We report a case of a 24 year old man who presented with pain in the medial aspect of the right knee.The radiograph and MRI of the right knee demonstrated the diagnosis of Pellegrini Stieda syndrome.We discuss the radiographic and MRI features of this condition and its clinical significance.
A 24 year old man presented to the Accident and Emergency department with a two day history of progressive persistent pain in the medial aspect of the right knee.There was a history of injury to the right knee four weeks prior , whilst playing football. A plain anteroposterior and lateral radiographs of the right knee were performed.An MRI of the right knee was also performed.
The Pellegrini-Stieda syndrome, also known as the, Kohler-Stieda-Pellegrini syndrome, Kohler-Pellegrini shadow or just Pellegrini’s disease, was first described in the early 1900s by Augusto Pellegrini, a surgeon in Florence , and Alfred Stieda ,a surgeon in Konigsberg, Germany . It describes the development of ossification in or adjacent to the medial collateral ligament (MCL), near the margin of the medial femoral condyle. It is believed to be the result of past healed trauma such as Stieda’s fracture . Stieda’s fracture is an avulsion injury from the medial femoral condyle at the origin of the MCL. Micro-traumas such as the manipulation of a stiff joint and post-surgical rehabilitation have also been reported as causative factors. Radiographically, it appears as a curvilinear, crescent-shaped, fusiform or elongated well defined ossification adjacent to the medial femoral condyle. The exact pathogenesis of this ossification is not known. Several theories have been suggested such as: metaplasia of the ligamentous tissue, periosteal reaction, calcification of the haematoma following trauma, and a form of myositis ossificans. Clinically, 3-4 weeks after injury, there is swelling, pain, and limitation of movement of the joint, with tenderness on pressure over the medial condyle of the femur. Several weeks after the initial swelling, a calcified mass may be palpated in the region of the MCL. It occurs at any age. Although most are asymptomatic, a few patients will develop the characteristic Pellegrini-Stieda syndrome, which can be severely limiting. On MR the ossification medial to the femoral condyle appears as signal void on T2*weighted sequences. With its high sensitivity to the magnetic susceptibility difference T2* facilitates the detection of tiny osseous fragments and create fine contrast against the surrounding soft tissue. MR studies of patients with Pellegrini Stieda syndrome usually locate these ossifications deep within the superficial layer of the MCL. Correlation with histopathological examination of a surgically excised specimen revealed that the MCL was largely replaced by bony tissue. MRI can therefore be useful in defining the exact extent of the ossification and the degree of involvement of the medial collateral ligament. In cases where surgical excision is contemplated, MRI can delineate the extent of adhesion of the calcified mass to the MCL and the remaining ligamentous volume. Premature excision may result in recurrence and thus care should be taken to allow the lesion to reach maturity. This is demonstrated on MR by the presence of fatty marrow within the ossification on T1 weighted images. Pellegrini-Stieda should not be confused with a fracture of the femoral condyle, periostitis, osteoma or calcification in the bursa or in the potential space between the MCL and the joint capsule. Treatment options includes joint rest, ice for symptom relief, non-steroidal anti-inflammatory drugs and local corticosteroid injection . Surgical excision of calcifications and repair of the tear in the MCL can be considered for refractory cases. The ossification can increase in size but also recede as well. Cases of complete spontaneous absorption have also been reported.
Pellegrini -Steida Syndrome of the right knee.
Based on the X-ray and MRI images of the patient's right knee, a band-shaped or crescent-shaped dense shadow can be seen near the medial femoral condyle. The signal characteristics suggest the presence of a calcification (or ossification) focus in or around the medial collateral ligament (MCL). On T2*-weighted MRI sequences, a clear signal void area is observed, indicating a small bony or calcified density. These imaging manifestations align with the literature describing Pellegrini-Stieda sign, which is characterized by an ossification focus appearing within or adjacent to the ligament near the medial femoral condyle.
There is no obvious large area of soft tissue edema around the joint. The joint space remains acceptable, with no evident fracture lines of the femur or tibia. The articular cartilage surface appears smooth, without noticeable subchondral cystic changes or extensive bony destruction.
In summary, given the patient's possible history of trauma, localized pain, and the position and morphology of the calcification on imaging, Pellegrini-Stieda syndrome is the most representative consideration.
Combining the clinical presentation (medial pain in the right knee, possible history of trauma or chronic ligament strain), the ossification or calcification focus near the origin or insertion of the medial collateral ligament on imaging, and the typical MRI signal void features, the most likely diagnosis is Pellegrini-Stieda syndrome.
For further confirmation, additional clinical examinations (e.g., ligament testing, physical assessment) or dynamic imaging studies may be considered. If the condition recurs or pain does not resolve, surgical exploration and histopathological evaluation may be warranted.
If symptoms persist long-term or if conservative treatment proves ineffective, surgical excision of the calcified lesion and repair of any MCL rupture may be considered. Surgery is typically advised once the calcified region is relatively mature (evidenced by fatty marrow signals on MRI) to reduce the likelihood of recurrence.
After pain and inflammation are controlled, gradual rehabilitation training can be introduced following the FITT-VP principle (Frequency, Intensity, Time, Type, and Progression):
Individual Precautions: Since the ossification may alter the MCL structure, appropriate protection during training is recommended. Avoid forceful impact or torsional stress on the joint. If marked pain or swelling occurs, reduce or pause training and assess for potential ligament reinjury or recurrent inflammation.
Disclaimer: This report only provides a reference analysis based on current imaging and clinical information. It does not replace in-person medical consultation or professional diagnosis and treatment. If you have any questions or discomfort, please contact a specialist or visit a hospital promptly.
Pellegrini -Steida Syndrome of the right knee.
