In vivo kinematics of the salto total ankle prosthesis

3D kinematics of tibiotalar motion in patients with mobile bearing and fixed bearing total ankle arthroplasty: In vivo videofluoroscopic feasibility study

BACKGROUND

As total ankle arthroplasty (TAA) is an increasingly common surgical intervention for patients with end-stage ankle arthritis, there is a need to better understand the dynamic performance of prosthetic implants during activities of daily living. Our purpose was to quantify and compare relative tibiotalar motion during gait in persons with a fixed-bearing (FB) and mobile-bearing (MB) total ankle arthroplasty. We hypothesized a FB prosthesis would have lower tibiotalar range of motion (ROM).

METHODS

Patients at least 12 months postoperative with either a FB (n=5) or MB (n=3) total ankle arthroplasty were tested. We used high-speed biplanar videoradiography to quantify tibiotalar kinematics during self-selected gait. Angular and linear ROM in three axes were compared between the groups.

RESULTS

ROM for dorsiflexion-plantarflexion, internal-external rotation, and inversion-eversion angles in FB subjects averaged 7.47±4.05°, 7.39±3.63°, and 4.51±2.13°, respectively. ROM in MB subjects averaged 6.74±2.04°, 6.28±4.51°, and 5.68±2.81°, respectively. Linear ROM along anteroposterior, mediolateral, and superior-inferior axes in FB subjects averaged 1.47±2.07 mm, 1.13±1.49 mm, and 0.28±0.30 mm, respectively. Linear ROM in MB subjects averaged 0.68±1.44 mm, 0.60±1.41 mm, and 0.20±0.13 mm, respectively. We found no significant difference between the two groups for any of these ROM parameters (p>0.05).

CONCLUSION

Total ankle arthroplasty using either FB or MB design appears to confer similar ankle motion during the gait cycle in this biplanar fluoroscopic model.

LEVEL OF EVIDENCE

Level IV, case series.

Standing on shoulder of giants: the incredible legacy of the Judet family in orthopaedic surgery

In orthopaedic surgery, as well as other areas in medicine, it is common for a surgical technique to carry the original authors' name describing the procedure. The Judet family represents a unique history, since several orthopaedic procedures are known as "Judet's technique". The aim of this historic review is to outline the genealogy of the orthopaedic arm of the Judet family, while crediting each surgical procedure to the specific family member that described the technique.

In Vivo Total Ankle Arthroplasty Kinematic Evaluation: A Prospective Radiostereometric Analysis

Ankle osteoarthritis (OA) represents a significant social burden and is one of the main causes of chronic disability in a rapidly growing part of the world's population. Total ankle arthroplasty (TAA) has become increasingly popular despite the poor results obtained with the first dedicated designs. The purpose of this paper was to evaluate the ankle kinematics, in vivo and under weight-bearing conditions, of a TAA through a dynamic model-based radiostereometric analysis (MB-RSA). The clinical evaluation was performed by administering the American Orthopaedic Foot and Ankle Society ankle-hindfoot score and Short Form-36 questionnaires. The kinematic evaluation was conducted through MB-RSA during the execution of an open kinetic chain and a closed kinetic chain motor task. Double radiographic images of the ankle joint were processed using dedicated software to obtain a 3D reconstruction of the ankle prosthetic components' motion. Eighteen patients (five females) completed the clinical and instrumental preoperative and postoperative evaluations (age 59.1 ± 10.3). All clinical scores showed a marked improvement (p < 0.005). During the closed kinetic chain motor tasks, the ankle showed a total range of motion (ROM) in dorsi-plantarflexion of 19.84°. The parameters in varus-valgus were recorded. Physiological motion can be achieved in TAA, characterized by a wide range of motion and coupling of movements on the three planes. The results of the present work may help to understand the real movement of a widespread TAA model and possibly to improve future designs and instrumentation.

Outcomes of Total Ankle Arthroplasty After Reoperation due to Gutter Impingement

Gutter impingement is one of the most common causes of subsequent surgery after total ankle arthroplasty (TAA). Although gutter debridement has been reported to resolve preoperative symptoms early on, persistent pain after surgery, recurrence, and poor functional outcome scores have been described in patients who have undergone reoperation for gutter debridement. The cause of gutter impingement after TAA is multifactorial, and a better understanding of its causes and optimal surgical techniques for intervention is needed.

Total Ankle Arthroplasty Survivorship, Complication, and Revision Rates in Patients Younger Than 55 Years

Total ankle replacement has become a viable alternative to ankle arthrodesis in the surgical management of advanced ankle arthritis. Total ankle replacement has generally been reserved for patients who are older and for those who will have a lower demand on the replacement. The purpose of the current study is to review patient outcomes, complications, and implant survival in patients younger than 55 years who underwent total ankle replacement at a single institution. A single-center chart and radiographic review was performed of consecutive patients who underwent total ankle replacement for treatment of end-stage ankle arthritis. All surgeries were performed by 1 of 5 fellowship-trained foot and ankle surgeons at a single institution. A total of 51 patients met inclusion criteria with a mean follow-up of 31.2 months (SD = 16.2). Implant survival was 94%, There were 7 major complications (13%) requiring an unplanned return to the operating room and 8 minor complications (15%) that resolved with conservative care. The results of this study show that total ankle replacement is a viable treatment option for patients younger than 55 years.Levels of Evidence: A retrospective case series.

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

BACKGROUND

To measure the motion of polyethylene insert and implant components of mobile-bearing total ankle replacement (TAR) by cone-beam CT scanning.

METHODS

10 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.

RESULTS

The 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.

CONCLUSION

We 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.

Assignment of local coordinate systems and methods to calculate tibiotalar and subtalar kinematics: A systematic review

The introduction of biplane fluoroscopy has created the ability to evaluate in vivo motion, enabling six degree-of-freedom measurement of the tibiotalar and subtalar joints. Although the International Society of Biomechanics defines a standard method of assigning local coordinate systems for the ankle joint complex, standards for the tibiotalar and subtalar joints are lacking. The objective of this systematic review was to summarize and appraise the existing literature that (1) defined coordinate systems for the tibia, talus, and/or calcaneus or (2) assigned kinematic definitions for the tibiotalar and/or subtalar joints. A systematic literature search was developed with search results limited to English Language from 2006 through 2020. Articles were screened by two independent reviewers based on title and abstract. Methodological quality was evaluated using a modified assessment tool. Following screening, 52 articles were identified as having met inclusion criteria. Methodological assessment of these articles varied in quality from 61 to 97. Included articles adopted primary methods for defining coordinate systems that included: (1) anatomical coordinate system (ACS) based on individual bone landmarks and/or geometric shapes, (2) orthogonal principal axes, and (3) interactive closest point (ICP) registration. Common methods for calculating kinematics included: (1) joint coordinate system (JCS) to calculate rotation and translation, (2) Cardan/Euler sequences, and (3) inclination and deviation angles for helical angles. The methods each have strengths and weaknesses. This summarized knowledge should provide the basis for the foot and ankle biomechanics community to create an accepted standard for calculating and reporting tibiotalar and subtalar kinematics.

Return to Sports and Activity After Total Ankle Arthroplasty and Arthrodesis: A Systematic Review

BACKGROUND

There is no consensus regarding participation in sports and recreational activities following total ankle replacement (TAR) and ankle arthrodesis (AA). This systematic review summarizes the evidence on return to sports and activity after operative management with either TAR or AA for ankle osteoarthritis (OA).

METHODS

A literature search of MEDLINE, EMBASE, CINAHL, and Cochrane Library databases was performed. Risk of bias of included studies was assessed using Methodological Index for Non-Randomized Studies (MINORS) criteria. Included studies reported sport and activity outcomes in patients undergoing TAR and AA, with primary outcomes being the percentage of sports participation and level of sports participation.

RESULTS

Twelve studies met inclusion criteria for analysis. There were 1270 ankle procedures, of which 923 TAR and 347 AA were performed. The mean reported patient age was 59.2 years and the mean BMI was 28 kg/m². The mean follow-up was 43 months. Fifty-four percent of patients were active in sports preoperatively compared with 63.7% postoperatively. The mean preoperative activity participation rate was 41% in the TAR cohort, but it improved to 59% after TAR, whereas the preoperative activity participation rate of 73% was similar to the postoperative rate of 70% in the AA cohort. The most common sports in the TAR and AA groups were swimming, hiking, cycling, and skiing.

CONCLUSION

Participation in sports activity was nearly 10% improved after operative management of ankle OA with TAR and remains high after AA. The existing literature demonstrated a large improvement in pre- to postoperative activity levels after TAR, with minimal change in activity after AA; however, AA patients were more active at baseline. The most frequent postoperative sports activities after operative management of ankle OA were swimming, hiking, cycling, and skiing. Participation in high-impact sports such as tennis, soccer, and running was consistently limited after surgery. This review of the literature will allow patients and foot and ankle surgeons to set evidence-based goals and establish realistic expectations for postoperative physical activity after TAR and AA.

LEVEL OF EVIDENCE

Level III, systematic review.

In vivo kinematics of fixed-bearing total ankle arthroplasty

BACKGROUND

A good recovery of the physiological mobility of the ankle is an indication of patients' satisfaction after total ankle arthroplasty, which does not generally match that of other consolidated procedures such as hip and knee replacement. The aim of this study was to investigate the kinematics of the Zimmer Total Metal Total Ankle (ZTMTA) during the different exercises.

METHODS

Fifteen patients with ZTMTA were enrolled in this study. The patients performed non-weightbearing flexion-extension, stair climbing and descending, and fluoroscopic images were taken to capture the ankle movements. A combined images/three-dimensional models method was used to perform a kinematic analysis.

RESULTS

Plantar-dorsiflexion resulted the main plane of movement, with the largest range of motion (ROM) of 23.3 ± 9.0° during flexion-extension. Inversion-eversion and adduction-abduction resulted lower than 10° in any trials.

CONCLUSIONS

In the investigated population, the ZTMTA allowed a good recovery of the mobility, with ROMs comparable to the healthy subjects.

Positive and negative factors for the treatment outcomes following total ankle arthroplasty? A systematic review

BACKGROUND

Patient selection, surgeon's experience and implant design play an integral role and affect the treatment outcomes of total ankle arthroplasty (TAA). The aims of this study were to investigate the positive and negative attributes that correlate with different clinical and radiographic outcomes.

METHODS

Eight-nine studies matched the inclusion criteria: (1) studies of primary TAA with uncemented prosthesis; (2) mean follow-up of no less than 2-year; (3) reports of clinical and radiographic outcomes, and exclusion criteria: (1) non-English study; (2) more than one type of prosthesis without separated data; (3) kin studies with shorter follow-up or smaller cohort. Age, etiology, preoperative deformity, surgeon's experience, follow-up duration and prosthetic type were studied with respect to different outcomes by mixed-effects logistic regression analysis.

RESULTS

Patients factor: older patients reported less pain or stiffness and demonstrated less radiographic loosening which did not require additional surgical intervention. More traumatic arthritis experienced adjacent joints degeneration after TAA. Surgeon factor: less experienced surgeons had more intraoperative complications. Lack of experience for complications management without implant retrieval during early period might result in more revisions or fusion was done. Prosthetic factor: updated instrumentation decreased malalignment. If the polyethylene (PE) insert was significantly narrower than the metal components more implant instability and subsequent severe particulate wear was seen. Designs with flat-on-flat articulation and ridge at the center of the talar component associated with more PE fracture. Minimal bone resection reduced postoperative fractures. A flat cut of the tibial component and a flat undersurface with press-fit by two screws or pegs of the talar component demonstrated less postoperative fractures, whereas a syndesmosis fusion and a small triangular shape with one central fin of the talar component experienced more loosening which did not require additional surgery. Anatomic conical shape of the talar component seemed to reduce adjacent joint degeneration. Finally, fewer failures were found in patients who received HINTEGRA and Salto Talaris.

CONCLUSIONS

Based on our investigation, some positive and negative factors for different clinical and radiographic outcomes were found, which should be taken into consideration in clinical practice and ankle implant design.

Design Rationale for Total Ankle Arthroplasty Systems: An Update

The design of total ankle arthroplasty systems is evolving as a result of findings from longer-term studies. Our understanding of modes of failure has increased, and surgical techniques have become more refined. Currently, five total ankle arthroplasty systems are used in the United States. The landscape has changed considerably in the decade since the latest article reviewing total ankle design was published. Some implants with acceptable intermediate results had much poorer outcomes at 7- to 10-year follow-up. As more research showing mid- to long-term outcomes is published, the design rationale and current outcomes data for each of these implants must be considered.

Fixed and mobile-bearing total ankle prostheses: Effect on tibial bone strain

BACKGROUND

Total ankle replacement is associated to a high revision rate. To improve implant survival, the potential advantage of prostheses with fixed bearing compared to mobile bearing is unclear. The objective of this study was to test the hypothesis that fixed and mobile bearing prostheses are associated with different biomechanical quantities typically associated to implant failure.

METHODS

With a validated finite element model, we compared three cases: a prosthesis with a fixed bearing, a prosthesis with a mobile bearing in a centered position, and a prosthesis with mobile bearing in an eccentric position. Both prostheses were obtained from the same manufacturer. They were tested on seven tibias with maximum axial compression force during walking. We tested the hypothesis that there was a difference of bone strain, bone-implant interfacial stress, and bone support between the three cases. We also evaluated, for the three cases, the correlations between bone support, bone strain and bone-implant interfacial stress.

FINDINGS

There were no statistically significant differences between the three cases. Overall, bone support was mainly trabecular, and less effective in the posterior side. Bone strain and bone-implant interfacial stress were strongly correlated to bone support.

INTERPRETATIONS

Even if slight differences are observed between fixed and mobile bearing, it is not enough to put forward the superiority of one of these implants regarding their reaction to axial compression. When associated to the published clinical results, our study provides no argument to warn surgeons against the use of two-components fixed bearing implants.

Motion at the Tibial and Polyethylene Component Interface in a Mobile-Bearing Total Ankle Replacement

BACKGROUND

Normal biomechanics of the ankle joint includes sagittal as well as axial rotation. Current understanding of mobile-bearing motion at the tibial-polyethylene interface in total ankle arthroplasty (TAA) is limited to anterior-posterior (AP) motion of the polyethylene component. The purpose of our study was to define the motion of the polyethylene component in relation to the tibial component in a mobile-bearing TAA in both the sagittal and axial planes in postoperative patients.

METHODS

Patients who were a minimum of 12 months postoperative from a third-generation mobile-bearing TAA were identified. AP images were saved at maximum internal and external rotation, and the lateral images were saved in maximum plantarflexion and dorsiflexion. Sagittal range of motion and AP translation of the polyethylene component were measured from the lateral images. Axial rotation was determined by measuring the relative position of the 2 wires within the polyethylene component on AP internal and external rotation imaging. This relationship was compared to a table developed from fluoroscopic images taken at standardized degrees of axial rotation of a nonimplanted polyethylene with the associated length relationship of the 2 imbedded wires. Sixteen patients were included in this investigation, 9 (56%) were male and average age was 68 (range, 49-80) years. Time from surgery averaged 25 (range, 12-38) months.

RESULTS

Total sagittal range of motion averaged 23±9 (range, 9-33) degrees. Axial motion for total internal and external rotation of the polyethylene component on the tibial component averaged 6±5 (range, 0-18) degrees. AP translation of the polyethylene component relative to the tibial component averaged 1±1 (range, 0-3) mm. There was no relationship between axial rotation or AP translation of the polyethylene component and ankle joint range of motion (P > .05).

CONCLUSION

To our knowledge, this is the first investigation to measure axial and sagittal motion of the polyethylene component at the tibial implant interface in patients following a mobile-bearing TAA. Based on outcome scores and range-of-motion measurements, we believe the patients in this study are a representative cross section of subjects compared to other TAA research results. The results from this investigation indicate the potential for a mobile-bearing TAA to fall within the parameters of normal polyaxial ankle motion. The multiplanar articulation in a mobile-bearing TAA may reduce excessively high peak pressures during the complex dynamic tibial and talar motion, which may have a positive influence on gait pattern, polyethylene wear, and implant longevity.

LEVEL OF EVIDENCE

Level IV, case series.

Arthroscopic Debridement After Total Ankle Arthroplasty

BACKGROUND

Residual pain due to impingement after ankle arthroplasty can be addressed with arthroscopic debridement. Literature focusing on the effectiveness of arthroscopic debridement after total ankle arthroplasty (TAA) is scarce. The authors report a case series of 12 patients complaining of anterior or posterior impingement pain, 11 of which were in the absence of malalignment which were treated by arthroscopy.

METHODS

Of the 106 TAAs performed between 2003 and 2012, a total of 12 subjects reported postoperative pain resulting from anterior or anteromedial impingement, medial and/or lateral gutter impingement, posterior impingement, and/or ankylosis. All patients were reviewed on a regular basis through chart review, clinical examination, and radiologic evaluation. The average time to final follow-up was 58.8 months. The average period from the original TAA to the arthroscopic debridement was 38.2 months.

RESULTS

The median AOFAS hindfoot score was significantly (P < .05) improved from 64.6 preoperatively to 73.5 postoperatively. Eight subjects reported good pain relief after the arthroscopic debridement, and partial pain relief was reported by 4 subjects. Three patients with painful ankylosis had no improvement in the total range of motion of the TAA implant after the arthroscopic debridement.

CONCLUSION

The results suggest that arthroscopic debridement in patients with residual pain due to impingement syndromes after TAA was effective in 8 of the 12 cases at 2 years' follow-up. However, the results suggest that arthroscopic debridement in the presence of painful ankylosis associated with or without impingement syndromes results only in partial pain relief and does not improve the range of motion.

LEVEL OF EVIDENCE

Level IV, case series.

Early radiographic and clinical results of Salto total ankle arthroplasty as a fixed-bearing device

BACKGROUND

Total ankle replacement has increased in popularity in the management of severe tibiotalar arthritis. Most previous clinical reports focused on mobile-bearing designs. This study evaluates early radiographic and clinical results of the Salto fixed bearing design.

METHODS

Twenty-three Salto fixed-bearing implants were prospectively studied. Records were reviewed for clinical outcome scores (VAS, AOFAS, SF36), subsequent surgeries, complications, radiographic data and implant survivorship. Average follow-up was 36 months.

RESULTS

Statistically significant improvements in VAS, AOFAS ankle/hindfoot scores, and SF36 scores were shown at an average of 3 years postoperatively. At 3 years followup, survivorship of the implant was 82.6% with any reoperation as the endpoint and 95.6% for revision or removal of components. Seven patients had radiolucencies around the implant, one of which required revision to arthrodesis.

CONCLUSION

The fixed-bearing Salto ankle replacement has comparable early radiographic and clinical results to reports of the mobile-bearing Salto of comparable followup.

LEVEL OF EVIDENCE

Level IV.

Incidence of revision after primary implantation of the Salto ® mobile version and Salto Talaris ™ total ankle prostheses: a systematic review

The incidence of revision of total ankle replacement prostheses remains unclear. We undertook a systematic review to identify the material relating to the incidence of revision after implantation of the Salto(®) mobile version and Salto Talaris™ total ankle prostheses. Studies were eligible for inclusion only if they had involved primary total ankle replacement with these prostheses and had included the incidence of revision. Eight studies involving 1,209 Salto(®) mobile version prostheses, with a weighted mean follow-up period of 55.2 months, and 5 studies involving 212 Salto Talaris™ total ankle prostheses, with a weighted mean follow-up period of 34.9 months, were included. Forty-eight patients with Salto(®) mobile version prostheses (4%) underwent revision, of whom 24 (70.5%) underwent ankle arthrodesis, 9 (26.5%) metallic component replacement, and 1 (3%) below-the-knee amputation. Five (2.4%) Salto Talaris™ total ankle prostheses underwent revision (3 metallic component replacement and 2 ankle arthrodeses). Restricting the data to the inventor, design team, or disclosed consultants, the incidence of revision was 5.2% for the Salto(®) mobile version and 2.6% for the Salto Talaris™ total ankle prostheses. In contrast, data that excluded these individuals had an incidence of revision of 2.8% for the Salto(®) mobile version and 2.0% for the Salto Talaris™ total ankle prostheses. We could not identify any obvious difference in the etiology responsible for the incidence of revision between these mobile- and fixed-bearing prostheses. The incidence of revision for the Salto(®) mobile version and Salto Talaris™ total ankle prostheses was lower than those reported through systematic review for the Agility™ and Scandinavian Total Ankle Replacement™ systems without obvious selection (inventor) or publication (conflict of interest) bias.

Force-controlled dynamic wear testing of total ankle replacements

Currently, our knowledge of wear performance in total ankle replacements is limited. The aim of this study is to develop a scenario for force-controlled testing and wear testing of total ankle replacements. A force-controlled wear test was developed: based on cadaver measurements, the passive stabilization (ligaments and soft tissue) of the ankle joint was characterized and a restraint model for ankle stabilization was developed. Kinematics and kinetics acting at the replaced ankle joint were defined based on literature data and gait analysis. Afterwards, force-controlled wear testing was carried out on a mobile, three-component, total ankle replacement design. Wear was assessed gravimetrically and wear particles were analyzed. Wear testing resulted in a mean wear rate of 18.2±1.4mm(3)/10(6) cycles. Wear particles showed a mean size of 0.23μm with an aspect ratio of 1.61±0.96 and a roundness of 0.62±0.14. Wear testing of total ankle replacement shows that a relevant wear mass is generated with wear particles in a biologically relevant size range. The developed wear test provides a basis for future wear testing of total ankle replacements.

Comparison of quality of life following total ankle arthroplasty and ankle arthrodesis: Retrospective study of 54 cases

INTRODUCTION

The benefit of ankle arthroplasty compared to arthrodesis continues to be debated, but the quality of life after these two interventions has rarely been assessed. We conducted a case-control study to compare quality of life and functional and athletic ability.

HYPOTHESIS

Functional results, athletic ability, and quality of life after total ankle arthroplasty (TAA) are better than after ankle arthrodesis.

MATERIAL AND METHODS

Two continuous series of 59 TAAs and 46 arthrodeses (operated on between 1997 and 2009) were evaluated retrospectively using a questionnaire including the functional items of the AOFAS score, the Foot Function Index (FFI) score, the Foot Ankle Ability Measure (FAAM), and the SF-36.

RESULTS

Eighty-three responses (79% of the overall series) were matched in two groups: 32 TAAs [age at the intervention, 51.4years (range, 21-63years); follow-up, 52.2months (range, 30-146months); age at revision, 55.8years (range, 26-67years); BMI, 27.7 (range, 21.7-36.7)] and 22 arthrodeses [age at intervention, 50.1years (range, 24-72years); follow-up 57.9months (range, 12-147months); age at revision 54.9 years (range, 31-75years); BMI, 26.8 (range, 17.6-37)] (NS on all items between the two groups). The pain results were better after TAA, but with no statistically significant difference: AOFAS pain, (/40) 28.1±8.2 vs. 24.5±9.6; FFI pain, 16.6±18.8 vs. 24.3±21.5. The overall FFI score (/100) was better (P=0.048) after TAA (16.2±16.5 vs. 24.8±18.2). The overall mean athletic level compared to the state prior to the injury was relatively low in both groups, but significantly (p=0.007) higher in the TAA group: FAAM sports score (/100), 49.5±24.4 vs. 29.8±26.2. The quality-of-life scores, SF-36 physical health, mental health, and general health were not significantly different after TAA and arthrodesis: mental health score, 63.1±14.7 vs. 57.8±21.5; physical health score, 61.3±17.8 vs. 53.7±23.9, overall score, 63.2±16.4 vs. 55.9±23.5.

DISCUSSION

Very few publications describe activities and quality of life after TAA and arthrodesis. Despite weaknesses, this comparative study demonstrates a tendency toward better functional results after TAA than after ankle arthrodesis, without the difference between the two groups being very significant. On the other hand, there was no difference in terms of quality of life. After the doubts raised by publications on severe periprosthetic osteolysis at the intermediate term with certain TAA models, these results encourage pursuit of implantation and development of TAA.

LEVEL OF PROOF

Comparative retrospective. Level III study.

A controlled, comparative study of a fixed-bearing versus mobile-bearing ankle arthroplasty

BACKGROUND

Total ankle arthroplasty is available with fixed-bearing (FB) or mobile-bearing (MB) versions, and there is little consensus on the benefits and drawbacks of each type. This study aimed to compare clinical outcomes of statistically paired series of FB and MB versions of the same ankle prosthesis.

METHODS

The study was a multicenter retrospective comparison between 2 groups: the FB group of 33 consecutive Talaris cases and the MB group of 33 "paired" Salto cases, selected from a database of 313 consecutive cases to statistically match etiology, age, and preoperative American Orthopaedic Foot & Ankle Society (AOFAS) score. All patients were operated upon with the same operative technique and received identical pre- and postoperative clinical and radiographic assessments. The mean follow-up was 24 months for the FB group and 23 months for the MB group.

RESULTS

There was no statistical difference between results of the 2 groups in terms of accuracy of positioning, clinical and radiographic mobility, and morbidity. The most recent postoperative AOFAS scores were higher for the FB group than for the MB group (P = .05). Radiolucent lines were observed in 4 FB patients versus 13 MB patients (P = .02). Subchondral cysts were noted in 1 FB patient and in 8 MB patients (P = .01).

CONCLUSION

There was no notable difference in clinical performance of the FB and MB implants with the numbers available. This short-term study demonstrated that FB ankle arthroplasty had results equivalent to, if not better than, MB ankle arthroplasty. Longer follow-up is necessary to determine the success of this new generation of ankle arthroplasty.

LEVEL OF EVIDENCE

Level III, retrospective case control study.

Prospective study of the effect on gait of a two-component total ankle replacement

BACKGROUND

The purpose of this study was to evaluate the functional outcome as measured by prospective gait analysis of patients undergoing total ankle arthroplasty using a 2-component Salto Talaris total ankle prostheses with a fixed polyethylene bearing.

METHODS

Twenty-one patients with severe ankle arthritis who underwent unilateral total ankle arthroplasty using a 2-component Salto Talaris device with a fixed polyethylene bearing were studied prospectively. Mean age was 69 years in 16 female and 5 male patients, and mean follow-up was 37.2 (range, 24-50) months. Three-dimensional gait analysis was performed using a 12-camera digital-motion capture system preoperatively and repeated at a minimum of 2 years postoperatively. Temporospatial measurements included velocity, cadence, step length, and support times. Measured kinematic parameters included sagittal plane range of motion of the ankle, knee, and hip. Kinetic parameters included sagittal plane ankle power and ankle plantarflexion moment.

RESULTS

There was significant improvement in temporospatial parameters, including step length (P = .014) and walking velocity, which increased from 0.9 to 1 m/s (P = .01). Kinematic results showed sagittal plane range of motion of the ankle increased significantly from a mean of 15.8 degrees preoperatively to 20.6 degrees (P = .00005) postoperatively with the increase occurring primarily in dorsiflexion. Kinetic results showed ankle peak power increased from a mean of 0.7 Nm/kg to 1.1 Nm/kg (P = .004).

CONCLUSIONS

A prospective study of gait in patients undergoing total ankle arthroplasty using a 2-component Salto Talaris device with a fixed polyethylene bearing showed, at midterm follow-up, significant improvements in multiple parameters of gait when compared to the patients' own preoperative function.

LEVEL OF EVIDENCE

Level IV, prospective case series.

Hindfoot motion following STAR total ankle arthroplasty: a multisegment foot model gait study

BACKGROUND

One of the rationales for total ankle arthroplasty (TAA) is that it may retard the changes of hypermobility and accelerated arthritis in the hindfoot after ankle arthrodesis. Until recently, it has not been possible to quantify or even objectively demonstrate biomechanical findings to substantiate the theory that postsurgical biomechanical changes in the ankle produce changes in the kinematics of the hindfoot. Standard gait analysis has treated the foot as a single biomechanical unit. This study was undertaken to describe the hindfoot motion following Scandinavian Total Ankle Replacement (STAR) TAA by using multisegment foot model gait analysis.

METHODS

Forty-six patients with a mean age of 66 years underwent a 3D gait analysis following TAR. Mean interval between surgery and gait analysis was 4.9 years (range 2 to 9). The contralateral limb was used as control for each patient. Temporospatial variables and kinematic parameters were studied.

RESULTS

Temporospatial results showed statistically significant differences. Stance time on the affected side was 61.1% ± 2.2% of the gait cycle compared to 63.2% ± 2.1% for the unaffected side. Step length was 55.6 cm ± 10 on the affected side compared to 53.9 cm ± 10 for the unaffected side. Kinematics results were statistically significant: Ankle range of motion (ROM) on the arthroplasty side was 16.8 ± 4.5 degrees compared to 23.6 ± 5.0 on the unaffected side. Sagittal plane ROM was 12.7 ± 4.2 degrees on the arthroplasty side and 17.3 ± 3.5 degrees on the unaffected side. Coronal plane ROM was 4.7 ± 2.4 degrees on the arthroplasty side and 7.5 ± 2.4 degrees on the unaffected side. Transverse plane ROM on the arthroplasty side was 4.1 ± 1.5 degrees and 4.9 ± 1.6 on the unaffected side.

CONCLUSION

This study showed that, in addition to previously documented diminution in sagittal plane motion and gait velocity, some of the residual abnormalities of gait following TAR were comprised of differences in hindfoot function. These results relate to the growing recognition of the importance of understanding hindfoot mechanics apart from those of the tibiotalar joint.

LEVEL OF EVIDENCE

Level III, comparative case series.

Comparison of gait after total ankle arthroplasty and ankle arthrodesis

BACKGROUND

Prior studies reported improved gait after total ankle arthroplasty and better parameters of gait than those reported in earlier studies of patients after ankle arthrodesis. However, there are very limited data prospectively evaluating the effects on gait after ankle arthroplasty compared with ankle arthrodesis. Controversy remains regarding the relative advantages and disadvantages of these 2 treatments and especially the differences in function between them.

METHODS

We performed a prospective study involving 28 patients with posttraumatic and primary ankle osteoarthritis and a control group of 14 normal volunteers. We compared gait in 14 patients who had undergone ankle arthrodesis with the gait of 14 patients who had ankle arthroplasty preoperatively and at 1 year postoperatively. Three-dimensional gait analysis was performed with a 12-camera digital-motion capture system. Temporospatial measurements included stride length and cadence. The kinematic parameters that were measured included the sagittal plane range of motion of the ankle and the coronal plane range of motion of the ankle. Double force plates were used to collect kinetic parameters such as ankle coronal and plantar flexion-dorsiflexion moments and sagittal plane ankle power. Center of pressure (CoP) and its progression in gait cycle were calculated.

RESULTS

Baseline parameters showed comparability among the treatment and control groups. Temporospatial analysis, using time as the main effect, showed that compared with ankle arthrodesis, patients with total ankle arthroplasty had higher walking velocity attributable to both increases in stride length and cadence as well as more normalized first and second rockers of the gait cycle. Kinematic analysis, using time and intervention as the main effects, showed that patients who had ankle arthroplasty had better sagittal dorsiflexion (P = .001), whereas those undergoing ankle arthrodesis had better coronal plane eversion (P = .01). Neither ankle arthrodesis nor arthroplasty altered the CoP progression during stance phase. Total ankle arthroplasty produced a more symmetrical vertical ground reaction force curve, which was closer to that of the controls than was the curve of the ankle arthrodesis group.

CONCLUSIONS

Patients in both the arthrodesis and arthroplasty groups had significant improvements in various parameters of gait when compared with their own preoperative function. Neither group functioned as well as the normal control subjects. Neither group was superior in every parameter of gait at 1 year postoperatively. However, the data suggest that the major parameters of gait after ankle arthrodesis in deformed ankle arthritis are comparable to gait function after total ankle arthroplasty in nondeformed ankle arthritis.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Functional performance of a total ankle replacement: thorough assessment by combining gait and fluoroscopic analyses

BACKGROUND

A thorough assessment of patients after total ankle replacement during activity of daily living can provide complete evidence of restored function in the overall lower limbs and replaced ankle. This study analyzes how far a possible restoration of physiological mobility in the replaced ankle can also improve the function of the whole locomotor apparatus.

METHODS

Twenty patients implanted with an original three-part ankle prosthesis were analyzed 12 months after surgery during stair climbing and descending. Standard gait analysis and motion tracking of the components by three-dimensional fluoroscopic analysis were performed on the same day using an established protocol and technique, respectively.

FINDINGS

Nearly physiological ankle kinematic, kinetic and electromyography patterns were observed in the contralateral side in both motor activities, whereas these patterns were observed only during stair climbing in the operated side. Particularly, the mean ranges of flexion at the replaced ankle were 13° and 17° during stair climbing and descending, respectively. Corresponding 2.1 and 3.1mm antero/posterior meniscal-to-tibial translations were correlated with flexion between the two metal components (p<0.05). In addition, a larger tibiotalar flexion revealed by fluoroscopic analysis resulted in a physiological hip and knee moment.

INTERPRETATION

The local and global functional performances of these patients were satisfactory, especially during stair climbing. These might be associated to the recovery of physiological kinematics at the replaced ankle, as also shown by the consistent antero/posterior motion of the meniscal bearing, according to the original concepts of this ankle replacement design.

Salto Talaris fixed-bearing total ankle replacement system

The Salto Talaris total ankle replacement is an anatomically designed fixed bearing prosthesis available in the United States based on the successful design of the mobile-bearing Salto prosthesis available outside the United States. The original mobile-bearing design was modified and the mobile-bearing was transferred to the precision instrumentation at the trial phase evaluation. Instrumentation and technique allow the surgeon to determine the functional joint axis before final implantation. The Salto Talaris total ankle replacement design blends minimal bone resection and optimizes surface area, cortical contact, and ultra-high molecular weight polyethylene conformity. The authors present an overview of the Salto Talaris total ankle replacement surgical technique and pearls for successful application.

A functional outcome study comparing total ankle arthroplasty (TAA) subjects with pain to subjects with absent level of pain by means of videofluoroscopy

BACKGROUND

Total ankle arthroplasty (TAA) subjects often suffer pain on the anteromedial side of their ankle joint. Whether this prevalent pain is caused by a changed motion pattern of the TAA is unclear. Therefore, this study assessed the kinematic differences in the motion of the TAA components during gait, comparing TAA subjects with elevated versus absent levels of pain.

METHODS

Eleven TAA subjects (5 with pain vs. 6 without pain), all with unilateral Mobility™ TAA and at least two years post-operation, were recruited and stratified based on standard clinical assessed patient data. The 3D motion of the TAA was assessed by means of videofluoroscopy during level, uphill and downhill walking.

RESULTS

The hypothesis that the pain group shows a different kinematic motion pattern than the no pain group could not be confirmed.

CONCLUSIONS

The same kinematic motion pattern causes pain in some patients, but not in others. Further investigation concerning ligament stresses is needed.

In vivo kinematics and articular surface congruency of total ankle arthroplasty during gait

Relatively high rates of loosening and implant failure have been reported after total ankle arthroplasty. Abnormal kinematics and incongruency of the articular surface may cause increased contact pressure and rotational torque applied to the implant, leading to loosening and implant failure. We measured in vivo kinematics of two-component total ankle arthroplasty (TNK ankle), and assessed congruency of the articular surface during the stance phase of gait. Eighteen ankles of 15 patients with a mean age of 75±6 years (mean±standard deviation) and follow-up of 44±38 months were enrolled. Lateral fluoroscopic images were taken during the stance phase of gait. 3D-2D model-image registration was performed using the fluoroscopic image and the implant models, and three-dimensional kinematics of the implant and incongruency of the articular surface were determined. The mean ranges of motion were 11.1±4.6°, 0.8±0.4°, and 2.6±1.5° for dorsi-/plantarflexion, inversion/eversion, and internal/external rotation, respectively. At least one type of incongruency of the articular surface occurred in eight of 18 ankles, including anterior hinging in one ankle, medial or lateral lift off in four ankles, and excessive axial rotation in five ankles. Among the four ankles in which lift off occurred during gait, only one ankle showed lift off in the static weightbearing radiograph. Our observations will provide useful data against which kinematics of other implant designs, such as three-component total ankle arthroplasty, can be compared. Our results also showed that evaluation of lift off in the standard weightbearing radiograph may not predict its occurrence during gait.

Kinematics of the three components of a total ankle replacement: in vivo fluoroscopic analysis

BACKGROUND

Careful kinematic analysis of ankle joints with newly developed prostheses should be carried out to assess the actual performance in vivo. This study analyzed the pattern of motion of the three components of a ligament-compatible ankle replacement, developed to replicate normal joint kinematics.

MATERIALS AND METHODS

Twelve patients treated with this design were analyzed at 6, 12, and 24 months followup. A series of images were acquired by videofluoroscopy at extremes of the range of motion, and during flexion/extension against gravity and stair-climbing/descending. Three-dimensional positions and orientations of the tibial and talar metal components and of the polyethylene mobile-bearing were obtained from the images by a standard shape-matching procedure. Motion between the three components was calculated and descriptively analyzed.

RESULTS

Large tibiotalar joint mobility of the replaced ankle was observed in all three anatomical planes, particularly in the sagittal. In flexion/extension against gravity, the mean range of flexion was 17.6, 17.7, and 16.2 degrees, respectively, over the three followups. The inclination angle of the mean axis of joint rotation was 3.7 degrees down and lateral in the frontal plane and 4.7 degrees posterior and lateral in the transverse plane, similar to those in the normal ankle. The corresponding antero-posterior translation of the meniscal-bearing with respect to the tibia was 3.3, 3.3, and 3.2 mm, with statistically significant correlation with joint flexion.

CONCLUSION

Physiological motion can be achieved in ligament-compatible ankle joint replacements. The considerable antero-posterior bearing-to-tibial motion and its coupling with flexion support the main original claims of this design.

Prospective study of a cementless, mobile-bearing, third generation total ankle prosthesis

BACKGROUND

The SALTO total ankle prosthesis is a noncemented mobile bearing anatomic design characterized by dual Ti-HA coating. This study reviews our results with this prosthesis.

MATERIALS AND METHODS

Between 2001 and 2007, 413 consecutive SALTO prostheses were implanted in our institution in 215 women and 198 men, aged 57.1 +/- 11.9 years. At the last visit, 401 implants (47% in the left ankle) were available with a mean followup of 29 (range, 1 to 84) months.

RESULTS

Based on the results of the 218 patients with at least 2 years of postoperative followup, the 5-year estimated survivorship, with the primary end-point being implant removal, was 86.6% and ranged from 85.1% in patients with post-traumatic osteoarthritis to 95.6% in those with rheumatoid arthritis. The AOFAS score increased from 50.9 +/- 16.8 points preoperatively to 82.2 +/- 14 points at followup (mean difference, 31.1 +/- 1.4, 95% confidence interval (C.I.) for the difference, 28.3 to 33.8, p < 0.001). Visual analog scale for pain decreased from 7.4 +/- 1.1 preoperatively to 2.0 +/- 2.0 postoperatively (mean difference, -5.4 +/- 0.7, 95% C.I. for the difference, -5.6 to -5.2, p < 0.001). Flexion/extension ROM increased from 25.2 +/- 14.1 degrees to 33.1 +/- 13.6 degrees at the last followup visit (mean difference, 7.9 +/- 0.5 degrees, 95% C.I. for the difference, 4.3 to 7.2, p < 0.001), while pronation/supination ROM increased from 23.8 +/- 13.7 degrees to 25.4 +/- 14.5 degrees (mean difference, 1.6 +/- 0.7 degrees, 95% C.I. for the difference, 0.9 to 2.2, p = 0.005).

CONCLUSION

The SALTO prosthesis provided good clinical and functional results and we believe helps validate the concept of anatomic replacement.

Position of the prosthesis components in total ankle replacement and the effect on motion at the replaced joint

PURPOSE

In some cases of total ankle replacement, perfect alignment of the prosthetic components is not achieved. This study analyses the extent to which component positioning is critical for the final range of motion.

METHODS

Fourteen patients undergoing total ankle replacement were assessed preoperatively and postoperatively at seven and 13 months follow-up. X-ray pictures of the ankle were taken in static double leg stance, i.e. at neutral joint position, and in maximum plantarflexion and dorsiflexion. Measurements were obtained by a specially devised computer program based on anatomical reference points digitised on the radiograms. These allowed calculation of the position and orientation of the components in the sagittal and coronal planes, together with the joint range of motion.

RESULTS

The mean range of motion was about 34 degrees at the first follow-up and maintained at the second. Tibial and talar components were more anterior than the mid-tibial shaft in 11 and nine patients, respectively. Mean inclination was about four degrees posterior for the tibial component and nearly one degree anterior for the talar component. A significantly larger range of motion was found in ankles both with the talar component located and inclined more anteriorly than the tibial.

CONCLUSIONS

Correlation, though weak, was found between motion at the replaced ankle and possible residual subluxation and inclination of the components. However, a satisfactory range of motion was also achieved in those patients where recommended locations for the components could not be reached because of the size of the original joint deformity.

The Salto total ankle arthroplasty: survivorship and analysis of failures at 7 to 11 years

BACKGROUND

Despite the appearance of new-generation, mobile-bearing, cementless prostheses, total ankle arthroplasty remains controversial. Among the criteria guiding the choice between arthrodesis and arthroplasty, the long-term survival and postoperative function are of critical importance. The mobile-bearing Salto prosthesis has been used in Europe since 1997, but only 2 to 5 years of followup data have been reported.

QUESTIONS/PURPOSES

We analyzed the longer-term survivorship and causes of failures of the Salto prosthesis in a cohort of previously studied patients. We asked whether this prosthesis provided a functional ankle (AOFAS score) and durable radiographic fixation.

PATIENTS AND METHODS

We retrospectively reviewed 96 prospectively followed patients with 98 prostheses implanted between 1997 and 2000. Of those, 85 patients (87 prostheses) had a minimum followup of 6.8 years (mean, 8.9 years; range, 6.8-11.1 years).

RESULTS

The survival rate was 65% (95% CI, 50-80) with any reoperation of the ankle and 85% (95% CI, 75-95) with revision of a component as the end points. Six prostheses were removed for arthrodesis, and 18 ankles underwent reoperation without arthrodesis. We observed three main causes of reoperations: bone cysts (11 patients), fracture of the polyethylene (five patients), and unexplained pain (three patients). The mean AOFAS score was 79 ± 12 points. Radiographic subsidence was observed in three patients and bone cysts in eight patients.

CONCLUSIONS

Our data suggest a high rate of reoperations but only six revisions with arthrodesis with mid-term followup. We observed few patients with loosening and/or subsidence.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Effect of ankle flexion angle on axial alignment of total ankle replacement

BACKGROUND

The Salto Talaris Anatomic® (Tornier) total ankle replacement (TAR) has found widespread use in the United States and features rotationally mobile trial components that auto-align the final components, which themselves are rotationally fixed and highly congruent. Based on recent work on prosthetic and native ankle kinematics, we investigated the influence of the ankle flexion angle at the time of final component preparation on the axial alignment of the Salto Talaris TAR.

MATERIALS AND METHODS

Following a power analysis based on a clinically meaningful difference of five degrees, eight fresh-frozen cadaveric thigh-to-foot specimens underwent installation of trial components using the Salto Talaris TAR system. Specimens were cycled from maximal dorsiflexion (DF) to plantarflexion (PF), as called for in the surgical technique guide, and drilling for the final component was carried out in both five degrees of DF and 15 degrees of PF using separate drill holes. These were compared with a reference drill hole previously placed along the axis of distal tibial cutting guide. Data were analyzed to determine whether components prepared in DF differed from those prepared in PF with respect to median (and variance) rotation.

RESULTS

We found no significant difference in median axial alignment (p = 0.139) or in variances between the two groups (p=0.937).

CONCLUSION

The ankle flexion angle at the time of final component preparation did not significantly alter the axial alignment of the Salto Talaris TAR.

CLINICAL RELEVANCE

Therefore, the rotational alignment of the tibial component is determined by the tibial bone cuts and will not auto-align to the rotation of the talar component.

Clinical evaluation and radiographic assessment of bone lysis of the AES total ankle replacement

BACKGROUND

AES mobile-bearing total ankle replacement is evolved from the Buechel Pappas model. We report medium-term results of a prospective study with AES.

MATERIALS AND METHODS

All patients who underwent AES TAR for ankle arthritis, by a single surgeon, from 2003 to 2006 were included, excluding neurologic disease, talar osteonecrosis and malalignment more than 20 degrees. All were reviewed at 6 months, 1 year, and at yearly intervals thereafter. X-rays were analyzed by three observers, using a 10-zone protocol. Fifty consecutive AES implants in 47 patients (mean age, 56 years; range, 21 to 79 year) were included, with at least 2 years' followup (mean 40 months). Preoperative diagnosis was mainly post-traumatic (50%) and osteoarthritis secondary to instability (36%). Associated procedures were performed in 38%.

RESULTS

Eighty-two percent had good functional results. The mean AOFAS score rose from 36.9 +/- 1.7 preoperatively to 85.4 +/- 12, dorsiflexion from 3 degrees to 7.3 degrees, and plantarflexion from 30.8 degrees to 37.8 degrees. Two ankles underwent secondary arthrodesis for talar subsidence and mechanical dislocation. Ninety-eight percent of implants were well positioned at 90 degrees +/-4. Mean prosthesis ROM on X-ray was 22.1 degrees. There were tibia/implant interface cysts (greater than 5 mm) in 62% of cases, and talar/implant interface cysts in 43%.

CONCLUSION

Although functional outcomes were comparable to the other mobile TAR in the literature, bone lysis with the AES prosthesis was more frequent with risk of subsidence. We therefore stopped implantation of this prosthesis and recommend preventive grafting for severe lysis.

Ankle function and sports activity after total ankle arthroplasty

BACKGROUND

The return to sporting activities after ankle arthroplasty has rarely been evaluated. The purpose of the present study was to evaluate function and return to sports after total ankle arthroplasty.

MATERIALS AND METHODS

One hundred seventy-nine Salto Total Ankle Arthroplasties (TAA) were implanted between 1997 and 2005. A self-administered questionnaire including the Foot Function Index (FFI) and Foot and Ankle Ability Measurement (FAAM) was sent to all patients. At last followup, six were deceased, 22 were not available for evaluation, and six questionnaires were incomplete. One hundred forty-five questionnaires were available. The mean age was 60.9 years and the mean followup was 53.8 months. The main indications for TAA were osteoarthritis (OA) in 100 cases and Rheumatoid arthritis (RA) in 40 cases.

RESULTS

15.2% of the patients said that their operated ankle was "normal'' 60.7%" nearly normal''; 20% "abnormal'' and 4.1% "highly abnormal.'' The FFI scores were 13.7 +/- 17 for "activity limitations'', 31.7 +/- 23 for "disability'' and 16.9 +/- 19 for "pain''. The FAAM scores were 74.9 +/- 18 for activities of daily living and 48.9 +/- 28 for sports activities. On a Visual Analog Scales (0 to 100 were 100 is the "pre-pathology level'') the mean rating was 70.2 +/- 19.6 for Activities of Daily Living and 53.7 +/- 28 for sport activities. In the OA patients, 38 regularly road bicycle, 21 perform recreational gymnastics, 58 swimming, 50 home gardening, 27 dancing, and 43 hiking. Seven patients regularly practice tennis, nine cross-country skiing, 17 downhill skiing, and six regularly run more than 500 m.

CONCLUSION

This study showed that TAA improved the quality of life and that return to recreational activities was generally possible but the return to impact sport was rarely possible.