Jogger’s Toe: Is The Sock The Culprit?

Running for exercise became popular in the 1960s and grew in acceptance due to its accessibility and many health benefits.¹ Although there may be many positive health-related issues related to running, there are many problems that can occur in the toe including blisters, tinea pedis and unguium, ingrown nails, erythema, edema, onychoschizia, onycholysis, calluses, cuts and abrasions, paronychia, and subungual hematoma, commonly known as jogger’s toe.¹

In 1973, Scher described jogger’s toe as a subungual hematoma occurring in the first and second digit.² He felt the problem occurred due to pressure from the shoe gear and the longest toe, which in most cases is the second digit. Some authors believe that repetitive thrusting of the longest toe into the shoe box as well as downhill running is the main cause.³ This is also known as black toe. This problem can occur in many other sports such as soccer, tennis, basketball and football.⁴

The process begins with trauma causing erythema and edema. It then proceeds to separation of the toenail from the nail bed. A less severe form of jogger’s toe is known as subungual hematoma.² One should differentiate subungual hematomas from other conditions such as blood dyscrasias, fungus or trauma such as fractures or even melanoma.^2,4-6 A melanoma may extend into the proximal nail fold and the nail bed as well as the nail plate itself, and one should biopsy this if suspected.⁵

Preventative treatment for jogger’s toe includes wearing a shoe with an adequate toe box so the toe does not slam into the shoe. Joggers should also cut their nails properly to make sure they are not hitting the end of the toe box, which can cause additional damage.^5,6 Proper nail hygiene can also prevent abnormal distribution of the forces that can lead to further nail dystrophy. Treatment of subungual hematomas can consist of drilling the nail and evacuating the bloody tamponade. Also consider a nail avulsion.

A Closer Look At Sock Fit And Shear Forces
There is a question that we still need to answer. Is the trauma to the nail really caused by the shoe as the literature suggests or is it possibly caused by the sock?

Research has shown us that specialized socks are important to relieve plantar pressure and pain. In fact, one study showed a 32 percent reduction in pressure with wearing padded socks versus being barefoot.⁷ Additional studies have also shown that acrylic socks cushion better than cotton socks that can compress easily. Synthetic fiber socks are usually preferred to cotton socks because of the hydrophobic ability and moisture management abilities.⁷ Additional moisture can lead to swelling of the sock fibers, which can lead to fit issues and possibly lead to nail trauma.⁸

The main reasons we believe socks are involved in nail trauma of jogger’s toe are fit and shear forces. During running, the foot experiences a shear force during foot strike combined with momentum for a resultant translational force. This can lead to micromotion of the foot within the shoegear parallel to the ground. In the physiological position of the nail plate, this represents a shear force applied perpendicular to the attachment of the nail plate to the nail bed.

Anecdotally, similar findings have occurred clinically in the hammertoe/mallet toe, resulting in a shear force applied secondary to the toenail impacting the floor or sole of the shoe. The potential issues we discuss can be further exacerbated by the athlete’s technique of placing a foot with a stocking into the shoegear. A properly donned sock, prior to placing into the shoe, may be perfectly positioned but when the foot slides into the topline of the shoe, the friction of the shoe on the outer surface of the sock adds further tension on the sock and potentially bottoms out the sock’s elasticity.   

In a properly fitted shoe with adequate room in the toebox, the apex of motion would occur at the heel and topline of the upper or proximal portion of the vamp of the shoe at the ankle level. This serves as an anchoring point to the forward motion of the sock both dorsally and plantarly. This rearward tension progressively increases as the foot loads at heel strike and during the midstance phase of gait with the momentum of the foot translating the foot forward into the toes of the sock. This is what we believe to be one of the main causes for nail trauma during running.⁹

The other factors that can lead to nail dystrophy with a runner are sock sizing issues. Socks are usually designed to span three to four sizes. This can put additional pressure on the distal toes through the gait cycle of running. Having properly sized socks is critical to prevent pressure areas.  

In Conclusion
Socks that are too small may cause additional pressure forces on the digit but even a properly fitted sock can cause problems. This can lead to many of the issues related to jogger’s toe because of the thousands of microtraumas that are occurring while running. We have empirically observed that even when joggers wear oversized shoes, jogger’s toe can still exist.

Therefore, we propose a simple method to prevent jogger’s toe. When an athlete puts on the shoe, the sock naturally pulls tighter onto the digits, causing further compression. Following the donning of the sock, one creates a reservoir end for the toes by grasping the sock at the toes and pulling it distally. This prevents the pre-tensioning that occurs at the time of slipping on one’s shoes. The creation of accurate testing for such conclusions would be the next step in refining this technique and its resulting applications. As for our hypothesis, the cause of black toe is most likely multifactorial and not just the fit of the shoe with the sock being a major component.

Dr. Mozena is in private practice at the Town Center Foot Clinic in Portland, Ore. He is a Fellow of the American College of Foot and Ankle Surgeons, and is board certified in foot and ankle surgery. He is a Clinical Assistant Professor of Surgery at the Western University of Health Sciences.

Dr. Jones is in private practice at the Town Center Foot Clinic in Portland, Ore. He is a Diplomate of the American College of Foot and Ankle Surgeons, and is board certified in foot surgery. He is a Clinical Assistant Professor of Surgery at the Western University of Health Sciences.

References

1. Malta Purim KS. Sports-related dermatosis among road runners in Southern Brazil. AnBras Dermatol. 2014; 89(4):587-92.
2. Scher RK. Jogger’s toe. Int J Dermatol. 1978; 17(9):719-720.
3. Bordelon RL. Management of disorders of the forefoot and toenails associated with running. Clin Podiatr Sports Med. 1985; 4(4):717-723
4. Mailler EA, Adams BB. The wear and tear of 26.2: dermatological injuries reported on marathon day. Br J Sports Med. 2004; 38(4):498-501.
5. Adams BB. Running-related toenail abnormality. Phys Sports Med. 1999; 27(13):85-87
6. Adams BB. Jogger’s toenail. J Am Acad Dermatol. 2003; 48(5Suppl):S558-59.
7. Richie DH. Therapeutic hosiery: an essential component of footwear for the pathological foot. Podiatry Management. 2013; 32(8):155-162.
8. Herring KH, Richie DH. Friction blisters and sock fiber composition: a double blind study. J Am Podiatr Med Assoc. 1990; 80(2):63-71.

For further reading, see “How To Address Nail Bed Injuries” in the February 2006 issue of Podiatry Today. For an enhanced reading experience, check out Podiatry Today on your iPad or Android tablet.