scholarly journals The Role of Calcaneofibular Ligament (CFL) Injury in Ankle Instability

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0002
Author(s):  
Kenneth Hunt ◽  
Richard Fuld ◽  
Judas Kelley ◽  
Nicholas Anderson ◽  
Todd Baldini
Keyword(s):  
Contact Mechanics ◽  
Ankle Joint ◽  
Motion Capture ◽  
Contact Area ◽  
Subtalar Joint ◽  
Ankle Instability ◽  
Weight Bearing ◽  
Calcaneofibular Ligament ◽  
Tibiotalar Joint ◽  
Ankle Stability

Category: Ankle Introduction/Purpose: Acute inversion ankle sprains are among the most common musculoskeletal injuries. Higher grade sprains, which include anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) injury, can be particularly problematic and often require surgical repair. The implications of CFL injury on ankle instability are unclear. We aim to evaluate the impact of CFL injury on ankle stability and subtalar joint biomechanics. We hypothesized that CFL injury will result in decreased stiffness and torque, and alteration of ankle contact mechanics compared to the uninjured ankle in a cadaveric model. Methods: Twenty matched cadaveric ankles dissected of skin and subcutaneous tissue were mounted to an Instron with 20° of ankle plantar flexion and 15° of internal rotation. Intact specimens were axially loaded to body weight, then underwent inversion stress along the anatomic axis of the ankle from 0 to 20° (simulating inversion injury) for three cycles. ATFL and CFL were sequentially sectioned, and inversion testing repeated for each condition. Stiffness and change in torque were recorded using an Instron, and pressure and contact area were recorded using a calibrated Tekscan sensor system. Inversion angle of the talus and calcaneus relative to the ankle mortise were recorded using a three-dimensional motion capture system. Paired t tests were performed for inter and intra-group comparisons. Results: Stiffness and torque did not significantly decrease after sectioning of the ATFL, but did decreased significantly after sectioning of CFL. Peak pressures in the tibiotalar joint decreased significantly following CFL release compared to both the uninjured ankle and ATFL-only release. Mean contact area significantly increased following CFL release compared to both the uninjured ankle and ATFL release. There was a concentration of force in the anteromedial ankle joint during weight-bearing inversion. However, the center-of-force shifts 1.22 mm posteromedial after CFL release relative to an intact ankle. Motion capture showed a significant and sequential increase in inversion angle of both the calcaneus and talus, after release of each ligament. There was significantly more inversion in the subtalar joint than the tibiotalar joint with weight-bearing inversion. Conclusion: There is significantly lower stiffness and torque with weight-bearing inversion of the ankle joint complex following injury to both ATFL and CFL, and sequentially greater inversion of the talus and calcaneus with progressive ligament injury. This corresponds to a significant shift in the center of force in the tibiotalar joint. CFL contributes considerably to lateral ankle stability, and sprains that include CFL injury result in substantial alteration of contact mechanics at the ankle and subtalar joints. Repair of CFL may be beneficial during lateral ligament reconstruction, potentially mitigating long-term consequences (e.g., articular damage) of a loose or incompetent CFL.

The Role of Calcaneofibular Ligament Injury in Ankle Instability: Implications for Surgical Management

2018 ◽  
Vol 47 (2) ◽  
pp. 431-437 ◽  
Author(s):  
Kenneth J. Hunt ◽  
Helder Pereira ◽  
Judas Kelley ◽  
Nicholas Anderson ◽  
Richard Fuld ◽  
...  
Keyword(s):  
Contact Mechanics ◽  
Ankle Joint ◽  
Contact Area ◽  
Ankle Instability ◽  
Peak Torque ◽  
Ligament Injury ◽  
Lateral Ligament ◽  
Anterior Talofibular Ligament ◽  
Ankle Sprains ◽  
Calcaneofibular Ligament

Background: Acute inversion ankle sprains are among the most common musculoskeletal injuries. Higher grade sprains, including anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) injury, can be particularly challenging. The precise effect of CFL injury on ankle instability is unclear. Hypothesis: CFL injury will result in decreased stiffness, decreased peak torque, and increased talar and calcaneal motion and will alter ankle contact mechanics when compared with the uninjured ankle and the ATFL-only injured ankle in a cadaveric model. Study Design: Descriptive laboratory study. Methods: Ten matched pairs of cadaver specimens with a pressure sensor in the ankle joint and motion trackers on the fibula, talus, and calcaneus were mounted on a material testing system with 20° of ankle plantarflexion and 15° of internal rotation. Intact specimens were axially loaded to body weight and then underwent inversion along the anatomic axis of the ankle from 0° to 20°. The ATFL and CFL were sequentially sectioned and underwent inversion testing for each condition. Linear mixed models were used to determine significance for stiffness, peak torque, peak pressure, contact area, and inversion angles of the talus and calcaneus relative to the fibula across the 3 conditions. Results: Stiffness and peak torque did not significantly decrease after sectioning of the ATFL but decreased significantly after sectioning of the CFL. Peak pressures in the tibiotalar joint decreased and mean contact area increased significantly after CFL release. Significantly more inversion of the talus and calcaneus as well as calcaneal medial displacement was seen with weightbearing inversion after sectioning of the CFL. Conclusion: The CFL contributes considerably to lateral ankle instability. Higher grade sprains that include CFL injury result in significant decreases in rotation stiffness and peak torque, substantial alteration of contact mechanics at the ankle joint, increased inversion of the talus and calcaneus, and increased medial displacement of the calcaneus. Clinical Relevance: Repair of an injured CFL should be considered during lateral ligament reconstruction, and there may be a role for early repair in high-grade injuries to avoid intermediate and long-term consequences of a loose or incompetent CFL.

scholarly journals Ankle and Subtalar Joint Kinematics following Lateral Ligament Repair- Implications for Early Surgical Treatment

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0002
Author(s):  
Kenneth Hunt ◽  
Nicholas Anderson ◽  
Judas Kelley ◽  
Richard Fuld ◽  
Todd Baldini
Keyword(s):  
Motion Capture ◽  
Contact Area ◽  
Subtalar Joint ◽  
Peak Pressure ◽  
Weight Bearing ◽  
Joint Kinematics ◽  
Ligament Repair ◽  
Tibiotalar Joint ◽  
Ligament Healing ◽  
The Impact

Category: Ankle Introduction/Purpose: The current trend for chronic lateral ankle instability treatment is direct repair of the ATFL and/or CFL by open or arthroscopic-assisted technique. There is recent evidence suggesting improved success with acute ligament repair following high grade ankle sprains as well as on the impact of CFL injury on ankle and subtalar biomechanics. However, the impact of acute repair on ankle and subtalar joint kinematics and biomechanics is not well understood. The purpose of this study was to determine the impact of repairing the ATFL alone compared to repairing both the ATFL and CFL, on restoration of ankle and subtalar joint kinematics. Methods: Ten matched pairs of fresh frozen human cadaveric ankles were dissected to expose intact ATFL and CFL. Ankles were mounted to an Instron at 20° plantar flexion and 15° of internal rotation. Each ankle was loaded to body weight and then inverted from 0 to 20° for three cycles; Peak pressure and contact area were recorded in the ankle joint using a calibrated Tekscan sensor system, and linear and rotational displacement of the talus and calcaneus relative to the ankle mortise was recorded using a three-dimensional motion capture system. Ankles then underwent sequential sectioning of ATFL and CFL and were randomly assigned to ATFL-only repair using two arthroscopic Broström all-soft anchors, or combined ATFL and CFL repair. Testing was repeated after repair. Results: Motion capture showed a significant increase in inversion angle of both the calcaneus and talus after release of each ligament. There was significantly more inversion in the subtalar joint than the tibiotalar joint with weight-bearing inversion. There was a significant increased medial shift of the calcaneus after CFL release. Neither ATFL alone nor combined ATFL/CFL repairs restored normal ankle joint inversion. Isolated ATFL repair restored inversion of subtalar joint nearing the intact state. We found no significant difference in peak pressure or contact area in the tibiotalar joint between the intact ankle and ATFL or combined repair. However, there was a 26% decrease in peak pressure following ATFL repair, and only an 11% decrease in peak pressure following ATFL/CFL repair compared to the uninjured ankle. Conclusion: The addition of CFL repair does not appear to provide significant improvement compared to ATFL repair alone in the immediate repair setting. Neither group demonstrated restoration of normal talus inversion with weight-bearing inversion testing, suggesting that acute repair, without a period of ligament healing, is not sufficient to resist a weight-bearing inversion moment. While the CFL plays an important role in normal ankle mechanics, this data supports the necessity for a protection period to allow sufficient ligament-healing before weight-bearing inversion stresses are applied following surgical repair.

Effect of Post-traumatic Tibiotalar Osteoarthritis on Kinematics of the Ankle Joint Complex

2009 ◽  
Vol 30 (8) ◽  
pp. 734-740 ◽  
Author(s):  
Michal Kozanek ◽  
Harry E. Rubash ◽  
Guoan Li ◽  
Richard J. de Asla
Keyword(s):  
Ankle Joint ◽  
Subtalar Joint ◽  
Imaging Techniques ◽  
Weight Bearing ◽  
Surgical Techniques ◽  
Heel Strike ◽  
Control Group ◽  
Tibiotalar Joint ◽  
Results Of Treatment ◽  
Post Traumatic

Background: Knowledge of joint kinematics in the healthy and diseased joint may be useful if surgical techniques and joint replacement designs are to be improved. To date, little is known about the kinematics of the arthritic tibiotalar joint and its effect on the kinematics of the subtalar joint. Materials and Methods: Kinematics of the ankle joint complex (AJC) were measured in six patients with unilateral post-traumatic tibiotalar osteoarthritis in simulated heel strike, midstance and toe off weight bearing positions using magnetic resonance and dual fluoroscopic imaging techniques. The kinematic data obtained was compared to a normal cohort from a previous study. Results: From heel strike to midstance, the arthritic tibiotalar joint demonstrated 2.2 ± 5.0 degrees of dorsiflexion while in the healthy controls the tibiotalar joint plantarflexed 9.1 ± 5.3 degrees ( p < 0.01). From midstance to toe off, the subtalar joint in the arthritic group dorsiflexed 3.3 ± 4.1 degrees whereas in the control group the subtalar joint plantarflexed 8.5 ± 2.9 degrees ( p < 0.01). The subtalar joint in the arthritic group rotated externally 1.2 ± 1.0 degrees and everted 3.3 ± 6.1 degrees from midstance to toe off while in the control group 12.3 ± 8.3 degrees of internal rotation and 10.7 ± 3.8 degrees eversion ( p < 0.01 and p < 0.01, respectively) was measured. Conclusion: The current study suggests that during the stance phase of gait, subtalar joint motion in the sagittal, coronal, and transverse rotational planes tends to occur in an opposite direction in subjects with tibiotalar osteoarthritis when compared to normal ankle controls. This effectively represents a breakdown in the normal motion coupling seen in healthy ankle joints. Clinical Relevance: Knowledge of ankle kinematics of arthritic joints may be helpful when designing prostheses or in assessing the results of treatment interventions.

The Role of Subtalar Motion and Ankle Contact Pressure Changes from Angular Deformities of the Tibia

Foot & Ankle ◽  
1987 ◽  
Vol 7 (5) ◽  
pp. 290-299 ◽  
Author(s):  
Arthur J. Ting ◽  
Richard R. Tarr ◽  
Augusto Sarmiento ◽  
Ken Wagner ◽  
Charles Resnick
Keyword(s):  
Contact Pressure ◽  
Ankle Joint ◽  
Contact Area ◽  
Subtalar Joint ◽  
Angular Deformity ◽  
Talar Dome ◽  
Posterior Portion ◽  
Fracture Angle ◽  
Tibiotalar Joint ◽  
Angular Deformities

It is a well known entity that fractures of the tibia heal with some component of angular deformity. Ankle and subtalar joints may compensate for small degrees of angular deformities, but the exact amount of malunion that can be accepted without development of late sequalae has yet to be determined. Two recent studies from this institution have concluded that (1) contact changes at the tibiotalar joint tend to be greater with distal third tibial fracture deformities compared to proximal and middle with the ankle in neutral, 5° dorsiflexion, and 20° of plantar flexion. (2) Anterior and posterior bow deformities produced a greater change in contact area of the tibiotalar joint than with valgus or varus deformities. This phenomena may be possibly explained by the subtalar motion in the horizontal plane which averages 23°. Thus, it was the primary purpose of this paper to determine the exact role, if any, in subtalar motion on tibiotalar contact in angular deformities of the tibia. To achieve this objective the subtalar joint was transfixed thereby eliminating its perceived compensatory movement. Six cadaveric lower extremities were disarticulated at the knee joint and stripped of soft tissue preserving capsular and ligamentous structures. A custom universal joint was used to create various angulatory deformities at proximal, middle, and distal third levels of the tibia. Contact pressure across the tibiotalar joint was recorded using pressure-sensitive film and analyzed quantitatively in terms of contact area as well as pattern. The same combinations of angular deformities were then run with the subtalar joint transfixed in neutral. The results indicated that as in the two previous studies distal third deformities resulted in the greatest amount of change in ankle contact pressure area. The data also demonstrated that when subtalar motion was restricted ankle contact area decreased significantly in all planes of angulatory deformity. (1) The data collected agree with the results of two previous studies which showed that there was a decreased in total ankle contact area consistently at the distal third level with posterior angulatory deformities of the tibia. (2) By defining the resultant fracture angle and the foot axis angle a geometric explanation can be given to demonstrate a distal level fracture of the tibia has a greater effect on the ankle articulation than one more proximal. (3) The ankle joint has been shown by others to be less congruent as it moves away from its neutral position. This was found to affect and therefore cause a decrease in ankle contact area with tibial angulatory deformities. (4) The ankle joint is more adapted for weightbearing in neutral and in dorsiflexion. The anterior portion of the talar dome is probably more adapted to weightbearing than the posterior portion. This accounted for greater changes in ankle contact area during plantarflexion than in dorsiflexion. (5) The subtalar joint was found to play a very significant role in maintaining the talus in its normal relationship to the tibia. Restriction of the subtalar joint affected all deformities of the tibia as the resultant fracture angle increased. (6) The data supports Inman's concept of the subtalar joint acting as a torque transmitter and compensates for tibial varus and valgus deformities. (7) Subtalar joint restriction affected varus deformities more than valgus deformities probably due to shifting of the talar dome therefore significantly altering its normal biomechanics.

scholarly journals Effect of Distal Tibial Varus and Valgus Deformity on Tibiotalar Joint Contact

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0025
Author(s):  
Zhao Hong-Mou
Keyword(s):  
Contact Pressure ◽  
Ankle Joint ◽  
Contact Area ◽  
Peak Pressure ◽  
Tibiotalar Joint ◽  
Force Center ◽  
Fibular Osteotomy ◽  
Group I ◽  
Joint Contact ◽  
Group A

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: To study the effect of different degrees of distal tibial varus and valgus deformities on the tibiotalar joint contact, and to understand the role of fibular osteotomy. Methods: Eight cadaveric lower legs were used for biomechanical study. Nine conditions were included: normal ankle joint (group A), 10° varus (group B), 5° varus (group C), 5° valgus (group D), 10° valgus (group E) with fibular preserved, and 10° varus (group F), 5° varus (group G), 5° valgus (group H), and 10° valgus (group I) after fibular osteotomy. The joint contact area, contact pressure, and peak pressure were tested; and the translation of contact force center was observed. Results: The joint contact area, contact pressure, and peak pressure had no significant difference between group A and groups B to E (P>0.05). After fibular osteotomy, the contact area decreased significantly in groups F and I when compared with group A (P<0.05); the contact pressure increased significantly in groups F, H, and I when compared with group A (P<0.05); the peak pressure increased significantly in groups F and I when compared with group A (P<0.05). There were two main anterior-lateral and anterior-medial contact centers in normal tibiotalar joint, respectively; and the force center was in anterior-lateral part, just near the center of tibiotalar joint. While the fibula was preserved, the force center transferred laterally with increased varus angles; and the force center transferred medially with increased valgus angles. However, the force center transferred oppositely to the medial part with increased varus angles, and laterally with increased valgus angles after fibular osteotomy. Conclusion: Fibular osteotomy facilitates the tibiotalar contact pressure translation, and is helpful for ankle joint realignment in suitable cases.

Contact patterns in the ankle joint after lateral ligamentous injury during internal rotation: A computational study

2020 ◽  
Vol 235 (1) ◽  
pp. 82-88
Author(s):  
G Marta ◽  
C Quental ◽  
J Folgado ◽  
F Guerra-Pinto
Keyword(s):  
Finite Element ◽  
Contact Mechanics ◽  
Internal Rotation ◽  
Ankle Joint ◽  
Ankle Instability ◽  
Computational Study ◽  
Rotational Instability ◽  
Anterior Talofibular Ligament ◽  
Maximum Contact ◽  
Contact Pressures

Lateral ankle instability, resulting from the inability of ankle ligaments to heal after injury, is believed to cause a change in the articular contact mechanics that may promote cartilage degeneration. Considering that lateral ligaments’ insufficiency has been related to rotational instability of the talus, and that few studies have addressed the contact mechanics under this condition, the aim of this work was to evaluate if a purely rotational ankle instability could cause non-physiological changes in contact pressures in the ankle joint cartilages using the finite element method. A finite element model of a healthy ankle joint, including bones, cartilages and nine ligaments, was developed. Pure internal talus rotations of 3.67°, 9.6° and 13.43°, measured experimentally for three ligamentous configurations, were applied. The ligamentous configurations consisted in a healthy condition, an injured condition in which the anterior talofibular ligament was cut, and an injured condition in which the anterior talofibular and calcaneofibular ligaments were cut. For all simulations, the contact areas and maximum contact pressures were evaluated for each cartilage. The results showed not only an increase of the maximum contact pressures in the ankle cartilages, but also novel contact regions at the anteromedial and posterolateral sections of the talar cartilage with increasing internal rotation. The anteromedial and posterolateral contact regions observed due to pathological internal rotations of the talus are a computational evidence that supports the link between a pure rotational instability and the pattern of pathological cartilaginous load seen in patients with long-term lateral chronic ankle instability.

Effect of Acupuncture as Seen in Stress Radiography of the Ankle

1995 ◽  
Vol 13 (1) ◽  
pp. 2-4 ◽  
Author(s):  
Saila Eksymä-Sillman ◽  
Ilkka Suramo ◽  
Seppo YT Junnila ◽  
Valtteri Myllylä
Keyword(s):  
Ankle Joint ◽  
Ankle Instability ◽  
False Negative ◽  
Muscle Spasm ◽  
Stress Radiography ◽  
Negative Finding ◽  
Tibiotalar Joint ◽  
Asymptomatic Volunteers ◽  
False Negative Finding

When studying ankle instability by stress radiography, pain and muscle spasm can prevent maximal widening of the tibiotalar ankle joint and cause a false negative finding. We examined the effect of acupuncture on widening of the tibiotalar joint during stress radiography in a series of 12 asymptomatic volunteers and 12 patients. The width of the tibiotalar joint increased in 66% of the volunteers. The diagnosis changed for two patients and became more confident for four others (50%).

scholarly journals Lateral talocalcaneal ligament substitution for calcaneofibular ligament difficient chronic ankle lateral instability

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0002
Author(s):  
Chen Jiao
Keyword(s):  
Tilt Angle ◽  
Subtalar Joint ◽  
Ankle Instability ◽  
Stress Test ◽  
Lateral Ligament ◽  
Lateral Instability ◽  
Calcaneofibular Ligament ◽  
Anterior Translation ◽  
Negative Results ◽  
Talar Tilt

Category: Ankle, Hindfoot, Sports, Trauma Introduction/Purpose: Introduction: Treatment of chronic ankle lateral instability associated with defective calcaneofibular ligament via tendon reconstruction or artificial grafts has several disadvantages. The method of substitution with lateral talocalcaneal ligament has never been reported. Purpose: To investigate the role of lateral talocalcaneal ligament substitution for the treatment of chronic ankle lateral instability associated with defective calcaneofibular ligament. Methods: Repair of ankle lateral ligament was performed on 32 patients with chronic ankle instability. The mean age was 26.4±8.7 years. The calcaneofibular ligament was absent in all the patients and was confirmed surgically. The calcaneofibular ligament was repaired via transfer of talar insertion of the lateral talocalcaneal ligament. Patients were followed up for an average of 22.3±4.0 months. AOFAS, Mazur and Tegner scores, objective examinations (anterior drawer test and varus stress test) and re-injury were assessed before and after the operation. The anterior translation distance of the talus and the talar tilt angle were also measured. Results: In all the patients, postoperative AOFAS, Mazur and Tegner scores were significantly improved. Postoperative evaluation (drawer test and lateral stress test) yielded negative results. The anterior translation distance was reduced from 4.9±1.0 mm to 2.0±0.8 mm. The talar tilt angle was reduced from 12.7º±2.5º to 5.0º±1.4º. The average satisfaction score was 7.4. No subjective instability or re-injury, subtalar joint (tarsal sinus) pain or/and instability occurred. Conclusion: Lateral talocalcaneal ligament substitution was effective against chronic ankle lateral instability associated with the absence of calcaneofibular ligament, without any significant effect on subtalar joint clinically.

Effect of Complete Syndesmotic Disruption and Deltoid Injuries and Different Reduction Methods on Ankle Joint Contact Mechanics

2017 ◽  
Vol 38 (6) ◽  
pp. 694-700 ◽  
Author(s):  
Jeremy LaMothe ◽  
Josh R. Baxter ◽  
Susannah Gilbert ◽  
Conor I. Murphy ◽  
Sydney C. Karnovsky ◽  
...  
Keyword(s):  
Contact Mechanics ◽  
Ankle Joint ◽  
Contact Area ◽  
Repeated Measures ◽  
Screw Fixation ◽  
Biomechanical Model ◽  
Posttraumatic Arthritis ◽  
Syndesmotic Injury ◽  
Suture Button ◽  
Joint Contact

Background: Syndesmotic injuries can be associated with poor patient outcomes and posttraumatic ankle arthritis, particularly in the case of malreduction. However, ankle joint contact mechanics following a syndesmotic injury and reduction remains poorly understood. The purpose of this study was to characterize the effects of a syndesmotic injury and reduction techniques on ankle joint contact mechanics in a biomechanical model. Methods: Ten cadaveric whole lower leg specimens with undisturbed proximal tibiofibular joints were prepared and tested in this study. Contact area, contact force, and peak contact pressure were measured in the ankle joint during simulated standing in the intact, injured, and 3 reduction conditions: screw fixation with a clamp, screw fixation without a clamp (thumb technique), and a suture-button construct. Differences in these ankle contact parameters were detected between conditions using repeated-measures analysis of variance. Results: Syndesmotic disruption decreased tibial plafond contact area and force. Syndesmotic reduction did not restore ankle loading mechanics to values measured in the intact condition. Reduction with the thumb technique was able to restore significantly more joint contact area and force than the reduction clamp or suture-button construct. Conclusion: Syndesmotic disruption decreased joint contact area and force. Although the thumb technique performed significantly better than the reduction clamp and suture-button construct, syndesmotic reduction did not restore contact mechanics to intact levels. Clinical Relevance: Decreased contact area and force with disruption imply that other structures are likely receiving more loads (eg, medial and lateral gutters), which may have clinical implications such as the development of posttraumatic arthritis.

scholarly journals Effect of Achilles tendon lengthening on ankle and subtalar joint orientation and load distribution utilizing a novel cadaveric model to simulate weight bearing

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0021
Author(s):  
Naven Duggal ◽  
Patrick Williamson ◽  
Stephen Okajima ◽  
Peter Biggane ◽  
Michael Nasr ◽  
...  
Keyword(s):  
Achilles Tendon ◽  
Contact Area ◽  
Subtalar Joint ◽  
Peak Pressure ◽  
Weight Bearing ◽  
Joint Orientation ◽  
Ankle Arthroplasty ◽  
Tendon Lengthening ◽  
Mean Pressure ◽  
Achilles Tendon Lengthening

Category: Basic Sciences/Biologics Introduction/Purpose: Ankle arthroplasties are increasingly performed to address ankle arthritis. Patients with long standing ankle arthritis often present with an associated achilles tendon contracture. An open or percutaneous lengthening of the Achilles is commonly performed at the same time as the ankle arthroplasty to improve range of motion. Current ankle arthroplasty implants include mobile bearing and fixed bearing systems. Lengthening the achilles tendon improves dorsiflexion, however the effect of the lengthening on the ankle and subtalar joint is not well documented in the literature. Using a novel system to simulate weight bearing in a cadaveric model, we evaluated achilles tendon lengthening and its effect on ankle and subtalar joint orientation and load distribution. This may have potential implications to polyethylene implant longevity in total ankle arthroplasties. Methods: Five fresh frozen lower limb cadaveric specimens without known skeletal condition were used. The femoral head was potted with PMMA and TekScan pressure sensors were inserted into the ankle and subtalar joint. The specimens were placed on a custom jig, which allowed for load cell modulated loading of the leg; 75 lb load (half body weight)(4) was applied at the femoral head while the foot was supported against a fixed plate keeping the ankle in neutral position. Mean pressure (MP), peak pressure (PP), contact area (CA), and center of force (COF) were measured in both joints under two conditions; baseline (BASE), and following Achilles tendon release (TENDON) to simulate lengthening. Each condition was tested three times per specimen; the results were averaged per specimen and used for final analysis. Displacement of COF was calculated relative to its location at baseline. Results: The Mean Pressure (MP), Peak Pressure (PP) and Contact Area (CA) did not show a statistical difference in the ankle and subtalar joints between baseline (BASE) and TENDON (Achilles tendon release) conditions. (Table 1). Further, the displacement of the COF from the BASE to TENDON was 0.5 mm. In our model, the contracture of the muscle was not fully simulated. Further hindfoot kinetic studies with active achilles contracture may demonstrate a difference in contact forces in the ankle and subtalar joint as compared to normal. Conclusion: Ankle arthroplasty is becoming an effective treatment option for ankle joint arthritis. Our novel study demonstrates that Achilles tendon lengthening did not change the mean pressure, peak pressure, contact area center of force in the ankle and subtalar joint. This model provides validation for further studies evaluating tendon release and contact pressure changes in a cadaver with an implanted fixed bearing versus mobile bearing total ankle prosthesis. Difference in polyethylene wear may effect the longevity of ankle replacements. This study will provide clinicians additional information when evaluating the benefit/risks associated with lengthening the Achilles tendon for ankle arthroplasty patients.

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