Tricia J. Hubbard

Contributing factors to chronic ankle instability

Background: The development of repetitive ankle sprains and persistent symptoms after initial ankle sprain has been termed chronic ankle instability (CAI). There is no clear indication of which measures are most important in discriminating between individuals with and without CAI. Methods: Thirty subjects with unilateral CAI and controls had measures of ankle laxity and hypomobility, static and dynamic balance, ankle and hip strength, lower extremity alignments, and flexibility taken on both limbs. Results: Based on comparisons of CAI ankles and side-matched limbs in controls, the measures significantly predictive of CAI were increased inversion laxity (r 2 change = 0.203), increased anterior laxity (r 2 change = 0.11), more missed balance trials (r 2 change = 0.094), and lower plantarflexion to dorsiflexion peak torque (r 2 change = 0.052). Symmetry indices comparing the side-to-side differences of each measure also were calculated for each dependent variable and compared between groups. The measures significantly predictive of CAI were decreased anterior reach (r 2 change = 0.185), decreased plantarflexion peak torque (r 2 change = 0.099), decreased posterior medial reach (r 2 change = 0.094), and increased inversion laxity (r 2 change = 0.041). Conclusions: The results of this study elucidate the specific measures that best discriminate between individuals with and without CAI. Both mechanical (anterior and inversion laxity) and functional (strength, dynamic balance) insufficiencies significantly contribute to the etiology of CAI. Prevention of CAI may be possible with proper initial management of the acute injury with rehabilitation aimed at those factors that best discriminate between individuals with and without CAI.

Effect of strength and proprioception training on eversion to inversion strength ratios in subjects with unilateral functional ankle instability

Objectives: To examine the effect of six weeks of strength and proprioception training on eversion to inversion isokinetic strength ratios (E/I ratios) in subjects with unilateral functional ankle instability. Methods: Thirty eight subjects were randomly assigned to one of four treatment groups: strength training (S); proprioception training (P); strength + proprioception training (B); control (C). Isokinetic strength was tested before and after training using a Kin Com 125 automatic positioning isokinetic dynamometer. Subtalar joint eversion and inversion motions were tested both concentrically and eccentrically through a range of motion involving 40°. All peak torque and average torque values were normalised for body mass. E/I ratios were calculated from average torque and peak torque measures by taking the concentric eversion value and combining it with the eccentric inversion value. Data were analysed using a mixed model analysis of variance with repeated measures on the test factor. Average torque and peak torque E/I ratios at 30 and 120°/s were analysed separately. Results: There were no significant differences in average torque and peak torque E/I ratios of the functionally unstable ankle for any of the groups after training compared with before. Conclusions: Six weeks of strength and proprioception training (either alone or combined) had no effect on isokinetic measures of strength in subjects with self reported unilateral functional instability. Further studies examining this agonist (concentric) to antagonist (eccentric) muscle group strength ratio are needed.

Mechanical Contributions to Chronic Lateral Ankle Instability

Lateral ankle sprains are one of the most common athletic injuries. Even more concerning is the high recurrence rate after an initial sprain. The development of repetitive ankle sprains and persistent symptoms after injury has been termed chronic ankle instability (CAI). One of the purported causes of CAI is mechanical ankle instability (MAI).MAI results in abnormal ankle mechanics. Both hypermobility and hypomo-bility may change a joint’s axis of rotation and result in abnormal joint mechanics. The role of hypermobility, or laxity, has been examined extensively in the literature, but more recently the role of hypomobility has also been examined. There may be a relationship between the two, with implications at the talocrural, subtalar, and inferior tibiofibular joints.Assessment and treatment should focus on both hypermobility and hypomobil-ity and although injury may seem to be isolated to the talocrural joint, the inferior tibiofibular and subtalar joints should also be thoroughly examined.

Ankle Ligament Healing After an Acute Ankle Sprain: An Evidence-Based Approach

OBJECTIVE To perform a systematic review to determine the healing time of the lateral ankle ligaments after an acute ankle sprain. DATA SOURCES We identified English-language research studies from 1964 to 2007 by searching MEDLINE, Physiotherapy Evidence Database (PEDro), SportDiscus, and CINAHL using the terms ankle sprain, ankle rehabilitation, ankle injury, ligament healing, and immobilization. STUDY SELECTION We selected studies that described randomized, controlled clinical trials measuring ligament laxity either objectively or subjectively immediately after injury and at least 1 more time after injury. DATA EXTRACTION Two reviewers independently scored the 7 studies that met the inclusion criteria. Because of differences in study designs, a meta-analysis could not be performed. Effect sizes and confidence intervals could be calculated only for 1 study. The percentages of subjective and objective instability were calculated for the remaining studies. DATA SYNTHESIS Ankle laxity improved over a period of 6 weeks to 1 year. One author showed stress talar tilt values of 16.10 +/- 8.8 degrees immediately after injury and 3.4 +/- 3.6 degrees at 3 months after injury. In 2 articles, the authors reported that positive anterior drawer tests were still present in 3% to 31% of participants at 6 months after injury. Additionally, feelings of instability affected 7% to 42% of participants up to 1 year after injury. CONCLUSIONS/RECOMMENDATIONS In the studies that we examined, it took at least 6 weeks to 3 months before ligament healing occurred. However, at 6 weeks to 1 year after injury, a large percentage of participants still had objective mechanical laxity and subjective ankle instability. Direct comparison among articles is difficult because of differences in methods. More research focusing on more reliable methods of measuring ankle laxity is needed so that clinicians can know how long ligament healing takes after injury. This knowledge will help clinicians to make better decisions during rehabilitation and for return to play.

Ligament Laxity Following Inversion Injury with and without Chronic Ankle Instability

Background: Not all patients develop chronic ankle instability (CAI) after one or more lateral ankle sprains; some seem to heal or adjust to the ankle laxity after injury. Why do some patients develop CAI and others are able to cope and return to normal function? The purpose of this study was to examine ligament laxity between subjects with and without CAI. Materials and Methods: Sixteen subjects with unilateral CAI and 16 subjects without participated in the study. Ligament laxity was measured with an instrumented ankle arthrometer. The arthrometer measured ankle joint motion for anterior/posterior displacement (mm) during loading at 125 N and inversion/eversion rotation (degrees of ROM) during loading at 4000 N/mm. For each dependent variable a 2 × 2 mixed model ANOVA was run with the between factor being group (CAI, No CAI) and the within factor with repeated measures being side (involved, uninvolved). Results: A significant group by side interaction for anterior displacement (F1,30 = 370.085, p < 0.001), and inversion rotation (F1,30 = 7.455, p = 0.010) was found. There was significantly more anterior displacement and inversion rotation for the involved ankles of the CAI group than the involved ankles of the stable group and the uninvolved ankles of the CAI group. Conclusion: Based on the results of this study it appears that the increased anterior displacement and inversion rotation compared to patients without instability may be why subjects develop CAI. Although the patients without instability have a history of more than one lateral ankle sprain, they did not demonstrate increased laxity, which may be the reason why they do not complain of the functional impairment demonstrated in subjects with CAI.

Talar Positional Fault in Persons With Chronic Ankle Instability

OBJECTIVE To determine whether sagittal plane talar position differs between uninjured controls and individuals with chronic ankle instability (CAI) using lateral ankle radiographs. DESIGN Single-blind case control. SETTING University-based sports medicine research laboratory. PARTICIPANTS University students (N=48) volunteered to participate. Twenty-four uninjured controls (12 men, 12 women; mean +/- SD, 21.8+/-2.6y; 170+/-10cm; 73+/-16kg), and 24 adults with CAI (12 men, 12 women; 21.7+/-2.8y; 175+/-13cm; 71+/-13kg) participated. INTERVENTION A single nonweight-bearing lateral radiograph was taken of each ankle. Subjects were positioned side lying with the hip and knee in a neutral position in the transverse plane and the ankle joint in a neutral position (90 degrees of dorsiflexion, 0 degrees of inversion/eversion). MAIN OUTCOME MEASURE The sagittal plane talar position was calculated as the distance between the most anterior margin of the inferior tibia and the most anterior margin of the talar dome in millimeters for each radiograph. RESULTS Talar position was significantly more anterior in the involved CAI limb (3.69+/-1.37mm) than the uninvolved CAI limb (2.98+/-1.61mm; P=.03). Additionally, an anterior talar position was significantly greater in the involved CAI limb than the matched control limb (2.65+/-1.24cm; P<.01). No differences were found between the uninvolved CAI limb and the matched control group limb (P=.57) or between the limbs of the uninjured control group (P=.75). Intratester reliability was found to be .90, while intertester reliability was .78. CONCLUSIONS An anterior talar positional fault is present in the involved limb of individuals with CAI relative to their uninvolved limb and compared with the matched limb of a control group. The talar position measurement technique has excellent intratester and intertester reliability.

Contributing Factors to Medial Tibial Stress Syndrome: A Prospective Investigation

PURPOSE To conduct a prospective, multisite, cohort study investigating the possible risk factors for medial tibial stress syndrome (MTSS) in college athletes. METHODS One hundred and forty-six healthy, collegiate athletes from NCAA Division I and Division II institutions participated in the study. Subjects first completed a health history questionnaire to establish previous history of injury and underwent a physical examination to assess their ankle/foot strength, ankle/foot range of motion, tibial varum, and navicular drop before the start of their respective athletic season. Athletes were instructed to report to a certified athletic trainer if they developed pain on their tibia. If MTSS was present, subjects were then placed into the symptomatic group. Independent t-tests and chi-square analyses were used to determine whether differences existed between MTSS and healthy athletes for the continuous and the discrete dependent variables, respectively. The significant dependent variables were then used in the discriminant function analysis. RESULTS Twenty-nine subjects developed MTSS during this study. Athletes that had been participating in athletic activity for fewer than 5 yr were significantly more likely to develop MTSS (P = 0.002). Additionally, athletes with a previous history of MTSS (P = 0.0001), a previous history of stress fracture (P = 0.039), and the use of orthotics (P = 0.031) were more likely to develop MTSS compared with those who did not develop MTSS. CONCLUSION This study established that the factors most influencing MTSS development were previous history of MTSS and stress fracture, years of running experience, and orthotic use. These data demonstrate the importance of establishing a thorough history before the start of the season so that athletes who might be at risk for MTSS development can be identified.

Mechanical Instability After an Acute Lateral Ankle Sprain

OBJECTIVE To examine the natural recovery of mechanical laxity after an ankle sprain over an 8-week period. DESIGN Prospective cohort study. SETTING Biodynamics research laboratory. PARTICIPANTS Subjects with an acute lateral ankle sprain (n=16; 7 men, 9 women; age, 19.5+/-0.7y; mass, 64.6+/-8.1 kg; height, 171.9+/-9.6 cm) and healthy controls (n=16; 7 men, 9 women; age, 20.4+/-1.7y; mass, 76.9+/-11.1 kg; height, 176.5+/-11.1 cm) participated. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Subjects with acute ankle sprains were tested 3 days after injury and again 8 weeks later. Anterior and posterior displacement (mm) and inversion and eversion rotation ( degrees ) were measured with an instrumented arthrometer. For each dependent variable, a 2 x 2 x 2 repeated-measures multivariate analysis of variance was performed. RESULTS A significant interaction was found between group, time, and side for anterior translation (F=4.24, P=.05). There were also significant main effects for group. There was significantly more anterior displacement at day 3 (F=19.52, P=.001) and at week 8 (F=8.45, P=.010) in the injured group compared with the healthy group. There was also significantly more inversion rotation at day 3 (F=2.70, P=.002) and at week 8 (F=5.4, P=.033) in the injured group compared with the healthy group. CONCLUSIONS The lack of significant differences in mechanical laxity over an 8-week period suggests that natural recovery of laxity takes longer than 8 weeks. Further research needs to be conducted to examine how long this laxity persists and the role ankle rehabilitation plays in mechanical stability restoration.

Effect of Ankle Taping on Mechanical Laxity in Chronic Ankle Instability

Background: The high percentage of re-injury after an initial ankle sprain necessitates examination of preventative methods. The purpose of this project was to investigate the effect ankle tape has on mechanical laxity in subjects with CAI. Materials and Methods: Twenty subjects with unilateral CAI (seven males and 13 females; age, 20.6 ± 1.8 years; mass, 69.9 ± 13.7 kg; height, 172.3 ± 9.3 cm) and 20 healthy subjects (seven males and 13 females; age, 21.9 ± 4.3 years; mass, 72.0 ± 14.6 kg; height, 171.1 ± 6.7 cm) participated in the study. Both ankles of each subject were tested under two conditions: 1) before the application of tape; and 2) immediately after 30 minutes of exercise with the ankle taped. Mechanical laxity was measured with an instrumented ankle arthrometer. Two (group) x two (time) repeated measures ANOVA analysis was used for analysis. Results: There were significant group by time interactions (p = 0.014) for anterior displacement with significantly increased anterior displacement in the involved ankle of the CAI group relative to the matched control limb both before and after tape application. Similarly, there were significant time main effects for posterior displacement (p = 0.004), inversion (p = 0.001) and eversion (p = 0.043) rotation. Specifically, tape application decreased posterior displacement, inversion and eversion rotation only in the CAI group. Additionally, a significant group main effect for inversion rotation (p = 0.001) was also noted. Followup testing indicated significantly greater inversion rotation for the CAI ankle compared to the matched healthy ankle before tape application. Conclusion: Mechanical laxity significantly decreased in CAI subjects after tape application. Although there was still a significant difference in mechanical laxity between the involved ankle vs. the uninvolved ankle of the CAI group, as well as the matched healthy group, laxity decreased in the CAI ankle after the application of tape. Clinical Relevance: Ankle taping may be able to improve mechanical instability in those with CAI.

Segmental Spinal Reflex Adaptations Associated With Chronic Ankle Instability

OBJECTIVE To further understanding of the role that segmental spinal reflexes play in chronic ankle instability (CAI). DESIGN A 2 x 2 repeated-measures case-control factorial design. The independent variables were ankle group with 2 levels (healthy, CAI) and stance with 2 levels (single, double legged). SETTING University research laboratory. PARTICIPANTS Twenty-two participants with CAI and 21 matched healthy controls volunteered. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The dependent variables were 2 measures of motoneuron pool excitability: paired reflex depression (PRD) and recurrent inhibition. RESULTS A 2 x 2 repeated-measures multivariate analysis of variance revealed a significant interaction between group and stance on the linear combination of PRD and recurrent inhibition variables (Wilks lambda=.808, F(2,40)=4.77, P=.014). Follow-up univariate F tests revealed an interaction between group and stance on the PRD (F(1,41)=9.74, P=.003). Follow-up dependent t tests revealed a significant difference between single- and double-legged PRD in the healthy participants (t(20)=-3.76, P=.001) with no difference in CAI participants (t(21)=-0.44, P=.67). Finally, there was a significant difference in recurrent inhibition between healthy (mean, 83.66) and CAI (mean, 90.27) (P=.004). CONCLUSIONS This study revealed that, compared with healthy participants, CAI participants were less able to modulate PRD when going from a double- to a single-legged stance. Additionally, CAI participants showed higher overall levels of recurrent inhibition when compared with healthy matched controls.