What is grade 1 anterolisthesis of L5 on S1 related to severe facet hypertrophy?

Grade 1 anterolisthesis of L5 on S1 refers to a slight forward displacement of the L5 vertebra over the S1 vertebra, typically classified as less than 25% slippage. This condition can be associated with severe facet hypertrophy, which is the enlargement of the facet joints due to degeneration or Arthritis. The hypertrophy can contribute to instability and alter the normal alignment of the vertebrae, leading to anterolisthesis. This combination may result in Back pain and can affect spinal function.