Nearly 40% of total injuries suffered by high school athletes are reported to be ankle injuries.1 Ankle injuries have been shown to affect ankle dorsiflexion range of motion (DROM).2 Decreased DROM has been correlated with an increased risk of plantar fasciitis and patellar tendinopathy, as well as increased risk of future injury.3–5 It can also have a deleterious effect on gait and landing mechanics and afferent joint sensory input.2,4 Previous ankle injuries1 and resultant decreased DROM4 are risk factors for future injury.2 This creates a need for an ankle dorsiflexion screening tool that could be used in preseason screening and rehabilitation to effectively identify individuals with decreased DROM.
Ankle DROM has been traditionally evaluated in an open chain position. However, in a literature review by Martin and McPoil,6 open chain DROM measurements were shown to have poor reliability. Furthermore, ankle dorsiflexion is used primarily through closed chain activities.7 The presence of closed chain ankle dorsiflexion allows the body to advance over the foot during gait8 and other athletic movements.2,4 Due to this, clinicians have incorporated closed chain ankle DROM measurements to test ankle DROM in a more functional position.3,9 Previous studies have investigated closed chain dorsiflexion using a modified lunge position.9–12 These studies observed that the modified lunge test had excellent inter-rater reliability and a low level of error.9,12 Performing the weight-bearing lunge test requires the use of ancillary objects such as a wall or flat surface perpendicular to the floor to complete the measurements.9,12,13 Closed chain DROM has also been examined using a half kneeling dorsiflexion test (HDT).5 Although the HDT has shown the ability to determine closed kinetic chain DROM, it can be time-consuming and difficult to perform. The HDT requires an inclinometer for correct scoring. Although measuring closed chain ankle dorsiflexion is a more functional test, it can be difficult to quickly screen the ankle in group pre-participation physical examinations or when determining the effectiveness of an intervention. No screen currently exists to quickly examine closed kinetic chain DROM. The use of a closed chain ankle DROM screen could allow for quick identification for those with closed chain range of motion deficits. Therefore, there is a need to evaluate the efficacy of a novel closed chain ankle DROM screen.
The purpose of this study was to determine the reliability and the criterion validity of a novel standing ankle dorsiflexion screen (SADS) in comparison to the HDT. It was hypothesized that there would be a distinct difference between SADS dorsiflexion ordinal scoring and the HDT DROM measurements. This study compares the criterion measurements of the SADS and the continuous measurements of the HDT. This finding will enable performance and health care professionals to screen dorsiflexion quickly to determine if further evaluation is necessary.
Thirty recreational adults (13 men and 17 women) with a total of 60 non-symptomatic ankles participated in this study. Participants were included if they did not report pain during testing and were unrestricted in all exercise activities. Participants were excluded if they reported a current injury or pain in the back, hips, knees, or ankles, reported a back or lower extremity injury in the past 6 months, or had ever incurred a back or lower extremity surgery. Each participant was informed of the risks and benefits of the study and gave consent to participate. The University's institutional review board approved this study.
For each participant, a coin was flipped to randomly determine the testing order of the SADS and the HDT. The SADS was completed in a standing heel-to-toe position. Participants held a dowel in the contralateral hand for balance. They were instructed to maintain a heel-to-toe position to drop straight down, to bend the knee, and take the back knee as far as possible beyond the toes, while maintaining heel contact with the ground. DROM of the back ankle was scored in relation to how anterior the back knee aligned relative to the medial malleolus of the front ankle (Figure 1). The SADS was scored on an ordinal scale: behind, within, or beyond the malleolus.
Modified Weight Bearing Lunge Test. The participant is given a dowel for balance. Standing in a heel-to-toe position, the participant keeps the back heel down and brings the back knee forward as far as possible. The tester measures the knee in relation to the medial malleolus on the front ankle: behind, within, or beyond.
The HDT was performed with the patient in a half kneeling position, placing a digital inclinometer just inferior to the tibial tuberosity on the forward leg. Participants were instructed to maintain an upright posture and to bring their knee forward, aligned with their second toe, as far as possible without lifting their heel off of the ground (Figure 2).5
Half Kneeling Dorsiflexion Test. The participant assumes a half kneeling position. Keeping the front heel down, the participant advances the front knee as far as possible over the front foot. The tester measures the degrees using an inclinometer.
Prior to testing, participants' height and body mass were recorded. All raters were trained by a physical therapist skilled in the SADS procedures and scoring criteria prior to testing. A third party recorded all measurements, and examiners were blinded to each tester's results. Two raters performed all HDT ankle DROM measurements using a digital inclinometer. Measurements were recorded two times for each ankle, with 5 minutes between measurements.10 Four raters measured the SADS criteria of behind, within, and beyond. Measurements were obtained two times per ankle, with 5 minutes of rest between measurements to prevent a treatment effect.10
All measurements (SADS and HDT) were obtained two times per side, with 5 minutes of rest between measurements to prevent a treatment effect.10 A third party recorded all measurements. Each HDT measurement was recorded and then averaged for analysis, and frequency counts were obtained for each category of the SADS.
Each ankle was treated as an individual subject; as a result each participant contributed two subjects (two ankles) to the analyses. Mean and standard deviation measurements were analyzed for height and body mass. Intraclass correlation coefficient (ICC) with a 95% confidence interval was used to determine interrater reliability for digital inclinometer HDT measurements, where a score of less than 0.40 was deemed poor, 0.40 to 0.59 moderate, 0.60 to 0.74 good, and greater than 0.75 excellent.14 Kappa coefficients were used to determine interrater reliability for the SADS criteria. Criterion validity was assessed using a one-way analysis of variance with three independent levels (behind, within, and beyond) comparing to the dependent HDT ROM. Tukey post-hoc analyses were used to identify specific group-to-group differences (P < .05). All statistical analyses were analyzed through JMP software (version 13.0.0; SAS Institute, Inc., Cary, NC).
The mean height was 174 ± 10.7 cm and the mean body mass was 76 ± 18.7 kg. There was excellent interrater reliability of 0.95 (ICC: 0.92 to 0.97) for HDT digital inclinometer measurements. The kappa coefficients for SADS criteria of a single trial were 0.61 to 0.81. The SADS percent agreement ranged from 86% to 96%.
There was a statistically significant difference between the HDT and SADS (P < .01). The mean HDT measurement for the SADS score was 33.5 ± 2.0 degrees for behind, 38.6 ± 1.2 degrees for within, and 43.0 ± 0.78 degrees for beyond. Tukey post-hoc analysis revealed a significant difference comparing SADS scores of beyond and behind (P < .01) and beyond and within (P = .01). No differences were observed comparing SADS scores of within and behind to those of the HDT (P = .08).
The prevalence of ankle injuries continues to plague athletics, resulting in an effect on ankle DROM.2 Researchers have shown that decreased ankle DROM can affect gait patterning, landing mechanics, and sensory input2,4 and lead to an increased injury risk.13 The results of this study suggest that a novel ankle dorsiflexion screen is able to discriminate between individuals with differences in ankle DROM. Supporting the hypothesis, significant differences were shown when looking at measurements comparing beyond and behind the malleolus and within and behind when looking at the SADS. However, there was no significant difference between within and behind the malleolus measurements.
Although this study used methods similar to those of previous studies, there were some differences. Previous studies used a wall to measure the distance the knee passes over the toe and to determine maximum closed chain dorsiflexion.11,12,15,16 Our study provided a more efficient method by using criterion measurements relative to the medial malleolus on the opposite leg. This method did not require changing positions or repeated set-up procedures as were seen in the previous studies.
DROM averages observed during the SADS were similar to those found in previous studies.11,13 The beyond average score measurement was 43 degrees. This average is comparable to those found in previous studies for healthy individuals11 and male military recruits undergoing 12 weeks of intensive training.13 Previous studies have suggested that DROM restrictions exist after ankle sprains.15,17 Studies have also found that decreased range of motion may lead to ankle sprains.13
One study13 found that DROM less than 34 degrees was associated with greater injury risk in army recruits. The authors discovered a five times greater risk of an ankle sprain in individuals with poor ankle DROM compared to those with normal ankle flexibility. Furthermore, their findings for reduced ankle DROM were similar to our measurement of behind the malleolus, which averaged 33.5 degrees. These similar results illuminate that the SADS may identify individuals with an ankle DROM insufficiency in a functional position.
Although significant differences were present when comparing beyond and behind and within and behind the malleolus, no difference was found between beyond and within the malleolus or between within and behind. In a previous study, DROM of the ankle, knee, and hip had an effect on single leg stance.16,18 This implies that during the SADS there may be contributing factors that affect the SADS measurement other than DROM alone. Previous studies have proposed that neuromuscular control plays a role in determining stiffness and flexibility during multi-joint movements.19,20 Neuromuscular control may alter stiffening strategies to help control movement.21 Hodges and Moseley20 observed that patients with low back pain used increased lumbar spine muscular stiffness strategies to overcome spinal stabilization requirements compared to pain-free individuals. The presence or lack of lower extremity neuromuscular control during the SADS may affect the final measurement. In our study, if a patient has difficulty balancing or controlling the lower extremities, he or she may have used a neuromuscular stiffening strategy and thus displayed decreased ankle DROM.
Because research shows 43 degrees is normative for healthy, active individuals and 34 degrees increases injury risk,13 the within measurement of 38 degrees falls within these cut-points. This finding suggests that a within measurement cannot be determined to be an adequate or inadequate ankle DROM measurement.
This study had limitations. We used a sample of asymptomatic adults; therefore, these findings cannot be used as general results for different populations. Drewes et al.2 looked at the effect chronic ankle sprains have on DROM. Participants were up to 12 months after injury or surgery, suggesting that limitations may persist after injury and surgery. The participants in this study only reported their injuries within the past 6 months, making the influence of earlier injuries a possibility. This study looked at a half kneeling position and a body weight position. These different positions may affect overall movement at the ankle and may have different implications for range of motion. The ordinal scale provides us with a categorical finding rather than the numerical finding of that found with the SADS. This categorical rating is effective for a screen, but may not provide specific findings and therefore requires further examination and testing.
Future studies should compare goniometric measurement of the SADS to the ordinal scale and further elucidate the differences and underlying causes in the SADS ordinal scores. No difference exists between the measurement within and behind the malleolus. Although the standing position provides a more functional position, it is unclear whether contributions from the hip and knee may affect DROM. For this reason, future research should focus on how the hip, knee, and other joints may affect the DROM in a weight-bearing position. Further exploration into the contribution of neuromuscular control and balance may explain the effects on weight-bearing dorsiflexion. Furthermore, future research may explore the correlations between standing and half kneeling positions.
Implications for Clinical Practice
Significant findings between the HDT and the SADS indicate that the SADS may be a valuable tool to quickly screen for ankle dorsiflexion limitations in an otherwise healthy population. This is especially useful during pre-participation physical examinations when efficiency and versatility are even more valuable. The SADS does not require the use of a wall, tape measure, or goniometer, which were necessary for measurement in other studies.11,12,15 It offers a fast screening method to determine if further intervention is necessary. The SADS would filter a client or athlete who does not achieve a beyond measurement or has pain to be evaluated further.
The SADS may be useful as a screening tool for identifying individuals with limited DROM. These screening findings can then be used by clinicians to identify individuals who are in need of further assessment.
Because decreased DROM has been correlated with an increased risk of future injury, the SADS provides an effective and efficient screen to identify individuals who do not possess enough closed chain dorsiflexion.3–5 This screen then allows the evaluator to determine if further investigation is necessary depending on criterion measurement. The SADS will provide an efficient way to identify individuals at risk for lower extremity injury during pre-participation physical examinations.
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