Incidence and Clinical Outcomes of Hardware Failure After MIS-ATP Guided Multilevel Posterior Percutaneous Fixation in Adult Spinal Deformity: A Prospective Analysis

Background: Minimally invasive surgical techniques are gaining acceptance for adult spine deformity treatment with the hopes of decreasing perioperative morbidity and improving recovery. The minimally invasive antepsoas (MIS-ATP) approach has been regarded as a reasonable alternative for multilevel posterior percutaneous fixation due to the soft tissue disruption it offers along with postoperative spinal stability. Hardware failure, including screw loosening, rod fracture, or construct instability is not well studied in the adult spine deformity population. Objective: Determine incidence of hardware failure in adult deformity receiving multilevel posterior percutaneous fixation via MIS-ATP with exploration of risk factors and clinical outcomes. Methods: This was a single center, exceptional prospective observational study at Department of Orthopedics, Adesh Medical College and Hospital, Haryana, India that included a total of 128 adult patients with spine deformity undergoing multilevel posterior percutaneous fixation from January 2023 to December 2023, with a minimum follow up of 12 months. Hardware failure was defined as any radiographically confirmed loosening, breakage, or migration of a fixation. Clinical measures were gathered by Visual Analog Scale (VAS) for pain, Oswestry Disability Index (ODI), and radiographic corrections of deformity. Results: Nineteen patients (14.8%) experienced hardware failure during follow-up. Loosening of the screw was the most common failure type (52.6%), followed by fracture of the rod (31.5%) and failure of the construct migration (15.9%). Increased body mass index (BMI), osteoporosis and number of instrumented levels were significant factors associated with hardware failure (p < 0.05). Patients with hardware failure had higher mean VAS and ODI scores than patients without failure, indicating worse functional outcomes. However, revision surgery restored stability and improved pain symptoms in the majority of patients. Conclusion: Hardware failure is a clinically relevant complication following MIS-ATP guided multilevel posterior percutaneous fixation in adult spine deformity, with an incidence of approximately 15%. Patient-specific risk factors, particularly osteoporosis and obesity, significantly influence outcomes. Careful preoperative patient selection, optimization of bone quality, and construct planning are essential to reduce the risk of hardware-related complications.