The investigators are conducting a randomized clinical trial comparing two types of splints for treatment of Boxer's fractures in children up to age 17 inclusive. Patients who meet inclusion criteria will be randomized to either Group A or B. Group A will be treated with the conventional plaster ulnar gutter splint. Group B will be treated with a custom molded thermoplastic hand-based splint. The thermoplastic splint will provide support of the metacarpal but does not immobilize the patient's wrist or interphalangeal joints.

Hypothesis: Is plaster splint immobilization an equivalent treatment method to a custom made thermoplastic splint for a fifth metacarpal neck fracture? Will one splint be tolerated better than the other and will the compliance be different between the two groups?

Nearly all Boxer's fractures are treated without surgery using a splint to keep part or all of the hand from moving (immobilization). There are several acceptable methods of immobilization used by hand surgeons, using splints of different sizes and materials for variable periods of time(1-6).

A recent systematic review from The Cochrane Collaboration found the current data to be inconclusive with regards to the optimal immobilization technique and highlighted the need for further studies(2). Specifically, it was recommended that future studies include functional outcome measures, timing of return to work, complications, pain scores, and an economic analysis.

The current practice at the investigators' institution is for patients to be splinted in a plaster ulnar gutter splint, in the Emergency Department and referred to the next available plastic surgery clinic. If needed, a closed reduction would be performed in clinic, if there was a significant angulation (greater than 45 degrees) or any clinical rotation deformity. The most common method of immobilization involves placing the wrist, ring finger and little finger all the way from the fingertips to the mid-forearm in molded plaster called an ulnar gutter splint. The splint is left on 24 hours a day for 3 to 4 weeks and then removed in the clinic.

Many patients find it difficult to keep the splint on for the full 3 to 4 weeks for a number of reasons. The plaster needs to stay dry, making it awkward to bathe. The splint can also get loose and rub as the swelling around the fracture gets better. The splint can also start to smell because sweat builds up under it. Some patients find the plaster material heavy, making it difficult to wear. Finally, many patients are self-conscious about the appearance of the splint and remove it for this reason alone. In the investigators' experience, up to 1 out of 5 patients will remove the splint on their own against doctor's orders for one reason or another. When patients do follow instructions and keep the splint on 24 hours a day for 3 to 4 weeks, this can lead to joint stiffness when the splint is removed. Some patients may even require physiotherapy to regain their normal finger movement and grip strength.

It is unknown if the ulnar gutter splint is really the best way to immobilize the hand after a Boxer's fracture. It is unknown what material is best for making the splint, whether it is truly necessary to keep the entirety of the wrist and ring and little fingers still, and for how long the hand and fingers should be kept still. Most surgeons recommend patients wear a splint for 3 to 4 weeks.

The investigators would like to determine if a smaller splint made of more durable, lighter moldable plastic that allows earlier movement of the hand and fingers while still keeping the fracture from moving gives the same result as the commonly used ulnar gutter splint.

Functional Hand Based Splint (Thermoplastic Splint) The functional hand-based splint is made of custom molded hard plastic and is fitted over the hand only. A thermoplastic splint is made from plastic that is heated and custom-fitted to the subject's hand, which hardens when it cools. This thermoplastic splint is custom fitted by an occupational therapist such that all joints are free to move. The splint does not limit the patient from moving their wrist or fingers while wearing it. It is custom molded such that it fits snuggly over the patient's hand and holds the fracture in a stable position.

Several adult studies have found this type of custom molded splint superior to either surgical treatment and/or plaster splint immobilization because it resulted in less stiffness, better movement after splint removal, and no increased pain (4-7). The investigators are not aware of any comparative studies done in pediatric patients.

Compliance Patient compliance for wearing their splint for the prescribed during can be a problem. At the investigators' institution, there is a non-compliance rate of approximately 15 to 20 % for Boxer's fracture patients. The investigators hypothesize that the hand-based splint will be better tolerated by patients and therefore result in a higher rate of compliance for the prescribed duration that the plaster splint. Also, the thermoplastic splint will not be damaged if it gets wet, which may translate into fewer additional visits to the clinic or emergency department to have the splint replaced.

This study will be a randomized, single-blinded controlled trial. The randomization of the two splint types will be determined by a computer-based number generator. The patients will know what type of splint they have, but the plastic surgeons and physiotherapist who examine and test the subjects ROM and grip strength will not know the type of splint for each subject.

Patients will be randomized to one of the two groups at their first clinic visit, within 7 days of their injury. They will have their splint placed at this visit and are to wear the splint at all times for 3 weeks. Subjects will return to clinic at 1, 3, 6, and 12 weeks to be reassessed. Specified outcome measures (primary and secondary) will be tested at each visit.

Inclusion Criteria:

• Isolated 5th metacarpal neck fracture
• Less than 10 days from injury

Exclusion Criteria:

• Multiple Metacarpal fractures
• Significant injuries to other hand structures (tendons, nerves, major arteries)