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

Printable functionally graded tibial implant for TAR: FE study comparing implant materials, FGM properties, and implant designs

Tibial implants with functionally graded material (FGM) for total ankle replacement (TAR) can provide stiffness similar to the host tibia bone. The FGM implants with low stiffness reduce stress shielding but may increase implant-bone micromotion. A trade-off between stress shielding and implant-bone micromotion is required if FGMs are to substitute traditionally used Ti and CoCr metal implants. The FGM properties such as material gradation law and volume fraction index may influence the performance of FGM implants. Along with the FGM properties, the design of FGM implants may also have a role to play. The objective of this study was to examine FGM tibial implants for TAR, by comparing implant materials, FGM properties, and implant designs. For this purpose, finite element analysis (FEA) was conducted on 3D FE models of the intact and the implanted tibia bone. The tibial implants were composed of CoCr and Ti, besides them, the FGM of Ti and HA was developed. The FGM implants were modelled using exponential, power, and sigmoid laws. Additionally, for power and sigmoid laws, different volume fraction indices were taken. The effect of implant design was observed by using keel type and stem type TAR fixation designs. The results indicated that FGM implants are better than traditional metal implants. The power law is most suitable for developing FGM implants because it reduces stress shielding. For both power law and sigmoid law, low values of the volume fraction index are preferrable. Therefore, FGM implant developed using power law with 0.1 vol fraction index is ideal with the lowest stress shielding and marginally increased implant-bone micromotion. FGM implants are more useful for keel type fixation design than stem type design. To conclude, with FGMs the major complication of stress shielding can be solved and the longevity and durability of TAR implants can be enhanced.

Ten-year revision rates of contemporary total ankle arthroplasties equal 22%. A meta-analysis

BACKGROUND

The National Institute for Health and Care Excellence criterion for hip replacements is a (projected) revision rate of less than 5% after 10 years. No such criterion is available for ankle prostheses. The objective of the current study is to compare survival rates of contemporary primary ankle prostheses to the hip-benchmark.

METHODS

The PRISMA methodology was used. Eligible for inclusion were clinical studies reporting revision rates of currently available primary total ankle prostheses. Data was extracted using preconstructed forms. The total and prosthesis-specific annual revision rate was calculated.

RESULTS

Fifty-seven articles of eight different ankle prostheses were included (n = 5371), totaling 513 revisions at an average 4.6 years of follow-up. An annual revision rate of 2.2 was found (i.e. an expected revision rate of 22% at 10 years).

CONCLUSIONS

The expected 10-year revision rate of contemporary ankle prostheses is lower than the current benchmark for hip prostheses.

Outcomes and Complications of the INFINITY Total Ankle: A Systematic Review

IV.

Three-Year Rates of Reoperation and Revision Following Mobile Versus Fixed-Bearing Total Ankle Arthroplasty: A Cohort of 302 Patients with 2 Implants of Similar Design

BACKGROUND

Currently, the implants utilized in total ankle arthroplasty (TAA) are divided between mobile-bearing 3-component and fixed-bearing 2-component designs. The literature evaluating the influence of this mobility difference on implant survival is sparse. The purpose of the present study was therefore to compare the short-term survival of 2 implants of similar design from the same manufacturer, surgically implanted by the same surgeons, in fixed-bearing or mobile-bearing versions.

METHODS

All patients were enrolled who underwent TAA with either the mobile-bearing Salto (Tornier and Integra) or the fixed-bearing Salto Talaris (Integra) in 3 centers by 2 surgeons between January 2004 and March 2018. All patients who underwent TAA from January 2004 to April 2013 received the Salto implant, and all patients who underwent TAA after November 2012 received the Salto Talaris implant. The primary outcome was time, within 3 years, to first all-cause reoperation, revision of any metal component, and revision of any component, including the polyethylene insert. Secondary outcomes included the frequency, cause, and type of reoperation.

RESULTS

A total of 302 consecutive patients were included, of whom 171 received the mobile-bearing and 131 received the fixed-bearing implant. The adjusted hazard ratio for all-cause reoperation was 1.42 (95% confidence interval [CI], 0.67 to 3.00; p = 0.36); for component revision, 3.31 (95% CI, 0.93 to 11.79; p = 0.06); and for metal component revision, 2.78 (95% CI, 0.58 to 13.33; p = 0.20). A total of 31 reoperations were performed in the mobile-bearing group compared with 14 in the fixed-bearing group (p = 0.07). More extensive reoperation procedures were performed in the mobile-bearing group.

CONCLUSIONS

With the largest comparison of 2 implants of similar design from the same manufacturer, the present study supports the use of a fixed-bearing design in terms of short-term failure. We found a 3-times higher rate of revision among mobile-bearing implants compared with fixed-bearing implants at 3 years after TAA. Reoperations, including first and subsequent procedures, tended to be less common and the causes and types of reoperations less extensive among fixed-bearing implants.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Correlation of Patient-Reported Outcomes With Physical Function After Total Ankle Arthroplasty

BACKGROUND

Total ankle arthroplasty (TAA) is successful by both subjective patient-reported outcome measures (PROMs) and objective functional improvements of gait. Each is reproducible and valid, but they are entirely distinct methods. This study investigated the correlation between subjective and objective outcomes of TAA.

METHODS

Seventy patients underwent gait analysis preoperatively and 1 year after TAA. The 36-Item Short-Form Health Survey (SF-36) and visual analog score (VAS) for pain and American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot Scores were recorded at each interval. A Student t test, a multivariate regression, and a Pearson correlation coefficient were used to measure the correlation between parameters of gait and PROMs.

RESULTS

Patients had statistically significant improvements in gait velocity, total range of motion (ROM), maximum plantarflexion, ankle power, and SF-36 Physical, VAS, and AOFAS scores. The SF-36 Physical score had a moderate positive correlation with preoperative walking speed, step length, and ankle power and postoperative walking speed and ankle power. No correlation between VAS score and function was detected. The AOFAS score had a moderate positive correlation with postoperative walking speed, step length, and ankle power, and improvement in walking speed, cadence, and ankle power.

CONCLUSION

Statistically significant correlations were found between numerous preoperative and postoperative comparisons of PROMs and the AOFAS score with the objective biomechanical outcomes of gait. Walking speed and ankle push-off power correlated most with patient perceptions of function and improvement, while pain and ROM did not. Subjective PROMs and objective biomechanical outcomes were complementary in the assessment of surgical outcomes and, combined, helped to address the dilemma of the confounding effect of other lower extremity pathologies on PROMs.

LEVEL OF EVIDENCE

Level III, comparative series.

Correlation of Single-Photon Emission Computed Tomography Results With Clinical and Intraoperative Findings in Painful Total Ankle Replacement

BACKGROUND

Evaluating pain after total ankle replacement (TAR) is often difficult, and traditional imaging modalities do not always adequately assess potential etiologies of failure. Our study adds to the current understanding of single-photon emission computed tomography combined with conventional computed tomography (SPECT-CT) as a diagnostic tool for painful TAR. We hypothesized that SPECT-CT would be predictive of clinical and intraoperative findings and would be more useful than magnetic resonance imaging (MRI) in our cohort.

METHODS

A retrospective review of SPECT-CT imaging performed at our institution in patients with painful TAR from January 2014 to November 2018 was conducted. A total of 37 patients were identified, and 28 of them underwent revision surgery. Additionally, 19 patients had an MRI during the same time frame. Imaging results were compared to the documented clinical findings and intraoperative findings during revision surgery.

RESULTS

Of the 37 patients included, 89.2% (33/37) had SPECT-CT results that were consistent with the ultimate diagnosis documented in the medical record. Aseptic loosening (12/33) and impingement (11/33) were the most common diagnoses. Among patients who underwent revision surgery, SPECT-CT results were consistent with intraoperative findings in 26 of the 28 (92.9%) cases. In the 19 patients who also underwent MRI, the findings were consistent with clinical findings 36.8% (7/19) of the time.

CONCLUSION

In our cohort, there was high consistency between SPECT-CT results and documented clinical diagnoses. SPECT-CT also demonstrated high consistency with intraoperative findings during revision surgery. Compared with MRI, SPECT-CT proved more useful in establishing a diagnosis of pain after TAR.

LEVEL OF EVIDENCE

Level III, comparative series.

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.

Mid-Term Prospective Clinical and Radiographic Outcomes of a Modern Fixed-Bearing Total Ankle Arthroplasty

The early outcomes of the Salto Talaris® Total Ankle Prosthesis have been promising, but information on its mid-term outcomes is still sparse. The purpose of this study was to evaluate the mid-term clinical and radiographic outcomes of this implant among a prospective cohort of patients who underwent total ankle replacement for various etiologies. Forty-six patients (50 ankles) were consecutively enrolled in the study. Our primary aim was to assess implant survivorship as determined by the removal or revision of the implant metal components or conversion to arthrodesis. Our secondary aim was to gauge patient outcomes by using commonly used outcome scores and assess ankle range of motion using goniometric and radiographic methods. We report 100% survivorship of the implant at a mean follow-up of 4.9 years. Compared with preoperative levels, all clinical outcome scores showed significant improvement at the 1-year, 2-year, and 5-year and longer follow-up. The mean clinical ROM improved from 27.7° ± 10.7° preoperatively to 40.0° ± 12.3° at the 2-year follow-up (p < .001). The mean radiographic ROM improved from 23.0° ± 10.2° preoperatively to 27.2° ± 9.1° at the 2-year follow-up (p = .007). Reoperations or secondary procedures were performed on 6 (12%) ankles, with the most common procedure being gutter debridement for impingement symptoms. The study confirms that the excellent survivorship seen with the implant in the early studies extends to mid-term follow-up as well. Patients could expect to see improvement in pain relief and activity well into 5 years after surgery and retain sufficient ankle range of motion for normal gait.

The Salto total ankle arthroplasty - Clinical and radiological outcomes at five years

BACKGROUND

Modern designs of total ankle arthroplasty (TAA) have the potential to treat symptomatic ankle OA without adversely affecting ankle biomechanics. We present the mid-term results of a modern, mobile-bearing TAA design.

METHODS

TAA was performed in 50 consecutive patients (55 ankles) in an independent, prospective, single-centre series. Implant survival, patient-reported outcome measures (PROMs) and radiographic outcomes are presented at a mean of five years (range 2-10.5years).

RESULTS

A total of three patients (four ankles) died and two (two ankles) were lost to follow-up. Three TAAs were revised for aseptic loosening (in two cases) or infection. Two further patients underwent reoperations, one for arthroscopic debridement of anterolateral synovitis and one for grafting of an asymptomatic tibial cyst. With all-cause revision as an endpoint, implant survival was 93.3% at five to ten years (95% CI 80.5%-97.8%). If reoperations are included this falls to 90.2% (95% CI 75.6%-96.3%) at five years. No other patient demonstrated radiographic evidence of loosening or subsidence. PROMs and satisfaction were excellent at latest follow-up.

CONCLUSION

At five years, the outcomes for this design of TAA in this series were excellent, and were similar to those of previously published series from the designer centre.

Short-Term Complications, Reoperations, and Radiographic Outcomes of a New Fixed-Bearing Total Ankle Arthroplasty

BACKGROUND

With the increasing use of total ankle arthroplasty (TAA), new implants with varied configurations are being developed every year. This study aimed to assess the early complications, reoperations, and radiographic and clinical outcomes of the Infinity TAA. To date, clinical results of this novel implant have not been published.

METHODS

A retrospective analysis of 64 consecutive ankles that underwent a primary Infinity TAA from July 2014 to April 2016 was performed. Patients had an average follow-up of 24.5 (range, 18-39) months. Medical records were reviewed to determine the incidence of complications, reoperations, and revisions. Radiographic outcomes included preoperative and postoperative tibiotalar alignment, tibial implant positioning, the presence of periprosthetic radiolucency and cysts, and evidence of subsidence or loosening. Additionally, patient-reported outcomes were analyzed with the Foot and Ankle Outcome Score (FAOS).

RESULTS

Survivorship of the implant was 95.3%. Fourteen ankles (21.8%) presented a total of 17 complications. A total of 12 reoperations were necessary in 11 ankles (17.1%). Revision surgery was indicated for 3 ankles (4.7%) as a result of subsidence of the implant. Tibiotalar coronal deformity was significantly improved after surgery ( P < .0001) and maintained during latest follow-up ( P = .81). Periprosthetic radiolucent lines were observed around the tibial component in 20 ankles (31%) and around the talar component in 2 ankles (3.1%). A tibial cyst was observed in 1 ankle (1.5%). Outcome scores were significantly improved for all FAOS components analyzed ( P < .0001), from 39.0 to 83.3 for pain, from 34.0 to 65.2 for symptoms, from 52.3 to 87.5 for activities of daily living, and from 15.7 to 64.2 for quality of life.

CONCLUSION

Most complications observed in the study were minor and successfully treated with a single reoperation procedure or nonoperatively. Failures and radiographic abnormalities were most commonly related to the tibial implant. Further studies with longer follow-up are needed to evaluate the survivorship of the tibial implant in the long term.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Scandinavian Total Ankle Replacement: 15-Year Follow-up

BACKGROUND

Over the past decade, total ankle arthroplasty (TAA) has become a mainstay in the treatment of end-stage ankle arthritis. Currently in its fourth generation, the Scandanavian Total Ankle Replacement (STAR) is the only 3-piece mobile bearing ankle prosthesis available in the United States. Our current study reports implant survivorship at 15 years and patient outcomes for a subset of these survivors available for study.

METHODS

Eighty-four TAAs were performed between 1998 and 2000. Metal component survivorship at 15 years was calculated with a Kaplan-Meier curve. Twenty-four (29%) of 84 patients were available for participation with a minimum 15-year follow-up. Any radiographic changes were documented. All additional procedures and complications were recorded. Clinical findings, self-reported performance and pain evaluations, and AOFAS ankle/hindfoot scores were noted.

RESULTS

Metal implant survival was 73% at 15 years. Of the 24 patients available for clinical evaluation, 18 of 24 patients (70.7%) had no change in prosthetic alignment from the immediate postoperative radiograph. Only 1 subtalar fusion was required for symptomatic adjacent joint arthritis. Three patients sustained a broken polyethylene component. AOFAS scores improved from an average of 39.6 points preoperatively, to an average of 71.6. More than half (52.4%) of patients with retained implants required an additional surgical procedure; 3 required 2 additional procedures. The average time to subsequent procedure was 10.2 years.

CONCLUSION

Our small cohort demonstrated STAR ankles with retention at 9 years were highly likely to survive to 15 years, and patients continued to have significant improvement in pain relief and minimal decrease in function. At 15 years from TAA, metal survivorship was 73%. As with all ankle replacements, supplementary procedures were common.

LEVEL OF EVIDENCE

Level IV, case series.

Short-term Clinical and Radiographic Results of the Salto Mobile Total Ankle Prosthesis

BACKGROUND

The mobile-bearing Salto total ankle prosthesis has been reported to have promising outcomes. However, clinical reports on this prosthesis are few, and most have been published by the inventors and disclosed consultants.

METHODS

We retrospectively reviewed 59 patients who received Salto prosthesis unilaterally. The average follow-up was 35.9 (range, 6-56) months. Clinical and radiologic results were evaluated. Clinical results were evaluated according to visual analog scale (VAS), American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, Ankle Osteoarthritis Scale (AOS) pain and disability score, and ankle range of motion (ROM) in dorsiflexion/plantarflexion. In the radiographic evaluation, we measured the tibial angle (TA), talar angle (TAL), tibial slope, and talocalcaneal angle (TCA) on weightbearing radiographs.

RESULTS

By the last follow-up, 7 of 59 patients (11.9%) had undergone reoperation, and 3 of 59 implants (5.1%) had been removed. The prosthesis survival was 94.9% (95% CI, 89.1%-100%). With any reoperation as the endpoint of follow-up, the clinical success rate was 88.1% (95% CI, 79.4%-96.9%). The mean postoperative visual analog scale score, AOFAS ankle-hindfoot score, and Ankle Osteoarthritis Scale pain and disability score improved significantly ( P < .001). The ankle range of motion also improved from preoperative 33.4 ± 16.6 to 40.3 ± 15.5 postoperatively ( P < .001); however, there was no statistically significant change in plantarflexion ( P = .243). Radiolucent areas and osteolysis were found in 28 (47.5%) and 27 (45.8%) patients, respectively. Heterotopic ossification was observed in 13 patients (22.0%).

CONCLUSIONS

In this series, early clinical and radiographic outcomes of this prosthesis were promising. We believe the early radiolucent lines were probably due to the gap at the implant and bone interface, and they disappeared at the time of osseous integration. However, longer follow-up is necessary to determine the long-term durability and survivorship of this implant, particularly given the high incidence of postoperative osteolysis.

LEVEL OF EVIDENCE

Level IV, case series.

Single-Surgeon Experience and Complications of a Fixed-Bearing Total Ankle Arthroplasty

BACKGROUND

Total ankle arthroplasty (TAA) has historically resulted in inferior survivorship rates compared with total hip and knee arthroplasty, because of technical issues unique to ankle anatomy. In this study, a single-surgeon series of intra- and postoperative complications as well as resultant reoperations/revisions of the Tornier Salto Talaris, a fixed-bearing TAA prosthesis, were reviewed.

METHODS

Medical records from index procedure to latest follow-up of primary TAA were reviewed. Complications were categorized according to the Glazebrook classification; additional complications were documented. Concurrent procedures were recorded, and radiographs were analyzed for alignment, subsidence, and cyst formation. Time to complication onset and learning curve analyses were performed. One hundred four Salto Talaris TAA prostheses (96 patients), with an average follow-up of 46 months, were included.

RESULTS

Thirty-five complications were identified in 32 ankles with a 34% complication rate, resulting in 11 reoperations (5 TAA revisions). Technical error (n = 12), wound healing (n = 9), and aseptic loosening (n = 4) were the most common complications, and there were no statistically significant differences in demographics or follow-up duration between cases with versus without complications. In both the cohorts with and without complications, there were moderate, negative correlations between radiographically observed keel osteopenia and lucency (ρ = -0.548, P = .00125, and ρ = -0.416, P = .000303, respectively); also, in the complication cohort, a weak, positive correlation between subsidence and lucency (ρ = 0.357, P = .0450) was found.

CONCLUSION

Salto Talaris TAA survivorship and reoperation rates in our series were comparable with previous reports, using either the same or similar mobile-bearing prostheses; new information regarding complication, radiographic, and learning curve analyses was presented.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Midterm Results of the Salto Talaris Total Ankle Arthroplasty

BACKGROUND

The Salto Talaris total ankle replacement is a modern fixed-bearing implant used to treat symptomatic ankle arthritis with the goals of providing pain relief, restoring mechanical alignment, and allowing motion of the ankle joint. The goal of this study was to report the midterm clinical results of one of the largest cohort of patients in the United States who underwent ankle replacement with this prosthesis.

METHODS

This is a review of patients with a minimum of 5 years up to 10 years' follow-up. At the preoperative visit and each annual assessment, patients rated their current level of pain using the visual analog score (VAS) and reported their functional level using the American Orthopaedic Foot & Ankle (AOFAS) ankle-hindfoot scores, the Short Musculoskeletal Function Assessment (SMFA), and the Short Form-36 (SF-36) Health survey. These scores were analyzed to assess differences between their levels preoperatively, 1 year postoperatively, and at their most recent follow-up. Criteria for failure was defined as revision requiring exchange or removal of the metallic components for any reason. We identified 106 patients having a Salto Talaris total ankle replacement. Seventy-two patients (mean age, 61.9 years) met the minimum requirement for follow-up (range 60-115 months, mean 81.1 months).

RESULTS

Significant improvements were seen in the VAS, SMFA, AOFAS score, and SF-36 from preoperatively to their final follow-up ( P < .001). Survivorship was 95.8% for those with at least 5-year follow-up, with 2 patients undergoing revision arthroplasty for aseptic loosening and a third patient scheduled for revision for a chronic wound infection. Fourteen patients (19%) required an additional surgery for a total of 17 additional operative procedures on the ipsilateral ankle or hindfoot.

CONCLUSION

Patients undergoing total ankle arthroplasty with the Salto Talaris prosthesis continued to show significant improvements in pain and functional outcomes at midterm follow-up. This prosthesis has shown to be an effective treatment option with durable results.

LEVEL OF EVIDENCE

Level IV, therapeutic, case series.

Are There Differences in Gait Mechanics in Patients With A Fixed Versus Mobile Bearing Total Ankle Arthroplasty? A Randomized Trial

BACKGROUND

Total ankle arthroplasty (TAA) is an alternative to arthrodesis, but no randomized trial has examined whether a fixed bearing or mobile bearing implant provides improved gait mechanics.

QUESTIONS/PURPOSES

We wished to determine if fixed- or mobile-bearing TAA results in a larger improvement in pain scores and gait mechanics from before surgery to 1 year after surgery, and to quantify differences in outcomes using statistical analysis and report the standardized effect sizes for such comparisons.

METHODS

Patients with end-stage ankle arthritis who were scheduled for TAA between November 2011 and June 2013 (n = 40; 16 men, 24 women; average age, 63 years; age range, 35-81 years) were prospectively recruited for this study from a single foot and ankle orthopaedic clinic. During this period, 185 patients underwent TAA, with 144 being eligible to participate in this study. Patients were eligible to participate if they were able to meet all study inclusion criteria, which were: no previous diagnosis of rheumatoid arthritis, a contralateral TAA, bilateral ankle arthritis, previous revision TAA, an ankle fusion revision, or able to walk without the use of an assistive device, weight less than 250 pounds (114 kg), a sagittal or coronal plane deformity less than 15°, no presence of avascular necrosis of the distal tibia, no current neuropathy, age older than 35 years, no history of a talar neck fracture, or an avascular talus. Of the 144 eligible patients, 40 consented to participate in our randomized trial. These 40 patients were randomly assigned to either the fixed (n = 20) or mobile bearing implant group (n = 20). Walking speed, bilateral peak dorsiflexion angle, peak plantar flexion angle, sagittal plane ankle ROM, peak ankle inversion angle, peak plantar flexion moment, peak plantar flexion power during stance, peak weight acceptance, and propulsive vertical ground reaction force were analyzed during seven self-selected speed level walking trials for 33 participants using an eight-camera motion analysis system and four force plates. Seven patients were not included in the analysis owing to cancelled surgery (one from each group) and five were lost to followup (four with fixed bearing and one with mobile bearing implants). A series of effect-size calculations and two-sample t-tests comparing postoperative and preoperative increases in outcome variables between implant types were used to determine the differences in the magnitude of improvement between the two patient cohorts from before surgery to 1 year after surgery. The sample size in this study enabled us to detect a standardized shift of 1.01 SDs between group means with 80% power and a type I error rate of 5% for all outcome variables in the study.

RESULTS

This randomized trial did not reveal any differences in outcomes between the two implant types under study at the sample size collected. In addition to these results, effect size analysis suggests that changes in outcome differ between implant types by less than 1 SD. Detection of the largest change score or observed effect (propulsive vertical ground reaction force [Fixed: 0.1 ± 0.1; 0.0-1.0; Mobile: 0.0 ± 0.1; 0.0-0.0; p = 0.0.051]) in this study would require a future trial to enroll 66 patients. However, the smallest change score or observed effect (walking speed [Fixed: 0.2 ± 0.3; 0.1-0.4; Mobile: 0.2 ± 0.3; 0.0-0.3; p = 0.742]) requires a sample size of 2336 to detect a significant difference with 80% power at the observed effect sizes.

CONCLUSIONS

To our knowledge, this is the first randomized study to report the observed effect size comparing improvements in outcome measures between fixed and mobile bearing implant types. This study was statistically powered to detect large effects and descriptively analyze observed effect sizes. Based on our results there were no statistically or clinically meaningful differences between the fixed and mobile bearing implants when examining gait mechanics and pain 1 year after TAA.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Operative Wound Complications Following Total Ankle Arthroplasty

BACKGROUND

Wound complications following total ankle replacement (TAR) potentially lead to devastating consequences. The aim of this study was to compare the operative and demographic differences in patients with and without major wound problems which required operative management. We hypothesized that increased tourniquet and operative time would negatively influence wound healing.

METHODS

We identified a consecutive series of 762 primary TARs performed between December 1999 and April 2014 whose data were prospectively collected. We then identified the subset of patients who required a secondary surgery to treat major wound complications (ie, operative debridement, split-thickness skin grafting, and soft tissue reconstruction). All patients requiring a second surgery had operative wound debridement. We then compared the demographics, operative characteristics, and functional scores to see if any differences existed between patients with and without major wound complications. Clinical outcomes including secondary procedures and implant failure rates were recorded.

RESULTS

Twenty-six patients (3.4%) had a total of 49 operative procedures to treat major wound issues. Eighteen patients had flaps and 14 had split-thickness skin grafts. The median time to operatively treating the wound was 1.9 (range: 0.5-12.5) months after the index TAR. The median follow-up time from the wound procedure was 12.7 (range: 1.2-170.8) months. Compared to the control group, patients with major wounds had a significantly longer mean surgery (214.8 vs 189.3 minutes, P = .041) time and trended toward a longer median tourniquet time (151 vs 141 minutes, P = .060). Patients without wound complications were more likely to have posttraumatic arthritis, whereas those with wound complications were more likely to have primary osteoarthritis ( P = .006). The control group trended toward having a higher mean BMI (29.5 vs 27.2, P = .056). There were 6 failures in the major wound complication cohort (23.1%), including 2 below the knee amputations.

CONCLUSION

Ankle wounds that required operative management had high failure rates and some resulted in devastating outcomes. We did not find any increase in major wound complications in those with various risk factors as identified by other studies. Given our data, we recommend limiting operative time. While correcting hindfoot and midfoot alignment is important for improving patient functionality and survivorship of the implant, thought should be given to staging the TAR if multiple pathologies are to be addressed at the time of surgery to limit operative time.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.

Salto Talaris Total Ankle Arthroplasty: Clinical Results at a Mean of 5.2 Years in 78 Patients Treated by a Single Surgeon

BACKGROUND

In recent years, the number of total ankle arthroplasty procedures performed has increased dramatically. We sought to report the clinical results of the largest cohort of patients treated with a modern fixed-bearing total ankle arthroplasty by a single surgeon.

METHODS

We retrospectively reviewed the charts of 78 consecutive patients (81 ankles) who underwent total ankle arthroplasty with a minimum clinical follow-up of 2 years. Sixty-three patients completed standardized questionnaires including the Foot and Ankle Disability Index (FADI), the Short Musculoskeletal Function Assessment (SMFA), the Short Form (SF)-36v2, and a visual analog scale (VAS) for pain. In addition, each patient underwent serial range-of-motion examination and radiographic implant evaluation at each follow-up appointment.

RESULTS

Implant survival was 97.5% at a mean follow-up time of 5.2 years. There was 1 revision of a tibial component and 1 revision of a talar component. Thirty-six patients underwent a concurrent procedure at the time of the index surgery, with the most common being removal of previous hardware. Seventeen patients underwent additional procedures following the index surgery, with the most common being gutter debridement. Total range of motion averaged 35.5° preoperatively and 39.9° postoperatively (p = 0.02). Fifty-seven ankles (70%) had >2 years of radiographic follow-up, and 25 ankles (31%) displayed evidence of lucency around a metallic component at the final radiographic follow-up. Outcome scores at a mean of 5.2 years revealed promising results for the cohort, with a mean VAS pain score of 17.7 and a mean FADI score of 79.1.

CONCLUSIONS

Modern fixed-bearing total ankle arthroplasty had excellent implant survival, improved plantar flexion and total range of motion, and had good-to-excellent functional outcome at a mean follow-up of 5.2 years.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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.