We describe the use of MRI to establish the exact diagnosis in a swollen elbow in a neonate. Urgent diagnosis was needed for medical and social reasons. We accomplished this without the use of an invasive procedure or anaesthesia for a fracture that is recognised to be difficult to diagnose in patients of this age group

Our aim was to determine whether abnormalities noted on MRI immediately after reduction for developmental dysplasia of the hip could predict the persistance of dysplasia and aid surgical planning. Scans of 13 hips in which acetabular dysplasia had resolved by the age of four years were compared with those of five which had required pelvic osteotomy for persisting dysplasia. The scans were analysed by two consultant musculoskeletal radiologists who were blinded to the outcome in each child. The postreduction scans highlighted a number of anatomical abnormalities secondary to developmental dysplasia of the hip, but statistical analysis showed that none were predictive of persisting acetabular dysplasia in the older child, suggesting that the factors which determine the long-term outcome were not visible on these images

The extent of necrosis is the main determining factor in the outcome of osteonecrosis of the femoral head and is best measured by MRI. Using statistical analyses, we have evaluated the accuracy and repeatability of seven different methods of measuring the extent of necrosis, of which three demonstrate good or acceptable accuracy. For the general observer their repeatability is poor; only for experienced observers were they reasonable. We conclude that within an institution or for personal use, the accuracy of some methods is acceptable, and repeatability reasonable. None is appropriate for international use

Total hip replacement in patients with advanced osteonecrosis of the femoral head is often complicated by early loosening of the femoral component. Recent evidence has suggested that abnormal bone extending into the proximal femur may be responsible for the early failure of the femoral component. We aimed to identify which patients were at high risk of early failure by evaluating gadolinium-enhanced MR images of histologically-confirmed osteonecrotic lesions beyond the femoral head. Although the MR signal intensity has been shown to correlate well with osteonecrosis in the femoral head, it was found to be relatively insensitive at identifying lesions below the head, with a sensitivity of only 51% and a predictive value of a negative result of only 48%. However, the specificity was 90%, with the predictive value of a positive MRI finding being 86%. Only those patients with osteonecrosis of the femoral head secondary to sickle-cell disease, who are known to be at high risk of early loosening, had changes in the MR signal in the greater trochanter and the femoral shaft. This observation suggests that changes in the MR signal beyond the femoral head may represent osteonecrotic lesions in areas essential for the fixation of the femoral component. Pre-operative identification of such lesions in the neck of the femur may be important when considering hip resurfacing for osteonecrosis of the femoral head, following which early loosening of the femoral component and fracture of the neck are possible complications

We reviewed retrospectively the MRI examinations of 108 knees of 80 children to identify the prevalence of a high signal in the menisci of those without symptoms. There were 51 boys and 29 girls with a mean age of 12.2 years (8 to 15). The prevalence of a high signal within the menisci was 66%, significantly higher than that in an adult group (29%). The prevalence decreased with age: grade-2 and grade-3 changes were observed in 80% of menisci at ten years of age, in 65% at 13 years and in 35% at 15 years. The prevalence of high signals also decreased with increased skeletal maturity at the knee. We emphasise the importance of awareness of the high prevalence of a high signal intensity in the menisci of children, especially in early adolescence

Aims

Internal hemipelvectomy without reconstruction of the pelvis is a viable treatment for pelvic sarcoma; however, the time it takes to return to excellent function is quite variable. Some patients require greater time and rehabilitation than others. To determine if psoas muscle recovery is associated with changes in ambulatory function, we retrospectively evaluated psoas muscle size and limb-length discrepancy (LLD) before and after treatment and their correlation with objective functional outcomes.

Aims

The Oswestry-Bristol Classification (OBC) is an MRI-specific assessment tool to grade trochlear dysplasia. The aim of this study is to validate clinically the OBC by demonstrating its use in selecting treatments that are safe and effective.

We used gadolinium-enhanced fat-suppressed MRI to investigate 67 patients with persistent pain after lumbar discectomy. Twenty-five patients had reoperations for lesions diagnosed in this way. Eleven were for recurrent disc prolapse at the same level and sciatica was relieved by all but one. Five operations were for prolapse at an adjacent level and all were successful. The diagnosis of sepsis was less precise, but extension of tissue enhancement into the operated disc space was found to be significant. Only three patients had evidence of arachnoiditis which suggests that this condition has been too often diagnosed as a cause of persisting low back pain

We studied active flexion from 90° to 133° and passive flexion to 162° using MRI in 20 unloaded knees in Japanese subjects. Flexion over this arc is accompanied by backward movement of the medial femoral condyle of 4.0 mm and by backward movement laterally of 15 mm, i.e., by internal rotation of the tibia. At 162° the lateral femoral condyle lies posterior to the tibia

In 13 unloaded living knees we confirmed the findings previously obtained in the unloaded cadaver knee during flexion and external rotation/internal rotation using MRI. In seven loaded living knees with the subjects squatting, the relative tibiofemoral movements were similar to those in the unloaded knee except that the medial femoral condyle tended to move about 4 mm forwards with flexion. Four of the seven loaded knees were studied during flexion in external and internal rotation. As predicted, flexion (squatting) with the tibia in external rotation suppressed the internal rotation of the tibia which had been observed during unloaded flexion

We have reviewed 37 patients under the age of 18 years with lesions of the lumbar posterior end plate. All but one were active in sport, and most were seen because of low back pain. An abnormality was commonly found at the inferior rim of the body of L4 and at the superior rim of the sacrum. All adjacent intervertebral discs showed a decrease of signal intensity on the T2-weighted MRI. In 12 patients there was no interposed tissue at the posterior end-plate lesions. When disc material had migrated posteriorly none protruded beyond the posterior margin of the end plate, the dissociated portion of which was the main element compressing neural tissue. The posterior end-plate lesion should be regarded as a vertebral non-articular osteochondrosis

We studied MR images of the spine in a consecutive series of 100 patients with acute compression of the spinal cord due to metastases. All patients had documented neurological deficit and histologically proven carcinoma. MRI was used to localise bony metastatic involvement and soft-tissue impingement of the cord. A systematic method of documenting metastatic involvement is described. A total of 43 patients had compression at multiple levels; 160 vertebral levels were studied. In 120 vertebrae (75%), anterior, lateral and posterior bony elements were involved. Soft-tissue impingement of the spinal cord often involved more than one quadrant of its circumference. In 69 vertebrae (43%) there was concomitant anterior and posterior compression. Isolated involvement of a vertebral body was observed in only six vertebrae (3.8%). We have shown that in most cases of acute compression of the spinal cord due to metastases there is coexisting involvement of both anterior and posterior structures

Aims. This prospective randomised controlled trial was designed to evaluate the outcome of both the MRI- and CT-based patient-specific matched guides (PSG) from the same manufacturer. Patients and Methods. A total of 137 knees in 137 patients (50 men, 87 women) were included, 67 in the MRI- and 70 in the CT-based PSG group. Their mean age was 68.4 years (47.0 to 88.9). Outcome was expressed as the biomechanical limb alignment (centre hip-knee-ankle: HKA-axis) achieved post-operatively, the position of the individual components within 3° of the pre-operatively planned alignment, correct planned implant size and operative data (e.g. operating time and blood loss). Results. The patient demographics (e.g. age, body mass index), correct planned implant size and operative data were not significantly different between the two groups. The proportion of outliers in the coronal and sagittal plane ranged from 0% to 21% in both groups. Only the number of outliers for the posterior slope of the tibial component showed a significant difference (p = 0.004) with more outliers in the CT group (n = 9, 13%) than in the MRI group (0%). . Conclusion. The post-operative HKA-axis was comparable in the MRI- and CT-based PSGs, but there were significantly more outliers for the posterior slope in the CT-based PSGs. Take home message: Alignment with MRI-based PSG is at least as good as, if not better, than that of the CT-based PSG, and is the preferred imaging modality when performing TKA with use of PSG. Cite this article: Bone Joint J 2016;98-B:786–92

Patients from a randomised trial on resurfacing hip arthroplasty (RHA) (n = 36, 19 males; median age 57 years, 24 to 65) comparing a conventional 28 mm metal-on-metal total hip arthroplasty (MoM THA) (n = 28, 17 males; median age 59 years, 37 to 65) and a matched control group of asymptomatic patients with a 32 mm ceramic-on-polyethylene (CoP) THA (n = 33, 18 males; median age 63 years, 38 to 71) were cross-sectionally screened with metal artefact reducing sequence-MRI (MARS-MRI) for pseudotumour formation at a median of 55 months (23 to 72) post-operatively. MRIs were scored by consensus according to three different classification systems for pseudotumour formation. . Clinical scores were available for all patients and metal ion levels for MoM bearing patients. . Periprosthetic lesions with a median volume of 16 mL (1.5 to 35.9) were diagnosed in six patients in the RHA group (17%), one in the MoM THA group (4%) and six in the CoP group (18%). The classification systems revealed no clear differences between the groups. Solid lesions (n = 3) were exclusively encountered in the RHA group. Two patients in the RHA group and one in the MoM THA group underwent a revision for pseudotumour formation. There was no statistically significant relationship between clinical scoring, metal ion levels and periprosthetic lesions in any of the groups. . Periprosthetic fluid collections are seen on MARS-MRI after conventional CoP THA and RHA and may reflect a soft-tissue collection or effusion. . Currently available MRI classification systems seem to score these collections as pseudotumours, causing an-overestimatation of the incidence of pseudotumours. . Cite this article: Bone Joint J 2015;97-B:1175–82

We studied the use of gadolinium diethylenetriaminepentaacetic acid-enhanced MRI in the detection of pathological changes in the nerve roots of 25 patients with unilateral sciatica due to lumbar disc herniation. Enhancement was observed in the affected nerve roots within the root sleeve at the caudal edge of the herniation and was classified into three categories: grade 0, none; grade 1, enhancement restricted to a focal region within the sleeve; and grade 2, diffuse and homogeneous. The grade of enhancement correlated well with the severity of the sciatica, and was considered to be due to a disruption of the blood-nerve barrier, leading to oedema

We scanned 25 left knees in healthy human subjects using MRI. Multiplanar reconstruction software was used to take measurements of the inferior and posterior facets of the femoral condyles and the trochlea. A ‘basic circle’ can be defined which, in the sagittal plane, fits the posterior and inferior facets of the lateral condyle, the posterior facet of the medial condyle and the floor of the groove of the trochlea. It also approximately fits both condyles in the coronal plane (inferior facets) and the axial plane (posterior facets). The circle fitting the inferior facet of the medial condyle in the sagittal plane was consistently 35% larger than the other circles and was termed the ‘medial inferior circle’. There were strong correlations between the radii of the circles, the relative positions of the centres of the condyles, the width of the condyles, the total knee width and skeletal measurements including height. There was poor correlation between the radii of the circles and the position of the trochlea relative to the condyles. In summary, the condyles are approximately spherical except for the inferior facet medially, which has a larger radius in the sagittal plane. The size and position of the condyles are consistent and change with the size of the person. However, the position of the trochlea is variable even though its radius is similar to that of the condyles. This information has implications for understanding anterior knee pain and for the design of knee replacements. Cite this article: Bone Joint J 2014;96-B:1623–30

Although it is clear that opening-wedge high tibial osteotomy (HTO) changes alignment in the coronal plane, which is its objective, it is not clear how this procedure affects knee kinematics throughout the range of joint movement and in other planes. Our research question was: how does opening-wedge HTO change three-dimensional tibiofemoral and patellofemoral kinematics in loaded flexion in patients with varus deformity?Three-dimensional kinematics were assessed over 0° to 60° of loaded flexion using an MRI method before and after opening-wedge HTO in a cohort of 13 men (14 knees). Results obtained from an iterative statistical model found that at six and 12 months after operation, opening-wedge HTO caused increased anterior translation of the tibia (mean 2.6 mm, p <  0.001), decreased proximal translation of the patella (mean –2.2 mm, p <  0.001), decreased patellar spin (mean –1.4°, p < 0.05), increased patellar tilt (mean 2.2°, p < 0.05) and changed three other parameters. The mean Western Ontario and McMaster Universities Arthritis Index improved significantly (p < 0.001) from 49.6 (standard deviation (. sd. ) 16.4) pre-operatively to a mean of 28.2 (. sd. 16.6) at six months and a mean of 22.5 (. sd.  14.4) at 12 months. The three-dimensional kinematic changes found may be important in explaining inconsistency in clinical outcomes, and suggest that measures in addition to coronal plane alignment should be considered. . Cite this article: Bone Joint J 2014; 96-B:1214–21

The purpose of this study was to investigate the development of the osseous acetabular index (OAI) and cartilaginous acetabular index (CAI) using MRI. The OAI and CAI were measured on the coronal MR images of the hip in 81 children with developmental dysplasia of the hip (DDH), with a mean age of 19.6 months (3 to 70), and 241 normal control children with a mean age of 5.1 years (1 month to 12.5 years). Additionally the developmental patterns of the OAI and CAI in normal children were determined by age-based cross-sectional analysis. Unlike the OAI, the normal CAI decreased rapidly from a mean of 10.17° (. sd. 1.60) to a mean of 8.25° (. sd. 1.90) within the first two years of life, and then remained constant at a mean of 8.04° (. sd. 1.65) until adolescence. Although no difference in OAI was found between the uninvolved hips in children with unilateral DDH and normal hips (p = 0.639), the CAI was significantly different between them both (p < 0.001). The normal CAI has fully formed at birth, and is maintained constantly throughout childhood. The CAI in the unaffected hips in children with unilateral DDH is also mildly dysplastic