Identifying Range-of-Motion Deficits and Talocrural Joint Laxity After an Acute Lateral Ankle Sprain

In our cross-sectional design, the independent variables were time (24–72 hours, 2–4 weeks, and 6 months), injury severity (grade I, II, or III), and group (LAS and CON). The dependent variables were DFROM (°), weight-bearing lunge test (WBLT) results (°, centimeters; Figure 1), INV TI (mm), INV length (mm), AD TI (mm), and AD length (mm). Covariates were sex, height, and mass. Testing took place at 3 time points after LAS: 24 to 72 hours, 2 to 4 weeks, and 6 months. The CON group was tested once, around the 6-month time point for the LAS group. During each testing session, the same sequence was completed by the same athletic trainer (AT), who had 4 years of experience using each measure: (1) DFROM, (2) WBLT, and (3) stress ultrasonography.

We recruited 108 volunteers (58 females, 50 males) for this study. All participants were recreational or competitive university student-athletes (Table 1) who engaged in physical activity for at least 30 minutes, 3 times a week. Each person provided informed consent, and the investigation was approved by the university's institutional review board. Recruitment and testing occurred over an 18-month period (fall 2017 to spring 2019). Participants were further divided into the LAS (n = 55) and CON (n = 53) groups (Figure 1). For the LAS group, all data were collected on unilateral acute LASs within 24 to 72 hours of injury using the International Ankle Consortium definition of ankle sprain.¹⁵  Ankle sprains were included whether or not the participant had incurred a previous LAS on that side. Nine LAS participants were not included in the 6-month testing session because they were either unavailable or not near the testing location at that time. Among the LAS group, each person's injury severity was classified (grade I, II, or III).¹⁶  For assignment to the LAS group, we selected those with a previous LAS on the same side. Those who had their first LAS on that side were also included in the study. A history of previous LAS on that side served as a covariate to attempt to account for this difference. A single experienced rater who is an AT completed the injury classification. We did not conduct a separate reliability analysis because the determination was also based on the laxity measurement. The reliability of each measure was taken from previous work and is outlined in the “Instrumentation” section. Communication regarding follow-up data collection took place via email and the participant's school AT. The involved limb and height and weight within 10% for the LAS individuals were matched in the CON group. In accord with the International Ankle Consortium guidelines¹⁵  for CON participants, the CON group had no history of LAS sprain on either side with Cumberland Ankle Instability Tool (CAIT) and Identification of Functional Ankle Instability (IdFAI) scores of 30 and 0, respectively. Excluded from the study were any participants with CAI (CAIT score < 24 or IdFAI score > 11) or who were currently seeking treatment for a separate lower extremity injury (not including an LAS) or had undergone any lower extremity surgery within the last year.¹⁵  In the LAS group, 44 of the 55 participants (80%) were National Collegiate Athletic Association Division I or II competitive athletes who received initial treatment within 24 to 72 hours and progressive rehabilitation (protection, rest, ice, compression, and elevation; range of motion; strength; balance; and joint mobilizations) from an AT. Although the rehabilitation process may affect outcomes after LAS, we did not evaluate the rehabilitation protocols. The remaining 20% of participants (n = 11) with LAS were recreational noncompetitive athletes who received an initial evaluation by a physician within 24 to 72 hours but did not pursue rehabilitation with an AT. However, these athletes reported verbally by the 2- to 4-week testing session that they had returned to physical activity (eg, military training, running, and ultimate Frisbee) after the LAS.

Mechanical laxity of the talocrural joint was measured using the LigMaster device (LigMaster, Inc) to stress the ankle in the AD and INV positions, while taking an ultrasound image (musculoskeletal ultrasound [MSUS]) using the LOGIQ E system (General Electric Co) at a 12-MHz frequency and 2.5-cm depth. The transducer head was positioned in the sinus tarsi, obliquely with respect to the distal fibula, from the origin to the insertion of the ATFL.¹⁷  Ultrasonic gel (Aquasonic 100; Parker Laboratories, Inc) was used as a conductive medium. For the DFROM and WBLT, an inclinometer, protractor, and tape measure were used.

Before the testing session, participants completed a questionnaire that addressed general information, such as age, sex, height, weight, and lower extremity injury history. They also completed 3 surveys related to foot and ankle function and instability so that we could determine if any participants had CAI, which would exclude them from this study. The 3 surveys were the CAIT, IdFAI, and Foot and Ankle Ability Measure (FAAM) Activities of Daily Living (ADL) and Sports Subscales.⁶ 

To determine each individual's injury severity and grade (I, II, or III), we measured ankle girth (ie, edema) using a tape measure in a figure-eight method, DFROM using a goniometer, and laxity using stress ultrasound. The methods of Malliaropoulos et al¹⁶  for classifying LAS grade are described in Table 2. Because a grade I ankle sprain is associated with negative AD and talar tilt tests, we analyzed severity separately.

Participants were asked to sit up on the plinth supporting themselves on outstretched arms with their legs straight and ankles hanging off the table. Using a goniometer and the methods of Malliaropoulos et al,¹⁶  we placed the axis at the distal edge of the lateral malleolus, with the stationary arm in line with the midline of the fibula and the movement arm parallel to the fifth metatarsal. Recruits were instructed to maintain neutral position (0° on the goniometer). They were then told to use their toes to pull the foot back toward them as far as they could. Three measurements were taken, and the largest measure was used for comparison. The uninvolved ankle was measured first, followed by the involved ankle.

We administered the WBLT using the methods described by Bennell et al.¹⁸  Range of motion (°) and the distance away from the wall (centimeters) were collected. Three trials were performed, and the maximal range of motion was used for analysis. If the participant easily reached the wall with the toes at 10 cm, the trial was repeated at a greater distance, 1 cm at a time until maximal distance and range were achieved. The opposite was done if the participant was unable to touch the wall without the heel rising at 10 cm. The foot moved closer to the wall 1 cm at time until maximal distance and range were achieved. The inclinometer was placed on the participant's anterior distal tibia.

For the last portion of the testing session, we placed the participant's leg in the LigMaster device using the guidelines for INV. The counter bearing was positioned near the lateral knee without creating pressure on the joint line. A cushion underneath the distal hamstrings was provided for added comfort. The pressure actuator was placed so that the edges of the rubber padding delivered pressure at the level of the most medial point on the medial malleolus (Figure 2A).¹⁹  Three static images were taken consecutively before the stress was imposed. A force of 15 dN was applied unless the participants reported pain before that value was reached; in that case, the force application was stopped between 12 and 15 dN. The MSUS images were obtained over the ATFL, with 3 images taken consecutively at the maximal stress position (Figure 2B).²⁰  Using the device's measurement function, we assessed the distance between the peaks of the lateral malleolus and talus, or TI, which constitutes the anatomic origin and insertion of the ATFL (Figure 3A).^14,21  Measurements of the uninjured ankle were compared with the injured side. An average of the 3 images was used for analysis, and the difference between the injured and uninjured ankles was determined.¹⁴  The INV TI was defined as the difference between the stress and static measures. The INV length was defined as the distance between the peak of the talus and the fibula at the maximal stress position.

The last measurement we took was in the AD position using the LigMaster device using methods similar to those of Croy et al.¹⁴  Participants were asked to lie on the side opposite the test ankle. The pressure actuator was placed so that the edges of the rubber padding delivered pressure at the level of 5.0 cm proximal to the medial malleolus (Figure 4). Three static images were taken consecutively before stress was imposed. A force of 15 dN was applied, unless the participant reported pain before that value was reached, in which case the force was removed between 12 and 15 dN.¹⁸  The MSUS images were obtained over the ATFL, with 3 images taken consecutively at the maximal stress position. We used the device's measurement function to determine the distance between the peaks of the lateral malleolus and talus, or TI, which constitutes the anatomic origin and insertion of the ATFL (Figure 3A).^14,21  Measurements of the uninjured ankle were compared with the injured side. An average of the 3 images was used for analysis, and the difference between the injured and uninjured ankles was determined.¹³  The AD TI was defined as the difference between the stress and static measures. The AD length was defined as the distance between the peak of the talus and the fibula at the maximal stress position.

Based on an a priori power analysis (G*Power, version 3.1.9; Heinrich-Heine-Universität Düsseldorf), 50 participants each were needed in the LAS and CON group to obtain power of 0.80, effect size of 1.4, and P ≤ .05. The following statistical analyses were used: (1) repeated-measures analysis of variance (ANOVA) to evaluate DFROM, WBLT, and AD and INV TI and length in the LAS group over the 3 time periods (24 to 72 hours, 2 to 4 weeks, and 6 months); (2) independent-samples t tests to compare the variables between groups (LAS and CON) at the 6-month time point; and (3) one-way ANOVA to compare the variables according to the 3 severity grades (grade I, II, III) in the LAS group during the 3 time periods. We calculated Cohen d effect sizes to determine the standardized difference in the means of significant findings. A small effect size was represented by 0.2, medium by 0.5, and large as 0.8.²²  All data were analyzed using SPSS (version 25; IBM Corp). An a priori α level of .05 was used to denote statistical significance.

Each variable (injury classification and function, DFROM, WBLT, INV TI and length, and AD TI and length) was assessed in the LAS group over time, by group at 6 months, by LAS severity over time, and between ankles in the LAS group. Five new participants were added to the LAS group between the 24- to 72-hour and 2- to 4-week testing sessions (total of 55 participants) when they were identified after the 72-hour window, and they returned for the 6-month analysis. From the 2- to 4-week (50 participants) and 6-month (46 participants) testing sessions, 9 participants dropped out because they were unavailable, not near the testing location, or sustained another injury before the 6-month session.

Of those who sustained an acute LAS, 21 of 55 (38%) injuries were grade I, 27 of 55 (49%) were grade II, and 7 of 55 (13%) were grade III. Regarding the injured ankle, participants had sustained an average of 2.16 ± 2 previous LASs.

In the LAS group, girth decreased between 24 and 72 hours, 2 and 4 weeks, and 6 months (Table 3). Over time, DFROM increased from 24 to 72 hours to 2 to 4 weeks and 6 months. The WBLT also increased between 2 to 4 weeks and 6 months. The INV length demonstrated a very small difference (1 mm) between 24 to 72 hours and 2 to 4 weeks. However, INV TI was greater at 24 to 72 hours than at 2 to 4 weeks. No differences were detected in the LAS group over time in AD TI (P = .280) or AD length (P = .228).

The CAIT score was lower at 2 to 4 weeks than at 6 months (P = .035). The IdFAI score was highest at 2 to 4 weeks compared with 24 to 72 hours and 6 months. The FAAM-ADL and FAAM-Sports scores increased over time from the 24- to 72-hour to 2- to 4-week to 6-month time frames (P < .001; Table 3).

At 6 months, we found no differences in girth between groups (P = .288; Table 4). Dorsiflexion ROM and WBLT performance did not differ between groups. The AD length, INV TI, and INV length were greater in the LAS group than in the CON group. The AD TI did not differ between groups.

All functional questionnaire scores of the LAS group differed from those of the CON group; the former exhibited lower CAIT, higher IdFAI, lower FAAM-ADL, and lower FAAM-Sports scores.

Using a 1-way ANOVA to examine differences between severity of ankle sprain (grade I, II, or III), we found that the FAAM-Sports score at 24 to 72 hours was lower in participants with grade III than grade I injuries (P = .030; Table 5). No differences were noted among grades at 24 to 72 hours for girth (P = .788) or CAIT (P = .486) or IdFAI (P = .360) or FAAM-ADL (P = .101) score. At 2 to 4 weeks, participants with grade III LASs displayed lower FAAM-Sports scores than those with grade I (P = .026) or II (P = .034) injuries. During this time, the CAIT was lower in recruits with grade III LASs than those with grade I (P = .006) or II (P = .043) injuries. The IdFAI and FAAM-ADL scores were not different between grades at 2 to 4 weeks (P = .539 and P = .080, respectively). At 6 months, the FAAM-Sports score was lower in individuals with grade III than grade I LASs (P = .041). Girth and the CAIT, IdFAI, and FAAM-ADL scores did not differ at 6 months.

At 24 to 72 hours, DFROM was less in those with grade III than grade I LASs. No difference was seen among grades at 2 to 4 weeks or 6 months (P = .980). At 24 to 72 hours, the WBLT was not conducted. At 2 to 4 weeks, the WBLT result (°) approached differences by severity (P = .053), yet the centimeter measure was not different (P = .080). Conversely, at 6 months, the WBLT result (centimeters) approached differences by severity (P = .061), but the result in degrees was not different (P = .174).

At 24 to 72 hours, INV length was larger in participants with grade III than grade I (P = .023) or II (P = .035; Table 5) LASs. However, no differences were noted between those with grade II and III injuries (P = .651). The AD TI was larger in individuals with grade II than grade I or III LASs at 24 to 72 hours (P = .009). The INV length and TI did not differ by severity at 2 to 4 weeks or 6 months. The AD length and TI did not differ by severity at 2 to 4 weeks or 6 months.

The long-term effects of an acute LAS on ankle joint laxity and function have not been previously identified in a college-aged population compared with a healthy, uninjured cohort. Our purpose was to assess mechanical laxity of the talocrural joint over time after an LAS. The primary finding was that, at 6 months after injury, the LAS group displayed differences in laxity.

Among the 55 participants who sustained an acute LAS, 38% (n = 21) were grade I, 49% (n = 27) were grade II, and 13% (n = 7) were grade III injuries. Our distribution pattern was similar to that reported by Malliaropoulos et al,¹⁶  who identified 208 track and field athletes and found 44% (n = 92) were grade I, 30% (n = 63) were grade II, and 26% (n = 53) were grade III.¹⁶  Our results were not surprising as we used the same criteria as Malliaropoulos et al¹⁶  to classify LAS severity.

As we noted, girth decreased over time in the LAS group, which was expected due to tissue healing. At 6 months, CAIT scores were 5.5 points lower in the LAS group than in the CON group. Wright et al²³  identified the minimal detectable change as 3.08 and the minimally clinical important difference as ≥3 points. The FAAM-ADL and FAAM-Sports scores increased in the LAS group between 24 to 72 hours and 2 to 4 weeks and demonstrated a smaller increase between 2 to 4 weeks and 6 months. Croy et al¹⁴  described increases in both FAAM-ADL and FAAM-Sports scores from baseline to week 3 (21.9 ± 16.2, P < .0001 and 23.8 ± 16.9, P < .0001, respectively) and from week 3 to week 6 (2.5 ± 4.4, P = .009 and 10.5 ± 13.2, P = .001, respectively). Doherty et al²⁴  observed that a lower level of self-reported function and poor dynamic postural control 6 months after a first-time LAS ultimately predicted the development of CAI. Although girth decreased and self-reported function improved over time, substantial deficits were still present at 6 months and depended on the severity of the LAS.

After an LAS, reduced DFROM compared with the healthy ankle has been recognized as a strong predictor of lower extremity injury.²⁵  Those with reduced DFROM (34°) were approximately 5 times more likely to sustain an LAS than those with an average DFROM (45°).²⁶  During gait, restricted DFROM may increase the risk of LAS by limiting the ankle's ability to reach a closed-packed position during midstance.²⁷  For normal walking, at least 10° of dorsiflexion is required; however, for running, 20° to 30° of dorsiflexion is required.²⁸ 

Few previous researchers have investigated the differences in DFROM and WBLT results by severity of LAS.²⁹  Our classification of the injury during the first 24 to 72 hours depended on the measured DFROM and the difference between the injured and uninjured ankles and was, thus, the basis for the difference among grades. In a grade II or III LAS, the structure of the ATFL has been disrupted; during the remodeling phase, scar tissue builds up around the repairing ligament.^30,31  This scar tissue is less mobile than that in an intact ligament. Earlier authors⁸  concluded that this may shift the talus to a more anterior position, causing a decrease in ankle DFROM. We postulate that this explains the decrease in WBLT among those with a grade II or III LAS. As DFROM improves over time after LAS, it may be important to consider the difference between the injured and uninjured limbs. We contend that the WBLT is important to use and monitor in those who sustain a grade II or III LAS to ensure no persistent differences. As DFROM improved over time after the LAS, deficits were noted by severity of LAS and DFROM did not tend to return to normal at the same rate.

The recent focus of research³²  has been on mechanical instability of the ankle joint, or laxity, after LAS, especially when determining a participant's risk for repetitive injuries or CAI. Croy et al¹⁴  conducted bilateral stress ultrasound imaging at baseline (<7 days) and on the affected ankle at 3 weeks and 6 weeks after injury in 3 conditions: neutral, AD, and INV. The AD length increased TI in the involved ankle (22.65 ± 3.75 mm, P = .017) compared with the uninvolved ankle (19.45 ± 2.35 mm) at baseline. To our knowledge, these authors were the first to discuss TI changes in neutral position. However, we defined TI (in millimeters) as the difference between the stressed and static positions on the MSUS image. Our results showed that those who had sustained an acute LAS still displayed differences in ankle laxity versus a healthy CON group at 6 months after injury.

The differences in INV length by severity showed that the grade assigned at 24 to 72 hours was correct according to the demonstrated laxity. Croy et al¹⁴  noted that INV stress resulted in greater interval changes in the injured (23.41 ± 2.81 mm) than the uninvolved ankle (21.13 ± 2.08 mm). They reported a main effect for time in INV (21.93 ± 3.75 mm, P = .019,) but not AD (21.18 ± 2.34 mm, P = .055), which is in line with our findings. The TI decreased between baseline and week 3 for INV only (F_1,26 = 5.6, P = .026). Similarly, we determined that TI decreased between 24 to 72 hours and 2 to 4 weeks after injury. Still, Croy et al¹⁴  did not include a control or healthy group but instead compared the values with those of the uninvolved ankle. Also, the ending time points were different: up to 6 weeks after injury versus our 6-month time point to determine the long-term effects of ankle laxity via stress ultrasonography.

Hubbard and Cordova¹⁰  examined the natural course of mechanical laxity of the talocrural joint over 8 weeks after an LAS. Participants with acute LASs were tested 3 days after injury and at follow-up 8 weeks later. Laxity was measured by anterior and posterior displacement (millimeters) and INV and eversion rotation (°) using an instrumented arthrometer. We included participants with grade I–III injuries, whereas Hubbard and Cordova³³  studied participants with grade I or II LASs. The authors reported more anterior displacement at day 3 (P = .001) and at week 8 (P = .010) in the injured group than in the healthy group. Also, INV rotation was greater at day 3 (F = 2.70, P = .002) and week 8 (F = 5.4, P = .033) in the injured group than in the healthy group. They concluded that reduction of mechanical laxity after an LAS may take longer than 8 weeks. Similarly, we showed that at 6 months after LAS, participants displayed persistent differences in ankle laxity (INV and AD) compared with a healthy CON group. We believe that by 6 months after LAS, the ligament (specifically the ATFL) is healing and developing collagen fibers appropriately; yet the ligament is unable to withstand the same mechanical forces as a healthy, uninjured ligament, leading to additional microinjuries to the structure. Initially after an LAS, talocrural joint laxity depends on the severity of the injury and improves little over time, becoming greater than in healthy control at 6 months.

Miklovic et al³⁴  suggested that an acute LAS leads to CAI by a pathway of dysfunction. This pathway develops because of impairments that have been previously associated with CAI, including decreased range of motion, strength, and postural control and altered movement patterns during functional activities. An impairment-based rehabilitation model created by Donovan and Hertel³⁵  was an effective rehabilitation strategy for those with CAI. In summary, the impairment-based model involves assessing each possible impairment, identifying deficits, and then addressing the impairment through rehabilitation.³⁵  Because similar impairments are seen in all groups, the impairment-based model may be effective for treating patients with an acute LAS.³⁴ 

Recently, the International Ankle Consortium³⁶  developed recommendations based on expert consensus for the clinical assessment of patients with acute LAS injuries. The Rehabilitation-Oriented Assessment includes an evaluation of the patient's ankle in multiple areas: joint pain, joint swelling, range of motion, arthrokinematics, strength, static and dynamic postural balance, gait, level of physical activity, and self-reported joint function. Along with establishing the mechanism of injury and assessing the ankle joint bones and ligaments through stress tests, clinicians need to consider all aspects of the injury.³⁶  We showed that deficits can be identified early, at 24 to 72 hours, and persist at 6 months after injury. We urge clinicians to evaluate these clinical outcomes throughout the healing process, which can take up to 6 months after LAS. Future researchers should focus on the patterns after 6 months to see if these deficits continue or worsen.

As clinicians, we must incorporate these models into our education and continuing education of new and current clinicians and promote their use on every patient with an acute LAS. Each LAS may display different impairments that need to be addressed and reevaluated after return to full function. In an athletic population, investigators³³  found that these patients may return to full participation too early in the healing process, without specific and detailed outcome measure follow-ups, which may lead to incomplete recovery. We learned that participants' self-reported function did not improve by 6 months after the LAS. From the onset of the LAS, at each clinical evaluation, clinicians should establish the patient's deficits using specific outcome measures (questionnaires, range of motion, and laxity) compared with the healthy, uninjured ankle and continue to assess them up to 6 months postinjury, even after the person returns to full participation. We emphasize that at 6 months after LAS, differences were still present. We believe that the use of musculoskeletal ultrasound to obtain subjective information can be important to clinicians early in the management of patients with an LAS.

Although we offer clinicians and researchers additional insight into the long-term effects of an acute LAS, our study was not without limitations. To obtain a large enough sample, we were unable to collect baseline test results before the LAS because the potential participant pool was very large. For the CON group, we did not pursue additional testing sessions to coincide with the 24- to 72-hour and 2- to 4-week time points in the LAS group; thus, the comparison between groups occurred only at the 6-month time period. We attempted to avoid a possible history bias by testing both groups at the approximate 6-month time point of the LAS group. Future researchers may consider studying only patients with first-time LASs if the cohort is large enough or may wish to split the group into those with previous LASs and those without. Also, given the scope of our work, we did not take into account individual rehabilitation protocols, even though most participants were collegiate athletes treated by an AT. Future authors should also determine the role of rehabilitation in the ankle's response to LAS.

During the INV and AD stress tests, performed with the LigMaster device at 24 to 72 hours after the injury, a small number of participants had pain, causing the examiner to decrease the force from 15 dN to 10 to 12 dN. In the device manual, LigMaster, Inc, recommended that decreasing to 10 to 12 dN would still achieve the same results; however, the stress on the injured fibers might be less. Most individuals who experienced pain had sustained a grade II or III ankle sprain. Before the test, the examiner asked the participant to acknowledge “pain that is uncomfortable and unbearable that we need to stop the test for.” Also, the design of the LigMaster device presented the examiner with difficulties when used on a participant who had a longer or shorter lower limb length (knee to ankle) or foot size (length and width). The placement of the foot in the machine (ie, fit and angle) varied slightly due to each participant's size. Future researchers should consider using lower limb length as a covariate and determine if it is related to stress values. Even though all measurements were completed by 1 rater, another limitation is that we did not establish the reliability of each measure used. Due to the many statistical analyses conducted, we performed covariate analyses to limit type II error; however, we may not have been able to eliminate the error entirely.

To our knowledge, this investigation is the only one of its kind to assess the long-term effects of an acute LAS on participants compared with a healthy CON group. As clinicians, we must assess patients with LASs in the areas mentioned (range of motion, ankle laxity, dynamic balance, and musculoskeletal ultrasound) to determine if differences exist over time, especially if the athlete has returned to play and still displays deficits. We showed that laxity differences were present at 6 months after LAS. Future researchers should use our methods over longer terms (1 year, 2 years, and beyond), comparing the LAS group with a healthy CON group, and addressing the potential for developing CAI.

Laxity differences persisted in patients 6 months after an LAS compared with a healthy CON group. Increases in INV, AD, and and talar tilt were also noted between the groups at that time. At 24 to 72 hours, patients with grade II and III LASs had greater INV and AD ATFL length. Our results indicated that long-term deficits were present in the ankle joint at least 6 months after an LAS, which may lead to negative outcomes, such as the development of CAI and residual symptoms. One theory may be that ligament healing slows if return to activity is introduced while the inflammatory process is still occurring.