Date Published: May 22, 2018
Author(s): Daniel A. Müller, Giovanni Beltrami, Guido Scoccianti, Pierluigi Cuomo, Francesca Totti, Rodolfo Capanna.
Soft tissue tumors around the knee joint still pose problems for the excision and subsequent reconstruction.
In the 6 included patients the soft tissue sarcoma has its base on the anterior surface of the extensor mechanism and expands towards the skin. The entire extensor apparatus (quadriceps tendon, patella, and patellar tendon) was resected and replaced by a fresh-frozen allograft.
The mean follow-up was 6.7 years (range: 2–12.4 years). In two patients a local recurrence occurred, resulting in a 5-year local recurrence-free rate of 66.7% (95% CI: 19.5%–90.4%). Distant metastases were found in 4 patients resulting in a 5-year metastasis-free rate of 33.3% (95% CI: 4.6%–67.5%). Two patients underwent at least one revision surgery, including one patient in whom the allograft had to be removed. According to the ISOLS function score 24.7 points (range: 19–28 points) were achieved at the last follow-up. The mean active flexion of the knee joint was 82.5° (range: 25–120°) and a mean extension lag of 10° (range: 0–30°) was observed.
The replacement of the extensor mechanism by an allograft is a reasonable option, allowing wide margins and restoration of active extension in most patients.
The presented study is listed on the ISRCTN registry with trial number ISRCTN63060594.
Soft tissue sarcomas represent a heterogeneous group of lesions that are often subtle in presentation and have a wide variation in extent of malignant behavior. Because of the rarity and vast histological varieties, they frequently pose diagnostic problems. The knee joint and the adjacent structures are quite uncommon locations for soft tissue sarcoma . The most common entities are liposarcoma (25%) and synovial sarcoma (25%), followed by fibrosarcoma (9%) and undifferentiated pleomorphic sarcoma (8%) .
In summary, the treatment of soft tissue sarcoma involving the extensor apparatus of the knee is associated with a high rate of previous inadequate surgeries and high local recurrence and metastatic rates. The replacement of the extensor mechanism by an allograft is a reasonable option, allowing wide margins and restoration of active extension in most patients.