KIDS Broken Forearm
Pediatric Both Bone Forearm Fracture
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related topics: broken arm, broken wrist, broken elbow, broken radial head, broken medial epicondyle, broken lateral condyle
What is a Pediatric Both Bone Forearm Fracture?
Kids are always running, playing, rough-housing, and as a result kids also tend to take more falls than adults. When we fall, we put our arm out to brace the fall, so its not uncommon for kids to break their forearm from the force of falling. A broken forearm a common injury in kids.
To better understand the injury lets quickly review the anatomy of our forearm. Your forearm has two bones: the radius (which is on the thumb side of your forearm) and the ulna (on the pinky finger side of the forearm). The name "Radius" is latin for "spoke" like the spokes of a bicycle tire that rotate around the axis....and this bone rotates around the other forearm bone (the Ulna) when you twist your wrist (like when turning a doorknob). The radius is the main forearm bone to form the wrist joint (it meets up with other wrist bones). But as you move toward the elbow, the radius gets thinner and smaller as the ulna becomes bigger, so that at the elbow, the ulna makes up the larger portion of the elbow joint. The two forearm bones work together very closely so its typical for both to be injured at the same time (and so its important to look for injury to the other bone, even when just one appears injured).
There are a couple of different types of forearm fractures worth discussing. Bones can break under tension (getting pulled apart) and can break under compression (getting squished together). Both commonly occur in kids.
"Buckle and Torus Fractures" are the compression type. The bone gets squished (impacted) by an axial force (directed up the shaft of the bone). Torus fractures are pure squishing injuries. Buckle fractures occur with squishing plus a little bending, called compression distraction fractures where one side of the bone is squished (compressed) while the other side is pulled apart (distracted). These breaks usually occur in the forearm just before the wrist (called the distal radius).
The "Greenstick Fractures" is your classic tension type injury (bones are pulled apart). "Greenstick" is named after a young tree branch (a greenstick) which is so flexible that when you try to break the twig, it doesn’t snap but rather partially splits apart because theres that green substance inside that prevents it from breaking fully (it mostly bends). In kids, fractures often occur the same way because there is a sleeve of soft tissue that surrounds the bone in all people (called periosteum) almost like bark on a tree which provides nutrients to the outer 1/3 of the bone. In kids this periosteum is very thick (it gets thinner as we get older) and this sleeve around the bone acts as a protective force, so when bone breaks this sleeve prevents a bone from snapping, it just breaks and bends a little. Greenstick fractures are incomplete breaks of the forearm bones. The bone is not completely broken, but it can bend significantly, and therefore there is a visible deformity of the forearm.
Diagnosing a Pediatric Both Bone Forearm Fracture?
These injuries are usually seen after a child falls onto an outstretched hand. The bone breaks due to a combination of a bending and rotational force. The forearm is often visibly bent (like a little broken wing), so diagnosis of a broken arm is usually straight forward. Doctors will order x-rays. These will confirm the break and will help doctors plan for treatment.
Treating a Pediatric Both Bone Forearm Fracture:
Buckle and Torus Fractures: The bone doesn't move out of position so the bone doesn't need to be re-aligned. The bones just need protection while they heal. Minor fractures only need a removable wrist splint, while bigger fractures need a cast for about 4 weeks to give better protection (and prevent the bone from shifting out of position).
Greenstick Fractures: The bones are bent, so they need to be straightened out. Therefore kids are usually sedated while a doctor straightens the bone (this is not surgery, there is no scalpel involved. its called a "closed reduction" because the skin remains closed). With that said, its important to recognize that all bent bones don't need to be perfectly straight. Doctors accept up to 15 degrees of bending in the bones of children because they know a child's body can fix the rest. This warrants repeating. The bone may not be perfectly straight after a greenstick fracture and thats ok. The bone will continue to straighten as it heals and as the child's forearm continues to grow (somehow the bone knows it should be straight and takes care of this on its own). This process of the bone straightening-itself is called "remodeling" and only kids have this ability (adults need surgery to get a perfectly straight bone...adult forearm fractures, see talk).
Sometimes, doctors allow even more than 15 degrees of bending , especially near the growth plate at the wrist, or in kids less than 10 years old because the bones has sooooo much remodeling potential. Studies show that growing bone can correct up to 10 degrees of bending every year. Remember that this remodeling only occurs in growing kids.
Once the bone is straight enough to heal on its own, its placed into a cast for a few weeks. Usually a both bone forearm fracture gets 4 weeks in a long-arm cast, then 4 weeks in a short-arm cast, then 4 weeks in a removable splint (this can definitely vary based on the doctor and the kid and the severity of injury).
What is the long term outcome?
This is a very common injury in kids, and they usually do great. The biggest concern for complication is a re-injury of the bone. There is a risk that the bone can re-break once a kid comes out of a cast. Re-breaking is uncommon, and it usually occurs between 3-6 months after the injury, once the child feels totally normal and returns back to full time sports (but there is probably a slight weakness in the bone).
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References
1) Bohm ER et al. Above and below-the-elbow plaster casts for distal forearm fractures in children. A randomized controlled trial. JBJS 2006; 88: 1-8. full article. nonop treatment BBFA.
2) McQuinn AG, Jaarsma RL. Risk factors for redisplacement of pediatric distal forearm and distal radius fractures. J Ped Ortho 2012. 32: 687-92. full article. initial displacement and quality of reduction.
3) Mamat AS et al. Redefining the cast index: the optimum technique to reduce redisplacement in pediatric distal forearm fractures. J Ped Ortho 2012; 32: 787-91. full article. cast index value.
4) Reinhardt KR et al. Comparison of intramedullary nailing to plating for both-bone forearm fractures in older children. J Ped Ortho 2008; 28: 403-9. full article. surgical treatment options.
5) Fuller DJ, McCullough CJ. Malunited fractures of the forearm in children. JBJS Br 1982; 64: 364-7. full article. distal breaks heal better bc 75% growth occurs here.
6) Evans EM: Fractures of the radius and ulna. JBJS Br 1951; 33: 548-561. full article. rotational component to fx.
7) Carey PJ et al. Both-bone forearm fractures in children. Orthopedics 1992; 15: 1015-9. full article. nonop reduction criteria.
8) Noonan KJ, Price CT. Forearm and distal radius fractures in children. JAAOS 1998; 6: 146-56. full article. review.
9) Price CT et al. Malunited forearm fractures in children. JPO 1990; 10: 705-12. full article. 47 pts with malunited fractures, all satisfied with function and cosmesis. no issues with nonunion.