Basic Clinical Examination of the Foot and Ankle. / Klinische Basisuntersuchungen am Fuß und Sprunggelenk.

Successful treatment of foot and ankle diseases requires an accurate diagnosis. In addition to differentiated history taking, clinical examination is the most important component in the diagnosis of foot and ankle diseases. The present video explains the common provocation tests and functional tests that are used in the basic clinical examination of the foot and ankle complex. In addition to general inspection and palpation, the focus is on different diagnostic tests and clinical signs that improve diagnostic accuracy. The present basic clinical examination methods allow a structured approach to clinical issues and can be a good basis, if supplemented by further specific and individual tests.

Conversion of cemented revision total knee prostheses to arthrodesis using custom-made arthrodesis modules that preserve the cemented stem anchorage in patients with long-established extensor mechanism insufficiency: A case series.

INTRODUCTION: Long-established extensor mechanism insufficiency that defies reconstruction is a rare, but devastating, complication after revision total knee arthroplasty (RTKA) that may require arthrodesis. For cemented stem guided knee prostheses with firmly attached stems, prosthesis explantation can lead to significant bone stock loss that may, at worst, make knee arthrodesis significantly more difficult or impossible to achieve. Under these circumstances, conversion of the cemented knee prosthesis with custom-made arthrodesis modules that preserve the existing stem anchorage may be a low-risk alternative. This case series presents this type of conversion to arthrodesis, which was performed for patients with a non-reconstructable, long-established extensor mechanism insufficiency. METHODS: After intraoperatively ascertaining that reconstruction of the extensor mechanism insufficiency was impossible, the inlying revision prosthesis was converted into arthrodesis with custom-made arthrodesis modules, without explanting the cemented stems. RESULTS: Conversion to arthrodesis was performed in four patients. There was no histopathological or microbiological evidence of a periprosthetic joint infection. Clinical follow-up showed a low level of pain, with a stable knee joint and proper implant position. The Oxford Knee Score increased from 20.5 (95% CI 17-26) to 35.5 (95% CI 30-36) points. The visual analog scale decreased from 5.5 (95% CI 4-7) pre-operatively to 1.5 (95% CI 1-2) points at last follow-up. No implant-specific complications occurred. CONCLUSIONS: Conversion of cemented RTKA with firmly attached cemented stems, without evidence of loosening, to arthrodesis might be a surgical treatment strategy for patients with a long-established extensor mechanism insufficiency that cannot be reconstructed.

Treatment of Primary Shoulder Stiffness: Results of a Survey on Surgeon Practice Patterns in Italy.

Objectives Shoulder stiffness is a condition of restricted glenohumeral range of motion (ROM), which can arise spontaneously or as consequence of a known cause. Several treatment options are available and currently no consensus has been obtained on which treatment algorithm represents the best choice for the patient. The aim of this study was to investigate surgeon practice patterns in Italy regarding treatment of primary shoulder stiffness. Methods A literature review was performed to identify randomized controlled trials reporting results of shoulder stiffness treatment. The following controversial or critical points in the treatment of primary shoulder stiffness were identified: modalities of physical therapy; indication for oral corticosteroid; indication and frequency for injective corticosteroid; technique and site of injection; and indication, timing, and technique for surgery. A survey composed by 14 questions was created and administrated to the members of a national association specialized in orthopaedics and sports traumatology (SIGASCOT at the time of survey completion, recently renamed SIAGASCOT after the fusion of the societies SIGASCOT and SIA). Results A total of 204 completed questionnaires were collected. Physical therapy was recommended by 98% of the interviewed. The use of oral corticosteroids was considered by 51%, and injections of corticosteroids by 72%. The posterior injection approach was the one preferred and a number of three was considered the upper limit for repeated injections. Injective therapy with local anesthetics and hyaluronic acid was considered by more than 20% of the interviewed. Thirty percent of the interviewed did not treat shoulder stiffness surgically. Conclusion Several approaches to shoulder stiffness have been proposed and high-level evidence is available to analyze and discuss their results. Several controversial points emerged both from a literature review and from this national survey. Treatment of shoulder stiffness should be tailored to the patient's clinical situation and the stage of its pathology and should aim at pain reduction, ROM restoration, functional regain, and shortening of symptoms duration, with conservative therapy remaining the mainstay of treatment.

A case series of cementless revision total knee arthroplasty in patients with benzoyl peroxide allergy.

PURPOSE: The contact allergens nickel, cobalt, and chromium are often discussed as possible triggers of allergic reactions to orthopedic implants. Additionally, acrylates and polymerization additives in bone cement (e.g., benzoyl peroxide (BPO)) have been implicated as triggers of eczema, wound healing disorders, and aseptic implant loosening. We report about six patients with aseptic loosening after total knee arthroplasty (TKA), who underwent revision surgery after testing positive for BPO hypersensitivity. METHODS: After clarification of possible other causes of implant failure, epicutaneous testing had been performed and the implants were replaced in a two-stage procedure with cementless, diaphyseal anchoring, hypoallergenic (TiNb-coated) revision endoprostheses. RESULTS: Epicutaneous testing revealed a BPO allergy in all six patients and an additional nickel allergy in three of the six patients. There was no histopathological or microbiological evidence for a periprosthetic infection. The clinical follow-up showed a low level of pain with good function, a stable knee joint, and proper implant position. The Knee Society Score (KSS) with its subscales Knee Score and Functional Score improved post-operatively from 43 to 70 points and from 47.5 to 68.3 points, respectively. Two implant-specific complications occurred: femoral stress shielding two years post-operatively with no further need for action and aseptic loosening of the tibial stem with the need of revision three years post-operatively. CONCLUSIONS: The regression of complaints after replacement with cementless and nickel-free revision implants suggests allergic implant intolerance. Implantation of a cementless, hypoallergenic endoprosthesis might, therefore, be a surgical treatment strategy in patients with evidence of allergies.

Comparison of two-stage revision arthroplasty and intramedullary arthrodesis in patients with failed infected knee arthroplasty.

BACKGROUND: Failed total knee arthroplasty (TKA) with significant bone loss and compromised soft-tissues is challenging and the final results are often inferior to patient's expectation. The objective of this study was to present a comparison of outcomes in patients with failed infected TKA treated with two-stage revision TKA or knee arthrodesis and to assess clinical and functional results, implant survival and infection recurrence. The hypothesis was that an arthrodesis may result in beneficial effects on patients' outcome. METHODS: Clinical data of 81 patients with periprosthetic joint infection (PJI) of the knee joint were collected and analyzed retrospectively. Between 2008 and 2014, a total of 36 patients had been treated within a two-stage exchange procedure and reimplantation of a modular intramedullary arthodesis nail and 45 patients with revision TKA. Patients were treated according to the same structured treatment algorithm. Clinical and functional evaluation was performed using the Oxford knee score (OKS) and the visual analogue scale (VAS). RESULTS: The mean follow-up was 32.9 ± 14.0 months. The rate of definitely free of infection at last follow-up in the arthrodesis group was 32 of 36 (88.9%) and 36 of 45 (80.0%) in the revision TKA group (p = 0.272). Mean VAS for pain in the arthrodesis group was 3.1 ± 1.4 compared to 3.2 ± 1.6 in the revision TKA group (p = 0.636). The OKS in the arthrodesis group was 38.7 ± 8.9 and 36.5 ± 8.9 (p = 0.246) in patients with revision TKA. Rate of revisions in the revision-TKA group was 2.8 ± 3.7 compared to 1.2 ± 2.4 in the arthrodesis group (p = 0.021). CONCLUSION: Treatment of PJI needs a distinct therapy with possible fallback strategies in case of failure. A knee arthrodesis is a limb salvage procedure that showed no significant benefits on the considered outcome factors compared to revision TKA but is associated with significantly lower revision rate. After exhausted treatment modalities, a knee arthrodesis should be considered as an option in selected patients. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

[Basic Clinical Examination of the Knee Joint]. / Klinische Basisuntersuchung des Kniegelenkes.

OBJECTIVE: Successful treatment of knee joint disease requires an accurate diagnosis. In addition to a differentiated history, clinical examination is the most important component in the diagnosis of knee joint diseases. METHOD: The present video explains the common provocation and functional tests that are used in the basic clinical examination of the knee joint. In addition to general inspection and palpation, the focus here is on the individual region's patella, menisci, cruciate ligaments and collateral ligaments. CONCLUSION: The present methods of basic clinical examination allow a structured approach to clinical issues and can be a good basis for the diagnosis of knee joint diseases, if supplemented by further specific and individual tests.

Two-stage knee arthrodesis with a modular intramedullary nail due to septic failure of revision total knee arthroplasty with extensor mechanism deficiency.

BACKGROUND: Periprosthetic joint infection is a serious complication and reconstruction after failed revision total knee arthroplasty with significant bone loss and compromised soft-tissues can be challenging. Objective of this study was to assess clinical and functional results, implant survival and infection recurrence rates in patients treated with two-stage arthrodesis after failed revision TKA with extensor mechanism deficiencies due to PJI, and to identify the factors that affect outcomes after surgery. METHODS: Thirty seven patients with PJI treated within a two-stage exchange and reimplantation of an arthrodesis nail between 2008 and 2014 were included. Systemic and local risk factors were graded preoperatively according to McPherson et al. All patients were treated according to a structured treatment algorithm. Clinical and functional evaluation was performed using the Oxford Knee Score and the Visual Analogue Scale. RESULTS: Thirty two of 37 patients (86.5%) were graded as free of infection. Five patients (13.5%) had recurrent infection after arthrodesis with the need of revision surgery. Mean leg-length discrepancy was 2.2cm. The mean VAS for pain was three, the mean Oxford Knee Score was 38±9. Total implant survival at a 74month follow-up was 74.3% (95% CI: 45.4 to 91.1%), as determined by Kaplan-Meier survival curves. Local McPherson Score, as well as number of revisions was found to be of significant influence to the survival rate. CONCLUSIONS: Septic failure of revision knee arthroplasty can be effectively treated with two-stage arthrodesis using a modular intramedullary nail, providing a stable and painless limb with satisfactory functional results and acceptable infection eradication rates.

RANK-ligand and osteoprotegerin as biomarkers in the differentiation between periprosthetic joint infection and aseptic prosthesis loosening.

AIM: To assess serum levels of RANK-ligand (RANKL) and osteoprotegerin (OPG) as biomarkers for periprosthetic joint infection (PJI) and compare their accuracy with standard tests. METHODS: One hundred and twenty patients presenting with a painful total knee or hip arthroplasty with indication for surgical revision were included in this prospective clinical trial. Based on standard diagnostics (joint aspirate, microbiological, and histological samples) and Musculoskeletal Infection Society consensus classification, patients were categorized into PJI, aseptic loosening, and control groups. Implant loosening was assessed radiographically and intraoperatively. Preoperative serum samples were collected and analyzed for RANKL, OPG, calcium, phosphate, alkaline phosphatase (AP), and the bone-specific subform of AP (bAP). Statistical analysis was carried out, testing for significant differences between the three groups and between stable and loose implants. RESULTS: All three groups were identical in regards to age, gender, and joint distribution. No statistically significant differences in the serum concentration of RANKL (P = 0.16) and OPG (P = 0.45) were found between aseptic loosening and PJI, with a trend towards lower RANKL concentrations and higher OPG concentrations in the PJI group. The RANKL/OPG ratio was significant for the comparison between PJI and non-PJI (P = 0.005). A ratio > 60 ruled out PJI in all cases (specificity: 100%, 95%CI: 89, 11% to 100.0%) but only 30% of non-PJI patients crossed this threshold. The positive predictive value remained poor at any cut-off. In the differentiation between stable and loose implants, none of the parameters measured (calcium, phosphate, AP, and bAP) showed a significant difference, and only AP and bAP measurements showed a tendency towards higher values in the loosened group (with P = 0.09 for AP and P = 0.19 for bAP). CONCLUSION: Lower RANKL and higher OPG concentrations could be detected in PJI, without statistical significance.

Pre-operative intra-articular deep tissue sampling with novel retrograde forceps improves the diagnostics in periprosthetic joint infection.

BACKGROUND: Histopathological tissue analysis is a key parameter within the diagnostic algorithm for suspected periprosthetic joint infections (PJIs), conventionally acquired in open surgery. In 2014, Hügle and co-workers introduced novel retrograde forceps for retrograde synovial biopsy with simultaneous fluid aspiration of the knee joint. We hypothesised that tissue samples acquired by retrograde synovial biopsy are equal to intra-operatively acquired deep representative tissue samples regarding bacterial detection and differentiation of periprosthetic infectious membranes. METHOD: Thirty patients (male n = 15, 50%; female n = 15, 50%) with 30 suspected PJIs in painful total hip arthroplasties (THAs) were included in this prospective, controlled, non-blinded trial. The results were compared with intra-operatively obtained representative deep tissue samples. RESULTS: In summary, 27 out of 30 patients were diagnosed correctly as infected (17/17) or non-infected (10/13). The sensitivity to predict a PJI using the Retroforce® sampling forceps in addition to standard diagnostics was 85%, the specificity 100%. CONCLUSIONS: Retrograde synovial biopsy is a new and rapid diagnostic procedure under local anaesthesia in patients with painful THAs with similar histological results compared to deep tissue sampling.

Outcome Predictors in Prosthetic Joint Infections--Validation of a risk stratification score for Prosthetic Joint Infections in 120 cases.

Prosthetic joint infections are a major challenge in total joint arthroplasty, especially in times of accumulating drug resistancies. Even though predictive risk classifications are a widely accepted tool to define a suitable treatment protocol a classification is still missing considering the difficulty in treating the -causative pathogen antibiotically. In this study, we present and evaluate a new predictive risk stratification for prosthetic joint infections in 120 cases, treated with a two-stage exchange. Treatment outcomes in 120 patients with proven prosthetic joint infections in hip and knee prostheses were regressed on time of infection, systemic risk factors, local risk factors and the difficulty in treating the causing pathogen. The main outcome variable was "definitely free of infection" after two years as published. Age, gender, and BMI were included as covariables and analyzed in a logistic regression model. 66 male and 54 female patients, with a mean age at surgery of 68.3 years±12.0 and a mean BMI of 26.05±6.21 were included in our survey and followed for 29.0±11.3 months. We found a significant association (p<0.001) between our score and the outcome parameters evaluated. Age, gender and BMI did not show a significant association with the outcome. These results show that our score is an independent and reliable predictor for the cure rate in prosthetic joint infections in hip and knee prostheses treated within a two-stage exchange protocol. Our score illustrates, that there is a statistically significant, sizable decrease in cure rate with an increase in score. In patients with prosthetic joint infections the validation of a risk score may help to identify patients with local and systemic risk factors or with infectious organisms identified as "difficult to treat" prior to the treatment or the decision about the treatment concept. Thus, appropriate extra care should be considered and provided.

Outcomes of a Modular Intercalary Endoprosthesis as Treatment for Segmental Defects of the Femur, Tibia, and Humerus.

BACKGROUND: Resection of diaphyseal bone tumors for local tumor control and stabilization often results in an intercalary skeletal defect and presents a reconstructive challenge for orthopaedic surgeons. Although many options for reconstruction have been described, relatively few studies report on the functional outcomes and complications of patients treated with modular intercalary endoprostheses. QUESTIONS/PURPOSES: The objectives of this study were to examine clinical outcomes after reconstruction with a modular intercalary endoprosthesis with a specific focus on (1) the rate of complication or failure; (2) differences in complication rates by anatomic site; (3) functional results as assessed by the Musculoskeletal Tumor Society System (MSTS); and (4) differences in complication rate between patients treated with cemented versus noncemented fixation. METHODS: We conducted a retrospective chart review of patients treated with a modular intercalary endoprosthesis from three musculoskeletal oncology centers from 2008 to 2013. The indication for use of this intercalary endoprosthesis was segmental bone loss from aggressive or malignant tumor with sparing of the joint above and below and deemed unsuitable for biologic reconstruction. No other implant was used for this indication during this period. During this period, 41 patients received a total of 44 intercalary implants, which included 18 (40%) humeri, 5 (11%) tibiae, and 21 (48%) femora. There were 27 (66%) men and 14 (34%) women with a mean age of 63 years (range, 18­91 years). Eight patients (20%) had primary bone tumors and 33 (80%) had metastatic lesions. Thirty-five (85%) patients were being operated on as an initial treatment and six (15%) for revision of a previous reconstruction. Twenty-nine (66%) procedures had cemented stem fixation and 15 (34%) were treated with noncemented fixation. The overall mean followup was 14 months (range, 1­51 months). Patients with primary tumors had a mean followup of 19 months (range, 4­48 months) and patients with metastatic disease had a mean followup of 11 months (range, 1­51 months). Causes of implant failure were categorized according to Henderson et al. [19] into five types as follows: Type I (soft tissue failure), Type II (aseptic loosening), Type III (structural failure), Type IV (infection), and Type V (tumor progression). At 2 years of followup, 38 (93%) of these patients were accounted for with three (7%) lost to followup. MSTS functional assessment was available for 39 of 41 patients (95%). RESULTS: At latest followup of these 41 patients, 14 (34%) patients were dead of disease, two patients (5%) dead of other causes, seven (17%) are continuously disease-free, one (2%) shows no evidence of disease, and 17 (41%) are alive with disease. There were 12 (27%) nononcologic complications. Five (11%) of these were Type II failures occurring in noncemented implants between the stem and bone, and six (14%) were Type III failures occurring in cemented implants at the clamp-rod implant interface. One patient developed a deep infection (2%, Type IV failure) and underwent removal of the implant. Additionally, one patient (2%, Type V failure) was treated by amputation after local progression of his metastatic disease. Complications were more common in femoral reconstructions than in tibial or humeral reconstructions. Twelve of 21 patients (57%) with femoral reconstructions had complications versus 0% of tibial or humeral reconstructions (0 of 23; odds ratio [OR], 62; 95% confidence interval [CI], 3­1154; p < 0.0001). The mean overall MSTS score was 77%. Implants with cemented fixation (29) had higher mean MSTS scores when compared with implants with noncemented (15) fixation (84% versus 66%, p = 0.0017). The complication rate was 33% in noncemented cases and 21% in cemented cases (p = 0.39); however, Type II failure at the bone-stem interface was associated with noncemented fixation and Type III failure at the clamp-rod interface was associated with cemented fixation (OR, 143; 95% CI, 2.413­8476; p = 0.0022). CONCLUSIONS: The results of this study indicate that this modular intercalary endoprosthesis yields equivalent results to other studies of intercalary endoprostheses in terms of MSTS scores. We found that patients treated with intercalary endoprostheses in the femur experienced more frequent complications than those treated for lesions in either the humerus or tibia and that the femoral complication rate of this endoprosthesis is higher when compared with other studies of intercalary endoprostheses for femoral reconstruction. Further studies are still needed to determine the long-term outcomes of this endoprosthesis in patients with primary tumors where longevity of the implant is of more importance than in the metastatic setting. We recommend cemented fixation for this intercalary modular endoprostheses because this provides improved MSTS scores and allows immediate return to weightbearing, which is of advantage to metastatic patients with limited lifespans. Level of Evidence: Level III, therapeutic study.

Polymicrobial infections reduce the cure rate in prosthetic joint infections: outcome analysis with two-stage exchange and follow-up ≥two years.

PURPOSE: Prosthetic joint infections (PJI) are a serious and challenging complication after total joint arthroplasty. According to the literature, most PJI are monomicrobial infections caused by gram-positive cocci. The number of polymicrobial PJI might be underrepresented in the literature and only limited data are available regarding the outcome of polymicrobial PJI. Our hypothesis was that polymicrobial PJI are associated with a reduced cure rate compared with monomicrobial PJI. METHODS: Routine clinical data were collected and analysed retrospectively as anonymised, aggregated data. A total of 77 consecutive patients with 77 confirmed PJI and proven infectious organism of the hip and knee joint treated within a two-stage exchange concept and a follow-up ≥ two years were investigated. Detection of the infectious organism was based on multiple microbiological cultures taken intra-operatively. Superficial wound swabs or swabs from sinus tracts were not taken into account. Data were grouped into polymicrobial and monomicrobial PJI. The main outcome variable was "definitively free of infection after two years" as published. Second, we considered several variables as potential confounders or as risk factors. RESULTS: A total of 42 men and 35 women with 46 infected total hip arthroplasties and 31 infected total knee arthroplasties were evaluated. In 37 (46.6 %) of our 77 patients a polymicrobial PJI could be detected. We found a significant association between polymicrobial PJI and the outcome parameter definitively free of infection after two years with an odds ratio (OR) of 0.3 [95 % confidence interval (CI) 0.1-1.0]. The rate of patients graded as definitively free of infection after two years was 67.6 % for polymicrobial infections vs. 87.5 % for monomicrobial infections. The American Society of Anesthesiologists (ASA) score (OR 0.4, 95 % CI 0.2-1.0, p = 0.062) was identified as a borderline significant covariable. CONCLUSIONS: Our data suggest that polymicrobial PJI might be underrepresented in the current literature. Additionally, the presence of multiple infectious organisms is associated with a reduced rate after two years with 67.6 vs 87.5 % for monomicrobial infections. Special attention and extra care should be considered for these patients.

Validation of the Charlson comorbidity index in patients undergoing revision total hip arthroplasty.

PURPOSE: The Charlson comorbidity index (CCI) was developed to quantify the influence of comorbidities on survival. The age-related CCI respects patients' age as an additional risk factor. There are several studies available based on administrative data regarding functional outcome, implant survival, resource use and length of hospital stay in patients undergoing primary total hip arthroplasty (THA). To date, there is a lack of knowledge regarding the correlation of the CCI and the age-related CCI in case of revision total hip arthroplasty (RTHA). OBJECTIVE: Our objective was to validate the influence of the CCI and age-related CCI in patients undergoing RTHA regarding complication rate, resource use implant survival and mortality rate. METHODS: Between October 2007 and November 2012, 142 consecutive patients undergoing RTHA were included in this retrospective study. Routine clinical data were collected and analysed as anonymized aggregated data. In accordance to CCI and age-related CCI the rate of complications (internal medical and surgical complications), the length of hospital stay and the need for ICU treatment and the mortality rate was evaluated. Kaplan-Meier survivorship was used to determine implant survival. RESULTS: Twenty-one patients (15%) had a low risk CCI, 59 patients (41%) a moderate risk CCI and 62 patients (44%) a high risk CCI. The mean follow-up was 27 months (range 24-70 months). In total, we recorded 57 complications (40%), of which 45 were surgical (79%) and 12 were internal medical complications (21%). Twenty-four patients (17%) had to undergo revision surgery. CCI and age-related CCI had no influence regarding implant survival. We recorded a significant influence of the age-related CCI in regard to the necessity of postoperative intensive care unit stay and the length of total hospital stay. Further we recorded a significant influence of the CCI and the age-related CCI regarding postoperative complications and internal complications, postoperative dislocation and the need for surgical revision. CONCLUSION: In summary, we conclude that the CCI and the age-related CCI are strong predictors regarding complication rate in patients undergoing RTHA. In a short- to mid-term follow-up, no influence on implant survival is detectable.

Can 3D ultrasound identify trochlea dysplasia in newborns? Evaluation and applicability of a technique.

Femoro-patellar dysplasia is considered as a significant risk factor of patellar instability. Different studies suggest that the shape of the trochlea is already developed in early childhood. Therefore early identification of a dysplastic configuration might be relevant information for the treating physician. An easy applicable routine screening of the trochlea is yet not available. The purpose of this study was to establish and evaluate a screening method for femoro-patellar dysplasia using 3D ultrasound. From 2012 to 2013 we prospectively imaged 160 consecutive femoro-patellar joints in 80 newborns from the 36th to 61st gestational week that underwent a routine hip sonography (Graf). All ultrasounds were performed by a pediatric radiologist with only minimal additional time to the routine hip ultrasound. In 30° flexion of the knee, axial, coronal, and sagittal reformats were used to standardize a reconstructed axial plane through the femoral condyle and the mid-patella. The sulcus angle, the lateral-to-medial facet ratio of the trochlea and the shape of the patella (Wiberg Classification) were evaluated. In all examinations reconstruction of the standardized axial plane was achieved, the mean trochlea angle was 149.1° (SD 4.9°), the lateral-to-medial facet ratio of the trochlea ratio was 1.3 (SD 0.22), and a Wiberg type I patella was found in 95% of the newborn. No statistical difference was detected between boys and girls. Using standardized reconstructions of the axial plane allows measurements to be made with lower operator dependency and higher accuracy in a short time. Therefore 3D ultrasound is an easy applicable and powerful tool to identify trochlea dysplasia in newborns and might be used for screening for trochlea dysplasia.

Acetabular defect reconstruction in revision hip arthroplasty with a modular revision system and biological defect augmentation.

PURPOSE: Revision of failed total hip arthroplasty with severe acetabular bone loss represents a rare but challenging problem. Anatomic reconstruction with biological defect augmentation as solid bone transplants or cancellous bone restores bone stock while providing good component stability. The objective of this study was to present short- to mid-term results of revision total hip arthroplasty with a modular ring system in a consecutive series of patients with severe acetabular bone loss. METHODS: We retrospectively reviewed 39 consecutive patients (39 hips) with severe acetabular bone loss (Paprosky type 3 A and 3 B) reconstructed with revision total hip arthroplasty using the cementless modular ring system MRS-Titan®. The MRS-Titan® consists of independent ring systems that are adapted modularly to the defect situation. Combined with acetabular defect reconstruction by using cancellous bone in impaction grafting technique, the MRS-Titan® system offers a cement-free revision system that enables defect-adapted customization to individual anatomic matters, bridging of the acetabular bone defect and reconstruction of the centre of rotation. Initial stability of the implant was obtained by screw fixation. Harris hip score and sequential radiographs were used to evaluate clinical and radiographic results. RESULTS: At an average follow up of 31 months (range 12-69 months) 33 of 39 (84.6 %) of the implants were considered radiographically stable without signs of acetabular migration of more than 2 mm in the horizontal or vertical direction, implant rotation or screw breakage. Complications included six implant failures (15 %). We recorded one aseptic loosening of the MRS prosthesis after 20 months. Five patients (12.8 %) had to undergo revision surgery because of periprosthetic joint infection. Two patients had a dislocation postoperatively. The mean Harris hip score improved from 27 ± 14 points preoperatively to 76 ± 15 points at the time of last follow up. CONCLUSION: By achieving stable implant fixation and providing potential for biological fixation, treatment of severe acetabular bone loss in revision total hip arthroplasty with the modular ring system MRS-Titan provides a durable solution with good clinical and radiographic results and allows us to accomplish major goals of reconstruction.

Investigation of neutrophilic peptides in periprosthetic tissue by matrix-assisted laser desorption ionisation time-of-flight imaging mass spectrometry.

PURPOSE: The accurate diagnosis of periprosthetic joint infection (PJI) relies on clinical investigation, laboratory parameters, radiological methods, sterile joint aspiration for synovial fluid leucocyte count and microbiological analysis and tissue sampling for histopathology. Due to the limits in specificity and sensitivity of these methods, molecular techniques and new biomarkers were introduced into the diagnostic procedure. Histological examination is related to the amount of neutrophils in the periprosthetic tissue in frozen sections and formalin-fixed paraffin embedded material (FFPE). However, the threshold of neutrophils per defined area of tissue among various studies is very inconsistent. METHODS: We have applied matrix-assisted laser desorption ionisation time-of-flight imaging mass spectrometry (MALDI IMS) to a total of 32 periprosthetic tissue samples of patients with PJI to detect peptides associated with areas of neutrophil infiltration. RESULTS: Specific peaks associated with a high amount of neutrophils were detected. Of these m/z peaks, four could be assigned to predictive neutrophil molecules. These peptides include annexin A1, calgizzarin (S100A11), calgranulin C (S100A12) and histone H2A. By MALDI IMS, these peptides could be shown to be co-localised with the infiltration of neutrophils in the immediate vicinity of the periprosthetic interface, whereas more distant areas did not show neutrophil invasion or infection-related peptides. CONCLUSIONS: MALDI IMS is a new method allowing identification of neutrophil peptides in periprosthetic tissues and may be a surrogate for counting neutrophils as an objective parameter for PJI.

Management of severe periacetabular bone loss combined with pelvic discontinuity in revision hip arthroplasty.

PURPOSE: Revision of failed total hip arthroplasty with massive acetabular bone loss resulting in pelvic discontinuity represents a rare but challenging problem. The objective of this study was to present short to mid-term results of revision total hip arthroplasty with a custom-made acetabular implant in a consecutive series of patients with pelvic discontinuity. METHODS: We retrospectively reviewed 18 consecutive patients with massive acetabular bone loss (Paprosky Type 3B) resulting in pelvic discontinuity reconstructed with revision total hip arthroplasty using a custom-made acetabular component. The prosthesis was created on the basis of a thin-cut 1-mm computed tomography (CT) scan of the pelvis. Initial stability of the implant was obtained by screw fixation. Harris hip score and sequential radiographs were used to evaluate the clinical and radiographic results. RESULTS: At an average follow up of 30 months (range 17-62 months) 16 of 18 (88.9%) custom-made implants were considered radiographically stable without signs of acetabular migration of more than 2 mm in the horizontal or vertical direction, implant rotation or screw breakage. Complications included two periprosthetic joint infections treated with explantation of the implant. Three patients had recurrent dislocations postoperatively. The mean Harris hip score improved from 28 ± 12 points preoperatively to 69 ± 13 points at the time of last follow up. CONCLUSION: Treatment of acetabular bone loss and pelvic discontinuity with a custom-made acetabular component can provide a durable solution with good clinical and radiographic results.

Lipopolysaccharide-binding protein: a valuable biomarker in the differentiation between periprosthetic joint infection and aseptic loosening?

PURPOSE: The pre-operative differentiation between periprosthetic joint infection (PJI) and aseptic loosening after total hip (THA) or knee (TKA) arthroplasty is essential for successful therapy and relies in part on the use of molecular markers. The objective of this study was to assess serum levels of lipopolysaccharide-binding protein (LBP) as a diagnostic tool for PJI and to compare its accuracy with standard tests. METHODS: One hundred and twenty patients presenting with a painful TKA or TKA with indication for surgical revision were included in this prospective, controlled, clinical trial at a single centre. Pre-operative blood and serum samples were collected and analysed for white blood cell (WBC) count, C-reactive protein (CRP) and LBP. The definite diagnosis of periprosthetic joint infection was determined on the basis of clinical, microbiological and histopathological examination. RESULTS: LBP showed significantly higher values in PJI compared with aseptic loosening (p < 0.001) and control (p < 0.001), with a specificity of 66% and a sensitivity of 71% at a cutoff value of >7 ng/ml. In combination with CRP, the positive predictive value for PJI was at 0.67; negative predictive value with both negative was at 0.77. DISCUSSION: Patients with PJI have elevated serum levels of LBP when compared with patients with aseptic loosening. The use of LBP in serum appears not to be a more accurate marker than CRP level in serum for detecting PJI. On the basis of these results, we cannot recommend the sole use of LBP for differentiating PJI and aseptic loosening following THA and TKA.

Evidence of MRSE on a gentamicin and vancomycin impregnated polymethyl-methacrylate (PMMA) bone cement spacer after two-stage exchange arthroplasty due to periprosthetic joint infection of the knee.

BACKGROUND: Periprosthetic joint infections (PJI) are often treated by two stage exchange with the use of an antibiotic impregnated spacer. Most of the two-stage exchange algorithms recommend the implantation of an antibiotic-impregnated spacer during the first stage for a period of 2-24 weeks before reimplantation of the new prosthesis. For the spacer to have a therapeutic effect, the local antibiotic concentration must be greater than the minimal inhibition concentration (MIC) against the pathogens causing the PJI. It must remain so for the entire spacer period, otherwise recurrence of infection or resistances might occur. The question as to whether a sufficient concentration of antibiotics in vivo is reached for the entire spacer period has not been answered satisfactorily. CASE PRESENTATION: We here present a case of a histologically confirmed chronic PJI 20 month after primary arthroplasty. The primary knee arthroplasty was performed due to osteoarthritis of the joint. Initial assessment did not detect a causative pathogen, and two stage exchange with a vancomycin-gentamycin impregnated spacer was performed. At the time of reimplantation, sonication of the explanted spacer revealed a multi-resistant strain of staphylococcus epidermidis on the device and in the joint. Adaption of the therapy and prolonged treatment successfully eradicated the infection. CONCLUSION: According to the authors' knowledge, the case presented here confirms for the first time the surface contamination (proven through sonication) of a vancomycin-/gentamicin- impregnated Vancogenx®-spacer with a MRSE after ten weeks of implantation.This case study demonstrates the difficulties still associated with the diagnostics of PJI and the published different two stage treatment regimes with the use of antibiotic impregnated spacers.

Interleukin-6 in serum and in synovial fluid enhances the differentiation between periprosthetic joint infection and aseptic loosening.

The preoperative differentiation between septic and aseptic loosening after total hip or knee arthroplasty is essential for successful therapy and relies in part on biomarkers. The objective of this study was to assess synovial and serum levels of inflammatory proteins as diagnostic tool for periprosthetic joint infection and compare their accuracy with standard tests. 120 patients presenting with a painful knee or hip endoprosthesis for surgical revision were included in this prospective trial. Blood samples and samples of intraoperatively acquired joint fluid aspirate were collected. White blood cell count, C-reactive protein, procalcitonin and interleukin-6 were determined. The joint aspirate was analyzed for total leukocyte count and IL-6. The definite diagnosis of PJI was determined on the basis of purulent synovial fluid, histopathology and microbiology. IL-6 in serum showed significantly higher values in the PJI group as compared to aseptic loosening and control, with specificity at 58.3% and a sensitivity of 79.5% at a cut-off value of 2.6 pg/ml. With a cut-off >6.6 pg/ml, the specificity increased to 88.3%. IL-6 in joint aspirate had, at a cut-off of >2100 pg/ml, a specificity of 85.7% and sensitivity of 59.4%. At levels >9000 pg/ml, specificity was almost at 100% with sensitivity just below 50%, so PJI could be considered proven with IL-6 levels above this threshold. Our data supports the published results on IL-6 as a biomarker in PJI. In our large prospective cohort of revision arthroplasty patients, the use of IL-6 in synovial fluid appears to be a more accurate marker than either the white blood cell count or the C-reactive protein level in serum for the detection of periprosthetic joint infection. On the basis of the results we recommend the use of the synovial fluid biomarker IL-6 for the diagnosis of periprosthetic joint infection following total hip and knee arthroplasty.