Loose bodies (LBs) are pathological findings in the knee joint, known for its anatomical complexity and prevalent synovial recesses and bursae
[1]
. The primary, underlying etiology of loose bodies is still unclear; however, it could be attributed to certain factors like direct trauma to the knee joint causing osteochondral fractures, indirect trauma to the knee joint due to repetitive stress causing the connection between the articular cartilage and bone to deteriorate, leading to loosening of the affected osteochondral area
[2]
. Moreover, conditions like osteoarthritis, rheumatoid arthritis, and tumor-like lesions could also be a reason behind the formation of loose bodies in the knee joint
[1]
. These LBs may be found either intra-articularly or localized within various recesses and bursae
[1]
. In case these LBs exhibit free movement within the joint cavity, the chances of these LBs becoming entrapped between the articular cartilage happen to increase. Consequently, joint locking happens intermittently, ultimately leading to limited motion, pain, and effusion intraarticularly
[3]
in contrast to the stable fragments that are located within the bursae or synovial recesses, which are typically asymptomatic
[4]
. When diagnosing loose bodies, radiological findings play a crucial role, as the clinical picture usually lacks specificity. Different imaging modalities assist in confirming the diagnosis, in addition to specifying the number, size, as well as the location of these fragments, allowing for the prevention of secondary degenerative changes by allowing for early surgical intervention
[5]
. Although the modalities of choice have always been CT arthrography and MR, recent advancements in ultrasonography aided the evaluation of such abnormalities. In such cases of symptomatic loose body, removal is warranted, regardless of the size. Arthroscopy is widely used for operative management, while arthrotomy is reserved for inaccessible or other large bodies
[6]
. This case report presents a 52-year-old male patient with an exceptionally large osseous loose body in the knee joint, along with associated pathologies. Symptomatic loose bodies, regardless of size, warrant removal. Arthroscopy is commonly used for operative intervention. Arthrotomy may be necessary for inaccessible or exceptionally large bodies
[6]
. This case report presents the clinical findings, radiological findings, and surgical management of a patient with an unusually large osseous loose body within the knee joint.
2. Case Report
The patient, a 52-year-old male, had recurrent episodes of severe, sudden locking in the knee joint, in addition to the sensation of a mobile round hard body inside the knee joint. Aiming to release this intermittent locking, the patient needed to do special maneuvers.
After the physical examination, an MRI was requested for the patient. A plain MRI study of the left knee was performed using multi-axial, multi-echo sequences. Various pathologies were observed in the MRI study. The femorotibial compartments revealed degeneration of the medial and lateral menisci in the posterior horn, with no extension to the articular surface. The hyaline cartilage had a partial loss of thickness of less than 50% in the tibiofemoral region, corresponding to Grade 2 ICRS (
Figure 1
). A mild deviation of the patella was noted on the lateral side. The anterior and posterior cruciate ligaments were intact and revealed normal shape and density (
Figure 2
). No fractures, subluxations, or other bone marrow edemas were found. A popliteal Baker’s cyst was observed. The cyst was located between the semimembranosus tendons and the medial head of the gastrocnemius, with measurements of 4.5 × 1.5 × 1.2 cm.
The surgery was performed under general anesthesia, and the patient was placed in a supine position, throughout the procedure, a tourniquet with a pressure of 200 mmHg was used. Two arthroscopy standard portals were established using size 11 blades. Each portal was 5 mm, allowing for the insertion of a camera to directly visualize the internal aspects of the knee joint. The examination revealed the presence of an abnormally large osseous loose body within the infrapatellar Hoffa’s fat pad of the left knee joint. The normal arthroscopic grasper was insufficiently small to grasp the loose body, so the Allis Grasper was used instead. The second portal was then enlarged to 2 cm promote extraction of the loose body. The Loose body, located in the infra-patellar Hoffa’s pad, was successfully extracted, with measurements of 2.5 × 1.7 cm (
Figure 3
). Further examinations were conducted to ensure the knee joint was clear of any remaining loose bodies. Additionally, grade one osteoarthritic changes were observed in the medial femoral condyle. Histopathology was not performed in this case, as no clinical or radiological suspicion warranted further investigation. The investigation and intraoperative findings were consistent with a benign loose body, and no features indicative of malignancy or other pathologies were observed.
Post-operatively, the patient was immediately able to walk. During a follow-up visit, the patient’s knee was re-examined physically. Upon sensation, the knee joint had a normal contour, and sensation of a round body disappeared. The knee joint was freely moving upon passive motion, with the absence of any sudden locking. The patient reported full ability to walk and move his knee joint without any locking. The limited range of motion was denied by the patient.
Figure 1. T1 lateral view of the MRI reveals the osseous loose body (yellow arrow).
Figure 2. T2 MRI saggital view reveals the presence of a popliteal Baker’s cyst.
Figure 3. The specimen’s size (2.5 × 1.7 cm).
3. Discussion
Loose bodies are remnants of bone or cartilage, floating freely in the synovial fluid of the knee joint. Typical loose bodies are unilateral, affecting only one knee at a time
[7]
. The patient in the presented case report displayed an abnormal, large osseous loose body in the knee joint, requiring arthroscopic intervention. This is similar to the case reported by Yang et al., where a patient was found to have low-density, loose radio-dense bodies in the suprapatellar bursa, analogous to the loose body detected in the case report
[7]
.
The efficacy of the arthroscopic intervention in extracting loose bodies and managing the associated symptoms is supported in the presented case, as the arthroscopic intervention successfully extracted the loose body from the knee joint, and a case of giant intra-articular loose bodies in the knee joint also highlights the successful treatment with knee arthroscopy reported by Sourlas et al.
[8]
.
Moreover, the treatment of loose bodies with arthroscopic intervention was also supported by the study of Chai and Lui, where posterior loose bodies were removed using posterior knee arthroscopy
[9]
. Though the precise location of the loose body in the case presented wasn’t specified, the surgical procedure consisted of establishing arthroscopy portals and removing the loose body.
The importance of accurately identifying and pinpointing the location of loose bodies on MRI for the determination of the optimal treatment, and prevention of osteoarthritis development was highlighted by the study of Gursoy
[5]
. The MRI findings in the presented case report included the identification of the loose body, degenerative changes in the menisci and hyaline cartilage, and the presence of a Baker’s cyst, which aligns with the study’s concentration on addressing numerous pathologies linked to loose bodies in the knee joint.
The results drawn from the presented case are in line with the results reported in the studies discussed, providing further evidence to support the effectiveness of arthroscopy in managing loose bodies in the knee joint, and highlighting the importance of accurately identifying and localizing the loose bodies to provide optimal treatment and prevent further complications.
Acknowledgements
The authors declare that there are no acknowledgements for this manuscript.
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