The hand is a complex, tightly connected structure of bones, ligaments, tendons, nerves and muscles, which allow for small and complicated motions. Thus, an injury to any particular structural component will have a significant effect on the function of the whole hand1.
In looking at the onset of wrist injuries related to athletics, the focus of the analysis will be on cycling due to its high popularity. According to a study sponsored by the US Department of Transportation?s National Highway Traffic Safety Administration (NHTSA) and Bureau of Transportation Statistics approximately 57 million people or 27.3% of the adult population, age 16 and over, rode a bicycle at least once during the summer of 20022.
Research about cycling injuries revealed an interesting pathology in cyclists: handlebar palsy. Handlebar palsy, a form of ulna neuropathy, is a compression syndrome of the deep terminal motor branch of the ulna nerve while it passes though the Guyon canal. The Guyon canal is formed by the pisiform and hamate bones and the ligament that passes between them. The narrowest section of the canal is at the connective tissue closer to the hamate bone, which makes this site prone to compression injuries. The deep branch of the ulna nerve divides off in proximity to the pisiform bone and then dives between the hypothenar muscles as it approaches the hook of the hamate. Due to the compression at the hamate, only the intrinsic muscles of the hand are affected while hypothenar muscles and all the sensation of the hand, provided by the ulna nerve, are spared.
Handlebar palsy has been most commonly associated with chronic repetitive trauma and chronic pressure3 applied to the wrist. Kronisch & Pfeiffer4 reported that 90% of interviewed cyclists experienced symptoms consistent with overuse injuries, 35% of them occurring at the wrist. Subjects described the discomfort as cramping and weakness in the hand and fingers, a common indicator for handlebar palsy.
The first case study presents a cyclist who participated in the Bicycle Ride Across the United States when he rode an average of 347 miles per day for 9 days. He began to experience weakness of the right hand after the third day of riding. Numbness and weakness in his hand persisted upon completion of the race. An examination revealed atrophy of all intrinsic hand muscles that are supplied by the ulna nerve. The hypothenar muscles were not affected and there was no sensory loss. In a similar case, a 49-year-old physician experienced clumsiness and cramps in both hands upon returning from his 2 weeks long mountain bike trip. He was unable to hold syringes at work or play the piano at home. After an MRI showed no lesions to the cervical spine an examination of the hand revealed paresis and atrophy of intrinsic hand muscles on both sides. Hypothenar muscles were spared and the sensation was preserved.
Both subjects were advised to refrain from offensive activities. Like in many nerve injuries, handlebar palsy resolves with rest. Wearing padded cycling gloves has also shown to provide relief from handlebar palsy as it eases the compression on the ulna nerve.
Handlebar Palsy can evolve into a debilitating condition. The most effective way to prevent handlebar palsy, according to research, is changing grip position during bicycling and wearing protective bicycling gloves. Therefore, do not leave your gloves at home next time you go out for a ride and check in with your hands every here and then ‚Äì if they tingle, switch the grip position!
The article is an excerpt from a kinesiology project ‚ÄúKinesiology of the hand and wrist‚Äù written by Fournier R, Merrill A, Newberry J and Young M, students of physical therapy at Regis University.
1 Moran, AC. Anatomy of the hand. Physical Therapy. 1989; 1007(7)
2 Available at https://www.bikeleague.org/media/facts/. Accessed January 27, 2008
3 Capitani D, Beer S. Handlebar Palsy-a compression syndrome of the deep terminal (motor) branch of the ulna nerve in biking. J Neurol. 2002; 249 1441-1445
4 Kronisch LK, Pfeifer PP. Mountain Biking Injuries: an update. Sports Medicine. 2002; 32(8):523-537