December 2009

Underuse, overuse both can lead to PTTD

by Cary Groner

Ongoing research into posterior tibial tendon dysfunction (PTTD) has revealed risk factors that include female sex, increasing age, overweight, unsupportive footwear, and even metabolic syndromes such as diabetes. Although typically associated with older, inactive patients, PTTD is also seen more rarely in young athletes.

The posterior tibial tendon is crucial to the gait cycle. If the tendon is impaired, the midtarsal joint destabilizes, pronation increases, and other problems follow. Regardless of whether PTTD occurs in a 50-year-old woman with diabetes or an 18-year-old basketball player, its characteristics are similar: collapse of the medial longitudinal arch, subtalar eversion, ankle valgus, and forefoot abduction.

“PTTD profoundly affects a patient’s life,” said Roger Marzano, CPO, CPed, who is in private practice with Yanke Bionics in Akron, OH.

Researchers and clinicians are developing better methods for assessing, classifying, and treating the disorder. Stage 1 is considered mild and is often addressed with articulated AFOs or foot orthoses. Stage 2 entails visible changes to foot structure and weakness, and may be treated similarly but with physical therapy added to the regimen. In Stage 3 the deformity becomes rigid and in Stage 4 the tendon may rupture; both phases may require more restrictive braces or surgery. Patients in the first three stages share pathologies, including a tight gastroc-soleus complex that stresses the metatarsal joint and the posterior tibial tendon.

Marzano has ideas about why PTTD is more prevalent in women.

“Women can’t wear structurally sound shoes during their employment years; they go through pregnancy, with the associated weight gain; and they tend to grow more knock-kneed with age, so the foot ends up adapting to the valgus changes in the knees,” he said.

Marzano occasionally sees younger athletes with the condition.

“In those cases, I usually find more forefoot abnormality creating the hindfoot stress,” he said. “There could be a short first metatarsal, forefoot varus, hypermobility of the first ray, or a cavus foot structure. The PTT tends to be shorter or tightened, so it doesn’t take much aggravation to get a tendonitic response.”

With those patients, Marzano favors a therapeutic approach beginning with a custom foot orthosis. If that fails, he shifts to a UCB-type orthosis. If patients end up requiring an AFO, they usually wear it for daily use or training, but not for competition because it is too restrictive.

In older patients, however, AFO use is common. Marzano tells of putting a 74-year-old nun into bilateral articulated AFOs for PTTD. She wore them for 13 years, then recently came back at age 87 for another pair.

“She wants them to last just as long,” he said, laughing. “She pointed her finger at me on the way out the door and said, ‘Don’t think I won’t be back!’”

Researchers at USC have developed a resistive exercise program for stage 1 or 2 PTTD that shows particular promise. According to Kornelia Kulig, PT, PhD, an associate professor of clinical physical therapy at the university, the approach involves hip extension and abduction exercises as well as eccentric exercises of the foot and ankle. For the research, she and her colleagues developed an apparatus that guides the foot as it resists movement toward abduction, but a resistive exercise band can do the job clinically.

“We think the eccentric loading allows better tendon remodeling,” she said. “If the musculo-tendinous unit undergoes eccentric loading, the muscle is less active, and the torque is produced by the tendon and connective issue.”

Kulig and her colleagues published their most recent results in Foot & Ankle International (Sept. 2009) and Physical Therapy (Jan. 2009). Although study subjects’ symptoms improved, their tendon morphology did not, and the researchers continue to investigate why.

“The message to both the patient and the practitioner is that even though they feel better, the [pathological] changes are still there,” Kulig said. “They shouldn’t abandon self-care.”

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