# A novel pre-contoured V-shaped rod in one-level pedicle subtraction osteotomy for the treatment of rigid lumbar kyphosis caused by ankylosing spondylitis: technical note and case series

## TL;DR

This paper introduces a new surgical technique using a pre-contoured V-shaped rod to correct spinal deformities in patients with ankylosing spondylitis.

## Contribution

The novel use of pre-contoured V-shaped rods in one-level PSO for treating AS-induced kyphosis is introduced and evaluated.

## Key findings

- The technique achieved significant correction of kyphosis and restoration of lumbar lordosis without complications.
- Average correction of general kyphosis was from 68.2° to 22.0° and lumbar lordosis from -5.4° to 37.6°.
- Surgical outcomes showed improved sagittal vertical and chin-brow angles with no instrument-related complications.

## Abstract

To introduce and evaluate the feasibility of one-level pedicle subtraction osteotomy (PSO) combined with pre-contoured V-shaped rods in the treatment of spinal kyphosis deformity caused by ankylosing spondylitis (AS).

Five patients from ages 33 to 47 years old with progressive spinal kyphosis caused by AS underwent one-level PSO, combined with pre-contoured V-shaped rods. Further technical modifications included a PEEK cage, enhanced positioning device, and enlarged osteotomy area. Preliminary short-term clinical and radiographic outcomes were assessed.

The mean operation duration was 306.0 min with an average estimated blood loss of 765.0 ml. No instrument-related or neurological complications occurred during hospitalization. On average, general kyphosis (GK) was corrected from 68.2° to 22.0° and lumbar lordosis (LL) was restored from − 5.4° to 37.6°. The correction angle ranged from 39° to 56° and the osteotomy vertebrae angle was performed between 34° and 51° based on the surgical necessity, averaging 40.8°. Finally, the mean sagittal vertical angle (SVA) was corrected from 231.8 mm to 89.0 mm and the mean chin-brow vertical angle (CBVA) was reduced from 42.6° to 13.8°.

One-level PSO with pre-contoured V-shaped rods at middle lumbar spine is a novel treatment option for the correction of AS-induced lumbar kyphosis and restoration of lumbar lordosis. This alternative technique obtains satisfactory radiographic and clinical outcomes for AS patients without necessitating additional surgery or elevating the risk of complications such as sagittal translation.