August 2010

Orthoses relieve PFPS

In the moment: Footcare

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Key variables predict response

By Jordana Bieze Foster

Prefabricated foot orthoses improve the ability to perform weight-bearing knee flexion tasks in patients with patellofemoral pain, according to research from La Trobe University in Australia.

Christian J. Barton, a PhD candidate in the university’s Musculoskeletal Research Center, and colleagues  assessed 52 subjects with patellofemoral pain as they performed three tasks designed to replicate movements that are typically painful in this patient population: single-leg squats, step downs, and single leg rises from sitting. Tasks were performed with and without prefabricated foot orthoses, which were three-quarter length with lateral cut-outs, fabricated from medium-density ethelyne vinyl acetate with build in arch supports and 4° of varus wedging.

Of the 37 subjects who were unable to complete 25 pain-free step downs without orthoses, 21 (57%) improved their ability to perform the task without pain after being given the orthoses. Of the 41 subjects who were unable to complete 20 single-leg rises from sitting without orthoses, 16 (38%) improved with the orthoses. Of the 43 subjects who experienced pain during the single leg squat test without orthoses, 18 (41.8%) reported a positive change in pain with the orthoses, and 69.2% of the entire 52-subject study population reported that orthoses made the squat task easier. The findings were e-published on July 20 by the British Journal of Sports Medicine.

A pronated foot type, as measured by the Foot Posture Index, was associated with reduced pain and ease of movement when performing  a single-leg  squat  and a greater number of pain-free single-leg rises from sitting with orthoses. This finding supports the theory that the pronation control offered by foot orthoses decreases patellofemoral pain by realigning the lower extremity, limiting medial collapse and reducing patellofemoral joint stress.

The researchers did not control for footwear; subjects were tested in the footwear they associated with painful symptoms. Analysis revealed that footwear with low levels of motion control were associated  with less pain during a single-leg squat and a higher number of pain-free rises from sitting with orthoses. This may suggest that PFPS patients who wear unsupportive shoes have more room for improvement, although it’s unclear whether simply providing them with better footwear would be as effective as prescribing orthoses.

The same research group discovered similar themes in a study, presented in June at the annual meeting of the American College of Sports Medicine, looking at which factors would predict the effectiveness of 12 weeks of orthosis wear in patients with patellofemoral pain.

Of 60 patients with PFPS enrolled in the study, 57 completed the 12 weeks. Of these, 67% reported at least a moderate improvement in symptoms on the five-point Likert scale, and 25% reported a marked improvement with the orthoses. The strongest predictor of marked improvement was reduced pain with orthoses during a single leg squat, which increased the probability of marked improvement to 45%. Other predictors of marked improvement were poor footwear motion control as measured using the Footwear Assessment Tool, baseline usual pain of less than 22 out of 100 on a visual analog scale, and ankle dorsiflexion with the knee flexed of less than 41.3°. Meeting at least three of these four criteria increased the probability of marked improvement to 78%.

The fact that lower pain levels were more likely to be associated with marked improvement suggests that foot orthoses alone may only be an appropriate treatment approach for subjects with milder patellofemoral pain symptoms. Limited ankle dorsiflexion may be important because of its reported association with delayed peak rearfoot eversion, which is thought to increase patellofemoral joint stress by increasing tibial and femoral rotation in the transverse plane. The orthoses, designed to control pronation, may also address rearfoot eversion patterns.

For comfort and stability in running, skip sixth set of eyelets when lacing

A seven-eyelet lacing technique that skips the sixth set of eyelets may offer the ideal combination of perceived comfort, stability, and reduced peak dorsal pressures in runners, according to research from the University of Duisberg-Essen in Germany.

Researchers surveyed 14 male runners, all rearfoot strikers, about their perceived comfort and stability while wearing running shoes laced in four different patterns: six eyelet laced normally, six eyelet laced tightly, seven eyelet, and seven eyelet minus the sixth set (A57). They also used a pressure measurement insole under the tongue of the shoe to assess peak dorsal patterns during running.

The runners perceived the seven-eyelet lacings and the tight six-eyelet lacing to provide the most stability, while the A57 and regular six-eyelet techniques were perceived to be most comfortable.

The researchers found that reduced dorsal pressure on the talus, navicular bone, and extensor tendons was related to perceived comfort. Those peak pressure values were lower for the A57 lacing technique than when all seven eyelets were laced.

The findings were published in the July issue of Research in Sports Medicine.

Australians confirm feet of obese children are both fatter and flatter

Research from the University of Wollongong in Australia confirms earlier reports that the feet of obese children are likely to be flatter (not just fatter) than those of non-obese children.

Investigators measured internal longitudinal arch height and medial midfoot plantar fat pad thickness in 75 obese primary school aged children and 75 matched non-obese children.

In fact, the obese children’s feet were fatter: mean medial midfoot fat pad thickness was significantly greater in the obese children both during weightbearing (4.7 mm vs 4.3 mm) and nonweightbearing (5.4 mm vs 4.6 mm). But the fatter feet were also flatter: medial longitudinal arch height averaged 23.5 mm in the obese children compared to 24.5 mm in the non-obese children.  All differences were statistically significant.

The findings, e-published on June 22 by the International Journal of Obesity, are consistent with those of an earlier, smaller study  from the same university. In the November 2006 issue of Obesity, the Wollongong researchers reported lower arch heights and thicker fat pads in overweight preschool children compared to their leaner counterparts.

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