Traditionally, the Clam exercise & the Figure 4 are used to strengthen the hip muscles (Glute Medius, Minimus & Maximus) in order to improve hip control. They are often used as an early stage of rehabilitation after hip surgery to facilitate control around the femero‐acetabular region. The theory is that the external rotation moment assists in strengthening the gluteal muscles & posterior rotators of the hip.
More recently, clinicians have been finding that this type of exercise tends to aggravate the patient. Post-operative Hip patients anecdotally say they have stopped performing the Clam as a home exercise as it seems to be giving them posterior Hip pain. Previously diagnosed as perhaps a sacroiliac injury or a trochanteric bursitis, we now know this to be (often) a Glute Medius and/or inimus tendinopathy. Glute Medius and /or Minimus tendinopathy is now accepted as the most prevalent pathology in those presenting with pain & tenderness over the greater trochanter (Grimaldi & Fearon, 2015). Tears or degenerative changes are found in MRI studies at the attachment (deep undersurface of tendon, as seen in supraspinatus tendinopathy) where they adhere to the anterior & superior capsule of the hip joint. This attachment augments hip joint stability & stabilises the head of the femur in the acetabulum during the gait cycle.