Metal-on-Metal Hip Replacement: MRI Signal Intensities of Different Body Tissues and Their Relations to Blood Metal Ion Levels.

BACKGROUND: Metal-on-metal total hip prostheses (MoM-THR) have been shown to produce hypersensitivity reactions and fluid collection (pseudotumor) by the hip as well as high blood metal ions levels (BMILs). OBJECTIVES: To evaluate the magnetic resonance imaging (MRI) signal-to-noise ratio (S/N) in selected body tissues around the hip of patients who underwent MoM hip replacement and to correlate to BMILs. METHODS: Sixty-one MRI hip examinations in 54 post-MoM-THR patients (18 males, 36 females, mean age 65 years) were retrospectively evaluated independently by two readers. The mean S/N ratio in a region of interest was calculated for periprosthetic pseudotumor collection (PPC), the bladder, fat, and muscle on axial T1w, FSE-T2w, and short tau inversion recovery (STIR) sequences on the same location. BMILs were retrieved from patient files. RESULTS: PPC was detected in 32 patients (52%) with an average volume of 82.48 mm3. BMIL did not correlate with the presence of PPCs but positively correlated with the PPC's volume. A trend for positive correlation was found between BMILs and S/N levels of STIR images for muscle and bladder as well as for PPC and cobalt levels. A trend for correlation was also seen between BMIL with PPC's T1 w S/N. CONCLUSIONS: Alteration of MRI S/N for different hip tissues showed a tendency for correlation with BMILs, possibly suggesting that metal deposition occurs in the PPC as well as in the surrounding tissues and bladder.

Bilateral total hip replacement: periprosthetic pseudotumor collections are more prevalent in metal-on-metal implants compared to non-metal-on-metal ones.

BACKGROUND: Metal-on-metal (MoM) hip prostheses were shown to have high failure rates including the formation of periprosthetic cystic masses called periprosthetic pseudotumor collections (PPCs). PURPOSE: To compare MRI prevalence and size of PPCs in patients after bilateral total-hip-replacement (THR) in which at least one hip was replaced by a MoM prosthesis. MATERIAL AND METHODS: All sequential MRI examinations of patients with bilateral THR in which at least one is MoM (2010-2013) were retrospectively evaluated. MRIs were analyzed separately by two readers for the presence and size of PPCs. These were compared between MoM and non-MoM implants and between patients with unilateral or bilateral-MoM prostheses. Blood metal ion levels were also compared. RESULTS: Seventy hips of 35 patients (male:female ratio, 9:26; mean age, 64 years; age range, 35-82 years) were assessed. Sixteen patients (45%) underwent bilateral MoM-THRs and 19 (55%) had one MoM and the other non-MoM, yielding 51 MoM THRs and 19 non-MoM THRs. Twenty-eight PPCs were detected in 19 patients (54%): 26 in MoM THRs (51%) and two in non-MoM THRs (10.5%, P = 0.00009). The mean PPC volume in the MoM implants (107 mm(3)) was higher than that of the non-MoM implants (18 mm(3), P = 0.49). Cobalt/chromium blood levels were 78 µg/L/25 µg/L for bilateral MoM THRs and 21 µg/L/10 µg/L for unilateral MoM implants (P = 0.1 and 0.16, respectively). CONCLUSION: PPCs are more prevalent in MoM THRs compared to non-MoM THRs. Larger PPC volumes and higher blood metal ion levels were detected in patients with bilateral MoM THRs compared to unilateral MoM THRs (P > 0.05).

Clinical and radiographic outcomes of 139 hips with articular surface replacement total hip arthroplasty*.

BACKGROUND: The articular surface replacement (ASR) total hip arthroplasty (THA) was recently recalled from the market due to high failure rates. This modality was used frequently by surgeons at our medical center. OBJECTIVES: To assess the clinical and radiographic outcomes in patients following the surgery and determine the revision rate in our cohort. METHODS: Between 2007 and 2010 139 hips were operated on and evaluated in our clinic. All patients underwent a clinical interview, function and pain evaluation, as well as physical examination and radiographic evaluation. When necessary, patients were sent for further tests, such as measuring cobalt-chromium levels and magnetic resonance hip imaging. RESULTS: With an average follow-up of 42 months the revision rate was 2% (3/139). Patients reported alleviation of pain (from 8.8 to 1.7 on the Visual Analog Scale, P < 0.001), good functional outcomes on the Harris Hip Score, and improved quality of life. Overall satisfaction was 7.86 on the reversed VAS. For patients who required further tests, clinical and radiographic outcomes were significantly poorer than for the rest of the cohort. Average blood ion levels were high above the normal (cobalt 31.39 ppb, chromium 13.32 ppb), and the rate of inflammatory collection compatible with pseudotumors on MRI was 57%. DISCUSSION: While our study favors the use of the ASR implant both clinically and radiographically, some patients with abnormal ion levels and inflammatory collections on MRI might require revision in the future.

Preoperative planning of total hip replacement using the TraumaCad™ system.

INTRODUCTION: Templating is now the standard approach for preoperative planning of total joint replacement and fracture fixation. The aim of this study was to assess the accuracy of new software, TraumaCad™, for preoperative planning for total hip replacement. METHODS: This software enables the import and export of all picture archiving communication system (PACS) files from local working stations. It can integrate with all PACS systems. We retrospectively reviewed TraumaCad™-generated templates of digitalized preoperative radiographs of 73 consecutive patients. RESULTS: The acetabular component, measured within ± 1 size, was accurate in 65 patients (89%), and the femoral stem design component was accurate in 70 patients (97%). The accuracy of the femoral size was predicted in 57 patients within 1 size (87%) and in 65 patients within 2 sizes (96%) out of 68 patients in the Corail femoral component group. TraumaCad™ successfully predicts the sizes of femoral and acetabular component and easily integrates with all PACS files.

Removal of a broken distal closed section intramedullary nail: report of a case using a simple method.

A simple method to remove a broken distal closed section intramedullary nail is presented. The surgical technique and a case report are described. This technique eliminates the need for an additional exposure, other than that required to insert the nail, or any specialized equipment.

Whiplash injury: is there a role for electromyographic studies?

INTRODUCTION: This retrospective study was undertaken to assess the value of carrying out baseline and follow-up electromyography (EMG) for patients with whiplash-associated disorders (WAD, grades I and II) after they had undergone rear-end car collisions, and to determine if there is any agreement with clinical and imaging (CT and MRI) findings. MATERIALS AND METHODS: We carried out a retrospective review of 330 patients seeking compensation after rear-end car collisions. The treating physician referred all patients for EMG studies in the post-injury follow-up period and for additional CT scans and MRIs. All patients underwent physical and X-ray examination by the senior author (SD), and 75 patients with persistent radicular complaints were referred again for EMG studies. The results of the association between patient complaints, clinical examination, and EMG, CT and MRI studies are reported. RESULTS: We sought but failed to find any correlations between 354 EMG results with those of 278 CT scans and 75 MRIs. Both subjective complaints and early vs late EMG abnormalities showed statistical agreement and persistency of findings only at disc level C7/D1. CONCLUSIONS: Our data indicate that follow-up EMG studies for patients with WAD do not contribute any useful information for patient management.

Comparative analysis of the benefits of autotransfusion of blood by a shed blood collector after total knee replacement.

INTRODUCTION: Joint replacement is associated with massive blood loss. Various techniques have been used to avoid the use of allogeneic blood. One of the techniques used is postoperative salvage and reinfusion of shed blood that was found to reduce the use of banked blood with its potential risk. MATERIALS AND METHODS: We prospectively studied 365 patients who underwent knee joint replacement (TKR) and were divided in two groups. Group A's shed blood (SureTrans System) was collected ( n=194) and reinfused and group B's was not ( n=171, "controls"). Hemoglobin levels before and after the operation were recorded. RESULTS: Allogeneic blood requirement for TKR decreased by 65% in group A compared to group B. The packed cell/patient index dropped from 0.91 to 0.29 in group 2A. Statistical analysis yielded the odds ratio for blood replacement, a "predicting formula" for blood replacement depending on hemoglobin levels, and a cutoff point for a patient's receiving blood replacement. CONCLUSION: We recommend using this system in TKR for decreasing allogeneic blood replacement and potential associated risks. The predicting formula for blood replacement may be a helpful tool when making a decision of whether or not to use the collector system and for whom.

A miniature and mobile intermittent pneumatic compression device for the prevention of deep-vein thrombosis after joint replacement.

The WizAir-DVT is a miniature, lightweight (690 g), battery-operated and mobile intermittent pneumatic compression device (ICD), which enables continuous intraoperative use and immediate patient mobilization postoperatively. We compared its efficacy with a commonly used ICD, the Kendall SCD. Peak femoral vein flow velocity was measured in 20 apparently healthy volunteers at rest and with each device: we found no significant differences between them. A second prospective, randomized, clinical trial was used to compare the efficiency of the device in preventing deep venous thrombosis (DVT) after joint replacement in 50 patients (n=25/group). None developed DVT. Doppler ultrasonography revealed no significant differences. The WizAir-DVT antithrombotic compression device is as safe and effective as the Kendall SCD.