The present invention relates to a new method for repairing human or animal tissues such as cartilage, meniscus, ligament, tendon, bone, skin, cornea, periodontal tissues, abscesses, resected tumors, and ulcers. An optical repeater is adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. Speakers mounted on the enclosure can share a single audio signal. The 2n-PSK and 2p-PSK optical signals are orthogonally polarized and transmitted. The rotary arm, when viewed from the end of a stall, may be pitched forward or rearward. A helical spring is provided coaxially with the arm to urge the links to an initial datum position, and to distribute the bending over the links of each segment.