Fully Constrained Total Knee Arthroplasty for Secondary Osteoarthritis Knee Due to 4-Years Neglected Knee Dislocation: A Case Report

Abstract

Background: Traumatic knee dislocation is a rare and severe injury. Untreated chronic knee dislocation progressing to marked instability and severe secondary osteoarthritis is exceptionally uncommon. Such cases usually present with degenerative changes, bone deformity, ligament laxity, and instability, making their management more challenging. Owing to the rarity of this condition, no defined treatment protocol has yet been established. Aims: This case report describes the management of a 57-year-old woman with a BMI of 27.8 who presented with chronic right knee pain, instability, varus deformity, and extensor mechanism impairment four years after an untreated traumatic knee dislocation. Presentation of Case: A 57-year-old female with a BMI of 27,8 complained of pain and instability in the right knee, with varus deformity and extensor mechanism impairment. Radiographs demonstrated advanced osteoarthritic changes attributable to a right knee dislocation that had remained untreated for 4 years. Given the extensive ligamentous injury, fully constrained total knee arthroplasty (TKA) was undertaken to maximise joint stability. Range-of-motion (ROM) exercises and weight-bearing commenced on the second postoperative day, and discharge education was provided. Discussion: Unstable secondary osteoarthritis after neglected knee dislocation is uncommon. Knee instability associated with bone deformity and ligamentous damage presents significant management challenges. As the patient was still active at work, arthrodesis was avoided to maximise ambulatory function. TKA itself presents several challenges, including bony deformities and ligament insufficiency. Fully constrained TKA, or a hinged total knee prosthesis, is selected when the ligaments are severely damaged to achieve knee stability and a complete range of motion. This treatment has been considered effective, with favourable mid-term clinical and radiological results. Conclusion: Fully constrained TKA for secondary osteoarthritis caused by neglected knee dislocation may be a reliable option for providing maximum knee stability without additional bony or soft-tissue procedures.