Adherence, expressed as a percentage of the recommended number of hours, ranged from 5% to 125% for all patients (median, 62%) (Table III). The median adherence among the 4 groups ranged from 41% to 76%, with the youngest and oldest patient groups being most adherent, and the middle 2 groups (the 1 and 2-year-old patients) being the least adherent.
Accuracy of Parent-Reported Brace Use
Parents reported an average of 11.3 hours per day of brace use (median, 11.5; and SD, 3.6 hours per day). Again, this was higher than the total measured brace use of 8 hours per day (median, 8; and SD, 5 hours per day). The difference between the parent-reported brace use and the measured use was significant for the 3 youngest patient groups (p ≤ 0.013) (Fig. 4).
The parent-reported accuracy of brace use ranged from 6% to 213% of the measured brace use for all patients (median, 77%). The median parent-reported brace use among the 4 groups ranged from 57% to 108% of the measured brace use, with the parents of the oldest patients being the most likely to underestimate brace application, as indicated by a median value of >100% (Table III).
Influence of Adherence on Relapse
Eight (18%) of the 44 patients who were monitored for the complete study period demonstrated relapse at their follow-up appointment; the mean measured brace application for those patients was 5 hours per day (median, 4; and SD, 3 hours per day), which was significantly lower than for those who did not relapse (mean, 8; median, 9; and SD, 5 hours per day) (p = 0.045) (Fig. 5). The mean adherence among patients who relapsed was 40% (median, 27%), whereas among patients who did not relapse, the mean adherence was 64% (median, 76%). The mean accuracy of parent-reported use among patients who relapsed was 70% (median, 47%), with a mean parent-reported use of 72% (median, 80%) among patients who did not relapse during the period of observation. Of the 4 patients who did not complete the study, 3 experienced a relapse of deformity at their follow-up appointment.
Adherence to the post-corrective clubfoot brace protocol has been stated to be the most important factor contributing to a successful outcome, and a lack of adherence is generally thought to be the most common cause of relapse3-19. Using various definitions, several studies have reported rates of nonadherence to brace use ranging from 32% to 61% of the recommended number of hours3-5,7-9,11-13. All of these studies relied on caregiver estimates of daily hours of brace use to determine nonadherence.
The present study showed that objectively measured post-corrective brace use was a median of 62% of that recommended by the physician. Furthermore, the estimated hours of brace use reported by the parents was a median of 77% of the measured use. On average, parents were instructed to apply the brace for 12.6 hours per day. They reported an average of 11.3 hours per day; as measured, brace used averaged 8 hours per day. For patients in the youngest 3 age groups (<3 years of age), families reported significantly higher brace use than was measured (p ≤ 0.013); however, for patients between the ages of 3 and 4 years, the difference between reported and measured brace wear was not significant (p = 0.468), indicating that parent-reported adherence was more accurate for older patients (Figs. 3 and 4).
Eight of the 44 patients who were monitored for the complete study period demonstrated relapse at their follow-up appointment. For those patients, the mean measured brace use, 5 hours per day, was significantly lower than the mean use among those who did not relapse, 8 hours per day (p = 0.045) (Fig. 5). This finding supports previous observations by investigators who reported an association between inadequate brace use, as reported by parents, and relapse3-19. However, the present study was the first, to our knowledge, to objectively quantify the relationship between brace wear and relapse. While the number of patients in the present study was perhaps too small to precisely determine the necessary number of hours—or brace dose—needed to prevent relapse, the results suggest that 8 hours or more of daily brace use may be helpful to prevent a relapse. Additional studies with larger cohorts will be needed to determine more accurately the minimum number of bracing hours necessary to curtail the frequency of relapse of deformity.
Heat25-30 and pressure31,32 sensors, embedded in orthoses, have been successfully used to accurately monitor brace wear in children with adolescent idiopathic scoliosis, which has led to several key advances in the treatment of scoliosis. Katz et al.26 used objectively measured brace-adherence data to determine a dose response, specifically, the rate of curve progression as a function of brace use. Those authors were able to demonstrate that, among 82% of the patients who wore their brace for ≥12 hours per day, the curves did not progress. More recently, Karol et al.33 reported that patient-specific data on brace adherence were effective for counseling patients and their families, thereby improving compliance and treatment outcomes, a strategy that may have future applicability to the families of patients with clubfoot.
To our knowledge, there has been only 1 previous article describing the objective measurement of clubfoot brace use. Morgenstein and colleagues20 used pressure sensors to monitor brace wear for a small group of patients. They found a mean adherence percentage of 91.7% in the first month of brace use (n = 15), which declined to 77.1% by the third month (n = 7). The authors concluded that mean adherence declined significantly; however, their study did not address adherence beyond the initial 3 months of use. In contrast, the present study was designed to quantify adherence over the entire course of brace treatment. This information may be beneficial to the clinician in interpreting parental reports of brace use.
There were several limitations of the present study. First, due to size limitations and the duration between patient visits, the sampling rate of the sensors was limited. However, the differences between the median recorded daily hours of brace use by patients who experienced relapse and those who did not was 5 hours, significantly larger than the effective resolution of our data logger, which was approximately 45 minutes. Second, this was a cross-sectional study, monitoring patients in several age groups, between 2 consecutive visits. Ideally, a longer-term longitudinal study may provide more information regarding brace-adherence patterns over time as a function of age. Third, findings pertain to a single institution with a single treating surgeon and a patient population composed largely of low-income families (88% with an annual family income of <$40,000; Table I), which may not be representative of the general population. Fourth, since the optimum number of hours of brace use to prevent relapse is not yet known, our recommendations for daily brace use were based on sleep patterns of infants and children as recommended by Ponseti22. Lastly, this study included only 1 post-corrective brace design.
In conclusion, this study objectively quantified the number of hours of brace wear among patients with clubfoot. Our findings showed that there was a difference between physician-recommended and actual brace use and that parent-reported use tends to be overestimated, particularly in younger patients. These observations indicate that routine brace monitoring has the potential to accurately identify patients who are receiving an inadequate number of hours of brace use and facilitate more effective counseling of these families. We also found that the patients who wore the brace more than 8 hours per day were less likely to experience relapse than those who wore it less than 5 hours per day. Larger studies are needed to more precisely establish the number of hours of post-corrective brace wear needed to reduce the occurrence of relapse of deformity. Currently in our practice, our findings assist us in better estimating actual brace use based on the parental report. Once better sensors and data retrieval systems are devised, we hope to routinely monitor all patients in the future.
A table showing the data collected and analyzed for patients in the study cohort is available with the online version of this article as a data supplement at jbjs.org.
NOTE: The authors thank Sanghun Alejandro Chung, MS, and Brice Lekavich, MS, for assistance with sensor testing and validation; Mohammad Nazif, BS, for assistance with data analysis and manuscript preparation; and Michael Jew, BS, and Shannon Cooper, BS, for assistance with clinical data collection.
Investigation performed at the J. Vernon Luck, Sr., MD, Orthopaedic Research Center at the Orthopaedic Institute for Children, Los Angeles, California
Disclosure: The study was funded by a 2014 Pediatric Orthopaedic Society of North America clinical research grant. Braces were donated by MD Orthopaedics, Wayland, Iowa. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article.
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