Biomedical subjects

U Bosch

Publications and source records attributed to U Bosch.

98 records · Page 6Linked to original sources

PubMedDate not supplied

Extension osteotomy in malunited clavicular fractures.

The association of a malunited clavicular fracture with a pattern of disability that includes not only pain but also impairment of shoulder function is rare. But in cases where such an association exists, correction of the clavicular deformity should be considered. We report on 4 patients with a malunited fracture of the clavicle after nonoperative treatment. In all 4 patients fracture union had occurred with shortening associated with pain and ipsilateral glenohumeral dysfunction. The deformity was not associated with neurovascular dysfunction. On preoperative radiographs the shortening of the malunited clavicle was between 0.9 and 2.2 cm compared with the contralateral clavicle. all patients underwent an extension osteotomy of the clavicle with interposition of an autogenous iliac crestbone graft secured with a plate and screws. The length of follow-up was 1 to 4 years in 3 cases and 6 weeks in 1 case. The functional outcome was evaluated with the Constant-Murley and University of California-Los Angeles scales. All patients had immediate pain relief after osteotomy and correction of the deformity. Shoulder function rapidly improved and functional outcome was good in 3 of the 4 patients. In cases of shoulder function impairment associated with malunited clavicular fractures, extension osteotomy combined with autogenous bone grafting is likely to produce good results.

Adult↗

PubMedDate not supplied

Outcome after primary and secondary hemiarthroplasty in elderly patients with fractures of the proximal humerus.

Thirty-nine consecutive patients with 3- and 4-part proximal humeral fractures and fracture dislocations were treated with hemiarthroplasty. After an average of 42 months (range 5 to 98 months) of follow-up, 17 women and 8 men (average age 64.5 years) were evaluated with the University of California-Los Angeles (UCLA) scale, the Constant-Murley scale, the Hospital for Special Surgery (HSS) scale, and the visual analogue scale. Fair, good, or excellent results were achieved in 80% of the patients on the UCLA and Visual scales, in 72% of the patients on the HSS scale, and in 44% of the patients on the Constant-Murley scale. The highest correlation was between the HSS score and the Visual analogue score. According to the UCLA and Constant-Murley results, the outcome after early (<4 weeks) humeral head replacement was significantly better than after late (> or =4 weeks) humeral head replacement (UCLA score, P=.02; Constant-Murley score, P=.01). After early hemiarthroplasty active forward flexion was significantly better (P=.035). Thus the decision to perform prosthetic humeral head replacement in elderly patients should be made as early as possible after trauma.

Aged↗

PubMedDate not supplied

[Induction of bone tissue on different matrices: an in vitro and a in vivo pilot study in the SCID mouse].

AIM: Three resorbable biomaterials were evaluated regarding proliferation and osteogenic differentiation of human bone marrow stromal cells (BMSC) in vitro. In a second step, the new biomaterial, calcium-deficient hydroxyapatite (CDHA), was tested in a pilot in vivo study by subcutaneous implantation in the severe combined immunodeficiency (SCID) mouse. METHODS: CDHA, beta-tricalcium phosphate (beta-TCP), and demineralized bone matrix (DBM) were seeded with human BMSC and cultured in osteogenic supplements for 3 weeks. In the pilot in vivo study, CDHA was seeded with BMSC and kept in osteogenic media for 2 weeks (group A) before subcutaneous implantation in 8 SCID mice for 3 and 8 weeks. In addition, CDHA seeded with BMSC without prior osteogenic induction (group B) and empty ceramics were implanted in each mouse. RESULTS: Total protein content and the values for specific alkaline phosphatase (ALP) increased significantly in vitro on all matrices, but no significant difference between the groups was noted. In the pilot in vivo study all ceramics were well penetrated by cells. After 8 weeks 2 of 4 samples in group B and 1 of 4 samples in group A revealed cells resembling hypertrophic chondrocytes. Specific ALP was higher in the group B (p = 0.012, Z = - 2.5) compared to empty ceramics. There were no significant differences between groups A and B. Differences between group A and the empty control did not become significant (p = 0.069, Z = - 1.8). CONCLUSION: All three matrices promoted BMSC proliferation and differentiation to osteogenic cells in vitro. Human BMSC on CDHA showed signs of osteogenic differentiation after subcutaneous implantation into SCID mice.

Adolescent↗

PubMedDate not supplied

[Indications and implementation of recommendations of the working group "Tissue Regeneration and Tissue Substitutes" for autologous chondrocyte transplantation (ACT)].

For the treatment of full-thickness articular cartilage lesions of the knee joint, as a result of trauma or osteochondritis dissecans, a variety of biological reconstruction techniques have been developed. Different studies, some of which were performed as randomised, prospective clinical studies, showed that the autologous chondrocyte transplantation (ACT) provides the most satisfying and reliable method of cartilage reconstruction in the adult when applied to defects exceeding 4 cm (2). Based on these results, ACT seems to be of economic benefit, as the risk of developing osteoarthritis correlates significantly with the size of the cartilage defect, when not treated properly and in time. Surveying the studies on basic scientific aspects of ACT, cartilage defect animal models and clinical studies, it can be concluded that clinical results of ACT depend on a variety of factors. In this review, published by the joined advisory board of the German Societies of Traumatology (DGU) and Orthopaedic Surgery (DGOOC), we summarize the current knowledge available and the state of the art concerning ACT. Especially we discuss the advantages of different procedures, methods for treating knee cartilage defects and factors that influence the outcome of the different treatment regimens, with the aim to develop guidelines for the correct indication and application of the ACT.

Adult↗

PubMedDate not supplied

The proliferative response of isolated human tendon fibroblasts to cyclic biaxial mechanical strain.

At the cellular level, dynamic strain plays a key role in cell stimulation and organization of the extracellular matrix. Although positive effects of physical strain on tendon tissue are well known, little knowledge exists on how mechanical strain affects tendon cells. In this study, human tendon fibroblasts from patellar tendon were cultured on silicone dishes. Subsequently, cyclic biaxial mechanical strain was applied to the dishes for 15, 30, and 60 minutes using a specially developed cell stretching system. After the fibroblasts were strained, cells were tested for proliferation at 6, 12, and 24 hours. As a control, cells were grown on silicone dishes but did not receive any strain. A biphasic response in proliferation was observed for the 15- and 60-minute strain periods: at 6 hours and 24 hours there was more proliferation than at 12 hours. After a strain duration time of 30 minutes, a lower proliferation rate was measured compared with control levels. This study shows that application of mechanical stress to tendon fibroblasts resulted in an alteration of cellular proliferation depending on the stress time. Our results may implicate future modifications in the treatment of ligament and tendon injuries.

Adult↗

PubMedDate not supplied

Healing of the patellar tendon autograft after posterior cruciate ligament reconstruction--a process of ligamentization? An experimental study in a sheep model.

Forty-eight skeletally mature sheep underwent posterior cruciate ligament reconstruction with free patellar tendon autografts in one knee; the contralateral knee served as a control. Immediate rehabilitation without immobilization followed. Autograft healing was evaluated by histologic, roentgenographic, and biomechanical techniques up to 2 years postoperatively. After implantation, the autograft tissue underwent necrosis and degeneration, followed by a gradual healing process comprising revascularization, cellular migration, and formation of an extracellular matrix. The autograft bone pegs were osseously incorporated by 6 weeks. After an initial loss of strength, the material properties of the operated knee recovered to only about one-third that of the control. Better alignment of the collagen fiber bundles resulted in increased material properties, up to approximately 50% of the control at 52 weeks. After 2 years, the autograft tissue was found to differ structurally and mechanically from a ligament, suggesting that the autograft may never approach normal ligament characteristics. Degenerative alterations, the wide-spread presence of type III collagen, and abnormal accumulations of glycosaminoglycans in the autograft correlated with a maximum stress of 60% and an elastic modulus of 70% of the control. Although ligamentization was not seen, the staging of autograft healing into different phases based on distinct morphologic manifestations (necrosis, revitalization, collagen formation, and remodeling) and correlating with changing mechanical properties may provide a rationale for rehabilitation protocols with a realistic evaluation of the loading capacity of the replacement tissue.

Animals↗

PubMedDate not supplied

Collagen fibril organization in the patellar tendon autograft after posterior cruciate ligament reconstruction. A quantitative evaluation in a sheep model.

We replaced the posterior cruciate ligament in 30 skeletally mature sheep with a patellar tendon autograft using the central third of the ipsilateral patellar tendon. The healing autograft was compared with the contralateral posterior cruciate ligament and the patellar tendons and posterior cruciate ligaments of nonoperated animals. The collagen fibril diameters were analyzed using transmission electron photomicrographs of fibril cross sections taken at six periods during the 2 years after surgery. The patellar tendon and posterior cruciate ligament were characterized by a broad, nongaussian distribution of collagen fibril diameters. The autografts shifted to a unimodal distribution by an increase of small-diameter collagen fibrils. The frequency of small-diameter fibrils measuring up to 100 nm was 99% after 2 years. At that time, these small-diameter fibrils represented 91.6% of the area covered by collagen fibrils. The mean diameter of the collagen fibrils in the autografts significantly decreased to 45% of the controls at Week 26 and remained at this level until the end of this study. The percentage of area covered by collagen fibrils per 1 micron 2 was 78% of the controls 2 years post-operatively. This study suggests that the patellar tendon autograft could not reproduce the collagen fibril organization of the posterior cruciate ligament. This may be a biologic factor responsible for inconsistent results in posterior cruciate ligament replacement.

Actin Cytoskeleton↗

PubMedDate not supplied

Alterations of glycosaminoglycans during patellar tendon autograft healing after posterior cruciate ligament replacement. A biochemical study in a sheep model.

In each of 30 skeletally mature sheep, the posterior cruciate ligament was replaced in one knee by a free patellar tendon autograft using the central third of the ipsilateral patellar tendon. The healing autograft was compared with the contralateral posterior cruciate ligament and the patellar tendons and posterior cruciate ligaments of nonoperated animals. The content of glycosaminoglycans, chondroitin sulfate disaccharides, and dermatan sulfate disaccharides was assessed biochemically at six periods during the 2 years after surgery. The total glycosaminoglycans and chondroitin sulfate disaccharides in the native posterior cruciate ligament was threefold that in the native patellar tendon. In contrast, the amount of dermatan sulfate disaccharides was similar in both the native tendon and native ligament. In the autograft, glycosaminoglycans and chondroitin sulfate disaccharides increased significantly to about 144% and 172%, respectively, of the contralateral posterior cruciate ligament at Week 104. The dermatan sulfate disaccharides in the autograft also showed a significant increase up to Week 26, followed by a remarkable but not significant decrease until the end of the study. In the contralateral posterior cruciate ligament, the dermatan sulfate disaccharides increased significantly between Weeks 52 and 104. Thus, the amount of dermatan sulfate disaccharides was similar in both the autograft and the contralateral posterior cruciate ligament after 2 years. This study suggests that the patellar tendon autograft did not completely assume the biochemical properties of the posterior cruciate ligament.

Animals↗