Root et al (1971, 1977) proposed that the range of dorsiflexion measured at the ankle joint in a static examination will predict the sagittal plane angle of the ankle joint at heel lift. To measure the range of dorsiflexion at the ankle joint in a non-weight bearing examination, Root et al (1971) described how one arm of a goniometer is placed along the lateral plantar aspect of the foot, and the other arm is placed along a bisection line that is drawn onto the lower lateral third of the leg, extending from the centre of the lateral malleolus. With the subtalar joint placed in a neutral position, Root et al (1971) stated that the foot is manually dorsiflexed onto the leg. Root et al (1977) proposed that placing the subtalar joint into a neutral position is essential to isolate the sagittal plane motion of the ankle joint. If the subtalar joint is allowed to pronate, Root et al (1977) stated that this will increase the range of dorsiflexion measured because dorsiflexion is a component of open chain (non-weight bearing) pronation of the subtalar joint.
The intra- and inter-assessor reliability of the examination of the range of dorsiflexion at the ankle joint
Moseley and Adams (1991), Elveru et al (1988) and Rome (1996) describe how there are numerous difficulties with the static non-weight bearing examination of the range of dorsiflexion at the ankle joint. These include: the poor identification of bony landmarks, variation in the force or torque applied by the examiner when moving the foot onto the leg, inadvertent muscular contraction from the patient, and the difficulty in reading the measurement recorded on a device.
78 Investigation Method of investigation Intra-assessor reliability Inter-assessor reliability Elveru et al (1988) 50 participants* 14 assessors Plastic goniometer ICC = 0.91 ICC = 0.50 Same position ICC = 0.40 Different position ICC = 0.59 Diamond et al (1989) 31 participants* 2 assessors Plastic goniometer ICC = <0.96 SEM = 1 ICC = <0.87 SEM = 2 Jonson and Gross (1995) 18 participants 2 assessors Plastic goniometer ICC = 0.74 SD = 1.32° ICC = 0.65 SD = 2.04° Menz et al (2003) 31 participants** 3 assessors Modified lunge examination Plastic goniometer - ICC = 0.87 Moseley and Adams (1991) 15 participants* 5 assessors Lidcombe template ICC = 0.97 - Konor et al (2012) 20 participants 1 assessor
Weight bearing lunge examination Plastic goniometer
ICC = <0.96
SEM = 1.8 -
Table 2.3 presents the intra- and inter-assessor reliability of the non-weight bearing examination of the range of dorsiflexion at the ankle joint. *asymptomatic and symptomatic participants. ** older patients (age range = 76-87years).
Elveru et al (1988) and Jonson and Gross (1997) report good to very good intra and inter-assessor reliability results with ICC = 0.90 (Elveru et al 1988) and Jonson and Gross (1997) reportICC = 0.74. For inter-assessor reliability, they reported moderate to good ICC values with ICC = 0.50 (Elveru et al 1988) and ICC= 0.65 (Jonson and Gross (1997). The reliability results from these investigations may be inadvertently higher, because the subtalar joint was not placed into a neutral position first. Elveru et al (1988) reported that the examination of the range of frontal plane motion at the subtalar joint was not as reliable if the subtalar joint was positioned in a neutral position first. Therefore, these results may not reflect the reliability of the measurements obtained from following the Root et al (1977) protocol. Some have proposed that using a specifically designed apparatus (Moseley and Adams 1991) or assessing the patient weight bearing (Konor et al 2012) is a more reliable method of examination. Moseley and Adams (1991) advocate the use of a lidcombe template
79 apparatus as it helps to standardise the amount of joint torque applied. Agreeably, this appears to improve the reliability as they reported ICC values of ICC = 0.97.
The assessment of the patient weight bearing using a standing lunge technique is described by Konor et al (2012) as more reliable than a non-weight bearing examination. Konor et al (2012) reported ICC values of 0.96 and smaller SEM values than the non-weight bearing examination too, with SEM= 1.8 to 2.8. However, Konor et al (2012) reported only intra-assessor reliability. To try and determine the clinical value of this examination, inter-assessor reliability results are required as it is highly unlikely that the same clinician will always assess the same patients. However, even with the good to excellent reliability between assessors, there is still variation in the measurements obtained, which undermines their clinical value. Keenan (1997) and Moseley and Adams (1991) emphasised that because a foot can be classified as abnormal from as little as 1° from the proposed normal value, perfect reliability between assessors is required. The minimal detectable change, which is the minimal amount of change incurred outside of the error incurred, is reported by Moseley and Adams (1991) to be up to 7.7°. This large variation would not satisfy the precision required by the Root et al (1977) protocol and it would affect the classification of the foot and the treatment rationale used.
The relationship between the range of dorsiflexion at the ankle joint measured in a non-weight bearing examination and the movement of the ankle joint during walking.
Root et al (1971, 1977) proposed that the minimum range of dorsiflexion to be measured in the static examination of the ankle joint is 10°. This is so that the ankle
80 joint can be dorsiflexed to this angle at heel lift. If the range of dorsiflexion measured in a static examination is less than 10°, Root et al (1977) classified this as ankle equines deformity. They assumed the ankle joint will be unable to dorsiflex to 10° at heel lift and that the heel will lift from the ground earlier than normal. To compensate for this limitation in the range of motion, they proposed that the subtalar joint will abnormally pronate during midstance, preventing the foot from transforming into a rigid lever and resulting in injury.
However, many (Leardini et al 2007, Arndt et al 2004, Lundrgen et al 2007, Hunt et al 2001a, Simon et al 2006, Nester et al 2006, Kitaoka et al 2006, and Moseley et al 1996) have reported that the calcaneus or talus is not dorsiflexed relative to the tibia up to or more than 10° at heel lift. All of these investigations also report that the calcaneus everted relative to the talus or tibia during midstance, to indicate pronation of the subtalar joint. Root et al (1977) would classify these feet as abnormal, which will present with or be pre-disposed to injury, except all participants included in these investigations are asymptomatic. This strongly indicates that feet do not require 10° of dorsiflexion to be symptom free and pronation of the subtalar joint is a normal movement of the foot and not a cause of injury. Cornwall and McPoil (1999b) reported that contrary to Root et al (1977), feet classified with less than 10° range of dorsiflexion at the ankle joint from static examination; do not pronate more at the subtalar joint during walking. In feet classified with less than 10°, the peak angle of calcaneal eversion relative to the tibia was only -0.2° (p=>0.05) greater than feet classified more than 15° of ankle dorsiflexion. The time to this peak angle of eversion was only 5.4% (p=>0.05) earlier than feet classified with more than 15° (Cornwall and McPoil 1999b). However, Cornwall and McPoil (1999b) describe how the time to heel lift was 2.8% earlier (p=<0.05), and the time to re-inversion
81 was 6.29% (p=<0.05) earlier in feet classified with less than 10° from static examination. This could be construed to be in part agreement with what Root et al (1977) proposed.
Figure 2.4 presents the frontal plane movement of the calcaneus relative to the tibia (rearfoot) during the stance phase of the gait cycle in feet classified with a limited (<10°) or normal (>15°) range of dorsiflexion at the ankle joint measured from static examination (Cornwall and McPoil 1999b).
Overall, it is unclear as to whether the range of dorsiflexion at the ankle joint measured from static examination can be used to predict the sagittal plane movement of the ankle joint during the stance phase of the gait cycle (Charles et al 2010). DiGiovanni et al (2002) proposed in support of Root et al (1977) that more feet were diagnosed with a musculoskeletal injury if the range of dorsiflexion at the ankle joint from a static examination was less than 10°. However, the participants used by DiGiovanni et al (2002) were all retired ex-military servicemen. In consideration of the high prevalence of injury in military personnel, it may suggest that these results are not indicative of the general population. In contrast, Orenduff et al (2006)
82 suggested that feet classified with less than 5° of dorsiflexion at the ankle joint from a static examination should be classified as an ankle equinus. This idea was based on the observation that the plantar pressure under the forefoot was significantly greater during the stance phase of walking in those classified with less than 5°. However, all participants included by Orenduff et al (2006) were diagnosed with diabetes and other factors may have caused the increase in plantar pressure, such as changes in plantar tissue.