The peri-prosthetic tissue response to wear debris is complex and influenced by various factors including the size, area and number of particles. We hypothesised that the ‘biologically active area’ of all metal wear particles may predict the type of peri-prosthetic tissue response. . Peri-prosthetic tissue was sampled from 21 patients undergoing revision of a small diameter metal-on-metal (MoM) total hip arthroplasty (THA) for aseptic loosening. An enzymatic protocol was used for tissue digestion and scanning electron microscope was used to characterise particles. Equivalent circle diameters and particle areas were calculated. Histomorphometric analyses were performed on all tissue specimens. Aspirates of synovial fluid were collected for analysis of the cytokine profile analysis, and compared with a control group of patients undergoing primary THA (n = 11) and revision of a failed ceramic-on-polyethylene arthroplasty (n = 6). . The overall distribution of the size and area of the particles in both lymphocyte and non-lymphocyte-dominated responses were similar; however, the subgroup with lymphocyte-dominated peri-prosthetic tissue responses had a significantly larger total number of particles. . 14 cytokines (interleukin (IL)-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, interferon (IFN)-γ, and IFN-gamma-inducible protein 10), chemokines (macrophage inflammatory protein (MIP)-1α and MIP-1ß), and growth factors (granulocyte macrophage colony stimulating factor (GM-CSF) and platelet derived growth factor) were detected at significantly higher levels in patients with metal wear debris compared with the control group. . Significantly higher levels for IL-1ß, IL-5, IL-10 and GM-CSF were found in the subgroup of tissues from failed MoM THAs with a lymphocyte-dominated peri-prosthetic response compared with those without this response. . These results suggest that the ‘biologically active area’ predicts the type of peri-prosthetic tissue response. The cytokines IL-1ß, IL-5, IL-10, and GM-CSF are associated with lymphocyte-dominated tissue responses from failed small-diameter MoM THA. Cite this article: Bone Joint J 2015;97-B:917–23

Aims

Fungal and mycobacterial periprosthetic joint infections (PJI) are rare events. Clinicians are wary of missing these diagnoses, often leading to the routine ordering of fungal and mycobacterial cultures on periprosthetic specimens. Our goal was to examine the utility of these cultures and explore a modern bacterial culture technique using bacterial blood culture bottles (BCBs) as an alternative.

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To verify whether secretory leucocyte protease inhibitor (SLPI) can promote early tendon-to-bone healing after anterior cruciate ligament (ACL) reconstruction.

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Osteoarthritis (OA) is a common degenerative joint disease. The osteocyte transcriptome is highly relevant to osteocyte biology. This study aimed to explore the osteocyte transcriptome in subchondral bone affected by OA.

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Minimally manipulated cells, such as autologous bone marrow concentrates (BMC), have been investigated in orthopaedics as both a primary therapeutic and augmentation to existing restoration procedures. However, the efficacy of BMC in combination with tissue engineering is still unclear. In this study, we aimed to determine whether the addition of BMC to an osteochondral scaffold is safe and can improve the repair of large osteochondral defects when compared to the scaffold alone.

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BoneMaster is a thin electrochemically applied hydroxyapatite (HA) coating for orthopaedic implants that is quickly resorbed during osseointegration. Early stabilization is a surrogacy marker of good survival of femoral stems. The hypothesis of this study was that a BoneMaster coating yields a fast early and lasting fixation of stems.

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To explore the effect of different durations of antibiotics after stage II reimplantation on the prognosis of two-stage revision for chronic periprosthetic joint infection (PJI).

1. By reducing the viscosity of the synovial fluid within the ankle joints of rabbits and then subjecting these to prolonged exercise, wear and tear of articular cartilage can be consistently produced. 2. This finding is an indirect confirmation of the view that fluid film lubrication is an important factor in the mechanical efficiency of joints. 3. The special properties of synovial fluid and articular cartilage that allow fluid film lubrication to exist within joints that are, in effect, slowly moving, heavily loaded, reciprocating bearings are discussed. They account for the remarkable resistance to wear and tear exhibited by synovial joints under physiological conditions

1. The hyaluronate of synovial fluid is an acidic linear polymer which can effectively resist the diffusion of other macromolecules into its domain. Gelatin was used as an experimental model for hyaluronate, to investigate its effect upon the diffusion of protein-polysaccharides from cartilage slices. 2. The concentration of protein-polysaccilaride in the extracting medium was quantitated by uronic acid estimation and liquid scintillation spectrometry of . 35. sulphate-labelled proteinpolysaccharide. 3. Concentrations of gelatin in excess of 20 per cent (W/v) significantly retarded diffusion of protein-polysaccharides out of cartilage slices, but evidently not the movement of these molecules within cartilage. 4. It is suggested that disaggregation of both the protein-polysaecharide molecules of cartilage and the hyaluronate of synovial fluid contribute to cartilage breakdown

The appearance and the biochemical, cytological and bacteriological findings were studied in synovial fluid obtained from the knees of 72 patients from south-west India. We report a group of 12 patients with 'eosinophilic synovitis'. In these patients, all below the age of 20 years with an acute onset of severe pain in the knee, there was a large effusion with painful limitation of movement. Their blood leucocyte count averaged 11,200 per mm3 with a mild eosinophilia of 6%. Biochemical examination of synovial fluid was normal, but cytology showed an increase in leucocytes ranging from 1200 to 20,500 (mean 9525) with between 75% and 90% of eosinophils in eight patients and 60% to 75% in four. All the patients responded well to a course of diethylcarbamazine

Aims

Monocyte-lymphocyte ratio (MLR) or neutrophil-lymphocyte ratio (NLR) are useful for diagnosing periprosthetic joint infection (PJI), but their diagnostic values are unclear for screening fixation-related infection (FRI) in patients for whom conversion total hip arthroplasty (THA) is planned after failed internal fixation for femoral neck fracture.

Aims

The purpose of this study was to evaluate unexpected positive cultures in total hip arthroplasty (THA) revisions for presumed aseptic loosening, to assess the prevalence of low-grade infection using two definition criteria, and to analyze its impact on implant survival after revision.

Slipped upper femoral epiphysis remains a disease of unknown aetiology. Recent evidence has bolstered speculation that the immune system may play a role in the aetiology or pathogenesis of slipped epiphysis or of one of its complications, chondrolysis. This study reports the finding of immune complexes in the synovial fluid of all but one hip affected with slipped epiphysis in a consecutive series. In seven patients, immune complexes were detected by both the Raji cell assay and C1q-binding assay; in two, by the C1q-assay only; and in one, by the Raji cell assay only. No patients had immune complexes in the serum. Twenty-one patients with synovitis of the knee or hip caused by a variety of disorders served as the control group. Two of these patients had immune complexes in their synovial fluid. It appears that the immune complexes characterise the synovitis found with slipped upper femoral epiphysis as distinct from most other synovitides

Bone cement containing gentamicin may release antibiotic when fractured during revision operations. Tissue samples taken during surgery may be contaminated by gentamicin and give inaccurate microbiological assessment. We studied five patients in whom cement containing gentamicin had been used in the primary procedure. During revision hip replacement, samples of joint fluid, tissues and cement were taken both before and after disruption of the cement. With the exception of one sample of joint fluid, low concentrations of gentamicin were recorded in the samples taken before the cement was disrupted, but after disruption the specimens contained gentamicin at concentrations high enough to inhibit or prevent growth of sensitive organisms. The cement contained very high levels up to ten years after insertion. Our findings suggest that no reliance can be placed on the microbiological assessment of specimens taken once cement splitting has started and that specimens should therefore be taken as early as possible

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Histology is an established tool in diagnosing periprosthetic joint infections (PJIs). Different thresholds, using various infection definitions and histopathological criteria, have been described. This study determined the performance of different thresholds of polymorphonuclear neutrophils (≥ 5 PMN/HPF, ≥ 10 PMN/HPF, ≥ 23 PMN/10 HPF) , when using the European Bone and Joint Infection Society (EBJIS), Infectious Diseases Society of America (IDSA), and the International Consensus Meeting (ICM) 2018 criteria for PJI.

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This study uses prospective registry data to compare early patient outcomes following arthroscopic repair or debridement of the acetabular labrum.

Clinical prediction algorithms are used to differentiate transient synovitis from septic arthritis. These algorithms typically include the erythrocyte sedimentation rate (ESR), although in clinical practice measurement of the C-reactive protein (CRP) has largely replaced the ESR. We evaluated the use of CRP in a predictive algorithm. The records of 311 children with an effusion of the hip, which was confirmed on ultrasound, were reviewed (mean age 5.3 years (0.2 to 15.1)). Of these, 269 resolved without intervention and without long-term sequelae and were considered to have had transient synovitis. The remaining 42 underwent arthrotomy because of suspicion of septic arthritis. Infection was confirmed in 29 (18 had micro-organisms isolated and 11 had a high synovial fluid white cell count). In the remaining 13 no evidence of infection was found and they were also considered to have had transient synovitis. In total 29 hips were categorised as septic arthritis and 282 as transient synovitis. The temperature, weight-bearing status, peripheral white blood cell count and CRP was reviewed in each patient. A CRP > 20 mg/l was the strongest independent risk factor for septic arthritis (odds ratio 81.9, p < 0.001). A multivariable prediction model revealed that only two determinants (weight-bearing status and CRP > 20 mg/l) were independent in differentiating septic arthritis from transient synovitis. Individuals with neither predictor had a < 1% probability of septic arthritis, but those with both had a 74% probability of septic arthritis. A two-variable algorithm can therefore quantify the risk of septic arthritis, and is an excellent negative predictor.

1. Articular cartilage from immature rabbits was placed in and near the rabbit knee joints for periods up to ten weeks. 2. Autografts of articular cartilage when placed free in the joint soon became adherent to its synovial lining; the cartilage with its subchondral bone remained viable. 3. Homografts remained viable in the presence of joint fluid, but when in contact with synovium antigenic cellular reaction was produced early. The presence of subchondral bone intensified this reaction and led to graft invasion and destruction. 4. Partial thickness homografts of articular cartilage were also antigenic and were absorbed. When full thickness cartilage was used, this cellular invasion was resisted by the zone of provisional calcification which appeared to function as a physical barrier against antigenic cells of the host. 5. When placed in muscle, both autogenous and homogenous grafts failed to survive through lack of nutrition, although the autogenous subchondral bone remained viable. It is inferred that subchondral circulation is not sufficient for cartilage survival and synovial fluid is essential for its proper nutrition. 6. Surviving immature articular cartilage transplants underwent "ageing" changes

Aims

Osteoarthritis (OA) is the most prevalent systemic musculoskeletal disorder, characterized by articular cartilage degeneration and subchondral bone (SCB) sclerosis. Here, we sought to examine the contribution of accelerated growth to OA development using a murine model of excessive longitudinal growth. Suppressor of cytokine signalling 2 (SOCS2) is a negative regulator of growth hormone (GH) signalling, thus mice deficient in SOCS2 (Socs2^-/-) display accelerated bone growth.