Total ankle arthroplasty: a review of 11 current ankle implants

Introduced in the early 1970s, total ankle arthroplasty offered patients with debilitating ankle arthritis reduction in pain and almost normal mobility at the ankle joint. The idea of replacing an arthritic ankle joint with a mobile ankle prosthesis was originally welcomed to replace ankle arthrodesis. Unfortunately, high failure rates of first-generation implants led many surgeons in the United States to recommend ankle arthrodesis as the best alternative. An improved understanding of ankle joint mechanics, implant material and design, and surgical technique has led to the development of several second-generation implants that are being used successfully throughout the world. As short-term, mid-term, and long-term results continue to be published, there has been a momentous change in the outlook of total ankle arthroplasty as a viable option to ankle arthrodesis.     

Comparison of reoperation rates following ankle arthrodesis and total ankle arthroplasty

BACKGROUND: The role of ankle arthroplasty in the treatment of ankle arthritis is controversial. Ankle fusion is commonly performed, but there is ongoing concern about functional limitations and arthritis in the adjacent subtalar joint following ankle arthrodesis. The use of ankle arthroplasty as an alternative to ankle fusion is expanding, but reported results have been limited to those in case series. The purpose of this study was to compare the reoperation rates following ankle arthrodesis and ankle replacement on the basis of observational, population-based data from all inpatient admissions in California over a ten-year period. Our hypothesis was that patients treated with ankle replacement would have a lower risk of undergoing subtalar fusion but a higher overall risk of undergoing major revision surgery. METHODS: We used California's hospital discharge database to identify patients who had undergone ankle replacement or ankle arthrodesis as inpatients in the years 1995 through 2004. Short-term outcomes, including rates of major revision surgery, pulmonary embolism, amputation, and infection, were examined. Long-term outcomes that were analyzed included the rates of major revision surgery and subtalar joint fusion. Logistic and proportional hazard regression models were used to estimate the impact of the choice of ankle replacement or ankle fusion on the rates of adverse outcomes, with adjustment for patient factors including age and comorbidity. RESULTS: A total of 4705 ankle fusions and 480 ankle replacements were performed during the ten-year study period. Patients who had undergone ankle replacement had an increased risk of device-related infection and of having a major revision procedure. The rates of major revision surgery after ankle replacement were 9% at one year and 23% at five years compared with 5% and 11% following ankle arthrodesis. Patients treated with ankle arthrodesis had a higher rate of subtalar fusion at five years postoperatively (2.8%) than did those treated with ankle replacement (0.7%). Regression analysis confirmed a significant increase in the risk of major revision surgery (hazard ratio, 1.93 [95% confidence interval, 1.50 to 2.49]; p < 0.001) but a decreased risk of subtalar fusion (hazard ratio, 0.28 [95% confidence interval, 0.09 to 0.87]; p = 0.03) in patients treated with ankle replacement compared with those treated with ankle fusion. CONCLUSIONS: This study confirms that, compared with ankle fusion, ankle replacement is associated with a higher risk of complications but also potential advantages in terms of a decreased risk of the patient requiring subtalar joint fusion. Additional controlled trials are needed to clarify the appropriate indications for ankle arthrodesis and ankle replacement.     

Prophylactic Bracing Versus Taping for the Prevention of Ankle Sprains in High School Athletes: A Prospective, Randomized Trial

Prophylactic ankle taping has been considered the mainstay of ankle injury prevention and has been used at all levels of competitive football. An alternative to taping is a semirigid ankle orthosis. This study prospectively compared the incidence of ankle sprains in high school football players during a single season, after randomization to either prophylactic bracing or taping of both ankles. Of 83 athletes followed up for an entire season, 6 ankle sprains occurred, 3 in each treatment group; and there was no statistically significant difference in the incidence of ankle sprains between the 2 groups. The time required to tape an athlete averaged 67 seconds per ankle, resulting in a total of 97 minutes per ankle during an entire season, and the average cost to tape each ankle during an entire season was greater than the cost of the commercially available brace. The projected cost savings for an athletic program using prophylactic bracing could be substantial when compared with the use of prophylactic taping of the ankle.     

Cost-effectiveness analysis of total ankle arthroplasty

BACKGROUND: There is renewed interest in total ankle arthroplasty as an alternative to ankle fusion in the treatment of end-stage ankle arthritis. Despite a lack of long-term data on the clinical outcomes associated with these implants, the use of ankle arthroplasty is expanding. The purpose of this cost-effectiveness analysis was to evaluate whether the currently available literature justifies the emerging use of total ankle arthroplasty. This study also identifies thresholds for the durability and function of ankle prostheses that, if met, would support more widespread dissemination of this new technology. METHODS: A decision model was created for the treatment of ankle arthritis. The literature was reviewed to identify possible outcomes and their probabilities following ankle fusion and ankle arthroplasty. Each outcome was weighted for quality of life with use of a utility factor, and effectiveness was expressed in units of quality-adjusted life years. Gross costs were estimated from Medicare charge and reimbursement data for the relevant codes. The effect of the uncertainty of estimates of costs and effectiveness was assessed with sensitivity analysis. RESULTS: The reference case of our model assumed a ten-year duration of survival of the prosthesis, resulting in an incremental cost-effectiveness ratio for ankle arthroplasty of $18,419 per quality-adjusted life year gained. This reflects a gain of 0.52 quality-adjusted life years at a cost of $9578 when ankle arthroplasty is chosen over fusion. This ratio compares favorably with the cost-effectiveness of other medical and surgical interventions. Sensitivity analysis determined that the cost per quality-adjusted life year gained with ankle arthroplasty rises above $50,000 if the prosthesis is assumed to fail before seven years. Treatment options with ratios above $50,000 per quality-adjusted life year are commonly considered to have limited cost-effectiveness. This threshold is also crossed when the theoretical functional advantages of ankle arthroplasty are eliminated in sensitivity analysis. CONCLUSIONS: The currently available literature has not yet shown that total ankle arthroplasty predictably results in levels of durability and function that make it cost-effective at this time. However, the reference case of this analysis does demonstrate that total ankle arthroplasty has the potential to be a cost-effective alternative to ankle fusion. This reference case assumes that the theoretical functional advantages of ankle arthroplasty over ankle fusion will be borne out in future clinical studies. Performance of total ankle replacement will be better justified if these thresholds are met in published long-term clinical trials.     

Kinematic changes after fusion and total replacement of the ankle: part 1: Range of motion

BACKGROUND: The purpose of this study was to determine how closely the present designs of ankle prostheses mimic the unique requirements of the foot and ankle. The three-dimensional range of motion (ROM) of the ankle joint complex, before and after ankle arthrodesis and after implantation of three currently used total ankle prostheses, was investigated. METHODS: The three-dimensional ROM was determined in six fresh-frozen cadaver leg specimens using a 6-df device with an axial load of 200 N and a four-camera high-speed video system. A moment of 100 Nm was applied to the footplate to determine the ROM in the sagittal (dorsiflexion and plantarflexion) and frontal (inversion and eversion) planes. The same moment was applied to the tibia to determine the ROM for the internal and external tibial rotation. The measurements were performed for the normal ankle, the fused ankle, and the AGILITY, HINTEGRA, and S.T.A.R. prostheses. RESULTS: Compared to the normal condition, the ROM for dorsiflexion and plantarflexion was changed for all surgical interventions. The changes were highest for the ankle arthrodesis. The changes due to the prostheses were significantly less than the changes due to ankle arthrodesis. Compared to the normal condition, the total ROM for inversion/eversion was slightly decreased by the fused ankle and not changed by the three-component prostheses (HINTEGRA, S.T.A.R.). However, the ROM for inversion/eversion was significantly higher for the two-component prosthesis, AGILITY. The ROM for internal and external tibial rotation was not altered by the AGILITY and HINTEGRA ankle, but it was significantly reduced by the ankle arthrodesis. S.T.A.R. showed a significant shift of the total ROM toward internal tibial rotation. CONCLUSIONS: The three tested ankle joint prostheses changed the ROM of the ankle joint complex less than ankle fusion did. Total ankle prostheses were shown to replicate normal joint ROM closely. However, ankle arthrodesis was found to reduce the ROM substantially in all three planes: the sagittal, frontal, and horizontal planes. CLINICAL IMPLICATIONS: With respect to the ROM, total ankle replacement changes the natural ankle joint condition less than ankle arthrodesis, which reduces the ROM in all three planes and might increase stress in adjacent structures. The prosthesis that replicated the normal ankle joint ROM best was the one with the most anatomical design.     

Ankle replacement versus arthrodesis: a comparative gait analysis study

BACKGROUND: The improving survivorship of ankle replacements is making this an increasingly popular option in the treatment of ankle arthritis, rather than the established option of ankle fusion. The potential benefits of restoring movement, improving gait and protecting adjacent joints are persuasive arguments in favor of replacing rather than fusing the ankle joint. METHODS: Gait analysis was performed before and after ankle arthroplasty on 12 patients, and compared to 12 patients with a successful ankle arthrodesis and to a healthy control group of 12 people. RESULTS: Important differences between the arthrodesis and ankle replacement groups were demonstrated although neither restored normal movement or walking speed. Ankle arthrodesis resulted in a faster gait with a longer step length compared to replacement, although the timing of gait demonstrated greater asymmetry. The ankle replacement group had greater movement at the ankle, a symmetrical timing of gait and restored ground reaction force pattern. CONCLUSION: The improved timing of gait would support the observation of a reduction in limp with ankle replacement though the gait is significantly slower. Longer term results are necessary to determine whether the improved movement and force transmission persists with time and protects adjacent articulations.     

Accurate measurement of ankle range of motion after total ankle arthroplasty

There is no standardized method reported in the literature to measure ROM of the ankle after a total ankle arthroplasty, which limits the possibility to compare results from the various ankle designs. It seems that most of the measurements are a combination of ankle and midfoot motion, not the tibiotalar joint. A protocol was developed to accurately measure the true tibiotalar and midfoot motion before and after an ankle replacement. Lateral radiographs were taken of the ankle with the patient in a weightbearing position, and measurements were done along fixed landmarks. In this study, the tibiotalar, midfoot, and combined ROM were measured preoperative and 1 year postoperative in a standardized, reproducible fashion. The preoperative tibiotalar ROM was 18.5 degrees and combined ankle and midfoot motion 25.1 degrees. The true tibiotalar motion after an Agility total ankle arthroplasty was 23.4 degrees, and the combined ankle and midfoot motion was 31.3 degrees. The average improvement in ROM in the tibiotalar joint was approximately 5 degrees, and combined ROM was 6.1 degrees. Preoperative ROM proved to be the main factor determining the eventual postoperative ROM. It is possible to accurately measure the true ankle and the midfoot motion and those measurements should be used when reporting on the results of ankle replacements. Total ankle arthroplasty resulted in a statistically significant, but clinically less than expected, increase in ROM.     

Total ankle replacement revisited

The surgical treatment of painful, end-stage ankle arthritis includes ankle arthrodesis and total ankle replacement. In the past decade, total ankle replacement has become a viable alternative to ankle arthrodesis. Modern implant designs either involve a syndesmosis fusion and resurfacing of the medial and lateral recesses of the ankle joint or the use of a 3-component, mobile bearing implant. In limited clinical series, the early results of both these prosthetic design approaches are encouraging. In selected patients, ankle arthroplasty is an effective approach to relieving pain and improving function. The purposes of this paper are to review the clinical results from total ankle replacement and ankle arthrodesis; discuss indications, contraindications, design features, postoperative rehabilitation, and initial results for the major current total ankle designs; and present concepts for future total ankle development. In particular, this article explores the advantages and concerns with 2 prevalent but different design approaches. It also discusses future directions for total ankle replacement.     

Arthrogenic muscle inhibition in the leg muscles of subjects exhibiting functional ankle instability

BACKGROUND: Functional ankle instability or a subjective report of ;;giving way' at the ankle may be present in up to 40% of patients after a lateral ankle sprain. Damage to mechanoreceptors within the lateral ankle ligaments after injury is hypothesized to interrupt neurologic feedback mechanisms resulting in functional ankle instability. The altered input can lead to weakness of muscles surrounding a joint, or arthrogenic muscle inhibition. Arthrogenic muscle inhibition may be the underlying cause of functional ankle instability. Establishing the involvement of arthrogenic muscle inhibition in functional ankle instability is critical to understanding the underlying mechanisms or chronic ankle instability. The purpose of this investigation was to determine if arthrogenic muscle inhibition is present in the ankle joint musculature of patients exhibiting unilateral functional ankle instability. METHODS: Twenty-nine subjects, 15 with unilateral functional ankle instability and 14 healthy control subjects, consented to participate. Bilateral soleus, peroneal, and tibialis anterior H-reflex and M-wave recruitment curves were obtained. Maximal H-reflex and maximal M-wave values were identified and the H:M ratios were calculated for data analysis. Separate 1 x 2 ANOVA were done for both the functional ankle instability and control groups to evaluate differences between limbs on the H:M ratios. Bonferroni multiple comparison procedures were used for post hoc comparisons (p < or = 0.05). RESULTS: The soleus and peroneal H:M ratios for subjects with functional ankle instability were smaller in the injured limb when compared with the uninjured limb (p < 0.05). No limb difference was detected for the tibialis anterior H:M ratio in the functional ankle instability group (p = 0.904). No side-to-side differences were detected for the H:M ratios in patients reporting no history of ankle injury (p > 0.05). CONCLUSIONS: Depressed H:M ratios in the injured limb suggest that arthrogenic muscle inhibition is present in the ankle musculature of patients exhibiting functional ankle instability. Establishing and using therapeutic techniques to reverse arthrogenic muscle inhibition may reduce the incidence of functional ankle instability.     

Distraction arthroplasty of the ankle--how far can you stretch the indications?

Ankle joint distraction has been shown to be a viable alternative to ankle arthrodesis or ankle replacement. The à la carte approach to ankle joint preservation (resection of blocking osteophytes, release of muscle/joint contractures, and realignment osseous ankle procedures) presented in this article as important for a successful outcome as is the hinged ankle joint distraction technique itself. The authors reviewed 32 patients who underwent this ankle joint distraction technique and found 78% of patients had maintained their ankle range of motion and have no pain to occasional moderate pain that can be managed generally with nonsteroidal anti-inflammatory drugs alone. Only one has required an ankle fusion, and only one has been converted to an ankle joint replacement. The longevity of these results and the higher percent of good or excellent results when compared with other studies suggest that combining adjunctive procedures and articulation with ankle distraction improves the results of this procedure.     

Comparative analysis of ankle arthroplasty versus ankle arthrodesis

In a retrospective study of 41 patients with total ankle arthroplasty (25 patients) and ankle arthrodesis (18 patients), the mean follow-up period was 3.8 years for total ankle arthroplasties and 3.3 for ankle arthrodeses. Sixteen of the 23 ankle arthroplasty patients, and 17 of the 18 arthrodesis patients had good or excellent results. Total ankle arthroplasty was successful in patients with rheumatoid arthritis, but not posttraumatic arthrosis. Total ankle arthroplasty is indicated in rheumatoid patients with severe ankle involvement who have not responded to medical management. It also may be used in the elderly or debilitated patients who will place minimal stress on the ankle. The elderly may not tolerate the prolonged immobilization or repeated operations that fusion may require. Total ankle arthroplasty should not be used in young patients with posttraumatic arthrosis.     

Arthrodese und Endoprothese des oberen Sprunggelenks

If adequate conservative measures for the treatment of end-stage ankle osteoarthritis have failed, surgery may be taken into consideration. After exorbitant failure rates in the beginning of total ankle replacement, nowadays this kind of treatment has regained lot of interest and has become a viable alternative to ankle fusion. The correct indication and a precise explanation of the surgical procedure, outcomes and potential complications provide a solid base for future success. Currently, there is no doubt that total ankle replacement has become an important player in the treatment of symptomatic and debilitating end-stage ankle arthritis. With increasing number of patients who undergo total ankle replacement the experience with this kind of procedure increases too. As a consequence several surgeons have started to stretch indications favoring total ankle replacement. However, it must be mentioned here, despite progress in terms of improved anatomical and biomechanical understanding of the hindfoot and improved surgical techniques and instruments, total ankle replacement and ankle fusion remain challenging and difficult procedures. We provide a review article including an overview of the relevant techniques. This article should serve as rough guide for surgeons and help in decision-making regarding total ankle replacement and ankle fusion.     

Bioelectrical impedance: a new method for measuring post-traumatic swelling

OBJECTIVES: The aim of this pilot study was to investigate whether measurement of the bioelectrical impedance of the lower limb could be used to measure the swelling resulting from acute ankle fracture. METHODS: The impedance of each ankle was measured in 14 patients with isolated acute ankle fracture. The degree of ankle swelling was also directly assessed by measurement of the ankle circumference and diameter and by the water displacement method. A control group of 17 healthy subjects with uninjured ankles was similarly assessed. RESULTS: The impedance of the ankle was significantly reduced in patients with ankle fracture, and there was a strong inverse relationship between the degree of this reduction and the amount of swelling as directly measured. The relationship was stronger using the impedance method than the circumference and diameter methods. CONCLUSIONS: We conclude that bioelectrical impedance can be used to measure ankle swelling in the presence of injury and could potentially be used both to monitor swelling clinically and as a research tool in studies of swelling management. More research is required to further define the potential role for this technique.     

Acute and chronic lateral ankle instability in the athlete

Ankle sprain injuries are the most common injury sustained during sporting activities. Three-quarters of ankle injuries involve the lateral ligamentous complex, comprised of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL). The most common mechanism of injury in lateral ankle sprains occurs with forced plantar flexion and inversion of the ankle as the body's center of gravity rolls over the ankle. The ATFL followed by the CFL are the most commonly injured ligaments. Eighty percent of acute ankle sprains make a full recovery with conservative management, while 20% of acute ankle sprains develop mechanical or functional instability, resulting in chronic ankle instability. Treatment of acute ankle sprains generally can be successfully managed with a short period of immobilization that is followed by functional rehabilitation. Patients with chronic ankle instability who fail functional rehabilitation are best treated with a Brostrom-Gould anatomic repair or, in those patients with poor tissue quality or undergoing revision surgery, an anatomic reconstruction.     

全踝关节置换的初步报告

目的介绍采用STAR活动负重型假体进行踝关节置换治疗终末期踝关节炎的方法，探讨其近期疗效。方法1999年10月～2003年2月．其施行STAR活动负重型踝关节置换术13例，男8例．女5例；年龄58～69岁．平均63．4岁；剖伤性关节炎6倒．骨性关节炎3例．大骨节病2例．类风湿性关节炎2例；病程8～42个月。按Kofoed踝关节评分系统分别对术前、术后患者疼痛程度、踝关节功能、踝关节活动度进行综合评分。结果随访资料完备者8例，随访时间6～38个月，平均16个月。该8例患者术前踝关节评分：6～49，平均29分；术后躁关节评分：56～99分．平均82分。术前踝关节疼痛评分：0～15分，平均7分；术后踝关节疼痛评分：35～50分．平均48分。1例患者术中发生内踝骨折，采用克氏针内固定后未影响假体稳定性，1例患者术中发生外踝骨折而改行踝关节融合术，术后1例患者伤口延迟愈合。随访时摄X线片均未见假体松动或下沉。结论STAR活动负重型踝关节置换术可有效缓解踝关节疼痛，改善踝关节活动度，并矫正踝关节畸形．是治疗终末期踝关节病变的有效手段。     

Sagittal Ankle and Midfoot Range of Motion Before and After Revision Total Ankle Replacement: A Retrospective Comparative Analysis

The most common reason for a revision total ankle replacement procedure is a painful, stiff ankle even after the initial surgery. Limited and conflicting data are available regarding the change in sagittal foot and ankle range of motion after revision total ankle replacement surgery. We sought to determine whether revision total ankle replacements would reduce compensatory midfoot range of motion. In determining this, a novel radiographic measurement system with stable osseous landmarks is used. A retrospective medical record review of patients who had undergone revision total ankle replacement from January 2009 to June 2016 was performed. Thirty-three patients (33 ankles) underwent revision total ankle replacement surgery and met the inclusion criteria with a mean follow-up period of 28.39?±?14.68 (range 2 to 59) months. Investigation of preoperative and postoperative weightbearing lateral radiographic images was performed to determine the global foot and ankle, isolated ankle, and isolated midfoot sagittal ranges of motion. Statistical analysis revealed a significant increase in ankle range of motion (p = .046) and a significant decrease in midfoot range of motion (p < .001) from preoperatively to postoperatively. The change in global foot and ankle range of motion was not significant (p = .53). For this patient population, the increased ankle range of motion effectively resulted in less compensatory midfoot range of motion.     

Arthroscopic synovectomy for recurrent hemarthrosis of the ankle in hemophilia

Nine patients with a history of recurrent hemarthroses of the ankle due to severe hemophilia were evaluated following arthroscopic ankle synovectomy. Follow-up averaged 33 months (range, 9 to 67 months) and included ankle range of motion, frequency of ankle hemarthroses, radiographic findings, and a functional assessment. The average age at the time of surgery was 12.3 years (range, 6.1 to 21.9 years). The average are of ankle motion was 48.4° (range, 30° to 70°) postoperatively. The functional score as modified from Mazur averaged 36.1 points (range, 17 to 68 points) preoperatively, and 77.9 points (range, 32 to 100 points) postoperatively. Radiographic evidence of ankle arthropathy remained stable for most ankles. Arthoscopic ankle synovectomy for recurrent hemarthrosis due to hemophilia is a viable alternative to open ankle synovectomy for controlling the frequency of ankle bleeds and maintaining ankle function.     

Ball and Socket Ankle: Mechanism and Computational Evidence of Concept

The ball and socket ankle joint is a morphologically abnormal joint characterized by rounding of the articular surface of the talus. Other than anecdotal observation, little evidence has been presented to describe the development of this deformity. The purpose of the present study was to review ankle and subtalar joint mechanics and to kinematically examine the functional combination of these joints as a mechanism of the ball and socket ankle deformity. We reviewed functional representations of the ankle joint, subtalar joint, and ball and socket ankle deformity. A computational study of joint kinematics was then performed using a 3-dimensional model derived from a computed tomography scan of a ball and socket deformity. The joint kinematics were captured by creating a “virtual map” of the combined kinematics of the ankle and subtalar joints in the respective models. The ball and socket ankle deformity produces functionally similar kinematics to a combination of the ankle and subtalar joints. The findings of the present study support the notion that a possible cause of the ball and socket deformity is bony adaptation that compensates for a functional deficit of the ankle and subtalar joints.     

Modified Evans Peroneus Brevis Lateral Ankle Stabilization for Balancing Varus Ankle Contracture during Total Ankle Replacement

Lateral ankle instability is frequently encountered when performing total ankle replacement and remains a challenge. In the present techniques report, I have described a modification of the Evans peroneus brevis tendon lateral ankle stabilization harvested through limited incisions using simple topographic anatomic landmarks. The harvested peroneus brevis is then transferred either to the anterior distal tibia concomitantly with total ankle replacement or through the tibia when performed after total ankle replacement and secured with plate and screw fixation. This modified Evans peroneus brevis tendon is useful in providing lateral ankle stability during or after primary and revision total ankle replacement.