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Burkhard Moellenbeck, 1 Tobias Kalisch, 1 Georg Gosheger, 1 Frank Horst, 2 Leonie Seeber, 1 Christoph Theil, 1 Tom Schmidt-Braekling, 1 Ralf Dieckmann 1 1Department of General Orthopedics and Tumor Orthopedics, Muenster University Hospital, Muenster, Germany; 2Department of Orthopedics and Traumatology, St. Josef-Stift Sendenhorst, Sendenhorst, GermanyCorrespondence: Burkhard MoellenbeckDepartment of General Orthopedics and Tumor Orthopedics, Münster University Hospital, Albert-Schweitzer-Campus 1, Building A1, Münster 48149, GermanyTel +49 251 83-45539Fax +49 251 83-47989Email Burkhard.Moellenbeck@ukmuenster.dePurpose: The present study investigates behavioral conformity regarding physical activity (PA) and sedentary behavior (SB) in older couples where one partner suffers from osteoarthritis (OA). Hereby the question is addressed whether and to what extent the typical physical limitations of OA patients have negative effects on their partners.Patients and Methods: The habitual PA and SB of end-stage osteoarthritis patients (n = 32, 52– 81 years | n = 14 gonarthrosis, n = 18 coxarthrosis), their spouses (n = 32, 50– 83 years) and control couples (n = 26 subjects, 52– 78 years) were assessed by accelerometry. Besides individual results of accelerometry hourly couple-specific performance ratios were calculated for four parameters of PA (number of steps, vector magnitude (VM), metabolic rate (MET), and total time in moderate-to-vigorous PA (MVPA)) and two parameters of SB (number of sedentary bouts and total time of sedentary bouts per hour). Analyses of covariance were used to explore differences in hourly couple-specific performance ratios between couples affected by osteoarthritis and control couples.Results: Significant differences in PA were observed between the three groups, whereby the patients showed the lowest PA and the subjects of the control group the highest PA. In contrast to this, SB did not differ between the three groups. The hourly analyses of couple-specific performance ratios revealed significant differences between the target couples (patients and spouses) and the control couples for all parameters of PA. Thereby, the deviance in PA between the patients and their spouses was always smaller than in control couples and also decreased with age. The investigation of SB, on the other hand, revealed larger deviations between the patients and their spouses as compared to control couples and no changes with age.Conclusion: This study confirmed the known negative impact of osteoarthritis on the PA and SB of elderly patients. More important, however, was the finding that the patients’ spouses adapt to this poor health behavior and show reduced PA as well. Consequentially, spouses of OA patients should be considered as a risk group for inactivity-related diseases in old age. This should be considered in interventions that aim to use the individual support of spouses to increase the PA of OA patients.Keywords: older couples, osteoarthritis, inactivity, synchrony, accelerometer

Purpose: Anemia has been shown to be a modifiable pre-operative, patient factor associated with outcome following arthroplasty. The aims of this retrospective study were to (1) ascertain the prevalence of preoperative anemia in patients undergoing primary and revision hip and knee arthroplasty at a tertiary referral center and (2) to test the association with outcome and whether it differs between primary and revision cases., Methods: All hip and knee primary and revision arthroplasties performed at a Canadian academic, tertiary-care, arthroplasty center between 2012 and 2017 were included in this study. The study group consisted of 5944 patients, of which 5251 were primary Total Hip and Knee Arthroplasties or Hip Resurfacings and 693 were revision arthroplasties (65% hip revisions/35% knee revisions). Anemia was classified as per WHO definition (hemoglobin < 130 g/L for men and < 120 g/L for women). All anemic patients were grouped into mild, moderate or severe anemia. Length-of-stay, perioperative transfusion-rate, 90-day readmission, overall complication rate and reoperation rates were recorded. The effect of preoperative anemia and the effect of severity of the anemia was evaluated through multivariable regression analysis controlling for relevant covariates., Results: Preoperatively, 15% (786/5251) of the primary patients and 47% (322/693) of the revision arthroplasty patients were anemic preoperatively. Anemic revision patients were 3.1 times more likely (95% CI: 1.47-6.33) to obtain blood transfusions during the hospital stay, compared to a 4.9 times higher risk in primary patients. The odds ratio to sustain any postoperative complication if anemic was 1.5 times higher (95% CI: 0.73-3.16) in revision patients and 1.7 in primary cases. In addition, the 90-day readmission rate among both groups was 1.6 times higher in anemic patients. Furthermore, anemic revision patients had a 5.3 days longer length of stay (95% CI: 2.63-7.91), compared to only 1 additional day in anemic primary patients (95% CI: 0.69-1.34)., Conclusion: In this study cohort, the prevalence of anemia in patients awaiting revision arthroplasty was 3 times higher (46.6%) than in primary arthroplasty patients (18.7%). Preoperative anemia was associated with similarly, inferior outcomes in both groups. To reduce postoperative complications and the "burden" associated with anemia, these findings strongly recommend optimizing the preoperative hemoglobin in all arthroplasty patients. However, revision patients are affected more frequently, and particular attention must therefore be taken to this growing group in the future., Level of Evidence: Level III., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: The most common approaches in total hip arthroplasty (THA) have different complication profiles; anterior-approach (AA-THA) has an increased risk of periprosthetic fractures (PPF); posterior-approach (PA-THA) is associated with higher dislocation risk. However, the relative severity of one versus the other is unknown. This study aims to compare outcome of patients who suffered PPF after AA-THA with those that sustained dislocation after PA-THA., Methods: This is a retrospective, single-center, multi-surgeon, consecutive case-series of primary THA patients. In a cohort of 9867 patients who underwent THA, 79 fulfilled the approach-specific, post-operative complication criteria, of which 44 were PPF after AA-THA and 35 with dislocation after PA-THA (age 67.9 years (range: 38.0-88.1), 58.2% women). Outcome included complication- and revision- rates, and patient-reported outcomes including Oxford Hip Score (OHS)., Results: At 5.8 years follow-up (range: 2.0-18.5), reoperation was more common in the dislocation after PA-THA group (23/35 vs. 20/44; p = 0.072). Change of surgical approach occurred in 15/20 of patients with PPF after AA-THA, but none in those with dislocation after PA-THA. Following re-operation, complication rate was greater in the PPF group (9/20 vs. 4/23; p = 0.049). At latest follow-up, OHS were superior in the PPF after AA-THA group [42.6 (range: 25.0-48.0) vs. 36.6 (range: 21.0-47.0); p = 0.006]., Conclusion: Dislocation following PA-THA is more likely to require revision. However, PPF following AA-THA requires more often a different surgical approach and is at higher risk of complications. Despite the increased surgical burden post-operative PROMs are better in the peri-prosthetic fracture group, especially in cases not requiring reoperation., Level of Evidence: III, case-control study., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: The presence of lumbar spine arthrodesis (SA) is associated with abnormal spinopelvic characteristics and inferior outcome post total hip arthroplasty (THA). However, whether patients with upper segment SA are also at increased risk of complications is unknown. This study aims to (1) determine if upper segment SA is associated with inferior THA outcomes; (2) assess spino-pelvic characteristics; and (3) test whether static or dynamic spinopelvic characteristics correlate with outcome post-THA., Materials and Methods: In this retrospective, case-matched, cohort study from a tertiary referral centre, 40 patients (59 hips) that had undergone both THA and any level of spinal arthrodesis (49 THA-Lumb and 10 THA-Cerv) were compared with 41 patients (59 hips) who had THA-only without known spinal pathology. Spino-pelvic characteristics [including severity of Degenerative-Disc-Disease (DDD); spinal balance and stiffness] and outcome, including patient reported outcome measures (PROMs), at minimum of 1-year post-THA were assessed., Results: THA-Lumb and THA-Cerv groups had greater number of complications and inferior hip and spinal PROMs compared to THA-Only (p < 0.001). Similar spinopelvic characteristics were seen between the THA-Cerv and THA-Lumb, which were significantly different to the THA-only group. The presence of DDD and unbalanced or stiff spine was associated with increased dislocation and inferior PROMs in the whole cohort., Conclusions: THA in the presence of SA, regardless of level, is associated with inferior outcomes and an increased risk for dislocation. The presence of a SA is associated with increased risk of adverse spinopelvic characteristics. Such characteristics were strongly associated with increased dislocation-risk and inferior PROMs. It is likely that these adverse characteristics are the most important adverse predictor, rather than segment of SA per se., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: Dislocation in Total hip arthroplasty (THA) is a common postoperative complication and reason for revision surgery. The direct anterior approach has become more popular over the last decade. The purpose of this study was to compare postoperative dislocation rates of the direct anterior and the posterior approach at a one-year follow-up., Material and Methods: 797 consecutive hips operated through a posterior approach [698 patients (307 male, 391 female)] between 2009 and 2012, were compared to 690 selected THA [610 patients (423 female, 187 male)] operated since 2012. Anterior hip replacement surgery was primarily indicated for patients demanding increased flexibility after surgery (Yoga) or were considered a higher risk for dislocation., Results: During a one-year follow-up there were eight dislocations out of 797 THA (1%) in the posterior group and none in the 690 THA (0%) in the anterior group (p-value of 0.008). Average time to dislocation was 7.5 weeks in the posterior group. Five of eight patients with dislocations needed revision surgery due to persistent instability., Conclusion: Even in a higher-risk patient population, the direct anterior approach showed a lower dislocation rate compared to the posterior approach in the first year after surgery., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The preoperative detection of prosthetic joint infection (PJI) prior to revision of total hip or knee arthroplasty is still a challenge. Serum Calprotectin (CP) is a heterodimer of two calcium-binding proteins present in the cytoplasm of neutrophils that is released in inflammatory processes and infections. The objective of this study is to determine the reliability of serum CP in the diagnosis of chronic PJI. 81 patients (40 women, 41 men) that presented a potential indication for revision arthroplasty of the hip (THA; n = 18) or knee (TKA, n = 63) at a single institution were prospectively evaluated. The joints were diagnosed as chronically infected or aseptic based on the musculoskeletal infection society (MSIS) criteria of 2018. Receiver operating characteristics and the Youden's index were used to define an ideal cutoff value. The median serum CP level was significantly higher in the group with chronic PJI (15,120 vs. 4980 ng/ml; p < 0.001) compared to the aseptic cases. The calculated optimal cut-off value was 9910 ng/ml (AUC 0.899, 95% CI 0.830-0.968) with a specificity of 91% and sensitivity of 81%. The present investigation suggests that serum CP has a high specificity and good sensitivity to diagnose chronic PJI after TJA of the knee or hip., (© 2022. The Author(s).)

Background: Dislocation following total hip arthroplasty (THA) is a significant complication that occurs in 0.3%-10% of cases with 13%-42% of patients requiring revision surgery. The literature has primarily focused on the dislocation risk associated with different surgical approaches. However, little is known about the natural history of the dislocated hip and whether surgical approach of the index THA is associated with further instability and revision surgery., Methods: This is a retrospective, single-center, multi-surgeon consecutive case series of all patients who experienced THA dislocation from 2002 to 2020. Patients were excluded if the initial dislocation was secondary to infection or fracture. The natural history of the cohort as per approach was determined. Outcome measurements of interest were the number of dislocations; the treatment surrounding each dislocation; the necessity and type of revision; and the complications encountered., Results: Of the 75 patients, 58 (77%) dislocated within 6 months following primary THA. The anterior group had greater odds of dislocation within 2 weeks post-THA compared to the lateral and posterior groups (P = .04). The mean number of dislocations per patient was significantly lower in the anterior (1.5 ± 0.7) compared to the lateral (2.4 ± 1.2) and posterior (2.1 ± 1.0) groups (P = .02). Revision surgery was needed in 30% (6/20) of patients in the anterior, 69% (25/36) of the posterior, and 68% (13/19) of the lateral groups (P = .01)., Conclusion: This study illustrates that while primary THA dislocations happen earlier with the anterior approach, they are typically less complicated and have a lower risk of recurrent instability and revision surgery., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: Megaprosthetic distal femoral reconstruction (DFR) is a limb-salvage procedure to address bone loss following two-stage revision for periprosthetic knee joint infection (PJI). The purpose of this study was to analyze the survival of DFR compared to hinged total knee arthroplasty (TKA). It was hypothesized that DFR was associated with a poorer survival., Methods: In this retrospective single-center study, 97 subjects who underwent two-stage revision of chronic knee PJI were included. Among these, 41 were DFR. The diagnosis of PJI was established using the Musculoskeletal Infection Society (MSIS) criteria. Implant survival was calculated using Kaplan-Meier method and compared with the log-rank test as well as multivariate Cox regression at a minimum follow-up period of 24 months., Results: The median follow-up period was 59 (interquartile range (IQR) 45-78) months. Overall, 24% (23/97) of patients required revision surgery for infection. The infection-free survival of rotating hinge revision TKA was 93% (95% Confidence Interval (CI) 86-100%) at five years compared to 50% (95% CI 34-66%) for DFR. In multivariate analysis, the risk factors for reinfection were DFR reconstruction (HR 4.7 (95% CI 1-22), p = 0.048), length of megaprosthesis (HR 1.006 (95% CI 1.001-1.012), p = 0.032) and higher BMI (HR 1.066, 95% CI 1.018-1.116), p = 0.007). 10% (4/41) of patients undergoing DFR underwent amputation to treat recurrent infection., Conclusion: Megaprosthetic DFR as part of a two-stage exchange for PJI is a salvage treatment that has a high risk for reinfection compared to non-megaprosthetic TKA. Patients must therefore be counseled accordingly., Level of Evidence: Retrospective observational study, Level IV., (© 2021. The Author(s).)

Megaprosthetic reconstruction of segmental bone defects following sarcoma resection is a frequently chosen surgical approach in orthopedic oncology. While the use of megaprostheses has gained popularity over the last decades and such implants are increasingly used for metastatic reconstructions and in non-tumor cases, there still is a high risk of long-term complications leading to revision surgery. This article investigates current implant survivorship, frequency and types of complications as well as functional outcomes of upper and lower limb megaprosthetic reconstructions.

The accurate preoperative diagnosis of periprosthetic joint infection (PJI) of total knee arthroplasty (TKA) can be difficult despite the use of a combination of serum and synovial markers. In such inconclusive cases, incisional open biopsy might be considered. This study investigates the usefulness of biopsies in patients with inconclusive diagnostic findings. We retrospectively identified 63 patients who underwent incisional biopsy for chronic PJI in the operation theatre following TKA revision between 2010 and 2018 after inconclusive preoperative diagnostics for PJI. In all cases, 5 independent biopsies were taken. Results from open biopsy for PJI were analyzed for diagnostic accuracy using the intraoperative results from following revision surgery as gold standard. 27 patients (43%) had a positive culture taken during biopsy. 15 cases (24%) met the diagnostic criteria for a chronic PJI. Most common organisms were Coagulase-negative staphylococci (67%) and Cutibacterium acnes (30%). Compared to the findings during revision surgery, biopsies showed a sensitivity of 47% and a specificity of 77% for PJI. Open incisional biopsy following inconclusive serum- and synovial diagnostics for low grade PJI may be considered for identification of microorganisms. Due to its low sensitivity and moderate specificity found in the present cohort, microbiological analysis should be combined with additional diagnostic markers and histological investigation.Level of Evidence. Retrospective cohort study (Level III).

Complications in megaprosthetic reconstruction following sarcoma resection are quite common. While several risk factors for failure have been explored, there is a scarcity of studies investigating the effect of the duration of surgery. We performed a retrospective study of 568 sarcoma patients that underwent megaprosthetic reconstruction between 1993 and 2015. Differences in the length of surgery and implant survival were assessed with the Kaplan-Meier method, the log-rank test and multivariate Cox regressions using an optimal cut-off value determined by receiver operating curves analysis using Youden's index. 230 patients developed a first and 112 patients a subsequent prosthetic failure. The median duration of initial surgery was 210 min. Patients who developed a first failure had a longer duration of the initial surgery (225 vs. 205 min, p = 0.0001). There were no differences in the probability of infection between patients with longer and shorter duration of initial surgery (12% vs. 13% at 5 years, p = 0.492); however, the probability of mechanical failure was higher in patients with longer initial surgery (38% vs. 23% at 5 years, p = 0.006). The median length of revision surgery for the first megaprosthetic failure was 101 min. Patients who underwent first revision for infection and did not develop a second failure had a longer median duration of the first revision surgery (150 min vs. 120 min, p = 0.016). A shorter length of the initial surgery appears beneficial, however, the notion that longer operating time increases the risk of deep infection could not be reproduced in our study. In revision surgery for infection, a longer operating time, possibly indicating a more thorough debridement, appears to be associated with a lower risk for subsequent revision.

D-dimer has been included in the criteria by the Musculoskeletal Infection Society in 2018 as a novel parameter to diagnose prosthetic joint infection (PJI). However, it is unclear how D-dimer levels change in between stages of a two-stage exchange. We prospectively investigated 30 patients who underwent a two-stage exchange using a spacer for PJI. D-Dimer, CRP and IL-6 were collected before first and second stage surgery and the difference (Δ) in between stages was calculated. The levels of plasma D-Dimer did not change from first to second stage surgery (2770 ng/ml (IQR, 1600-3770 ng/ml) versus 2340 ng/ml (IQR, 1270-4100 ng/ml); p = 0.8) while CRP (4.0 mg/dl (IQR, 1.7-5.5 mg/dl) versus 0.6 mg/dl (IQR, 0.5-0.8 mg/dl); p < 0.001) and IL-6 (21 pg/ml (IQR, 10-29 pg/ml) versus 6 pg/ml (4-9 pg/ml); p < 0.001) decreased. The ΔD-dimer between both stages was 300 ng/ml (range: - 2820 to 4280 ng/ml), the median ΔCRP was - 3.4 mg/dl (IQR, - 1.2 to - 4.8 mg/dl) and ΔIL-6 was - 13 pg/ml (IQR, - 4 to - 20 pg/ml). In 15 of 30 cases (50%) the D-dimer level increased between both stages, whereas the level of CRP (93%; 28/30) and IL-6 (96%; 28/29) decreased in most patients. As the level of serum D-dimers varies greatly, lacks a uniform decrease and does not identify persisting infection, surgeons should be cautious when using it at the timing of reimplantation.

Background: Two-stage exchange using antibiotic-loaded spacers is a common approach in treating periprosthetic joint infections. Acute kidney injury (AKIN) can be a systemic complication of this procedure. This study investigates the prevalence of AKIN and identifies potential risk factors., Methods: This is a single-center retrospective analysis of patients undergoing 2-stage exchange using a spacer in 285 patients treated between 2010 and 2017. Risk factors were evaluated using parametric and nonparametric analyses and a multivariate, binary logistic regression model., Results: Thirty-three percent of patients (95/285) developed an AKIN postoperatively. Twenty-four percent (23/95) of these patients had an acute on chronic kidney failure with a previously impaired renal function. In multivariate analysis, a higher age (hazard ratio [HR], 1.034; 95% confidence interval [CI], 1-1.068; P = .046) and a higher baseline creatinine level (HR, 1.94; 95% CI, 1.237-3.052; P = .004) were risk factors for AKIN. Treatment with vancomycin in the spacer or systemically was not associated with AKIN while a high vancomycin blood level (HR, 1.91; 95% CI, 0.913-3.992; P = .086) and fungal infections were (HR, 3.482; 95% CI, 0.968-12.521; P = .056). Furthermore, in univariate analysis, a higher median Charlson comorbidity index (4 vs 3, P = .007), a lower preoperative hemoglobin (10.9 vs 11.7 g/dL, P = .008), and a higher number of blood transfusions (1 vs 0, P = .004) were associated with AKIN., Conclusion: AKIN is common in patients undergoing 2-stage exchange. Associated patient factors, particularly in patients with chronic renal dysfunction, should be optimized. The general use of glycopeptide antibiotics was no risk factor for AKIN., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: Hypotensive epidural anesthesia (HEA) is used in total joint arthroplasty as a safe and effective blood-saving modality. In order to maintain the blood pressure and heart rate patients, receive 1000 to 1500 mL of lactated Ringer's solution during surgery. While HEA reduces the intraoperative blood loss, the effect of intravenous fluid loading on hemoglobin levels is not fully understood. The current study investigates the effect of HEA on perioperative hemoglobin levels., Materials and Methods: The study included 35 patients operated on by a single surgeon undergoing primary total knee arthroplasty under HEA. Intraoperatively, at least 300 mL of intravenous fluid were given every 15 min over the first 60 min after HEA. Blood samples were drawn before entering the operating room, after HEA, as well as after inflation of the tourniquet, every 15 min thereafter, as well as in the recovery room and on postoperative days one and two. In addition, fluid in- and outtake was recorded., Results: Patients received a mean 1275 mL during the 60 min of tourniquet time. The mean arterial pressure (MAP) 5 min after HEA dropped to 60 mmHg and reached a constant level of around 58 mmHg 15 min after HEA. The average hemoglobin level dropped from 13.9 g/dL prior to HEA, to 12.5 g/dL immediately after HEA ( p < 0.001). Intraoperatively the hemoglobin level dropped further and reached 11.8 g/dL at 60 min in the absence of blood loss., Conclusions: Hypotensive epidural anesthesia and the resulting fluid substitution resulted in an average hemoglobin drop of 2.1 g/dL within the first 60 min. This needs to be taken into account when evaluating the need for blood transfusions after primary joint replacement surgery under HEA.

Background: Soft tissue deficiency in total knee arthroplasty infection is a potentially devastating complication. Gastrocnemius muscle flaps can be used to address this problem. We aim at reporting survival rates of these reconstructions and identify risk factors for failure., Methods: A retrospective evaluation of all flaps performed at a single center between 2006 and 2019 was performed. Clinical and microbiological results were assessed in 43 cases after a median follow-up period of 53 months (25%-75% interquartile range 18-79). Function was assessed using the Oxford Knee Score. We analyzed the infection-free survival and identified risk factors using survival comparison and (non-)parametric testing., Results: Infection-free survival was 71% at 2 years and 63% at 5 years. The rate of subsequent amputation was 16% with a mortality rate of 26% during follow-up. Four patients did not undergo reimplantation and 11 patients received an arthrodesis implant. There were no failures of the flap itself. The Charlson Comorbidity index was the only relevant risk factor for reinfection. Coagulase-negative staphylococci were most common organisms identified. Postoperative function was limited with a mean Oxford Knee Score of 20., Conclusion: Gastrocnemius flap coverage is a valid option for soft tissue reconstruction in periprosthetic infections to retain a functioning limb despite a high complication rate and the risk of subsequent amputation., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: D-dimer is a diagnostic criterion for periprosthetic joint infection (PJI) of the Musculoskeletal Infection Society (MSIS) in 2018. The aim of this study was to evaluate the serum D-dimer values in comparison to C-reactive protein (CRP) and interleukin-6 (IL-6) for the diagnosis of PJI. Materials and Methods: We included 119 patients (50 women, 69 men; 71 knees, 48 hips) undergoing revision arthroplasty with preoperative assessment of CRP, IL-6, and serum D-dimer. Cases were classified as infected or aseptic based on the MSIS criteria of 2018. Receiver operating curves and Youden's index were used to define an ideal cut-off value and sensitivity and specificity for the individual parameters, and respective combinations were calculated using cross-tables. Results: The median D-dimer level (2320 vs. 1105 ng/mL; p < 0.001), the median CRP level (4.0 vs. 0.5 mg/dL; p < 0.001), and the median IL-6 level (21.0 vs. 5.0 pg/mL; p < 0.001) were significantly higher in the group of PJI compared to the group with aseptic failure. The calculated optimal cut-off values were 2750 ng/mL (AUC 0.767) for D-dimer, 1.2 mg/dL (AUC 0.914) for CRP, and 10.0 pg/mL (AUC 0.849) for IL-6. D-dimer showed a sensitivity of 38% and specificity of 94%, whereas the CRP and IL-6 had sensitivities of 88% and 76%, and specificities of 87% and 92%, respectively. Conclusion: In comparison with CRP and IL-6, serum D-dimer showed low sensitivity and specificity in our cohort. While CRP and IL-6 combination had the highest sensitivity, a combination of Il-6 and D-dimer or CRP and IL-6 had the highest specificity.

Introduction : The most common causative organism in periprosthetic joint infections (PJIs) is Gram-positive bacteria that are increasingly drug resistant. In these cases the use of linezolid may be warranted. However, there are conflicting reports regarding its role in antibiotic treatment of PJIs. The aim of this review is to gather and analyze clinical results and treatment details on linezolid in patients with PJIs. Methods : In August 2019, a comprehensive literature search using MEDLINE (Pubmed and Ovid) and Cochrane Library was performed. A total of 504 records were screened, and a total of 16 studies including 372 patients treated with linezolid for a PJI were included in this review based on the PRISMA criteria and after quality analysis using the MINOR score and Newcastle-Ottawa scale, as well as assessing level of evidence. Pooling analysis as well as descriptive analysis was performed. Results : Based on the results from the studies included, infection control was achieved in 80 % (range 30 %-100 %) of patients after a mean follow-up period of 25 (range 2-66) months. The mean duration of treatment was 58 d intravenous and orally at a median dose of 600 mg bis in die (b.i.d.) (range 400-900 b.i.d.). A combination therapy with rifampicin was used in 53 % of patients. MRSA (methicillin-resistant Staphylococcus aureus) infections were present in 29 % and resistant CoNS (coagulase-negative Staphylococcus ) in 46 %. Adverse effects occurred in 33 % of cases, mostly anemia, thrombocytopenia and gastrointestinal complaints leading to treatment discontinuation in 9 %. However, great heterogeneity was found with respect to surgical treatment, diagnosis of infection and indication for linezolid. Discussion : Linezolid is an appropriate option for treatment of resistant Gram-positive organisms in PJIs. Most commonly 600 mg b.i.d. is used, and a combination with rifampicin appears feasible although one must consider individual increases in doses in these cases. However, adverse effects are common and there are limited data for long-term use and optimal antibiotic combinations or individual doses., Competing Interests: The authors declare that they have no conflict of interest., (Copyright: © 2020 Christoph Theil et al.)

Background: Modular stems are widely used in revision total hip arthroplasty (THA) with aseptic loosening being a common reason for revision. Despite the good results reported on the use of modular stem designs, there are only few studies focusing on aseptic revisions and few studies on a hexagonal stem design. The goal of this study is to determine stem survival, clinical and functional outcome along with possible risk factors for implant failure in aseptic revision THA., Methods: We retrospectively identified 53 patients with aseptic THA revision using a modular hexagonal stem with a minimum follow-up of two years. Femoral bone loss, radiographic and clinical outcomes as well as function measured using the Harris Hip Score (HHS) was assessed. Patients' previous medical history was analyzed for comorbidities and the body mass index. Stem survival was calculated using the Kaplan-Meier method. Possible risk factors for implant failure were analyzed using the log-rank test. The median age at revision was 69 (IQR 62-73) with a median follow up of 74 months., Results: Implant survival rates amounted to 90.4% at 3 and 5 years. The median HHS improved by 47 points (34 (IQR 22-47) vs 81 (IQR 59-90) p<0.001). There was a reduced implant survival after 5 years when the revision stem was used following a previous cemented stem (83.4% vs 100%, p = 0.04)., Conclusion: A modular, hexagonal stem can be successfully used in aseptic revision THA with remarkable functional results and excellent survivorship. Revision of a cemented stem using this implant might result in reduced survival which must be considered when planning treatment., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: Prof. Georg Gosheger, Dr. Burkhard Möllenbeck, Dr. Thomas Ackmann and Dr. Tom Schmidt- Bräkling declare not to have any competing interests regarding this publication. Dr. Jan Schwarze, Dr. Christoph Theil and Prof. Ralf Dieckmann declare to have one financial competing interest: Travel grants and honoraria for speaking or participation at meetings have been paid by implantcast GmbH (Buxtehude Germany). This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Background: This study aims at investigating cup survival of porous tantalum revision cups and identifies risk factors for failure., Methods: We retrospectively reviewed 41 patients treated between 2010 and 2012. Main indications were aseptic loosening in 83% and two-stage exchange after periprosthetic joint infection in 17% of cases. Mean follow-up period was 72 months. Femoral megaprostheses were used in 13% of cases. Most defects were classified as Paprosky 3b (29%). Function was assessed using the Harris Hip score., Results: Aseptic cup survivorship was 80% at 104 months (95% Confidence Interval 67.4-92.4). Overall implant survival was 73%. Major bone loss defects (Paprosky types 2c to 3b) were associated with a significantly higher rate of failure than minor defects (P = 0.002). There were eight cases of aseptic loosening (19.5%) and two of infection (4.9%). Previous surgeries, indication for acetabular revision, patient-related risk factors and use of megaprostheses did not significantly influence implant survival. The Harris Hip Score improved from a median of 40 (Interquartile range 31-45) to 82 (interquartile range 65-88) postoperative (P < 0.0001)., Conclusions: In summary, the use of porous tantalum metal implants in acetabular revision surgery achieves good to excellent short- term and mid-term functional results and an acceptable complication rate relative to the extent of defect and previous surgery. However, one should be aware of potential limitations of the implants in addressing large defects and discontinuity.

Background: Despite very good prosthesis retention times, the growing numbers of primary implantations of hip endoprostheses are leading to increasing numbers of revision operations. Periprosthetic infection, particularly in revision implants, often leads to a massive loss of bone stock, so that in a two-stage exchange the only option left is implantation of a megaendoprosthesis. This retrospective study investigated the clinical and functional outcome for patients who received megaendoprostheses in the proximal femur in two-stage exchange procedures., Methods: Forty-nine patients were treated between 1996 and 2014 (mean age 71 years, mean follow-up period 52 months). Microorganisms were isolated intraoperatively in 44 patients (89.9%). The reinfection rate was documented in patients who did not undergo any further revision surgery due to mechanical failure (primary) and in patients who had subsequent revisions after reimplantation and subsequent reinfection (secondary)., Results: The mean C-reactive protein level at the time of reimplantation was 1.25 mg/dL (range 0.5-3.4). The primary success rate with curative treatment for prosthetic joint infection was 92% (four of 49 patients). The secondary success rate with infection revision cases was 82% (three of 17 revision cases). The mean Harris hip score was 69 (range 36-94). The majority of patients needed different types of walking aid or even wheelchairs, and only 50% of the patients were able to walk outside., Conclusions: Reinfections occurred in only 8% of patients who underwent two-stage exchanges with a proximal femur replacement. When revision surgery for the proximal femur replacement was required for mechanical reasons, however, the associated reinfections increased the reinfection rate to 18%. Proximal femur replacement achieves a clear reduction in pain, maintenance of leg length, and restoration of limited mobility, and the procedure thus represents a clear alternative to the extensive Girdlestone procedure, which is even more immobilising, or mutilating amputation.

Background: Due to the increasing numbers of revision total hip arthroplasty (THA) procedures being carried out, the frequency of major acetabular defects is also rising. A combination of an anti-protrusio cage and a dual mobility cup has been used in our department since 2007 in order to reduce the dislocation rate associated with complex defects. Although both implants have an important place in endoprosthetics, there are as yet limited data on the dislocation and complication rates with this combination., Methods: This retrospective study included all patients in whom a Burch-Schneider cage and a dual mobility cup were implanted in our department between 2007 and 2014 and who had a minimum follow-up period of 24 months., Results: The study included 79 patients with a mean follow-up period of 5.3 years. The implant survival rate was 85% at 65 months. Postoperative dislocation occurred in two cases (2.1%), with the first dislocation taking place within the first 3 weeks in both of these patients., Conclusions: The present study shows a promising dislocation rate with a combination of an anti-protrusio cage and a dual mobility cup. Particularly in the medium-term follow-up, no further dislocations occurred in the study. A maximum cup inclination of 45° in revision cases was associated with a lower dislocation rate in this group of patients., Competing Interests: The authors have declared that no competing interests exist.

Periprosthetic infection remains one of the most serious complications following megaendoprostheses. Despite a large number of preventive measures that have been introduced in recent years, it has not been possible to further reduce the rate of periprosthetic infection. With regard to metallic modification of implants, silver in particular has been regarded as highly promising, since silver particles combine a high degree of antimicrobial activity with a low level of human toxicity. This review provides an overview of the history of the use of silver as an antimicrobial agent, its mechanism of action, and its clinical application in the field of megaendoprosthetics. The benefits of silver-coated prostheses could not be confirmed until now. However, a large number of retrospective studies suggest that the rate of periprosthetic infections could be reduced by using silver-coated megaprostheses.

Background: In 2011, the current liner was withdrawn from the market because of the potential risk for liner fracture secondary to increased pressures used to assemble the metal locking ring. The present study provides a short-term follow-up of patients with this implant., Methods: We retrospectively evaluated 63 consecutive hips in 53 patients operated by a single surgeon using a recalled ceramic-on-ceramic bearing. There were 30 women and 23 men with an average age of 50.6 years (range 20.3-63.5 years). The mean follow-up was 36.8 months., Results: Six hips in 6 patients were revised (9.5%) because of a liner-fracture during the follow-up period. All liner fractures were identified on computer tomography imaging. Nine patients had self-reported episodes of squeaking (14.3%). All 6 patients that underwent revision surgery for liner fracture described squeaking before revision. There were no revisions for other causes. Two of the revised patients had a subsequent dislocation (33%)., Conclusion: The recalled ceramic liner lots have an increased liner fracture rate. Patients with mechanical symptoms or squeaking should undergo computer tomography to rule out liner facture., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Intact cartilage in the lateral compartment is an important requirement for medial unicompartmental knee arthroplasty. This study sought to determine how measurements of joint space width in the lateral compartment on valgus stress radiographs compare to cartilage thickness as measured with a precise needle test, and whether cartilage thickness is a predictor of cartilage degeneration., Methods: A consecutive series of 100 knees undergoing total knee arthroplasty for end-stage varus osteoarthritis was studied. Twenty-eight knees were retrospectively excluded because not all data were available, leaving 72 knees (61 patients; mean age, 67 years [49-87]). On calibrated valgus stress radiographs, lateral-compartment joint space width was measured. During surgery, osteochondral samples of the distal lateral femur and the lateral tibia plateau were harvested. Cartilage thickness and histology were assessed. Cartilage thickness of tibia and femur was defined as lateral-compartment cartilage thickness., Results: Lateral-compartment joint space width on valgus stress radiographs and lateral-compartment cartilage thickness correlated well (r s  = 0.671, P < .001). However, no correlation of cartilage histology according to the osteoarthritis cartilage histopathology assessment system, and cartilage thickness on the lateral tibia plateau (r s  = -0.060, P = .614) and cartilage thickness on the distal lateral femur (r s  = -0.128, P = .282) was observed., Conclusion: Valgus stress radiographs can assess combined cartilage thickness in the lateral compartment of the knee. Cartilage thickness, however, is a poor predictor of cartilage degeneration., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Although venous thromboembolism is one of the leading causes of morbidity after knee arthroplasty, little data exist on the risk of deep venous thrombosis (DVT) after unicompartmental knee arthroplasty (UKA)., Methods: We prospectively enrolled 112 patients undergoing UKA to determine the incidence of DVT utilizing aspirin 325 mg twice a day (BID) for 4 weeks postoperatively as DVT prophylaxis. The data were compared with a recent randomized controlled trial of patients undergoing total knee arthroplasty utilizing aspirin and Lovenox in conjunction with pneumatic compression devices., Results: One patient (0.9%) had an asymptomatic DVT, and none developed clinical symptoms of either DVT or pulmonary embolus. The incidence of asymptomatic and symptomatic DVT was 0.9% and 0%, respectively., Conclusion: Our data suggest that 325 mg of aspirin BID for 4 weeks results in a very low risk of DVT for patients undergoing UKA., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Introduction: Serum metal ions are part of the regular follow-up routine of patients with metal-on-metal total hip arthroplasties (MoM-THA). Increased cobalt levels have been suggested to indicate implant failure and corrosion., Questions: (1) Is there a correlation between the size of the osteolysis measured on a CT scan and metal ion levels? (2) Can metal ion levels predict the presence of osteolysis in MoM-THA? (3) Are cobalt and chromium serum levels or the cobalt-chromium-ratio diagnostic for osteolysis?, Materials and Methods: CT scans of patients (n = 75) with a unilateral MoM-THA (Birmingham Hip System, Smith & Nephew, TN, USA) implanted by a single surgeon were reviewed to determine the presence of osteolysis. Statistical analysis was performed to detect its association with metal ion levels at the time of the imaging exam., Results: The incidence of osteolysis was the same in men and women (35.6 vs 35.7 %). The cobalt-chromium-ratio correlates with the size of the osteolysis on the CT scan and the femoral component size in the overall study population (p = 0.050, p = 0.001) and in men (p = 0.002, p = 0.001) but not in women (p = 0.312, p = 0.344). The AUC for the cobalt-chromium-ratio to detect osteolysis was 0.613 (p = 0.112) for the overall population, 0.710 for men (p = 0.021) and 0.453 (p = 0.684) for women. The data suggest that a cut off level of 1.71 for the cobalt-chromium-ratio has a sensitivity of 62.5 % and specificity of 72.4 % to identify male patients with osteolysis., Conclusions: The disproportional increase of cobalt over chromium, especially in male patients with large component sizes can not be explained by wear alone and suggests that other processes (corrosion) might contribute to metal ion levels and might be more pronounced in patients with larger component sizes.

Competing Interests: The authors have no conflicts of interest to declare.

Objective: The current study investigates the diagnostic accuracy of the criteria described for frozen sections and whether modern leukocyte specific staining techniques including leukocyte peroxidase and Naphtol-AS-D-chloroacetate-esterase will improve the accuracy of the intra-operative histology., Method: 77 patients undergoing revision total hip and knee arthroplasty were included in this retrospective study. Patients were grouped into septic and aseptic based on intraoperative cultures. Tissue samples were analyzed utilizing the Mirra, Feldman, Lonner, Banit and Athanasou criteria., Results: An experienced pathologist had a high specificity (96%), but rather low sensitivity (57%) diagnosing infection. By using the Banit-, Mirra-, or Athanasou-criteria the sensitivity is increased to 0.90. The Feldman- and Lonner-criteria have a lower sensitivity (0.48 and 0.38), however, an increased specificity of 0.96 and 0.98, respectively. The Banit cut off has the highest accuracy (86%). MPOX and NACE staining increased the sensitivity and accuracy up to 100% and 92% respectively., Conclusion: Banit's cut off is the most accurate histologic criteria to diagnose infection. Modern leukocyte specific staining techniques slightly improve the accuracy. The synovial fluid white blood cell count appears to be the most accurate intraoperative test.

Introduction: Metal-on-metal (MoM) bearings are known to release metal ions secondary to wear and corrosion. This may cause local reactions (adverse soft tissue reactions and osteolysis) and systemic effects. Little is known about the exact pattern and the differences between large head MoM total hip replacements (THA) and resurfacings (HR)., Questions: (1) Is there a difference in metal ion concentrations between HR and MoM-THR using the same bearing design (Birmingham Hip Resurfacing System, Smith & Nephew, Inc. Memphis, TN, USA)? (2) Are metal ion levels changing over time in MoM-THA or HR? (3) Do acetabular inclination angle and femoral component size influence cobalt and chromium levels? Is there a correlation between clinical outcome and metal ion levels?, Materials and Methods: A retrospective analysis was conducted in 77 well functioning unilateral Birmingham HR and 42 well functioning unilateral modular Birmingham MoM-THA (Smith & Nephew, Inc. Memphis, TN, USA) operated on between 2007 and 2012. Blood samples were taken at a minimum of 13 months and subsequent during annual follow-ups., Results: (1) Cobalt levels were significantly higher in MoM-THA compared to HR (p < 0.001). There was no significant difference in chromium levels (p = 0.313). (2) Cobalt is increasing over time in MoM-THA (p = 0.030) whereas metal ions remain stable in HR. (3) Metal ion levels were not affected by acetabular inclination angle and femoral component size in MoM-THA. Chromium levels correlate with the femoral component size (r = -0.240; p = 0.037), the UCLA activity score (r = -0.344; p = 0.003) and the VAS (r = 0.263; p = 0.38) in HR., Conclusion: Considering that HR and MoM-THA used the same MoM bearing design, increased cobalt levels may be related to trunnion wear or corrosion. Elevated cobalt levels should raise concern for corrosion related failure in MoM-THA.

Fracture of a ceramic liner of a total hip arthroplasty is rare and is radiographically occult if not displaced. We report on two patients in whom ceramic liner fracture was radiographically occult but was diagnosed on subsequent CT scan through appropriate windowing.

Purpose: We investigated the effectiveness of non-image-guided hip injections., Methods: We retrospectively evaluated 369 intra-articular hip injections in 331 patients using anatomical landmarks. The percentage and duration of pain relief was documented. Hip injections were grouped in responders and nonresponders (50 % maximum pain relief as a cut off)., Results: In 82% (n = 304) of hip injections, patients responded positively and experienced >50 % pain relief. Nonresponders had a significantly higher body mass index (p = 0.007)., Conclusions: Hip injections using anatomical landmarks are an effective treatment option for patients with osteoarthritis of the hip.

Introduction: Postoperative hip dislocations have been reported in 0.5 to 10.6 % of patients after primary posterolateral total hip arthroplasty (THA). Hip precautions are currently recommended for 6 weeks postoperatively to reduce early dislocation and facilitate healing of the posterior soft tissue repair., Materials and Methods: To determine the impact of a modified 4-week precaution protocol on the dislocation rate, 698 consecutive patients (797 hips) operated by a single surgeon between September 2008 and December 2012 were retrospectively evaluated. All patients had a standard THA using a minimal invasive posterior approach with posterior soft tissue repair and 28-36-mm head size. 98.7 % of the patients were available for follow-up., Results: There were eight (1 %) dislocations in 797 hips in the first 12 months after surgery with 4 weeks of hip precautions. The average time to dislocation was 7.5 weeks after surgery (range 1.0-16.9 weeks); two dislocations (25 %) took place in the first 4 weeks., Conclusions: Shortening the time of posterolateral hip precautions from 6 to 4 weeks after surgery does not increase the risk of postoperative dislocation.

Background: Lateral patellar arthritis has been associated with poor outcomes in unicompartmental knee arthroplasty. The current study correlates intraoperative findings with MRI imaging, skyline radiographs and the presence of anterior knee pain., Methods: In 92 consecutive knees with varus arthritis, the patellofemoral compartment was assessed during surgery, on skyline radiographs and on MRI. Anterior knee pain was recorded on a visual-analog-scale. Intraoperative assessment was based on the Outerbridge grading scale. Skyline radiographs were evaluated according to the Ahlbäck grading scale; MRIs were assessed according to a modified Outerbridge grading scale., Results: There was an excellent correlation (rs=0.833; p<0.001) in the cartilage assessment of the lateral patellar facet between MRI and surgery. A good correlation (rs=0.664; p<0.001) was seen between Ahlbäck Grades and macroscopic Outerbridge Grades of the lateral patella. Ahlbäck Grades and MRI modified Outerbridge Grades showed a good correlation (rs=0.643; p<0.001) for the lateral patella. Twelve percent of knees (seven out of 60) with Ahlbäck Grade 0 or 1 and mild to moderate anterior knee pain had a macroscopic Outerbridge Grade of 3 on the lateral patella. None of these 60 knees had a full-thickness cartilage defect on MRI., Conclusion: Normal skyline radiographs in patients with mild to moderate anterior knee pain can rule out full-thickness cartilage defects of the lateral patellar facet as observed during surgery and on MRI. The MRI allows for the most accurate assessment of the patellofemoral joint and is warranted in all patients with radiographic abnormalities or severe anterior knee pain., Level of Evidence: Diagnostic study, Level II., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Objective: Osteolysis has not been recognized as a common failure mode of the Birmingham modular metal-on-metal (MoM) total hip arthroplasty (THA). The clinical value of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) to assess the periprosthetic soft tissue is well documented; however, the appropriate image modalities to detect periacetabular osteolysis remain unclear. Eleven patients with periacetabular osteolysis within 3-6 years after uncemented Birmingham modular MoM THA with a synergy stem are presented. All 11 patients received corresponding standardized AP pelvis radiographs, high-quality MARS MRIs and CT scans with a metal artifact reduction sequence. While periacetabular osteolysis around MoM THA was not detected on MARS MRI in ten patients, CT imaging identified osteolysis in all patients. Periacetabular osteolysis appears to be a failure mechanism of the Smith & Nephew Birmingham MoM THA., Discussion: There is no evidence in the literature to support the effectiveness of MARS MRI to detect periacetabular osteolysis around cobalt chromium alloy metal-on-metal total hip arthroplasties. Osteolysis due to corrosion-related particles seems to be one of the primary modes of failure in modular MoM THA., Conclusions: MRI is not a sensitive test to identify periacetabular osteolysis. The authors recommend CT for the screening of implants with this failure mode. Our study suggests that patients with a Birmingham modular MoM THA are at increased risk to develop acetabular osteolysis and should be carefully monitored for this failure mode.

Purpose: Limited data exist for the reconstructive potential of short bone-preserving stems in THA using a minimal invasive posterolateral approach. Our study aim was to assess the effect of stem design on the reconstruction of hip offset and leg length in MIS posterolateral THA., Methods: This retrospective consecutive single-surgeon study compares hip offset and leg length, as well as acetabular component positioning (cup anteversion; inclination) of 129 THAs with a cementless standard-length stem (Synergy®) and 143 THAs with a cementless short bone-preserving stem (Trilock®)., Results: In reference to the contralateral side, the mean difference in hip offset was 0.9 mm (p = 0.067) for the standard stem and 0.1 mm (p = 0.793) for the short stem, respectively. Leg-length discrepancy was 0.7 mm (Synergy®) and 0.9 mm (Trilock®), respectively. A total of 233 (86 %) acetabular components fell within the target zone for anteversion and inclination., Conclusion: Accurate component positioning in MIS posterolateral approach THA is possible and is not influenced by the type of stem.