August 2009

In the Moment: Foot Care

 

istock 7726517

istock 7726517

by Jordana Bieze Foster

Rehab enhances HV results
Post-op plan medializes weight bearing

Austrian researchers have found that rehabilitation following hallux valgus surgery can significantly improve weightbearing under the first ray, which has long been one of the barriers to full functional recovery.

Investigators from the Foot and Ankle Center Vienna analyzed 30 patients who underwent surgical correction of mild to moderate hallux valgus deformity, including 20 Austin osteotomies and 10 scarf osteotomies. Four weeks after surgery, all patients participated in a multimodal rehabilitation program, once a week for four to six weeks.

At six month follow-up testing, the researchers found significant improvement from preoperative levels for weight bearing at the great toe and first metatarsal head, first metatarsophalangeal joint range of motion, and function as measured by the American Orthopaedic Foot and Ankle Society forefoot questionnaire. The results were e-published on July 16 by Physical Therapy.

Plantar pressure analysis revealed that maximum force levels at the great toe increased from 66.1 N to 87.2 N, while the force-time integral increased from 18.7 N·s to 24.2 N·s—an indication that the first ray was not only able to bear more weight but could do so for longer periods of time. Similar improvements were seen at the first metatarsal head, where maximum force increased from 117.8 N to 126.4 N and the FTI increased from 37.9 N·s to 55.6 N·s. Mean AOFAS functional scores improved from 60.7 preoperatively to 94.5 at six months.

A limitation of the Austrian study is that it did not utilize a control group. However, several previous plantar pressure studies have documented a lack of weightbearing in the medial forefoot and first ray following hallux valgus surgery.

In a 2002 Foot & Ankle International study, researchers from the University of Wisconsin-La Crosse analyzed 25 patients one year after Austin osteotomy and found significantly decreased loading in the medial toe region, coupled with significant increases in the central forefoot.

Similarly, a 2006 British study published in the Journal of Foot & Ankle Surgery and a 2008 Italian study published in FAI both found significant decreases in load bearing at the hallux and overloading of the second and third metatarsals at long-term follow-up. The British study analyzed 22 Mitchell osteotomies and 22 scarf osteotomies a mean of 23 months post-surgery; load distribution under the hallux was better for the scarf procedures but still not comparable to normal controls. The Italian study analyzed 30 Austin and 30 Boc osteotomies a mean of 37 months postoperatively and found that the Boc procedure was associated with better load distribution under the second and third metatarsal heads than the Austin procedure; no control group was used.

The procedures with better load distribution were also associated with higher mean AOFAS functional scores (81.9 vs 86.4 in the Italian study, 74 vs 84 in the British study). However, the mean score of 94.5 in the Austrian study suggests that the rehabilitation protocol could offer a significant functional improvement over previously reported outcomes.

In addition to faciliating a more normal gait, well-distributed weight bearing following hallux valgus surgery can also potentially decrease the incidence of new callus formation under the middle metatarsal heads. In a 2006 study in Clinical Orthopaedics & Related Research, investigators from Baylor analyzed outcomes following a modified McBride procedure in 43 feet and found that average peak pressure under the second metatarsal head had increased at a mean of 29 months follow-up. Twelve 12 feet exhibited first metatarsal elevation of more than 2 mm, which was associated with diminished peak pressure and pressure time integral under the first metatarsal head and hallux. Of those 12 feet, five developed new second metatarsal transfer lesions.

Athletes with generalized joint laxity face risk of medial midfoot collapse

Athletes with high generalized joint laxity have an increased risk of medial midfoot collapse and may benefit from orthotic therapy, according to a study from Cincinnati Children’s Hospital.

Researchers measured generalized joint laxity in 112 female soccer players between the ages of 11 and 21, and found significantly greater midfoot loading in the 27 players with high generalized joint laxity than in the 85 players with low joint laxity. Hypermobile athletes demonstrated significantly higher levels of dynamic peak pressure and maximum force in the medial midfoot, for both dominant and nondominant limbs. Maximim force in the second metatarsal region of both limbs was also significantly higher in the hypermobile athletes.

The findings, published in the July-August issue of the Journal of Athletic Training, suggest that athletes with joint hypermobility should be evaluated for signs of medial midfoot collapse. Foot orthoses may help correct the athlete’s mechanics and lower the risk of related injury, such as medial tibial stress syndrome, ankle instability, patellofemoral pain, or stress fracture.

Vibration stimulus at the feet lowers gait variability, could prevent falls

Subsensory vibration applied to the soles of the feet significantly reduces gait variability in elderly individuals and may therefore also decrease the risk of falling, according to a Boston study.

In conjunction with the ongoing Mobilize Boston Study, researchers from the Hebrew SeniorLife Institute for Aging Research compared the effects of custom vibrating sandals in 12 healthy young adults, 22 elderly (average age 76.5) adults with a history of reccurent falls, and 19 elderly non-fallers.

The vibrations were associated with significantly reduced standard deviations for stride time, stance time and swing time in the recurrent fallers; stride and stance time variability was also significantly reduced in the older non-fallers. Nonsignificant decreases for all variables were seen in the young adults. The results were published in the July issue of Gait & Posture.

Previous research from the University of Toronto, published in the March 1997 issue of the Journal of the American Geriatric Society, found that increased variability in stride length, speed and double-support time was predictive of fall risk in older adults.

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