RESUMEN

BACKGROUND: The use of the lateral decubitus approach for L5-S1 anterior lumbar interbody fusion (LALIF) is a recent advancement capable of facilitating single-position surgery, revision operations, and anterior column reconstruction. To the authors' knowledge, this is the first description of the use of LALIF at L5-S1 for failed prior transforaminal lumbar interbody fusion (TLIF) and anterior column reconstruction. Using an illustrative case, the authors discuss their experience using LALIF at L5-S1 for the revision of pseudoarthrosis and TLIF failure. OBSERVATIONS: The patient had prior attempted L2 to S1 fusion with TLIF but suffered from hardware failure and pseudoarthrosis at the L5-S1 level. LALIF was used to facilitate same-position revision at L5-S1 in addition to further anterior column revision and reconstruction by lateral lumbar interbody fusion at the L1-2 level. Robotic posterior T10-S2 fusion was then added to provide stability to the construct and address the patient's scoliotic deformity. No complications were noted, and the patient was followed until 1 year after the operation with a favorable clinical and radiological result. LESSONS: Revision of a prior failed L5-S1 TLIF with an LALIF approach has technical challenges but may be advantageous for single position anterior column reconstruction under certain conditions.

RESUMEN

OBJECTIVE: In an effort to prevent loss of segmental lordosis (SL) with minimally invasive interbody fusions, manufacturers have increased the amount of lordosis that is built into interbody cages. However, the relationship between cage lordotic angle and actual SL achieved intraoperatively remains unclear. The purpose of this study was to determine if the lordotic angle manufactured into an interbody cage impacts the change in SL during minimally invasive surgery (MIS) for lumbar interbody fusion (LIF) done for degenerative pathology. METHODS: The authors performed a retrospective review of a single-surgeon database of adult patients who underwent primary LIF between April 2017 and December 2018. Procedures were performed for 1-2-level lumbar degenerative disease using contemporary MIS techniques, including transforaminal LIF (TLIF), lateral LIF (LLIF), and anterior LIF (ALIF). Surgical levels were classified on lateral radiographs based on the cage lordotic angle (6°-8°, 10°-12°, and 15°-20°) and the position of the cage in the disc space (anterior vs posterior). Change in SL was the primary outcome of interest. Subgroup analyses of the cage lordotic angle within each surgical approach were also conducted. RESULTS: A total of 116 surgical levels in 98 patients were included. Surgical approaches included TLIF (56.1%), LLIF (32.7%), and ALIF (11.2%). There were no differences in SL gained by cage lordotic angle (2.7° SL gain with 6°-8° cages, 1.6° with 10°-12° cages, and 3.4° with 15°-20° cages, p = 0.581). Subgroup analysis of LLIF showed increased SL with 15° cages only (p = 0.002). The change in SL was highest after ALIF (average increase 9.8° in SL vs 1.8° in TLIF vs 1.8° in LLIF, p < 0.001). Anterior position of the cage in the disc space was also associated with a significantly greater gain in SL (4.2° vs -0.3°, p = 0.001), and was the only factor independently correlated with SL gain (p = 0.016). CONCLUSIONS: Compared with cage lordotic angle, cage position and approach play larger roles in the generation of SL in 1-2-level MIS for lumbar degenerative disease.

Asunto(s)

RESUMEN

OBJECTIVE: In this study the authors compared the anterior lumbar interbody fusion (ALIF) and posterior transforaminal lumbar interbody fusion (TLIF) techniques in a homogeneous group of patients affected by single-level L5-S1 degenerative disc disease (DDD) and postdiscectomy syndrome (PDS). The purpose of the study was to analyze perioperative, functional, and radiological data between the two techniques. METHODS: A retrospective analysis of patient data was performed between 2015 and 2018. Patients were clustered into two homogeneous groups (group 1 = ALIF, group 2 = TLIF) according to surgical procedure. A statistical analysis of clinical perioperative and radiological findings was performed to compare the two groups. A senior musculoskeletal radiologist retrospectively revised all radiological images. RESULTS: Seventy-two patients were comparable in terms of demographic features and surgical diagnosis and included in the study, involving 32 (44.4%) male and 40 (55.6%) female patients with an average age of 47.7 years. The mean follow-up duration was 49.7 months. Thirty-six patients (50%) were clustered in group 1, including 31 (86%) with DDD and 5 (14%) with PDS. Thirty-six patients (50%) were clustered in group 2, including 28 (78%) with DDD and 8 (22%) with PDS. A significant reduction in surgical time (107.4 vs 181.1 minutes) and blood loss (188.9 vs 387.1 ml) in group 1 (p < 0.0001) was observed. No significant differences in complications and reoperation rates between the two groups (p = 0.561) was observed. A significant improvement in functional outcome was observed in both groups (p < 0.001), but no significant difference between the two groups was found at the last follow-up. In group 1, a faster median time of return to work (2.4 vs 3.2 months) was recorded. A significant improvement in L5-S1 postoperative lordosis restoration was registered in the ALIF group (9.0 vs 5.0, p = 0.023). CONCLUSIONS: According to these results, interbody fusion is effective in the surgical management of discogenic pain. Even if clinical benefits were achieved earlier in the ALIF group (better scores and faster return to work), both procedures improved functional outcomes at last follow-up. The ALIF group showed significant reduction of blood loss, shorter surgical time, and better segmental lordosis restoration when compared to the TLIF group. No significant differences in postoperative complications were observed between the groups. Based on these results, the ALIF technique enhances radiological outcome improvement in spinopelvic parameters when compared to TLIF in the management of adult patients with L5-S1 DDD.

Asunto(s)

RESUMEN

OBJECTIVE: Patients undergoing long-segment fusions from the lower thoracic (LT) spine to the sacrum for adult spinal deformity (ASD) correction are at risk for proximal junctional kyphosis (PJK). One mechanism of PJK is fracture of the upper instrumented vertebra (UIV) or higher (UIV+1), which may be related to bone mineral density (BMD). Because Hounsfield units (HUs) on CT correlate with BMD, the authors evaluated whether HU values were correlated with PJK after long fusions for ASD. METHODS: The authors performed a retrospective study of patients older than 50 years who had undergone ASD correction from the LT spine to the sacrum in the period from October 2007 to January 2018 and had a minimum 2-year follow-up. Demographic and spinopelvic parameters were measured. HU values were measured on preoperative CT at the UIV, UIV+1, and UIV+2 (2 levels above the UIV) levels and were assessed for correlations with PJK. RESULTS: The records of 127 patients were reviewed. Fifty-four patients (19 males and 35 females) with a mean age of 64.91 years and mean follow-up of 3.19 years met the study inclusion criteria; there were 29 patients with PJK and 25 patients without. There was no statistically significant difference in demographics or follow-up between these two groups. Neither was there a difference between the groups with regard to postoperative pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), PI minus LL (PI-LL), thoracic kyphosis (TK), or sagittal vertical axis (SVA; all p > 0.05). Postoperative pelvic tilt (p = 0.003) and T1 pelvic angle (p = 0.014) were significantly higher in patients with PJK than in those without. Preoperative HUs at UIV, UIV+1, and UIV+2 were 120.41, 124.52, and 129.28 in the patients with PJK, respectively, and 152.80, 155.96, and 160.00 in the patients without PJK, respectively (p = 0.011, 0.02, and 0.018). Three receiver operating characteristic (ROC) curves for preoperative HU values at the UIV, UIV+1, and UIV+2 as a predictor for PJK were established, with areas under the ROC curve of 0.710 (95% CI 0.574-0.847), 0.679 (95% CI 0.536-0.821), and 0.681 (95% CI 0.539-0.824), respectively. The optimal HU value by Youden index was 104 HU at the UIV (sensitivity 0.840, specificity 0.517), 113 HU at the UIV+1 (sensitivity 0.720, specificity 0.517), and 110 HU at the UIV+2 (sensitivity 0.880, specificity 0.448). CONCLUSIONS: In patients undergoing long-segment fusions from the LT spine to the sacrum for ASD, PJK was associated with lower HU values on CT at the UIV, UIV+1, and UIV+2. The measurement of HU values on preoperative CTs may be a useful adjunct for ASD surgery planning.

Asunto(s)

RESUMEN

OBJECTIVE: Scheuermann kyphosis (SK) could require surgical treatment in certain situations. A posterior reduction is the most widespread treatment so far, although the development of proximal junctional kyphosis (PJK) is one of the possible complications of this procedure. The contour of the proximal part of the rod could influence the occurrence of PJK in SK patients. The objective of this study was to analyze the impact of the proximal rod contour on the occurrence of a PJK complication in SK patients. METHODS: This retrospective monocentric study was performed in the Nanjing Spine Surgery Department. All eligible patients had undergone posterior correction surgery with pedicle screws only between 2002 and 2017 and had at least 24 months of follow-up. The presence of PJK was quantified on radiographs using the proximal junctional angle (PJA > 10° at the last follow-up). The authors propose a new radiological parameter to measure the angulation of the proximal part of the instrumentation: the proximal contouring rod angle (PCRA) is the angle between the upper endplate of the upper instrumented vertebra (UIV) and the lower endplate of the second vertebra caudal to the UIV. The patients were analyzed according to the presence or absence of PJK. A t-test, receiver operating characteristic (ROC) curve analysis, and logistic regression analysis were performed for statistical analysis. RESULTS: Sixty-two patients treated for SK were included in this study. The mean age was 18.6 ± 8.5 years, and the mean follow-up was 42.5 ± 16.4 months. The mean correction rate of global kyphosis was 46.4% ± 13.7%. At the last follow-up, 17 patients (27.4%) presented with PJK. No significant difference was found between the PJK and non-PJK groups in terms of age and other preoperative variables. A significant difference in the postoperative PCRA was found between the PJK and non-PJK groups (8.2° ± 4.9° vs 15.7° ± 6.6°, respectively; p = 0.001). A postoperative PCRA less than 10.1° predicted a significantly higher risk for PJK (p = 0.002, OR 2.431, 95% CI 1.781-4.133). CONCLUSIONS: Under-contouring of the proximal part of the rods (lower than 10°) is a risk factor for PJK after posterior correction of SK.

RESUMEN

OBJECTIVE: Few studies have addressed that dynamic sagittal imbalance can develop distal to the spinal fusion and cause sagittal malalignment, unlike proximal junctional kyphosis (PJK) in the proximal portion. The purpose of this study was to investigate risk factors between the 2 different types of postoperative sagittal imbalance after long fusion to the sacrum for the treatment of degenerative sagittal imbalance (DSI). METHODS: Eighty patients who had undergone surgical correction for DSI were included. Radiographic measurements included spinopelvic parameters on whole-spine plain radiographs and degeneration of paravertebral muscles on MRI. Univariate and multivariate analyses for clinical and radiological factors were conducted for respective risk factors. In subgroup analyses, the 2 different types of postoperative sagittal imbalance were directly compared. RESULTS: Forty patients (50%) developed postoperative sagittal imbalance; of these patients, 22 (55.0%) developed static proximal kyphosis from PJK, and 18 patients (45.0%) developed dynamic sagittal imbalance without PJK. The independent risk factors in proximal kyphosis were greater postoperative pelvic tilt (HR 1.11) and less change in sacral slope (SS) (HR 1.09), whereas there were more fusion levels (HR 3.11), less change in SS (HR 1.28), and less change in thoracic kyphosis (HR 1.26) in dynamic sagittal imbalance. Directly compared with the proximal kyphosis group, dynamic sagittal imbalance was more commonly found in patients who had less correction of sagittal parameters as well as fatty atrophy of the paravertebral muscles. Clinical outcomes in the dynamic sagittal imbalance group were superior to those in the proximal kyphosis group. CONCLUSIONS: Optimal correction of sagittal alignment should be considered in long instrumented fusion for DSI, because insufficient correction might cause one of 2 different types of postoperative sagittal imbalance at different sites of decompression. Dynamic sagittal imbalance compared with proximal kyphosis was significantly associated with less correction of sagittal alignment, in conjunction with more fusion levels and degeneration of the paravertebral muscles.

RESUMEN

OBJECTIVE: Maintaining lumbosacral (LS) arthrodesis and global sagittal balance after long fusion to the sacrum remains an important issue in the surgical treatment for adult spinal deformity (ASD). The importance and usefulness of LS fixation have been documented, but the optimal surgical long fusion to the sacrum remains a matter for debate. Therefore, the authors performed a retrospective study to evaluate fusion on CT scans and the risk factors for LS pseudarthrosis (nonunion) after long fusion to the sacrum in ASD. METHODS: The authors performed a retrospective study of 59 patients with lumbar degenerative kyphosis (mean age 69.6 years) who underwent surgical correction, including an interbody fusion of the L5-S1, with a minimum 2-year follow-up. Achievement of LS fusion was evaluated by analyzing 3D-CT scans at 3 months, 6 months, 9 months, 1 year, and 2 years after surgery. Patients were classified into a union group (n = 36) and nonunion group (n = 23). Risk factors for nonunion were analyzed, including patient and surgical factors. RESULTS: The overall fusion rate was 61% (36/59). Regarding radiological factors, optimal sagittal balance at the final follow-up significantly differed between two groups. There were no significant differences in terms of patient factors, and no significant differences with respect to the use of pedicle subtraction osteotomy, the number of fused segments, the proportion of anterior versus posterior interbody fusion, S2 alar iliac fixation versus conventional iliac fixation, or loosening of sacral or iliac screws. However, the proportion of metal cages to polyetheretherketone cages and the proportion of sacropelvic fixation were significantly higher in the union group (p = 0.022 and p < 0.05, respectively). CONCLUSIONS: LS junction fusion is crucial for global sagittal balance, and the use of iliac screws in addition to LS interbody fusion using a metal cage improves the outcomes of long fusion surgery for ASD patients.

RESUMEN

OBJECTIVE: The aim of this study was to investigate sagittal alignment and compensatory mechanisms in patients with monosegmental spondylolysis (mono_lysis) and multisegmental spondylolysis (multi_lysis). METHODS: A total of 453 adult patients treated for symptomatic low-grade spondylolytic spondylolisthesis were retrospectively studied at a single center. Patients were divided into 2 subgroups, the mono_lysis group and the multi_lysis group, based on the number of spondylolysis segments. A total of 158 asymptomatic healthy volunteers were enrolled in this study as the control group. Radiographic parameters measured on standing sagittal radiographs and the ratios of L4-S1 segmental lordosis (SL) to lumbar lordosis (L4-S1 SL/LL) and pelvic tilt to pelvic incidence (PT/PI) were compared between all experimental groups. RESULTS: There were 51 patients (11.3%) with a diagnosis of multi_lysis in the spondylolysis group. When compared with the control group, the spondylolysis group exhibited larger PI (p < 0.001), PT (p < 0.001), LL (p < 0.001), and L4-S1 SL (p = 0.025) and a smaller L4-S1 SL/LL ratio (p < 0.001). When analyzing the specific spondylolysis subgroups, there were no significant differences in PI, but the multi_lysis group had a higher L5 incidence (p = 0.004), PT (p = 0.018), and PT/PI ratio (p = 0.039). The multi_lysis group also had a smaller L4-S1 SL/LL ratio (p = 0.012) and greater sagittal vertical axis (p < 0.001). CONCLUSIONS: A high-PI spinopelvic pattern was involved in the development of spondylolytic spondylolisthesis, and a larger L5 incidence might be associated with the occurrence of consecutive multi_lysis. Unlike patients with mono_lysis, individuals with multi_lysis were characterized by an anterior trunk, insufficiency of L4-S1 SL, and pelvic retroversion.

RESUMEN

OBJECTIVE: Lumbar spinal canal stenosis (LSS) and knee osteoarthritis (KOA), both of which are age-related degenerative diseases, are independently correlated with increased pain and dysfunction of the lower extremities. However, there have been few studies that investigated whether LSS patients with KOA exhibit poor clinical recovery following lumbar spinal surgery. The aim of this study was to elucidate the surgical outcomes of lumbar spinal surgery for LSS patients with KOA using multiple health-related quality of life (HRQOL) parameters. METHODS: A total of 865 consecutive patients who underwent posterior lumbar spinal surgery for LSS were retrospectively reviewed. Baseline characteristics, radiographic parameters, perioperative factors, and multiple HRQOL parameters were analyzed preoperatively and at 1-year follow-up. HRQOL items included the Zurich Claudication Questionnaire, Oswestry Disability Index, Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ). The effectiveness of surgical treatment was assessed using the JOABPEQ. The treatment was regarded as effective when it resulted in an increase in postoperative JOABPEQ score by ≥ 20 points compared with preoperative score or achievement of a postoperative score of ≥ 90 points in those with a preoperative score of < 90 points. RESULTS: A total of 32 LSS patients with KOA were identified, and 128 age- and sex-matched LSS patients without KOA were selected as controls. In both groups, all HRQOL parameters markedly improved at the 1-year follow-up. On the SF-36, the postoperative mean score for the role physical domain was significantly lower in the KOA group than in the control group (p = 0.034). The treatment was significantly less "effective" in the social life domain of JOABPEQ in the KOA group than in the control group (p < 0.001). CONCLUSIONS: The surgical outcomes of LSS patients with KOA are favorable, although poorer than those of LSS patients without KOA, particularly in terms of social life and activities. These results indicate that LSS patients with KOA experience difficulty in routine work or ordinary activities due to knee pain or restricted knee ROM even after lumbar spinal surgery. Hence, preoperative KOA status warrants consideration when planning lumbar spinal surgery and estimating surgical outcomes of LSS.

RESUMEN

OBJECTIVE: The incidence of proximal junctional kyphosis (PJK) after long-segment fixation in patients with adult spinal deformity (ASD) has been reported to range from 17% to 61.7%. Recent studies have reported using "hybrid" techniques in which semirigid fixation is introduced between the fused and flexible segments at the proximal level to allow a more gradual transition. The authors used these hybrid techniques in a clinical setting and analyzed PJK to evaluate the usefulness of the flexible rod (FR) technique. METHODS: The authors retrospectively selected 77 patients with lumbar degenerative kyphosis (LDK) who underwent sagittal correction and long-segment fixation and had follow-up for > 1 year. An FR was used in 30 of the 77 patients. PJK development and spinal sagittal changes were analyzed in the FR and non-FR groups, and the predictive factors of PJK between a PJK group and a non-PJK group were compared. RESULTS: The patient population comprised 77 patients (75 females and 2 males) with a mean (± SD) follow-up of 32.0 ± 12.7 months (36.7 ± 9.8 months in the non-FR group and 16.8 ± 4.7 months in the FR group) and mean (± SD) age of 71.7 ± 5.1 years. Sagittal balance was well maintained at final follow-up (10.5 and 1.5 mm) in the non-FR and FR groups, respectively. Thoracic kyphosis (TK) and lumbar lordosis (LL) were improved in both groups, without significant differences between the two (p > 0.05). PJK occurred in 28 cases (36.4%) in total, 3 (10%) in the FR and 25 (53.2%) in the non-FR group (p < 0.001). Postoperatively, PJK was observed at an average of 8.9 months in the non-FR group and 1 month in the FR group. No significant differences in the incidence of PJK regarding patient factors or radiological parameters were found between the PJK group and non-PJK group (p > 0.05). However, FR (vs non-FR) and interbody fusion except L5-S1 using oblique lumbar interbody fusion (vs non-oblique lumbar interbody fusion), demonstrated a significantly lower PJK prevalence (p < 0.001 and p = 0.044) among the surgical factors. CONCLUSIONS: PJK was reduced after surgical treatment with the FR in the patients with LDK. Solid long-segment fixation and the use of the FR may become another surgical option for spine surgeons who plan and make decisions regarding spine reconstruction surgery for patients with ASD.

RESUMEN

OBJECTIVE: Although the importance of spinopelvic sagittal balance and its implications for clinical outcomes of spinal fusion surgery have been described, to the authors' knowledge there have been no reports of the relationship between spinopelvic alignment and clinical outcomes for 2-level posterior lumbar interbody fusion (PLIF). The purpose of this study was to elucidate the relationship between clinical outcomes and spinopelvic sagittal parameters after 2-level PLIF for 2-level degenerative spondylolisthesis (DS). METHODS: This study was limited to patients who were treated with 2-level PLIF for 2-level DS at L3-4-5. Between 2005 and 2014, 33 patients who could be followed up for at least 2 years were included in this study. The average age at the time of surgery was 72 years, and the average follow-up period was 5.6 years. Based on clinical assessments, the Japanese Orthopaedic Association (JOA) score and recovery rate were evaluated. The patients were divided into 2 groups based on the recovery rate: the good outcome group (G group; n = 19), with recovery rate ≥ 50%, and the poor outcome group (P group; n = 14) with recovery rate < 50%. Spinopelvic parameters were measured using lateral standing radiographs of the whole spine as follows: sagittal vertical axis (SVA), thoracic kyphosis (TK), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), and segmental lordosis (SL) at L3-4-5. The clinical outcomes and radiological parameters were assessed preoperatively and at the final follow-up. Radiological parameters were compared between the 2 groups. RESULTS: The mean JOA score improved significantly in all patients from 10.8 points before surgery to 19.6 points at the latest follow-up (mean recovery rate 47.7%). For radiological outcomes, no difference was observed from preoperative assessment to final follow-up in any of the spinopelvic parameters except SVA. Although no significant difference between the 2 groups was detected in any of the spinopelvic parameters, there were significant differences in the change in SL and LL (ΔSL 3.7° vs -2.1° and ΔLL 1.2° vs -5.6° for the G and P groups, respectively). In addition, the number of patients in the G group was significantly larger for the patients with ΔSL-plus than those with ΔSL-minus (p = 0.008). CONCLUSIONS: The clinical outcomes of 2-level PLIF for 2-level DS limited at L3-4-5 appeared to be satisfactory. The results indicate that acquisition of increased SL in surgery might lead to better clinical outcomes.

RESUMEN

OBJECTIVE: L5-S1 stand-alone anterior lumbar interbody fusion (ALIF) is a reliable technique to treat symptomatic degenerative disc disease but remains controversial for treatment of isthmic spondylolisthesis. In the present study the authors aimed to identify risk factors of instrumentation failure and pseudarthrosis after stand-alone L5-S1 ALIF and to evaluate whether instrumentation failure influenced the rate of fusion. METHODS: The study included 64 patients (22 [34.4%] male and 42 [65.6%] female, mean age 46.4 years [range 21-65 years]) undergoing stand-alone L5-S1 ALIF using radiolucent anterior cages with Vertebridge plating fixation in each vertebral endplate. Clinical and radiographic data were reviewed, including age, sex, pelvic parameters, segmental sagittal angle (SSA), C7/sacro-femoral distance (SFD) ratio, C7 sagittal tilt, lumbar lordosis (LL), segmental LL, percentage of L5 slippage, L5-S1 disc angle, and posterior disc height ratio. Univariate and multivariate analyses were used to identify risk factors of instrumentation failure and pseudarthrosis. RESULTS: At a mean follow-up of 15.9 months (range 6.6-27.4 months), fusion had occurred in 57 patients (89.1%). Instrumentation failure was found in 12 patients (18.8%) and pseudarthrosis in 7 patients (10.9%). The following parameters influenced the occurrence of instrumentation failure: presence of isthmic spondylolisthesis (p < 0.001), spondylolisthesis grade (p < 0.001), use of an iliac crest bone autograft (p = 0.04), cage height (p = 0.03), pelvic incidence (PI) (p < 0.001), sacral slope (SS) (p < 0.001), SSA (p = 0.003), and LL (p < 0.001). Instrumentation failure was statistically linked to the occurrence of L5-S1 pseudarthrosis (p < 0.001). On multivariate analysis, no risk factors were found. CONCLUSIONS: L5-S1 isthmic spondylolisthesis and high PI seem to be risk factors for instrumentation failure in case of stand-alone L5-S1 ALIF, findings that support the necessity of adding percutaneous posterior pedicle screw instrumentation in these cases.

Asunto(s)

RESUMEN

OBJECTIVE: Proximal junctional kyphosis (PJK) is a structural complication of spinal fusion in 5%-61% of patients treated for adult spinal deformity. In nearly one-third of these cases, PJK is progressive and requires costly surgical revision. Previous studies have suggested that patient body habitus may predict risk for PJK. Here, the authors sought to investigate abdominal girth and paraspinal muscle size as risk factors for PJK. METHODS: All patients undergoing thoracolumbosacral fusion greater than 2 levels at a single institution over a 5-year period with ≥ 6 months of radiographic follow-up were considered for inclusion. PJK was defined as kyphosis ≥ 20° between the upper instrumented vertebra (UIV) and two supra-adjacent vertebrae. Operative and radiographic parameters were recorded, including pre- and postoperative sagittal vertical axis (SVA), sacral slope (SS), lumbar lordosis (LL), pelvic tilt, pelvic incidence (PI), and absolute value of the pelvic incidence-lumbar lordosis mismatch (|PI-LL|), as well as changes in LL, |PI-LL|, and SVA. The authors also considered relative abdominal girth and the size of the paraspinal muscles at the UIV. RESULTS: One hundred sixty-nine patients met inclusion criteria. On univariate analysis, PJK was associated with a larger preoperative SVA (p < 0.001) and |PI-LL| (p = 0.01), and smaller SS (p = 0.004) and LL (p = 0.001). PJK was also associated with more positive postoperative SVA (p = 0.01), ΔSVA (p = 0.01), Δ|PI-LL| (p < 0.001), and ΔLL (p < 0.001); longer construct length (p = 0.005); larger abdominal girth-to-muscle ratio (p = 0.007); and smaller paraspinal muscles at the UIV (p < 0.001). Higher postoperative SVA (OR 1.1 per cm), smaller paraspinal muscles at the UIV (OR 2.11), and more aggressive reduction in |PI-LL| (OR 1.03) were independent predictors of radiographic PJK on multivariate logistic regression. CONCLUSIONS: A more positive postoperative global sagittal alignment and smaller paraspinal musculature at the UIV most strongly predicted PJK following thoracolumbosacral fusion.

Asunto(s)

RESUMEN

OBJECTIVEWith the development of minimally invasive procedures, percutaneous pedicle screw systems have been used to attempt to correct spondylolisthesis. No previous studies have reported on reduction measures using long tab percutaneous pedicle screws for spondylolisthesis. Additional intraoperative correction has been proposed with the "swing" technique. This study was conducted to compare the efficacy of standard minimally invasive transforaminal interbody fusion (MIS-TLIF) with the efficacy of MIS-TLIF with the "swing" technique (MIS-TLIF and swing) in lumbar spondylolisthesis.METHODSThis was a matched-control study and included 30 consecutive patients who were followed up for 6 months after surgery. Of those patients, 15 were treated with operative reduction via MIS-TLIF with the "swing" technique, whereas the other 15 were treated with the standard MIS-TLIF procedure. The swing technique is a new reduction procedure for use with long tab percutaneous screws. In the swing technique, the entire system is swung back and forth several times after all constructs are placed. Only patients with Meyerding grade I or II lumbar spondylolisthesis were included in the study (18 with grade I and 12 with grade II). Perioperative and clinical outcomes, radiological parameters (Meyerding grade, percentage of slip, slip correction rate, segmental lordosis, and lumbar lordosis) were compared between groups at 6 months after surgery.RESULTSDemographic data did not differ significantly between the 2 groups. Postoperative clinical outcomes showed significant improvement in both groups. Postoperative radiological parameters showed that the degree of spondylolisthesis (swing: 4.7% vs standard: 8.9%) and reduction rate (swing: 77.3% vs standard: 57.1%) favored the swing group. The swing technique effectively decreased the degree of spondylolisthesis (swing: 24.1% to 4.7% vs standard: 21.8% to 8.9%). No complications related to the procedure were reported.CONCLUSIONSMIS-TLIF with the "swing" technique with long tab percutaneous pedicle screws is a safe and effective reduction method for monosegmental spondylolisthesis. This technique cannot only alleviate symptoms but also achieve nearly completely reduction of slippage.

Asunto(s)

RESUMEN

OBJECTIVE: Relocation of the apex is often found in patients with ankylosing spondylitis (AS)-associated thoracolumbar/lumbar kyphosis after corrective surgery. This study evaluates the influence of different postoperative apex locations on surgical and clinical outcomes of osteotomy for patients with AS and thoracolumbar kyphosis. METHODS: Sixty-two patients with a mean age of 34.6 ± 9.7 years (range 17-59 years) and a minimum of 2 years of follow-up, who underwent 1-level lumbar pedicle subtraction osteotomy for AS-related thoracolumbar kyphosis, were enrolled in the study, as well as 62 age-matched healthy individuals. Patients were divided into 2 groups according to the postoperative location of the apex (group 1, T8 or above; group 2, T9 or below). Demographic data, radiographic measurements (including 3 postoperative apex-related parameters), and clinical outcomes were compared between the 2 groups preoperatively, postoperatively, and at the last follow-up. Furthermore, a subgroup analysis was performed among patients with a postoperative apex located at T6-11 and postoperatively the entire AS cohort was compared with normal controls regarding the apex location of the thoracic spine. RESULTS: In the majority of the enrolled patients, the apex location changed from T12-L2 preoperatively to T6-9 postoperatively. The sagittal vertical axis (SVA) differed significantly both postoperatively (25.7 vs 59.0 mm, p = 0.001) and at the last follow-up (34.6 vs 59.9 mm, p = 0.003) between the 2 groups, and the patients in group 1 had significantly smaller horizontal distance between the C7-vertical line and the apex (DCA) than the patients in group 2 (67.5 vs 103.7 mm, p = 0.001). Subgroup analysis demonstrated similar results, showing that the patients with a postoperative apex located at T8 or above had an average SVA < 47 mm. Notably, a significant correlation was found between postoperative SVA and DCA (r = 0.642, p = 0.001). Patients who underwent an osteotomy at L3 had limited apex relocation but larger SVA correction than those at L1 or L2. However, no significant difference was found in health-related quality of life between the 2 groups. CONCLUSIONS: AS patients with an apex located at T8 or above after surgery tended to have better SVA correction (within 47 mm) than those who had a more caudally located apical vertebra. For ideal postoperative apex relocation, a higher (closer to or at the preoperative apex) level of osteotomy is more likely to obtain the surgical goal.

Asunto(s)

RESUMEN

The sacrum forms the distal end of the spine and communicates with the pelvis. Fractures involving the sacrum are complex and may disrupt this vital communication. Neglecting these fractures may result in malunion, which often causes significant alteration in the pelvic parameters and sagittal balance. Management of ensuing deformities is complex and poorly described. The authors present a case of sacral malunion with sagittal imbalance treated with a low lumbar osteotomy.

Asunto(s)

RESUMEN

OBJECTIVEThe importance of global sagittal alignment is well known. Patients with lumbar spinal stenosis (LSS) generally tend to bend forward to relieve their neurological symptoms, i.e., they have a positive sagittal vertical axis (SVA). We hypothesized that the positive SVA associated with LSS is symptom related and should improve after surgery. However, little is known about the changes in sagittal alignment in LSS patients after decompression surgery. In this study the authors aimed to evaluate midterm radiographical changes in sagittal spinopelvic alignment after decompression surgery for LSS and to determine the factors influencing the improvement in sagittal spinopelvic alignment.METHODSThe authors retrospectively reviewed 89 patients who underwent lumbar decompression without fusion between January 2014 and September 2015 with a minimum follow-up of 2 years. Standing whole-spine radiographs at the preoperative stage and at the final follow-up were examined. We analyzed SVA, lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), thoracolumbar kyphosis (TLK), and thoracic kyphosis (TK).RESULTSLL and TK were significantly increased postoperatively. SVA and PI minus LL (PI-LL) were significantly decreased. There were no significant differences between the preoperative and postoperative PT, PI, SS, or TLK. Twenty-nine patients had preoperative sagittal malalignment with SVA > 50 mm. Thirteen of the 29 patients improved to SVA < 50 mm after decompression surgery. Lower ASA grade, preoperative higher LL, and lower PI-LL were related to patient improvement. A receiver operating characteristic curve for the preoperative PI-LL had an area under the curve value of 0.821, indicating moderate accuracy (p = 0.003). A cutoff value for preoperative PI-LL of 19.2° showed a sensitivity of 93.5% and a specificity of 71.4%.CONCLUSIONSLumbar decompression can lead to a reactive improvement in the lumbar and global sagittal alignment. However, some of the sagittal malalignment in LSS was irreversible. Preoperative PI-LL was a useful predictor to distinguish reversible from irreversible sagittal malalignment.

RESUMEN

OBJECTIVEThe purpose of this study was to determine the relationship between vertebral bodies, psoas major morphology, and the course of lumbar nerve tracts using diffusion tensor imaging (DTI) before lateral interbody fusion (LIF) to treat spinal deformities.METHODSDTI findings in a group of 12 patients (all women, mean age 74.3 years) with degenerative lumbar scoliosis (DLS) were compared with those obtained in a matched control group of 10 patients (all women, mean age 69.8 years) with low-back pain but without scoliosis. A T2-weighted sagittal view was fused to tractography from L3 to L5 and separated into 6 zones (zone A, zones 1-4, and zone P) comprising equal quarters of the anteroposterior diameters, and anterior and posterior to the vertebral body, to determine the distribution of nerves at various intervertebral levels (L3-4, L4-5, and L5-S1). To determine psoas morphology, the authors examined images for a rising psoas sign at the level of L4-5, and the ratio of the anteroposterior diameter (AP) to the lateral diameter (lat), or AP/lat ratio, was calculated. They assessed the relationship between apical vertebrae, psoas major morphology, and the course of nerve tracts.RESULTSAlthough only 30% of patients in the control group showed a rising psoas sign, it was present in 100% of those in the DLS group. The psoas major was significantly extended on the concave side (AP/lat ratio: 2.1 concave side, 1.2 convex side). In 75% of patients in the DLS group, the apex of the curve was at L2 or higher (upper apex) and the psoas major was extended on the concave side. In the remaining 25%, the apex was at L3 or lower (lower apex) and the psoas major was extended on the convex side. Significant anterior shifts of lumbar nerves compared with controls were noted at each intervertebral level in patients with DLS. Nerves on the extended side of the psoas major were significantly shifted anteriorly. Nerve pathways on the convex side of the scoliotic curve were shifted posteriorly.CONCLUSIONSA significant anterior shift of lumbar nerves was noted at all intervertebral levels in patients with DLS in comparison with findings in controls. On the convex side, the nerves showed a posterior shift. In LIF, a convex approach is relatively safer than an approach from the concave side. Lumbar nerve course tracking with DTI is useful for assessing patients with DLS before LIF.

RESUMEN

OBJECTIVEThe goal of this study was to investigate the impact of thoracic and lumbar alignment on cervical alignment in patients with adolescent idiopathic scoliosis (AIS).METHODSEighty-one patients with AIS who had a Cobb angle > 40° and full-length spine radiographs were included. Radiographs were analyzed using dedicated software to measure pelvic parameters (sacral slope [SS], pelvic incidence [PI], pelvic tilt [PT]); regional parameters (C1 slope, C0-C2 angle, chin-brow vertical angle [CBVA], slope of line of sight [SLS], McRae slope, McGregor slope [MGS], C2-7 [cervical lordosis; CL], C2-7 sagittal vertical axis [SVA], C2-T3, C2-T3 SVA, C2-T1 Harrison measurement [C2-T1 Ha], T1 slope, thoracic kyphosis [TK], lumbar lordosis [LL], and PI-LL mismatch); and global parameters (SVA). Patients were stratified by their lumbar alignment into hyperlordotic (LL > 59.7°) and normolordotic (LL 39.3° to 59.7°) groups and also, based on their thoracic alignment, into hypokyphotic (TK < -33.1°) and normokyphotic (TK -33.1° to -54.9°) groups. Finally, they were grouped based on their global alignment into either an anterior-aligned group or a posterior-aligned group.RESULTSThe lumbar hyperlordotic group, in comparison to the normolordotic group, had a significantly larger LL, SS, PI (all p < 0.001), and TK (p = 0.014) and a significantly smaller PI-LL mismatch (p = 0.001). Lumbar lordosis had no influence on local cervical parameters.The thoracic hypokyphotic group had a significantly larger PI-LL mismatch (p < 0.002) and smaller T1 slope (p < 0.001), and was significantly more posteriorly aligned than the normokyphotic group (-15.02 ± 8.04 vs 13.54 ± 6.17 [mean ± SEM], p = 0.006). The patients with hypokyphotic AIS had a kyphotic cervical spine (cervical kyphosis [CK]) (p < 0.001). Furthermore, a posterior-aligned cervical spine in terms of C2-7 SVA (p < 0.006) and C2-T3 SVA (p < 0.001) was observed in the thoracic hypokyphotic group.Comparing patients in terms of global alignment, the posterior-aligned group had a significantly smaller T1 slope (p < 0.001), without any difference in terms of pelvic, lumbar, and thoracic parameters when compared to the anterior-aligned group. The posterior-aligned group also had a CK (-9.20 ± 1.91 vs 5.21 ± 2.95 [mean ± SEM], p < 0.001) and a more posterior-aligned cervical spine, as measured by C2-7 SVA (p = 0.003) and C2-T3 SVA (p < 0.001).CONCLUSIONSAlignment of the cervical spine is closely related to thoracic curvature and global alignment. In patients with AIS, a hypokyphotic thoracic alignment or posterior global alignment was associated with a global cervical kyphosis. Interestingly, upper cervical and cranial parameters were not statistically different in all investigated groups, meaning that the upper cervical spine was not recruited for compensation in order to maintain a horizontal gaze.

Asunto(s)

RESUMEN

OBJECTIVE: Spinopelvic parameters, such as the pelvic incidence (PI) angle, sacral slope angle, and pelvic tilt angle, are important anatomical indices for determining the sagittal curvature of the spine and the individual variability of the lumbar lordosis (LL) curve. The aim of this study was to investigate the influence of spinopelvic parameters and LL on adjacent-segment degeneration (ASD) after short lumbar and lumbosacral fusion for single-level degenerative spondylolisthesis. METHODS: The authors retrospectively reviewed the records of all short lumbar and lumbosacral fusion surgeries performed between August 2003 and July 2010 for single-level degenerative spondylolisthesis in their orthopedic department. RESULTS: A total of 30 patients (21 women and 9 men, mean age 64 years) with ASD after lower lumbar or lumbosacral fusion surgery comprised the study group. Thirty matched patients (21 women and 9 men, mean age 63 years) without ASD comprised the control group, according to the following matching criteria: same diagnosis on admission, similar pathologic level (≤ 1 level difference), similar sex, and age. The average follow-up was 6.8 years (range 5-8 years). The spinopelvic parameters had no significant influence on ASD after short spinal fusion. CONCLUSIONS: Neither the spinopelvic parameters nor a mismatch of PI and LL were significant factors responsible for ASD after short spinal fusion due to single-level degenerative spondylolisthesis.

Asunto(s)