Do Current Recommendations for Upper Instrumented Vertebra Predict Shoulder Imbalance? An Attempted Validation of Level Selection for Adolescent Idiopathic Scoliosis

HSS Journal Article

Benjamin T. Bjerke, MD, MS
Hospital for Special Surgery, New York, NY

Zoe B. Cheung, MS
Hospital for Special Surgery, New York, NY

Grant D. Shifflett, MD
Hospital for Special Surgery, New York, NY

Sravisht Iyer, MD
Hospital for Special Surgery, New York, NY

Peter B. Derman, MD, MBA
Hospital for Special Surgery, New York, NY

Matthew E. Cunningham, MD, PhD
Matthew E. Cunningham, MD, PhD

Assistant Attending Orthopaedic Surgeon, Hospital for Special Surgery
Assistant Professor in Orthopaedic Surgery, Weill Cornell Medical College


Shoulder balance for adolescent idiopathic scoliosis (AIS) patients is associated with patient satisfaction and self-image. However, few validated systems exist for selecting the upper instrumented vertebra (UIV) post-surgical shoulder balance.

The purpose is to examine the existing UIV selection criteria and correlate with post-surgical shoulder balance in AIS patients.

Patients who underwent spinal fusion at age 10–18 years for AIS over a 6-year period were reviewed. All patients with a minimum of 1-year radiographic follow-up were included. Imbalance was determined to be radiographic shoulder height |RSH| ≥ 15 mm at latest follow-up. Three UIV selection methods were considered: Lenke, Ilharreborde, and Trobisch. A recommended UIV was determined using each method from pre-surgical radiographs. The recommended UIV for each method was compared to the actual UIV instrumented for all three methods; concordance between these levels was defined as “Correct” UIV selection, and discordance was defined as “Incorrect” selection.

One hundred seventy-one patients were included with 2.3 ± 1.1 year follow-up. For all methods, “Correct” UIV selection resulted in more shoulder imbalance than “Incorrect” UIV selection. Overall shoulder imbalance incidence was improved from 31.0% (53/171) to 15.2% (26/171). New shoulder imbalance incidence for patients with previously level shoulders was 8.8%.

We could not identify a set of UIV selection criteria that accurately predicted post-surgical shoulder balance. Further validated measures are needed in this area. The complexity of proximal thoracic curve correction is underscored in a case example, where shoulder imbalance occurred despite “Correct” UIV selection by all methods.

Level of Evidence: IV

This article appears in the HSS Journal: Volume 11, Number 3.
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About the HSS Journal

HSS Journal, an academic peer-reviewed journal, is published twice a year, February and September, and features articles by internal faculty and HSS alumni that present current research and clinical work in the field of musculoskeletal medicine performed at HSS, including research articles, surgical procedures, and case reports.


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