When Mike Zunino went on the DL for my beloved Seattle Mariners last week with a hamate fracture, the same type of injury Ken Griffey Jr. sustained in 1996, it prompted me to review how baseball players seem specifically prone to this injury. When you look at the anatomy of the wrist, and the mechanism of swinging a baseball bat, it is really pretty simple to understand.
Check out this image and you can see that the hook of the hamate bond is in close contact with the handle of a baseball bat, and with a hard swing, especially a swing and a miss, the torque of the bat is leverages on the part of the lower wrist where the hook of the hamate is just under the skin. If you feel your wrist, on the pinkie side, at the very base of the wrist, you’ll feel the hook of the pisiform bone. Just distal to that in the outside base of the palm is the hook of the hamate. Now pretend you are swinging a bat, and missing. As the leading hand rolls over, much of the pressure of the bat comes right on the hook of the hamate. This appears to be the mechanism that leads to fractures of this part of the hamate bone on a hard swing and miss. Golfers are also sometimes at risk for this injury.
Fortunately this part of the bone is relatively expendable. The standard of care is for early excision of the hook of the hamate, usually the whole hook, not just the tip if only the tip is broken off, because of concern for a second hamate hook fracture more proximally later. When Ken Griffey had his hamate fracture he returned to play in just 23 days, but somewhat longer recoveries are more typical according to Mariner’s trainer Rick Griffin 28-35 days is more typical.
Complications of hamate hook fractures can include injury to the ulnar nerve as it passes through the Guyon tunnel that the hook of the hamate covers as it passes the outside of the wrist and lends innervations to the muscles deep in the hand. Decreased grip strength is also a possible complication as relatively unimportant ligaments that attach to the hook of the hamate may need to be sacrificed in the excision. Still most baseball players return to full function without complications.
Look at this list of professional baseball players who have had this injury:
Dustin Pedroia (Red Sox): Played the last 2 months of 2007 including the World Series with a hamate fracture, had off season surgery, and was the AL MVP in 2008.
Troy Tulowitzki (Rockies) returned successfully after surgery in midseason 2010.
Pablo Sandoval (Giants) missed 7 weeks last year and returned to great success the rest of the season.
On a fun note, it you want to rememember the names of the 8 bones of the wrist the naughty mnemonic we used in anatomy class is: “Never lower Tilly’s pants, gramma lesser might come home. The bones of the two 4-bone arches of the carpus (wrist) are the Navicula (also called the Scaphoid), Lunate, Triquetrial, Pisiform,Greater Multangular (Trapizium) Lesser Multangular (Trapezoid), Capitate and Hamate bones.
Let’s all hope that Henry Blanco and the fill in free agent Humberto Quintero can fill the void left as Zunino, who has been hitting better of late, is on the DL. Go M’s!