Finger capillary damage in an archer: Sirufo 2020

A 16-year-old girl who had shot compound for five years was seen by clinical immunologists from the University of L'Aquila because her right hand was swollen and both hands hurt, symptoms present for about two years and worse over the last one, especially after competitions and long training sessions. Blood tests, including the antibodies typical of autoimmune disease, an MRI of the hands and a Doppler ultrasound of the arms were all normal.

Nailfold capillaroscopy, a magnified view of the small vessels at the base of the nails, did however find changes on the index, middle and ring fingers of the right hand, the string hand: dilated and twisted capillaries shaped like a treble clef or antlers, return limbs up to 35 micrometres wide, a ratio of return to supply limb above 2 to 1, granular flow and small haemorrhages. The left hand, the bow hand, was normal. The authors classify the picture as non-specific, meaning without the typical signs of scleroderma, and attribute it to the muscle tension and vibration the string-hand fingers undergo with every shot. The girl was advised to reconsider, where possible, her posture and the tension in her hand when shooting, to do hand relaxation exercises, to protect her hands from the cold and to repeat the examination every year.

This is a single case report. The girl, right-handed, had shot since the age of 11, on average three hours a day on three days a week plus a weekly competition of an hour and a half, with 100 to 200 arrows per session; she used a 48 lb compound bow, held in her left hand. Before the capillaroscopy the authors used her history, blood tests, MRI and Doppler ultrasound to rule out conditions that produce similar changes: autoimmune and vascular disease, primary Raynaud's phenomenon, diabetes and carpal tunnel syndrome.

The examination used a videocapillaroscope at 200 times magnification linked to image analysis software, after 15 minutes' acclimatisation at 23 degrees and with a drop of oil on the nailfolds of the index, middle, ring and little fingers of both hands. For each finger the authors assessed capillary density, diameter and shape, their arrangement, blood flow and any microhaemorrhages, set against reference values in a table.

A single case, examined once, says nothing about how common these changes are in archers or whether they progress over the years: the authors acknowledge this and call for a study of more athletes. The link with shooting is a hypothesis built on the difference between the two hands and on ruling out other causes; there is no comparison with symptom-free archers or with girls of the same age who do not shoot, and no follow-up.

Above all, the paper does not say how she released. Compound archers usually shoot with a mechanical release aid, which takes the string off the fingers, whereas the description of the shot given in the introduction, with the string between the finger joints, is that of a finger release. Without knowing whether the string left her fingers or a release aid, the idea that string friction and vibration are the cause remains unproven. Finally, the swelling of the right hand reduced skin transparency on exactly the fingers examined, which can make the images harder to read.

For archers the study is a warning sign, not a measurement: a girl who trained for many hours a week had a swollen right hand, pain in both hands and capillary changes on just three fingers of her string hand, while capillaroscopy of her bow hand was normal. It suggests that persistent pain in the drawing fingers may have a cause other than simple tiredness, and that a simple, non-invasive test such as capillaroscopy can document what is happening to the small vessels.

It does not show how many archers have these changes, that archery damages the circulation in the fingers, or that changing technique would make any difference: the advice to reduce hand tension comes from the authors and was not tested. The proposal of regular capillaroscopy for competitive archers is also the authors' idea, drawn from a single case. Working out the cause of pain and swelling that do not settle is a doctor's job.