Intraosseous schwannoma in schwannomatosis.

This study investigates the clinical, radiological, and pathological features of two cases of intraosseous schwannoma that arose in patients with multiple soft tissue schwannomas. In both cases, the patients were adult females and the tibial bone was affected. Vestibular schwannomas were not identified, indicating that these were not cases of neurofibromatosis 2 (NF2). Radiographs showed a well-defined lytic lesion in the proximal tibia; in one case, this was associated with a pathological fracture. Histologically, both cases showed typical features of benign schwannoma. Molecular analysis of one of the excised tumors showed different alterations in the NF2 gene in keeping with a diagnosis of schwannomatosis. Our findings show for the first time that intraosseous schwannomas can occur in schwannomatosis.

Giant-cell-rich pseudotumour in Paget's disease.

Paget's disease (PD) of the bone is a disorder of bone remodelling that may be polyostotic or monostotic. Although development of a sarcoma in PD is well-recognised, it is less well recognised that pseudosarcomas in bone and soft tissue can also arise in this condition. In this report we document the case of a large giant-cell-rich pseudotumour that developed in the tibia and overlying soft tissues in a case of polyostotic PD. Bone and soft tissues were highly vascular and contained abundant haemorrhage with focal areas of new bone formation and a diffuse infiltrate of osteoclastic giant cells. The lesion has not recurred or produced metastases 3 years after removal. Clinicians should be aware that a benign giant-cell-rich pseudotumour can develop in PD and that it needs to be distinguished from other giant-cell-rich tumours.

Necrotic granulomatous pseudotumours in bilateral resurfacing hip arthoplasties: evidence for a type IV immune response.

Clinical, radiological and histological findings were analysed in four patients who developed bilateral pseudotumours following metal-on-metal (MoM) resurfacing arthroplasties of both hips. Using a panel of monoclonal antibodies directed against HLA-DR, macrophages (CD14, CD68), dendritic cells (DC-SIGN, S100, CD11c), B cells (CD20), and T cells (CD3, CD4, CD8), the nature of the heavy inflammatory response seen in these cases was examined. Bilateral masses developed in periprosthetic soft tissues following the second MoM arthroplasty; these were characterised histologically by extensive coagulative necrosis, a heavy macrophage infiltrate and the presence of granulomas containing macrophages and giant cells; there was also a diffuse lymphocyte and variable plasma cell and eosinophil polymorph infiltrate. Immunohistochemistry showed strong expression of HLA-DR, CD14 and CD68 in both granulomatous and necrotic areas; lymphocytes were predominantly CD3+/CD4+ T cells. The clinical, morphological and immunophenotypic features of these necrotic granulomatous pseudotumours, which in all cases develop following a second resurfacing hip arthroplasty, is suggestive of a type IV immune response, possibly to MoM metal alloy components.

The Oxford unicompartmental knee arthroplasty: a radiological perspective.

Unicompartmental knee arthroplasty (UKA) is increasingly being performed in both specialist centres as well as district hospitals. The radiologists should be aware of the required preoperative imaging, the normal appearance, and complications of this procedure. Unfortunately, very little is available in the radiology literature. This review aims to provide a radiological perspective to an already widely used procedure.

Acquired adult flat foot due to isolated plantar calcaneonavicular (spring) ligament insufficiency with a normal tibialis posterior tendon.

BACKGROUND: We present nine cases of acquired flat foot deformity (AFFD) in adults caused by isolated spring ligament insufficiency. METHODS: We present the clinical sign that allows differentiation of this diagnosis from posterior tibialis tendon (PTT) dysfunction namely the ability to single leg tiptoe, but with persistent forefoot abduction and heel valgus. In addition we illustrate the unique radiological features which allow confirmation of the diagnosis. Only a solitary previous case report has documented this alternative aetiology of AFFD; in that case, diagnosis was made intra-operatively. RESULTS: Six patients have been managed with orthoses. Three patients underwent surgery; one patient who presented early had isolated repair of the spring ligament complex. The remaining two required a calcaneal osteotomy and flexor digitorum longus transfer as for a PTT reconstruction. CONCLUSION: We propose that early diagnosis (with ultrasound confirmation) and management of this condition would offer a better prognosis and allow less interventional surgery.

Pre-operative clinical and radiological assessment of the patellofemoral joint in unicompartmental knee replacement and its influence on outcome.

Anterior knee pain and/or radiological evidence of degeneration of the patellofemoral joint are considered to be contraindications to unicompartmental knee replacement. The aim of this study was to determine whether this is the case. Between January 2000 and September 2003, in 100 knees (91 patients) in which Oxford unicompartmental knee replacements were undertaken for anteromedial osteoarthritis, pre-operative anterior knee pain and the radiological status of the patellofemoral joint were defined using the Altman and Ahlback systems. Outcome was evaluated at two years with the Oxford knee score and the American Knee Society score. Pre-operatively 54 knees (54%) had anterior knee pain. The clinical outcome was independent of the presence or absence of pre-operative anterior knee pain. Degenerative changes of the patellofemoral joint were seen in 54 patients (54%) on the skyline radiographs, including ten knees (10%) with joint space obliteration. Patients with medial patellofemoral degeneration had a similar outcome to those without. For some outcome measures patients with lateral patellofemoral degeneration had a worse score than those without, but these patients still had a good outcome, with a mean Oxford knee score of 37.6 (SD 9.5). These results show that neither anterior knee pain nor radiologically-demonstrated medial patellofemoral joint degeneration should be considered a contraindication to Oxford unicompartmental knee replacement. With lateral patellofemoral degeneration the situation is less well defined and caution should be observed.

Reporting of vertebral fragility fractures: can radiologists help reduce the number of hip fractures?

Patients with osteoporotic vertebral fractures are at increased risk of hip fracture. In a cohort of hip fracture patients, many had previous imaging studies showing incidental vertebral fractures. Fifty-four percent of fractures were not reported by the radiologist, highlighting a missed opportunity for diagnosing and treating osteoporosis, thereby preventing further fractures. PURPOSE: Patients with osteoporotic vertebral fragility fractures (VFFs) are at increased risk of future fractures, including hip fractures. Treating osteoporosis in these patients has the potential to reduce the risk of subsequent hip fractures, which are associated with high morbidity, mortality and cost. In this retrospective cohort study, we investigated the reporting and follow-up of VFFs evident on imaging by radiologists at the John Radcliffe Hospital, Oxford. MATERIALS AND METHODS: Data from the local Fracture Liaison Service was used to case-find all incident hip fractures from 2013 presenting to the trust. We then identified patients who had also undergone a radiological procedure that included the thoracic and/or lumbar spine in the previous 6 years. All identified radiological images were re-examined for the presence of VFFs using the Genant semi-quantitative method. RESULTS: Seven hundred and thirty-two patients over the age of 50 with a hip fracture in 2013 were identified. One hundred and fifty-seven patients had previously undergone a radiological procedure involving the spine, and VFFs were identified in 65/157 (41%). Of these, only 30/65 (46%) were reported by a radiologist when the fracture was first visible. 32/35 (91%) of unreported VFFs were from imaging reported by non-musculoskeletal radiologists. Only 16/65 (25%) of patients with a VFF were documented as being on bone-specific therapy at the time of hip fracture. CONCLUSIONS: Our study highlights the under-reporting of osteoporotic vertebral fractures, particularly by non-musculoskeletal radiologists. Better systems for reporting and referring osteoporotic VFFs are necessary to increase the number of patients receiving appropriate osteoporosis treatment.

Unsatisfactory outcomes following unicompartmental knee arthroplasty in patients with partial thickness cartilage loss: a medium-term follow-up.

AIMS: While medial unicompartmental knee arthroplasty (UKA) is indicated for patients with full-thickness cartilage loss, it is occasionally used to treat those with partial-thickness loss. The aim of this study was to investigate the five-year outcomes in a consecutive series of UKAs used in patients with partial thickness cartilage loss in the medial compartment of the knee. PATIENTS AND METHODS: Between 2002 and 2014, 94 consecutive UKAs were undertaken in 90 patients with partial thickness cartilage loss and followed up independently for a mean of six years (1 to 13). These patients had partial thickness cartilage loss either on both femur and tibia (13 knees), or on either the femur or the tibia, with full thickness loss on the other surface of the joint (18 and 63 knees respectively). Using propensity score analysis, these patients were matched 1:2 based on age, gender and pre-operative Oxford Knee Score (OKS) with knees with full thickness loss on both the femur and tibia. The functional outcomes, implant survival and incidence of re-operations were assessed at one, two and five years post-operatively. A subgroup of 36 knees in 36 patients with partial thickness cartilage loss, who had pre-operative MRI scans, was assessed to identify whether there were any factors identified on MRI that predicted the outcome. RESULTS: Knees with partial thickness cartilage loss had significantly worse functional outcomes at one, two and five years post-operatively compared with those with full thickness loss. A quarter of knees with partial thickness loss had a fair or poor result and a fifth failed to achieve a clinically significant improvement in OKS from a baseline of four points or more; double that seen in knees with full thickness loss. Whilst there was no difference in implant survival between the groups, the rate of re-operation in knees with partial thickness loss was three times higher. Most of the re-operations (three-quarters), were arthroscopies for persistent pain. Compared with those achieving good or excellent outcomes, patients with partial thickness cartilage loss who achieved fair or poor outcomes were younger and had worse pre-operative functional scores. However, there were no other differences in the baseline demographics. MRI findings of full thickness cartilage loss, subchondral oedema, synovitis or effusion did not provide additional prognostic information. CONCLUSION: Medial UKA should be reserved for patients with full thickness cartilage loss on both the femur and tibia. Whilst some patients with partial thickness loss achieve a good result we cannot currently identify which these will be and in this situation MRI is unhelpful and misleading. Cite this article: Bone Joint J 2017;99-B:475-82.

Anterior knee pain and evidence of osteoarthritis of the patellofemoral joint should not be considered contraindications to mobile-bearing unicompartmental knee arthroplasty: a 15-year follow-up.

AIMS: It is not clear whether anterior knee pain and osteoarthritis (OA) of the patellofemoral joint (PFJ) are contraindications to medial unicompartmental knee arthroplasty (UKA). Our aim was to investigate the long-term outcome of a consecutive series of patients, some of whom had anterior knee pain and PFJ OA managed with UKA. PATIENTS AND METHODS: We assessed the ten-year functional outcomes and 15-year implant survival of 805 knees (677 patients) following medial mobile-bearing UKA. The intra-operative status of the PFJ was documented and, with the exception of bone loss with grooving to the lateral side, neither the clinical or radiological state of the PFJ nor the presence of anterior knee pain were considered a contraindication. The impact of radiographic findings and anterior knee pain was studied in a subgroup of 100 knees (91 patients). RESULTS: There was no relationship between functional outcomes, at a mean of ten years, or 15-year implant survival, and pre-operative anterior knee pain, or the presence or degree of cartilage loss documented intra-operatively at the medial patella or trochlea, or radiographic evidence of OA in the medial side of the PFJ. In 6% of cases there was full thickness cartilage loss on the lateral side of the patella. In these cases, the overall ten-year function and 15-year survival was similar to those without cartilage loss; however they had slightly more difficulty with descending stairs. Radiographic signs of OA seen in the lateral part of the PFJ were not associated with a definite compromise in functional outcome or implant survival. CONCLUSION: Severe damage to the lateral side of the PFJ with bone loss and grooving remains a contraindication to mobile-bearing UKA. Less severe damage to the lateral side of the PFJ and damage to the medial side, however severe, does not compromise the overall function or survival, so should not be considered to be a contraindication. However, if a patient does have full thickness cartilage loss on the lateral side of the PFJ they may have a slight compromise in their ability to descend stairs. Pre-operative anterior knee pain also does not compromise the functional outcome or survival and should not be considered to be a contraindication. Cite this article: Bone Joint J 2017;99-B:632-9.

Which imaging modality is most effective for identifying pseudotumours in metal-on-metal hip resurfacings requiring revision: ultrasound or MARS-MRI or both?

AIMS: The aims of this study were to compare the diagnostic test characteristics of ultrasound alone, metal artefact reduction sequence MRI (MARS-MRI) alone, and ultrasound combined with MARS-MRI for identifying intra-operative pseudotumours in metal-on-metal hip resurfacing (MoMHR) patients undergoing revision surgery. METHODS: This retrospective diagnostic accuracy study involved 39 patients (40 MoMHRs). The time between imaging modalities was a mean of 14.6 days (0 to 90), with imaging performed at a mean of 5.3 months (0.06 to 12) before revision. The prevalence of intra-operative pseudotumours was 82.5% (n = 33). RESULTS: Agreement with the intra-operative findings was 82.5% (n = 33) for ultrasound alone, 87.5% (n = 35) for MARS-MRI alone, and 92.5% (n = 37) for ultrasound and MARS-MRI combined. The diagnostic characteristics for ultrasound alone and MARS-MRI alone reached similar sensitivities (90.9% vs 93.9%) and positive predictive values (PPVs; 88.2% vs 91.2%), but higher specificities (57.1% vs 42.9%) and negative predictive values (NPVs; 66.7% vs 50.0%) were achieved with MARS-MRI. Ultrasound and MARS-MRI combined produced 100% sensitivity and 100% NPV, whilst maintaining both specificity (57.1%) and PPV (91.7%). For the identification of a pseudotumour, which was confirmed at revision surgery, agreement was substantial for ultrasound and MARS-MRI combined (κ = 0.69), moderate for MARS-MRI alone (κ = 0.54), and fair for ultrasound alone (κ = 0.36). DISCUSSION: These findings suggest that ultrasound and/or MARS-MRI have a role when assessing patients with a MoMHR, with the choice dependent on local financial constraints and the availability of ultrasound expertise. However in patients with a MoMHR who require revision, combined imaging was most effective. TAKE HOME MESSAGE: Combined imaging with ultrasound and MARS-MRI always identified intra-operative pseudotumours if present. Furthermore, if neither imaging modality showed a pseudotumour, one was not found intra-operatively.

The MRI diagnosis and management of incomplete intertrochanteric fractures of the femur.

Incomplete intertrochanteric fractures do not extend across to the medial femoral cortex and are stable, without rotational deformity or shortening of the lower limb. The aim of our study was to establish whether they can be successfully managed conservatively. A total of 68 patients over a five-year period presented with a suspected fracture of the femoral neck and underwent an MRI scan for further assessment. From these, we retrospectively reviewed eight patients with normal plain radiographs but with an incomplete, intertrochanteric fracture on MRI scan. Five were managed conservatively and three operatively. The mean length of hospital stay was 16 days for the conservatively-treated group and 15 days for those who underwent surgery; this was not statistically significant (p > 0.5) and all patients were mobilised on discharge. Although five patients were readmitted at a mean of 3.2 years after discharge, none had progressed to a complete fracture. We believe that patients with incomplete intertrochanteric fractures should be considered for conservative treatment.

Pregnancy-associated osteoporosis.

The clinical features, investigation and outcome in 24 patients with pregnancy-associated osteoporosis, followed for up to 24 years from the first pregnancy are described. Symptoms occurred most often in the first pregnancy (17 patients) at a mean age of 27 years (range 21-36); the most frequent was back pain in late pregnancy or post partum (n = 18); less common was hip (n = 5) or ankle (n = 1) pain. In most, symptoms improved soon after delivery. Four subjects had pre-existing disorders known to reduce bone density (corticosteroid therapy, heparin treatment, mild osteogenesis imperfecta and previous anorexia nervosa). Radiographs showed vertebral collapse or localized osteoporosis of the hip, with MRI evidence of oedema. Forearm bone mineral density (BMD) was sometimes normal, but spinal BMD (measured by DXA) was low. Bone biopsies in eleven patients showed features compatible with osteoblast failure. Except for the patient with mild osteogenesis imperfecta, cultured dermal fibroblasts synthesized and exported normal Type I collagen. In 14 subsequent pregnancies (10 patients) there was no recurrence in ten and mild symptoms in the remainder. Excluding one patient who had repeated osteoporotic fractures and vertebral collapse, the long-term prognosis was good.

Can MRI of the knee affect arthroscopic practice? A prospective study of 58 patients.

We made a prospective study of 58 patients with suspected internal derangement of the knee. They were examined by magnetic resonance imaging using 3-D gradient echo intermediate-weighted studies before having an arthroscopy. The preoperative clinical assessment was found to have a diagnostic sensitivity of 77% and a specificity of 43%, compared with 100% and 63% respectively for magnetic resonance imaging. Comparison of magnetic resonance imaging and arthroscopy confirmed the accuracy of magnetic resonance imaging in the diagnosis of internal derangement but the results for articular cartilage lesions were much less good, with a sensitivity of only 18% but a specificity of 100%. Acceptance of the magnetic resonance imaging findings could have resulted in a 29% reduction in the number of arthroscopies without missing any significant meniscal lesion.

Genetic influences in the aetiology of tears of the rotator cuff. Sibling risk of a full-thickness tear.

From a retrospective, cohort study of 205 patients diagnosed with full-thickness tears of the rotator cuff, we determined, using ultrasound, the prevalence of such tears in their 129 siblings. Using 150 spouses as controls, the relative risk of full-thickness tears in siblings versus controls was 2.42 (95% CI 1.77 to 3.31). The relative risk of symptomatic full-thickness tears in siblings versus controls was 4.65 (95% CI 2.42 to 8.63). The significantly increased risk for tears in siblings implies that genetic factors play a major role in the development of full-thickness tears of the rotator cuff.

Prevalence and epidemiological variation of anomalous muscles at guyon's canal.

Ultrasound was performed in 116 wrists of asymptomatic volunteers to determine the prevalence and morphology of anomalous muscles in Guyon's canal in the normal population. The size of the muscle was correlated with sex, hand-dominance and occupation. Anomalous muscles were identified in 47% of volunteers and 35% of wrists (male prevalence (50%); female prevalence (21%)). All were variants of abductor digiti minimi. Bilateral muscles were present in 50% of index cases in both sexes. Mean muscle thickness was 1.7 mm overall with no inter-sex variation. Muscle thickness did not vary with hand dominance or manual employment. The prevalence of anomalous muscles is higher than previously reported and may be sex-linked. The size of the muscle may be an important factor in determining whether an anomalous muscle is significant in cases of ulnar nerve compression at Guyon's canal.

Discrete mineralisation of the acetabular labrum: a novel marker of femoroacetabular impingement?

Femoroacetabular impingement (FAI) is increasingly thought to play a role in the development of hip osteoarthritis, but is difficult to define clinically and on imaging. This study investigates mineralisations of the acetabular labrum (MALs), which are small, discrete foci of dense radio-opacity within the region of the acetabular labrum. The study aims to characterise MALs and test the hypothesis that MALs are associated with FAI. CT images and radiographs of 106 hips in 66 individuals without known FAI were reviewed for the presence of MALs. The anatomical locations of the MALs in the acetabular labrum were measured. Three current radiographic markers of FAI were recorded in hips with MALs and in age- and gender-matched hips without MALs: centre-edge angle and acetabular version angle as measures of pincer impingement, and alpha angle as a measure of cam impingement. MALs were identified in 18% of hips (n=19). Hips with MAL had a larger mean alpha angle (p=0.013) than those without. MALs were found to be located anterosuperiorly and posterosuperiorly within the labrum, consistent with coup and contrecoup impingement lesion locations reported for FAI. No significant association was found between MAL and centre-edge angle or version angle. Our data demonstrate that MALs are associated with increased alpha angle and thus may be linked to cam-type FAI. MALs have not previously been associated with FAI. This correlation may give further insight into the disease process underlying hip osteoarthritis and might represent a future radiographic marker of cam-type FAI.

Locally aggressive fibrous dysplasia.

Although fibrous dysplasia (FD) is a benign fibro-osseous lesion, locally aggressive behaviour has rarely been described but is poorly characterised. In this study, we document clinical, radiological and pathological (including molecular genetics) findings in three cases of locally aggressive FD, two of which involved the ribs. Lesions in these cases, one of which was a recurrent lesion, were followed up for 2-7 years. All of the lesions showed typical histological features of FD but were characterised by extension through the bone cortex into the extra-osseous soft tissue. The lesions did not exhibit overexpression/amplification of CDK4 and MDM2; in two of the cases, a GNAS mutation was identified. Our findings confirm that FD can rarely exhibit locally aggressive behaviour with extension beyond the bone compartment into the surrounding soft tissue; these lesions can be distinguished from low-grade intramedullary osteosarcoma by lack of amplification/overexpression of CDK4 and MDM2 and the presence of a GNAS mutation.

Skyline patellofemoral radiographs can only exclude late stage degenerative changes.

Accurate preoperative assessment of the patellofemoral joint is especially important in compartment specific knee arthritis. This study aims to show the actual intraoperative grade of patellofemoral cartilage damage that may be reliably detected or excluded by preoperative standard radiographic views. 100 consecutive knees awaiting arthroplasty underwent preoperative lateral and skyline radiographs and were scored using the Ahlback score. Intraoperative cartilage damage was assessed using the Collins score. The sensitivity and specificity were calculated for each grade of cartilage damage. Preoperative anterior knee pain and function were assessed and correlated to the degree of cartilage damage. The lateral radiograph shows poor sensitivity for all grades of disease (0.05-0.23). The skyline shows good sensitivity for grade 4 (large full thickness) damage (0.90) but decreases substantially for grades 1-3 (0.19-0.46). Significantly more people with skyline radiograph joint space narrowing complained of anterior knee pain than those with a normal radiograph (p<0.001). There was only a poor correlation between preoperative anterior pain and intraoperative patellofemoral cartilage damage (r=0.24). The lateral radiograph cannot exclude even large areas of full thickness cartilage damage whereas a normal skyline radiograph can reliably exclude significant (grade 4) patellofemoral disease and should be used in addition to the lateral view.

The patho-anatomy of patellofemoral subluxation.

Patella subluxation assessed on dynamic MRI has previously been shown to be associated with anterior knee pain. In this MRI study of 60 patients we investigated the relationship between subluxation and multiple bony, cartilaginous and soft-tissue factors that might predispose to subluxation using discriminant function analysis. Patella engagement (% of patella cartilage overlapping with trochlea cartilage) had the strongest relationship with subluxation. Patellae with > 30% engagement tended not to sublux; those with < 30% tended to sublux. Other factors that were associated with subluxation included the tibial tubercle-trochlea notch distance, vastus medialis obliquus distance from patella, patella alta, and the bony and cartilaginous sulcus angles in the superior part of the trochlea. No relationship was found between subluxation and sulcus angles for cartilage and bone in the middle and lower part of the trochlea, cartilage thicknesses and Wiberg classification of the patella. This study indicates that patella engagement is a key factor associated with patellar subluxation. This suggests that in patients with anterior knee pain with subluxation, resistant to conservative management, surgery directed towards improving patella engagement should be considered. A clinical trial is necessary to test this hypothesis.