INTRODUCTION: Posttraumatic elbow arthritis in young adults is a rare yet challenging condition, presenting primarily with progressive pain and stiffness that limits functional activities. Achieving a functional, low-pain elbow joint with future treatment options is essential for younger, active patients. Unlike total elbow arthroplasty (TEA), which is prone to loosening in young patients, interposition arthroplasty (IA) offers bone preservation, pain reduction, and improved joint function. CASE PRESENTATION: A 22-year-old male presented with four years of right elbow pain and stiffness following a sports-related injury. Initial closed reduction and subsequent surgeries led to progressive stiffness. The patient underwent IA with a fascia lata graft and controlled postoperative physiotherapy. Postoperative management included a 6-week removable POP slab and a 24-week hinged brace, allowing for active range of motion exercises starting at 3-4 weeks. CLINICAL DISCUSSION: Interposition arthroplasty (IA) has become a viable alternative to total elbow arthroplasty (TEA), especially in younger, active patients. IA aims to restore joint function by interposing a biological material such as a fascia lata graft between the damaged bone surfaces of the joint. The fascia lata graft acts as a spacer, reducing pain and facilitating improved motion while preserving the underlying bone structure. The use of this technique is particularly advantageous in patients with posttraumatic arthritis, where joint preservation is crucial, and the long-term risk of implant loosening is a concern with traditional arthroplasty. CONCLUSION: This case illustrates IA as a viable surgical alternative for young patients with posttraumatic elbow arthritis, achieving significant improvements in range of motion and daily function.