Shoulder arthroplasty. Part 1: Prosthesis terminology and classification.

Shoulder arthroplasty is the third most common joint replacement procedure in the UK, and there are a number of different implant options available to surgeons to treat a variety of shoulder disorders. With an increasing burden placed on clinical follow-up, more patients are remaining under the care of their general practitioners and musculoskeletal triage assessment services and are not necessarily being seen by specialists. Referrals to orthopaedic specialists are therefore often prompted by radiological reports describing evidence of implant failure. This article is the first of two reviews on shoulder arthroplasty, concentrating on implant features and the indications for their use. The second article will address the modes of failure of shoulder arthroplasty and describe the relevant associated radiological features.

Shoulder arthroplasty. Part 2: normal and abnormal radiographic findings.

Frequently, the decision made by general practitioners or musculoskeletal triage assessment services to refer patients for specialist review is initiated by a radiological report. Following shoulder arthroplasty it is important to ensure that any patient with asymptomatic evidence of a failing prosthesis is referred for review so that revision surgery can be contemplated and planned before the situation becomes unsalvageable. The first paper in this series described the various types of shoulder arthroplasty and indications for each. This follow-up paper will concentrate on their modes of failure and the associated radiographic features, and is aimed at radiology trainees and non-musculoskeletal specialist radiologists.

Patellar height measurement in trochlear dysplasia.

A number of measurements of patellar height are in clinical use all of which reference from the tibia. The patellotrochlear index (PTI) has been proposed recently as a more accurate reflection of the functional height of the patella and described in normal knees. We compared patellar height measurements in patients with patellofemoral dysplasia. In a retrospective analysis of the MRI scans of 33 knees in 29 patients with patellofemoral dysplasia we assessed the inter- and intraobserver reliability of four patellar height measurements: the recently described PTI, Insall-Salvati (IS), Blackburne-Peel (BP) and Caton-Deschamps (CD) ratios. We also assessed the correlation between the different measurements in predicting patella alta. Three blinded observers on two separate occasions performed the measurements. There were 21 females and 8 males with a median age of 21 years (range 13-33). Statistical analysis revealed good inter-observer reliability for all measurements (0.78 for PTI, 0.78 for IS, 0.73 for BP and 0.77 for CD). Intra-observer reliability was also good (0.80, 0.83, 0.75 and 0.78, respectively). There was weak correlation between the PTI and the other ratios for patella alta. There was a strong correlation between the CD and BP ratios (0.96) and a moderate correlation between IS and CD and IS and BP ratios (0.594 and 0.539, respectively). We propose the PTI as a more clinically relevant measure than the IS, CD and BP ratios.

Assessment and management of chronic patellofemoral instability.

Chronic patellofemoral instability can be a disabling condition. Management of patients with this condition has improved owing to our increased knowledge of the functional anatomy of the patellofemoral joint. Accurate assessment of the underlying pathology in the unstable joint enables the formulation of appropriate treatment. The surgical technique employed in patients for whom non-operative management has failed should address the diagnosed abnormality. We have reviewed the literature on the stabilising features of the patellofemoral joint, the recommended investigations and the appropriate forms of treatment.

Magnetic resonance imaging of the patella: a comparison of the morphology of the patella in normal and dysplastic knees.

We retrospectively analysed the MR scans of 25 patients with patellofemoral dysplasia and ten control subjects, to assess whether there was any change in the morphology of the patella along its vertical length. Ratios were calculated comparing the size of the cartilaginous and subchondral osseous surfaces of the lateral and medial facets. We also classified the morphology using the scoring systems of Baumgartl and Wiberg. There were 18 females and seven males with a mean age of 20.2 years (10 to 29) with dysplasia and two females and eight males with a mean age of 20.4 years (10 to 29) in the control group. In the patient group there was a significant difference in morphology from proximal to distal for the cartilaginous (Analysis of variance (ANOVA) p = 0.004) and subchondral osseous surfaces (ANOVA, p = 0.002). In the control group there was no significant difference for either the cartilaginous (ANOVA, p = 0.391) or the subchondral osseous surface (ANOVA, p = 0.526). Our study has shown that in the dysplastic patellofemoral articulation the medial facet of the patella becomes smaller in relation to the lateral facet from proximal to distal. MRI is needed to define clearly the cartilaginous and osseous morphology of the patella before surgery is considered for patients with patellofemoral dysplasia.

Cartilage-bone mismatch in the dysplastic trochlea. An MRI study.

Trochlear dysplasia is an important anatomical abnormality in symptomatic patellar instability. Our study assessed the mismatch between the bony and cartilaginous morphology in patients with a dysplastic trochlea compared with a control group. MRI scans of 25 knees in 23 patients with trochlear dysplasia and in 11 patients in a randomly selected control group were reviewed retrospectively in order to assess the morphology of the cartilaginous and bony trochlea. Inter- and intra-observer error was assessed. In the dysplastic group there were 15 women and eight men with a mean age of 20.4 years (14 to 30). The mean bony sulcus angle was 167.9 degrees (141 degrees to 203 degrees), whereas the mean cartilaginous sulcus angle was 186.5 degrees (152 degrees to 214 degrees; p < 0.001). In 74 of 75 axial images (98.7%) the cartilaginous contour was different from the osseous contour on subjective assessment, the cartilage exacerbated the abnormality. Our study shows that the morphology of the cartilaginous trochlea differs markedly from that of the underlying bony trochlea in patients with trochlear dysplasia. MRI is necessary in order to demonstrate the pathology and to facilitate surgical planning.

Isolated tibial vessel disease: treatment options and outcome.

Tibial vessel disease is an important cause of limb ischaemia, particularly in diabetics. Revascularisation by angioplasty and bypass is increasingly feasible. The aim of this study was to review treatment and outcome in patients with this patterns of disease. We have performed 25 procedures in 20 patients since September, 1989. Six patients (5 diabetic) underwent 9 tibial angioplasties for stenotic lesions causing critical ischaemia or short-distance claudication. In 6 procedures there was single vessel run-off. Eight angioplasties were radiologically successful with a median increase in ankle-brachial index (ABI) of 0.15 [range: 0.00-0.44] at a median follow-up of 9 months. A further 4 patients (3 diabetic) with critical ischaemia underwent popliteal-distal, in-situ vein bypass for tibial occlusions. Distal anastomosis was onto the dorsalis pedis artery or distal anterior artery. Three grafts remain patent with successful limb salvage and ABI's greater than 1.0. Angioplasty is also useful for distal disease progression following femoro-popliteal bypass. Six patients with "at-risk" grafts underwent 8 tibial angioplasties for stenotic lesions in distal run-off. Radiologically, 6 procedures were successful with a median increase in ABI of 0.21 [range: 0.00-0.38] at a median follow-up of 7 months. There were less favourable results when a "graft-distal" bypass performed to salvage an occluded femoro-popliteal graft with diseased run-off vessels. Three of 4 grafts reoccluded within 3 months, 2 patients requiring amputation. We advocate an aggressive policy towards localised distal disease causing foot ischaemia.

Error in radiology.

The level of error in radiology has been tabulated from articles on error and on "double reporting" or "double reading". The level of error varies depending on the radiological investigation, but the range is 2-20% for clinically significant or major error. The greatest reduction in error rates will come from changes in systems.

Audit of the value of double reading magnetic resonance imaging films.

100 consecutive magnetic resonance imaging (MRI) examinations were reviewed independently by two radiologists. Patients were selected so that the anatomical areas of clinical interest coincided with the special interests of the reviewers. The reviewers were both consultant radiologists, one with 3 years' and the other with 6 years' experience of MRI. Hard copy images from the MRI examinations were reported independently by both reviewers. Of the 100 MRI examinations, there was full concordance of opinion in 61/100. Of the remaining 39 cases, four (10%) were considered "minor unrelated" differences, 12 (31%) "minor related" differences and 23 (59%) "major related" differences resulting in a significant change in patient management.

The value of the short tau inversion recovery sequence in magnetic resonance imaging of thyroid eye disease.

22 patients with thyroid eye disease were examined with magnetic resonance imaging (MRI) and the results compared with 10 controls. Imaging was performed on a 1.0 T scanner using a head coil. All patients were examined using both T1W and short tau inversion recovery (STIR) sequences. The relative signal intensity (SI) of individual extraocular muscles were quantified by comparison with SI from the adjacent temporalis muscle to give a signal intensity ratio (SIR). The results were compared with clinical disease activity assessed by the Werner grading system. Visual evaluation of muscle size and calculated SIRs showed an increase when compared to normals in 15 of the 22 patients. This difference was significant in patients with high grade (4-6) clinical disease. The known histological changes in this disease suggest that this increase in signal is caused by oedema secondary to acute inflammation. STIR sequences suppress the retro-orbital fat and thus enhance these changes both in the muscles and in the fat itself. The MR findings suggest that the STIR sequence can be used to predict those patients that will respond to anti-inflammatory treatment.

Magnetic resonance imaging of the whole spine in suspected malignant spinal cord compression: impact on management.

Patients with suspected malignant spinal cord compression may present with a misleading sensory level or have multiple levels of compression that are not apparent clinically or on imaging of a limited area of the spine. To estimate how often this occurs and to evaluate a policy of magnetic resonance imaging (MRI) of the whole spine for any patient with suspected cord compression, data from 127 patients who had undergone MRI scans of the whole spine were reviewed. In 85 of 127 scans, there was evidence of compression of or impingement upon the spinal cord. A sensory level was present in 47 of these 85 patients, but in 12/47 (26%) the sensory level was four or more segments below or three or more segments above the actual lesion. Multiple levels of compression or impingement were found in 33 of 85 (39%) patients; in 24 of these, more than one region (cervical/thoracic/lumbar) of the cord was involved. For 32 patients who commenced radiotherapy to a treatment volume based on clinical criteria before the MRI scan was available, the radiotherapy fields needed modification in 16 (50%) as a result of the MRI findings. The results support a policy of MRI of the whole spine in any patient with suspected malignant spinal cord compression.

Magnetic resonance imaging of patellar tendonitis.

The radiological and MRI appearances of 24 knees with patellar tendonitis resistant to conservative therapy were analysed to identify the characteristic MRI appearance and to determine if the patellar morphology was abnormal. A significant thickening of the tendon was found in all cases; this was a more reliable diagnostic feature than a high signal within the superior posterior and central aspect of the tendon at its proximal attachment. The site of the lesion shown by MRI is more compatible with impingement of the inferior pole of the patella against the patellar tendon than a stress overload of the tendon. There were no significant differences in the length of the patella, inferior pole or length of the articular surface when the patellar morphology was compared with that of a matched control group.

Limitations of chest radiography in discriminating between aortic dissection and myocardial infarction: implications for thrombolysis.

It has been stated that chest radiographic features of aortic dissection are a contraindication to intravenous thrombolysis in patients with suspected acute myocardial infarction. Excluding aortic dissection could significantly delay such treatment in patients who would benefit from thrombolysis. Initial chest radiographs of 18 patients with acute aortic dissection and 25 patients with acute myocardial infarction were evaluated. The radiographs were studied by two experienced radiologists for signs of aortic dissection. No radiographic signs or combinations of signs accurately distinguished aortic dissection from myocardial infarction. Patients with chest radiographic signs suggesting aortic dissection but with clinical features suggesting myocardial infarction should not be denied the benefits of immediate intravenous thrombolysis.

The outcome of intra-articular debris, following anterior cruciate ligament reconstruction.

Following arthroscopic anterior cruciate ligament reconstruction, radio-opacities were noted on the post-operative radiographs in 40 of 50 consecutive cases. There was no correlation between the presence of these opacities and post-operative knee pain, joint effusion, arthrofibrosis or knee recovery. In 12 cases undergoing a subsequent radiograph between 3 and 18 months post-operatively, opacities were noted in only one case.

The effect of ultrasound guided steroid injection on progression to surgery in thumb CMC arthritis.

Thumb carpometacarpal joint (CMCJ) osteoarthritis is a common complaint that produces pain and disability within the hand. This study aims to ascertain whether joint injection with local anaesthetic and steroid is of predicative value in disease progression in thumb carpometacarpal osteoarthritis. Forty-three patients were assessed at an average follow up of 24 months following ultrasound-guided injection. Fourteen patients (32%) progressed to surgery, at a mean interval of 8.6 months (range 4-14 months). There was a statistically significant correlation between those patients who had on-going pain following injection at one week and progression to surgery (p = 0.025) with an odds ratio of 3.14 and positive likelihood ratio of 2.1. Patients with thumb CMCJ osteoarthritis that does not respond favourably to injection at one week are likely to progress to surgery in the first year after the injection. This work offers a useful tool in predicting disease progression and patient counseling.

The correct rotation of the femoral component in patellofemoral replacement: a laboratory assessment of a surgical technique.

Ensuring correct rotation of the femoral component is a challenging aspect of patellofemoral replacement surgery. Rotation equal to the epicondylar axis or marginally more external rotation is acceptable. Internal rotation is associated with poor outcomes. This paper comprises two studies evaluating the use of the medial malleolus as a landmark to guide rotation. We used 100 lower-leg anteroposterior radiographs to evaluate the reliability of the medial malleolus as a landmark. Assessment was made of the angle between the tibial shaft and a line from the intramedullary rod entry site to the medial malleolus. The femoral cut was made in ten cadaver knees using the inferior tip of the medial malleolus as a landmark for rotation. Rotation of the cut relative to the anatomical epicondylar axis was assessed using CT. The study of radiographs found the position of the medial malleolus relative to the tibial axis is consistent. Using the inferior tip of the medial malleolus in the cadaver study produced a mean external rotation of 1.6° (0.1° to 3.7°) from the anatomical epicondylar axis. Using the inferior tip of the medial malleolus to guide the femoral cutting jig avoids internal rotation and introduces an acceptable amount of external rotation of the femoral component.

The volar anatomy of the distal radius--an MRI study of the FCR approach.

INTRODUCTION: Fractures of the distal radius are one the commonest orthopaedic injuries. Recent advances in implant technology have seen a dramatic rise in the number of fractures treated with volar locked plates, as they permit accurate peri-articular reconstruction. The surgical approach along the bed of flexor carpii radialis (FCR) tendon encounters a number of key soft tissue and neurovascular structures during the dissection to the fracture plane. The aim of this study was to describe the exact position of such structures involved (and hence at risk) during the FCR approach. METHODS: 100 adult MRI scans were reviewed. The relationships between the brachioradialis tendon (BR), flexor carpi radialis (FCR) tendon, flexor pollicis longus (FPL) tendon, median nerve (MN) and radial artery (RA) were measured. RESULTS: The male to female ratio was 35:65. Average age was 39. FCR tendon was 7.4 mm (SD 1.46) from the RA and 7.01 mm (SD 2.37) from the MN. The distance between BR and RA was significantly different between male and female (5.06 mm vs. 4.1 mm, p=0.034). CONCLUSION: This study highlights the precise nature of the surgical anatomy involved in dissection to the fracture site. Vigilance is needed during the initial steps of the FCR-bed approach to avoid damage to the radial artery and median nerve which lie in close proximity. If the approach is extended to include a brachioradialis tenotomy, we suggest this should be made under direct vision, given its relationship with the radial artery.