Expanding Your Working Envelope: Why It Matters in Upper-Limb Prosthetics

Expanding Your Working Envelope: Why It Matters in Upper-Limb Prosthetics

By Marins Inc.

Ever tried to carry a heavy bag while reaching for your keys? Or hold onto a tool while climbing a ladder? For many upper-limb amputees, this is daily life — and how far you can reach, hold, and move freely depends on something called your working envelope.

What Is a Working Envelope?

Think of your working envelope as the invisible space around your body where you can comfortably reach, grip, lift, and maneuver objects while using your prosthetic. It’s not just about arm length, it’s about what you can do inside that space without awkward compensations or overexertion.

A well-designed working envelope means you can:

• Keep a firm grip while moving your arm freely
• Reach up high, down low, or across your body
• Balance, stabilize, or switch tasks without constantly readjusting

How the ProHook Expands What’s Possible

Many prosthetic users know the frustration of limited motion. If you have to constantly maintain tension just to hold onto something, your shoulder and upper body get worn out fast — which shrinks your working envelope.

The ProHook changes that. Its self-actuated locking system holds your grip steady without needing extra input. Once you’ve got a good grip, you’re free to move naturally: twist, lift, brace yourself, or switch positions without fear of dropping what you’re holding.

This means less fatigue, better control, and more confidence. In real life, that can look like:

• Carrying a grocery bag and unlocking your front door
• Holding a screw overhead while adjusting a drill
• Climbing a ladder while holding onto a bucket or tool

Why It Matters

At Marins, we know a good prosthetic doesn’t just give you a hook — it gives you back space, freedom, and trust in your own movements. The more you can do inside your working envelope, the more you get back to living life your way.

The ProHook was designed by someone who lives this every day — so it works hard, locks on demand, and stays out of your way while you get on with it.

Learn More

Want to dig deeper? Here are a few resources that explain the working envelope in prosthetics:

• Prosthetic Upper Limb Functional Anatomy in the VA/DoD Clinical Practice Guidelines — includes working envelope considerations when choosing devices.
• Atkins DJ et al., Epidemiologic Overview of Individuals with Upper-Limb Loss and Their Reported Research Priorities (JRRD 1996; 33(2): 155–162) — discusses real-life functional goals that include working envelope needs.
• National Academies Press – The Promise of Assistive Technology to Enhance Activity and Work Participation (2017) — addresses range of motion and functional reach.