Preliminary research of combining LARS and semi-joint replacement for malignant tumor around the knee in children / 中华骨科杂志

ABSTRACT

Objective To study the preliminary effect of combining ligament advanced reinforcement system (LARS) and semi-joint replacement for malignant tumor around the knee in children.Methods 9 cases of malignant tumor around the knee (5 boys and 4 girls) from February 2015 to May 2017 were analyzed respectively.The average age was 9.2 years old (ranged from 5 to 12 years).The follow-up time was 6 to 28 months,with an average of 13.5 months.The preoperational biopsy diagnosis respectively were Ewing sarcoma (3 cases) and osteosarcoma (6 cases).According to Enneking staging system,all 9 cases were staged as ⅡB.The planned courses of standardized preoperative neoadjuvant chemotherapy were successfully given to all patients on time.All patients were given tumor extensive resection and modular prosthesis replacement.Suitable length prosthesis were prepared according to CT and MRI.LARS were annularly bundled to the prosthesis.Then residual patella ligaments,cruciate ligaments,collateral ligaments,capsules and muscles were tightly sutured to LARS.Adjuvant chemotherapy and functional exercise were given after operation.Bone healing,limb discrepancy,and complications were regularly recorded.Functional outcomes were assessed by the system of the Musculoskeletal Tumor Society (MSTS) and the range of motion (ROM) of both knee joints.Results All patients successfully received standardized chemotherapy.In all courses of chemotherapy,bone marrow all restored.No other major complications occurred during chemotherapy.Primary healing of incisions were obtained.No obvious limb discrepancy.The average limb length discrepancy was 2.9±1.8 cm (0.5～6.4 cm),the femur was 1.9±1.0 cm (0.6～3.9 cm),the tibia was 0.8±0.5 cm (0.2～2.0cm).The distance between the lower limb alignment and the center of the knee was 0.3±0.1 cm (0.2～0.6 cm).MSTS score was 24.6±3.2 of the last follow-up,and 21.4± 1.9 of preoperation,the difference was statistically significant (t=2.71,P=0.03).ROM of the knee were 71.7°± 18.2° at the last follow-up,and 69.1 °± 17.9° before operation,and the difference was statistically significant (t=3.261,P=0.01).No infection,snapping knee,limp,dislocation,periprosthesis fractures,prosthetic broken or loosening.2 case had lung metastasis and still survived.NO local recurrence or other metastasis cases.Conclusion LARS combined with semijoint replacement for the treatment of malignant tumor around the knee in children have a satisfactory postoperative joint function recovery and simple surgical technique and fewer complications,and preserve the contralateral osteophytes to minimize the occurrence of limb inequality,but the long-term efficacy needs further follow-up.