A 32-year-old male patient presented to our clinic with chronic left knee pain that was ongoing for about 1.5 years. The patient visited several times our clinic and the other clinics; conservative treatment (including rest, knee brace, and ice application with NSAIDs) was recommended by various different doctors. The anamnesis, physical examination, and plain radiography were nonspecific. Early MRI findings mislead us to believe it is bone marrow edema. One and half years with noneffective treatment, the knee pain persisted. At the latest visit intra-articular osteoid osteoma was suspected and the knee MRI with CT was employed. Even though the diagnosis of intra-articular osteoid osteoma often presents a challenge for the surgeons, with a present awareness of intra-articular osteoid osteomas which lack the characteristic sclerotic lesions and nidus on plain X-rays and the aid of multislice CT, a correct diagnosis which warrants proper treatment can be achieved. The possibility of osteoid osteomas, especially in young adults with persistent knee pain with unknown reasons that show normal plain radiographs results, must not be overlooked. The treatment method of these lesions should be customized depending on the location of the lesion, experience of the surgeon, and cost of method.
Osteoid osteoma, first described by Jaffe in 1935 [
Approximately 13% of osteoid osteomas arise within the joint (intra-articular). Hip joint is the most commonly affected area, followed by the ankle, elbow, wrist, and knee [
Intra-articular location of the osteoid osteoma obscures classical symptoms and radiologic appearance, which, thus, can cause misdiagnosis and delayed proper treatment for the condition [
In this report, we would like to make a contribution to the literature by sharing our experience on a case with a lesion located on anteromedial tibia plateau (within joint capsule) and a delayed diagnosis by 1.5 years.
A 32-year-old male patient presented to our clinic with chronic left knee pain that lasted for about 1.5 years. The patient visited several times our clinic before conservative treatment (including rest, knee brace, and ice application with NSAIDs) was recommended by two different doctors. The pain persisted during resting period and got worse during the night. NSAIDs caused temporary and partial pain relief. No significant medical stories from the patient or his family were seen. Physical examination showed some swelling and tenderness on anteromedial side of the left knee. Meniscal tests were negative, while the left quadriceps muscle showed moderate atrophy with an intact range of motion. Left knee radiographs showed no abnormalities (Figure
Normal findings at plain radiography.
When patient’s MRI results were assessed, initial MRI of the patient, taken 1.5 years ago, at the beginning of the complaints, showed bone marrow edema. Second MRI, which is recent, showed a nidus-like view with bone marrow edema (Figure
T2 weighted images (a and c) showed the hypointense lesion (yellow arrow) located at tibia anteromedial plateau with ill-defined bone marrow edema; (b) T1 weighted image showed the well-defined bordered hypointense lesion (yellow arrow).
CT scans showed a small radiolucent zone, surrounded by reactive circumferential sclerosis, which is typical for osteoid osteoma (Figure
Coronal (a), axial (b), and sagittal (c) CT images showed the perinidal sclerosis with centrally calcified nidus (yellow arrow) consistent with an osteoid osteoma.
Under general anesthesia, pneumatic tourniquet was applied (350 mmHg) and a medial parapatellar incision was made. After opening the joint capsule, the Hoffa were stripped in the direction of lesion (towards medial), exposing the undersurface of anterior horn of medial meniscus. Intervention area was detected after the discolored and irregular lesion surface was marked (Figure
Intraoperative photo that shows surface discoloration over the lesion.
Histopathological examination of the surgically removed lesion confirmed the initial diagnosis of osteoid osteoma (Figure
Photomicrograph of the lesion revealing abundant osteoid formation characteristic of an osteoid osteoma [H&E, ×4 obj. (a), ×10 obj. (b)].
In this article, we would like to highlight the difficulties on the diagnosis of the intra-articular osteoid osteoma. This atypical presentation with uncharacteristic radiological findings and the lack of trauma history usually directs the surgeon not to order unnecessary MRI/CT images, which causes delay on correct diagnosis.
Szendroi et al.’s [
Another study done by Kattapuram et al. [
In addition to other authors, the low capability of producing new thick bone of the intracapsular periosteum was first underlined by Freiberger et al. [
These atypical anatomical, pathological, and physiological features of the affected intracapsular bone and adjacent synovium are all contributing factors in diagnosis delay of intra-articular osteoid osteoma. The patient can be subjected to redundant treatments such as unnecessary arthroscopies and/or arthrotomies with a delay in correct diagnosis and proper treatment [
As plain radiographs usually show no abnormalities in the joint, they have little value on the diagnosis. However, they are still required for elimination of other possible conditions and should be the first in line for diagnostic investigation in a normal diagnostic algorithm.
Another valuable investigation technique for classic extra-articular located osteoid osteomas is scintigraphy which shows the characteristic double density sign [
MRI images can also be misleading for the surgeon, as the detection of synovitis or bone marrow edema during the early stages of the disease might lead the surgeon to misdiagnose the condition as arthritis or stress fracture of the bone. As in our case, nidus appearance usually develops at the late stages of the disease and is not evident on MRI until that time. Krause et al.’s [
As opposed to our case, in the cases where the patient had a trauma or bruising history, the surgeons usually tend to suspect other causes such as meniscal tears, chondral lesions, and collateral ligament tears or bone bruising. In those situations, the surgeon is likely to order X-rays and MRI for diagnosis. Bone marrow edema view during early stages of the osteoid osteoma might lead the surgeon to misdiagnose the condition as a bone bruise or a stress fracture, therefore delaying the correct diagnosis, as in our case.
CT remains the method of choice for investigating intra-articular osteoid osteomas [
Recently, the new imagining methods such as SPECT/CT have gained popularity. SPECT/CT can be very useful especially in those cases when the osteoid osteoma is intra-articular and the X-ray and MRI are not informative. Sharma et al. [
Latter Squier et al. [
Farid et al. [
Even though there were several reports on intra-articular osteoid osteomas in the distal femur [
Despite the fact that CT-guided thermoablation is getting more and more popular for treating osteoid osteoma, it has several prerequisites such as assistance from a radiologist and the fact that the procedure has to be performed in either a CT room or an operating theatre equipped with a CT scanner. RF ablation might also cause cartilage degeneration when used for resecting subchondral osteoid osteomas [
In conclusion, here we presented an osteoid osteoma case that arises within knee joint which was successfully treated by open excision. Even though the diagnosis of intra-articular osteoid osteoma often presents a challenge for the surgeons, with a present awareness of intra-articular osteoid osteomas which lack the characteristic sclerotic lesions and nidus on plain radiography and the aid of multislice CT, a correct diagnosis which warrants proper treatment can be achieved. The possibility of osteoid osteomas, especially in young adults with persistent knee pain with unknown reasons that show normal plain radiograph results, must not be overlooked. The treatment method of these lesions should be customized depending on the location of the lesion, experience of the surgeon, and cost of method.
Computed tomography
Intra-articular osteoid osteoma
Radiofrequency
Magnetic Resonance
Nonsteroidal anti-inflammatory drugs
Prostaglandin(s).
Antalya Memorial Hospital Ethical committee approved this study.
The written informed consent was obtained from the patient. The patient has consented to using the photography (that was taken intraoperatively) and radiologic images in a scientific paper.
The authors declare that there are no conflicts of interest regarding the publication of this paper.
Ahmet Turan Aydin and Kemal Gokkus contributed to the performing of surgeries of the case and collected the data. Ergin Sagtas and Kemal Gokkus contributed to the literature scan and establishing the discussion part together. Ergin Sagtas and Kemal Gokkus have been involved in drafting the manuscript or revising it critically for important intellectual content. Ahmet Turan Aydin came up with the main idea for the study. All authors read and approved the final manuscript.
The authors would like to thank Antalya Memorial Hospital Chief of Medicine Dr. Omer Ozozan for providing the necessary settings for the study. They would like to thank Taylan Alpaslan for English language editing. They would like to thank their mentor Professor Ahmet Turan Aydin for his exceptional mind and ideas regarding this study.