Find the Right Pulley Splint
The internet is a powerful tool to query, but too much information can be confusing.
This article is written to address questions you may have regarding a pulley injury and to review the splint choices available so you can choose wisely.
What Splint is Best After Sustaining a Flexor Tendon Pulley Injury?
When and why do I need a finger splint?
The goal of wearing a splint, after a pulley injury, is to keep the flexor tendons next to the finger bone, (phalanx), to which the pulley is attached, so that it can heal in as close to its original size as possible. Tape alone will not work! To better understand this statement, please take a look at our research in the science section of the site.
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In uninjured fingers the A1 – A5 pulleys hold the flexor tendons close to the bones, (MC: metacarpal; PP: proximal phalanx; MP: middle phalanx; DP: distal phalanx), like guides on a fishing pole hold the line close to the pole. The A2 pulley is the strongest and most important pulley, but sadly the most frequently injured in climbers; (A4 is the second most commonly injured pulley in rock climbers).
How are finger pulleys injured?
Injuries happen most commonly when using the crimp grip, like one would use on a small hold. The finger joint at the first knuckle, (proximal interphalangeal joint), is flexed more than 90 degrees. This puts lots of stress on the A2, A3 and A4 pulleys, and if a foot slips or a foot hold breaks, or the climber dynamically loads the finger, the pulleys get “shock loaded” and can rupture or tear. If this happens the flexor tendons pull away from the bone increasing the tendon-phalanx distance, (TPD), as indicated by the *’s below.
If the A2 pulley tears, further climbing or strenuous use of the hand will put extra strain on the A3 and A4 pulleys, (see arrows on left diagram), putting them at risk for rupture. A4 pulley tears will in turn put extra strain on the A3 and A2 pulleys, (see arrows on right diagram).
Without real support the injured pulley will always heal in a stretched-out position. This is because the finger flexor muscles in the forearm pull the flexor tendons in a straight line towards the forearm, unless constrained by a pulley, and there are no forces to change this physical phenomenon.
The asterisks in the diagrams above demonstrate the gap between the tendon and the phalanx, and the brackets in Figures A and B below also represent this distance in a cross-sectional view. This tendon-phalanx-distance (TPD) can be measured with ultrasound (or MRI) and decreases with the application of a pulley splint.
Stretched out pulleys can lead towards recurrent tendonitis in the flexor tendons, (inflammation after use), of the finger as tendon biomechanics are altered. Furthermore, stretched out pulleys can lead to larger loads being applied to neighboring pulleys when climbing in the future, putting them at additional risk for injury.
What finger splint options are available?
Option 1: An injured climber can go to see a certified hand therapist and they can make a splint for you. In this case you may or may not get a great device, but in most cases it should work. Many hand therapists have little contact with climbers, and don’t really understand the forces climbing puts through the fingers. This option may or may not be covered by your insurance, so be sure to check on this beforehand as the cost will likely be several hundred dollars.
Option 2: You can follow the instructions given by Jared Vagy, DPT on his website and make a Pulley “Protection” Splint. This device was invented by Micha Schneeberger B.S. and Andreas Schweizer M.D who published their experience treating 47 climbers with pulley injuries over a 6-year period in: Wilderness & Environmental Medicine, 27, 211–218 (2016). The design is thoughtful of the finger anatomy and should minimize compression of the nerves and blood vessels which makes good common sense. Their results are very good, and the design has proven itself over time. Unfortunately, it is bulky to wear and uncomfortable to climb with – which a climber will return to as time goes by and the pulley is ready for some loading, but still needs protection. Moreover, it is complex and time consuming to make and Dr. Vagy estimates the cost at $50-$400 depending on what equipment and supplies you need to buy.
Option 3: You can get a selection of pre-molded Pulley “Protection” Splints from Nice Climbs. Their product called “Pulley Pals” are available from Amazon for about $20. This option saves you time and money if this design suits you. The downsides are a less custom fit and a similar bulky, uncomfortable splint.
Option 4: You can buy a ring to support your pulley. This may be a comfortable solution, but unfortunately it will not support the pulley as the joint (knuckle) above the compromised A2 or A4 pulley has a bigger circumference than the middle of the phalanx where the pulley lives, so you get a comfortable solution that won’t reduce the tendons to the bone or reduce the TPD - for about $82.
Option 5: You can buy a custom Semilunar Pulley Orthosis (S.P.Ort). This kit allows you to make at least 2 custom supports that can be closed down around the middle of the phalanx, decreasing the TPD, while supporting the pulley as it heals. See Figures A and B below, and compare the TPD.
Tape alone - in any configuration - is not a viable option if you want close to anatomic healing.
Figure A
Figure B
The included instructions are straightforward, and there are helpful videos on how to make your S.P.Ort on our Customizing Your S.P.Ort page.
While there are not expansions for the neurovascular bundles on the S.P.Ort we have not found these to be necessary after treating thousands of pulley injuries. This became apparent to me when patients of mine came to the operating room with wedding bands on their finger overlying the A2 pulley, that had not been removed for decades. These rings couldn’t be removed over the neighboring knuckle and could barely spin around their fingers. They had no sign of nerve or vascular compromise in the finger with a really tight band on the middle of their proximal phalanx, for many years. (Because of swelling concerns after surgery, we had to cut off the rings before surgery.) Therefore, it is not an oversight that we do not recommend these medial and lateral expansions. They are simply not needed. Moreover, not having these expansions makes the S.P.Ort much more form-fitting and more comfortable to wear. Given the need to wear a support full-time for 2 months to allow for healing, and another 2 months part-time when climbing or doing heavy manual work, comfort (which leads to compliance) matters.
What happens if I don't treat my pulley injury?
What is the bottom line with pulley splints for climber's finger?
Almost every serious climber I know has injured a pulley (or a few) along the way, and the vast majority of us are still climbing. Don’t despair, you will get back in the game!
Invest in the pulley support that makes the most sense to you, wear it religiously and give your pulleys time to heal – at least 8 weeks.
I purposely avoid the term pulley “protection” splint, because none of these devices will allow you to keep working your project with a sore pulley and protect it from rupturing! They will support the pulley as you give it time to heal and spend some time training your chest and triceps, doing stretches or yoga and improving your aerobic fitness. Eventually you will CLIMB ON!
Physics lovers who want to investigate the pulley forces involved further can look up studies done on pulley biomechanics and related free-body diagrams: Lin, G.-T. et al. Functional anatomy of the human digital flexor pulley system. Hand Surg., 14A: 949-956,1989; Marco, R.A. et al., Pathomechanics of closed rupture of the flexor tendon pulleys in rock climbers. Journal of Bone and Joint Surgery A 80, 1012-1017, 1998.