Severe injuries to the lower spine and pelvis, known as traumatic unstable sacral fractures, are complex injuries that often require surgery to stabilize the bones and prevent long-term disability. A standard surgical treatment is lumbopelvic fixation, which uses metal screws and rods to connect the lower spine to the pelvic bones. This procedure can be performed using a traditional open surgical approach with a larger incision, or a minimally invasive approach using smaller incisions.

While both methods are used to effectively stabilize the fracture, there is a need for more comprehensive data comparing which approach provides the best overall recovery with the fewest complications.

The purpose of this retrospective study is to compare the long-term outcomes of adult patients who underwent open lumbopelvic fixation versus those who had minimally invasive lumbopelvic fixation. Researchers will review the medical records and imaging of patients treated between January 2016 and December 2024.

The main goal of the study is to evaluate physical function and recovery using a standardized assessment tool called the Majeed Pelvic Score. Additionally, the study will compare the two surgical groups to look at:

• Bone healing: How well the bones aligned and healed over time.
• Surgical complications: Rates of wound infections, skin issues, or hardware failures (like broken screws).
• Clinical recovery: Improvement in nerve function (for those who had pre-existing deficits) and post-surgery back pain levels.
• Quality of life: How quickly patients were able to return to work and perform their jobs efficiently.
• Secondary surgeries: The need for any additional operations following the initial fix.

By comparing these two approaches comprehensively, researchers hope to help surgeons identify the optimal surgical method tailored to a patient's specific fracture characteristics.

Traumatic unstable sacral fractures are challenging high-energy pelvic injuries with significant implications for structural integrity and neurological function. While traditional open lumbopelvic fixation (O-LPF) provides excellent biomechanical stability and allows for direct neural decompression, it requires an extensile posterior approach associated with significant perioperative morbidity, including deep surgical site infection rates historically ranging from 16% to 26%. Minimally invasive or percutaneous lumbopelvic fixation (MIS-LPF) was developed to mitigate these approach-related complications, though it permits only indirect neural decompression.

Despite emerging evidence favoring MIS techniques for reduced blood loss and infection rates, most published series remain small, retrospective, and heterogeneous. This study aims to provide a comprehensive, multi-dimensional comparison of open versus minimally invasive lumbopelvic fixation specifically in adult patients with traumatic unstable sacral fractures.

This is a retrospective, comparative cohort study conducted at the Department of Orthopedic Surgery and Traumatology at Assiut University. Data will be systematically extracted by two independent investigators from electronic medical records, surgical operative logs, and PACS digital imaging systems for qualifying index surgeries performed between January 2016 and December 2024. A standardized data extraction sheet will be utilized to minimize observer bias, and all data will be de-identified prior to analysis.

Researchers will collect comprehensive data points across several domains:

• Baseline and Injury Characteristics: Demographics, comorbidities, mechanism of injury, and precise fracture classifications including Denis Zones, Roy-Camille, and AO/OTA.
• Surgical and Perioperative Details: Surgical technique utilized, operative time, estimated blood loss, specific implant details, use of intraoperative imaging, and length of hospital/ICU stay.
• Clinical and Radiological Outcomes: Neurological status documented via the Gibbons Neurological Grading Scale, quality of fracture reduction assessed via Matta and Tornetta criteria, time to radiographic union, and postoperative pain levels via Visual Analog Scale (VAS).
• Complications: Incidence of surgical site infections (superficial and deep), wound dehiscence, implant failure, thromboembolic events, and the necessity and timing of secondary reoperations.

Inclusion Criteria:

• Adult patients aged 18 years or older at the time of injury and surgery.
• Confirmed diagnosis of a traumatic, unstable sacral fracture, including: Denis Zone I, II, or III fractures with instability; Spinopelvic dissociation (U-type / H-type sacral fractures); AO/OTA Type C pelvic ring injuries involving the sacrum.
• Operated on using lumbopelvic fixation (open or minimally invasive technique) within the study period (2016-2024).
• Availability of adequate and complete medical records, including: Preoperative and postoperative imaging (X-ray and/or CT scan), and operative notes and surgical logs.
• Minimum clinical follow-up of 12 months postoperatively.

Exclusion Criteria:

• Pathological fractures (e.g., fractures secondary to primary or metastatic malignancy, osteoporotic insufficiency fractures).
• Patients managed conservatively or with alternative fixation strategies that do not include lumbopelvic instrumentation (e.g., isolated iliosacral screw fixation, anterior ring fixation alone).
• Severe polytrauma resulting in in-hospital mortality prior to the minimum required follow-up period.
• History of previous pelvic, sacral, or lumbosacral spine surgery prior to the index trauma.
• Incomplete medical records or inadequate radiological follow-up data preventing accurate assessment of outcomes.
• Patients with pre-existing neuromuscular disorders or spinal pathology that would confound neurological or functional outcome assessment.
• Pregnant patients at the time of injury

The study population consists of adult patients ($\ge$ 18 years) treated at the Department of Orthopedic Surgery and Traumatology at Assiut University. Patients must have a confirmed diagnosis of a traumatic, unstable sacral fracture (including Denis Zones I-III with instability, spinopelvic dissociation, or AO/OTA Type C injuries). All included subjects were operated on using either open or minimally invasive lumbopelvic fixation between January 2016 and December 2024. Furthermore, participants must have adequate medical records with a minimum of 12 months of postoperative clinical follow-up.