Acidity Is an Excellent Marker of Infection in Hip and Knee Arthroplasty.

BACKGROUND: The diagnosis of joint replacement infection is a difficult clinical challenge that often occurs when the implant cannot be salvaged. We hypothesize that the pH value of synovial fluid could be an important indicator of the inflammatory status of the joint. However, in the literature, there is a lack of data on the pH changes in hip and knee joint replacements and their relation to infection and implant failure. In this study, we aimed to measure the pH levels of synovial fluid in patients with hip and knee joint replacements. We also investigated the potential of pH measurement as a diagnostic tool for joint replacement infection. In this study, we recorded the pH values to be 7.55 and 7.46 in patients where Pseudomonas aeruginosa was identified as the cause of the prosthetic joint infection. We attribute this to the different environments created by this specific bacterium. In other cases where the pH was higher, chronic mitigated infections were diagnosed, caused by strains of Staphylococcus aureus, Streptococcus agalactiase, and coagulase negative staphylococcus. MATERIALS AND METHODS: In our cohort of 155 patients with implanted hip (THA; n = 85) or knee (TKA; n = 70) joint replacements, we conducted a prospective study with a pH measurement. Out of the whole cohort, 44 patients had confirmed joint replacement infection (28.4%) (44/155). In 111 patients, infection was ruled out (71.6%) (111/155). Joint replacement infection was classified according to the criteria of the Musculoskeletal Infection Society (MSIS) from 2018. Based on the measured values, we determined the cut-off level for the probability of ongoing inflammation. We also determined the sensitivity and specificity of the measurement. RESULTS: The group of patients with infection (n = 44) had a significantly lower synovial fluid pH (pH = 6.98 ± 0.48) than the group of patients with no infection (n = 111, pH = 7.82 ± 0.29, p < 0.001). The corresponding median pH values were 7.08 for the patients with infection and 7.83 for the patients with no infection. When we determined the cut-off level of pH 7.4, the sensitivity level of infected replacements was 88.6%, and the specificity level of the measurement was 95.5%. The predictive value of a positive test was 88.6%, and the predictive value of a negative test was 95.5%. CONCLUSIONS: Our results confirm that it is appropriate to include a pH measurement in the diagnostic spectrum of hip and knee replacements. This diagnostic approach has the potential to provide continuous in vivo feedback, facilitated by specialized biosensors. The advantage of this method is the future incorporation of a pH-detecting sensor into intelligent knee and hip replacements that will assess pH levels over time. By integrating these biosensors into intelligent implants, the early detection of joint replacement infections could be achieved, enhancing proactive intervention strategies.

Eye tracking: empirical foundations for a minimal reporting guideline.

In this paper, we present a review of how the various aspects of any study using an eye tracker (such as the instrument, methodology, environment, participant, etc.) affect the quality of the recorded eye-tracking data and the obtained eye-movement and gaze measures. We take this review to represent the empirical foundation for reporting guidelines of any study involving an eye tracker. We compare this empirical foundation to five existing reporting guidelines and to a database of 207 published eye-tracking studies. We find that reporting guidelines vary substantially and do not match with actual reporting practices. We end by deriving a minimal, flexible reporting guideline based on empirical research (Section "An empirically based minimal reporting guideline").

A comparison of the performance on extrinsic and intrinsic cartographic visualizations through correctness, response time and cognitive processing.

The aim of this study was to compare the performance of two bivariate visualizations by measuring response correctness (error rate) and response time, and to identify the differences in cognitive processes involved in map-reading tasks by using eye-tracking methods. The present study is based on our previous research and the hypothesis that the use of different visualization methods may lead to significant cognitive-processing differences. We applied extrinsic and intrinsic visualizations in the study. Participants in the experiment were presented maps which depicted two variables (soil moisture and soil depth) and asked to identify the areas which displayed either a single condition (e.g., "find an area with low soil depth") or both conditions (e.g., "find an area with high soil moisture and low soil depth"). The research sample was composed of 31 social sciences and humanities university students. The experiment was performed under laboratory conditions, and Hypothesis software was used for data collection. Eye-tracking data were collected for 23 of the participants. An SMI RED-m eye-tracker was used to determine whether either of the two visualization methods was more efficient for solving the given map-reading tasks. Our results showed that with the intrinsic visualization method, the participants spent significantly more time with the map legend. This result suggests that extrinsic and intrinsic visualizations induce different cognitive processes. The intrinsic method was observed to generally require more time and led to higher error rates. In summary, the extrinsic method was found to be more efficient than the intrinsic method, although the difference was less pronounced in the tasks which contained two variables, which proved to be better suited to intrinsic visualization.

Six year results of the Rebalance mobile bearing total ankle replacement.

BACKGROUND: We report the outcomes of a prospective consecutive series of 267 total ankle replacements (TARs) using a new mobile bearing Rebalance® prosthesis. METHODS: Between April 2011 and December 2018, 267 consecutive Rebalance® prostheses were implanted in 255 patients at 3 different centers. Estimated survival curves with 95% confidence intervals were produced with the Kaplan-Meier method. 110 ankles were followed for at least 5 years and clinical and radiological outcomes were assessed in 92 of these ankles. RESULTS: Twenty-one ankles were revised at a mean of 34 (7-60) months. The estimated survival was 90% (95% CI 86-95) at 5 years and 88.3% (95% CI 83.-94 at 6 years. The ankles followed for at least 5 years demonstrated a median Likert score of 1 (1-4). Radiolucent zones were detected in 14% and osteolytic cysts in 3%. CONCLUSION: The survival rate of the Rebalance prosthesis conforms with other reports of similar designs. The satisfaction rate was high. Radiological zones and osteolytic cysts were found at a lower rate than usually reported for mobile bearing TARs. These results favour further use of this implant.

The change of first metatarsal head articular surface position after Lapidus arthrodesis.

BACKGROUND: The Lapidus procedure has been used for hallux valgus deformity correction since 1931. In some cases, the arthrodesis results in an unfavourable lateral inclination of first metatarsal head articular surface. The objective of our study was to evaluate the change of orientation of this articular surface in relation to the second metatarsal axis by comparing pre- and postoperative radiographs. The secondary target was to evaluate possible benefits of combination of Lapidus and Akin procedures in the reduction of hallux valgus deformity. METHODS: We evaluated 449 pre- and postoperative radiographs of 134 operations from 2010 to 2015. Routinely used angle measurements were performed on all X-rays. A sum of tangential angle to the second axis and distal articular set angle values was chosen as the best indicator for the deformity correction success. RESULTS: The mean value of these angles total was 5.2° ±9.3° before and 14.2° ±7.8° after the operation. In the group of patients, where the additional Akin osteotomy was used, the mean value was 5.3° ±8.4° before and 6.9° ±10.2° after the surgery. The mean difference in values between the two groups (with and without Akin procedure) was 7.3° of extra correction in favour of the group with the Akin osteotomy. CONCLUSIONS: The mean worsening of the tangential angle after Lapidus operation was 6.1° ±6.9°, which counts for significant deterioration after a surgery. The Akin osteotomy was found to be a valuable addition to the Lapidus arthrodesis, which improves the position of articular surfaces in first metatarsophalangeal joint.

Eye-tracking Analysis of Interactive 3D Geovisualization.

This paper describes a new tool for eye-tracking data and their analysis with the use of interactive 3D models. This tool helps to analyse interactive 3D models easier than by time-consuming, frame-by-frame investigation of captured screen recordings with superimposed scanpaths. The main function of this tool, called 3DgazeR, is to calculate 3D coordinates (X, Y, Z coordinates of the 3D scene) for individual points of view. These 3D coordinates can be calculated from the values of the position and orientation of a virtual camera and the 2D coordinates of the gaze upon the screen. The functionality of 3DgazeR is introduced in a case study example using Digital Elevation Models as stimuli. The purpose of the case study was to verify the functionality of the tool and discover the most suitable visualization methods for geographic 3D models. Five selected methods are presented in the results section of the paper. Most of the output was created in a Geographic Information System. 3DgazeR works with the SMI eye-tracker and the low-cost EyeTribe tracker connected with open source application OGAMA, and can compute 3D coordinates from raw data and fixations.

EyeTribe Tracker Data Accuracy Evaluation and Its Interconnection with Hypothesis Software for Cartographic Purposes.

The mixed research design is a progressive methodological discourse that combines the advantages of quantitative and qualitative methods. Its possibilities of application are, however, dependent on the efficiency with which the particular research techniques are used and combined. The aim of the paper is to introduce the possible combination of Hypothesis with EyeTribe tracker. The Hypothesis is intended for quantitative data acquisition and the EyeTribe is intended for qualitative (eye-tracking) data recording. In the first part of the paper, Hypothesis software is described. The Hypothesis platform provides an environment for web-based computerized experiment design and mass data collection. Then, evaluation of the accuracy of data recorded by EyeTribe tracker was performed with the use of concurrent recording together with the SMI RED 250 eye-tracker. Both qualitative and quantitative results showed that data accuracy is sufficient for cartographic research. In the third part of the paper, a system for connecting EyeTribe tracker and Hypothesis software is presented. The interconnection was performed with the help of developed web application HypOgama. The created system uses open-source software OGAMA for recording the eye-movements of participants together with quantitative data from Hypothesis. The final part of the paper describes the integrated research system combining Hypothesis and EyeTribe.

Medial calcar of proximal humeral fracture as landmark in restoration of humeral length in case of hemiarthroplasty.

PURPOSE: Several methods to restore the appropriate length of the humerus in the case of proximal humeral fractures treated by hemiarthroplasty have been previously published. Our study evaluates the possibility of using the medial calcar of humerus for humeral length reconstruction not based on preoperative planning. METHODS: Preparations of 320 dry humeral bones were used for the purpose of the study. Points of interest were marked on each bone: the most proximal point of the humeral head, the crest of greater tuberosity, diameters of the head, the anatomical and surgical necks. Proximal parts of bones were then scanned from two angles with a digital camera and all measurements were performed on calibrated photographs. We compared accuracy in humeral length reconstruction using insertion of the pectoralis major and the area of medial calcar where usually a fracture develops. RESULTS: The distance between the top part of the humeral head and the insertion of pectoralis major was 54.1 ± 6.0 mm. The distance between the lateral margin of the anatomical neck and the medial calcar was 51.4 ± 4.3 mm. We compared these data with diameters of the humeral head. CONCLUSIONS: The site of the fracture can be used for the reconstruction of the humeral length with greater accuracy than area of the pectoralis major insertion. We suggest that to obtain the final distance between the lateral margin of the artificial head and medial calcar of the fracture 2-3 mm should be added to the diameter of the head.

Lateral release in hallux valgus deformity: from anatomic study to surgical tip.

The important part of hallux valgus deformity operations, especially in the case of an incongruent joint, is the release of the soft tissue on the lateral side of the first metatarsophalangeal joint. The purpose of the present anatomic study was, with preparation of the lateral structures of the joint and lateral conjoined tendon, to provide a background for a surgical tip of the release of the joint for an additional metatarsal osteotomy. For the present study, we used 30 specimens (15 left and 15 right) from 19 cadavers at the Institute of Anatomy, First Faculty of Medicine, Charles Faculty (Prague, Czech Republic). Only specimens that met the criteria of hallux valgus were included in the present study. The technique was based on the incision of the lateral sesamoid ligament and partial tenotomy of the lateral conjoined tendon from the first interdigital web space. The release was done gradually with supination and abduction of the big toe to achieve the smallest size of the tenotomy. The median of the tenotomy size of the conjoined tendon was 6.5 (range 5 to 14) mm. The median size of the conjoined tendon in the frontal plane just ventral to the sesamoid bone was 10.6 (range 8 to 14) mm. The technique of the release, in which the big toe was abducted and supinated, can minimize the size of the lateral conjoined tendon release and can minimize the possibility of a postoperative deformity.

Hypermobility of the first metatarsal bone in patients with rheumatoid arthritis treated by Lapidus procedure.

BACKGROUND: Foot deformities and related problems of the forefoot are very common in patients with rheumatoid arthritis. The laxity of the medial cuneometatarsal joint and its synovitis are important factors in the development of forefoot deformity. The impaired joint causes the first metatarsal bone to become unstable in the frontal and sagittal planes. In this retrospective study we evaluated data of patients with rheumatoid arthritis who underwent Lapidus procedure. We evaluated the role of the instability in a group of patients, focusing mainly on the clinical symptoms and X-ray signs of the instability. METHODS: The study group included 125 patients with rheumatoid arthritis. The indications of the Lapidus procedure were a hallux valgus deformity greater than 15 degrees and varus deformity of the first metatarsal bone with the intermetatarsal angle greater than 15 degrees on anterio-posterior weight-bearing X-ray. RESULTS: Data of 143 Lapidus procedures of 125 patients with rheumatoid arthritis, who underwent surgery between 2004 and 2010 was evaluated. Signs and symptoms of the first metatarsal bone instability was found in 92 feet (64.3%) in our group. The AOFAS score was 48.6 before and 87.6 six months after the foot reconstruction. Nonunion of the medial cuneometatarsal joint arthrodesis on X-rays occurred in seven feet (4.9%). CONCLUSION: The Lapidus procedure provides the possibility to correct the first metatarsal bone varus position and its instability, as well as providing the possibility to achieve a painless foot for walking. We recommend using the procedure as a preventive surgery in poorly symptomatic patients with rheumatoid arthritis in case of the first metatarsal bone hypermobility.

Ankle block implemented through two skin punctures.

BACKGROUND: Recently, peripheral nerve blocks have increasingly been used in orthopedic surgery. The foot block is an alternative for anesthesia in cases of forefoot and midfoot operations. We propose a modification of the block technique due to potential difficulties concerning the tibial nerve. MATERIALS AND METHODS: The spatial position of the tibial nerve in the neurovascular bundle, proximal to entering the tarsal tunnel and sural nerve behind lateral malleolus was measured on 60 dissected preparations. Modification of the block technique was proposed. A tibial nerve block was administered by inserting a needle, at an area above the upper edge of the heel bone, tangential to the Achilles tendon. The needle was then withdrawn and redirected to the frontal plane and inserted through the tissue, anterior to the Achilles tendon and laterally behind the lateral malleolus to block the sural nerve. A block of the saphenous nerve superficial and deep peroneal nerves was implemented by needle insertion subcutaneously two centimeters proximal to the crest of the ankle joint. The technique was then evaluated in the clinical part of the study in 84 operative procedures. RESULTS: The tibial nerve is located 21.1 mm +/- 2.1 mm from the medial aspect of the Achilles tendon and 11.6 mm +/- 1.3 mm deep in the neurovascular bundle. The distance from the posterior margin of the lateral malleolus to the sural nerve is 18.3 mm +/- 1.9 mm. We achieved a 93% success rate in implementation of the complete foot block in 84 operations. CONCLUSION: The technique, proposed in the anatomical portion of the study and evaluated in the clinical part, had a similar success rate when compared to techniques published in the literature. Though comparable to currently used techniques, this technique provides easier positioning of a patient and a complete block of the foot can be done with two skin injection sites.

Isolated talonavicular arthrodesis in patients with rheumatoid arthritis of the foot and tibialis posterior tendon dysfunction.

BACKGROUND: The foot is often affected in patients with rheumatoid arthritis. Subtalar joints are involved more frequently than ankle joints. Deformities of subtalar joints often lead to painful flatfoot and valgus deformity of the heel. Major contributors to the early development of foot deformities include talonavicular joint destruction and tibialis posterior tendon dysfunction, mainly due to its rupture. METHODS: Between 2002 and 2005 we performed isolated talonavicular arthrodesis in 26 patients; twenty women and six men. Tibialis posterior tendon dysfunction was diagnosed preoperatively by physical examination and by MRI. Talonavicular fusion was achieved via screws in eight patients, memory staples in twelve patients and a combination of screws and memory staples in six cases. The average duration of immobilization after the surgery was four weeks, followed by rehabilitation. Full weight bearing was allowed two to three months after surgery. RESULTS: The mean age of the group at the time of the surgery was 43.6 years. MRI examination revealed a torn tendon in nine cases with no significant destruction of the talonavicular joint seen on X-rays. Mean of postoperative followup was 4.5 years (3 to 7 years). The mean of AOFAS Hindfoot score improved from 48.2 preoperatively to 88.6 points at the last postoperative followup. Eighteen patients had excellent results (none, mild occasional pain), six patients had moderate pain of the foot and two patients had severe pain in evaluation with the score. Complications included superficial wound infections in two patients and a nonunion developed in one case. CONCLUSIONS: Early isolated talonavicular arthrodesis provides excellent pain relief and prevents further progression of the foot deformities in patients with rheumatoid arthritis and tibialis posterior tendon dysfunction.

Lesser tuberosity is more reliable than bicipital groove when determining orientation of humeral head in primary shoulder arthroplasty.

PURPOSE: The objective of the study was to provide statistical evaluation of position of bone landmarks of proximal humerus in relation to transepicondylar line and find out which one is the most suitable for setup of the head retroversion in case of humeral head destruction. METHODS: We measured 185 dry humeral preparations (92 left, 93 right). Structures of interest on the proximal humerus were marked with pointers of custom made steel frame. Angular relationships between the humeral head axis and medial margin of the greater tuberosity, lateral margin of the lesser tuberosity, bicipital groove, and crest of the greater tuberosity were evaluated with respect to intramedullary axis of the proximal humeral shaft. RESULTS: The angle between the humeral head axis and medial margin of greater tuberosity was 11.5 +/- 9.0 degrees , the angle between the lateral margin of the lesser tuberosity and the axis was 47.5 +/- 7.4 degrees , the angle between the bicipital groove and the axis was 31.6 +/- 8.8 degrees at the level of the humeral head. The angle between the crest of the greater tuberosity and the axis was 26.6 +/- 9.6 degrees in plane of the surgical neck. CONCLUSIONS: We statistically proved that the lateral margin of lesser tuberosity is more reliable than the bicipital groove; medial margin of the greater and transepicondylar line for reconstruction of humeral head retroversion. We suggest that the lesser tuberosity should be used to determine the retroversion, especially in cases when the margin of humeral head was destructed.

Attachments of muscles as landmarks for implantation of shoulder hemiarthoplasty in fractures.

BACKGROUND: The attachments of muscles and the position of the humeral head are important for a good functional outcome of shoulder hemiarthroplasties after displaced fractures of the proximal humerus. Deviations in the attachments and changes in their spatial position with respect to the humeral head during surgical reconstruction change the biomechanics and reduce the range of motion of the should joint postoperatively. METHODS AND RESULTS: We used 198 humerus preparations and using 3-dimensional analysis measured the angular relationships between the humeral head axis and medial margin of the greater tuberosity (11.9 degrees +/- 9.1 degrees ), lateral margin of the lesser tuberosity (48.0 degrees +/- 7.8 degrees ), and the crest of the greater tuberosity (27.1 degrees +/- 9.6 degrees ). CONCLUSION: This study provides average values of the positions of the greater and lesser tuberosities with respect to the humeral head axis. We show that the greater and lesser tuberosities are more reliable than the transepicondylar line for reconstruction of humeral head retroversion. LEVEL OF EVIDENCE: Basic Science.

Expression of heat shock protein receptors on fibroblast-like synovial cells derived from rheumatoid arthritis-affected joints.

We examined the membrane expression of inducible Hsp70 and HSP receptors like TLR2, TLR4, CD14, CD36, CD40 and CD91 on fibroblast-like synovial cells (SC) derived from synovial tissue in 23 patients with rheumatoid arthritis (RA), who underwent synovectomy by using flow cytometric analysis. For comparison, autologous skin fibroblasts (SF) derived from the operation wound were tested. Significantly higher Hsp70 expression was found on synovial cells than on skin fibroblasts (median SC 21.4% x SF 5.0%, P < 0.001). Both synovial cells and skin fibroblasts expressed high levels of cell surface CD91 (median SC 80.2% x SF 79.2%), however, no or low levels of CD14, CD40, TLR2, TLR4 and CD36. Further, we observed high co-expression of CD91 and Hsp70 on RA synovial cells (median 18.6%), while skin fibroblasts showed only background Hsp70 expression (median 3.9%, P < 0.001). Since we demonstrated the high prevalence of inducible Hsp70 in RA synovial fluids, we speculate that Hsp70 might be captured onto the membrane of synovial cells from the extracellular space via the CD91 receptor. The significance of the Hsp70 interaction with synovial cells via CD91 remains undefined, but may mediate other non-immune purposes.