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

Spine Deformity 1 (2013) 447e451 www.spine-deformity.org

Should Shoulder Balance Determine Proximal Fusion Levels in Patients With 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 and postoperative shoulder balance. Summary of Background Data: A high left shoulder is an indication to extend the fusion proximally in a right thoracic curve. Some apply a 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 2year follow-up. Preoperative and postoperative shoulder height differences were recorded and categorized by the opposite shoulder (right shoulder in a left thoracolumbar curve) as high (greater than 1 cm), level (0e1 cm), and low (less than 1 cm). Preoperative and postoperative 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 associated with a greater mean thoracic Cobb (31 ) than a level (24 ) or low shoulder (26 ) (p 5 .008). Postoperatively, 64% of patients had level shoulders (less than 1 cm); 93% had a shoulder difference less than 2 cm. Preoperative lumbar Cobb was a significant predictor of postoperative shoulder height (p 5 .051). A slightly greater proportion of preoperative high shoulders (36%) had a nonselective fusion than those with level (27%) or low (9%) shoulders. Among the 29 patients with a preoperative moderate or significant high shoulder (greater than 2 cm), 3 continued to have a high shoulder greater than 2 cm that was not influenced by fusing the thoracic spine. There were no significant differences 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. Ó 2013 Scoliosis Research Society. Keywords: Shoulder balance; Adolescent idiopathic scoliosis; Thoracolumbar/lumbar curves; Nonselective fusion

Author disclosures: BY (grant to the Setting Scoliosis Straight Foundation from DePuy Spine, Inc.; consultancy for K2M, Synthes, Ellipse, Medtronic; 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 Foundation 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, Franzen, & McKenna, law firm Smith, Haughey, Rice, & Roegge; grants from 2212-134X/$ - see front matter Ó 2013 Scoliosis Research Society. http://dx.doi.org/10.1016/j.jspd.2013.08.003

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 DePuy Synthes Spine; royalties from DePuy Synthes Spine, Thieme Publishing; payment for the development of educational presentations from DePuy Synthes 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: [email protected] (B. Yaszay).

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Introduction The goal of the surgical treatment of adolescent idiopathic scoliosis (AIS) is to obtain a stable arthrodesis while maximizing deformity correction, maintaining 2-dimensional balance, and minimizing fusion levels. Multiple recommendations from King et al. [1] in 1983 to Lenke et al. [2] in 2001 have been developed to assist in selecting the curves as well as the vertebral levels to include in the fusion, in some cases. Distally, surgeons focus on selecting levels that optimally treat the scoliosis while maximizing lumbar flexibility. Proximally, the primary concern is to select the level that will achieve the desired deformity correction and result in balanced shoulders [3]. The Lenke classification recommended the inclusion of the proximal thoracic curve within the region of fusion when it was found to be structural [2,4]. Correcting a main thoracic curve and leaving a structural upper thoracic curve untreated risks postoperative spinal deformity that could result in clinical shoulder asymmetry. Others have suggested instrumenting the upper thoracic curved based on T1 tilt, the clavicular angle, or the patient’s preoperative shoulder balance [5-11]. For example, a high left shoulder is an indication to extend the fusion proximally in a right thoracic curve. In all of these instances, the recommendations have been for the treatment of a primary main thoracic curve. The authors are unaware of any study that has focused on the relationship between shoulder balance and the treatment of a thoracolumbar/lumbar (TL/L) curve. Should a high right shoulder be an indication to similarly extend the fusion proximally in a primary left thoracolumbar/lumbar curve? The purposes of this study were to identify the frequency of an opposite side (relative to the TL/L curve direction) high shoulder in Lenke 5 patients, and to evaluate the factors that influence shoulder balance both preoperatively and postoperatively.

Methods A prospective multicenter AIS database was queried to identify patients with Lenke 5 (primary thoracolumbar) curves. All patients had undergone surgical correction with either an anterior or posterior approach and were 2 years out from surgery. Preoperative and 2-year postoperative shoulder height data were obtained. Shoulder height differences were measured on the posteroanterior radiographs as the distance in millimeters between a horizontal reference line of the acromial clavicular joint of the superior shoulder and a similar horizontal reference line of the acromial clavicular joint of the inferior shoulder [12,13]. Both preoperative and postoperative shoulder height data were then categorized for each patient as opposite shoulder high (right shoulder high in a left thoracolumbar curve), level shoulders (difference of within 0.9 mm), or opposite shoulder low (right shoulder low in left thoracolumbar

curve). The high and low shoulders were further classified as slight (1e2 cm), moderate (2e3 cm), or significant (greater than 3 cm), as per Kuklo et al. [6]. The magnitudes of preoperative coronal Cobb angles (upper thoracic, thoracic, and lumbar) and their respective flexibilities (expressed as a percentage) were measured. Surgical approach (anterior or posterior) and the extent of fusion were recorded (selective fusion of only the thoracolumbar curve or nonselective fusion of both the primary thoracolumbar and nonstructural thoracic curve). The 2-year postoperative coronal Cobb angles were measured and percent corrections were calculated. Frequencies and percentages of preoperative shoulder height groups were calculated (opposite high, level, or opposite low). Analysis of variance with Bonferroni post hoc comparisons was used to compare the preoperative coronal Cobb angles and flexibilities among these 3 groups to assess whether the preoperative characteristics were significantly different. Chi-square analysis was used to determine whether the distribution of selective versus nonselective fusion was significantly different among the 3 preoperative shoulder height groups. Frequencies and percentages of postoperative shoulder height status were also calculated. Univariate and subsequent multivariate logistic regression was used to identify factors predictive of a high postoperative shoulder. Preoperative and postoperative Scoliosis Research Society scores were evaluated based on shoulder height difference using multivariate analysis of variance. All analyses were performed 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 with instrumentation and fusion for correction of scoliosis deformity with 2-year follow-up were identified. The average age of the cohort was 15  2 years (range, 11e20 years). The gender was predominately female, with 85 females (82%) and 19 males (18%). A total of 72 patients (69%) underwent a selective thoracolumbar fusion, whereas 32 patients (31%) underwent fusion of both the primary thoracolumbar curve and the nonstructural thoracic curve. Forty-eight patients (46%) were treated with posterior instrumentation and fusion and 56 (54%) were treated with anterior instrumentation and fusion. Preoperatively, approximately half of the patients had a high opposite shoulder (55 of 104; 53%) (Figure), followed by 38 patients (36.5%) with level shoulders and 11 (10.5%) with a low opposite shoulder. A high shoulder was associated with a greater mean thoracic Cobb (30.9 ) than those with a level or low shoulder (23.7 and 25.6 , respectively; p 5 .008) (Table 1). No other preoperative radiographic differences were identified. A slightly greater proportion of the preoperative high shoulders (36%) had a nonselective fusion than those with a level (27%) or low

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449

Table 1 Preoperative radiographic data by shoulder level group. 

Upper thoracic Cobb ( ) Thoracic Cobb (  ) Lumbar Cobb (  ) Upper thoracic flexibility (%) Thoracic flexibility (%) Lumbar flexibility (%)

Opposite high

Level

Opposite low

p

9.27.2 30.912.7 48.29.4 74.428.4 61.617.3 63.817.7

7.86.6 23.78.4 46.57.5 76.336.7 59.023.4 64.620.1

10.56.1 25.69.4 45.58.9 65.230.3 4519 64.716.4

.42 .008 .51 .67 .09 .98

(9%) shoulder (p 5 .19). Although shoulder imbalance was not significantly associated with a nonselective fusion, the nonselectively fused patients had larger thoracic Cobb angles (35.2 vs. 24.4 ; p ! .001) and thoracic rotation as measured by scoliometer (10.4 vs. 5.5 ; p ! .001), and trended toward having less T10eL2 kyphosis (1.5 vs. 5.8 ; p 5 .07) and a smaller TH/L:TH curve ratio (1.6 vs. 2.3; p 5 .09) than selectively fused patients. Postoperatively, 97 of the patients (93%) had a shoulder height difference of less than 2 cm in either direction. A total of 67 of these patients (64%) had level shoulders (within 0.9 cm) and 30 (29%) had a slight shoulder height difference (1e2 cm). Only 7 patients (7%) had a moderate shoulder height difference (2e3 cm) postoperatively and no patients had a significant (greater than 3 cm) shoulder height difference. A logistic regression analysis was performed to identify factors predictive of having a postoperative shoulder height difference (1e3 cm). Of the variables analyzed in the univariate regression analyses (preoperative coronal Cobb angles, flexibilities, postoperative percent correction of all 3 Cobb angles, preoperative magnitude of shoulder height difference, type of fusion, and approach), only preoperative shoulder height difference (p 5 .03), preoperative thoracic curve (p 5 .05), and preoperative lumbar curve (p 5 .01) met inclusion requirements for entry into multivariate regression analysis. These 3 variables were then entered into a multivariate logistic regression, the results of which are shown in Table 2. Only the size of the preoperative lumbar Cobb demonstrated a significant association (odds ratio, 1.06; 95% confidence interval, 1.00e1.12 95; p 5 .051). An association that approached significance was observed with magnitude of preoperative shoulder height difference (odds ratio, 1.44, 95% confidence interval, 0.95e2.2 95; p 5 .083). Preoperative thoracic Cobb was not a significant predictor 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.

Preoperative magnitude of shoulder height difference, cm Preoperative thoracic Cobb (  ) Preoperative lumbar Cobb (  )

p Value

Odds ratio

.08

1.44

.61 .05

1.01 1.06

Among the 29 patients with a preoperative moderate or significant high shoulder (greater than 2 cm), only 3 continued to have a high shoulder greater than 2 cm. Two of these patients were treated with a selective fusion of the primary thoracolumbar curve and 1 was treated with fusion of both the thoracolumbar curve and the nonstructural thoracic curve. There were no significant differences preoperatively or postoperatively in Scoliosis Research Society scores based on shoulder height differences (p O .05) (Tables 3 and 4). Discussion Decision making for the proximal extent of a fusion is influenced by the surgeon’s concern for postoperative shoulder balance. For a main thoracic curve, multiple preoperative factors have been evaluated to help assist the surgeon determine the need to fuse a proximal thoracic curve. The Lenke classification recommended fusing a proximal thoracic curve based on whether it was considered ‘‘structural’’ (greater than 25 ) on side-bending radiographs or associated with proximal kyphosis [2]. This was supported by Cil et al. [4], who specifically evaluated the effect of this rule on shoulder balance. They suggested that proximal curves that were below the threshold for being structural could be safely Table 3 Preoperative Scoliosis Research Society scores in relation to preoperative opposite shoulder height.

Pain

Self-image

General function

Mental health

Satisfaction

Total

Preoperative opposite shoulder

Mean

p Value

High Level Low High Level Low High Level Low High Level Low High Level Low High Level Low

4.20.7 4.00.8 4.30.5 3.50.7 3.60.5 3.90.6 4.50.6 4.40.6 4.70.3 4.10.7 4.00.5 4.20.4 3.61.3 3.80.6 3.40.9 4.00.4 4.00.4 4.30.3

.567

.124

.321

.456

.539

.170

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

Table 4 Postoperative Scoliosis Research Society scores as a function of 2-year postoperative shoulder difference severity.

Pain

Self-image

General function

Mental health

Satisfaction

Total

Severity of postoperative shoulder height difference

Meanstandard deviation

p

Level Moderate Slight Level Moderate Slight Level Moderate Slight Level Moderate Slight Level Moderate Slight Level Moderate Slight

4.50.6 4.50.5 4.40.7 4.40.5 4.30.6 4.40.6 4.70.4 4.60.5 4.60.5 4.20.7 3.90.6 4.30.7 4.40.7 4.80.4 4.50.8 4.40.4 4.30.3 4.40.6

.979

.926

.528

.308

.467

.749

left un-instrumented and had similar postoperative shoulder balance as those that had the upper thoracic curve fused. Others have suggested that preoperative shoulder balance is the most important predictor of postoperative shoulder balance. Kuklo et al. [6] used the clavicle angle (intersection of a horizontal line and a line connecting the 2 highest points of each line) on the standing posteroanterior radiograph to assess the patient’s shoulders. They recommended extending the fusion proximally to T2 or T3 if the contralateral shoulder was high. Interestingly, they found that neither the proximal thoracic nor the side-bending proximal thoracic Cobb was the best predictor of postoperative shoulder balance. Suk et al. [8] recommended treating the proximal curve if the Cobb was greater than 25 and if the patient had

a preoperative level or elevated left shoulder. Failure to include the curve would result in postoperative shoulder asymmetry, especially with the significant correction that can occur with segmental instrumentation. Similar to main thoracic curves, patients with thoracolumbar/lumbar curves can have significant preoperative shoulder asymmetry. In the current series, half of the patients had a high opposite shoulder; nearly half of this group had greater than 2 cm of shoulder discrepancy. Of the remaining patients, most had levels shoulders and only 10% had low opposite shoulders. As expected, those with a high opposite shoulder had a significantly greater preoperative thoracic curve magnitude. Ultimately, the question is whether there is a risk for shoulder asymmetry after the treatment of Lenke 5 curves. Whereas a slightly greater proportion of the preoperative high opposite shoulders (36%) had their fusion extended across their thoracic curve compared with those with balanced or low opposite shoulders, this was not significant. Therefore, it was unclear whether this was a consideration during the surgeon’s surgical decision making, and it is considered a limitation of the study. However, the authors found that patients with a larger thoracic deformity preoperatively, which was associated with a high opposite shoulder, were more likely to be fused nonselectively. Another limitation was that the authors did not know whether surgeons altered their surgical technique in either a selective or nonselective fusion to attempt to balance the shoulders. Postoperatively, most patients had balanced shoulders. Whether the patient had the thoracic curve included in the fusion of the thoracolumbar/lumbar curve does not appear to influence postoperative shoulder balance. Unlike preoperative shoulder asymmetry, the magnitude of the thoracic curve did not affect postoperative shoulder height difference. Only the preoperative lumbar Cobb and possibly the preoperative shoulder height difference were associated

Fig. Lenke 5 curve with high opposite shoulder preoperatively, treated with selective posterior fusion and resultant leveling of the shoulder.

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with a postoperative shoulder height difference. Why the preoperative lumbar curve magnitude and not the size of the compensatory thoracic curve affected postoperative shoulder height is not clear. While shoulder balance does not appear to be an important criterion for extending the fusion across the thoracic curve, there are other factors to consider when performing a selective thoracolumbar/lumbar fusion. According to the Lenke classification, if a thoracic curve does not bend less than 25 or there is kyphosis greater than 20 at the thoracolumbar junction, a nonselective fusion should be performed because both curves are considered structural [2,14,15]. Leaving a structural curve untreated risks further curve progression and truncal imbalance. Sanders et al. [16] attempted to determine which major thoracolumbar/lumbar curves could be treated through a selective anterior approach. They defined failure as progression of the thoracic curve requiring a second fusion procedure. Their predictors for successful selective fusion included skeletal maturity, a thoracolumbar/thoracic Cobb ratio less than 1.25, and a preoperative thoracic best bend of less than 20 to be good predictors of success. Although these recommendations have not been validated for a posterior approach, recent studies have suggested similar results between the 2 approaches [17-19]. This study evaluated the relationship between shoulder balance and the treatment of a thoracolumbar/lumbar curve. Half of all Lenke 5 curves have a high oppositeshoulder that was influenced by the size of the compensatory thoracic curve. At 2 years postoperatively, most patients had level shoulders. Inclusion of the thoracic spine (nonselective fusion) did not appear to influence postoperative shoulder balance even among those with moderate or significant high opposite shoulders preoperatively. References [1] King HA, Moe JH, Bradford DS, Winter RB. The selection of fusion levels in thoracic idiopathic scoliosis. J Bone Joint Surg Am 1983;65: 1302e13. [2] Lenke LG, Betz RR, Harms J, et al. Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am 2001;83:1169e81. [3] Maurice B, Jean-Marie G, Jean-Michel T. Taking the shoulders and pelvis into account in the preoperative classification of idiopathic scoliosis in adolescents and young adults (a constructive critique of King’s and Lenke’s systems of classification). Eur Spine J 2011;20:1780e7. [4] Cil A, Pekmezci M, Yazici M, et al. The validity of Lenke criteria for defining structural proximal thoracic curves in patients with adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2005;30:2550e5.

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[5] Ilharreborde B, Even J, Lefevre Y, et al. How to determine the upper level of instrumentation in Lenke types 1 and 2 adolescent idiopathic scoliosis: a prospective study of 132 patients. J Pediatr Orthop 2008;28:733e9. [6] Kuklo TR, Lenke LG, Graham EJ, et al. Correlation of radiographic, clinical, and patient assessment of shoulder balance following fusion versus nonfusion of the proximal thoracic curve in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2002;27: 2013e20. [7] Li M, Gu S, Ni J, et al. Shoulder balance after surgery in patients with Lenke Type 2 scoliosis corrected with the segmental pedicle screw technique. J Neurosurg Spine 2009;10:214e9. [8] Suk SI, Kim WJ, Lee CS, et al. Indications of proximal thoracic curve fusion in thoracic adolescent idiopathic scoliosis: recognition and treatment of double thoracic curve pattern in adolescent idiopathic scoliosis treated with segmental instrumentation. Spine (Phila Pa 1976) 2000;25:2342e9. [9] Qiu XS, Ma WW, Li WG, et al. Discrepancy between radiographic shoulder balance and cosmetic shoulder balance in adolescent idiopathic scoliosis patients with double thoracic curve. Eur Spine J 2009;18:45e51. [10] Lee CS, Chung SS, Shin SK, et al. Changes of upper thoracic curve and shoulder balance in thoracic adolescent idiopathic scoliosis treated by anterior selective thoracic fusion using VATS. J Spinal Disord Tech 2011;24:462e8. [11] Smyrnis PN, Sekouris N, Papadopoulos G. Surgical assessment of the proximal thoracic curve in adolescent idiopathic scoliosis. Eur Spine J 2009;18:522e30. [12] O’Brien MF, Kuklo TR, Blanke KM, Lenke LG. Spinal Deformity Study Group Radiographic Measurement Manual. Memphis, TN: Medtronic Sofamor Danek USA, Inc. 2005. [13] Dang NR, Moreau MJ, Hill DL, et al. Intra-observer reproducibility and interobserver reliability of the radiographic parameters in the Spinal Deformity Study Group’s AIS Radiographic Measurement Manual. Spine (Phila Pa 1976) 2005;30:1064e9. [14] Lenke LG, Edwards II CC, Bridwell KH. The Lenke classification of adolescent idiopathic scoliosis: how it organizes curve patterns as a template to perform selective fusions of the spine. Spine (Phila Pa 1976) 2003;28:S199e207. [15] Puno RM, An KC, Puno RL, et al. Treatment recommendations for idiopathic scoliosis: an assessment of the Lenke classification. Spine (Phila Pa 1976) 2003;28:2102e14; discussion 2114e5. [16] Sanders AE, Baumann R, Brown H, et al. Selective anterior fusion of thoracolumbar/lumbar curves in adolescents: when can the associated thoracic curve be left unfused? Spine (Phila Pa 1976) 2003;28: 706e13; discussion 714. [17] Li M, Ni J, Fang X, et al. Comparison of selective anterior versus posterior screw instrumentation in Lenke5C adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2009;34:1162e6. [18] Hee HT, Yu ZR, Wong HK. Comparison of segmental pedicle screw instrumentation versus anterior instrumentation in adolescent idiopathic thoracolumbar and lumbar scoliosis. Spine (Phila Pa 1976) 2007;32:1533e42. [19] Geck MJ, Rinella A, Hawthorne D, et al. Comparison of surgical treatment in Lenke 5C adolescent idiopathic scoliosis: anterior dual rod versus posterior pedicle fixation surgery: a comparison of two practices. Spine (Phila Pa 1976) 2009;34: 1942e51.