A pictorial review of atlanto-axial rotatory fixation: key points for the radiologist.

Atlanto-axial rotatory fixation (AARF) is a rare condition which occurs more commonly in children than in adults. The terminology can be confusing and the condition is also known as 'atlanto-axial rotatory subluxation' and 'atlanto-axial rotary dislocation'. Rotatory fixation is the preferred term, however, as in most cases the fixation occurs within the normal range of rotation of the joint. By definition, therefore, the joint is neither subluxed nor dislocated. AARF is a cause of acquired torticollis. Diagnosis can be difficult and is often delayed. The radiologist plays a key role in confirming the diagnosis. The classification system proposed by Fielding in 1977 is most frequently used and will be discussed in detail. Given that this classification system was devised in the days before computed tomography (CT), as well as the fact that combined atlanto-axial and atlanto-occipital rotatory subluxation (AORF) is omitted from the classification, we propose a modification to the classification of this rare but significant disorder. The radiological findings in six cases of AARF will be illustrated, including a case with associated atlanto-occipital subluxation. The pertinent literature is reviewed and a more comprehensive classification system proposed. The imaging approach to diagnosis and the orthopaedic approach to management will be discussed.

Percutaneous Ethibloc injection in aneurysmal bone cysts.

OBJECTIVE: To investigate whether the injection of Ethibloc into aneurysmal bone cysts can be an effective treatment modality. DESIGN AND PATIENTS: Ethibloc is an alcoholic solution of zein (corn protein) which has thrombogenic and fibrogenic properties. Ten patients with aneurysmal bone cysts were treated with CT-guided percutaneous injection of Ethibloc into the cyst cavity. Ethibloc injection was the primary treatment in five patients. Four patients had recurrence following previous curettage and bone grafting and one patient had not responded to injection into the lesion of autologous iliac crest bone marrow aspirate. Three patients needed a second injection. The median follow-up was 27 (6-60) months. RESULTS AND CONCLUSION: Symptoms were relieved in all patients. At imaging, seven patients had resolution of the lesion and three had partial response at the most recent follow-up. Complications consisted of a local transitory inflammatory reaction in two patients and an aseptic abscess in one patient. This relatively simple, minimally invasive procedure makes an operation unnecessary by stopping the expansion of the cyst and inducing endosteal new bone formation. This technique may be used as the primary management of aneurysmal bone cysts excluding spinal lesions.

Comparison of gait patterns between healthy and scoliotic patients using time and frequency domain analysis of ground reaction forces.

STUDY DESIGN: The walking gait in 20 healthy adolescent girls and 20 adolescent girls with idiopathic scoliosis was compared using time and frequency domain analysis of the ground reaction forces. OBJECTIVES: To investigate the support phase mechanics of walking gait in health subjects and those with scoliosis. SUMMARY OF BACKGROUND DATA: Previous studies have demonstrated the important role of gait in the etiology of scoliosis, although, to date, there are no detailed reports that examine kinetic gait parameters. METHODS: Selected force-time parameters were used to investigate time domain patterns. The frequency content of the vertical, anterior-posterior, and medial-lateral components was used to examine frequency characteristics. Inter- and intrasubject variability and bilateral symmetry also were examined. RESULTS: The findings indicated no significant difference between the two groups for the time domain variables. However, the frequency content of the group with scoliosis was significantly higher han that of the control group, especially in the medial lateral component, suggesting presence of a balance control misfunction. In addition, substantially higher inter- and intrasubject variability and asymmetry was found within the frequency content of the group with scoliosis compared with the control group in the medial-lateral and anterior-posterior directions. CONCLUSIONS: Patients with scoliosis exhibit balance problems during the stance phase of gait and have significant asymmetry in the frequency characteristics. These findings could be a primary effect that contributes to the medial-lateral deformity of the spine and its initiation and progression.

The relationship between surface and radiological deformity in adolescent idiopathic scoliosis: effect of change in body position.

Three-dimensional (3D) surface deformity of the trunk in adolescent idiopathic scoliosis (AIS) is affected by changes in patient position. Initial quantification of the curve and its associated deformity, as well as subsequent monitoring, relies on both radiological and surface measurements. However, there is often a discrepancy between radiological and apparent surface deformity. The present investigation studied the dynamics of the 3D deformity associated with changes in patient position on 27 patients with AIS. The trunk deformity was quantified in three positions by measuring the angle of thoracic inclination at each vertebral level using a scoliometer. The patients all had full spine radiography in the antero-posterior erect position. Vertebral rotation and lateral spinal curvature were measured from the radiographs. Body position altered the magnitude of the surface deformity over the whole trunk, with the prone position offering the optimum relationship between 3D trunk shape and radiological deformity. This could be attributed to the ease and standardisation of positioning for prone measurements, together with increased patient comfort. It is suggested that adoption of standardised positioning and measurement of surface and radiological deformity will permit consistency of clinical judgement based on these parameters.

Eighteen-level analysis of vertebral rotation following Harrington-Luque instrumentation in idiopathic scoliosis.

We used the Perdriolle method to measure the rotation of each vertebra from the seventh cervical to the fifth lumbar level, before and after posterior spinal arthrodesis and Harrington-Luque instrumentation in fifteen patients who had idiopathic scoliosis. The primary curve was corrected an average of 50 per cent and the secondary curve, an average of 73 per cent. Following the operation, the average number of vertebrae involved in the primary curve increased from seven (range, five to ten) to nine (range, seven to fifteen). The rotation of the apical vertebra of the primary curve increased 10 degrees in four patients and 5 degrees in two patients and decreased 5 degrees in one patient. The rotation of the apical vertebra of the secondary curve increased 10 degrees in three patients and 5 degrees in one patient and decreased 5 degrees in four patients. In seven patients, correction of the curve was associated with unexpected counter-rotation, beyond the levels of instrumentation, of three or more vertebral segments that had been in neutral position before the operation.

Correlation between bone age and Risser's sign in adolescent idiopathic scoliosis.

Skeletal maturity in 86 girls with adolescent idiopathic scoliosis was determined by assessing their bone age at the hand and wrist and by the development of their iliac (Risser's sign) and ischial apophyses. The two methods were compared and a statistically significant correlation was noted, signifying that the development of the iliac and ischial apophyses is a sensitive parameter for assessing skeletal maturity in these patients. The iliac apophysis is visible on routine follow-up radiographs of these patients, so using this criterion results in a reduction of roentgen ray exposure to the patient and significant financial savings. A more sensitive method of assessing the development of the iliac and ischial apophyses is suggested.

Measurement of body surface topography using an automated imaging system.

An automatic computer imaging system for recording body surface topography has been developed on a microcomputer-based image processing system. The computer processes fringe patterns generated on the surface of the trunk and reconstructs the complete 3-dimensional form of the surface. From the topographic reconstruction, clinical parameters of scoliotic deformity such as Angle of Trunk Inclination are calculated at a number of levels from the upper thoracic to the sacral region. These multiple level measurements illustrate the change in deformity over the trunk and correspond to measurements obtained using conventional tactile devices on patients.

Maintenance of cell viability in stored bone.

Although stored autogenous bone is routinely used for bone grafting in spinal surgery, the cellular elements of this bone do not survive the period of storage under standard conditions. By the use of tissue culture techniques, the authors show that it is possible to keep bone cells alive for many weeks. The potential advantages of maintaining cellular viability in grafted bone is discussed.

Contralateral percutaneous adductor tenotomy. An aid to peroperative fluoroscopy in hip fracture fixation.

In 6 elderly patients with femoral neck fractures, contralateral hip disease made lateral fluoroscopy difficult. Percutaneous adductor tenotomy of the contralateral hip facilitated screening of guide-wire placement during the fixation of the fracture.

Scoliosis surgery in the Prader-Willi syndrome.

There is a high incidence of spinal deformity in children with the Prader-Willi syndrome. We have encountered major complications following spinal surgery in this condition. We report our experience and conclude that spinal surgery is a formidable undertaking and the risks should be appreciated by the surgeon and the parents.

Etiology of Freiberg's disease: ? trauma.

Freiberg's disease is osteochondritis of the metatarsal head(s) commonly occurring in adolescent girls. The true etiology is unknown. The authors present a case precipitated by a form of folk dancing popular among British schoolgirls.

Osteoid osteoma of a rib as a cause of scoliosis. A case report.

A case of osteoid osteoma of a rib causing painful scoliosis is reported. The importance of full investigation in such a case is highlighted.

Intra-operative awakening to monitor spinal cord function during scoliosis surgery. Description of the technique and report of four cases.

We used a modification of the wake-up test to monitor spinal cord function in 102 consecutive scoliotic patients undergoing Harrington instrumentation. Four patients were found to have a neural deficit when they were awakened during the operation. Three recovered immediately after partial release of the distracting force; one required immediate removal of the rod and was left with a slight neural deficit. Using our method, we have encountered no problem in performing the wake-up test, although attention is drawn to the difficulty in repeating the test if the patient is re-anaesthetised with diazepam. There were no false negative results in this series.

A prospective study of deep vein thrombosis of the leg in children on halo-femoral traction.

This prospective study was performed to determine the true incidence of deep vein thrombosis of the lower limb in children who had undergone halo-femoral traction to correct scoliosis before operation. Bilateral ascending phlebography of the lower limbs was performed on 54 children two days before spinal fusion and Harrington rod instrumentation. Two patients developed clinical evidence of thrombosis whilst on traction. This diagnosis was confirmed by phlebography. The other 52 children had no clinical evidence of thrombosis and their venograms were normal. The incidence of thrombosis was 3.7 per cent and clinically silent thrombosis did not occur.