Long-Term (Over Five Years) Results of Surgical Correction of Scheuermann’s Kyphosis
Authors: Mikhaylovskiy Mikhail , Gubina Elena , Alshevskaya Alina , Lukinov Vitaly 
Published: May 2021

Abstract
Study design. Retrospective cohort study.Objective. The study objective is to assess long-term results of surgical correction of kyphosis due to Scheuermann’s disease.Summary of Background Data. Despite a large number of studies on surgical correction of juvenile kyphosis, articles discussing long-term (over five years) results of these interventions are very rare.Methods. The study group included 43 patients (m/f ratio, 34/9). The mean age was 19.1 (14–32) years; the mean postoperative follow-up was 6 + 10 (5–20) years. Two-stage surgery including discectomy and interbody fusion followed by posterior correction and fusion was conducted in 35 cases (group A). Eight patients (group B) underwent only posterior correction and spinal fusion. The following parameters were determined for each patient: Thoracic Kyphosis (TK); Lumbar Lordosis (LL), Sagittal Vertical Axis (SVA); Sagittal Stable Vertebra (SSV); First Lordotic Vertebra (FLV); Proximal Junctional Angle (PJA); and Distal Junctional Angle (DJA). All measurements were performed immediately before surgery, one week after surgery, and at the end of the follow-up period. All patients answered the SRS-24 questionnaire after surgery and at end of the follow-up.Results. Groups A and B were comparable in age and sex, BMI and initial Cobb angle (P < 0.05). The curve decreased from 77.8° to 40.7° in group A and from 81.7° to 41.6° in group B. The loss of correction was 9.1° and 6.0° in groups A and B, respectively. At ID < 1.2, deformity correction and correction loss were 35° (44.0 %) and 7.1°, respectively; at ID ˃ 1.2, deformity correction and correction loss were 44.5° (54.7 %) and 3.9°, respectively (P < 0.05).Proximal junctional kyphosis was detected in 21 out of 43 patients (48.8 %). The rate of PJK was 45.4 % in those patients whose upper end vertebra was included in the fusion and 60 % in individuals whose upper end vertebra was not included. PJK developed in eight (47.8 %) out of 17 patients who received ≥ 50 % kyphosis correction and in 13 (50 %) individuals who had < 50 % deformity correction. The rate of DJK development was 39.5 %. The lower instrumented vertebra (LIV) was located proximal to the sagittal stable vertebra in 16 cases, with 12 of them being diagnosed with DJK (75 %). In 27 patients, LIV was located either at the SSV level or distal to it, the number of DJK cases was 5 (18.5 %) (P < 0.05). Only two patients with complications required unplanned interventions. According to the patient questionnaires, the surgical outcome score increases between the immediate and long-term postoperative periods for all domains and from 88.4 to 91.4 in total. The same applies to answer to the question No. 24 (“Would you have the same treatment again if you had the same condition?”): rate of positive answers ranges from 82 to 86 %.Conclusions. Two-stage surgery, as a more difficult and prolonged one, has no advantages over one-stage operation in terms of magnitude and stability of the achieved effect. The problem of choosing the area of spinal fusion is far from being solved. Surgical treatment improves the quality of life of patients with Scheuermann’s disease; the improvement is also observed in the long-term postoperative period.