Reconstruction with a bionic knee megaprosthesis after resection of a distal femoral osteosarcoma in children / 中华骨科杂志

ABSTRACT

Objective:We designed and applied a novel, bionic megaprosthesis for distal femur, which substituted the hinged articulation with an artificial ligament and a constrained tibial insert in order to maintain articular stability and reduce stress and the risks of wearing, loosening and breakage.Methods:We reviewed the cases of distal femoral osteosarcoma in children population who were initially treated in our center during 2019. Twelve cases of bionic distal femoral prosthesis (bionic group) and 21 cases of fixed-hinge distal femoral prosthesis (control group) were included. In the bionic group, there were six female and six male with the mean age as 8.8±2.6 y. One patient had pathological fracture. Staging according to Enneking system included 1 case of stage IIA, 10 cases of stage IIB and 1 case of stage III. In the control group, there were seven female and fourteen male with the mean age as 8.6±2.2 y. Pathological fracture was seen in three cases. Staging included 15 cases of stage IIB and 6 cases of stage III.We investigated the peri-operative safety, oncological outcome, complication profiles and post-operative functional status of the bionic prosthesis by comparing the baseline data, operative data, and oncological and prosthetic outcomes between the two groups.Results:The two groups were comparable in terms of baseline data including gender, age, height, weight and onset duration, and operative data including duration of operation (126.7±27.9 min vs 143.3±38.9 min, P=0.203), intra-operative hemorrhage (162.5±212.3 ml vs 247.6±175.6 ml, P=0.224) and duration of wound drainage (6.3±2.4 d vs 6.4±3.4 d, P=0.908). The mean follow-up duration of bionic group was 16.0±4.7 months, during which time three patients had systemic progression and one of them died of disease. Another patient had local recurrence and subluxation of the prosthesis that was treated by amputation. Subluxation might be related to the huge tumor mass and excessive resection of the quadriceps femoris. As for the control group, the mean follow-up duration was 12.7±4.5 months. Three patients had systemic progression and all patients were still alive by last follow-up. Local recurrence was seen in two patients and was treated by excision. No prosthetic complications were seen in the control group. The averaged range of motion (ROM) was greater in the bionic group than that in the control group (120.6°±13.6° vs 92.0°±7.7°, P<0.05), but the MSTS 93 scores were similar between groups (29.1±0.9 vs 29.5±0.6, P=0.337). Conclusion:Compared with the fixed-hinge distal femoral prosthesis, the bionic prosthesis had good peri-operative safety, did not increase the risks of prosthetic complications, and could achieve a better range of motion and a similar functional status based on the results of short-term follow-up.