Indications For Total Ankle Replacement Research Articles

Long-Term Outcomes After Total Ankle Arthroplasty: A Systematic Review

Category: Ankle Arthritis; Ankle Introduction/Purpose: There is a paucity of aggregate literature reporting on long-term patient-reported outcomes (PROs) and implant failure after total ankle arthroplasty (TAA). The purpose of this study is to report an aggregate of literature on minimum 10-year patient-reported outcomes after total ankle arthroplasty. Methods: A systematic review on minimum 10-year PROs of TAA was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Pubmed, Scopus, and Cochrane Trials were queried on December 28th, 2022, with the following keywords: (ankle) AND (replacement or arthroplasty) AND (long-term or 10-year). Primary research articles were included if they reported minimum 10-year PROs for patients undergoing primary TAA and written in English. Forest plots with heterogeneity were created for PROs reported preoperatively and postoperatively in three or more studies. Long-term was defined as minimum 10-year follow-up. Survivorship was defined by implant failure which was determined uniquely by each study. Results: Six studies met the inclusion criteria with all 6 studies being level IV. A total of 277 ankles with average age range of 54-60.9 years were included in the study with follow up ranging from 10 to 24 years. The primary indication for total ankle replacement was osteoarthritis. Two of the six studies reported significant improvement in PROs following surgery. The remaining 4 studies also demonstrated improvement in PRO however no p values were reported. A forest plot was generated for the AOFAS score and I2 of 67% was calculated. Survivorship at a minimum of 10 year follow up ranged from 66-94.4%. Average time to implant failure ranged from 54.7-166 months. Conclusion: Patients undergoing primary TAA demonstrated improved outcomes at minimum 10-year follow-up. However, they demonstrated variable rates of survivorship ranging from 66-94.4% with average time to implant failure ranging from 54.7 – 166 months.

A Review Of Distraction Arthroplasty Vs Ankle Arthrodesis Vs Ankle Replacement

Recent developments in surgical techniques have led to new methods to treat ankle arthritis and perhaps produce a better effect on joint function and gait improvement. The indications for total ankle replacement, ankle fusion, or distraction arthroplasty in the management of ankle arthritis are controversial. The aim of this study is to evaluate different approaches with an overview of the literature. Core tip: Ankle arthritis is a common debilitating chronic disease that is not only present in the geriatric population, but also younger populations. The main method to treat end stage arthritis is ankle fusion. Ankle replacement is currently improving in popularity. Both treatment options manage end stage arthritis. It is important to consider the role of distraction arthroplasty in the context of these two other well accepted treatments. Here we examine the literature from 1941 to 2020 considering our own experience and the growing role regenerative techniques and biologics.

Clinical Radiographical Outcomes and Complications after a Brand-New Total Ankle Replacement Design through an Anterior Approach: A Retrospective at a Short-Term Follow Up.

Recently, the progress in techniques and in projecting new prosthetic designs has allowed increasing indications for total ankle replacement (TAR) as treatment for ankle osteoarthritis. This retrospective work comprehended 39 subjects aged between 47 and 79 years old. The patients, observed for at least 12 months (mean follow up of 18.2 ± 4.1 months), have been evaluated according to clinical and radiological parameters, both pre- and post-operatively. The AOFAS and VAS score significantly improved, respectively, from 46.2 ± 4.8 to 93.9 ± 4.1 and from 7.1 ± 1.1 to 0.7 ± 0.5 (p value < 0.05). At the final evaluation, the mean plantarflexion passed from 12.2° ± 2.3° to 18.1° ± 2.4° (p value < 0.05) and dorsiflexion from a pre-operative mean value of 8.7° ± 4.1° to 21.7° ± 5.4° post-operatively (p value < 0.05). This study found that this new total ankle replacement design is a safe and effective procedure for patients effected by end-stage ankle osteoarthritis. Improvements have been demonstrated in terms of range of motion, radiographic parameters and patient-reported outcomes. However, further studies are needed to assess the long-term performance of these prostheses.

Is it Safe to Offer Total Ankle Replacement (TAR) Surgery in Patients with Type II Diabetes?

Category:Ankle; Ankle Arthritis; Diabetes; Midfoot/ForefootIntroduction/Purpose:The indications for Total Ankle Replacement (TAR) in patients with Type II Diabetes mellitus is poorly defined and there is paucity of literature reporting clinical, radiological and patient reported outcomes for TAR in this patient group. We aimed to explore the ideal pre-operative criteria for TAR in patients with Type II DM based on results from our center.Methods:We studied the x-rays, clinical findings and patient reported outcomes of surgery at pre-op and 5 years for patients who underwent a total ankle replacement at our center between 2006 and 2014 who had Type II DM. This was a retrospective study. The above findings were also compared between patients who had Type II DM vs. who were not diabetic. Pre-operative screening for diabetic patients included Hb1Ac levels, clinical reporting of swelling, warmth, erythema findings, neurovascular status including proprioception, vibration and neuro filament tests. Statistical analysis of WOMAC and SF-36 scores and differences between diabetic and non-diabetic patients were calculated using General Linear Model - repeated measures ANOVA. Patient satisfaction was analyzed using chi-square test. Rates of superficial and deep infection as well as revision were recorded.Results:Of 230 patients, 9 (3.9%) were diabetic. Pre-op radiographic analysis showed features confining to OA; x-ray, CT scan showed no signs of bone debris, fragmentation per articular fractures. Talus was not translated, no evidence of OA in Subtalar or Talonavicular joint. At 5 years, there was no implant subsidence, loosening, migration or peri-prosthetic cysts; hind and midfoot joints had no features of diabetic arthropathy/collapse. Comparing outcomes to Non-diabetic TAR patients, WOMAC & SF-36 scores showed significant (p<0.05) improvement and no significant difference between groups from pre-op to 5 years. In the diabetic group there was 1 superficial infection (11%) 1 deep infection that required revision (11%) compared to 30 superficial infections (13.6%), 1 deep infection (0.5%) and 12 revisions (5.4%) in the non-diabetic group.Conclusion:Painful end stage OA in Type II DM can be treated by TAR, taking into consideration the inclusion and exclusion criteria that we have used in our series.

Subtalar Joint Arthritis After Total Ankle Replacement

Category: Ankle Arthritis Introduction/Purpose: It has been shown that total ankle replacement (TAR) is effective in reducing pain and maintaining function in posttraumatic ankle osteoarthritis (OA). Compared to ankle fusion, TAR restores hindfoot kinematics more physiological. However, the assumption that the maintenance of ankle motion has a protective effect on the subtalar joint is still a matter of debate. Only a scarce number of long-term studies exist to support this statement.The purpose of this study was (1) to evaluate to which extent the integrity of the subtalar joint can be preserved by treating patients with a TAR, (2) to determine the rate of subtalar fusion following TAR, and (3) to determine whether the need of subsequent subtalar fusion was predictable at time of TAR. Methods: A consecutive series of 1140 primary TAR (508 female, 632 male, median age 63.5 years), performed between May 2000 and December 2015, were prospectively documented. The indication for TAR was posttraumatic OA in 78%, primary and systemic OA in 10% each, and other secondary OA in 3% of the cases. 199 subtalar joints were either fused before (n=73) or during TAR surgery (n=126), leaving 941 subtalar joints available for analysis. Radiographs before implantation and at latest follow-up were classified using the Kellgren and Lawrence Grading Score (KLS). In case of a subtalar fusion, the radiograph prior to the fusion was classified. Results: After a median radiographic follow-up of 6.1 years, the KLS remained unchanged in 66% of all cases. While it was increased by one stage in 30%, it was increased by two stages in 3%; whereas, signs of OA decreased by one stage in 1%. Cases with an increase of two stages on the KLS had a longer follow-up compared to cases without increase (p=0.047).37 cases (3.9%) underwent a subtalar joint fusion, of which the indication was progressive OA in 19 cases (51%), instability in 10 cases (27%) and others in 8 cases (22%). Subtalar joints that required a fusion after TAR did not show higher preoperative KLS than the group which did not need a subtalar joint fusion. Conclusion: Apparently, TAR protects the subtalar joint from secondary degeneration, as found in 67% with no increase in KLS. Although 33% showed an increase in the KLS, only 2% required a subtalar fusion due to progressive OA. Overall, the rate of subtalar joint fusion after TAR was low and comparable to the rates reported in the literature. Subtalar joints requiring fusion after TAR did not show higher preoperative rates of OA. Therefore, the KLS classification of subtalar OA on conventional radiographs provides only limited information about the need for postoperative subtalar fusion, and thus need to be interpreted with caution.

Syndesmotic Instability After Total Ankle Replacement

Category: Ankle Arthritis Introduction/Purpose: Total ankle replacement (TAR) evolved over the last decades and has been shown to be an effective concept in the treatment of ankle osteoarthritis (OA). In three-component designs, the second interface between polyethylene insert (PI) and tibial component allows the PI to find its position according the individual physiological properties. This was believed to decrease shear forces within the ankle joint. However, it is not clarified to which extent such an additional degree of freedom may overload the ligamentous structures of the ankle joint over time. This may in particular be the case for the syndesmotic ligaments. Therefore, the purpose of this study was to analyze all ankles after TAR that showed a symptomatic overload of the syndesmotic ligaments and to determine the potential consequences. Methods: Between 2003 and 2017, 31 ankles (females, 17; males 14; mean age 60 [40-79] years) were treated with a tibio-fibular fusion for a symptomatic instability of the syndesmosis. The indication for TAR was posttraumatic OA in 27 (87%), primary OA in 3 (10%), and hemochromatosis in one ankle (3%). The 31 ankles included 23 primary TAR (74%), 6 revision TAR (19%), and two take-down of a fusion and conversion to TAR (7%). Criteria for fusion were the presence of at least two of the followings: (1) tenderness over the syndesmosis, (2) pain while compressing the fibula against the tibia (squeeze test), (3) pain while rotating the foot externally (external rotation test), (4) widening of the syndesmosis on an anteroposterior view. Alignment of TAR (tibial articular surface [TAS] angle) and hindfoot alignment were measured on standard radiographs. Intraoperatively, the syndesmotic instability was confirmed before fusion. The wear of PI was documented. Results: After a mean of 63 (range, 4 – 152) months after TAR, all patients evidenced pain at the level of the syndesmosis of at least 3 months. 25 ankles (81%; 24 after posttraumatic OA) showed a widening of the syndesmotic space and 22 ankles (71%) of the medial clear space with lateral translation of the talus. The PI was seen to overlap the tibial component in 15 ankles (48%). Nine ankles (29%) evidenced cyst formation, and eight ankles (26%) showed a decrease in height of the PI; whereas, in 3 ankles (10%) a fracture of the PI was found. A valgus misalignment of the heel was found in 25 ankles (81%), a valgus TAS in 16 (52%) and a varus TAS in 11 ankles (36%). Conclusion: A syndesmotic instability after a three-component TAR apparently occurred mostly after posttraumatic OA, in particular if the heel was left in valgus. If the talus starts to move lateralward, the PI seems to be at risk for increased wear and finally mechanical failure (Figure 1). Therefore, a valgus misaligned heel should always be corrected during TAR implantation. If there is any sign of syndesmotic instability, a fusion should be considered. Further studies must proof whether in cases with a syndesmotic instability the use of a two-component design will be superior, as it stabilizes the talus in the coronal plane.

2017 IFFAS Award for Excellence Winner

Category: Ankle Arthritis Introduction/Purpose: Pilon fractures of the distal tibia are high energy injuries often occurring in a young patient cohort. Despite optimal acute fracture management, post traumatic osteoarthritis of the tibiotalar joint is a common corollary. Standard treatment is by way of tibiotalar arthrodesis, however the lack of motion at the ankle afforded by this treatment is often poorly tolerated by patients and can lead to arthrosis of adjacent joints. Total ankle replacement (TAR) offers an attractive pain relieving and motion preserving option for this patient subgroup. Here we report the two-year patient reported outcome measures for a cohort of patients undergoing TAR for osteoarthritis secondary to tibial pilon fracture and compare them to the outcomes for other indications for total ankle replacement. Methods: The results of patient-reported outcome measures (PROMs) for TAR performed between March 2006 and November 2014 by a single surgeon at a single institution in the United Kingdom were reviewed. Data collected included Foot and Ankle Outcome Scores (FAOS) (WOMAC pain/stiffness/function); SF-36 General Health Questionnaire; number of comorbidities; self- reported BMI and patient satisfaction scores. Time points for data collection were pre-operatively and then at one and two years post-operatively. Clinical notes and radiographs were reviewed to highlight the indication for TAR and were categorised into the following sub-groups: osteoarthritis (OA); rheumatoid arthritis (RA); arthritis following pilon fracture; arthritis following ankle fracture; and post-traumatic arthritis without previous fracture (PTOA). FAOS and SF-36 were analysed using a general linear model to assess variance and by way of repeated measures ANOVA. Demographic data was assessed using student t-test and chi- squared analysis. Patient satisfaction scores were evaluated using cross-tabulation and chi-squared examination. Results: The pilon fracture group had the youngest average age and highest BMI (56.5 years; mean BMI 31.6). There was no statistically significant difference in number of reported comorbidities between subgroups (p&gt;0.05). Significant improvement in FAOS pain, function and stiffness scores was seen in all subgroups from pre-operatively to one year post-operatively (p=0.01, 0.05 and 0.03 respectively). No further statistically significant improvement in the same scores was seen at two years. SF-36 analysis demonstrated similar results for all subgroups. There was general improvement in all parameters except for general health (p=0.890 at one year) and reduction in physical function in the RA group from first to second post-operative years (p=0.046). Patient satisfaction survey showed similar results for all subgroups. Conclusion: Our study has demonstrated that statistically significant improvement is seen in FAOS pain, function and stiffness scores in all subgroups of patients undergoing TAR by one year post surgery and that this improvement is maintained by two year follow up. There was no major difference in any of the reported outcomes between subgroups by two years post-operatively, suggesting that TAR performed for arthritis secondary to pilon fracture is a realistic alternative to tibio-talar arthrodesis.

Total ankle replacement design and positioning affect implant-bone micromotion and bone strains

Implant loosening – commonly linked with elevated initial micromotion – is the primary indication for total ankle replacement (TAR) revision. Finite element modelling has not been used to assess micromotion of TAR implants; additionally, the biomechanical consequences of TAR malpositioning – previously linked with higher failure rates – remain unexplored. The aim of this study was to estimate implant-bone micromotion and peri-implant bone strains for optimally positioned and malpositioned TAR prostheses, and thereby identify fixation features and malpositioning scenarios increasing the risk of loosening. Finite element models simulating three of the most commonly used TAR devices (BOX®, Mobility® and Salto®) implanted into the tibia/talus and subjected to physiological loads were developed. Mobility and Salto demonstrated the largest micromotion of all tibial and talar components, respectively. Any malpositioning of the implant creating a gap between it and the bone resulted in a considerable increase in micromotion and bone strains. It was concluded that better primary stability can be achieved through fixation nearer to the joint line and/or while relying on more than a single peg. Incomplete seating on the bone may result in considerably elevated implant-bone micromotion and bone strains, thereby increasing the risk for TAR failure.

Posterior Talar Shifting in Mobile-Bearing and Fix-Bearing Total Ankle Replacement

Category: Ankle Arthritis Introduction/Purpose: Sagittal implant malalignment after total ankle replacement (TAR) has been considered to be a possible cause for premature implant failure. In a prior study, the change of the tibiotalar ratio (T-T ratio) over time in TARs was assessed in an unconstrained, three component implant. A significant increase in the T-T ratio between 2 and 6 months after surgery (from 34.6% to 37.2%) was documented. This variation of the talar position in the sagittal plane may be due to the presence of an inlay between the tibial and the talar components. Aim: The aim of this study was to compare the translation of the talus in TARs performed with an unconstrained, three-component design (Hintegra, Newdeal, Lyon, France; Integra, Plainsboro, NJ), and those performed with a semi-constrained, two- component design (Zimmer Trabecular Total Ankle, Zimmer, Warsaw, IN). Methods: The study included 71 consecutive patients (71 ankles) who underwent TAR with the Hintegra implant and 24 consecutive patients (24 ankles) who received the Zimmer implant between May 2011 and December 2014. The most common indication for TAR was post-traumatic arthritis (80.3% and 75.0% in the Hintegra group and in the Zimmer group, respectively). Patients were assessed clinically and radiologically preoperatively (T0), at 6 months (T2) and 12 months (T3) post-surgery. There was also a radiological assessment 2 months after surgery (T1). Results: The comparison of the T-T ratio between the two groups and over time indicated an interaction between time and group, therefore the changes of the T-T ratio with time were affected by the implant type factor (p &lt; 0.0001). The changes of the post-operative T-T ratio over time were not significant in the Zimmer group (35.7%±6.7% at T1, T2, and T3; p=1.0 for each pairwise comparison). In the Hintegra group, the T-T ratio at 2 months (34.4%±5.5%) was significantly different to the T-T ratio at 6 months (37.0% ± 5.8%; p &lt; 0.0001). The American Orthopaedic Foot &amp; Ankle Society (AOFAS) score significantly increased from pre-op to 6 months post-surgery in both the Hintegra group (53.3±16.0 at 6 mos; p &lt; 0.0001) and the Zimmer group (76.8±7.0 at 6 mos; p &lt; 0.0001). There was no statistical difference in the preoperative scores (Hintegra: 32.7 ± 12.8; Zimmer: 34.6 ± 11.9; p=0.5347). Conclusion: The significant antero-posterior translation of the talus documented only in the cohort receiving the unconstrained, three-component implant may have associated with, and produced by the presence of the mobile bearing interface between the polyethylene insert and the tibial prosthesis.

Total Ankle Replacement with a Staged Correction of a 20 Degree Post Traumatic Ankle Valgus and Medial Ankle Instability

Total ankle replacement can be a challenging surgery especially when pre-operative deformity exists. Most authors advocate the indication for total ankle replacement should be narrowed to patients with less than 10 to 15 degrees of pre-operative varus or valgus. When greater than 10-15 degrees of coronal plane malalignment is found, ancillary procedures must be performed. We report a case of a 56 year old male with 20 degrees of pre-operative ankle valgus after a pronation-external rotation injury that was malreduced at an outside institution. In addition to the valgus, the patient presented with medial ankle instability, distal lateral tibial osteonecrosis and a shortened, posteriorly rotated fibula. Staged procedures were employed to successfully realign the patient’s ankle joint. The patient was first brought to the operating room and stressed under c-arm fluoroscopy. He was found to have instability of the deltoid complex. He subsequently underwent an ankle arthrotomy, synevectomy and deltoid imbrication to re-establish medial ankle stability. Second, the patient underwent a fibular lengthening and derotation, syndesmotic fusion and medial opening wedge tibial osteotomy. Once consolidation was confirmed by CAT scan, the patient had a gastrocnemius lengthening total ankle arthroplasty with a Zimmer trabecular metal implant (Zimmer Inc®, Warsaw, IN) and debridement and grafting of the distal lateral tibial osteonecrosis. The patient is now greater than 24 months post operatively and able to ambulate pain free without assistive devices.

Indications of Total Ankle Replacement for Ankle Arthritis: The Evaluation of Quality of Life and Radiographic Findings

Objectives: Little is known about the quality of life and clear cut radiographic grades of ankle arthritis in patients with indication for the total ankle replacement (TAR) comparing with patients without indication for TAR. This study was to compare the quality of life and radiographic grades of ankle arthritis in patients who had ankle arthritis with and without indication for TAR. Methods: From January 2010 to November 2013, the evaluation was conducted on 23 patients aged 18 or older who had ankle arthritis from several causes. The 23 patients were divided into two groups according to their indications of TAR: TAR group (n=7 patients) and non-TAR group (n=16 patients). The medical records of each patient were reviewed to collect for the pre-treatment visual analogue scale (VAS-pain score), visual analogue scale foot and ankle (VAS-FA) score, health-related quality of life score via short-form 36 (SF-36), baseline data including age, gender, side of ankle arthritis, cause of arthritis, radiographic findings, and treatment methods. Results: There were no significant differences in the mean VAS-pain, VAS-FA, and SF-36 scores between the TAR and non-TAR groups (p>0.05). Poorer radiographic grades as Takakura grades 3-4 or the author's grades 3-4 were significantly higher in TAR group (p<0.001). SF-36 scores were significantly lower in patients with poorer radiographic grades in both Takakura (p=0.023) or Angthong (p=0.042) classifications. Conclusion: Although quality of life in patients with indication for TAR was not significantly poorer than patients without indication for TAR, radiographic grades in patients with indication for TAR were significantly poorer than patients without indication for TAR. Radiographic grades of ankle arthritis as Takakura grades 3-4 or the author's grades 3-4 are the clear cut criteria in combination with other accepted criteria to be indications for TAR.

The Revolution and Unanswered Questions

Commentary With the relatively recent publication of the long-term results of total ankle replacement1, as well as the efficacy of this procedure compared with ankle arthrodesis2, total ankle replacement is rapidly becoming a viable option in the treatment of degenerative disorders of the ankle. As more orthopaedic surgeons continue to push the boundaries and as more residencies and fellowships are training surgeons in this procedure, there will obviously be an increase in the number of total ankle replacements performed each year. Couple that with the aging population and perceived quality-of-life issues, and I believe that we are on the cusp of a revolution in the treatment of such diseases. Although there will always be a role for ankle arthrodesis, I believe that total ankle replacement, much like total knee and total hip replacement, will become the standard of care. However, along with such advancement there will be new questions that need to be addressed regarding indications for total ankle replacement (limitations involving deformity, age, and weight) and revision options. The article by Hintermann et al. addresses the question regarding revision surgery, and it is an important article as the primary implants will have a limited life span and there will be a need for viable revision solutions even with use of the strictest indications. The strengths and weaknesses of this article are closely related. The most obvious weakness, from my perspective, is that it represents merely another case series study performed by a single surgeon with use of his prosthesis design, which is currently not available for use in the United States. Will these results be reproducible, and how can we interpret this information regarding an implant that is currently not available for use in the United States? In my opinion, however, this study goes beyond outcome reporting. It is a starting point from which to begin to answer revision-related questions. The authors present a classification system for evaluating failure and bone loss defects that will be useful for further publications and discussions regarding the patterns of failure. The authors also go further by defining principles for revision surgery that are potentially general in nature, useful for a range of similar primary implant designs. The failures of the primary ankle replacements were not limited to a single implant design, and the authors applied their concepts across a broad spectrum of failures with good intermediate-term results. The results would, in fact, have been useful even if the revision outcomes had been poor. Surgeons will also be able to use the information in discussing the available options and outcomes with their patients when total ankle replacements fail. Although I do not believe that this will become a landmark article, I do believe that it is the type of article that is needed, especially as we begin to try to answer the questions that will be posed as more total ankle replacement procedures are performed. Obviously, other studies will need to be performed, including direct comparisons of ankle arthrodesis with revision, to allow the surgeon to make decisions regarding the best option for patients. Even other surgeons’ experiences will be useful as we strive to answer the question of what to do about implant failure, other than tell our patients that we’ll cross that bridge later. This study is a necessary starting point that provides a guideline for revision surgery and will advance our understanding of the use of total ankle replacement. Although the outcome results presented in this article may only be directly applicable to the HINTEGRA implant, the overall concepts are beneficial to our understanding of the future treatment options for failed total ankle replacements.

Revisionsarthroplastik des oberen Sprunggelenks

In the last 20years total ankle replacement has become a viable alternative to arthrodesis for end-stage osteoarthritis of the ankle. Numerous ankle prosthesis designs have appeared on the market in the past and attracted by the encouraging intermediate results reported in the literature, many surgeons have started to perform this procedure. With increased availability on the market the indications for total ankle replacement have also increased in recent years. In particular, total ankle replacement may now be considered even in younger patients. Therefore, despite progress in total ankle arthroplasty the number of failures may increase. Up to now, arthrodesis was considered to be the gold standard for salvage of failed ankle prostheses. Because of extensive bone loss on the talar side, in most instances tibiocalcaneal fusion is the only reliable solution. An alternative to such extended hindfoot fusions would be revision arthroplasty. To date, however, there are no reported results of revision arthroplasty for salvage of a failed ankle replacement.Based on our experience prosthetic components with a flat undersurface are most likely to be able to find solid support on remaining bone stock. The first 83 cases (79patients, 46 males, 33 females, average age 58.9 years, range 30.6-80.7years) with a average follow-up of 5.4 years (range 2-11 years) showed excellent to good results in 69 cases (83%), a satisfactory result in 12 cases (15%) and a fair result in 2 cases (2%) and 47patients (56%) were pain free. Primary loosening was noted in three cases and of these two cases were successfully revised by another total ankle replacement and in one case with arthrodesis. Another case with hematogenous infection was also revised by arthrodesis. At the last follow-up control two components were considered to be loose and the overall loosening rate was thus 6%.This series has proven that revision arthroplasty can be a promising option for patients with failed total ankle prosthesis. The most challenging issue is the solid anchoring of available components on residual bone. More experience is needed, however, to better define the possibilities and limitations of revision arthroplasty.

Total Ankle Replacement Outcome in Low Volume Centers: Short-Term Followup

The indication for total ankle replacement (TAR) as an alternative to ankle fusion continues to be a much-debated topic. The reported survival of TAR at midterm followup is approximately 90%. The aim of this study was to compare functional outcome and survival of TAR in low volume centers versus high volume centers. A retrospective cohort study was carried out in four low volume centers. Sixty-four Salto TARs were performed between 2003 and 2007 in 60 patients. Fifty-five (59 TAR) patients were eligible for followup with 28 men. Standardized American Orthopaedic Foot and Ankle Society (AOFAS) scores, patient satisfaction, and range of motion (ROM) were measured. Standardized and dynamic radiographs were used for evaluation of radiolucencies, ROM and component alignment. Seven of the 59 ankle prostheses had to be revised: five for loosening and two for deep infection. Three of the five revised for loosening went on to fusion, and in two a revision of one of the components was performed. Both infected ankles were fused. Five patients declined to participate this study, among these two were TAR failures. Survival with revision as the endpoint was 86% at final followup. The average AOFAS score was 75 (SD ± 15). On dynamic radiographs the ROM was 22 degrees (SD ± 8) in the tibiotalar joint. This study demonstrated that functional results of total ankle replacement in low volume centers were comparable to most high volume centers but survival was lower especially when we consider our shorter followup than most comparable series.

The effect of specimen size and geometry on the mechanical behaviour of trabecular bone specimens

Implant loosening – commonly linked with elevated initial micromotion – is the primary indication for total ankle replacement (TAR) revision. Finite element modelling has not been used to assess micromotion of TAR implants; additionally, the biomechanical consequences of TAR malpositioning – previously linked with higher failure rates – remain unexplored. The aim of this study was to estimate implant-bone micromotion and peri-implant bone strains for optimally positioned and malpositioned TAR prostheses, and thereby identify fixation features and malpositioning scenarios increasing the risk of loosening. Finite element models simulating three of the most commonly used TAR devices (BOX®, Mobility® and Salto®) implanted into the tibia/talus and subjected to physiological loads were developed. Mobility and Salto demonstrated the largest micromotion of all tibial and talar components, respectively. Any malpositioning of the implant creating a gap between it and the bone resulted in a considerable increase in micromotion and bone strains. It was concluded that better primary stability can be achieved through fixation nearer to the joint line and/or while relying on more than a single peg. Incomplete seating on the bone may result in considerably elevated implant-bone micromotion and bone strains, thereby increasing the risk for TAR failure.