation of the extent of involvement in the sagittal plane. We aim to heighten awareness of OPLL in non-orientals, in whom the clinical features, histological characteristics, and radiographic patterns are very similar to those of oriental patients.

Progressive structural scoliosis in growing rabbits has been produced. Tethering the thoracic spine into the form of an asymmetric lordosis produces a slowly progressive structural scoliosis by purely mechanical means. The addition of a contralateral release of the paraspinal muscles leads to a very progressive deformity with early cardiorespiratory failure. This release, however, was performed with an electric soldering iron and subsequent study showed that in those animals with severe progressive deformity there was localised spinal cord damage. We suggest that it is this neural damage and not the muscle release which leads to rapid progression. The clinical implications are important in that neurological dysfunction seems to render the spinal column less able to resist mechanical buckling and may be the crucial factor differentiating severely progressive from more benign curves.

Reports of spondylolysis in vertebrae other than those of the lower lumbar spine are rare. We report 32 patients with upper lumbar spondylolysis who have been studied clinically, radiologically and scintigraphically. Twenty patients had bilateral lesions, and seven of those with unilateral lesions had structural changes or anomalies in the opposite posterior arch. Positive scans were found to be associated with a short clinical history, and indicated stress-related lesions. Our findings suggest that mechanical factors may play a role in the aetiology of spondylolysis in the upper lumbar spine similar to that which they play in the lower lumbar spine, and that local structural anomalies may contribute to abnormal loading of these vertebrae.

An alternative to Syme's amputation for congenital absence of the fibula is described in this paper. Nine children have had the ankle reconstructed using the Gruca technique with a very satisfactory result in eight. This procedure is not suitable for every patient and in most unilateral cases the operation can only be regarded as an interim procedure because of progressive leg-length inequality. The decision to remove the foot may be delayed and it allows childhood to be spent without resort to prostheses. However, the procedure can be considered as the definitive operation in cases of bilateral deformity.

The correction of a relapsed or neglected clubfoot by an external distractor is an alternative to a major operation which may involve triple arthrodesis and is often associated with skin problems. We report the use of the Ilizarov method to treat nine severely deformed feet, with satisfactory results in terms of function and appearance. The distractor enables treatment to be applied before maturity and avoids the shortening of the foot that results from wedge osteotomies. We discuss the indications, technique, complications and results of the method.

After a unicompartmental Oxford knee replacement, a clear lateral radiographic view of the components may be obtained without the shadow of prosthetic components in the other compartment. Radiographs of 20 knees were studied; with the patient supine and the muscles relaxed, views with the knee at full extension and 90 degrees of flexion were obtained and the movement of the meniscal bearings over this range of flexion was measured. The bearings were found to move backwards on the tibia through an average distance of 4.4 mm (range 0.0 to 13.5 mm) in the medial compartment and 6.0 mm (range 1.6 to 13.0 mm) in the lateral compartment. These movements were in the same direction as that observed in cadaver specimens but smaller in magnitude. At 90 degrees of flexion, radiographs were obtained with the tibia twisted manually to the limits of medial and lateral rotation. The average movement of the bearings between these extremes was found to be 6.6 mm in the medial compartment and 5.1 mm in the lateral; their movements on the tibia were in opposite directions in the two compartments. Bearing movement was still present in knees examined five years after operation.

A case of duplication of the patella in the coronal plane is reported. Previously reported cases of double patella have shown sagittal or vertical duplication, and some have been associated with multiple epiphyseal dysplasia. In our case, excision of one patella and realignment of the extensor mechanism relieved symptoms of giving-way.

Resection arthroplasty of the patella has been found to be a satisfactory procedure for the treatment of patellofemoral pain caused by osteoarthritis. In the present series 60% of the operated cases were pain-free on a 31-month average follow-up. The patients found it easier to climb stairs and to kneel and in most cases the radiographic joint space was good.

We have developed an apparatus to measure the anteroposterior stability of the knee to forces of up to 250 N, applied at 20 degrees of flexion. We measured anterior laxity at 200 N, anterior stiffness at 50 N and total laxity at +/- 200 N. A study of cadaveric knees revealed that the soft tissues surrounding the bones had a significant influence on the force-displacement curve, and emphasised that differences between injured and normal pairs of knees are much more important than the absolute values of the parameters. In 61 normal volunteers we found no significant left to right differences in anterior laxity at 200 N and anterior stiffness at 50 N. In 92 patients with unilateral anterior cruciate deficiency there were significant differences (p less than 0.0005) in anterior laxity, anterior stiffness and total laxity, the injured-normal differences averaging 6.7 mm, 1.3 N/mm, and 8.1 mm respectively.

Fifty-six patients with displaced malleolar fractures had open reduction and fixation of the fracture fragments using, by random selection, either biodegradable implants or metal AO plates and screws. The cylindrical biodegradable implants were made of polylactide-glycolide copolymer (polyglactin 910). The complications, radiographic results and functional recovery were studied prospectively. After follow-up of at least one year, no significant differences emerged in the complication rate or in the results of treatment between the two methods of fixation. Because of the advantage of avoiding the need to remove metal fixation after union, we now use biodegradable internal fixation routinely to treat displaced malleolar fractures.

We report the results of simple laboratory experiments which showed that bleeding pressures known to occur at the bone surface during total hip arthroplasty may compromise the integrity of the bone-cement interface and the cement itself. Such undesirable effects can be prevented by maintaining adequate pressure on the cement until its increased viscosity can resist displacement caused by the bleeding pressure.

Twenty-four cases of complete division of median or ulnar nerves were assessed on two occasions after direct suture, with an interval of three years between assessments. Clinical, electrophysiological and timed functional tests were used. All the operations had been performed by one surgeon, using the operating microscope for approximately half the cases but not for the other half. The results were analysed, and the patient's age, any delay between injury and suture, and the duration of follow-up were all found to exert strong and consistent effects on the scores obtained. After controlling for these factors, there was no consistent difference between the results of the two surgical methods. It is concluded that, at least in the hands of one particular surgeon, the use of the operating microscope gives no better results than careful epineural suture performed without it.

The results of a prospective multicentre study of the Herbert differential pitch bone screw used to treat 50 scaphoid fractures and non-unions are presented. All fresh fractures and four of the five fracture-dislocations united, an overall union rate of 92%. Although the technique is demanding, the Herbert screw can achieve excellent results in the management of scaphoid fractures.

A prospective study was made over a three-year period of 900 consecutive unilateral Colles' fractures. The radiographic features at the time of fracture, after reduction and one week later were measured and correlated with grip strength and range of movement at three years. The most significant radiographic feature to influence the outcome was the presence of shortening of the radius one week after reduction of the fracture. Persistent dorsal tilt, radiocarpal joint involvement and ulnar styloid fracture were each associated with reduced range of movement, but had no effect on grip strength. Extension of the fracture into the distal radio-ulnar joint was associated with reduced grip strength but had no effect on range of movement. Radial tilt of the radial fragment did not correlate with any aspect of the result after three years.

Nine children with chronic post-traumatic dislocation of the head of the radius were treated by an osteotomy of the ulna with over-correction of the angular deformity and with elongation of the bone. Satisfactory results were obtained in eight cases, the only poor outcome following a three-year delay between the initial injury and the reposition. The interosseous membrane of the forearm appeared to be the most important structure in maintaining the corrected position of the radial head.

A new technique for the treatment of displaced fractures of the proximal humerus is described. Twelve fractures in 11 patients were managed by transcutaneous reduction using a Steinmann pin, and external fixation with a Hoffmann-type neutralising bar connected to two half-pins in the humeral head and three half-pins in the shaft. The pins were removed after four weeks. Two patients sustained redisplacement after a further injury, but in the others reduction was maintained. Two cases of pin-track infection resolved after antibiotics, but delayed union resulted. There were no neurovascular injuries and at follow-up of 6 to 12 months no refractures had been seen. The early functional results were excellent or satisfactory in nine cases.

A new method of replacement for the paralysed anterior deltoid is described. The latissimus dorsi with its neurovascular pedicle is freed and rotated, and then placed over the anterior part of the paralysed muscle. The lever arm of the transposed muscle is as long as that of the deltoid, and the muscle volume is enough to restore the natural contour of the shoulder. We report operations on 10 patients with shoulder palsy, eight caused by brachial plexus injury and two by resection of a neurilemmoma of the plexus. In six cases, active flexion to over 90 degrees was achieved. At least one of the rotator cuff muscles or the long head of biceps should have some active function if good results are to be obtained.

Between 1969 and 1985 26 patients with destructive lesions of the distal humerus were treated by endoprosthetic replacement; each implant was custom-made and incorporated part of the distal humerus or the entire bone as well as a hinged total elbow replacement. Recurrence occurred in three of the patients with tumours, and three prostheses were removed because of deep infection in patients with previously compound injuries of the elbow. Another three loosened without infection, but none needed revision or removal and no amputations resulted. Other complications included nerve palsies, but the only deaths were from metastases. A useful range of elbow movement, with a stable arm and good hand function, was achieved in every patient.

Endoprosthetic replacement of the proximal humerus has been performed in our unit on 25 occasions between 1950 and 1982. The indication for surgery was destruction of the proximal half of the humerus so extensive that the only alternatives were reconstruction or amputation. Of the patients with tumours two died from metastases, and three from unrelated causes; local recurrence necessitated amputation in two patients. Minor complications were frequent, but there were no deep infections and, after 1964, no prosthesis became loose. Active shoulder movement after operation was considerably limited, but passive movement was good and function of the elbow and hand were preserved.

We report the case of a carrier of the hepatitis B virus who required arthroscopy of the knee. The irrigation fluid was shown to contain the virus. In view of the highly infective nature of this virus, appropriate precautions are necessary when carrying out arthroscopy in such patients.

The parameters of cellular proliferation and growth in the growth plates of immature rats were measured after unilateral tibial osteotomy and used to calculate growth rates. Distal osteotomy of one tibia was followed by a bilateral increase in the calculated growth rate of the distal growth plates. However, the ipsilateral distal growth plate grew faster than the contralateral between 12 and 18 days after operation, which appeared to be related to increased cell proliferation and height. Proximal osteotomy led to an increase in growth rates proximally which was more marked on the contralateral side. The lesser response of the ipsilateral growth plate may have been due to local impairment of blood supply, or to greater local release of metabolites after bony damage. Distal tibial osteotomy gave similar results to circumferential release of the distal tibial periosteum. Proximal osteotomy, however, produced a relative impairment of growth on the operated side. This may be of importance in the correction of childhood deformities associated with inequality of leg length.