150PREDICTORS OF EARLY FAILURE FOLLOWING INTERNAL FIXATION OF LONG BONE FRACTURES: A PROSPECTIVE COHORT STUDYInternal fixation remains the cornerstone of treatment for many long bone fractures, providing mechanical stability that facilitates fracture healing, early mobilization, and restoration of function. Despite advances in implant design, surgical techniques, and perioperative care, early fixation failure continues to represent a significant clinical challenge. Complications such as implant loosening, implant breakage, loss of fracture reduction, delayed union, and nonunion can compromise healing, necessitate revision surgery, prolong rehabilitation, increase healthcare costs, and adversely affect patient quality of life. Understanding the factors associated with fixation failure is therefore essential for improving surgical outcomes and developing targeted preventive strategies. This prospective cohort study was conducted to identify predictors of early failure following internal fixation of long bone fractures and to evaluate the relative contributions of patient-related, fracture-related, and surgical factors. A total of 180 patients undergoing internal fixation for long bone fractures were enrolled and prospectively followed for a period of 6 to 12 months. Early failure was defined as implant failure, loss of reduction, delayed union progressing to nonunion, or any fixation-related complication requiring additional surgical or clinical intervention. Detailed demographic, clinical, fracture, and operative variables were recorded, including age, sex, smoking status, diabetes mellitus, fracture type, fracture comminution, open versus closed injury, reduction quality, and fixation characteristics. Statistical analysis involved univariate comparisons using chi-square testing followed by multivariable logistic regression to identify independent predictors of early fixation failure, with results expressed as adjusted odds ratios (aORs). During followup, early fixation failure occurred in 27 of 180 patients, corresponding to an overall incidence of 15%. Multivariable analysis demonstrated that inadequate fracture reduction was the strongest independent predictor of failure (aOR ? 3.3), highlighting the critical importance of achieving optimal alignment and stability during surgery. Open fractures were also associated with a significantly increased risk of failure (aOR ? 2.6), likely reflecting greater soft-tissue damage, contamination, and biological compromise. Fracture comminution independently increased failure risk (aOR ? 2.4), emphasizing the challenges of achieving durable fixation in complex injury patterns. Patient-related factors also contributed, with smoking (aOR ? 2.1) and diabetes mellitus (aOR ? 1.9) demonstrating significant associations with fixation failure, likely through their adverse effects on bone healing and vascularity. These findings indicate that both modifiable surgical factors and patient characteristics influence outcomes following internal fixation. Overall, early failure after internal fixation of long bone fractures was driven predominantly by reduction quality, fracture severity, and patient comorbidities. The results support meticulous surgical technique, careful preoperative planning, optimization of modifiable risk factors such as smoking and diabetes, and enhanced monitoring of high-risk patients to improve fixation success and reduce the burden of revision surgery-Research922019 Long bone fracture; Internal fixation; Implant failure; Nonunion; Open fracture; Reduction qualityDr. Yadlapalli Sai Pramod, Dr. Rajaram GanesanAssistant Professor, Department of Orthopaedics, Sri Lakshmi Narayana Institute of Medical Sciences & Hospital, Osudu, Puducherry – 605502, India.,Associate Professor, Department of Radiology, Sri Lakshmi Narayana Institute of Medical Sciences & Hospital, Osudu, Puducherry – 605502, India