Sensitivity, specificity and accuracy of magnetic resonance imaging for differentiating vertebral compression fractures caused by malignancy, osteoporosis, and infections.

PURPOSE: To evaluate the sensitivity, specificity and accuracy of various magnetic resonance imaging (MRI) features in differentiating vertebral compression fractures caused by malignancy, osteoporosis, and infections. METHODS: 35 men and 45 women aged 40 to 78 (mean, 59) years underwent MRI to assess the underlying pathology of already diagnosed vertebral compression fractures (n=152). The interval from presentation to imaging ranged from 7 to 95 (mean, 62) days. MRI features of each vertebral compression fracture were assessed. The sensitivity, specificity, and accuracy for each of the MRI features were calculated. Association between each MRI feature and various underlying pathologies (malignancy, osteoporosis, and infections) of vertebral compression fractures was evaluated. RESULTS: Regarding these 80 patients, the MRI diagnosis was correct in 78 and inconclusive in 2 with malignancy. MRI features suggestive of malignant fractures were a convex posterior border of the vertebral body, pedicle involvement, posterior neural element involvement, an epidural mass, a paraspinal mass, and other spinal metastases. MRI features suggestive of osteoporotic fractures were retropulsion, low signal intensity band, spared normal marrow signal intensity, and the fluid sign. MRI features suggestive of infective fractures were contiguous vertebral involvement, end plate disruption, disc involvement, and paraspinal and epidural abscesses. CONCLUSION: Combination of several MRI features can provide clues to differentiate between malignant, osteoporotic, and infective vertebral compression fractures.

Treatment of benign bone tumours using external fixation.

We present a retrospective study of patients suffering from a variety of benign tumours in whom external fixators were used to treat deformity and limb-length discrepancy, and for the reconstruction of bone defects. A total of 43 limbs in 31 patients (12 male and 19 female) with a mean age of 14 years (2 to 54) were treated. The diagnosis was Ollier's disease in 12 limbs, fibrous dysplasia in 11, osteochondroma in eight, giant cell tumour in five, osteofibrous dysplasia in five and non-ossifying fibroma in two. The lesions were treated in the tibia in 19 limbs, in the femur in 16, and in the forearm in eight. The Ilizarov frame was used in 25 limbs, the Taylor Spatial Frame in seven, the Orthofix fixator in six, the Monotube in four and the Heidelberg fixator in one. The mean follow-up was 72 months (22 to 221). The mean external fixation period was 168 days (71 to 352). The mean external fixation index was 42 days/cm (22.2 to 102.0) in the 22 patients who required limb lengthening. The mean correction angle for those with angular deformity was 23 degrees (7 degrees to 45 degrees ). At final follow-up all patients had returned to normal activities. Four patients required a second operation for recurrent deformity of further limb lengthening. Local recurrence occurred in one patient, requiring further surgery.

Skeletal disorders associated with skin pigmentation: a role of melatonin?

Although frequently encountered, no available consensus about the association between skeletal abnormalities and skin pigmentation. Several syndromes are characterized by the presence of skin pigmentation in association with skeletal disorders like neurofibroamtosis 1, McCune-Albright Syndrome, Jaffe-Campanacci Syndrome and Jaffe-Lichtenstein Syndrome. Even in the absence of these syndromes, skeletal abnormalities were detected in all radiologically examined patients having patterned skin pigmentation. Although skin pigmentation is controlled by several factors, melatonin is the most reliable factor to have relation to development of skeletal abnormalities. Recent research works support that melatonin might play a role in bone development and several hypotheses link melatonin with some bone diseases associated with skin pigmentation. It seems that melatonin deficiency is a probable operating co-factor in a lot of clinical situations characterized by skin pigmentation and skeletal disorders. This would explain some of the un-explained observations related to these syndromes and research works along these lines might lead to the development of efficient treatment for these diseases.

Bone development in neurofibromatosis 1.

Bony abnormalities are common findings in cases of neurofibromatosis 1. We might hypothesize that neurofibromin, the protein encoded by the neurofibromatosis 1 gene, plays important roles in bone development. Loss of function of oligodendrocyte-myelin glycoprotein gene and increased activity of ras p21 might increase the level of c-fos proto-oncogene in bones with formation of fibrous dysplasia-like tissue. Also, increased ras p21 might disturb collagen I synthesis by osteoblasts. Moreover, increased ras activity might increase the mitogenic signals to the nucleus through mitogen-activated protein kinase (MAPK) and disturb the level of the transcription factor core-binding factor alpha(1) (Cbfa1). Abnormal fibrous tissue and neurofibromas formed at the site of pseudarthrosis might represent abnormal response of periosteal fibroblasts for injury, an effect simulating the response of skin fibroblasts in neurofibromatosis 1 to injury.

Osteosarcoma around the knee. Intraepiphyseal excision and biological reconstruction with distraction osteogenesis.

In 11 patients juxta-articular osteosarcoma around the knee was treated by intraepiphyseal excision of the tumour and reconstruction of the bone defect by distraction osteogenesis. Preoperative and postoperative chemotherapy was given to eight patients with high-grade tumours. The articular cartilage of the epiphysis and a maximum of healthy soft tissues were preserved. Distraction osteogenesis was then carried out. The mean gain in length was 9.7 cm. Full function of the limb was preserved in all except one patient, with a mean follow-up of 53.8 months. Treatment of juxta-articular osteosarcomas around the knee with joint preservation and biological reconstruction using distraction osteogenesis can give excellent functional results.

Melatonin deficiency and fibrous dysplasia: might a relation exist?

Fibrous dysplasia of bone might be monostotic, polystotic, or occurs as a part of McCune-Albright syndrome and Jaffe-Lichtenstein syndrome. Activating mutations of GNAS1 gene was identified in patients with fibrous dysplasia. However, fibrous dysplasia might occur in the absence of these mutations and fibrous dysplastic tissue was produced in vitro by the effects of excess exogenous cAMP on human osteogenic cells. It was proved that the fibrous dysplastic tissue is deficient in bone sialoprotein. Melatonin deficiency might be hypothesized in syndromes associated with fibrous dysplasia or formation of fibrous dysplasia-like tissue. The receptor RZR/ROR is the nuclear receptor of melatonin and the human bone sialoprotein gene contains a RZR/ROR response element. It was supposed that binding of melatonin to its membrane receptors results in changes in the levels of activity of nuclear cAMP that lead to alteration of expression of bone sialoprotein. Also, melatonin deficiency might increase cAMP in bone through its effect on prostaglandins of the E group. Further, melatonin deficiency might explain precocious puberty in cases of McCune-Albright syndrome. We might hypothesize that melatonin deficiency might play a role in development of fibrous dysplasia in some cases.

Cannulation of simple bone cysts.

We describe a consecutive series of 26 patients with simple bone cysts who were treated by curettage, multiple drilling and continuous decompression by the insertion of either a cannulated screw or a pin. In the first 15 patients we used titanium cannulated screws (group 1) and in the next 11 a cannulated hydroxyapatite pin (group 2). Satisfactory healing was achieved in 12 patients in group 1 (80%) and in all in group 2. This technique seems to be a promising option for the treatment of simple bone cysts. The cannulated hydroxyapatite pin is recommended because of its higher success rate and the fact that it does not need to be removed.

Simple bone cyst is not a single entity: point of view based on a literature review.

Three varieties of simple bone cysts have not attracted a lot of clinical attention: simple bone cysts in non-tubular bones, multiple cysts and epiphyseal cysts. Simple bone cysts occurring in non-tubular bones form about 4-10% of total cases, with a higher age incidence and better prognosis. Epiphyseal simple bone cysts have a higher age incidence, a lower male/female ratio, a very high humerus/femur ratio and higher incidence of tibial location than the classic metaphyseal cysts. Multiple cysts occur in the higher age group and show very high male predominance. In the review of the literature, 15 cysts (35.7%) were in non-tubular bones and six cysts (14.3%) were epiphyseal. They have a better prognosis than the classic metaphyseal ones. Four clinico-anatomic varieties of simple bone cysts could be recognized: classic metaphyseal, non-tubular, epiphyseal, and multiple. Venous obstruction might be the cause of all forms of the disease but the etiologies of venous obstruction causing the last three clinical forms might be different from that causing the classic metaphyseal ones.

Total en bloc spondylectomy.

We have developed a surgical technique of total en bloc spondylectomy (TES) through a posterior approach applied to solitary metastatic vertebral tumors. Our TES is a radical en bloc resection of a whole vertebra in two parts with an oncological wide margin to obtain local curability. It consists of two steps: (1) en bloc laminectomy and setting of posterior spinal instrumentation for stabilization and (2) en bloc corpectomy and replacement by a vertebral prosthesis. We have performed this procedure in 72 patients with malignant vertebral tumors. Three of these 72 patients had local recurrence. TES is the most radical method for malignant spinal tumors.

The association of neurofibromatosis 1 and spinal deformity with primary hyperparathyroidism and osteomalacia: might melatonin have a role?

A 35-year-old woman with neurofibromatosis 1 and thoracic kyphoscoliosis had incomplete paraplegia. She had a history of hyperparathyroidism due to a parathyroid adenoma which had been excised 4 years previously. Plain radiographs of the spine revealed kyphoscoliosis from the third to sixth thoracic vertebrae. Kyphosis and scoliosis angles were 86 degrees and 28 degrees, respectively. Radiographs of the skull and hands showed radiological changes suggestive of hyperparathyroidism. Laboratory tests showed low-normal serum calcium, hypophosphatemia, elevated serum alkaline phosphatase, and low serum 25-hydroxyvitamin D. Retrospective review of the patient's laboratory data showed that she had osteomalacia at the time of diagnosis of primary hyperparathyroidism. The patient had been treated by anterior and posterior decompression and fusion with posterior instrumentation through a single posterior approach. The postoperative kyphosis and scoliosis angles were 30 degrees and 12 degrees, respectively. Neurological recovery and spinal fusion had been achieved. Osteomalacia responded well to vitamin D therapy. This is the first case of coexisting neurofibromatosis 1, primary hyperparathyroidism due to parathyroid adenoma and osteomalacia to be reported in the literature. The osteomalacia in this patient could be related to primary hyperparathyroidism, and not to neurofibromatosis 1. A drop in melatonin level after parathyroidectomy may have been the cause of spinal curvature progression in this patient.

Aetiology of spinal deformities in neurofibromatosis 1: new hypotheses.

Neurofibromatosis 1 is a common heritable disorder. The gene causing neurofibromatosis 1 had been recognized and the protein encoded by this gene, neurofibromin, was supposed to play a role in development of various tissues. Neurofibromin was found to have GTP-ase (GAP) domain against small p21 ras. IQGAP1 is another human ras-specific GAP that was found to have calmodulin-binding motifs. Spinal deformities in cases of neurofibromatosis 1 are generally classified into dystrophic and non-dystrophic. Aetiologies of both types are still unknown. We hypothesize that muscle pathology could be the initiating factor for non-dystrophic curves due to neurofibromin deficiency and/or increase of the level of IQGAP. Dystrophic curves might begin as a developmental error due to neurofibromin deficiency in bone. Melatonin deficiency, increased serotonin level with disturbed melatonin-serotonin interactions and calmodulin antagonism by increased IQGAP1 may be responsible for progression of both types of spinal deformities in neurofibromatosis 1.

Bilateral symmetrical cysts in the upper tibiae in a skeletally mature patient: might they be simple bone cysts?

A 55-year-old Japanese woman presented with right knee pain of 1-month duration. Radiological studies revealed bilateral mild osteoarthritic changes in the medial knee joint compartment and symmetrical cysts in the upper tibial metaphyses, extending to the epiphyses. Intraosseous ganglion was considered the most probable diagnosis. However, intraoperatively, serous fluid-filled cavities were recognized; these were curetted and filled with hydroxyapatite granules. Histopathological examination of the cyst wall revealed thin fibrous tissue formed of collagen fibers without a lining cell layer, with scattered lymphocytes, histiocytes, irregular masses of fibrin-like material, and periosteal osteocartilagenous callus formation; a picture compatible with simple bone cysts. Bilateral symmetrical cysts of the upper tibial metaphyses extending to the epiphyses are extremely rare. A literature review revealed that the age incidence, and bony locations of multiple and epiphyseal simple bone cysts are atypical in relation to the classic metaphyseal simple bone cysts. Also, multiple and epiphyseal simple bone cysts have a better prognosis than the classic metaphyseal ones. Four clinicoanatomic varieties of simple bone cysts are recognized; classic metaphyseal, nontubular, epiphyseal, and multiple.