Soluble Urokinase Plasminogen Activator Receptor (SuPAR) Analysis for Diagnosis of Periprosthetic Joint Infection

Soluble urokinase plasminogen activator receptors (suPARs) are a biomarker for inflammatory diseases. This study aims to investigate its diagnostic properties regarding periprosthetic joint infections (PJI). This retrospective cohort study included adult patients who underwent joint puncture for suspected PJI. The presence of PJI was determined according to the criteria of the European Bone and Joint Infection Society (EBJIS). Laboratory study analyses included the determination of white blood cells (WBC) in whole blood, C-reactive protein (CRP) in blood plasma, and suPAR in both blood plasma and synovial fluid. Appropriate diagnostic cut-off values were identified utilizing Youden's J, and their diagnostic performance was determined by calculating the positive (PPV) and negative predictive value (NPV) for each marker. Sixty-seven cases were included in the final analysis. Forty-three samples (64%) were identified as periprosthetic joint infection (PJI) and twenty-four specimen (36%) were PJI negative cases. The PPV and NPV were 0.80 and 0.70 for synovial suPAR, 0.86 and 0.55 for CRP, 0.84 and 0.31 for WBC and 1.00 and 0.31 for plasma suPAR. Synovial suPAR showed a solid diagnostic performance in this study and has the potential to be an alternative or complementary biomarker for PJI. Further investigations in larger patient collectives are indicated.

Vancomycin Elution Kinetics of Four Antibiotic Carriers Used in Orthopaedic Surgery: In Vitro Study over 42 Days

This study aimed to analyse and compare the vancomycin elution kinetics of four biodegradable, osteoconductive antibiotic carriers used in clinical practice within a 42-day in vitro setting. Carriers A and D already contained vancomycin (1.1 g and 0.247 g), whereas carriers B and C were mixed with vancomycin according to the manufacturer's recommendations (B: 0.83 g and C: 0.305 g). At nine time points, 50% (4.5 mL) of the elution sample was removed and substituted with the same amount of PBS. Probes were analysed with a kinetic microparticle immunoassay. Time-dependent changes in vancomycin concentrations for each carrier and differences between carriers were analysed. Mean initial antibiotic levels were highest for carrier A (37.5 mg/mL) and lowest for carrier B (5.4 mg/mL). We observed time-dependent, strongly negative linear elution kinetics for carriers A (-0.835; p < 0.001), C (-0.793; p < 0.001), and D (-0.853; p < 0.001). Vancomycin concentrations increased from 48 h to 7 d and dropped thereafter in carriers C and D whilst constantly decreasing at any time point for carrier A. Carrier B showed a shallower decrease. Mean antibiotics levels at 42 d were 1.5 mg/mL, 2.6 mg/mL, 0.1 mg/mL, and 0.1 mg/mL for carriers A, B, C, and D. Differences in mean initial and final vancomycin concentrations for carrier A were significantly larger in comparison to C (p = 0.040). A carrier consisting of allogenic bone chips showed the highest vancomycin-to-carrier ratio and the largest elution over the study period. Whilst vancomycin concentrations were still measurable at 42 days for all carriers, carrier A provided a higher drug-to-carrier ratio and a more consistent antibiotic-releasing profile.

Total joint arthroplasty versus resection-interposition arthroplasty for thumb carpometacarpal arthritis: a randomized controlled trial

BACKGROUND AND PURPOSE

 Thumb carpometacarpal (TCMC) osteoarthritis is a common condition that causes pain and functional limitations. We compared the outcomes of 2 surgical procedures for TCMC osteoarthritis, the Epping resection-suspension arthroplasty and the double-mobility TCMC prosthesis, and focused on pain relief, functional outcomes, and patient quality of life.

PATIENTS AND METHODS

 Over a 7-year period a randomized controlled trial including 183 cases of TCMC osteoarthritis was conducted comparing a double mobility TCMC prosthesis (Moovis, Stryker, Kalamazoo, MI, USA) with the Epping resection-suspension arthroplasty. Pre- and postoperative examinations included the range of motion (ROM), SFMcGill score, visual analogue scale (VAS), the disabilities of the arm, shoulder and hand questionnaire (DASH), and the hospital anxiety and depression scale (HADS).

RESULTS

 At the 6-week postoperative follow-up, significant differences were found in VAS: Epping median 4.0 (interquartile range [IQR] 2.0-5.0) vs. TCMC prosthesis 2.0 (IQR 0.25-4.0), p = 0.03, effect size (area under the curve [AUC]) 0.64 (95% confidence interval [CI] 0.55-0.73), in DASH score: Epping 61 (IQR 43-75) vs. TCMC prosthesis 45 (IQR 29-57), p < 0.001, AUC 0.69 (CI 0.61- 0.78), and in radial abduction: Epping 55 (IQR 50-60) vs. TCMC prosthesis 62 (IQR 60-70), p = 0.001, AUC 0.70 (CI 0.61-0.79). No significant group differences were found at the 6- and 12-months follow-up. During the follow-up period, 3 of 82 prostheses had to be revised but there was no revision in the Epping group.

CONCLUSION

The double mobility TCMC prosthesis had superior outcomes compared with the Epping procedure at 6 weeks; however, there were no significant differences in outcomes at 6 months and 1 year postoperatively. The implant survival rate of 96% after 12 months was acceptable.

The Sinus Tract in Bone and Joint Infection: Minimally Invasive Salvation or Prolonged Suffering? A Multicenter Study

This study assessed the quality of life (QOL) and the functional outcome in daily living in patients with a chronic, treatment-resistant periprosthetic joint infection (PJI) or osteomyelitis, living with a natural or iatrogenic sinus tract.

METHODS

A follow-up examination in three national reference centers for septic bone and joint surgery was performed utilizing the Hospital Anxiety and Depression Scale (HADS-D/A), the Visual Analogue Scale (VAS), and the Short Form-36 (SF-36) score, including patients with a chronic sinus tract due to treatment-resistant PJI or osteomyelitis.

RESULTS

In total, 48 patients were included, with a mean follow-up time of 43.1 ± 23.9 months. The mean SF-36 Mental Component Summary (MCS) was 50.2 (±12.3) and the Physical Component Summary (PCS) was 33.9 (±11.3). The mean HADS-D was 6.6 (±4.4) and HADS-A was 6.2 (±4.6), and the VAS was 3.4 (±2.6). The SF-36 MCS showed no significant differences between the study group and the standard population (47.0, p = 0.10), as well as the HADS-A. The PCS in the study population was significantly worse (50.0, p < 0.001), as was the HADS-D.

CONCLUSIONS

A sinus tract represents a treatment option in selected cases with an acceptable QOL. The treatment should be considered for multimorbid patients with a high perioperative risk or if the bone or soft tissue quality prevents surgery.

Long-term changes in serum silver concentrations after extremity reconstruction with silver-coated megaprostheses

Silver-coated megaprostheses are considered to reduce infection rate following reconstruction of bone defects in tumour surgery or revision arthroplasty. However, little is known about systemic silver exposure and possible side effects. The aim of this study was to analyse serum silver concentrations in patients with silver-coated megaprostheses over a prolonged time period. Between 2004 and 2016, 46 patients (52.2% female, mean age at surgery 47.1 ± 24.2 years) received silver-coated megaprostheses for septic (n = 26) or oncological (n = 17; main implant since 2013) indications, or aseptic loosening (n = 3). Blood was drawn from all patients within the first few days following surgery (without silver ion levels) and thereafter every 6 months at the outpatient department (with silver ion levels). Inductively coupled plasma mass spectrometry was used to determine silver ion levels. Median follow-up was 47.3 months (IQR: 16.1–78.9). Overall, 29 revision surgeries became necessary in 20 patients, equivalent to a cumulative complication rate of 63.0%. Revisions were most commonly for periprosthetic joint infections (PJIs, n = 12) and instability/soft tissue problems (n = 10). Revision-free implant survival was 81.4%, 42.3% and 35.2% at one, 5 and 10 years. Incidence of local argyria was 8.7% (n = 4). Silver ion levels at two or more consecutive time points during follow-up were available for 26 patients. An increment of silver levels within the first months (“run-in”) was observed, followed by an unspecific undulating course. Median initial and latest follow-up (median, 49.5 months) serum silver ion levels were 16.0 ppb (IQR: 9.1–29.1) and 7.4 ppb (IQR: 2.7–14.1), respectively. According to the multivariate mixed linear random-effects model, development of PJI was associated with significantly higher silver ion levels over time (p = 0.002), irrespective of time from surgery (p = 0.274). In the current series, a cumulative complication rate of 63.0% was observed for patients receiving silver-coated megaprostheses for septic of oncological indications. An overall unspecific course of silver ion concentration was present. Development of PJI was significantly associated with increased silver ion levels over time. Yet, no systemic complication associated to high silver levels occurred. It can be concluded that silver-coated implants constitute a safe solution for megaprosthetic reconstruction, but monitoring of silver concentrations is recommended.

Cat at home? Cat scratch disease with atypical presentations and aggressive radiological findings mimicking sarcoma, a potential diagnostic pitfall

Background and purpose - Cat scratch disease (CSD) is a self-limiting disease caused by Bartonella (B.) henselae. It is characterized by granulomatous infection, most frequently involving lymph nodes. However, it can present with atypical symptoms including musculoskeletal manifestations, posing a diagnostic challenge. We describe the prevalence and demographics of CSD cases referred to a sarcoma center, and describe the radiological, histological, and molecular findings.Patients and methods - Our cohort comprised 10 patients, median age 27 years (12-74) with clinical and radiological findings suspicious of sarcoma.Results - 7 cases involved the upper extremities, and 1 case each involved the axilla, groin, and knee. B. henselae was found in 6 cases tested using polymerase chain reaction and serology in 5 cases. 9 cases were soft tissue lesions and 1 lesion involved the bone. 1 patient had concomitant CSD with melanoma metastasis in enlarged axillary lymph nodes. On MRI, 5 soft tissue lesions were categorized as probably inflammatory. In 3 cases, with still detectable lymph node structure and absent or initial liquefaction, the differential diagnosis included lymph node metastasis. A sarcoma diagnosis was suggested in 4 cases. The MRI imaging features of the bone lesion were suspicious of a bone tumor or osteomyelitis.Interpretation - Atypical imaging findings cause a diagnostic challenge and the differential diagnosis includes malignant neoplasms (such as sarcoma or carcinoma metastasis) and other infections. The distinction between these possibilities is crucial for treatment and prognosis.

Risk of reinfection after two- or multiple-stage knee revision surgery using superficial vancomycin coating and conventional spacers

This study investigates the effect of superficial vancomycin coating (SVC) in two- or more-stage exchange procedures of prosthetic knee joint infections. We hypothesized that spacer treatment with SVC result in lower reinfection rates than conventional spacers after prosthetic reimplantation. Our secondary aim was to determine the demographic and treatment factors associated with reinfection rates. This retrospective cohort study compromised 96 cases with prosthetic knee infections. Twenty-four cases were treated with a temporary SVC spacer and 72 cases with conventional spacers. Prosthetic reinfection occurred after a median observation period of 1.7 ± 4.0 years in 24 cases (25%). The prevalence of having a reinfection was not significantly different between the two treatment groups (13% [3 cases] in the SVC group vs. 29% [21 cases] in the conventional spacer group [p = .104]). In seven cases (7.3%), two in the SVC group (8.3%) and five (6.9%) in the conventional spacer group (p ≥ .999), histological, respectively microbiological evaluations from the intraoperative specimens revealed persistent infection at the second stage. Nevertheless, in all seven cases no significant higher risk of periprosthetic reinfection was observed during follow-up (p = .750). Our secondary investigation of cofactors revealed that spacers additionally stabilized by nails were significantly associated with a 3.9-fold higher hazard ratio of sustaining a reinfection of revision prosthesis (p = .005).

Comparison of elution characteristics and mechanical properties of acrylic bone cements with and without superficial vancomycin coating (SVC) in the late phase of polymerization

INTRODUCTION

Antibiotic-loaded bone cements (ALBCs) are used as spacers in two-stage revision arthroplasty for periprosthetic joint infection. We previously described a new technique applying vancomycin powder coating to custom-made cements. To our best knowledge, this method of superficial vancomycin coating (SVC) has not been assessed before. We therefore performed an in-vitro study to determine: (1) whether manually applied SVC strengthened the cements' antibiotic effect; and (2) whether the mechanical requirements for the cements were fulfilled.

HYPOTHESIS

SVC increases the antibiotic effect of cement within the first 24hours.

METHODS

Cuboid blocks were produced from two commercially available acrylic ALBCs (Palacos R+G and Copal G+V) with and without SVC. Each block was eluted in phosphate-buffered saline at 37°C. Eluates obtained at 1, 2, 3, 4, 5, 10, 15, 30 and 60minutes and 3, 6 and 24hours were evaluated against Staphylococcus aureus (Palacos, Copal) and methicillin-resistant Staphylococcus aureus (MRSA) (Copal) using zone of inhibition tests. Mechanical test results (bending modulus, bending strength) were compared to ISO requirements (≥1800MPa, ≥50MPa).

RESULTS

Palacos with SVC produced significantly greater zones of inhibition against Staphylococcus aureus than Palacos without SVC (p=0.002). Copal with SVC showed greater zones of inhibition against both Staphylococcus aureus and MRSA (p=0.002). The antibiotic effect was enhanced by SVC in both cements at every time point within 24hours. The bending modulus and bending strength of Palacos with SVC (2089±166MPa, 60.8±2.6 MPA) and Copal with SVC (2283±195MPa, 56.9±2.4MPa) were significantly above ISO requirements.

CONCLUSION

SVC boosts the antibiotic effect of ALBCs in the first 24hours, while maintaining sufficient stability. These findings endorse SVC as a promising additive in septic revision surgery.

LEVEL OF EVIDENCE

III; case control study.

Residents' Learning Curve of Total Knee Arthroplasty Based on Radiological Outcome Parameters: A Retrospective Comparative Study

BACKGROUND

This study aimed to plot the impact of a learning curve for a resident's first 103 total knee arthroplasties (TKAs) based on radiological deviations and incision to closure time (ICT), and to compare it to 103 matched TKAs performed by a senior surgeon.

METHODS

This is a retrospective comparative study comprising a total of 206 TKAs and evaluated the results based on radiographic outcome and ICT. Radiological evaluation was performed according to a predefined implemented radiological grading system (RGS). t-Tests compared ICT and RGS; data of mechanical axis were observed with Man-Whitey U-tests and Wilcoxon signed-rank-tests.

RESULTS

The study included 206 patients (mean age 73 years, mean body mass index of 30). Determining all the deviation points (DP) with the RGS, the deviation ratio for resident vs senior surgeon was 0.96:0.5 DP (P = .0002). The learning curve based on DP showed a decrease over time with statistical significance in the first (26 DP, P = .0001), second (21 DP, P = .0059), and fourth (20 DP, P = .0187) quintiles of implanted cases. The ICT of the resident showed a decrease within the quintiles from 79.45 minutes (first quintile) to 65.17 minutes (fifth quintile), for an improvement of 14.28 minutes. When the quintiles are viewed in relation to the mean operation time of the senior surgeon (mean ICT 66.04 minutes), the mean values of the first and the second quintiles remain statistically significant.

CONCLUSION

Supervised TKA showed statistical significance in the learning curves according to deviations documented with a predefined radiological outcome assessment system as well as to ICTs.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The Dark Side of Arthroplasty: Competing Risk Analysis of Failed Hip and Knee Arthroplasty With Periprosthetic Joint Infection

BACKGROUND

Increasing total hip (THA) and knee (TKA) arthroplasties inevitably lead to accumulating failed arthroplasty (FA) with periprosthetic joint infections (PJI) and definite treatment recommendations are scarce. Our aims were to evaluate patient and infection site specific risk factors, and to identify case-dependent salvage procedure recommendations.

METHODS

Retrospective analysis was conducted of salvage procedures for FA after PJI (amputation, Girdlestone resection arthroplasty [GRA], arthrodesis, or chronic fistulation [CF]) from 2008 to 2018. Univariable and multivariable modeling of revision and mortality rates, using cumulative incidence competing risk analysis, and Cox proportional hazards models were calculated.

RESULTS

In total, 135 patients (THA 62%; TKA 38%) were diagnosed for FA after PJI, having undergone an average of 3 [1-4] revisions at a mean follow-up of 12.8 [7.8-20.9] years. Forty-four percent of THAs and 55% of TKAs had to be revised following FA, 44% deceased during follow-up, and 16% could be reconverted to an infection-free arthroplasty. GRA revealed significantly higher revision rates than CF (P = .015) for THA. Lower age (P = .003), higher number of revisions before FA (P = .007), more than one microorganism at infection site (P = .034), and GRA (P = .037, only THA) prevailed independent risk factors for revision. Patients' age remained an independent mortality risk factor (P = .001).

CONCLUSION

High-risk patients suffering from FA after THA with poor constitution profit from controlled constitution of CF, reducing the risk for revision surgeries and hospitalization. In case of FA after TKA, data did not allow definite treatment recommendations. We believe that education concerning amputation should be considered early after multiple TKA revisions.

Combined serum biomarker analysis shows no benefit in the diagnosis of periprosthetic joint infection

Purpose

In many cases, the diagnosis of a periprosthetic joint infection (PJI) consisting of the clinical appearance, laboratory tests, and other diagnostic tools remains a difficult task. Single serum biomarkers are easy to collect, are suitable for periodical assessment, and are a crucial tool in PJI diagnosis, but limited sensitivity or specificity is reported in literature. The aim of this study was to combine the best-performing single serum biomarkers into a multi-biomarker model aiming to improve the diagnostic properties.

Methods

Within a 27-month period, 124 surgical procedures (aseptic or septic revision total knee arthroplasty (TKA) or total hip arthroplasty (THA)) were prospectively included. The serum leukocyte count, C-reactive protein (CRP), interleukin-6, procalcitonin, interferon alpha, and fibrinogen were assessed 1 day prior to surgery. Logistic regression with lasso-regularization was used for the biomarkers and all their ratios. After randomly splitting the data into a training (75%) and a test set (25%), the multi-biomarker model was calculated and validated in a cross-validation approach.

Results

CRP (AUC 0.91, specificity 0.67, sensitivity 0.90, p value 0.03) and fibrinogen (AUC 0.93, specificity 0.73, sensitivity 0.94, p value 0.02) had the best single-biomarker performances. The multi-biomarker model including fibrinogen, CRP, the ratio of fibrinogen to CRP, and the ratio of serum thrombocytes to CRP showed a similar performance (AUC 0.95, specificity 0.91, sensitivity 0.72, p value 0.01).

Conclusion

In this study, multiple biomarkers were tested for their diagnostic performance, with CRP and fibrinogen showing the best results regarding the AUC, accuracy, sensitivity, and specificity. It was not possible to further increase the diagnostic accuracy by combining multiple biomarkers using sophisticated statistical methods.

Excellent mid-term osseointegration and implant survival using metaphyseal sleeves in revision total knee arthroplasty

PURPOSE

Metaphyseal fixation in revision total knee arthroplasty (RTKA) is a very promising treatment option for extended bone defects. Currently published mid-term results remain limited. The purpose was to analyse the implant durability, the clinical and the radiological mid-term results in RTKA when using metaphyseal sleeves.

METHODS

Clinical and radiological follow-up examinations were performed in 92 patients (93 knees) with RTKA using hybrid fixation technique (cementless sleeves and stem). Radiographic measurements regarding osseointegration at the bone-sleeve interface were performed and the range of motion (ROM), a subjective satisfaction score (SSS), the American Knee Society Score (KSS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) as well as the SF-36 Health survey were examined. Bone defects were analysed using the Anderson Orthopaedic Research Institute (AORI) classification.

RESULTS

No knee had to be revised due to aseptic loosening at the time of the follow-up (mean 6.3 years ± 2.3, minimum 2 years). Satisfactory radiographic osseointegration at the sleeve/bone interface was detected in 96.1% of cases. 17 knees (18.2%) had to be re-revised, 15 of them due to a recurrent infection and 2 due to aseptic reasons (mediolateral instability and a periprosthetic fracture). The median of the ROM (96°), SSS (8), KSS (87), WOMAC (9), SF-36 MCS (55) and SF-36 PCS (38) showed very satisfying results.

CONCLUSION

No case of aseptic loosening was found in this large series of RTKA with extended bone defects using metaphyseal sleeve fixation. In this large retrospective series, it has been shown that this technique is an excellent treatment option for extended bone defects in RTKA surgery.

LEVEL OF EVIDENCE

Retrospective cohort study, level III.

[Silver coating on tumour prostheses]

BACKGROUND

Modular endoprostheses, so-called "tumour or megaprostheses" are mainly used for limb salvage surgery after resection of malignant soft tissue or a bone tumour. Sometimes, this type of prosthesis is also used for revision surgeries after failed primary joint arthroplasty. Despite continuously improving techniques and quality management systems, periprosthetic infection is one of the most serious complications.

AIM OF THE STUDY

Review of the literature in the PubMed data base with the main focus on silver coatings in joint arthroplasty and their effect on infection rate, outcome and patients' safety.

RESULTS

The current literature shows that there is a beneficial role of silver coatings in megaprostheses in terms of revision rates for septic complications, especially following tumour resection with bad soft tissue coverage or in (multimorbid) high-risk patients, compared to uncoated implants.

DISCUSSION

Based on the results of previous publications examining blood or serum silver concentrations or silver levels in urine, silver coatings do not appear to have side effects, except for local argyria. Continuous monitoring of silver levels in blood or serum is still recommended, and additional long-term studies will be necessary to verify the effectiveness and safety of silver coatings.

Septic Revision Total Knee Arthroplasty: Treatment of Metaphyseal Bone Defects Using Metaphyseal Sleeves

BACKGROUND

Bone loss is a severe problem in septic revision total knee arthroplasty (RTKA). The use of porous coated metaphyseal sleeves is a promising treatment option for metaphyseal bone defects. The currently published midterm results remain limited and no study has been focused exclusively on septic cases. Our aim was to determine the implant survivorship (with special focus on osseointegration) and the clinical and radiological midterm outcome of metaphyseal sleeve fixation in septic RTKA surgery (minimum follow-up of 2 years).

METHODS

We performed a clinical and radiographic examination of 56 patients with a history of prosthetic joint infection who underwent 2-stage RTKA with the use of porous coated metaphyseal sleeves. These examinations included evaluation of the American Knee Society Score, the Western Ontario and McMaster Universities Osteoarthritis Index, the Short Form (SF-36) Health survey as well as radiographic measurement to determine whether successful osseointegration had been achieved.

RESULTS

Nine patients (16%) had to be re-revised at the time of follow-up (mean, 5.3 years; range, 2-11.2), all due to reinfection. We did not encounter any cases of aseptic loosening. The mean range of motion (92°, SD ± 21°), subjective satisfaction score (7, SD ± 2), American Knee Society Score (76, SD ± 19), Western Ontario and McMaster Universities Osteoarthritis Index (70, SD ± 20), SF-36 mental component summary (55, SD ± 14), and SF-36 physical component summary (35, SD ± 9) have shown satisfying results.

CONCLUSION

Metaphyseal sleeves have shown very promising midterm results regarding clinical scores, osseointegration, and aseptic loosening. Our results are the first analyzing exclusively septic indications and indicate that they are a reliable fixation option in all bone defect types in septic RTKA patients.

Fibrinogen - A Practical and Cost Efficient Biomarker for Detecting Periprosthetic Joint Infection

The early and accurate diagnosis of periprosthetic joint infection (PJI) can be challenging. Fibrinogen plays an important role in mediating inflammation of bacterial infections and therefore could be a valuable biomarker for PJI. The purpose of this study was to investigate the sensitivity and specificity of serum levels of fibrinogen in detecting PJI, and to compare the results with the established PJI biomarkers C-reactive protein (CRP) and leukocyte count. Eighty-four patients (124 surgeries) were prospectively included. The preoperatively analyzed parameters were fibrinogen, CRP and leukocyte count. The sensitivity and specificity of the biomarkers were calculated and compared. Fibrinogen (p < 0.001), CRP (p < 0.001) and leukocyte count (p < 0.001) had a statistically significant correlation with the criteria defining the presence of PJI. For fibrinogen, the value of 519 mg/dl had a sensitivity of 0.90 and a specificity of 0.66. The CRP cut-off point of 11.00 mg/dl had a sensitivity of 0.90 and a specificity of 0.74. The leukocyte count of 5.68 G/l had a sensitivity of 0.90 and a specificity of 0.39. Our results indicated that fibrinogen is a significant biomarker for detecting a bacterial PJI. It has shown to be a cost-efficient diagnostic support with high sensitivity and specificity.

Survival Rate of Short-Stem Hip Prostheses: A Comparative Analysis of Clinical Studies and National Arthroplasty Registers

BACKGROUND

The primary aim was to evaluate the outcome of short-stem hip prostheses in terms of overall revision rates. Data were taken from published literature and national arthroplasty registers. The second study aim was to evaluate a potentially superior outcome of dependent compared to independent clinical studies.

METHODS

All clinical studies on short-stem hip prostheses between 2006 and 2016 were reviewed and evaluated with a special interest on revision rates. Revision rate was calculated as "revision per 100 component years." Short stems were divided into femoral neck retaining (NR), neck sparing (NS), and neck harming (NH) prostheses. Published literature was further classified into dependent and independent studies, and data were compared to the Australian National Arthroplasty Register.

RESULTS

Fifty-two studies with 56 cohorts met the inclusion criteria and were therefore included in our study. All clinical studies showed a median revision rate of 4.8% after 10 years. NS and NH stems performed equally, whereas neck retaining prostheses were significantly inferior. Independent showed higher revision rates compared to dependent data without being statistically significant. The Australian register revealed a revision rate of 6.6% after one decade.

CONCLUSION

Similar low revision rates for NS and NH short-stem prostheses were found in the included data. Dependent studies seem not to be biased with regard to the longevity of short-stem hip replacement. Longer follow-up periods in clinical studies and more detailed information in arthroplasty registers would be desirable for future studies.

Pedicle screw loosening is correlated to chronic subclinical deep implant infection: a retrospective database analysis

PURPOSE

Spinal fusion is used for treatment of spinal deformities, degeneration, infection, malignancy, and trauma. Reduction of motion enables osseous fusion and permanent stabilization of segments, compromised by loosening of the pedicle screws (PS). Deep implant infection, biomechanical, and chemical mechanisms are suspected reasons for loosening of PS. Study objective was to investigate the frequency and impact of deep implant infection on PS loosening.

METHODS

Intraoperative infection screening from wound and explanted material sonication was performed during revision surgeries following dorsal stabilization. Case history events and factors, which might promote implant infections, were included in this retrospective survey.

RESULTS

110 cases of spinal metal explantation were included. In 29.1% of revision cases, infection screening identified a germ, most commonly Staphylococcus (53.1%) and Propionibacterium (40.6%) genus. Patients screened positive had a significant higher number of previous spinal operations and radiologic loosening of screws. Patients revised for adjacent segment failure had a significantly lower rate of positive infection screening than patients revised for directly implant associated reasons. Removal of implants that revealed positive screening effected significant pain relief.

CONCLUSIONS

Chronic implant infection seems to play a role in PS loosening and ongoing pain, causing revision surgery after spinal fusion. Screw loosening and multiple prior spinal operations should be suspicious for implant infection after spinal fusion when it comes to revision surgery. These slides can be retrieved under Electronic Supplementary Material.

Superficial Vancomycin Coating of Bone Cement in Orthopedic Revision Surgery: A Safe Technique to Enhance Local Antibiotic Concentrations

BACKGROUND

The use of antibiotic-loaded cement has become a well-accepted method to develop high local antibiotic concentrations in revision surgery of infected arthroplasty. A new surgical technique has been established to further increase the local antibiotic concentration and thereby minimizes the risk of reinfection. Our study aim was to investigate the safety of additional superficial vancomycin coating (SVC) by analyzing postoperative joint and serum vancomycin concentrations, as well as the creatinine levels of patients with orthopedic revision surgery.

METHODS

A longitudinal case series was performed by reviewing collected data of patients who were treated by SVC during revision surgery (1- or 2-stage exchange) because of prosthetic joint infections. Vancomycin levels were obtained, local from drains and systemic from blood samples, on postoperative days 1 to 5. Furthermore, preoperative and postoperative serum creatinine levels were analyzed.

RESULTS

Highest median local vancomycin levels were documented on postoperative day 1 with 546.8 μg/mL (range, 44.4-1485 μg/mL) in the reimplantation group and 408.7 μg/mL (range, 24.7-1650 μg/mL) in the spacer group. Median serum vancomycin level was 4.4 μg/mL (range, <2.0-11.7 μg/mL) on the first postoperative day in the reimplantation group and <2.0 μg/mL (range, <2.0-3.9 μg/mL) in the spacer group, and lower than 2.0 μg/mL (range, <2.0-7.5 μg/mL) from postoperative day 2 to 5 in both groups. Neither an anaphylactic reaction nor other side effects to SVC were observed.

CONCLUSION

Our data showed that SVC of bone cement is an effective technique to enhance local concentrations of vancomycin without leading to systemic side effects.

Paediatric diaphyseal forearm refractures after greenstick fractures: operative management with ESIN

BACKGROUND

One of the complications of forearm shaft fracture is refracture. Elastic stable intramedullary nailing represents an alternative method for refracture treatment to cast immobilisation for another five to seven weeks. Operative treatment often necessitates an open reduction in most cases due to blocked or narrowed medullary canals. The purpose of this study was to examine the expense of the operative procedure, technique (closed or open intramedullary nailing) and postoperative complications in diaphyseal forearm refractures.

METHODS

We retrospectively examined the expense of operative procedure in 21 children with diaphyseal forearm refractures treated with ESIN.

RESULTS

In 18 cases, closed reduction with nailing was possible; three required an open reduction. In nine patients a closed medullary cavity was present; only two of them needed an open reduction. None of the patients had complications (wound healing, osteomyelitis, rupture of the extensor pollicus longus). Swelling appeared in four patients, paraesthesia of the thumb in one. Free functional movement was achieved in all children. Long term results: No re-refracture occurred. One patient suffered from meteorosensitivity. Twelve are able to do the same sporting activities as before injury.

CONCLUSION

ESIN seems to be one choice for treatment in refracture of the forearm, as in most cases the operative reduction can be performed in a closed way by means of "tricks and hints".

Chondrocyte apoptosis enhanced at the growth plate: a physeal response to a diaphyseal fracture

Post-traumatic overgrowth of growing long bones is a common clinical phenomenon in paediatric traumatology and is the result of an enhanced stimulation of the nearby growth plate after fracture. To date, the exact post-fractural reactions of the growth plate are poorly understood. The aim of this study has been to determine the impact of fracture on the frequency of chondrocyte apoptosis of the growth plate. Rats sustained a mid-diaphyseal closed fracture of the left tibia or were left untreated. All animals were killed 3, 10, 14 or 29 days after trauma. The left and right tibiae were harvested and apoptotic chondrocytes of the proximal tibial growth plate were detected by TUNEL staining. The apoptosis percentage of physeal chondrocytes was statistically compared among fractured bones, intact contra-lateral bones and control bones. The physeal apoptosis rate of the fractured bone was significantly higher than that of the contra-lateral intact bone (valid for all evaluated days) and the control bone (valid from day 10 onwards). Contra-lateral intact tibiae never showed significantly higher apoptosis rates compared with control tibiae. Thus, mid-diaphyseal fracture influences the nearby growth plate by stimulating chondrocyte programmed cell death, which is associated with cartilage resorption and bone replacement. The lack of a significant difference between the intact contra-lateral and the intact control bone suggests that fracture only has a local effect that contributes to the greater apoptosis rate of the adjacent physis.