scholarly journals Patient-Specific Instrumentation for Total Ankle Replacement: The Emperor's New Clothes Redux

2022 ◽  
pp. 100153
Author(s):  
Thomas S. Roukis
Keyword(s):  
Total Ankle Replacement ◽  
Patient Specific ◽  
Patient Specific Instrumentation ◽  
Ankle Replacement

scholarly journals The Role of Axial Rotation in Total Ankle Replacement

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0009
Author(s):  
Ali-Asgar Najefi ◽  
Andrew Goldberg
Keyword(s):  
Surgical Techniques ◽  
Axial Rotation ◽  
Total Ankle Replacement ◽  
Tibial Tuberosity ◽  
Ct Scans ◽  
Patient Specific ◽  
Ankle Arthritis ◽  
Ankle Replacement ◽  
Wright Medical Technology ◽  
The Mean

Category: Ankle Arthritis Introduction/Purpose: The importance of implant orientation in the axial rotational plane is ill understood. No Total ankle replacement (TAR) implant deals specifically with rotation as part of the surgical technique. Preoperative computed tomography (CT) scan–derived patient-specific plans and guides (PROPHECY, Wright Medical Technology, Memphis, TN) have been developed for TAR scanning the knee and ankle for the purposes of patient specific instrumentation. The objectives of this study were to establish the range and relationship between the transtibial axis at the knee, the tibial tuberosity, and the transmalleolar axis using these CT scans in an adult population with ankle arthritis. Methods: 150 CT Scans of patients with end stage ankle osteoarthritis undergoing Psi, we measured the relationship between the transtibial axis, the tibial tuberosity and the transmalleolar axis (Figure 1). All CT scans were analysed using the Solidworks software (Dassault Systèmes). Varus or valgus arthritis, tibiotalar angle and presence of deformity was also recorded. Results: The mean difference in the axial plane between the transmalleolar axis and the tibial tuberosity was 17.9 ± 9.3 degrees externally rotated. There was a large range which was between -5 and 53 degrees of external rotation. The mean foot angle was 15.4 ± 11.1 degrees relative to the implant position. All planned implant positions were mean 1.0 ± 1.8 degrees (range -3.8 – 1.7 degrees) internally rotated to the transmalleolar axis. Varus or valgus ankle arthritis did not correlate with rotation of the tibial axis (p=0.4). Conclusion: There is a wide variation in rotational alignment of the tibia, which cannot be accurately assessed clinically or using plain radiographs. Surgical techniques that reference the tibial tuberosity to plan component alignment can be misleading and lead to implant malalignment. We recommend routine preoperative CT scanning prior to ankle replacement surgery and recommend research to assess the effects of axial rotation of implant performance and survival.

INFINITY® Total Ankle Replacement Including PROPHECY® Patient-Specific Alignment Guides

2021 ◽  
pp. 137-149
Author(s):  
Mark A. Prissel ◽  
Justin L. Daigre ◽  
Murray J. Penner ◽  
Gregory C. Berlet
Keyword(s):  
Total Ankle Replacement ◽  
Patient Specific ◽  
Ankle Replacement

scholarly journals The Ankle-Hindfoot Kinematics of Current Generation Total Ankle Replacement: A Cadaveric Gait Simulation

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0020
Author(s):  
Thos Harnroongroj ◽  
Daniel Sturnick ◽  
Scott J. Ellis ◽  
Constantine Demetracopoulos ◽  
Jonathan Deland
Keyword(s):  
Joint Kinematics ◽  
Total Ankle Replacement ◽  
Patient Specific ◽  
Fixed Bearing ◽  
Ankle Arthritis ◽  
Current Generation ◽  
Gait Simulation ◽  
Ankle Replacement ◽  
Wright Medical Technology ◽  
Significant Difference

Category: Ankle Arthritis Introduction/Purpose: Total ankle replacement (TAR) has developed as a standard treatment option for end-stage ankle arthritis with the primary benefit of pain relief and ankle-hindfoot motion preservation. The current generation of TARs features limited bone resection and improved initial fixation of components to restore physiologic constraint and the anatomic articulation of the ankle. However, the ankle-hindfoot kinematics of current TAR designs compared to the baseline native ankle have not yet been extensively studied. Cadaveric gait simulation is a valuable tool for investigating direct effects of surgical procedures on foot and ankle biomechanics. The objective of this study was to assess whether this current generation TAR system could provide normal ankle-hindfoot kinematics as the baseline native ankle using cadaveric gait simulation. Methods: Eleven mid-tibia cadaveric specimens were secured to a static mounting fixture with a six-degree of freedom robotic platform to simulate gait in native-intact and TAR conditions. A force plate was moved relative to the stationary specimen through an inverse tibial kinematic path calculated from in vivo data while extrinsic tendons were actuated using physiologic loads (Figure 1A). Ankle-hindfoot kinematics were measured from reflective markers attached to bones via surgical pins. TAR was performed using a current generation, fixed-bearing system by a fellowship-trained foot-ankle surgeon using the manufacturer described protocol (PROPHECY Patient-specific instrumentation, Infinity, Wright Medical Technology). Ankle-hindfoot joint kinematics were measured using the same tibial kinematic inputs and muscle forces as the intact condition. Non-parametric, bias-corrected bootstrapping was used to calculate 95% confidence intervals to compare motion between intact and total ankle replacement. Results: Analyses demonstrated no significant difference in average ankle-hindfoot joint kinematics between the intact and TAR conditions (Figure 1B). The result was consistent for the ankle, subtalar, and talonavicular joints, in each plane of motion. Conclusion: These findings demonstrate that the current generation of fixed-bearing TAR can recreate normal ankle-hindfoot kinematics patterns seen in normal ankles. Restoring ankle kinematics can be a significant factor in slowing down the progression of adjacent joint arthritis in the foot. However, it is still inconclusive whether ankle-hindfoot kinematics can be restored in patients with long standing ankle arthritis, and this should be addressed in future studies.

scholarly journals The Demographics of Total Ankle Replacement in the USA: A Study of 21,222 Cases Undergoing Pre- Operative CT Scan-Based Planning

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0038
Author(s):  
Murray J. Penner ◽  
Gregory C. Berlet ◽  
Ricardo Calvo ◽  
Eric Molina ◽  
David Reynolds ◽  
...  
Keyword(s):  
Ct Scan ◽  
Demographic Data ◽  
Total Ankle Replacement ◽  
Patient Specific ◽  
Clear Understanding ◽  
Ankle Arthritis ◽  
Ankle Replacement ◽  
The Usa ◽  
The Mean ◽  
Over Time

Category: Ankle; Ankle Arthritis Introduction/Purpose: To understand the role of total ankle replacement (TAR) in treating the spectrum of arthritis of the ankle, a clear understanding of the epidemiology of ankle arthritis is required. The largest pools of epidemiologic data available to date come from international registries. In the USA, the largest market for TAR, where an estimated 10,000 TARs are implanted per year, the largest pool of demographic data on patients undergoing TAR is comprised of just 805 cases collected over 6 years. With the advent of patient-specific instrumentation (PSI), detailed demographic and CT scan data can now be collected. These data on 21,222 cases undergoing CT scan-based PSI planning were reviewed to define the demographics of a very large cohort of TAR patients. Methods: The cohort contained 21,222 patients from the USA and Canada, with surgery dates from 2012 - 2019. Data analysed included deformity measures, presence of existing hardware and joint fusion status. To date, a subset sample of 4800 cases was available for analysis. Extraction is ongoing and data for the full cohort will soon be available. This subset described cases with surgery dates ranging from November 2015 through May 2019. Summary statistics to describe age, gender, ankle size, and tibio- talar deformity were calculated. Of the 4800 patients analyzed, 53% were male. Mean age 63.6 years (SD 10.4) (Age distribution in Figure 1a). The deformity distribution is shown in Figure 1b, with varus more common than valgus. The mean degree of deformity increased with every decade of patient age from 6.1° (age 30-39) to 9.2° (age 80-89), and over time from 9.3°(2016) to 11.8° (2019) [in stemmed- implant cases]. Results: Tibia size varied with gender. Females ranged between 34-38mm in 85% of cases; males from 41-48mm in 79%. Of 21,222 cases, 5964 (28%) had adjacent hardware (screws, etc) in situ and pre-existing ankle fusions were present in 517 (2.4%), increasing from 1.2% in 2013 to 2.9% in 2019.The mean age of TAR patients is similar to that reported in smaller series. Tibia size was significantly greater in males than females, a finding not previously reported in demographic literature. In contrast to knee arthritis, intra-articular deformity >5° is common, present in > 51% of cases (varus > valgus). This is the first series to show the degree of deformity increases with age. Over time, TAR is being used in cases with greater deformity. Conclusion: Hardware is seen to be commonly present in TAR, increasing complexity. Conversion of fusion to TAR, while rare, is more common than existing literature suggests, with the rate increasing each year, suggesting this may be an increasingly important role for TAR in the future. This study presents the largest set of demographic data on TAR patients in the literature. The demographics of USA patients undergoing TAR are similar to those seen in non-USA registries. Deformity is common, increasing with age. The severity of deformity treated with TAR and conversion of fusion to TAR are increasing over time.

scholarly journals Custom-made talar component of total ankle replacement implant, with or without lateral articular facet: A finite element analysis

2020 ◽  
Author(s):  
Min Zhu ◽  
Kang-lai Tang ◽  
Zhong-min Jin ◽  
Zhi Xu ◽  
Guo-cheng Feng ◽  
...  
Keyword(s):  
Finite Element ◽  
Contact Surface ◽  
Total Ankle Replacement ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Contact Type ◽  
Articular Facet ◽  
Ankle Replacement ◽  
Custom Made ◽  
Surface Contact

Abstract Background: The present patient dissatisfaction with and high failure rates of total ankle replacement (TAR) are likely due to current prosthesis designs, which are not patient-specific and anatomy-based, leading to unphysiological motion at the replaced joint. The design of customized prostheses is already possible by means of medical imaging and additive manufacturing technology.Methods: In this study, dome and geometric fixtures of custom-made talar components for TAR were designed, and we investigated two kinds of talar components: 2-surface contact type (Type-1, without lateral articular facet) and 3-surface contact type (Type-2, with lateral articular facet). The effects of the above two prostheses on the loading stress of the prosthesis contact surface were comparatively analysed with three-dimensional finite element models.Results: The maximum and average von Mises stress values of the 3-surface prosthesis were smaller than those of the 2-surface prosthesis. In terms of contact surface pressure, the maximum and average values of the 3-surface prosthesis are almost equal to those of the 2- surface type. In terms of the tangential slip distribution of the contact surface, the maximum and average values of the 3-surface prosthesis were smaller than those of the 2-surface prosthesis.Conclusions: The custom-made talar component of the total ankle replacement implant reproduced the anatomical morphology of the natural articular surfaces well. The 3-surface contact type prosthesis with lateral articular facet, compared to the 2-surface contact type without lateral articular facet, offers better static stability by affecting the internal and external forces.

Computed Tomography-Based Patient-Specific Instrumentation Loses Accuracy with Significant Varus Preoperative Misalignment

2020 ◽  
Author(s):  
Vicente Jesús León-Muñoz ◽  
Mirian López-López ◽  
Alonso José Lisón-Almagro ◽  
Francisco Martínez-Martínez ◽  
Fernando Santonja-Medina
Keyword(s):  
Computed Tomography ◽  
Deformity Correction ◽  
Patient Specific ◽  
Control Group ◽  
X Rays ◽  
Varus Alignment ◽  
Patient Specific Instrumentation ◽  
Conventional Instrumentation ◽  
The Mean ◽  
Valgus Alignment

AbstractPatient-specific instrumentation (PSI) has been introduced to simplify and make total knee arthroplasty (TKA) surgery more precise, effective, and efficient. We performed this study to determine whether the postoperative coronal alignment is related to preoperative deformity when computed tomography (CT)-based PSI is used for TKA surgery, and how the PSI approach compares with deformity correction obtained with conventional instrumentation. We analyzed pre-and post-operative full length standing hip-knee-ankle (HKA) X-rays of the lower limb in both groups using a convention > 180 degrees for valgus alignment and < 180 degrees for varus alignment. For the PSI group, the mean (± SD) pre-operative HKA angle was 172.09 degrees varus (± 6.69 degrees) with a maximum varus alignment of 21.5 degrees (HKA 158.5) and a maximum valgus alignment of 14.0 degrees. The mean post-operative HKA was 179.43 degrees varus (± 2.32 degrees) with a maximum varus alignment of seven degrees and a maximum valgus alignment of six degrees. There has been a weak correlation among the values of the pre- and postoperative HKA angle. The adjusted odds ratio (aOR) of postoperative alignment outside the range of 180 ± 3 degrees was significantly higher with a preoperative varus misalignment of 15 degrees or more (aOR: 4.18; 95% confidence interval: 1.35–12.96; p = 0.013). In the control group (conventional instrumentation), this loss of accuracy occurs with preoperative misalignment of 10 degrees. Preoperative misalignment below 15 degrees appears to present minimal influence on postoperative alignment when a CT-based PSI system is used. The CT-based PSI tends to lose accuracy with preoperative varus misalignment over 15 degrees.

Living With Both a Total Ankle Replacement and an Ankle Fusion: A Qualitative Study From the Patients’ Perspective

2021 ◽  
pp. 107110072110044
Author(s):  
Catherine Conlin ◽  
Ryan M. Khan ◽  
Ian Wilson ◽  
Timothy R. Daniels ◽  
Mansur Halai ◽  
...  
Keyword(s):  
Hospital Setting ◽  
Case Series ◽  
Total Ankle Replacement ◽  
Qualitative Description ◽  
Level Of Evidence ◽  
Foot Placement ◽  
Advantages And Disadvantages ◽  
Ankle Fusion ◽  
Ankle Replacement ◽  
Patient Reported

Background: Total ankle replacement (TAR) and ankle fusion are effective treatments for end-stage ankle arthritis. Comparative studies elucidate differences in treatment outcomes; however, the literature lacks evidence demonstrating what outcomes are important to patients. The purpose of this study was to investigate patients’ experiences of living with both a TAR and ankle fusion. Methods: This research study used qualitative description. Individuals were selected from a cohort of patients with TAR and/or ankle fusion (n = 1254). Eligible patients were English speaking with a TAR and contralateral ankle fusion, and a minimum of 1 year since their most recent ankle reconstruction. Surgeries were performed by a single experienced surgeon, and semistructured interviews were conducted by a single researcher in a private hospital setting or by telephone. Ankle Osteoarthritis Scale (AOS) scores, radiographs, and ancillary surgical procedures were collected to characterize patients. Themes were derived through qualitative data analysis. Results: Ten adults (8 men, 2 women), ages 59 to 90 years, were included. Average AOS pain and disability scores were similar for both surgeries for most patients. Participants discussed perceptions of each reconstructed ankle. Ankle fusions were considered stable and strong, but also stiff and compromising balance. TARs were considered flexible and more like a “normal ankle,” though patients expressed concerns about their TAR “turning” on uneven ground. Individuals applied this knowledge to facilitate movement, particularly during a first step and transitioning between positions. They described the need for careful foot placement and attention to the environment to avoid potential challenges. Conclusion: This study provides insight into the experiences of individuals living with a TAR and ankle fusion. In this unusual but limited group of patients, we found that each ankle reconstruction was generally perceived to have different characteristics, advantages, and disadvantages. Most participants articulated a preference for their TAR. These findings can help clinicians better counsel patients on expectations after TAR and ankle fusion, and improve patient-reported outcome measures by better capturing meaningful outcomes for patients. Level of Evidence: Level IV, case series.

scholarly journals Patient-specific instrumentation (PSI) Referencing High Tibial Osteotomy Technological Transfer and Education: protocol for a double-blind, randomised controlled trial (PROTECTED HTO Trial)

BMJ Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. e041129
Author(s):  
Lawrence Chun Man Lau ◽  
Elvis Chun Sing Chui ◽  
Jason Chi Ho Fan ◽  
Gene Chi Wai Man ◽  
Yuk Wah Hung ◽  
...  
Keyword(s):  
Randomised Controlled Trial ◽  
Knee Osteoarthritis ◽  
High Tibial Osteotomy ◽  
Controlled Trial ◽  
Patient Specific ◽  
Tibial Osteotomy ◽  
Double Blind ◽  
Patient Specific Instrumentation ◽  
3D Printed ◽  
Randomised Controlled

IntroductionHigh tibial osteotomy (HTO) is a treatment of choice for active adult with knee osteoarthritis. With advancement in CT imaging with three-dimensional (3D) model reconstruction, virtual planning and 3D printing, patient-specific instrumentation (PSI) in form of cutting jigs is employed to improve surgical accuracy and outcome of HTO. The aim of this randomised controlled trial (RCT) is to explore the surgical outcomes of HTO for the treatment of medial compartment knee osteoarthritis with or without a 3D printed patient-specific jig.Methods and analysisA double-blind RCT will be conducted with patients and outcome assessors blinded to treatment allocation. This meant that neither the patients nor the outcome assessors would know the actual treatment allocated during the trial. Thirty-six patients with symptomatic medial compartment knee osteoarthritis fulfilling our inclusion criteria will be invited to participate the study. Participants will be randomly allocated to one of two groups (1:1 ratio): operation with 3D printed patient-specific jig or operation without jig. Measurements will be taken before surgery (baseline) and at postoperatively (6, 12 and 24 months). The primary outcome includes radiological accuracy of osteotomy. Secondary outcomes include a change in knee function from baseline to postoperatively as measured by three questionnaires: Knee Society Scores (Knee Scores and Functional Scores), Oxford Knee Scores and pain visual analogue scale (VAS) score.Ethics and disseminationEthical approval has been obtained from the Joint Chinese University of Hong Kong – New Territories East Cluster Clinical Research Ethics Committee (CREC no. 2019.050), in accordance with the Declaration of Helsinki. The results will be presented at international scientific meetings and through publications in peer-reviewed journals.Trial registration numberNCT04000672; Pre-results.

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