The effect of prophylactic vertebroplasty on the incidence of proximal junctional kyphosis and proximal junctional failure following posterior spinal fusion in adult spinal deformity: a 5-year follow-up study

Background Context

The incidence of proximal junctional kyphosis (PJK) ranges from 5% to 46% following adult spinal deformity surgery. Approximately 66% to 76% of PJK occurs within 3 months of surgery. A subset of these patients, reportedly 26% to 47%, develop proximal junctional failure (PJF) within 6 months postoperatively. To date, there are no studies evaluating the impact of prophylactic vertebroplasty on PJK and PJF incidence at long-term follow-up.

Risk factor analysis of proximal junctional kyphosis after posterior fusion in patients with idiopathic scoliosis

Study design

A retrospective analysis of 150 adolescents who underwent spinal fusion for idiopathic scoliosis.

Objective

To analyse the incidence of the postoperative proximal junctional kyphosis after posterior fusion to the upper thoracic vertebra in adolescents with idiopathic scoliosis and to explore its risk factors.

Summary of background data

The reported incidence of the proximal junctional kyphosis after the posterior fusion in patients with idiopathic scoliosis varies depending on surgical methods and strategies adopted by the institution.

Methods

The changes in the Cobb angle of the proximal junctional kyphosis on the lateral spine X-ray were measured and the presence of PJK was recorded. The risk factors were screened using statistical analysis.

Results

PJK occurred in 35 out of 123 patients with an overall incidence of 28%. Among them, 28 patients (80%) experienced PJK within 1.5 years after surgery. The PJK-inducing factors included greater than 10° intraoperative decrease in thoracic kyphosis, thoracoplasty, the use of a pedicle screw at the top vertebra, autogenous bone graft and fusion to the lower lumbar vertebra (below L2).

Conclusions

There is a high incidence of postoperative proximal junctional kyphosis after posterior fusion to the upper thoracic vertebra within 1.5 years after surgery in adolescents with idiopathic scoliosis. In order to reduce its incidence, the risk factors for PJK should be carefully evaluated before surgery.     

Prophylactic vertebral cement augmentation at the uppermost instrumented vertebra and rostral adjacent vertebra for the prevention of proximal junctional kyphosis and failure following long-segment fusion for adult spinal deformity

Background Context

Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) are common problems after long-segment (>5 levels) thoracolumbar instrumented fusions in the treatment of adult spinal deformity (ASD). No specific surgical strategy has definitively been shown to lower the risk of PJK as the result of a multifactorial etiology.

Combined spinal arthrodesis with instrumentation for the management of progressive thoracolumbar kyphosis in children with mucopolysaccharidosis

Purpose

To evaluate the outcome and complications of a novel technique for the treatment of progressive thoracolumbar kyphosis in children with mucopolysaccharidosis (MPS).

Methods

The medical records and spinal imaging of four consecutive paediatric patients who underwent a single stage anteroposterior spinal fusion with segmental pedicle screw instrumentation were reviewed.

Results

Patients underwent spinal deformity correction at the mean age of 3 years (2.4–3.7) with mean clinical follow-up of 3.2 years (2.1–4.5) and mean postoperative radiographic follow-up was 2.4 years (0.8–3). Preoperative kyphosis was corrected from a mean angle of 65º (63º–70º) to 6.5º (–12º–13º). Vertebral subluxation at the apex of the deformity was corrected from an average 64 % (56–83 %) to 12 % (0–24 %). Spinal cord monitoring with somatosensory evoked potentials (SSEP) was successfully obtained and stable throughout surgery. No instrumentation failure, loss of correction or junctional problems occurred at final follow-up.

Conclusions

Anterior and posterior spinal arthrodesis with segmental pedicle screw instrumentation is a safety and reliable technique for the treatment of severe thoracolumbar kyphosis in children with MPS. This technique achieves excellent correction of the deformity with adequate decompression of the spinal canal. The fusion is limited to the thoracolumbar junction and interferes minimally with the longitudinal growth of the thorax. No neurological complications or intraoperative spinal cord monitoring events occurred. No loss of correction or junctional kyphosis was observed.     

Osteotomies in proximal junctional kyphosis in the cervicothoracic area

Introduction

Proximal junctional kyphosis (PJK) of the cervicothoracic spine is a deformity that can affect patients who have undergone long thoracolumbar instrumented fusion. Preoperative hyperkyphosis of the thoracic spine and changes of more than 30° in lumbar lordosis are independent risk factors for the onset of PJK.

Methods

When PJK occurs in the cervicothoracic spine, extension of the fusion with eventual application of osteotomy techniques is frequently necessary to treat symptomatic patients or in case a neurological deficit occurs. Ponte osteotomy and pedicle subtraction osteotomy (PSO) are the two most used techniques to restore a good cervicothoracic alignment, although they are still demanding procedures even for expert surgeons. In junctional fractures, a vertebral column resection can be performed to support the anterior column. Ponte osteotomy ideally restores 10° at each treated level, while PSO allows a segmental correction up to 30°–35°. Adequate preoperative planning is fundamental for outlining the correct surgery and choosing the appropriate osteotomy.

Conclusions

The aim of corrective surgery is to restore the cervicothoracic alignment, obtaining an adequate postoperative sagittal balance and decreasing the risk of further complications and new revision surgeries.

     

Sagittal balance and idiopathic scoliosis: does final sagittal alignment influence outcomes,degeneration rate or failure rate?

Introduction

In the last decade, spine surgeons have been impacted by the “sagittal plane analysis revolution”. Significant correlations have been found in adult spinal deformity (ASD) between sagittal lumbo-pelvic parameters and functional outcomes, but most of them do not apply in adolescent idiopathic scoliosis (AIS). Meanwhile, instrumentation and reduction strategies have considerably evolved. This paper aims to describe the preoperative sagittal alignment in AIS, and to report literature evidence regarding the influence of postoperative sagittal balance on complication rates, low back pain incidence and disc degeneration.

Methods

A bibliographic search in Medline and Google database from 1984 to May 2017 was performed. The keywords included ‘adolescent idiopathic scoliosis’, ‘adult scoliosis’, ‘sagittal alignment’, ‘proximal junctional kyphosis’, ‘distal junctional kyphosis’, ‘outcomes’, ‘low back pain’ and ‘complication’, used individually or in combination.

Results

Algorithms of sagittal balance analysis and treatment decision have been reported in ASD, but the clinical situation is very different in children. Sagittal alignment greatly varies in AIS among the various Lenke types. Most patients are clinically balanced before surgery, but the spinal harmony is altered, with overgrowth of the anterior column and global sagittal flattening (undersestimated in 2D). The exact role of pelvic incidence and whether or not patients also use pelvic compensation to maintain balance still require further clarification. The incidence of radiological junctional failures remains highly variable, depending on definitions, cohort size and follow-up. Preoperative hyperkyphosis seems to be a consistent and relevant risk factor. Current literature does not support the recent trend to save motion segments (selective fusion), and no significant association was found between the distal level of fusion and the incidence of low back pain. Postoperative sagittal alignment seems to be more important than LIV selection to avoid disc degeneration at mid-term follow-up.

Conclusion

It is clear now that sagittal alignment plays a major role in clinical outcomes and should not be neglected in AIS. Seven key guidelines that should be considered for each patient before surgery are reported (Table 2). Personalized planning using 3D technology is gaining popularity and might help in the future reducing complications.

     

Rod stiffness as a risk factor of proximal junctional kyphosis after adult spinal deformity surgery: comparative study between cobalt chrome multiple-rod constructs and titanium alloy two-rod constructs

Background Context

Little is known about the effect of rod stiffness as a risk factor of proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery.

Teriparatide improves volumetric bone mineral density and fine bone structure in the UIV+1 vertebra,and reduces bone failure type PJK after surgery for adult spinal deformity

Summary

We conducted a prospective comparative study of the effect of teriparatide therapy for preventing vertebral-failure-type PJK after reconstructive surgery for adult spinal deformity. Prophylactic teriparatide improved the volumetric bone mineral density and fine bone structure of the vertebra above the upper-instrumented vertebra and reduced the incidence of vertebral-failure-type PJK.

Introduction

Proximal junctional kyphosis (PJK) is a complication after corrective surgery for spinal deformity. This study sought to determine whether teriparatide (TP) is an effective prophylactic against PJK type 2 (vertebral fracture) in surgically treated patients with adult spinal deformity (ASD).

Methods

Forty-three patients who started TP therapy immediately after surgery and 33 patients who did not receive TP were enrolled in this prospective case series. These patients were female, over 50, surgically treated for ASD, and followed for at least 2 years. Preoperative and postoperative standing whole-spine X-rays and dual-energy X-ray absorptiometry scans, and multidetector CT images obtained before and 6 months after surgery were used to analyze the bone strength in the vertebra above the upper-instrumented vertebra (UIV+1).

Results

Mean age was 67.9 years. After 6 months of treatment, mean hip-bone mineral density (BMD) increased from 0.721 to 0.771 g/cm² in the TP group and decreased from 0.759 to 0.729 g/cm² in the control group. This percent BMD change between groups was significant (p?<?0.05). The volumetric BMD (326 to 366 mg/cm³) and bone mineral content (BMC) (553 to 622 mg) at UIV+1 were also significantly increased in TP group. The bone volume/tissue volume ratio increased from 46 to 54 % in the TP group, and the trabecular bone thickness and number increased by 14 and 5 %, respectively. At the 2-year follow-up, the PJK type 2 incidence was significantly lower in the TP group (4.6 %) than in the control group (15.2 %; p?=?.02).

Conclusions

Prophylactic TP treatment improved the volumetric BMD and fine bone structure at UIV+1 and reduced the PJK-type 2 incidence.

     

Poor visualization limits diagnosis of proximal junctional kyphosis in adolescent idiopathic scoliosis

Background Context

Multiple methods are used to measure proximal junctional angle (PJA) and diagnose proximal junctional kyphosis (PJK) after fusion for adolescent idiopathic scoliosis (AIS); however, there is no gold standard. Previous studies using the three most common measurement methods, upper-instrumented vertebra (UIV)+1, UIV+2, and UIV to T2, have minimized the difficulty in obtaining these measurements, and often exclude patients for which measurements cannot be recorded.

Incidence and risk factors for proximal junctional kyphosis: a meta-analysis

Purpose

To analyse the incidence and risk factors associated with proximal junctional kyphosis (PJK) following spinal fusion, we collect relative statistics from the articles on PJK and perform a meta-analysis.

Methods

An extensive search of literature was performed in PubMed, Embase, and The Cochrane Library (up to April 2015). The following risk factors were extracted: age at surgery, gender, combined anterior-posterior surgery, use of pedicle screw at top of construct, hybrid instrumentation, thoracoplasty, fusion to sacrum (S1), preoperative thoracic kyphosis angle (T5–T12) >40°, bone mineral density (BMD) and preoperative to postoperative sagittal vertical axis (SVA difference) >5 cm. Data analysis was conducted with RevMan 5.3 and STATA 12.0.

Results

A total of 14 unique studies including 2215 patients were included in the final analyses. The pooled analysis showed that there were significant difference in age at surgery >55 years old (OR 2.19, 95 % CI 1.36–3.53, p = 0.001), fusion to S1 (OR 2.12, 95 % CI 1.57–2.87, p < 0.001), T5–T12 >40° (OR 2.68, 95 % CI 1.73–4.13, p < 0.001), low BMD (OR 2.37, 95 % CI 1.45–3.87, p < 0.001) and SVA difference >5 cm (OR 2.53, 95 % CI 1.24–5.18, p = 0.01). However, there was no significant difference in gender (OR 0.98, 95 % CI 0.74–1.30, p = 0.87), combined anterior-posterior surgery (OR 1.55, 95 % CI 0.98–2.46, p = 0.06), use of pedicle screw at top of construct (OR 1.55, 95 % CI 0.67–3.59, p = 0.30), hybrid instrumentation (OR 1.31, 95 % CI 0.92–1.87, p = 0.13) and thoracoplasty (OR 1.55, 95 % CI 0.89–2.72, p = 0.13). The incidence of PJK following spinal fusion was 30 % (ranged from 17 to 62 %) based on the 14 studies.

Conclusions

The results of our meta-analysis suggest that age at surgery >55 years, fusion to S1, T5–T12 >40°, low BMD and SVA difference >5 cm are risk factors for PJK. However, gender, combined anterior–posterior surgery, use of pedicle screw at top of construct, hybrid instrumentation and thoracoplasty are not associated with PJK.

     

Revision surgery in proximal junctional kyphosis

Proximal junctional kyphosis (PJK) is a relatively common complication following spinal deformity surgery that may require reoperation. Although isolating the incidence is highly variable, in part due to the inconsistency in how PJK is defined, previous studies have reported the incidence to be as high as 39% with revision surgery performed in up to 47% of those with PJK. Despite the discordance in reported incidence, PJK remains a constant challenge that can result in undesirable outcomes following adult spine deformity surgery. A comprehensive literature review using Medline and PubMed was performed. Keywords included “proximal junctional kyphosis,” “postoperative complications,” “spine deformity surgery,” “instrumentation failure,” and “proximal junctional failure” used separately or in conjunction. While the characterization of PJK is variable, a postoperative proximal junction sagittal Cobb angle at least 10°, 15°, or 20° greater than the measurement preoperatively, it is a consistent radiographic phenomenon that is well defined in the literature. While particular studies in the current literature may ascertain certain variables as significantly associated with the development of proximal junctional kyphosis where other studies do not, it is imperative to note that they are not all one in the same. Different patient populations, outcome variables assessed, statistical methodology, surgeon/surgical characteristics, etc. often make these analyses not completely comparable nor generalizable. The goal of adult spine deformity surgery is to optimize patient outcomes and mitigate postoperative complications whenever possible. Due to the multifactorial nature of this complication, further research is required to enhance our understanding and eradicate the pathology. Patient optimization is the principal guideline in not only PJK prevention, but overall postoperative complication prevention. These slides can be retrieved under Electronic Supplementary Material.     

Instrumentation techniques to prevent proximal junctional kyphosis and proximal junctional failure in adult spinal deformity correction—a systematic review of biomechanical studies

Background contextCorrection of adult spinal deformity (ASD) by long segment instrumented spinal fusion is an increasingly common surgical intervention. However, it is associated with high rates of complications and revision surgery, especially in the elderly patient population. The high construct stiffness of instrumented thoracolumbar spinal fusion has been postulated to lead to a higher incidence of proximal junctional kyphosis (PJK) and failure (PJF). Several cadaveric biomechanical studies have reported on surgical techniques to reduce the incidence of PJF/PJK. As yet, no overview has been made of these biomechanical studies.PurposeTo summarize the evidence of all biomechanical studies that have assessed techniques to reduce PJK/PJF following long segment instrumented spinal fusion in the ASD patient population.Study designA systematic review.MethodsEMBASE and MEDLINE databases were searched for human and animal cadaveric biomechanical studies investigating the effect of various surgical techniques to reduce PJK/PJF following long segment instrumented thoracolumbar spinal fusion in the adult patient population. Studied techniques, biomechanical test methods, range of motion (ROM), intervertebral disc pressure (IDP) and other relevant outcome parameters were documented.ResultsTwelve studies met the inclusion criteria. Four of these studies included non-human cadaveric material. One study investigated the prophylactic application of cement augmentation (vertebroplasty), whereas the remaining studies investigated semi-rigid junctional fixation techniques to achieve a gradual transition zone of forces at the proximal end of a fusion construct, so-called topping-off. An increased gradual transition zone in terms of ROM compared to pedicle screw constructs was demonstrated for sublaminar tethers, sublaminar tape, pretensioned suture loops, transverse hooks and laminar hooks. Furthermore, reduced IDP was found after the application of sublaminar tethers, suture loops, sublaminar tapes and laminar hooks. Finally, two-level prophylactic vertebroplasty resulted in a lower incidence of vertebral compression fractures in a flexion-compression experiment.ConclusionsA variety of techniques, involving either posterior semi-rigid junctional fixation or the reinforcement of vertebral bodies, has been biomechanically assessed. However, the low number of studies and variation in study protocols hampers direct comparison of different techniques. Furthermore, determination of what constitutes an optimal gradual transition zone and its translation to clinical practice, would aid comparison and further development of different semi-rigid junctional fixation techniques. Even though biomechanics are extremely important in the development of PJK/PJF, patient-specific factors should always be taken into account on a case-by-case basis when considering to apply a semi-rigid junctional fixation technique.     

Pre-existing vertebral fracture is a risk factor for postoperative proximal junctional fracture after adult spinal deformity surgery: A propensity score-matched analysis

BackgroundCorrective surgery for adult spinal deformity has recently been increasingly performed because of aging populations and advances in minimally invasive surgery. Low bone mineral density is a major contributor to proximal junctional kyphosis after spinal long fusion. Assessment for low bone mineral density ideally involves both dual energy X-ray absorptiometry and identification of pre-existing vertebral fractures, the latter, requiring only standard equipment, being performed more frequently. We therefore aimed to examine the impact of pre-existing vertebral fractures on the incidence of type 2 proximal junctional kyphosis, including proximal junctional fracture and failure, after corrective surgery for adult spinal deformity.MethodsWe performed a retrospective, single institution study of 106 women aged over 50 years who had undergone corrective long spinal fusion for severely symptomatic spinal deformity from 2014 to 2017. We allocated them to three groups (with and without pre-existing vertebral fractures and with severe [Grades 2–3 according to Genant et al.‘s classification] preexisting vertebral fractures) and used propensity score matching to minimize bias. The primary outcome was postoperative proximal junctional fracture and the secondary outcome proximal junctional kyphosis/failure.ResultsThe primary and secondary endpoints were achieved significantly more often in the 28 patients with than in the 78 without preexisting vertebral fractures (total 41). The former group was also significantly older and had greater pelvic tilt and fewer fused segments than those without vertebral fractures. After propensity score matching, the incidences of the endpoints did not differ with pre-existing vertebral fracture status; however, patients with severe vertebral fractures more frequently had proximal junctional fractures postoperatively. Postoperative improvements in health-related quality of life scores did not differ with pre-existing vertebral fracture status.ConclusionsSevere pre-existing vertebral fractures are a risk factor for proximal junctional fracture after correction of adult spinal deformity.     

Congenital kypho-scoliosis: a case of thoracic insufficiency syndrome and the limitations of treatment

Introduction

Congenital spinal vertebral anomalies may present with deformity resulting in congenital scoliosis and kyphosis. This leads to abnormal spinal growth. The latter when combined with associated rib fusions may impair normal thoracic cage development and resultant pulmonary hypoplasia. Most congenital scoliosis can be detected in utero by ultrasound scan or recognized in the neonatal period, but a few spinal defects can remain undetected.

Materials and Methods

In this Grand Round, we present the case of a 7-year-old girl with a severe scoliosis and thoracic insufficiency syndrome (TIS). 3D CT reconstruction imaging demonstrated a mixed picture of fusion and segmentation abnormalities. A marked kyphoscoliosis was demonstrated at the thoraco-lumbar junction. Via a left thoracotomy, anterior excision of intervertebral discs was performed together with, interbody fusion, and in situ stabilisation of the kyphosis with double allograft (femur) strut grafts.

Conclusions

This article highlights the features of congenital kypho-scoliosis and TIS. The difficulties of treating kyphosis when combined with TIS are discussed together with the limitations of current surgical techniques.     

Proximal junctional kyphosis in adult scoliosis: comparison of four radiological predictor models

Objective

The objective of this retrospective study is to identify the best immediate postoperative radiological predictors for the occurrence of proximal junctional kyphosis (PJK). Four proposed methods will be explored.

Methods

A homogeneous database of adult scoliosis from multiple centers was used. Patients with whole spine X-rays at the required follow-up (FU) periods were included. Spinal and pelvic parameters were measured and calculated to compare four predictive methods: Method 1: assessment of the global sagittal alignment (GSA); Method 2: restoration of the theoretical values of lumbar lordosis (LL) and thoracic kyphosis (TK) according to pelvic incidence (PI); Method 3: evaluation of TK + LL, and Method 4: restoration of the apex of sagittal LL to its theoretical values according to various spine shapes in Roussouly Classification. PJK occurrence was assessed at the last FU radiograph.

Results

250 patients were included; mean age was 56.67 years and mean FU was 2.5 years. PJK occurred in 25.6% of cases. PJK occurred in 19.9% in patients with a GSA <45° and in 29.9% where GSA >45° (p = 0.04, OR = 1.71). Restoring the sagittal apex of the LL to its theoretical values according to PI deceased PJK to 13.5% compared to 38.9% in the other cases (p = 0.01, OR = 4.6). The two other described methods (2 and 3) were not significant predictors.

Discussion

The comparison between the four predictive methods showed that a GSA >45° and restoration of sagittal apex of lordosis according to PI, were the most predictive methods for PJK in ASD. The latter had a higher predictive value. Our findings could prove useful in effective preoperative planning in ASD surgery to reduce PJK rates.

Level of evidence

Level IV.

     

Proximal junctional fracture and kyphosis after long spinopelvic corrective fixation for adult spinal deformity

BackgroundProximal junctional fractures (PJFx) are the main cause for proximal junctional kyphosis (PJK), a complication of adult spinal deformity surgery. This study investigated risk factors for PJFx when performing long spinopelvic corrective fixation with lateral interbody fusion from T9 to ilium.MethodsThis was a retrospective study of 43 patients with a minimum follow-up of 2 years. Radiographic measurements including thoracic kyphosis (TK), sagittal vertical axis (SVA), T1 pelvic angle (TPA), proximal junctional angle (PJA), lumbar lordosis (LL), lower LL, and pelvic tilt were measured preoperatively, one-month postoperatively, and at final follow up. TK and LL were also measured in a fulcrum backward-bending position preoperatively.ResultsAt final follow-up, PJK was found in 30/43 patients (69.8%); 20.9% of the cases had PJFx (9 patients). TPA (preoperative, and one-month postoperative) was significantly higher in the PJFx group than in the other groups. The differences in TPA, TK, and PJA between preoperative and one-month postoperative measurements in the PJFx group were significantly higher than those in the other groups. At final follow up, SVA was significantly higher in the PJFx group than in the “PJK without PJFx” group. TPA and TK were significantly higher in the PJFx group than in the other groups. PJA was significantly different between all groups.ConclusionPreoperative large TPA was the only risk factor for PJFx. Preoperative flexibility of the thoracolumbar spine and overcorrection of sagittal deformity were not related to PJFx or PJK.     

Combined Anterior-Posterior Surgery is the Most Important Risk Factor for Developing Proximal Junctional Kyphosis in Idiopathic Scoliosis

Background  

Several studies have identified risk factors for proximal junctional kyphosis (PJK) after instrumentation for scoliosis, but the relative risks are unclear.     

Proximal junctional kyphosis following correction surgery in the Lenke 5 adolescent idiopathic scoliosis patient

Background

To investigate the risk factors of proximal junctional kyphosis (PJK) in Lenke 5 AIS patients after all-pedicle instrumentation and correction, and to compare the difference of radiographic and clinical outcome between PJK and Non-PJK populations.

The results of closing wedge osteotomy with posterior instrumented fusion for the surgical treatment of congenital kyphosis

Purpose

There exist not much data regarding the surgical treatment of pure congenital kyphosis (CK) in the literature. The purpose of this study was to evaluate the results of closing wedge osteotomy with posterior instrumented fusion in patients with congenital kyphotic deformity.

Methods

We retrospectively evaluated the radiographical results of 10 patients who were subject to closing wedge vertebral osteotomy and posterior instrumented fusion due to CK. The mean age of the patients at surgery was 12.6 ± 3.72 years (range 8–18 years). Radiographical measurements including local kyphosis, correction loss, global kyphosis and sagittal balance values were noted for the preoperative, postoperative and final follow up periods, respectively. The data obtained from those periods underwent statistical analysis.

Results

Average follow-up period was 51.8 ± 29.32 months (range 26–96 months). The mean local kyphosis angle was 67.7° ± 15.64° (range 42°–88°) prior to the surgery, 31.5° ± 17.12 (range 14°–73°) following the surgery and 31.9° ± 15.98° (range 14°–71°) during the follow up-period, respectively (p < 0.05). A correction rate of 53.5 % was reported at the final follow up. Average sagittal balance was measured as 33.1 ± 24.48 mm (range 2–77 mm) prior to the surgery, 20.8 ± 15.46 mm (range 5–46 mm) following the surgery (p < 0.05) and 14.1 ± 9.2 mm (range 0–30 mm) during follow-up period (p > 0.05). Complications consisted of a rod fracture due to pseudoarthrosis, an implant failure with loosening of screws and a proximal junctional kyphosis. No neurological deficit or deep infection were encountered in any of the patients in the study group.

Conclusion

Closing wedge osteotomy with posterior instrumented fusion is an efficient method of surgical treatment in terms of sagittal balance restoration and deformity correction in patients with congenital kyphosis.     

Selection of proximal fusion level for adult degenerative lumbar scoliosis

Introduction

There is controversy regarding the appropriate proximal fusion level for adult degenerative scoliosis. Ideally, the horizontal vertebra is chosen for the upper instrumented vertebra to create a balanced spine. Fusion to T10 is recommended to prevent junctional problems at the proximal adjacent segment. The purpose of this retrospective study was to determine the optimal proximal fusion level for adult degenerative lumbar scoliosis.

Materials and Methods

Fifty-one patients with adult degenerative lumbar scoliosis (mean age 64.6 years) who underwent posterior instrumentation were analyzed after a minimum 2-year follow-up. The average number of levels fused was 5.9 segments (range 3–9) with distal fusion at L5 in 30 patients and S1 in 21 patients. The upper instrumented vertebra (UIV) ranged from T9 to L2. According to the relationship between UIV, horizontal vertebra (HV) and upper end vertebra (UEV), the patients were divided into three groups in the coronal plane: Group HV (UIV = HV or above); Group HV–UEV (UIV = between HV and UEV); and Group UEV (UIV = UEV or below). In the sagittal plane; the patients were divided into Group T9–10 (UIV = T9–10), Group T11–12 and Group L1–2.

Results

Proximal adjacent segment disease (ASD) was identified in 13 (25 %) out of 51 patients, including junctional kyphosis (n = 5), compression fractures (n = 4), progression of disc wedging (n = 2) and spinal stenosis (n = 2). Group UEV had more ASD (9 of 16 patients) compared to Group HV (2 of 21 patients) and Group HV–UEV (2 of 14 patients). It appeared that neutral vertebra could be a criterion for the selection of UIV in the coronal plane. Among the groups divided in the sagittal plane, proximal ASD was found in 47 % of 19 patients in Group L1–2, which was notably higher than 9 % in Group T9–10 and 20 % in Group T11–12.

Conclusions

Proximal adjacent segment disease developed more commonly when the proximal fusion stopped at the UEV or below in adult degenerative lumbar scoliosis. UIV must be above UEV in the coronal plane. Fusion to T11 or T12 was acceptable when UIV was above UEV, since there was no significant difference in the rate of proximal adjacent segment between fusion to T10 and fusion to T11 or T12.