Mobile-bearing Total Ankle Replacement Research Articles

RANDOMIZED PROSPECTIVE TRIAL COMPARING THE SALTO TALARIS FIXED-BEARING AND SALTO MOBILE-BEARING TOTAL ANKLE ARTHROPLASTY

IntroductionComparative studies examining Fixed-Bearing (FB) and Mobile-Bearing (MB) Total Ankle Replacement (TAR) designs have demonstrated similar results and successful long-term outcomes for both. To date there has been no study directly comparing FB and MB designs of the same prosthesis. We present the first prospective randomised trial comparing patient satisfaction, functional outcomes and radiographic results of the Salto Talaris Fixed-Bearing and the Salto Mobile-Bearing Total Ankle Replacement in the treatment of end-stage ankle arthritis.MethodsA total of 108 adult patients with end-stage ankle arthritis were enrolled in the study between November 2014 and October 2021 with similar demographic comparison. Prospective patient-reported outcomes and standardised weightbearing ankle radiographs were performed preoperatively, at 6 weeks, 6 months and 12 months post-operatively, followed by yearly intervals. All surgeries were performed by a single non-design orthopaedic foot and ankle specialist with experience in over 200 Salto and Salto Talaris TAR prior to the study. Radiographs were examined independently by two clinicians. Complete patient data and radiographs were available for 103 patients with an average follow up of 2 years.ResultsBoth groups demonstrated statistically significant improvement from preoperative evaluation to most recent follow up with no statistically significant difference between the two groups in all outcome measures. Radiographic incidence of subchondral cyst formation was 8.9% and 38.2% for FB and MB, respectively. Talar subsidence occurred in 2.2% and 5.5% of FB and MB, respectively.DiscussionOur study demonstrates a higher than previously reported rate of cyst formation in the MB TAR and comparatively higher talar subsidence in the MB TAR vs FB however this did not correlate with clinical outcome measures which were favourable for both groups.ConclusionFixed-Bearing and Mobile-Bearing Total Ankle Replacement demonstrate comparable favourable

The 10-Year Patient-Reported and Clinical Outcomes of a Series of 156 Mobile-Bearing Total Ankle Replacements and the Effects of Patient Age

Category: Ankle Arthritis; Ankle Introduction/Purpose: Total Ankle Replacement (TAR) is an established treatment option for end-stage ankle arthritis. We analysed at minimum, 10-year patient-reported and clinical outcomes of 156 TARs from a single centre. We specifically compared outcomes between patients under 60 and over 60 at time of surgery. Methods: Data was collected retrospectively from our departmental patient database. It included all patients who underwent a TAR by a single surgeon between 2006 and 2010 and patients were divided into those under 60 and those over 60 at the time of surgery. Patient reported outcomes (PROMs), including WOMAC, SF-36 and patient satisfaction scores and complications were analysed preoperatively and at one, two, five and over 10 years postoperatively. Results: There were 156 patients included in this analysis, 61 were under 60 (mean age 50.29) and 95 were over 60 (mean age 69.12). A total of 12 patients had revision surgery, (nine in the under 60 group) and 52 patients were deceased at the time of analysis (10 in the under 60 group). At one year the over 60 group had less pain and better functional scores (p=0.02, p=0.017). At two, five and ten years there was no statistical difference in pain and function between groups. At two years the over 60s reported less stiffness and quicker return to activities of daily living (p=0.007, p=0.001). However, at five and 10 years there was no statistical difference in any domain. Conclusion: This study demonstrates that age does not correlate with a significant difference in pain or functional outcomes in patients who have TAR, at over 10 years follow up. The higher revision rates in the younger group may correlate with higher functional demand and lower mortality rate.

Analysis of Polyethylene-Related Revisions After Total Ankle Replacements Reported in US Food and Drug Administration Medical Device Adverse Event Database.

There are 2 general types of total ankle replacement (TAR) designs with respect to the polyethylene insert, mobile-bearing (MB) and fixed-bearing (FB) TARs. The aim of this study is to compare polyethylene-related adverse events (AEs), particularly revisions, reported for MB TARs and FB TARs using the US Food and Drug Administration's (FDA's) Manufacturer and User Facility Device Experience (MAUDE) database. A text mining method was applied to the medical device reporting (MDR) in the MAUDE database from 1991 to 2020, followed by manual reviews to identify, characterize, and describe all polyethylene-related AEs, including revisions, reported for MB and FB TARs. We found 1841 MDRs for MB (STAR Ankle only) and 1273 MDRs for 40+ FB TARs approved/cleared by the FDA. For the MB design, 33% (606/1841) of the AEs reported related to the polyethylene component, compared to 24% (291/1273) of the AEs reported for FB designs. Polyethylene fractures were reported in 11.3% (208/1841) for the MB designs compared to 0.2% (2/1273) for the FB designs. Half of the polyethylene-related revisions occurred within an average of 4.1 years after implantation for the MB design compared within an average of 5.2 years for FB designs. Analysis of this database revealed a higher proportion of reported polyethylene fractures and greater need for earlier revisions for polyethylene-related issues with use of the primary MB design in the database as compared with FB TAR designs. Further study of device-related complications with more recent designs for both MB and FB ankle replacement components are needed to improve the outcomes of total ankle replacement. Level III, retrospective comparative study.

Mobile-Bearing Total Ankle Replacement In Vivo Kinematic Assessment: A Prospective Study Protocol.

Total ankle prosthesis as a surgical solution in the case of end-stage osteoarthritis has seen a considerable increase in the last two decades. This study protocol arises from the need to understand the in vivo kinematics of mobile-bearing, flat tibial component total ankle replacement, evaluating the real range of motion and the reciprocal relationships between the components during normal motor tasks through the use of model-based radio-stereometric analysis (MB-RSA). In addition, pre- and post-operative evaluation of walking kinematics with inertial motion sensors, proprioception through a dedicated workstation, and clinical outcomes are discussed. We expect that based on our study protocol researchers will be able to improve future prosthetic designs and validate the setup of MB-RSA, as well as to understand “how an ankle prosthesis moves” once implanted in the patient.

Syndesmotic Overload in 3-Component Total Ankle Replacement

Category:Ankle; Ankle Arthritis; OtherIntroduction/Purpose:Mobile-bearing total ankle replacement (TAR) potentially enables motion at the tibial implant- polyethylene insert (PI) interface. Such additional freedom of movement may overload periarticular ligaments and subsequently result in coronal translation of the talus. The aim of this study was to assess whether syndesmotic overload affects clinical and radiographic outcomes following mobile-bearing TAR and whether tibiofibular fusion is an effective treatment option.Methods:Thirty-one patients who underwent revision surgery for syndesmotic overload after mobile-bearing TAR were retrospectively analyzed. Clinical and radiographic outcome, including computed tomography scans, were assessed before and after index TAR, preoperatively to revision surgery, and at the last follow-up after revision surgery. Additionally, available computed tomography scans were analyzed.Results:Ankles with lateral talar translation prior to revision surgery were about 10 times more likely to have valgus tibial implant position (P =.003). A wide tibiofibular distance at the level of the syndesmosis after index TAR was associated with an increased hindfoot moment arm at revision surgery (P =.025). Decrease of PI height at revision surgery and a PI fracture were evident in 10 (32%) and 4 (13%) cases, respectively. Talar cyst formation at revision surgery was evident in 12 (39%) cases. Tibiofibular fusion was effective in restoring function of the replaced ankle and providing pain relief.Conclusion:Syndesmotic overload impaired clinical and radiographic outcomes after mobile-bearing TAR. Proper implant positioning and additional realignment procedures may prevent overload of periarticular soft tissue structures after mobile-bearing TAR.

Effect of Packaging on Polyethylene Fractures, Implant Survivorship and Cyst Formation in Mobile Bearing Total Ankle Replacements

Category:Ankle Arthritis; AnkleIntroduction/Purpose:The Scandinavian Total Ankle Replacement (STAR) is the most widely used mobile bearing total ankle arthroplasty (TAA) in the US. The polyethylene component is ultrahigh molecular weight polyethylene and is designed to articulate with both the tibial and talar component. Initial data on the STAR in the US reported polyethylene fracture rates of greater than 10% as well as a concern for cyst formation due to osteolysis. The manufacturer changed the packaging to foil to prevent potential oxidation of the polyethylene, which could predispose the polyethylene to failure. The objective of the study was to evaluate a cohort of patients with STAR performed before and after converting to foil packaging to determine if there is a difference in polyethylene survivorship and cyst formation.Methods:All primary TARs performed by the senior author from 2010-2017 were reviewed. Patients with a minimum 48 month follow up were included in the study. The two groups were stratified by those performed prior to August 2014 (PRE) and those performed after August 2014 (POST). Preoperative and most recent postoperative alignment was determined on weight bearing radiographs. The outcomes included polyethylene fractures and cyst formation in the two groups. Cysts were defined as those measuring greater than 1cm2 on plain radiographs. Patients were recommended to have surgery if cyst volume was greater than 2cm2. Chi-squared tests were used to detect significant differences in the rate of cyst formation between the two groups. Paired t- tests were used to determine difference in preoperative versus postoperative alignment, follow up length, and polyethylene component thickness and patient age at time of procedure between the two groups.Results:The PRE group had 35 patients with an average follow up of 75 months (range 48-118). The POST group had 15 patients with average follow up 55 months (range 48-60). There was no difference in preoperative versus postoperative radiographic alignment between the groups (p>0.05). Cysts were present in 9 (26%) patients in the PRE group versus 4 patients (26%) in the POST group. Nine patients (26%) needed a second surgery due to cyst formation in the PRE group versus two (16%) in the POST group (p>0.05). Four patients (11%) had a fracture of the polyethylene in the PRE group with an average thickness of 6.7mm (range 6-9) and 77 months (range 68-84) versus zero in the POST group. The average time to polyethylene exchange for cyst(s) or polyethylene fracture was 58.3 months.Conclusion:This study suggests that changes in packaging to limit oxidation of the polyethylene from plastic to foil did not appear to represent a difference in periprosthetic cyst formation. However, there was a trend for additional surgery related to periprosthetic cysts and increased risk for polyethylene fracture in the PRE group. These results could suggest the potential for oxidation changes that alter the wear characteristics and fragility of the polyethylene component. Confounding factors could include postoperative time and component thickness. Further investigation and longer follow-up will be needed to further delineate oxygenation impacts on TAA polyethylene components.

The motion between components in a mobile-bearing total ankle replacement measured by cone-beam CT scanning

BackgroundTo measure the motion of polyethylene insert and implant components of mobile-bearing total ankle replacement (TAR) by cone-beam CT scanning. Methods10 TAR patients with high amount of clinical motion after the CCI implant (Ceramic Coated Implant; Wright Medical Technology, Arlington, TN, USA) with average age at operation 64,3 years (range 47–84) and average clinical total range of motion 42 degrees (range 35–55) were included. ResultsThe average total range of motion between the insert and the tibial component was 0.8mm (range 0–2) in the coronal plane, and 2.9mm (range 1–6) in the sagittal plane. There was wide variation in the axial rotation measurements between the components. ConclusionWe found measurable motion between the mobile-bearing insert and the tibial component in all planes. The relevance of this motion to the function and long-term survival of the TAR remains to be determined.

Was Mark Reiley Right? A Outcome Analysis of Intramedullary Versus Extramedullaryalignment Referencing for Total Ankle Replacement

Category:Ankle Arthritis; AnkleIntroduction/Purpose:The purpose of this study was to report on the radiographic outcomes, clinical outcomes, and implant survivorship following extramedullary-referenced (EMr) versus intramedullary-referenced (IMr) total ankle replacement (TAR).Methods:From May 2007 to February 2018, a consecutive series of patients with end-stage tibiotalar osteoarthritis undergoing TAR for primary arthritis, post-traumatic arthritis, and inflammatory arthritis was enrolled in this study. Analyses were performed comparing IMr versus EMr components for patient-reported outcomes data, pre and postoperative radiographic ankle alignment, concomitant procedures, and complications. Kaplan-Meier survivorship analyses served to determine implant reoperation and revision surgery. Data was prospectively collected and retrospectively analyzed. A p-value of < 0.05 was considered significant for all statistical analyses.Results:A total of 340 TARs were included with 105 IMr TAR and 235 EMr TAR. The mean follow-up was 5.3 years ( +- 2.5, range 2-12). The absolute value for preoperative coronal alignment was significantly greater for IMr compared to EMr TAR (13.0 vs 6.4 degrees; p < 0.0001), but both groups achieved near neutral alignment postoperatively (1.4 vs 1.5 degrees; p=0.6655). The odds of having a concomitant procedure was 2.7 times higher in patients with an IMr TAR (OR 2.7, CI 1.7-4.4; p-value <0.0001). There were similar improvements in patient-reported outcome scores at one year and final follow up (all p > 0.05). The 5-year implant survivorship was 98.6.% for IMr versus 97.5% for EMr at final follow-up.Conclusion:Despite the IMr TAR group having more severe preoperative coronal and sagittal malalignment, both IMr and EMr TAR components had comparable postoperative alignment, patient-reported outcome scores, and complications. Among the patients with preoperative varus, valgus, or anterior distal tibial slope, the IMr patients achieved greater correction than the EMr patients. Although the 5-year implant survivorship was similar between the two cohorts with 98.6% survival for IMr TAR and 97.5% for EMr TAR, impending failures were greater for the mobile-bearing EMr TAR.

Syndesmotic Overload in 3-Component Total Ankle Replacement.

Mobile-bearing total ankle replacement (TAR) potentially enables motion at the tibial implant-polyethylene insert (PI) interface. Such additional freedom of movement may overload periarticular ligaments and subsequently result in coronal translation of the talus. The aim of this study was to assess whether syndesmotic overload affects clinical and radiographic outcomes following mobile-bearing TAR and whether tibiofibular fusion is an effective treatment option. Thirty-one patients who underwent revision surgery for syndesmotic overload after mobile-bearing TAR were retrospectively analyzed. Clinical and radiographic outcomes were assessed before and after index TAR, preoperatively to revision surgery, and at the last follow-up after revision surgery. Computed tomography scans were also analyzed. Ankles with lateral talar translation prior to revision surgery were about 10 times more likely to have valgus tibial implant position (P = .003). A wide tibiofibular distance at the level of the syndesmosis after index TAR was associated with an increased hindfoot moment arm at revision surgery (P = .025). Decrease of PI height at revision surgery and a PI fracture were evident in 10 (32%) and 4 (13%) cases, respectively. Talar cyst formation at revision surgery was evident in 12 (39%) cases. Tibiofibular fusion was effective in restoring function of the replaced ankle and providing pain relief. Syndesmotic overload impaired clinical and radiographic outcomes after mobile-bearing TAR. Proper implant positioning and additional realignment procedures may prevent overload of periarticular soft tissue structures after mobile-bearing TAR. Level IV, retrospective case series.

The Effect of Exchanging a Mobile-Bearing into a Fixed-Bearing Total Ankle Replacement System in Patients with Coronal Plane Instability

Category:Ankle, Ankle ArthritisIntroduction/Purpose:The interface between the polyethylene (PE) inlay and the tibial component in mobile-bearing total ankle replacement (TAR) systems may allow the talus to seek its position according to the individual anatomy. However, chronic overload and/or incompetence of soft tissue may allow medial and/ or lateral translation of the talar component over time. This typically results in medial and/ or lateral gutter pain as well as pain along the syndesmosis. The purpose of this study was to assess the effect of tibial component exchange and conversion from a mobile-bearing into a fixed-bearing TAR system in patients with coronal plane instabilities TAR.Methods:A consecutive series of 30 ankles (29 patients; age 65.6 [48.9 – 86.1]; male, 23; female, 7) with coronal plane instabilities underwent revision TAR with exchange of a mobile-bearing (Hintermann Series, H3) into a fixed-bearing (Hintermann Series, H2) TAR system. Patients presented with a medial (n = 12) or lateral (n = 9) translation of the talar component, or a varus (n = 4) or valgus (n = 5) instability with subsequent tilt of the talar component. After removing the tibial component and PE inlay, a tibial osteotomy was performed and 1 to 2 mm of the distal tibia removed. A tibial component of the H2 total ankle system was inserted. While holding the foot in neutral position, the PE inlay was locked to the tibial component in the appropriate position. Functional outcome and pain were recorded to evaluate clinical outcome, and standard radiographs under fluoroscopy were taken for radiographic assessment.Results:All but one of the remaining 28 patient showed significant improvement of pain (P<0.05). Preoperative gutter pain disappeared completely in 20 ankles (71.4%), and partially in 8 ankles (18.6%). The AOFAS Hindfoot Score improved from 54.3 (range, 21 to 90) preoperatively to 74.0 (range, 48 to 92) at latest follow-up (P<0.05). Radiographic assessment showed firm osteointegration in all patients with the talar component centralized in the ankle mortise, and a free medial and lateral gutter without tilt of talar component (Figure 1). One patient with bilateral revision TAR was affected by a bilateral deep infection of both ankles 9 months after surgery subsequent to a severe pneumonia. Both ankles were removed and replaced by a cement spacer.Conclusion:Converting a mobile-bearing into a fixed-bearing TAR system has shown to be effective in the treatment of patients with coronal plane instabilities following TAR. Allowing the PE inlay to adapt its position according to the talar component before definitive fixation to the tibial component of the H2 series, saved having to replace the talar component. Future long-term studies however are needed to identify significant benefits of this novel total ankle concept in primary and revision TAR.

The Effect of Sagittal and Coronal Balance on Patient-Reported Outcomes Following Mobile-Bearing Total Ankle Replacement

Total ankle replacement (TAR) is an established technique for the treatment of end-stage ankle arthritis. The aims of TAR include pain relief, preservation of tibiotalar movement, protection of adjacent joints, and restoration of anatomic alignment in the coronal and sagittal planes. The aims of this study were to determine the relative importance of pre- and post-TAR coronal and sagittal balance on postoperative patient-reported outcome measures (PROMs). A total of 101 ankles in 99 patients were included in this retrospective cohort study. Patients were scored preoperatively and at a minimum of 2 years by using the Foot and Ankle Outcome Score (FAOS), the American Orthopedic Foot and Ankle Society (AOFAS) hindfoot-ankle score, the Short Form-36 measures, and a set of radiographic measurements to define the sagittal and coronal alignment. There was no significant difference between the groups regarding the anterior or posterior translation of the talus preoperatively. There were no statistically significant correlations between any preoperative measure and any domain of the PROM data. Significant correlations were observed between postoperative medial distal tibial angle and the function domain of the FAOS and the AOFAS hindfoot-ankle score. Preoperative coronal and sagittal plane deformity are not markedly different, depending on the diagnosis. Preoperative deformity does not appear to correlate significantly with postoperative function, as measured by the PROM scores. Postoperative sagittal plane alignment does not correlate significantly with postoperative function, as measured by PROMs. Coronal plane alignment, as measured by the medial distal tibial angle, may be associated with postoperative function, as measured on the AOFAS hindfoot-ankle and FAOS function subscales.

Comparison of 25 ankle arthrodeses and 25 replacements at 67 months’ follow-up

IntroductionIn the treatment of osteoarthritis of the ankle, controversy persists between advocates of arthrodesis and of joint replacement. HypothesisResults of total ankle replacement (TAR) are equivalent to those of ankle arthrodesis (AA). Material and methodsA single-center continuous retrospective series included 50 patients (25 TAR, 25 AA) operated on by a single surgeon. TAR used the standard Salto® mobile-bearing prosthesis, and arthrodesis used screws or plates. Results were assessed clinically on AOFAS score, visual analog scale (VAS) and satisfaction questionnaire, and radiologically on X-ray and CT. Survivorship in the 2 procedures was estimated on the Kaplan Meier method. ResultsAt a mean 67 months’ follow-up (range, 40–105 months), mean AOFAS and VAS scores were significantly better in the AA group (74.1 and 1.9, respectively) than in the TAR group (67 and 3.5, respectively) (p<0.001). In the AA group, 80% of patients were satisfied or very satisfied, compared to 64% after TAR. Five-year survival without revision for non-union (AA) or implant removal (TAR) was similar between groups: AA, 96%; TAR, 90% (p=0.72). In contrast, survival with no revision procedures was significantly better with AA (96%) than TAR (75%) (p=0.03). DiscussionAt 5 years, surgical revision rates were significantly greater than after standard Salto® mobile-bearing TAR than for arthrodesis, notably due to onset of cysts; we therefore decided to abandon this implant. Level of evidenceIV, comparative retrospective study.

Total ankle replacement: is pre-operative varus deformity a predictor of poor survival rate and clinical and radiological outcomes?

The objective of this study was to compare survival rate and clinical and radiological outcomes of a cementless mobile-bearing total ankle replacement (TAR) between two groups of patients, affected by end-stage ankle arthritis, with or without a pre-operative varus deformity. A total of 81 patients (81 ankles) were included in the study and divided in two groups. Group A, "varus" group, includes 11 patients with pre-operative varus deformity of more than 10° and group B, "neutral" group, includes 70 patients, with a varus/valgus deformity of less than 10°. American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, visual analogue scale (VAS), and Short Form (SF)-12 score were used to compare clinical outcomes. Radiological parameters, complications, and survival rate at last follow-up were also recorded. In both groups, all clinical and radiological parameters improved after surgery (p< 0.05) without statistically significant difference. Complications were similar between two groups. Overall in three cases, an implant revision was necessary: 1 in group A (9%) at 3.1years follow-up and 2 (3%) in group B at 3.8years, without statistically significant difference (p> 0.001). Severe varus malalignment should not be considered a contraindication for a mobile-bearing TAR. Nevertheless, TAR in severe deformity should be performed only by experienced surgeons.

The effect of patient age and diagnosis on the 5-year outcomes of mobile-bearing total ankle replacement

Total Ankle Replacement is an established technique for the management of end-stage ankle arthritis. However, there are few studies focussing on patient-reported outcomes in the medium and long term related to age or arthritis type. We compared demographic data and patient-reported outcomes preoperatively and at five years postoperatively for patients who underwent total ankle replacement with the aim of establishing whether differences exist in outcome depending on patient age or diagnosis. The Foot and Ankle Score (FAOS) and 36-item Short-Form (SF-36) Health Survey were analysed by diagnosis (osteoarthritis, rheumatoid arthritis, post-traumatic arthritis) and age (under or over 60 years).At 5 years, the post-traumatic arthritis group had a significantly higher composite score than the osteoarthritis (p<0.0001) or rheumatoid arthritis groups (p<0.0001). Only the post-traumatic arthritis group experienced a significant increase in composite SF-36 score from baseline (p<0.0001). There was a significant improvement from pre-operatively to 5 years in all three domains of the FAOS and in total scores in both groups (over 60 p<0.0001; 60 and under p=0.0002). There was a significant improvement in composite SF-36 score from pre-operative to 5 years in the patients 60 years or younger at the time of surgery (p=0.0006), but not for the patients over 60. Three patients have been revised (4%), at a mean of 4.8 years following surgery with one patient awaiting revision.

Prospective Randomized Trial Comparing Mobile-bearing and Fixed-bearing Total Ankle Replacement

Category: Ankle Arthritis Introduction/Purpose: Outcomes of total ankle replacement for the treatment of end-stage ankle arthritis continue to improve. Debate continues whether a mobile-bearing total ankle replacement (MB-TAR) or a fixed-bearing total ankle replacement (FB-TAR) is superior, with successful outcomes reported longterm for MB-TAR and at intermediate-to-longterm follow-up for newer generation FB-TAR. Although comparisons between the two total ankle designs have been reported, to our knowledge, no investigation has compared the two designs with a high level of evidence. This prospective, randomized controlled trial conducted at a single institution compares patient satisfaction, functional outcomes and radiographic results of the mobile-bearing STAR and the fixed-bearing Salto-Talaris in the treatment of end-stage ankle arthritis. Methods: This investigation was approved by our institution’s IRB committee. Between November 2011 and November 2014, adult patients with end-stage ankle osteoarthritis failing nonoperative treatment were introduced to the study. With informed consent, 100 patients (31 male and 69 female, average age 65, range 35 to 85) were enrolled; demographic comparison between the two cohorts was similar. Exclusion criteria included inflammatory arthropathy, neuropathy, weight exceeding 250 pounds, radiographic coronal plane deformity greater than 15 degrees or extensive talar dome wear pattern (“flat top talus”). Prospective patient-reported outcomes, physical exam and standardized weightbearing ankle radiographs were obtained preoperatively, at 6 and 12 months postoperatively, and then at yearly intervals. Data collection included visual analog pain score (VAS), short form 36 (SF-36), foot and ankle disability index (FADI), short musculoskeletal functional assessment (SMFA) and AOFAS ankle-hindfoot score. Surgeries were performed by non-design team orthopaedic foot and ankle specialists with total ankle replacement expertise. Statistically analysis was performed by a qualified statistician. Results: At average follow-up of 4.5 years (range 2-6 years) complete clinical data and radiographs were available for 84 patients; 7 had incomplete data, one had died, 4 were withdrawn after enrolling but prior to surgery and 4 were lost to follow-up. In all outcome measures, the entire cohort demonstrated statistically significant improvements from preoperative evaluation to most recent follow-up. There was no statistically significant difference in improvement in clinical outcomes between the two groups. Radiographically, tibial lucency/cyst formation was 26.8% and 20.9% for MB-TAR and FB-TAR, respectively. Tibial settling/subsidence occurred in 7.3% of MB-TAR. Talar lucency/cyst formation occurred in 24.3% and 2.0% of MB-TAR and FB-TAR, respectively. Talar subsidence was observed in 21.9% and 2.0% of MB-TAR and FB-TAR, respectively. Re-operations were performed in 8 MB-TAR and 3 FB-TAR, with the majority of procedures being to relieve impingement or treat cysts and not to revise or remove metal implants. Conclusion: For the first time, with a high level of evidence, our study confirms that patient reported and clinical outcomes are favorable for both designs and that there is no significant difference in clinical improvement between the two implants. The incidence of lucency/cyst formation was similar for MB-TAR and FB-TAR for the tibial component, but the MB-TAR had greater talar lucency/cyst formation and tibial and talar subsidence. As has been suggested in previous studies, clinical outcomes do not correlate with radiographic findings. Re-operations were more common for MB-TAR and in the majority of cases were to relieve impingement or treat cysts rather than revise or remove metal implants.

Range of Motion Following Total Ankle Replacement and Subtalar Fusion Through Lateral Versus Anterior Approach. Biomechanics Analysis

Category: Ankle Arthritis Introduction/Purpose: A gait analysis of patients who underwent simultaneous total ankle replacement (TAR) and subtalar fusion allows to assess the ankle range of motion (ROM) with precision. In healthy subjects or in patients who underwent isolated TAR this is not possible because it is influenced by the subtalar ROM and it is not possible to analyse the two joints separately. Excluding the role of the subtalar joint, it is possible to analyse the consequences of different prosthetic designs and different surgical approaches on joint kinematics. The aim was to evaluate and compare with a gait analysis the effects of two different TAR designs on the functionality of the tibiotalar joint by exploiting the exclusion of the subtalar effect determined by the subtalar fusion simultaneously performed. Methods: Minimum follow-up was 12 months. 16 patients underwent a fix-bearing TAR through lateral approach (Zimmer Trabecular Metal Total Ankle), 7 patients underwent a mobile-bearing TAR through anterior approach (Hintegra). A six-camera motion capture system was used to measure foot static posture and foot segment kinematics. Rotations in the sagittal, frontal, and transverse planes between shank and the whole foot, shank and calcaneus, calcaneus and midfoot, midfoot and metatarsus, and calcaneus and metatarsus were calculated. Sagittal and transverse plane rotations of the first matatarso-phalangeal joint, medial longitudinal arch deformation, transverse plane angle between first and second metatarsal bone and between second and fifth metatarsal bone, and sagittal plane orientation of the first and second metatarsal bone with respect to the ground were also calculated. The following spatio-temporal parameters were calculated: stance time, swing time, stride length, normalized stride length, cycle time, cadence, walking speed, and normalized walking speed. Results: On average, the lateral approach group walked at a faster speed and with a longer stride length than the anterior approach group. However, spatio-temporal parameters in both groups were generally lower than the control values. No major differences were detected between the two groups in terms of ROM in any foot joint, with the exception of the frontal-plane motion of the midfoot with respect to the calcaneus (midtarsal joint) which was larger in the anterior approach group. Conclusion: patients with TAR through lateral approach seem to walk at a faster speed and with a longer stride length than patients with TAR through anterior approach; the midtarsal joint ROM was larger in the anterior approach group and this could mean that mobile bearing TARs through an anterior approach could lead to an overload of the midtarsal joint with respect to fixed-bearing TARs through a lateral approach. However, further studies with larger samples of patients are needed to confirm these results.

The AES total ankle arthroplasty analysis of failures and survivorship at ten years.

AES mobile-bearing total ankle replacement was developed from the Buechel Pappas model. It was withdrawn in 2009, after identification of a higher than expected complication rate. The purpose of the current study was to analyse clinical outcomes, failures and survival of the initial series of 50 AES published in 2009. In this single-centre continuous prospective study (2003-2006), 50 AES prostheses were included. Pre-operative osteoarthritis was mainly post-traumatic (50%) and secondary to instability (36%). All patients were assessed with clinical and radiographic follow-up at six months, one year, two years and every two to three years thereafter. A CT-scan was systematically performed before procedure, and at two years, five years and ten years. At last follow-up, all patients with TAR had a functional (SF 36, AOFAS) and clinical assessment. All complications or surgical events were analysed. The mean follow-up was ten ± two years (range, 9-13). The mean AOFAS score was 75 points (range, 26-100). The mean SF 36 score was 69 points (range, 35-97). There was a significant deterioration in AOFAS score at five years and at last follow-up (p<0.05). Fifteen TARs underwent reoperation for cyst curettage-graft because of development of periprosthetic lesions. Six of them ended up with prosthesis removal-arthrodesis. At the last follow-up, 14 TARs were removed for arthrodesis. Of the 30 prostheses seen at last follow-up, four are awaiting prosthesis removal-arthrodesis and one for cyst curettage-graft. The ten year survivorships free of any prosthesis removal or arthrodesis and free of any reoperation were 68% (95% CI, 55-85) and 57% (95% CI, 44-74), respectively. Our data suggested a high rate of reoperation. Overall ten year survival was lower than with other designs, particularly due to cyst lesions. Level IV, prospective case series.

Mobile- vs. Fixed-Bearing Total Ankle Prostheses

Category: Ankle, Ankle Arthritis Introduction/Purpose: Total ankle replacement (TAR) is a well-accepted treatment option in patients with end-stage ankle osteoarthritis. In general, TAR designs can be classified based on their number of components: 2-components (fixed-bearing) vs. 3- components (mobile-bearing). In the U.S. the STAR prosthesis is the only one mobile-bearing TAR with FDA approval. It remains unclear whether 3-component TAR designs have superior clinical outcomes including prosthesis survivorship. Therefore we performed a systematic review and meta-analysis of the available TAR designs to determine prosthesis survivorship and whether there is a statistically significant difference between mobile- and fixed-bearing TAR designs. Methods: We reviewed literature using common data bases. All searches were unlimited. For the search we used the subject heading terms: “ankle”, “replacement”, “arthroplasty”, and “prosthesis”. For meta-analysis a checklist was used as described by Meta-analysis Of Observational Studies in Epidemiology (MOOSE) Group. The quality of included studies was assessed using Coleman’s Methodology Score. The following parameters were reviewed: type of study, inventor bias, number of patients/ankles, mean age with range, gender, etiology of underlying ankle osteoarthritis, average and maximum follow-up, number of TAR failures, and total exposure time. For each study, failure rate was estimated as the number of failures/total exposure years. N-year (here, 5 or 10 years) failure rate was calculated as 1-exp(-N*failure rate). The pooled estimate of failure rate was a weighted average across studies using the inverse variance weighting method. The test for heterogeneity was not significant so fixed effects models were used. Results: In total, 32 studies with 3968 ankles were included into the analysis. Nine studies included 844 fixed-bearing TARs and 23 studies included 3124 mobile-bearing TARs. Patient characteristics were comparable in both study groups. For fixed-bearing TAR, the 5-year and 10-year failure rate was 0.077 and 0.149 with an average annual failure rate of 0.016 (95%CI 0.008-0.025). For mobile-bearing TAR, the 5-year and 10-year failure rate was 0.074 and 0.142with an annual failure rate of 0.015 (95%CI 0.011- 0.020). Two studies with fixed-bearing TAR and six studies with mobile-bearing TAR had inventor bias. The average annual failure rate was comparable in both groups (P = 0.88), with and without inventor bias, 0.013 vs. 0.018 (P = 0.87). Conclusion: We have shown that TAR has an overall failure rate of 0.149 and 0.142 at 10 years in patients with fixed-bearing and mobile-bearing TAR design, respectively. No superiority of one implant design over another can be supported by the available data.

Age-Related Outcome of Mobile-Bearing Total Ankle Replacement

Category: Ankle, Ankle Arthritis Introduction/Purpose: Total ankle replacement (TAR) is becoming increasingly popular amongst patients with end-stage ankle arthritis. This is in part related to the advances in design, technology, and technique that have improved TAR longevity. The ideal candidate for a TAR is not fully clear. For a long time patients over age 50 years, body mass index (BMI) under 30 kg/m2, and with low functional demands represented selection criteria for many patients. However, these criteria were based off a very limited number of scientific studies on older TAR designs. The aim of this study is to investigate clinical and radiographic outcome in patients of 50 years or less versus patients over 50 years undergoing a Hintegra® total ankle replacement (Integra, Plainsboro, NJ). Methods: This study includes 70 consecutive patients who underwent primary TAR from May 2011 to April 2014. The cohort was divided into 2 groups: the young group (YG) with age less than or equal to 50 years, and the older group (OG) with age above 50 years. Patients were assessed clinically and radiologically preoperatively and at 6, 12 and 24 months postoperatively. Results: A significant increase in the AOFAS and SF-12 and decrease in VAS scores was seen in both groups between preoperative and final followup (p &lt; 0.001). There was a statistically significant difference between the YG and OG for the AOFAS score at final follow-up. The YG had significantly greater improvement compared to the OG (p = 0.046). In addition radiographic results showed no statistically significant difference in the coronal and sagittal alignment between the 2 groups. The mean postoperative angles in either study group demonstrated significant improvements compared to the preoperative alignment. Conclusion: This study demonstrates that total ankle arthroplasty is an effective short-term treatment for young, active patients with symptomatic end-stage ankle arthritis. Our findings are in disagreement with the widespread theory that ankle replacement is a more reliable treatment in the elderly

Age-related outcome of mobile-bearing total ankle replacement

Category:Ankle, Ankle ArthritisIntroduction/Purpose:Total ankle replacement (TAR) is becoming increasingly popular amongst patients with end-stage ankle arthritis. This is in part related to the ad...