Spine Deformity 1 (2013) 447e451www.spine-deformity.org

Should Shoulder Balance Determine Proximal Fusion Levels in PatientsWith Lenke 5 Curves?

Burt Yaszay, MD*, Tracey P. Bastrom, MA, Peter O. Newton, MD,Harms Study Group

Department of Orthopedics, Rady Children’s Hospital, 3030 Children’s Way, Suite 410, San Diego, CA 92123, USA

Received 11 October 2012; revised 7 August 2013; accepted 19 August 2013

Abstract

Study Design: Multicenter review of prospectively collected data.Objectives: To identify the frequency of an opposite high shoulder in Lenke 5 patients and evaluate factors that influence preoperative andpostoperative shoulder balance.Summary of Background Data: A high left shoulder is an indication to extend the fusion proximally in a right thoracic curve. Some applya similar rule to high right shoulders in patients with left thoracolumbar/lumbar curves.Methods: A prospective multicenter adolescent idiopathic scoliosis database was queried for patients with Lenke 5 curves and minimum 2-year follow-up. Preoperative and postoperative shoulder height differences were recorded and categorized by the opposite shoulder (rightshoulder in a left thoracolumbar curve) as high (greater than 1 cm), level (0e1 cm), and low (less than 1 cm). Preoperative and post-operative radiographic variables and Scoliosis Research Society questionnaire scores were evaluated.Results: Of the 104 patients identified, 37% had level shoulders and 53% had a high opposite shoulder. A high shoulder was associatedwith a greater mean thoracic Cobb (31�) than a level (24�) or low shoulder (26�) (p 5 .008). Postoperatively, 64% of patients had levelshoulders (less than 1 cm); 93% had a shoulder difference less than 2 cm. Preoperative lumbar Cobb was a significant predictor ofpostoperative shoulder height (p 5 .051). A slightly greater proportion of preoperative high shoulders (36%) had a nonselective fusion thanthose with level (27%) or low (9%) shoulders. Among the 29 patients with a preoperative moderate or significant high shoulder (greater than2 cm), 3 continued to have a high shoulder greater than 2 cm that was not influenced by fusing the thoracic spine. There were no significantdifferences in preoperative or postoperative Scoliosis Research Society scores based on shoulder height (p O .05).Conclusions: Half of all Lenke 5 curves have a high opposite shoulder that is influenced by the size of the compensatory thoracic curve.Postoperatively, most patients had level shoulders. Inclusion of the thoracic spine did not influence postoperative shoulder balance.� 2013 Scoliosis Research Society.

Keywords: Shoulder balance; Adolescent idiopathic scoliosis; Thoracolumbar/lumbar curves; Nonselective fusion

Author disclosures: BY (grant to the Setting Scoliosis Straight Founda-

tion from DePuy Spine, Inc.; consultancy for K2M, Synthes, Ellipse, Med-

tronic; grants from KCI, DePuy, K2M, Ellipse; payment for lectures

including service on speakers bureaus from DePuy Spine, K2M; royalties

from Orthopediatrics); TPB (grant to the Setting Scoliosis Straight Founda-

tion from DePuy Spine, Inc.); PON (grant to the Setting Scoliosis Straight

Foundation from DePuy Spine, Inc.; consulting fee from DePuy Synthes

Spine; support for travel to meetings for the study or other purposes from

DePuy Synthes Spine; board membership with POSNA, Harms Study Group

Foundation, SRS, Children’s Specialist Foundation; consultancy for DePuy

Spine, Stanford University; employment with Children’s Specialist of San

Diego; expert testimony for NorCal, law firm Carroll, Kelly, Trotter, Fran-

zen, & McKenna, law firm Smith, Haughey, Rice, & Roegge; grants from

NIH, OREF, POSNA, SRS, Harms Study Group Foundation, DePuy Synthes

Spine, Axial Biotech, Biospace/Med/EOS Imaging; payment for lectures

including service on speakers bureaus from DePuy Spine; patents from DeP-

uy Synthes Spine; royalties from DePuy Synthes Spine, Thieme Publishing;

payment for the development of educational presentations from DePuy Syn-

thes Spine; stock/stock options from Nuvasive); Harms Study Group (grant

to the Setting Scoliosis Straight Foundation from DePuy Spine, Inc.)

This study was supported in part by a grant to the Setting Scoliosis

Straight Foundation from DePuy Spine, Inc.

*Corresponding author. Department of Orthopedics, Rady Children’s

Hospital, 3030 Children’s Way, Suite 410, San Diego, CA 92123, USA.

Tel.: (858) 966-6789; fax: (858) 966-7494.

E-mail address: byaszay@rchsd.org (B. Yaszay).

2212-134X/$ - see front matter � 2013 Scoliosis Research Society.

http://dx.doi.org/10.1016/j.jspd.2013.08.003

448 B. Yaszay et al. / Spine Deformity 1 (2013) 447e451

Introduction

The goal of the surgical treatment of adolescent idio-pathic scoliosis (AIS) is to obtain a stable arthrodesiswhile maximizing deformity correction, maintaining2-dimensional balance, and minimizing fusion levels.Multiple recommendations from King et al. [1] in 1983 toLenke et al. [2] in 2001 have been developed to assist inselecting the curves as well as the vertebral levels to includein the fusion, in some cases. Distally, surgeons focus onselecting levels that optimally treat the scoliosis whilemaximizing lumbar flexibility. Proximally, the primaryconcern is to select the level that will achieve the desireddeformity correction and result in balanced shoulders [3].

The Lenke classification recommended the inclusion ofthe proximal thoracic curve within the region of fusionwhen it was found to be structural [2,4]. Correcting a mainthoracic curve and leaving a structural upper thoracic curveuntreated risks postoperative spinal deformity that couldresult in clinical shoulder asymmetry. Others have sug-gested instrumenting the upper thoracic curved based on T1tilt, the clavicular angle, or the patient’s preoperativeshoulder balance [5-11]. For example, a high left shoulderis an indication to extend the fusion proximally in a rightthoracic curve. In all of these instances, the recommenda-tions have been for the treatment of a primary mainthoracic curve.

The authors are unaware of any study that has focused onthe relationship between shoulder balance and the treatmentof a thoracolumbar/lumbar (TL/L) curve. Should a high rightshoulder be an indication to similarly extend the fusionproximally in a primary left thoracolumbar/lumbar curve?The purposes of this study were to identify the frequency ofan opposite side (relative to the TL/L curve direction) highshoulder in Lenke 5 patients, and to evaluate the factorsthat influence shoulder balance both preoperatively andpostoperatively.

Methods

A prospective multicenter AIS database was queried toidentify patients with Lenke 5 (primary thoracolumbar)curves. All patients had undergone surgical correction witheither an anterior or posterior approach and were 2 years outfrom surgery. Preoperative and 2-year postoperativeshoulder height data were obtained. Shoulder height differ-ences were measured on the posteroanterior radiographs asthe distance in millimeters between a horizontal referenceline of the acromial clavicular joint of the superior shoulderand a similar horizontal reference line of the acromialclavicular joint of the inferior shoulder [12,13]. Bothpreoperative and postoperative shoulder height data werethen categorized for each patient as opposite shoulder high(right shoulder high in a left thoracolumbar curve), levelshoulders (difference of within 0.9 mm), or oppositeshoulder low (right shoulder low in left thoracolumbar

curve). The high and low shoulders were further classified asslight (1e2 cm), moderate (2e3 cm), or significant (greaterthan 3 cm), as per Kuklo et al. [6].

The magnitudes of preoperative coronal Cobb angles(upper thoracic, thoracic, and lumbar) and their respectiveflexibilities (expressed as a percentage) were measured.Surgical approach (anterior or posterior) and the extent offusion were recorded (selective fusion of only the thor-acolumbar curve or nonselective fusion of both the primarythoracolumbar and nonstructural thoracic curve). The 2-yearpostoperative coronal Cobb angles were measured andpercent corrections were calculated.

Frequencies and percentages of preoperative shoulderheight groups were calculated (opposite high, level, oropposite low). Analysis of variance with Bonferroni post hoccomparisons was used to compare the preoperative coronalCobb angles and flexibilities among these 3 groups to assesswhether the preoperative characteristics were significantlydifferent. Chi-square analysis was used to determinewhether the distribution of selective versus nonselectivefusion was significantly different among the 3 preoperativeshoulder height groups. Frequencies and percentages ofpostoperative shoulder height status were also calculated.Univariate and subsequent multivariate logistic regressionwas used to identify factors predictive of a high post-operative shoulder.

Preoperative and postoperative Scoliosis Research Societyscores were evaluated based on shoulder height differenceusing multivariate analysis of variance. All analyses wereperformed using SPSS version 12 (SPSS, Inc., Chicago, IL)and alpha was set at p ! .05 to declare significance.

Results

A total of 104 Lenke 5 curves surgically treated withinstrumentation and fusion for correction of scoliosisdeformity with 2-year follow-up were identified. Theaverage age of the cohort was 15 � 2 years (range, 11e20years). The gender was predominately female, with 85females (82%) and 19 males (18%). A total of 72 patients(69%) underwent a selective thoracolumbar fusion, whereas32 patients (31%) underwent fusion of both the primarythoracolumbar curve and the nonstructural thoracic curve.Forty-eight patients (46%) were treated with posteriorinstrumentation and fusion and 56 (54%) were treated withanterior instrumentation and fusion.

Preoperatively, approximately half of the patients hada high opposite shoulder (55 of 104; 53%) (Figure), fol-lowed by 38 patients (36.5%) with level shoulders and 11(10.5%) with a low opposite shoulder. A high shoulder wasassociated with a greater mean thoracic Cobb (30.9�) thanthose with a level or low shoulder (23.7� and 25.6�,respectively; p 5 .008) (Table 1). No other preoperativeradiographic differences were identified. A slightly greaterproportion of the preoperative high shoulders (36%) hada nonselective fusion than those with a level (27%) or low

Table 3

Preoperative Scoliosis Research Society scores in relation to preoperative

opposite shoulder height.

Preoperative

opposite shoulder

Mean p Value

Pain High 4.2�0.7 .567

Level 4.0�0.8

Low 4.3�0.5

Self-image High 3.5�0.7 .124

Level 3.6�0.5

Low 3.9�0.6

General function High 4.5�0.6 .321

Table 1

Preoperative radiographic data by shoulder level group.

Opposite high Level Opposite low p

Upper thoracic Cobb ( �) 9.2�7.2 7.8�6.6 10.5�6.1 .42

Thoracic Cobb ( �) 30.9�12.7 23.7�8.4 25.6�9.4 .008

Lumbar Cobb ( �) 48.2�9.4 46.5�7.5 45.5�8.9 .51

Upper thoracic flexibility (%) 74.4�28.4 76.3�36.7 65.2�30.3 .67

Thoracic flexibility (%) 61.6�17.3 59.0�23.4 45�19 .09

Lumbar flexibility (%) 63.8�17.7 64.6�20.1 64.7�16.4 .98

449B. Yaszay et al. / Spine Deformity 1 (2013) 447e451

(9%) shoulder (p 5 .19). Although shoulder imbalance wasnot significantly associated with a nonselective fusion, thenonselectively fused patients had larger thoracic Cobb angles(35.2� vs. 24.4�; p! .001) and thoracic rotation as measuredby scoliometer (10.4� vs. 5.5�; p! .001), and trended towardhaving less T10eL2 kyphosis (1.5� vs. 5.8�; p 5 .07) anda smaller TH/L:TH curve ratio (1.6 vs. 2.3; p 5 .09) thanselectively fused patients.

Postoperatively, 97 of the patients (93%) had a shoulderheight difference of less than 2 cm in either direction. Atotal of 67 of these patients (64%) had level shoulders(within 0.9 cm) and 30 (29%) had a slight shoulder heightdifference (1e2 cm). Only 7 patients (7%) had a moderateshoulder height difference (2e3 cm) postoperatively and nopatients had a significant (greater than 3 cm) shoulderheight difference. A logistic regression analysis was per-formed to identify factors predictive of having a post-operative shoulder height difference (1e3 cm). Of thevariables analyzed in the univariate regression analyses(preoperative coronal Cobb angles, flexibilities, post-operative percent correction of all 3 Cobb angles, preop-erative magnitude of shoulder height difference, type offusion, and approach), only preoperative shoulder heightdifference (p 5 .03), preoperative thoracic curve (p 5 .05),and preoperative lumbar curve (p 5 .01) met inclusionrequirements for entry into multivariate regression analysis.These 3 variables were then entered into a multivariatelogistic regression, the results of which are shown inTable 2. Only the size of the preoperative lumbar Cobbdemonstrated a significant association (odds ratio, 1.06;95% confidence interval, 1.00e1.12 95; p 5 .051). Anassociation that approached significance was observed withmagnitude of preoperative shoulder height difference (oddsratio, 1.44, 95% confidence interval, 0.95e2.2 95; p 5.083). Preoperative thoracic Cobb was not a significantpredictor within the multivariate analysis (p O .10).

Table 2

Variables that met inclusion into the multivariate regression as potential

predictors of postoperative shoulder height difference.

p Value Odds ratio

Preoperative magnitude of shoulder

height difference, cm

.08 1.44

Preoperative thoracic Cobb ( �) .61 1.01

Preoperative lumbar Cobb ( �) .05 1.06

Among the 29 patients with a preoperative moderate orsignificant high shoulder (greater than 2 cm), only 3 continuedto have a high shoulder greater than 2 cm. Two of thesepatients were treated with a selective fusion of the primarythoracolumbar curve and 1 was treated with fusion of both thethoracolumbar curve and the nonstructural thoracic curve.There were no significant differences preoperatively or post-operatively in Scoliosis Research Society scores based onshoulder height differences (p O .05) (Tables 3 and 4).

Discussion

Decision making for the proximal extent of a fusion isinfluenced by the surgeon’s concern for postoperativeshoulder balance. For a main thoracic curve, multiple pre-operative factors have been evaluated to help assist thesurgeon determine the need to fuse a proximal thoracic curve.The Lenke classification recommended fusing a proximalthoracic curve based on whether it was considered ‘‘struc-tural’’ (greater than 25�) on side-bending radiographs orassociated with proximal kyphosis [2]. This was supported byCil et al. [4], who specifically evaluated the effect of this ruleon shoulder balance. They suggested that proximal curves thatwere below the threshold for being structural could be safely

Level 4.4�0.6

Low 4.7�0.3

Mental health High 4.1�0.7 .456

Level 4.0�0.5

Low 4.2�0.4

Satisfaction High 3.6�1.3 .539

Level 3.8�0.6

Low 3.4�0.9

Total High 4.0�0.4 .170

Level 4.0�0.4

Low 4.3�0.3

Table 4

Postoperative Scoliosis Research Society scores as a function of 2-year

postoperative shoulder difference severity.

Severity of

postoperative

shoulder height

difference

Mean�standard

deviation

p

Pain Level 4.5�0.6 .979

Moderate 4.5�0.5

Slight 4.4�0.7

Self-image Level 4.4�0.5 .926

Moderate 4.3�0.6

Slight 4.4�0.6

General function Level 4.7�0.4 .528

Moderate 4.6�0.5

Slight 4.6�0.5

Mental health Level 4.2�0.7 .308

Moderate 3.9�0.6

Slight 4.3�0.7

Satisfaction Level 4.4�0.7 .467

Moderate 4.8�0.4

Slight 4.5�0.8

Total Level 4.4�0.4 .749

Moderate 4.3�0.3

Slight 4.4�0.6

450 B. Yaszay et al. / Spine Deformity 1 (2013) 447e451

left un-instrumented and had similar postoperative shoulderbalance as those that had the upper thoracic curve fused.

Others have suggested that preoperative shoulder balanceis the most important predictor of postoperative shoulderbalance. Kuklo et al. [6] used the clavicle angle (intersectionof a horizontal line and a line connecting the 2 highest pointsof each line) on the standing posteroanterior radiograph toassess the patient’s shoulders. They recommended extendingthe fusion proximally to T2 or T3 if the contralateralshoulder was high. Interestingly, they found that neither theproximal thoracic nor the side-bending proximal thoracicCobb was the best predictor of postoperative shoulderbalance. Suk et al. [8] recommended treating the proximalcurve if the Cobb was greater than 25� and if the patient had

Fig. Lenke 5 curve with high opposite shoulder preoperatively, treated w

a preoperative level or elevated left shoulder. Failure toinclude the curve would result in postoperative shoulderasymmetry, especially with the significant correction thatcan occur with segmental instrumentation.

Similar to main thoracic curves, patients with thor-acolumbar/lumbar curves can have significant preoperativeshoulder asymmetry. In the current series, half of thepatients had a high opposite shoulder; nearly half of thisgroup had greater than 2 cm of shoulder discrepancy. Of theremaining patients, most had levels shoulders and only 10%had low opposite shoulders. As expected, those with a highopposite shoulder had a significantly greater preoperativethoracic curve magnitude.

Ultimately, the question is whether there is a risk forshoulder asymmetry after the treatment of Lenke 5 curves.Whereas a slightly greater proportion of the preoperativehigh opposite shoulders (36%) had their fusion extendedacross their thoracic curve compared with those withbalanced or low opposite shoulders, this was not significant.Therefore, it was unclear whether this was a considerationduring the surgeon’s surgical decision making, and it isconsidered a limitation of the study. However, the authorsfound that patients with a larger thoracic deformitypreoperatively, which was associated with a high oppositeshoulder, were more likely to be fused nonselectively.Another limitation was that the authors did not knowwhether surgeons altered their surgical technique in eithera selective or nonselective fusion to attempt to balancethe shoulders.

Postoperatively, most patients had balanced shoulders.Whether the patient had the thoracic curve included in thefusion of the thoracolumbar/lumbar curve does not appearto influence postoperative shoulder balance. Unlike preop-erative shoulder asymmetry, the magnitude of the thoraciccurve did not affect postoperative shoulder height differ-ence. Only the preoperative lumbar Cobb and possibly thepreoperative shoulder height difference were associated

ith selective posterior fusion and resultant leveling of the shoulder.

451B. Yaszay et al. / Spine Deformity 1 (2013) 447e451

with a postoperative shoulder height difference. Why thepreoperative lumbar curve magnitude and not the size ofthe compensatory thoracic curve affected postoperativeshoulder height is not clear.

While shoulder balance does not appear to be animportant criterion for extending the fusion across thethoracic curve, there are other factors to consider whenperforming a selective thoracolumbar/lumbar fusion.According to the Lenke classification, if a thoracic curvedoes not bend less than 25� or there is kyphosis greater than20� at the thoracolumbar junction, a nonselective fusionshould be performed because both curves are consideredstructural [2,14,15]. Leaving a structural curve untreatedrisks further curve progression and truncal imbalance.Sanders et al. [16] attempted to determine which majorthoracolumbar/lumbar curves could be treated througha selective anterior approach. They defined failure asprogression of the thoracic curve requiring a second fusionprocedure. Their predictors for successful selective fusionincluded skeletal maturity, a thoracolumbar/thoracic Cobbratio less than 1.25, and a preoperative thoracic best bend ofless than 20� to be good predictors of success. Althoughthese recommendations have not been validated fora posterior approach, recent studies have suggested similarresults between the 2 approaches [17-19].

This study evaluated the relationship betweenshoulder balance and the treatment of a thoracolumbar/lum-bar curve. Half of all Lenke 5 curves have a high opposite-shoulder that was influenced by the size of the compensatorythoracic curve. At 2 years postoperatively, most patients hadlevel shoulders. Inclusion of the thoracic spine (nonselectivefusion) did not appear to influence postoperative shoulderbalance even among those with moderate or significant highopposite shoulders preoperatively.

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