Rapid cortical motor output map changes assessed by the triple stimulation technique.

The amplitudes of motor evoked potentials (MEPs) were mapped by transcranial magnetic stimulation (TMS) using the triple stimulation technique (TST) in 11 normal individuals. Stimuli were given while the subjects were (a) distracted, (b) concentrating on their target (recorded) hand, and (c) concentrating on their contralateral hand. Within seconds, the proportion of excited motor units increased, similarly in all subjects, by an average of 70% from (a) to (b), and by 48% from (a) to (c). At the optimal stimulation site, results obtained with the TST were compared to those of conventional MEPs. The TST proved superior in detecting the rapid changes of the motor output caused by the non-specific mental tasks studied.

Interbody cage stabilisation in the lumbar spine: biomechanical evaluation of cage design, posterior instrumentation and bone density.

We performed a biomechanical study on human cadaver spines to determine the effect of three different interbody cage designs, with and without posterior instrumentation, on the three-dimensional flexibility of the spine. Six lumbar functional spinal units for each cage type were subjected to multidirectional flexibility testing in four different configurations: intact, with interbody cages from a posterior approach, with additional posterior instrumentation, and with cross-bracing. The tests involved the application of flexion and extension, bilateral axial rotation and bilateral lateral bending pure moments. The relative movements between the vertebrae were recorded by an optoelectronic camera system. We found no significant difference in the stabilising potential of the three cage designs. The cages used alone significantly decreased the intervertebral movement in flexion and lateral bending, but no stabilisation was achieved in either extension or axial rotation. For all types of cage, the greatest stabilisation in flexion and extension and lateral bending was achieved by the addition of posterior transpedicular instrumentation. The addition of cross-bracing to the posterior instrumentation had a stabilising effect on axial rotation. The bone density of the adjacent vertebral bodies was a significant factor for stabilisation in flexion and extension and in lateral bending.

[Differential surgical therapy of popliteal entrapment syndrome 1967 to 1992]. / Chirurgische Differentialtherapie des poplitealen Entrapment-Syndroms von 1967 bis 1992.

From 1967 to 1992 at the University Hospital of Zurich 16 patients (14 male, 2 female) with 22 popliteal artery entrapment syndromes underwent a surgical treatment. In this period several different operation procedures were used. The modern operative procedure depends on the degree of the arteries wall compression. The procedure of choice for minimal compression of arterial wall is a musculo-tendinous decompression with a medial replacement of the popliteal artery. In the cases of severe compression we used autologous venous bypass from femoropopliteal I to popliteal III.

Endoscopic carpal tunnel release--current status.

Endoscopic carpal tunnel release is one of the most controversial topics in hand surgery today. Many surgeons have reservations in doing carpal tunnel release endoscopically because its merits and demerits have not been clearly defined. This article describes the various techniques now available to perform endoscopic carpal tunnel release. The anatomic basis for a single-portal technique using the Concept Carpal Tunnel Release Kit is described in detail. The results of 100 postoperative cases indicate that endoscopic carpal tunnel release was superior to the open technique in regard to postoperative morbidity and patient satisfaction in 92% of this patient group.

[Arterial popliteal entrapment syndrome as the cause of acute peripheral ischemia]. / Die Problematik des arteriellen poplitealen Entrapmentsyndroms als Ursache der akuten peripheren Ischämie.

The popliteal artery entrapment syndrome results from an abnormal relation of artery and tendomuscular structures in the popliteal fossa, which can compromise the artery. We report our experience in 18 cases of popliteal artery entrapment syndrome in 14 patients (12 men, 2 women) operated on at the University Hospital in Zurich during the period 1967-1988. A follow-up examination was possible in 12 of the 14 patients in whom popliteal artery entrapment syndrome (both legs in 2) was treated surgically. These patients had first presented with ischaemic symptoms at an average age of 30 years. The correct diagnosis of an entrapment syndrome was made at an average age of 36 years. In all, 5 of the 14 patients were affected bilaterally. In 5 cases the first sign was an acute ischaemic syndrome. All these patients were young and had formerly taken active part in sport. The follow-up examination after an average age of 11.25 years showed a very good result in 13 cases, a good result in 2 cases and an unsatisfactory postoperative result in 1.

[Aseptic meningitis in pediatrics]. / Aseptische Meningitiden in der Pädiatrie.

We analyzed the 259 pediatric patients (69% males, 31% females) treated for aseptic meningitis at the Department of Pediatrics (Inselspital), University of Berne, Switzerland, during the 10-year period from 1978 to 1987. 79% were in- and 21% outpatients. The main study purpose was the evaluation of clinical presentation, diagnostic workup, course and prognosis of this disease entity. The clinical characteristics (fever, meningitic signs, headache, nausea and vomiting, and usually normal consciousness) were not discriminative for differential diagnosis. On the other hand, pleocytosis in cerebrospinal fluid averaged 406 x 10(6) cells/l (57% mononuclear cells) at first lumbar puncture, and 6 to 12 hours later showed both slight decrease of total cell count and clear shift to mononuclear cells (71%). The course of the disease was always short and benign. Complications, usually of a neurologic nature, occurred in only 10% and all were mild and reversible. Nevertheless, follow-up interview by phone identified 21% of patients with transient post-meningitic disorders, especially prolonged episodes of stress-induced headache. However, except for one case of chronic hydrocephalus, there were no severe or persistent sequelae. Neither complications nor sequelae correlated with patient age or laboratory findings. Our results confirm that aseptic meningitis in children is relatively benign, and underline the importance of rest and relaxation during convalescence. Rapid, reliable and cheap viral diagnostic tests in the cerebrospinal fluid could simplify the management of the individual patient with regard to repeated lumbar punctures (in 36%), surveillance in the hospital (in 79%), and antibiotic therapy (in 25%).

[Ventral direct screw fixation in dens fractures]. / Die ventrale direkte Verschraubung bei Densfrakturen.

Direct anterior screw fixation of odontoid fractures is indicated in type II and occasionally type III fractures according to the Anderson and d'Alonzo classification. This fracture treatment follows the generally accepted concepts of surgical treatment of limb fractures. It is direct osteosynthesis of a fracture by screw fixation with interfragmentary compression and differs fundamentally from all other treatment methods in spinal fractures, where the treatment is combined with fusion and definite immobilization of a motion segment. The iatrogenic trauma is minimal by using an anterior surgical approach and no supplemental bone grafting is required. The postoperative care is very simple, and the fusionless fracture fixation has a better functional outcome. With the introduction of cannulated screws, which can be inserted over K-wires, the surgical procedure has been further simplified and minimizes the peroperative risks. After initial complications in the first series of 17 patients, the most recent 15 cases were without complications. This stresses the fact that this surgical procedure should only be done by spine surgeons who are familiar with the upper cervical spine and osteosynthesis techniques.

Direct anterior fixation of dens fractures with a cannulated screw system.

Anterior screw fixation of dens fractures appears to be an optimal method of treatment for these injuries. Anatomic dens fracture reduction with stable internal screw fixation satisfies the established principles of the AO/ASIF. Iatrogenic trauma is minimized by the use of an anterior surgical approach, and no supplemental bone grafting is required. This procedure is quite prone to complications when performed improperly or in contraindicated situations. The use of meticulous surgical technique along with a newly designed cannulated screw system has evolved this procedure into an established form of treatment at our department. Since 1982, 23 patients were treated with direct screw fixation of dens fractures. The overall rate of fracture union was 92.3%, and fracture resolution averaged 5.5 months. The major complication rate of 17% (4/23) resulted from inappropriate use of this technique. The 11 most recent cases, all of which involved stabilization with cannulated screws, resulted in only a single complication (9%) and an average fracture healing time of 3.5 months. A recommended operative technique for anterior screw fixation of dens fractures will be presented along with a discussion of potential sources of difficulty or failures.

Long-term results of tibial plafond fractures treated with open reduction and internal fixation.

In this study a series of 41 consecutive cases of operatively treated fractures of the tibial plafond was retrospectively analysed. The fractures were classified into types I (9.75%), II (41.5%) and III (48.75%) as defined by Rüedi. The 10-year average follow-up revealed 66% good and 24% fair objective results overall. The recent literature uniformly reports good results in operatively treated type-I and -II fractures. In this series, these essentially low-velocity injuries resulted in a satisfactory outcome in 86% of cases. Controversy exists in reports of operative treatment of type-III fractures. The incidence of satisfactory results in the present series in type-III fractures was 95% good and fair results, which appears to be better than in other authors' experience. This can be partially explained by the relatively few high-velocity injuries (50% of the type-III fractures) and also by certain technical procedures used in surgery to stabilise these fractures. The initial type of fracture and articular cartilage damage are directly related to late arthrosis. There is clear evidence that the quality of reduction correlates with later development of arthrosis. However, anatomical reduction may still be followed by significant joint arthrosis because of articular cartilage damage. Severe arthrosis present at late follow-up did not correlate with poor subjective or objective results. With adequate open reduction and internal fixation, satisfactory results can be obtained in severe tibial plafond fractures. Meticulous soft tissue care and handling at surgery are important. Various fixation devices may need to be incorporated to ensure optimal soft tissue status for fracture healing.

Fractures of the odontoid process. Treatment with anterior screw fixation.

Seventeen cases of Anderson and D'Alonzo Type II and "shallow" Type III fractures of the odontoid, treated by anterior screw fixation, were reviewed and compared with previously published series of fractures treated nonoperatively, treated with posterior C1-C2 arthrodeses, and with anterior screw fixation series. Although the nonunion rate (12%) and major complication rate (24%) in the present series were higher than those previously reported, the combined rates of all anterior screw fixation series were comparable to those of posterior C1-C2 arthrodesis studies. Three of the complications presented occurred in cases that in retrospect were inappropriate for the use of this technique. These included a verified nonunion and 2 individuals with markedly osteoporotic bone and unfavorable fracture type. Because of the difficulty involved in mastering anterior screw fixation of the dens, its use should be limited to experienced spine surgeons with the appropriate surgical facilities.

[Bone screw osteosynthesis of dens fractures. Technical surgical aspects and results]. / Die Schraubenosteosynthese von Densfrakturen. Operationstechnische Aspekte und Ergebnisse.

Twenty cases of Anderson and d'Alonzo type II and "shallow" type III fractures of the dens were treated by anterior screw fixation: the results were reviewed and compared with previously published results obtained in series of such fractures treated non-surgically, by posterior C1-C2 arthrodesis or anterior screw fixation. The complication rate of 25% in our series is comparable to those reported in a previously published review of studies on posterior wiring for C1-C2 arthrodesis. Three of our cases in which complications occurred (15%) were recognized in retrospect as inappropriate for the use of this technique: in one of these patients there was confirmed non-union, and the other two had markedly osteoporotic bone. A meticulous operative technique and the use of special instruments may improve the success rate. The anterior screw fixation method, however, allows for maximal post-treatment cervical motion, since it makes arthrodesis unnecessary and minimizes the degree and duration of postoperative external immobilization. It also reduces the iatrogenic trauma since an anterior rather than a posterior cervical approach is taken and supplementary bone grafting is not required. Anterior screw fixation of type II dens fractures appears to be the ideal method of treatment for these injuries, but since it is difficult to perform its use should be limited only to experienced spine surgeons with access to the appropriate surgical facilities.

The internal skeletal fixation system. A new treatment of thoracolumbar fractures and other spinal disorders.

A new internal skeletal fixation system (ISFS) for stabilizing thoracolumbar fractures and other spinal disorders was developed by Dick in Switzerland. The ISFS is a modification of the Magerl external skeletal fixation system of the spine. The Dick modification consists of a threaded rod connected by clamps to Schanz screws and is located in the vertebral pedicles on both sides of the spine. Due to a stable angle between the rod and Schanz screw, a one-point fixation above and below the diseased vertebra is sufficient. The ISFS provides a short fixation and promotes fusion. Control of lordosis, kyphosis, and rotation of the spine is possible with threaded rod distraction and compression and through manipulation of the Schanz screws held by movable clamps. The advantage of the ISFS is the ability to achieve reduction and fixation with the same instrumentation. ISFS has been used in more than 90 patients and proven most adequate for thoracolumbar fractures and other localized spinal disorders. The Harrington system and its modifications are no longer in use for these problems.

Stabilization of the lower thoracic and lumbar spine with the internal spinal skeletal fixation system. Indications, techniques, and first results of treatment.

Since 1984, 30 patients with burst fractures of the lower thoracic and lumbar spine were treated with AO internal spinal skeletal fixation system. All patients in this series had a minimum follow-up of 12 months. This new instrumentation is a posterior intrapedicular system developed by Dick in 1982. It allows stable fixation that is limited only to adjacent spinal segments. The internal fixator permits reduction in all three planes. Independently, it is possible to add distraction or compression to the involved segments. It also is able to reduce effectively the "middle column" which is thought to be accomplished by "ligamentotaxis." In this series there were 16 neurologically intact patients and 14 with partial or complete neurologic injury. There were two minor instrumentation loosenings early in the series. Most patients in this series had a near-anatomic reduction of all three columns in the involved segment. It was also possible to re-establish the normal lordosis of the lumbar spine. The device provided sufficient rigid fixation for rapid postoperative mobilization in a light external orthosis.

Treatment by external fixation of open fractures associated with severe soft tissue damage of the leg. Biomechanical principles and clinical experience.

External fixation is the treatment of choice for fractures of the leg involving severe damage to the soft tissue. Each of the various patterns of application has advantages and disadvantages. Based on various biomechanical studies and clinical experience, the authors use a right-angle arrangement for the screws. If the type of fracture permits, internal and external fixation may significantly increase stability. During the period from 1978 to 1980, 56 patients with second- and third-degree open fractures were treated. A combination of external and internal fixation was used in 42 patients. Of the 44 patients re-evaluated at follow-up examinations, 19 had returned to unrestricted weight-bearing within 19.8 weeks. If no signs of bony union are noted ten to 12 weeks after the initial operation, cancellous bone grafting and internal fixation instead of external fixation are indicated. Twenty-three patients were fully weight-bearing an average of 14 weeks after internal fixation and cancellous bone grafting. Two patients had difficult problems and did not return to full weight-bearing until about 45 weeks after operation.

[Load stability in relation to the osteosynthesis method, course and complications in open lower-leg fractures with severe soft tissue lesions ]. / Belastungsstabilität in Abhängigkeit von Osteosyntheseverfahren, Verlauf und Komplikationen bei offenen Unterschenkelfrakturen mit schwerem Weichteilschaden.

The external fixator ("fixateur externe") is today's method of choice in the treatment of lower leg fractures with severe damage to the soft parts. The various application techniques and angles of application of this device entail varying stability and are characterized by certain advantages and drawbacks. Basing on detailed biomechanical studies and experience with patients, the authors prefer the rectangular mode of application using Schanz screws. If the type of fracture allows, a combination of minimal osteosynthesis and external tensor is used; this can significantly enhance the stability. In 42 patients of a total of 56 during 1978-1980 with second-grade and third-grade open fractures of lower leg, combination with minimal osteosynthesis was effected (traction screw). Of 44 patients followed up, 19 achieved stability to load within an average period of 19.8 weeks. If there is no osseous bridging 10-12 weeks after initial treatment, additional measures such as spongiosaplasty and changeover to stable inner fixation with plates become necessary. Following plate osteosynthesis with additional spongiosaplasty, full load was permissible on the average 14 weeks after this procedure in 23 patients. The course was more complicated in the case of the 2 remaining patients; it took up to 45 weeks until full load became permissible.