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Tibial plafond fractures. How do these ankles function over time?

BACKGROUND: The intermediate outcome of fractures of the tibial plafond treated with current techniques has not been reported, to our knowledge. The purpose of this study, performed at a minimum of five years after injury, was to determine the effect of these fractures on ankle function, pain, and general health status and to determine which factors predict favorable and unfavorable outcomes. METHODS: Fifty-six ankles (fifty-two patients) with a tibial plafond fracture were treated with a uniform technique consisting of application of a monolateral hinged transarticular external fixator coupled with screw fixation of the articular surface. Thirty-one patients with thirty-five involved ankles returned between five and twelve years after the injury for a physical examination, assessment of ankle pain and function with the Iowa Ankle Score and Ankle Osteoarthritis Scale, assessment of general health status with the Short Form-36 (SF-36), and radiographic examination of the ankle. RESULTS: Arthrodesis had been performed on five of the forty ankles for which the outcome was known at a minimum of five years after the injury. Other than removal of prominent screws (two patients), no other surgical procedure had been performed on any patient. The average Iowa Ankle Score was 78 points (range, 28 to 96 points). The scores on the SF-36 and Ankle Osteoarthritis Scale demonstrated a long-term negative effect of the injury on general health and on ankle pain and function when compared with those parameters in age-matched controls. The degree of osteoarthrosis was grade 0 in three ankles, grade 1 in six, grade 2 in twenty, and grade 3 in six. The majority of patients had some limitation with regard to recreational activities, with an inability to run being the most common complaint (twenty-seven of the thirty-one patients). Fourteen patients changed jobs because of the ankle injury. Fifteen ankles were rated by the patient as excellent; ten, as good; seven, as fair; and one, as poor. Nine patients with previously recorded ankle scores had better scores after the longer follow-up interval. The patients perceived that their condition had improved for an average of 2.4 years after the injury. CONCLUSIONS: Although tibial plafond fractures have an intermediate-term negative effect on ankle function and pain and on general health, few patients require secondary reconstructive procedures and symptoms tend to decrease for a long time after healing.

Adult↗

Single-leg jump-landing stabilization times in subjects with functionally unstable ankles.

CONTEXT: Factors contributing to functional ankle instability may cause individuals with the condition to land from a jump differently than those with stable ankles. OBJECTIVE: To determine stabilization time differences during single-leg jump landings between stable and unstable ankle groups and to report the reliability and precision of time-to-stabilization measures. DESIGN: A mixed design with 1 between factor (ankle group) and 1 within factor (direction) was used to analyze the comparison between our 10 subjects with functional ankle instability and 10 subjects with stable ankles. Time to stabilization (seconds) was the dependent measure. Reliability for time-to-stabilization measures of our 12 additional subjects with stable ankles were assessed using intraclass correlation coefficients (ICC 2,7). Standard errors of measurements were also calculated for time-to-stabilization measures. SETTING: Sports medicine research laboratory. PATIENTS OR OTHER PARTICIPANT(S): Ten subjects with functional ankle instability who reported at least 2 sprains and "giving way'' sensations at their ankles constituted the functional ankle instability group. Ten subjects without a history of ankle sprain injury served as healthy subjects. Twelve additional healthy subjects participated in the reliability study. INTERVENTION(S): Subjects performed a jump-landing test, which required them to jump 50% to 55% of their maximum vertical jump height and then land on a single leg on a force plate. After landing, they stabilized quickly and remained as motionless as possible in a single-leg stance for 20 s. MAIN OUTCOME MEASURE(S): Anterior-posterior and medial/ lateral vibration magnitude curve fit time-to-stabilization. RESULTS: Time to stabilization was longer for the functional ankle instability group (1.98 +/- 0.81 s) than for the stable ankle group (1.45 +/- 0.30 s) (P < .05). Reliability (standard error of the measurement) values for anterior/posterior and medial/lateral time-to-stabilization were 0.79 (0.15 s) and 0.65 (0.26 s), respectively. CONCLUSIONS: Time to stabilization was longer for subjects with functional ankle instability than subjects with stable ankles. The ankle instability may have impaired the subjects' ability to stabilize after a single-leg jump landing. Reliabilities and standard errors of the measurements of time-to-stabilization measures were moderate and low, respectively.

Journal Article↗

Syndesmosis sprains of the ankle. The influence of heterotopic ossification.

A retrospective study of 50 syndesmosis sprains in 44 football players was performed. Five patients (6 ankles) were lost to follow-up, allowing review of 44 injuries. Average follow-up was 47 months. The patients were evaluated for recurrent injury, overall ankle function, and for persistent ankle symptoms, including stiffness, pain, limping, and swelling. Follow-up radiographs of the injured ankle were obtained in 22 patients. The average return time to full activity was 31 days. Pain with pushing-off was a major factor preventing return to activity. At final followup, 36% of the patients complained of persistent mild to moderate stiffness of the ankle. Twenty-three percent had mild to moderate pain, usually with activity. One patient had a mild limp with activity, and 18% of the ankles had persistent mild to moderate swelling. Ankle function was rated as good to excellent in 86%. All patients with fair results had recurrent ankle sprains. There were no poor results. Eleven of the 22 patients with follow-up radiographs developed heterotopic ossification within the interosseous membrane, but no patient developed a frank synostosis. The patients with heterotopic ossification required an average of 11 days more recovery time than those without ossification. There was no significant difference between the 2 groups' ultimate ratings of ankle function or ankle symptoms, but the ankles with heterotopic ossification were associated with more recurrent lateral ankle sprains. We conclude that syndesmosis sprains require a longer recovery period than other types of ankle sprains. Most of these injuries showed good to excellent ankle function after recovery, unless there was a recurrent ankle sprain.2+ formation of heterotopic ossification.

Adult↗

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.

Adult↗

Single leg balance test to identify risk of ankle sprains.

BACKGROUND: Ankle sprains are a common and potentially disabling injury. Successful prediction of susceptibility to ankle sprain injury with a simple test could allow ankle sprain prevention protocols to be initiated and help prevent disability in the athletic population. OBJECTIVE: To investigate the ability of the single leg balance (SLB) test, carried out at preseason physical examination, to predict an ankle sprain during the autumn sports season. DESIGN: Prospective cohort study SETTING: High school varsity athletics and intercollegiate athletics. MAIN OUTCOME MEASURE: Ankle sprains in athletes with positive SLB tests. RESULTS: The association between a positive SLB test and future ankle sprains was significant. Controlling for confounding variables, the relative risk for an ankle sprain with a positive SLB test was 2.54 (95% confidence interval, 1.02 to 6.03). Athletes with a positive SLB test who did not tape their ankles had an increased likelihood of developing ankle sprains. The relative risk for ankle sprain for a positive SLB test and negative taping was 8.82 (1.07 to 72.70). A history of previous ankle injury was not associated with future ankle sprains in this study. The kappa value for interrater reliability for the SLB test was 0.898 (p<0.001). CONCLUSIONS: An association was demonstrated between a positive SLB test and ankle sprain. In athletes with a positive SLB test, not taping the ankle imposed an increased risk of sprain. The SLB test is a reliable and valid test for predicting ankle sprains.

Adolescent↗

Total ankle arthroplasty with the Agility prosthesis: clinical and radiographic evaluation.

BACKGROUND: Although ankle arthrodesis remains a standard operative procedure for disabling ankle arthritis, it has potential long-term problems. Total ankle arthroplasty offers preserved joint motion and may be a more favorable option in select patients. The purpose of this study was to report the intermediate-term clinical and radiographic results of total ankle arthroplasty using the Agility prosthesis. METHODS: We retrospectively reviewed the results of total ankle arthroplasty in 41 consecutive patients (43 ankles). Evaluation included preoperative and postoperative questionnaires, physical examination, and radiographs. RESULTS: At the time of followup, 38 patients (40 ankles) were available for review. The most common preoperative diagnoses included posttraumatic arthritis (24 of 40 ankles, 60%) and rheumatoid arthritis (eight of 40 ankles, 20%). Average age at surgery was 63 (range 32 to 85) years. Average followup was 44.5 (range 26 to 64) months. Preoperative and postoperative American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scores averaged 33.6 and 83.3, respectively, demonstrating significance (p < 0.001). Postoperative Medical Outcomes Study Short Form-36 (SF-36) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores averaged 49.5 and 56.1, respectively. Although 34 of 40 ankles demonstrated radiographic lucency or lysis, the degree of involvement varied. Migration or subsidence of components was noted in 18 ankles. Overall, 37 of 38 patients were satisfied with the outcome of their surgery and would have the same procedure under similar circumstances. CONCLUSIONS: Agility total ankle arthroplasty results in a favorable clinical outcome and patient satisfaction in most patients at intermediate-term followup. However, total ankle arthroplasty is associated with potential complications and the need for subsequent operative intervention. Radiographic followup commonly reveals periprosthetic lucency, lysis, and component migration or subsidence, but this does not appear to adversely affect the intermediate-term clinical outcome. The long-term consequences of such radiographic findings are of concern, and surgeons and patients choosing this procedure need to be cautious.

Adult↗

Peroneal Reaction Times and Eversion Motor Response in Healthy and Unstable Ankles.

OBJECTIVE: To measure and compare latency, electromechanical delay, and speed of motor response of the peroneus longus muscle in a large sample of subjects with healthy or unstable ankles. DESIGN AND SETTING: Subjects with healthy or unstable ankles underwent identical test procedures consisting of 6 consecutive, sudden 50 degrees ankle-inversion movements in the standing position with full weight on the tested leg. Latency, first and second decelerations, and total inversion time were monitored. In a separate setting, electromechanical delay was measured during a voluntary ankle eversion. SUBJECTS: We tested 81 subjects (27 males, 54 females) with healthy ankles or unilateral or bilateral ankle instability: 40 individuals with 48 unstable ankles (18 males, 22 females; age range, 18 to 23 years), and 41 individuals with 46 healthy ankles (9 males, 32 females; age range 15 to 29 years). MEASUREMENTS: Using surface electromyography, the latency of the peroneus longus muscle was measured during sudden inversion. Simultaneously, using accelerometry, first and second decelerations were measured. Separately, the electromechanical delay was measured using electromyography and accelerometry. RESULTS: The time of the first deceleration was significantly shorter in subjects with unstable ankles (25.5 milliseconds versus 28.4 milliseconds for those with healthy ankles). The latency, total inversion time, second deceleration time, and electromechanical delay were not shown to be significantly different between healthy and unstable ankles. CONCLUSIONS: The significantly shorter first deceleration during sudden inversion in the standing position in subjects with unstable ankles compared with subjects with healthy ankles is explained by less control of inversion speed in the first phase of the sudden inversion in unstable ankles. Our study does not confirm the results of the systematic literature search showing a longer latency in subjects with unstable ankles.

Journal Article↗

Development and reliability of the ankle instability instrument.

CONTEXT: Functional ankle instability has been defined in a variety of ways. Factors that are frequently used in this definition include a history of a severe ankle sprain, a history of multiple ankle sprains, and a recurrent feeling of instability or "giving way." With all the variations in defining functional ankle instability, it becomes increasingly important to develop a more consistent framework for assessing this instability. OBJECTIVE: To develop a new ankle instability assessment tool, the Ankle Instability Instrument, and evaluate the reliability of this instrument. DESIGN: Test-retest reliability was evaluated using intraclass correlation coefficients (2,1) for each item, each factor, and the total score between test days 1 and 2. Cronbach alpha was calculated to estimate internal consistency of the 12 items. SETTING: Classrooms, offices, athletic fields, and private residences. PATIENTS OR OTHER PARTICIPANTS: College students (29 males, 72 females, age = 20.7 +/- 2.7 years), including 73 (72%) with and 28 (28%) without a history of ankle injury. MAIN OUTCOME MEASURE(S): Subjects were asked to complete the Ankle Instability Instrument on 2 occasions approximately 1 week apart. RESULTS: An exploratory factor analysis of the Instrument produced 3 factors and reduced it from 21 to 12 items. The factors accounted for 32.3%, 10.7%, and 7.0% of the variance, respectively. Together, these factors accounted for 50.0% of the variance in the responses to the Instrument. Test-retest reliability ranged from .70 (SEM = 0.28) to .98 (SEM = 0.06) for the individual items and .95 (SEM = 1.85) for the Instrument overall. The Cronbach alpha coefficient was .92 for factor 1 (severity of initial ankle sprain), .87 for factor 2 (history of ankle instability), .81 for factor 3 (instability during activities of daily life), and .89 for the Instrument overall. CONCLUSIONS: The creation of the Ankle Instability Instrument is a first step in recognizing a more objective way of identifying patients suffering from functional ankle instability. The high reliability we found shows that self-reporting of ankle symptoms is a feasible, appropriate way to obtain information on the presence of instability symptoms. Additionally, through this preliminary study, we found 3 factors that represent unique and important components of functional ankle instability. Clinicians and researchers can, therefore, use these 12 items, either alone or in combination with other information, to determine if functional ankle instability is present.

Journal Article↗

Ligamentous posttraumatic ankle osteoarthritis.

BACKGROUND: Ankle sprains are the most common injuries in sports and recreational activities. HYPOTHESIS: Ankle osteoarthritis can be caused by ankle ligament lesions. Latency time between injury and osteoarthritis is influenced by the type and side of the injured ligaments. The side of the ligamentous lesion correlates with the hindfoot alignment. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Of a cohort of 247 patients with ankle arthritis, we reviewed data from 30 patients (33 ankles; mean age, 58.6 years) with ligamentous end-stage ankle osteoarthritis. The patients were evaluated etiologically, clinically, and radiologically. RESULTS: Etiologic analysis: 55% had a ligamentous lesion from sports injuries (soccer, 33%); 85% injured the lateral ankle ligaments, and 15% injured the medial and medial-lateral ligaments. The mean latency time between injury and osteoarthritis was 34.3 years. The survivorship rate for single severe ankle sprains was worse than that for chronic recurrent ligamentous lesions (mean latency time, 25.7 vs 38.0 years; P < .05), and the rate for medial sprains was worse than for lateral sprains (mean latency time, 27.5 vs 35.0 years; P < .05). At follow-up, the American Orthopaedic Foot and Ankle Society hindfoot score was 23.0 points, 52% had varus malalignment, 52% had persistent instability, and the mean ankle arthritis grade was 2.6 points. There was a correlation between chronic lateral ankle instability and varus malalignment. CONCLUSION: Lateral ankle sprains in sports are the main cause of ligamentous posttraumatic ankle osteoarthritis and correlate with varus malalignment. At the time of end-stage ligamentous ankle osteoarthritis, persistent instability may be encountered.

Adult↗

Functional roles of ankle and hip sagittal muscle moments in able-bodied gait.

OBJECTIVE: The main objectives of this study on able-bodied gait were (a) to identify the main functions of the ankle and hip muscle moments and their contribution to support and propulsion tasks, and (b) to illustrate the interaction between the ankle and hip moment activities. DESIGN: Twenty young, able-bodied male subjects walked along a 13 m path at a freely chosen speed. BACKGROUND: Functional contributions of the ankle and hip muscles and their interactions in achieving support and propulsion tasks during gait are still subject to controversy. METHODS: Principal component analysis was applied as a curve structure detection method to identify the main functional characteristics of the ankle and hip muscle moments. The first two principal components which contained over 70% and 85%, respectively, of the information in the ankle and hip moment curves revealed their functional tasks. Ankle versus hip moment plots was used to illustrate the interactions between muscles acting at the hip and ankle in the sagittal plane. Correlation coefficient and covariance calculations quantified the interaction between the ankle and hip moments. RESULTS: The first principal component revealed that the main role of the ankle and hip is to keep the body from collapsing. The second principal component is associated with the functional contribution of both ankle plantarflexors and hip flexors during the propulsion phase (50-60% of the gait cycle). High coordination (r=0.82) between the ankle and hip moments was observed. CONCLUSION: Maintaining body support against gravity was identified as the first functional task of the ankle plantarflexors and hip extensors, while contribution to propulsion was recognised as the second major role for the ankle plantarflexors and hip flexors. RELEVANCE: Identifying the main roles of the muscles acting at the hip and ankle during able-bodied walking provides better insight into how pathological gait should be evaluated.

Adult↗

Ankle fractures in the elderly: what you get depends on where you live and who you see.

OBJECTIVES: This study was performed to determine 1) the rate of ankle fractures in the elderly in the United States stratified by hospital referral region, and 2) whether the percentage of ankle fractures treated surgically is affected by factors, such as fracture location, hospital referral region, concentration of orthopaedists, presence of a teaching hospital in that region, patient age, race, gender, or the number and type of specific medical comorbidities. DESIGN: A 20% sample of Medicare Part B claims from the years 1998 to 2000 was analyzed. PATIENTS/INTERVENTION: The CPT codes for operative and nonoperative treatment of isolated medial malleolar, isolated lateral malleolar, bimalleolar, and trimalleolar fractures were identified. These codes were used to determine the overall rate of ankle fractures and individual fracture types. MAIN OUTCOME MEASUREMENT: : The rate of ankle fractures was evaluated by hospital referral region, patient age (groups of 5 years, aged 65 years or older), gender, and race. The percentage of surgical treatment was determined for each fracture type as the number of surgically treated fractures over the total number of ankle fractures within each subtype and analyzed by fracture type, hospital referral region, and concentration of orthopaedists in that region, presence of a teaching hospital within the hospital service area, patient age, gender, race, and number and type of specific medical comorbidities. Regression was performed by using the above variables. RESULTS: We identified 33,704 ankle fractures: 7.6% were isolated medial malleolar, 50.8% were isolated lateral malleolar, 27.4% were bimalleolar, and 14.2% were trimalleolar fractures. The overall United States average was 4.2 ankle fractures per 1000 Medicare enrollees. The rate of ankle fractures varied by a factor of 8, from 1 per 1000 Medicare enrollees in San Francisco, CA, to 8.3 in Hickory, NC. The rate of ankle fractures was highest in white women at 5.8 and lowest in nonwhite men at 1.5 per 1000 Medicare enrollees. The overall rate of ankle fractures that underwent surgical stabilization was 33%, ranging from 14% in Binghampton, NY, to 72% in Napa, CA. The rate of surgical intervention was 22% for isolated medial malleolar fractures, 11% for isolated lateral malleolar fractures, 58% for bimalleolar fractures, and 74% for trimalleolar fractures. In regression analysis, the factors associated with nonoperative care after ankle fracture were: older age, female gender, increasing number of comorbidities as measured by the Charlson index, presence of diabetes or peripheral vascular disease, and living in a hospital service area that had a designated teaching hospital. Beneficiaries living in areas in which a hospital was a member of the Council of Teaching Hospitals were less likely to receive surgical treatment of their ankle fracture. Increasingly older age was strongly associated with decreased likelihood of having surgical intervention, with each 5 year age grouping progressively less likely to have surgical treatment. The concentration of orthopaedists in the region was not associated with the likelihood of having surgical treatment. CONCLUSIONS: The term ankle fracture involves a wide spectrum of injuries. We found a large variation through the United States in both the rate of ankle fractures and the percentage of those that undergo surgical intervention.

Age Distribution↗

Immobilization with removable walking brace for treatment of chronic foot and ankle pain.

Fifty feet and ankles in 47 patients (three bilateral) (26 women and 21 men; average age, 44+/-15 years) were treated for chronic foot and ankle pain (duration: minimum, three months; average, 27+/-35 months; range, three to 132 months). Evaluation included detailed history, physical examination, and radiography. Initial treatment consisted of immobilization (full weight-bearing) using a removable walking brace (23.5 hours per day, including in bed at night), with standing and walking limited to activities of daily living. Follow-up evaluation included assessment of pain response and repeat physical examination. There was a history of trauma in 32 (64%) feet and ankles. Braces (pneumatic in 31 [62%] and double-upright in 19 [38%] feet and ankles) immobilized the ankle in neutral position and included a rigid rocker sole. After an average of 13+/-10 weeks (range, three to 50 weeks) of brace use, pain symptoms were improved in 35 (70%), unchanged in 11 (22%), and worse in four (8%) feet and ankles. Physical examination was improved in 43 (86%) feet and ankles, unchanged in six (12%) feet and ankles, and worse in one (2%) foot and ankle. In all 50 feet and ankles, the average number of abnormal physical findings decreased from initial (6+/-3 abnormal physical findings) to follow-up evaluation (3+/-3 abnormal physical findings) (P < 0.001). The average number of diagnoses per foot and ankle decreased from initial (4+/-1 diagnoses per foot and ankle) to follow-up evaluation (2+/-1 diagnoses per foot and ankle) (P < 0.0001). Improvement of pain was independent of duration of pre-existing symptoms, patient age, gender, or type of brace used. In summary, immobilization with a removable walking brace may improve chronic foot and ankle pain and localize the primary source of symptoms.

Adult↗

Kinematic changes after fusion and total replacement of the ankle: part 2: Movement transfer.

INTRODUCTION: The purpose of this in vitro study was to determine the biomechanical characteristics of the ankle based on the movement transfer between foot and leg before and after ankle arthrodesis, and after implantation of three currently used total ankle prostheses. METHODS: A 6-df device with an axial load of 200 N and a four-camera high-speed video system were used for the measurement of the range of motion in six fresh-frozen cadaveric leg specimens. While the foot was moved through the range of dorsiflexion/plantarflexion, the resulting foot eversion/inversion and tibial rotation were recorded. Analogously, the resulting foot eversion/inversion from tibial rotation and, vice versa, the resulting tibial rotation from foot eversion/inversion were determined. The same measurements were performed for the normal ankle, the fused ankle, and after total ankle replacement by the AGILITY, HINTEGRA, and S.T.A.R. prostheses. RESULTS: While in dorsiflexion/plantarflexion of the foot, ankle joint fusion increased the movement transfer to tibial rotation by a 2.4 factor and to eversion/inversion by a 18.5 factor, whereas, this movement transfer did not change for all prostheses conditions. The movement transfer between foot eversion and tibial rotation was found to decrease for all ankle prostheses, but more in the AGILITY and S.T.A.R. prosthesis than in the HINTEGRA. CONCLUSIONS: The three tested ankle joint prostheses changed the movement transferred within the ankle joint complex less than ankle fusion did, especially for dorsiflexion/plantarflexion movement of the foot. The closer the design was to the normal anatomy of the ankle, the closer the transfer of movement was shown to be replicated with respect to normal joint. It is suggested that success of total ankle arthroplasty depends on how successfully designs can mimic the movement transfer of the normal ankle, while dissipating the rotational forces and maintaining the stability of the joint.

Aged↗

Kinematic changes after fusion and total replacement of the ankle: part 3: Talar movement.

INTRODUCTION: The purpose of this study was to determine talar movement (e.g., talar rotation and talar shift during (dorsiflexion/plantarflexion) with respect to the tibia in the normal ankle, in the fused ankle, and in the replaced ankle by currently used prosthetic designs. METHODS: A 6-df device with an axial load of 200 N and a four-camera high-speed video system were used for the measurement of the range of motion in six fresh-frozen cadaveri leg specimens. While moving the foot through the whole range of motion for plantarflexion/dorsiflexion, segmental motion of the marked bones of the foot and shank were measured dynamically. Rotation and medial-lateral shift of the talus were then calculated with regard to flexion position of the foot. RESULTS: In the normal ankle, plantarflexion movement was coupled with talar inversion of 3.5 degrees, and dorsiflexion movement with talar eversion of 1.0 degree, in totally accounting for 4.5 degrees of talar rotation. While both the HINTEGRA and the S.T.A.R. prostheses did not show changes to the normal condition during the dorsiflexion/plantarflexion cycle (p < .05), talar rotation had a 60% decrease (p < .05) for the AGILITY prosthesis. In the normal ankle joint, a lateral talar shift of 1.4 mm was found to occur during dorsiflexion, and a lateral talar shift of 5.2 mm during plantarflexion. In both, the HINTEGRA and S.T.A.R. ankles, talar shift was converted into medial direction during dorsiflexion of the foot (difference to normal: p < .05), whereas talar shift in the lateral direction was found to occur during plantarflexion of the foot which was comparable to the normal ankle. The AGILITY ankle evidenced an 80% decrease of talar shift (p < .05) during the whole dorsiflexion/plantarflexion cycle. DISCUSSION: The two-component ankle (AGILITY) obviously tends to restrict tremendously talar motion within the ankle mortise, whereas the three-component ankles (HINTEGRA, S.T.A.R.) seem to allow talar range of motion comparable to that in the normal ankle. It is suggested that such a restriction of talar motion results in an increase of stress forces within and around the prosthesis, leading to polyethylene wear and potential loosening at the bone-implant interfaces. Therefore, a successful prosthetic design for the ankle should consist of three components that are shaped as anatomically as possible to provide a normal range of motion and to allow the full transmission of movement transfer between foot and shank and unconstrained movement of the talus within the ankle mortise.

Aged↗

Consequences of ankle joint fixation on FES cycling power output: a simulation study.

INTRODUCTION: During fixed-ankle FES cycling in paraplegics, in which the leg position is completely determined by the crank angle, mechanical power output is low. This low power output limits the cardiovascular load that could be realized during FES ergometer cycling, and limits possibilities for FES cycling as a means of locomotion. Stimulation of ankle musculature in a released-ankle setup might increase power output. However, releasing the ankle joint introduces a degree of freedom in the leg that has to be controlled, which imposes constraints on the stimulation pattern. METHODS: In this study, a forward dynamics modeling/simulation approach was used to assess the potential effect of releasing the ankle on the maximal mechanical power output. RESULTS: For the released-ankle setup, the optimal stimulation pattern was found to be less tightly related to muscle shortening/lengthening than for the fixed-ankle setup, which indicates the importance of the constraints introduced by releasing the ankle. As a result, the maximal power output for 45-RPM cycling in the released-ankle setup was found to be about 10% lower than with a fixed ankle, despite the additional muscle mass available for stimulation. Power output for the released-ankle setup can be improved by tuning the point of contact between the foot and pedal to the relative strength of the ankle plantar flexors. For the model used, power output was 14% higher than for the fixed-ankle setup when this point of contact was moved posteriorly by 0.075 m. CONCLUSION: Releasing the ankle joint and stimulating the triceps surae and tibialis anterior is expected to result in a modest increase in power output at best.

Acceleration↗

Clinical experiences with three different designs of ankle prostheses.

Until 1995, fusion was in our institution the only rational surgical option for a severe ankle arthrosis. Consistent reports about good mid- and long-term results with ankle replacement allowed us to change our minds. Ankle replacement became the gold standard and fusion was then almost totally banished. Because ankle arthrosis can be morphologically different from one patient to another, we soon believed that one single type of ankle prosthesis would not be the universal optimal solution for all patients. We therefore divided the ankle arthrosis into three groups. Each group shows the best solution from each of the ankle prostheses with which we had gained experience (Agility, STAR, and BP). The Agility prosthesis, which was indicated for ankles with extremely damaged geometry, did not restore sufficiently the ankle motion. Preoperatively stiff ankles remained stiff postoperatively. Additionally, significant residual pain was more likely to occur in those patients. These cases did not show significant advantages compared with ankle fusion, especially from a functional point of view. Fusion for these stiff ankles is therefore today our first treatment of choice. In our experience, the malleolar joints do not have to be replaced. Even a severe arthrosis at this level does not produce significant pain, provided that osteophytes have been removed and joint height has been restored by the implanted prosthesis. It is our strong belief that these malleolar joints are also less sensitive to pain, similar to the femoropatellar joint. For these reasons, a replacement of the malleolar joints and the resurfacing of the talar sides is not necessary. Leaving the talar sides untouched requires less bone resection and makes the implantation of the talar component easier. Although we obtained good results with the STAR prosthesis, we progressively abandoned it because of these reasons, and we preferred the BP prosthesis. The BP prosthesis works on the same biomechanic principle as the STAR prosthesis. Some features, however, like the untouched malleolar joints, the large exposition of the joint, the easier adjustments of its position, the possibility of enhancing the press fit, and the good short- and midterm results we obtained with it led us to the decision of using it as our only design for cases of nice and acceptable arthroses. Even if mostly good and excellent results have been achieved with all prostheses currently used, some results are still disappointing. Some ankles become stiff postoperatively and some remain diffusely painful; the explanations for these problems are often difficult to attain. This clearly shows that despite all the progress made over the last few years, there is still a lot to be learned about ankle arthroplasty.

Arthritis↗

Low-load eversion force sense, self-reported ankle instability, and frequency of giving way.

CONTEXT: Functional ankle instability has been attributed to proprioceptive loss. However, in previous studies of proprioception,authors have not investigated the ability to sense force at the ankle. Additionally, previous investigators have viewed functional ankle instability as either a present or absent condition,rather than a continuum. OBJECTIVE: To determine the relationship of ankle giving-way frequency and perceived ankle instability to ankle eversion force sense. DESIGN: Cohort design. SETTING: Sports medicine research laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty individuals (5 men,15 women) with a history of unilateral ankle instability. INTERVENTION(S): We tested subjects with 2 loads: 10% and 30% of maximal voluntary isometric contraction. MAIN OUTCOME MEASURE(S): We measured eversion force sense by calculating absolute, constant, and variable errors from a 3-trial force-matching procedure. Furthermore, subjects reported their frequency of giving way in units of times per day,week, or month, and these data were extrapolated to estimate annual giving-way frequency. Finally, subjects answers to 6 questions about ankle stability during typical daily or sports activities were summed to create a perceived ankle instability index. RESULTS: Significant relationships were found for only the 10% maximal voluntary isometric contraction. For absolute error,a positive relationship existed between the number of self reported episodes of giving way and eversion force sense for both ipsilateral (r .58) and contralateral (r .49) testing of the injured ankle. Constant error was correlated with giving way(r = -.56) for ipsilateral testing of the injured ankle. The ankle instability index was also positively correlated with eversion force sense absolute error (r .51) for ipsilateral testing only. CONCLUSIONS: Our results suggest that subjects with ankle instability had difficulty replicating eversion forces. Specifically,larger errors were related to both self-reported giving-way episodes and perceived ankle instability.

Journal Article↗

Radiographic indicators of ankle instability: changes with plantarflexion.

BACKGROUND: The effect of plantarflexion on radiographic indicators of instability was investigated in matched pairs of stable ankles and unstable ankle fractures with complete deltoid ligament tears to test the hypothesis that differences exist in indicators as a function of either stability or position. The purpose of this study was to determine whether plantarflexion increases radiographic indicators of ankle fracture instability. METHODS: Measurements from 34 patients scheduled for operative treatment of unstable ankle fractures were collected prospectively from normal, stable ankles and the injured, unstable ankles. Instability was defined as a positive fluoroscopic stress examination under anesthesia. Stability and instability and neutral position and plantarflexion were associated with eight radiographic indicators of which five were distances in millimeters and three were binomial (either stable or unstable). RESULTS: Measurements were larger in the unstable ankles than in the normal stable ankles. Plantarflexion was associated with increased distances in stable ankles, and a trend was seen in unstable ankles. Plantarflexion was associated with increased binomial indicators in unstable ankles but not in stable ankles. DISCUSSION: Joint positioning affected measurement of ankle stability: plantarflexion increased the sensitivity of radiographic indicators.

Ankle Injuries↗