Meniscal hematoma is very rare; we identified only two case reports in the English-language literature1,2. Recurrent hemarthrosis of the knee, or spontaneous hemarthrosis, is also a relatively rare condition3,4. We do not believe that a case of meniscal hematoma concurrent with hemarthrosis of the knee has been previously reported.
We present a case of meniscal hematoma involving the lateral meniscus concurrent with spontaneous knee hemarthrosis. The patient was informed that data concerning the case would be submitted for publication, and she gave her consent.
A fifty-six-year-old woman was referred to our department because of recurrent hemarthrosis of the knee and exacerbation of knee pain.
The patient had experienced a catching sensation in the left knee joint since the age of approximately thirty years, but she did not seek medical advice because she had no pain. Approximately one month before presenting to our department, she visited a physician because of swelling and pain in the left knee without apparent cause, which led to difficulty in walking. Bloody joint fluid was aspirated, but subsequently the hemarthrosis and knee pain recurred.
The patient had a history of cervical spinal cord injury due to a traffic accident when she was thirty-nine years old, which had resulted in quadriparesis. She used a T-shaped stick while walking. At presentation, in addition to difficulty with walking, she had marked swelling and pain in the left knee. Instability of the knee was not demonstrated, but a large effusion was present. Left knee motion was –20° of extension and 60° of flexion (unaffected knee: –5° of extension and 125° of flexion). She had tenderness along the lateral joint line. Evaluation of the meniscus with the McMurray test and Apley test was difficult because of pain and a limited range of motion. Hip and ankle motion was normal, and no disturbance in sensation to painful stimuli was detected in the lower extremity.
A radiograph demonstrated osteoarthritic changes of the lateral compartment in both knees. Magnetic resonance imaging (MRI) revealed a 2-cm-long mass lesion anterior to the intercondylar notch in the left knee, showing low signal intensity on the T1-weighted image and a mixture of low and high signal intensity on the T2-weighted image (Figs. 1-A and 1-B). A degenerative tear of the lateral meniscus was observed in both knees (Fig. 1-C). Serum tests showed mild anemia and an increased erythrocyte sedimentation rate. Biochemical and coagulation test results were normal. There was no history of a bleeding disorder or anticoagulant treatment.
Because of the findings of an intra-articular mass and recurrent hemarthrosis, pigmented villonodular synovitis was suspected and arthroscopic surgery was conducted. Arthroscopic examination showed a bucket-handle tear adjacent to the lateral meniscus insertion site extending from the middle segment to the posterior horn, as well as a mass in the midportion of the bucket handle. The mass had a smooth surface and a membrane of elasticity like rubber. It appeared as a polyp-like elevation from the region of the bucket-handle tear and showed no continuity with other intra-articular structures (Fig. 2). The meniscal bucket-handle portion together with the mass was resected arthroscopically. Under arthroscopic viewing, although active bleeding was not observed, a blood clot was found around the tear of the lateral meniscus. The ruptured site of the lateral meniscus was suspected to be the source of bleeding, and hemostasis was achieved with electrocoagulation.
Gross examination of the resected mass lesion showed a pedicled tumor with a smooth surface measuring 15 × 12 mm in diameter. The surface was covered with fibrous tissue, and the interior contained a black substance resembling a hematoma (Fig. 3). Histopathologically, the surface layer of the mass was fibrous connective tissue and the interior content was a blood clot composed of red blood cells and fibrin (Figs. 4-A and 4-B). No vascular structure was observed in the resected specimen. On the basis of the above findings, the diagnosis was meniscal hematoma associated with a lateral meniscal tear.
As a preventive measure against rebleeding after surgery, the knee was immobilized in a plaster splint and weight-bearing was restricted. Knee motion exercises were started two weeks later. Full weight-bearing was permitted at four weeks after surgery. There was a transient recurrence of the hemarthrosis two months after surgery. Swelling of the knee was observed, and 7 mL of bloody joint fluid was aspirated. Thereafter, there was no recurrence of the hemarthrosis, and the subsequent course was uneventful through fourteen months of further follow-up. Motion of the affected knee improved to 5° of extension and 125° of flexion. The patient walked with a T-shaped cane.