Biomechanical comparison of two different concepts for stand alone anterior lumbar interbody fusion.

Segmental instability in degenerative disc disease is often treated with anterior lumbar interbody fusion (ALIF). Current techniques require an additional posterior approach to achieve sufficient stability. The test device is an implant which consists of a PEEK-body and an integrated anterior titanium plate hosting four diverging locking screws. The test device avoids posterior fixation by enhancing stability via the locking screws. The test device was compared to an already established stand alone interbody implant in a human cadaveric three-dimensional stiffness test. In the biomechanical test, the L4/5 motion segment of 16 human cadaveric lumbar spines were isolated and divided into two test groups. Tests were performed in flexion, extension, right and left lateral bending, right and left axial rotation. Each specimen was tested in native state first, then a discectomy was performed and either of the test implants was applied. Finite element analysis (FE) was also performed to investigate load and stress distribution within the implant in several loading conditions. The FE models simulated two load cases. These were flexion and extension with a moment of 5 Nm. The biomechanical testing revealed a greater stiffness in lateral bending for the SynFix-LR compared to the established implant. Both implants showed a significantly higher stiffness in all loading directions compared to the native segment. In flexion loading, the PEEK component takes on most of the load, whereas the majority of the extension load is put on the screws and the screw-plate junction. Clinical investigation of the test device seems reasonable based on the good results reported here.

Laminated multi-segment rib graft in anterior column reconstruction.

Rib harvested during thoracotomy can be effectively used for anterior column reconstruction. An innovative technique is described to convert multiple individual rib segments into a robust single anterior column reconstruction graft using cortical screws.

Long-term mortality and morbidity of transfusion-associated non-A, non-B, and type C hepatitis: A National Heart, Lung, and Blood Institute collaborative study.

Persons with non-A, non-B hepatitis (cases) identified in 5 transfusion studies in the early 1970s have been followed ever since and compared for outcome with matched, transfused, non-hepatitis controls from the same studies. Previously, we reported no difference in all-cause mortality but slightly increased liver-related mortality between these cohorts after 18 years follow-up. We now present mortality and morbidity data after approximately 25 years of follow-up, restricted to the 3 studies with archived original sera. All-cause mortality was 67% among 222 hepatitis C-related cases and 65% among 377 controls (P = NS). Liver-related mortality was 4.1% and 1.3%, respectively (P =.05). Of 129 living persons with previously diagnosed transfusion-associated hepatitis (TAH), 90 (70%) had proven TAH-C, and 39 (30%), non-A-G hepatitis. Follow-up of the 90 TAH-C cases revealed viremia with chronic hepatitis in 38%, viremia without chronic hepatitis in 39%, anti-HCV without viremia in 17%, and no residual HCV markers in 7%. Thirty-five percent of 20 TAH-C patients biopsied for biochemically defined chronic hepatitis displayed cirrhosis, representing 17% of all those originally HCV-infected. Clinically evident liver disease was observed in 86% with cirrhosis but in only 23% with chronic hepatitis alone. Thirty percent of non-A, non-B hepatitis cases were unrelated to hepatitis viruses A,B,C, and G, suggesting another unidentified agent. In conclusion, all-cause mortality approximately 25 years after acute TAH-C is high but is no different between cases and controls. Liver-related mortality attributable to chronic hepatitis C, though low (<3%), is significantly higher among the cases. Among living patients originally HCV-infected, 23% have spontaneously lost HCV RNA.

Delayed focal neurological deficit secondary to a cervico-thoracic spinal cord epidural haematoma.

This is a report of an elderly woman who developed focal neurological deficit in association with a cervico-thoracic spinal epidural haematoma. Symptoms developed several days after the initial injury and subsequently resolved without surgical intervention. The unusual features of this presentation are discussed.

Short segment fixation of thoracolumbar burst fractures without fusion.

There continues to be controversy surrounding the management of thoracolumbar burst fractures. Numerous methods of fixation have been described for this injury, but to our knowledge, spinal fusion has always been part of the stabilising procedure, whether this involves an anterior or a posterior approach. Apart from an earlier publication from this centre, there have been no reports on the use of internal fixation without fusion for this type of fracture. The aim of the study was to determine the outcome of patients with thoracolumbar burst fractures who were treated with short segment pedicle screw fixation without fusion. This is a retrospective review of 28 consecutive patients who had short segment pedicle screw fixation of thoracolumbar burst fractures without fusion performed between 1990 and 1993. All patients underwent a clinical and radiological assessment by an independent observer. Outcome was measured using the Low Back Outcome Score. The minimum follow-up period was 2 years (mean 3.1 years). Fifty percent of patients achieved an excellent result with the Low Back Outcome Score, while 12% were assessed as good, 20% fair and 16% obtained a poor result. The only significant factor affecting outcome was the influence of a compensation claim (P < 0.05). The implant failure rate (14% of patients) and the clinical outcome was similar to that from series where fusion had been performed in addition to pedicle screw fixation. The results of this study support the view that posterolateral bone grafting is not necessary when managing patients with thoracolumbar burst fractures by short segment pedicle screw fixation.

Assessment of spinal cord blood flow and function in sheep after anterolateral cervical interbody fusion in the presence of cord damage.

The safety of an anterolateral cervical fusion, which facilitates stabilization without sacrifice of the anterior longitudinal ligament, recently has been brought into question. The purpose of this study was to assess the effect of an anterolateral cervical fusion on spinal cord blood flow and motor and sensory-evoked potentials in the presence of an incomplete spinal cord injury. In 12 sheep, a spinal cord injury was produced by the rapid inflation of an extradural balloon catheter; six of the animals had a cervical fusion. There was no significant difference in spinal cord blood flow or evoked potential responses obtained from the sheep that had an anterolateral cervical fusion, compared with the sheep that did not. Based on these results, it seems unlikely that this surgery has an adverse effect on recovery from spinal cord injury in the absence of operative mishap.

Pseudo-abscess of the psoas bursa in failed double-cup arthroplasty of the hip.

Seven psoas bursae filled with purulent fluid and inspissated debris were revealed at revision operations for failed resurfacing hip arthroplasties, an incidence of 5.8% in such revisions. Histological and microbiological investigations demonstrated that the psoas bursa collections resulted from the tissue response to polyethylene wear debris. None was due to infection.

Road crash cervical injuries. A radiological study of fatalities.

A lateral radiograph of the cervical spine was obtained for 174 of the 207 persons killed in road crashes in Adelaide, South Australia, during the 12-month period of June 1, 1987 to May 31, 1988. Of the total of 57 cases of cervical injury, routine postmortem examination identified 30 cases (52.6%), and the radiographic examinations identified 51 cases (89.5%). In the cases where it was performed, radiography identified 96.2% of injuries. One-half of injuries of level C3 and above were not reported at postmortem examination, compared with 22% of those occurring below this level. This finding correlates with the physical difficulties of examining the upper part of the cervical spine. This study has shown that lateral cervical radiography is a simple and effective method of more accurately identifying significant cervical spinal injuries, thus improving greatly the value of postmortem examinations in determining the patterns and mechanisms of these injuries.

Cervical spine injuries in road traffic crashes in South Australia, 1981-86.

The records of all cases of injury to the cervical spine sustained in road crashes for the 6 year period (1 January 1981 to 31 December 1986) which were admitted to the Spinal Injuries Unit of the Royal Adelaide Hospital, to the Adelaide Children's Hospital, or were identified at post-mortem examination were examined, and the relevant data extracted. There were 291 cases in the non-fatal group, and 161 in the fatal group. These represent a complete enumeration of all such patients in the state of South Australia over the 6 year period, given that up to 50% of cervical injuries in fatal cases can be missed. Comparison of the two groups showed that the fatal group had a much higher proportion of pedestrians, and persons over 50 years of age. About one-half of the fatal group had injuries at the level of C1 or the atlanto-occipital articulation. The most frequent level of injury in the non-fatal group was C2 (29.2%). About 30% of the non-fatal cases had some spinal cord damage. Case fatality rates were calculated, and ranged from 100% for injury at the atlanto-occipital articulation to 8% at C2. The fatality rate of pedestrians was about 4 times higher than that of vehicle occupants. About three-quarters of all cervical spine injuries occurred in vehicle occupants. There was an increase in the number of cases occurring in each year of the period studied. This rise was noted in non-fatal cases, in males, in vehicle occupants, and in crashes in the country.