Objective To evaluate long-term bone quality changes within the fusion construct (FC) after 2- to 3-level lumbar fusion using computed tomography (CT)-derived Hounsfield units (HUs).
Methods Among 520 screened patients, 222 who underwent 2- to 3-level posterior lumbar interbody fusion met the inclusion criteria. HU values were measured on CT scans preoperatively, at 1-year postoperative, and at final follow-up. The percentage change in HU (HU [final–pre]%) was calculated for each vertebral level.
Results At the final follow-up, the FC demonstrated a significant decline in HU compared to preoperative values (median [10th–90th percentile], 132.0 [86.5–220.4]; 95% confidence interval [CI], 116.0–142.5 vs. 124.5 [71.0– 210.0]; 109.8–135.1; HU (final–pre)%: -11.0 [-62.0 to 48.5]; -19.9 to -6.1; p<0.001). In contrast, HU increased significantly at the uppermost instrumented vertebra (HU (final–pre)%: median [10th–90th percentile], 28.3 [-19.9 to 102.9]; 95% CI, 21.1–36.4; p<0.001), likely reflecting increased mechanical demands. Subgroup analysis revealed a more pronounced decline in HU in patients with longer follow-up durations, particularly in the FC group (p=0.003).
Conclusion CT-derived HU revealed progressive trabecular bone loss within FC over time after lumbar fusion. In patients with longer postoperative intervals, clinicians should remain aware of the potential weakening of the FC, which has important implications when considering implant removal or planning revision surgery.
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A Commentary on “Disuse Bone Loss in Fusion Constructs After Multilevel Lumbar Fusion: A Computed Tomography Hounsfield Unit Analysis” Jiajun Deng, Hongsheng Lin Neurospine.2026; 23(2): 504. CrossRef
Reply Letter: A Commentary on “Disuse Bone Loss in Fusion Constructs After Multilevel Lumbar Fusion: A Computed Tomography Hounsfield Unit Analysis” Hyun-Jun Jang, Dongkyu Kim, Bong-Ju Moon, Kyung-Hyun Kim, Jeong-Yoon Park, Sung-Uk Kuh, Keun-Su Kim, Dong-Kyu Chin Neurospine.2026; 23(2): 506. CrossRef
Objective We aimed to investigate the incidence of delayed-onset neurological deficits (DONDs), DOND-related reoperation rates following adult spinal deformity (ASD) surgery, and efficacy of transverse process hooks (TPHs) at the uppermost instrumented vertebra (UIV) compared to pedicle screws (PSs).
Methods We included 90 consecutive patients who underwent instrumented fusion from the sacrum to the distal thoracic spine for ASD, with a minimum follow-up of 24 months. Clinical and radiological outcomes were compared between 33 patients in the TPH group and 57 patients in the PS group, using the Scoliosis Research Society-22 Outcomes questionnaire (SRS-22), Medical Outcomes Study Questionnaire Short-Form 36 (SF-36), and various spinal sagittal parameters.
Results While absent in the TPH group, myelopathy occurred in 15.8% of the PS group, wherein 15 patients underwent reoperation. The change in the proximal junctional angle, from the pre- to postoperative assessment, was lower in the TPH group than in the PS group (0.2 vs. 6.6, p=0.002). Postoperative facet degeneration in the PS group progressed more significantly than in the TPH group (0.5 vs. 0.1, p=0.002). Surgical outcomes were comparable for both groups, except for the back visual analogue scale (3.5 vs. 4.1, p=0.010) and SRS-22 domains, including pain and satisfaction (3.3 vs. 2.9, p=0.033; 3.7 vs. 3.3, p=0.041). No intergroup difference was observed in SF-36.
Conclusion Using TPHs at the UIV level can prevent DOND, and thereby prevent postoperative myelopathy that necessitates reoperation; thus, TPHs is preferable over PSs in ASD surgery.
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Neurospine 2021;18(3):597-607. Published online September 30, 2021
Objective In this study, we investigate about relationship between postoperative global sagittal imbalance and occurrence of mechanical complications after adult spinal deformity (ASD) surgery. In global sagittal balance parameters, odontoid-hip axis (OD-HA) angle and T1 pelvic angle (TPA) were analyzed.
Methods Between January 2009 and December 2016, 199 consecutive patients (26 males and 173 females) with ASD underwent corrective fusion of more than 4 levels and were followed up for more than 2 years. Immediate postoperative and postoperative 2 years whole spine x-rays were checked for evaluating immediate postoperative OD-HA, TPA, and other parameters. In clinical outcomes, back and leg pain visual analogue scale, Scoliosis Research Society-22 spinal deformity questionnaire (SRS-22), Oswestry Disability Index (ODI), 36- item Short Form Health Survey (SF-36) were evaluated.
Results Based on the occurrence of mechanical complications, a comparative analysis was performed for each parameter. In univariable analysis, mechanical complications were significantly much more occurred in OD-HA abnormal group (odds ratio [OR], 3.296; p < 0.001; area under the curve [AUC] = 0.645). In multivariable analysis, the result was much more related (OR, 2.924; p = 0.001; AUC = 0.727). In contrast, there was no significant difference between normal and the occurrence of mechanical complications in TPA. In clinical outcomes (normal vs. abnormal), the differences of SRS-22 (0.88 ± 0.73 vs. 0.68 ± 0.64, p = 0.042), ODI (-24.72 ± 20.16 vs. -19.01 ± 19.95, p = 0.046), SF-36 physical composite score (19.33 ± 18.55 vs. 12.90 ± 16.73, p = 0.011) were significantly improved in OD-HA normal group.
Conclusion The goal of ASD surgery is to improve patient life quality through correction. In our study, TPA was associated with spinopelvic parameter and OD-HA angle was associated with health-related quality of life and complications. OD-HA angle is predictable factor for mechanical complications after ASD surgery.
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Methods We performed a retrospective analysis of 162 patients over 80 years of age who underwent posterior lumbar fusion or decompressive laminectomy between January 2011 and September 2016. We examined patient survival and modified frailty index (mFI) from medical records.
Results By October 2019, 29 of 162 patients had expired (follow-up period: 1–105 months). Three-month mortality was 1.9%, and 1-year mortality was 4.9%. Frailty did not affect long-term survival at 1 year but was associated with 3-month mortality (p = 0.024).
Conclusion There was no relationship in long-term survival according to frailty in patients 80 years of age or older, but a difference was identified in short-term mortality. When making a surgical decision for lumbar spine surgery in frail patients over 80 years of age, surgeons should pay attention to the short-term prognosis.
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