An osteochondral defect (OCD) of the talus often has a severe effect on the quality of life of young patients. This thesis aims to evaluate several aspects of etiology and treatment of talar OCDs. Part I of the thesis describes the natural history of OCDs and the development of subchondral bone cysts. Part II contains chapters on different surgical treatment options of talar OCDs, the postoperative treatment and rehabilitation after arthroscopic debridement and microfracture, and the role of the subchondral bone after surgical treatment. Part III finalizes the thesis with a general discussion and a summary.

This thesis deals with current issues in the management of trauma and sports injuries of the elbow. Common sports injuries of the elbow involve ruptures of the distal biceps tendon and the ulnar collateral ligament. Various surgical techniques in their treatment are discussed. The radial head is most frequently fractured after trauma of the elbow and may require operative fixation or replacement by prosthesis. Different kinds of radial head prosthesis are critically evaluated and compared.

The research described in this thesis evaluated the management of acute hamstring injuries including prognosis, treatment and return to play decision making. We firstly investigated whether some commonly used clinical tests to assess hamstring flexibility and strength are reliable in subjects with acute hamstring injuries. For this purpose we determined the intertester reliability of hamstring flexibility measurements with the active and passive knee extension test (chapter 2). In chapter 3 we determined the interrater reliability and the prognostic value of hamstring handheld dynamometry strength measurements.