The principles established in Parts 1 to 3 apply broadly to denervated muscle wherever it occurs in the body. But clinical reality is specific. A spinal cord injury involves complications that a post-surgical nerve repair does not. A facial palsy presents challenges that a thigh muscle does not. And the practical question of why specialist equipment costs so much deserves an honest answer.
Part 4 applies the foundations, evidence, and treatment framework to specific conditions and practical concerns. Chapter 11 covers spinal cord injury, the population for whom much of the evidence was built. Chapter 12 addresses facial palsy, where the anatomy is unique and clinical guidelines have lagged behind the evidence. Chapter 13 examines post-surgical denervation, where the race between nerve regrowth and muscle deterioration creates a distinct clinical urgency. Chapter 14 extends the tissue health argument to pressure ulcers. Chapter 15 addresses the combination of treatments into a coordinated programme. Chapter 16 explains why specialist equipment costs what it does.