Apparatus for applying sustained tension on tether in treatment site includes a positioning mechanism, gripping mechanism and pressurized fluid actuated mechanism. The positioning mechanism is operable to position the pressurized fluid actuated mechanism at a fixed distance relative to treatment site, and to engage a target at treatment site and secure the tether proximate to the target. The gripping mechanism is operable to selectively grip the tether and maintain tether when tether is held in tension. The pressurized fluid actuated mechanism is selectively operable to apply desired pulling force on gripping mechanism directed away from treatment site so as to transmit and apply in a sustained manner the desired pulling force on the tether independently from the tether displacement and place it under desired level of tension while the tether is being secured.