| Acetabulum | 'Socket' part of the pelvis (hip bone) |
| Abducted/adducted | Abduct is to move away from and adduct is to move towards the middle point of the body |
| Bilateral | Both hips affected |
| DDH | Developmental dysplasia of the hip |
| Developmental | Might not be present at birth but can present at some stage during childhood; related to growth of hip joint in line with rest of the body |
| Dislocated | The ball is completely outside of the socket |
| Dysplasia | The ball and socket do not fit together in their normal position through lack of growth |
| Femoral Head* | Ball shaped top of thigh bone |
| Femur* | Thigh bone |
| Instability | The ball and socket is not being held together sufficiently by the loose ligaments |
| Lax* | Loose |
| Orthopaedics | The medical specialty hip dysplasia is treated under which focuses on bones and joints |
| Osteotomy | Surgical procedure to reshape/repair either the ball or the socket |
| Reduction | Closed — ball and socket repositioned to normal position by specialist without surgery required. Open — surgical intervention required to reposition the ball and socket to normal position; necessary if tissue is in the way |
| Subluxated | The ball will move in and out of the socket but still rest partially within the socket |
| Ultrasound* | A technique which uses high-frequency sound waves to build up a picture of soft tissue and organs in the body |
| Unilateral | One hip affected |
| X-Ray* | A techinique which uses very low-dose radiation to image parts of the body, especially useful for imaging bones |
Further explanation of frequently used terms can be found on the steps charity website (steps-charity.org.uk).
(*) Sourced from aforementioned website.