header advert
Results 1 - 9 of 9
Results per page:
Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_17 | Pages 70 - 70
24 Nov 2023
Roskar S Mihalic R Trebse R
Full Access

Aim

Prosthetic joint infection (PJI) represents the second most frequent complication of total joint arthroplasty (TJA) with up to 20% of low-grade PJI treated as aseptic failure. Sensitive diagnostic criteria have been provided by EBJIS. However, to date there is no single test to reliably diagnose all PJIs. Studies of Mazzucco et al. and Fu et al. suggest that synovial fluid (SF) viscosity could be considered as an important marker for PJI. The primary aim of our study was to determine if SF viscosity is a more reliable diagnostic criterion of PJI than the SF cell count with differential (CCD), and the combined diagnostic value of SF viscosity and CCD.

Method

We prospectively analysed the viscosity of SF samples obtained during TJA of hip and knee revisions. We sampled 2.5–5mL of SF for viscosity and CCD. Intraoperatively, 1mL of the sample was analysed for the CCD. The remaining SF was centrifuged for 4min at 7000rpm. The viscosity of the supernatant was determined on Ostwald viscometer as the time required to pass the viscometer at 20°C. During each surgery at least 5 microbiological and multiple histopathological samples were harvested, and explant sonication was performed. The diagnosis was based on EBJIS definition. The viscosity threshold for detecting PJI was set at 65 seconds.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_10 | Pages 69 - 69
1 Oct 2022
Roskar S Mihalic R Mihelic A Trebse R
Full Access

Aim

Debridement, antibiotics and implant retention (DAIR) are considered as an optimal curative treatment option for prosthetic joint infection (PJI) when the biofilm is still immature and radical debridement is achievable. There are two main groups of patients suitable for DAIR. Those with an early acute PJI and patients with acute hematogenous PJI. However, there is also a third group of early PJI resulting from a wound healing problem or leaking hematoma. These may be either high or low grade depending on the microorganisms that infected the artificial joint “per continuitatem”.

Methods

We retrospectively analysed 100 successive DAIR procedures on prosthetic hip and knee joints performed between January 2010 and January 2022, from total of 21000 primary arthroplasties implanted within the same time period. We only included PJI in primary total replacements with no previous surgeries on the affected joint. Patients data (demographics, biochemical, microbiological, histopathological results, and outcomes) were collected from hospital bone and joint infection registry. The aim of surgery was radical debridement and the mobile parts exchange. The standardized antibiotic regime based on antibiofilm antibiotics.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_15 | Pages 32 - 32
1 Dec 2021
Mihalic R Zdovc J Brumat P Trebse R
Full Access

Aim

The cut-off values for synovial fluid leukocyte count and neutrophils differential (%PMN) for differentiating aseptic from septic failure in total knee arthroplasties were already defined in the past. Our goal was to determine the cut-off values for synovial fluid leukocyte count and %PMN in failed total hip arthroplasties (THA).

Method

Patients undergoing revision THA were prospectively included. In perioperative assessment phase, synovial fluid leukocyte count and %PMN were determined. During the surgery, at least 4 intraoperative samples for microbiological and one for histopathological analysis were obtained. Infection was defined as presence of sinus tract, inflammation in histopathological samples, and ≥2 tissue and/or synovial fluid samples growing the same microorganism. Exclusion criteria were systemic inflammatory diseases, revision surgery performed less than 3 months from index surgery and insufficient tissue sampling. Receiver operating characteristic (ROC) curves were constructed to assess the diagnostic performance and Youden's J statistic was computed to identify optimal cut-off values.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_15 | Pages 36 - 36
1 Dec 2021
Roskar S Mihalic R Trebse R
Full Access

Aim

Prosthetic joint infection (PJI) presents the second most common complication of total joint arthroplasty (TJA). Accumulating evidence suggests that up to 20% of aseptic failures are low-grade PJI. However, there is still no single test to reliably diagnose all PJI. In his thesis, Mazzucco emphasized the viscosity differences between normal, osteoarthritic, and rheumatic synovial fluid. Similarly, a recent study by Fu et al. reported significantly lower viscosity in patients with PJI compared to the aseptic failure cohort. The primary aim of our study was to determine whether synovial fluid viscosity is a more reliable diagnostic criterion for PJI compared to the synovial fluid cell count with differential and serum C-reactive protein (CRP) levels.

Method

We prospectively analyzed the viscosity of synovial fluid samples obtained during TJA of hip and knee joint revision procedures. We sampled 2.5–5 mL of synovial fluid for viscosity measurement. The samples were centrifuged (4 min at 7000 rpm) and the resulting supernatant was immediately transferred into the Ostwald viscometer. Viscosity was derived from the time required for a given volume of synovial fluid to pass the viscometer at 20 °C. The synovial fluid samples were also analysed for their cell count with differential and serum CRP was measured. The definite diagnosis of PJI was established on basis of EBJIS criteria. For the viscosity, the threshold for detecting PJI was set at 65 seconds.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_5 | Pages 6 - 6
1 Mar 2021
Mihalic R Zdovc J Brumat P Trebse R
Full Access

Aim

One of the most accurate and inexpensive tests in detection of prosthetic joint infection (PJI) is synovial fluid white blood cell (WBC) count and differential. Since leukocytes produce many different interleukins (IL) in situation of PJI, we hypothesized that ILs could be even more accurate in detection of PJI. The aim of the study was to test, if the synovial fluid IL-6 level is superior to WBC count and differential in detection of PJI.

Methods

Unselected patients undergoing total hip or knee revision surgery were prospectively included. In perioperative assessment phase, WBC count, differential and IL-6 levels of synovial fluid were measured. Patients were labelled as positive or negative according to the predefined cut-off values for IL-6 (230pg/ml) and WBC count with differential (1,7 × 109 WBC/ml with ≥65% of granulocytes). During the surgery, at least 4 intraoperative samples for microbiological and one for histopathological analysis were obtained. PJI was defined as presence of sinus tract, inflammation in histopathological samples, and growth of the same microorganism in at least two or more samples of periprosthetic tissue or synovial fluid. Binary diagnostic test was performed to check the diagnostic strength of both methods in detection of PJI.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 11 - 11
1 Mar 2017
Mohar J Knez D Cirman R Trebse R Mihalic R Vrtovec T
Full Access

Summary

Optimum position of pedicle screws can be determined preoperatively by CT based planning. We conducted a comparative study in order to analyse manually determined pedicle screw plans and those that were obtained automatically by a computer software and found an agreement in plans between both methods, yet an increase in fastening strengths was observed for automatically obtained plans.

Hypothesys

Automatic planning of pedicle screw positions and sizing is not inferior to manual planning


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_9 | Pages 45 - 45
1 May 2016
Mihalic R Trebse R
Full Access

Background

Total hip arthroplasty (THA) is one of the most successful surgical procedures ever performed. Nevertheless if procedure is performed by high or low volume surgeons; more than 50% of cups are still placed out of the safe zone, which is connected to lower survival rate of the prosthesis. The idea was to develop an imageless navigation system for safe and accurate positioning of the cup in THA procedures, without a need of any preoperative computer tomography (CT) or magnetic resonance imagining (MRI).

Methods

The validation of the system was approved by National Ethics Committee. The committee allowed the validation on 10 patients who all signed the agreement for participation in the study. Unselected patients undergoing THA were included. All patients had had performed preoperative x-rays of pelvis and hips for standard preoperative planning. Immediately before skin incision, anterior pelvic plane (APP) was defined with help of specially developed electromagnetic navigation system (Guiding Star, E-Hip module, Ekliptik d.o.o., Ljubljana, Slovenia) and specificaly designed hardware tool which is essential for accurate APP determination [Fig.1]. In all patients THAs were performed through direct lateral approach and all implanted components (Allofit S cup and Alloclassic stem, Zimmer Inc., Warsaw, Indiana, USA) were implanted with freehand technique according to preoperative plan. After placement of the cups their inclination and anteversion angles were determined with aforementioned navigation system [Fig. 2]. The day after surgery, low dose CT scans of pelvises of operated patients were performed and DICOM format files were up-loaded into EBS software (Ekliptik d.o.o., Ljubljana, Slovenia), a multipurpose application for perioperative planning, measuring and constructing where virtual copies of pelvises were generated. On virtual pelvises the position of the cups was measured by independent person [Fig.3]. Measurements were compared, statistically analysed and the deviation calculated with root mean square error (RMSE) method. Afterwards the average error (eaver) and standard deviation (σ) between intraoperatively determined and postoperatively measured angles were calculated.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 426 - 426
1 Dec 2013
Mihalic R Trebe R Kreuh D
Full Access

Background

Periacetabular osteotomy (PAO) is an effective treatment method for early or mild osteoarthritis caused by developmental dysplasia of the hip. Since the procedure is performed from late eighties of the past century it is still a very demanding procedure performed only by high skilled surgeons in high volume orthopaedic centres. The idea was to develop a custom-made surgical tool to improve the accuracy of the two osteotomies of the iliac bone and help us to avoid inadvertent intraarticular osteotomy of the acetabulum.

Methods

Firstly CT scans of pelvises of two cadavers were performed. The DICOM format files were up-loaded into EBS software (Ekliptik d.o.o., Ljubljana, Slovenia), application for preoperative planning, constructing and designing different templates, where the three-dimensional (3D) model of each pelvis was created. On the virtual pelvis models the PAO lines on each of four acetabuls were placed and virtual PAOs were performed [Fig. 1]. For the execution of the two iliac bone osteotomies the osteotome or saw guiding jigs were virtually created and exported in STL format in ProJet 3500 HDPlus printer which created custom made jigs made from VisiJet Crystal biocompatible plastic material (3D systems, Rock Hill, South Carolina, USA) for each of the four acetabula. The next step was the surgery on aforementioned cadavers. Extended Smith-Petrson approach was performed on each of four cadaveric hips and Bernese PAOs were performed using custom-made jigs. After performing the acetabular correction the cadavers were carefully dissected to study any possible posterior column damage or damage of the acetabular wall. None of them were damaged and the osteotomies were performed according to the virtual plan.

Next step was the real procedure on 47-years old female patient with bilateral acetabular dysplasia. The procedure was executed on right side using the extended Smith-Peterson approach. Preoperatively native X-ray of both hips and the CT scan of pelvis were performed. According the CT scan (DICOM format) the virtual 3D model of the pelvis was created and virtual osteotomy lines were decided and production of the appropriate jig was manufactured in the same manner as for the cadavers [Fig. 2]. Preoperative and postoperative centre-edge (CE) angles were measured.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_IV | Pages 608 - 608
1 Oct 2010
Mihalic R Tercic D Trampuz A Trebse R
Full Access

Background: Preoperative aspiration of synovial fluid is not always possible. Intraoperative collection of synovial fluid for determination of cell count and differential may be a useful approach for diagnosing or excluding prosthetic joint infection (PJI). However, the value and accuracy of synovial fluid collected during surgery has not yet been prospectively investigated. We analysed intraoperatively collected synovial fluid cell count for rapid and accurate diagnosis of PJI.

Methods: Unselected patients undergoing total hip or knee revision surgery from 06/06-05/08 were prospectively included. During surgery, synovial fluid was collected for determination of cell count; the cut-off value for PJI was > 1700 leucocytes/mm3 and/or > 65% neutrophils (according to Am J Med2004;117:556). In addition, 6 intraoperative samples were obtained for microbiology and 1 for histopathology. PJI was defined as presence of intraoperative pus, acute inflammation in histopathology, or ≥2 tissue samples growing the same organism.

Results: 59 patients (median age, 69 years; 68% females) with hip (n = 41) and knee (n = 18) prostheses were included, of whom 20 (34%) had PJI. Synovial fluid cell counts were true-positive in 16, true–negative in 38, false–positive in 1 and false–negative 4 patients. Sensitivity of synovial fluid cell count was 80%, specificity 97%, positive and negative predictive values were 94% and 90%, respectively.

Conclusion: The intraoperative synovial fluid cell count analysis is a rapid, inexpensive and reliable test for predicting or excluding PJI, having a ≥90% positive and negative predictive value. This test may be used for making operative decisions during surgery.