CASE 22 – Left Medial Thigh Pain
A 16-year-old active hockey and soccer player comes into your office with a two-week history of left medial knee pain, aggravated with climbing stairs. There is no history of trauma.
He had a similar episode four months ago, of pain over the left medial knee which resolved spontaneously.
You find on exam that the left knee is warm over the medial femoral condyle, and there is a large fixed protrusion over this area. Otherwise, there is no knee joint effusion, no ligamentous laxity, and normal patellar tracking. You also find he has no joint line tenderness, full range of motion bilaterally, and normal menisci.
X-Ray findings below:
Figure 1. Tunnel view of the left knee
Figure 2. Lateral view of the left knee
Figure 3. Skyline view of the left knee
Figure 4. Bilateral AP view of knees
An osteochondroma is a bony spur with a cartilage cap, arising from the surface of a bone. It is also known as an osteocartilagenous exostosis. These lesions are generally idiopathic, although there can be an association with previous surgery, radiotherapy, and the genetic condition hereditary multiple osteochondromas or hereditary multiple exostoses (HMO/HME). These growths are the most common type of benign bone tumors, making up approximately 30 % of all benign bone tumors.
Osteochondromas tend to present during the second decade of life, and are more prevalent in males. These bony spurs grow until skeletal maturity. The distal femur is the most common location of occurrence, although they can show up in the humerus, tibia, vertebra and even in the form of subungal exostosis (e.g. hallux), amongst other places.
Figure 5. Typical and less typical locations of osteochondroma lesions. Case courtesy of A.Prof Frank Gaillard, Radiopaedia.org, rID: 16304
History and physical exam:
Most osteochondromas are asymptomatic, and are found incidentally on x-rays. Symptomatic presentation is often due to mechanical effects, as in our 16-year-old patient, where the lesion was rubbing against adjacent soft tissue, causing inflammation, swelling and thus pain with certain activities. These lesions can also present with symptoms related to complications (see below). On examination, there may be a palpable mass as with our patient, or the patient may have mechanical symptoms.
Osteochondromas are easily diagnosed on plain radiographs which will show a broad based (sessile) or narrow stalk (pedunculated) osseous spur which is continuous with, and arising from the surface of the affected bone. MRI can be used if malignant transformation is suspected (see complications). Other less common imaging modalities to assess osteochondromas include CT, ultrasound and bone scan.
The treatment of osteochondromas is either conservative or operative. Most osteochondromas are treated conservatively and observed with yearly x-rays if the patient is asymptomatic. If pain is present, analgesia is added. However, surgery can be performed if the patient is extremely symptomatic or functionally limited, or his/her growth is affected, or he/she is dissatisfied with the osteochondroma cosmetically. These surgeries are preferably done after skeletal maturity to prevent recurrence.
Depending on the location and growth, osteochondromas can cause complications such as by affecting the growth plates of children leading to asymmetric growth or deformities. They can also cause pneumothorax, or even spinal canal compression. Other complications include tendon compression, malignant transformation to chondrosarcoma (suspected when there is growth and pain from the lesion after skeletal maturity), bursa formation and bursitis, neurovascular compression, fracture through the lesion, and recurrence.
Figure 6. Fractured pedunculated osteochondroma of distal femur. Case courtesy of Dr Michael Sargent, Radiopaedia.org, rID: 5979
Figure 7. Sessile (broad-based) osteochondroma of distal tibia. Case courtesy of Dr Maulik S Patel, Radiopaedia.org, rID: 17436
Diagnosis: Osteochondroma of the left femur
Treatment: Anti-inflammatory medication (NSAIDS) on an as needed basis, with follow up in four weeks’ time. If our patient continues to be symptomatic, we will refer to our orthopedic colleagues for an assessment and possible resection.
Dr. Annie Qu (Sept 9, 2019 – PR ND)