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 Table of Contents  
SYMPOSIUM: ADOLESCENT IDIOPATHIC SCOLIOSIS
Year : 2020  |  Volume : 3  |  Issue : 2  |  Page : 196-206

Role of anterior surgery in idiopathic scoliosis: A literature review


Department of Spine Surgery, Primus Superspeciality Hospital, New Delhi, India

Date of Submission09-Dec-2019
Date of Decision22-Jan-2020
Date of Acceptance07-Jun-2020
Date of Web Publication13-Jul-2020

Correspondence Address:
Dr. Naveen Pandita
Department of Spine Surgery, Primus Superspeciality Hospital, Chankyapuri, New Delhi.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/isj.isj_80_19

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  Abstract 

Scoliosis is lateral curvature of the spine, which includes three-dimensional deformity. Both anterior and posterior approaches have been used to treat the deformity. Over the period of time, anterior scoliosis surgery has been popularized by various people albeit for selective indications. A literature review was done searching available literature from 1970 to 2019, using medical search engines, PubMed and Google Scholar. Review was aimed at defining the current status and indications for anterior surgery in adolescent idiopathic scoliosis. Anterior scoliosis surgery leads to similar correction compared to posterior surgery with additional advantage of saving of fusion levels along with preservation of more mobility. The pulmonary function affection from clinical standpoint remains limited with anterior approaches. Currently, anterior approaches are used for treating Lenke type 5 and 6 curves with similar results to posterior surgery. In addition, anterior approach can be an essential adjunct to posterior surgery in severe curves where there is significant stiffness.

Keywords: Anterior fusion, anterior surgery, deformity correction, scoliosis
Key Messages: Anterior surgery in idiopathic scoliosis can be advantageous in Lenke type 5 and 6 curves in terms of saving fusion levels in lumbar spine. In severe thoracic curves, prior anterior release can help in achieving better correction without significant pulmonary compromise.


How to cite this article:
Srivastava A, Pandita N, Jayaswal A. Role of anterior surgery in idiopathic scoliosis: A literature review. Indian Spine J 2020;3:196-206

How to cite this URL:
Srivastava A, Pandita N, Jayaswal A. Role of anterior surgery in idiopathic scoliosis: A literature review. Indian Spine J [serial online] 2020 [cited 2020 Aug 10];3:196-206. Available from: http://www.isjonline.com/text.asp?2020/3/2/196/289662




  Introduction Top


Scoliosis is defined as lateral curvature of the spine, which also includes three-dimensional deformity, including rotation and altered sagittal profile. Although anterior approaches are used for selective indications, they have their inherent advantages over a posterior approach which includes better curve correction, derotation, and saving of fusion levels. The disadvantage of anterior surgery is the violation of the thoracic/thoracolumbar cavity, which leads to alteration in pulmonary biology and function. Currently, anterior surgery is used mostly for correction of thoracolumbar/lumbar curve (Lenke 5). The evolution of anterior scoliosis surgery and instrumentation can be traced back to the introduction of Dwyer system.[1] In 1970s, when Paul Harrington was developing his distraction-based instrumentation for posterior scoliosis correction,[2] the anterior approach at that time was considered superior to the posterior approach as it provided short segment fusion with better sagittal profile and higher chances of fusion. Further modifications were done by Zielke et al.,[3] which included placing the screws more posteriorly in the body. It gave improved derotation effect along with better sagittal alignment and used stronger rods than Dwyer cables.[2] However, the complications were still high, which included rod/cable breakages, pseudarthrosis, and loss of correction. With the intention to minimize the complications, Kaneda et al.[4] introduced his next generation of anterior implants/technique using two-rod system which was more robust and biomechanically superior with better derotation capabilities. Since the 1990s, with the advent of thoracoscopic techniques, minimally invasive anterior releases are being performed along with corrective surgeries. Nonfusion growth modulating surgeries with anterior tethers and staples have been introduced which can also be done thoracoscopically. Anterior release, either open or thoracoscopic, has been used as an adjunct to posterior instrumented correction in rigid and severe deformity.


  Method Top


A thorough literature search was done using the Medical search engines, PubMed, Scopus, MEDLINE, and Google Scholar, from 1970 to 2019. To maximize the relevance and sensitivity of the search, we used various key words: anterior spine surgery, anterior scoliosis surgery, anterior spine, deformity correction, and idiopathic scoliosis. Approximately 2041 articles were found related to our search. Of these 82 articles were found to be relevant to idiopathic scoliosis and anterior surgery, published in English. Literature was thoroughly searched for available articles on various topics of anterior surgery including historical prospective, various approaches in anterior scoliosis surgery, indications, current status, various advantages and disadvantages over more popular posterior approach, and recent advances in anterior surgery. Full texts of the published studies were manually organized and examined to ensure that no clinically relevant studies were missed. All the available literature was used in the review article to summarize the current role and status of anterior scoliosis surgery.


  Anterior Scoliosis Correction (Level Selection) Top


Lumbar curves

The plan to decide on the number of fusion levels in anterior surgery particularly in the lumbar spine is based on supine bend films and standing posterio-anterior (PA) whole spine films as described by Bernstein and Hall.[5] The fusion levels are based on whether the disc or vertebral body is placed as the most horizontal structure at the apex of the primary curve in standing films. If it is a disc which is the most horizontal then two vertebrae cephalad and two vertebrae caudal were included in the fusion. Alternatively, if the most horizontal level is a vertebral body, then one body above and below the said level is included in the fusion. On supine bend films, the disc spaces both on top and bottom of the main curve which open up on convexity are left unfused. The curve apex is planned to be overcorrected to the other side, and therefore a residual L5 tilt was accepted if any. In case of any divergence between the levels of fusion in supine and bending films, the longer segment was preferred. The intention is to stack the vertebral bodies above and below the apex over the sacrum, parallel to each other once the correction is done.[5]

Others such as Lenke et al.[6] recommend inclusion of all the vertebrae from the upper-end vertebrae to lower end vertebrae in the fusion length, which essentially includes all the convex discs within the instrumentation.

In authors’ opinion in Lenke 5 curves, only fusion from end to end vertebrae is recommended.

Thoracic curves

In thoracic curves, the usual length of fusion in anterior spinal surgery is from upper end vertebrae to lower end vertebrae. Commonly the upper extent of fusion is limited to T4 due to access related issues. However, if the flexibility of proximal curve was found to be rigid as identified by flexibility of less than 50%, in order to prevent decompensation fusion was limited to 1 level below the end vertebrae. As far as distal instrumented vertebrae is concerned it is the lower end vertebrae except when neutral vertebrae is one level proximal to the end vertebrae then that is chosen as lower instrumented vertebrae.[7]

This is in contrast to posterior pedicle screw constructs where the extent of fusion classically is from neutral vertebrae above to stable, stable minus 1 or 2 below, depending on the separation between the end vertebrae and neutral vertebrae. If the separation was less than two levels, then distal fusion was extended to neutral vertebrae which corresponded to stable minus one. However, if the separation was more than two levels then it is recommended to fuse up to neutral vertebrae minus 1 which matches with stable minus 2[6],[7],[8].

Further detailed comparison between anterior and posterior surgery is discussed in a subsequent subsection.


  Outcomes of Anterior Surgery Top


Sagittal curve correction

The utility of sagittal alignment cannot be overemphasized. Many studies have reported that clinical outcomes are better in patients who have a balanced spine compared to an unbalanced one.[9],[10] Idiopathic scoliosis is usually associated with thoracic hypokyphosis in the main thoracic curve and lumbar hypolordosis in the thoracolumbar/lumbar curve. In the sagittal plane, anterior procedures on the convex side of the curve apply cantilever and compression forces which lead to shortening and kyphosis. Hence, anterior spinal fusion (ASF) is better at restoring thoracic kyphosis which is sustained in the long-term follow-up without causing significant overcorrection in skeletally mature patients with Lenke type 1 and 3 curves.[11],[12],[13] Thus, preexisting hyperkyphosis is a relative contraindication for anterior thoracic scoliosis surgery especially in immature spine.[14] The posterior approach for 5C curves obtained a larger increase of Cobb angle of lumbar lordosis than the anterior approach, from preoperative to final follow-up in thoracic adolescent scoliosis as observed in the meta-analysis.[15] Anterior instrumentation is kyphogenic, so in the lumbar spine in order to restore the lordosis, it is pertinent to supplement the construct with interbody structural grafts or interbody cages below L1.

Meta-analysis by Lin et al.[16] suggested that anterior thoracic fusion is superior to posterior selective thoracic fusion for spinal correction in the sagittal plane as it increases kyphosis in an otherwise hypokyphotic thoracic scoliotic curve [Tables 1] and [2].
Table 1: Advantages and disadvantages of anterior approach for adolescent idiopathic scoliosis

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Table 2: Summary details of important meta-analysis and studies published

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Coronal curve correction

There is not much significant difference in coronal deformity correction in both anterior and posterior surgery with the added advantage of a shorter fusion anteriorly.

The percentage curve correction by anterior approach in thoracolumbar/lumbar curves ranged from 54.4% to 77% compared to posterior surgery where the correction percentage ranged from 55.2% to 88%. However, no statistically significant difference was noted in percentage correction rate as concluded by Lao et al.[15] in meta-analyses.

Vavruch et al.[17] compared anterior and posterior thoracic curve correction in their study and noted that thoracic Cobb angle correction was 57% ± 12% in the anterior cohort and 73% ± 12% in the posterior cohort (P < 0.001) directly after surgery, and 55% ± 13% and 66% ± 12% (P 1⁄4 0.001), respectively, after 2 years follow-up. Thus the loss of correction is more in posterior correction compared to anterior correction.

Correction of vertebral body rotation

Vertebral body rotation specifically at the apex contributes significantly to the cosmetic deformity in the form of rib hump. Hence, alteration of rotation is a vital component of correction maneuver to obtain satisfactory cosmetic results. Anterior surgery has inherent advantage, more so in structural/mature curves, in providing extensive release of obstructing structures to correction such as disc, annulus, and longitudinal ligaments. Moreover, the anterior placement of screws provides greater moment arm and corrective force application compared to posterior hooks. This allows far better correction of axial rotation compared to traditional posterior approaches such as hooks and wire construct. With the advent of all posterior pedicle screw constructs and powerful de-rotation manouvers, the rotational correction has been statistically significant especially in more flexible curves. The rotation angle midline for anterior approach corrected from 26.2 ± 4.8 to 21.8 ± 4.7, whereas the values for posterior pedicle screw construct improved from 25.5 ± 4.6 to 22.6 ± 5.3 at the end of 2-year follow-up.

However, the percentage correction of midline rotation is higher in the anterior approach (16.8%) when compared to the pedicle screw constructs (11.4%).[18]

Spontaneous compensatory curve correction

Anterior surgery leads to good correction of rotation and compensatory curve in both immediate and the long-term follow-up with range of 35%–48% as outlined in various long-term studies.[7],[19],[20]

Compensatory Thoracic curves: Yoshihara in his systematic review on Lenke 5C curves mentioned the values reported by various studies have higher variability/ range for proximal spontaneous correction, for posterior surgery (19%–67%) compared to anterior surgery (17%–52%).[21]The posterior might have better correction (may be statistically not significant). The correction in posterior surgery was less than the initial flexibility shown by the proximal curves.[22] Recently, Delfino et al.[23] reported long-term results of thoracolumbar anterior scoliosis surgery with a mean follow-up of 17.3 years where the compensatory thoracic curve corrected from 31.4° to 18.4° in the immediate postoperative period and stayed at 17.8° at the final follow-up.

Compensatory lumbar/thoracolumbar curves: Dobbs et al.[24] have regarded push prone films to be of significant value in predicting the behavior of the lumbar curve after doing selective thoracic fusion in both anterior and posterior approach. Spontaneous lumbar/thoracolumbar curve correction is noted both in selective anterior and posterior corrective surgery, with some authors stating it to be better in anterior curve correction.[25],[26] This leads to saving of lumbar segment and shorter fusion levels which leads to better mobility in these patients. Maintenance of spontaneous lumbar curve correction was closely related to initial main thoracic curve correction and its maintenance after anterior spine surgery. This was seen even up to 18 years of follow-up duration.[27]

Lowe et al.[28] have reported an increase in T2–T5 kyphosis (PJK) in posterior selective thoracic fusion as compared to the anterior approach.

Functional outcome

Patients reported that health-related quality of life outcomes are an important tool to quantify the pathology and assess the effect of an intervention on it. Anterior spinal surgery for adolescent idiopathic scoliosis has been shown to be effective in improving the patient reported outcomes such as SRS-30/SRS-24/SRS-22 even on long-term follow-up.[19],[29] A comparative study of Lenke 5C curve correction done by anterior and posterior approach by Miyanji et al.[30] shows no significant difference in the Scoliosis Research Society (SRS) functional outcome scores [Table 2]. However, the information is limited on long-term functional outcome as pointed out in the meta-analysis by Luo et al.[15] on Lenke 5C curves.

Similarly, there is paucity of many studies looking into the functional outcome of anterior surgery compared to posterior surgery in Lenke 1 and 2 curves. Nohara et al.[31] showed a significant improvement in the functional outcome of patients treated with ASF versus posterior spinal fusion (PSF) as measured by SRS-30 self-image scores. This is deviation from the findings of Lonner et al.[32] who noted no significant difference in the functional outcome of the two approaches.


  Anterior Loosening/Release in Rigid Scoliosis Top


Anterior release at the apex of curve has been a prevalent strategy to make the scoliotic curve more flexible before planning definitive posterior instrumentation and correction. This in many cases obviates the need for aggressive osteotomies such as vertebral column resection for final curve correction, which have high morbidity and risk of neurological deficit. Routine use of anterior release has diminished in moderate curves (curves less than 90°). With the use of all pedicle screw constructs, various authors in recent years argue against anterior release even in curves greater than 70° but usually less than 90° and propose a posterior pedicle screw approach with or without posterior release and osteotomies.[33],[34],[35],[36] However, utility of anterior release in select cases continues to be relevant. These include rounded, severe rigid deformity which include scoliosis >90–100° and flexibility less than 30%,.[37],[38] The anterior release can be done either via a thoracoscopic approach where multiple annulotomies and discectomies are done.[39],[40],[41] Alternatively, open anterior release with more aggressive discectomies and placement of bone graft can be done, through a routine thoracotomy, to augment the anterior fusion and provide more flexibility [Figure 1]. Aggressive anterior discectomy with posterior rib resection increases the coupled motions between the individual vertebrae and enhance rotational correction of deformity[42],[43] Thus for the curves which are severe and rigid, anterior release still holds a place in safe and effective management of these curves.
Figure 1: Case example of 15-year-old female with rigid scoliosis achieved 30% correction of deformity after anterior release

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  Complications Top


General complications including neurological

Adolescent Idiopathic Scoliosis in general has the lowest rates of complication when compared to other types of scoliosis such as neuromuscular and syndromic scoliosis. This has been substantiated by the SRS mortality and morbidity report presented by Coe et al. and another report from Harms Study Group by Bartley et al., which places the overall major complication rate at 5.7% (363/6334 patients) and 5.4%, respectively.[44],[45],[46] Overall complication rate reported in literature after anterior scoliosis surgery is approximately 3%–5.2%), which is marginally greater in magnitude to posterior surgery (2.6%–5.1%). However, the complication rate tends to increase when both approaches are combined (5.6%–10.2%). This risk factor was identified by both Bartley et al. and Coe et al. in the large series of patients and they advised specific counselling before the combined surgery.[44],[45],[46] Bartley et al.[46] reported the rate of neurologic complications in the perioperative period at 0.53%. Most common complication consisted of nerve root injury (0.17%) followed by spinal cord injury (0.14%), and also included a third class labelled as “other” (0.22%), which incorporated changes in intraoperative neurophysiologic monitoring (IONM) or weakness resulting in an unplanned staged procedure.

The most common complications for anterior procedures as reported by Coe et al. were pulmonary which included hemothorax, pneumothorax, pneumonia, and ventilatory support (1.6%). The next most common complication was implant-related (1.4%). Wound infections were reported in only a small number of patients (0.2%–0.6%) of anterior only procedures where as it was the most common complication in posterior procedure group (1.4%). The rate of superficial and deep wound infection appears to be significantly lower in patients compared to posterior instrumentation. Incidence rate of various other perioperative complications encountered after anterior approach include dural tear (0.26%), nonfatal hematologic (0.26%), and neurologic (0.26%). The risk of neurologic deficit is lower in anterior surgery as compared to posterior surgery and is usually incomplete spinal cord injury. The recovery of incomplete neurological deficit is better as compared to complete one. However, the perioperative complication rate is slightly higher (3% vs. 2.4%) for anterior surgery group.

The delayed major complication rate as mentioned by Bartley et al. for anterior surgical approach is 3.8%, which includes implant failure, nonunion, delayed wound infection and reoperations and in small cases neurologic deficits (usually nerve root injury/radiculopthy), and is comparatively lower than posterior approach (4.2%).[44],[45],[46]

The neurological recovery rates were approximately 61% in patients with automatic identification system (AIS) as reported by Coe et al.[44] (SRS data) with no patient reporting complete deficits for all the approaches.. This was also reported by Reames et al.’s[47] study of SRS database in which they reported partial or full recovery in all patients with neurological deficits (cord/root) except one, with overall rate of new neurological deficit at 0.8%. However, they did not provide specific recovery rates for anterior surgery.

Pulmonary complications

Anterior surgery leads to disruption of the chest cavity, which can potentially alter the pulmonary function in an undesirable way. Kim et al.[48] showed that pulmonary function as measured by forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) at 2-year postoperative was significantly decreased in patients undergoing thoracotomy. Lonner et al.[49] and Newton et al.[50] in their study further stated minimal changes in pulmonary function with throracoscopic and thoracoabdominal approach. In contrast to this, Urquhart et al.[51] and Zhou et al.[52] noted, in a small group of patients, no significant decrease in FEV1 and FVC at mean follow-up of 5.8 years with a combined anterior and posterior approach for high-grade scoliosis with mean 100° Cobb angle.

Lee et al.[53] in their meta-analysis, analyzing pulmonary function changes after anterior scoliosis surgery and thoracoplasty, found that at 2 years followup there was no significant change in the pulmonary function of these patients from preoperative values. On long-term follow-up at 5,[26] 10 and 15 years, there is a gradual decline in % predicted pulmonary function test (PFT) values as outlined by Yaszey et al.,[54] Gitelman et al.,[55] and Sudo et al.,[7] respectively, which is in contrast to posterior fusion where the drop is minimal. However, Sudo et al.[7] in their analysis did not report any clinical complaints related to reduced PFT. Recently, Yaszey et al.[54] stated that % predicted FEV declined in patients the most with anterior approach at 2 years’ and 5 years’ follow-up. This leads them to suggest that concerns around anterior surgery PFT alteration might be exaggerated as anterior surgery does not decrease the PFT from preop values, but there is a decline in % predicted values in the long term, which may not be clinically significant.

Junctional kyphosis (proximal and distal)

Distal junctional kyphosis is an important factor for deterioration of clinical outcomes over time in scoliosis surgery along with symptoms such as pain, decompensation, and reemergence of cosmetic concerns. The incidence of distal junctional kyphosis (DJK) noted in a comparative study of thoracic adolescent curves treated by anterior surgery was 7.1% compared to 14.6% in posterior surgery group.[28] The primary risk factor outlined by Lowe et al.[28] in selective anterior fusion included inability to recreate and maintain the sagittal profile. Therefore, the use of inter-vertebral graft /cages for maintaining adequate lordosis and extending proximal instrumentation beyond kyphotic area is instrumental in preventing DJK following anterior surgery. Therefore, we recommend extension up to L1/L2 with interbody cages below as shown in Case 1 [Figure 2]. The distal adding on effect (DAO) is defined as >5° of increase of Cobbs in postoperative follow-up and when end vertebrae moves distally in the follow-up period. This incidence was noted to be high after anterior thoracic scoliosis surgery (33% compared to 7% in posterior group at 5 years postoperative duration). Curves with Lenke type 1A treated by anterior spine surgery are at high risk for DAO.[31]
Figure 2 (Case 1): Case example of 14-year-old male with right thoracic scoliosis Lenke 1, treated by anterior release with instrumented fusion showing good clinical and radiological result

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Miyanji el al. in their comparative study observed that, despite providing the advantage of fusing lesser levels after anterior surgery, there was comparatively greater disc angulation of 3.84 degrees after anterior surgeries as compared to 1.78 degrees after posterior spinal fusion.[30]

Proximal junctional kyphosis (PJK) is more commonly reported in posterior correction surgeries in AIS.[56],[57],[58] The rate of PJK in anterior surgery in 5C curves was reported to be lower than posterior surgery by Li et al.[59] in their long-term follow-up of 5 years. They reported an incidence of PJK in one case among 40 cases of ASF, whereas PJK was noted in five cases of 37 cases in PSF. Hee et al.[60] have reiterated similar findings albeit in a smaller case group and with follow-up of 2 years. In contrast, Geck et al.[61] have reported similar rates of PJK in ASF and PSF in 2 years matched follow-up. However, the radiological incidence of PJK does not correlate with the clinical outcome, which remains stable in most of cases.[62]

Other complications

Recently, shoulder girdle has been recognized as an important determinant for upper limb function. The anterior approach causes a reduction in shoulder strength and forward flexion till 6 months postsurgery but it normalizes at 1 year[63] especially with approaches which access higher levels such as T3–T4, although the range of movement returns to normal at 6 weeks.


  Anterior versus Posterior Surgery Top


Fusion levels

The anterior approach offers the advantage of saving fusion levels in adolescent scoliosis correction compared to posterior surgery. In a multicenter study by O’Donnell et al.[64] for treatment of 5C Lenke curves, an average of one level was saved. Similarly, Dong et al.[65] and Abel et al.[66] reported an average reduction of 2 and 1.3 vertebral levels, respectively, in the fusion length, when compared to posterior surgery, in 5C curves [Figure 3] (Case 2)].
Figure 3 (Case 2): Case example of 13-year-old female with Lenke 5C curve with 62° Cobb’s angle where correction was done via anterior approach showing good correction of deformity and rib hump along with saving of motion segment

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The trend was similar for type 1 Lenke where ASF leads to an average of 7-level fusion compared to an average of 10 for PSF. The least was noted in thoracoscopic anterior spinal surgery, where, on average, only six levels were fused as described by Newton et al.[55 A similar observation that anterior surgery required 2.5 less number of fusion levels was noted by Betz et al.[67] and Lonner et al.[32] in type 1 curves. On the contrary, Potter et al.[68] found only 1.2 level fusion level difference in anterior and posterior surgery when all pedicle screw construct was used. Thus, anterior surgery leads to saving of fusion levels compared to posterior surgery. Moreover spontaneous correction of the proximal thoracic curve may be better following anterior fusion.[69]

Access to the curve

There is limitation to access the levels of the curve in anterior approaches. The proximal access and instrumentation to T3 and above is difficult and similarly the distal most vertebrae easily accessed and instrumented is L4. In posterior approach easy access is from occiput to sacrum and pelvis by a single posterior incision. For accessing thoracolumbar region in anterior surgery, the access is by cutting the diaphragm and joining the exposed thoracic and the retroperitoneal cavity.

Selective thoracic/lumbar/thoracolumbar fusion

In the meta-analysis by Lin et al.,[16] the degree of curve correction in coronal and sagittal plane was similar in ASF and PSF. The spontaneous curve correction was satisfactory in both anterior and posterior approaches in both thoracic and lumbar curves as outlined by Lin et al.[16] and Franic et al.[70]

Kyphosis increases in ASF and is not affected in PSF group and helps in correcting hypokyphosis both at the thoracic and thoracolumbar region. In posterior surgery, the lumbar lordosis is better maintained and corrected compared to anterior surgery and aids in improving lumbar sagittal balance. However, the incidence of DJK is more than double in posterior surgery compared to anterior surgery in selective thoracic fusion group as reported by Lowe et al.[28]

Overall sagittal balance as read by C7 plumb line was better restored and maintained by anterior selective thoracic fusion compared to posterior surgery, whereas the coronal balance was reestablished in both anterior and posterior approaches.[16] However, they further stated that in selective lumbar fusion (SLF) no significant changes in final sagittal balance were observed in the posterior or anterior group.

Vavruch et al.,[17] in their comparative study on Lenke type 1 curves found that, correction of compensatory lumbar curve, thoracic kyphosis, lumbar lordosis and postoperative alignment restoration was similar between the two approaches at 2 years followup. However, better correction of main thoracic curve was achieved with posterior approach and lesser levels were fused by anterior approach.


  Recent Advances Top


Thoracoscopic anterior scoliosis correction

Thoracoscopic surgery has the benefit of being minimally invasive with small incisions and blood loss while giving outcomes almost equal to open approach with the advantages of any minimal access procedure viz. less morbidity, less postoperative analgesic requirement, and early return to work.[39],[71-73] The common indications are the same as for open anterior approach viz. limited release and discectomy to loosen the apex in patients with reduced curve flexibility and in patients with large magnitude rounded curves or curves with thoracic hyperkyphosis. It is also used for anterior curve correction and instrumentation in patients with a moderate degree of flexible Lenke type 1 scoliosis.

Patients undergoing thoracoscopic surgery for scoliosis correction in one study have reported better self-image and mental health scores on SRS-22 compared to patients undergoing posterior approach despite no significant difference in curve correction. The possible reasons attributed could be the low visibility of thoracoscopic scars compared to midline posterior scars along with inherent prejudice of patients towards minimally invasive surgery. However, these conclusions are based on few individual studies which have recommended further studies with a larger sample size to arrive at definitive outcome.[32],[74],[75]

In a recent meta-analysis by Pedhaye et al.,[76] thoracoscopic surgery was found to be a viable alternative to conventional open technique notwithstanding steep learning curve and longer operative duration and initial pulmonary complications.

Vertebral body tethering

This is a motion-preserving surgery for early adolescent idiopathic scoliosis, which still has growth potential left in them. Typically, immature curves within the range of 35°–70° in the thoracic or lumbar spine can be treated with this technique.[77],[78] Also, the patients who are candidates for brace therapy, but refuse it or are noncompliant, are likely to benefit from vertebral body tethering (VBT). The titanium screws are placed preferable via thoracoscopic technique and tether made of a white polyethylene terephthalate flexible cord is negotiated through the screw heads. The cord is pulled to provide compression on the convex side to achieve correction and then it is fixed with nuts.

The Vertebral body stapling (VBS) provides restrained but flexible spine which still has growth potential and mobility.[79],[80],[81] It obliviates the need for future multiple surgeries or distraction as required in conventional or MAGEC growth rod systems. The long-term clinical results of this technique are still awaited, although it seems promising in medium-term studies in carefully selected cases. The complications usually include overcorrection and tether breakage.


  Current Status of Anterior Surgery Top


The anterior approach is essential in the armamentarium for spine deformity management and can be used for treating Lenke type 1 and type 5/6 curves with similar results to posterior surgery with potential advantage to save fusion levels [Table 1]. This technique in the author’s opinion is superior, especially in Lenke 5 curves, where it saves the motion segment and provides a satisfactory overall correction. In addition to this, anterior approach can be an essential adjunct to posterior surgery in severe curves where there is significant stiffness. It can make the curve supple, reduce the operative time, and obliviate the need for aggressive osteotomies for these types of curves.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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