Unilateral Prostheses Research Articles

Quantitative analysis of metal artifact reduction in total hip arthroplasty using virtual monochromatic imaging and orthopedic metal artifact reduction, a phantom study

ObjectiveTo quantify metal artifact reduction using 130 keV virtual monochromatic imaging (VMI) with and without orthopedic metal artifact reduction (O-MAR) in total hip arthroplasty.MethodsConventional polychromatic images and 130 keV VMI of a phantom with pellets representing bone with unilateral or bilateral prostheses were reconstructed with and without O-MAR on a dual-layer CT. Pellets were categorized as unaffected, mildly affected and severely affected.ResultsWhen 130 keV VMI with O-MAR was compared to conventional imaging with O-MAR, a relative metal artifact reduction in CT values, contrast-to-noise (CNR), signal-to-noise (SNR) and noise in mildly affected pellets (67%, 74%, 48%, 68%, respectively; p < 0.05) was observed but no significant relative metal artifact reduction in severely affected pellets. Comparison between 130 keV VMI without O-MAR and conventional imaging with O-MAR showed relative metal artifact reduction in CT values, CNR, SNR and noise in mildly affected pellets (92%, 72%, 38%, 51%, respectively; p < 0.05) but negative relative metal artifact reduction in CT values and noise in severely affected pellets (− 331% and -223%, respectively; p < 0.05), indicating aggravation of metal artifacts.ConclusionOverall, VMI of 130 keV with O-MAR provided the strongest metal artifact reduction.

CT evaluation for sarcopenia involving the psoas and paravertebral muscles in patients with total hip arthroplasty.

Computed tomography (CT) has been validated in diagnosing sarcopenia in various clinical conditions. To evaluate the core abdominal muscles in terms of sarcopenia in patients with total hip arthroplasty (THA) with and without complication. Retrospective analysis of patients with a pelvic CT revealed 145 consecutive patients with THA. Also, 118 consecutive cases with normal CT scans constituted the control group. The area and density measurements of bilateral psoas (PSA, psoas area; PSD, psoas density) and paravertebral (PVA, paravertebral area; PVD, paravertebral density) muscles were performed at the level of L3 or L4 vertebrae regardless of prosthesis side. All measurements were evaluated in normal cases and in patients with THA, as well as in patients with complicated prostheses. In the whole population and subgroup of patients with bilateral THA, bilateral PSA, PSD, and PVD but not the PVA were lower in patients with THA compared to controls (all p < 0.01). In patients with unilateral prostheses, ipsilateral PSA, PSD, and bilateral PVD but not the PVA were lower compared to controls (all p < 0.01). Furthermore, in patients with unilateral prostheses with complication, only ipsilateral PSD was lower compared to patients with unilateral prostheses without complication (all p < 0.05) and in patients with bilateral prostheses with complication, bilateral PSA, PSD, and PVD but not the PVA were lower compared to patients with bilateral prostheses without complication (all p < 0.05). Sarcopenia indicated by the area and density measurements of core abdominal muscles can be associated with the presence and complication of hip prostheses.

Metal ion levels in the blood of patients with metal-on-metal hip prostheses.

A BHR (Birmingham hip resurfacing) prosthesis was implanted in 445people in Norway. Adverse reactions can arise as a result of the release of metal ions from metal-on-metal joint surfaces made from cobalt-chromium alloy. The aim of the study was to analyse the release of metal ions during the first five years after surgery in patients with a BHR prosthesis and to investigate whether this was linked to clinical complications. Forty-four male patients (median age 53 years) implanted with a BHR prosthesis at the Coastal Hospital at Hagevik in the period October 2009 to May 2013 were monitored by means of blood samples before implantation and three months, one year, three years and five years afterwards. Analyses of cobalt and chromium in whole blood were performed. Function scoring was used to clinically assess the prosthetic joint. Metal ion concentrations increased between the surgery date and one year later (p < 0.001), and subsequently remained stable. After five years, the median concentrations (min.- max.) of cobalt and chromium were 1.1 µg/L (0.4-6.3 µg/L) and 1.4 µg/L (0.4-11.7 µg/L) respectively for unilateral prostheses (n = 36), and 2.3 µg/L (1.6-28.5 µg/L) and 2.6 µg/L (1.7-14.1 µg/L) respectively for bilateral prostheses (n = 8). Five patients underwent revision surgery, while other patients had good hip function. Patients with a BHR prosthesis had a significant increase in cobalt and chromium in their blood one to five years after surgery, but the median levels were still well below the threshold value of 7 μg/L, which indicates an increased risk of complications.

Metal Artifact Reduction for Orthopedic Prosthesis in Lower Extremity CT Venography: Evaluation of Image Quality and Vessel Conspicuity

This study evaluates the image quality of lower extremity CT venography reconstructed with orthopedic metal artifact reduction (O-MAR) in patients with unilateral or bilateral metallic prostheses in the hip or knee. This retrospective study was approved by our institutional review board, and informed consent was waived. Twenty-nine patients of lower extremity CT with 51 metallic hip or knee prostheses were reconstructed to both standard CT images and O-MAR images. The subjective image quality and vessel conspicuity for both images were evaluated by two readers using five-point scales (0-4). Vessel conspicuity scores of 3 or 4 were considered diagnostically acceptable. Image noise was measured in the air and subcutaneous fat. O-MAR images showed significantly higher scores of subjective image quality (p < .001) and vessel conspicuity (p = .002) than standard CT images. Diagnostic acceptance of vessel conspicuity was not significantly different between O-MAR images and standard CT images (p = 1.000). O-MAR images showed significantly less image noise than conventional CT images (p < .001 for both air and subcutaneous fat). O-MAR may be an effective solution for the metal artifacts in lower extremity CT venography; however, the distance between prostheses and vessels affects the diagnostic acceptance in patients with metallic hip or knee prostheses. Level 4, Case Series.

Is the synovial fluid cobalt-to-chromium ratio related to the serum partitioning of metal debris following metal-on-metal hip arthroplasty?

ObjectivesWe investigated the reliability of the cobalt-chromium (CoCr) synovial joint fluid ratio (JFR) in identifying the presence of a severe aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) response and/or suboptimal taper performance (SOTP) following metal-on-metal (MoM) hip arthroplasty. We then examined the possibility that the CoCr JFR may influence the serum partitioning of Co and Cr.MethodsFor part A, we included all revision surgeries carried out at our unit with the relevant data, including volumetric wear analysis, joint fluid (JF) Co and Cr concentrations, and ALVAL grade (n = 315). Receiver operating characteristic curves were constructed to assess the reliability of the CoCr JFR in identifying severe ALVAL and/or SOTP. For part B, we included only patients with unilateral prostheses who had given matched serum and whole blood samples for Co and Cr analysis (n = 155). Multiple regression was used to examine the influence of JF concentrations on the serum partitioning of Co and Cr in the blood.ResultsA CoCr JFR > 1 showed a specificity of 83% (77% to 88%) and sensitivity of 63% (55% to 70%) for the detection of severe ALVAL and/or SOTP. In patients with CoCr JFRs > 1, the median blood Cr to serum Cr ratio was 0.99, compared with 0.71 in patients with CoCr JFRs < 1 (p < 0.001). Regression analysis demonstrated that the blood Cr to serum Cr value was positively associated with the JF Co concentration (p = 0.011) and inversely related to the JF Cr concentration (p < 0.001).ConclusionElevations in CoCr JFRs are associated with adverse biological (severe ALVAL) or tribocorrosive processes (SOTP). Comparison of serum Cr with blood Cr concentrations may be a useful additional clinical tool to help to identify these conditions.Cite this article: D. J. Langton, S. Natu, C. F. Harrington, J. G. Bowsher, A. V. F. Nargol. Is the synovial fluid cobalt-to-chromium ratio related to the serum partitioning of metal debris following metal-on-metal hip arthroplasty? Bone Joint Res 2019;8:146–155. DOI: 10.1302/2046-3758.83.BJR-2018-0049.R1.

No clear evidence on the clinical performance of different removable prosthetic options in partially edentulous patients.

Data sourcesMedline/PubMed, Embase, BIOSIS/Ovid, SciSearch/DIMDI, Cochrane library, FIZ Technik Web and hand searches of the journals; Clinical Oral Investigations, International Journal of Prosthodontics, Journal of Prosthetic Dentistry, Deutsche Zahnärztliche Zeitschrift, Swiss Dental Journal, Journal of Dentistry and the Journal of Dental Research.Study selectionRandomised controlled trials, prospective and retrospective studies on survival rates of removable dental prostheses in the moderately reduced dentition with at least 15 participants having an observation period of at least two years, and a dropout rate of less than 25% were considered.Data extraction and synthesisTwo reviewers abstracted data. A qualitative summary of the included studies was carried out. Studies providing data that permitted a Kaplan-Meier analysis were included in meta-analysis.ResultsThe review included 19 studies, six of which were in multiple publications. Cast-metal framework dentures showed failure rates of 33% and 50% after five years. One study with a 25-year observation period reported failure rates of 50%. Proper pretreatment and a good recall scheme improve the results. Bilateral attachment prostheses showed failure rates of 11% and 30% after five years. Unilateral attachment prostheses showed failure rates of 75% after five years. Double-crown prostheses dentures show failure rates of 0% to 21.7% after three to six years.ConclusionsWithin the limitations of this study, it seems that removable partial dentures, (RPD), given suitable pretreatment and follow-up regimes, can provide a satisfactory treatment option. Based on only one paper, they revealed acceptable results even over a very long observation period (25 years).

Effect of the Keratinized Mucosa Width on the Health Status of Periimplant and Contralateral Periodontal Tissues: A Cross-sectional Study.

The purpose of this study was to examine whether the width of keratinized mucosa (WKM) is associated with the health status of tissue surrounding dental implants and the contralateral teeth. Sixty patients who received implant-fixed unilateral prostheses in the premolar or molar region were recruited for the study. The following parameters were measured for each implant and contralateral tooth: WKM, gingival index (GI), probing pocket depth (PPD), bleeding on probing (BOP), pus discharge, plaque accumulation (PA), gingival recession (GR), and difficulty of brushing. The effect of the WKM on the health status of the surrounding tissue was evaluated by comparing the different WKM groups (WKM < 2 mm vs WKM ≥ 2 mm). Implants with a WKM <2 mm demonstrated significantly greater PPD, PA, and a higher rate of BOP compared with implants with a WKM ≥2 mm. There was significantly greater GR in contralateral teeth with a WKM <2 mm compared with a WKM ≥2 mm. In addition, implant sites had a higher rate of BOP compared with the contralateral teeth. Inadequate keratinized mucosa decreased cleansibility of implant sites and increased mucosal inflammation. There is a possibility that PA in implant sites caused more pronounced inflammatory response compared to contralateral tooth.

Alloplastic total temporomandibular joint replacements: do they perform like natural joints? Prospective cohort study with a historical control

The aim of this study was to qualitatively and quantitatively describe the biomechanics of existing total alloplastic reconstructions of temporomandibular joints (TMJ). Fifteen patients with unilateral or bilateral TMJ total joint replacements and 15 healthy controls were evaluated via dynamic stereometry technology. This non-invasive method combines three-dimensional imaging of the subject's anatomy with jaw tracking. It provides an insight into the patient's jaw joint movements in real time and provides a quantitative evaluation. The patients were also evaluated clinically for jaw opening, protrusive and laterotrusive movements, pain, interference with eating, and satisfaction with the joint replacements. The qualitative assessment revealed that condyles of bilateral total joint replacements displayed similar basic motion patterns to those of unilateral prostheses. Quantitatively, mandibular movements of artificial joints during opening, protrusion, and laterotrusion were all significantly shorter than those of controls. A significantly restricted mandibular range of motion in replaced joints was also observed clinically. Fifty-three percent of patients suffered from chronic pain at rest and 67% reported reduced chewing function. Nonetheless, patients declared a high level of satisfaction with the replacement. This study shows that in order to gain a comprehensive understanding of complex therapeutic measures, a multidisciplinary approach is needed.

SU-E-J-230: Effect of Metal Hip Prosthesis On the Accuracy of Electromagnetic Localization and Tracking

Purpose: To quantify the effect of metal hip prosthesis on the ability to track and localize electromagnetic transponders. Methods: Three Calypso transponders were implanted into two prostate phantoms. The geometric center of the transponders were identified on computed tomography and set as the isocenter. With the phantom stationary on the treatment table and the tracking array 14-cm above the isocenter, data was acquired by the Calypso system at 10 Hz to establish the uncertainty in measurements. Transponder positional data was acquired with unilateral hip prostheses of different metallic compositions and then with bilateral hips placed at variable separation from the phantom. Results: Regardless of hip prosthesis composition, the average vector displacement in the presence of a unilateral prosthesis was < 0.5 mm. The greatest contribution to overall vector displacement occurred in the lateral dimension. With bilateral hip prosthesis, the average vector displacement was 0.3 mm. The displacement in the lateral dimension was markedly reduced compared with a unilateral hip, suggesting that there was a countervailing effect with bilateral hip prosthesis. The greatest average vector displacement was 0.6 mm and occurred when bilateral hip prostheses were placed within 4 cm of the detector array. Conclusion: Unilateral and bilateral hip prostheses did not have any meaningful effect on the ability to accurately track electromagnetic transponders implanted in a prostate phantom. At clinically realistic distances between the hip and detection array, the average tracking error is negligible.

Detection of Orthopaedic Implants by Airport Metal Detectors

To report the effect of patient's body mass index (BMI), implant type, size, location, number, and material on detection by certified Transportation Security Administration (TSA) and Federal Aviation Administration (FAA) airport metal detectors set to today's standard sensitivity. Retrospective clinical study. Level 1 university trauma center. Ninety-six regularly scheduled trauma clinic patients with a wide variety of orthopaedic implants were enrolled in the study from August 2004 through December 2004. Patients walked through an airport arch metal detector and were also wanded with a handheld metal detector. Detection of implants by arch detector or wand was recorded. We also gathered information regarding BMI, location of implants, type, metal composition, and size. All unilateral prostheses (8/8) and bilateral prostheses (1/1) were detected. Subjects with 4 or fewer screws and no other implants were never detected by the arch metal detector (0/7). For the remaining 78 subjects, the 2 best predictors of detection by the arch were having plates of length >10 holes and having titanium nails (P < 0.001 for each predictor, Wald's test for effects in a logistic model). Prostheses, plates of length >10 holes, and titanium nails were the best predictors of detection by the arch. These 3 factors accounted for 42 of the 43 detections by the arch. Body mass index was not shown to affect detectability of orthopaedic implants.

In vivo isocenter dose in two hip prosthesis patients

Hip prostheses may cause irradiation dose inhomogeneities in conventional four-field target volumes to the pelvis. Two patients, with bilateral and unilateral prostheses, were subjected to thermoluminescent dosimetry measurements in the prostatic urethra during 24 MV photon portal exposures. The results suggested a 13% decrease in absorbed dose only for conventional four-field beam geometry with bilateral prostheses, as compared to oblique four-field beam geometry or unilateral prosthesis. This supports the suggestion that beam technique modifications may be warranted for patients with hip prostheses.

Penile Prosthesis Reimplantation

Occasionally, penile prostheses are removed following erosion, infection or malfunction and they are not replaced immediately. Patients may present later for reimplantation of a penile prosthesis after an interval free of a device. However, no information is available as to the outcome and difficulties of such a procedure. We reviewed the charts of all 305 patients undergoing implantation of a penile prosthesis at our institution and contacted all 8 who had undergone reimplantation. Bilateral prostheses were placed in 4 patients. Unilateral prostheses only could be placed in 2 patients because of extensive fibrosis in the other corporeal body. One of these prostheses subsequently was removed because of erosion. In 2 patients the prosthesis could not be implanted in either side because of extensive fibrosis. Of the 8 patients 4 are able to have intercourse (1 with difficulty) and reimplantation of the prosthesis often was difficult or impossible. We conclude that reimplantation of a penile prosthesis is beneficial for some patients but they should be informed of the possibility of unsatisfactory results.

Long-term results of prosthetic ureteral replacement in minipigs.

In a 3-year study, silicone rubber prostheses were implanted in 6 minipigs as ureteric replacement. A Dacron velour cuff was applied for the proximal anastomosis and a disc of the same material implanted into the bladder wall to anchor the prosthesis distally. The silicone tube incorporated a metal spiral to prevent kinking. On autopsy all anastomoses were firm and resistant to tearing except in 1 animal where the proximal end of the prosthesis had loosened without further complications. Incrustation or leakage never occurred. On histology dense ingrowth of collagen fibres into the meshes of Dacron velour was evident. Malignant cells could never be demonstrated. The findings are compared with a previous 12-month study. The growth of polypoid structures occluding the prosthesis was found to be a new problem with long-term alloplastic ureteric replacement. The best results were achieved with unilateral prostheses after contralateral nephrectomy.