[Adjacent Segment Disease in Lumbar Spine and Lumbosacral Junction Stabilisation: Systematic Review]

This paper aims to analyse available scientific sources related to adjacent segment disease after the surgical stabilisation of lumbar spine. To be specific, to the incidence, risk factors, gender and age of patients, correlation between the length of the instrumentation and ASD development, and the effects of suboptimal sagittal spine stability.

A systematic review was elaborated in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) guideline. A literature search in PubMed database was conducted in January 2025. The papers included in the systematic review were published between 2004 and 2023.

The search brought about 1,014 results, of which 59 studies were shortlisted based on their title and abstract. Those 59 articles were subsequently thoroughly examined and unsuitable papers were excluded. Yet another study meeting our criteria was identified through the analysis of cited references. A total of 17 papers that satisfied the predetermined criteria were selected. The number of patients included in the cohorts ranged from 117 to 3,799. The subjects were followed up for the period of at least 12 months up to 10 years postoperatively, the mean follow-up period reached 5.44 years. At the time of initial surgery, the age of the followed-up patients was 18 to 74 years, with a mean age of 56.67 years. The ASD incidence ranged from 0.74% to 30.3%. As concerns surgical therapy, 2.62%-27.4% of patients underwent surgery for adjacent segment disease. The most commonly referred to factor contributing to ASD development was the adjacent segment degeneration visible already preoperatively as well as iatrogenic damage to adjacent facets, high BMI, length of the fixation, sagittal balance, rheumatoid arthritis, or age. Osteoporosis, smoking, or diabetes mellitus, on the other hand, were not confirmed as risk factors.

Currently, there is a large body of studies on ASD published over several decades. This fact further reinforces its high clinical significance and long-term interest of academia in spine surgery.

ASD is a common postoperative complication in instrumented lumbar and lumbosacral fusions. The most commonly cited risk factors were preoperative adjacent segment degeneration, followed by iatrogenic alterations on unfixed intervertebral joints, sagittal imbalance, and higher BMI of the patient. Some authors also refer to advanced age as a factor contributing to earlier development of adjacent segment degeneration. Different conclusions are stated with respect to the fixation length, with more frequent reference to higher incidence of ASD in longer-segment fixation. The outcomes of other studies, however, reveal that the frequency of ASD development is independent of the number of fixed segments. Moreover, in one case, protective effects of long-segment fixations were proven by the authors. No correlation between gender, smoking, diabetes mellitus or osteoporosis with adjacent segment disease development was confirmed. Although the incidence of ASD can be reduced by correct indication and surgical technique, we shall continue to encounter this condition in clinical practice.