Prolonged suppressive antibiotic therapy is successful in the management of prosthetic joint infection.

INTRODUCTION: Prosthetic joint infection (PJI) remains one of the major challenges facing orthopaedic surgeons. There is a paucity of evidence on non-operative management of PJI. We present the results of prolonged antibiotic suppression therapy (PSAT) in PJI from a single centre. METHODS: A retrospective study was performed. Twenty-six patients were included. Two patients were excluded due to the lack of follow-up data. Failure was defined as admission for sepsis from the joint or amputation. RESULTS: Average age was 72 years (range 35-93). Mean Charlson co-morbidity index was 4.3. Mean follow-up was 3.2 years (range 1.3-5.7). Staphylococcal species were isolated in 11 cases (44%) (MRSA 1, MSSA 5, Staph. epidermidis 4 and Staph Pasteuri 1). Other bacteria included E. Coli (2), Streptococci spp. (3), Propionebacterium acnes (1) and Pseudomonas aeruginosa (1). Four cases were polymicrobial infection (16%), and no organisms were identified in two cases (8%). Candida albicans was identified in one case. All cases of bacterial infection were treated with prolonged oral doxycycline or amoxicillin. Twenty patients (80%) received 6 weeks of intravenous antibiotics prior to commencing prolonged oral antibiotics. Two patients experienced persistent symptoms and required amputation (both TKA). Two patients experienced sepsis but were treated successfully with IV antibiotics alone. The success rate of PSAT was 84% (21/25) successful at an average 3.2-year follow-up. DISCUSSION AND CONCLUSION: Prolonged suppressive antibiotic therapy is a viable option for the management of PJI with a low incidence of complications.

Clinically insignificant trunnionosis in large-diameter metal-on-polyethylene total hip arthroplasty.

OBJECTIVES: Mechanical wear and corrosion at the head-stem junction of total hip arthroplasties (THAs) (trunnionosis) have been implicated in their early revision, most commonly in metal-on-metal (MOM) hips. We can isolate the role of the head-stem junction as the predominant source of metal release by investigating non-MOM hips; this can help to identify clinically significant volumes of material loss and corrosion from these surfaces. METHODS: In this study we examined a series of 94 retrieved metal-on-polyethylene (MOP) hips for evidence of corrosion and material loss at the taper junction using a well published visual grading method and an established roundness-measuring machine protocol. Hips were retrieved from 74 male and 20 female patients with a median age of 57 years (30 to 76) and a median time to revision of 215 months (2 to 324). The reasons for revision were loosening of both the acetabular component and the stem (n = 29), loosening of the acetabular component (n = 58) and infection (n = 7). No adverse tissue reactions were reported by the revision surgeons. RESULTS: Evidence of corrosion was observed in 55% of hips. The median Goldberg taper corrosion score was 2 (1 to 4) and the annual rate of material loss at the taper was 0.084 mm3/year (0 to 0.239). The median trunnion corrosion score was 1 (1 to 3). CONCLUSIONS: We have reported a level of trunnionosis for MOP hips with large-diameter heads that were revised for reasons other than trunnionosis, and therefore may be clinically insignificant.Cite this article: H. S. Hothi, D. Kendoff, C. Lausmann, J. Henckel, T. Gehrke, J. Skinner, A. Hart. Clinically insignificant trunnionosis in large-diameter metal-on-polyethylene total hip arthroplasty. Bone Joint Res 2017;6:52-56. DOI: 10.1302/2046-3758.61.BJR-2016-0150.R2.

International metal-on-metal multidisciplinary teams: do we manage patients with metal-on-metal hip arthroplasty in the same way? An analysis from the International Specialist Centre Collaboration on MOM Hips (ISCCoMH).

AIMS: There are many guidelines that help direct the management of patients with metal-on-metal (MOM) hip arthroplasties. We have undertaken a study to compare the management of patients with MOM hip arthroplasties in different countries. METHODS: Six international tertiary referral orthopaedic centres were invited to participate by organising a multi-disciplinary team (MDT) meeting, consisting of two or more revision hip arthroplasty surgeons and a musculoskeletal radiologist. A full clinical dataset including history, blood tests and imaging for ten patients was sent to each unit, for discussion and treatment planning. Differences in the interpretation of findings, management decisions and rationale for decisions were compared using quantitative and qualitative methods. RESULTS: Overall agreement between the orthopaedic centres and the recommended treatment plans for the ten patients with MOM hip implants was moderate (kappa = 0.6). Full agreement was seen in a third of cases, however split decisions were also seen in a third of cases. Units differed in their interpretation of the significance of the investigation findings and put varying emphasis on serial changes, in the presence of symptoms. DISCUSSION: In conclusion, the management of raised or rising blood metal ions, cystic pseudotumours and peri-acetabular osteolysis led to inconsistency in the agreement between centres. Coordinated international guidance and MDT panel discussions are recommended to improve consensus in decision making. TAKE HOME MESSAGE: A lack of evidence and the subsequent variation in regulator guidance leads to differences in opinions, the clinical impact of which can be reduced through a multi-disciplinary team approach to managing patients with MOM hip implants. Cite this article: Bone Joint J 2016;98-B:179-86.

Septic single-stage knee arthrodesis after failed total knee arthroplasty using a cemented coupled nail.

Knee arthrodesis is a potential salvage procedure for limb preservation after failure of total knee arthroplasty (TKA) due to infection. In this study, we evaluated the outcome of single-stage knee arthrodesis using an intramedullary cemented coupled nail without bone-on-bone fusion after failed and infected TKA with extensor mechanism deficiency. Between 2002 and 2012, 27 patients (ten female, 17 male; mean age 68.8 years; 52 to 87) were treated with septic single-stage exchange. Mean follow-up duration was 67.1months (24 to 143, n = 27) (minimum follow-up 24 months) and for patients with a minimum follow-up of five years 104.9 (65 to 143,; n = 13). A subjective patient evaluation (Short Form (SF)-36) was obtained, in addition to the Visual Analogue Scale (VAS). The mean VAS score was 1.44 (SD 1.48). At final follow-up, four patients had recurrent infections after arthrodesis (14.8%). Of these, three patients were treated with a one-stage arthrodesis nail exchange; one of the three patients had an aseptic loosening with a third single-stage exchange, and one patient underwent knee amputation for uncontrolled sepsis at 108 months. All patients, including the amputee, indicated that they would choose arthrodesis again. Data indicate that a single-stage knee arthrodesis offers an acceptable salvage procedure after failed and infected TKA.

[CD15 focus score for diagnostics of periprosthetic joint infections : Neutrophilic granulocytes quantification mode and the development of morphometric software (CD15 quantifier)]. / CD15-Fokus-Score zur Diagnostik der periprothetischen Gelenkinfektion : Neutrophile-Granulozyten-Quantifizierungs-Modus und Entwicklung einer morphometrischen Software ("CD15-Quantifier").

BACKGROUND: The aim of this project was to devise a quantification method for neutrophils within a single focal point through the development of a CD15 focus score which enables bacterial infections in synovial-like interface membranes (SLIM) to be diagnosed. METHODS: In this study a histopathological classification of 91 SLIM removed during revision surgery from the hips (n = 59) and knees (n = 32) was performed. Neutrophils were identified immunohistochemically by means of a CD15-specific monoclonal antibody. The quantitative evaluation of CD15-positive neutrophils (CD15Ne) used the principle of maximum focal infiltration (focus) together with an assessment of a single focal point (0.3 mm(2)). This immunohistochemical approach made it possible to develop the CD15 quantifier software, which automatically quantifies CD15Ne. RESULTS: The SLIM cases with positive microbiological findings (n = 47) had significantly (p < 0.001, Mann-Whitney U-test) more CD15Ne/focal point than cases with negative microbiological findings (n = 44). A count of 50 CD15Ne/focal point was identified as the optimum threshold when diagnosing periprosthetic joint infections (PJI) using the CD15 focus score. If the microbiological findings are used as a gold standard, the diagnostic sensitivity is 0.83, and the specificity is 0.864 with a positive predictive value (PPV) of 0.87, a negative predictive value (NPV) of 0.83, an accuracy of 0.846 and an area under the curve (AUC) of 0.878. The evaluation of findings for the preparations using the CD15 quantifier software (n = 31) deviated by an average of 12 cells from the histopathological evaluation findings (CD15 focus score). Above a cell count of 62, the CD15-quantifier needs on average 32 s less than the pathologist. CONCLUSION: The immunohistochemical CD15 focus score has a high diagnostic value and allowed the development of the CD15 quantifier software. This provides an automated procedure, which shortens the mentally tiring and time-consuming process of microscopic cell counting and thus makes a contribution towards the standardization of tools for diagnosing PJI.

[Revision arthroplasty : Histopathological diagnostics in periprosthetic joint infections]. / Revisionsendoprothetik : Infektionsdiagnostik und Histopathologie.

BACKGROUND: Histopathological differences in synovia and synovial-like interface membrane (SLIM) patterns can be used to differentiate periprosthetic particle-induced reactions, bacterial infections (bacterial synovitis and osteomyelitis), mechanical-induced tissue alterations, adverse reactions to implant material, and arthrofibrosis (SLIM consensus classification). AIM: Because of differences in treatment the diagnosis of a bacterial implant infection is very important. Histopathological tests and scoring systems are important diagnostic tools in identifying deep implant infections in patients with unclear clinical history as well as radiographic and laboratory studies. RESULTS: Modern enzyme PCR-based methods, histochemical- and immune-histopathological techniques (CD3,CD15, CD68) are useful in identifying specific and nonspecific infections, as well as differentiating postsurgical changes from recurrent infections in patients with a spacer. In all histopathological scoring systems for bacterial infection, quantifying the number of neutrophil granulocytes in a defined number of high power fields is crucial. DISCUSSION: Neutrophil granulocytes can be detected through histochemical methods and more specifically by immune-histopathological techniques and by various quantification systems (histopathological scores) leading to the diagnosis of bacterial peri-implant infection. One important function of histopathology, apart from diagnosing infection, is to rule out other mechanisms of implant failure, such as tumor infiltrations, particle-induced reactions, and adverse reactions to implant materials.

Revised histopathological consensus classification of joint implant related pathology.

This extended classification of joint implant related pathology is a practical histopathologic classification based on defined morphological criteria covering the complete spectrum of pathohistologic changes in periprosthetic tissues. These changes may occur as a consequence of endoprosthetic replacement of large joints and may lead to a reduction in the prosthesis survival rate. We describe the established consensus classification of the periprosthetic membrane, in which aseptic and septic prosthetic loosening can be subdivided into four histological types, as well as histopathological criteria for additional significant pathologies including endoprosthetic-associated arthrofibrosis, particle-induced immunological, inflammatory and toxic mechanisms (adverse reactions), and bone tissue pathologies. These characteristic tissue alterations and their relationships are summarized in the extended classification. Since particle heterogeneity in periprosthetic tissue is high and particle identification is a necessary part of diagnosis, the identification of different types of particles is described in the histopathological particle algorithm. The morphological qualities of prosthetic material particles and the demarcation between abrasion and non-abrasion endogenous particles are also summarized. This feasible classification which is based on low cost standard tissue processing and examination and on well-defined diagnostic criteria is a solid platform for the histological diagnosis of implant associated pathologies providing a stable and reproducible tool for the surgical pathologist. Since this classification is suitable for standardized histopathological diagnostics, it might also provide a useful data set for joint arthroplasty registers, particularly for registers based on so-called routine data.

The role of hinges in primary total knee replacement.

The use of hinged implants in primary total knee replacement (TKR) should be restricted to selected indications and mainly for elderly patients. Potential indications for a rotating hinge or pure hinge implant in primary TKR include: collateral ligament insufficiency, severe varus or valgus deformity (>20°) with necessary relevant soft-tissue release, relevant bone loss including insertions of collateral ligaments, gross flexion-extension gap imbalance, ankylosis, or hyperlaxity. Although data reported in the literature are inconsistent, clinical results depend on implant design, proper technical use, and adequate indications. We present our experience with a specific implant type that we have used for over 30 years and which has given our elderly patients good mid-term results. Because revision of implants with long cemented stems can be very challenging, an effort should be made in the future to use shorter stems in modular versions of hinged implants.

Single-stage revision for fungal peri-prosthetic joint infection: a single-centre experience.

Fungal peri-prosthetic infections of the knee and hip are rare but likely to result in devastating complications. In this study we evaluated the results of their management using a single-stage exchange technique. Between 2001 and 2011, 14 patients (ten hips, four knees) were treated for a peri-prosthetic fungal infection. One patient was excluded because revision surgery was not possible owing to a large acetabular defect. One patient developed a further infection two months post-operatively and was excluded from the analysis. Two patients died of unrelated causes. After a mean of seven years (3 to 11) a total of ten patients were available for follow-up. One patient, undergoing revision replacement of the hip, had a post-operative dislocation. Another patient, undergoing revision replacement of the knee, developed a wound infection and required revision 29 months post-operatively following a peri-prosthetic femoral fracture. The mean Harris hip score increased to 74 points (63 to 84; p < 0.02) in those undergoing revision replacement of the hip, and the mean Hospital for Special Surgery knee score increased to 75 points (70 to 80; p < 0.01) in those undergoing revision replacement of the knee. A single-stage revision following fungal peri-prosthetic infection is feasible, with an acceptable rate of a satisfactory outcome.

The current state of bearing surfaces in total hip replacement.

We reviewed the literature on the currently available choices of bearing surface in total hip replacement (THR). We present a detailed description of the properties of articulating surfaces review the understanding of the advantages and disadvantages of existing bearing couples. Recent technological developments in the field of polyethylene and ceramics have altered the risk of fracture and the rate of wear, although the use of metal-on-metal bearings has largely fallen out of favour, owing to concerns about reactions to metal debris. As expected, all bearing surface combinations have advantages and disadvantages. A patient-based approach is recommended, balancing the risks of different options against an individual's functional demands.

One-stage exchange: it all began here.

Based on the first implementation of mixing antibiotics into bone cement in the 1970s, the Endo-Klinik has used one stage exchange for prosthetic joint infection (PJI) in over 85% of cases. Looking carefully at current literature and guidelines for PJI treatment, there is no clear evidence that a two stage procedure has a higher success rate than a one-stage approach. A cemented one-stage exchange potentially offers certain advantages, mainly based on the need for only one operative procedure, reduced antibiotics and hospitalisation time. In order to fulfill a one-stage approach, there are obligatory pre-, peri- and post-operative details that need to be meticulously respected, and are described in detail. Essential pre-operative diagnostic testing is based on the joint aspiration with an exact identification of any bacteria. The presence of a positive bacterial culture and respective antibiogram are essential, to specify the antibiotics to be loaded to the bone cement, which allows a high local antibiotic elution directly at the surgical side. A specific antibiotic treatment plan is generated by a microbiologist. The surgical success relies on the complete removal of all pre-existing hardware, including cement and restrictors and an aggressive and complete debridement of any infected soft tissues and bone material. Post-operative systemic antibiotic administration is usually completed after only ten to 14 days.

Femoral stem impaction grafting: extending the role of cement.

Femoral revision after cemented total hip replacement (THR) might include technical difficulties, following essential cement removal, which might lead to further loss of bone and consequently inadequate fixation of the subsequent revision stem. Femoral impaction allografting has been widely used in revision surgery for the acetabulum, and subsequently for the femur. In combination with a primary cemented stem, impaction grafting allows for femoral bone restoration through incorporation and remodelling of the impacted morsellized bone graft by the host skeleton. Cavitary bone defects affecting meta-physis and diaphysis leading to a wide femoral shaft, are ideal indications for this technique. Cancellous allograft bone chips of 1 mm to 2 mm size are used, and tapered into the canal with rods of increasing diameters. To impact the bone chips into the femoral canal a prosthesis dummy of the same dimensions of the definitive cemented stem is driven into the femur to ensure that the chips are very firmly impacted. Finally, a standard stem is cemented into the neo-medullary canal using bone cement. To date several studies have shown favourable results with this technique, with some excellent long-term results reported in independent clinical centres worldwide.

Histopathological, immunohistochemical criteria and confocal laser-scanning data of arthrofibrosis.

Arthrofibrosis (af) is defined as a fibrosing disease of the synovial membrane, after joint operations, with painful restricted range of motion. The aim of this paper was to describe the histopathological substrate of af, hitherto only defined by clinical criteria. Based on a group of 222 tissue samples, the characteristic changes to af were analyzed. The control group comprised 29 cases with neosynovialis of the indifferent type. Due to cytoplasmic SM-actin positivity and the absence of specific cytoplasmic reactivity in CD 68 representation, af fibroblasts were characterized as myofibroblasts. In confocal laser-scanning microscopy, ß-catenin-positive aggregates were detected in the cytoplasm. Over and above this, unequivocal colocalization of ß-catenin and the tight junction protein ZO-1 became manifest, particularly on the cell membrane and, partly, in the cytoplasm. A threshold value of 20 ß-catenin-positive cells/HPF was determined. This enables the histopathological diagnosis of an af to be made (sensitivity: 0.733, specificity: 0.867). Af is a fibrosing disease of the synovial membrane with variable grade of fibrotization (fibroblast cellularity). A threshold value of 20 ß-catenin-positive fibroblasts per HPF was defined, which enables the histopathological diagnosis of af.

Dislocation after total hip arthroplasty.

Dislocation remains one of the most common complications after total hip arthroplasty, regardless of the surgical approach. While multiple reasons as laxity, implant position, improper implant choice, and impingement etc. might be leading factors for dislocation, an exact identification of the exact reason is of major importance, to plan for a proper surgical or nonsurgical correction. This article describes in detail the definition, etiology, reduction, and possible treatment options for dislocation after primary and revision total hip arthroplasty that are currently used at the Endo Klinik in Hamburg. It furthermore includes a distinct overview of possible surgical treatment options, based on the main pathology leading to dislocation.

[Histopathological differential diagnostics in context of joint implant allergic reactions]. / Histopathologische Differenzialdiagnostik bei gelenkimplantatallergischen Fragestellungen.

Total joint replacement has greatly increased over the last decades and so have endoprothesis-associated pathologies. European studies have shown a 10-year durability varying from 88% to 95%. By means of histopathology different pathogenetic synovial-like interface membrane (SLIM) patterns that lead to reduction of implant durability can be discerned, such as periprosthetic particles, bacterial infections and arthrofibrosis. Subsequently, SLIM types have been determined in a revised consensus classification including particle-induced type (type I) so-called non-septic loosening, infection type (type II) so-called septic loosening, combination type (type III) of bacterial and particle-induced types, indifferent type with mechanical and functional disorders (type IV), osseus pathologies (type V), arthrofibrotic type (type VI, endoprosthesis-associated arthrofibrosis) and allergic/immunological/toxic reactions to prosthesis material (type VII). Particles are characterized histopathologically according to the Krenn particle algorithm. In cases of severe lymphocyte/macrophage infiltration, necrosis, abrasion particle detection and granuloma formation, a toxic or allergic reaction to implant material should be considered. As a direct abrasion particle-induced toxicity cannot be differentiated from a particle-induced allergic type VII reaction to implant material, the histopathological diagnosis of toxic reaction to implant material or allergic reaction to implant material should be made with caution and only in association with immunological, allergic and clinical data. It is recommended that tissue samples should be arthroscopically taken from different regions: close to the prosthesis, distant from the prosthesis and from bone tissue. The pathologist should be given information concerning clinical, allergological and microbiological data.

[Non-traumatic anterior knee dislocation in a patient with osteoarthritis of the knee]. / Atraumatische anteriore Kniegelenksluxation bei Pangonarthrose.

Complete knee dislocation is a rare and severe injury and usually follows high-energy trauma. Non-traumatic knee dislocations are exceedingly rare, while severe overweight appears to be the main cause of the knee dislocation. We here report on a spontaneous knee dislocation in a patient with severe osteoarthritis of the left knee. A 68-year-old woman was admitted to our hospital for an elective total knee replacement. One year prior to admission, a planned joint replacement was not performed due to an existing ulcus cruris. After healing of the ulcus cruris, the patient presented with progressive pain and instability of the left knee without any trauma. The clinical examination showed a multidirectional instability of the left knee with a restricted range of motion (ROM) with 0-0-40 degrees for extension and flexion. The performed radiological examination revealed an anterior knee dislocation of the left knee. Intraoperative findings suggest a non-traumatic aetiology. We suspect that osteoarthritis of the left knee has caused the dislocation. Therefore, we recommend, even in usually "harmless" osteoarthritis, close clinical and radiological follow-up examinations to detect and treat possible complications.

Infection rates in patients undergoing primary knee arthroplasty with pre-existing orthopaedic fixation-devices.

BACKGROUND: Prior knee surgery in the setting of knee arthroplasty (KA) can influence the overall outcome of the procedure and render the operation more technically challenging. The effects of residual fixation devices on subsequent procedures about the knee are ill-defined. Some authors claim an increase in periprosthetic infection in this cohort of patients. The objective of this study was to evaluate the overall incidence of periprosthetic infections in patients undergoing primary KA with pre-existing osteosynthetic hardware in situ. METHODS: The current investigators retrospectively reviewed 124 patients undergoing knee arthroplasty and removal of orthopaedic fixation devices, due to prior high tibial osteotomies, fracture fixation or cruciate ligament reconstruction. The exclusion criterion was a prior history of infection of the fixation device. The mean follow-up time was 5.4 years (range 15 months to 9 years). Nine patients were lost to follow-up. RESULTS: Joint aspiration was performed two weeks prior to surgery in 53 patients (42.4%) and intra-operative samples were obtained in 106 patients (84.8%), which did not show any bacterial growth. A subacute periprosthetic infection occurred after seven months in only one patient. CONCLUSION: The results of the current study demonstrate that previously implanted osteosynthetic fixation devices do not significantly increase the risk of developing periprosthetic knee infections. A two-stage procedure with implant retrieval prior to total knee arthroplasty is not clinically indicated in the cohort described, amongst whom an infection rate of 0.9% was revealed.

Single-stage revision for peri-prosthetic shoulder infection: outcomes and results.

There have been only a few small studies of patients with an infected shoulder replacement treated with a single-stage exchange procedure. We retrospectively reviewed 35 patients (19 men and 16 women) with a peri-prosthetic infection of the shoulder who were treated in this way. A total of 26 were available for clinical examination; three had died, two were lost to follow-up and four patients had undergone revision surgery. The mean follow-up time was 4.7 years (1.1 to 13.25), with an infection-free survival of 94%. The organisms most commonly isolated intra-operatively were Staphylococcus epidermidis and Propionibacterium acnes; two patients developed a recurrent infection. Three different types of prosthesis were used: a hemiarthroplasty, a hemiarthroplasty with a bipolar head and reverse prosthesis. The mean Constant-Murley score at final follow-up was 43.3 (14 to 90) for patients with a hemiarthroplasty, 56 (40 to 88) for those with a hemiarthroplasty with a bipolar head and 61 (7 to 90) for those with a reverse prosthesis. The mean hospital stay was 10.6 days (5 to 29). Single-stage exchange is a successful and practical treatment for patients with peri-prosthetic infection of the shoulder.

[Revised consensus classification. Histopathological classification of diseases associated with joint endoprostheses]. / Erweiterte Konsensusklassifikation. Histopathologische Klassifikation von Gelenkendoprothesen-assoziierten Erkrankungen.

The revised classification of the periprosthetic membrane (synovial-like interface membrane SLIM) encompasses all pathological alterations which can occur as a result of endoprosthetic replacement of major joints and lead to a reduction in durability of prostheses. This also includes the established consensus classification of SLIM by which aseptic and septic prosthetic loosening can be subdivided into four histological types and histopathological criteria for additional pathologies: endoprosthesis-associated arthrofibrosis, immunological/allergic alterations and osseous pathologies. This revision represents the foundation for the histopathological diagnostics of the total spectrum of diseases associated with joint prostheses, is a suitable basis for a standardized diagnostic procedure and etiological clarification of endoprosthesis failure and also as a data standard for endprosthesis registers, in particular for registers based on routine data (e.g. German endoprosthesis register).