December 2011

Foot orthoses and landing mechanics

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By Katie Bell

Research suggests foot orthoses can affect frontal and transverse plane motion in proximal joints during landing from a jump, which could help decrease the risk of anterior cruciate ligament injury, especially in female athletes.

In the May issue of the Journal of Applied Biomechanics (JAB), researchers from East Carolina University (ECU) in Greenville, SC, reported that gender and foot orthoses affect frontal plane hip motion during landing from a vertical jump.

“Foot orthotic devices are able to change hip motion in the frontal and transverse plane,” said Walter Jenkins, PT, DHS, associate professor and chair of ECU’s Department of Physical Therapy. “Dysfunctional hip motion is commonly observed in patients with knee pathology.”

Researchers analyzed the 3D motion of the lower extremities in 36 study participants (18 women, 18 men) during a vertical jump with and without prefabricated foot orthoses. In the women researchers found significantly less hip adduction with foot orthoses compared with no orthoses (p< .05). The men showed no differences between foot orthoses conditions.

The apparent gender-specific proximal reactions to foot orthoses during landing may be related to kinematic landing strategies, which also tend to differ by gender, said Michael Joseph, PhD, PT, assistant professor in the Kinesiology Department’s Doctor of Physical Therapy program at the University of Connecticut.

“We have shown in our lab that men actually land in knee varus with their hip abducted and use hip adduction and knee valgus as a strategy to accelerate during the jump after the deceleration phase of landing. Therefore, an orthotic intended to decrease frontal plane adduction in men would be ineffective,” Joseph said. “Women have poor frontal and transverse plane control of their kinematic chain. A foot orthotic may be a simple solution—and quicker than neuromuscular retraining—to control motion. Ultimately, orthoses may be an excellent adjunct to a neuromuscular training program.”

In the March 2010 issue of the Open Access Journal of Sports Medicine, Joseph and colleagues reported that a 5° medial wedge reduced frontal, but not sagittal, plane motion during landing in highly trained female athletes. Hip adduction was reduced 1.98° (95% CI 0.97°–2.99°) with the wedge. In the 2008 issue of the American Journal of Sports Medicine, Joseph and colleagues had previously reported that the same medial wedge reduced ankle eversion and knee valgus in female athletes during landing. In both studies, kinematic data were collected from 10 college-aged women during drop-jump landings from a 31-cm platform with and without bilateral full-length medial posts.

Robert Weil, DPM, a sports podiatrist in private practice in Aurora, IL, suggested that custom foot orthoses are more effective for controlling motion during jump landings than prefabricated models.

“We’ve always known as sports podiatrists that proper custom orthotics affect all aspects of foot and leg function, including stability, balance, and crucial positions in push off and landing during jumping,” Weil said. “Athletes function more efficiently from A to Z when using proper custom orthotics. Prefabs are an ‘intelligent guess’ and that can make a big difference.”

In the November 2009 issue of JAB, researchers from ECU reported that foot orthotic devices decreased transverse plane motion during landing from a forward vertical jump in healthy young women, but that prefabricated and custom orthoses had different effects. The investigators analyzed 3D motion of the lower extremities of 12 female college students during a vertical jump with no orthoses, over-the-counter orthoses, and custom-made orthoses. Compared with no orthoses, the women had significantly less internal rotation at the hip (p< .05) with over-the-counter orthoses and significantly less tibial internal rotation (p< .05) with custom-made orthoses.

“The fundamental question of how orthotics work remains unanswered. Is there a simple wedge effect in which motion is limited at the foot, which transfers a limitation of motion up the kinematic chain or is there a neuromuscular mechanism modulating motion?” Joseph said. “The difficulty with studying custom-made orthotics is the variability of fabrication methods.  Extreme variability exists in evaluation and prescription of posting as well as in orthotic materials.”

Sponsored by an educational grant from Ortho-Rite

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