Symptoms
Patient's commonly complain of deep pain in the groin/anterior aspect of the hip but can also have associated symptoms in the muscles around the hip joint. This is commonly worse with activities where they stand for long periods of time or perform sporting activities with high impact to the hip joint.
To confirm a hip dysplasia diagnosis, a healthcare provider will order x-rays and potentially magnetic resonance imaging exams or computed tomography scans to get more information about the health of the hip joint.
Cause
Hip dysplasia is most common in females. Patients with more subtle dysplasia that does not involve dislocation as a child but still has a smaller than normal hip socket can develop pain with activities in their teenage or adult years. This is due to mechanical overload of a socket that is smaller. This causes extra stress on the soft tissues around the joint including the cartilage, labrum, and muscles and ligaments.
In patients with hip dysplasia, the worry is that the mechanical overload over time will lead to arthritis forming in the joint. This is the most common reason for a female under the age of 50 to need a hip replacement surgery.
Treatments
Non-Surgical 
There are non-surgical options such as injections, medications, and physical therapy to address the modifiable variables contributing to hip dysplasia pain. 
Surgical 
In patients who have closed growth plates of their hip, the treatment of choice for hip dysplasia is a periacetabular osteotomy. This reorients the hip socket so there is more hip socket in the weightbearing part of the joint. This can relieve pain and hopefully decrease the amount of degenerative change that happens over time. Sometimes there is also a tear in the labrum at the edge of the socket and this can be addressed at the same time with hip arthroscopy. Patients can generally return to activities and sports after their hip dysplasia is fixed. In patients with hip dysplasia that also have arthritis change to their hip from wear and tear over the years, the pain is better treated with nonoperative measures or hip replacement surgery. This is because the osteotomy surgery does not work in the setting of arthritis changes.