Prognostic factors for surgical outcomes including preoperative total knee replacement and knee osteoarthritis status in female patients with lumbar spinal stenosis

Study Design: A retrospective clinical case series. Objective: To investigate knee osteoarthritis (KOA) and total knee replacement (TKR) status as prognostic factors for surgical outcomes in female patients with lumbar spinal stenosis (LSS). Summary of Background Data: There have been many reports on numerous prognostic factors for surgical outcomes in patients with degenerative lumbar conditions; however, there has been no report on the surgical outcome in patients who underwent spinal surgery with coexisting KOA and TKR. Methods: This study included 141 female patients (mean age, 67.6 y) who underwent spinal surgery for LSS between January 2006 and December 2010. At 1 year postoperatively, surgical outcomes were measured using the Oswestry disability index (ODI). Various clinical factors including KOA and TKR were analyzed as prognostic factors for surgical outcomes. Results: Mean average scores at preoperative evaluation were 26.1±6.6 in the no KOA group, 23.6±7.9 in the KOA group, and 30.4±6.7 in the TKR group (P<0.05). Mean average scores at postoperative 1 year were 13.8±8.5 in the no KOA group, 16.8±9.5 in the KOA group, and 21.4±5.7 in the TKR group (P<0.05, Mann-Whitney U test). Preoperative ODI scores were shown to be significantly affected by the TKR status only (P<0.05), and were significantly higher in the TKR patient group. ODI scores at postoperative 3 months were significantly correlated with the preoperative ODI and the operational level (P<0.05). At postoperative 1 year, ODI scores were shown to be affected by the operational level, the preoperative ODI, and the presence of advanced radiographic KOA (Kellgren/Lawrence grades III and IV) (P<0.05). Conclusions: A poor preoperative functional score, the presence of preoperative KOA, and longer operational levels were shown to be poor prognostic factors for the 1-year surgical outcome of LSS. Also, patients in the TKR group showed the worst ODI scores at preoperative and postoperative 1-year evaluations. Consideration of these factors when planning for spine surgery could be helpful in predicting the surgical outcomes of lumbar spinal surgery.