Fibular position in individuals with self-reported chronic ankle instability

STUDY DESIGN: Case control study. OBJECTIVES: The purpose of this study was to assess the position of the distal fibula in individuals with chronic ankle instability (CAI). BACKGROUND: Recent literature has suggested that a positional fault of the fibula on the tibia may contribute to CAI; however, there is a lack of objective scientific evidence to support this claim. METHODS AND MEASURES: Thirty subjects with unilateral CAI (mean +/- SD age, 20.3 +/- 1.3 years) and 30 subjects with no previous history of ankle injury (mean +/- SD age, 21.3 +/- 3.8 years) participated in this study. Subjects completed a pair of subjective functional scales and fluoroscopic lateral images of both the right and left ankles were recorded. The distance from the anterior margin of the distal tibia to the anterior margin of the distal fibula was measured in millimeters. Nonparametric statistics were used to assess the relationship between fibular position and CAI status. RESULTS: There were significant differences between the CAI and control group ankles (P = .045) and within the involved and uninvolved sides of the CAI group (P = .006). Those with CAI had a significantly more anterior fibular position on their involved ankle in relation to their uninvolved limb, and the ankles of the control group. CONCLUSIONS: The fibula was positioned significantly more anterior in relation to the tibia in subjects with unilateral CAI. It is unclear if repetitive bouts of ankle instability caused the anterior fibular position or if the more anterior position was a predisposing factor to injury.     

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.     

Instrumented measurement of anteroposterior and inversion-eversion laxity of the normal ankle joint complex

Manual examination is the most common method for the evaluation of ankle anteroposterior (AP) and inversion-eversion (I-E) laxity. Objective assessment data of normal ankle laxity must be provided before comparison with an injured ankle can be made. The purpose of this study was to compare AP translation and I-E rotation at three force loads between dominant and nondominant ankles and to assess the test-retest reliability of a portable arthrometer in obtaining these measurements. The arthrometer consists of a frame that is fixed to the foot, a pad that is attached to the tibia, and a load-measuring handle that is attached to the foot plate through which the load is applied. A six-degrees-of-freedom spatial kinematic linkage system is connected between the tibial pad and the foot frame to measure motion. Instrumented measurement testing of total AP displacement and I-E rotation of both ankles was performed in 41 subjects (21 men and 20 women; mean age, 23.8 +/- 4.4 years). Subjects had no history of ankle injury. Subjects were tested in the supine position while lying on a table with the knee secured in extension and the foot positioned at 0 degrees of flexion. Laxity was measured from total AP displacement (millimeters) during loading to 125 N of AP force and from total I-E rotation (degrees of range of motion) during loading to 4000 N-mm. Reliability was evaluated by calculating intraclass correlation coefficients (2,1) at 75 N, 100 N, and 125 N of AP force and at 2000, 3000, and 4000 N-mm torque loads. Mean differences for displacement and rotation between the dominant and nondominant ankles at each of the force and torque loads were analyzed by dependent t-tests. For both the dominant and nondominant ankles, respectively, the reliability coefficients at each of the force loads for AP displacement (range, 0.82-0.89) and I-E rotation (range, 0.86-0.97) were high. The t-test analyses showed no significant differences (P > or = 0.05) for total AP displacement or I-E rotation between the dominant and nondominant ankles at any of the force loads. The results are clinically useful in providing information about the reliability of measures at different AP and I-E force loads using a portable ankle ligament arthrometer.     

Relationship Between Isokinetic Muscle Strength and Functional Tests in Chronic Ankle Instability

Isokinetic muscle strength measurements and functional tests are usually performed to evaluate ankle condition in chronic ankle instability (CAI), yet there is no clear demonstration of the relationship between isokinetic muscle strength and functional tests. The objective of this study was to evaluate the relationship between isokinetic muscle strength and functional tests in CAI. Between April 2014 and August 2016, 103 patients with unilateral CAI were studied. Single-leg balance, single-heel raise, and single-leg squat tests were performed for static balancing assessment. Single-leg hop, double-leg jump, and sidestep tests were performed for dynamic balancing assessment. The isokinetic muscle strength of both ankles was measured using a dynamometer. The involved ankle showed lower muscle strength in inversion than the uninvolved ankle, while eversion, dorsiflexion, and plantarflexion muscle strength had no significant differences between ankles. There were significant correlations between the isokinetic muscle strength of inversion and the single-leg balance test, single-heel raise test, and sidestep test (Pearson's r; 0.246, 0.514, and 0.229 at 30°/second; 0.288, 0.473, and 0.239 at 180°/second, respectively). The single leg balance, single heel raise, and sidestep tests are useful to assess not only ankle functional performance but also isokinetic muscle strength. Among these tests, the single heel raise test was the most reliable test to reflect muscle strength deficiency in CAI.     

Analysis of ankle-hindfoot stability in multiple planes: an in vitro study

BACKGROUND: It is necessary to have an understanding of ankle and hindfoot motion and stability to accurately diagnosis and treat ankle-hindfoot disorders. METHODS: We devised an ankle ligament testing apparatus to more critically determine ankle stability in all planes with a constant rotational force applied (inversion, eversion, internal rotation, external rotation) throughout the range of sagittal plane motion in 13 cadaver specimens. Three-dimensional kinematics were determined with a magnetic tracking device. RESULTS: With inversion force applied, calcaneal-tibial inversion was greatest in maximal plantarflexion (mean 22.1 +/- 6.0 degrees) and gradually decreased with dorsiflexion, which indicated that the ankle had the most inversion instability in plantarflexion. With eversion force applied, calcaneal-tibial eversion gradually increased with increasing dorsiflexion to 12.7 +/- 7.4 degrees indicating that the most eversion instability was in dorsiflexion. With internal rotation force applied, calcaneal-tibial internal rotation from plantarflexion to neutral ankle position increased. With external rotation force application, external rotation from neutral to maximal dorsiflexion increased. CONCLUSIONS: Ankle laxity was not constant but varied depending on the plantarflexion-dorsiflexion position and the direction of the applied force. The degree of ankle laxity was greater with inversion and internal rotation torque. Variation in laxity between specimens was observed, consistent with previous reports. These data indicate that the ankle is less stable in plantarflexion when inversion and internal rotation forces are applied. This may explain why the lateral ankle ligaments are most prone to injury in this position. The ankle was less stable in dorsiflexion when eversion and external rotation forces were applied. This is consistent with the observation that deltoid ligament injuries occur in the neutral to dorsiflexion position. The study demonstrates the importance of examining patients with suspected ankle ligament injuries in several ankle positions. The ankle testing device has potential application for in vivo testing of patients with suspected ankle ligament instability.     

Assessment of the lateral ligaments of the ankle after healed fractures

BACKGROUND: Lateral ligament complex injuries are difficult to diagnose immediately after ankle fracture, and treatment is focused on the fracture. This study examines the prevalence of ligamentous injuries after severe ankle fractures. METHODS: Lateral ligament instability can be revealed by inversion and anterior stress views after fracture healing. The results of 54 inversion and anterior stress examinations of the ankle after fracture healing, using a Telos stress device at 15 kPa force, were compared with uninjured ankles. RESULTS: No patient had 5 degrees or more of talar tilt or 6 mm or more of anterior displacement of the talus in uninjured ankles; however, in ankles with fractures, we found abnormal talar tilt angle in 12 and excessive anterior displacement in five. An abnormal inversion stress test was found to be considerably more common in the fractured ankles. CONCLUSION: Our study revealed that lateral ligament injuries may occur simultaneously with ankle fractures, with the most frequently injured being the calcaneofibular ligament.     

Repeated ankle sprains and delayed neuromuscular response: acceleration time parameters

STUDY DESIGN: A comparative study. OBJECTIVES: To assess whether in subjects with unilateral chronic ankle instability the dynamic reaction time of the affected ankle differs from the healthy ankle and from ankles of a control group. BACKGROUND: Reaction time is an essential element in joint protection against sudden unexpected excessive movement requiring fast and coordinated muscle action. During a sudden ankle inversion movement, a reflex action of the evertor muscles is needed to counteract the movement. Adequate neuromuscular response is crucial and a delayed response could contribute to inversion trauma and subsequently to chronic ankle instability. The isokinetic dynamometer acceleration time (ACC-TIME) provides valuable information on dynamic neuromuscular ability. MATERIAL AND METHODS: Patients with unilateral chronic ankle instability (n = 11) and healthy individuals in a control group (n = 11) were tested on an isokinetic dynamometer during 3 sets of 3 reciprocal inversion/eversion movements of both ankles at 30 degrees/s and 120 degrees/s. Analysis of variance models were used to compare the ACC-TIME of the affected ankle to the unaffected ankle of the same subjects and a control group. RESULTS: For the evertor muscles at 30 degrees/s and 120 degrees/s a significantly prolonged ACC-TIME was found when comparing the affected ankles to the contralateral ankles and both ankles of the control group. For the invertor muscles at 120 degrees/s a significantly prolonged ACC-TIME was found when comparing the affected ankle to the unaffected ankles of patients and those of the control group. CONCLUSIONS: Because the most important evertor muscles are innervated by the fibular nerve, the significantly prolonged ACC-TIME of the affected ankle is consistent with the finding of a lower motor nerve conduction velocity of the fibular nerve after inversion trauma. The results support the concept of a delayed neuromuscular response as an important factor in the etiology of chronic ankle instability.     

Characteristics of Chronic Ankle Instability Requiring Both Anterior Talofibular and Calcaneofibular Ligament Repair

Chronic ankle instability (CAI) leads to the ankle osteoarthritis (OA), and ligament repair is performed to restore ankle stability. However, anterior talofibular ligament (ATFL) repair alone is not sufficient to stabilize the ankle in some cases, which additionally require calcaneofibular ligament (CFL) repair. This study aimed to explore characteristics of CAI that necessitated the repair of both ATFL and CFL. Forty-three patients (44 ankles) with CAI treated operatively were retrospectively reviewed. After ATFL repair, patients with residual ankle instability revealed by the varus stress under fluoroscopy additionally underwent CFL repair. Preoperative condition and intraoperative findings of the combined ATFL and CFL repair (AC) (n = 24) and only ATFL repair (A) (n = 20) groups were compared. The ankle activity score of group AC was significantly higher (p < .05) than that of group A. OA changes at the medial gutter were observed in 62.5% (15/24) in the group AC and 20% (4/20) in group A. Chondral/osteochondral lesions were seen in 66.7% (16/24) in the group AC and 20% (4/20) in group A. The remnant quality in group AC was inferior to that of group A. CAI that necessitated both ATFL and CFL repair exhibited characteristic findings such as high ankle activity score, high rate of chondral/osteochondral lesions and/or OA changes, and poor quality of ATFL remnants compared to those in CAI that required only ATFL repair. The repair of both ATFL and CFL should be considered in CAI which exhibit these characteristics to ensure complete correction of the instability.     

Lack of Definition of Chronic Ankle Instability With Arthrometer-Assisted Ankle Joint Stress Testing: A Systematic Review of In Vivo Studies

Despite extensive research on ankle instability a consensual and clear objective definition for pathological mechanical lateral ankle instability is yet to be determined. This systematic review aimed to summarize current available arthrometric devices, measuring methods and lateral ankle laxity outcomes in patients with chronic ankle instability that underwent objective arthrometric stress measurement. Sixty-eight studies comprising a total of 3,235 ankles with chronic ankle instability were included. Studies reported a wide range of arthrometric devices, testing position and procedures, and measuring methods. For the anterior drawer test, the average mean differences between injured and uninjured ankles ranged from -0.9 to 4.1 mm, and total translation in the injured ankle from 3.2 to 21.0 mm. Most common pathological threshold was ≥4 mm or ≥10 mm unilaterally and ≥3 mm bilaterally. For the talar tilt test, the average mean differences between injured and uninjured ankles ranged from 0.0° to 8.0°, and total tilt from injured ankle from 3.3 to 60.2°. Most common pathological threshold was ≥ 10° unilaterally and ≥ 6° mm bilaterally. It was found high heterogeneity in the scientific literature regarding the arthrometric devices, use of concomitant imaging and measuring methods of arthrometer-assisted anterior drawer and talar tilt tests which led to variable laxity outcomes in individuals with chronic ankle instability. Future studies should focus on standardizing the testing and measuring methods for an objective definition of mechanical ankle instability.     

The effect of axial load on the in vivo anterior drawer test of the ankle joint complex

The anterior drawer test is commonly used in the diagnosis of ankle joint mechanical instability. However, the effect of axial load on the anterior drawer test has not been examined in vivo. The purpose of the study was to assess the effect of axial load on passive anterior instability, and on the diagnostic measurement of the anterior drawer instability of the ankle joint complex. A total of 21 subjects with various degrees of ankle sprains were tested on a device that could continuously record applied anterior force and the resultant displacement of the rear-foot. Anterior drawer flexibility of the ankle joint complex in a neutral dorsi/plantar flexion position was quantified on both feet for all subjects without and with an axial load (385 N). Flexibility of the ankle joint complex in anterior drawer was defined as the slope of a linear load-displacement curve (which fitted test data with high correlation coefficients (r>0.991)). With axial load, anterior drawer flexibility was significantly reduced by 28.8% compared to that without axial load. The difference in anterior drawer flexibility between injured and intact ankles significantly decreased with axial load. An axial load increased the stability of ankle joint complex. However, axial load reduced the sensitivity of anterior drawer test to mechanical instability of the ankle joint complex.     

Long-term results of the Chrisman-Snook operation for reconstruction of the lateral ligaments of the ankle

The Chrisman-Snook procedure for instability of the lateral ankle ligaments, first described in 1969, reconstructs the anterior talofibular ligament and the calcaneofibular ligament using one-half of the peroneus brevis tendon, routed through tunnels in the fibula and calcaneus. In the present long-term evaluation of the results of this procedure, forty-eight of sixty ankles, in fifty-seven patients, were assessed after a mean follow-up of ten years (range, four to twenty-four years). The results were excellent in thirty-eight ankles, good in seven, fair in two, and poor in one. The two ankles with a fair result were improved but still had some persistent instability, while the ankle with a poor result (no improvement) was in a patient with generalized ligament laxity. All three patients with a fair or poor result had had a severe reinjury to the ankle. Based on the findings in this study, we concluded that this procedure will restore good long-term function in a high percentage of patients who are disabled by ankle instability due to unhealed or neglected tears of the lateral ligaments.     

Instrumented measurement of anterior laxity of the knee

We performed instrumented measurement of anterior-posterior laxity of the knee in thirty-three cadaver specimens, 338 normal subjects, and eighty-nine patients with unilateral disruption of the anterior cruciate ligament. The test instrument was the Medmetric knee arthrometer, model KT-2000. We measured total anterior-posterior laxity, produced by anterior and posterior loads of eighty-nine newtons (twenty pounds), and the anterior compliance index. The total anterior-posterior laxity is composed of an anterior displacement and a posterior displacement; these are measured from a testing reference position, defined as the resting position of the knee after applying and then releasing a posterior load of eighty-nine newtons. The anterior compliance index is defined as the anterior displacement between an anterior load of sixty-seven newtons and one of eighty-nine newtons. All tests were performed with the knee held on a thigh support that placed the knee in 20 +/- 5 degrees of flexion. The mean anterior displacement at eighty-nine newtons was 5.7 millimeters in a group of normal subjects and 13.0 millimeters in a group of patients with a disrupted anterior cruciate ligament. Ninety-two per cent of the normal subjects had a left knee-right knee difference in anterior displacement of no more than two millimeters, while 96 per cent of the patients with a unilateral disruption of the anterior cruciate ligament had an injured knee-normal knee difference in anterior displacement of more than two millimeters. Ninety-three per cent of the normal subjects had a difference in the left-right compliance index of no more than 0.5 millimeter, and 85 per cent of the patients with unilateral disruption of the anterior cruciate ligament had a difference in the compliance index of the injured and normal sides of more than 0.5 millimeter.     

Detecting Ankle Instability With an Instrumented Ankle Arthrometer: An Experimental Study

A new instrumented device was developed to quantify ankle joint stability during an anterior talar drawer test. The aim of the present study was to validate this device comparing bone kinematics with arthrometer measurement outcomes. An anterior talar drawer test was performed with 14 cadaver legs using a custom instrumented ankle arthrometer. Using clusters of bone‐pin markers, the relative three‐dimensional movement of calcaneus, talus, and fibula was simultaneously measured. Anterior drawer test was applied on the intact foot and after sequentially sectioning the anterior talofibular ligament, the calcaneofibular ligament, and the posterior talofibular ligament. Cutting the anterior talofibular ligament caused a significant increase in bone‐pin measured anterior translations of calcaneus and talus as well as in the anterior translation of the arthrometer. Analysis of receiver operating characteristic curves indicates a fair to good ability to discriminate between the intact and the sectioned conditions with the arthrometer. Distal distraction, inversion, and internal rotation movements were observed when two and three ligaments were cut. Results revealed that the ankle arthrometer was sensitive to detect changes in bone‐to‐bone movements during an anterior talar drawer test, when the anterior talofibular ligament was sectioned. Presumably due to movements in additional planes of motion, the arthrometer was not able to differentiate between situations with one or more ligaments cut. In conclusion, the instrumented anterior talar drawer tester may augment current procedures in assessing ankle instability primarily caused by ruptures of the anterior talofibular ligament. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2019–2026, 2019     

Twenty-year results of the Evans operation for lateral instability of the ankle

Twenty-four patients (25 ankles), operated on using the static modification of the Evans tenodesis for lateral instability, were evaluated 19 to 21 years after surgery. Twelve of the patients (12 ankles) had excellent results, seven patients (eight ankles) had good results, three patients (three ankles) had fair results, and two patients (two ankles) had poor results. The subjective results had no clear correlation to the stress radiographs, which showed minor or moderate anterior talar translation in 10 ankles. Moreover, the difference between the surgically treated and the contralateral ankle was not significant. Static modification of the Evans tenodesis is recommended if an anatomic reconstruction of the lateral ligaments is not feasible (general laxity of joints, reoperation).     

The Effects of Chronic Ankle Instability on the Biomechanics of the Uninjured,Contralateral Ankle During Gait

ObjectiveTo determine whether unilateral chronic ankle instability (CAI) affects the kinematics of the uninjured contralateral ankle.MethodsIn this case‐control study, 15 adult patients with unilateral CAI and 15 healthy controls were studied. Both the unstable and uninjured ankles in patients with unilateral CAI (CAI group, n = 15) were compared with that of healthy individuals (control group, n = 15). Applying body photo‐reflective markers, the participant''s motion during gait was measured. Biomechanical variables including overall ankle‐toe angle, linear velocity, linear acceleration, angular velocity, angular acceleration, range of motion (RoM) in dorsiplantar flexion, and inversion‐eversion at initial contact, loading response, mid‐stance, terminal stance, pre‐swing, and swing phase of the gait were measured.ResultsIn patients with CAI, the injured and uninjured ankles were significantly different regarding angle‐toe angle, inversion‐eversion RoM, dorsiplantar flexion in mid‐stance, inversion‐eversion at initial contact and terminal stance as well as the pre‐swing and swing phases (p < 0.01). The uninjured ankles of patients showed lower ankle‐toe velocity (p = 0.01) and acceleration (p = 0.01) compared to both the left and right ankles of the controls. In addition, the uninjured ankles of the patients showed decreased ankle dorsiflexion and increased inversion during initial contact, loading response, mid‐stance, terminal stance, pre‐swing, and swing compared to the control group (p < 0.017).ConclusionThe results suggest that unilateral CAI can affect gait biomechanics in the contralateral uninjured ankle. Left unaddressed, unilateral CAI may lead to increased morbidity to the contralateral uninjured side. When surgery is not preferred for the management of unilateral CAI, rehabilitation protocols should focus on both sides.     

Reconstruction of the lateral ankle ligaments using a split peroneus brevis tendon graft

Thirty-one consecutive ankles in 30 patients with chronic lateral ankle instability were reconstructed using a split peroneus brevis tendon graft. All patients had pain and instability despite adequate treatment and a rehabilitation program. Six patients had clinical and radiographic evidence of associated subtalar laxity. Four patients (four ankles) had prior Brostrom ligament reconstructions. The average time from the initial injury or treatment to surgery was 23 months. At a mean follow-up of 44 months (range, 24-64 months), the functional results included excellent in 20 ankles, good in 9, fair in 1, and poor in 1. Ankle stability, which did not deteriorate with time, was achieved in 30 of 31 ankles. This procedure is simple, safe, and reliable with a 94% good to excellent clinical result and 97% mechanical stability. It is an excellent reconstruction choice for those individuals with high demand ankles, with a longstanding ankle instability with or without subtalar instability, and for failed primary reconstruction.     

Taping the ankle for chronic instability

Twenty patients with chronic ankle instability were examined radiographically for anterior talar displacement and talar tilting. The examinations were carried out with the ankles untaped and taped, and the taped ankles were examined again after 20 min running. The measurable instability was significantly improved after taping, but after exercise this was seen only for talar tilting. Generally, the best stabilizing effect of taping was obtained in the ankles with the greatest degree of instability. After exercise, all but one of the adhesive taping bandages were loose and were mostly acting as canvas boots, affording the ankle only limited protection.     

Congenital Dislocation of the Head of the Radius

Twenty patients with chronic ankle instability were examined radiographically for anterior talar displacement and talar tilting. The examinations were carried out with the ankles untaped and taped, and the taped ankles were examined again after 20 min running. The measurable instability was significantly improved after taping, but after exercise this was seen only for talar tilting. Generally, the best stabilizing effect of taping was obtained in the ankles with the greatest degree of instability. After exercise, all but one of the adhesive taping bandages were loose and were mostly acting as canvas boots, affording the ankle only limited protection.     

The effect of a 4-week comprehensive rehabilitation program on postural control and lower extremity function in individuals with chronic ankle instability

STUDY DESIGN: Prospective, randomized controlled trial. OBJECTIVE: To examine the effects of a 4-week rehabilitation program for chronic ankle instability (CAI) on postural control and lower extremity function. BACKGROUND: CAI is associated with residual symptoms, performance deficits, and reinjury. Managing CAI is challenging and more evidence is needed to guide effective treatment. METHODS AND MEASURES: Subjects with unilateral CAI were randomly assigned to the rehabilitation (CAI-rehab, n=16) or control (CAI-control, n=13) group. Subjects without CAI were assigned to a healthy group (n=19). Baseline testing included the (1) center of pressure velocity (COPV), (2) star excursion balance test (SEBT), and (3) Foot and Ankle Disability index (FADI) and FADI-Sports Subscale (FADI-Sport). The CAI-rehab group completed 4 weeks of rehabilitation that addressed range of motion, strength, neuromuscular control, and functional tasks. After 4 weeks, all subjects were retested. Nonparametric analyses for group differences and between-group comparisons were performed. RESULTS: Subjects with CAI demonstrated deficits in postural control and SEBT reach tasks of the involved limb compared to the uninvolved limb and reported functional deficits of the involved limb compared to healthy subjects. Following rehabilitation, the CAI-rehab group had greater SEBT reach improvements on the involved limb than the other groups and greater improvements in FADi and FADI-Sport scores. CONCLUSIONS: These results demonstrate postural control and functional limitations exist in individuals with CAl. In addition, rehabilitation appears to improve these functional limitations. Finally, there is evidence to suggest the SEBT may be a good functional measure to monitor change after rehabilitation for CAI.     

Role of the peroneal tendons and superior peroneal retinaculum as static stabilizers of the ankle

The role of the peroneal tendons as static stabilizers of the ankle is poorly understood. Anterior-posterior displacement of the talus was evaluated in eight fresh-frozen cadaveric ankle joints. With the distal tibia stabilized, loads of 150 N were applied to the talus in the anterior direction while the ankle was held in neutral. All tests were initially performed on intact specimens. Loads were reapplied after sequential sectioning of the peroneal tendons and superior peroneal retinaculum and then the anterior talofibular ligament. When compared with intact ankles, releasing the peroneal tendons caused an average increase of 15% displacement (0.90 mm, p < .05). Adding the release of the anterior talofibular ligament increased the anterior displacement an additional 16% (1.35 mm, p < .05) for a combined anterior laxity of 34% (2.25 mm, p < .05). The data suggest that the peroneal tendons along with the superior peroneal retinaculum provide static resistance to anterior talar displacement with the ankle in neutral. This may contribute to the overall stability of the lateral ankle not previously recognized.