Relationship between thoracic hypokyphosis, lumbar lordosis and sagittal pelvic parameters in adolescent idiopathic scoliosis

Purpose

Sagittal spine and pelvic alignment of adolescent idiopathic scoliosis (AIS) is poorly described in the literature. It generally reports the sagittal alignment with regard to the type of curve and never correlated to the thoracic kyphosis. The objective of this study is to investigate the relationship between thoracic kyphosis, lumbar lordosis and sagittal pelvic parameters in thoracic AIS.

Methods

Spinal and pelvic sagittal parameters were evaluated on lateral radiographs of 86 patients with thoracic AIS; patients were separated into hypokyphosis group (n = 42) and normokyphosis group (n = 44). Results were statistically analyzed. The lumbar lordosis was lower in the hypokyphosis group, due to the low proximal lordosis. The thoracic kyphosis was not correlated with any pelvic parameters but with the proximal lordosis. The pelvic incidence was correlated with sacral slope, pelvic tilt, lumbar lordosis and highly correlated with distal lumbar lordosis in the two groups. There was a significant linear regression between thoracic kyphosis and proximal lordosis and between pelvic incidence and distal lordosis.

Conclusions

We can consider that the proximal part of the lordosis depends on the thoracic kyphosis and the distal part depends on the pelvic incidence. The hypokyphosis in AIS is independent of the pelvic parameters and could be described as a structural parameter, characteristic of the scoliotic deformity.     

Reversing the concept: correction of adolescent idiopathic scoliosis using the convex rod de-rotation maneuver

Purpose

To show the radiological results of adolescent idiopathic scoliosis (AIS) patients treated with posterior fusion using all-pedicle-screw construct with correction carried out using a convex rod reduction technique.

Methods

Between October 2004 and June 2007, 42 AIS patients were treated with posterior fusion using all-pedicle-screw construct with correction done through the convex side. Two patients were lost to follow-up and were not included in the study. Forty patients had a minimum follow-up of 2 years. Patients were evaluated for the deformity correction in coronal and sagittal planes and for spinal balance.

Results

The mean preoperative Cobb angle of the major curve and secondary minor curves was 60° and 41°, respectively. Immediate postoperative mean Cobb angle of the major curve and secondary minor curves was 17° and 13°, respectively. Postoperative 2-year average major curve loss of correction was 7 %. Postoperative 2-year average minor curve loss of correction was 5 %. Preoperative thoracic kyphosis of 28° was changed to 22° in 2-years follow-up. The loss of thoracic kyphosis was most noted in hyperkyphotic patients.

Conclusions

The correction of AIS by convex-sided pedicular screws yields a coronal correction comparable to what is described in the literature for segmental concave-sided screws.     

Role of thoracoscopy for the sagittal correction of hypokyphotic adolescent idiopathic scoliosis patients

Purpose

Thoracic adolescent idiopathic scoliosis (AIS) curves (Lenke 1–4) are often characterized by hypokyphosis. Sagittal alignment remains challenging to correct, even with recent posterior segmental instrumentation. Some authors recommend anterior endoscopic release (AER) to reduce anterior column height, and facilitate thoracic kyphosis correction. The aim of this study was to assess the contribution of AER to sagittal correction in hypokyphotic AIS.

Methods

Fifty-six hypokyphotic (T4T12<20°) AIS patients were included. In group 1 (28 patients), patients first underwent AER, followed by posterior instrumentation and correction 5–7 days later. In group 2 (28 patients), patients underwent the same posterior procedure without AER. Posterior correction was performed in all cases using posteromedial translation and hybrid constructs consisting of lumbar pedicle screws and thoracic sublaminar bands. From radiological measurements performed using low-dose EOS radiographs, the correction of thoracic kyphosis was compared between the two groups.

Results

Groups 1 and 2 were comparable regarding demographic data and preoperative thoracic kyphosis (group 1: 11.7° ± 6.9° vs group 2: 12.1° ± 6.3°, p = 0.89). Postoperative thoracic kyphosis increase averaged 18.3° ± 13.6° in group 1 and 15.2° ± 9.0° in group 2. The benefit of anterior release was not statistically significant (p = 0.35).

Conclusion

Although previous studies have suggested that thoracoscopic release improved correction compared to posterior surgery alone, the current study did not confirm this finding. Moreover, results of the current series showed that no significant benefit can be expected from AER in terms of sagittal plane improvement when the posteromedial translation technique is used, even in challenging hypokyphotic patients.     

Segmental pedicle screws instrumentation and fusion to L5 for spinal deformity secondary to Duchenne muscular dystrophy: results with a minimum of 2 years follow-up

Background

Traditional treatment recommendations in the surgical treatment of scoliosis in Duchenne muscular dystrophy have included instrumentation and fusion to the sacrum/pelvis to correct pelvic obliquity and to restore the sitting balance of the trunk. However, caudal extent of instrumentation and fusion has remained a matter of considerable debate. This study was performed to determine the efficacy and safety of stopping segmental pedicle screw constructs at L5 in the surgical treatment of scoliosis in Duchenne muscular dystrophy (DMD), with mild pelvic obliquity (<15°).

Materials and methods

From May 2005 to June 2007, a total of 22 consecutive patients underwent posterior spinal fusion and segmental pedicle screw instrumentation only to L5 for scoliosis secondary to DMD. A minimum 2-year follow-up was required for inclusion in this study. Assessment was performed clinically and with radiologic measurements. Radiologic measurements included the Cobb angles of the curves in the coronal plane, thoracic kyphosis and lumbar lordosis in the sagittal plane, and pelvic obliquity. The operating time, blood loss, and complications were evaluated.

Results

Twenty patients, aged 11–17, were enrolled. The average follow-up period was 35 months. Preoperative coronal curves averaged 70° (range: 51–85°), with a postoperative mean of 15° (range: 8–25°) and 17° (range: 9–27°) at the last follow-up. Pelvic obliquity improved from 13° (range: 7–15°) preoperatively to 5° (range: 3–8°) postoperatively and 6° (range: 3–9°) at the last follow-up. Good sagittal plane alignment was recreated and maintained. No loss of correction of scoliosis and pelvic obliquity was noted. The mean operating time was 271 min (range: 232–308 min). The mean intraoperative blood loss was 890 ml (range: 660–1260 ml). The mean total blood loss was 2100 ml (range: 1250–2880 ml).There was no major complication.

Conclusion

Segmental pedicle screw instrumentation and fusion to L5 is effective and safe in patients with scoliosis secondary to DMD without significant pelvic obliquity initially and long term, obviating the need for fixation to the sacrum/pelvis. There was no major complication.     

Reciprocal sagittal alignment changes after posterior fusion in the setting of adolescent idiopathic scoliosis

Purpose

Surgical adolescent idiopathic scoliosis (AIS) management can be associated with loss of thoracic kyphosis and a secondary loss of lumbar lordosis leading to iatrogenic flatback. Such conditions are associated with poorer clinical outcomes during adulthood. The aim of this study was to evaluate sagittal plane reciprocal changes after posterior spinal fusion in the setting of AIS.

Methods

Thirty consecutive adolescents (mean age 14.6 years) with AIS Lenke 1, 2 or 3 were included in this retrospective study with 2 year follow-up. Full-spine standing coronal and lateral radiographs were obtained preoperatively, at 3 and 24 months postoperatively. Coronal Cobb angle, thoracic kyphosis (TK) and lumbar lordosis (LL) were measured. Surgical procedure was similar in all the cases, with use of pedicular screws between T11 and the lowest instrumented vertebra (≥L2), sublaminar hooks applied in compression at the upper thoracic level and sub-laminar bands and clamps in the concavity of the deformity. Statistical analysis was done using t test and Pearson correlation coefficient.

Results

Between preoperative and last follow-up evaluations a significant reduction of Cobb angle was observed (53.6° vs. 17.2°, p < 0.001). A significant improvement of the instrumented thoracic kyphosis, TK (19.7° vs. 26.2°, p < 0.005) was noted, without difference between 3 and 24 months postoperatively. An improvement in lumbar lordosis, LL (43.9° vs. 47.3°, p = 0.009) was also noted but occurred after the third postoperative month. A significant correlation was found between TK correction and improvement of LL (R = 0.382, p = 0.037), without correlation between these reciprocal changes and the amount of coronal correction.

Conclusion

Results from this study reveal that sagittal reciprocal changes occur after posterior fusion when TK is restored. These changes are visible after 3 months postoperatively, corresponding to a progressive adaptation of patient posture to the surgically induced alignment. These changes are not correlated with coronal plane correction of the deformity. In the setting of AIS, TK restoration is a critical goal and permits favorable postural adaptation. Further studies will include pelvic parameters and clinical scores in order to evaluate the impact of the noted reciprocal changes.     

Evaluation des sagittalen Profils nach operativer Therapie der thorakalen adoleszenten idiopathischen Skoliose Lenke Typ 1

Introduction

The principle philosophy of posterior spinal instrumentation and fusion (PSIF) for the treatment of adolescent idiopathic scoliosis (AIS) has changed during recent decades. In the past the treatment of AIS mainly focused on correction of the major curve in the frontal plane while the sagittal profile and balancing were only of inferior interest in treatment planning. Various long-term outcome studies have demonstrated that many AIS patients developed a flatback syndrome (decrease of thoracic kyphosis and lumbar lordosis) associated with pain. It was concluded that treatment of AIS should consider the sagittal profile and balance; however, there are only few studies addressing additional procedures, which include the correction of the sagittal profile.

Material and methods

The purpose of this study was to evaluate the effects of different posterior correction techniques on sagittal profile and balance. A total of 36 consecutive patients with thoracic AIS, who were treated with selective thoracic posterior correction were included in this retrospective study. The patients were further assigned to three different subgroups according to different surgical strategies: A: pedicle screws, B: long-head pedicle screws and C: additional Ponte osteotomy. Standardized radiographs in the standing position of the whole spine in two planes were evaluated before and at least 2 years after correction for all patients and a subgroup analysis was done to identify differences between the three groups.

Results

A significant correction of the major curve was achieved in all three groups (p?<?0.001). There was a significant difference between the groups with groups B and C showing significantly higher levels of major curve correction in comparison to group A (p?<?0.001). Concerning the sagittal profile, there was a significant difference in the development of thoracic kyphosis (TK) and lumbar lordosis (LL). While a significant reduction of TK and LL was found in groups A and B after surgery, a significant increase of TK and LL was noted in group C which was associated with a decrease of pelvic tilt and an increase of sacral slope. The 2-year follow-up showed the lowest ODI-% value only in group C which was positively correlated with reduction in pelvic tilt.

Conclusions

The results of this study underline that the PSIF technique alone using pedicle screws leads to a satisfactory correction in the frontal plane but is associated with adverse effects on the sagittal profile (flat back syndrome), corroborating previous studies. It was further shown that significant improvements of sagittal parameters were achieved by adding techniques for the lengthening of the dorsal thoracic column. This approach can therefore be recommended for the treatment of AIS Lenke type 1.     

Thoracic curve correction after posterior fusion and instrumentation of structural lumbar curves in patients with adolescent idiopathic scoliosis

Introduction

Spontaneous thoracic curve correction may occur following selective anterior spinal fusion in patients with adolescent idiopathic scoliosis (AIS). However, a few reports have described outcomes in patients following selective posterior fusion. The aim of this retrospective study was to assess curve correction in AIS patients with major lumbar curves and secondary thoracic curves after selective posterior fusion of the major curve.

Methods

The records of 42 AIS patients with major lumbar and minor thoracic curves who had received selective posterior lumbar fusion with segmental pedicle screw fixation were examined. Preoperative and follow-up radiographs were examined and the following were determined: curve flexibility, Cobb angle measurements of the major and minor curves, thoracolumbar/lumbar and thoracic Cobb measurements. Also, thoracolumbar/lumbar to thoracic Cobb ratios were determined. Minimum follow-up was 2?years. Patients were compared with respect to whether final thoracic curve improvement was (group A) or was not (group B) apparent. Improvement was indicated by a final thoracic curve that was less than the preoperative thoracic curve.

Results

Thoracic curve improvement was apparent in 32 of 42 patients after surgery. The mean preoperative thoracic curve in group A was 22.5° and 15.0° at follow-up, while corresponding values in group B were 35.0° and 39.8°. There were no cases in group A and eight cases in group B in which the preoperative thoracic curve was >30°. All patients in group B had preoperative thoracic curves on lateral bending >20°. Thoracic curvature at final follow-up was strongly correlated with preoperative thoracic curvature (r?=?0.911) and thoracic curvature on lateral bending (r?=?0.948).

Conclusions

Selective posterior fusion with segmental pedicle screw fixation in patients with major lumbar AIS resulted in curve correction in the majority of cases. Preoperative thoracic curvature and thoracic curvature on lateral bending were strongly correlated with the final thoracic curvature.     

Two-year results for scoliosis secondary to Duchenne muscular dystrophy fused to lumbar 5 with segmental pedicle screw instrumentation

Background

Instrumentation and fusion to the sacrum/pelvis has been a mainstay in the surgical treatment of scoliosis in patients with Duchenne muscular dystrophy since the development of the intrailiac post. It is recommended for correcting pelvic obliquity. However, caudal extent of instrumentation and fusion has remained a matter of considerable debate. This study was performed to determine the efficacy and safety of stopping segmental pedicle screw constructs at L5 during surgical treatment of scoliosis associated with Duchenne muscular dystrophy (DMD).

Methods

From May 2005 to June 2007, a total of 20 consecutive patients underwent posterior spinal fusion and segmental pedicle screw instrumentation only to L5 for scoliosis secondary to DMD. All patients had progressive scoliosis, difficulty sitting, and back pain before surgery. A minimum 2-year follow-up was required for inclusion in this study. Assessment was performed clinically and with radiological measurements. The Cobb angles of the curves and spinal pelvic obliquity were measured on the coronal plane. Thoracic kyphosis and lumbar lordosis were measured on the sagittal plane. These radiographic assessments were performed before surgery, immediately after surgery, and at a 3-month interval thereafter. The operating time, blood loss, and complications were evaluated. Patients were questioned about whether they had difficulty sitting and felt back pain before surgery and at 6 weeks, 1 year, and 2 years after surgery.

Results

A total of 20 patients, aged 11–17 years, were enrolled. The average follow-up period was 37 months. Preoperative coronal curves averaged 70° (range 51°–85°), with a postoperative mean of 15° (range 8°–25°) and a mean of 17° (range 9°–27°) at the last follow-up. Pelvic obliquity improved from 13° (range 7°–15°) preoperatively to 5° degrees (range 3°–8°) postoperatively and 6° (range 3°–9°) at the last follow-up. Good sagittal plane alignment was recreated and maintained. Only a small loss of correction of scoliosis and pelvic obliquity was noted. The mean operating time was 271 min (range 232–308 min). The mean intraoperative blood loss was 890 ml (range 660–1260 ml). The mean total blood loss was 2100 ml (range 1250–2880 ml). There was no major complication. All patients reported that difficulty sitting and back pain were alleviated after surgery.

Conclusion

Segmental pedicle screw instrumentation and fusion only to L5 is safe and effective in patients with DMD scoliosis of <85° and pelvic obliquity of <15°. Good sagittal plane alignment was achieved and maintained. All patients benefited from surgery in terms of improved quality of life. There was no major complication.     

Operative Therapie der idiopathischen Skoliose mittels ventraler Doppelstabinstrumentation

Background

In the surgical treatment of idiopathic scoliosis both anterior and posterior correction and instrumentation techniques are available. The aim of the present study was to analyse the results of a new anterior dual rod instrumentation.

Patients and methods

Prospective analysis of radiometric and clinical parameters of 93 patients operated on between 1996 and 2004 using the Münster Anterior Dual Rod System.

Results

The average curve correction was 65% (fusion length usually Cobb levels) with a preoperative Cobb angle of 59°. Postoperative loss of correction amounted to 1.5° (average follow-up of 36 months). Apical vertebral derotation averaged 45% in the thoracic and 53% in the lumbar spine with a subsequent correction of the rib hump of 66% and the lumbar hump of 81%. There were no revisions or neurological complications.

Conclusion

Anterior dual rod instrumentation enables an effective and safe three-dimensional curve correction in single structural curves with only minimal loss of correction.     

Sagittal balance correction of idiopathic scoliosis using the in situ contouring technique

Purpose

Idiopathic scoliosis can lead to sagittal imbalance. The relationship between thoracic hyper- and hypo-kyphotic segments, vertebral rotation and coronal curve was determined. The effect of segmental sagittal correction by in situ contouring was analyzed.

Methods

Pre- and post-operative radiographs of 54 scoliosis patients (Lenke 1 and 3) were analyzed at 8 years follow-up. Cobb angles and vertebral rotation were determined. Sagittal measurements were: kyphosis T4–T12, T4–T8 and T9–T12, lordosis L1–S1, T12–L2 and L3–S1, pelvic incidence, pelvic tilt, sacral slope, T1 and T9 tilt.

Results

Thoracic and lumbar curves were significantly reduced (p = 0.0001). Spino-pelvic parameters, T1 and T9 tilt were not modified. The global T4–T12 kyphosis decreased by 2.1° on average (p = 0.066). Segmental analysis evidenced a significant decrease of T4–T8 hyperkyphosis by 6.6° (p = 0.0001) and an increase of segmental hypokyphosis T9–T12 by 5.0° (p = 0.0001). Maximal vertebral rotation was located at T7, T8 or T9 and correlated (r = 0.422) with the cranial level of the hypokyphotic zone (p = 0.003). This vertebra or its adjacent levels corresponded to the coronal apex in 79.6 % of thoracic curves.

Conclusions

Lenke 1 and 3 curves can show normal global kyphosis, divided in cranial hyperkyphosis and caudal hypokyphosis. The cranial end of hypokyphosis corresponds to maximal rotation. These vertebrae have most migrated anteriorly and laterally. The sagittal apex between segmental hypo- and hyper-kyphosis corresponds to the coronal thoracic apex. A segmental sagittal imbalance correction is achieved by in situ contouring. The concept of segmental imbalance is useful when determining the levels on which surgical detorsion may be focused.     

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.     

Segmental pedicle screw instrumentation in idiopathic thoracolumbar and lumbar scoliosis

The role of posterior correction and fusion in thoracolumbar and lumbar scoliosis as well as pedicle screw instrumentation in scoliosis surgery are matters of debate. Our hypothesis was that in lumbar and thoracolumbar scoliosis, segmental pedicle screw instrumentation is safe and enables a good frontal and sagittal plane correction with a fusion length comparable to anterior instrumentation. In a prospective clinical trial, 12 consecutive patients with idiopathic thoracolumbar or lumbar scolioses of between 40° and 60° Cobb angle underwent segmental pedicle screw instrumentation. Minimum follow-up was 4 years (range 48– 60 months). Fusion length was defined according to the rules for Zielke instrumentation, normally ranging between the end vertebrae of the major curve. Radiometric analysis included coronal and sagittal plane correction. Additionally, the accuracy of pedicle screw placement was measured by use of postoperative computed tomographic scans. Major curve correction averaged 64.6%, with a loss of correction of 3°. The tilt angle was corrected by 67.0%, the compensatory thoracic curve corrected spontaneously according to the flexibility on the preoperative bending films, and led to a satisfactory frontal balance in all cases. Average fusion length was the same as that of the major curve. Pathological thoracolumbar kyphosis was completely corrected in all but one case. One patient required surgical revision with extension of the fusion to the midthoracic spine due to a painful junctional kyphosis. Eighty-five of 104 screws were graded “within the pedicle”, 10 screws had penetrated laterally, 5 screws bilaterally and 4 screws medially. No neurological complications were noted. In conclusion, despite the limited number of patients, this study shows that segmental pedicle screw instrumentation is a safe and effective procedure in the surgical correction of both frontal and sagittal plane deformity in thoracolumbar and lumbar scoliosis of less than 60°, with a short fusion length, comparable to anterior fusion techniques, and minimal loss of correction. Received: 23 September 1999 Revised: 20 January 2000 Accepted: 26 January 2000     

Dreidimensionale Korrekturprinzipien einer dreidimensionalen Deformit?t

Background

There is presently still no consensus on how to operatively treat adolescent idiopathic scoliosis (AIS), i.e. a clearly reduced thoracic kyphosis. For a long time the primary focus was mostly on correcting the coronal plane while neglecting the sagittal profile. Based on the current literature and own retrospective data a comprehensive review will be given on the optimal correction of the spine and how to avoid secondary complications. Different operative standard procedures are demonstrated with special attention to the sagittal balance and the special parameters sagittal vertical axis (SVA), lumbar lordosis (LL), thoracic kyphosis (TK), pelvic tilt (PT), sagittal slope (SSL) and pelvic incidence (PI).

Results

A total of 24?patients (2 groups of 12?patients) with AIS and posterior fusion with (group?A) and without (group?B) additional osteotomy were analyzed with respect to the impact on spinopelvic balance and health-related quality of life (HRQoL) parameters. Patients in group?A had a significant reduction of TK, LL and SSL and an increase in PT whereas patients in group?B showed the opposite. Correlation analysis revealed a significant dependence of HRQoL on PT.

Discussion

Both the results from the literature and own data confirm that operative correction of AIS needs a careful planning including sagittal spinopelvic parameters. Rigid thoracic hypokyphosis require additional osteotomy.     

Use of the Universal Clamp for deformity correction and as an adjunct to fusion: preliminary results in scoliosis

Purpose

Evaluation of a novel instrumentation device for adolescent idiopathic scoliosis.

Methods

A new osteosynthesis implant (Universal Clamp) primarily consisting of a sublaminar band and titanium clamp was prospectively studied in 32 patients (average age, 15 years) with a major thoracic curve.

Results

The Universal Clamp was used without anterior release to reduce and maintain correction of the thoracic curve, which improved from 55.1° preoperatively to 14.5° at 3 months without neurological complication or loss of kyphosis.

Conclusions

This implant distributes stress over a larger area of the laminar cortex than sublaminar wires, patently reducing the risk of laminar fracture for equivalent reduction forces, and permits progressive reduction at several apical levels simultaneously.     

Modified technique of transforaminal lumbar interbody fusion for segmental correction of lumbar kyphosis: a safe alternative to osteotomies?

Background

Sagittal rebalancing of a fixated lumbar hypolordosis (kyphosis) is very important to gain satisfactory results. To correct a misalignment vertebral column resection or pedicle subtraction osteotomies are favored, disregarding the relatively high complication rates. The aim of this study was to evaluate the efficiency and safety of a new modified transforaminal lumbar fusion technique as an alternative.

Methods

We conducted a retrospective review (06/2011-06/2015 ) of a prospective database at an University hospital. Inclusion criteria were adult patients with a fixated lumbar hypolordosis and the need of monosegmental correction of more than 10° with an mTLIF. Exclusion criteria consisted of minor aged patients and polysegmental corrections. Study parameters were the perioperative complications and the achieved postsurgical lordosis. The follow up period was 6 months.

Results

A total of 11 patients could be included. The mean segmental lordosis was -2.3° ± 12.4° (range -22° to 14°) preoperative and 15.5° ± 10.5° (range 0° to 29°) postoperative. The degree of correction was 17° ± 5.7° in mean per treated segment (range 12° to 29°). No neurologic or vascular complications occurred. No substantial loss of correction or implant failure was noted during the 6-month follow-up.

Conclusion

The modified transforaminal lumbar fusion technique is a safe method to correct a fixated lumbar kyphosis. The potential of segmental correction is comparable to pedicle subtraction osteotomies but sparing potentially healthy segments.

     

Indication for preoperative MRI of neural axis abnormalities in patients with presumed thoracolumbar/lumbar idiopathic scoliosis

Purpose

The purpose of this study was to investigate the incidence of neural axis abnormalities in patients with presumed “idiopathic” thoracolumbar or lumbar scoliosis by magnetic resonance imaging (MRI) and try to determine which clinical and radiographic characteristics correlate with neural axis abnormalities on MRI in these patients.

Methods

The database of a single spinal deformity center was retrospectively reviewed to identify all patients with a primary diagnosis of idiopathic scoliosis (IS) between January 2003 and August 2011. A total of 446 patients with main thoracolumbar or lumbar curves were identified. Radiographic parameters including main curve Cobb angles, location of curve apex, span of main curve, thoracic kyphosis (T5–T12), thoracolumbar junction kyphosis (T10–L2), lumbar lordosis (L1–S1), and sagittal and coronal balance were measured.

Results

Neural axis abnormalities were detected in 35 (7.8 %) patients. For patients with neural axis abnormalities, a higher proportion of male gender and long thoracolumbar curves were presented. In these patients, the mean age was smaller and the mean Cobb angle of main curve was larger. Greater thoracic kyphosis (≥30°) was more frequently found in those with neural axis abnormalities. The incidences of thoracolumbar junction hyperkyphosis were similar between two groups (P > 0.05). There was no difference between two groups as to lumbar lordosis and coronal and sagittal balance.

Conclusion

We recommend the routine use of MRI in the patients with one or more of the following characteristics: right curves, long curve span, apex at thoracolumbar spine and hyperthoracic kyphosis.     

Adolescent idiopathic scoliosis treated with posteromedial translation: radiologic evaluation with a 3D low-dose system

Purpose

Computed tomography can be used for three-dimensional (3D) evaluation of adolescent idiopathic scoliosis (AIS) patients, but at the expense of high radiation exposure, and with the limitation of being performed in the supine position. These drawbacks can now be avoided with low-dose stereoradiography, even in routine clinical use. The purpose of this study was to determine the 3D postoperative correction of AIS patients treated by posteromedial translation.

Methods

Forty-nine consecutive patients operated for AIS (Lenke 1–4) using posteromedial translation were included. Corrections were evaluated preoperatively, postoperatively and after at least 2 years using the EOS imaging system. 3D angles were measured in the plane of maximum deformity.

Results

Mean number of levels fused and operative time were 13.5 ± 1 and 215 ± 25 min, respectively. Main thoracic, proximal thoracic, and lumbar curves corrections averaged 64.4 ± 18, 31 ± 10 and 69 ± 20 %, respectively. Mean T4–T12 kyphosis increased 18.8° ± 9° in the subgroup of hypokyphotic patients. Mean apical vertebral rotation reduction was 48.3 ± 20 %. Trunk height gain averaged 27.8 ± 14 mm. There was no pseudarthrosis or significant loss of correction in any plane during follow-up. Two patients (4 %) developed asymptomatic proximal junctional kyphosis, despite having normal thoracic kyphosis. Their sagittal balance was shifted posteriorly by 36 and 47 mm, respectively, by the operation, but revision surgery was not performed.

Conclusions

Low-dose stereoradiography provided 3D reconstructions of the fused and unfused spine in routine clinical use. Postoperative 3D analysis showed that posteromedial translation enhanced sagittal balance correction, without sacrificing frontal or axial correction of the deformity.     

Posterior short-segment instrumentation and limited segmental decompression supplemented with vertebroplasty with calcium sulphate and intermediate screws for thoracolumbar burst fractures

Purpose

Thoracolumbar burst fractures treated with short-segment posterior instrumentation without anterior column support is associated with a high incidence of implant failure and correction loss. This study was designed to evaluate the clinical and radiographic results following posterior short-segment instrumentation and limited segmental decompression supplemented with vertebroplasty with calcium sulphate and intermediate screws for patients with severe thoracolumbar burst fractures.

Methods

Twenty-eight patients with thoracolumbar burst fractures of LSC point 7 or more underwent this procedure. The average follow-up was 27.5 months. Demographic data, radiographic parameters, neurologic function, clinical outcomes and treatment-related complications were prospectively evaluated.

Results

Loss of vertebral body height and segmental kyphosis was 55.3 % and 20.2° before surgery, which significantly improved to 12.2 % and 5.4° at the final follow-up, respectively. Loss of kyphosis correction was 2.2°. The preoperative canal encroachment was 49 % that significantly improved to 8.8 %. The preoperative pain and function level showed a mean VAS score of 9.2 and ODI of 89.9 % that improved to 1.4 and 12.9 % at the final follow-up, respectively. No implant failure was observed in this series, and cement leakage occurred in two cases without clinical implications.

Conclusions

Excellent reduction and maintenance of thoracolumbar burst fractures can be achieved with short-segment pedicle instrumentation supplemented with anterior column reconstruction and intermediate screws. The resultant circumferential stabilization combined with a limited segmental decompression resulted in improved neurologic function and satisfactory clinical outcomes, with a low incidence of implant failure and progressive deformity.     

Changes in the sagittal spinal alignment of the elderly without vertebral fractures: a minimum 10-year longitudinal study

Background

Thoracic hyperkyphosis, or loss of lumbar lordosis, is often equated with osteoporosis because vertebral fractures are assumed to be a major causative factor. However, recent evidence suggests that up to one-half of the patients with hyperkyphosis have no evidence of underlying vertebral fracture. The shape characteristics of the intervertebral discs and their role in determining kyphotic curvature have been investigated. The spinal sagittal parameters and segmental disc angles of elderly subjects were examined during a longitudinal follow-up.

Methods

A total of 53 subjects (20 men, 33 women) without vertebral fractures during a more than 10-year follow-up were included in this study, undergoing standing lateral radiographs of the spine using 36-inch film at baseline and final follow-up. The mean age of the subjects was 63 years (range 50–77 years) at baseline and 75 years (range 62–88 years) at follow-up; and the mean follow-up period was 11 years 11 months.

Results

The lumbar lordosis and the sacral inclination angle decreased and the C7-plumbline distance increased with age. Among a total of 664 discs, 70 discs (10.5%) showed anterior wedging over 5° at follow-up. In contrast, 39 discs (5.9%) showed posterior wedging over 5°. The subjects had only discs with anterior wedging, decreased total lumbar lordosis, and the C7 plumbline displaced anteriorly. However, when the subjects had discs with posterior wedging, the C7 plumbline and sagittal spinal balance tended to be maintained. This compensatory mechanism was seen in younger subjects.

Conclusions

A decrease in the total lumbar lordosis and the sacral inclination angle occurred with age. Increasing age correlated with a more forward sagittal vertical axis, depending on a decrease in the total lumbar lordosis. The cause of loss of lumbar lordosis in the subjects without vertebral fracture was anterior wedging of the segmental discs. Posterior wedging of the thoracic and lumbar segmental discs then could occur, compensating for the loss of lumbar lordosis.     

Posterior-only correction of Scheuermann kyphosis using pedicle screws: economical optimization through screw density reduction

Introduction

Posterior-only approach using pedicle screws’ fixation has emerged as the preferred surgical technique for Scheuermann kyphosis (SK) correction. Insertion of multiple pedicle screws while increasing stability increases also the risk of complications related to screw malpositioning and surgical cost. The optimal screw density required in surgical correction of SK remains unclear. This study compares the safety and efficacy of low screw density (LSD) versus high screw density (HSD) technique used in posterior-only correction of SK.

Methods

Twenty-one patients underwent surgical correction of SK between 2007 and 2011 and were reviewed after a mean of 29 months. HSD technique (i.e., 100 % of available pedicles, averaged 25.2 ± 4 screws) was used in 10 cases and LSD technique (i.e., 54–69 % of available pedicles in a pre-determined pattern, averaged 16.8 ± 1.3 screws; p < 0.001) was used in 11 cases. Kyphosis correction was assessed by comparing thoracic kyphosis, lumbar lordosis and sagittal balance on preoperative and postoperative radiographs. Cost saving analysis was performed for each group.

Results

Preoperative thoracic kyphosis, lumbar lordosis and sagittal balance were similar for both groups. The average postoperative kyphosis correction was similar in both HSD and LSD groups (29° ± 9° vs. 34° ± 6°, respectively; p = 0.14). Complication occurred in four patients (19 %) in the HSD group and in two patients (9 %) in the LSD group (p = 0.56). Three patients required re-operation. Compared to HSD using LSD saves 4,200£ per patient in hardware and 88,200£ for the entire cohort.

Conclusion

LSD technique is as safe and effective as HSD technique in posterior-only correction of SK. Implant-related cost could be reduced by 32 %.