Richard W. Whitehouse

Chronic Recurrent Multifocal Osteomyelitis Mimicked in Childhood Hypophosphatasia

Hypophosphatasia (HPP) is the inborn error of metabolism characterized by low serum alkaline phosphatase (ALP) activity caused by inactivating mutations within TNSALP, the gene that encodes the “tissue‐nonspecific” isoenzyme of ALP (TNSALP). In HPP, extracellular accumulation of inorganic pyrophosphate, a TNSALP substrate, inhibits hydroxyapatite crystal growth leading to rickets or osteomalacia. Chronic recurrent multifocal osteomyelitis (CRMO) is the pediatric syndrome of periarticular pain and radiographic changes resembling infectious osteomyelitis but without lesional pathogens. Some consider CRMO to be an autoinflammatory disease. An unrelated boy and girl with the childhood form of HPP suffered chronic, multifocal, periarticular pain, and soft tissue swelling. To investigate this unusual complication, we evaluated their cumulative clinical, biochemical, radiological, and histopathological findings and performed mutation analysis of their TNSALP alleles. The earliest radiographic disturbances were typical of childhood HPP. Subsequently, changes consistent with CRMO developed at sites where there was pain, including lucencies, osteosclerosis, and marked expansion of the underlying metaphyses. Bone marrow edema was shown by MRI. Biopsies of affected bone showed nonspecific histopathological findings and no pathogens. The boy was heterozygous (c.1133A>T, p.D378V) and the girl compound heterozygous (c.350A>G, p.Y117C, c.400_401AC>CA, p.T134H) for different TNSALP missense mutations. Nonsteroidal anti‐inflammatory drugs diminished their pain, which improved or resolved at maturity. HPP should be considered when CRMO is a diagnostic possibility. Metaphyseal radiographic changes and marrow edema associated with periarticular bone pain and soft tissue swelling suggestive of osteomyelitis can complicate childhood HPP.

Calcific tendinitis of the gluteus maximus tendon with abonormalities of cortical bone

Calcific tendinitis of the gluteus maximus tendon is unusual and only eight cases associated with erosions of cortical bone have been reported. We present three further cases which demonstrate variation in appearances of the amorphous calcification in the tendon and cortical erosions on plain radiographs. Isotope bone scans show focal increased activity and computed tomography (CT) clearly demonstrates erosion of cortical bone and calcification within the tendon insertion of gluteus maximus. Follow-up examinations in two cases demonstrated resolution of the changes. We believe this series demonstrates the radiological features and natural history of a common condition occurring at an unusual site. Its recognition is important in order to avoid unnecessary surgical intervention. Resolution of the calcification and cortical erosions has not been previously described.

Use of Tobramycin-Impregnated Calcium Sulphate Pellets in Addition to Oral Antibiotics An alternative treatment to minor amputation in a case of diabetic foot osteomyelitis

To supplement surgical debridement, pellets of calcium sulfate (CS) were used as vehicles for local antibiotic delivery in treating osteomyelitis (1). We are aware of one case series in which diabetic pedal osteomyelitis was resolved with postoperatively implanted polymethylmethacrylate antibiotic beads and intravenous antibiotics (2). We now present a case of radiologically successful, nonsurgical management of diabetic foot osteomyelitis with tobramycin-impregnated CS pellets, in addition to oral antibiotic …

Low-dose computed tomographic imaging in orbital trauma

We review the findings in 75 computed tomographic (CT) examinations of 66 patients with orbital trauma who were imaged using a low-radiation-dose CT technique. Imaging was performed using a dynamic scan mode and exposure factors of 120 kVp and 80 mAs resulting in a skin dose of 11 mGy with an effective dose-equivalent of 0.22 mSv. Image quality was diagnostic in all cases and excellent in 73 examinations. Soft-tissue abnormalities within the orbit including muscle adhesions were well demonstrated both on primary axial and reconstructed multiplanar images. The benefits of multiplanar reconstructions are stressed and the contribution of soft-tissue injuries to symptomatic diplopia is examined.

The sesamoid index in psoriatic arthropathy

ObjectiveThe sesamoid index was originally described as an aid to the diagnosis of acromegaly. We performed this study to assess the value of the thumb sesamoid index in the diagnosis of psoriatic arthropathy.DesignRetrospective measurement of the sesamoid index (length × width of the medial thumb sesamoid), along with the age and sex were recorded for patients as described below. Patients with psoriasis were subdivided into those with or without radiographic evidence of hand arthropathy.PatientsFifty-nine consecutive patients attending rheumatology clinics with arthralgia and psoriasis were studied. Comparison groups with radiographic evidence of rheumatoid arthritis (52 patients), osteoarthritis (44) or normal hands (55) were also recorded.ResultsTwenty-one of 59 patients with psoriasis and arthropathy had a sesamoid index >40, compared with two of 52 with rheumatoid arthritis, none of 44 with osteoarthritis and none of 55 normals.ConclusionsPsoriatic arthropathy is a recognised cause of bone enlargement, usually in the phalanges due to periostitis and proliferative enthesopathy. We have confirmed that psoriatic hand arthropathy can cause significant enlargement of the thumb sesamoids, a feature which is easily quantified and may assist diagnosis.

Influence of temperature on QCT: implications for mineral densitometry.

Objective Inaccuracies in quantitative CT (QCT) for vertebral bone mineral measurements may result from differences between the temperature of the vertebrae and the calibration standards. This study aims to quantify these effects by using scans of marrow-equivalent materials and computer simulation. Materials and Methods The CT numbers of fat, water, gelatin suspension, and bone were measured within an anthropomorphic phantom at temperatures between −18 and 38αC. A computer simulation was then performed using these materials to represent marrow fat, soft tissue, and bone in varying proportions over this temperature range. Postprocessing single and dual energy QCT calculations were then performed on the data acquired from the simulation. Results A change of 80 HU in the CT number of water on cooling from 38 to −18°C was demonstrated. An increase of 95 HU in the CT number of fat occurred over the same temperature range. Dry cortical bone showed no change in CT number with temperature changes from 24 to - 18°C. In the computer simulation, the fat error associated with single energy QCT for trabecular bone mineral densitometry was 20% less for specimens at room temperature than at body temperature. In simulated frozen specimens, varying marrow fat/soft tissue composition had almost no effect on single energy QCT mineral densitometry. Dual energy QCT methods that use a fat-equivalent reference material were significantly influenced by the temperature of the specimen. Conclusion The fat error of single energy QCT for mineral densitometry may have been underestimated in previous in vitro studies using vertebral specimens scanned at room temperature. In the simulation, the fat error diminished as the temperature of the specimen was reduced and was negligible when frozen. Fat-equivalent reference materials used for dual energy QCT in vivo should have similar X-ray-attenuating properties at room temperature to those of marrow fat at body temperature.

The influence of chemical shift artifact on magnetic resonance imaging of the ligamentum flavum at 0.5 tesla

Study Design Retrospective clinical magnetic resonance imaging study and prospective magnetic resonance imaging volunteer study of the appearance of the ligamentum flavum. Objective To demonstrate the effect of chemical shift artifact on the apparent thickness of the ligamentum flavum on axial magnetic resonance images. Summary of Background Data The ligamentum flavum is a symmetric structure clearly seen on magnetic resonance images. Apparent unilateral thickening may be interpreted as indicating a pathologic process, and the influence of chemical shift artifact on the apparent thickness of the ligamentum flavum has not been emphasized. Methods Ligamenta flava thicknesses were measured from axial T1-weighted gradient echo magnetic resonance scans of 12 consecutive patients and various axial sequences in seven volunteers. Results The ligamentum flavum appeared consistently thicker on the lower side of the readout gradient field. This chemical shift effect could be manipulated by swapping phase and frequency or patient orientation in the magnet. Conclusions Caution should be applied in attributing apparent asymmetry of the ligamenta flava to disease; the influence of chemical shift artifact should be considered.

Dual Energy X-Ray Absorptiometry (DXA)

DXA is most commonly used to measure the mineral content of the skeleton, for the diagnosis and follow up of osteoporosis, but can also measure the fat and lean soft tissue content of the body.

Charcot neuroarthropathy: an unusual case and a review of the literature.

Charcot neuroarthropathy is a devastating consequence of diabetes, requiring early identification and immediate management. A differentiation should be made from osteomyelitis and other pathologies. The authors describe a case of Charcot foot with radiological findings of complete fragmentation of the calcaneum. Further investigation with magnetic resonance and white cell-labeled imaging revealed osteomyelitis. Below-knee amputation was the only therapeutic option in this hindfoot collapse complicated with osteomyelitis.

Spinal bone defects in neurofibromatosis type I with dural ectasia: stress fractures or dysplastic? A case series

ObjectivesNeurofibromatosis type I (NF1) is a multisystem neurocutaneous disorder with varied musculoskeletal manifestations. Dural ectasia is a known association, whilst pedicular anomalies have been described, although not as frequently as other skeletal manifestations. However, reports of pedicular and other spinal clefts or fractures in combination with dural ectasia in NF1 are scarce. We aimed to identify osseous defects in the posterior elements of NF1 patients with dural ectasia.MethodsImages of patients with NF1 and back pain were reviewed for osseous defects in the posterior elements.ResultsFour patients were identified with NF1, back pain, dural ectasia and bone defects. The imaging appearances of the defects are illustrated.ConclusionsDefects in the spinal posterior elements of patients with NF1, back pain and dural ectasia may be dysplastic, stress fractures or, most probably, multifactorial in origin. Computed tomography demonstrates these defects most clearly.Key Points• Dural ectasia with posterior element dysplasia is common in neurofibromatosis.• Pedicle defects, which may be stress fractures, occur in NF1.• Posterior element defects should be sought in NF1 patients with back pain.