Case Report
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Apr 16, 2022; 10(11): 3561-3572
Published online Apr 16, 2022. doi: 10.12998/wjcc.v10.i11.3561
Patellar dislocation following distal femoral replacement after extra-articular knee resection for bone sarcoma: A case report
Yuta Kubota, Kazuhiro Tanaka, Masashi Hirakawa, Tatsuya Iwasaki, Masanori Kawano, Ichiro Itonaga, Hiroshi Tsumura
Yuta Kubota, Kazuhiro Tanaka, Masashi Hirakawa, Tatsuya Iwasaki, Masanori Kawano, Ichiro Itonaga, Hiroshi Tsumura, Orthopaedic Surgery, Oita University, Yufu City 879-5593, Oita, Japan
Author contributions: Kubota Y, Tanaka K and Tsumura H conceived the study; Kubota Y and Tanaka K reviewed the literature and contributed to manuscript drafting; Kubota Y, Tanaka K, Iwasaki T and Kawano M contributed data analysis and interpretation; Hirakawa M, Itonaga I and Tsumura H were responsible for the critical revision of the manuscript for important intellectual content; all authors have read and approved the final version of the manuscript.
Informed consent statement: Informed written consent was obtained from the patients for the publication of this report and any accompanying images.
Conflict-of-interest statement: The authors declare that they have no conflict of interest.
CARE Checklist (2016) statement: The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Kazuhiro Tanaka, MD, Associate Professor, Orthopaedic Surgery, Oita University, 1-1 Idaigaoka, Hasama, Yufu City 879-5593, Oita, Japan. ktanaka@oita-u.ac.jp
Received: November 8, 2021
Peer-review started: November 8, 2021
First decision: December 27, 2021
Revised: January 9, 2022
Accepted: February 27, 2022
Article in press: February 27, 2022
Published online: April 16, 2022
Processing time: 150 Days and 21.8 Hours
Abstract
BACKGROUND

For the treatment of bone sarcoma in the distal femur, wide-margin resection and knee reconstruction with tumor endoprosthesis are standard therapies. Extra-articular 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.

Keywords: Bone tumor; Distal femoral replacement; Lateral release; Patellar dislocation; Proximal realignment; Case report

Core Tip: Extra-articular knee resection is required in cases of tumor invasion of the knee joint. To the best of our knowledge, there are three reports of patellar dislocations after replacement of tumor endoprosthesis. We report a case of patellar dislocation after extra-articular knee resection and knee reconstruction with a tumor endoprosthesis without its malalignment. When distal femoral replacement with extra-articular knee resection is planned and the quadriceps muscle is assumed to be resected asymmetrically, proximal realignment may be considered during primary surgery if there is concern regarding an imbalance in the forces controlling the patellar tracking.