Methods: This study included 138 patients who underwent PLIF, with a mean age of 67 years and a follow-up period of 12 months. At 12 months postoperatively, lumbar computed tomography (CT) was performed to assess SL, and patients were categorized into SL and nonloosening (NL) groups accordingly. A propensity score-matched model was used to adjust for age, sex, and body mass index (BMI). Propensity score matching was performed to compare outcomes between the SL and NL groups. Results: Among the 138 patients, 29 (21%) developed SL following PLIF. Preliminary analysis revealed that the patients in the SL group were older and exhibited decreased femoral neck bone mineral density, preoperative pelvic retroversion, poor whole spine alignment, and lesser improvement in HRQOL compared with the NL group. Using propensity score matching, 22 patients were selected from each group (mean age, 72 years) (C-statistic=0.78). The propensity score-matched analysis demonstrated significant differences in the preoperative pelvic tilt (25.9° vs. 17.8°, p=0.010) between the matched SL and NL groups. Furthermore, the Oswestry Disability Index scores indicated poorer improvements in the matched SL group than in the matched NL group at 9 months postoperatively (p=0.025). Conclusions After matching, pre- and postoperative pelvic retroversion were significantly associated with SL. Patients with SL experienced significantly poorer improvement in HRQOL at 9 months postoperatively. Therefore, implementing strategies for preventing SL may enhance early postoperative HRQOL.

Nephroblastomatosis (NBM) is a precursor of Wilms tumor. We herein report a case in which Wilms tumor was initially suspected and the affected kidney was removed.The tumor was subsequently diagnosed as intralobar NBM and a favorable outcome was achieved with postoperative chemotherapy. A 2-year-old boy who presented with gross hematuria was found to have an enlarged left kidney with hydronephrosis.Needle biopsy of the left kidney suggested Wilms tumor and left nephrectomy was performed. The tumor was histopathologically diagnosed as intralobar NBM.Although NBM is regarded as a precancerous lesion, a definite treatment plan has not yet been established. In the present case, we used a similar chemotherapy regimen to that for Wilms tumor. Eight years after the completion of chemotherapy, Wilms tumor has not developed or recurred. Appropriate management plans need to be developed by accumulating similar cases.