Ankle morphometry based on computerized tomography

Category: Ankle Introduction/Purpose: Understanding the morphometry of the ankle joint is crucial to improve total ankle replacement (TAR). Despite improvements of the implant material TAR did not reach comparable success rates to total hip or knee arthroplasty. Recent studies queried whether current designs match with the articular geometry. The present study was performed to evaluate the ankle morphometry and thereby gain information about the joint axis. Methods: We analyzed 96 high-resolution CT-scans of complete caucasian cadaver legs. Using the software Mimics and 3-Matic (Materialize) 22 anatomic parameters of the talocrural joint were assessed, including the length, width and surface area of the tibial and talar bearing areas. Additionally the radii of the bearing areas, the medial distal tibial angle and the height of the talar dome were determined. Therefore we analyzed defined sagittal, axial and frontal planes. Results: The radius of the central trochlea tali was 44.6 ± 4.1 mm (mean ± SD). The central trochlea tali arc length was 40.8 ± 3.0 mm and its width was 27.4 ± 2.5 mm. Additionally we determined 47.0 ± 4.4 mm for the tibial sagittal radius, 27.6 ± 3.0 mm for the tibial arc length and 27.4 ± 2.5 mm for the central tibial width. Conclusion: The present study describes the three-dimensional morphometry of the caucasian ankle joint. Our results might be considered for the development of total ankle replacements.

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Talar Dome Investigation and Talocrural Joint Axis Analysis Based on Three-Dimensional (3D) Models: Implications for Prosthetic Design

BioMed Research International ◽

10.1155/2019/8634159 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10

Author(s):

Da-Hang Zhao ◽

Di-Chao Huang ◽

Gong-Hao Zhang ◽

Yun-Ping Fan ◽

Jian Yu ◽

...

Keyword(s):

Inclination Angle ◽

Three Dimensional ◽

Ct Scanning ◽

Implant Design ◽

Lateral Ligament ◽

Neutral Position ◽

Talar Dome ◽

Talocrural Joint ◽

Joint Axis ◽

The Mean

Ankle joint kinematics is mainly stabilized by the morphology of the talar dome and the articular surface of tibiofibular mortise as well as the medial and lateral ligament complexes. Because of this the bicondylar geometry of talus dome is believed to be crucial for ankle implant design. However, little data exist describing the precise anatomy of the talar dome and the talocrural joint axis. The aim of this study is to document the anatomy of the talar dome and the axis of the talocrural joint using three-dimensional (3D) computed tomographic (CT) modeling. Seventy-one participants enrolled for CT scanning and 3D talar model reconstruction. All the ankles were held in a neutral position during the CT scanning. Six points on the lateral and medial crest of the talar dome were defined. The coordinate of the six points; radii of lateral-anterior (R-LA), lateral-posterior (R-LP), medial-anterior (R-MA), and medial-posterior (R-MP) sections; and inclination angle of the talar dome were measured, and the inclination and deviation angles of the talocrural joint axis were determined. The mean values of R-LA, R-LP, R-MA, and R-MP were 19.23 ± 2.47 mm, 18.76 ± 2.90 mm, 17.02 ± 3.49 mm, and 22.75 ± 3.04 mm. The mean inclination angle of the talar dome was 9.86 ± 3.30 degrees. Gender variation was found in this parameter. The mean inclination and deviation angles were 8.60 ± 0.07 and 0.76 ± 0.69 degrees for the dorsiflexion axis and −7.34 ± 0.07 and 0.09 ± 0.18 degrees for the plantarflexion axis. Bilateral asymmetries between the medial and lateral crest of the talar dome were found, which resulted in different dorsiflexion and plantarflexion axes of the talocrural joint. Currently, no ankle implants replicate this talar anatomy, and these findings should be considered in future implant designs.

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Three-dimensional analysis of the talocrural joint axis: Relation to the talar articular surface

Foot and Ankle Surgery ◽

10.1016/j.fas.2017.07.455 ◽

2017 ◽

Vol 23 ◽

pp. 120-121

Author(s):

L. Claassen ◽

P. Luedtke ◽

D. Yao ◽

S. Ettinger ◽

K. Daniilidis ◽

...

Keyword(s):

Dimensional Analysis ◽

Articular Surface ◽

Three Dimensional ◽

Talocrural Joint ◽

Joint Axis

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Changes in the Plantarflexion Moment Arm of the Achilles Tendon Following Total Ankle Arthroplasty

Foot & Ankle Orthopaedics ◽

10.1177/2473011420s00480 ◽

2020 ◽

Vol 5 (4) ◽

pp. 2473011420S0048

Author(s):

Francesca E. Wade ◽

Gregory Lewis ◽

Andrea H. Horne ◽

Lauren Hickox ◽

Michael C. Aynardi ◽

...

Keyword(s):

Achilles Tendon ◽

Ankle Joint ◽

Sagittal Plane ◽

Total Ankle Arthroplasty ◽

Moment Arm ◽

Talar Dome ◽

Ankle Arthroplasty ◽

Joint Structure ◽

Joint Axis ◽

Mean Differences

Category: Ankle; Ankle Arthritis Introduction/Purpose: Deficits in ankle joint kinetics following total ankle arthroplasty (TAA) may be attributed to a reduction in the force-generating capacity of ankle joint muscles, but it is also important to consider the alterations to joint structure that may accompany this procedure. One key parameter indicative of joint structure with the potential to be influenced by TAA is the plantarflexion moment arm of the Achilles tendon (ATma). ATma is an indicator of the potential for the tendon force to produce plantarflexion moment that is determined by the three-dimensional line of action of the tendon relative to the ankle joint axis. The purpose of this study was to assess pre-to-post TAA changes in ATma; we hypothesized that pre- and post-TAA moment arms would not be different. Methods: We tested 10 TAA patients (age at surgery: 62.86 +- 9.72 y; height: 1.72 +- 0.08 m; body mass: 97.81 +- 20.89 kg) at pre-operative (˜ 1 mo pre) and post-operative (˜6 mo post) visits. All procedures involving testing of human subjects were approved by the Penn State Hershey Medical Center Institutional Review Board. ATma were measured using a method that combined ultrasound imaging of the tendon with 3D motion tracking of both the ultrasound probe and the ankle joint. The tendon and joint axis were located during trials in which the patients were seated with the knee extended while the ankle joint was voluntarily rotated in the sagittal plane. We also examined sagittal-plane weightbearing radiographs (pre- and post-op) to determine the AP distance from the center of the talar dome to the posterior margin of the calcaneus. Pre- and post-op ATma were compared using a paired t-test and regression. Results: No significant mean differences were found between post-op ATma and pre-op ATma (p = 0.360). Despite this, some patients were found to have large differences between pre- and postoperative ATma. For example, participants 1, 3, and 8 exhibited changes of -54.22%, +64.14% and +123.98% (pre-to-post) respectively (Figure 1). A moderate correlation between pre- and post-op ATma was found (r2 = 0.461, p = 0.031), indicating that only 46.1% of the variance in post-op ATma was explained by pre-op ATma (Figure 1). The normalized AP distance measured from the radiographs did not significantly change on average pre- to post-TAA (p = 0.561), and we found the change in this distance to correlate with the change in ATma (r2 = 0.370, p = 0.062). Conclusion: This is the first investigation of whether TAA alters ATma. Our results supported our hypothesis that pre-operative ATma predicts post-operative ATma. However, our hypothesis is supported only when the mean differences are considered, as there were sizeable differences for individuals. Despite a non-significant average change in ATma following TAA, at the individual level substantial changes in ATma were observed in seven of the 10 patients. Change in ATma was only partly explained by change in the AP position of the talar dome. Change in ATma has potential consequences for function in terms of ankle plantarflexor strength and walking velocity.

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Three-dimensional Analysis of the Talocrural Joint Axis

Foot & Ankle Orthopaedics ◽

10.1177/2473011417s000331 ◽

2017 ◽

Vol 2 (3) ◽

pp. 2473011417S0003

Author(s):

Christian Plaass ◽

Leif Claassen ◽

Christina Stukenborg-Colsman ◽

Daiwei Yao ◽

Kiriakos Daniilidis ◽

...

Keyword(s):

Sagittal Plane ◽

Articular Surface ◽

Three Dimensional ◽

Frontal Plane ◽

High Standard ◽

Patient Specific ◽

Rotational Axis ◽

Talocrural Joint ◽

Joint Axis

Category: Ankle Introduction/Purpose: The total ankle replacement (TAR) is increasingly used in cases of severe ankle arthritis. Although the knowledge about joint kinematics is crucial for designing and positioning of TAR there is no consensus about the talocrural joint axis. The aim of the present study was the determination of the kinematic rotational axis of the talocrural joint as an orientation for prosthesis positioning. Methods: We analyzed 96 CT-scans of full cadaver caucasien legs. With the software Mimic, 3-Matic (both Materialize) and GOM inspect we generated three-dimensional reconstruction models of the talus and a best fitting cone orientated to the talar articular surface. The kinematic rotational axis was defined to be the axis of this cone. Results: The determination of the kinematic rotational axis showed a high inter- and intrarater reliability. The kinematic rotational axis of the talocrural joint is orientated from lateral-distal to medial-proximal (84.9° ± 8.5 compared to mechanical tibial axis in frontal plane), from dorsal-proximal to anterior-distal (93.1° ± 42.3 compared to mechanical tibial axis in sagittal plane) and from dorsal-lateral to anterior-medial (169.0° ± 6.7 compared to mechanical tibial axis in axial plane). A high standard deviation especially in the sagittal plane was noteworthy. Conclusion: With the present study we present a new reproducable single-axis model of the talocrural joint. Our data showed relevant interindividual variations. The consideration of these variations might support the development of patient-specific TAR implantation techniques.

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Ankle Osteoarthritis – Arthroplasty or Arthrodesis?

Ortopedia Traumatologia Rehabilitacja ◽

10.5604/01.3001.0012.7282 ◽

2018 ◽

Vol 20 (5) ◽

pp. 361-371

Author(s):

Jakub Wąsik ◽

Tomasz Stołtny ◽

Maria Leksowska-Pawliczek ◽

Jarosław Pasek ◽

Maciej Szcześniak ◽

...

Keyword(s):

Surgical Treatment ◽

Ankle Joint ◽

Irreversible Loss ◽

Ankle Osteoarthritis ◽

Talocrural Joint ◽

Ankle Arthroplasty ◽

Joint Axis ◽

Surgical Methods ◽

History Of ◽

Neurological Conditions

Osteoarthritis of the talocrural joint accounts for only 4% of cases of degenerative disease of the musculoskeletal system. Unlike other joints, idiopathic OA of the ankle joint is identified in only 7% of patients. Until the end of the 1960’s, arthrodesis was the treatment of choice in advanced OA of ankle joint. Absolute indications for arthrodesis include irreversible loss of joint anatomy, neurological conditions, advanced osteoporosis and chronic inflammation. Currently, the surgical treatment of ankle joint OA relies on third-generation endoprostheses of the ankle. Arthroplasty is indicated in patients under 60 years of age with no history of non-orthopaedic co-morbidities, engaging in little physical activity, with an intact joint axis and satisfactory mobility and non-smoking. This article analyzes the available literature on the results of surgical treatment in patients with osteoarthritis of the talocrural joint treated with arthrodesis or arthroplasty, taking into consideration the strict indications for each of these surgical methods.

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Three-dimensional analysis of the talocrural joint axis: Relation to the talar articular surface

Foot and Ankle Surgery ◽

10.1016/j.fas.2016.05.111 ◽

2016 ◽

Vol 22 (2) ◽

pp. 48

Author(s):

L. Claassen ◽

P. Ludtke ◽

S. Ettinger ◽

Magdalena Müller-Gerbl ◽

Andrej Nowakowski ◽

...

Keyword(s):

Dimensional Analysis ◽

Articular Surface ◽

Three Dimensional ◽

Talocrural Joint ◽

Joint Axis

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Subtalar Joint Alignment in Ankle Osteoarthritis

Foot & Ankle Orthopaedics ◽

10.1177/2473011417s000249 ◽

2017 ◽

Vol 2 (3) ◽

pp. 2473011417S0002

Author(s):

Nicola Krähenbühl ◽

Lukas Zwicky ◽

Manja Deforth ◽

Beat Hintermann ◽

Markus Knupp

Keyword(s):

Ankle Joint ◽

Subtalar Joint ◽

Ct Scans ◽

Control Group ◽

Talar Dome ◽

Ankle Arthritis ◽

Ankle Osteoarthritis ◽

Talar Tilt ◽

Joint Inclination ◽

Weightbearing Ct

Category: Ankle Arthritis, Hindfoot Introduction/Purpose: The influence of the subtalar joint on the evolution of ankle joint osteoarthritis is still a matter of debate. Although subtalar joint compensation of deformities above the ankle joint was proposed until mid-stage of ankle osteoarthritis, the evidence of this assumption is weak. In this study, we investigated the subtalar joint alignment in different stages of ankle joint osteoarthritis using weightbearing CT scans. The influence of the tibio-talar tilt and presence of subtalar joint osteoarthritis was additionally assessed. We hypothesized, that the subtalar joint compensates for deformities above the ankle joint in early- to mid-stage of ankle osteoarthritis. We also hypothesized, that subtalar joint compensation increases with a pronounced tibio-talar tilt and decreases with the presence of subtalar joint osteoarthritis. Methods: We included patients with ankle joint osteoarthritis treated in our institution from January 2013 to April 2016. A control group of 28 patients was additionally assessed. Varus and valgus ankles were subdivided according to the modified Takakura classification, the tilt of the talus in the ankle mortise and stage of subtalar joint osteoarthritis. The type of ankle osteoarthritis was diagnosed on a plain weightbearing anterior to posterior radiograph of the ankle. The medial distal tibial angle (TAS) and the angle between the tibial shaft and the surface of the talar dome (TTS) were measured. The subtalar joint alignment was assessed using weightbearing CT scans. Two angles were assessed: The subtalar inclination angle (SIA) was measured to investigate the subtalar compensation. For assessment of the morphology of the talus, the inftal-subtal angle (ISA) was determined. Results: This analysis showed significant differences of the subtalar inclination between varus feet and the controls (SIA, P=.001). Regarding the talar morphology, significant differences were found between varus/ valgus feet and the controls (ISA, P=.001 and .036, respectively). No significant differences of the subtalar joint inclination and talar morphology could be identified comparing different stages of ankle joint osteoarthritis inside the varus or valgus group. No relationship between the tilt of the talus in the ankle joint mortise and the subtalar joint inclination or talar morphology was identified. Neither presence nor absence of subtalar joint osteoarthritis influenced the subtalar joint inclination and talar morphology. Conclusion: Varus ankles compensate in the subtalar joint for deformities above the ankle joint. Compensation had no influence on the stage of ankle osteoarthritis, extent of the tibio-talar tilt and stage of subtalar joint osteoarthritis. Consequently, the progression of ankle joint osteoarthritis is more depended on the supramalleolar alignment and integrity of the periarticular structures (i.e. ligaments and tendons) than on the osseous alignment of the subtalar joint.

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Frontal Plane Moments Do Not Accurately Reflect Ankle Dynamics during Running

Journal of Applied Biomechanics ◽

10.1123/jab.21.1.85 ◽

2005 ◽

Vol 21 (1) ◽

pp. 85-95 ◽

Cited By ~ 2

Author(s):

Kristian M. O’Connor ◽

Joseph Hamill

Keyword(s):

Ankle Joint ◽

Subtalar Joint ◽

Stance Phase ◽

Three Dimensional ◽

Frontal Plane ◽

Joint Moment ◽

Muscle Action ◽

Universal Joint ◽

Joint Moments ◽

Joint Axis

The ankle joint has typically been treated as a universal joint with moments calculated about orthogonal axes and the frontal plane moment generally used to represent the net muscle action about the subtalar joint. However, this joint acts about an oblique axis. The purpose of this study was to examine the differences between joint moments calculated about the orthogonal frontal plane axis and an estimated subtalar joint axis. Three-dimensional data were colected on 10 participants running at 3.6 m/s. Joint moments, power, and work were calculated about the orthogonal frontal plane axis of the foot and about an oblique axis representing the subtalar joint. Selected parameters were compared with a paired t-test (α = 0.05). The results indicated that the joint moments calculated about the two axes were characteristically different. A moment calculated about an orthogonal frontal plane axis of the foot resulted in a joint moment that was invertor in nature during the first half of stance, but evertor during the second half of stance. The subtalar joint axis moment, however, was invertor during most of the stance. These two patterns may result in qualitatively different interpretations of the muscular contributions at the ankle during the stance phase of running.

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A three-dimensional model to assess the effect of ankle joint axis misalignments in ankle–foot orthoses

Prosthetics and Orthotics International ◽

10.1177/0309364614543551 ◽

2014 ◽

Vol 40 (2) ◽

pp. 240-246 ◽

Cited By ~ 1

Author(s):

Stefania Fatone ◽

William Brett Johnson ◽

Kerice Tucker

Keyword(s):

Ankle Joint ◽

Three Dimensional ◽

Foot Orthoses ◽

Two Dimensional ◽

Dimensional Model ◽

Three Dimensional Model ◽

Ankle Foot Orthosis ◽

Joint Axis ◽

Ankle Foot Orthoses ◽

Foot Orthosis

Background: Misalignment of an articulated ankle–foot orthosis joint axis with the anatomic joint axis may lead to discomfort, alterations in gait, and tissue damage. Theoretical, two-dimensional models describe the consequences of misalignments, but cannot capture the three-dimensional behavior of ankle–foot orthosis use. Objectives: The purpose of this project was to develop a model to describe the effects of ankle–foot orthosis ankle joint misalignment in three dimensions. Study design: Computational simulation. Methods: Three-dimensional scans of a leg and ankle–foot orthosis were incorporated into a link segment model where the ankle–foot orthosis joint axis could be misaligned with the anatomic ankle joint axis. The leg/ankle–foot orthosis interface was modeled as a network of nodes connected by springs to estimate interface pressure. Motion between the leg and ankle–foot orthosis was calculated as the ankle joint moved through a gait cycle. Results: While the three-dimensional model corroborated predictions of the previously published two-dimensional model that misalignments in the anterior -posterior direction would result in greater relative motion compared to misalignments in the proximal -distal direction, it provided greater insight showing that misalignments have asymmetrical effects. Conclusions: The three-dimensional model has been incorporated into a freely available computer program to assist others in understanding the consequences of joint misalignments. Clinical relevance Models and simulations can be used to gain insight into functioning of systems of interest. We have developed a three-dimensional model to assess the effect of ankle joint axis misalignments in ankle–foot orthoses. The model has been incorporated into a freely available computer program to assist understanding of trainees and others interested in orthotics.

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Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis

Scientific Reports ◽

10.1038/s41598-021-93821-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Niksa Mohammadi Bagheri ◽

Mahmoud Kadkhodaei ◽

Shiva Pirhadi ◽

Peiman Mosaddegh

Keyword(s):

Clinical Data ◽

Three Dimensional ◽

Element Model ◽

Von Mises Stress ◽

Patient Specific ◽

Average Error ◽

Constant Thickness ◽

Arc Length ◽

Implementation Techniques ◽

Von Mises

AbstractThe implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outcomes. Thus, this study aimed to investigate the influence of ICRS implementation techniques and design on the postoperative biomechanical state and keratometry results. The clinical data of three patients with different stages and patterns of keratoconus were assessed to develop a three-dimensional (3D) patient-specific finite-element model (FEM) of the keratoconic cornea. For each patient, the exact surgery procedure definitions were interpreted in the step-by-step FEM. Then, seven surgical scenarios, including different ICRS designs (complete and incomplete segment), with two surgical implementation methods (tunnel incision and lamellar pocket cut), were simulated. The pre- and postoperative predicted results of FEM were validated with the corresponding clinical data. For the pre- and postoperative results, the average error of 0.4% and 3.7% for the mean keratometry value ($$\text {K}_{\text{mean}}$$ K mean ) were predicted. Furthermore, the difference in induced flattening effects was negligible for three ICRS types (KeraRing segment with arc-length of 355, 320, and two separate 160) of equal thickness. In contrast, the single and double progressive thickness of KeraRing 160 caused a significantly lower flattening effect compared to the same type with constant thickness. The observations indicated that the greater the segment thickness and arc-length, the lower the induced mean keratometry values. While the application of the tunnel incision method resulted in a lower $$\text {K}_{\text{mean}}$$ K mean value for moderate and advanced KC, the induced maximum Von Mises stress on the postoperative cornea exceeded the induced maximum stress on the cornea more than two to five times compared to the pocket incision and the preoperative state of the cornea. In particular, an asymmetric regional Von Mises stress on the corneal surface was generated with a progressive ICRS thickness. These findings could be an early biomechanical sign for a later corneal instability and ICRS migration. The developed methodology provided a platform to personalize ICRS refractive surgery with regard to the patient’s keratoconus stage in order to facilitate the efficiency and biomechanical stability of the surgery.

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