Biomedical subjects

C Knop

Publications and source records attributed to C Knop.

42 records · Page 3Linked to original sources

PubMed1997

[Fractures of the thoracolumbar spine. Late results of dorsal instrumentation and its consequences].

Between January 1989 and July 1992, 76 patients with thoracolumbar fractures were operatively treated at the Department of Trauma Surgery, Hannover Medical School. After a mean of more than 3 years, 56 of 62 patients (90%) still alive who had their implants removed were examined. According to the ASIF classification 33 patients sustained type A fractures, 13 type B and 10 type C. Three patients with incomplete paraplegia returned to normal; in one case of complete paraplegia no change occurred. In 40 cases the dorsal instrumentation was combined with transpedicular cancellous bone grafting. The mean operative time totaled 3 h. In this series, two complications (3.6%) were observed: one iatrogenic vertebral arch fracture without consequences and one deep infection. Compared to the preoperative status, our follow-up examinations demonstrated permanent physical and social sequelae; the percentage of individuals able to do physical labor was reduced by half (22 to 11 patients) whereas the share of unemployed or retired patients doubled (4 to 8 patients). At the time of follow-up examination only 21 of 42 patients continued in sports. The assessment of complaints and functional outcome with the "Hannover Spinal Trauma Score" reflected a significant difference (P < 0.001) between the status before injury (96.6/100 points) and at the time of follow-up (71.4/100 points). The radiographic assessment in the lateral plane (Cobb technique) demonstrated a significant (P < 0.001) mean restoration from an initial angle of -15.6 degrees (kyphosis) to +0.4 degree (lordosis). Serial postoperative radiographic follow-up showed progressive loss of correction; at follow-up examination we found a mean of 10.1 degrees (P < 0.001). Compared to the preoperative deformity a mean improvement of 6.1 degrees to an average of -9.7 degrees at follow-up examination was noted. The addition of transpedicular cancellous bone grafting did not decrease the loss of correction. CT scans after implant removal were performed in 9 cases: only 3 of 9 patients showed evidence of intervertebral fusion. No correlation could be found between ASIF classification and radiographic outcome. However, the preoperative wedge angle of the vertebral body correlated significantly with the postoperative loss of reduction. Due to disappointing results after dorsal stabilization with transpedicular cancellous bone grafting we recommend a combined procedure with dorsal stabilization and ventral fusion in cases of complete or incomplete burst injury of the vertebral body.

Adolescent↗

PubMed1997

[New developments in surgery of the injured spine].

There are many new options, and those procedures that are interesting from the aspect of traumatology have been selected: (1) A special positioning aid for the treatment of injuries to the cervical spine. The appliance has proved extremely useful for reduction and immobilization of fractures and dislocations and also allows reliable positioning of the head in all desired surgical positions when ventral and/or dorsal approaches are used. (2) A new titanium H-plate, which can be fixed either with the usual 3.5-mm-thick screws or with unconventional 4.5-mm-thick screws in the case of lesions to the lower cervical spine. (3) A new technique for less invasive atlanto-axial screw fixation, with a cannula system extending to the axis from small incisions at the level of the upper thoracic spine, by way of which the C-1 joint block can be drilled, milled and screwed. (4) Jeanneret's CerviFix rod system. This system has progressed beyond the drawbacks of plating as performed so far for internal fixation of the dorsal cervical spine, in which screws could be inserted only at predetermined intervals and angles. Movable grips, lateral stabilizers and extension pieces mean that the system is very well able to fulfil the demands of a variable and stable implant. (5) Transthoracic endoscopic spinal surgery, which is excellently suited to fusion of a traumatized segment to supplement reduction and instrumentation from a dorsal approach. (6) A reduced-invasion method at the thoracolumbar transition, with no insertion of implants from a ventral approach and blocking through a small left lateral thoracotomy with autogeneic shavings from the iliac crest.

Endoscopes↗

PubMed1996

[Long-term outcome of 57 patients after ventral interbody spondylodesis of the lower cervical spine].

In this retrospective study we present the long-term results in 89 patients who underwent anterior interbody fusion of acute cervical spine injuries in our institution between 1972 and 1983. There were 23 dislocations, 50 fracture-dislocations and 16 burst fractures without significant posterior lesions. Only 20 patients showed no neurologic symptoms. In all 79 patients who were treated initially in our trauma department, closed reduction was performed as soon as possible. No aggravation of the neurologic conditions by this manoeuvre was observed. The mean time between injury and operation was 7 days (range 0-110 days). In 79 patients an H-plate or one-third-tubular plate was used, and in 10 patients fusion was performed only by bone grafting according to the technique of Robinson [40]. Severe complications, i.e. persistent instability with kyphosis or sagittal dislocation, were found in only 2 of these 10 patients secondary to technical problems. The radiologic results demonstrated a high fusion rate, with fusion in 78 out of the 79 patients. Of the 79 patients treated with plate spondylodeses, 7 devices had to be removed without loss of correction: 6 owing to loosening and 1 to breakage of the plate. Only in one additional case after early hardware removal because of loosening was a loss of correction detected. Of the original 89 patients, 17 had died of causes unrelated to the operation. The mean age of the surviving 72 patients at the time of injury was 36 years (14-83 years). A further 15 patients were lost during follow-up, so that 57 (79%) could be included in the study with a mean follow-up of 11 years, 9 months (10-19 years). The functional results were as follows: Active range of motion was limited between 25 and 50%. 40 patients had no pain at rest, 38 only during motion without need for treatment. A significant correlation between pain and fused segments could not be found. Spontaneous fusion and spondylophytes in adjacent motion segments were seen in 27 patients, again without significant correlation to residual pain. No hypermobility of adjacent motion segments in functional X-rays was seen. 46 patients returned to their former work, 7 were not able to work again secondary to the injury, 4 patients received old-age pension. Improvement of the neurologic deficits in the 37 symptomatic patients was observed in 30 cases (81.1%) according to the "Sunnybrook Cord Injury Scale" [49]; according to the ASIA Neurological Impairment Scale [5] 25 (67.6%) of them improved of at least 1 degree. No correlation could be found between the interval injury to operation and neurologic improvement. With regard to the early stage of the procedure of anterior interbody fusion for traumatic lesions this study shows promising data with high fusion rates and low morbidity, especially for the combination with plate fixation. Further improved within the last 12 years this method offers an excellent alternative for operative treatment of most acute lower cervical spine injuries. Using devices which are not angle stable, special attention should be given to precise bicortical screw fixation.

Adolescent↗

PubMed1995

Development of PCR for screening of enteroaggregative Escherichia coli.

In this study, we determined the sequence of the EcoRI-PstI fragment of the plasmid pCVD432, also termed the enteroaggregative Escherichia coli (EAggEC) probe. A primer pair complementary to this probe was designed for PCR amplification of a 630-bp region. Comparison of the analysis of the EAggEC probe sequence with those in database libraries revealed no significant similarity to any known bacterial gene. Pure cultures of E. coli cells, as well as mixed cultures from stool specimens, were investigated with the PCR assay, the EAggEC probe test, and the adherence test. Of 50 E. coli strains which demonstrated aggregative adherence to HEp-2 cells, 43 (86%) were positive with the EAggEC PCR. All 43 of these strains reacted with the EAggEC probe. Six EAggEC strains gave negative results by both molecular techniques. In contrast, only 4 of 418 (0.96%) strains representing other categories of diarrheagenic E. coli demonstrated a positive PCR result. The PCR was also successful in screening for the presence of EAggEC in enriched cultures grown from stool specimens. Compared with cell culture assays and colony hybridization, our findings revealed that the PCR assay was more rapid, simple, and highly sensitive and can therefore be recommended as a screening method for EAggEC in the clinical laboratory.

Adolescent↗

PubMed1994

[Function of the supraspinatus muscle in a dynamic shoulder model].

Active glenohumeral joint motion was simulated in ten cadaveric shoulder specimens with hydrodynamic cylinder forces at the deltoid muscle and at the rotator cuff. Computerized regulation initiated standardized cycles of glenohumeral joint motion in which the isolated effect of the supraspinatus muscle could be studied. The effect of the supraspinatus muscle on the elevation of the glenohumeral joint was measured with an ultrasonic sensor system. Pressures underneath the coracoacromial arch as an indicator of the 'impingement' at the shoulder were recorded with capacitive sensors. Elimination of force of the supraspinatus muscle led to a significant 6% decrease in elevation (p < 0.05). The deltoid muscle was able to reverse this loss of elevation by an increase in force equal to only one third the force lost at the supraspinatus muscle. When no force was applied to the supraspinatus muscle average pressures under the coracoacromial vault decreased by 8% (p > 0.05). In conclusion, the supraspinatus muscle produces less torque and more glenohumeral joint compression than the deltoid muscle. However, the supraspinatus muscle has no significant effect on the centering of the humeral head on the glenoid during elevation.

Acromioclavicular Joint↗

PubMedDate not supplied

Surgical options for the treatment of severe tibial pilon fractures: a study of three techniques.

OBJECTIVE: To determine whether long-term results of one of three different management protocols for severe tibial pilon fractures offer advantages over the other two. DESIGN: In a retrospective study, patients were examined clinically and radiologically after internal fixation of severe tibial plafond fractures (i.e., 92 percent Type C fractures according to the AO-ASIF classification). SETTING: Department of Traumatology, Hanover Medical School. Level I trauma center. PATIENTS: Fifty-one of seventy-seven patients treated between 1982 and 1992 were examined clinically and radiologically at an average of sixty-eight months (range 13 to 130 months) after injury. INTERVENTIONS: The patients were treated in three different ways: primary internal fixation with a plate following the AO-ASIF principles (n = 15), which was reserved for patients with closed fractures without severe soft tissue trauma; one-stage minimally invasive osteosynthesis for reconstruction of the articular surface with long-term transarticular external fixation of the ankle for at least four weeks (n = 28); and a two-stage procedure entailing primary reduction and reconstruction of the articular surface with minimally invasive osteosynthesis and short-term transarticular external fixation of the ankle joint followed by secondary medial stabilization with a plate using a technique requiring only limited skin incisions (a reduced invasive technique) (n = 8). MAIN OUTCOME MEASUREMENTS: Objective evaluation criteria were infection rate, amount of posttraumatic arthritis, range of ankle movement, and number of arthrodeses. Subjective criteria were pain, swelling, and restriction of work or leisure activities. RESULTS: Because only closed fractures were treated by primary internal fixation with a plate, there was a statistically significant difference (p < 0.005) in the distribution of open fractures between the three treatment groups. Fracture classification in these groups were not significantly different. All but four fractures were classified as Type C lesions according to the AO-ASIF system. The soft tissue was closed in 63 percent (n = 32) and open in 37 percent (n = 19). No significant relationship could be found between the soft tissue damage and degree of arthritis or between the type of surgical treatment and extent of posttraumatic arthritis. However, none of the patients who required secondary arthrodesis (23 percent of all cases) were in the group who had undergone two-step surgery (p < 0.05). The range of ankle movement was much greater in the two-step group than in the others; these patients also had less pain, more frequently continued working in their previous profession, and had fewer limitations in their leisure activities. These differences did not reach statistical significance. The incidence of wound infection did not differ significantly among the three groups. CONCLUSIONS: On the basis of our results, we now prefer a two-step procedure for the treatment of severe tibial pilon fractures with extensive soft tissue damage. In the first stage, primary reduction and internal fixation of the articular surface is performed using stab incisions, screws, and K-wires. Temporary external fixation is applied across the ankle joint. After recovery of the soft tissues, the second stage entails internal fixation with a medial plate using a reduced invasive technique.

Adolescent↗