PTTD prognostication: Four criteria predict response to bracing

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In the moment: FootcareMay 2010 / News

Photo courtesy of Arizona AFO

By Jordana Bieze

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PTTD prognostication

Four criteria predict response to bracing

Four variables, identifiable at an initial clinical evaluation, can help predict

whether bracing will be successful in patients with posterior tibial tendon

dysfunction, according to research from the University of Rochester Medical

Center in Rochester, NY.

The investigators retrospectively reviewed records for 166 patients with PTTD,

41 of whom (24.6%) underwent surgery during the six and a half year study

period. The median treatment duration for the entire study population was 300

days; 60% of patients in the operative group had surgery fewer than 300 days

from initial evaluation.

Patients were more likely to eventually have surgery if at initial evaluation

they had a body mass index of less than 30, had previously used an orthotic

device, had undergone cortisone injection, or had symptoms for more than six

months.

In a logistic regression model, the sensitivity of these four criteria for

predicting eventual surgery was low, only 38.2%, but the specificity was high,

at 95.4%. This means that the four variables cannot be used to predict which

patients will need surgery, but that patients who meet none of the four criteria

are very unlikely to have a surgical outcome.

The findings, published in the March issue of Foot & Ankle International,

support the use of custom bracing for management of PTTD in patients who have

not previously used an orthotic device and fail to meet the other three

criteria. Patients in the nonoperative group were significantly more likely than

those in the operative group to progress to a " less aggressive " form of bracing

(for example, from a custom brace to an over-the-counter brace) during the

treatment period. The majority (60%) of those who went on to surgery tended to

stay in the brace they were initially prescribed, compared to 46.4% of those in

the nonoperative group.

Custom braces were prescribed at initial evaluation to a higher percentage of

patients in the operative group (33%) than in the nonoperative group (13.6%).

The authors hypothesized that this finding, along with duration of symptoms, may

be related to stage of PTTD at initial evaluation, which they were unable to

include in the statistical model because of incomplete data. However, pain at

initial evaluation did not differ significantly between the two groups.

A prospective study from the same institution, presented in March at the annual

meeting of the American Academy of Orthopaedic Surgeons, found that

supplementing brace treatment with a home strengthening regimen did not

significantly improve Stage II PTTD outcomes compared to bracing alone.

The study included 37 subjects, all of whom were treated with an over the

counter brace. In addition, 19 patients were randomized to an intervention group

that was prescribed 12 weeks of strengthening exercises. The other 18 patients

received passive treatment only.

Patients in the intervention group attended five sessions with a physical

therapist, then were instructed to continue concentric and eccentric

strengthening exercises at home for the remainder of the intervention period.

At six weeks, both groups had improved significantly on the Foot Function Index

and the Short Musculoskeletal Functional Assessment compared to baseline levels;

no further improvement was seen at 12 weeks. There was no significant difference

between groups for either outcome measure at either time point.

" The exercise did not appear to make a significant difference. Therefore, we

feel that bracing plays a larger role in the improvement, " said A.

Flemister, Jr, MD, associate professor of orthopaedic surgery at the university,

who presented the results at the AAOS meeting.

Researchers from the University of Southern California reported in the January

2009 issue of Physical Therapy that foot-specific eccentric exercises added to

the effectiveness of orthotic treatment of PTTD; however, those exercises

involved a custom-made device designed to isolate the posterior tibial tendon.