A 27-year-old man comes to the office due to recent onset of right knee pain. The pain developed 2 weeks ago while the patient was training for a triathlon. The pain is sharp and is on the medial side of the knee. It has been continuous but is exacerbated by exercise and improves partially with ice and rest. The patient has had no associated knee locking. He otherwise feels well and has no chronic medical conditions. Vital signs are normal. On examination, there is localized tenderness at the medial tibia below the knee joint with no associated redness or warmth. A valgus stress test has no effect on the pain. The gait is normal. X-ray of the knee and tibia reveals no abnormalities. Which of the following is the most likely cause of this patient's knee pain?

Question

A 27-year-old man comes to the office due to recent onset of right knee pain.  The pain developed 2 weeks ago while the patient was training for a triathlon.  The pain is sharp and is on the medial side of the knee.  It has been continuous but is exacerbated by exercise and improves partially with ice and rest.  The patient has had no associated knee locking.  He otherwise feels well and has no chronic medical conditions.  Vital signs are normal.  On examination, there is localized tenderness at the medial tibia below the knee joint with no associated redness or warmth.  A valgus stress test has no effect on the pain.  The gait is normal.  X-ray of the knee and tibia reveals no abnormalities.  Which of the following is the most likely cause of this patient's knee pain?

Quizplus · Accepted Answer

11ec25c8_d315_0673_bc81_efac97557442_MD0003_00 This patient with medial knee pain and focal tenderness has pes anserinus pain syndrome. This condition is often referred to as anserine bursitis, but most patients do not have true inflammation in the bursa, and multiple regional structures can contribute to the pain. The pes anserinus is formed by the conjoined tendons of gracilis, sartorius, and semitendinosus. The anserine bursa is located anteromedially over the medial tibial condyle, distal to the joint line and deep to the pes anserinus. Pes anserinus pain syndrome can be caused by an abnormal gait, overuse, or trauma. Risk factors include obesity, diabetes mellitus, knee osteoarthritis, and angular deformity of the knee. Patients experience localized pain over the anteromedial tibia, which is often exacerbated by pressure from the opposite knee while lying on the side. Examination shows a well-defined area of tenderness over the medial tibial condyle just below the joint line; swelling, erythema, and induration are typically absent. The diagnosis is based primarily on clinical features, although x-ray can exclude concurrent osteoarthritis of the knee. Management includes quadriceps strengthening exercises and nonsteroidal anti-inflammatory drugs. (Choice A) The medial collateral ligament is usually injured acutely, typically from a blow to the lateral knee with the knee partially flexed. Tenderness is most evident at (rather than below) the joint line, and the valgus stress test maneuvers elicit pain and/or laxity. Patients also may have swelling and visible ecchymosis. (Choice B) Meniscal tears in young patients are typically caused by an acute rotational force on a planted foot. There is often an associated effusion and a sensation of instability. Examination findings include medial joint line tenderness and palpable locking or catching when the joint is rotated or extended while under load (eg, Thessaly test, McMurray test). Thessaly test McMurray test (Choice C) Patellofemoral syndrome is most common in women and presents with anterior (rather than medial) pain that is worsened by squatting, climbing stairs, or prolonged sitting. Examination findings are insensitive, but pain and crepitus may be elicited by extending the knee while compressing the patella. (Choice E) Prepatellar bursitis presents with pain and swelling directly over the patella, usually following trauma or extended periods of kneeling. Examination shows cystic swelling and tenderness over the patella, often with erythema and warmth. Educational objective: Pes anserinus pain syndrome presents with localized pain and tenderness over the medial tibial condyle. It is often associated with overuse; risk factors include obesity, diabetes mellitus, knee osteoarthritis, and angular deformity of the knee. The diagnosis is based on clinical features, although x-ray can exclude concurrent osteoarthritis. Management includes quadriceps strengthening exercises and nonsteroidal anti-inflammatory drugs. References: Anserine syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/21125167)

A 27-Year-Old Man Comes to the Office Due to Recent