Despite well-established bone-grafting techniques, large bone defects still represent a challenge for orthopaedic and reconstructive surgeons. Efforts have therefore been made to develop osteoconductive, osteoinductive and osteogenic bone-replacement systems. According to its original definition, tissue engineering is an 'interdisciplinary field that applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function'. It is based on the understanding of tissue formation and regeneration, and aims to grow new functional tissues rather than to build new spare parts. This review focuses on the principles of tissue engineering applied to the creation of bioartificial bone tissue. Important aspects, such as osteogenic cells, matrix materials, inter- and intra-cellular communication, growth factors, gene therapy and current concepts of bone tissue engineering are reviewed. First clinical applications are discussed. An outlook provides insight into the possible future perspectives of bone tissue engineering.

The dislocated four-fragment fracture of the proximal humerus is a problematic fracture. In this study we evaluated shoulder function after implantation of a shoulder hemiprosthesis of the anatomical generation. The evaluation was based on a case-control study in which the following information was gathered: epidemiology, Constant-Murley score, compliance score, radiological results, and a summary of complications. Twenty shoulder prostheses were implanted between September 2000 and August 2002. After an average follow-up time of 14 months, the average Constant score was 52. The score for the opposite shoulder was 91 points. The function found to be most limited was shoulder movement. The subjective estimation of shoulder function had a mean value of 49% and correlated with the Constant score. Fourteen of the patients exhibited a postoperative defect in the tuberculum majus. Implantation of shoulder hemiprostheses allows treatment of four-fragment fractures of the humerus head in older patients, whereby limitations of mobility and function are to be expected.

Pelvic disruptions are rare in children caused by the flexible anchoring of bony parts associated with a high elasticity of the skeleton. Portion of pelvic fractures in infants is lower than 5% even when reviewing cases of specialized centers. The part of complex pelvic injuries and multiple injured patients in infants is higher when compared to adults, a fact caused by the more intense forces that are necessary to lead to pelvic disruption in children. Combination of a rare injury and the capability of children to compensate blood loss for a long time may implicate a wrong security and prolong diagnostic and therapeutic procedures--a problem that definitely should be avoided. Three cases were analyzed and established algorithms for treatment of patients matching these special injury-features demonstrated. A good outcome may only be achieved when all components of injury pattern get recognized and treatment is organized following the hierarchy of necessity. Therefore in the time table first life-saving steps have to be taken and then accompanying injuries can be treated that often decisively influence life quality. As seen in our cases unstable and dislocated fractures require open reduction and internal fixation ensuring nerval decompression, stop of hemorrhage and realizing the prerequisite for effective treatment of soft tissue damage. The acute hemorrhagic shock is one of the leading causes of death following severe pelvic injuries. After stabilization of fracture, surgical treatment of soft tissue injuries and intraabdominal bleeding sources the immediate diagnostic angiography possibly in combination with a therapeutic selective embolization is a well established part of the treatment. The aim of complete restitution can only be accomplished by cooperation of several different specialists and consultants in a trauma center.

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