Telescopic test is useful to diagnose?

In supine position, hip and knee are flexed as much as 90 degree and thigh is pulled up and pushed down. Even in normal condition a slight amount of excursion of trochanter can be felt by other hand. If excursion is more, then this indicates instability of the hip joint such as: Old unreduced posterior dislocation Loss of neck and head in old fracture neck femur paralytic hip Ref: Clinical ohopedic Diagnosis: Sureshwar Pandey 2/e, Page 262.