The effects of altered strain environments on bone tissue kinetics.

This study defines the alteration in bone tissue kinetics responsible for the "adaptive remodeling" response to altered strain environments. Adult beagle dogs were separated into three experimental groups: ulnar osteotomy, ulnar osteotomy with fracture fixation plate spanning the gap and sham surgery. Four sets of double fluorochrome labels were administered. Prior to sacrifice at 1, 3, and 6 months, strains were measured through rosette strain gages on the cranial and caudal surfaces of the intact radius. Histomorphometric analysis indicated that the increased bone mass in response to elevated strain results from increased activation frequency of modeling with more sites undergoing formation processes than resorption processes on periosteal and endocortical surfaces. Increased remodeling activation did not lead to increased bone mass. There was no evidence that elevated strain changes the individual vigor of osteoclasts or osteoblasts, or that the sigma period was altered by elevated strain.

Skeletal change in response to altered strain environments: is woven bone a response to elevated strain?

Studies demonstrate that geometric changes in bone architecture in response to altered mechanical strain occur through the formation of woven bone. The goal of this study was to test the hypothesis that these changes are partly the result of surgical manipulation rather than a true adaptive response to altered strain. Beagle dogs were subjected to either an ulnar osteotomy, an osteotomy with plate fixation, or sham operation. Strains on the radius were measured just prior to sacrifice 1, 3 or 6 months after surgery. Our results support the idea that woven bone can be a normal response to an abnormal strain environment if the mechanical challenge is intense enough; that elevated mechanical strains can cause the endocortical bone envelope to revert to a state of net formation; and that "adaptive remodeling" in adults in response to a change in mechanical strain may be a special case of modeling in which resorption is not required prior to formation at a particular skeletal site.

Loss of collagen type IV in rheumatoid synovia and cytokine effect on the collagen type-IV gene expression in fibroblast-like synoviocytes from rheumatoid arthritis.

Collagen type IV is a structural matrix protein which contributes to the structural organization of the synovia. In order to characterize the distribution of this protein in synovia with chronic synovitis, collagen type IV was detected by immunochemistry in normal synovia and in synovia from patients with osteoarthritis (OA) and rheumatoid arthritis (RA). A decrease of collagen type IV was observed in synovial layers of rheumatoid synovia, which statistically correlated with the grade of inflammation and with the thickness of the synovial layer. In vitro, we found no differences in the gene expression of collagen type IV in cultures of fibroblast-like synoviocytes (FLS) derived from OA and RA using a reverse-transcriptase polymerase chain reaction. Nevertheless, we observed a downregulating effect of tumor necrosis factor-alpha and interleukin (IL)-1beta on the gene expression of collagen type IV only in FLS isolated from patients with RA. The effect of IL-1beta was dose dependent. In summary, we observed an inflammation-associated decrease of collagen type IV in the synovial layer of rheumatoid synovia. Inflammatory cytokines may play a role in regulating the synthesis of collagen type IV in the rheumatoid process in vivo.

Synovial membrane and cartilage changes in experimental osteoarthrosis.

The Hulth instability model was performed on 25 rabbit knee joints. Electron-microscopic, light-microscopic, and histomorphometric data demonstrated consistent chondrocyte alterations and cartilage destruction. The comparison between operated, sham, and control knees shows that surgical intervention without surgically induced instability is followed by changes in the synovial membrane and cartilage. The cartilage destruction is preceded by a synovial reaction, suggesting that the inflammatory response has an important role in the onset of cartilage damage in this model. The damage was more severe in the experimental knees, suggesting that mechanical instability is also a factor in cartilage destruction.

The autologous stump plasty. Treatment for bony overgrowth in juvenile amputees.

Autologous stump capping is a procedure designed to prevent bony overgrowth in skeletally immature amputation stumps. All 19 capping procedures in the lower extremities were successful after an average follow-up of 7.3 years. All patients use their prostheses, and no secondary operations have been needed for stump problems. Of the 31 cap-plasties of the humerus, six required re-operation. The overall failure rate of 12% is low compared with the failure rate of re-amputation.

A ten- to 15-year follow-up of the cementless spotorno stem.

We followed the first 354 consecutive implantations of a cementless, double-tapered straight femoral stem in 326 patients. Follow-up was at a mean of 12 years (10 to 15). The mean age of the patients was 57 years (13 to 81). At follow-up, 56 patients (59 hips) had died, and eight (eight hips) had been lost to follow-up. Twenty-five hips underwent femoral revision, eight for infection, three for periprosthetic fracture and 14 for aseptic loosening. The overall survival was 92% at 12 years (95% CI 88 to 95). Survival with femoral revision for aseptic loosening as an endpoint was 95% (95% CI 92 to 98). The median Harris hip score at follow-up was 84 points (23 to 100). Radiolucent lines (< 2 mm) in Gruen zones 1 and 7 were present in 38 (16%) and 34 hips (14%), respectively. Radiolucencies in zones 2 to 6 were found in five hips (2%). The results for mid- to long-term survival with this femoral component are encouraging and compare with those achieved in primary cemented total hip arthroplasty. The high rate of loosening of the cup and the high rate of pain are, however, a source of concern.

Middle-term results of threaded acetabular cups. High failure rates five years after surgery.

We report our results using three different threaded acetabular components (Mecring A, Mecring B and Weill) in 715 hips with a follow-up of between one and ten years (median: 99.1, 56.5, 38.3 months, respectively). All cups were implanted with one type of cementless stem. The clinical results were good or acceptable in about 70% of the hips, but signs of loosening with radiolucency and/or migration were found in 10.1%. Radiological evidence of loosening did not correlate significantly with the clinical outcome. Pain was not a reliable indicator of loosening and its absence sometimes allowed severe osteolysis to develop. Twenty-five hips were revised (3.5%) for aseptic loosening of the acetabular component. Kaplan-Meier estimates of the cumulative rate of failure showed a rapid increase five years after the initial operation, but no significant correlation with gender, age or weight. The high rate of failure indicates that further use of these acetabular components cannot be recommended. Annual radiographs are required to assess osteolysis even if the patients are free from pain.

A new animal model of femoral head necrosis induced by intraosseous injection of ethanol.

There is no reliable animal model of the early stages of osteonecrosis of the femoral head (ONFH) for the evaluation of new therapeutic approaches. In this study, we propose a new animal model of femoral head osteonecrosis. Pure ethanol was injected into the centre of the femoral head in adult Merino sheep under fluoroscopic control. After 3, 6 and 12 weeks the animals were killed and the femoral heads were harvested. Microradiographic and histological changes were analysed and recorded. Partial necrosis was documented over a period of 12 weeks in all animals. The appearance of necrosis in combination with intact macrotexture, macrocirculation and joint cartilage is similar to the features described in early ONFH in humans. Due to its efficacy and its similarity to the early stages of ONFH in humans, this model may be suitable to evaluate new therapeutic techniques in the treatment of ONFH.

Late results after subtrochanteric angulation osteotomy in young patients.

Young patients with painful congenital dislocation of the hips need surgery if conservative treatment is unsuccessful. A total of 24 patients after 28 subtrochanteric angulation osteotomies without resection of the femoral head were followed up (mean, 17 years) to evaluate long-term results. Most patients maintain improved function: 20 hips showed persistent gain of abduction, 14 patients showed improvement of gait, and 18 patients described less pain. The degree of angulation must equal the inclination of the pelvic wall to influence hip stability as well as hip range of motion. Osseous reactions of support-seen in 10 hips-are not proof of operative success. Angulation osteotomy does not exclude later surgical procedures such as total hip replacement.

[Management of unstable pertrochanteric femoral fracture by alloarthroplastic joint replacement]. / Die Versorgung der instabilen pertrochanteren Femurfraktur durch alloarthroplastischen Gelenkersatz.

The treatment of trochanteric fractures of the femur should aim at the reconstruction of the joint function and should allow early weight bearing. In the case of unstable fractures and advanced osteoarthritis of the hip joint the advantages and risks of a total hip replacement have to be compared with different methods of osteosynthesis. We report on 35 patients with trochanteric fractures primarily treated with a total hip replacement. Their perioperative mortality was 9%, the most common complication was a luxation of the replaced hip joint in 3 cases. 1 patient had to be reoperated because of a soft tissue infection. Comparing the literature the primary total hip replacement shows a lower morbidity and mortality rate than complicated methods of osteosynthesis.

[Arthrotomy--a prearthrotic factor?]. / Arthrotomie--präarthrotischer Faktor?

UNLABELLED: Light-microscopic and electron microscopic findings of the synovial membrane and cartilage were compared, of rabbit knee joints on which arthrotomy and surgical induced instabilisation operation were performed. The joint opening was followed by an inflammation of the synovial membrane, and cartilage changes were similar in joints of arthrotomy and surgically induced instability. CLINICAL RELEVANCE: To prevent joints from further damage after arthrotomy or arthroscopy, joints should be spared from weight bearing during the time of synovial inflammation.

[Peroneal nerve palsy after total knee arthroplasty under continuous epidural anaesthesia]. / Peronäusläsionen nach KTEP-Implantation unter Verwendung einer postoperativ fortgeführten periduralen Analgesie.

BACKGROUND: Peroneal nerve palsy is a rare but distressing complication of total knee arthroplasty (TKA). After introducing a standardised intraoperative and postoperative epidural anaesthesia protocol under otherwise unchanged perioperative management, we noted a sudden cumulation of peroneal nerve palsies after TKA. PATIENTS AND METHODS: In this retrospective study we checked the patients' histories for well-known risk factors for nerve lesions after TKA as well as for those risk factors controversially discussed in the literature. RESULTS: We found an additive harmful impact of epidural anaesthesia leading to unrecognised pressure on the peroneal nerve, which caused, in combination with a pressure lesion of the pneumatic tourniquet, an axonal lesion in terms of a double-crush syndrome. By lowering the pneumatic tourniquet pressure and carefully positioning the operated leg, we found a clearly reduced risk of nerve lesion while preserving the advantages of epidural anaesthesia for the patient. CONCLUSION: To prevent a peroneal lesion after TKA while using continuous epidural anaesthesia, we strongly recommend limiting the pneumatic tourniquet pressure to 320 mmHg while ensuring pressure-free positioning of the operated leg.

[Histologic, morphometric study of the human synovial membrane]. / Histologische, morphometrische Untersuchung der menschlichen Synovialmembran.

Human synovial membrane was studied by light- and electronmicroscope and histomorphometrically. Areas of distinct structures are seen. The surface structure fold that is mainly seen in the areaolar and adipose synovial membrane type, seemed to be the prime structure for the synovial turn over. Villi have fenestrated capillaries and they are covered of A- and AB-synoviocytes. Villi are regarded as the synovia production areas. The fibrous type of the synovial membrane is mostly smooth surfaced and seemed to be an ordinary fibrous connective tissue. The B-synoviocyte is discussed as fibrocyte.

[Complete synostosis of the cervical spine at a young age. A thus far unpublished disease]. / Komplette Synostosierung der Halswirbelsäule im jugendlichen Alter. Ein bisher unveröffentlichtes Krankheitsbild.

A case of complete synostosis of the cervical spine in a 12-year-old girl is described. Differential diagnosis included dysontogenetic forms of synostosis, Klippel-Feil syndrome, rheumatic synostosis and synostosis of other inflammatory origin. This severe case, the first of its type to be described, appeared to be due to tuberculosis of the cervical spine.

[Spinal fractures in ankylosing spondylitis]. / Wirbelsäulenfrakturen bei der ankylosierenden Spondylitis.

In the final stage of ankylosing spondylitis the spine will be completely fixed. With loss of mobility the patients suffering of ankylosing spondylitis are susceptible to spinal fractures. Predominantly the fractures occur in the lower part of the cervical spine, caused often by minor trauma. High fatality is at a 30% rate seen as severe consequence of these fractures. Conservative and operative treatment may be used. Severe fracture dislocation and progressive neurological deficiencies are recommended to be stabilized operatively. To avoid trauma of the spine in patients with ankylosing spondylitis preventive measures seem to be possible and should be employed.

[Expression of TNF receptors in rheumatoid arthritis and ankylosing spondylitis]. / Expression von TNF-Rezeptoren bei rheumatoider Arthritis und Spondarthropathien.

Tumor necrosis factor is an important mediator of the pathophysiologic events in synovitis. The expression of the p75 and p55-TNF-receptors in rheumatic diseases was investigated. Synovial mononuclear cells (SMNC) of patients with rheumatoid arthritis and spondylarthropathies express p75 TNF receptors in all cases, whereas SMNC of patients with traumatic synovitis do not. In 4/9 patients with rheumatoid arthritis and in 6/11 patients with spondylarthropathies SMNC also expressed the p55 TNF receptor. Differential analysis of lymphocytes and monocytes/macrophages revealed that both predominantly expressed the p75 TNF receptor. The highest concentrations of both soluble TNF receptors which may act as TNF antagonists were found in synovial fluids of rheumatoid arthritis patients.

[Results of resection of the head of the ulna]. / Ergebnisse nach Ellenköpfchenresektion.

A follow up of 57 wrists with resection of caput ulnae shows different value to different groups of patients. The painful arthrosis of distal radioulnar joint gives indication in posttraumatic cases. Release of pain and improvement of range of motion will be achieved; loss of strength is the most impairing problem for younger patients. 13 patients out of 21 with posttraumatic deformities were satisfied with the post-operative outcome; 13 patients showed significant loss of strength, too. In case of rheumatoid arthritis with caput-ulnae-syndrome the resection is without alternative, needs to be combined with the arthrodesis of radiolunar-joint, if necessary. 20 of 34 rheumatics were satisfied with the outcome after resection of caput ulnae; in 6 cases an ulnar drift was evident, which implied simultaneous or later partial arthrodesis of the wrist. For all patients release of pain decided on their satisfaction with surgery.

[Cementless hip prosthesis in inflammatory rheumatic diseases]. / Zementfreie Hüftendoprothetik bei entzündlich-rheumatischen Erkrankungen.

We compared the outcome of cementless hip arthroplasty in patients with chronic rheumatic diseases (cases) and patients with osteoarthritis (controls). Between 1985 and 1993 we implanted 26 cementless hips in 22 patients with Rheumatoid Arthritis, Psoriatic Arthritis or Ankylosing Spondylitis. From a pool of more than 600 patients with Osteoarthritis we chose 40 matched controls (41 hips). Matching variables were year of implantation, age, follow-up, height, weight, gender and type of implant. At follow-up (cases: 58 +/- 27 months; controls: 56 +/- 26 Monate) no signs of loosening or migration of the stem were found, neither in the cases nor in the controls. Loose and/or migrated cups were found in 4 patients with rheumatic diseases (after 44, 65, 65 and 107 months) and in 3 patients with osteoarthritis (after 63, 84 and 100 months). Two cups were revised within 18 months in the control group, in the case group one revision was necessary after 5 years. Loosening and revision rates did not differ significantly (p > 0.20). Clinically, those with Osteoarthritis had a better extension (p < 0.02), were more satisfied with their (artificial) hips (p < 0.05) and did better in some activities of daily living (climbing stairs, dressing, sitting/standing up). Within a mean follow-up of 5 years the results of patients with chronic rheumatic diseases seem to be comparable to those of a matched control-group of patients with Osteoarthritis. Differences between the groups concern areas, in which rheumatic patients are handicapped due to their chronic illness. Nevertheless, we need long-term-results, before we can recommend cementless implants for these patients.

External fixation in proximal tibial osteotomy: a comparison of three methods.

During a period of 6 years (1990-1996), 154 patients with unilateral gonarthrosis underwent proximal tibial osteotomy using 3 different methods of external fixation: (1) closing wedge osteotomy and bilateral fixation; (2) closing wedge osteotomy with unilateral fixation, and (3) opening wedge osteotomy with unilateral fixation. The most common complications were pin-tract infection (25%), temporary nerve palsy (10%), and loss of alignment (17%). At least one complication developed in 33% of patients in this study, indicating that the use and technique of external fixation in proximal tibial osteotomy can be problematic.

[Biometric planning of clinical-orthopedic studies. The optimal test]. / Biometrische Planung klinisch-orthopädischer Studien. Der optimale Stichprobenumfang.

A determinant for the evidence of a clinical trial is the magnitude of the sample size. The proper sample size can be easily computed with the knowledge of alpha, power and effect size. Standard values for alpha and power in clinical trials are 5% and 90%, respectively. As a consequence, effect size is crucial for the sample size. The effect size has to be determined by the clinician according to medical considerations. Possible consequences of sample sizes that are either too small or too large are discussed with regard to the meaning of alpha, Power and effect size. Trials with improper small sample sizes have a high risk of false negative results, and may subsequently prevent the application of a possibly effective therapy. Trials with improper large sample sizes may result in statistically significant differences without any clinical relevance.