There is limited literature on the effects of socioeconomic factors on outcomes after total ankle arthroplasty (TAA). In the setting of hip or knee arthroplasty, patients of a lower socioeconomic status demonstrate poorer post-operative satisfaction, longer lengths of stay, and larger functional limitations. It is important to ascertain whether this phenomenon is present in ankle arthritis patients. This is the first study to address the weight of potential socioeconomic factors in affecting various socioeconomic classes, in terms of how they benefit from ankle arthroplasty. This is retrospective cohort study of 447 patients who underwent a TAA. Primary outcomes included pre-operative and final follow-up AAOS pain, AAOS disability, and SF-36 scores. We then used postal codes to determine median household income using Canadian 2015 census data. Incomes were divided into five groups based on equal amounts over the range of incomes. This method has been used to study medical conditions such as COPD and cardiac disease. These income groups were then compared for differences in outcome measures. Statistical analysis was done using unpaired t-test. A total of 447 patients were divided into quintiles by income. From lowest income to highest income, the groups had 54, 207, 86, 64, and 36 patients, respectively. The average time from surgery to final follow up was 85.6 months. Interestingly, we found that patients within the middle household income groups had significantly lower AAOS disability scores compared to the lowest income groups at final follow-up (26.41 vs 35.70, p=0.035). Furthermore, there was a trend towards middle income households and lower post-operative AAOS pain scores compared to the lowest income group (19.57 vs 26.65, p=0.063). There was also a trend toward poorer AAOS disability scores when comparing middle income groups to high income groups post-operatively (26.41 vs 32.27, p=0.058). Pre-operatively, patients within the middle-income group had more pain, compared to the lowest and the highest income groups. No significant differences in SF-36 scores were observed. There were no significant differences seen in middle income groups compared to the highest income group for AAOS pain post-operatively. There were no significant differences found in pre-operative AAOS disability score between income groups. Patients from middle income groups who have undergone TAA demonstrate poorer function and possibly more pain, compared to lower and higher income groups. This suggests that TAA is a viable option for lower socioeconomic groups and should not be a source of discouragement for surgeons. In this circumstance there is no real disparity between the rich and the poor. Further investigation is needed to explore reasons for diminished performance in middle class patients

Restoration of ankle alignment is thought to be critical in total ankle arthroplasty (TAA) outcomes, but previous research is primarily focused on coronal alignment. The purpose of this study was to investigate the sagittal alignment of the talar component. The talar component inclination, measured by the previously-described gamma angle, was hypothesized to be predictive of TAA outcomes. A retrospective review of the Canadian Orthopaedic Foot and Ankle Society (COFAS) database of ankle arthritis was performed on all TAA cases at a single center over a 11-year period utilizing one of two modern implant designs. Cases without postoperative x-rays taken between 6 and 12 weeks were excluded. The gamma angle was measured by two independent orthopaedic surgeons twice each and standard descriptive statistics was done in addition to a survival analysis. The postoperative gamma angles were analyzed against several definitions of TAA failure and patient-reported outcome measures from the COFAS database by an expert biostatistician. 109 TAA cases satisfied inclusion and exclusion criteria. An elevated postoperative gamma angle higher than 22 degrees was associated with talar component subsidence, defined as a change in gamma angle of 5 degrees or more between postoperative and last available followup radiographs. This finding was true when adjusting for age, gender, body mass index (BMI), and inflammatory arthritis status. All measured angles were found to have good inter- and intraobserver reliability. Surgeons should take care to not excessively dorsiflex the talar cuts during TAA surgery. The gamma angle is a simple and reliable radiographic measurement to predict long-term outcomes of TAA and can help surgeons counsel their patients postoperatively

Numerous studies have demonstrated that concomitant lower back pain (LBP) results in worse functional outcomes in patients undergoing surgical treatment for the management of end stage hip and knee arthritis. However, no equivalent studies have analysed the impact of back pain on the outcomes of patients with end stage ankle arthritis. Furthermore, given that two widely accepted surgical options exist in the treatment of ankle arthritis, namely total ankle arthroplasty (TAA) and ankle arthrodesis (AA), it is possible that one surgical technique may be superior in patients with LBP. The aim of this study was to determine the incidence of LBP in people with ankle arthritis, analyse its effect on functional outcomes, and explore whether there was a treatment advantage from either TAA or AA. Prospectively collected data from the Canadian Orthopaedic Foot and Ankle Society (COFAS) database of ankle arthritis was analysed in this study. All patients with ankle arthritis who underwent surgery performed by three fellowship-trained foot and ankle surgeons at a single institution between January 2003 and July 2012 were studied. Patient demographics were collected pre-operatively, including the absence or presence of back pain, and post-operative follow up was performed at 2 and 5 years, evaluating patient-reported functional outcome measures including the Ankle Arthritis Score (AAS) and the 36-item short form survey (SF-36). Using a linear regression model, a multivariate analysis was performed to examine the relationship between back pain, TAAs and AAs. In total, 451 patients were studied. 164 patients (36.4%) presented with concomitant LBP. At presentation, the LBP group had worse AAS scores (54.8 vs 57.8 p. At 2 years postoperatively, the AAS score was the same in both groups (28.9 vs 26.8 p = 0.3), but patients with LBP had worse SF-36 PCS (42.1 vs 36.6 p 0.05) in any of the functional outcome scores at 2 or 5 years post-operatively. The results of this study suggest there is no advantage of TAA over AA in the treatment of ankle arthritis in patients with concomitant lower back pain. Although pre-operative back pain resulted in worse SF-36 outcomes at 2 and 5 years post- operatively, this was not the case for AAS scores

Power production in the terminal stance phase is essential for propelling the body forward during walking and is generated primarily by ankle plantarflexion. Osteoarthritis (OA) of the ankle restricts joint range of motion and is expected to reduce power production at that ankle. This loss of power may be compensated for by unaffected joints on both the ipsilateral and contralateral limbs resulting in overloading of the asymptomatic joints. Total ankle arthroplasty (TAA) has been shown to reduce pain and has the potential to restore range of motion and therefore increase ankle joint power, which could reduce overloading of the unaffected joints and increase walking speed. The purpose of this study was to test the hypothesis that ankle OA causes a loss of power in the affected ankle, compensatory power changes in unaffected lower limb joints, and that TAA will increase ankle power in the repaired ankle and reduce compensatory changes in other joints. One hundred and eighty-three patients (86 men, 97 women with average ages 64.1 and 62.4 years respectively) requiring surgical intervention for ankle OA were prospectively enrolled. Implant selection of either a fixed (INBONE or Salto Talaris) or mobile (STAR) bearing implant was based on surgeon preference. Three-dimensional kinematics and kinetics were collected prior to surgery and one year post-operatively during self-selected speed level walking using an eight-camera motion capture system and a series of force platforms. Subject walking speed and lower extremity joint power during the last third of stance at the ankle, knee, and hip were calculated bilaterally and compared before and after surgical intervention across the entire group and by implant type (fixed vs. mobile), and gender using a series of ANOVAs (JMP SAS, Cary, NC), with statistical significance defined as p < 0 .05. There were no gender differences in age, walking speed, or joint power. All patients increased walking as a result of surgery (0.87 m/s±0.26 prior to surgery and 1.13 m/s±0.24 after surgery, p < 0 .001) and increased total limb power. Normalized to total power (which accounts for changes in speed and distribution of power production across joints), prior to surgery the affected ankle contributed 19%±10% of total power while the unaffected ankle contributed 42%±12% (P < 0 .001). After surgery, the affected ankle increased to 25%±9% of total power and the unaffected ankle decreased to 38%±9% of total (P < 0.001). Other joints showed no significant power changes following surgery. Fixed bearing implants provide greater surgical ankle power improvement (61% versus 29% increase, p < 0 .002). Much of that change was due to the fact that those that received fixed-bearing implants had significantly lower walking speed and power before surgery. Ankle OA reduced ankle power production, which was partially compensated for by the unaffected ankle. TAA increases walking speed and power at the affected ankle while lowering power production on the unaffected side. The modifications in power production could lead to increased physical activity and reduced overloading of asymptomatic joints

Background. Total ankle arthroplasty (TAA) is an alternative to ankle arthrodesis, replacing the degenerated joint with a mechanical motion-preserving alternative. Implant loosening remains a primary cause of TAA revision, and has been associated with wear-mediated osteolysis. Differing implant designs have a major influence on the wear performance of joint replacements. Providing a range of implant sizes allows surgeons a greater intra-operative choice for varying patient anatomy and potential to minimise wear. Minimal pre-clinical testing exists in the literature that investigates the effect of implant size on the wear behaviour. The aim of this study therefore was to investigate the effect of two different implant sizes on the wear performance of a TAA. Materials & Methods. Six ‘medium’ and six ‘extra small’ BOX® (MatOrtho Ltd, UK) TAA implants, of the same conceptual design and polyethylene insert thickness, were tested in a modified 6 station pneumatic knee simulator. 5 million cycles (Mc) of wear simulation were completed for each implant size, under kinematics aiming to replicate an ankle gait cycle (Figure 1) [1]. The simulator used had six degrees of freedom, of which four were controlled. The maximum axial load was 3150N, equivalent to 4.5 times body weight of a 70kg individual. The flexion profile ranged from −15° plantarflexion to 15° dorsiflexion. Rotation about the tibial component ranged from −2.3° of internal rotation to 8° external rotation, and anterior/posterior (AP) displacement ranged from 3.1 mm anterior to −0.9 mm posterior displacement. The lubricant used was 25% bovine serum supplemented with 0.04% sodium azide to prevent bacterial degradation. The wear of the TAA polyethylene inserts were determined gravimetrically after each Mc, with unloaded soak controls used to compensate for the uptake of moisture by the polyethylene. Results. There were no significant differences (P = 0.872) in the mean wear rates (± 95% confidence limits) between the medium (11.00 ± 3.06 mm3/Mc) and extra small (10.64 ± 4.61 mm3/Mc) implant sizes (Figure 2). An observation of insert surfaces showed clear signs of abrasive wear and burnishing (Figure 3). There was evidence of polyethylene transfer and scratching on the tibial components, while talar components displayed fine linear scratching in similar directions for both implant sizes. Conclusions. The wear rates of both implant sizes are comparable to the wear rate (13.30 ± 2.50 mm3/Mc) of a previous wear study, which was conducted on ‘medium-sized’ Corin Zenith TAAs, under the same simulator conditions for 2 Mc [1]. The wear rates for both implant sizes are substantially lower than the wear of four ‘small-sized’ BOX® ankles (18.60 ± 12.80 mm3/Mc) for 2Mc [2]. The considerable difference in wear rates may be due to the lower forces, higher AP and deionised water as the test lubricant [2], which does not replicate the features of the natural synovial fluid and produce tribological artefact. The results from this study suggest that under the same kinematic and kinetic conditions, the wear rates are unaffected by a change in TAA implant size

INTRODUCTION. Proper ligament engagement is an important topic of discussion for total knee arthroplasty; however, its importance to total ankle arthroplasty (TAA) is uncertain. Ligaments are often lengthened or repaired in order to achieve balance in TAA without an understanding of changes in clinical outcomes. Unconstrained designs increase ankle laxity,. 1. but little is known about ligament changes with constrained designs or throughout functional activity. To better understand the importance of ligament engagement, we first investigated the changes in distance between ligament insertions throughout stance with different TAA designs. We hypothesize that the distance between ligaments spanning the ankle joint would increase in specimens following TAA throughout stance. METHODS. A validated method of measuring individual bone kinematics was performed on pilot specimens pre- and post-TAA using a six-degree-of-freedom robotic simulator with extrinsic muscle actuators and motion capture cameras (Figure 1). 2. Reflective markers attached to surgical pins and radiopaque beads were rigidly fixed to the tibia, fibula, talus, calcaneus, and navicular for each specimen. TAAs were performed by a fellowship-trained foot and ankle surgeon on two specimens with separate designs implanted (Cadence & Salto Talaris; Integra LifeSciences; Plainsboro, NJ). Each specimen was CT-scanned after robotic simulations of stance pre- and post-TAA. Specimens were then dissected before a 3D-coordinate measuring device was used to digitize the ligament insertions and beads. Ligament insertions were registered onto the bone geometries within CT images using the digitized beads. Individual bone kinematics measured from motion capture were then used to record the point-to-point distance between centers of the ligament insertions throughout stance. RESULTS. Results from the pilot specimens are presented for the calcaneofibular ligament (CFL) only. The distance between the CFL insertions was larger throughout stance following Cadence implantation (Figure 2A) and was decreased throughout most of stance following Salto Talaris implantation (Figure 2B). The percent change in CFL distance with respect to static standing was also increased with the Cadence implant (Figure 2C) and similar to intact following Salto Talaris implantation (Figure 2D). Ankle motion was similar to intact with the Cadence (Figure 3A) and was decreased with the Salto Talaris (Figure 3B). DISCUSSION. This study suggests that ligament length during stance changes following TAA. The Cadence implant similarly replicated ankle kinematics but CFL length was increased throughout stance which supports our hypothesis. In contrast, the Salto Talaris implant reduced ankle motion and decreased the CFL length. Although the slack length and pre-strain of the CFL were unknown, the distance between insertions from the pilot specimens provides preliminary insight into how ligament mechanics change post-TAA during functional activity. CLINICAL RELEVANCE. Preliminary results of ligament length changes throughout stance may indicate that ligament mechanics change post-TAA and could affect patient outcomes. Changes may be even more pronounced when a soft tissue release or reconstruction is performed to correct malalignment. For any figures or tables, please contact the authors directly

Background. Total ankle arthroplasty (TAA) with the use of third generation implants has demonstrated favorable clinical results and improved survival. However, few studies have compared the different types of implants. The purpose of this study was to perform a retrospective evaluation of patient outcomes and complications by comparing TAA procedures performed with HINTEGRA versus MOBILITY systems. Methods. Fifty-two consecutively enrolled patients (28 men and 24 women; mean age 64.8 years) underwent TAA using HINTEGRA (21 ankles) or MOBILITY (33 ankles) between September 2004 and July 2012. Visual analog scale (VAS) pain scores and the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot scores were determined at each follow-up visit. The radiographs were reviewed to assess component positioning, radiolucency, heterotopic ossification and other factors. Results. The mean follow-up period was 28.3 months in the HINTEGRA group and 32.5 months in the MOBILITY group. VAS decreased from 8.3 to 2.0 for the HINTEGRA group and from 7.9 to 2.7 for the MOBILITY group. The AOFAS score increased from 43.8 to 87.3 for the HINTEGRA group and from 46.6 to 83.7 for the MOBILITY group. Intra- and postoperative malleolar fractures were not noted in the HINTEGRA group, whereas 5 ankles (15.2%) in the MOBILITY group sustained this injury (P=.144). Ankle impingement syndrome was noted in 8 ankles (38.1%) in the HINTEGRA group and 3 (9.1%) in the MOBILITY group (P=.015). However, no significant differences in postoperative osteolysis and neuralgia were noted between the groups. Conclusions. HINTEGRA and MOBILITY implants both exhibited favorable clinical outcome without significant differences. However, in terms of complications, ankle impingement syndrome was significantly more common in the HINTEGRA group, while intraoperative malleolar fracture was observed in only the MOBILITY group

Objectives. Biologic agents (BIO) drastically changed the rheumatoid arthritis (RA) therapy from starting to use biologics at 2003 in Japan. The rate of orthopaedic surgery, especially total joint arthroplasty (TJA) may reflect trends in disease severity, management and health outcomes. Methods. We surveyed the number and rate of orthopaedic surgeries and TJA in RA treatment with BIO in the last decade, so called BIO-era. Results. We had 18,701 cases of orthopaedic surgeries, including 491 rheumatoid surgeries from 2004 to 2013. They contained 382 cases of total joint arthroplasties (78%), including 258 total knee arthroplasty (TKA), 80 total hip arthroplasty (THA), 18 total elbow arthroplasty (TEA), 14 total ankle arthroplasty (TAA), 4 swanson arthroplasty for fingers. The numbers of orthopaedic surgery increased year by year. The rate of rheumatoid surgeries not changed in the last decade (r=0.8, p<0.05, Fig. 1). The numbers of TSA and TEA in 2009–2013 increased twice compared to them in 2004–2008, but TKA and THA not changed. We had 241 RA patients treated by biologics agents from 2003, including 60 rheumatoid surgeries with the biologic therapy. Over half of rheumatoid surgeries were TJA (37 cases; 61%), including 26 cases for lower joint; 11 cases for upper joint. The rate of upper TJA more increased than that of lower joint in the RA patients with BIO in this decade. Conclusion. TJA for upper joint that improve the quality of life may increase in the RA patients with biologic therapy, because their disease activity and attitudes have changed year by year in this BIO-era

Purpose. The goal of Total Ankle Arthroplasty (TAA) is to relieve pain and restore healthy function of the intact ankle. Restoring intact ankle kinematics is an important step in restoring normal function to the joint. Previous robotic laxity testing and functional activity simulation showed the intact and implanted motion of the tibia relative to the calcaneus is similar. However there is limited data on the tibiotalar joint in either the intact or implanted state. This current study compares modern anatomically designed TAA to intact tibiotalar motion. Method. A robotic testing system including a 6 DOF load cell (AMTI, Waltham, MA) was used to evaluate a simulated functional activity before and after implantation of a modern anatomically designed TAA (Figure 1). An experienced foot and ankle surgeon performed TAA on five fresh-frozen cadaveric specimens. The specimen tibia and fibula were potted and affixed to the robot arm (KUKA Robotics Inc., Augsburg, Germany) while the calcaneus was secured to a fixed pedestal (Figure 1). Passive reflective motion capture arrays were fixed to the tibia and talus and a portable coordinate measuring machine (Hexagon Metrology Group, Stockholm, Sweden) established the location of the markers relative to anatomical landmarks palpated on the tibia. A four camera motion capture system (The Motion Monitor, Innovative Sports Training, Chicago, IL) recorded the movement of the tibia and talus. The tibia was rotated from 30 degrees plantar flexion to 15 degrees dorsiflexion to simulate motions during the stance phase of gait. At each flexion angle the robot found the orientation which zeroed all forces and torques except compressive force, which was either 44N or 200N. Results. Preliminary data indicates the tibiotalar motion of the TAA is similar to the intact ankle. The pattern and magnitude of tibiotalar translations and rotations are similar between the intact and implanted states for both 44N and 200N compressive loads (Figure 2). The most variation occurs with internal-external rotation. Increased translation especially in the anterior-posterior directions was observed in plantarflexion while the mediolateral translation remained relatively centered moving less than a millimeter. The intact talus with respect to the calcaneus had less than 3 degrees of rotation over the whole arc of ankle flexion (Figure 3). The angular motion of the implanted talus was similar in pattern to the intact talus, however there were offsets in all three angular directions which changed depending on the loading (Figure 3). This indicates that most of the motion that occurs between the intact tibial calcaneal complex occurs in the tibiotalar joint. Conclusion. Although more investigation is required, this study adds to the limited available tibiotalar kinematic data. This current study suggests the anatomical TAA design allows the tibiotalar joint to behave in similar way to the intact tibiotalar joint. Restoring intact kinematics is an important step in restoring normal function to the joint. For figures/tables, please contact authors directly.

When total ankle arthroplasty (TAA) is performed, although tibial osteotomy is instructed to be perpendicular to long axis of tibia, there is no established index for the talar bone corrective osteotomy. Then, we have been deciding the correction angle at the plan for adjustment of the loading axis through whole lower extremities. We studied 17 TAA cases with rheumatoid arthritis (RA). X-ray picture of hip to calcaneus view (hip joint to tip of the calcaneus) defined to show more approximated loading axis has been referred for the preoperative planning. Furthermore, the data of correction angle has been reflected to pre-designed custom-made surgical guide. If soft tissue balance was not acceptable, malleolar sliding osteotomy was added. The distance between the centre of ankle joint and the axis (preD) was measured (mm) preoperatively, and the distance between the centre of prosthesis and the axis (postD) was measured postoperatively. Next, the tilting angle between tibial and talar components (defined as the index of prosthesis edge loading) were measured with X-rays during standing. Tibio Calcaneal (TC) angle was also measured pre and postoperatively. TC angle was significantly improved from 8.3±6.0° to 3.5±3.6° postoperatively (P=0.028). PreD was 12.9±9.6mm, and that was significantly improved to 4.8±6.3mm (postD) (P=0.006). Within 17 cases, 8 cases showed 0–1mm of postD, 4 cases showed 1–5mm of postD, remaining 5 cases concomitant subtalar fusion with severe valgus and varus hindfoot deformity showed over 8mm of postD. All of the 12 cases showing within 5mm of postD indicated within 13mm of preD. The tilting angle between components was 0.17±0.37° postoperatively. Taken together, pre-designed corrective talar osteotomy based on preoperative planning using hip to calcaneus view was useful to adjust the mechanical axis for replaced ankle joint in RA cases. Furthermore, after surgery, the hip to calcaneus view was useful to evaluate post-operative mechanical axis of whole lower extremities

Introduction. Ankle arthrodesis is a common treatment for destroyed ankle arthrosis with sacrificing the range of motion. On the other hand, total ankle arthroplasty (TAA) is an operation that should develop as a method keeping or improving range of motion (ROM); however, loosening and sinking of the implant have been reported in especially constrained designs of the implant. The concept of FINE TAA is the mobile bearing system (Nakashima Medical Co., Ltd, Okayama Japan) that can reduce stress concentration to implants. The purpose of this study is to evaluate the short-term results of FINE TAA. Objectives and Methods. We performed FINE TAA for osteoarthritis (OA) (2 ankles of 2 patients) and rheumatoid arthritis (RA) (4 ankles of 3 patients). All patients were female. The mean age of the patients was 71.4 years old at the operation. The mean follow-up period was 32.6 (range, 18–55) months. All patients were assessed for Japan Orthopedic Association (JOA) score and ROM in plantar flexion and dorsiflexion at the point of pre-operation and final follow-up. We evaluated radiolucent line, subsidence, and alignment of implants at the latest follow-up. Results. JOA score improved from 34.8 to 72.2 on average. ROM improved from 4.0 ± 5.5 º to 7.0 ± 4.5 º on average in plantar flexion and from 21.0 ± 17.0 º to 31.0 ± 16.0 º in dorsiflexion. One case underwent an ankle arthrodesis because of the implant loosening. This failed case was very obese (70 kg of body weight, 31.0 of Body Mass Index) and her activity was relatively high. One ankle showed radiolucent line around the components with no symptoms. The alignment of implants was slightly varus and anteversion (the mean values of alpha angle was 88.0 ± 1.2º, beta angle was 84.0 ± 9.2º, and gamma angle was 2.1 ± 0.2º). Discussion. The ankle joint is highly loaded up to five times body weight on small surface of contact area during walking. Therefore, the poor results have been published after TAA with using fixed-bearing 2-component prostheses compared to ankle arthrodesis. On the other hand, FINE TAA was designed as 3-component mobile bearing system that can reduce stress concentration compared to conventional TAA. We experienced implant failure in one obese case but short-term results of other cases were acceptable. Good clinical results can be expected with FINE TAA except for the obese case. We should pay careful attention to the surgical indication. Conclusion. Our short term results of FINE TAA were acceptable except for one obese case. We should evaluate further mid- and long- clinical results

Introduction and aims. Recently many implants for ankle arthroplasty have been developed around the world, and especially some mobile bearing, three-component implants have good results. Nevertheless, at our institution fixed two-component, semi-constrained alumina ceramic total ankle arthroplasty (TAA) with TNK Ankle had been performed since 1991 and led to improved outcomes. We report clinical results and in vivo kinematic analyses for TNK Ankle. Method. Between 1991 and 2006, total ankle arthroplasties with TNK Ankle were performed with 102 patients (106 ankles) with osteoarthritis at our institution. There were 91 women and 11 men. The mean age was 69 years and mean follow-up was 5.4 years. These cases were evaluated clinically and radiographically. Besides in vivo kinematics, in TNK Ankle was analysed using 3D-2D model registration technique with fluoroscopic images. Between 2007 and 2008, prospectively ten TAA cases examined with fluoroscopy at postoperative one year. Results. In clinical results, excellent were 48 cases, good were 31 cases, fair were 10 cases, poor were nine cases, and death and loss to follow-up were 10 cases. Reoperations are performed on eight cases, one was arthrodesis, seven were talar component revision or talar revision with ceramic whole talus prosthesis. TNK Ankle have the rough surfaces by beadworks, and added surface treatment with hydroxyapatite granules, calcium phosphate paste or tissue engineered mesenchymal cells. Recently, only talar components were fixed with bone cement. Loosening has been more frequent in talar than tibial, whereas no reoperation was on cemented talar component cases. According to 3D-2D model registration, both components rotated a little each other and the contact region between both components variously sifted during weight bearing flexion of ankle. It was supposed that replaced position and angle of components concerned with the contact region. Conclusions. TAA with TNK Ankle have led to better results with improvement for surface treatments. Kinematics of ankle prostheses was derived by 3D-2D model registration, more appropriate position and angle to replace

Purpose. The failure rate of total ankle arthroplasty (TAA) in rheumatoid patients may be higher than in osteoarthritis patients due to the medications used to treat rheumatoid arthritis and the comorbidities associated with this disease. The purpose of this study was to prospectively look at the intermediate-term outcomes of TAA in patients with rheumatoid arthritis and to compare the results to a matched cohort of patients with ankle osteoarthritis undergoing TAA. Method. This study is a prospective, multicentre comparison study of patients two to eight years post-TAA. A cohort of 57 patients with rheumatoid arthritis was identified from the prospective national database of TAAs (RA group). Matched controls were identified in the database using age, type of prosthesis, and follow-up time as matching criteria (OA group). The following data was collected: demographic information, previous and additional surgeries at the time of TAA and major and minor complications including revisions. Generic and disease specific, validated outcome scores collected include the Short-Form 36 (SF36) and Ankle Osteoarthritis Score (AOS). Results. Each group consisted of 42 female and 15 male patients with an average follow-up of four years. The two groups were similar with an average age of 59.55 years (33–82) in the RA group and 58.13 years (36–85) in the osteoarthritis group and an average BMI of 25.77 kg/m2 in the RA group and 27.70 kg/m2 in the OA group. Preoperative AOS scores were similar in both groups: 64.42 for pain and 72.59 for disability in the RA group and 58.39 for pain and 72.37 for disability in the OA group. There was a significant improvement at latest follow-up: 16.64 for pain and 27.03 for disability in the RA group and 11.75 for pain and 22.66 for disability in the OA group. The OA group had a greater improvement in the SF-36 physical component score (29.97 to 41.29 versus 26.88 to 34.82 in the RA group) whereas the RA group had a greater improvement in the mental component score (49.71 to 56.90 versus 48.99 to 52.02 in the OA group). There was a higher rate of additional surgeries, predominantly hindfoot fusions, in the RA group than the OA group (33 versus 13). Revision rates were similar between the two groups with two revisions in the RA group and three in the OA group. There were no major wound complications in the OA group and two in the RA group. Conclusion. Total ankle arthroplasty is a good option for patients with rheumatoid arthritis. A greater number of additional surgeries were required to balance the foot and support the ankle replacement in the rheumatoid patients than in the osteoarthritis patients. Both groups showed similar improvement in a generic quality of life outcome measure (SF36) and a disease specific functional outcome measure (AOS). Revision rates were similar between the groups; however, the patients with rheumatoid arthritis had a higher rate of wound complications

Purpose. The purpose of this study was to assess the clinical outcomes over two years for total ankle arthroplasty (TAA) using Short Form-36, Foot Function Index and Ankle Osteoarthritis Scores, and to compare these with radiostereometric analysis longitudinal migration and inducible displacement results. Method. Twenty patients undergoing TAA implanting the Mobility Total Ankle System (DePuy, Warsaw IN) were assessed at 3mth, 6mth, 1yr and 2yr followup periods by model-based radiostereometric analysis, MBRSA 3.2 (Medis specials, Leiden, The Netherlands), for longitudinal migration (LM) and inducible displacement (ID). The same subjects completed clinical outcome questionnaires at these followup periods for Short Form-36 (SF-36; Physical Component Scores (PCS) and Mental Component Scores (MCS)), Foot Function Index (FFI) and Ankle Osteoarthritis Scores (AOS). Descriptive statistics and Pearson correlations (alpha = 0.05) were calculated using Minitab 15 (Minitab Inc., State College PA). Results. For the PCS of SF-36, FFI and AOS the scores were significantly different at 2 year followup when compared to preoperative values; p = 0.005, 0.0002 and 0.0003 respectively. The PCS on average increased with respect to pre-operative by 10 points (SD = +/−13), while the MCS on average did not change with respect to pre-operative (SD = +/− 12). The FFI on average decreased by 25 points with respect to pre-operative (SD = +/− 18) and AOS on average decreased by 23 points with respect to pre-operative (SD = +/− 21). There were several correlations for the 2 yr results: AOS to FFI of r = 0.92 (p = 0.000); AOS to PCS of r = −0.67 (p = 0.005); AOS to MCS of r = −0.51 (p = 0.046); AOS to talar component ID of r = 0.70 (p = 0.004); AOS to the talar component LM of r = 0.62 (p = 0.046). PCS related better than MCS to both AOS and FFI. The LM of the talar component and tibial component were not significantly correlated, r = 0.18 (p = 0.62). The ID of the talar component and tibial component were not significantly correlated, r = 0.48 (p = 0.07). The latter result may be too underpowered to determine a significant difference; due to the small sample size. Conclusion. The outcome scores of AOS, FFI, SF-36 (PCS) and SF-36 (MCS) were correlated to each other. The strongest outcome score relationships were AOS to FFI, followed by AOS to SF-36 (PCS). The correlation of AOS to the talar component LM and ID suggests that the implant performance may be related to the stability of the talar component

Purpose. To compare Radiostereometric Analysis (RSA) and subjective outcomes of Total Knee Arthroplasty (TKA) and Total Ankle Arthroplasty (TAA). Method. Twenty-five patients were recruited to receive TKA (Zimmer, NexGen LPS Trabecular Metal Monoblock) and 20 patients were recruited to receive TAA (DePuy, Mobility). The tibial component of the TKA and the tibial component of the TAA were followed for two years with RSA with exams postoperatively at six, 12 and 24 months. At two years, inducible displacement RSA at the knee and ankle was also performed. RSA outcomes measured were translations in the anterior-posterior, medial-lateral and distal-proximal directions of both implants. SF-36 outcome questionnaires were completed preoperatively and at each RSA follow-up with the outcome being the mental component score (MCS) and physical component score (PCS). Analysis of variance statistical testing was used to compare RSA outcomes and subjective outcomes. Results. Preoperatively there were no differences in age, BMI, SF-36 MCS or SF-36 PCS between the TKA and TAA patients. At six, 12 and 24 months the TKA group had significantly higher SF-36 PCS scores (p=0.006, p=0.002 and p=0.004 respectively. There were no differences at any time point in SF-36 MCS. Longitudinal RSA results showed that the TAA tibial component moved further into the bone at all follow-ups (p=0.000 at all time points). The TAA also migrated more anteriorly compared with the TKA, although this only became significant at 12 and 24 months (p=0.013, p=0.05). RSA inducible displacement showed that the TAA had greater inducible displacement into the bone than the TKA (p=0.015). Conclusion. The subjective data show that TAA and TKA both improve the symptoms of patients. However, the subjective results of the TAA have not achieved the high standard set by TKA. The RSA data suggest that the TAA is stabilizing within the bone. However, the higher longitudinal migrations and inducible displacements seen in the TAA suggest that the interface may not be as robust as in the TKA. This may partially be explained by the much smaller surface area available to distribute the loads at the ankle resulting in higher stresses and migrations. The 3rd generation of TAA has recently been reintroduced as a treatment option for severe arthritis of the ankle. Previous generations of TAA have been unsuccessful with high failure rates. It is unclear if the current generation of TAA will be more successful in the long term. Comparisons between these arthroplasty procedures with high precision measures such as RSA can provide insight into whether TAA has achieved the same level of success as TKA. Although there are no comparable migration thresholds for TAA as TKA, this study suggests that TAA may not achieve as robust an interface with the bone as TKA. The results of the current generation of TAA are promising. However, TAA still has room for improvement to achieve the same outstanding results as TKA

Purpose. The purpose of this study was to assess the biomechanical stability of the a total ankle arthroplasty system using longitudinal migration (LM) and inducible displacement (ID) measures. This study is the first study of its kind to assess total ankle arthroplasty (TAA) implant micromotion using model-based radiostereometric analysis (MBRSA). Method. Twenty patients underwent TAA that implanted the Mobility(TM) (DePuy, Warsaw IN). The mean (SD) age was 60.4 (12.5) and BMI was 29.1 (2.8) kg/m. 2. One surgeon performed all surgeries. All patients included in this study had given informed consent. Capital Health Research Ethics Board had approved this study. Uniplanar medial-lateral RSA X-ray exams were taken postop (double exam), at six wk, three mth, six mth, one yr and two yr followup times using a supine, unloaded position. Standing medial-lateral exams were taken at three mth, six mth, one yr and two yr followup intervals. LM and ID micromotions were assessed using Model-based RSA 3.2 software (Medis specials, Leiden, The Netherlands). Implant micromotions (x, y, z, Rx, Ry, Rz, MTPM) were determined and assessed for each subject using model-based pose estimation, and the implant-based coordinate system. The Elementary Geometric Shapes module from the Model-based RSA 3.2 software was used to assess the micromotion of the tibial component spherical tip due to implant symmetry. Results. The median (range) maximum total point motion (MTPM) for the implants at 2 year followup were 1.23 mm (0.39–1.95 mm) for the talar implant and 0.96 mm (0.17–2.28 mm) for the spherical tip of the tibia implant. Generally for each subject and implant component, the slopes of the migration curves decreased over time. The talar and tibial implants mean LM showed initial subsidence in the y-direction (migration into the bone) followed by stabilization patterns at one year followup. The median (range) of two year MTPM ID for the talar component was 0.39 (0.27–1.06) mm. At the one year and two year followup times the ID were almost all below the detection limit of 0.85 mm. The highest measured displacement for any one talar component at either of these times was 1.06 mm. Hence, the implant was displaced at least 0.21 mm under loading. The median (range) of one year and two year MTPM ID for the tibial component spherical tip was 0.08 (0.03–0.19) mm. The tibial component spherical tip demonstrates no ID in terms of MTPM greater than the 0.22 mm detection limit. Conclusion. The implant subsides directly into the bone in the line of primary loading during standing or walking. For most of the patients the two year LM for the Mobility(TM) demonstrates a typical subsidence-stabilization behaviour seen in many RSA studies of orthopaedic implants. Based on the results of this study the Mobility(TM) components show no measurable ID. This is the first study of its kind internationally for total ankle arthroplasty and offers novel insight into the need for prosthetic design change