One method of reconstruction in limb salvage surgery for bone tumours is wide resection, extracorporeal devitalisation of the excised segment by autoclaving, and reimplantation of the segment. We have studied the changes in temperature in the medullary cavity, the head, the medial condyle and lateral condyle of calf femora during autoclaving at 134 degrees C in two different autoclaves. There were impressive differences of temperature at different sites. The most unfavourable position was the lateral condyle, which consists mainly of cancellous bone: a short programme of 11 minutes produced a lowest temperature in the series of only 45 degrees C, which may not be sufficient to kill all tumour cells

We studied the effect of non-steroidal anti-inflammatory drugs on the fixation of hydroxyapatite-coated implants. Cylindrical plugs of pure titanium, coated with hydroxyapatite (HA), were inserted into both femora of 10 adult rabbits, 5 of which received 7 daily doses of 30 mg diclofenac. Three weeks after implantation the interface strengths were measured by the pull-out test. The mean peak force for the diclofenac-treated group was 290 +/- 57 N compared with 369 +/- 37 N for the control group (p < 0.025). We conclude that the inhibitory effect of diclofenac on bone repair is not neutralised by HA-coating of an implant

This paper describes the design, development and early surgical experience with a stereotactic device to allow closed retrieval and interchange of intramedullary rods in children with osteogenesis imperfecta. This relatively atraumatic procedure may allow more frequent rod interchange than with other techniques, lessening the likelihood of deformity and fracture in the unsupported skeleton when the bone has outgrown the intramedullary rod. The procedure was developed by design studies in vitro followed by intramedullary rodding of tibiae of New Zealand white rabbits. It has been used in children 12 times, in six tibiae and six femora: 11 rods have been successfully retrieved, with rod interchange in eight of these cases

Hinged casts and roller traction were used in two developing countries to treat fractured femora, most of which were due to road traffic accidents or civil violence. This method of treatment, developed by Neufeld, is particularly useful in the Third World because it uses local materials, adapted in a hospital workshop, and circumvents the difficulties and complications of standard traction and of operative treatment. The results are reported from 11 patients treated in Uganda in 1979 and from 110 treated in the Dominican Republic in 1981 and 1982. All but one fracture united without complication or significant shortening after a brief period in hospital. The method was easily taught to hospital staff and is strongly recommended

A patient with typical congenital contractural arachnodactyly followed up from the age of 12 years to the age of 48 is reported. He had spiderlike fingers and toes and marked contractures of the knees, ankles, toes, shoulders, elbows and fingers; the mobility of the hips and wrists was almost normal. Persistent knee contractures prevented him from walking. In his twenties he had an osteotomy of both femora and shortening of the patellar tendons which enabled him to walk for the first time in an upright position without external support. When seen at the age of 48 the range of movement of his knees was 0 to 90 degrees. He was working as a turner and had been doing so for almost 20 years

The early diagnosis of caisson disease of bone is hindered by the long delay which must elapse before an abnormality becomes apparent on a radiograph. The possible use of bone scintigraphy for this purpose was investigated. Necrosis of the bone and marrow was produced in rabbits by glass microspheres to simulate persistent gas-bubble emboli and then serial radiographs and scintigrams using 99mTc-diphosphonate were obtained. Regions of necrosis could be detected as "hot-spots" on the scintigrams as early as three weeks after the causative insult, which was many weeks before any abnormality could be detected on the radiographs. Histological examination of excised femora suggested that the scintigraphic abnormality might depend on the new bone formation during a reactive or repair process. It is suggested that scintigraphy may have clinical value in caisson disease

A computerised image analyser has been used experimentally to determine its possible usefulness in quantifying bone density. Rats were prepared for this purpose and ash weight/volume readings were obtained on femora which had been radiographed and studied to estimate radiographic density by means of the image analyser. The findings indicated that rats can be prepared by administering oestradiol or by allowing an additional week's growth, both of which give a statistically significant increase of bone density. The computerised image analyser was able to detect these differences but the correlations, although real and linear, between ash weight/volume and radiographic density were not large. Further refinements in techniques will be needed before the system is applied clinically

Dual-energy X-ray absorptiometry (DEXA) is increasingly used to measure changes in bone mineral density (BMD) around femoral prostheses after total hip arthroplasty. We have studied the factors which affect the accuracy of these measurements. The coefficient of variation was < 2% using a hydroxyapatite phantom, 2.7% in an anthropomorphic phantom specimen, and < 1% in repeated measurements on implanted cadaver femora. The precision did not vary with different implant materials or designs. In patients we found a mean precision error of 2.7% to 3.4%. The most significant factor affecting reproducibility was rotation of the femur. We conclude that DEXA is a precise method of measurement for small changes in BMD around femoral implants, but that correct and careful positioning of patients is essential to obtain reliable results

Aims

The purpose of this study was to evaluate the biological fixation of a 3D printed porous implant, with and without different hydroxyapatite (HA) coatings, in a canine model.

The rigidity of a sliding compression screw and three cannulated lag screws in the treatment of subcapital fractures was compared in five pairs of female cadaver femora. There were no significant differences between the compressive strength, bone density, cortical thickness or Singh index of the bones in each pair. A subcapital fracture was standardised using a perpendicular saw cut across the femoral neck. A uniaxial 'load test system' with force and length measurement facilities was used to mimic cyclical stressing applied in vivo at a frequency of 0.5 Hz from 0 to 3 times body-weight. There was no significant difference between the fixation afforded by the sliding compression screw and three lag screws. Bone quality was the single most important factor in the stability of the bone implant unit

Twenty-six children conservatively treated for fracture of the femoral shaft have been reviewed with regard to differences in limb length seven to ten years after the injury. In nine patients the clinical measurements were checked against radiographic measurements of both femora and tibiae. The following conclusions were reached. Nearly two-thirds of the patients had overgrowth of the femur of 10 millimetres or more. Shortening of 15 to 20 millimetres at the fracture site was well compensated for by accelerated growth. Growth acceleration seemed to take place during the healing period and the difference at the end of healing was permanent. Overgrowth was promoted by comminuted and long oblique fractures and by overriding of the fracture ends, but was not influenced by the age at fracture, the duration of treatment or the level of fracture of the shaft. Growth of the tibia was not affected by the femoral fracture

To investigate the origin of fractures at the distal locking site of the Gamma nail, we loaded ten paired human cadaver femora fixed with a Gamma nail in torsion until they fractured. When an awl was hammered in to start the hole for distal locking a fissure appeared in the lateral cortex of all the femora, and the mean torsional load to create a fracture was reduced by 57.8% compared with that in a control group in which the distal locking hole had been started with a centre drill. When an additional drill hole was made, the mean failure load in torsion decreased by 35.7%. We strongly recommend that an awl should not be used at the distal locking site of the Gamma nail; we recommend the use of a centre drill. Additional drill holes should be avoided because they act as stress raisers

Total hip replacement was performed in 27 hips of patients who had sickle cell anaemia with avascular necrosis of the femoral head. The disease was bilateral in 11 patients. Considerable medical problems were encountered although most of the patients had exchange transfusion before surgery (86%), which prevented postoperative sickle cell crises in all but two cases. At the primary operation hard sclerotic bone was seen in nine femora with complete obliteration of the femoral canal. There were four femoral fractures, three following perforation of the shaft due to this hard bone. There was a very high morbidity due to loosening in both cemented and uncemented prostheses. With a rate of 59% over a cumulative 5.5 year period, revision was being performed at an average of only 43 months. Surgeons should be aware of these problems

We have compared the interface morphology at the stem-cement interface of standard Charnley stems with a satin finish (Ra = 0.75 μm) with identical stems which had been grit-blasted over their proximal third (Ra = 5.3 μm) to promote a proximal bond. The stems were cemented into cadaver femora using conventional contemporary cementing techniques. After transverse sectioning, we determined the percentage of the perimeter of the stem which had a gap at the interface. There were substantial gaps (mean 31.4 ± 17.1%) at the stem-cement interface in the grit-blasted region. This fraction was significantly (paired t-test, p = 0.0054) higher than that found around the contralateral satin-finished stems (mean 7.7 ± 11.7%). Although studies of isolated metal-cement interfaces have shown that the bond strength can increase with surface roughness it cannot be assumed that this effect will be observed under clinical conditions

An innovative Kirschner (K-) wire point was developed and compared in fresh pig femora in terms of drilling efficiency and temperature elevation with the trochar and diamond points currently used in clinical practice. The tips of thermal couples were machined to the defined geometry and the temperature measured during drilling. Using the same drill speed (rev/min) and feed rate, the new K-wire point produced the lowest thrust force and torque as measured by a Kistler dynamometer. Drill point temperatures were highest with the trochar geometry (129 ± 6°C), followed by the diamond (98 ± 7°C). The lowest temperatures were recorded with the Medin K-wire (66 ± 2°C). On repeated drilling it could be used for up to 30 holes before reaching the less satisfactory drill performance of the diamond tip. The new K-wire provides a better alternative as it requires less effort for insertion, generates less heat and may be re-used

We have investigated the use of a conically-shaped cement plug made of Polyactive (PA), a biodegradable copolymer. The flexibility and hydrogel properties were thought to facilitate occlusion of the femoral canal even when it was oval or irregular in shape. The function of the plug was first compared with that of the Thackray polyethylene model in 16 artificial plastic femora. The maximum intramedullary pressure achieved during cementing was ten times higher with the biodegradable model. Migration or leakage of cement did not occur when the diameter of the femoral canal was equal to or smaller than the diameter of the plug. We also showed that the biodegradable properties of this implant were such that it did not require removal during revision. The new plug was tested in a pilot clinical trial. At two years only two out of 21 patients had evidence of migration or leakage of cement, probably due to a mismatch in the size of plug and femoral canal. There were no local changes in the femur

The clinical diagnosis of a partial tear of the anterior cruciate ligament (ACL) is still subject to debate. Little is known about the contribution of each ACL bundle during the Lachman test. We investigated this using six fresh-frozen cadaveric lower limbs. Screws were placed in the femora and tibiae as fixed landmarks for digitisation of the bone positions. The femur was secured horizontally in a clamp. A metal hook was screwed to the tibial tubercle and used to apply a load of 150 N directed anteroposteriorly to the tibia to simulate the Lachman test. The knees then received constant axial compression and 3D knee kinematic data were collected by digitising the screw head positions in 30° flexion under each test condition. Measurements of tibial translation and rotation were made, first with the ACL intact, then after sequential cutting of the ACL bundles, and finally after complete division of the ACL. Two-way analysis of variance analysis was performed. During the Lachman test, in all knees and in all test conditions, lateral tibial translation exceeded that on the medial side. With an intact ACL, both anterior and lateral tibial landmarks translated significantly more than those on the medial side (p < 0.001). With sequential division of the ACL bundles, selective cutting of the posterolateral bundle (PLB) did not increase translation of any landmark compared with when the ACL remained intact. Cutting the anteromedial bundle (AMB) resulted in an increased anterior translation of all landmarks. Compared to the intact ACL, when the ACL was fully transected a significant increase in anterior translation of all landmarks occurred (p < 0.001). However, anterior tibial translation was almost identical after AMB or complete ACL division. We found that the AMB confers its most significant contribution to tibial translation during the Lachman test, whereas the PLB has a negligible effect on anterior translation. Section of the PLB had a greater effect on increasing the internal rotation of the tibia than the AMB. However, its contribution of a mean of 2.8° amplitude remains low. The clinical relevance of our investigation suggests that, based on anterior tibial translation only, one cannot distinguish between a full ACL and an isolated AMB tear. Isolated PLB tears cannot be detected solely by the Lachman test, as this bundle probably contributes more resistance to the pivot shift

We compared 54 patients treated by a Medoff sliding plate (MSP) with 60 stabilised by a compression hip screw (CHS) in a prospective, randomised study of the management of intertrochanteric femoral fractures. Four months after the operation femoral shortening was determined from radiographs of both femora. In unstable fractures the mean femoral shortening was 15 mm with the MSP and 11 mm with the CHS (p = 0.03). A subgroup in which shortening was classified as large, comprising one-third of the patients in each group, had a similar extent of shortening, but more medialisation of the femoral shaft occurred in the CHS (26%) than in the MSP (12%) group (p = 0.03). Five postoperative failures of fixation occurred with the CHS and none with the MSP (p = 0.03). The marginally greater femoral shortening seen with the MSP compared with the CHS appeared to be justified by the improved control of impaction of the fracture. Biaxial dynamisation in unstable intertrochanteric fractures is a safe principle of treatment, which minimises the rate of postoperative failure of fixation

Aims

Although good clinical outcomes have been reported for monolithic tapered, fluted, titanium stems (TFTS), early results showed high rates of subsidence. Advances in stem design may mitigate these concerns. This study reports on the use of a current monolithic TFTS for a variety of indications.

Intra-osseous phlebography and the measurement of intramedullary pressure (IMP) have been used clinically and in experimental animals as qualitative methods of measuring blood flow in the bone. The normal phlebographic appearances in long bones are not clearly understood and the correlation between these appearances and the IMP is not known. The distal femora of 10 anaesthetised rabbits were cannulated percutaneously. The IMP was measured and phlebography performed by injecting a radio-opaque dye (Conray 280).The mean resting IMP was 33 millimetres of mercury with a range of 7 to 81 millimetres of mercury. The rate of elimination of dye from the marrow varied from less than 1 minute to 40 minutes. There was no correlation between the rate of elimination of dye and the IMP. Variation in the medullary phlebographic appearance and in the routes of drainage were noted. We concluded that the wide range of resting values for both techniques suggest that neither is a true measure of blood flow in the bone and that the results of research or clinical investigation using these techniques should be viewed with caution