Biomedical subjects

L Rudig

Publications and source records attributed to L Rudig.

At least 19 recordsLinked to original sources

PubMed2006

Locking plates for corrective osteotomy of malunited dorsally tilted distal radial fractures: a biomechanical study.

The purpose of the study was to compare the biomechanical properties of five different palmar fixation plate designs in a distal radius osteotomy cadaver model. A 1cm metaphyseal osteotomy gap was made to simulate a corrective osteotomy and the osteotomy plated. Axial load was applied to the distal end of each construct by a material testing machine under control of a motion analysis video system. The specimens were arranged into five implant groups of eight specimens each. No test group developed deformity and movement of the fracture gap greater than 2mm with a load of 100N. Increasing the load to 250N revealed statistically significant differences in stiffness and failure load between the different plates. Axial failure strength and stiffness were greater for the radial correction plates than for the other implants. The former may provide enough stability for corrective osteotomy of dorsally angulated distal radial malunions, even when the osteotomy gap is only filled with cancellous bone graft instead of cortical bone graft.

Aged↗

PubMed2006

The phenomenon and efficiency of ligamentotaxis after dorsal stabilization of thoracolumbar burst fractures.

Thirty-six consecutive patients with burst fractures of the thoracolumbar spine and with a fractured posterior vertebral surface dislocated into the spinal canal without neurological symptoms were treated with the AO internal fixator. Computed tomography-aided planimetry of the spinal canal was undertaken preoperatively and within 1 week postoperatively to elucidate the effect of kyphosis correction and distraction on spinal canal widening (ligamentotaxis). The stenosis of the spinal canal area (SCA) was reduced from 29% preoperatively to 19% postoperatively (+10%) of the estimated original area, and the stenosis of the mid-sagittal diameter (MSD) reduced from 31 to 23% (+8%). The widening of the SCA was greater at the level of L1/L2 (+13%) than at L3/L4 (+6%). High preoperative canal compromise was associated with greater absolute spinal canal widening. Large trapezoid-shaped fragments resisted reduction by ligamentotaxis. Even though the effect of ligamentotaxis after operative treatment with the internal fixator was proven, a certain stenosis of the spinal canal remains in most cases. Especially for patients with fracture-related neurological symptoms, ligamentotaxis alone does not seem sufficient for the requested spinal decompression. Even an exact analysis of preoperative CT scans under consideration of the fracture level will not always allow an exact prognosis of the expected effect of ligamentotaxis.

Adolescent↗

PubMed2005

["Progressive" hypothenar hammer syndrome Indication for operative treatment].

Hypothenar hammer syndrome (HHS) is ischemia of the distal ulnar artery caused by injury to the ulnar part of the palmar arch. This disease often involves workers who frequently use the hypothenar part of the hand as a hammer. The aneurysmatic form of HHS represents an indication for operative treatment; the thrombotic form is treated mainly conservatively. In our opinion, the symptomatic thrombotic form represents an indication for operation if symptoms persist during conservative therapy, particularly if symptoms progress. In fresh embolic occlusions, regional thrombolysis is usually successful. We present here the symptomatic treatment and course in two patients with complaints increasing during conservative therapy. The patients reported progressive Raynaud's phenomenon of the fingers. Angiography confirmed corkscrew-like aneurysmatic configuration of the distal ulnar artery and subsequent embolization of digital arteries. In both cases, we removed the source of the embolism with resection of the involved arterial segment and anastomosis with autologous vein grafts.

Adult↗

PubMed2004

Friction of ceramic and metal hip hemi-endoprostheses against cadaveric acetabula.

INTRODUCTION: Studies of hip arthroplasty have dealt mainly with total endoprosthesis, while tribology measurement values of hemi-endoprosthetic implants are rare. The small amount of experimental tribological data concerning materials of hemi-endoprosthetic implants in the form of pendulum trials, animal experiments, in vivo measurements on human hip joints and pin on disc studies report friction coefficients between 0.014 and 0.57; the friction coefficients measured in fresh human cadaver hip joints were determined between 0.001 and 0.08. MATERIALS AND METHODS: The HEPFlEx-hip simulator was constructed to test the friction coefficients of unipolar femur head hemi-endoprostheses made of metal or ceramic against fresh cadaveric acetabula. Its plane of movement is uniaxial with a flexion-extension movement of +30/-18 degrees . The force is produced pneumatically dynamic with amounts of 2.5 kN. Newborn calf serum serves as a lubricant. We mounted 20 fresh porcine acetabula and 10 fresh human cadaver acetabula in the HEPFlEx-hip simulator and compared the two unipolar femur head hemi-endoprostheses (metal vs. ceramic). RESULTS: The mean friction coefficients against porcine acetabula were micro=0.017-0.082 for ceramic and micro=0.020-0.101 for metal; against human cadaver acetabula micro=0.017-0.083 for ceramic and micro=0.019-0.118 for metal. The frictional coefficient deltas (metal-ceramic) values of all measurements were Deltamicro=0.004 for porcine acetabula and Deltamicro=0.001 for cadaver acetabula. Box-plots graphics document significantly lower frictional coefficients of the ceramics. CONCLUSIONS: The lower frictional coefficients of ceramic compared to metal against fresh cadaveric acetabula may have a clinical impact on the process of the protrusion of the corresponding femoral head through the acetabulum.

Acetabulum↗

PubMed2004

[Intramedullary osteosynthesis of the ulna in revision surgery].

The exact and adequate management of diaphyesal fractures of the forearm is necessary to ensure forearm motion. Unsatisfactory treatment can lead to loss of function and disability of forearm and hand movement, resulting in severe patient morbidity. Since the rotational and angulatory stresses at the fracture site are the superior factors which influence the outcome of the forearm fracture healing after surgical treatment, the implants must fulfill some general prerequisites including high biomechanical stability, less invasive surgical approach and adequate biological features. However, less clinical studies are known for cases of complicated ulnar fractures when additional revision surgery is necessary to restore form and function. Thus, the choice of implant in such difficult situations requires a profound knowledge and experience. In a series of seven clinical cases we report about the successful use of the ForeSight-nail in revision surgery of complicated ulnar fractures. The series include cases with refractures after plate removal, in-situ plate brokerage and a critical size bone non-union which were treated with interlocking intramedullary osteosynthesis technique.

Adult↗

PubMed2004

[Monteggia injuries in adults: Critical analysis of injury pattern, management, and results].

BACKGROUND: Complications, revision surgery, and unsatisfactory functional results after operative management of Monteggia fractures are frequent. Moreover, hardly any studies exist that deal exclusively with the therapeutic concept for adults. PATIENTS AND METHODS: Between January 1988 and December 2001, 68 patients with Monteggia fractures or equivalent injury were surgically treated. A total of 49 patients could be followed up after 83 months (25-176). Fracture type was assessed according to Bado's classification, functional results according to the Mayo elbow performance score, and the extent of osteoarthritis based on the criteria of Baird and Johnson. RESULTS: The median age of the follow-up patients was 38 years (18-89, 31 men, 18 women). Corresponding to Bado's classification the following injuries were observed: 18 cases of type 1, 22 of type 2, 5 of type 3, and 4 cases of type 4. After surgical intervention, 14 patients achieved "very good", 21 "good", 9 "satisfactory", and 5 "poor" results. Of the 14 patients with either "satisfactory" or "poor" results, 9 manifested a type 2 injury. Complications requiring revision surgery occurred in 14 patients and complications not requiring revision in another 14. Severe osteoarthritic changes in the humeral or radioulnar joint were observed in 4 cases. CONCLUSIONS: Monteggia fractures in adults are fraught with complications despite good functional results in the majority of cases. The patient should be made aware early on of the risk of residual functional deficits and the need for further surgical intervention.

Adolescent↗

PubMed2003

Limb trauma with arterial injury: long-term performance of venous interposition grafts.

BACKGROUND: In contrast to arterial occlusive disease, data on long-term outcomes after vein grafts in limb trauma with arterial injury are sparse. PATIENTS: From 1991 through 2001, 22 trauma victims received 23 interposition vein grafts performed by an interdisciplinary team of trauma and vascular surgeons. Indications included both blunt and penetrating injuries with critical limb ischemia in the majority of cases. RESULTS: Operative treatment of the injured vessels (brachial n = 5, radial/ulnar n = 7, popliteal n = 6, tibial n = 3, pedal n = 2) encompassed venous interposition graft of either saphenous (n = 15) or cephalic vein (n = 8). All patients survived the operative procedure. 4 graft occlusions were noted and 3 major amputations had to be performed (one despite patent graft). 13 patients (76%) were available for duplex ultrasound examination after a mean follow-up of 59 months where patent grafts could be detected in all cases. CONCLUSION: A multidisciplinary approach ensures optimal treatment strategy of arterial injury in extremity trauma. Interposition vein grafts provide durable long-term results and should be attempted even in single-vessel injuries of forearm and lower leg.

Adolescent↗

PubMed2000

Endoscopic carpal tunnel release: results with special consideration to possible complications.

Single-portal endoscopic carpal tunnel release (Agee technique) was carried out in 148 patients. Of these, 100 were examined clinically and electrophysiologically 1 day before surgery and 1 and 3 months thereafter. Ten patients experienced transient ulnar neuropraxia and two patients complained postoperatively of intense pain in the middle and ring fingers. Three patients suffered residual symptoms. In one of these an incomplete release of the distal portion of the retinaculum flexorum was suspected and later confirmed by magnetic resonance imaging. Another patient had applied for pension due to problems associated with a vertebral fracture in addition to his carpal tunnel symptoms. A third patient with residual symptoms was rheumatic, and upon reexamination 6 months later he was virtually symptom free. Five of the 148 operations were converted to an open procedure due to poor visualization. A review of literature on carpal tunnel release (biportal Chow technique and uniportal Agee technique) uncovered 31 intra- and postoperative complications, including 14 affecting nerve structures, 2 tendon structures, 2 bony structures, and 9 the surrounding tissues. We discuss the most common complications, considering in particular the anatomical characteristics in the carpal tunnel region.

Carpal Tunnel Syndrome↗

PubMed1998

[Efficacy of ultrasound controlled direct reposition of fragments of the posterior vertebral body facet].

To calculate canal compromise and decrease of midsagittal diameter caused by retropulsion of fragments into the spinal canal we analyzed the pre- and postoperative computed tomographies of 32 patients with unstable thoracolumbar burst fractures treated by USS (universal spine system). Our intention was to examine the efficiency of ultrasound guided repositioning of the dispaced fragments which was performed in all 32 cases. We found a clear postoperative enlargement of canal area (ASP preoperatively 55%, postop. 80%) and midsagittal diameter (MSD preop. 58%, postop. 78%). 10 of 13 patients presented a postoperative improvement of neurological deficit, no neurological deterioration occurred. Fractures with neurological deficit showed more canal compromise (52%) and less midsagittal diameter (MSD compromise 51%) than those without (40% or 39%). There was no correlation between the percentage of spinal canal stenosis and the severity of neurological deficit. Below L 1 the spinal canal is greater than between Th 11 and L 1, so a more important spinal stenosis is tolerated. In case of unstable burst fractures with neurological deficit the ultrasound guided spinal fracture reposition is an effective procedure concerning the necessary improvement of spinal stenosis: an additional ventral approach for the revision of the spinal canal is unneeded. In fractures without neurologic deficit the repositioning of the displaced fragments promises an avoidance of long-term damages such as myelopathia and claudicatio spinalis.

Adolescent↗

PubMed1998

[3D CT of fractures: comparison of volume and surface reconstruction].

PURPOSE: The comparison of volume rendering (VR) and surface rendering (SSD) for demonstrating fractures from spiral-CT data. MATERIALS AND METHODS: Standardized VR and SSD projections were produced from 50 spiral CT scans of 50 consecutive patients with fractures. Appropriate multiplanar reformattings (MPR) were used as the standard. RESULTS: SSD provided sufficient information in 31/50 cases. Results of VR were not significantly different (33/50). VR was superior in demonstrating 6/7 craniofacial fractures and 3/3 calcaneal fractures. SSD was superior for visualizing 2/3 shoulder fractures and 2/2 elbow fractures. CONCLUSION: VR is a flexible technique for the depiction of fractures and the assessment of spongiosa and articular surfaces at one setting. SSD is superior in the delineation of small dislocated fragments.

Calcaneus↗

PubMed1997

[Magnetic resonance tomography examination of thoracolumbar spinal fractures after fixateur interne stabilization].

To analyse the possible injuries of vertebral segments, especially the disc, after unstable thoracolumbar fractures stabilised with AO internal fixator, we performed magnetic resonance imaging (MRI) of the traumatised region after implant removal. There were two aspects of disc degeneration (DD):(1) biochemical changes and (2) structural damage. MRI detects biochemical processes as one aspect of DD that is often small even in the presence of greater structural damage of the nucleus pulposus caused by fracture. None of the patients presented with structural failure of the anulus fibrosus, which is the essential structural component of the vertebral segments with regard to stability. We observed biochemical changes more often in the lower of the two fracture-adjacent discs and alterations of discal shape more often in the upper of the two, whereas loss of height concerned both discs to approximately the same degree. The supporters of upper-disc resection in thoracolumbar fractures justify their procedure among other things with the structural disc damage, such as alteration of shape and loss of height (altogether more frequent in the upper disc). Our observations that a disc with a structurally altered nucleus pulposus can be biochemically intact and can show an intact anulus fibrosus are arguments in favour of disc preservation. With regard to the upper disc, the widespread opinion that complete and regular disc damage requires a resection has to be revised. The question of whether the lower disc should be resected more often because of its greater biochemical changes cannot be answered by the present study alone. Besides the excellent static information in all anatomical structures of the vertebral column available by MRI, a repeat examination in a prone position yields dynamic information on the spinal cord in the case of suspected dorsal adhesions.

Adolescent↗

PubMed1997

Minimally invasive plate fixation in femoral shaft fractures.

Bridge-plating with its advantages in terms of vascularity and bone healing is a well established procedure today in the treatment of comminuted femoral fractures. Bridge-plating means that the fracture site is not interfered with during the operative procedure. This paper introduces a surgical technique in which the plate is inserted through isolated proximal and distal incisions only, behind the vastus lateralis. Alignment is secured by the plates, the fracture site remains untouched, fixation and screw insertion is restricted to the proximal and distal main fragments. Longitudinal femoral fractures extending right into the trochanteric and or condylar areas are the main indication for minimally invasive plate fixations with angled blade plates or condylar screws since fractures which are restricted to the diaphyseal area are mostly treated by nailing today. The surgical trauma resulting from plating by proximal and distal incisions only is less than that associated with conventional techniques. Indirect reduction of femoral fragments is much easier since the integrity of the surrounding muscles and soft tissue is preserved, the fragments often being reduced simply by traction. Adjustment of rotation is an essential aspect requiring careful attention. For special indications, namely comminuted fractures affecting a large part of the femur and extending into the trochanteric or condylar areas, insertion of the plate via proximal and distal incisions only is a further development in bridge-plating which minimizes surgical trauma and operation time.

Bone Plates↗

PubMed1997

[Complications of endoscopic retinaculum dissection].

Reviewing the literature on endoscopic carpal tunnel release (biportal Chow-technique and uniportal Agee-technique), we found 31 different intra- and postoperative complications. Of these, 14 affected nerve structures, four vessel structures, two tendon structures, two bony structures, and nine surrounding tissues. The most common complications were analyzed taking anatomical and pathological variations of the carpal tunnel into consideration. In our own prospective series of 88 endoscopic releases of the carpal tunnel using the Agee technique, we had eleven complications: one patient suffered residual symptoms, five patients experienced transient ulnar neurapraxia, and one patient complained of intense pain in the middle- and ringfinger after the operation. In four cases, intraoperative change of technique from endoscopic to open became necessary, due to poor visualization.

Carpal Tunnel Syndrome↗

PubMed1996

Hypothenar hammer syndrome in sports.

Repetitive blunt trauma or single severe trauma to the hypothenar region may lead to traumatic thrombosis of the distal ulnar artery (hypothenar hammer syndrome, HHS). In the sports-related literature we found and analysed isolated cases attributed to injuries sustained during sporting activities such as baseball, badminton, handball, football, frisbee, softball, karate, weight-lifting and hockey. Further, we report the case of an amateur golf player with ischaemic symptoms of his left hand, where angiography revealed filling defects in the digital arteries associated with a corkscrew-like configuration of the distal ulnar artery. Magnetic resonance imaging (MRI) scan demonstrated, at the level of the hamulus ossis hamati, accessory fibres of m. palmaris brevis forming a sling around the ulnar artery. Treatment by resection of the thrombosed a. ulnaris segment and replacement with an autologous vein graft resulted in complete relief of symptoms. Histological sections revealed partially organized thrombi adherent to the intimal surface with fragmentation of the internal elastic membrane, indicating a traumatic genesis. As the mechanism of injury, we suspected intensive golf playing with the grip style and subsequent motions leading to pressure injury of the hypothenar area and the underlying ulnar artery. Contraction of the anomalous muscle belly may have additionally compressed the artery, slowing down the arterial flow and promoting thrombosis. In most reported cases including our own, it took a relatively long time until the cause of the disease as traumatic was found and accepted. The initial repetitive blunt or single severe trauma initiating the HHS can easily be overlooked or ignored. After intimal damage of a. ulnaris, the beginning of symptoms may be prolonged and mislead one into thinking the cause is a collagen or vasospastic disease.

Adult↗

PubMed1996

[Radiation burden to the hands of surgeons in intramedullary nailing].

During 41 procedures of intramedullary nailing of femoral and tibial fractures the primary surgeon and the first assistant wore ring dosimeters on their dominant index fingers. While the average fluoroscopy time per procedure was 4.6 min the average dose of radiation to the dominant hand of the primary surgeon was 1.27 mSv and 1.19 mSv to the first assistant. The dose limit for the extremities is 500 mSv per year recommended by the International Commission on Radiological Protection. Extrapolation of the average dose of the primary surgeon and first assistant per procedure of 1.23 mSv leads to the result, that the recommended dose limit of 500 mSv would only be exceeded if more than 407 intramedullary nailing procedures are carried out per year. The duration of fluoroscopy-time correlated with the radiation dose of the hands of the surgeons, though it was determined by phantom measurements that the majority of radiation exposure occurred during brief exposures of the hands in the direct X-ray beam on the X-ray tube near side of the patient.

Body Burden↗

PubMed1995

[The "inserted" condylar plate].

Twelve extensive segmental and comminuted fractures of the femur affecting the metaphyseal areas (7 times proximal, 5 times distal) and the diaphysis were treated with extremely long condylar plates (16 to 20 holes). The condylar plates were inserted via a proximal and a distal incision leaving the Musculus vastus lateralis intact at the fracture site in all cases. Following standard preparation of the blade position using the seating chisel, the condylar plate was inserted behind the musculus vastus lateralis with the blade pointing towards the surgeon. The condyles or the trochanteric area were tilted slightly and the plate was turned 180 degrees and driven home. No screws were inserted in the area of the fracture, in particular, lag screws were not used. Ten out of 12 fractures healed without problems, in 2 cases bone grafting was necessary. Three main observations resulted from analysis of the operations and subsequent clinical and radiographical assessments. In the presence of relatively intact soft tissue covering, an astonishingly good reduction of the fragments was achieved after restoration of leg length and extension. In the healing process, callus formed rapidly and provided medial support. The bone structure was found to be more homogeneous than in the case for plate fixation involving several screws at the fracture site around which considerable fluctuations in bone density frequently occur. The application of condylar plates behind the musculus vastus lateralis by only proximal and distal incision for osteosyntheses of extensive multifragmental fractures is a further development of bridge-plating and can be recommended for long fractures.

Bone Plates↗

PubMed1995

[Color-coded duplex ultrasound as a screening method in trauma surgery].

Deep vein thrombosis with consecutive pulmonary embolism is one of the most important complications for trauma patients. At the University Hospital of Mainz, Department of Traumatology, colour duplex ultrasound is used as screening method in trauma patients. Fractures of thoracic and lumbal spinal bones, pelvis, hip and lower extremities, endoprosthesis of hip and knee joints and longer immobilisation are considered as special risk for the genesis of deep vein thrombosis. Out of 326 patients investigated with colour duplex ultrasound, 24 patients suffered from unknown deep vein thrombosis, 8 developing pulmonary embolism. We recommend colour duplex sonography on day 10, after the third week, and after longer immobilisation. Colour duplex sonography provides an easy performable and noninvasive method for screening evaluation of deep vein thrombosis in trauma patients.

Adolescent↗

PubMed1995

[The effect of bone marrow embolization on the choice of procedure in the stabilization of femoral fractures].

Because of an extended venous drainage system, especially in the supracondylar area, a pressure increase in the femoral cavity results in embolization of the contents of the bone marrow cavity. Bone marrow embolization alone is mostly not apparent clinically but together with cofactors it may result in severe pulmonary damage and occasionally even in death. Cofactors are volume deficit, shock, thoracic and polytrauma and preexisting pulmonary disease. In the field of traumatology a pressure increase in the femoral cavity regularly occurs during unavoidable movement of femoral fragments in traction, during reduction, intraoperatively during intramedullary nailing, and in hip replacement. A hematoma acts as a hydraulic transmitter. Early osteosynthesis within 24 h avoids permanent intravasation of moderate amounts of the contents of the bone marrow cavity. Concerning intramedullary nailing, there are considerable differences between reamed and unreamed nailing. Reaming always leads to high-pressure increases in the femoral cavity, resulting in embolization. Therefore, reaming should not be performed if cofactors of manifestation of pulmonary impairment are present. Unreamed nailing results in less intravasation, but is not entirely harmless, as considerable pressure increases occur in unreamed nailing as well. The gap between the nail and the entrance of the distal fragment is the decisive parameter. Not just the smaller intravasation of bone marrow during unreamed nailing is important. After each reaming process, the bone marrow cavity rapidly refills with blood, which is activated concerning coagulation and pressed into the circulation during the following reaming process. Because of superior bone healing, interlocking nailing is the treatment of choice in diaphysial femoral fractures. As far as the differential indications of reaming are concerned, the discussion is not yet closed. However, reaming should undoubtedly be restricted to a few reaming processes. Before unreamed femoral nailing, the width of the bone marrow cavity must be examined exactly. If the width of the bone marrow cavity, the patient's condition and experience of the surgeon allow unreamed nailing, this procedure can be recommended. As the venous drainage system of the tibia is not important compared to the femur, the question of reaming or not in tibial fractures is not influenced by the danger of embolization, but by soft tissue damage and the stability of interlocking bolts. In patients with femoral fractures and co-factors for the manifestation of pulmonary impairment, the choice of osteosynthesis type should take plating in its improved form into consideration, as this preserves the vascularity of the fragments.(ABSTRACT TRUNCATED AT 400 WORDS)

Bone Marrow↗