Prospective radiographic study.
To investigate the feasibility of controlling quality of reconstructed sagittal balance for sagittal imbalance.
Patients with sagittal imbalance cannot walk or stand erect without overwork of musculature because of compromised biomechanical advantage. The result is muscle fatigue and activity-related pain. During reconstructive surgery, restoration of optimal sagittal balance is crucial for obtaining satisfactory clinical results. However, there is no way to control quality of reconstructed sagittal balance before or during surgery.
A method was developed to determine the lumbosacral curve in a way that theoretically would bring sagittal balance to an ideal state by calculation and simulation for each patient before surgery and then template rods of the curve and a blueprint were made accordingly for operative procedures. Ninety-four consecutive patients with sagittal imbalance due to lumbar kyphosis were treated for intractable pain and then followed up for a mean of 4.3 years. Radiographs were analyzed before surgery, 2 months after surgery, and at most recent follow-up.
The mean estimated values of L1–S1 lordosis, sacral inclination angle, sacrofemoral distance, and distribution of L1–S1 lordosis at the closing-opening wedge osteotomy site and L4–S1 segments were −30.8°, 24.6°, 0 mm, 16.1% (−5°), and 62% (−19°), respectively. The mean reconstructed values were 241.1°, 23.3°, 3.9 mm, 41% (−17°), and 46% (−19°), respectively. There were significant differences between estimated and reconstructed values of L1–S1 lordosis and the percentage of distributions; however, there was no significant difference between the estimated and reconstructed magnitude of L4–S1 lordosis, sacral inclination angle, and sacrofemoral distance. A properly oriented pelvis can be brought nearly directly above the hip axis. The mean sagittal global balance, represented by the distance between the vertical line through the hip axis and sacral promontory, improved from 61.4 mm before surgery to 3.9 mm 2 months after surgery, and 1.3 mm at final follow-up. Normal sagittal global balance was reconstructed and maintained. The mean sagittal spinal balance measured as the horizontal distance between the C7 sagittal plumb line and the posterior superior corner of S1 improved from 97.4 mm before surgery to 11 mm 2 months after surgery. However, there was significant loss of sagittal spinal balance to 25.4 mm at the final visit. Normal sagittal spinal balance was reconstructed and appeared to be maintained. The magnitude of T1–T12 kyphosis compensated from 13° before surgery to 25.2° 2 months after surgery and 34.5° at final follow-up.
Quality control of the reconstructed sagittal balance for sagittal imbalance is possible. Correctly orienting the pelvis, reconstructed by the restoration of enough L1–S1 lordosis with adequate distribution at L4–S1 segments, is a matter of critical importance for optimizing reconstructed sagittal balance. The correctly oriented pelvis can be determined before surgery. Preventing junctional fracture and persistent rehabilitation of surgically injured lumbar extensor musculature are crucial for maintaining the reconstructed sagittal balance.
The lumbosacral curve that theoretically would bring sagittal balance to an ideal state can be determined before surgery. Optimal sagittal balance can be reconstructed after instrumentation-assisted correction with the template rod of the lumbosacral curve. A correctly oriented pelvis, which can be determined before surgery, reconstructed by restoration of enough L1–S1 lordosis with adequate distribution at L4–S1 segments is of critical importance for optimizing reconstructed sagittal balance.
*Taiwan Spine Center, Jen-Ai Hospital, Taichung, Taiwan, Republic of China
†Department of Bio-Industrial Mechatronics Engineering, National Chung Hsing University, Taichung, Taiwan, Republic of China
‡Affiliated Hospital of Changchun University of Chinese medicine, Changchun, Jilin, People's Republic of China.
Address correspondence and reprint requests to Kao-Wha Chang, MD, PhD, Taiwan Spine Center, Jen-Ai Hospital, No. 483 Dong Rong Rd, Tali, Taichung, Taiwan, Republic of China; E-mail: email@example.com
Acknowledgment date: March 30, 2010. Revision date: May 26, 2010. Acceptance date: June 29, 2010.
The manuscript submitted does not contain information about medical device(s)/drug(s).
No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.