James Wimhurst

Grading the severity of soft tissue changes associated with metal-on-metal hip replacements:reliability of an MR grading system

IntroductionMetal-on-metal (MoM) soft tissue reactions or aseptic lymphocytic vasculitis-associated lesions (ALVAL) are being recognised using metal artefact reduction (MAR) MR with increasing frequency following the advent of second generation metal-on-metal bearings, but there is no standardised technique for reporting of MR appearances in this disease. The aim of this study was to measure the reliability of a grading system designed for scoring the severity of MoM disease on MRI.Materials and methodsMRI examinations of 73 hips in 59 patients were retrospectively selected and then anonymised, randomised and reviewed by three independent observers (musculoskeletal radiologists). Each MR examination was scored as either A: normal, B: infection, C1: mild MoM disease, C2: moderate MoM disease or C3: severe MoM disease according to pre-defined criteria. Kappa correlation statistics were used to compare the observations.ResultsThere was substantial agreement among all three observers; the correlation coefficient between the two most experienced observers was κ = 0.78 [95% confidence intervals (CI): 0.68–0.88] and when compared with the least experienced observer coefficients were κ = 0.69 (95% CI: 0.57–0.80) and κ = 0.66 (95% CI: 0.54–0.78). The strongest correlation occurred for grades A, C2 and C3. The weakest correlations occurred for grades B and C1.ConclusionThe grading system described in this study is reliable for evaluating ALVAL in MoM prostheses using MR but is limited in differentiating mild disease from infection.

Silent soft tissue pathology is common with a modern metal-on-metal hip arthroplasty.

Background and purpose Adverse reactions to metal debris have been reported to be a cause of pain in metal-on-metal hip arthroplasty. We assessed the incidence of both symptomatic and asymptomatic adverse reactions in a consecutive series of patients with a modern large-head metal-on-metal hip arthroplasty. Methods We studied the early clinical results and results of routine metal artifact-reduction MRI screening in a series of 79 large-head metal-on-metal hip arthroplasties (ASR; DePuy, Leeds, UK) in 68 patients. 75 hips were MRI scanned at mean 31 (12–52) months after surgery. Results 27 of 75 hips had MRI-detected metal debris-related abnormalities, of which 5 were mild, 18 moderate, and 4 severe. 8 of these hips have been revised, 6 of which were revised for an adverse reaction to metal debris, diagnosed preoperatively with MRI and confirmed histologically. The mean Oxford hip score (OHS) for the whole cohort was 21. It was mean 23 for patients with no MRI-based evidence of adverse reactions and 19 for those with adverse reactions detected by MRI. 6 of 12 patients with a best possible OHS of 12 had MRI-based evidence of an adverse reaction. Interpretation We have found a high early revision rate with a modern, large-head metal-on-metal hip arthroplasty. MRI-detected adverse rections to metal debris was common and often clinically “silent”. We recommend that patients with this implant should be closely followed up and undergo routine metal artifact-reduction MRI screening.

Metal Ion Levels Not Sufficient as a Screening Measure for Adverse Reactions in Metal-on-Metal Hip Arthroplasties

This study aims to assess the accuracy of metal ion analysis in the diagnosis of adverse reaction to metal debris (ARMD) in patients with metal-on-metal hip arthroplasties by comparing the cobalt and chromium levels in 57 patients (62 hips) to findings on metal artifact reduction magnetic resonance imaging (MRI). An ARMD was detected using MRI in 18 (29%) of the hips. Forty patients had cobalt levels less than 7 μg/L, and 33 had chromium levels less than 7 μg/L, but 8 of these had an ARMD on MRI and only minimal symptoms (Oxford Hip Score ≥ 44/48). The incidence of ARMD was significantly higher when chromium concentration was above 7 μg/L (P = .02), but normal metal ion levels can be misleading and metal artifact reduction MRI imaging is advised in all patients.

The clinical and radiological outcomes of the LISS plate for distal femoral fractures: A systematic review

PURPOSE The purpose of this systematic review was to assess the literature evaluating the clinical and radiological outcomes following less invasive surgical stabilisation system (LISS) fixation of distal femoral fractures (AO 32/33). METHODS A review of EMBASE, Medline, CINAHL and AMED from their inception to November 2008, sources of grey literature and a pertinent hand search of specialist orthopaedic journals was undertaken. RESULTS Twenty-one studies assessing 663 patients with 694 fractures were reviewed. The findings suggest that the LISS system may be an appropriate fixation method for the management of distal femoral fractures. However, there remains a high incidence of loss of reduction (n=134; 19%), delayed or non-union (n=40; 6%) and implant failure (n=38; 5%). On analysis, such complications were largely confined to articles published before 2005, therefore during the infancy of the widespread clinical application of this trauma system. On critical appraisal, the evidence-base remains limited by recruiting small, under-powered sample sizes and poorly accounting for confounding variables such as osteoporosis, diabetes, multi-trauma and fracture classification. CONCLUSION Further study is required to assess the outcomes of LISS fixation in specific patient populations, and to compare the outcome of this fixation method to condylar plates and intrameduallary devices, to determine the optimal management strategy for this complex patient group.

MRI of Aseptic Lymphocytic Vasculitis-Associated Lesions in Metal-on-Metal Hip Replacements

OBJECTIVE The aim of this review is to describe the clinical, histopathologic, and MRI features of aseptic lymphocytic vasculitis-associated lesions in total hip replacements. CONCLUSION The introduction of modern metal-on-metal hip arthroplasty has been accompanied by a newly described disease, aseptic lymphocytic vasculitis-associated lesions, which is characterized histologically by bland necrosis and dense perivascular lymphocytic infiltrates. Conventional radiographic findings are often normal, but the typical MRI findings include periprosthetic fluid collections, soft-tissue masses, gluteal tendon avulsion, bone loss, periosteal stripping, neurovascular involvement, and periprosthetic fractures. The severity of the histologic and MRI appearances can be graded according to defined published criteria.

A Reliability Study of Measurement Tools Available on Standard Picture Archiving and Communication System Workstations for the Evaluation of Hip Radiographs Following Arthroplasty

BACKGROUND Conventional radiography is the primary imaging tool for routine follow-up of total hip replacements, but the reliability of this method has been questioned. The aim of this study was to assess the reliability of commonly used measurements of the position of hip prostheses on postoperative radiographs with use of tools available on all standard picture archiving and communication system workstations. METHODS Fifty anteroposterior pelvic and lateral hip radiographs that were made after a unilateral total hip arthroplasty were included in this study. Acetabular inclination, lateral offset, lower-limb length, center of rotation, and femoral stem angle were independently assessed by two observers. Intraclass correlation coefficients were calculated for each measurement. RESULTS The results demonstrated excellent reliability for acetabular angle (r = 0.95), lower-limb length (r = 0.91), and lateral offset (r = 0.95) measurements and good reliability for center of rotation (r = 0.73) and lateral femoral stem angle (r = 0.68) measurements. CONCLUSIONS The position of total hip replacements can be reliably assessed with use of simple electronic tools and standard radiology workstations.

The natural history of metallosis from catastrophic failure of a polyethylene liner in a total hip

We report on a case of metallosis initially presumed to be heterotopic ossification based on radiologic findings. A 68-year-old man with a total hip arthroplasty experienced failure of the polyethylene liner, resulting in articulation of the ceramic head with the titanium acetabular shell. During revision surgery, extensive metallic debris was evident macroscopically throughout the periprosthetic tissue and was confirmed histologically to be metallosis.

A New Technique for Radiographic Measurement of Acetabular Cup Orientation

Accurate radiographic measurement of acetabular cup orientation is required in order to assess susceptibility to impingement, dislocation, and edge loading wear. In this study, the accuracy and precision of a new radiographic cup orientation measurement system were assessed and compared to those of two commercially available systems. Two types of resurfacing hip prostheses and an uncemented prosthesis were assessed. Radiographic images of each prosthesis were created with the cup set at different, known angles of version and inclination in a measurement jig. The new system was the most accurate and precise and could repeatedly measure version and inclination to within a fraction of a degree. In addition it has a facility to distinguish cup retroversion from anteversion on anteroposterior radiographs.

Reliability of the radiological assessments of radiolucency and loosening in total hip arthroplasty using PACS

We evaluated the reliability of three commonly used radiological assessments of total hip arthroplasty (THA) using the electronic picture archiving and communications system (PACS). Thirty-three patients were selected at random at a mean of 7.2 years after THA. The Barrack, Gruen and Hodgkinson evaluations of cementing quality, loosening/radiolucency were graded. Three observers assessed each radiograph (one consultant orthopaedic surgeon, one senior orthopaedic registrar and one senior house officer). Four weeks after the initial assessment, each radiograph was reviewed a second time. The findings indicated that the intra- and inter-observer reliability of the Barrack, Gruen and Hodgkinson methods were questionable. Inter-observer reliability using the Gruen system was poor, using the Barrack system it was moderate to good, and fair to good using the Hodgkinson assessment. Intra-observer reliability was moderate to good for Barrack assessment, poor to good using Gruen zone assessments, but good to very good for the Hodgkinson assessment. The use of Barrack, Gruen and Hodgkinson assessments to evaluate femoral and acetabular loosening should be questioned since these exhibit limited inter- and intra-observer reliability on PACS radiographs, but of the three, the Hodgkinson system is the most reliable.

Painless lump on the shin: diagnosis and discussion

Periosteal ganglia are rare lesions that occur most commonly in people between the ages of 30 years and 50 years. Patients present with a history of a painless lump adjacent to a long bone. Such lumps are usually found around the long bones of the lower extremities, especially the tibia, but they have also been documented in the distal radius, femur and ilium. The pathogenesis of periosteal ganglia is unclear. The ganglia probably arise as a result of mucoid degeneration of the periosteum, with secondary mucin-filled cyst formation. The stimulus for the degenerative process is not known. Periosteal ganglia are usually uni-locular, with no extension through the adjacent cortex, as might occur with an osseous ganglion with extra-osseous extension and communication with adjacent joints [1]. Radiographic findings include a soft tissue mass of water attenuation (see case presentation, Fig. 1a, arrowheads), scalloping of the adjacent cortex and marginal periosteal new bone formation (Fig. 1a, arrows). This periosteal new bone can be mistaken for Codman’s triangles, and a more aggressive process may be inferred. The ultrasound findings are of an anechoic cyst (Fig. 1d, asterisk), which may contain small, low-level, speckled echoes, but there should be no Doppler signal within the cyst. Cortical scalloping (Fig. 1d, arrow) can be demonstrated in the adjacent cortex. MRI demonstrates a well-defined periosteal lesion of homogeneous fluid signal (Fig. 1b, arrow). Marginal elevated periosteum, the source of the periosteal new bone, can also be demonstrated (Fig. 1c, arrow) [2]. These MRI features are considered to be diagnostic of a periosteal ganglion. However, the same features can also be demonstrated with high-resolution ultrasound probes and, therefore, may be an alternative diagnostic tool for identifying periosteal ganglia. The material aspirated from a ganglion is usually thick, colourless and jelly-like. Cytological examination reveals scattered histiocyte-like cells (Fig. 1e, arrow) with abundant cytoplasm and small oval nuclei within a background of abundant myxoid material (Fig. 1e, arrowheads). Histiocytes, or macrophages, in a mucinous background indicate a process involving mucoid degeneration. Periosteal ganglia can be successful treated by excision or aspiration. Recurrence of the lesion at the site following any form of treatment is most probably due to the conSkeletal Radiol (2007) 36:971–972 DOI 10.1007/s00256-007-0339-x