Hip and knee pain are common among all people. Athletes are at increased risk due to excess forces on their joints. Knee pain is usually due to local pathology and is not commonly referred to other sites. Hip pathology commonly causes referred pain in the buttocks and lower extremity, and pain felt in the hip may be due to extraarticular pathology. The differential diagnosis for hip or knee pain is broad but a focused history and physical examination will often lead to the diagnosis (Table 179-1).
Table 179-1 Suggested Clues for the Differential Diagnosis of Hip and Knee Pain |Favorite Table|Download (.pdf)
Table 179-1 Suggested Clues for the Differential Diagnosis of Hip and Knee Pain
Determine the location of the pain to narrow down the potential diagnosis.
Determine the activities that bring on the pain.
The knee “giving out” or “buckling” generally is due to pain and reflex muscle inhibition rather than an acute neurologic emergency. This complaint may also represent patellar subluxation or ligamentous injury and joint instability.
Poor conditioning or quadriceps weakness generally causes anterior knee pain of the patellofemoral syndrome; therapy should address this weakness.
Locking of the knee suggests a meniscal injury, which may be chronic.
A popping sensation or sound at the onset of pain is reliable for a ligamentous injury.
A recurrent effusion after activity suggests a meniscal injury.
Pain at the joint line suggests a meniscal injury.
Meralgia paresthetica is a compressive inflammation of the lateral femoral cutaneous nerve causing pain in the hip, thigh, or groin, burning or tingling paresthesias, and hypersensitivity to light touch. ED treatment includes addressing the source of nerve irritation (eg, obesity, pregnancy, tight pants belt) and provision of NSAIDs. Obturator nerve entrapment usually occurs after pelvic fractures or in athletes with a fascial band at the distal obturator canal, which causes pain in the groin and down the inner thigh. Surgery may be needed for pain relief. Ilioinguinal nerve entrapment is associated with pregnancy or hypertrophy of the abdominal wall musculature. Piriformis syndrome, irritation of the sciatic nerve from the piriformis muscle, manifests as pain in the buttocks and hamstring muscles that is worsened by sitting, climbing stairs, or squatting. ED treatment is conservative for all of these nerve entrapment syndromes.
Abscess of the psoas muscle may present with abdominal pain radiating to the hip or flank, fever, and limp. The diagnosis is made by CT. Treatment includes antibiotics and surgical drainage.
Hip and knee bursae may cause localized pain due to inflammation, infection, rheumatologic disorders (psoriatic arthritis, rheumatoid arthritis, ankylosing spondylitis) or crystalline disease (gout, pseudogout). Infection may be difficult to distinguish clinically from more benign disorders. (Table 179-2) Treatment is directed at the underlying cause. NSAIDs, rest, heat, and time are the basis of treatment for inflammatory conditions. Steroid injections into readily accessible bursa may be useful ...