We reviewed a series of 91 patients with deep infection of a cemented total hip arthroplasty caused by coagulase-negative staphylococci (C-NS). Of these, 72 were treated by one-stage exchange arthroplasty with a failure rate of 13% due to recurrence of infection. The other 19 patients have started or completed treatment by a two-stage exchange without failure to date. In 27 of the 91 patients multiple strains of C-NS were discovered, many being resistant to previously used antibiotics. The use of gentamicin-containing cement in the primary arthroplasty was significantly associated with the emergence of gentamicin-resistant C-NS in subsequent deep infection. Bacteriological diagnosis of such infections must take into consideration the possibility that multiple strains of the organism are involved

The sternoclavicular joint (SCJ) is a pivotal articulation in the linked system of the upper limb girdle, providing load-bearing in compression while resisting displacement in tension or distraction at the manubrium sterni. The SCJ and acromioclavicular joint (ACJ) both have a small surface area of contact protected by an intra-articular fibrocartilaginous disc and are supported by strong extrinsic and intrinsic capsular ligaments. The function of load-sharing in the upper limb by bulky periscapular and thoracobrachial muscles is extremely important to the longevity of both joints. Ligamentous and capsular laxity changes with age, exposing both joints to greater strain, which may explain the rising incidence of arthritis in both with age. The incidence of arthritis in the SCJ is less than that in the ACJ, suggesting that the extrinsic ligaments of the SCJ provide greater stability than the coracoclavicular ligaments of the ACJ. Instability of the SCJ is rare and can be difficult to distinguish from medial clavicular physeal or metaphyseal fracture-separation: cross-sectional imaging is often required. The distinction is important because the treatment options and outcomes of treatment are dissimilar, whereas the treatment and outcomes of ACJ separation and fracture of the lateral clavicle can be similar. Proper recognition and treatment of traumatic instability is vital as these injuries may be life-threatening. Instability of the SCJ does not always require surgical intervention. An accurate diagnosis is required before surgery can be considered, and we recommend the use of the Stanmore instability triangle. Most poor outcomes result from a failure to recognise the underlying pathology. There is a natural reluctance for orthopaedic surgeons to operate in this area owing to unfamiliarity with, and the close proximity of, the related vascular structures, but the interposed sternohyoid and sternothyroid muscles are rarely injured and provide a clear boundary to the medial retroclavicular space, as well as an anatomical barrier to unsafe intervention. This review presents current concepts of instability of the SCJ, describes the relevant surgical anatomy, provides a framework for diagnosis and management, including physiotherapy, and discusses the technical challenges of operative intervention. Cite this article: Bone Joint J 2013;95-B:721–31

Aims

The purpose of our study was to determine which groups of orthopaedic providers favour virtual care, and analyze overall orthopaedic provider perceptions of virtual care. We hypothesize that providers with less clinical experience will favour virtual care, and that orthopaedic providers overall will show increased preference for virtual care during the COVID-19 pandemic and decreased preference during non-pandemic circumstances.

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Aseptic loosening is a leading cause of uncemented arthroplasty failure, often accompanied by fibrotic tissue at the bone-implant interface. A biological target, neutrophil extracellular traps (NETs), was investigated as a crucial connection between the innate immune system’s response to injury, fibrotic tissue development, and proper bone healing. Prevalence of NETs in peri-implant fibrotic tissue from aseptic loosening patients was assessed. A murine model of osseointegration failure was used to test the hypothesis that inhibition (through Pad4^-/- mice that display defects in peptidyl arginine deiminase 4 (PAD4), an essential protein required for NETs) or resolution (via DNase 1 treatment, an enzyme that degrades the cytotoxic DNA matrix) of NETs can prevent osseointegration failure and formation of peri-implant fibrotic tissue.

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Biofilm formation is one of the primary reasons for the difficulty in treating implant-related infections (IRIs). Focused high-energy extracorporeal shockwave therapy (fhESWT), which is a treatment modality for fracture nonunions, has been shown to have a direct antibacterial effect on planktonic bacteria. The goal of the present study was to investigate the effect of fhESWT on Staphylococcus aureus biofilms in vitro in the presence and absence of antibiotic agents.

We tested in compression specimens of human proximal tibial trabecular bone from 31 normal donors aged from 16 to 83 years and determined the mechanical properties, density and mineral and collagen content. Young’s modulus and ultimate stress were highest between 40 and 50 years, whereas ultimate strain and failure energy showed maxima at younger ages. These age-related variations (except for failure energy) were non-linear. Tissue density and mineral concentration were constant throughout life, whereas apparent density (the amount of bone) varied with ultimate stress. Collagen density (the amount of collagen) varied with failure energy. Collagen concentration was maximal at younger ages but varied little with age. Our results suggest that the decrease in mechanical properties of trabecular bone such as Young’s modulus and ultimate stress is mainly a consequence of the loss of trabecular bone substance, rather than a decrease in the quality of the substance itself. Linear regression analysis showed that collagen density was consistently the single best predictor of failure energy, and collagen concentration was the only predictor of ultimate strain

1. A series of 154 patients who underwent anterior cervical discectomy and fusion has been studied. A detailed analysis of the first eighty-four patients who have been observed for periods of from one to eight and a half years is described. In sixty-eight patients the fusion was done with a keystone type of graft, in seventeen by a dowel (Cloward) graft. 2. Despite a preponderance of multiple level fusions in the keystone series, clinically better results (80·8 per cent excellent or good) were found in this group than in the dowel group (64·8 per cent excellent or good). 3. A biomechanical study has indicated the keystone graft to be more stable than a dowel graft under flexion and extension strains as well as lateral bending strain. The graft is more stable the closer it is to the line of "zero velocity.". 4. The three cases of non-union all occurred in the dowel group. The high incidence of fusion with the keystone technique is considered to be related to the type of graft, its method of seating, its depth of penetration, its larger surface area and the fact that raw cancellous bone of the adjacent vertebral bodies is in contact with the graft above and below

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The aim of this study was to screen the entire genome for genetic markers associated with risk for anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injury.

We have used an experimental model employing the bent tail of rats to investigate the effects of mechanical forces on bones and joints. Mechanical strain could be applied to the bones and joints of the tail without direct surgical exposure or the application of pins and wires. The intervertebral disc showed stretched annular lamellae on the convex side, while the annulus fibrosus on the concave side was pinched between the inner corners of the vertebral epiphysis. In young rats with an active growth plate, a transverse fissure appeared at the level of the hypertrophic cell layer or the primary metaphyseal trabecular zone. Metaphyseal and epiphyseal trabeculae on the compressed side were thicker and more dense than those of the distracted part of the vertebra. In growing animals, morphometric analysis of hemiepiphyseal and hemimetaphyseal areas, and the corresponding trabecular bone density, showed significant differences between the compressed and distracted sides. No differences were observed in adult rats. We found no significant differences in osteoclast number between compressed and distracted sides in either age group. Our results provide quantitative evidence of the working of ‘Wolff’s law’. The differences in trabecular density are examples of remodelling by osteoclasts and osteoblasts; our finding of no significant difference in osteoclast numbers between the hemiepiphyses in the experimental and control groups suggests that the response of living bone to altered strain is mediated by osteoblasts

Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship.

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The Exeter V40 cemented polished tapered stem system has demonstrated excellent long-term outcomes. This paper presents a systematic review of the existing literature and reports on a large case series comparing implant fractures between the Exeter V40 series; 125 mm and conventional length stem systems.

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The processes linking long-term bisphosphonate treatment to atypical fracture remain elusive. To establish a means of exploring this link, we have examined how long-term bisphosphonate treatment with prior ovariectomy modifies femur fracture behaviour and tibia mass and shape in murine bones.

We studied the biomechanical behaviour of three sliding fixation devices for trochanteric femoral fractures. These were a titanium alloy sideplate and lag screw, a titanium alloy sideplate and dome plunger with cement augmentation, and a stainless-steel sideplate and lag screw. We used 18 mildly osteoporotic cadaver femora, randomly assigned to one of the three fixation groups. Four displacement and two strain gauges were fixed to each specimen, and each femur was first tested intact (control), then as a two-part fracture and then as a four-part intertrochanteric fracture. A range of physiological loads was applied to determine load-bearing, load-sharing and head displacement. The four-part-fracture specimens were subsequently tested to failure to determine maximum fixation strengths and modes of failure. The dome-plunger group failed at a load 50% higher than that of the stainless-steel lag-screw group (p < 0.05) and at a load 20% higher than that of the titanium-alloy lag-screw group (NS). All 12 lag-screw specimens failed by cut-out through the femoral head or neck, but none of the dome-plunger group showed movement within the femoral head when tested to failure. Strain-gauge analysis showed that the dome plunger produced considerably less strain in the inferior neck and calcar region than either of the lag screws. Inferior displacement of the femoral head was greatest for the dome-plunger group, and was due to sliding of the plunger. The dome plunger with cement augmentation was able to support higher loads and did not fail by cut-out through the femoral head.(ABSTRACT TRUNCATED AT 250 WORDS)

Of the 4172 patients in a survey of all cases of tuberculosis notified in a six-month period in England and Wales in 1978-79, 198 had a bone or joint lesion; 79 were white and 108 were of Indian subcontinent (Indian, Pakistani or Bangladeshi) ethnic origin. The estimated annual notification rates for orthopaedic tuberculosis were 29 per 100 000 for the Indian subcontinent group and 0.34 per 100 000 in the white group, a ratio of 85 to 1. Rates increased with age in both groups. The spine was the most common site, and was affected in 30% of the white patients and 43% of the Indian subcontinent patients; the distribution of other sites was similar in both groups. Positive culture from a bone or joint lesion was obtained in 99 (50%) of the 198 patients (58% of white patients and 47% of the Indian subcontinent patients). Bacteriological or histological confirmation of tuberculosis either from a bone or joint lesion or from another site was obtained in 68% of the patients. Mycobacterium tuberculosis was isolated from the orthopaedic lesions in 79 of the 82 patients with identification test results and M. bovis in the 3 remaining patients. Of the 61 patients with M. tuberculosis and with no history of previous chemotherapy, 5 had resistant strains compared with 1 of the 18 patients who had previously received chemotherapy. All 6 patients with resistant strains were of Indian subcontinent ethnic origin

1. Three groups of one month old rats were fed for a period of four to five weeks on a rachitogenic diet (group R), the same rachitogenic diet with vitamin D (group N), and a complete diet (group S). 2. Young's modulus of elasticity E for bone can be derived from measurements of the deflexion of the centre of a femur loaded at the centre and supported at its ends. 3. The three different diets produced significant differences in breaking stress S. B. , Young's modulus E, and percentage ash in the bones. It has not been shown conclusively that higher ash content alone is responsible for the greater S. B. and E values of bones produced on the better diets. 4. The value of E in group R was 0·6 x 10. 6. lb./in. 2. ; in group N 1·0 x 10. 6. lb./in. 2. ; and in group S (which can be taken as normal) 1·6 x 10. 6. lb./in. 2. . 5. There is a high correlation between S. B. and E even when the effect of diet is eliminated. 6. Although the bones produced on the good diet (group S) were much stronger than those of groups N or R, the strain at the elastic limit was the same (about 1·5 per cent.). The strain at rupture tended to be higher in groups N and R than in group S. 7. The properties of bone as a structural material are discussed

Our aim was to determine the relationship between age and the mechanical and physical properties of trabecular bone, to describe the patterns in which the variations in these properties take place, and to investigate the influence of the physical properties on the mechanical characteristics of trabecular bone during growth. We used 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. We performed non-destructive compression tests of the specimens in three orthogonal directions and compression tests to failure in the axial direction. The physical properties of the specimens were also determined. The data were correlated with age and compared in skeletally immature and mature animals. Multiple regression analyses were performed between the mechanical and the physical properties. Age correlated positively with elastic modulus, bone strength, energy absorption to failure, elastic energy, mechanical anisotropy ratio, tissue density, apparent density, apparent ash density, and bone mineral content, and inversely with ultimate strain, viscoelastic energy absorption, relative energy loss, the collagen content of bone and the percentage porosity. The values of all variables were significantly different in the skeletally mature and immature groups. The apparent density of trabecular bone tissue was found to be the major predictor of its compressive mechanical properties. Together with the content of bone muscle and bone collagen, the apparent density could explain 84% of the variation in the elastic modulus, whereas only a small portion of the variation in ultimate strain could be explained by the variation in apparent density

Surgical treatment for traumatic, anterior glenohumeral instability requires repair of the anterior band of the inferior glenohumeral ligament, usually at the site of glenoid insertion, often combined with capsuloligamentous plication. In this study, we determined the mechanical properties of this ligament and the precise anatomy of its insertion into the glenoid in fresh-frozen glenohumeral joints of cadavers. Strength was measured by tensile testing of the glenoid-soft-tissue-humerus (G-ST-H) complex. Two other specimens of the complex were frozen in the position of apprehension, serially sectioned perpendicular to the plane containing the anterior and posterior rims of the glenoid, and stained with Toluidine Blue. On tensile testing, eight G-ST-H complexes failed at the site of the glenoid insertion, representing a Bankart lesion, two at the insertion into the humerus, and two at the midsubstance. For those which failed at the glenoid attachment the mean yield load was 491.0 N and the mean ultimate load, 585.0 N. At the glenoid region, stress at yield was 7.8 ± 1.3 MPa and stress at failure, 9.2 ± 1.5 MPa. The permanent deformation, defined as the difference between yield and ultimate deformation, was only 2.3 ± 0.8 mm. The strain at yield was 13.0 ± 0.7% and at failure, 15.4 ± 1.2%; therefore permanent strain was only 2.4 ± 1.1%. Histological examination showed that there were two attachments of the anterior band of the inferior glenohumeral ligament at the site of the glenoid insertion. In one, poorly organised collagen fibres inserted into the labrum. In the other, dense collagen fibres were attached to the front of the neck of the glenoid

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In wound irrigation, 1 mM ethylenediaminetetraacetic acid (EDTA) is more efficacious than normal saline (NS) in removing bacteria from a contaminated wound. However, the optimal EDTA concentration remains unknown for different animal wound models.