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Forearm Pain That Doesn’t Quite Match the Injury? Hmm.
If your forearm pain is getting WORSE despite elevation and strong painkillers, the forearm feels tight and hard, and gently straightening your fingers is agony… stop reading and go to an emergency department now.
Acute forearm compartment syndrome is a surgical emergency. Pressure builds inside a closed muscle compartment until it cuts off that muscle’s own blood supply, and the muscle begins to die within hours. The treatment is an emergency operation called a fasciotomy. Released within about 6 hours, the outlook for muscle and nerve is good. Beyond 12 hours, permanent damage is the expectation rather than the risk.
The single most reliable sign is pain that is far worse than the injury should produce, and that escalates rather than settles despite elevation and strong painkillers.
Here’s the problem. You’ve had a fracture, a crush, a fresh cast or a hard knock, and everyone told you it would hurt. So when it hurts MORE, you assume that’s just the injury.
Get that wrong and the price isn’t a slow recovery. It’s dead muscle that turns to scar and pulls the wrist and fingers into a fixed claw. Reconstruction can improve that hand. It doesn’t give it back.
So the rest of this page is about one skill: telling pain that’s settling from pain that’s climbing.
What does forearm compartment syndrome feel like?
The signs, in the order they appear:
- Pain out of proportion. Earliest and most important. Deep, relentless, escalating. The painkillers that should work, don’t.
- Pain on passive stretch. Someone gently straightens your fingers and the forearm screams. When the flexor (palm-side) compartment is involved, this is the most sensitive clinical test.
- A tense, wooden-feeling forearm. Not soft, not squashy. Hard, like a packed sausage.
- Paresthesia. Numbness and tingling in the hand as the nerves lose their supply.
- Paralysis. Weakness or inability to move the wrist and fingers. This is late.
- Pulselessness. Very late, and often never. A present pulse does NOT rule this out.
Waiting for a lost pulse before acting is waiting for the limb to be already lost. Pressure that kills muscle is lower than the pressure needed to stop an artery.
In children, and in anyone who can’t report reliably, the signs are the three A’s: increasing Analgesia requirement, Anxiety, and Agitation. These often precede everything else.
A child in a cast who needs more and more pain relief, won’t settle and won’t wiggle their fingers is telling you something. Believe them. See supracondylar elbow fractures in children, the classic setup.
What to do right now, on the way to the ER
- Loosen or remove every bandage and dressing you safely can. All layers, down to the skin.
- In a cast? Say the words “I think my cast is too tight and the pain is getting worse” at triage. A cast has to be split down to the skin, padding included, and that’s the first thing they’ll do.
- Keep the arm at HEART LEVEL, not elevated. Raising it above the heart lowers the pressure driving blood in and makes the perfusion worse. This is the one time the usual “hand up” advice is wrong.
- Do not ice it. Cold reduces perfusion further.
- Nothing to eat or drink. Surgery may be immediate.
- Note the time the pain started climbing. The surgeon will ask, cos that’s when the clock started. Mention blood thinners if you take them.
What causes compartment syndrome in the forearm?
The forearm muscles sit in compartments wrapped in fascia, a tough, fibrous layer that barely stretches.
Bleeding or swelling inside that wrapping has nowhere to go, so pressure climbs. Once it exceeds the pressure in the small vessels, blood stops reaching the muscle.
Muscle tolerates this for roughly 4 to 6 hours.
Nerve tolerates it for less.
Common causes:
- Forearm and elbow fractures, especially supracondylar fractures in children. See forearm fracture recovery.
- Crush injuries. See crushed hand recovery.
- A cast or bandage applied too tight, or one that was fine until the swelling arrived.
- Restored blood flow after a period of arterial blockage.
- High-pressure injection injuries (paint, grease, hydraulic fluid).
- A drip or injection that leaked into the forearm.
- Lying on the arm for hours after alcohol, drugs or a long anesthetic.
- Blood thinners plus relatively minor trauma.
Can a tight cast cause compartment syndrome?
Yes. A cast can’t expand, and the swelling after a fracture peaks over the first 24 to 72 hours. A cast that fit well on day one can be too tight on day two.
Tight-cast pain behaves the same way: it climbs, it doesn’t respond to elevation, and the fingers get numb, pale or dusky. Numbness in a cast is its own urgent question, covered in numb fingers after a wrist fracture or in a cast.
How is compartment syndrome diagnosed?
Diagnosis is clinical. A doctor who sees escalating pain, pain on passive stretch and a tense forearm doesn’t need a machine to agree before going to the operating room.
- Compartment pressure measurement: a needle connected to a pressure monitor. Used where the picture is unclear, or the patient is unconscious, sedated or a young child. A common threshold is compartment pressure within 30 mmHg of the diastolic blood pressure.
- X-rays and scans: show the fracture, not the pressure. A normal scan does not rule this out.
- A normal pulse: does not rule it out either. The pressure that kills muscle is lower than the pressure that stops an artery.
How fast does compartment syndrome cause damage?
This is the Closing Window Method at its most brutal: name the window, find where you are in it, act while it’s open. Here the window is measured in hours.
- 0 to 6 hours: fasciotomy, best chance of full muscle and nerve recovery. Window OPEN.
- 6 to 12 hours: partial damage likely. Window CLOSING.
- Beyond 12 hours: permanent muscle loss and contracture. Window SHUT for normal function. The goal changes to salvage.
Nearly every window on this site is measured in weeks. This is the one measured in hours, and it is the shortest one you will read here.
What happens in a fasciotomy?
Emergency fasciotomy: the fascia is opened along the length of the compartment to release the pressure. It’s a long incision on purpose. A short one doesn’t release enough.
- Wounds are left open at first, because closing them would rebuild the pressure.
- Back to the operating room in a few days to close the wound, or cover it with a skin graft if the swelling won’t allow closure.
- Often a carpal tunnel release at the same time, cos the median nerve gets squeezed at the wrist too.
Recovery after fasciotomy, phase by phase
Your surgeon’s protocol wins over anything here. These are the typical phases.
- Days 0 to 7 (wounds open, then closed or grafted): hand rested in a splint in the safe position, wrist slightly up, knuckles bent, fingers straight. See resting hand splint. Once the pressure is released, elevation is back on for swelling. Fingers move as soon as the surgeon allows.
- Weeks 1 to 3 (wound healing): tendon glides, 10 reps of each position, 3 to 5 times a day. Gentle wrist and finger motion. Swelling control. The job is to keep the forearm muscles gliding and the fingers from drifting into a curl.
- Weeks 3 to 8 (scar and stretch): once the wound or graft has healed, scar massage and silicone, a few minutes daily. See scar management after hand surgery. With your surgeon’s OK, a combined stretch: wrist and fingers straightened together, held 30 seconds, 3 times, several times a day. Light grip work starts.
- Months 2 to 6 (strength): putty, grip, forearm strengthening, progressing to the loads your life needs.
- Months 3 to 12 (nerves): if a nerve was affected, it regrows at roughly 1 mm a day, about an inch a month. Feeling returns from the forearm downward, fingertips last.
(The forearm scar is long. It looks dramatic. It’s the reason the hand underneath it still works.)
When can I work, drive and play sport after a fasciotomy?
- Desk work: in my experience, often 2 to 6 weeks after the wound is closed, longer with a skin graft.
- Manual or heavy work: 3 months or more, and depends on how much muscle was saved.
- Driving: once the wound is healed, you’re off strong pain meds, and you can grip and turn the wheel firmly enough to handle an emergency stop. Usually weeks, not days.
- Gym, contact sport, climbing: 3 months at the earliest, cleared by your surgeon. If the original cause was a fracture, that bone sets the pace too.
What happens if compartment syndrome is missed?
Volkmann’s ischemic contracture is what untreated compartment syndrome leaves behind: dead muscle replaced by scar, which shortens and pulls the wrist and fingers into a fixed claw. Reconstruction is possible, tendon lengthening, muscle slides, muscle transfers, but it is salvage, and hands do not come back to normal.
Is forearm arm pump the same thing?
No. The chronic version, forearm pump in climbers, motocross riders and rowers, is a separate condition with a separate article: forearm pain and arm pump.
It is exercise-induced, resolves with rest, and surgery for it is elective. The acute version described here does not resolve and is not elective.
Forearm pain without any of the warning signs above? Forearm pain by location sorts it by spot.
Go to the emergency department now if
- Forearm pain after a fracture, crush or new cast is getting worse instead of better, despite elevation and pain meds.
- Gently straightening your fingers causes severe forearm pain.
- The forearm feels tight, hard and swollen, like it’s about to burst.
- New numbness, tingling or weakness in the hand, especially in a cast.
- A child in a cast needs more and more pain relief, is increasingly distressed, or won’t move their fingers.
- You take blood thinners, had a knock, and the forearm is swelling fast and tightening.
Call your surgeon today if
After a fasciotomy:
- Increasing redness, warmth, discharge or a fever.
- Pain climbing again after it had settled.
- Numbness or weakness getting worse rather than slowly better.
- The fingers pulling into a bend you can’t fully straighten, even with the other hand helping.
Most hand problems give you weeks. This one gives you hours, and the pain is the alarm. Listen to it.
Written by Nigel Chua, hand occupational therapist in practice since 2005. Thousands of hands, wrists and elbows assessed and treated. My credentials are here. This article explains; it doesn’t examine. Forearm pain that keeps climbing is not a reading problem. It’s an emergency department problem, tonight.