Imbalance between procoagulant factors and natural coagulation inhibitors contributes to hypercoagulability in the critically ill COVID-19 patient: clinical implications.

OBJECTIVE: Coronavirus Disease-2019 (COVID-19) predisposes patients to thrombosis which underlying mechanisms are still incompletely understood. We sought to investigate the balance between procoagulant factors and natural coagulation inhibitors in the critically ill COVID-19 patient and to evaluate the usefulness of hemostasis parameters to identify patients at risk of venous thromboembolic event (VTE). PATIENTS AND METHODS: We conducted an observational study recording VTEs defined as deep vein thrombosis or pulmonary embolism using lower limb ultrasound (92% of the patients), computed tomography pulmonary angiography (6%) and both tests (2%). We developed a comprehensive analysis of hemostasis. RESULTS: Ninety-two consecutive mechanically ventilated COVID-19 patients (age, 62 years [53-69] (median [25th-75th percentiles]); M/F sex ratio, 2.5; body-mass index, 28 kg/m2 [25-32]; past hypertension (52%) and diabetes mellitus (30%)) admitted to the Intensive Care Unit (ICU) from 03/11/2020 to 5/05/2020, were included. When tested, patients were receiving prophylactic (74%) or therapeutic (26%) anticoagulation. Forty patients (43%) were diagnosed with VTE. Patients displayed inflammatory and prothrombotic profile including markedly elevated plasma fibrinogen (7.7 g/L [6.1-8.6]), D-dimer (3,360 ng/mL [1668-7575]), factor V (166 IU/dL [136-195]) and factor VIII activities (294 IU/dL [223-362]). We evidenced significant discrepant protein C anticoagulant and chromogenic activities, combined with slightly decreased protein S activity. Plasma D-dimer >3,300 ng/mL predicted VTE presence with 78% (95%-confidence interval (95% CI), 62-89) sensitivity, 69% (95% CI, 55-81) specificity, 66% (95% CI, 51-79) positive predictive value and 80% (95% CI, 65-90) negative predictive value [area under the ROC curve, 0.779 (95%CI, 0.681-0.859), p=0.0001]. CONCLUSIONS: Mechanically ventilated COVID-19 patients present with an imbalance between markedly increased factor V/VIII activity and overwhelmed protein C/S pathway. Plasma D-dimer may be a useful biomarker at the bedside for suspicion of VTE.

[Comparative Cost Effectiveness of Clostridium Histolyticum Collagenase (Xiapex®) and Partial Fasciectomy for the Treatment of Dupuytren's Contracture in Austria]. / Kosteneffektivität der Behandlung von Patienten mit Dupuytren-Kontraktur mit mikrobieller Collagenase Clostridium histolyticum (Xiapex®) im Vergleich zur partiellen Fasziektomie in Österreich.

INTRODUCTION: Since Dupuytren's contracture is a common disorder, the costs for its surgical treatment impose a considerable burden on the healthcare system. For the first time in the German-speaking area, this study aimed to provide a comparative cost-effectiveness analysis for partial fasciectomy vs. treatment with Clostridium histolyticum collagenase (CCH). METHODS: A retrospective monocentric study of the period from 2012 to 2014 comprised 40 patients with previously untreated Dupuytren's contracture of one finger. 20 outpatients received one CCH treatment (Group 1), while 20 inpatients underwent partial fasciectomy (Group 2). The direct pre-interventional treatment and post-interventional costs were compared. RESULTS: The direct post-interventional and postoperative results were comparable. Group 1 (CCH) showed a mean reduction in contracture of 96.4%; in Group 2 (partial fasciectomy), this was 97.7%. There were fewer complications in Group 1 than in Group 2. Mean treatment costs in Group 1 were € 1 458.60 and in Group 2, € 5 315.20. CONCLUSION: Treatment with CCH is more cost effective than with partial fasciectomy. This is due to greater costs for personnel, time and surgical material, as well as the treatment of the more frequent complications in Group 2. Despite the limited comparability, our findings are consistent with the present international literature.

One-stage reconstruction of isolated and combined tendon defects with the vascularized adductor magnus tendon graft: Surgical technique and preliminary results.

INTRODUCTION: Secondary reconstructions of isolated and combined tendon defects are still a challenge for plastic surgeons. Due to its reliable anatomy, reconstructive potential and low donor-site morbidity, the medial femoral condyle is an ideal area for harvesting isolated and combined tendon flaps. This study evaluates our preliminary results with the vascularized adductor magnus tendon flap. PATIENT AND METHODS: The study included six patients who received a vascularized tendon flap (upper extremity: three patients; lower extremity: three patients) from 2011 to 2015. For three patients, the adductor magnus tendon was used as a single flap; for the other three patients, the tendon was included in a composite flap. A retrospective chart review provided the patients' demographic data, surgical details and the post-operative course. The further objective and patient-reported outcome was evaluated with a long-term follow-up. RESULTS: All of the free vascularized flaps healed without complications and with good vascularization upon duplex ultrasonography. One patient did, however, require revision surgery in the late post-operative course. At the end point, all patients showed good functional results without any donor-site morbidity. CONCLUSION: For carefully selected isolated and combined tendon defects on the upper and lower extremities, the vascularized adductor magnus tendon flap provides a reliable and versatile method for microsurgical reconstruction.

[Treatment of Dupuytren's disease with collagenase - a 1-year follow-up of 37 patients]. / Behandlung der Dupuytren'schen Kontraktur mit Kollagenase - Ein-Jahres-Follow-up-Analyse anhand von 37 Patienten.

INTRODUCTION: The efficiency of collagenase of Clostridium histolyticum (CCH; Xiapex) in the treatment of Dupuytren's contracture has been proved in phase III studies. This retrospective study aims to evaluate our clinical results after the use of CCH. PATIENTS AND METHODS: The study included 40 Dupuytren's contractures in 37 patients. There were 32 male and 5 female patients; their average age was 66 years. The most affected finger was the ring finger (55%; 22/40), followed by the little finger (30%; 12/40) and the middle finger (15; 6/40). 14 fingers (35%) presented isolated contractures of the metacarpophalangeal joint whereas an isolated contracture of the proximal interphalangeal joint was evident in 8 (20%) fingers. 18 (45%) fingers presented combined MCP and PIP flexion contractures. None of the patients underwent any treatment prior to this study. A retrospective chart review was performed of all patients. Follow-up examinations were performed seven days, fourteen days, three months, six months and one year after the intervention. The follow-up examination included goniometry of each affected finger to assess the range of motion (ROM) before and after cord breaking. Further patient-reported outcome was accessed concerning postinterventional complaints, impairment of sensibility and satisfaction with the treatment. RESULTS: The range of motion improved in all fingers. Full extension of the affected finger without any contracture could be observed in 93% of the MCP contractures, 38% of the PIP contractures and in 28% of the combined MCP and PIP contractures. Incomplete cord breaking could be observed in 9 (22.5%) fingers. In 8 fingers (20%) skin tears occurred after joint manipulation but healed up without any further surgical intervention. The recurrence rate at the latest follow-up was 2.5% (1/40). Patient satisfaction was high and none of the patients reported any complaints at the latest follow-up. CONCLUSION: The best results could be achieved in patients with isolated contractures of the MCP joint. Regarding the good functional results, the low complication rates and the high patient satisfaction, CCH represents a simple and effective treatment for Dupuytren's contracture in selected cases.

Monitoring of scoliosis surgery with epidurally recorded motor evoked potentials (D wave) revealed false results.

OBJECTIVE: To elucidate the mechanism behind D wave amplitude changes after surgical correction of scoliosis. METHODS: We collected D wave and muscle MEP data from 93 patients (78 female, 15 male, age range 4-19 years, mean age 15.9 years), who underwent surgical correction of scoliosis. D waves were recorded via a catheter electrode inserted epidurally through the flavectomy. Muscle MEPs from lower limb muscles were also recorded. Muscle MEPs/D wave were elicited by short trains/single transcranial electrical stimuli. SEPs were elicited through bilateral percutaneous stimulation of the tibial nerves at the ankle and an averaged response from 100 to 200 single sweeps were recorded over the scalp at Cz'/Fz. In addition, we analyzed intraoperatively obtained X-ray images of the spine in 9 patients and preoperative spinal MRI in two of those nine. RESULTS: After surgical correction of scoliosis in 25 of 93 (27%) patients, the D wave amplitude changed by more than 20% of its baseline value. A decremental change occurred in 21 (84%) and an incremental change in 4 (16%) patients. D wave decrements of more than 50% were observed in 5 patients without significant SEP changes in any of these cases. In 9 patients, intraoperatively obtained X-rays of the spine (before and after correction of spine curvature) showed no catheter displacement. Muscle MEPs did not change and postoperative sensory-motor status was normal. In 2 patients, preoperative MRI revealed displacement of the spinal cord towards the concave side of the scoliotic curvature. CONCLUSIONS: During scoliosis surgery, D wave amplitude changes should be interpreted cautiously until the definitive cause(s) of these changes are found. One possible mechanism to explain D wave changes during scoliosis correction could involve rotation of the spinal cord within the spinal canal, and the relative position of the epidural recording catheter (ERC). Rotation of the spinal cord after correction of scoliosis could introduce a new relationship between the ERC and the corticospinal tracts (CTs). Due to high incidence of false D wave amplitude changes we suggest that this methodology should not be used to assess the functional integrity of the CTs during scoliosis surgery. SIGNIFICANCE: This study provides new insight into the methodology of D wave monitoring as well as strong evidence of a high incidence of false positive results using D wave monitoring during surgical correction of scoliosis.

Bilateral epilepsy surgery in a 4-year-old child.

OBJECTIVE: Reports on bilateral epilepsy surgical interventions are anecdotal because of the possible neurological deficits caused by them. METHODS: We report on a four-year-old amaurotic child with catastrophic epilepsy due to bilateral occipital cortical dysplasia. After video-EEG monitoring and intraoperative electrocorticography he underwent a two-step bilateral occipital lobectomy. RESULTS: The first resection resulted in only temporary seizure cessation; however, he became seizure-free after the second operation (follow-up: 20 months). CONCLUSION: Patients with catastrophic epilepsy due to bilateral epileptogenic lesions but without a high risk of additional postsurgical deficit may be good candidates for epilepsy surgery.

Good results of circumferential spine fusion in smokers, using autograft and allograft.

We have examined the rates of anterior interbody fusion of lumbar spine segments following fusion with a fresh frozen femoral head allograft in 25 heavy smoking patients. They were all stabilized both anteriorly and posteriorly. The indications for surgery were: degenerative disc disease, degenerative spondylolisthesis and nonunion following previous posterolateral fusion of lumbar spine segments. Only patients who had fusion of one or two lumbar segments were included. They all were stabilized posteriorly with pedicle screws and autogenic iliac bone graft. The fusion was assessed at least one year after surgery according to plan X-rays as "Solid", "Questionable" or "Failure". One patient was found at follow up not fused, in another one the fusion was "questionable" and all the other 23 patients had an anterior solid fusion. Clinically, 84% of the patients had the same or improved work status as before surgery and 68% acknowledged that they were satisfied with the surgical results. No major complications were recorded and the average length of hospitalization was 10.3 days.

[Macrocytic anemia and neurological signs due to vitamin B-12 deficiency in a breast-fed infant of a strict vegetarian mother]. / Anyai vegan diéta talaján kialakult csecsemókori B12-vitaminhiányos macrocytaer anaemia idegrendszeri tünetekkel.

Vitamin B12 deficiency is a very rare disease of infants and young children in Europe. Authors report a case of a 9.5-month-old infant who was exclusively breast-fed by his vegan mother and developed serious vitamin B12 deficiency in form of neurological regression, repetitive vomiting, drowsiness, dysphagia, obstipation, and tremor. A few days after intramuscular vitamin substitution his abnormal signs improved dramatically, hematological restitution was reached in six weeks. Authors describe the hematological and neurological signs, the diagnostic and differential-diagnostic pitfalls, therapy, prognosis, and prevention of this condition. Beside reviewing the literature they emphasize the importance of early recognition and intervention and the need of an appropriate doctor-parent cooperation in this disease.

Instrumented posterior arthrodesis of the lumbar spine in patients with diabetes mellitus.

The existence of diabetes mellitus has been postulated to have a deleterious effect on the outcome following lumbar spine surgery. We retrospectively examined the records and radiographs of 32 diabetic patients (mean age, 60 years) who underwent posterior lumbar fusions using transpedicular instrumentation and iliac crest autograft. Ten patients were insulin-dependent and 22 required oral hypoglycemic agents for at least 1 year prior to surgery. The minimum follow-up time was 2 years after surgery (mean, 2.5 years). Surgical indications included herniated lumbar disk, lumbar spinal stenosis, thoracolumbar trauma, and lumbar pseudarthrosis. Clinical results were evaluated by chart review and/or interview by using Odom's criteria. At follow-up, 75% of patients were graded as excellent or good, and 25% as fair or poor. Twenty-five of 32 patients (78%) had improvement of back pain. Twenty of 27 (74%) patients had improvement of leg pain. Eight of 15 (53%) patients had improvement in motor strength, and 6 of 11 (54%) had improvement in light-touch sensation. Insulin dependence and the presence of polyneuropathy were associated with a poorer outcome. The average time to radiographic fusion was 5 months. Twenty-nine of 32 patients (91%) developed solid fusion by strict radiographic criteria. The three patients with a pseudarthrosis had persistent back pain and a poor result. Ten of 32 (31%) of the patients experienced perioperative complications, including prolonged wound drainage (n = 5), deep wound infection (n = 1), superficial wound infection (n = 1), atrial fibrillation (n = 1), ruptured cerebral aneurysm (n = 1), and ulnar nerve neuropathy (n = 1). We conclude that posterolateral lumbar spinal fusion with internal fixation in diabetic patients yields clinical results comparable to those of nondiabetic patients, with similar risks of perioperative complications.

Hippocampal malrotation with normal corpus callosum: a new entity?

Among 527 MRI examinations of patients with a suspicion of epilepsy in 5 years, we found 32 cases of hippocampal malrotation (HIMAL). The characteristic features are: incomplete inversion of the hippocampus with and abnormally round shape; unilateral involvement of the whole hippocampus; normal signal intensity and size; blurred internal structure; an abnormal angle of collateral sulcus; abnormal position and size of the fornix; normal size of the temporal lobe; enlargement and particular configuration of the temporal horn, typical of corpus callosum agenesis; and a normal corpus callosum. In 7 cases (22%) HIMAL occurred together with developmental disorders. It was predominantly seen in men. The clinical features were varied. Based on some MRI features, the presence of developmental disorders, the male predominance, the frequently positive family history, and a review of the literature, we think HIMAL may be the consequence of a mild hemisphere developmental disorder. It is probably not the basic cause of epilepsy in such varied clinical setting, but may be a sign of a developmental disorder and can help in selecting patients for more meticulous investigation. It also may give some new understanding of brain development.

Comparison between the outer table and intracortical methods of obtaining autogenous bone graft from the iliac crest.

STUDY DESIGN: A prospective study in two groups of patients selected randomly. OBJECTIVES: To determine whether keeping the outer and inner cortices of the ilium intact, while obtaining bone graft, would result in reduced postoperative bleeding and less postoperative pain. SUMMARY OF BACKGROUND DATA: Donor site complications after harvesting bone from the iliac crest are frequent. They comprise pain and bleeding related to the large bone exposed, injuries to the cluneal nerve, and sacroiliac instability. METHOD: Sixty patients who were admitted for elective fusion of lumbar segments were included in the study. In half of them, the iliac bone graft was taken in the outer Table method (group A), which included the outer cortex and the cancellous bone beneath, and in the remaining 30 patients only the cancellous bone from between the cortices was collected (group B). The amount of bone harvested, and the time taken to obtain it, were measured, as was the blood volume in the drains. At fixed intervals after surgery and up to 2 years thereafter, the patients were asked to grade the severity of pain in their back and at the donor site. RESULTS: Two years after surgery, 22% of the patients in group A and 17% of the patients in group B reported to have significant pain at the donor site. This difference was not found to be statistically significant, nor was the postoperative bleeding. The average amount of bone harvested in group A was 36 grams compared with 25.7 grams in group B, taking 14 minutes and 20.3 minutes, respectively, to harvest it. These differences were found to be statistically significant. CONCLUSIONS: Preserving the iliac cortices, while obtaining bone graft, does not reduce the postoperative bleeding or the severity of pain at the donor site. In the intraosseous method, less bone is harvested and longer duration of surgery is required, compared with that of the outer Table method.

Injuries to the lateral femoral cutaneous nerve during spine surgery.

STUDY DESIGN: A prospective study to locate patients with injured lateral femoral cutaneous nerve after elective spine surgery. OBJECTIVES: To assess the prevalence of injury of the lateral femoral cutaneous nerve and to identify the cause of injury according to the position of the patients at surgery and the surgical approach. SUMMARY OF BACKGROUND DATA: Injuries to the lateral femoral cutaneous nerve, also known as meralgia paresthetica, may cause pain and therefore result in restriction of activity. Compression of the nerve by disc hernia, retroperitoneal tumors, and external pressure around the anterior superior iliac spine are among the more common causes. METHODS: One hundred five patients admitted for elective spine procedures were grouped according to position on the operating table and surgical approach. All patients were examined before and after surgery for signs of injury to the lateral femoral cutaneous nerve, and those found injured were followed up for 1 year after surgery. RESULTS: Injury to the lateral femoral cutaneous nerve was found in 21 (20%) patients. In 6 of them, all of whom underwent surgery on the Hall-Relton frame, the injury was bilateral. In 7 patients the injury was not associated with discomfort. In addition to injury by external pressure at the anterior superior iliac spine from the Hall-Relton frame, the nerve was also injured at the retroperitoneum by hematoma or traction and at the anterior iliac crest when bone was harvested. In 89% of the patients, the nerve completely recovered within 3 months of surgery. Two patients still had pain 1 year after surgery and hypoesthesia of the anterolateral thigh. CONCLUSION: Injuries to the lateral femoral cutaneous nerve during spine surgery are frequent, and patients should be informed of the possible risk. It usually has a benign course, but some preventive steps should be taken: keep posterior to the anterior superior iliac spine and minimize retraction when harvesting a bone graft, pad the posts of the Hall-Relton frame over the anterior superior iliac crest, and avoid traction on the psoas muscle during the retroperitoneal dissection.

Use of the anterior interbody fresh-frozen femoral head allograft in circumferential lumbar fusions.

Many studies in the literature have documented the outcome of circumferential lumbar fusions. However, no study has specifically evaluated the performance of the anterior fresh-frozen femoral head allograft as a structural interbody graft material. All office and hospital records, including charts and radiographs, were reviewed to obtain pertinent clinical and radiographic information. The cases included 23 single-level fusions, 22 two-level fusions, and 5 fusions of three or more levels. In all, 88 fusion levels were analyzed radiographically. The mean follow-up time was 28 months (range, 24 to 36 months). All procedures were performed in a single stage. At the latest follow-up, clinical outcome was graded good to excellent in 39 (78%) cases, fair in 8 (16%) cases, and poor in 3 (6%) cases. The average time to anterior radiographic fusion was 6 months (range, 4 to 8 months). The overall fusion rate was 98%. The average preoperative anterior disk space height was 10 mm, 14 mm immediately after operation, and 13 mm at follow-up. The posterior disk space height averaged 5 mm before operation, 7 mm immediately after operation, and 6 mm at follow-up. The average segmental lordosis was 7 degrees before operation, 10 degrees immediately after operation, and 10 degrees at follow-up. Late postoperative disk space collapse of 3 mm or more was noted in 17% of the fused disk spaces examined. Seventy-eight percent of the disk spaces maintained a disk space height greater than that of their preoperative value at the latest follow-up. Segmental lordosis did not change significantly at follow-up. The occurrence of collapse did not correlate with the clinical result, smoking history, or surgical indication (p < 0.05). Perioperative complications included one pleural effusion, two urinary tract infections, and one deep wound infection. Late complications included five painful graft sites and two patients with pseudarthrosis. Fresh-frozen femoral head allograft fulfills its desired function as an anterior structural graft in combination with rigid posterior transpedicular fixation, maintaining the disk space height achieved at surgery while reliably allowing remodeling and incorporation into a solid anterior fusion.

An algorithm for selection of instrumentation levels in scoliosis.

Appropriate levels for instrumentation and fusion in scoliosis have been a matter of debate among surgeons since the introduction of operative management of this deformity. We set out to examine the hypothesis that the amount of correction achieved in all planes during surgical instrumentation of a curve should be less than, or comparable to, the degree of correction attainable at any non-instrumented adjacent curve. An algorithm was designed to facilitate preoperative planning and intraoperative performance of spinal fusion procedures in the management of scoliosis. To test the validity of the hypothesis and the proposed algorithm, measurements were taken from the preoperative radiographs of 200 patients. The dimensions of the curves were obtained from an initial set of four X-ray films: (1) standing anteroposterior film of the whole spine, (2) standing lateral film of the whole spine, (3) two properly performed side-bending films including each curve of the spine. With this data, a plan was designed using the algorithm. The results of this plan were compared with the actual results of the surgery, which were revealed only at this stage. All patients in whom actual instrumentation levels fell within those predicted by the proposed algorithm had no imbalance at follow-up. All patients whose actual instrumentation levels were short of those recommended by the algorithm showed obvious imbalance on final postoperative standing radiograph.

Anal duct/gland cyst: report of a case and review of the literature.

PURPOSE: The purpose of this communication is to report a case of anal duct/gland cyst and review cases of perianal and presacrococcygeal mucus-secreting cysts reported in the literature with emphasis on their histopathologic features. METHOD: Our patient presented with coccydynia. An extraluminal retrorectal tumor was felt on rectal examination. A computerized tomographic scan demonstrated a presacrococcygeal mass closely related to the anorectal junction. The tumor and the coccyx were excised using a posterior approach. Cases of perianal and presacrococcygeal mucus-secreting cysts reported in the literature were reviewed. RESULTS: In our case, the tumor proved to be an anal duct/gland cyst. Some of the reported cases of presacrococcygeal glandular cysts had histopathologic features suggestive of anal duct/gland origin. CONCLUSION: Diagnosis of anal duct/gland cyst is based on routine histologic features, histochemical characteristics of mucus, and/or the presence of a communication with an anal duct or crypt. Based on these criteria, some of the reported cases of mucus-secreting cysts occurring around the anorectum may prove to be anal duct/gland in origin.

Screw omission and the stability of posterior pedicle screw constructs for short-segment stabilization.

To determine the net contribution of a spinal construct to stability, and whether extending the construct to another level in situations in which a defective pedicle cannot have a screw inserted, we performed biomechanical tests in which we evaluated three-, four-, and five-level synthetic spinal constructs in which the location and number of pedicle screws were varied above and below a vertebrectomy defect. We subjected all constructs to axial, compression, lateral bending, flexion, extension, and torsional forces with the use of an Instron biaxial machine. Left-right symmetrical constructs were more stable than asymmetrical ones. Three-level constructs were statistically stiffer than the longer ones in compression, left bending, and flexion. Torsional stability, however, was greater in the longer constructs. Five-level constructs with both end screws in place had greater torsional stiffness than when they were missing a screw. In vertebrectomy defects, if four screws cannot be placed across it, then the engagement of two screws is indicated. The stability provided by a single screw at a spinal level is minimal. Additional screws augment the purchase of the construct in the bone; however, they do not afford further protection to the defect.

The mechanical role of laminar hook protection of pedicle screws at the caudal end vertebra.

Biomechanical studies have shown hooks to be superior to pedicle screws in pull-out, especially in osteoporosis. This study evaluates the possible increase in stiffness of pedicle screws provided by laminar hooks while applying non-destructive forces to a vertebrectomy model assembled with Compact Cotrel Dubousset (CCD) instrumentation. Synthetic vertebrae were employed in a three-level vertebrectomy model. CCD screw-based three-level constructs with and without sublaminar hooks in the caudal element were tested in flexion, extension, compression, lateral bending, and torsion. There was no statistically significant advantage in adding inferior laminar hooks to a caudal end vertebra that had bilateral pedicle screws in any of the testing modes. Torsional stability, however, was augmented, but not significantly. Torsional instability and osteoporotic bone may be the clinical justifications for adding laminar hooks below screws in the caudal end vertebra.

An anatomic evaluation of L5 nerve stretch in spondylolisthesis reduction.

STUDY DESIGN: Lumbosacral spondylolisthesis was simulated using four embalmed human spines, and the path of the L5 nerve was studied. OBJECTIVES: To quantify the change in length of the L5 nerve root associated with reduction of spondylolisthesis, correction of slip angle, and changing disc height. SUMMARY OF BACKGROUND DATA: Stretch injury to the lumbar nerves remains a complication of spondylolisthesis reduction. To date, no anatomic studies have been performed to quantify this effect of reduction on the lumbar nerves. METHODS: The L5 vertebral body and the sacrum of four embalmed human spines were constrained in an adjustable jig, and the length of a simulated nerve was determined for various position variables--sagittal translation (0-100% slip), slip angle (-40 degrees to +20 degrees), and disc height (5 or 10 mm). Two standard points of reference were chosen to represent fixed points along the path of the L5 nerve. An inelastic cord was used to measure the path length between these points as L5 was reduced from 100% to 0% slip. Testing was performed using a 5-mm and a 10-mm disc height. The effect of varying slip angle alone was also studied. RESULTS: The effect of spondylolisthesis reduction and slip angle correction on nerve length varied depending on the location of L5 with respect to the sacrum. There was an increasing effect of partial reduction on nerve length as L5 approached full reduction. Initially, little strain was produced in the L5 nerve as L5 was reduced in higher grade slips. However, as L5 approached full reduction, the strain per increment of reduction increased rapidly. On average, the mean nerve strain was 4.0% for the first 50% of reduction and 10.0% for the second half of reduction. Increasing lordosis relaxed the nerve in high-grade slips and stretched the nerve in fully reduced slips. At 100% slip, the mean nerve excursion decreased 5.1 mm (nerve slackening) when L5 was rotated from +20 degrees to -40 degrees. At 0% slip, the mean nerve excursion increased 3.1 mm (nerve stretch). Increasing disc height directly stretched the L5 nerve. However, given a larger disc height, the strain on the nerve per increment of reduction was less than for the smaller height. CONCLUSION: The findings suggest that the risk of stretch injury to the L5 nerve with reduction of a high-grade spondylolisthesis is not linear; with 71% of the total L5 nerve strain occurring during the second half of reduction, partial reduction may be a significantly safer treatment approach for high-grade spondylolisthesis than complete reduction. Correction of lumbosacral kyphosis in high-grade spondylolisthesis may be protective of the L5 nerve.

Deep vein thrombosis after major reconstructive spinal surgery.

STUDY DESIGN: A prospective study was performed. OBJECTIVES: The goals of the study were to determine the incidence of deep vein thrombosis after major adult spinal surgery and the optimal mode of prophylaxis in this surgical population. SUMMARY OF BACKGROUND DATA: Few studies have evaluated deep vein thrombosis incidence and prophylaxis after major adult spinal surgery. Incidence rates have ranged from 0.9-14%. METHODS: Three hundred twenty-nine patients were evaluated. One hundred ten patients were randomized to 3 different deep vein thrombosis prophylaxis groups. These patients had duplex doppler scans between the fifth and seventh postoperative days. The remaining 219 patients formed a nonrandomized group and received either thrombosis embolic deterrent stockings alone or thrombosis embolic deterrent stockings and pneumatic compression boots for deep vein thrombosis prophylaxis. The type of deep vein thrombosis prophylaxis in this group was based on surgeon preference. All 329 patients were followed for clinical signs and symptoms of thromboembolic disease. Patients were followed clinically for a minimum of 1 year. RESULTS: All 110 prophylaxis study group patients were clinically asymptomatic and 109 duplex scans were normal. One scan was indeterminate and a follow-up venogram was negative. Two patients in the coumadin group (5.7%) experienced excessive blood loss. One of the 219 patients from the nonrandomized group developed a clinically detectable proximal deep vein thrombosis which was confirmed by duplex ultra-sonography. The overall clinical incidence of deep vein thrombosis was 0.3% (1 in 329 patients). CONCLUSIONS: This low 0.3% rate is in agreement with recent studies that focus on thromboembolic disease. Given the low incidence, routine screening for asymptomatic thrombi appears unwarranted. In addition, mechanical prophylaxis with graduated compression stockings and pneumatic compression boots is preferable to anticoagulation therapy.

The relationship between degenerative changes and osteoporosis in the lumbar spine.

Degenerative changes in the spine, specifically disc degeneration and facet arthrosis, and osteoporosis are conditions that primarily affect the elderly and may significantly impact the quality of life. The relationship between osteoporosis and degenerative changes in the hip joint has been studied, but their correlation in the spine is not entirely clear. Two hundred ninety-four subjects older than 50 years of age were retrospectively studied for the existence of lumbar spinal degeneration and osteoporosis through radiologic examination for 3 clinical manifestations: (1) disc degeneration, (2) facet joint arthrosis, and (3) lumbar osteoporosis. Peripheral osteoporosis in the distal radius of the nondominant hand was measured using a single-photon bone absorptiometer. Results indicated that subjects with severe osteoporosis in the distal radius also had severe degenerative changes in the discs and the facets; those with mild osteoporosis in the distal radius showed a tendency to have a lesser degree of degenerative changes than the subjects without osteoporosis.