Treatment with corticosteroids is a risk factor for non-traumatic avascular necrosis of the femoral head, but the pathological mechanism is poorly understood. Short-term treatment with high doses of methylprednisolone is used in severe neurotrauma and after kidney and heart transplantation. We investigated the effect of such treatment on the pattern of perfusion of the femoral head and of bone in general in the pig. We allocated 15 immature pigs to treatment with high-dose methylprednisolone (20 mg/kg per day intramuscularly for three days, followed by 10 mg/kg intramuscularly for a further 11 days) and 15 to a control group. Perfusion of the systematically subdivided femoral head, proximal femur, acetabulum, humerus, and soft tissues was determined by the microsphere technique. Blood flow in bone was severely reduced in the steroid-treated group. The reduction of flow affected all the segments and the entire epiphysis of the femoral head. No changes in flow were found in non-osseous tissue. Short-term treatment with high-dose methylprednisolone causes reduction of osseous blood flow which may be the pathogenetic factor in the early stage of steroid-induced osteonecrosis

A biomechanical study has been carried out on 20 cadaveric knees to investigate their load-absorbing mechanism. The impact load was applied using a weight falling onto the transected proximal femur and the force transmitted through the knee was measured at the transected distal tibia using a load transducer. The peak force transmitted increased as, sequentially, meniscus, articular cartilage and subchondral bone were damaged or removed. The most striking result was found in an implanted knee replacement where the transmitted force reached 180% of that in the intact knee. The results show that the joint has an impact-absorbing property in each segment and that in the osteoarthritic knee there is less absorption of shock than in the normal knee. The high impact force in an implanted knee suggests that microfractures of the cancellous bone might be expected and may produce loosening

A protocol for the treatment of fractures of the middle third of the femur by the early application of a hip spica has been evaluated in 191 children aged 10 years or less. Children without other injuries spent only a few days in hospital for the application and later removal of the spica. At all ages, anterior angulation of less than 20 degrees and valgus angulation of less than 15 degrees were accepted at the one-week review. Acceptance of shortening varied with the age of the child and the stage of treatment, but was 10% or less of the femoral length at the time of spica removal. At late review leg-length discrepancy was rare and clinically insignificant. This method of treatment was simple and effective. It dramatically reduced the cost of care and freed a number of children's hospital beds

The ultrasonic findings in 38 children with osteomyelitis of the limb bones were analysed in four time-related groups based on the interval between the onset of symptoms and the ultrasonic examination. Deep soft-tissue swelling was the earliest sign of acute osteomyelitis; in the next stage there was periosteal elevation and a thin layer of subperiosteal fluid, and in some cases this progressed to form a subperiosteal abscess. The later stages were characterised by cortical erosion, which was commonly present in those who had had symptoms for more than a week. Concurrent septic arthritis was revealed in 11 patients, most frequently in association with osteomyelitis of the proximal femur or the distal humerus. Four weeks after clinical cure, ultrasonic examination showed no abnormalities. Ultrasonography is therefore a useful additional method for the diagnosis and assessment of osteomyelitis and its complications

1. Because of socio-medical deficiencies, osteitis in some parts of the world still conforms to the classical pattern seen before the introduction of antibiotics. 2. One of many complications is loss of continuity from widespread destruction of tubular bone. 3. Twelve patients with this complication are described. The most satisfactory treatment, when practicable, is the transference of an adjoining normal bone into the remnants of the defective one. 4. Two neonates each with a massive defect of the femur are described. This complication of osteitis at this age has not been reported before. 5. The long-term prognosis of lower limb defects is poor when there is failure of bone growth. Nevertheless, reconstructive procedures are still worth attempting because later amputation, if necessary, can be conservative, and prosthetic difficulties may thus be eased

1. In tuberculous disease of the hip, premature epiphysial fusion at the knee joint is due to rupture of the epiphysial cartilaginous plates consequent upon resorption of cancellous support and suppression of osteogenesis. 2. In the tibia, premature fusion is usually preceded by near-central "bulging" of the metaphysial and tibial marrow through the epiphysial plate. In the femur, epiphysial changes preceding fusion are of a fragmentary type. 3. Injury, in quiescent disease, plays little or no part in the causation of premature epiphysial fusion. 4. The factors which are responsible for these changes—local toxaemia and prolonged immobilisation—must exist for not less than two years. 5. In cases which are treated conservatively for long periods the incidence of premature fusion, with serious shortening of the limb, is so high that the wisdom of such treatment must be reconsidered

We performed isokinetic knee testing to assess thigh muscle function in ten patients (12 legs) before and after mid-shaft femoral shortening averaging 46 mm (27 to 70). Tests were at angular velocities of 60 degrees/sec and 180 degrees/sec, and were performed preoperatively and after 3, 6, 12 and 24 months. Isokinetic tests at two years showed a significant reduction in muscle function in both quadriceps and hamstrings, but recovery of function was significantly better for the hamstrings. There was a linear relationship with correlation of r2 = 0.31 to 0.86 between loss of muscle force at two years and the magnitude of shortening. Long-term loss of muscle force should be expected after a mid-shaft shortening of the femur of more than 10%

We performed Kawamura's dome osteotomy of the pelvis, with simultaneous distal transfer of the greater trochanter on 101 hips in 91 patients with osteoarthritis secondary to hip dysplasia. The mean age at operation was 30 years (15 to 55), and follow-up was for a mean of 8.3 years (5 to 14). Clinical evaluation using the Merle d'Aubigne score showed 92% excellent or good results. Radiologically, 91 hips had good acetabular remodelling and showed no signs of progression of osteoarthritis. In ten hips the osteoarthritic process progressed despite the osteotomy and six of these eventually underwent total hip replacement. Factors which were significantly associated with a poor outcome included an advanced stage of osteoarthritis, valgus deformity of the proximal femur, old age at the time of operation and postoperative persistence of abductor insufficiency

We performed limb lengthening and correction of deformity of nine long bones of the lower limb in six children (mean age, 14.7 years) with osteogenesis imperfecta (OI). All had femoral lengthening and three also had ipsilateral tibial lengthening. Angular deformities were corrected simultaneously. Five limb segments were treated using a monolateral external fixator and four with the Ilizarov frame. In three children, lengthening was done over previously inserted femoral intramedullary rods. The mean lengthening achieved was 6.26 cm (mean healing index, 33.25 days/cm). Significant complications included one deep infection, one fracture of the femur and one anterior angulation deformity of the tibia. The abnormal bone of OI tolerated the external fixators throughout the period of lengthening without any episodes of migration of wires or pins through the soft bone. The regenerate bone formed within the time which is normally expected in limb-lengthening procedures performed for other conditions. We conclude that despite the abnormal bone characteristics, distraction osteogenesis to correct limb-length discrepancy and angular deformity can be performed safely in children with OI

We used the stainless steel cable grip system described by Dall and Miles in 1983 to fix trochanters in 40 hips after total arthroplasty with trochanteric osteotomy. The cable broke in 32.5% of the hips; the trochanter failed to unite in 37.5%. Significantly more cables broke when placed inside the femoral canal than when the cable was placed round the femoral shaft (58% as against 9.5%, difference p less than 0.01). The high incidence of breakage may have resulted from contact between the stainless steel cable and the titanium prosthesis, from the acute angulation, or because of the lower fatigue strength of stainless steel. Better results have been obtained using cables with a higher fatigue strength, passed outside the proximal femur

Fractures of the femoral shaft are generally considered to affect young patients, but we have reviewed 24 cases in patients over 60 years who have been treated by locked nailing, usually by closed methods. Most were women with low-velocity injuries, but despite this, 14 fractures were significantly comminuted. The complication rate was 54% with a peri-operative mortality of 17%. Most complications were the general ones of operating on elderly patients. Specific complications included: fractures below an abnormal hip, proximal fracture related to the nail and poor purchase in the distal femur. In all survivors, the femoral shaft fractures united satisfactorily, and the fixation allowed early mobilisation. The locking nail appears to be an effective method of managing femoral shaft fractures in the elderly patient

Immobilisation causes denervation-like changes in the motor endplates, decreases the content of IGF-I, and increases the number of IGF-I receptors in the spinal cord. In the rat we investigated whether similar changes occur after a fracture of the midshaft of the femur which had been treated by intramedullary fixation with adequate or undersized pins. A more pronounced reduction in muscle wet weight was seen after fixation by undersized pins as well as decreased ash density of the ipsilateral tibia which did not completely return to normal within the 12-week experimental period. The nicotinic cholinergic receptors in the motor endplates of tibialis anterior were increased (p < 0.01) and there was a significant increase (p < 0.02) in IGF-I receptors in the lumbar spinal cord ipsilateral to the fracture after treatment by undersized nails. These changes may be associated with the impaired proprioception, co-ordination and motor activity which are sometimes seen after fractures

The pathogenesis of Perthes' disease has been related to increased intra-articular pressure secondary to a joint effusion. The pressure within the hip in different positions was measured in eight children with transient synovitis and four with the synovial stage of Perthes' disease. In the position of comfort for the hip this pressure was always less than the arteriolar blood pressure and in a supine position it did not exceed the systolic blood pressure. However, in extension with medial rotation the intra-articular pressure always became several times the systolic blood pressure. This high pressure was also recorded in the stable lateral position which occurs normally during sleep. It is concluded that in the presence of a synovial effusion in the hip, a position of extension and medial rotation causes an increase in intra-articular pressure which may compromise the blood supply to the capital epiphysis of the femur

Three cases are reported in which an osteosarcoma developed in relation to an enchondroma in a long bone. Two of the cases were in the proximal femur whilst one occurred in the proximal humerus, both recognised sites for old calcified enchondromas or "cartilage rests". The ages of the patients at presentation were 55, 63 and 84 years and all were women. Two patients died with pulmonary metastases within six months of the onset of clinical symptoms. Despite their intimate relationship to the enchondromas, none of the osteosarcomas could be shown histologically to have arisen from tumour cartilage. It appears probable that these are cases in which independently arising tumours have merged to form a so-called "collision" tumour, but the possibility that they could have been derived by dedifferentiation of a previously benign neoplasm cannot be discounted

Of 135 consecutive patients admitted with subtrochanteric fractures of the femur, 104 were studied; half had internal fixation with a Zickel nail and half had a nail-plate device. Fractures treated with a Zickel nail had significantly less blood loss during operation and took less time to walk with full weight-bearing, but the incidence of technical error at operation was higher. Errors included malalignment of the cross-pin, penetration of the femoral cortex and comminution of the greater trochanter. There was mechanical failure within one year of surgery in 17% of the nail-plate series but no implant failures in the Zickel nail group within the same period. The total time spent in hospital was similar in both groups. The Zickel nail provides better fixation for subtrochanteric fractures than a simple nail-plate but, because of technical difficulty, its use should be reserved for surgeons of reasonable experience

Disruption of the major ligaments of the knee was seen in six young men, five parachutists and a house painter, after what we have termed abduction-traction injury. This unusual complaint results from the application of a sudden block to the ankle while falling head first, leading to traction and abduction of the knee. All the patients underwent operations, generally with unsatisfactory results. At operation tears of the anterior cruciate ligament, medial collateral ligament and posterior oblique ligament were seen in each case; in four patients the posterior capsule and in three the posterior cruciate ligament also were torn. In one patient the lateral collateral ligament was torn and the lateral meniscotibial ligament was avulsed. The compression component is absent in this type of injury and consequently the menisci and the osteochondral surfaces of the tibia and femur remained intact in each case

A 14-year-old girl with a congenitally deformed and shortened right leg and foot is described. The patient could not bear weight on the deformed limb and had to hop on the left leg. The deformed foot faced backwards and had nine toes. The right leg was shorter than the left by 26 centimetres. Radiologically, the lower end of the right femur was ill-developed and there was no knee joint. There were two fibulae and the tibia and the patella were absent. A through-knee disarticulation was done and a prosthesis fitted later. The amputated leg and foot were dissected. Many of the muscles in the leg and foot were duplicated. There were two calcanei, one talus, one navicular, two cuboids and four cuneiforms. Ther were nine metatarsals, and all the toes had three phalanges except for one which had two

The off-loading characteristics of the cast-braces of 30 patients with fractures of the shaft of the femur have been investigated, during axial loading, using strain-gauge transducers. These were applied at the level of the fracture, where the cast was circumferentially split, and to the hinges of the brace at the knee. They measured the load transferred between the two portions of the thigh cast, and between the thigh cast as a whole and the below-knee cast; by subtraction from the total load on the limb, the skeletal force at the fracture level and at the knee could be calculated. In all patients there was an increase in the fracture load as union progressed which was thought to be due to physiological feedback mechanism from the fracture site. The load carried by the two portions of the thigh cast and by the thigh cast as a whole was proportionately high at first and stabilised at an average of 35 per cent of body weight

Six cases are reported in which a fibrosarcoma or malignant fibrous histiocytoma developed in relation to an enchondroma in a long bone. Four of the tumours were fibrosarcomata, and two were malignant fibrous histiocytomata. Five of the six cases were in the distal femur, which is a common site for old calcified enchondromata or "cartilage rests". The age of the patients was between fifty-six and eighty-six with a mean of seventy. Four were women, Five died less than one year after presentation. The fibrosarcomata and malignant fibrous histiocytomata do not appear to have arisen directly from the tumour cartilage but from the dense fibrous tissue surrounding necrotic areas in the enchondromata by a process analogous to that responsible for the development of fibrosarcomata in bone infarcts and chronic osteomyelitis. The possibility that some "dedifferentiated" chondrosarcomata are forms of collision tumour is discussed

Ninety-eight fractures of the shaft of the femur were seen in one unit over the two years 1974 and 1975, and the results have been assessed in sixty-nine. Of these, thirty-eight were treated by skeletal traction in a Thomas's splint followed by skin traction, and thirty-one by skeletal traction followed by a cast-brace. The technique of application is described in some detail. The average time for application of the cast-brace was six weeks after the injury, the time in hospital eight weeks and the time till removal fifteen weeks. The patients selected for a cast-brace were in hospital for just over half the time of the others and their fractures on average united more quickly, though with some trouble from angulation of fractures of the uppermost third of the shaft. It is concluded that when used with all the judgment and skill it demands, the cast-brace method is a great advance in conservative treatment