Pincer impingement is a type of hip “pinching” problem caused by extra coverage of the femoral head by the acetabulum (hip socket). It is commonly discussed under the broader term femoroacetabular impingement (FAI). It can contribute to hip or groin pain, limited motion, and mechanical symptoms in some people. It is used in orthopedics, sports medicine, radiology, and physical therapy to describe a specific hip shape and contact pattern.

Pincer deformity is a hip shape variation where the socket (acetabulum) covers the ball (femoral head) more than typical. It is commonly discussed as a cause of femoroacetabular impingement (FAI), a mechanical conflict during hip motion. The term is used in orthopedic clinics, sports medicine, and hip imaging reports to describe a structural finding. It can be associated with hip pain, labral injury, and cartilage wear in some people.

Piriformis tendon is the strong, fibrous end of the piriformis muscle where it attaches to bone. It sits deep in the buttock and typically connects the piriformis muscle to the upper femur near the greater trochanter. Clinicians discuss it in hip anatomy, deep buttock pain evaluations, and some hip and sciatic-nerve–related conditions. It may also be referenced during certain hip surgeries where the short external rotators are exposed or repaired.

Piriformis stretch is a general term for movements that lengthen the piriformis muscle in the deep buttock. It is commonly used in physical therapy and sports medicine for buttock pain and certain patterns of sciatica-like symptoms. It can be performed in several positions, such as lying on the back, sitting, or standing. Clinicians often pair it with an exam of the hip, pelvis, and lower back to identify the likely source of symptoms.

Piriformis syndrome is a clinical term used when buttock pain and sciatica-like symptoms are thought to come from the piriformis muscle region. It is most commonly discussed in orthopedics, sports medicine, and physical therapy when hip-area structures may be irritating the sciatic nerve. The idea is simple: a deep buttock muscle may contribute to nerve irritation and referred pain down the leg. Because several conditions can look similar, Piriformis syndrome is often considered a working diagnosis after other causes are assessed.

Piriformis is a small, deep muscle in the back of the hip and buttock. It helps move and stabilize the hip during walking, sitting, and twisting. Clinicians use the term Piriformis when describing hip anatomy, exam findings, and some causes of buttock pain. It is also referenced in physical therapy plans and in image-guided injections around the hip.

Pigmented villonodular synovitis hip is an uncommon condition that affects the lining of the hip joint. It involves an overgrowth of synovium, the tissue that normally produces joint fluid for lubrication. It is commonly discussed in orthopedics and radiology when evaluating unexplained hip pain and swelling. Many clinicians also refer to it within the broader category of tenosynovial giant cell tumor (TGCT).

Perthes lateral pillar classification is a way clinicians describe how much of the femoral head is affected in Legg–Calvé–Perthes disease. It is based on what the hip looks like on an X-ray at a specific stage of the condition. The system groups hips into categories that broadly reflect severity and expected shape during healing. It is commonly used in pediatric orthopedics and in research to communicate prognosis in a standardized way.

Perthes disease is a childhood hip condition where the ball of the hip joint temporarily loses part of its blood supply. This can weaken the top of the thighbone (the femoral head) and change its shape over time. It is most commonly discussed in pediatric orthopedics, sports medicine, radiology, and physical therapy. People often encounter the term when a child develops a limp, hip or groin pain, or reduced hip motion.

Periprosthetic joint pain is pain felt in or around a joint that has an artificial implant. It most often refers to symptoms after hip or knee replacement surgery. Clinicians use the term to describe a problem area, not a single diagnosis. It signals the need to consider implant-related and non-implant-related causes.