Plantar loading and risk of fifth metatarsal stress fractures in elite football players

Fifth metatarsal stress fractures are potentially career-ending injuries for professional football players and are therefore considered high-risk stress fractures. The reported incidence of this injury among football players is relatively high, while the average absence from football is between three to five months. This FastFact investigates possible risk factors for the development of this injury and suggests strategies for prevention.

Given the potential burden associated with this type of injury it is important to understand possible causative factors to allow clinicians to identify players that are at risk, and to better manage their treatment and rehabilitation. Currently identified risk factors include: being under the age of 25 years, during pre-season or early season, playing in the midfield, the non-dominant (stance) foot or having weak intrinsic foot muscles strength (especially toe flexors).

It is likely that vertical ground reaction forces and loading impact are also possible risk factors, however these are hard to objectively measure, especially during on-field game relevant movements. The current study involved the use of in-shoe insoles (with 99 capacitive sensors) to measure dynamic load in the foot during football-specific movements 1. Load was measured during a set-piece kick, curved run with ball interplay and during a straight-line run at 5.5 m s-1. Seven players who had suffered a primary stress fracture of the fifth metatarsal (and had been successfully treated) were compared with healthy controls.

Lateral foot plantar load was found to be significantly higher in the stress fracture group in the stance leg during the set-piece kick, or the inside foot when accelerating into a curved run. The lateral toes (2–5) showed much larger magnitudes of load in the fifth metatarsal fracture group for all three movements tested, peaking with the set-piece kick. Another interesting finding was that the majority (6/7 players) in the stress fracture group complained of prodromal symptoms (mostly vague lateral foot pain) prior to the development of their stress fracture.

These findings have some potentially important implications. Firstly, young midfielders who perform many high-velocity passes or set-piece kicks and complain of lateral foot pain, especially in pre-season, should be investigated promptly. Secondly, players returning from fifth metatarsal stress fractures should have their training loads closely monitored especially the volume of movements that increase lateral foot load. Similarly, players, who report lateral foot pain may be able to stay involved in training by doing straight line running and other movements that increase medial (not lateral) load such as cutting and sprinting. Lastly the lateral toes showed much larger magnitudes of load in the fifth metatarsal fracture group for all three movements tested. Strengthening of intrinsic foot muscles and the use of more support in the football boots can help absorb these large ground reaction forces.

To learn more about fifth metatarsal stress fractures, and foot injuries in general, complete the Foot module in the FIFA Diploma in Football Medicine.

Reference
1Thomson A, Akenhead R, Whiteley R, D’Hooghe P, Van Alsenoy K, Bleakley C. Fifth metatarsal stress fracture in elite male football players: an on-field analysis of plantar loading. BMJ Open Sport & Exercise medicine. 2018;4(1):e000377.

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