C2 pedicle screw and plate combined with C1 titanium cable fixation for the treatment of atlantoaxial instability not suitable for placement of C1 screw.

STUDY DESIGN: A method of atlantoaxial stabilization using individual fixation of the C1 posterior arch and the C2 pedicle with C2 pedicle screws and plates combined with C1 titanium cables is described. In addition, the clinical results of this method on 8 patients are described. OBJECTIVE: To describe the method and the clinical and radiographic results for posterior C1-C2 fixation with a combined implant system. SUMMARY OF BACKGROUND DATA: Stabilization of the atlantoaxial complex is a challenging procedure because of the unique anatomy of this region. Fixation by plate or rod and C1 and C2 screw and structural bone grafting leads to excellent fusion rates. The technique is technically demanding and has a potential risk of the injuries to the vertebral artery, the internal carotid artery, spinal cord, and hypoglossal nerves. In addition, how to stabilize the atlantoaxial complex in the cases not suitable for placement of C1 screw is not described in the literature. To address these limitations, a method of C1-C2 fixation has been developed: bilateral insertion of C2 pedicle screws and rolling of C1 titanium cable through the posterior arch of atlas and the cranial hole of the plate, followed by C1-C2 plate fixation. METHODS: From February 2003 to March 2006, 8 patients with atlantoaxial instability and not suitable for placement of C1 screw were included in this study: 5 cases of broken C1 pedicle screw trajectory and 3 cases of C1 anatomic anomalies. Skull traction was performed in each patient preoperatively. The pedicle screws were inserted into C2 pedicles in the direction as its axis. C1 titanium cable was rolled superior to lower through posterior arch of atlas in the cases not suitable for placement of C1 screw. The C1-C2 plate was slightly bent to fit the upper cervical contour. Hyperflexion alignment of the atlantoaxial complex was corrected by application of extension force created by tightening of the nut on the pedicle screws and the C1 titanium cable, which was passed through the cranial hole of the plate. Morselized autogenous cancellous iliac grafts were placed on the surface of the posterior arches of both atlas and axis. All patients were assessed clinically for neurologic recovery by Odom's method. RESULTS: There were 5 males and 3 females with a mean age of 37.8 years (range, 17 to 59 y). There were 2 cases of old odontoid fracture, 2 cases fresh odontoid fracture (Aderson II C), 2 cases atlas transverse ligament laxation, 2 cases atlas transverse ligament rupture, and in these cases, 5 cases had failed placement of C1 screw because of broken C1 pedicle screw trajectory and 3 cases not suitable for placement of C1 screw because of anatomic anomalies. There were no spinal cord and vertebral artery and nerve injury after surgery. Follow-up duration was from 18 to 55 months with the average of 29 months. The plant bones all fused and there were no internal fixation rupture and mobility. All the patients showed improvement. CONCLUSIONS: C2 pedicle screw and plate combined with C1 titanium cable could be used to treat atlantoaxial instability in the cases not suitable for placement of C1 screw.

[Precision-fit surface hemiarthroplasty of the hip for the treatment of the femoral head osteonecrosis].

OBJECTIVE: To evaluate the outcome of precision-fit surface hemiarthroplasty in the treatment of femoral head osteonecrosis. METHODS: The clinical data of 41 patients (48 hip joints) with femoral head osteonecrosis were reviewed. Of them, 30 were male and 11 were female, average age was 37 years old (ranging from 29 - 49). Thirty-five patients were at Ficat stage III and 13 at Ficat stage IV, their acetabula were relatively normal. The 41 patients (48 hip joints) underwent precision-fit surface hemiarthroplasties. RESULTS: The mean duration of follow-up was 5.2 years. The average UCLA hip score at follow-up was improved significantly from 3.1 to 9.1 points for pain, 4.4 to 9.2 points for walking, and 5.5 to 7.1 points for activity (P = 0.001). The satisfaction rate was 88.6% for 35 at Ficat stage III, 69.2% for 13 at stage IV (P = 0.25). Eight hips failed; the UCLA hip score was not improved significantly; the postoperative X-ray examination showed that 7 femoral prostheses were implanted in a varus orientation (the angle between the femoral prosthesis stem and the anatomic axis of the femoral shaft was lower than angle of 130 degrees). Five-year survival rate was 83.0%. CONCLUSIONS: Precision-fit surface hemiarthroplasty of the hip has the satisfactory result in treatment of the femoral head osteonecrosis on the basis of observing strictly operative indications and improving operative technique.