Kai-Ming Fu

BACKGROUND AND OBJECTIVES: Minimally clinically important difference (MCID) defines the smallest difference in patient-reported outcomes (PROs) required for a level of clinical improvement. The hypothesis of this study is that at least one of the MCID thresholds in this study will provide appropriate MCID thresholds for the PROs in grade 2 spondylolisthesis. METHODS: This study used the Grade 2 Spondylolisthesis module of the Quality Outcomes Database Spine CORe ^® Study Group, which included 328 patients from 14 institutions. PROs collected include Oswestry Disability Index (ODI), Numeric Rating Scale (NRS) for back pain and leg pain, and European Quality of Life-5 Dimensions (EQ-5D). Seven MCID thresholds were calculated with North American Spine Society satisfaction scale as the anchor. Each method was evaluated using area under the curve, reflecting the ability to predict satisfaction. RESULTS: There were 328 patients with ≥80% 5-year follow-up. The optimal percentage cutoff method generally demonstrated the highest predictive accuracy for defining MCID in ODI, NRS back pain, and NRS leg pain, whereas the optimal numeric cutoff method generally demonstrated the highest predictive accuracy for EQ-5D. For ODI, 2-year optimal percentage cutoff was 30.4% and 5-year optimal percentage cutoff was 38.1%. For NRS back pain, 2-year optimal percentage cutoff was 75.0% and 5-year optimal percentage cutoff was 42.9%. For NRS leg pain, 2-year optimal percentage cutoff was 62.5% and 5-year optimal percentage cutoff was 66.6%. For EQ-5D, the optimal numeric cutoffs were 0.293 at 2 years and 0.128 at 5 years. CONCLUSION: Using satisfaction as an anchor, this study identified the optimal percentage cutoff as the most appropriate method for determining MCID in ODI and NRS pain scores, while the optimal numeric cutoff was most appropriate for EQ-5D in grade 2 spondylolisthesis. These findings provide reference definitions for evaluating postoperative improvement in this patient population.

BACKGROUND AND OBJECTIVES: Circumferential minimally invasive surgery (cMIS) techniques in adult spinal deformity (ASD) surgery may reduce physiological burden compared with open technique, but their utility in octogenarians has not been previously assessed. METHODS: Operative ASD patients aged 80 years or older with complete baseline (BL) and 2-year postoperative radiographic and health-related quality of life data were assessed and compared by surgical technique: open vs cMIS. Propensity score matching aligned groups by BL Charlson Comorbidity Index (CCI), C7-S1 sagittal vertical axis, pelvic incidence minus lumbar lordosis mismatch, and C7 plumb line. BL and peri/postoperative factors were assessed using analysis of variance and Bonferroni-adjusted analysis of covariance while controlling for BL CCI and posterior fusion length. RESULTS: Thirty-four octogenarian ASD patients met inclusion criteria, of whom 29.4% underwent cMIS and 70.6% underwent open correction. cMIS patients were less likely to require surgical intensive care unit (10% vs 75%, P < .001) and had shorter hospital stays (4.6 vs 10.1 days, P = .013). Open patients reported higher Scoliosis Research Society-22 Appearance and Mental domain scores (both P < .005) and more frequently reached minimal clinically important difference in both domains by 2 years ( P = .025, .024). cMIS patients more often required reoperation for radiographic sagittal imbalance by 2 years when controlling for CCI and levels fused (20.0% vs 8.3%, P < .001). No deaths occurred in either group by 2 years. CONCLUSION: In octogenarians undergoing ASD surgery, cMIS reduced physiological burden but had higher reoperation rates, whereas open surgery showed greater durability.

Study Design: Retrospective analysis of patients from the prospective Quality Outcomes Database Spine CORe ^® Spondylolisthesis cohort to assess the prevalence of sleep dysfunction and factors associated with improved sleep after surgery. Objective: To characterize the prevalence of sleep disruption and identify factors associated with improved sleep among patients undergoing surgery for Meyerding grade I degenerative lumbar spondylolisthesis. Summary of Background Data: Improved sleep after surgery for lumbar spinal stenosis has been reported in several studies but not in patients with spondylolisthesis. Methods: A total of 608 patients from the prospective Quality Outcomes Database Spine CORe ^® Spondylolisthesis cohort were retrospectively analyzed. Patients were included in this study if they responded to the sleep subitem of the Oswestry Disability Index (ODI) at baseline and 24-month follow-up. The level of sleep dysfunction was assessed and compared at baseline and 24-month follow-up using univariable and multivariable statistics. Results: Overall, 526 of the 608 patients met the inclusion criteria. At baseline, 455 patients (86.5%) had sleep disruption. At 24 months or greater, 325 patients (71.4% of the 455 impaired) had improved sleep, with 184 patients (40.4%) reporting no disruption of sleep postoperatively. In multivariable analyses, improvement in sleep was predicted by a higher baseline ODI (OR=1.01, 95% CI: 1.001–1.01, P P =0.002) and higher ASA grade (OR=1.15, 95% CI: 1.02–1.30, P =0.03) in the 65 years or younger cohort, while minimally invasive techniques (OR=1.14, 95% CI: 1.01–1.30, P =0.04) were significant in the 65 years of age or older cohort. Conclusion: Most patients (86.5%) presenting for surgery for low-grade degenerative spondylolisthesis have impaired sleep. However, 24 months after surgery, over 70% of patients with baseline dysfunction reported improvements with 40.4% reporting no sleep dysfunction.

BACKGROUND: Safe posterior cervical spine surgery requires in-depth understanding of the surgical anatomy and common variations. The cervical pedicle attachment site to the vertebral body (VB) affects the location of exiting nerve roots and warrants preoperative evaluation. The relative site of attachment of the cervical pedicle has not been previously described. OBJECTIVE: To describe the site of the pedicle attachment to the VB in the subaxial cervical spine. METHODS: Cervical spine computed tomography scans without any structural, degenerative, or traumatic pathology as read by a board-certified neuroradiologist during 2021 were reviewed. Multiplanar reconstructions were created and cross-registered. The pedicle's attachment to the VB was measured relative to the VB height using a novel calculation system. RESULTS: Fifty computed tomography scans met inclusion criteria yielding 600 total pedicles between C3-T1 (100 per level). The average patient age was 26 ± 5.3 years, and 21/50 (42%) were female. 468/600 (78%) pedicles attached in the cranial third of the VB, 132/600 (22%) attached in the middle third, and 0 attached to the caudal third. The highest prevalence of variant anatomy occurred at C3 (36/100 C3 pedicles; 36%). CONCLUSION: In the subaxial cervical spine, pedicles frequently attach to the top third of the VB, but significant variation is observed. The rate of variation is highest at C3 and decreases linearly with caudal progression down the subaxial cervical spine to T1. This is the first report investigating this morphological phenomenon.

OBJECTIVE: Minimally invasive surgery (MIS) for spinal deformity uses interbody techniques for correction, indirect decompression, and arthrodesis. Selection criteria for choosing a particular interbody approach are lacking. The authors created the minimally invasive interbody selection algorithm (MIISA) to provide a framework for rational decision-making in MIS for deformity. METHODS: A retrospective data set of circumferential MIS (cMIS) for adult spinal deformity (ASD) collected over a 5-year period was analyzed by level in the lumbar spine to identify surgeon preferences and evaluate segmental lordosis outcomes. These data were used to inform a Delphi session of minimally invasive deformity surgeons from which the algorithm was created. The algorithm leads to 1 of 4 interbody approaches: anterior lumbar interbody fusion (ALIF), anterior column release (ACR), lateral lumbar interbody fusion (LLIF), and transforaminal lumbar interbody fusion (TLIF). Preoperative and 2-year postoperative radiographic parameters and clinical outcomes were compared. RESULTS: Eleven surgeons completed 100 cMISs for ASD with 338 interbody devices, with a minimum 2-year follow-up. The type of interbody approach used at each level from L1 to S1 was recorded. The MIISA was then created with substantial agreement. The surgeons generally preferred LLIF for L1–2 (91.7%), L2–3 (85.2%), and L3–4 (80.7%). ACR was most commonly performed at L3–4 (8.4%) and L2–3 (6.2%). At L4–5, LLIF (69.5%), TLIF (15.9%), and ALIF (9.8%) were most commonly utilized. TLIF and ALIF were the most selected approaches at L5–S1 (61.4% and 38.6%, respectively). Segmental lordosis at each level varied based on the approach, with greater increases reported using ALIF, especially at L4–5 (9.2°) and L5–S1 (5.3°). A substantial increase in lordosis was achieved with ACR at L2–3 (10.9°) and L3–4 (10.4°). Lateral interbody arthrodesis without the use of an ACR did not generally result in significant lordosis restoration. There were statistically significant improvements in lumbar lordosis (LL), pelvic incidence–LL mismatch, coronal Cobb angle, and Oswestry Disability Index at the 2-year follow-up. CONCLUSIONS: The use of the MIISA provides consistent guidance for surgeons who plan to perform MIS for deformity. For L1–4, the surgeons preferred lateral approaches to TLIF and reserved ACR for patients who needed the greatest increase in segmental lordosis. For L4–5, the surgeons’ order of preference was LLIF, TLIF, and ALIF, but TLIF failed to demonstrate any significant lordosis restoration. At L5–S1, the surgical team typically preferred an ALIF when segmental lordosis was desired and preferred a TLIF if preoperative segmental lordosis was adequate.

Adult spinal deformity (ASD) can be associated with substantial suffering due to pain and disability. Surgical intervention for achieving neural decompression and restoring physiological spinal alignment has shown to result in significant improvement in pain and disability through patient-reported outcomes. Traditional open approaches involving posterior osteotomy techniques and instrumentation are effective based on clinical outcomes but associated with high complication rates, even in the hands of the most experienced surgeons. Minimally invasive techniques may offer benefit while decreasing associated morbidity. Minimally invasive surgery (MIS) for ASD has evolved over the past 20 years, driven by improved understanding of open procedures along with novel technique development and technologic advancements. Early efforts were hindered due to suboptimal outcomes resulting from high pseudarthrosis, inadequate correction, and fixation failure rates. To address this, multi-center collaborative groups have been established to study large numbers of ASD patients which have been vital to understanding optimal patient selection and individualized management strategies. Different MIS decision-making algorithms have been described to better define appropriate candidates and interbody selection approaches in ASD. The purpose of this state of the review is to describe the evolution of MIS surgery for adult deformity with emphasis on landmark papers, and to discuss specific MIS technology for ASD, including percutaneous pedicle screw instrumentation, hyperlordotic grafts, three-dimensional navigation, and robotics.