Multiligamentous Knee Reconstruction Complicated by Septic Arthritis Following Cosmetic Surgery, A Case Report.

Background and Purpose: Multiligamentous knee injuries present challenges to surgeons and rehabilitation specialists. Challenges can be complicated by postoperative infections, which impact patient outcomes. The knee stability and movement coordination impairments in this case are consistent with the Knee Ligament Sprain Clinical Practice Guideline, which provides a clinical framework for rehabilitation decision making following complex ligament reconstructions. This case report describes the rehabilitation management and outcomes following multiligament knee reconstruction complicated by septic arthritis after elective cosmetic surgery performed shortly after an orthopedic surgery. Case Description: A 22-year-old female recreational athlete (runner and gymnast) sustained a right tibiofemoral dislocation after a motor vehicle accident. A staged surgical approach was performed with posterolateral corner reconstruction followed by anterior and posterior cruciate ligament reconstruction four months later. Eight weeks after cruciate ligament reconstruction, the patient underwent elective cosmetic surgery with autologous fat grafting from the thigh. She developed a sudden onset of right knee pain and swelling and was diagnosed with septic arthritis. Arthroscopic irrigation, debridement, synovectomy, and intravenous antibiotics were administered. Rehabilitation progressed through a multi-phased protocol based on tissue healing and clinical readiness. Patient-reported outcomes included the International Knee Documentation Committee (IKDC), the ACL Return to Sport After Injury (ACL-RSI), and the Optimal Screening for Prediction of Referral and Outcome Yellow Flag (OSPRO-YF) and isokinetic testing. Outcomes: The patient completed 36 sessions over 63 weeks from arthroscopic irrigation to the final physical therapy visit. IKDC increased by 17.24 points (MCID = 9.5), and ACL-RSI improved by 30 points (MIC = 15.1). OSPRO-YF decreased from five yellow flags to three. Isokinetic testing revealed a quadriceps peak torque-to-body weight ratio of 84.2%, with a limb symmetry index of 96.6%, surpassing normative values. She returned to an interval running program at 16 weeks and resumed coaching gymnastics at 28 weeks post-irrigation. Discussion: This case highlights infection as a critical differential diagnosis in patients presenting with a painful knee effusion and describes septic arthritis occurring after an elective procedure performed shortly following orthopedic surgery. Level of Evidence: 4.