- Email: [email protected]
The Salto Talaris Total Ankle Arthroplasty System: A Review and Report of Early Results
The Salto Talaris Total Ankle Arthroplasty System: A Review and Report of Early Results Siddhant K. Mehta,* Brian G. Donley, MD,† Jeffrey R. Jockel, MD,‡ Mark P. Slovenkai, MD,‡ Mark M. Casillas, MD,§ Wayne S. Berberian, MD,* and Sheldon S. Lin, MD* With ongoing advances in joint-replacement technology and renewed interest in total ankle arthroplasty (TAA), various TAA systems have been developed during the past decade to surgically manage severe, end-stage arthritis. Better understanding of physiological kinematics and anatomic relationships with reference to the ankle joint has allowed for improved prosthetic design and more precise surgical techniques, potentially creating promising superior clinical outcomes. One such TAA system that has emerged and recently gained Food and Drug Administration approval is the Salto Talaris Anatomic Ankle (Tornier, Saint-Ismier, France), which features a fixed-bearing, 2-component design derived from a mobile-bearing European design. Although clinical results are yet to be reported, insight as to its likely role in providing improved functional outcomes can be extrapolated from the authors’ experiences using this TAA system and from short- and mid-term results of the Salto mobile-bearing design. This article aims to provide historical background, describe surgical technique, and present relevant clinical data to better understand the potential role of the Salto Talaris ankle replacement system in providing symptomatic relief and optimal range of motion, and hence improving quality of life in patients with end-stage ankle arthritis. Semin Arthro 21:282-287 © 2010 Elsevier Inc. All rights reserved. KEYWORDS Salto Talaris, total ankle arthroplasty, total ankle replacement, early results
E
nd-stage ankle arthritis is a common problem encountered by foot and ankle surgeons. For many years, ankle arthrodesis has been performed to reduce joint motion and hence provide symptomatic relief in patients with arthritic ankles. However, the major setbacks of rigid internal fixation as used in arthrodesis are reduced range of motion and disturbance of the biomechanics of adjacent joints, resulting in arthrosis.1,2 To overcome this, total ankle arthroplasty (TAA) was developed as an alternative to arthrodesis and has gained increasing popularity during the past decade among patients, surgeons, and manufacturers. Initially plagued with compli-
*Department of Orthopaedics, University of Medicine & Dentistry of New Jersey (UMDNJ), New Jersey Medical School, Newark, NJ. †Center for Foot and Ankle, Department of Orthopaedic Surgery, Orthopaedic and Rheumatology Institute, Cleveland Clinic, Cleveland, OH. ‡Department of Orthopaedic Surgery, Tufts University, School of Medicine, Boston, MA. §Foot and Ankle Center of South Texas, San Antonio, TX. Address reprint requests to Sheldon S. Lin, MD, Associate Professor, Department of Orthopaedics, University of Medicine & Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, 90 Bergen Street, DOC, Suite 7300, Newark, NJ 07103. E-mail: [email protected]
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1045-4527/10/$-see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1053/j.sart.2010.09.010
cations and failures, the evolution of TAA prosthetic design and surgical technique has occurred with better understanding of physiological ankle motion and has continued to improve clinical outcomes. Although currently not the “gold” standard treatment for end-stage ankle arthritis, TAA may become the treatment mainstay for this problem in the future. Despite the failure of early TAA designs, interest has been renewed with the development of second-generation uncemented implants with a fixed (2-component) or mobile (3component) polyethylene bearing. Featuring designs that were less constrained and more closely mimicking normal ankle anatomy, combined with improved fixation approaches, these implants provided more encouraging results than their first-generation predecessors. However, increased polyethylene wear and TAA failure caused by painful impingement, subluxation, or complete dislocation of components made apparent the need for a superior design: the third generation implant. Third-generation ankle prostheses consist of a metallic baseplate fixed to the tibia, a domed metallic component that anatomically resurfaces the talus, and a bearing surface made
The Salto Talaris total ankle arthroplasty system
283 component of the Salto Talaris requires fixed insertion of the polyethylene bearing, being slid into a tibial component tray and hence being replaceable. Its improved instrumentation allows the trial tibial component to rotate into the correct position as determined by the talar component.
Indications and Contraindications
Figure 1 Example of a Salto Talaris total ankle arthroplasty system. (Color version of figure is available online.)
of ultrahigh molecular weight polyethylene interposed between the tibial and talar components. Fixed-bearing systems include a titanium tibial component with a tibial post, a highly conforming polyethylene articulating insert, and a talar component that anatomically resurfaces the anterior/posterior and lateral surfaces. Mobile-bearing systems adapt a similar design, but the bearing component is left free between the tibial and talar components, theoretically reducing the stress on the fixation of the implants. The actual amount of relative motion that the mobile component provides in vivo compared with a fixed component is controversial.3 The newer implants also use improved osseous integration materials with in-growth characteristics that require no cement. The Salto Talaris Anatomic Ankle (Tornier, Saint-Ismier, France) is a Food and Drug Administration-approved thirdgeneration total ankle-replacement system that uses a 2-component fixed-bearing design in an effort to reduce pain, provide realignment at the ankle joint, and restore normal ankle anatomy for optimal range of motion (Fig. 1). Its design was based on the Salto mobile bearing prosthesis used in Europe, which upon initial postoperative radiographic evaluation of 20 ankles demonstrated minimal anteroposterior and varus/ valgus mobility between the polyethylene and tibial components; hence, the idea for a fixed bearing design with a similar construct.3 Improvements in design included changes to both the talar and tibial components.4 In an effort to mimic normal anatomy and biomechanics about the ankle joint, the new talar component was designed to have a conical surface with differential radii of curvature, the medial being smaller than the lateral radius. To provide stiffness at the subtalar joint and overall stability upon motion, a curved groove was also created in the sagittal plane, along with 4° of rotation around the center of curvature in the area above the subtalar joint, and a central peg.4 The tibial
Clinical indications for TAA, although not clearly defined, should be influenced by several factors, including anticipated intermediate and long-term results, and whether salvage of a TAA failure secondary to component loosening, infection, or hypertrophic bone growth would be possible.5,6 Careful patient selection is fundamental, with the procedure ideally performed in older patients (although there is no specific age requirement) with low-impact daily activity, good bone stock, no osteopenia, metabolic disorders, or systemic pharmacologic treatments that would lead to progressive deterioration of solid bone support for the implant (to allow appropriate implant fixation), no surrounding soft tissue pathology, and minimal deformity to the ankle joint (correct hind foot-ankle alignment).
Preoperative Planning Standard radiographic evaluation helps determine implant size and amount of osteophyte resection necessary for adequate exposure of the tibial joint surface and consists of anteroposterior, lateral, and mortise roentgenograms of the ankle, with contralateral comparative films obtained as needed. To evaluate bone stock and assess joint-surface defects, degenerative joint changes, or location of osteophytes, more advanced imaging, such as computed tomography, alone or in combination with arthrography, may be useful. Magnetic resonance imaging (MRI) may serve beneficial to detect the presence of avascular necrosis of the talus, which is among the contraindications for TAA. Furthermore, a bone scan can help to determine whether joints distal to the tibiotalar joint (eg, subtalar) demonstrate degenerative changes, which may require ankle fusion (tibiotalocalcaneal or staged subtalar) before arthroplasty.
Surgical Technique The tibial cut is performed first after verifying the “resection level” and “rotation and medial/lateral displacement” adjustments on the cutting guide using an external jig system. Nine millimeters of bone is usually resected from the distal tibia referenced off the tibial plafond. Rotational alignment is referenced off the talar body. The syndesmosis and distal fibular articulation is left intact when using this system. When preparing the talus, minimal chamfered bone resection is performed, with maintenance of the anatomic contour of the talus. The trial tibial base is allowed to auto-rotate into proper position to achieve appropriate alignment of the prosthesis. A tibial keel, which is referenced off the talar component, is
S.K. Mehta et al
284
Figure 2 The trial talar and tibial base components are placed (A), the joint is reduced, and the ankle is fully ranged to allow self-alignment of the tibial assembly. This is a critical step to find the “sweet spot.” Creation of the tibial keel (B) is performed by drilling the appropriate holes and using an osteotome to connect them. (Color version of figure is available online.)
subsequently formed to maintain alignment and rotation (Fig. 2). Adjunctive procedures, such as Achilles tendon lengthening or ligamentous releases, are performed on an individual basis before implantation of the final components.7 After being nonweight-bearing for 6 weeks in a cast or cam walker, the patient is progressively allowed to bear weight and perform range of motion exercises.
Conceptual Differences Between the Salto Talaris and Other Systems The Agility prosthesis (DePuy, Warsaw, IN) requires syndesmotic fusion, resulting in increased operative time, the need for bone grafting, an additional procedure for removal of hardware, and delayed weight-bearing (8 weeks).8 The Scandinavian Total Ankle Replacement (STAR; Waldemar Link, Hamburg, Germany) prosthesis is a mobile-bearing system, but theoretically there are issues, such as bearing fracture, bearing wear, and overhang with edge loading.9 In contrast, when implanting the Salto Talaris, the syndesmosis and distal fibular articulation is left intact. In addition, the Salto Talaris has a fixed bearing design that uses instruments to autorotate the tibial component to the talus to find the “ideal spot.” Even in a well-placed mobile-bearing Salto, minimal translation (⬍2 mm) and rotation (⬍3 degrees) were reported,10 supporting the fixed bearing design.
Complications Despite the newer generation of prostheses boasting an improved design and superior instrumentation, TAA remains a technically demanding surgical procedure with high complication rates and a steep learning curve. Some investigators have suggested that with greater surgeon experience, the number of intraoperative complications diminishes, optimal
alignment improves, and reliability of TAA improves.11,12 Using the Agility Total Ankle System (DePuy), Myerson and colleagues reported the occurrence of intraoperative complications in their initial 25 procedures, whereas only 2 occurred in their next 25 cases.14 Similarly, Haskell and Mann11 reported a reduction in perioperative complications with increasing surgeon experience with the STAR system. The most common complications associated with TAA are problems associated with wound healing, fractures of the medial and/or lateral malleoli, polyethylene bearing wear, and osteolysis.13 In addition, delayed union or nonunion, component subsidence, instability, bony impingement, and infection may occur.13,14 In an effort to reduce intra- and postoperative complications, surgeons must familiarize themselves with the surgical approach, plan ahead for possible variations in patient anatomy, and be comfortable with instrumentation of the TAA of their choice.
Results Although limited clinical data exist regarding the fixed-bearing Salto Talaris total ankle prosthesis, one may extrapolate from the outcomes of the earlier mobile-bearing European design (Salto Total Ankle; Tornier). Preliminary results of the Salto Total Ankle Prosthesis were described by Bonnin and colleagues15 in a prospective study evaluating 98 consecutive implants in 96 patients between 1997 and 2000. Because 2 patients were deceased, 1 patient was lost to follow-up, and 2 prostheses were removed, 93 implants in 91 patients were available for review. Sixty-two women and 36 men with a mean age of 56 years were reported with a mean follow-up of 35 months. The overall survivorship of the Salto prosthesis at 68 months when using surgical revision or radiographic loosening as the end point was reported to be 93.8% in the
The Salto Talaris total ankle arthroplasty system favorable scenario and 91.8% in the unfavorable scenario, and using implant removal as the endpoint, 98% and 94.9%, respectively. In addition, the mean American Orthopaedic Foot and Ankle Society scores were significantly improved from 32.3 ⫾ 10 points preoperatively to 83.1 ⫾ 16 points at the longest follow-up (P ⬍ 0.005). Overall range of motion as measured from dynamic radiographic also showed significant improvement from 15.2 ⫾ 10° preoperatively to 28.3 ⫾ 7° at follow-up. The authors concluded that these results were encouraging and supported the concept of anatomic replacement to improve functional outcomes, but recognized the need for longer follow-up for further validation. More recently, Bonnin and colleagues16 also retrospectively evaluated the return to sporting activities in 179 patients after implantation of a Salto TAA between 1997 and 2005 by delivering self-administered questionnaires to patients to assess foot and ankle function and ability. Of the 140 questionnaires analyzed, the mean patient age was 60.9 years, with a mean follow-up of 53.8 months, a male-tofemale ratio of 5:9, and mean body mass index of 25.6 kg/m2. The prosthesis was implanted for post-traumatic (70 ankles), primary (15 ankles), post-instability (15 ankles), or rheumatoid (40 ankles) end-stage arthritis. Overall patient satisfaction was described as normal in 15.2%, nearly normal in 60.7%, abnormal in 20%, and very abnormal in 4.1% of the patients. Furthermore, the mean Foot Function Index scores (0-100) were 13.7 ⫾ 17 for “activity limitations”, 31.7 ⫾ 23 for “disability” and 16.9⫾19 for “pain,” and the mean Foot and Ankle Ability Measurement scores were 74.9 ⫾ 18 for activities of daily living and 48.9 ⫾ 28 for sports activities. To correlate with the Foot and Ankle Ability Measure scores, subjective ankle ratings on the visual analog scales (0-100 where 100 is the “pre-pathology level”) were 70.2 ⫾ 19.6 for activities of daily living and 53.7 ⫾ 28 for sport activities. Participation in recreational sporting activities was only analyzed in patients with nonrheumatoid arthritic ankles. Of these patients, 38 regularly cycled outdoors, 21 performed recreational gymnastics, 58 participated in swimming, 50 gardened at home, 27 danced, and 43 hiked. Participation in impact sports was very limited: 7 regularly practiced tennis, 9 skied cross-country, 17 downhill skied, and 6 regularly ran more than 500 m. The authors concluded that TAA can significantly improve the quality of life to near normal and potentially allow patients to return to light recreational activities or nonimpact sporting activities. It must be noted that although participation in greater-demand/intensity activities, such as impact sports, is possible, it may carry a greater risk of component loosening, polyethylene wear, and periprosthetic fractures. Increasing interest in TAA has led to focus on its biomechanical implications and functional assessment. In an effort to describe the impact translation upon joint mobility in the Salto mobile-bearing prosthesis, an evaluation of the in vivo weight-bearing kinematics during gait and step-up in 20 patients with the Salto TAA, using fluoroscopy and 3D-to-2D registration techniques was performed by Leszko and colleagues.10 Because the ultra-high-molecular weight-polyethylene insert remained internally rotated with respect to the
285 tibial component, the average contact point on the lateral condyle during both activities was located more anterior than that on the medial condyle; a result of both rotational motion and translation. During gait, posterior translation of the center of the medial condyle, and anterior translation of the lateral condyle increases internal rotation of the insert from heel-strike to toe-off. Meanwhile, for step up, both condyles translate anteriorly, keeping internal rotation of the insert constant. However, the mean absolute range of anterior-posterior translation of the mobile-bearing insert was observed to be small; 1.5 and 2.3 mm for gait and step-up, respectively. Leszko’s findings10 with respect to anteroposterior translation complemented those of Komistek and colleagues,3 who analyzed another mobile-bearing TAA and healthy ankles, as well as those of Siegler and colleagues,17 who analyzed healthy ankle and subtalar joints. With such relatively small range of translation, it may be suggested that translations plays a less significant role in providing sufficient mobility in patients with mobile-bearing TAA systems as the Salto. Further, given that the fixed-bearing Salto Talaris TAA has up to 3-mm build into the play of the fixed bearing, such a design may provide comparable mobility and superior stability about the ankle joint.
Our Experience with the Salto Talaris TAA The senior authors (Lin, Berberian) implanted 9 Salto Talaris total ankle arthroplasties in consecutive patients from 2007 through 2008. Four males and 5 females, with a mean age of 53 years (range, 38-71 years), underwent TAA for posttraumatic (7 patients) or rheumatoid (2 patients) end-stage ankle arthritis. The right ankle was involved in 3 patients and the left ankle was involved in 6 patients. The mean weight was 198 lbs (range, 160-250 lbs), the mean height was 68.36 inches (range, 64.5-73 inches), and average body mass index was calculated to be 29.8 (range, 25.8-36.7). Significant risk factors for impaired osseous healing (ie, diabetes mellitus, alcoholism, smoking, or steroid use) were identified in 3 patients; 2 patients with rheumatoid arthritis who were being managed with chronic steroid therapy, and 1 patient with posttraumatic arthritis and a history of smoking and alcohol abuse. A previous triple arthrodesis was performed in 1 patient with rheumatoid arthritis, as well as a calcaneal slide in 1 patient. Two patients were lost to follow-up after a minimum 6-month visit; 1 patient died and 1 patient emigrated from the United States. All other reported patients have been evaluated clinically and radiographically for at least 2 years, with follow-up currently ongoing. Intraoperative procedure-related complications occurred in 2 patients, including fracture of the distal tibia in 1 patient and medial malleolar fracture in another. Both occurrences were easily identified at the time of index procedure and required open reduction and internal fixation with malleolar screw placement. Postoperatively, wound healing issues included proximal tibial tubercle pin site infections in 2 patients and 1 occurrence of wound dehiscence treated with a local rotational flap in a patient with a history of smoking and alcohol abuse. No neurovascular injuries were noted.
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Figure 3 Anteroposterior and lateral radiographs of a 58-year-old female patient with rheumatoid arthritis resulting in end-stage ankle arthritis (A, B). A Salto Talaris TAA was performed, and postoperative radiographs at 2.5 weeks (C, D), and 32 months (E, F) are shown.
The authors (Slovenkai and Jockel) from a separate center reviewed available data from 7 consecutive cases using the Salto Talaris prosthesis between 2007 and 2008, over 2 years from the original date of arthroplasty. Six females and 1 male, with a mean age of 63 years (range, 53-68 years) underwent TAA for posttraumatic (3 patients), inflammatory (2 patients), or primary degenerative (2 patients) end-stage ankle arthritis. The left ankle was involved in 6 patients, and the right ankle was involved in 1 patient. The mean patient height was 63 inches (range, 60-65 inches, mean weight was 205 lbs (range, 169-284 lbs), for an average body mass index of 36 (range 29-48). It is noted that 2 of 3 patients with posttraumatic arthritis had undergone previous open reduction internal fixation, and 2 patients underwent TAA as the second of a staged procedure: 1 patient with primary degenerative arthritis following initial subtalar arthrodesis with talocalcaneal bone cyst grafting, and 1 patient with inflammatory arthritis treated with initial stage triple arthrodesis. Additionally, 1 of 2 patients with inflammatory arthritis who underwent TAA had simultaneous talonavicular arthrodesis at the time of index procedure. One common complication after TAA in this series related to wound breakdown of the anterior approach. Three of 7 patients required further wound care until complete incision healing; 1 of which underwent debridement of superficial dehiscence, and 1 patient, a diabetic, required tibialis anterior tendon resection and VAC closure. No deep infections occurred and all prostheses were retained. One patient sustained a fracture of the posterior and medial malleoli during final tibial component placement requiring open reduction internal fixation. No neurovascular injuries occurred. Patient follow-up data revealed positive outcomes in 6 of 7 patients, with the remaining patient reporting a fair outcome. Patients were able to return to moderate exertional activities, including dancing, swimming, and extended walking distances, with peak ranges of motion from 10° dorsiflexion to 40° plantarflexion. Four patients reported intermittent soreness around the ankle, 1 patient elected for subsequent TAA of the contralateral side, and the 1 diabetic patient is scheduled for contralateral ankle arthrodesis. Clinical outcomes tended to correlate with radiographic findings, as most recent follow-up imaging revealed stable component positioning and alignment of 5 of 7 patients. Talar component subsidence occurred in 1 patient at 1-year follow-up with no further collapse at 2-year imaging. Radiographs revealed lucency around the tibial component with concern for possible loosening in 1 patient. Notably, both patients with radiographic changes had a history of inflammatory arthritis and associated chronic steroid-biological medication use, while one of these patients was also treated for adult-onset diabetes.
Conclusion Serial radiographic evaluation demonstrated ingrowth in all 9 TAAs, with no evidence of osteolysis or component subsidence (Fig. 3). Overall clinical results have correlated well with radiographic findings in all patients at last follow-up visit, with no patients limited to sedentary activity.
Total ankle arthroplasty for the management of end-stage arthritis of the ankle, remains a debated area of modern orthopedics. Guidelines for determining when to perform TAA and for choosing a specific implant are not clear-cut, although appropriate patient selection seems to be a key factor
The Salto Talaris total ankle arthroplasty system for successful outcome. Although early attempts of TAA were disappointing, recently renewed interest in this complex procedure during the past few decades has allowed for the evolution of ankle prostheses with respect to implant design, surgical technique, and instrumentation. These improvements along with increased surgeon experience has reduced the number of associated complications and hence improved clinical outcomes. The Salto Talaris TAA system, with a 2-component fixedbearing design, was developed to address the complexity of the biomechanics and anatomic relationships between the tibia and talus at the ankle joint. With its design more accurately resembling a normal anatomic ankle, the Salto Talaris aims to restore function, alleviate pain, and provide an overall improvement in quality of life for patients with severe, debilitating arthritis of the ankle. Because of its recent Food and Drug Administration approval, limited data are currently available to validate the clinical results of the Salto Talaris. Although one may extrapolate from reports of outcomes in patients with the European mobile-bearing predecessor, the Salto Total Anatomic Ankle, a need still exists for similar studies describing the outcomes of the Salto Talaris in an effort to identify strengths and/or weaknesses in design, surgical technique, and instrumentation, and justify its continued clinical utility. The authors’ report of early results in patients with the Salto Talaris prosthesis support its use as a viable alternative to ankle arthrodesis in selected patients. However, its ultimate role in the management of such patients is yet to be defined by further investigation through prospective, multicentric studies.
References 1. Fuchs S, Sandmann C, Skwara A, et al: Quality of life 20 years after arthrodesis of the ankle. A study of adjacent joints. J Bone Joint Surg Br 85:994-998, 2003
287 2. Buchner M, Sabo D: Ankle fusion attributable to posttraumatic arthrosis: a long-term followup of 48 patients. Clin Orthop Relat Res 406: 155-164, 2003 3. Komistek RD, Stiehl JB, Buechel FF, et al: A determination of ankle kinematics using fluoroscopy. Foot Ankle Int 21:343-350, 2000 4. Cracchiolo A III, Deorio JK: Design features of current total ankle replacements: implants and instrumentation. J Am Acad Orthop Surg 16:530-540, 2008 5. Thomas RH, Daniels TR: Ankle arthritis. J Bone Joint Surg Am 85:9231936, 2003 6. Hintermann B: Total Ankle Arthoplasty: Historical Overview, Current Concepts and Future Perspectives. Wien, NY, Springer, 2005 7. Salamon ML, Pinney SJ, Van Bergeyk A, et al: Surgical anatomy and accuracy of percutaneous Achilles tendon lengthening. Foot Ankle Int Jun 27:411-413, 2006 8. Knecht SI, Estin M, Callaghan JJ, et al: The agility total ankle arthroplasty. Seven to sixteen-year follow-up. J Bone Joint Surg Am 86:11611171, 2004 9. Tochigi Y, Rudert MJ, Brown TD, et al: The effect of accuracy of implantation on range of movement of the Scandinavian total ankle replacement. J Bone Joint Surg Br 87:736-740, 2005 10. Leszko F, Komistek RD, Mahfouz MR, et al: In vivo kinematics of the Salto total ankle prosthesis. Foot Ankle Int 29:1117-1125, 2008 11. Haskell A, Mann RA: Perioperative complication rate of total ankle replacement is reduced by surgeon experience. Foot Ankle Int 25:283289, 2004 12. Raikin SM, Myerson MS: Avoiding and managing complications of the agility total ankle replacement system. Orthopedics 29:930-938, 2006 13. Glazebrook MA, Arsenault K, Dunbar M: Evidence-based classification of complications in total ankle arthroplasty. Foot Ankle Int 30:945949, 2009 14. Myerson MS, Mroczek K: Perioperative complications of total ankle arthroplasty. Foot Ankle Int 24:17-21, 2003 15. Bonnin M, Judet T, Colombier JA, et al: Midterm results of the Salto total ankle prosthesis. Clin Orthop Relat Res 424:6-18, 2004 16. Bonnin MP, Laurent JR, Casillas M: Ankle function and sports activity after total ankle arthroplasty. Foot Ankle Int 30:933-944, 2009 17. Siegler S, Udupa JK, Ringleb SI, et al: Mechanics of the ankle and subtalar joints revealed through a 3D quasi-static stress MRI technique. J Biomech 38:567-578, 2005
E
nd-stage ankle arthritis is a common problem encountered by foot and ankle surgeons. For many years, ankle arthrodesis has been performed to reduce joint motion and hence provide symptomatic relief in patients with arthritic ankles. However, the major setbacks of rigid internal fixation as used in arthrodesis are reduced range of motion and disturbance of the biomechanics of adjacent joints, resulting in arthrosis.1,2 To overcome this, total ankle arthroplasty (TAA) was developed as an alternative to arthrodesis and has gained increasing popularity during the past decade among patients, surgeons, and manufacturers. Initially plagued with compli-
*Department of Orthopaedics, University of Medicine & Dentistry of New Jersey (UMDNJ), New Jersey Medical School, Newark, NJ. †Center for Foot and Ankle, Department of Orthopaedic Surgery, Orthopaedic and Rheumatology Institute, Cleveland Clinic, Cleveland, OH. ‡Department of Orthopaedic Surgery, Tufts University, School of Medicine, Boston, MA. §Foot and Ankle Center of South Texas, San Antonio, TX. Address reprint requests to Sheldon S. Lin, MD, Associate Professor, Department of Orthopaedics, University of Medicine & Dentistry of New Jersey (UMDNJ)-New Jersey Medical School, 90 Bergen Street, DOC, Suite 7300, Newark, NJ 07103. E-mail: [email protected]
282
1045-4527/10/$-see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1053/j.sart.2010.09.010
cations and failures, the evolution of TAA prosthetic design and surgical technique has occurred with better understanding of physiological ankle motion and has continued to improve clinical outcomes. Although currently not the “gold” standard treatment for end-stage ankle arthritis, TAA may become the treatment mainstay for this problem in the future. Despite the failure of early TAA designs, interest has been renewed with the development of second-generation uncemented implants with a fixed (2-component) or mobile (3component) polyethylene bearing. Featuring designs that were less constrained and more closely mimicking normal ankle anatomy, combined with improved fixation approaches, these implants provided more encouraging results than their first-generation predecessors. However, increased polyethylene wear and TAA failure caused by painful impingement, subluxation, or complete dislocation of components made apparent the need for a superior design: the third generation implant. Third-generation ankle prostheses consist of a metallic baseplate fixed to the tibia, a domed metallic component that anatomically resurfaces the talus, and a bearing surface made
The Salto Talaris total ankle arthroplasty system
283 component of the Salto Talaris requires fixed insertion of the polyethylene bearing, being slid into a tibial component tray and hence being replaceable. Its improved instrumentation allows the trial tibial component to rotate into the correct position as determined by the talar component.
Indications and Contraindications
Figure 1 Example of a Salto Talaris total ankle arthroplasty system. (Color version of figure is available online.)
of ultrahigh molecular weight polyethylene interposed between the tibial and talar components. Fixed-bearing systems include a titanium tibial component with a tibial post, a highly conforming polyethylene articulating insert, and a talar component that anatomically resurfaces the anterior/posterior and lateral surfaces. Mobile-bearing systems adapt a similar design, but the bearing component is left free between the tibial and talar components, theoretically reducing the stress on the fixation of the implants. The actual amount of relative motion that the mobile component provides in vivo compared with a fixed component is controversial.3 The newer implants also use improved osseous integration materials with in-growth characteristics that require no cement. The Salto Talaris Anatomic Ankle (Tornier, Saint-Ismier, France) is a Food and Drug Administration-approved thirdgeneration total ankle-replacement system that uses a 2-component fixed-bearing design in an effort to reduce pain, provide realignment at the ankle joint, and restore normal ankle anatomy for optimal range of motion (Fig. 1). Its design was based on the Salto mobile bearing prosthesis used in Europe, which upon initial postoperative radiographic evaluation of 20 ankles demonstrated minimal anteroposterior and varus/ valgus mobility between the polyethylene and tibial components; hence, the idea for a fixed bearing design with a similar construct.3 Improvements in design included changes to both the talar and tibial components.4 In an effort to mimic normal anatomy and biomechanics about the ankle joint, the new talar component was designed to have a conical surface with differential radii of curvature, the medial being smaller than the lateral radius. To provide stiffness at the subtalar joint and overall stability upon motion, a curved groove was also created in the sagittal plane, along with 4° of rotation around the center of curvature in the area above the subtalar joint, and a central peg.4 The tibial
Clinical indications for TAA, although not clearly defined, should be influenced by several factors, including anticipated intermediate and long-term results, and whether salvage of a TAA failure secondary to component loosening, infection, or hypertrophic bone growth would be possible.5,6 Careful patient selection is fundamental, with the procedure ideally performed in older patients (although there is no specific age requirement) with low-impact daily activity, good bone stock, no osteopenia, metabolic disorders, or systemic pharmacologic treatments that would lead to progressive deterioration of solid bone support for the implant (to allow appropriate implant fixation), no surrounding soft tissue pathology, and minimal deformity to the ankle joint (correct hind foot-ankle alignment).
Preoperative Planning Standard radiographic evaluation helps determine implant size and amount of osteophyte resection necessary for adequate exposure of the tibial joint surface and consists of anteroposterior, lateral, and mortise roentgenograms of the ankle, with contralateral comparative films obtained as needed. To evaluate bone stock and assess joint-surface defects, degenerative joint changes, or location of osteophytes, more advanced imaging, such as computed tomography, alone or in combination with arthrography, may be useful. Magnetic resonance imaging (MRI) may serve beneficial to detect the presence of avascular necrosis of the talus, which is among the contraindications for TAA. Furthermore, a bone scan can help to determine whether joints distal to the tibiotalar joint (eg, subtalar) demonstrate degenerative changes, which may require ankle fusion (tibiotalocalcaneal or staged subtalar) before arthroplasty.
Surgical Technique The tibial cut is performed first after verifying the “resection level” and “rotation and medial/lateral displacement” adjustments on the cutting guide using an external jig system. Nine millimeters of bone is usually resected from the distal tibia referenced off the tibial plafond. Rotational alignment is referenced off the talar body. The syndesmosis and distal fibular articulation is left intact when using this system. When preparing the talus, minimal chamfered bone resection is performed, with maintenance of the anatomic contour of the talus. The trial tibial base is allowed to auto-rotate into proper position to achieve appropriate alignment of the prosthesis. A tibial keel, which is referenced off the talar component, is
S.K. Mehta et al
284
Figure 2 The trial talar and tibial base components are placed (A), the joint is reduced, and the ankle is fully ranged to allow self-alignment of the tibial assembly. This is a critical step to find the “sweet spot.” Creation of the tibial keel (B) is performed by drilling the appropriate holes and using an osteotome to connect them. (Color version of figure is available online.)
subsequently formed to maintain alignment and rotation (Fig. 2). Adjunctive procedures, such as Achilles tendon lengthening or ligamentous releases, are performed on an individual basis before implantation of the final components.7 After being nonweight-bearing for 6 weeks in a cast or cam walker, the patient is progressively allowed to bear weight and perform range of motion exercises.
Conceptual Differences Between the Salto Talaris and Other Systems The Agility prosthesis (DePuy, Warsaw, IN) requires syndesmotic fusion, resulting in increased operative time, the need for bone grafting, an additional procedure for removal of hardware, and delayed weight-bearing (8 weeks).8 The Scandinavian Total Ankle Replacement (STAR; Waldemar Link, Hamburg, Germany) prosthesis is a mobile-bearing system, but theoretically there are issues, such as bearing fracture, bearing wear, and overhang with edge loading.9 In contrast, when implanting the Salto Talaris, the syndesmosis and distal fibular articulation is left intact. In addition, the Salto Talaris has a fixed bearing design that uses instruments to autorotate the tibial component to the talus to find the “ideal spot.” Even in a well-placed mobile-bearing Salto, minimal translation (⬍2 mm) and rotation (⬍3 degrees) were reported,10 supporting the fixed bearing design.
Complications Despite the newer generation of prostheses boasting an improved design and superior instrumentation, TAA remains a technically demanding surgical procedure with high complication rates and a steep learning curve. Some investigators have suggested that with greater surgeon experience, the number of intraoperative complications diminishes, optimal
alignment improves, and reliability of TAA improves.11,12 Using the Agility Total Ankle System (DePuy), Myerson and colleagues reported the occurrence of intraoperative complications in their initial 25 procedures, whereas only 2 occurred in their next 25 cases.14 Similarly, Haskell and Mann11 reported a reduction in perioperative complications with increasing surgeon experience with the STAR system. The most common complications associated with TAA are problems associated with wound healing, fractures of the medial and/or lateral malleoli, polyethylene bearing wear, and osteolysis.13 In addition, delayed union or nonunion, component subsidence, instability, bony impingement, and infection may occur.13,14 In an effort to reduce intra- and postoperative complications, surgeons must familiarize themselves with the surgical approach, plan ahead for possible variations in patient anatomy, and be comfortable with instrumentation of the TAA of their choice.
Results Although limited clinical data exist regarding the fixed-bearing Salto Talaris total ankle prosthesis, one may extrapolate from the outcomes of the earlier mobile-bearing European design (Salto Total Ankle; Tornier). Preliminary results of the Salto Total Ankle Prosthesis were described by Bonnin and colleagues15 in a prospective study evaluating 98 consecutive implants in 96 patients between 1997 and 2000. Because 2 patients were deceased, 1 patient was lost to follow-up, and 2 prostheses were removed, 93 implants in 91 patients were available for review. Sixty-two women and 36 men with a mean age of 56 years were reported with a mean follow-up of 35 months. The overall survivorship of the Salto prosthesis at 68 months when using surgical revision or radiographic loosening as the end point was reported to be 93.8% in the
The Salto Talaris total ankle arthroplasty system favorable scenario and 91.8% in the unfavorable scenario, and using implant removal as the endpoint, 98% and 94.9%, respectively. In addition, the mean American Orthopaedic Foot and Ankle Society scores were significantly improved from 32.3 ⫾ 10 points preoperatively to 83.1 ⫾ 16 points at the longest follow-up (P ⬍ 0.005). Overall range of motion as measured from dynamic radiographic also showed significant improvement from 15.2 ⫾ 10° preoperatively to 28.3 ⫾ 7° at follow-up. The authors concluded that these results were encouraging and supported the concept of anatomic replacement to improve functional outcomes, but recognized the need for longer follow-up for further validation. More recently, Bonnin and colleagues16 also retrospectively evaluated the return to sporting activities in 179 patients after implantation of a Salto TAA between 1997 and 2005 by delivering self-administered questionnaires to patients to assess foot and ankle function and ability. Of the 140 questionnaires analyzed, the mean patient age was 60.9 years, with a mean follow-up of 53.8 months, a male-tofemale ratio of 5:9, and mean body mass index of 25.6 kg/m2. The prosthesis was implanted for post-traumatic (70 ankles), primary (15 ankles), post-instability (15 ankles), or rheumatoid (40 ankles) end-stage arthritis. Overall patient satisfaction was described as normal in 15.2%, nearly normal in 60.7%, abnormal in 20%, and very abnormal in 4.1% of the patients. Furthermore, the mean Foot Function Index scores (0-100) were 13.7 ⫾ 17 for “activity limitations”, 31.7 ⫾ 23 for “disability” and 16.9⫾19 for “pain,” and the mean Foot and Ankle Ability Measurement scores were 74.9 ⫾ 18 for activities of daily living and 48.9 ⫾ 28 for sports activities. To correlate with the Foot and Ankle Ability Measure scores, subjective ankle ratings on the visual analog scales (0-100 where 100 is the “pre-pathology level”) were 70.2 ⫾ 19.6 for activities of daily living and 53.7 ⫾ 28 for sport activities. Participation in recreational sporting activities was only analyzed in patients with nonrheumatoid arthritic ankles. Of these patients, 38 regularly cycled outdoors, 21 performed recreational gymnastics, 58 participated in swimming, 50 gardened at home, 27 danced, and 43 hiked. Participation in impact sports was very limited: 7 regularly practiced tennis, 9 skied cross-country, 17 downhill skied, and 6 regularly ran more than 500 m. The authors concluded that TAA can significantly improve the quality of life to near normal and potentially allow patients to return to light recreational activities or nonimpact sporting activities. It must be noted that although participation in greater-demand/intensity activities, such as impact sports, is possible, it may carry a greater risk of component loosening, polyethylene wear, and periprosthetic fractures. Increasing interest in TAA has led to focus on its biomechanical implications and functional assessment. In an effort to describe the impact translation upon joint mobility in the Salto mobile-bearing prosthesis, an evaluation of the in vivo weight-bearing kinematics during gait and step-up in 20 patients with the Salto TAA, using fluoroscopy and 3D-to-2D registration techniques was performed by Leszko and colleagues.10 Because the ultra-high-molecular weight-polyethylene insert remained internally rotated with respect to the
285 tibial component, the average contact point on the lateral condyle during both activities was located more anterior than that on the medial condyle; a result of both rotational motion and translation. During gait, posterior translation of the center of the medial condyle, and anterior translation of the lateral condyle increases internal rotation of the insert from heel-strike to toe-off. Meanwhile, for step up, both condyles translate anteriorly, keeping internal rotation of the insert constant. However, the mean absolute range of anterior-posterior translation of the mobile-bearing insert was observed to be small; 1.5 and 2.3 mm for gait and step-up, respectively. Leszko’s findings10 with respect to anteroposterior translation complemented those of Komistek and colleagues,3 who analyzed another mobile-bearing TAA and healthy ankles, as well as those of Siegler and colleagues,17 who analyzed healthy ankle and subtalar joints. With such relatively small range of translation, it may be suggested that translations plays a less significant role in providing sufficient mobility in patients with mobile-bearing TAA systems as the Salto. Further, given that the fixed-bearing Salto Talaris TAA has up to 3-mm build into the play of the fixed bearing, such a design may provide comparable mobility and superior stability about the ankle joint.
Our Experience with the Salto Talaris TAA The senior authors (Lin, Berberian) implanted 9 Salto Talaris total ankle arthroplasties in consecutive patients from 2007 through 2008. Four males and 5 females, with a mean age of 53 years (range, 38-71 years), underwent TAA for posttraumatic (7 patients) or rheumatoid (2 patients) end-stage ankle arthritis. The right ankle was involved in 3 patients and the left ankle was involved in 6 patients. The mean weight was 198 lbs (range, 160-250 lbs), the mean height was 68.36 inches (range, 64.5-73 inches), and average body mass index was calculated to be 29.8 (range, 25.8-36.7). Significant risk factors for impaired osseous healing (ie, diabetes mellitus, alcoholism, smoking, or steroid use) were identified in 3 patients; 2 patients with rheumatoid arthritis who were being managed with chronic steroid therapy, and 1 patient with posttraumatic arthritis and a history of smoking and alcohol abuse. A previous triple arthrodesis was performed in 1 patient with rheumatoid arthritis, as well as a calcaneal slide in 1 patient. Two patients were lost to follow-up after a minimum 6-month visit; 1 patient died and 1 patient emigrated from the United States. All other reported patients have been evaluated clinically and radiographically for at least 2 years, with follow-up currently ongoing. Intraoperative procedure-related complications occurred in 2 patients, including fracture of the distal tibia in 1 patient and medial malleolar fracture in another. Both occurrences were easily identified at the time of index procedure and required open reduction and internal fixation with malleolar screw placement. Postoperatively, wound healing issues included proximal tibial tubercle pin site infections in 2 patients and 1 occurrence of wound dehiscence treated with a local rotational flap in a patient with a history of smoking and alcohol abuse. No neurovascular injuries were noted.
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Figure 3 Anteroposterior and lateral radiographs of a 58-year-old female patient with rheumatoid arthritis resulting in end-stage ankle arthritis (A, B). A Salto Talaris TAA was performed, and postoperative radiographs at 2.5 weeks (C, D), and 32 months (E, F) are shown.
The authors (Slovenkai and Jockel) from a separate center reviewed available data from 7 consecutive cases using the Salto Talaris prosthesis between 2007 and 2008, over 2 years from the original date of arthroplasty. Six females and 1 male, with a mean age of 63 years (range, 53-68 years) underwent TAA for posttraumatic (3 patients), inflammatory (2 patients), or primary degenerative (2 patients) end-stage ankle arthritis. The left ankle was involved in 6 patients, and the right ankle was involved in 1 patient. The mean patient height was 63 inches (range, 60-65 inches, mean weight was 205 lbs (range, 169-284 lbs), for an average body mass index of 36 (range 29-48). It is noted that 2 of 3 patients with posttraumatic arthritis had undergone previous open reduction internal fixation, and 2 patients underwent TAA as the second of a staged procedure: 1 patient with primary degenerative arthritis following initial subtalar arthrodesis with talocalcaneal bone cyst grafting, and 1 patient with inflammatory arthritis treated with initial stage triple arthrodesis. Additionally, 1 of 2 patients with inflammatory arthritis who underwent TAA had simultaneous talonavicular arthrodesis at the time of index procedure. One common complication after TAA in this series related to wound breakdown of the anterior approach. Three of 7 patients required further wound care until complete incision healing; 1 of which underwent debridement of superficial dehiscence, and 1 patient, a diabetic, required tibialis anterior tendon resection and VAC closure. No deep infections occurred and all prostheses were retained. One patient sustained a fracture of the posterior and medial malleoli during final tibial component placement requiring open reduction internal fixation. No neurovascular injuries occurred. Patient follow-up data revealed positive outcomes in 6 of 7 patients, with the remaining patient reporting a fair outcome. Patients were able to return to moderate exertional activities, including dancing, swimming, and extended walking distances, with peak ranges of motion from 10° dorsiflexion to 40° plantarflexion. Four patients reported intermittent soreness around the ankle, 1 patient elected for subsequent TAA of the contralateral side, and the 1 diabetic patient is scheduled for contralateral ankle arthrodesis. Clinical outcomes tended to correlate with radiographic findings, as most recent follow-up imaging revealed stable component positioning and alignment of 5 of 7 patients. Talar component subsidence occurred in 1 patient at 1-year follow-up with no further collapse at 2-year imaging. Radiographs revealed lucency around the tibial component with concern for possible loosening in 1 patient. Notably, both patients with radiographic changes had a history of inflammatory arthritis and associated chronic steroid-biological medication use, while one of these patients was also treated for adult-onset diabetes.
Conclusion Serial radiographic evaluation demonstrated ingrowth in all 9 TAAs, with no evidence of osteolysis or component subsidence (Fig. 3). Overall clinical results have correlated well with radiographic findings in all patients at last follow-up visit, with no patients limited to sedentary activity.
Total ankle arthroplasty for the management of end-stage arthritis of the ankle, remains a debated area of modern orthopedics. Guidelines for determining when to perform TAA and for choosing a specific implant are not clear-cut, although appropriate patient selection seems to be a key factor
The Salto Talaris total ankle arthroplasty system for successful outcome. Although early attempts of TAA were disappointing, recently renewed interest in this complex procedure during the past few decades has allowed for the evolution of ankle prostheses with respect to implant design, surgical technique, and instrumentation. These improvements along with increased surgeon experience has reduced the number of associated complications and hence improved clinical outcomes. The Salto Talaris TAA system, with a 2-component fixedbearing design, was developed to address the complexity of the biomechanics and anatomic relationships between the tibia and talus at the ankle joint. With its design more accurately resembling a normal anatomic ankle, the Salto Talaris aims to restore function, alleviate pain, and provide an overall improvement in quality of life for patients with severe, debilitating arthritis of the ankle. Because of its recent Food and Drug Administration approval, limited data are currently available to validate the clinical results of the Salto Talaris. Although one may extrapolate from reports of outcomes in patients with the European mobile-bearing predecessor, the Salto Total Anatomic Ankle, a need still exists for similar studies describing the outcomes of the Salto Talaris in an effort to identify strengths and/or weaknesses in design, surgical technique, and instrumentation, and justify its continued clinical utility. The authors’ report of early results in patients with the Salto Talaris prosthesis support its use as a viable alternative to ankle arthrodesis in selected patients. However, its ultimate role in the management of such patients is yet to be defined by further investigation through prospective, multicentric studies.
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