Musculosketal Studies Lower Extremity Overuse

Musculosketal Studies

Lower extremity overuse injuries and flat feet:

Patellofemoral pain syndrome, iliotibal band syndrome, and metarsal stress fractures

Traditionally, 'flat feet,' or feet not possessing a normal arch, have been associated with a variety of orthotic conditions affecting the lower extremities. This is because the position of the foot affects the individual's entire gait. Flat feet can be a particularly detrimental condition, previous literature suggests, for individuals involved in the sport of running, or for military recruits who must run and march for long periods of time and long distances. Repetitive stress exacerbates the orthopedic difficulties experienced by individuals with flat feat. A 1982 study of 50 runners with chronic orthopedic disorders found that 44% had flat feet, as opposed to 29% who were normal-arched and 32% with high-arched feet. A 1981 study of 4,000 patients seeking treatment at an orthopedist's office found that 40% had flat feet. While the "only established causative factor" in running injuries is miles per week, it has been commonly assumed that there is a strong correlation between flat-footedness and a high incidence of injuries (Hunter, Dolan & Davis, 1995, p. 30).

The knee pain known as patellofemoral pain is extremely common, especially in runners and other sports where overuse injuries tend to occur. The likelihood of flat-footedness being an exacerbating factor for such knee pain seems logical. When feet do not have strong arches the foot has a tendency to roll inwards or pronate which means the knee has to compensate for the inward movement more than an individual with normal-arched feet (Patellofemoral pain, 2008, Patient UK). "Over-pronation occurs when there is excessive mobility in the sab-taler joint of the foot which causes hyper-mobility of the foot. The increased mobility causes the medial arch to flatten out and causes the foot to roll in too much while walking and running. This increased mobility adversely affects all the muscles in the foot and can even affect the lower leg, upper leg and cause back pain. This mechanical imbalance is highlighted during running due to the increased forces being applied to the body. Orthotics are often prescribed for such individuals to lessen the pain" (Flat feet and running, 2008, Runner's rescue).

However, iliotibal band syndrome is more often associated with cavus, or high-arched feet than flat feet. High-arched feet tend to under-pronate, which lessens the ability of the body to absorb the shocks of pounding the pavement (Hunter, Dolan & Davis, 1995, p.31). IB syndrome is usually "characterized by a sharp burning pain on the outer side of the knee, just below the joint line. Pain may be localized at the side of the knee, or it may radiate up the side of the thigh. The pain worsens with continued movement, and resolves with rest. The knee may feel like it 'snaps' when it is bent and then straightened. Some individuals may also experience a 'snapping hip,' in which the muscles that cross the outside of the hip feel like they snap or click while walking or running" ("Iliotibal band syndrome," 2008, Caring Medical & Rehabilitation Services).

However, while the lack of shock absorption of a high-arched foot may exacerbate the danger of developing IB syndrome, flat-footed individuals are not immune. As with knee pain, a variety of physical and environmental factors can lead to the development of the syndrome, such as high mileage, leg length, stiff muscles, muscle imbalance, flat feet or poor foot structure and pronation (inward and downward tilting of the foot). Running on pavement that is cantilevered, such as on a road that is designed to 'run off' rainwater, is more apt to be a culprit in developing patellofemoral pain, regardless of the individual's foot type, while running downhill may exacerbate the tendency of an individual to develop IB syndrome. Improper running shoes for the individual's foot type can also exacerbate both conditions -- inflexible new running shoes again heightening the chance of developing IB syndrome (Hunter, Dolan & Davis, 1995, p.31).

Stress fractures are another common orthopedic plague. They are small fractures of the bone that develop over time, again often from overuse activities like running. Medical literature suggests that certain foot types are more apt to develop stress fractures in certain places than other areas of the body. For example, some believe that flat-footedness may actually guard against overuse injuries in certain places. One clinical study of fifty healthy subjects -- 34 with normal feet, 16 with flat feet -- walked and ran five trials each at standard speeds. An "assessment of impact found that biomechanically, individuals with a flat foot could be at a lower risk for lateral column metatarsal stress fractures, indicating that foot type should be assessed when determining an individual's risk for metatarsal stress fractures" (Chuckpaiwong, Nunley, Mall, Queen 2008, p.403). Outside of the 'laboratory,' individuals with cavus or high-arched feet seem more apt to contract 'Jones' fractures of the proximal fifth metatarsal, which do not heal well, as well as femoral and tibial stress fractures (Hunter, Dolan & Davis, 1995, p.30-31). However, a 1989 study of military recruits suggested that flat-footed individuals are more prone to metatarsal stress fractures, while high-arched individuals are more prone to tibial and femoral fractures Hunter, Dolan & Davis, 1995, p.30).