摘要
BACKGROUND For the treatment of bone sarcoma in the distal femur,wide-margin resection and knee reconstruction with tumor endoprosthesis are standard therapies.Extraarticular knee resection is required in cases of tumor invasion of the knee joint;however,the incidence of complications,such as aseptic loosening,prosthesis infection,and implant failure,is higher than that following intra-articular knee resection.To the best of our knowledge,there are three reports of patellar dislocations after replacement of a tumor endoprosthesis.CASE SUMMARY A 36-year-old man with no significant past medical history was admitted to our institution with continuous pain in his left knee for 4 mo.An open biopsy was performed,and the patient was diagnosed with a left distal femoral malignant bone tumor.Extra-articular knee resection and knee reconstruction with a tumor endoprosthesis were performed.Although the alignment of the tumor prosthesis was acceptable,knee instability was noticed postoperatively.The axial radiographic view of the patellar and computed tomography showed lateral patellar dislocation at 4 wk postoperatively.The patient had to undergo a lateral release and proximal realignment.He could perform his daily activities at 9 mo postoperatively.Radiography revealed no patellar re-dislocation.CONCLUSION Proximal realignment may be considered during primary surgery if there is an imbalance in the forces controlling the patellar tracking.
