Does the Sagittal Balance Influence Microsurgical Results for Spinal Stenosis?

Study Design. Retrospective study. Objective. Lumbar spinal stenosis (LSS) is known as one of the most frequent causes of spinal surgery. Since sagittal balance (SB) has drawn scientific attention in recent years, questions have been raised, as to whether there is a need to restore SB for the best clinical outcome in every spinal surgery. This study evaluated the influence of SB on the clinical outcome of patients with LSS in a long-term follow-up of more than 4 years. Background. Results of short-term follow-up did not show any association between clinical outcome and the degree of sagittal imbalance in patients with LSS, who received microsurgical decompression alone. Data concerning the long-term influence of SB are lacking. Patients and Methods. A total of 136 patients were included and received a 1-year follow-up. Seventy-two subjects underwent additional long-term follow-up (51 mo). The patients received preoperative and follow-up long-standing spinal radiographs. Patients were assigned to one of 3 groups, according to their SB [normal balance, minor loss of balance (miIB), and major loss of balance]. Clinical outcome parameters were determined by evaluating the Roland-and-Morris Disability Questionnaire, Oswestry-Disability-Index, Odom criteria, Short Form 36-item score, Visual Analog Scales for pain, and walking distance. Results. Long-term follow-up showed a significant improvement of clinical outcome parameters independently of their SB [∆ Oswestry Disability Index (ODI)_normal balance = -23.0±18.9; ∆ODI_miIB = - 26.9±21.6; ∆ODI_major loss of balance = -21.6 ±25.1]. There was no significant difference among the 3 groups in pain, disability, and quality of life. The miIB group benefitted most concerning walking distance. A relevant change concerning the SB was not detected at 4 years after surgery. Conclusions: SB does not influence the long-term clinical outcome in patients with symptomatic LSS after microsurgical decompression. Patients without obvious instability benefit significantly from microsurgery, regardless of their preoperative global SB. The initial pathologic SB in patients with LSS appears to represent true structural changes of the spine, rather than a pseudo-imbalance due to a compensatory mechanism to relieve claudication.