Purpose: Postoperative dislocation after revision total hip arthroplasty (rTHA) is a frequent complication. Certain risk factors have been well identified (greater trochanter non-union, history of repeated dislocation or infection, multiple operations), but the role of spinal morphology is not well known. The purpose of this prospective study was to determine the role of spinal morphology on postoperative dislocation.

Material and methods: Between September 2000 and March 2002, 49 patients underwent rTHA. The prospective analysis included a preoperative radiographic evaluation of the spinal morphology for lumbopelvic assessment using the Legave and Duval Beaupère criteria. A standard information card was used pre- intra- and postoperatively to record usual patient- and material-related risk factors of dislocation. Five patients experienced postoperative dislocation despite any apparent defect in implant position.

Results: Mean sacral slope was significantly different (p=0.006) between patients with and without dislocation. This difference remained significant (p=0.017) when limiting the study to the 33 patients who had no associated risk factor postoperatively (history of recurrent dislocation or infection, multiple operations, tight non-union of the greater trochanter).

Discussion: Our study demonstrated the role of lumbar morphology on the risk of postoperative dislocation. Spinal morphology modifies the pelvic orientation and thus landmarks habitually used for implantation. It also affects the amplitude of pelvic movement when moving from the sitting to standing position, requiring hip compensation, particularly extension.

Purpose: Several techniques have been proposed for C1-C2 fusion. The anterior transoral technique is the most direct approach but at the cost of major risk of infection. The posterior approach allows wiring (Gallie technique) or direct atloidoaxoid screw fixation (Magerl technique). The retrosternomastoid bilateral approach (Du Toit technique) allows direct screwing in the lateral masses. The rate of nonunion reported in the literature is high for wiring techniques. Biomechanical studies have demonstrated the mechanical superiority of trans-articular screwing which has been confirmed in clinical series. The purpose of the present study was to describe a modification of the Du Toit technique and describe results in a short series.

Material and methods: This modification of the Du Toit technique consists in an abrasion of the C1 lateral mass at its origin enabling the penetration of a Cloward curette to create a stable introduction point for the drill bit and thus avoid slippage forward as can occur with the conventional technique. The screw is directed towards C2, in a strict frontal plane. The obliquity depends on the room allowed by the mastoid. The drill bit should cross both corticals of the inferior facet of C1 and the superior facet of C2. The screws must cross in a coronal plane just under the odontoid. Fusion of the C1-C2 lateral masses is achieved by abrasion and grafting.

We have used the modified Du Toit technique for C1-C2 arthodesis in four patients with rheumatoid arthritis, fracture of the odontoid, an odontoid bone, and isolated degeneration. The procedure was a first intention treatment for the patient with primary degeneration, and a second intention procedure for the others who had developed nonunion after wiring.

Results: Mean hospitalisation was six day. Operative time was 2 h 10 min. Mean blood loss was 200 ml peroperatively and 120 ml postoperatively. None of the patients had developed nonunion or mechanical failure at a mean follow-up of 2.7 years (range 1 – 5 years). Operative complications included one case of venous bleeding which was treated with vascular clips and two cases were the lateral mass of C1 was weakened requiring cementing. There was one early postoperative neurological complication with hypoaesthesia of the hemitongue that regressed spontaneously. None of these complications produced sequelae.

Conclusion: The advantages of the modified technique for lateral screw fixation of C1-C2 is the improvement in the entry point for the drill bit allowing an optimal screw position and a stable drilling to achieve good mechanical fixation and certain union.

Purpose: We analysed retrospectively 32 cases of posterior cervicothoracic fixation for spinal tumours. We evaluated spinal stability, spinal alignment, and associated complications.

Material and methods: Thirty-two patients underwent surgery: 27 men and five women, mean age 52 years, age range 17–72 years. We implanted 96 articular screws in C4 to C6, 54 screws in C7 and 180 pedicular screws in T1 to T8. Nineteen patients had primary lung cancer with spinal invasion, eleven had spinal metastases, one had a chondrosarcoma and one had a myeloma. For the first group of 19 patients, en bloc resection of the tumour with the vertebra was performed: four total vertebrectomies, 15 partial vertebrectomies. In a second group of 15 patients, palliative posterior fixation was performed with laminectomy decompression.

Results: Follow-up ranged from three to 54 months with a mean of 15 months. Mean survival after total or partial vertebrectomy was 16 months (range 3 – 54 months). Survival after palliative decompression was eleven months with a range from five to 19 months. There were no changes in the sagittal alignment in 30 patients: two patients developed mechanical complications late after surgery requiring revision. We did not have any case of screw, plate or rod fracture. There were no neurological complications related to screw insertion either at the thoracic level (180 screws) or the cervical level (96 screws in C4C5C6 and 54 screws in C7). A control scan was available for 21 patients and revealed a malposition of the implanted screws for 2.5% of the screws with no clinical impact.

Discussion: Posterior screw fixation is a good method to stabilise the cervicothoracic spine during tumour surgery. Articular cervical screws and transpedicular thoracic screws provide effective stability postoperatively. In addition, this type of instrumentation does not interfere should subsequent laminectomy or wider resection be necessary.