A 13-year-old boy is brought to the office due to right knee pain. Several weeks ago, he developed mild anterior knee pain that has gradually worsened and now causes him to limp. The pain has significantly limited his participation in basketball practice. It is relieved by rest and can be reproduced when the patient straightens out his right knee while seated in a chair. Further evaluation reveals an avulsion fracture affecting a developing secondary ossification center due to muscle overuse. Which of the following structures is most likely involved in this patient's disease process?

Question

A 13-year-old boy is brought to the office due to right knee pain.  Several weeks ago, he developed mild anterior knee pain that has gradually worsened and now causes him to limp.  The pain has significantly limited his participation in basketball practice.  It is relieved by rest and can be reproduced when the patient straightens out his right knee while seated in a chair.  Further evaluation reveals an avulsion fracture affecting a developing secondary ossification center due to muscle overuse.  Which of the following structures is most likely involved in this patient's disease process?

Quizplus · Accepted Answer

11ec160b_35ea_6e70_9249_d96fd1fe2de9_MD0001_00 This patient likely has Osgood-Schlatter disease (OSD), a common cause of knee pain in adolescent athletes due to overuse of the quadriceps muscle group (ie, rectus femoris, vastus intermedius, vastus medialis, vastus lateralis). The quadriceps is responsible for leg extension at the knee and inserts into the tibial tubercle via the patellar ligament. The tubercle forms as a secondary ossification center (apophysis) of the tibia, and the cartilaginous nature of the developing tibial tuberosity in childhood makes it more prone to injury compared to the fully ossified bone in adults. OSD most commonly occurs after a growth spurt due to increased tension in tendons and ligaments caused by the rapidly elongating bone. Repetitive quadriceps contraction (eg, sports activity) then results in chronic avulsion of the tibial tubercle. Clinical findings include tenderness and swelling at the tibial tubercle and pain that worsens with knee extension (eg, jumping). Imaging frequently shows an elevated and fragmented tibial tubercle. (Choice A) The anterior intercondylar area (ie, fossa) is the space between the medial and lateral condyles of the tibia. The anterior cruciate ligament (ACL) attaches at this specific location and is crucial for knee stabilization. ACL injury typically results from sudden deceleration with direction change and presents as acute knee pain, swelling, and instability that prevents weight-bearing. (Choice B) The sartorius muscle is the longest muscle in the body. It originates from the anterior superior iliac spine and inserts with the pes anserinus onto the anteromedial tibia shaft near the tibial tuberosity. Pes anserinus bursitis commonly occurs in runners and causes anteromedial knee pain. (Choices C and D) The tendon of the biceps femoris (part of the hamstrings) inserts at the styloid process of the head of the fibula. The medial condyle of the tibia is the insertion site for the semimembranous muscle, the most medial of the hamstring muscles. The hamstring muscles are involved in knee flexion and hip extension. Educational objective: The quadriceps muscle group is connected to the patella, which is attached to the tibial tubercle by the patellar ligament. Repetitive quadriceps contraction (eg, jumping) in adolescents can result in Osgood-Schlatter disease, which is characterized by focal anterior knee pain and swelling due to chronic avulsion of the tibial tubercle. __________ References: Precise risk factors for Osgood-Schlatter disease. (http://www.ncbi.nlm.nih.gov/pubmed/26133498) Osgood Schlatter syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/17224661)

A 13-Year-Old Boy Is Brought to the Office Due to Right