Biological reconstruction after excision of juxta-articular osteosarcoma around the knee: a new classification system

A new classification system for juxta-articular osteosarcoma around the knee joint was developed to allow biological reconstructions using distraction osteogenesis or frozen autograft containing tumors treated with liquid nitrogen. Type I: Tumor has metaphyseal extension to a maximum of 2 cm from the epiphyseal cartilage plate. Type II: Tumor extends to at least half the circumference of the epiphyseal cartilage plate. Type III: Extension to the whole circumference of the epiphyseal cartilage plate. Type IV: Tumor extends to part of the epiphysis through any point of the epiphyseal cartilage plate 10 mm from the joint line. Type V: Tumor extends to half or less of the epiphysis. Type VI: Extension of the tumor to more than half of the epiphysis.

Twenty patients with juxta-articular osteosarcoma around the knee joint were treated according to this classification system. The cohort comprised 12 males and 8 females with a mean age of 20 years. The tumors were located in the femur in 12 patients and in the tibia in 8 patients.

The tumors were Type II in 1 patient, Type III in 8 patients, Type IV in 2 patients, Type V in 3 patients and Type VI in 6 patients. Reconstruction after tumor excision was performed using distraction osteogenesis in 13 patients and using frozen autografts in 7 patients. The mean follow-up in the series was 54 months, ranging from 5 to 103 months.

The classification system may act as a guide to appropriate decision-making in cases of juxta-articular osteosarcoma around the knee joint. Biological reconstruction, using distraction osteogenesis or frozen autografts, may yield good functional results without leading to an increase in the incidence of local recurrence.