VOL. 95-B, No. 3, MARCH 2013 401  SPINE Comparison of unipedicular and bipedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures A PROSPECTIVE RANDOMISED STUDY B. J. Rebolledo, B. P. Gladnick, A. Unnanuntana, J. T. Nguyen, C. K. Kepler, J. M. Lane From Hospital for Special Surgery, New York, New York, United States  B. J. Rebolledo, MD, Resident  B. P. Gladnick, MD, Resident  J. T. Nguyen, MPH, Statistician, Clinical Research Assistant  J. M. Lane, MD, Attending Orthopaedic Surgeon, Associate Professor, Chief Metabolic Bone Disease Service Hospital for Special Surgery, 535 East 70th Street, New York, New York 10021, USA.  A. Unnanuntana, MD, Attending Orthopaedic Surgeon, Clinical Instructor Siriraj Hospital, Mahidol University, 2 Prannok Road, Bangkoknoi District, Bangkok 10700, Thailand.  C. K. Kepler, MD, MBA, Assistant Professor Rothman Institute, Thomas Jefferson University, 111 South 11th Street, Philadelphia, Pennsylvania 19107, USA. Correspondence should be sent to Dr B. J. Rebolledo; e-mail: rebolledob@hss.edu ©2013 The British Editorial Society of Bone & Joint Surgery doi:10.1302/0301-620X.95B3. 29819 $2.00 Bone Joint J 2013;95-B:401–6. Received 4 July 2012; Accepted after revision 4 December 2012 This is a prospective randomised study comparing the clinical and radiological outcomes of uni- and bipedicular balloon kyphoplasty for the treatment of osteoporotic vertebral compression fractures. A total of 44 patients were randomised to undergo either uni- or bipedicular balloon kyphoplasty. Self-reported clinical assessment using the Oswestry Disability Index, the Roland-Morris Disability questionnaire and a visual analogue score for pain was undertaken pre-operatively, and at three and twelve months post-operatively. The vertebral height and kyphotic angle were measured from pre- and post-operative radiographs. Total operating time and the incidence of cement leakage was recorded for each group. Both uni- and bipedicular kyphoplasty groups showed significant within-group improvements in all clinical outcomes at three months and twelve months after surgery. However, there were no significant differences between the groups in all clinical and radiological outcomes. Operating time was longer in the bipedicular group (p < 0.001). The incidence of cement leakage was not significantly different in the two groups (p = 0.09). A unipedicular technique yielded similar clinical and radiological outcomes as bipedicular balloon kyphoplasty, while reducing the length of the operation. We therefore encourage the use of a unipedicular approach as the preferred surgical technique for the treatment of osteoporotic vertebral compression fractures. Cite this article: Bone Joint J 2013;95-B:401–6. Osteoporosis is the most common metabolic bone disease in the United States, characterised by decreased bone mass, alteration of bone microarchitecture and increased risk of fragility fracture. 1 The most common fragility fractures associated with osteoporosis are vertebral com- pression fractures, affecting 25% of post- menopausal women and accounting for over 700 000 fractures annually in the United States. 2-4 The presence of vertebral compression fractures can lead to chronic and disabling symp- toms. 1-5 In 2005 it was estimated that the annual cost of fractures related to osteoporosis in the United States was $16.9 billion, with the expec- tation that this figure would rise to $25.3 billion by 2025. 5 The aim of surgical treatment is to address the associated morbidity by providing pain relief and early stabilisation of the fractures. Balloon kyphoplasty achieves reduction of the vertebral fracture using a balloon tamp inserted into the vertebral body by a trans- pedicular approach, followed by fixation of the fracture fragments with polymethylmeth- acrylate (PMMA) bone cement. 6,7 It has been shown in randomised studies that balloon kyphoplasty provides significant pain relief and improved function. 8,9 It has also been shown to be cost-effective compared with non- surgical management 10 and to restore vertebral body height. 11 The American Academy of Orthopaedic Surgeons (AAOS) has recom- mended that kyphoplasty should be considered for patients with osteoporotic vertebral com- pression fractures. 12 The standard technique for kyphoplasty involves a bipedicular approach using two balloon tamps, 6 but recently a unipedicular approach has been advocated, reducing the operating time and risks, and increasing the cost-effectiveness of the procedure. 13 The purpose of this study was to determine whether a uni- or bipedicular technique was superior in terms of pain relief, improvement of function and correction of deformity, based on radiological measures. Additionally, we evaluated the operating time, the amount of cement injected and the inci- dence of cement extravasation associated with each technique. Patients and Methods Patients were identified and recruited for this prospective randomised trial from the