An electrosurgical apparatus 100 for ligament tightening comprising an electrosurgical generator 104, a probe 118, a flexible shaft containing a coaxial transmission line, an applicator, a detector 1012, 1014 and a controller 106. The applicator has an energy delivery structure arranged to receive microwave EM from the coaxial transmission line and emit this into a treatment zone. The controller 106 is arranged to control an energy delivery profile of the microwave energy. The detector 1012, 1014 has a temperature sensor, imaging device and a power sensing module. The module detects a forward power signal from the generator 104 and a reflected power signal. The controller 106 is arranged to determine complex impedance, attenuation and phase constants of the body tissue. The apparatus has a cooling mechanism comprising an actuator to deliver coolant through a fluid feed conduit. The controller is arranged to detect the presence of nerve tissue.
