<prompt> Prolapsed intervertebral Disc PID is most common at -C10C11C2,C3L2L4L5S1  <response>: L5 - SI disc space is the most commonly involved space in disc prolapse.Lumbar intervertebral disc herniation is most common at L5 - SI and slightly less common at L4 - L5, and rare at L3 - L4 or above.The disc at L5 - Si is most commonly involved, followed in order by L4 - L5 and L3 - L4. Pocket book of orthopaedics 