Lumbar spinal stenosis — surgical management

A 62-year-old man with a 3-year history of progressive lumbar spinal stenosis presents with neurogenic claudication. Imaging shows severe central stenosis at L4–L5 with ligamentum flavum hypertrophy and facet joint osteoarthritis. Conservative management (NSAIDs, physical therapy, epidural steroid injections) has failed over 6 months. He is now a candidate for surgical decompression. Which of the following surgical approaches would provide the most direct decompression of the ligamentum flavum and lateral recess stenosis while preserving segmental stability and minimizing iatrogenic instability?

A 58-year-old man presents with a 2-year history of bilateral lower limb claudication that worsens with standing and walking, but improves with sitting and forward bending. MRI of the lumbar spine shows degenerative changes with central canal stenosis at L4–L5 and L5–S1 levels. He has normal ankle reflexes and no focal motor deficit. Conservative management with NSAIDs and physical therapy has failed. Which of the following is the most appropriate surgical approach for this patient?