Clinical and Radiological Results of PMMA-Augmented Pedicle Screws in Patient with Osteopenic Bone

Introduction: In osteopenic patients (e.g., osteoporosis, tumors), stability of transpedicular fixation can be increased by injection of polymethylmethacrylate (PMMA) through fenestrated screws. We have retrospectively analyzed a consecutive series of 15 patients (n = 15) treated with thoracic or lumbar PMMA-augmented pedicle screws, to determine the safety of the procedure and the stability of the implant.

Material and Methods: From February 2008 to March 2010, PMMA-augmented pedicle screw insertion was performed in 15 patients who had severe osteopenia. We analyzed the clinical and radiological data, based on pre- and postoperative magnetic resonance imaging, computed tomographic scans, dynamic X-rays, and clinical evaluation. Early and late postoperative complications were recorded during follow-up.

Results: The mean postoperative clinical and radiological follow-up was 6 months (range 3 to 9 months). The average age of the patient was 73.5 years (range 67 to 83 years). The mean number of fused segments was 4 (range 2–13), with an average of 2.5 cc PMMA injection per screw, 5 cc per vertebral body. Total of eight thoracic (53%) and seven lumbar (57%) transpedicular fixations were performed. Ten patients (67%) had documented osteoporosis with the T-score value of less than −2.5 and all had multiple comorbidities. Indications for PMMA-augmented screws were: spinal instability (n = 4) associated with radiological osteopenia, pathologic fractures (n = 5), metastasis (n = 2), spinal stenosis (n = 2), or pseudarthrosis after previous surgery (n = 2). Of the 15, 13 patients (87%) showed significant improvement of symptoms (pain and neurological deficit) after surgery. PMMA injection was uneventful in all patients except one patient (6.6%), where a minor leak of PMMA into the epidural venous plexus was observed (with no clinical side effect). Three (20%) superficial wound infections were observed and treated by local debridement and antibiotics. One patient (6.6%) developed a pseudarthrosis and increasing kyphosis, which required surgical revision. One patient (6.6%) had a screw loosening, which didn’t require revision because asymptomatic.

Conclusion: In cases of reduced bone quality (e.g., in patients suffering from osteoporosis or osteolytic tumors), screw augmentation with PMMA injection is a good alternative method to provide better fixation and improve stability. Nevertheless, this procedure is associated with a high incidence of complications.