Question 1

Why can isolated ulna fractures sometimes be treated with just a cast when both-bone forearm fractures always need surgery?

Accepted Answer

This is because the intact radius acts as a natural splint stabilizing the broken ulna. In both-bone forearm fractures, both radius and ulna are broken, so there's nothing to prevent the bones from displacing (moving out of position) in a cast—this is why surgery is almost always needed in adults with both bones broken. With isolated ulna fracture, the radius remains intact and connected to the ulna at the elbow and wrist, providing some stability. Think of it like a ladder with one side rail broken but the other intact—the intact rail helps keep the broken rail from collapsing completely. However, this only works for minimally displaced ulna fractures. If displacement is significant (more than 50% width or more than 10 degrees crooked), the radius can't provide enough stability and the fracture will displace further in cast, leading to malunion (crooked healing). Malunion causes problems: loss of forearm rotation (can't turn palm up/down fully), chronic pain at fracture site, and potential for developing arthritis at nearby joints. This is why displaced isolated ulna fractures need surgery despite having an intact radius—the risk of poor outcome with casting is too high. Treatment decision based on X-ray measurements: less than 50% displaced AND less than 10 degrees angulated—try casting with close monitoring (X-rays every 2 weeks); more than 50% displaced OR more than 10 degrees angulated—surgery recommended to restore alignment and prevent malunion.

Question 2

I fractured my ulna 6 weeks ago and it was put in a cast, but my recent X-ray shows it's moved slightly—do I need surgery now?

Accepted Answer

This is called 'late displacement' and is one of the risks of non-surgical treatment. Decision depends on: (1) How much has it displaced? If now more than 50% displaced or more than 10-15 degrees angulated, surgery usually recommended to prevent malunion. If still minimally displaced (just slight movement), may continue casting with very close monitoring (X-rays every 1-2 weeks); (2) How much healing has occurred? If fracture showing early callus formation (healing bone) on X-ray, displacement may be acceptable as bone is stabilizing. If no callus yet (still fresh fracture line), higher risk of further displacement; (3) Your functional demands? Manual workers, athletes, or people who need full forearm rotation more likely to benefit from surgery to restore perfect alignment. Sedentary individuals may tolerate minor malunion. Options at this point: CONTINUE CASTING if: displacement still minimal, early callus forming, patient accepts risk of some permanent loss of rotation. Monitor with X-rays every 1-2 weeks. If no further displacement, continue cast to 10-12 weeks total. SURGERY NOW if: displacement now significant (more than 50% or more than 10-15 degrees), no callus forming (fracture not stabilizing), patient wants optimal functional outcome. Surgery at 6 weeks is more difficult than acute surgery (some callus may have formed making reduction harder) but still very effective. DELAYED SURGERY LATER if: fracture allowed to heal in malunited position (crooked), patient develops chronic pain or significant loss of rotation (can't turn doorknobs, use utensils, type comfortably). Corrective osteotomy (rebreak and realign bone) possible but more complex than acute fixation. Honest discussion with your surgeon about risks/benefits based on your specific X-ray findings and functional needs.

Medical Disclaimer

Broken Ulna Bone from Direct Blow (Nightstick Fracture)

📖What is Broken Ulna Bone from Direct Blow (Nightstick Fracture)?

🔬What Causes It?

⚠️Risk Factors

You may be at higher risk if:

🛡️Prevention