Adductor-related groin pain is the most common type of groin pain in athletes, and pain at the proximal adductor longus insertion is a key finding in the diagnosis of longstanding groin pain. "Tightness" or "shortening" of the adductor longus is considered both a cause and effect of pain, that can lead to increased tension at the proximal insertion, thus playing a role in the persistence of longstanding adductor-related pain. For patients who do not respond sufficiently to non-surgical procedures, an adductor longus tenotomy is a surgical option that is considered to reduce tension at the proximal adductor longus insertion assisting in reduction of pain and return to sport.

The bent knee fall out test (BKFO) is one of the most commonly used tests to test adductor flexibility. This test involves a combined hip movement with hip flexion, abduction, and external rotation, and a high result is generally considered to be related to adductor muscle "tightness", specifically that of the adductor longus. It is uncertain whether the BKFO test is actually measuring adductor muscle flexibility or hip joint range of motion, as the test results may also be affected by a femoral head cam morphology. A slightly different test, called the Patrick FABER's test, involves a similar movement and is mainly used as a hip joint pain provocation test.

By cutting the adductor longus tendon, thereby removing the effect of potential adductor longus "tightness", it will be possible to show if and how much the flexibility of this muscle affects the BKFO test results. This will assist in future considerations of what this test is actually testing.

The aim of this study is to investigate the immediate effect of an adductor longus tenotomy on the results of the bent knee fall out test.