Biomedical subjects

V Vécsei

Publications and source records attributed to V Vécsei.

At least 55 records · Page 3Linked to original sources

PubMed1999

Fatigue strength of locking screws and prototypes used in small-diameter tibial nails: a biomechanical study.

BACKGROUND: One major problem with the use of small-diameter nails in the treatment of tibial fractures is the high rate of fatigue fractures of the locking screws. The objective of this study was to correlate such parameters as diameter of locking screws, influence of notch effect, and material with fatigue strength and fatigue limit. METHODS: In a biomechanical study, the mechanical properties of 11 different locking screws and screw designs to be used in solid tibial nails were tested under typical fatigue conditions. RESULTS: The results showed that an increase in the screw's diameter significantly increased the fatigue strength of the tested locking screws and prototypes (p < 0.0005). A 20% increase of diameter improved fatigue strength by 25 to 70%. Absence of thread at the location where the screw contacts the nail's aperture (where the main load is transmitted to the screw and where the screw, therefore, usually tends to break) may double the fatigue strength and fatigue limit by avoiding the negative notch effect of the screw's thread. It was further significant that titanium alloys had a higher fatigue strength compared with stainless steel alloys (p < 0.001). However, the fatigue strength of titanium implants is massively reduced by minimal damage to the surface. CONCLUSION: Optimizing the core diameter of the locking screws at the aperture of the solid tibial nail by using screws without a continuous thread generates a fatigue strength two to three times higher compared with screws with a continuous thread. Increasing fatigue strength of locking screws might decrease malunion in fractures stabilized by small-diameter nails.

Biomechanical Phenomena↗

PubMed1999

Recommendations for the diagnosis of traumatic meniscal injuries in athletes.

It has always been difficult to develop a method of correctly evaluating knee injuries and, in turn, to devise the appropriate rehabilitation programme. Flawless diagnosis of meniscal injury is necessary, considering the diverse consequences of this injury for patients, and even more so in relation to athletes, bearing in mind the intensified physical demands on their bodies. There is no doubt that an accurate and concise clinical evaluation of patients with injuries to the knee is the basis for an exact diagnosis and successful treatment. The use of noninvasive methods, such as magnetic resonance imaging, in addition to clinical evaluation is recommended because of their high accuracy and negative predictive value. The use of invasive methods, such as arthroscopic operations, should be restricted to treatment, and not be used for diagnosis.

Adolescent↗

PubMed1998

[Concomitant intra-abdominal injuries in pelvic trauma].

A pelvic fracture combined with abdominal injury and soft tissue damage, defined as complex pelvic trauma, is an expression of severe trauma and requires specific procedures in terms of diagnosis and treatment. The clinical course and outcome of 75 patients (56 males and 19 females) with complex pelvic injuries from 1985 to 1996 are presented in this follow-up study. There were 33 (44%) Type A (stable pelvic ring fracture), 10 (13%) Type B (rotationally unstable pelvic ring fracture) and 32 (43%) Type C (rotationally and vertically unstable pelvic ring fracture). Concomitant abdominal injuries included: 14 liver lacerations (19%), 28 splenic lesions (37%), 7 ruptures of the kidney (9%), 18 ruptures of the bladder (24%), 13 urethra lesions (17%), 13 intestinal lesions (17%) and 16 ruptures of the diaphragm (21%). The mean Hannover polytrauma score was 22 points. Twelve patients (16%) died within 6 hours after associated head and/or chest injury with hemorrhage, and 3 patients (4%) died in the intensive care unit from sepsis and multiorgan failure within 2 weeks after injury. The priority of the steps taken is of utmost importance in the diagnosis and treatment of such injuries. Immediate control of hemorrhage by surgical or minimally invasive radiological techniques, stabilization of pelvic fractures and inter-disciplinary cooperation are important requirements for management and successful treatment.

Abdominal Injuries↗

PubMed1998

[Prospective comparison of MRI vs. direct magnification radiography in occult fractures of the scaphoid bone].

The diagnosis of occult fractures of the scaphoid bone is even more challenging than that of conventional fractures of the scaphoid. This study aimed to compare prospectively the gold standard method (plain radiographs in four projections, after about 14 days) and the primary findings with direct magnification radiography (DIMA) and magnetic resonance imaging (MRI). Primary MRI showed much higher diagnostic power than plain radiography at 10-14 days in occult scaphoid fractures and in detection of associated carpal injuries. This may lead to a decreasing time of disease. DIMA was inferior in detecting occult fractures of the scaphoid.

Adolescent↗

PubMed1998

[Periprosthetic femur shaft fracture. Indications and outcome in 51 patients].

Periprosthetic femoral fractures present the problem of fracture treatment and prosthetic stability. Various treatment options are recommended for managing these fractures. We treated 51 patients with 54 periprosthetic fractures between 1985 and 1995. Of these, 42 (78%) fractures were treated with a plate, eight (14%), with a revision prosthesis, two (4%), with retrograde nailing, and two (4%), conservatively due to poor medical condition. The choice of fracture management was dependent on the type and location of the fracture and on the stability of the prosthesis. A total of 50 fractures healed primarily. Complications included three cases of plate loosening, one further fracture, one deep infection, one broken bolt and one varus deformity. Four patients died in the postoperative period, an additional 19 were dead at the time of the evaluation. Fractures with a stable implant can be treated with plate fixation. Cases of a loose implant require revision. Distal fractures are stabilized with a plate or with a retrograde nail.

Aged↗

PubMed1998

Twisting of patellar tendon grafts does not reduce their mechanical properties.

The purpose of this study was to investigate whether the twisting of a patellar tendon (PT) graft improves or reduces its mechanical properties. Twenty-seven pairs of 10 mm cadaveric PT grafts were tested at a strain rate of 10% min(-1). For each pair, the left specimen served as an unmanipulated control while the right specimen was either left untwisted, twisted + 90 degrees, or twisted - 90 degrees. All avulsion failures were excluded from the data analysis, focusing only on pure in-substance tendon ruptures. Higher ultimate load values than previously reported were obtained for both the twisted and untwisted specimens, without a statistical significant difference between the two. The values obtained for the left and right specimens from Group A were 4014+/-319 and 3973+/-245 N, from Group B 3613+/-207 and 3891+/-14 N, and from Group C 3997+/-278 and 4415+/-507 N, respectively. Stiffness and failure strain were not influenced by the twisting. Neither the presence of a twist, nor the direction of the twist were found to increase the ultimate load of the 10 mm cadaveric patellar tendon graft. Therefore, recommendation for twisting cannot be assessed to its mechanical properties.

Adult↗

PubMed1998

Shortening of the patellar tendon after anterior cruciate ligament reconstruction.

In this prospective study, patellar height changes were investigated after anterior cruciate ligament (ACL) reconstruction with a mean follow-up of 22.4 months. A total of 114 patients were included. Fifty-two patients (group A) were treated by multiple suture repair, 27 patients (group B) underwent acute ACL reconstruction, and 35 patients (group C) underwent ACL reconstruction > or =6 weeks after injury with a patellar tendon graft. The patellar vertical height ratios (VHR) were evaluated preoperatively (VHR 1), 6 months postoperatively (VHR 2), and at follow-up (VHR 3). For the studied questions, the following answers were obtained: (1) The change of the patella height was the same in all three groups (i.e., disregarding the different surgical procedures). (2) The time elapsed between injury and ACL reconstruction did not influence the shortening of the patellar tendon. (3) Women showed a more pronounced shortening of the patellar tendon than did men. (4) A significant shortening of the patellar tendon occurred in 30% of our patients, and the process of shortening was finished 6 months postoperatively. (5) Anterior knee pain was present in 27.2% of our patients and occurred significantly more often after patellar tendon graftings. (6) Age had no influence on the changes of the patellar height.

Adult↗

PubMed1998

External fixation of lower limb fractures in children.

26 children with 29 lower limb fractures, between the age of 2 and 15 years, were treated with an external fixator. The average time to union and removal of the fixator was 71 days for femoral and 73 days for tibial fractures. Complications included pin problems in nine cases, two devices had to be replaced with a cast and one refracture. Leg length discrepancies were noted in five children and radiological malalignment in three. We recommend external fixation for all femoral shaft fractures and all open or dislocated tibial and tibia and fibula fractures beginning at the age of three to adolescence.

Child↗

PubMed1998

Patients with increased intracranial pressure cannot be monitored using near infrared spectroscopy.

The hypothesis of this study was that with near infrared spectroscopy a decrease of the regional cerebral saturation would be detectable in patients with increased intracranial pressure. For this purpose, two study groups were compared: (A) eight healthy volunteers and (B) eight heart beating organ donors with brain stem herniation. The regional cerebral saturation was measured according to the developer's suggestions. Mean arterial pressure and peripheral pulse oximetry were recorded. The statistical comparison, using the unpaired t-test, revealed no significant differences for the regional cerebral saturation (p = 0.97) or for the mean arterial pressure or peripheral pulse oximetry between the groups. In both of the studied situations, no differences in the regional cerebral situation were detectable, even though the patient situations were completely antagonistic. Therefore, it is reasonable to discourage the use of the INVOS 3100 Cerebral Oxymeter to monitor patients with increased intracranial pressure indirectly.

Adult↗

PubMed1998

Patellar alignment evaluated by MRI.

We analyzed the congruence of the articular cartilage surfaces and the corresponding subchondral bone in the patellar joint. 20 volunteers underwent MRI investigations of the right patellar joint in 20 degree and 45 degree flexion in the axial plane. The sulcus, congruence, and lateral patellofemoral angles, measured on MRI slices centered through the midtransverse patella, were recorded. In 20 degree and 45 degree knee flexion, the bony sulcus and lateral patellofemoral angles were significantly different from the respective cartilagineous angle. We conclude that 1) measurement of the bony sulcus and lateral patellofemoral angles does not allow conclusions about the articular cartilage surface and its thickness, 2) the bony congruence angle corresponds well to the articular cartilage surface as an indicator of patellar centralization.

Anthropometry↗

PubMed1998

Limited diagnostic value of macroradiography in suspected scaphoid fractures.

In a prospective study 60, patients having suspected occult scaphoid fractures, but with normal conventional scaphoid radiographs, also underwent macroradiography. Clinical and conventional radiographic follow-up examinations and MRI identified 8 occult scaphoid fractures and 23 nonscaphoid lesions. Macroradiography identified only 50% of the occult scaphoid fractures.

Adolescent↗

PubMed1998

Unreamed nailing of tibial fractures with the solid tibial nail.

In 1993 a solid 7.5-mm tibial nail was developed and is composed of a wrought stainless steel alloy. In a preclinical testing series its static and dynamic mechanical properties proved to be superior to other small diameter nails. The clinical application of the Solid Tibial Nail in 70 cases of acute tibial diaphyseal fractures showed promising results. Neither severe intraoperative complications nor infections were observed. The entire series, including seven Grade I, eight Grade II, four Grade IIIA, and nine Grade IIIB open fractures, revealed a union rate of 95% at 6 months postoperative. After dynamization in one case and reaming and renailing in three cases, the fractures with delayed healing progressed to union within the following 3 months. There was no need for bone grafting in any of the cases. Locking screw breakage was observed in 10 (14%) cases 8 to 24 weeks postoperatively. This did not lead to any additional complications. No nail failures were observed. The excellent results of unreamed nailing with the Solid Tibial Nail consequently led to its use as the primary method of treatment for tibial fractures associated with soft tissue injury at the authors' institution.

Adolescent↗

PubMed1998

[Diagnostic reliability of 0.2 Tesla dedicated MRI low-field strength equipment in traumatology].

Anatomical dedicated low-field-strength MR imaging (non-whole-body-systems) has been developed for examinations of the peripheral joints. It has several advantages compared to high-field-strength MR imaging (whole-body-systems). The dimensions are small, the noise is not as bad as in whole body systems and people do not suffer of claustrophobic attacks. However, our results of a prospective blinded study in 56 patients with three different kinds of peripheral joint injuries demonstrated that the 0.2 T dedicated system showed a significant lower rate of diagnostic accuracy compared to middle and high-field-strength MR imaging and scored with obvious lower image quality ratings.

Adolescent↗

PubMed1998

Femur fractures in patients with hip arthroplasty: indications for revision arthroplasty.

The number of periprosthetic femur fractures has increased due to the increase in the number of patients having total hip arthroplasty. In this study, we define indications for operative treatment in patients with femur fractures after hip arthroplasty. Fifty-three patients with 56 periprosthetic fractures were available for retrospective review of charts, radiographs, and physical examination; 42 fractures were treated with open reduction and internal fixation, 8 had replacement of hip prosthesis, 4 were treated with a retrograde genucephalic nail, and 2 patients were treated conservatively. The choice of treatment depended on the stability of the prosthesis and on the type and location of the fracture. Fifty-two fractures healed primarily. Three patients sustained a refracture, one an additional fracture, and two a deep infection. We recommend treatment with plate fixation for fractures without signs of prosthetic loosening. In fractures with loose implants, revision arthroplasty is required. Distal femoral fractures should be stabilized with a plate or with genucephalic nailing.

Aged↗

PubMed1997

Tibial avulsion fracture of the posterior cruciate ligament: K-wire or screw fixation? A retrospective study of 26 patients.

Although the posterior cruciate ligament (PCL) is not frequently injured, a greater understanding of its role in stabilizing the knee joint, mechanism of injury and treatment has developed. Isolated avulsion injuries constitute only a subgroup of PCL injuries, but nevertheless several operative techniques have been described for the fixation of the avulsed bony fragment. In order to investigate whether K-wire or screw fixation yields better long-term results, we examined 26 patients at an average of 10.5 years after the initial operation. Clinical examination, activity level, radiographic evaluation and instrumented measurements did not reveal any significant differences. All the patients had an excellent functional result. Thus, both K-wire and screw fixation are recommended for bony PCL avulsion injuries.

Adult↗

PubMed1997

Economic considerations for the diagnosis and therapy of meniscal lesions: can magnetic resonance imaging help reduce the expense?

With magnetic resonance imaging (MRI) the surgeon has such an effective diagnostic tool in the diagnosis of a meniscal lesion that the times of diagnostic arthroscopy should be in the past. A total of 823 patients with clinically diagnosed meniscal lesions were divided into two groups: group A, 143 patients underwent MRI and 75 of those arthroscopy; group B, 680 patients, 201 (30%) of whom were operated after being only clinically examined. MRI was done on a Siemens Medical System Magnetom 1.5 Tesla with a 256 x 256 matrix. Spinal echo and gradient echo images were performed with slices of 2 to 4 mm thickness. All meniscal tears were graded according to Reicher and Crues, respectively. Grades III and IV were judged to be positive for a meniscal lesion. Arthroscopy was carried out under general anesthesia and the usual technique. The MRI revealed the following results: Medial meniscus: accuracy 95%, positive predictive value (PPV) 92%, negative predictive value (NPV) 95%, sensitivity 98%, and specificity 82%, lateral meniscus: accuracy 97%, PPV 92%, NPV 98%, sensitivity 94%, and specificity 98%. The overall values for MRI of the medial and lateral menisci combined were: accuracy 96%, PPV 93%, NPV 98%, sensitivity 96%, and specificity 90%. The clinical examination often failed to diagnose a meniscal lesion: accuracy 64%, PPV 59%, NPV 89%, sensitivity 96%, and specificity 33% for the medial meniscus. For the lateral meniscus the accuracy was 91%, PPV 61%, NPV 98%, sensitivity 89%, and specificity 91%. The overall values for the clinical investigation of the medial and lateral menisci combined were: accuracy 78%, PPV 60%, NPV 94%, sensitivity 93%, and specificity 62%. Investigation of all 201 patients operated from group B with MRI would have cost $160,800. The cost of 30% fewer arthroscopies would have been $562,800--in total $723,600. The operation of all 201 patients cost $804,000. Hence about $80,000 could have been saved by scanning all 201 patients and therefore reduce the rate of diagnostic arthroscopies.

Adolescent↗

PubMed1997

[Saving the extremity by massive transfusion in grade III open femoral fracture with vascular lesion. A case report].

The major problems in the treatment of open fractures with high blood loss are hypothermia acidosis and coagulopathy. By improving the standards of polytrauma management and using massive transfusion systems, which should help to avoid those complications, the indication for primary limb salvage under hypovolemic shock conditions is greatly increased. The following case of an grade 3 open fracture of the femur with severe soft-tissue damage, including vascular lesions, with consecutive massive transfusion, should demonstrate that the cardiac-respiratory system can still be stabilized, even if a surgical solution seems impossible.

Adult↗

PubMed1997

[Hip dislocation without bone injuries].

Dislocation of the hip is rare and so we regard every hip dislocation as an emergency until it has been reduced. From 1977 to 1996 a total of 82 patients with hip dislocation were treated at the Traumatic Surgery Clinic, University of Vienna, Austria. The average age at injury was 29 years. Some 77 patients had unilateral dislocation of the hip, but only in 5 cases was bilateral dislocation found. Iliac dislocation was most common (54 patients). Our treatment consisted in reduction within 6 h of the injury under general anaesthesia (Böhler) and 14 days bedrest. Then the patients were mobilized with full weight bearing, depending on the pain. Of the patients 29 had no clinical infirmities, 8 patients reported temporarily occurring pain and in 6 patients we found a limited range of movement in the hip joint with occasional pain. In all, 43 patients were followed up after 1/2 to 19 years. Radiological signs were seen in 17 patients and avascular necrosis of the femoral head in 1. So after careful evaluation of the patients and the kind of treatment, we recommend the following: 1. Immediate, gentle reduction of the hip joint; 2. Bedrest for 14 days; 3. Early mobilization with full weight bearing.

Adolescent↗