The present state of ankle arthroplasty

Total Ankle Replacement: Biomechanics of the Designs, Clinical Outcomes, and Remaining Issues

The present review paper aimed at discussing the current major issues in total ankle replacement, both the technical and biomechanical concepts, and the surgical and clinical concerns. Designers shall target at the same time restoration of natural ankle kinematics and congruity of the artificial surfaces throughout the range of motion. Surgeons are recommended to expand biomechanical knowledge on ankle joint replacement, and provide appropriate training and key factors to make arthroplasty a good alternative to arthrodesis. Moreover, adequate selection of patients and careful rehabilitation are critical. In the future, custom-made prosthesis components and patient-specific instrumentation are major developments for more complex cases.

Incidence of ankle arthrodesis and total ankle replacement between 1997 and 2018: A nationwide registry study in Finland

BACKGROUND

Surgical treatment options for end-stage ankle osteoarthritis (OA) include ankle arthrodesis (AA) and total ankle replacement (TAR). We investigated the national incidence of AA and TAR and assessed trends in the surgical management of ankle OA in Finland between 1997 and 2018.

METHODS

The Finnish Care Register for Health Care was used to calculate the incidence of AA and TAR based on sex and different age groups.

RESULTS

The mean age (SD) of patients was similar, 57.8 (14.3) years for AA and 58.1 (14.0) for TAR. TAR showed a 3-fold increase from 0.3 per 100 000 person-years in 1997 to 0.9 per 100 000 person-years in 2018. The incidence of AA operations decreased during the study period from 4.4 per 100 000 person-years in 1997 to 3.8 per 100 000 person-years in 2018. TAR utilization increased notably at the expense of AA between 2001 and 2004.

CONCLUSION

TAR and AA are both widely used procedures in the treatment of ankle OA, with AA being the favored option for most patients. The incidence of TAR has remained constant for the past 10 years, indicating appropriate treatment indications and utilization.

Joint Preserving Surgery for Valgus Ankle Osteoarthritis

Valgus ankle OA is a complex problem with multiple etiologies that can either be isolated or superimposed on top of other medical or musculoskeletal disorders. Proper medical history, physical, and preoperative radiological examinations are crucial in deciding on surgery and planning the surgical approach. JPS, especially the varisating medial closing-wedge SMOT with solid plate fixation, has been consistently associated with good outcomes for patients with valgus ankle OA. To further improve JPS for valgus ankle OA, further clinical and biomechanical studies are required to address the long-term clinical and functional outcomes and complications.

Effectiveness and Safety of Ankle Arthrodesis Versus Arthroplasty: A Prospective Multicenter Study

BACKGROUND

Newer designs and techniques of total ankle arthroplasty (TAA) have challenged the assumption of ankle arthrodesis (AA) as the primary treatment for end-stage ankle arthritis. The objective of this study was to compare physical and mental function, ankle-specific function, pain intensity, and rates of revision surgery and minor complications between these 2 procedures and to explore heterogeneous treatment effects due to age, body mass index (BMI), patient sex, comorbidities, and employment on patients treated by 1 of these 2 methods.

METHODS

This was a multisite prospective cohort study comparing outcomes of surgical treatment of ankle arthritis. Subjects who presented after nonoperative management had failed received either TAA or AA using standard-of-treatment care and rehabilitation. Outcomes included the Foot and Ankle Ability Measure (FAAM), Short Form-36 (SF-36) Physical and Mental Component Summary (PCS and MCS) scores, pain, ankle-related adverse events, and treatment success.

RESULTS

Five hundred and seventeen participants underwent surgery and completed a baseline assessment. At 24 months, the mean improvement in FAAM activities of daily living (ADL) and SF-36 PCS scores was significantly greater in the TAA group than in the AA group, with a difference between groups of 9 points (95% confidence interval [CI] = 3, 15) and 4 points (95% CI = 1, 7), respectively. The crude incidence risks of revision surgery and complications were greater in the AA group; however, these differences were no longer significant after adjusting for age, sex, BMI, and Functional Comorbidity Index (FCI). The treatment success rate was greater after TAA than after AA for those with an FCI of 4 (80% versus 62%) and not fully employed (81% versus 58%) but similar for those with an FCI score of 2 (81% versus 77%) and full-time employment (79% versus 78%).

CONCLUSIONS

At 2-year follow-up, both AA and TAA were effective. Improvement in several patient-reported outcomes was greater after TAA than after AA, without a significant difference in the rates of revision surgery and complications.

LEVEL OF EVIDENCE

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

Ankle arthroplasty: A review and summary of results from joint registries and recent studies

Total ankle arthroplasty offers a reasonable alternative to ankle arthrodesis in carefully selected patients.

It is debatable whether rheumatoid arthritis patients have better outcomes compared with those who have ankle arthroplasty for either primary osteoarthritis or post-traumatic arthritis.

Aseptic loosening and infection are the most common complications requiring revision.

It is worth noting that some of the best survival rates are seen in the surgeon-designer case series.

The uncemented mobile or fixed bearing prostheses have better outcomes compared with their older counterparts.

There is no convincing evidence to suggest superiority of one design over another among the currently available prostheses.

Ankle arthroplasty surgery has a steep learning curve; the prosthesis choice should be driven by the surgeon’s training and experience.

Cite this article: EFORT Open Rev 2018;3:391-397. DOI: 10.1302/2058-5241.3.170029

Long-term Results of Scandinavian Total Ankle Replacement

BACKGROUND

The purpose of this study was to evaluate the long-term results of the Scandinavian Total Ankle Replacement (STAR) implant in a single center.

METHODS

Between 1997 and 2002, 34 consecutive ankles were replaced with the STAR ankle prosthesis and reviewed in 2016. Patients were followed both radiologically and clinically; clinical outcomes were measured with the Kofoed ankle score and subjective measurements. The median follow-up period was 159 months (13.3 years; range, 13-202 months).

RESULTS

The implant survival rate was 93.9% (95% confidence interval [CI], 92.2%-86.7%) at 5 years, 86.7% (95% CI, 69.3%-96.2%) at 10 years, and 63.6% (95% CI, 30.8%-89.0%) at 15 years. A total of 15 ankles (44%) had been revised: 2 by fusion, 3 by further replacement, 5 by insert exchange, and 5 by bone grafting for marked osteolysis. The improvements in the Kofoed ankle score and Kofoed ankle score for pain were statistically significant at every postoperative evaluation point compared to the preoperative values (all P < .0001), and subjective patient satisfaction was high.

CONCLUSION

Our results were satisfactory and in agreement with previously reported findings of STAR implants.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Obesity Is Associated With Increased Complications After Operative Management of End-Stage Ankle Arthritis

BACKGROUND

Total ankle arthroplasty (TAA) and ankle arthrodesis (AA) are two operative options for the management of end-stage ankle arthritis that has failed conservative interventions. Obesity is associated with a greater incidence of musculoskeletal disease, particularly osteoarthritis of the weight-bearing joints, including the ankle. The objective of the present study was to use a national database to examine the association between obesity and postoperative complications after TAA and AA.

METHODS

The PearlDiver database was queried for patients undergoing AA and TAA using International Classification of Diseases, 9th Revision (ICD-9) procedure codes. Patients were divided into obese (body mass index ≥30 kg/m(2)) and nonobese (body mass index <30 kg/m(2)) cohorts using ICD-9 codes for body mass index and obesity. Complications within 90 days postoperatively were assessed using ICD-9 and Current Procedural Terminology (CPT) codes.

RESULTS

23,029 patients were identified from 2005 to 2011, including 5361 with TAA and 17,668 with AA. Obese TAA patients had a significantly increased risk of 90-day major, minor, local, systemic, venous thromboembolic, infectious, and medical complications compared with nonobese patients. The incidence of revision TAA was also significantly higher in obese patients compared with nonobese patients. Findings were similar for AA, as all types of complications were significantly higher in obese patients compared with nonobese patients.

CONCLUSION

Obesity was associated with significantly increased rates of all complications after both TAA and AA. The cause of this association was likely multifactorial, including increased rates of medical comorbidities, intraoperative factors, and larger soft tissue envelopes.

LEVEL OF EVIDENCE

Level III, comparative series.

Racial disparities in total ankle arthroplasty utilization and outcomes

INTRODUCTION

The objective of this study was to examine the racial disparities in total ankle arthroplasty (TAA) utilization and outcomes.

METHODS

We used the National Inpatient Sample (NIS) to study the time-trends. Race was categorized as White and Black. Utilization rates were calculated for the U.S. general population per 100,000. Hospital length of stay, discharge disposition and mortality after TAA were assessed. We used the Cochran Armitage trend test to assess time-trends from 1998 to 2011 and chi-square test to compare TAA utilization. We used analysis of variance or chi-squared test to compare the characteristics of Whites and Blacks undergoing TAA and logistic regression to compare mortality, length of stay and discharge to home versus medical facility.

RESULTS

The mean ages for Whites undergoing TAA were 62 years and for Blacks was 52 years. Significant racial disparities were noted in TAA utilization rates (/100,000) in 1998, 0.14 in Whites vs. 0.07 in Blacks (P<0.0001; 2-fold) and in 2011, 1.17 in Whites vs. 0.33 in Blacks (P<0.0001; 4-fold). Racial disparities in TAA utilization increased significantly from 1998 to 2011 (P<0.0001). There was a trend towards statistical significance for the difference in the length of hospital stay in Blacks vs. Whites (52.9% vs. 44.3% with length of hospital stay higher than the median; P=0.08). Differences in the proportion discharged to an inpatient medical facility after TAA, 16.6% Blacks vs. 13.4% Whites, were not significant (P=0.36).

CONCLUSIONS

This study demonstrated significant racial disparities with lower TAA utilization and suboptimal outcomes in Blacks compared to Whites. Further studies are needed to understand the mediators of these disparities and to assess whether these mediators can be targeted to reduce racial disparities in TAA.

Radiographic evaluation of posttraumatic osteoarthritis of the ankle: the Kellgren-Lawrence scale is reliable and correlates with clinical symptoms

OBJECTIVE

To assess reliability and construct validity of the Kellgren-Lawrence (K&L) scale in posttraumatic ankle osteoarthritis (OA); additionally evaluate the validity of including tibiotalar tilting in the scale.

METHOD

One-hundred and fifty ankle radiographs (75 patients, unilateral malleolar fractures) evaluated at average of 18 years after surgery. American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot (HF) score and pain (visual analog scale) were recorded. Grading of OA according to K&L criteria and identification of OA features was performed on standardized radiographs by four physicians. Minimal joint space width, sclerosis, and talar tilt angle were quantified by digital measurements. A modified K&L scale including talar tilting is presented. Validity of original and modified scale was evaluated and expressed as ability to (1) Identify those with clinical symptoms of ankle OA; and (2) Distinguish between different degrees of fracture severity.

RESULTS

Inter- and intra-observer reliability of OA assessment according to K&L were good (ICC 0.61 and 0.75). Original and modified K&L grades significantly increased with decreasing AOFAS ankle-HF scores and greater pain. A talar-tilt angle > 2° compared with ≤ 2° in grade 3 was associated with significantly higher pain levels (VAS pain 4.2 vs 1.4, respectively; mean difference 2.8, 95% CI 0.5-5.1). More severe fracture patterns at time of surgery were more often in patients with the highest K&L grades.

CONCLUSIONS

The K&L scale is a valid and reliable radiographic grading system for assessment of ankle OA. Inclusion of the talar tilt angle might allow for better differentiation with respect to clinical outcomes.

Modular stem fixed-bearing total ankle replacement: prospective results of 23 consecutive cases with 3-year follow-up

In the present report, the 3-year outcomes of 23 consecutive patients treated with a modular stem fixed-bearing total ankle replacement are described. Pain, functional impairment, and disability were assessed annually using a visual analog scale. Complications and additional procedures also were recorded. Compared with preoperative pain (8.4 ± 1.4), functional impairment (8.7 ± 2.3), and disability (3.0 ± 2.5), there were statistically significant postoperative improvements at 1 year (pain, 2.6 ± 1.6; functional impairment, 3.1 ± 2.1; disability, 0.9 ± 1.2), 2 years (pain, 1.5 ± 1.3; functional impairment, 1.9 ± 1.4; disability, 0.6 ± 1.4), and 3 years (pain, 1.3 ± 1.3; functional impairment, 1.9 ± 1.9; disability, 0.4 ± 0.9; p ≤ .001). Pain, function, and disability significantly improved postoperatively from 1 to 2 years (p ≤ .008) and from 1 to 3 years (p ≤ .008). The reductions in pain, functional impairment, and disability were maintained from 2 to 3 years (p ≥ .08). Nine complications (39.1%) were encountered: 1 deep infection, 2 pulmonary embolisms, 3 wounds, 1 ectopic bone formation, 1 stiff joint, and 1 talar subsidence. In the 3-year follow-up period, 3 patients (13.0%) required additional procedures after the immediate postoperative phase. Our results have demonstrated that modular stem fixed-bearing prostheses can be implanted in a predictable and consistent fashion with resultant improvements in pain, function, and disability. Future studies evaluating the clinical outcomes after modular stem fixed-bearing total ankle replacement are warranted.

The mid-term outcome of total ankle arthroplasty and ankle fusion in rheumatoid arthritis: a systematic review

Background

While arthrodesis is the standard treatment of a severely arthritic ankle joint, total ankle arthroplasty has become a popular alternative. This review provides clinical outcomes and complications of both interventions in patients with rheumatoid arthritis.

Methods

Studies were obtained from Pubmed, Embase and Web of Science (January 1980 – June 2011) and additional manual search. Inclusion criteria: original clinical study, > 5 rheumatoid arthritis (population), internal fixation arthrodesis or three-component mobile bearing prosthesis (intervention), ankle scoring system (outcome). The clinical outcome score, complication- and failure rates were extracted and the methodological quality of the studies was analysed.

Results

17 observational studies of 868 citations were included. The effect size concerning total ankle arthroplasty ranged between 1.9 and 6.0, for arthrodesis the effect sizes were 4.0 and 4.7. Reoperation due to implant failure or reoperation due to non-union, was 11% and 12% for respectively total ankle arthroplasty and arthrodesis. The methodological quality of the studies was low (mean 6.4 out of a maximum of 14 points) and was lower for arthrodesis (mean 4.8) as compared to arthroplasty (mean 7.8) (p = 0.04).

Conclusions

17 observational and no (randomized) controlled clinical trials are published on the effectiveness of arthroplasty or arthrodesis of the ankle in rheumatoid arthritis. Regardless of the methodological limitations it can be concluded that both interventions show clinical improvement and in line with current literature neither procedure is superior to the other.

Complication rates after total ankle arthroplasty in one hundred consecutive prostheses

INTRODUCTION

Total ankle arthroplasty is increasingly used as an alternative to arthrodesis to treat advanced ankle arthritis. However, the outcomes and postoperative complications are poorly described.

PATIENTS AND METHODS

Between March 2005 and May 2010 114 S.T.A.R. prostheses were implanted by one surgeon at our institution. We retrospectively analysed the demographics, clinical outcomes and radiographic characteristics of 100 ankle prostheses (97 patients).

RESULTS

The average follow up was 36 months. The average preoperative AOFAS score of 36.87 (22-58) significantly increased to 75.99 postoperative. A total of 87 % of the patients reported a better life quality. Twenty-seven ankles incurred complications after primary surgery, and 21 prostheses required revision surgery, including four patients who required arthrodesis.

CONCLUSION

Our study shows a high satisfaction rate after total ankle replacement and clear pain relief. Patients with a body mass Index higher than 30 showed a higher rate of complications. Compared with ankle fusion, the rates of complications are comparable.

Clinical and radiographic outcomes of the mobility total ankle arthroplasty system: early results from a prospective multicenter study

BACKGROUND

The Mobility Total Ankle System is a third-generation design consisting of a 3-component, cementless, unconstrained, mobile-bearing prosthesis. This study reports the early results of a prospective multicenter study of the Mobility prosthesis.

METHODS

Eighty-eight Mobility total ankle arthroplasties (TAAs) were implanted in 85 patients. The most common underlying diagnosis was posttraumatic arthritis (53%). Ankles were classified according to the Canadian Orthopedic Foot and Ankle Society (COFAS) end-stage ankle arthritis classification system. Coronal plane deformity was quantified preoperatively. Patients were reviewed at regular intervals postoperatively, with clinical and radiographic assessment. The mean follow-up time was 40 months (range, 30-60 months).

RESULTS

Type 1 ankle arthritis was demonstrated in 44 ankles (50%). No patient had preoperative coronal plane angulation greater than 20 degrees. In 32 ankles (36%) the preoperative coronal alignment was neutral, and in 34 ankles (39%) the deformity was less than 10 degrees. The mean American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot score improved from 38.2 (range, 12-59) preoperatively to 74.8 (range, 46-100) postoperatively. Bone-implant interface abnormalities were identified in 33 ankles with a retained prostheses (43%). Thirty (91%) of these involved zones around the tibial plate. In total, 8 TAAs required revision, 6 for aseptic loosening, 1 for talar migration, and 1 for deep infection. There was 1 conversion to arthrodesis for component malpositioning and 1 transtibial amputation for chronic regional pain syndrome. Six patients were being investigated for ongoing pain. The cumulative survival was 89.6% (95% confidence interval, 80.8-94.8) at 3 years and 88.4% (95% confidence interval, 79.3-93.9) at 4 years.

CONCLUSION

Early results of the Mobility TAA for independent researchers do not match those reported by other surgeons. Good pain relief and improved function were achieved postoperatively in 72 ankles (82%). High rates of bone-implant interface abnormalities around the tibial plate are concerning but require longer follow-up to determine their clinical significance.

Treatment of the arthritic valgus ankle

The ankle joint is part of a biomechanical hindfoot complex. Approximately 1% of the world's adult population is affected by ankle osteoarthritis (AO). Trauma is the primary cause of ankle OA, often resulting in varus or valgus deformities. Only 50% of patients with end-stage ankle OA have a normal hindfoot alignment. The biomechanics and morphology of the arthritic valgus ankle is reviewed in this article and therapeutic strategies, including joint preserving and nonpreserving modalities are presented. Pitfalls are discussed and the literature is reviewed regarding outcomes in patients with valgus deformity who underwent total ankle replacement.

Early results after tibialis anterior tendon transfer for severe varus in total ankle replacement

BACKGROUND

Treatment of severe ankle arthritis with varus malalignment remains controversial.

METHODS

In 14 consecutive total ankle replacements (TAR) with tibiotalar varus malalignment of above 15 (range, 16 to 41) degrees, a complete transfer of the tibialis anterior tendon together with other soft-tissue and bony realignment measures was added to the primary procedure.

RESULTS

After mean followup time of 33.4 (range, 21 to 49) months, only one case showed minor tibiotalar tilt in the frontal plane. The overall clinical results were good to excellent in all but two cases with an average AOFAS-score of 86.4 (range, 70 to 98) points. However, three cases of tibial nerve neuropathy due to entrapment or overtensioning were observed; one of these cases developed clinical problems with incomplete recovery.

CONCLUSION

Tibialis anterior tendon transfer can be recommended in conjunction with TAR in cases of varus malalignment with severe muscular or ligamentous imbalance with neuropathy of the tibial nerve being the main complication.

Total ankle replacement for treatment of end-stage osteoarthritis in elderly patients

End-stage osteoarthritis of the ankle is a disabling problem, particularly in elderly patients who experience an overall loss of mobility and functional impairment and who then need compensatory adaption. Ankle arthrodesis, which has been demonstrated to provide postoperative pain relief and hindfoot stability, leaves the patient with a stiff foot and gait changes. For elderly patient, these changes may be more critical than generally believed. Additionally, the long duration of healing and rehabilitation process needed for ankle arthrodesis may be problematic in the elderly. In contrast to ankle arthrodesis, total ankle replacement has significant advantages including a less strenuous postoperative rehabilitation and preservation of ankle motion which supports physiological gait. Recently, total ankle replacement has evolved as a safe surgical treatment in patients with end-stage ankle osteoarthritis with reliable mid- to long-term results. Total ankle replacement needs less immobilization than arthrodesis and does allow for early weight-bearing and should be considered as a treatment option of first choice in many elderly patients with end-stage osteoarthritis of the ankle, especially in elderly patients with lower expectations and physical demands.

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.

Outcomes following pantalar arthrodesis in rheumatoid arthritis

BACKGROUND

We report a consecutive series of pantalar arthrodeses in patients with rheumatoid arthritis, using a single laterally based incision and autologous bone graft.

MATERIALS AND METHODS

All operations were performed by a single surgeon and were assessed preoperatively and at 6 and 12 months postoperatively. The levels of patient satisfaction, functional improvement and pain scores of the foot following surgery were recorded along with radiological parameters. Seventeen patients (two male and 15 female) underwent 18 hindfoot surgeries and were assessed preoperatively using the SF-12 General Health survey questionnaire, Manchester-Oxford Foot Survey and pain scores.

RESULTS

We found a significant improvement in pain levels and SF-12 scores. In addition the patients reported a high level of satisfaction with the outcome of surgery and improvement in function.

CONCLUSION

The results show that pantalar arthrodesis is a very effective operative treatment for severe ankle and concomitant hindfoot disease. The treatment period is prolonged and patients should be counselled appropriately.

LEVEL OF EVIDENCE

IV, Retrospective Case Series

Total ankle arthroplasty outcome comparison for post-traumatic and primary osteoarthritis

BACKGROUND

Mobile-bearing total ankle arthroplasty designs have achieved good clinical results for the treatment of ankle osteoarthritis. However, no direct comparison of the outcomes of total ankle arthroplasty has been made between post-traumatic and primary osteoarthritis. The purpose of the present study was to compare the clinical and radiographic outcomes of total ankle arthroplasty in patients with post-traumatic and primary osteoarthritis.

MATERIALS AND METHODS

The HINTEGRA total ankle arthroplasty was carried out in 65 patients (67 ankles) with symptomatic ankle osteoarthritis. Group A included 37 patients (37 ankles) with post-traumatic osteoarthritis, whereas Group B included 28 patients (30 ankles) with primary osteoarthritis. Patients were assessed clinically and radiographically at a mean followup of 38 months.

RESULTS

No significant differences were found between the two study groups in terms of American Orthopaedic Foot and Ankle Society ankle-hindfoot scales, range of motion, or radiographic values at final followup (p > 0.05). The incidence of complications (38% in Group A, 27% in Group B) and additional procedures (54% in Group A, 27% in Group B) was significantly higher in Group A (p = 0.014 for complications, p = 0.013 for additional procedures). One ankle was revised in Group A for a deep infection.

CONCLUSION

The clinical and radiographic outcomes of total ankle arthroplasty for post-traumatic and primary osteoarthritis were comparable, although the incidence of complications after total ankle arthroplasty was higher in the post-traumatic osteoarthritis group. More preceding or concomitant surgeries were required in order to make the post-traumatic cases suitable for total ankle arthroplasty.

Total ankle replacement compatible with ligament function produces mobility, good clinical scores, and low complication rates: an early clinical assessment

BACKGROUND

A three-part ankle replacement was developed to achieve compatibility with the natural ligaments by allowing fibers on the medial and lateral sides to remain isometric during passive motion. Unlike all current prostheses, the new design uses nonanatomically shaped components on the tibia and talus and a fully conforming interposed meniscal bearing.

QUESTIONS/PURPOSES

Does this new design restore ankle mobility, improve clinical score, and result in low complication and early revision rates?

PATIENTS AND METHODS

We reviewed 51 patients in whom 51 prostheses were implanted in a seven-center trial from July 2003 to July 2006. The mean age of the patients at surgery was 61.5 years (range, 35.1-82.5 years). We used the AOFAS score to assess clinical outcome. We used lateral radiographs to assess function. The minimum followup was 24 months (mean, 30 months; range, 24-48 months).

RESULTS

The mean preoperative AOFAS score of 38.5 increased to 76.9, 79.1, 76.4, and 79.0 at 12, 24, 36, and 48 months, respectively. We observed a correlation between meniscal bearing movement on the tibial component (mean, 3.4 mm; range, 2-12 mm) and range of flexion at the replaced ankle (mean, 27.4º; range, 16º-53º). We revised one arthroplasty in the second postoperative year for lateral impingement, providing a 3-year cumulative survival rate of 97% and performed one other secondary operation for hindfoot pain.

CONCLUSIONS

These data suggest the new prosthesis can provide short-term restoration of ankle mobility, a good clinical score, and low complication and failure rates. Longer followup with larger numbers is required.

LEVEL OF EVIDENCE

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

The instantaneous helical axis of the subtalar and talocrural joints: a non-invasive in vivo dynamic study

Background

An understanding of rear-foot (talocrural and subtalar joints) kinematics is critical for diagnosing foot pathologies, designing total ankle implants, treating rear-foot injuries and quantifying gait abnormalities. The majority of kinematic data available have been acquired through static cadaver work or passive in vivo studies. The applicability of these data to dynamic in vivo situations remains unknown. Thus, the purpose of this study was to fully quantify subtalar, talocrural and calcaneal-tibial in vivo kinematics in terms of the instantaneous helical axis (IHA) in twenty-five healthy ankles during a volitional activity that simulated single-leg toe-raises with partial-weight support, requiring active muscle control.

Methods

Subjects were each placed supine in a 1.5 T MRI and asked to repeat this simulated toe-raise while a full sagittal-cine-phase contrast (dynamic) MRI dataset was acquired. From the cine-phase contrast velocity a full kinematic description for each joint was derived.

Results

Nearly all motion quantified at the calcaneal-tibial joint was attributable to the talocrural joint. The subtalar IHA orientation and position were highly variable; whereas, the talocrural IHA orientation and position were extremely consistent.

Conclusion

The talocrural was well described by the IHA and could be modeled as a fixed-hinge joint, whereas the subtalar could not be.

The AES total ankle replacement: A mid-term analysis of 93 cases

BACKGROUND

There are few studies concerning specific total ankle arthroplasties. This study reports mid-term survival data for the AES prosthesis.

METHODS

Ninety-three AES ankle arthroplasties were performed by the senior authors. The mean follow-up was 3.5 years. The 5-year survivorship and also the number of simultaneous procedures, reoperations, additional procedures and revisions are analyzed.

RESULTS

The 5-year survivorship with revision for any reason as end-point was 90%. Simultaneous procedures were performed in 25 patients, deltoid release and subtalar fusion being the most common. There were seven revisions, one due to loosening, and two due to infection, instability and fractures, respectively. Twenty-seven reoperations or additional procedures were performed in 23 patients with a procedure for malleolar impingement being the most common reoperation, and correction of hindfoot varus being the most common reason for an additional procedure.

CONCLUSIONS

The AES total ankle replacement seems to be a reasonably safe procedure in experienced hands.