Functional and radiological assessment of total ankle replacement with infinity prosthesis

Objective: To present mid-term functional and radiological outcomes obtained with the use of Infinity prosthesis in Bogotá (Colombia). Methods: This cross-sectional observational study selected consecutive patients subjected to total ankle replacement with the fourth generation Infinity prosthesis (Wright Medical Technology). Results: Fifty-two patients with ankle arthrosis were followed for a mean period of 24 months, and the most frequently reported case of joint degeneration was trauma. Postoperative improvement was observed in perception of pain (visual analog scale increased from 8/10 to 2/10; p<0.0005), AOFAS functional scale (from 23 to 84.5; p < 0.0005), and range of motion (from 11° to 29°; p<0.0005). Similarly, radiological findings, implant positioning, and signs of loosening did not reveal implant failure. Conclusions: The use of fluoroscopically navigated prostheses allows us to achieve predictable outcomes, with satisfactory mid-term clinical and imaging results. Level of Evidence IV; Therapeutic Studies; Case Series.

TL 18183 - Total ankle arthroplasty

Introduction: Total ankle arthroplasty (TAA) is an alternative for the treatment of end-stage ankle arthrosis that is still in the implementation phase in Brazil. The objective of this study is to present the clinical and radiographic outcomes of the INBONE II prosthesis assessed by the Ankle and Foot Groups of the Department of Orthopedics and Traumatology of the Paulista School of Medicine at Federal University of São Paulo and Federal University of Minas Gerais. Methods: From November 2016 to December 2018, 13 TAAs were performed in 13 patients (4 females: 31%; 9 males: 69%) with ages ranging from 41 to 84 years (mean: 58 years) using INBONE II implants (Wright Medical Technology, USA). Parametric data on arthrosis etiology, clinical status (visual analog scale (VAS) and American Orthopedic Foot and Ankle Society (AOFAS) scores), implant positioning and bone cut adequacy (lateral tibial slope (LTS), alpha, beta and theta angles and distances "a" and "b") were collected, in addition to short-term qualitative bone properties (periprosthetic bone cysts and tibial and talar component sinking and wear). We also collected immediate and early postoperative data on associated surgeries, complications and reinterventions. All data were subjected to statistical analysis at the 5% significance level. Results: The VAS (pre 8; post 2) and AOFAS (pre 37; post 80) scores significantly improved at the end of a mean follow-up period of 10 months (min 1 month: max 2 years, 2 months). The immediate and early postoperative tibial and talar component alignment was within 2 degrees of deviation from the ideal in the sagittal plane in 84% patients and in the coronal plane in 92% patients, with an LTS below 5 mm in 100% of patients and good correction of radiographic parameters, even in cases of arthroplasty revision. Conclusion: Total ankle replacement is a good alternative for the treatment of advanced arthrosis of the ankle, and the INBONE II prosthesis is seems to be a good option for cases of arthroplasty failure due to loosening or malalignment. Longer follow-up is needed to evaluate intermediate and long-term outcomes.

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

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

The Role of Axial Rotation in Total Ankle Replacement

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

The Infinity Total Ankle System

Category: Ankle Arthritis Introduction/Purpose: Background: Increasing interest in 2-component total ankle arthroplasty (TAA) designs and the increased use of TAA overall has led to the development of a new generation of 2-component TAA implants. The first of these to become available was the Infinity Total Ankle System (Wright Medical Technology, Memphis, TN), introduced in 2014. Despite it currently being the most commonly used TAA implant in the UK and among the most commonly used in the USA, published clinical results are lacking. Purpose: This study presents the first report of the clinical and radiographic outcomes of the Infinity Total Ankle System with minimum 2 year follow-up Methods: The first 67 consecutive patients who underwent primary Infinity total ankle arthroplasty (TAA) at 2 North American sites between 2013 and 2015 were reviewed in a prospective observational study. Demographic, radiographic, and functional outcome data was collected preoperatively, at 6-12 months postoperatively, and annually thereafter. Results: The overall implant survival rate was 97% (65 of 67 implants) at mean follow up of 3 years (range 27-47 months). Two cases underwent talar component revision for aseptic loosening. Six of the 67 cases (9%) required a non-revision reoperation. Mean FFI and AOS scores at latest follow up improved from preoperative by 21.6 (p<0.0001) and 34.0 (p<0.0001), respectively. No radiographic loosening of any talar or tibial components was identified in the 65 non-revised cases. Conclusion: Early clinical and radiographic outcomes with the Infinity TAA are promising and compare favorably to those reported for both fixed- and mobile-bearing third generation TAA designs, even when used in cases with deformity and increased case complexity.

Tibialis Anterior Tendon Reconstruction Using Augmented Half-Thickness Tendon Segment Transposition

Tibialis anterior tendon rupture causes substantial morbidity. The present study describes the outcomes of augmented, half-thickness tibialis anterior tendon segment transposition, a novel reconstruction technique. This was an institutional review board–approved retrospective review of 3 patients with surgically treated attritional distal rupture with 1-year follow-up. The postdebridement tendon defect prohibited primary repair and was managed by distal transposition of a half-thickness healthy segment. This repair was augmented with human acellular dermal matrix allograft (Graftjacket, Wright Medical Technology, Memphis, TN). The mean age was 68 years (range, 59-73 years). Mean interval between injury and surgery was 59.3 days (range, 15-146 days). All patients regained symmetrical range of motion, motor power, and the ability to heel walk. Mean pain scores improved from 4.6 (range, 2.5-8.5) preoperatively to 0.7 (range, 0-2) postoperatively. Mean Foot and Ankle Ability Measure scores increased from 30.6 (range, 23.8-43.8) preoperatively to 78.7 (range, 72.6-97.6) postoperatively. No postoperative complications occurred. One patient was satisfied and 2 were very satisfied with their outcome. Although limited, the present findings appear to indicate that this technique produces short-term clinical results comparable to those described for other techniques for tibialis anterior tendon reconstruction. Levels of Evidence: Therapeutic, Level IV

Lateral Ankle Stabilization Using Acellular Human Dermal Allograft Augmentation

Background We describe a retrospective study that uses the Broström-type surgical procedure with modifications that augment deficient and torn ligaments with acellular human dermal grafts. At the onset of this study, the most prevalent dermal graft available to us was GraftJacket (Wright Medical Technology, Arlington, Tennessee). Greater than 50% of the study participants were grafted with this product, but more recently other equally effective human dermal grafts have been used with no apparent difference. Methods Thirty-five lateral ankle stabilization procedures were performed in the past 6 years on 33 patients. Eight patients were considered athletes (mean age, 23 years). The balance of the study group consisted of sedentary patients (mean age, 41 years). The mean patient body mass index (calculated as the weight in kilograms divided by the square of the height in meters) was 31. Results All of the patients were satisfied with their results, with no recurrent instability. Two patients in this group went on to have contralateral ankle stabilization in a similar manner owing to their satisfaction. Complications included two soft-tissue infections. Conclusions Lateral ankle stabilization using acellular human dermal graft augmentation is a useful tool in the surgical treatment of ankle instability. This procedure offers distinct advantages over traditional methods of ankle repair and can be performed with relatively limited surgical exposure. Ease of operation, consistent results, and limited patient morbidity should allow surgeons to use this procedure independently or adjunctively to improve surgical outcomes.

Ολική αρθροπλαστική ισχίου με μεταλλικές αρθρούμενες επιφάνειες, συναρμολογούμενους μεταβλητούς αυχένες και μεγάλες κεφαλές

Λόγω των θεωρητικών πλεονεκτημάτων τους, τα συστήματα ισχίου που συνδυάζουνμεταβλητούς αυχένες και μεγάλες κεφαλές απέκτησαν βαθμιαία μεγάληδημοτικότητα. Όμως, μεταξύ των άλλων, ανησυχίες διατυπώθηκαν για τις αλλαγέςπου τα συστήματα αυτά επιφέρουν στο πρότυπο των φορτίσεων στο εγγύς μηριαίο.Πράγματι, πρόσφατες αναλύσεις φορτίσεων έδειξαν ότι η χρήση τωνσυναρμολογούμενων αυχένων και των μεγάλων κεφαλών αλλάζει σημαντικά τηνκατανομή των φορτίων κατά μήκος του μηριαίου. Η αρχική μας υπόθεση είναι ότι οιμεταβολές αυτές επηρεάζουν την πρώιμη άπω μετανάστευση του μηριαίου στυλεού.Εξετάσαμε, κατόπιν, την επίδραση της διαμέτρου της κεφαλής και της γεωμετρίαςτου αυχένα στην μετανάστευση του στυλεού μετά δύο χρόνια παρακολούθησης σεμια σειρά 116 ασθενών (125 ισχίων), οι οποίοι υποβλήθηκαν σε πρωτογενή ΜοΜΟΑΙ με την εγγύς αρθρωτή πρόθεση Profemur®E (Wright Medical Technology Inc., Arlington, TN) συνδυασμένη με κεφαλές μεγάλης διαμέτρου (≥40mm). Βρήκαμε ότιη επιλογή της γεωμετρίας του αυχένα και της διαμέτρου της κεφαλής δεν είχε καμίαεπίδραση στην μετανάστευση του στυλεού. Μία πολυπαραγοντική ανάλυσηπαλινδρόμησης που περιέλαβε τους συγχυτικούς παράγοντες του δείκτη μάζαςσώματος, της ποιότητας του οστού, της πλήρωσης του αυλού σε διάφορες θέσεις καιτης θέσης τοποθέτησης του στυλεού απεκάλυψε μόνο μια αρνητική συσχέτιση μεταξύ της καθίζησης και της πλήρωσης του αυλού στο ύψος της μέσης του στυλεού. Ηστατιστική ανάλυση δεν επιβεβαίωσε την αρχική μας υπόθεση ότι η επιλογή τηςγεωμετρίας του αυχένα και/ή της διαμέτρου της κεφαλής επηρεάζει την πρώιμη άπωμετανάστευση του στυλεού. Απεδείχθη όμως η σημασία της σωστής εκτίμησης τουμεγέθους του στυλεού. Για να διερευνήσουμε παραπέρα αν τα διαφορετικά πρότυπα φορτίσεων τωνδιαφόρων κατευθύνσεων του αυχένα και των διαφορετικών διαμέτρων της κεφαλήςπαίζουν κάποιο ρόλο στην αυξημένη συχνότητα χαλάρωσης, σχεδιάσαμε μιαανάλυση πεπερασμένων στοιχείων και χρησιμοποιήσαμε σαν πρότυπο το σύστημα μετον ευθύ αυχένα και την κεφαλή των 28 χιλ. Χρησιμοποιώντας στοιχεία πουπροήλθαν από αξονικές τομογραφίες, αλλά και τη χρήση μιας σταθερής μετρητικήςμηχανής, ένα πτωματικό μηριαίο και ο αρθρωτός στυλεός Profemur®Eψηφιοποιήθηκαν πλήρως, οδηγώντας μέσω του λογισμικού ANSYS Workbench σεένα τρισδιάστατο μοντέλο πεπερασμένων στοιχείων. Αρχικά, προσδιορίσθηκαν ταφορτία και οι παραμορφώσεις, εστιάζοντας σε ορισμένες περιοχές κατά μήκος τουμηριαίου: στο μηριαίο πλήκτρο και στην εξωτερική επιφάνεια κάτω από τον μείζονατροχαντήρα, στην περιοχή του άκρου του στυλεού, καθώς και κατά μήκος τηςτραχείας γραμμής. Η ανάλυση των πεπερασμένων στοιχείων απέδειξε ότι η χρήσητων μεγάλων κεφαλών προκαλεί σημαντικές αλλαγές στις παραμορφώσεις μέσα στονοστικό όγκο, σε σχέση με το μοντέλο με την κεφαλή των 28 χιλ. Στην εξωτερικήεπιφάνεια του μηριαίου, κατά μήκος της τραχείας γραμμής και στο άκρο του στυλεούη αύξηση της διαμέτρου οδηγεί σε αύξηση των παραμορφώσεων, ενώ στην περιοχήτου μηριαίου πλήκτρου συμβαίνει το αντίθετο.Κατόπιν υπολογίσθηκαν οι μέσες τιμές των παραμορφώσεων για καθεμία από τις 11γεωμετρίες του αυχένα, εστιάζοντας σε συγκεκριμένες περιοχές ενδιαφέροντος: στηνέσω πλευρά του μηριαίου στο μηριαίο πλήκτρο, στην έξω πλευρά στην περιοχή κάτωαπό τον μείζονα τροχαντήρα, καθώς επίσης στην πρόσθια και οπίσθια επιφάνεια τουμηριαίου και σε μια κυκλική περιοχή γύρω από το άκρο του στυλεού. Συγκρινόμενοιμε το σύστημα με τον ευθύ αυχένα, ο αυχένας με πρόσθια κλίση 15° έδειξε μιααύξηση 17% και 17.7% στην πρόσθια και οπίσθια επιφάνεια του μηριαίου και φαίνεται να είναι ο πιο επικίνδυνος. Ο ίδιος αυχένας έδειξε τη μεγαλύτερη αύξησητων παραμορφώσεων στην εξωτερική περιοχή ενδιαφέροντος (13%) και στο μηριαίοπλήκτρο (5%). Στην περιοχή του άκρου του στυλεού η μεγαλύτερη αύξησηκαταγράφηκε με τον διπλής γωνίας βλαισό-οπίσθιας κλίσης αυχένα (15.4%), ενώ μετον 15° πρόσθιας κλίσης ήταν 11%.Πιστεύουμε, πάντως, ότι η δημοσιευμένη μεγαλύτερη συχνότητα άσηπτηςχαλάρωσης των συγκεκριμένων συστημάτων δεν μπορεί να εξηγηθεί με τα ευρήματααυτής της μελέτης. Αντίθετα η εξήγηση πρέπει να αναζητηθεί στη βιοδραστικότητατων μεταλλικών ιόντων που παράγονται από τις ΜοΜ συνδέσεις και όχι μόνο στηνεμβιομηχανική αυτών των συστημάτων.

Spherical Ceramic Interpositional Arthroplasty for Basal Fourth and Fifth Metatarsal Arthritis

Background: Arthrosis of the fourth and fifth tarsometatarsal joints is difficult to treat. Arthrodesis is both difficult to achieve as well as disabling. Tendon interpositional arthroplasty has been performed with some success. A new technique using ceramic ball interpositional arthroplasty was evaluated. Methods: Between 2001 and 2003, 13 patients in whom nonoperative treatment had failed had resection arthroplasty of the base of the fourth or fifth metatarsals with ceramic ball interposition (Orthosphere, Wright Medical Technology, Arlington, Tennessee). Patients were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) Midfoot Scale, a visual analogue scale, a satisfaction index, physical examination, and radiographs. Results: At an average 34-months followup, 11 of the 13 patients were available for evaluation. The five men and six women had an average age of 48 years. Seven patients reported a traumatic etiology. Average postoperative AOFAS score was 53 points, an 87% improvement over preoperative values. Visual analogue scale pain improved 42%. All 11 patients were satisfied and would undergo the operation again. One of the patients demonstrated subsidence of the implant into the cuboid but continued to have improvement in symptoms. To date there have been no implant dislocations. Three of the 11 patients had differential injections before surgery. Conclusions: Lateral column tarsometatarsal interpositional arthroplasty is an effective salvage operation for lateral column midfoot arthrosis and should be considered in this patient population. The use of the ceramic ball allows a technically simple procedure and rapid recovery.