Objectives

The purpose of this study was to examine the bactericidal efficacy of hydrogen peroxide (H₂O₂) on Cutibacterium acnes (C. acnes). We hypothesize that H₂O₂ reduces the bacterial burden of C. acnes.

In impaction grafting of contained bone defects after revision joint arthroplasty the graft behaves as a friable aggregate and its resistance to complex forces depends on grading, normal load and compaction. Bone mills in current use produce a distribution of particle sizes more uniform than is desirable for maximising resistance to shear stresses. We have performed experiments in vitro using morsellised allograft bone from the femoral head which have shown that its mechanical properties improve with increasing normal load and with increasing shear strains (strain hardening). The mechanical strength also increases with increasing compaction energy, and with the addition of bioglass particles to make good the deficiency in small and very small fragments. Donor femoral heads may be milled while frozen without affecting the profile of the particle size. Osteoporotic femoral heads provide a similar grading of sizes, although fewer particles are obtained from each specimen. Our findings have implications for current practice and for the future development of materials and techniques

1. The rate of non-union of 100 intertrochanteric osteotomies of the McMurray type, with internal fixation, is reported. One in five was not united one year after operation. The criteria of union are discussed. 2. The patient's disability in twelve ununited osteotomies has been assessed, and related to the mobility of the osteotomy. 3. The factors which prejudice union have been analysed. The principal cause of non-union appeared to be the varus angulation strain on a varus osteotomy displaced medially more than half the diameter of the bone. Obliquity inwards and upwards of the osteotomy was a contributory factor. The types of internal fixation used, the use of external splintage and the period of protected weight bearing with crutches did not appear to be related to the rate of union. 4. It is concluded that marked inward displacement of the osteotomy, combined with either obliquity of the osteotomy or a varus position, prejudices union; that the use of this technique is unfounded in principle and not supported empirically; and that displacement should be eschewed to avoid this complication of intertrochanteric osteotomy in the treatment of osteoarthritis of the hip

In thirty-one rat tibiae, plugs of plain acrylic cement were inoculated with Staphylococcus aureus; these all remained contaminated at the end of two weeks when the animals were killed. Inoculation with known strains of Pseudomonas, Proteus and Gp. G Streptococcus resulted in 70 to 93 per cent persisting contamination. Gentamicin, to which the organisms were fully sensitive, was efficacious in controlling the infection (90 per cent plugs proving sterile after two weeks). Fucidin was less successful against Staphylococcus aureus although effective in vitro. Intravenous inoculation with a suspension of Staphylococcus aureus succeeded in contaminanting 70 per cent of sixty plain cement plugs when injected into the tail vein half an hour after closure of the leg wounds. Only 11 per cent of sixty-four plugs were so contaminanted when the injection was delayed for two weeks. This animal model is submitted as a possible future means of testing different antibiotic-cement combinations against infection

1. Ten consecutive fractures of the dome of the talus are reported. Six were lateral, three medial and one anterior. 2. The injury is most commonly seen in the second and third decades of life, and with the exception of the rare anterior dome fracture, results from an inversion injury of the ankle. The possibility of a dome fracture associated with strain of the lateral ligament of the ankle joint should therefore always be borne in mind. 3. Antero-posterior views in neutral and in plantar fiexion are helpful in diagnosing medial dome fractures. Lateral fractures are best seen in an antero-posterior view taken in neutral flexion with 10 degrees inward rotation of the limb. 4. A large dome fracture with displacement should be accurately reduced by open operation in order to preserve congruity of the joint surface. 5. A small fracture with no displacement may be treated conservatively until radiographically it appears united. 6. A small fracture with marked displacement is best treated by early excision of the fragment to prevent further damage to the ankle joint

1. Homografts of eighteen-day-old foetal femora in pure strains of mice showed no fundamental difference in behaviour from grafts of more mature bone and cartilage. 2. Growth of bone was limited to a short period after transplantation and was abolished by previous immunisation. Cartilage growth alone was responsible for the increase in size of these transplants and did not appear to be influenced by the presence of immunity. 3. There is no reason to suppose that bone from an immature source is likely to behave more favourably than more mature bone homografts in clinical use. 4. The limited growth of cartilage and the total failure of bone survival in the heterografts indicate an immune reaction ofa different order from that which develops against the homograft. 5. The different effect of the homograft immune reaction on cartilage and bone enabled certain conclusions to be drawn concerning the part played by these two tissues in determining the form of a bone. Cartilage growth and development is shown to be regulated in large part by intrinsic factors. Bone growth and form on the other hand is shown to be dependent largely upon extrinsic influences

Aims

In this randomized study, we aimed to compare quality of regenerate in monolateral versus circular frame fixation in 30 patients with infected nonunion of tibia.

A cadaver study was performed to determine the effect of arm position and capsular release on rotator cuff repair. Artificial defects were made in the rotator cuff to include only the supraspinatus (small) or both supraspinatus and infraspinatus (large). The defects were repaired in a standard manner with the shoulder abducted 30 degrees at the glenohumeral joint. Strain gauges were placed on the lateral cortex of the greater tuberosity and measurements were recorded in 36 different combinations of abduction, flexion/extension, and medial/lateral rotation. Readings were obtained before and after capsular release. With small tears, tension in the repair increased significantly with movement from 30 degrees to 15 degrees of abduction (p < 0.01) but was minimally affected by changes in flexion or rotation. Capsular release significantly reduced the force (p < 0.01) at 0 degree and 15 degrees abduction. For large tears, abduction of 30 degrees or more with lateral rotation and extension consistently produced the lowest values. Capsular release resulted in 30% less force at 0 degree abduction (p < 0.05)

We adduce the following conclusions from our experience of using this spring-loaded compression screw on completely displaced medial fractures of the femoral neck:. 1. That this method probably eliminates non-union when the head is fully viable. 2. That primary "first-intention" osseous union occurs in approximately 33·3 per cent of cases. 3. That a vascular complication, of varying severity, undetectable by orthodox radiological tests, is revealed by extrusion of the screw in 66·6 per cent of cases. 4. That these observations disprove the idea that the main obstacle to revascularisation of an ischaemic head is the existence of forces so inclined to the axis of the femoral neck as to cause "shear.". 5. That, compared with the Smith-Petersen nail used for completely displaced fractures, continuous spring compression can materially reduce the incidence of utter mechanical failure within the first year after operation. This is the result of "mushroom" impaction which itself can resist shearing strain and so can permit function as a fibrous union. 6. That early and rapid extrusion is a sensitive indication of a vascular complication in the head. Forewarned by this, activity can be restricted, or possibly other measures adopted, to anticipate or permanently postpone serious trouble

Many knee surgeons flex the knee and sometimes also extend the hip before inflating a tourniquet on the thigh. This practice stems from the belief that these manoeuvres prevent excessive strain on the quadriceps during surgery, the assumption being that movement of the muscle is restricted by an inflated tourniquet. We therefore examined, using ultrasound, the movement of the quadriceps muscle above and below the tourniquet before and after inflation. We applied a tourniquet of standard size to the thigh of five volunteers for approximately five minutes. A bubble of air was injected into the quadriceps muscle above the tourniquet and was the proximal point of reference. The musculotendinous junction was the distal point. The movement of the reference point was measured by ultrasound before and after inflation of the tourniquet. Each measurement was repeated with either the knee flexed and the hip extended, or the hip flexed and the knee extended. The mean and standard deviation were recorded. Before inflation the mean amount of passive movement was 1.1 ± 0.13 cm proximal and 4.0 ± 0.08 cm distal to the tourniquet, with a range of movement of the knee of 0° to 137° (6.7°). After inflation the mean passive movement was 1.0 ± 0.07 cm proximal and 4.0 ± 0.08 cm distal to the tourniquet with a range of 0° to 132° (± 7.6°). The ultrasound findings therefore have shown no evidence of restriction of the quadriceps muscle by an inflated tourniquet

The orthopaedic surgeon is often the first consultant to whom a patient with syringomyelia is referred. The disease is not as rare as he may suppose, but its early presenting features are very variable; if he relies solely on such familiar features as pes cavus and scoliosis, he may well miss the diagnosis. The commonest presenting symptom is pain in the head, neck, trunk or limbs; headache or neckache made worse by straining is particularly significant. A history of birth injury also may suggest the possibility of syringomyelia, especially if any spasticity subsequently worsens. Neurological features which may be diagnostic include nystagmus, dissociated sensory loss, muscle wasting, spasticity of the lower limbs or Charcot's joints. Radiographic features include erosion of the bodies of cervical vertebrae and widening of the spinal canal; if, at C5, the size of the canal exceeds that of the body by 6 millimetres in the adult, pathological dilatation is present. The presence of basilar invagination or other abnormalities of the foramen magnum, of spina bifida occulta and of scoliosis are further pointers. Thermography is a useful way of showing asymmetrical sympathetic involvement in early cases. A greater awareness of the prevalence of syringomyelia may lead to earlier diagnosis and to early operation, which appears to hold out the best hope of arresting what is all too commonly a severely disabling and progressive condition

Experiments on white mice were undertaken to determine the reaction of bone to the intramedullary introduction of the virus of tick-borne encephalitis. The following conclusions were drawn. 1. The tick-borne encephalitis virus S47, when introduced intraosteally in white mice, provokes osteitis. 2. Inflammation may lead to acute necrosis of bone, preceded by marked medullary oedema and subsequent proliferation, or it may take a milder form with haemorrhagic effusion into the marrow tissue and subsequent hyperplasia of connective tissue. 3. Damage to the epiphysial and articular cartilage may ensue in the course of acute necrotic osteitis. 4. Skeletal and extra-skeletal osteogenesis is a characteristic feature of viral osteitis. 5. In radiographs in acute viral osteitis with extensive necrosis the expanded bone appears to be thickened. 6. Viruses of the S47 strain introduced intraosteally preserve their affinity for brain tissue after three passages through bone. 7. Viruses introduced into the bony tissue preserve their toxicity and are found in the bony tissue after ten days in quantities lethal for young mice when inoculated intracerebrally. 8. The tick-borne encephalitis virus S47 is pathogenic when inoculated into the marrow in white mice. 9. In osteitis of non-bacterial origin in man the possibility of viral infection should be considered

1. Posterior fusion of the spine in scoliosis cannot be relied upon to maintain correction of the curve or to prevent progression of a vicious resistant curve. It can, however, hold to some extent the correction of a mobile curve and the compensation of a fixed curve. 2. Despite generally poor results as assessed radiographically, the clinical improvement is often gratifying. Most patients claim to be greatly improved: the spine feels stronger, there is less fatigue, and balance is better controlled. Moreover, visible deformity may be improved markedly even though the anatomical correction as observed radiographically is slight (Figs. l0 and 11). 3. It is believed that the true cause of relapse is that the bone formed from sliver grafts remains immature for a long time. Even when incorporated with the immature bone of the child's spine or the mature bone of the adult spine, it remains soft and resilient. When subjected to the stresses and strains of weight bearing and gravity, and then to the unnatural forces which initiated or perpetuated the scoliosis, this immature bone undergoes remodelling to Wolff's Law—like the neck of the femur after slipping of the upper femoral epiphysis. The forces that alter the grafted bone are not only lateral forces but also—perhaps more important—rotational forces. There seems to be a definite link between the degree of rotation and the amount of relapse, correction being maintained best when rotation is least

1. In five series of experiments in eighty-two rabbits we succeeded in causing rarefaction of the calcaneum of all the animals soon after it was relieved from muscular compressing forces; new bone was generated when the calcaneum was subjected again to the stresses and strains of muscle contraction. 2. We found evidence that during muscle action pressure forces are transmitted through the bone, and that the presence or absence of these pressure forces conditions the balance between bone formation and bone removal. 3. In the calcaneum of the rabbit lack of muscular action seems to be the most important factor inducing osteoporosis. It is possible that the origin of post-traumatic osteoporosis has the same basis. 4. In our experiments bone rarefaction was characterised by a great increase in the vascularity of the bone; this increase ceased when the bone reached its final precarious bone density. Thus, vascular over-activity accompanied the removal of bone; but bone reconstruction was also seen to be accompanied by a more localised increase in vascularity. 5. From our experiments we cannot suggest that the inhibition of muscle contraction accompanying Sudeck's syndrome is responsible for this disorder, because we were unable in our animals to cause any of the other signs characteristic of Sudeck's bone atrophy. But the constancy with which we caused bone atrophy by the removal of muscle action may possibly help to explain the mechanism of bone absorption accompanying Sudeck's disease

Aims

Options for the treatment of intra-articular ligament injuries are limited, and insufficient ligament reconstruction can cause painful joint instability, loss of function, and progressive development of degenerative arthritis. This study aimed to assess the capability of a biologically enhanced matrix material for ligament reconstruction to withstand tensile forces within the joint and enhance ligament regeneration needed to regain joint function.

Aims

We compared implant and patient survival following intraoperative periprosthetic femoral fractures (IOPFFs) during primary total hip arthroplasty (THA) with matched controls.

We aimed to highlight the relationship between age and the architectural properties of trabecular bone, to outline the patterns in which the variations in these properties take place, and to investigate the influence of the architecture on the mechanical properties of trabecular bone in growing animals. We studied 30 lambs in three age groups and 20 sheep in two age groups. Cubes of subchondral bone were cut from the proximal tibia according to a standardised protocol. They were serially sectioned and their architectural properties were determined. Similar cubes were obtained from the identical anatomical position of the contralateral tibia and their compressive mechanical properties measured. The values obtained from the skeletally immature and mature individuals were compared. Multiple regression analyses were performed between the architectural and the mechanical properties. The bone volume fraction, the mean trabecular volume, the architectural and the mechanical anisotropy, the elastic modulus, the bone strength, the energy absorption to failure, and the elastic energy correlated positively with increasing age whereas the connectivity density, the bone surface density, the ultimate strain, the absorption of viscoelastic energy and the relative loss of energy correlated inversely. The values of all variables were significantly different in the skeletally mature and immature groups. We determined the patterns in which the variations took place. The bone volume fraction of the trabecular bone tissue was found to be the major predictor of its compressive mechanical properties. Together with the mean trabecular volume and the bone surface density, it explained 81% of the variations in the compressive elastic modulus of specimens obtained from the contralateral tibiae

Aims

The objectives of this study were to compare postoperative pain, analgesia requirements, inpatient functional rehabilitation, time to hospital discharge, and complications in patients undergoing conventional jig-based unicompartmental knee arthroplasty (UKA) versus robotic-arm assisted UKA.

Objectives

Unicompartmental knee arthroplasty (UKA) is one surgical option for treating symptomatic medial osteoarthritis. Clinical studies have shown the functional benefits of UKA; however, the optimal alignment of the tibial component is still debated. The purpose of this study was to evaluate the effects of tibial coronal and sagittal plane alignment in UKA on knee kinematics and cruciate ligament tension, using a musculoskeletal computer simulation.