The PRTS allows for efficient treatment of intraarticular fractures with PiP involvement. Although standardized positioning of the wires is important, proximal position of the retraction only increased forces for 30 degrees flexion.

Bone-anchored hearing aids are a standard option in rehabilitation of patients with conductive or mixed hearing loss, and also CROS fitting. However, the skin-penetrating bone anchor repeatedly gives reason for discussion about the risk of infection of surrounding tissues as a major cause of malfunction. In the present study, explanted bone anchors with surrounding bone and soft tissue were examined and compared with the morphology of lost implants. The anchors originated from five patients. Two needed explantation due to deafness with the need of cochlea implantation. A third patient underwent explantation due to meningeal irritation by the bone anchor. Another patient lost the implant due to mechanical stress shortly after implantation. The last implant was lost in a child without apparent reason. All implants were clinically free of infection and had been stable for a median implantation period of 12 months. During the explantation procedure, the fixtures were recovered together with the attached soft tissue and bone. The specimens were examined by light microscopy or scanning electron microscopy (SEM). Sectioning for light microscopy was performed with a diamond-coated saw microtome. Histopathologic examination of the surrounding skin and subcutaneous soft tissue showed slight inflammation in one case only. The bone was regularly vital, presenting no signs of inflammation. The threads of the fixtures were filled with bone, with particularly strong attachment to the flank of traction. The SEM investigation exposed the ultrastructural interaction of bone with the implant surface. Filiform- and podocyte-like processes of osteocytes attach to the implant; lost implants did not reflect these features. Implant integration involves both osseointegration as well as soft tissue integration. Titanium oxide as the active implant surface promotes this integration even in unstable implants. The morphologic analysis exposed structural areas of the implant with weak bone-to-metal contact. Optimized implant design with modified surface and threads may additionally improve osseointegration of hearing aid bone anchors.

The results of treating fracture dislocations of the proximal interphalangeal joint are often unsatisfactory for the patient because conservative methods cannot prevent stiffness of the joint. Thus, early functional treatment with external fixation systems is increasingly favoured. This therapy combines the principles of ligamentotaxis and the possibility of early movement of the injured joint. The frequently modified pins and rubbers traction system is especially effective. It is cheap, easy to apply, and well accepted by patients due to its light weight and small size. This paper gives an overview of the therapeutic options and the clinical results of treating fractures of the proximal interphalangeal joint.

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