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Biomedical subjects

D Hohmann

Publications and source records attributed to D Hohmann.

At least 19 recordsLinked to original sources
PubMed2004

Molecular mechanism of estrogen receptor (ER)alpha-specific, estradiol-dependent expression of the progesterone receptor (PR) B-isoform.

The physiological effects of progesterone are mediated by the progesterone receptor (PR) isoforms PRA and PRB, transcribed from a single gene, under control of two distinct promoters. Both the isoforms display different, promoter- and cell line-specific transactivation properties. Upregulation of both isoforms in response to estradiol stimulation has been described, although the two promoters contain no classical estrogen response element (ERE). Therefore, we decided to investigate the regulation of PRB-expression through distinct estrogen receptor (ER)-isoforms: ERalpha and ERbeta We demonstrate, that in HeLa cells treated with E2, PRB promoter activity was enhanced (five-fold) by ERalpha, but not by ERbeta. ERbeta was also unable to stimulate activity of the PRB promoter in BT20 and Ishikawa cells, where ERalpha induced reporter activity by two-fold. Deletion of the AF1-but not AF2 domain from ERalpha resulted in loss of the transactivation potential in all cell lines tested. Furthermore, in BT20 cells deletion of the AF2 domain of ERalpha resulted in stronger transcriptional activation than that mediated through wild-type ERalpha. In SK-BR-3 cells both ERs repressed PRB promoter activity and this repression was enhanced by co-transfection of SRC1. However, strong estrogen-dependent stimulation was observed after deletion of AF2. We conclude that PRB expression is stimulated by ERalpha but not ERbeta in an unique, AF1-dependent but AF2-independent mechanism.

Breast Neoplasms↗
PubMed2002

Alternative bearing surfaces in total hip arthroplasty: zirconia-alumina pairing. Contribution or caveat?

The aim of the present study was to evaluate the zirconia and alumina articulation in total hip arthroplasty in regard to clinical and radiological outcome. This is the first report concerning the clinical application of a hybrid ceramic articulation. Owing to ethical reasons, a limited number of patients was enrolled in the study. Ten consecutive patients with degenerative arthritis were randomly allocated after informed consent to hybrid total hip arthroplasty treatment using an alumina femoral head and an alumina acetabular liner (5 hips), or using a zirconia femoral head and an alumina acetabular liner (5 hips). The median age of patients at index operation was 57.8 years. Current criteria were used for clinical and radiological assessment. The mean follow-up was 5.1 years (5 to 5.3 years). No hip required revision, and no clinical and radiological differences were observed between the two groups of hips. The median preoperative Harris hip score was rated 55.3 points in the control group of hips with alumina head, and 55.6 in the group of hips with zirconia head. The median Harris hip score increased to 94.9 points at the time of follow-up in the control group, and 96 points in the zirconia group. No radiological signs of cup loosening or focal acetabular osteolysis were detected at follow-up. All stems showed stable fixation without radiolucent lines or focal osteolysis. Zirconia femoral heads and alumina acetabular liners have been successfully used in the present series of 5 total hip arthroplasties with a mean follow-up of 5.1 years. Nevertheless, the use of femoral heads made of zirconia in total hip arthroplasties remains an important clinical concern due to the potential genesis of wear microparticles which can lead to progressive osteolysis. Further in-vitro and in-vivo investigations are required to define the value of this alternative bearing surface.

Aged↗
PubMed2000

Total hip arthroplasty using an uncemented femoral component with taper design: outcome at 10-year follow-up.

The aim of this study was to assess the clinical and radiological outcome of the cementless-system (CLS) femoral component designed by Spotorno with a taper design. Ninety-four patients (107 hips) were operated on from January 1987 to December 1988. The female/male ratio was 2/1, the mean age was 51 years (range 20-77 years). Clinical follow-up was obtained in 89 hips (83%). Five patients (7 hips, 6.5%) could not be traced. Nine patients (11 hips, 10%) had died before the minimum time of follow-up required for this study (10 years). All these hips still had their stem in place at the time of the last intermediate inquiry. The mean follow-up was 10.3 +/- 0.3 years. No stem required revision. According to the Harris score, 84% of hips were rated good or excellent, 14% fair, and 2% poor. The average Harris hip score was 88 at the time of the last follow-up. Fifteen patients (17%) reported occasional thigh pain. All patients reported complete relief of pain within the first 6 months after the operation. Radiologically, 95% of stems showed stable fixation by bony ingrowth, 5% by fibrous ingrowth. Seven (9%) uncemented acetabular components showed progressive migration. Three of those cups had been replaced in the meantime. Fifty-one (65%) of the CLS stems induced either no change in femoral bone density or only patchy loss of bone density localized to zone 1 or 7 according to Gruen, while 27 (35%) of the hips showed some reduction of bone density in the proximal diaphysis of the femur (zone 2 or 6). Severe progressive osteolysis of the femoral cortex underneath the lesser trochanter was found in 4 hips (5%) with coexistent loosening of the cup. In all of these hips, the Mecron cup had been used. At a mean follow-up of 10 years, the results of the CLS femoral component are comparable with those of modern techniques of cementing in primary total hip arthroplasty and with the long-term outcomes of other uncemented stems with tapered design. The long-term fixation of the cup remains an unsolved problem.

Adult↗
PubMed2000

Influence of facet joint angles and asymmetric disk collapse on degenerative olisthesis of the cervical spine.

This study examined the facet angles of the joint facets of the intervertebral joints, the anterior and posterior heights of the intervertebral disks, and cervical lordosis as possible parameters of olisthesis. Lateral radiographs of the cervical spine in 123 patients were examined, and parameters were correlated to anterolisthesis and retrolisthesis in each segment. Results indicate anterolisthesis is caused by a decrease of the facet angles of the caudal joint facets. This process is favored by loss of anterior height of the intervertebral disks and a flattened position of the cervical spine. Loss of posterior height of the intervertebral disks promotes retrolisthesis.

Adolescent↗
PubMed1999

Prophylaxis of secondary osteoarthrosis with spherical osteotomy in residual acetabular dysplasia. Analysis of predictive factors of success.

The aim of this study was to evaluate whether or not spherical acetabular osteotomy prevents progression of osteoarthrosis in hip joints with residual dysplasia and which radiological parameters can be used postoperatively as predictive factors concerning the outcome. Sixty-eight out of 78 joints were re-investigated with a mean follow-up of 11.2 years after the index operation. Twenty-three Wagner type 1 and 45 type II osteotomies were performed. At surgery, the mean age of the patients was 26 years; 90% of joints showed no or mild degenerative changes, 26% presented with a good or excellent Harris hip score. At follow-up, 28% of patients had improved in function, mean Harris hip score rated 75 points. The mean center-edge (CE) angle improved from -4 degrees to 18 degrees, and the anterior center-edge (ACE) angle from -4 degrees to 26 degrees. The weight-bearing zone of the acetabulum showed an acetabular index (AC) angle of 27 degrees preoperatively and 14 degrees postoperatively. Statistical analysis proved a significant correlation between the normal postoperative values of the acetabulum/femoral-head index of Heyman and Herndon and the absence of degenerative joint changes at follow-up. 73.5% of the hips had not markedly progressed to secondary osteoarthrosis, but 26.5% of joints had deteriorated: 7.4% of them due to perioperative complications and early postoperative trauma. In 8.8% (severe dysplasia) only partial reorientation was possible, which explains the progression of arthrosis, but 10.2% progressed despite sufficient correction.

Acetabulum↗
PubMed1999

Relevance of the drainage along the linea aspera for the reduction of fat embolism during cemented total hip arthroplasty. A prospective, randomized clinical trial.

The aim of this study was to assess the relevance of drainage placed along the linea aspera for the prevention of fat embolism and cardiopulmonary impairment during the insertion of a cemented stem. We studied 40 patients with coxarthrosis randomly allocated to total hip arthroplasty with proximal drainage or without it. The venting hole for the drainage of the medullary cavity was placed posteriorly, between the greater and the smaller trochanter, in the prolongation of the linea aspera. The heart was monitored intraoperatively by a echocardiography probe positioned in the patient's oesophagus. During the operation we monitored the hemodynamics and blood gas values. Severe embolic events were observed in 85% of the control group and in 20% of the drainage group (P = 0.01). Embolism occurred during the insertion of the femoral component and continued after reduction of the hip joint. After major embolism, the pulmonary shunt values increased significantly in the control group (+22.7%), but there were no marked changes in the drainage group (+7.1%). The logical therapeutic measure to avoid intravasation of bone marrow, fat, and bone debris during the insertion of the femoral component is to prevent the rise of intraosseous pressure. The drainage of the venous system located along the linea aspera significantly reduces the risk of intraoperative embolism and cardiopulmonary impairment.

Aged↗
PubMed1999

Long-term results of spherical acetabular osteotomy.

We have examined the effect of the Wagner spherical acetabular osteotomy on preserving the joint in 38 hips with a mean follow-up of 17 years. At the time of the initial operation, 55% of patients had clinical symptoms and 30 joints showed minimal or absent radiological signs of osteoarthritis. At follow-up, 54% of patients had a good functional result. The osteotomy improved the mean centre-edge angle from -3 degrees to +15 degrees, the mean anterior centre-edge angle to 23 degrees and the acetabular head index to 75%. The obliquity of the acetabular roof decreased from 28 degrees to 16 degrees. One patient improved, but 14 deteriorated with joint degeneration. Of these, one progressed because of postoperative deep-tissue infection and five due to undercorrection. One patient needed total joint replacement after 14 years. At 17 years after operation, Wagner osteotomy had prevented progression of secondary arthritis in 63% of cases.

Acetabulum↗
PubMed1998

Impaction grafting and acetabular reinforcement in revision hip replacement.

A substantial loss of bone stock is frequently encountered at revision of a hip replacement. A mix of autologous and homologous bone chips is a biological method of filling the cavities. Reinforcement implants can be used to anchor the new prosthesis and to impact the bone graft, protecting it during healing. The goals of this study were to evaluate the clinical and radiological results after revision of cups with aseptic loosening. Follow-up examination of 81 revisions in 78 patients at 6.5 years (range 3 to 9 years) showed that 93% of the patients were satisfied with their results. One patient underwent a further revision because of recurrent dislocation of the femoral head, and one had a superficial infection. All the grafts were fused at 3 months after the operation. The bone stock had increased in every case, but 6 of them show some degree of graft resorption. No implant showed impending signs of loosening. These results were encouraging. The reinforcement implants allow sufficient primary fixation and secondary stability can be achieved with the impaction grafting. Careful preoperative evaluation and assessment at operation is important to match bone defects with the grafts and selection of the prosthesis.

Arthroplasty, Replacement, Hip↗
PubMed1996

Radiographic evaluation of the upper cervical spine in rheumatoid arthritis: a retrospective analysis.

We analysed retrospectively 295 lateral roentgenograms of the cervical spine in 150 patients with classic or definite rheumatoid arthritis. In addition to measuring the atlantodental interval, measurements of the different vertical parameters described by McGregor, Ranawat and Redlund-Johnell and a new measurement method with high reproducibility were described and their results compared statistically. As a control group we analysed 100 lateral roentgenograms of the cervical spine in patients with no inflammatory disease, posttraumatic lesion, tumour or osseous deformity.

Adult↗
PubMed1996

Measuring stability of wire cerclage in femoral fractures when performing total hip replacement. In vitro study on a standardized bone model.

The stability of wire cerclage was investigated on a wooden model. Two semitubular shells made of hard oak were firmly joined together using cerclage wires of different diameters and with different techniques. A conical test piece was then implanted. The test set-up was subjected once to an axial force of 4 kN and a torque of 20 Nm using a testing machine. Implant excursion at the interface was measured. One hundred forty measurements carried out on test pieces with fissures demonstrated that cerclage wires with the largest diameter possible should be used with a double-loop technique. Wire diameters under 1.2 mm are unsuitable for cerclage of the femur because they rupture easily. The most stable cerclage is obtained with two double cerclages using 1.5-mm stainless steel wires. Although micromotion is greater than for the reference group without fissures, no cases of excursions exceeding 100 microns could be measured. In comparison with a femoral shaft that is not fractured, marked instability remains. It is recommended that a tightening tool be used to tighten the wires, as this achieves considerably more stable cerclage than that achieved with two forceps.

Bone Wires↗
PubMed1996

[Surgical therapy of spondylogenic cervical myelopathy. Indications and techniques].

The cervical spondylotic myelopathy is the most frequent spinal dysfunction. Its spontaneous course is very variable, from progress to stagnation. This makes prognosis and decision-making difficult for conservative or operative treatment. The authors attempt to provide some basis for decision-making by observing the individual course of neural dysfunction, consideration of morphometric data and the use of functional scores. To advise a patient, the outcome of conservative and operative treatment as described in the literature has to be considered, as well as the possible complications. The advantages and disadvantages of surgery from the anterior and posterior approach are discussed. Operative planning according to the individual condition is suggested. Operative techniques of anterior decompression and fusion are contrasted to laminoplasties.

Adult↗
PubMed1995

Atlantoaxial instability in a 7-year-old boy associated with traumatic disrupture of the ossiculum terminale (apical odontoid epiphysis).

A case of atlantoaxial instability with a rare etiology in a boy of 7 years and 3 months is presented. Computerized tomography with three-dimensional reconstruction revealed avulsion of the ossiculum terminale (apical odontoid epiphysis). Developmental peculiarities and relevant disorders of the infantile upper cervical spine are discussed. Temporary posterior C1/C2 fusion and transdental screw fixation of the ossiculum terminale were attempted in order to stabilize C1/C2 and avoid permanent fusion. After removal of the dorsal implants, the transdental screw broke, the instability recurred and a permanent atlantoaxial fusion had to be performed.

Atlanto-Axial Joint↗
PubMed1994

[Prevention of para-articular ossifications after endoprosthetic hip joint replacement by postoperative irradiation].

In a prospectively randomized study, 137 patients with 141 hips at high risk for heterotopic ossification (HO) received prophylactic radiation therapy (RT). Patients were randomly assigned to a low-dose regimen of five fractions of 2 Gy each (n = 73) or a high-dose regimen of either 10 fractions of 2 Gy each (n = 7) or five fractions of 3.5 Gy each (n = 61). Treatment outcome was assessed by comparing immediately postoperative radiographs with radiographs obtained at least 6 months after hip surgery (Brooker grading score). Positive responses (ie, effective prophylaxis of HO) were seen in 129 (91.5%) hips. Treatment failures were observed in 12 (8.5%). Use of a nonsteroidal antiinflammatory drug (NSAID) lowered the failure rate in both groups. High RT dose with a short duration (< or = 9 days) and use of an NSAID was significantly (p = 0.009) correlated with treatment success. RT delivered within a few days after hip surgery is effective in preventing HO, even in high-risk patients, and provides an alternative of at least equal value for patients with contraindications to long-term medication with either NSAIDs or corticosteroids.

Adult↗
PubMed1993

Prevention of heterotopic ossification (HO) after total hip replacement: randomized high versus low dose radiotherapy.

In a prospectively randomized study 60 hips at high risk for heterotopic ossification (HO) received prophylactic radiotherapy (RT). Randomization was performed between a low dose (LD-RT) of 5 x 2 Gy (arm A: 32 patients) and a high dose (HD-RT) of either 10 x 2 Gy (arm B1; 8 patients) or 5 x 3.5 Gy (arm B2; 20 patients). Relevant patient and risk factors were equally distributed in both treatment arms. 4 (7%) patients developed treatment failures. A short delay of RT after postoperative day (POD) 4 was significantly correlated with failure (p < 0.001). The results suggest no difference in prophylactic efficacy between LD-RT and HD-RT treatment. 2/19 (11%) patients receiving additional diphosphonates and 2/18 (11%) on no medication failed RT treatment, but none on indomethacin did so. In conclusion, immediate postoperative RT has been shown to be an effective prophylactic treatment.

Adult↗
PubMed1993

Prophylactic radiation therapy for prevention of heterotopic ossification after hip arthroplasty: results in 141 high-risk hips.

In a 4 1/2-year, prospectively randomized study, 137 patients with 141 hips at high risk for heterotopic ossification (HO) received prophylactic radiation therapy (RT). Patients were randomly assigned to a low-dose regimen of five fractions of 2 Gy each (n = 73) or a high-dose regimen of either 10 fractions of 2 Gy each (n = 7) or five fractions of 3.5 Gy each (n = 61). Treatment failure was assessed by comparing immediately postoperative radiographs with radiographs obtained at least 6 months after hip surgery (Brooker grading score). Positive responses (ie, effective prophylaxis of HO) were seen in 129 (91.5%) hips. Treatment failures were observed in 12 (8.5%). Use of a nonsteroidal antiinflammatory drug (NSAID) lowered the failure rate in both RT groups. High RT dose with a short duration (< or = 9 days) and use of an NSAID was significantly (P = .009) correlated with treatment success. RT delivered within a few days after hip surgery is effective in preventing HO, even in high-risk patients, and provides an excellent alternative for patients with contraindications to long-term medication with either NSAIDs or corticosteroids.

Adult↗
PubMed1988

[Approaches in computer-assisted surgical planning in hip dislocation].

From a sequence of planar CT pictures of the hip joint the diagnostically relevant contours are extracted on a graphic monitor by means of an image-analysis process. To do this an image preprocessing is necessary to improve the quality of the CT pictures. These contour data permit a mathematical surface model of the hip joint to be derived using well-known methods of simulating an osteotomy. Three-dimensional reconstruction of the cartilage surface by MRI will be possible in the future. It will then be possible to plan computer-aided osteotomies with high accuracy.

Computer Graphics↗
PubMed1987

[Benign tumors of the spine].

The most common benign tumors and tumor-like lesions are presented from the aspects of localization in the spinal column and the resulting implications for diagnosis and therapy. For some of these tumors (aneurysmal bone cysts, osteoblastomas, giant cell tumors), von Enneking's suggested staging classification (latent, active, aggressive) is valuable for planning the operation (curettage, tumor removal with healthy tissue margins, wide en bloc resection). If the tumor stage is evaluated preoperatively, problems can be avoided such as overtreatment leading to loss of stability that could have been avoided or the danger of recurrence because the operation was not sufficiently radical. Embolization of the tumor vessels, as an adjuvant measure, not only makes the excision of highly vascular tumors easier, but also can be a means of curbing tumor growth in inoperable cases.

Diagnosis, Differential↗