Aseptic loosening of tumor endprostheses in distal femur after revision surgery: a retrospective study

Abstract

Background: More patients are having revision surgery because of aseptic loosening of tumor prostheses in distal femur, but the revision failure rate is also increasing, which is mainly due to the recurrence of aseptic loosening. The purpose of this study was to analyze the risk factors for recurrence of aseptic loosening after revision surgery of tumor prosthesis in the distal femur. Method: A retrospective analysis was performed on 23 patients who had revision surgery for distal femur prosthesis due to aseptic loosening between June 2002 and June 2021. They were divided into two groups based on the condition of the prostheses after revision surgery: loosening group and control group. After the initial replacement, length and diameter of the prosthetic intramedullary stem were measured. The osteotomy length, femoral length and diameter, femoral intramedullary stem diameter, hip–knee–ankle angle (HKAA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA) and so on were measured as well. Following that, statistical analysis was performed. Results: Patients in the loosening group had statistically significant differences in the ratio of prosthesis length to femur length (71.89±6.62) and the ratio of intramedullary stem diameter to medullary cavity diameter (25.50±6.90) (P < 0.05) when compared to the control group. The HKAA (175.58°±2.78°), mLDFA (94.42°±2.57°), and the deviation angle between the force line of the lower limb and the longitudinal axis of the tibial prosthesis (2.23°±1.09°) in the loosening group were significantly different from those in the control group (P < 0.05) on postoperative radiographs of the entire length of the lower limbs. The lowest score in intramedullary manubrium I indicated less osteolysis, while the highest score in intramedullary manubrium Ⅲ indicated the most serious osteolysis, and the difference was statistically significant (P < 0.05). Conclusions: We conclude that using longer and thicker intramedullary stems can effectively reduce the incidence of aseptic loosening, and that using the original prosthesis carefully can reconstruct the standard line of lower limb force. The distal segment of the intramedullary stem is more prone to osteolysis and should be closely follow-up after surgery.

Limited Revision with a Newly Designed Hinge Device for the Treatment of Mega‐Prosthesis Hinge Failure: Two Case Reports

“…The axial yoke‐type rotary hinge joint, due to its uniform stress distribution, greatly reduces the risk of hinge damage and has gradually become the basic template design of various companies. However, in China, some patients have accepted old mega‐prosthesis reconstruction without any axial yoke‐type hinge 8 . Some of these patients experienced clinical problems such as knee hyperextension, dislocation, and joint instability.…”

“…However, many mega‐prostheses with design defects have been previously used, especially in developing countries, and so, some patients with mega‐prostheses have required revision surgeries 7 . A conventional revision surgery generally involves removing the failed mega‐prostheses thoroughly and then installing new mega‐prostheses 8–10 . This revision method in most cases is often traumatic, difficult to operate, and less cost‐effective 7,11,12 .…”