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Biomedical subjects

C Olerud

Publications and source records attributed to C Olerud.

At least 19 recordsLinked to original sources
PubMed2004

Posterior fixation of subaxial cervical spine fractures in patients with ankylosing spondylitis.

Cervical spine fractures in patients with ankylosing spondylitis are serious and potentially lethal injuries with high complication rates. Treatment obstacles include long lever arms that generate large forces on any fixation device, osteoporosis, and, usually, kyphotic deformity. The Olerud Cervical Fixation System (OC), with cervical pedicle screws and rods, offers an opportunity to create a biomechanically stable posterior fixation in these complicated cases. The present study is a retrospective chart review and a radiological follow-up of patients with this diagnosis, treated at our department between 1995 and 2000. Nineteen patients (two women) with a mean age of 60 years (32-78 years) were included. The fracture levels were predominantly C5-C6 (five patients) and C6-C7 (five patients). All patients were treated with a long posterior fixation with the OC, and in four patients this was combined with an anterior plate fixation. One patient with severe lordosis also received a short posterior plate fixation. The patients' notes and plain radiographs have been reviewed. Five patients died during the post-operative follow-up period; the others had a mean follow-up time of 24 months (10-55 months). Eleven patients had no neurological deficits preoperatively. One of them developed moderate weakness in his right arm, postoperatively, due to a misplaced pedicle screw in the right pedicle of C5. However, after extraction of the screw he almost totally recovered in 6 months. Eight patients had neurological deficits. Two were paraplegic; two had motor weakness combined with sensory deficiency, and four had a sensory deficiency. Two of the patients with neurological deficits improved postoperatively, but the others were unchanged. Peroperative problems were recorded in five patients; one C6 pedicle was perforated, and two patients had pedicles on one or more levels that the surgeon was not able to probe. In one of the latter patients, transfacet screws were chosen, instead, for one of the levels. Extensive peroperative bleeding was encountered in two patients. One deep-wound infection was noted, postoperatively, and required surgical drainage, but no patients have been re-operated due to loosening of the instrument or to healing problems. In conclusion, the results of the present study indicate that the OC--and possibly other similar long-fixation systems that allow using both pedicle screws and lateral mass screws rigidly connected to a rod--is suited for treating subaxial cervical spine fractures in patients with ankylosing spondylitis, allowing high healing rates.

Adult↗
PubMed2004

The significance of radiolucent zones surrounding pedicle screws. Definition of screw loosening in spinal instrumentation.

We examined the radiographs from a prospective clinical study of fixation by pedicle screws and those from an experimental study in a sheep model. In the clinical study, instruments were removed from 21 patients after implantation for 11 to 16 months and the extraction torques of the screws were recorded. A structured protocol was used for the radiological examinations. In the experimental study, loaded pedicle screw instrumentations were implanted in the sheep for six or 12 weeks. After radiological examination the pull-out resistance and the histological characteristics were studied. In the clinical study, all screws with radiolucent zones had a significantly reduced mean extraction torque compared with screws without radiolucent zones (16 +/- 10 Ncm v 403 +/- 220 Ncm; p < 0.0001). In the experimental study the mean maximum pull-out resistance for the screws with radiolucent zones was significantly lower than for those with no radiolucency (243 +/- 156 N v2214 +/- 578 N; p = 0.0006) and the mean bone-to-screw contact was reduced for screws with zones compared with those without zones (8 +/- 9% v 55 +/- 29%; p = 0.0002). Our findings showed that all screws with radiolucent zones had low extraction torques or low pull-out resistance. A radiolucent zone is a good indicator of loosening of a pedicle screw.

Animals↗
PubMed2002

Posterior atlanto-axial fusion with the Olerud Cervical Fixation System for odontoid fractures and C1-C2 instability in rheumatoid arthritis.

In posterior C1-C2 fusion, traditional wire fixation gives poor stability. The bone quality is often insufficient to provide the competent structural bone graft that is required, and the introduction of sublaminar wires is somewhat dangerous. The stability is markedly improved by adding transarticular screws, but the drawbacks of structural bone graft and sublaminar wires remain. The C1 claw of the Olerud Cervical Fixation System improves C1-C2 fixation without relying on structural bone graft or compromising the spinal canal. The aim of this study was to evaluate radiological healing and possible complications in a consecutive series of C1-C2 fusions from our department operated with the C1 claw device. Twenty-six patients (14 women) with a mean age of 73 (range 37-93) years were included. The diagnoses were odontoid fracture in 18 patients, rheumatoid instability in 6, and odontoid non-union and os odontoideum in 1 each. The patients were followed clinically and with plain radiographs for an average of 15 (range 3-27) months. There were no neurological or vascular complications, and no secondary displacements or reoperations in the series. Twenty patients followed for 6-27 months were radiographically healed. Six patients died from unrelated causes 1-38 months postoperatively. Three of these patients had no radiographs later than the postoperative control, one had a healed odontoid fracture but resorbed bone graft at 8 months, while the remaining two patients were not healed, but showed no signs of healing disturbance at the time of death. On the basis of the findings of this study, posterior C1-C2 fusion with the Olerud Cervical Fixation System seems promising. No serious complications related to the surgical procedure were encountered. The stability of the implant obviates the use of a solid bone block as a graft and still allows a high frequency of fusion healing.

Adult↗
PubMed2002

Hydroxyapatite coating improves fixation of pedicle screws. A clinical study.

We investigated the effects of hydroxyapatite (HA) coating on the purchase of pedicle screws. A total of 23 consecutive patients undergoing lumbar fusion was randomly assigned to one of three treatment groups. The first received uncoated stainless-steel screws, the second screws which were partly coated with HA, and the third screws which were fully coated. The insertion torque was recorded. After 11 to 16 months, 21 screws had been extracted. The extraction torque was recorded. Radiographs were taken to assess fusion and to detect loosening of the screws. At removal, the extraction torques exceeded the upper limit of the torque wrench (600 Ncm) for many HA-coated screws. The calculated mean extraction torque was 29 +/- 36 Ncm for the uncoated group, 447 +/- 114 Ncm for the partly-coated group and 574 +/- 52 Ncm for the fully-coated group. There were significant differences between all three groups (p < 0.001). There were more radiolucent zones surrounding the uncoated screws than the HA-coated screws (p < 0.001). HA coating of pedicle screws resulted in improved fixation with reduced risk of loosening of the screws.

Adult↗
PubMed2001

Improved bone-screw interface with hydroxyapatite coating: an in vivo study of loaded pedicle screws in sheep.

STUDY DESIGN: An in vivo sheep model with loaded pedicle screws was used, wherein each animal served as its own control. OBJECTIVES: To examine the effects of hydroxyapatite (HA) coating on the bone-to-implant interface in loaded spinal instrumentations. SUMMARY OF BACKGROUND DATA: Spinal instrumentation improves the healing rate in spinal fusion, but screw loosening constitutes a problem. HA coating of other implants has resulted in favorable effects on the bone-to-implant interface. METHODS: Nine sheep were operated on with destabilizing laminectomies at two levels: L2-L3 and L4-L5. Each level was stabilized separately with a four-screw instrumentation. Uncoated screws (stainless steel) or the same type of screws coated with plasma-sprayed HA were used in either the upper or the lower instrumentation in a randomized fashion. The animals were killed at 6 or 12 weeks after surgery. The specimens were embedded in resin, ground to approximately 10 microm, and stained with toluidine blue. Histomorphometric evaluation was carried out in a Leitz Aristoplan (Wetzlar, Germany) light microscope equipped with a Leitz Microvid unit. RESULTS: The average percentage of bone-to-implant contact after 6 weeks was 69 +/- 10 for the HA-coated screws and 18 +/- 11 for the uncoated screws (P < 0.03), and after 12 weeks 64 +/- 31 (HA-coated) and 9 +/- 13 (uncoated, P < 0.02). The average bone volume in the area close to the screw was significantly higher for the HA-coated screws at both 6 and 12 weeks. CONCLUSIONS: HA coating improved the bone-to-implant interface significantly, indicating that HA coating can become useful for improving the purchase of pedicle screws.

Animals↗
PubMed2001

Cauda equina syndrome as a postoperative complication in five patients operated for lumbar disc herniation.

STUDY DESIGN: A retrospective analysis of records and radiographs in five patients who developed acute cauda equina syndrome after surgery for lumbar disc herniation. OBJECTIVES: To postulate as a possible pathophysiologic mechanism the venous congestion caused by preexisting spinal stenosis and to present a management plan: extended decompression within 48 hours. SUMMARY OF BACKGROUND DATA: Cauda equina syndrome is reported as a sequela in 0.2%-1% of the surgeries for lumbar disc herniation. There is, however, no consensus on the possible pathophysiologic mechanism to the complication or to its management. METHODS: Preoperative investigations consisted of magnetic resonance imaging, or myelography and computed tomography. There was a good correlation between clinical appearance and radiographic findings in all patients. When the complication became apparent in four of the patients, they were investigated with magnetic resonance imaging and reoperated on within 48 hours with wide decompressions. RESULTS: The index operation was reported uneventful in all patients. Postoperative magnetic resonance imaging did not show the cause of the cauda equina syndrome, nor could this be established at the reoperation. Before surgery, all five patients had preexisting narrowing of the spinal canal. In no case was the lumbosacral disc the index level. Two patients recovered fully, whereas the other three experienced varying degrees of residual symptoms. There was no correlation between the end result and the delay until secondary decompression. CONCLUSION: Relative spinal stenosis may contribute to the development of cauda equina syndrome after surgery for lumbar disc herniation. A venous congestion can be triggered by postoperative edema, leading to nerve root ischemia. The treatment of choice seems to be extended decompression within 48 hours.

Adult↗
PubMed2001

The C1 claw device: a new instrument for C1-C2 fusion.

A new fixation device for C1-C2 fusion is presented. It consists of a claw construct for the C1 arch that is rigidly attached to C1-C2 transarticular screws to form an instrument that combines anterior and posterior fixation in the same construct. The new device was successfully applied in a case with failed C1-C2 fusion that was initially stabilized with transarticular screws alone, where the usual posterior wiring was omitted due to a defect of the posterior C1 arch.

Cervical Vertebrae↗
PubMed2001

Hydroxyapatite coating enhances fixation of loaded pedicle screws: a mechanical in vivo study in sheep.

Loosening of the pedicle screws with subsequent non-union or loss of correction is a frequent problem in spinal instrumentation. In a clinical pilot study, coating of pedicle screws with plasma-sprayed hydroxyapatite (HA) resulted in a significant increase of removal torque. An experimental study was performed to investigate the effects of HA coating on the pull-out resistance. Thirteen sheep were operated on with destabilising laminectomies at two levels, L2-L3 and L4-L5. Two instrumentations with four pedicle screws in each were used for stabilisation. Uncoated screws (stainless steel) or the same type of screws coated with plasma-sprayed HA were used in either the upper or the lower instrumentation in a randomised fashion. Four sheep were examined immediately after the application of the screws, three sheep at 6 weeks and four sheep at 12 weeks. Two sheep were euthanised early due to complications. The pull-out resistance was recorded in two HA-coated and two standard screws in each animal. The maximum pull-out resistance was higher for the HA-coated screws at 0 weeks (P< 0.02) and at 12 weeks (P<0.01) when compared to the uncoated screws, while there was no significant difference between the groups at 6 weeks. We believe that the higher pull-out resistance for HA-coated screws at 0 weeks was mainly caused by differences in surface roughness, while the difference at 12 weeks was due to a favourable bone reaction around the HA-coated screws. At 12 weeks, the average stiffness was significantly higher for the HA-coated screws, while there was no significant differences in stiffness between the two screw types at 0 and 6 weeks. Energy to failure was significantly higher for coated screws when compared to the uncoated screws at all three time points. HA coating improves fixation of loaded pedicle screws, with increased pull-out resistance and reduced risk of loosening.

Animals↗
PubMed2000

Biomechanical comparison of five different atlantoaxial posterior fixation techniques.

STUDY DESIGN: Five different reconstructions of the atlantoaxial complex were biomechanically compared in vitro in a nondestructive test. OBJECTIVES: To determine whether non-bone graft-dependent one-point fixation affords stability levels equivalent to three-point reconstructions. SUMMARY OF BACKGROUND DATA: Previous investigations have demonstrated that three-point fixation, using bilateral transarticular screws in combination with posterior wiring, provide the most effective resistance to minimize motion around C1-C2. However, placement of transarticular screws is technically demanding. Posterior wiring techniques affording one-point fixation have failure rates of approximately 15%, with failure considered to be secondary to structural bone graft failures. One-point, non-bone graft-dependent fixations have not been tested. METHODS: Eight human cervical specimens, C0-C3 were loaded nondestructively. Unconstrained three-dimensional segmental motion was measured. The reconstructions tested were two one-point fixations, one two-point fixation, and two three-point fixations. RESULTS: Under axial rotation two and three-point reconstructions provided better stiffness than the one-point reconstructions (P < 0.05). During flexion-extension, higher stiffness levels were observed in one- and three-point fixations when compared with the intact spine (P < 0.05). In lateral bending no significant differences were observed among the six groups, although the trend was that reconstructions including transarticular screws provided greater stability than one-point fixations. CONCLUSION: The current findings substantiate the use of three-point fixation as the treatment of choice for C1-C2 instability. [l: atlantoaxial fixation, biomechanics, cervical spine, instability, spinal instrumentation, transarticular screws]

Aged↗
PubMed2000

Improved extraction torque of hydroxyapatite-coated pedicle screws.

Loosening of the screws is a problem in instrumentation with pedicle screws. Coating with hydroxyapatite improves the holding characteristics for metal implants, but the possible effects on the anchorage of pedicle screws have not been described. In this study, seven patients were operated on with spinal instrumentation using four stainless steel pedicle screws. Hydroxyapatite-coated screws were used in either the upper or the lower of the instrumented levels. The insertion torque was measured. In four cases the screws were removed after 10-22 months and the extraction torque was measured. The mean insertion torque was found to be significantly greater in the hydroxyapatite-coated screws (107 Ncm) than in the standard screws (76 Ncm). In three cases, the extraction torque for the hydroxyapatite-coated screws exceeded the range for the torque wrench (600 Ncm), while the conventional screws were loose (< 5 Ncm). In one case, the extraction torque was 475 and 550 Ncm for the coated screws, and 5 and 25 Ncm for the conventional screws. The difference in extraction torque was significant. Hydroxyapatite coating was shown to have improved the purchase of pedicle screws very effectively. By using fully coated screws, as in the present study, extraction was extremely difficult compared to extraction of conventional stainless steel screws, which were regularly loose. By reducing the area of the screws that is coated, it may be possible to achieve an enhanced purchase while extraction will be easier when compared to fully coated screws.

Adolescent↗
PubMed2000

Odontoid fractures: high complication rate associated with anterior screw fixation in the elderly.

This study is a retrospective analysis of patients older than 65 years with odontoid fractures. The series consisted of 29 consecutive patients with odontoid fractures (18 women, mean age 78, range 66-99 years). Twenty-six patients were neurologically intact, Frankel E, whereas three had neurological symptoms: two Frankel D and one Frankel C. Eleven patients were treated with anterior screw fixation according to Böhler, seven with a posterior C1-C2 fusion. Ten patients with either minimally displaced fractures or with complicating medical conditions were treated conservatively. At follow-up, 7/7 patients with posterior fusion had healed without any problems, whereas 8/11 patients treated with anterior screw fixation, and 7/10 conservatively treated patients were either failures or had healed, but after a complicated course of events. We conclude that anterior screw fixation according to Böhler is associated with an unacceptably high rate of problems in the elderly. Probable causes may be osteoporosis with comminution at the fracture site, or stiffness of the cervical spine preventing ideal positioning of the screws. As non-operative treatment also often fails, the method of choice seems to be posterior C1-C2 fusion.

Aged↗
PubMed2000

Acute whiplash-associated disorders (WAD): the effects of early mobilization and prognostic factors in long-term symptomatology.

OBJECTIVE: To compare two different home exercise programmes for patients with acute whiplash-associated disorders (WAD). A further aim was to describe the initial prognostic variables related to self-reported pain at six months follow-up. DESIGN: A randomized treatment study with a follow-up period of six months. SETTINGS: The study was undertaken in an orthopaedic clinic at a university hospital. SUBJECTS: A total of 59 symptomatic (neck pain, stiffness, etc.) patients with acute whiplash injury. INTERVENTIONS: Patients were randomized to a regular treatment group (RT group) and an additional-exercise treatment group (AT group). MAIN OUTCOME MEASURES: Pain Disability Index (PDI), Self-Efficacy Scale (SES), Coping Strategies Questionnaire (CSQ), neck range of motion (ROM), head posture, kinaesthetic sensibility, visual analogue scale (VAS). RESULTS: Patients given an additional exercise did not improve more than patients with regular treatment. Only one CSQ item, 'Ability to decrease pain', showed a significant difference between the groups in its pattern of change over time: the AT group had a significant increase between three and six months whilst values in the RT group decreased. Nonsymptomatic patients at six months follow-up were characterized by initially better self-efficacy, lower disability and significantly different patterns in the use of 'behavioural coping strategies' when compared with symptomatic patients. The nonsymptomatic patients also reported more frequent training than symptomatic patients, i.e. they complied better with the treatment regime. CONCLUSION: This home exercise programme, including training of neck and shoulder ROM, relaxation and general advice seems to be sufficient treatment for acute WAD patients when used on a daily basis. Additionally, patients reporting low self-efficacy and high disability levels may profit from more attention initially, as these psychological factors are significant predictors of pain at long-term follow-up.

Adult↗
PubMed1999

Evaluation of grip strength measurements after Colles' fracture: a methodological study.

Maximal isometric grip strength during short and sustained contractions was registered in 28 females and five males with displaced Colles' fracture involving the distal radio-ulnar joint. After reduction the patients were immobilized with plaster cast or with external fixation. The reliability of the measurements of the uninjured side was high and stable over a two-year follow-up period. The between-occasion reliability of the injured side was lower than that of the uninjured side. At each session the intensity of pain was measured. There was a reduction in pain after two years. The discriminatory ability of the measurements was satisfactory. It is suggested that the measurement methods and the present findings may serve as guidance in physiotherapy for these patients, especially if the uninjured side is used as reference.

Colles' Fracture↗
PubMed1999

The Olerud Cervical Fixation System; a study of safety and efficacy.

To evaluate safety and efficacy of the Olerud Cervical Fixation System a one-year follow up study was done by an independent observer. There were 30 patients (14 women) with a mean age of 68 (37-85) years. Indications were rheumatoid arthritis in 10, spinal stenosis in 6, trauma in 6, metastases in 4, revisions in 3, and painful spondylotic deformity in one patient. Short fusions were performed in 8 patients and long fusions in 22. Four patients were fused to occiput. C1-C2 fusion was performed in 3 patients. Nineteen of the 20 still alive were evaluated at follow up. One patient was deliberately fused in hyperlordosis, in the rest the alignment was acceptable. Primary stabilization was achieved in all but one. 107 pedicle screws were used; one screw in Th2 was placed lateral to the pedicle. 42 subaxial transarticular screws were used. There were no complications related to these screws. One patient experienced a non-instrument related neurological deterioration. Two infections and one hematoma drainage healed on conservative treatment. Loss of fixation and non-union developed in 2 patients. Patients with metastasis or myelopathy due to rheumatoid arthritis carried a high mortality risk. The Olerud Cervical Spine Fixation System is versatile in posterior fixation of the cervical spine and has proven to be both safe and efficient.

Adult↗
PubMed1999

Cervical spine fractures in the elderly: factors influencing survival in 65 cases.

To evaluate whether a cervical spine fracture increases the death risk in elderly patients, and to define risk factors, we studied the survival of 65 patients (26 women) with a mean age of 77 (66-99) years. 8 of the patients were tetraparetic. In 35 patients, the upper cervical spine was fractured. 7 patients suffered from ankylosing spondylitis. Severe co-morbidity was present in 16. Survival status and the date of death were retrieved from the government official personal registry. The expected survival was calculated from data retrieved from the Swedish National Board of Health and Welfare. Variables having a possible relation with survival (i.e., a p-value < 0.10 when entered into a Kaplan-Meier survival analysis) were used in a Cox multiple regression survival analysis. 53 (24-105) months after injury, 25 of the 65 patients had died. The survival was significantly lower than the expected values. Severe co-morbidity (risk ratio: 5,6), neurological injury (6,4), high age (1,1), and ankylosing spondylitis (5,5) proved to be significant risk factors for death. Thus, a cervical spine fracture may lead to earlier death in a patient with a severe co-morbidity. A neurological complication constitutes a risk also for a previously healthy individual. Patients having ankylosing spondylitis (with increased death risk) run a higher than normal risk of sustaining a cervical spine fracture.

Age Distribution↗
PubMed1997

Subaxial cervical spine subluxation in rheumatoid arthritis. A retrospective analysis of 16 operated patients after 1-5 years.

We evaluated the clinical and radiological outcomes in 16 patients (15 women) having rheumatoid arthritis with a mean age of 66 (55-77) years, on average 2 (1-5) years after decompression and stabilization, for subaxial subluxation of the cervical spine. The duration of rheumatoid arthritis averaged 30 (10-67) years and the duration of neck symptoms averaged 15 (1-60) months. Preoperatively, 11 of the patients had pain in the neck, all 16 suffered from arm rhizopathy and varying degrees of myelopathy. 4/5 patients with severe myelopathy died within 3 months of surgery. Fixation failure occurred in 7 patients, but had no clinical significance in 5. There were 1 deep infection and 1 nerve root lesion resulting in deltoid weakness. Other complications were dysphagia and donor-site pain. 4 reoperations were performed, 2 extension of fusion, 1 revision of infection, and 1 foraminotomy. Neck pain was reliably relieved, while arm rhizopathy was less positively affected. Myelopathy carried a poor prognosis for relief and its occurrence correlated with death. Early treatment, before significant myelopathy has developed, is recommended. Decompression, both via realignment and bone resection, followed by fusion of the entire cervical spine, is advocated. Due to the poor bone quality and with the presently available implant systems, simultaneous anterior and posterior fixation is beneficial.

Aged↗
PubMed1996

Outcome after limited posterior surgery for thoracic and lumbar spine metastases.

The efficacy of 'limited posterior surgery' for metastases in the thoracic and lumbar spine was studied prospectively in 51 patients (32 men and 19 women, mean age 64 years). The most common primary tumors were prostate, breast, and renal carcinoma, 37 patients had metastases in the thoracic spine and 14 in the lumbar spine. Indications for surgery were severe pain or neurologic deficit. Of the 46 patients with neurologic symptoms, 25 were unable to walk. Surgery was confined to direct or indirect decompression and stabilization with a pedicle screw fixator over few segments as possible. Pain, as well as a variety of functional performance parameters and residential status were registered preoperatively and after surgery at 3, 6, 9, and 12 months, and at 6-monthly intervals thereafter. Pain was rated by the patient on a Visual Analog Scale, and functional performance was assessed with the Eastern Co-operative Oncology Group (ECOG) Performance Status Scale. We had no perioperative neurologic deterioration or death. Nineteen of the 25 nonambulatory patients regained their walking ability. Postoperative pain relief was significant and lasting over time. Nearly half of the patients attained improvement in functional performance. The median survival was 8 months. Older age and intact postoperative walking ability were positive factors for survival.

Bone Screws↗