Biomedical subjects

L P Müller

Publications and source records attributed to L P Müller.

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↗

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↗

PubMed2005

[Surgical treatment of type I capitellar-humeral fractures using the Henry ventral approach approach. Short- and medium-term results].

Capitellar fractures are rare. Despite adequate surgical treatment, patients suffer frequently from limited range of motion, osteonecrosis, and neurological deficits. The purpose of this retrospective study was to evaluate short- and medium-term surgical results in seven patients who had type I capitellar fractures according to Bryan and Morrey. All patients were treated via an anterior approach, according to Henry, and open reduction and internal fixation with two screws. Seven patients were examined clinically, neurologically, and radiologically after 10-65 months. The fracture healed in all patients. None of the patients had a neurological deficit. According to the Morrey Score, five of seven patients had an excellent or good functional result. Open reduction and internal fixation with two screws via the Henry approach is a suitable option for surgical treatment for type I capitellar fractures.

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

[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

Rapid musculoskeletal magnetic resonance imaging using integrated parallel acquisition techniques (IPAT)--initial experiences.

PURPOSE: To investigate the feasibility of using multiple receiver coil elements for time saving integrated parallel imaging techniques (iPAT) in traumatic musculoskeletal disorders. MATERIAL AND METHODS: 6 patients with traumatic derangements of the knee, ankle and hip underwent MR imaging at 1.5 T. For signal detection of the knee and ankle, we used a 6-channel body array coil that was placed around the joints, for hip imaging two 4-channel body array coils and two elements of the spine array coil were combined for signal detection. All patients were investigated with a standard imaging protocol that mainly consisted of different turbo spin-echo sequences (PD-, T (2)-weighted TSE with and without fat suppression, STIR). All sequences were repeated with an integrated parallel acquisition technique (iPAT) using a modified sensitivity encoding (mSENSE) technique with an acceleration factor of 2. Overall image quality was subjectively assessed using a five-point scale as well as the ability for detection of pathologic findings. RESULTS: Regarding overall image quality, there were no significant differences between standard imaging and imaging using mSENSE. All pathologies (occult fracture, meniscal tear, torn and interpositioned Hoffa's cleft, cartilage damage) were detected by both techniques. iPAT led to a 48 % reduction of acquisition time compared with standard technique. Additionally, time savings with iPAT led to a decrease of pain-induced motion artifacts in two cases. CONCLUSION: In times of increasing cost pressure, iPAT using multiple coil elements seems to be an efficient and economic tool for fast musculoskeletal imaging with diagnostic performance comparable to conventional techniques.

Adolescent↗

PubMed2002

[The HEPFIEx simulator, a device for determination of friction between femur head prosthesis and cartilage].

We describe a device designed to investigate friction between various femoral head prostheses and human acetabula. It enables not only the determination of friction and the relevance of the play between the femoral head and acetabulum, but also the evaluation of the kinematic behaviour of bipolar prostheses. In the simulator, the various femoral head prostheses are placed on a special cone and tested against a human cadaveric acetabulum. The swiveling range of the device is uniaxial, and the swiveling angle is +/- 35 degrees. The maximum force produced pneumatically is 5kN. Testing of the simulator with a TEP was successful and friction-coefficients of < 0.1 were measured, as are reported in the literature.

Acetabulum↗

PubMed2001

Association of chronic lymphocytic leukemia with specific alleles of the HLA-DR4:DR53:DQ8 haplotype in German patients.

The etiology of chronic lymphocytic leukemia (CLL) remains unknown, though a genetic susceptibility has been suggested. Results of complete DNA typing of HLA alleles in CLL patients are lacking. We compared HLA class I and class II frequencies in 101 German CLL patients and 157 healthy German controls as determined by PCR-SSP/SSO DNA analysis and serologic typing. The most striking difference was the increased frequency of HLA-DRB4*0103 [relative risk (RR) = 2.74, p < 0.0025] among patients. The presence of alleles HLA-DRB1*0401, HLA-DQB1*0302 and HLA-DPB1*0301 as well as of homozygosity for HLA-DQB1 was also associated with a higher risk for CLL, though none of these differences remained significant after correction for multiple comparisons. No association was found for any HLA class I allele. Haplotype analysis revealed a CLL-specific linkage disequilibrium for HLA-DRB1*0401:DRB4*0103 and HLA-DRB4*0103:DQB1*0302. Our results suggest that CLL could be associated with distinct class II alleles of the Caucasian haplotype HLA-DR4:DR53:DQ8, which has also been related to a susceptibility for several auto-immune diseases. The positive, though weak, association of CLL with HLA-DPB1*0301 might represent an independent susceptibility factor since no linkage disequilibrium existed with any of the other CLL-associated alleles. None of the previously reported associations with HLA class I antigens was confirmed. Our results suggest that factors within or close to the human MHC class II region confer susceptibility to CLL.

Alleles↗

PubMed2001

Long-term results after operative treatment of femoral neck fractures with ceramic head prostheses.

From 1985-1990, a total of 277 elderly patients underwent hemiarthroplasty using a ceramic head prosthesis. Average patient age was 81.7 years. Of these, 77 patients were available for follow-up examination in 1993. A standardized score was calculated assessing activity, gait, and hip pain; the average score was 58 out of 78 possible points. Three patients had hip pain, and in 4 patients, radiographic examination revealed protrusio acetabuli. Two of 4 patients underwent revision surgery for replacement of the cup, leaving the stem in situ. Because of the small number of prosthetic-related complications, hemiarthroplasty using a ceramic head prosthesis is the recommended surgical treatment for femoral neck fractures in elderly patients. In the rare patient with protrusio acetabuli, revision surgery can be performed to replace the cup, leaving the stem in situ.

Acetabulum↗

PubMed2000

Frozen shoulder: a sympathetic dystrophy?

Diagnostic and clinical features of the frozen shoulder syndrome and the Sudeck syndrome are similar in many aspects. Radioisotope bone scan shows an increased uptake in affected areas in both diseases, while native radiographs show a progressive demineralisation. Measurement of bone mineral density (BMD) by quantitative digital radiography objectified these local decalcification processes in an early stage of the frozen shoulder syndrome; 10 of 12 patients with primary frozen shoulder had BMD decreases greater 21% in the humeral head of the affected shoulder compared to the non-affected side. In the immobilised control group with degenerative changes of the rotator cuff, calcifying tendinitis and shoulder instability (n = 12) and in the group of healthy probands (n = 20), the difference between the affected and non-affected side (left and right humerus of the healthy probands) was only more than 21% in one case each. There are several references in the literature that assume frozen shoulder to be an algoneurodystrophic process; our observations support this hypothesis, possibly leading to earlier diagnoses and extended therapeutic management.

Absorptiometry, Photon↗

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↗

PubMed2000

Is there still an indication for operative treatment of femoral neck fractures with a ceramic hemiprosthesis? Four-year results.

From 1985 to 1995, 417 patients with dislocated medial femoral neck fractures (Garden III-IV) were treated with hemiarthroplasty using a Biolox ceramic head. The average patient age at the time of operation was 81.5 years. A total of 140 survivors was available for follow-up examination with a mean prosthesis longevity of 55.8 months. The Harris hip score recorded a mean of 70.6 points. At the time of follow up, 5 patients had severe hip pain, and in 8 the roentgenographic examination revealed protrusio acetabuli. Five of these 8 patients underwent revision surgery for replacement of the cup, leaving the stem in situ.

Aged↗

PubMed2000

HLA-A, B, Cw and DRB1, DRB3/4/5, DQB1, DPB1 frequencies in German immunoglobulin A-deficient individuals.

HLA class I and II frequencies and haplotype frequencies were determined in 80 German immunoglobulin (Ig)A-deficient individuals and 157 healthy controls with normal IgA levels using serological and DNA typing methods. For several alleles, significant associations were found, which could be explained mainly in the context of a positive association with three different extended haplotypes (HLA-B*08:DRB1*0301: DQB1*0201, HLA-B*14:DRB1*0102:DQB1*0501 and HLA-B*44:DRB1*0701:DQB1*0202) and a negative association with a fourth haplotype (HLA-B*07:DRB1*1501:DQB1*0602). Furthermore, for the first time this study reports a positive association of IgA deficiency with DPB1 alleles. Homozygosity rate for the gene loci DRB1 and DQB1 was increased in IgA deficiency. Further analysis suggested a different pattern of HLA associations depending on the degree of IgA deficiency and the gender of the IgA-deficient individuals.

Alleles↗

PubMed1999

[Bilateral elastofibroma dorsi].

A 75-year-old man had painless, slowly enlarging tumors in the right and left infrascapular regions. Clinically, the tumors were nontender and semimobile. MR imaging and the operative exploration revealed tumors infiltrating the lateral thoracic muscles and periost of the scapula and underlying ribs. At surgery, the tumors were thought to be malignant, most likely liposarcomas. The histological examination showed the characteristic appearance of elastofibromas with spindle-shaped fibroblasts, which were separated by thick eosinophilic collagenous and elastic fibers. Elastofibromas are benign mesenchymal soft-tissue lesions that mainly affect elderly women. In 10 % of the patients bilateral, often asynchronous tumors are seen. Ninety-nine percent of the lesions are located in the subscapular region. Occasional elastofibromas have been described in the extremities, head, and in the abdominal and thoracic cavities.

Aged↗

PubMed1999

Pigmented villonodular synovitis of the shoulder: review and case report.

Pigmented villonodular synovitis (PVNS) as reviewed in detail elsewhere most frequently involves the knee and finger synovial structures; shoulder involvement is rare: A search through the English literature yielded 18 publications describing 25 cases of PVNS affecting the shoulder joint. Analyzing these reports we found the clinical and radiological findings generally to be nonspecific, often mimicking a malignancy, as in the case presented here of a 16-year-old boy with painful swelling in the area of the left proximal humerus. Magnetic resonance imaging showed a suspected malignant soft tissue mass involving the shoulder capsule and measuring 7.5 x 6 x 4 cm. Preoperatively the patient could recall no trauma; however, postoperatively he did report a distortion trauma of the affected shoulder following a bicycle accident. Intraoperatively, two tumors were found infiltrating the axillary vessels and nerve and tendon structures originating in the capsule of the shoulder joint. Rapid sections of the tissue revealed no signs of malignancy; further pathohistological examination revealed localized PVNS. Preoperatively, the shoulder joint was not suspected as the primary site of origin of the tumor because the patient had no complaints or functional deficits of the shoulder. The clinical presentation of such a PVNS lesion over the proximal humerus is unusual and to date has only twice been described in the literature.

Adolescent↗

PubMed1998

Radiation exposure to the hands and the thyroid of the surgeon during 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, as recommended by the International Commission on Radiological Protection. Extrapolation of the mean 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 to 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. In order to assess the surface doses of the thyroid gland to the primary surgeon with and without a lead shield, we performed in vitro measurements during operative procedures of the lower leg simulating different intraoperative situations under fluoroscopic control. The average registered ionizing dosage without a thyroid shield was approximately 70 times higher than with thyroid lead protection. In a previous study we found average fluoroscopy times during intramedullary nailing of the tibia and femur of 4.6 min per procedure. Extrapolation of this value leads to the result, that even when 1000 intramedullary nailings were carried out without wearing lead protection, only 13 per cent of the dose limit recommended by the International Commission on Radiological Protection for the thyroid of 300 mSv per year would be reached; by wearing the lead protection only 0.2 per cent of the recommended dose would be reached.

Femoral Fractures↗

PubMed1998

[Pigmented villonodular synovitis of the shoulder joint].

A 16-year-old student presented with painful swelling over the left proximal humerus. Magnetic resonance imaging showed a malignant-looking soft tissue mass of 7.5 x 6 x 4 cm invading the shoulder capsule. The patient did not remember initially a shoulder trauma, through postoperatively he reported a distortion trauma of the affected shoulder after a mountain bike accident. Intraoperatively we found two tumors infiltrating the axillary vessel and nerve structures originating from the shoulder joint capsule. Quick examination of the tissue revealed to signs of malignancy, further pathohistologic examination showed a local pigmented villonodular synovitis. Unusual is the clinical presentation of the lesion over the proximal humerus, leading us preoperatively to neglect the possibility of tumor origin from the shoulder capsule, especially since the patient didn't have any complaints or functional deficits of the shoulder joint.

Adolescent↗

PubMed1998

Frozen shoulder--an algoneurodystrophic process?

The frozen shoulder syndrome and the Sudeck syndrome are clinically in many aspects similar. Radioisotope bone scan shows an increased uptake in the affected areas in both diseases, while standard radiographs show a progressive demineralization. With measurement of bone-mineral density by quantitative digital radiography these local decalcification processes were diagnosed in an early stage of the frozen shoulder syndrome: of 12 patients with primary frozen shoulder 10 had a bone-mineral density decrease of more than 21% in the humeral head of the affected shoulder compared to the unaffected side. In the control groups (n = 32) the difference between affected and unaffected side (left and right humerus of the healthy probands) was in only one case each above 21%. There are several indications in the literature assuming the frozen shoulder to be an algoneurodystrophic process. Our observation supports this hypothesis, and may possibly lead to earlier diagnosis and improved therapeutic management.

Bone Density↗