Plicae are folds in the membrane that surrounds a joint. A plica doesn’t necessarily cause problems. However, a plica can sometimes get caught in the joint as it moves, causing clicking, pain, and problems with some movements. Plicae are often found in the knee. So far it has been rare to find plicae in the hip.
These authors report on the case of a hip plica in a 19-year-old cross-country runner. Running had become painful for her, even though she had not had a specific injury. Her hip clicked as it moved, and she had problems standing up from a crouch. MRIs showed some abnormalities in her hip joint, so the doctor did an arthroscopy. Arthroscopy involves inserting a tiny camera into the joint through a small incision. The camera lets a doctor actually see the inside of the joint.
In this case, the arthroscope very clearly showed a plica in the runner’s hip joint. It also showed damage to the cartilage where the plica had been sticking in the joint. Her doctor used the arthroscope to remove the plica. Six months later, the patient had returned to running without pain. She could use her hip normally, and there was no clicking when it moved.
The authors note that there are only five reported cases of hip plicae that caused pain. But they think that hip plicae might go undiagnosed most of the time. As more doctors use arthroscopes in the hip, they believe that more hip plicae will be found. That is what happened with the knee. Knee plicae were once thought to be rare, but now they are often found when doctors use an arthroscope during knee surgery.