Reduced cement volume does not affect screw stability in augmented pedicle screws.

Spinal fixation using pedicle screws is a common treatment in osteoporotic patients, but screw loosening remains a challenge. Cement augmentation has been proposed to improve screw anchorage. However, the optimal cement volume for augmentation is unclear. While some studies suggest higher cement volumes enhance stability, others highlight risks like cement leakage. Prior research has shown that cement augmentation increases screw stability, but the role of cement volume in this effect has not been fully resolved. This uncertainty drove the need for a controlled comparison of different cement volumes. No prior work had resolved whether reducing cement volume compromises stability. The relationship between cement volume and screw fatigue resistance is not well established. This gap motivated a study to evaluate how varying cement amounts affect screw performance. The study aimed to determine if lower cement volumes could maintain stability while reducing complications.

The study aimed to assess how different cement volumes influence the fatigue strength of pedicle screws in osteoporotic vertebrae. Researchers focused on comparing 1 ml and 3 ml cement augmentation volumes. They wanted to determine if reduced cement volume still provides sufficient screw stability. The motivation stemmed from high complication rates associated with cement leakage. The goal was to find a balance between stability and safety. They hypothesized that lower cement volumes might not reduce screw performance. The study also aimed to guide clinical practice on optimal cement usage. By identifying the minimum effective cement volume, they sought to improve patient outcomes.

The study used twenty-five human vertebral bodies from donors aged 73 to 97. Bone density was measured using quantitative computed tomography. Conventional pedicle screws were implanted, followed by unilateral cement augmentation. Thirteen vertebrae received 1 ml of bone cement, and twelve received 3 ml. A fatigue test applied cyclic cranial-caudal loads at 0.5 Hz. The load increased incrementally from 100 N with 0.1 N per cycle. The test continued until screw failure was observed. The load to failure was recorded for each specimen. The study compared fatigue loads between groups to assess the effect of cement volume.

Cement augmentation significantly increased screw fatigue load compared to non-augmented screws. Non-augmented screws failed at 183.8 N, while cement-augmented ones reached 268.1 N (p < 0.001). Augmentation with 1 ml increased the load by 41% compared to non-augmented. Augmentation with 3 ml increased the load by 51% compared to non-augmented. However, there was no significant difference between the 1 ml and 3 ml groups (p = 0.504). Both volumes provided similar fatigue resistance. The study found that lower cement volumes did not compromise stability. These findings suggest that reducing cement volume may not affect screw performance.

The authors concluded that cement augmentation improves pedicle screw stability in osteoporotic bone. They found that both 1 ml and 3 ml cement volumes achieved similar fatigue resistance. The benefit of augmentation was not significantly affected by reducing cement volume. This suggests that lower cement volumes may be sufficient for stability. The study supports using reduced cement volumes to minimize complications. They recommend 1 ml per screw to balance safety and effectiveness. These findings align with the goal of reducing cement-related risks. The authors propose that lower volumes could be safely adopted in clinical practice.