Analysis of the analgesic efficacy of acetaminophen 1000 mg, codeine phosphate 60 mg, and the combination of acetaminophen 1000 mg and codeine phosphate 60 mg in the relief of postoperative pain.

Patients who experienced pain after surgery were administered a single dose of 1 of 3 treatments: acetaminophen 1000 mg, codeine phosphate 60 mg, or a combination of these. Patients rated their pain intensity on ordinal and visual analog scales just prior to medication and at intervals thereafter for up to 5 hours. They also rated pain relief, pain half gone, and any adverse effects. Sum of pain intensity difference and total pain relief scores were analyzed using Dunnett's procedure. The drug combination was statistically superior to codeine as measured by SPID, TOTPAR, pain half gone, and time to remedication. The combination achieved better mean scores than acetaminophen on all efficacy measures, but was (marginally) statistically superior only in pain half gone. No appreciable differences in adverse effects were noted among the treatments. The difficulty of showing the analgesic efficacy of codeine in a single dose trial is discussed.

Moiré patterns: an accurate technique for determination of the locus of the centres of rotation.

This study describes an accurate technique for the determination of the centre of rotation of small angles. The moiré fringe method localizes the centre of rotation by defining two primary fringes, each of which is found by the intersection of three lines. The primary fringes intersect at the centre of rotation at 90 degrees to each other, the angle least likely to produce an error in measurement. By utilizing joints with known centres of rotation, we have found that the method is extremely accurate and reproducible to within 2 mm of the real centre for angular changes as small as 3 degrees. This technique is useful in evaluating whether a joint is a simple hinge, i.e. rotating about a single axis of rotation or whether the joint moves about a changing axis of rotation referred to as a locus or centrode.

Neurologic deterioration in patients with thoracic and lumbar fractures after admission to the hospital.

STUDY DESIGN: Thirty-five patients with spinal fractures in a series of 1019 patients deteriorated neurologically while in the hospital. Thirty-two were available for review. OBJECTIVES: To determine whether there was a preponderance of a fracture type associated with early neurologic deterioration. METHODS: Patients were evaluated by means of plain radiographs and computed tomography scans according to the classification of Denis for the fracture types. This was compared with a newer classification. Neurologic assessment was according to the Frankel grading system and the motor score index. RESULTS: Ten patients deteriorated by one Frankel grade and two deteriorated by three Frankel grades; the remaining deteriorated, but within the same grade. The motor score index dropped from 33.5 to 26.8. In the Denis classification, the most common injury was a burst fracture, including a significant number of rotational bursts. In the newer classification, those fractures that contained a component of rotation were the most commonly seen. CONCLUSION: When a torsional mechanism has been identified, additional care should be taken in managing patients with spinal fractures because of the risk of further neurologic injury.

Traumatic pneumomyelography. A marker of spinal column injury in the face of innocuous spine fractures: two case reports.

STUDY DESIGN: A report of two cases of spinal column injury. OBJECT: To document the presence of air within the spinal canal following spinal fractures. SUMMARY OF BACKGROUND DATA: Only two previous cases of air in the spinal canal have been reported in the English literature. This report emphasizes that even with innocuous-appearing fractures of the thoracic spine, a similar phenomenon can occur. METHODS: The author reports on the medical records and radiographic investigations related to these two cases. RESULTS: Air within the cervical, thoracic, and lumbar spine was identified in what appeared to be minor spinal fractures of the thoracic spine. CONCLUSIONS: In cases of relatively undisplaced fractures of the thoracic spine associated with air in the spinal canal, one should be alert to the possibility of more unstable injuries that may have undergone significant displacement at the time of the fracture.

Scoliosis Research Society. Multicenter spine fracture study.

This study consisted of 1,019 spinal fracture patients followed prospectively for 2 years. Sixty-four physicians from 12 countries participated. The purpose of the study was to determine: 1) the relationship between neurologic deficit and fracture type, level, and spinal canal compromise; 2) the neurologic outcome comparing surgical versus nonsurgical treatment and anterior versus posterior surgery; and 3) the relationship of pain to both kyphotic deformity and to surgical and nonsurgical treatment. The main findings of this study are as follows: 1) seat belts reduced the incidence of severe neurologic injury; 2) there was a higher incidence of neurologic deficit with fracture-dislocations and a higher incidence of neurologically intact patients with compression and flexion-distraction injuries; 3) there was a greater incidence of complete neurologic deficits caused by fractures at the spinal cord level, and a diminished incidence at the cauda equina level; 4) for burst fractures there was a weakly positive relationship between canal compromise and neurologic deficit, including bladder function; 5) surgical intervention led to a greater percentage of improved neurologic function than nonoperative treatment, but the rate of improvement was not statistically different; 6) anterior surgery was not more effective than posterior surgery in improving the neurologic function when function was assessed using the Frankel or Motor Index scales, but it was statistically significant when compared to the Manabe scale; 7) in patients who deteriorated before surgery and underwent surgery, there was a greater improvement neurologically, particularly for anterior surgery, compared to those patients treated nonoperatively or to the overall surgically treated group; 8) There was a statistically significant relationship between bladder function and fracture type, with an increased incidence of absent function seen with fracture-dislocations, of impaired function with burst fractures, and of intact bladder function with compression and flexion-distraction injuries; 9) anterior surgery was more beneficial in improving complete bladder impairment to partial impairment compared to posterior surgery; 10) a kyphotic deformity of greater than 30 degrees at 2-year follow-up was associated with an increased incidence of significant back pain; 11) patients who had surgery complained less of severe pain than those who were treated without surgery.

Accuracy of pedicular screw placement in vivo.

The accuracy of pedicular screw placement was assessed in 40 consecutive patients treated with the AO "Fixateur Interne." Postoperative CT scans were used to measure canal encroachment from the medial border of the pedicle, the angle of insertion and the point of entry. Eighty-one percent of the screws were placed within 2 mm of the medial border of the pedicle and 6% had 4-8 mm of canal encroachment with two patients developing minor neurological complications that spontaneously resolved. Four percent were inserted lateral to the pedicle. The parameters linked to satisfactory screw placement include entry point, angle of insertion and pedicular isthmus widths. Improvement in accuracy was noted in the latter 25% of screw insertions, reflecting the learning curve associated with this technique.

Pseudarthrosis of the lumbar spine. Outcome after circumferential fusion.

STUDY DESIGN: Twenty-five patients with a pseudarthrosis after previous spinal fusion surgery were reviewed after a circumferential fusion was performed. OBJECTIVES: To determine the fusion rate and its relation to outcome, i.e., pain reduction and return to work, and associated complications. SUMMARY OF BACKGROUND DATA: Circumferential fusion has become a common procedure with more patients undergoing multiple operations. This operation is thought to improve the fusion rate with a low complication rate. However, the procedure has not been evaluated specifically for the management of pseudarthrosis. METHODS: Twenty-five patients were reviewed regarding age, gender, smoking status, previous back surgeries, extent of leg and back pain, occupation, levels of surgery, type of instrumentation, blood loss, and complications. A minimum follow-up period of 2 years included evaluation of radiographs, pain levels, medication, and return to work. RESULTS: Twenty percent of patients were heavy smokers. An average of 2.2 previous procedures had been performed, and the average follow-up period was 2.7 years. Eighty percent of patients underwent multiple-level fusions. A solid fusion was achieved in 100%. Complications included two painful instrumentation devices requiring removal, one retroperitoneal hematoma, one anterior abdominal wall dehiscence, and one case of pneumonia. Pain scores improved from 7.4 to 4.7 for back pain, and 5.4 to 2.8 for leg pain, respectively. Both improvements were statistically significant (P < 0.01 and 0.003, respectively). However, only 52% of patients reduced their pain by a full category. Forty-one percent were still taking narcotics intermittently or consistently, and 53% returned to work or were actively seeking employment. DISCUSSION: A fusion rate of 100% was noted in the face of factors often placing patients at high risk for developing a pseudarthrosis, namely multiple levels of previous spinal surgery, including previous pseudarthrosis, and a habit of heavy smoking. Complications were few. However, the satisfactory outcome rate was only somewhat better than 50%, based on a lack of substantial pain improvement and return to work.

The management of burst fractures of the fifth lumbar vertebra.

Burst fractures of the fifth lumbar vertebra are extremely rare. Three cases of this fracture are reported and the treatment discussed. Two patients were treated conservatively with bed rest and lumbar bracing; the third underwent posterior decompression and instrumentation. All patients showed a loss of lordosis between L4 and the sacrum, this being greatest in the surgically treated patient. It is suggested that current instrumentation cannot adequately maintain this unusual fracture in good alignment and a conservative approach is advocated.

An unusual cause of lumbar discitis.

STUDY DESIGN: Case report. OBJECTIVE: To identify an unusual cause of lumbar discitis. SUMMARY OF BACKGROUND DATA: Discitis resulting from a foreign body has not been reported in the English-language literature. METHOD: A case report is reviewed identifying the presence of this foreign object (titanium), erroneously implanted into the disc space at L5-S1. Imaging studies identify the location and surrounding reaction. RESULTS: The surgical exploration of this disc revealed an inflammatory response surrounding the disc with degeneration within the disc space. CONCLUSION: If this gynecologic procedure is performed using bone anchors, care must be take to ensure that the sacrum is identified before insertion.

Thoracic facetectomy and bone grafting in the surgical treatment of adult idiopathic scoliosis.

A retrospective study of adult patients with surgically treated idiopathic scoliosis was carried out to determine the importance of thoracic facetectomy and bone grafting. The results indicate that failure to excise and bone graft the thoracic facets was not associated with a significant impairment of initial correction or loss of correction after a mean follow-up of 2 years. The incidence of pseudarthrosis was comparable to other series. It also was established that the use of Bobechko hooks without postoperative bracing gave satisfactory results.

Analysis of sagittal plane instability of the lumbar spine in vivo.

Segmental instability secondary to degenerative disc disease may result in chronic low-back pain. In the sagittal plane, segmental instability can be characterized during lumbar motion from full extension to full flexion. The authors studied this movement using a translational method for the kinematic analysis, implementing a new concept known as the instability factor. Both translational and angular components of motion are evaluated. By computing the incremental motion parameters at different stages of spinal bending, the total amount of translation and angulation is obtained and combined in a ratio termed the instability factor. This factor increases with linear instability and decreases with rotational instability. The authors reviewed 12 control subjects and 36 patients with chronic low-back pain. The diagnoses of patients were categorized into three groups: idiopathic low-back pain, lumbar disc prolapse, and degenerative disc disease. Lateral radiographs of each subject's spine at the L4-5 level were obtained using low dose radiography and were performed serially as the subjects moved from full extension to full flexion. It was found that the group of patients with degenerative disc disease had an average age-corrected instability factor of 37.3 (mm/radian), which was significantly larger than that of normal subjects 25.5 (mm/radian), (P = 0.0065). No significant difference was seen in the instability factor of patients with idiopathic low-back pain or lumbar disc prolapse.

Computer analysis of spinal segment motion in degenerative disc disease with and without axial loading.

The center of rotation of the spinal motion segment is an indicator of spinal instability. However, the motion segment does not move about a single fixed axis of rotation, but rather a locus of instantaneous axes of rotation, the centrode. This paper studies centrodes in various stages of degenerative disc disease comparing them with normal spines. Computer analysis is undertaken in 47 cadaveric spines, 22 of which also were evaluated with axial loading. The normal centrode fell within the posterior half of the disc space and averaged 21 mm in ten specimens. In the earliest stages of degenerative disc disease, the centrode lengths increased significantly (average 116 mm). Specimens with moderate disc degeneration also migrated inferiorly into the L5 vertebra. Axial loading did not appear to influence the centrode lengths or position. This technique is highly sensitive, detecting 94% of the abnormal spines as compared with only 25% detected by means of measuring an excessive range of motion on flexion and extension radiographs. This method provides a highly reliable and quantifiable method of detecting early changes in spinal motion in degenerative disc disease prior to the well recognized radiographic abnormalities.

Centrode patterns in the lumbar spine. Baseline studies in normal subjects.

Segmental spinal instability is a known cause of back pain, but no method of accurately quantifying instability exists. The movement of complex joints with rotational and translational components (such as the lumbar motion segment) is tracked by a pathway of instantaneous centers of rotation, or a centrode. Instability, ie, excessive and/or erratic movement, is reflected by increased centrode length in cadaver studies. This study describes an in vivo method that precisely determines the centrode pattern and reports the results for 21 normal male volunteers who were studied at the L4-5 and L5-S1 levels. Each volunteer underwent lateral radiographs of the lumbar spine. High speed films were used and six positions, from full extension to full flexion, were recorded. Acetate tracings and contour matching techniques recorded the relative positions of the vertebral bodies on each film. Multiple tracings of each radiograph, combined with a digitizer and computer, were used to improve precision in the calculated centrode patterns. Centrode lengths measured 43.7 mm and 55.9 mm, respectively, for the L4-5 and L5-S1 levels. This study demonstrates that precise centrode pattern analysis for sagittal plane motion of the lumbar spine is possible in vivo. Studies are under way to determine whether this technique will be useful as a clinical test in diagnosing early segmental instability of the lumbar spine in patients with low-back pain.

Centrode patterns and segmental instability in degenerative disc disease.

Moiré fringes were used to determine centrode patterns in cadaveric spines with degenerative disc disease. The normal centrodes were compared with those with minor, mild, moderate, and severe degenerative disc disease. The most complex loci noted were those discs that showed minimal radiographic evidence of degeneration, that is, the minor and mild groups. The loci lengthened significantly (P less than 0.001) when compared with normal controls. The position of the centrode shifted downward into the body of L5 in the moderate group.

Canal clearance in burst fractures using the AO internal fixator.

The purpose of this study was to evaluate the ability of posterior distraction delivered by the AO internal fixator to effect a satisfactory reduction of the intraspinal fragments in burst fractures. The overall decompression achieved was from an initial compromise of 54% to a residual encroachment of 40%. Canal clearance proved most effective when carried out in the first 4 days, with an initial canal compromise of between 34 and 66%. The extent of improvement, even in this group, was not dramatic, with an average of 31% encroachment still remaining, with some cases as high as 50%. Therefore, we recommend that when canal clearance is essential, anterior decompression is the treatment of choice.

Determination of a locus of instantaneous centers of rotation of the lumbar disc by moiré fringes. A new technique.

The aim of this study was to define the motion of the L4-5 spinal segment moving from full extension to full flexion. A new technique using moiré fringes was applied to measure angles of 3-degree change, a technique proven to be highly accurate for small angular changes. This investigation has identified a locus of centers of rotation (centrode) that is located in the posterior half of the intervertebral disc. The direction of the locus passes from posterior to anterior and back to posterior. The technique can be adapted for evaluation of in vivo radiographs. This technique may prove useful in identifying aberrations in movement associated with spinal segment instability in its earliest stages.

Semirigid instrumentation in the management of lumbar spinal conditions combined with circumferential fusion. A multicenter study.

STUDY DESIGN: Patients with the diagnosis of degenerative disc conditions or spondylolisthesis undergoing circumferential fusion with posterior pedicle screw fixation using a semirigid rod were reviewed. OBJECTIVES: To determine the effectiveness of this approach in achieving a spinal fusion and satisfactory clinical outcome, and to determine the complications associated with the procedure. SUMMARY OF BACKGROUND DATA: The use of instrumentation to stabilize the lumbar motion segments and thereby enhance the fusion rate has been proposed in a number of studies. Semirigid fixation was believed to be effective in achieving these objectives without concern for stress-shielding, which was suggested by some authors using rigid fixation systems. METHODS: Patients who required spinal fusion with anterior and posterior approaches because of specific lumbar pathology or previous surgeries were selected. The surgery consisted of an anterior interbody fusion using allograft, followed by a posterolateral fusion and pedicle screw fixation. Fusion was determined by continuity of trabecular bridging, and outcomes were determined by pain reduction and return to previous levels of activity. Fusion was considered solid if the two posterolateral areas were fused (Zones one and two), if the anterior interbody area was fused (Zone three), or if all three zones were fused. Complications were documented during and after surgery. RESULTS: Sixty-two percent of patients had previous surgery with 25% of these patients having a diagnosis of pseudarthrosis. Fifty-five percent of patients had two or more levels fused, and 43% were heavy smokers. Ninety-seven percent of patients had successful fusions. Pain was significantly reduced on a pain analogue scale from 7.1 to 2.1 in the back and from 5.8 to 1.5 in the leg (p < 0.006 and 0.0001, respectively). Fifty-nine percent of patients returned to their previous level of activity, and 18% returned to lighter work or job retraining, for a total of 77% returning to the same or lighter levels of activity. Complications included metal failure, 4.9%; neurologic deficit, 1.2%; deep infection, 1.2%; deep venous thrombosis, 4.9%; and vascular injury, 2.4%. Fatal pulmonary embolus occurred in one patient. CONCLUSION: This technique produces a satisfactory fusion rate (97%) and a good clinical outcome based on pain reduction and return to a satisfactory level of activity (77%). It is associated with few, but significant, complications that compare well with other reported series in a difficult group of patients. This procedure should be reserved for patients who are considered to be at high risk for not achieving spinal fusion.

The neurological outcome following surgery for spinal fractures.

Sixty consecutive patients with spinal injuries and encroachment upon the spinal canal of greater than 20% were assessed for neurological outcome. The patients were divided into two groups, those undergoing posterior surgery alone, and those undergoing anterior surgery for formal decompression with or without anterior or posterior instrumentation. In those patients undergoing posterior surgery, an improvement rate in the neurological function of 83% was noted in patients with incomplete lesions, whereas an 88% improvement rate was found in those undergoing the anterior procedure. There was no statistical difference in outcome between these two groups. Positive correlations were found between the level of injury and Frankel grades. The cord lesions tended to demonstrate more severe neurological deficit, whereas the cauda equina lesions were associated with a lesser severity of neurologic deficit. A component of dislocation to the injury also resulted in a more severe neurological deficit. There was no apparent difference between the degree of bony encroachment of the spinal canal and the initial Frankel grade, nor was there a clear difference between those patients undergoing anterior versus posterior surgery.

Decompression and circumferential stabilization of unstable spinal fractures.

A technique of anterior decompression of the spinal canal with anterior strut grafts, followed by posterior instrumentation and local fusion, is described in a group of 18 patients with unstable thoracolumbar fractures. All patients were found to have greater than 50% encroachment of the spinal canal and a preoperative kyphosis of 21.8 degrees. At follow-up 81% of patients with incomplete neurological lesions improved at least one Frankel Grade. Residual encroachment on the spinal canal was 4.6% and at follow-up the kyphotic angle was 17.1 degrees. Complications included one anterior graft loosening (not requiring revision), three loosened rods, only one of which required revision, and one fractured Harrington rod which did not require revision. The authors conclude that this technique is an effective and safe method for treating unstable thoracolumbar injuries and is recommended if anterior instrumentation is unavailable.

Results of a locking-hook spinal rod for fractures of the thoracic and lumbar spine.

The results of a consecutive series of 110 patients treated with the locking-hook spinal rod are presented. A prospective protocol was completed in 95 patients. Pain was absent or mild in 93%. In those patients with a partial neurologic deficit, there was recovery of at least one Frankel grade in 84%. The overall kyphotic deformity was reduced from 21 to 17 degrees. In those patients in whom no anterior surgery was performed, the deformity improved from 21 to 13 degrees. No rod fractures occurred, and the overall instrument complication rate was 13.7%, of which one was due to infection and four secondary to uncrimped nuts, for a true complication rate of 8.4%. The locking-hook spinal rod has proven to be a satisfactory internal fixation device in the treatment of unstable thoracolumbar fractures.