Severe periprosthetic osteolytic lesions after the Ankle Evolutive System total ankle replacement

Sports Activity with Ankle Osteoarthritis and Total Ankle Arthroplasty

Background/Objectives: The interest in performing total ankle arthroplasty (TAA) to address end-stage ankle osteoarthritis (OA) is continuously growing. Sports activity plays an important role in our world. The literature is sparse regarding return-to-sports activity following TAA. The levels and types of sports in TAA are rarely reported. The purpose of this prospective case series study is to investigate sports activity in ankle osteoarthritis (OA) and TAA in terms of rate, frequency, type, and clinical outcomes with a minimum 2 years of follow-up after surgery. Methods: A total of 103 patients (105 implants, 52 female, and 51 male), mean age 60.5 years (range, 23-84 years) with end-stage ankle OA were treated using a three-component, uncemented, mobile-bearing VANTAGE Total Ankle System. The mean follow-up was 2.9 years (range, 2-5 years). Visual Analogic Scale Pain Score (VAS, 0-10 points), Ankle Dorsiflexion/Plantarflexion (DF/PF) range of motion (ROM; degrees), functional American Orthopaedic Foot and Ankle Society (AOFAS) Ankle/Hindfoot Score (0-100 points), Subjective Patients' Satisfaction Score (0-10 points), Sports Activity Rate, Sports Frequency Score, and sports type were assessed. Results: The mean preoperative VAS Pain Score was 6.7 points (range, 3-10 points) and 0.2 points for postoperative (range, 0-3 points) (p < 0.001). The mean DF/PF ROM was 24.9° preoperative (range, 0-60°) and 52.9° postoperative (range, 15-85°) (p < 0.001). The mean preoperative functional AOFAS Ankle/Hindfoot Score was 39.5 points (range, 4-57 points) and 97.8 points for postoperative (range, 75-100 points) (p < 0.001). The mean postoperative Subjective Patients' Satisfaction Score was 9.7 points (range, 7-10 points). The preoperative Sports Activity Rate was 31.1%, with 85.4% for postoperative (p < 0.001). All the groups exhibited substantial Sports Frequency Score increases (p < 0.001). The most practised sports were hiking, biking, fitness, and swimming. Conclusions: total ankle arthroplasty (TAA) is an effective treatment for end-stage ankle OA. TAA facilitates a noteworthy increase in sports activity. This research offers important sports insights to patients with ankle OA and TAA.

Bone grafting for periprosthetic bone cysts following total ankle arthroplasty

Aims

The purpose of this study was to assess the success rate and functional outcomes of bone grafting for periprosthetic bone cysts following total ankle arthroplasty (TAA). Additionally, we evaluated the rate of graft incorporation and identified associated predisposing factors using CT scan.

Methods

We reviewed a total of 37 ankles (34 patients) that had undergone bone grafting for periprosthetic bone cysts. A CT scan was performed one year after bone grafting to check the status of graft incorporation. For accurate analysis of cyst volumes and their postoperative changes, 3D-reconstructed CT scan processed with 3D software was used. For functional outcomes, variables such as the Ankle Osteoarthritis Scale score and the visual analogue scale for pain were measured.

Results

Out of 37 ankles, graft incorporation was successful in 30 cases. Among the remaining seven cases, four (10.8%) exhibited cyst re-progression, so secondary bone grafting was needed. After secondary bone grafting, no further progression has been noted, resulting in an overall 91.9% success rate (34 of 37) at a mean follow-up period of 47.5 months (24 to 120). The remaining three cases (8.1%) showed implant loosening, so tibiotalocalcaneal arthrodesis was performed. Functional outcomes were also improved after bone grafting in all variables at the latest follow-up (p < 0.05). The mean incorporation rate of the grafts according to the location of the cysts was 84.8% (55.2% to 96.1%) at the medial malleolus, 65.1% (27.6% to 97.1%) at the tibia, and 81.2% (42.8% to 98.7%) at the talus. Smoking was identified as a significant predisposing factor adversely affecting graft incorporation (p = 0.001).

Conclusion

Bone grafting for periprosthetic bone cysts following primary TAA is a reliable procedure with a satisfactory success rate and functional outcomes. Regular follow-up, including CT scan, is important for the detection of cyst re-progression to prevent implant loosening after bone grafting.

Outcomes of Total Ankle Arthroplasty After Periprosthetic Cyst Curettage and Bone Grafting

Total ankle arthroplasty (TAA) has become a popular management option for ankle arthritis. Periprosthetic osteolysis is one of the most common causes for reoperation in TAA. A CT scan should be done in all suspected osteolysis cases to confirm location, quantify size and aid in surgical planning. These patients are often asymptomatic with limited evidence regarding appropriate management. Smaller lesions should be monitored for progression in size. Periprosthetic cysts measuring 10-15mm in all three axes should be considered for debridment and curettage with autogenous bone grafting. The authors believe that bone grafting of large asymptomatic periprosthetic cysts could prevent implant failure.

Complications after total wrist arthroplasty

We reviewed the incidence and management of complications after total wrist arthroplasty, as reported in the literature, with so-called fourth-generation implants and other recent designs. While early intraoperative and postoperative complications, including fractures, tendon lacerations, infection, nerve compression, tendonitis, stiffness and chronic regional pain syndrome, had an acceptable incidence, late complications, such as periprosthetic osteolysis and implant loosening, occurred more frequently. Implant survival at 10 years was in the range of 70%-80% in most publications. Several of the implants have been modified or withdrawn. Instability and dislocation were frequent after a pyrocarbon spacer. Failed arthroplasties can be salvaged by revision arthroplasty or total wrist arthrodesis. Revision arthroplasty has a lower survival rate than primary arthroplasty and does not clearly offer important significant advantages over total wrist arthrodesis in terms of patient-reported outcome measures. Further development of prosthetic design, new materials and more knowledge on patient-related risk factors are needed.

Metal debris release is commonly seen from explanted total ankle replacements

This study aimed to characterise the damage mechanisms present on the metal components used in various contemporary total ankle replacements. Twenty-seven explanted total ankle replacements comprising 8 different designs (3 fixed bearing and 5 mobile bearing) were analysed using various explant analysis techniques. Pitting and scratching were the most commonly observed wear features. Microscopic analysis revealed metallic pitting on 52% of tibial components and 95% of talar components. Pitting was identified on more cobalt-chromium than titanium alloy tibial components (63% versus 0%). Non-contact profilometry confirmed the presence of pitting, with significant (p < 0.05) differences in the measured average surface roughness values of pitted and unpitted areas for tibial and talar components. There was macroscopically visible sliding plane scratching, indicating the presence of hard third body particles, on 78% of talar components. Changes to the non-articulating surfaces coatings in terms of coating loss and/or changes in reflectivity was identified visually on 80% of metal components. Scanning electron microscopy with energy dispersive X-ray spectroscopy identified metallic embedded debris in 19% of polyethylene inserts. This explant study demonstrates the release of metal debris from both the metallic tibial and talar component articulating surfaces and non-articulating surface coatings of various contemporary total ankle replacements. Metal particulate debris release from total ankle replacements may be more common than previously recognised. Metal debris should be considered in further study into the aetiology of failed total ankle arthroplasty.

Does Perioperative Use of Bisphosphonate Affect the Implant Revision Rate of Total Ankle Arthroplasty?

BACKGROUND

It is unknown whether perioperative bisphosphonate (BP) use reduces revision rates in total ankle replacement arthroplasty (TAR) although its effect has been demonstrated to be effective in reducing revision rates in total knee or hip replacement arthroplasty.

METHODS

We reviewed National Health Insurance Service data based on national health insurance service claims data and health care utilization, health screening, sociodemographic variables, medication history, operation codes, and mortality data for 50 million Koreans. From 2002 to 2014, 6391 of 7300 patients who underwent TAR were BP nonusers, whereas 909 patients were BP users. The revision rate according to BP medication and comorbidities was investigated. The Kaplan-Meier estimate and extended Cox proportional hazard model were also used.

RESULTS

The revision rate of TAR was 7.9% for BP users and 9.5% for BP nonusers, which showed no significant difference (P = .251). Implant survival over time decreased constantly. Adjusted hazard ratio for hypertension was 1.242 (P = .017), whereas other comorbidities such as diabetes had no effect on the revision rate of TAR.

CONCLUSION

We found that the perioperative BP use did not reduce the revision rate of TAR. Comorbidities (except hypertension) did not affect the revision rate of TAR. More research regarding various factors affecting the revision of TAR could be warranted.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Isolation and characterisation of wear debris surrounding failed total ankle replacements

Aseptic loosening and osteolysis continue to be a short- to mid-term problem for total ankle replacement (TAR) devices. The production of wear particles may contribute to poor performance, but their characteristics are not well understood. This study aimed to determine the chemical composition, size and morphology of wear particles surrounding failed TARs. A recently developed wear particle isolation method capable of isolating both high- and low-density materials was applied to 20 retrieved periprosthetic tissue samples from 15 failed TARs of three different brands. Isolated particles were imaged using ultra-high-resolution imaging and characterised manually to determine their chemical composition, size, and morphology. Six different materials were identified, which included: UHMWPE, calcium phosphate (CaP), cobalt chromium alloy (CoCr), commercially pure titanium, titanium alloy and stainless steel. Eighteen of the 20 samples contained three or more different wear particle material types. In addition to sub-micron UHMWPE particles, which were present in all samples, elongated micron-sized shards of CaP and flakes of CoCr were commonly isolated from tissues surrounding AES TARs. The mixed particles identified in this study demonstrate the existence of a complex periprosthetic environment surrounding TAR devices. The presence of such particles suggests that early failure of devices may be due in part to the multifaceted biological cascade that ensues after particle release. This study could be used to support the validation of clinically-relevant wear simulator testing, pre-clinical assessment of fixation wear and biological response studies to improve the performance of next generation ankle replacement devices. STATEMENT OF SIGNIFICANCE: Total ankle replacement devices do not perform as well as total hip and knee replacements, which is in part due to the relatively poor scientific understanding of how they fail. The excessive production of certain types of wear debris is known to contribute to joint replacement failure. This is the first study to successfully isolate and characterise high- and low-density wear particles from tissues collected from patients with a failed total ankle replacement. This article includes the chemical composition and characteristics of the wear debris generated by ankle devices, all of which may affect their performance. This research provides clinically relevant reference values and images to support the development of pre-clinical testing for future total ankle replacement designs.

Hybrid-Total Ankle Arthroplasty (H-TAA) for Failed Talar Component in Mobile-Bearing Total Ankle Arthroplasty

INTRODUCTION

Revision Total Ankle Arthroplasty (TAA) surgery due to TAA aseptic loosening is increasing. It is possible to exchange the talar component and inlay to another system for isolated talar component loosening in a primary mobile-bearing TAA: Hybrid-Total Ankle Arthroplasty (H-TAA). The purpose of this study was to analyze the results of the revision surgery of an isolated aseptic talar component loosening in a mobile-bearing three-component TAA with a H-TAA solution.

METHODS

In this prospective case study, nine patients (six women, three men; mean age 59.8 years; range 41-80 years) with symptomatic isolated aseptic loosening of the talar component of a mobile-bearing TAA were treated with an isolated talar component and inlay substitution. In all nine cases, a hybrid TAA revision surgery was performed by implanting a VANTAGE TAA talar and insert component (Flatcut talar component: six cases, standard talar component: three cases). The patients were reviewed with the pain score (VAS Pain Score 0-10), Dorsiflexion/Plantarflexion (DF/PF) Range of Motion (ROM; degrees), the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle/Hindfoot Score (0-100 points), Sports Frequency Score (Level 0-4), and subjective Patients' Satisfaction Score (0-10 points).

RESULTS

The average Pain score improved significantly from preoperative 6.7 points to postoperative 1.1 points (p < 0.001). Average Dorsiflexion/Plantarflexion ROM values increased significantly post-surgery: 21.7° preoperative to 45.6° postoperative (p < 0.001). The postoperative AOFAS scores were significantly greater than the preoperative values: 47.7 points preoperative, 92.3 points postoperative (p < 0.001). The sports activity improved from preoperative to postoperative where, preoperative, none of the patients were able to perform sports. Postoperative, eight patients were able to be sports-active again. The overall average postoperative level of sports activity was 1.4. The postoperative average patient's satisfaction was 9.3 points.

CONCLUSIONS

In painful talar component aseptic loosening of a three-component mobile-bearing TAA, H-TAA is a good surgical solution for reducing pain, restoring ankle function, and improving patients' life quality.

Early-Term Results of the Cadence Total Ankle Prosthesis: An European Noninventor Study

BACKGROUND

Although considerable literature can be found on the outcome of total ankle replacement (TAR), only a few studies have reported the results of the fixed-bearing Cadence prosthesis. This noninventor study reports a consecutive series of 60 Cadence TAR systems with a mean of 2.9 years' follow-up, focusing on clinical and radiographic outcomes and early complications. This study is the first to assess true postoperative radiographic ankle prosthesis range of motion (ROM) and to report an unanticipated serious adverse device effect.

METHODS

Sixty patients who underwent primary TAR with the Cadence prosthesis between July 2016 and July 2019 were clinically and radiographically evaluated preoperatively and at last follow-up after the procedure. Revisions, additional procedures, implant failure, and complications were reported according to the classifications of Vander Griend and Glazebrook. Radiographic outcomes included radiographic TAR ROM, bone-implant interface, and alignment parameters.

RESULTS

The survival rate of the prosthesis was 98.3%. The mean radiographic ankle ROM at the last follow-up was 24 degrees (9 degrees of dorsiflexion and 15 degrees of plantarflexion). The coronal and sagittal alignment of TAR was 90.8 degrees and 3.9 degrees, respectively. Bone-implant interface analysis revealed osteolysis in 9 ankles (15%) and radiolucent lines in 33 ankles (55%) occurring at both component interfaces. Intraoperative complications were 3 periprosthetic malleolar fractures (5%). Five talar implant fractures (implant failure of 8.3%) were observed, and 1 unexplained persistent pain that required a conversion from TAR to a tibiotalocalcaneal arthrodesis.

CONCLUSION

Clinical, radiograph ROM, implant position outcomes, and survival rate at an early-term follow-up of 2.9 years were similar to those reported in recent Cadence studies. However, this study reports 5 unanticipated talar implant fractures and a high rate of posterior radiolucent lines.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Complications after total ankle arthroplasty- A systematic review

BACKGROUND

Total ankle arthroplasty was developed as an alternative option to ankle arthrodesis in patients with end-stage ankle osteoarthritis. Multiple trials have assessed the outcomes of ankle arthroplasty, but complication risk or relative effectiveness is not systematized in literature.

AIM

Review complications of new designs of total ankle arthroplasty and the relationship between their severity and failure rates.

METHODS

We reviewed complications and revision rates of prospective studies of primary total ankle arthroplasty that included more than 50 patients and with minimum 2 years follow-up.

RESULTS

We included 22 studies (4412 ankles, median age of 61.9 years) with an adjusted mean follow-up time of 66.6 ± 40.9 months. The adjusted mean complication rate was 23.7 % (2.4-52 %), mostly high-grade complications (35.6 %). We found a statistically significant positive correlation between high- and medium-grade complications and revision rates.

CONCLUSION

Patient selection is crucial to successfully treat end-stage ankle osteoarthritis. Further multicenter clinical trials with consistent reporting of complications are warranted.

Periprosthetic Osteolysis as a Risk Factor for Revision After Total Ankle Arthroplasty: A Single-Center Experience of 250 Consecutive Cases

BACKGROUND

Periprosthetic osteolysis after total ankle arthroplasty (TAA) is a challenging problem. This study aimed to evaluate the prevalence of and predisposing factors for osteolysis and its effects on clinical outcomes.

METHODS

We enrolled 236 patients (250 ankles) who underwent primary TAA using a mobile-bearing HINTEGRA prosthesis, with a mean follow-up of 83.5 months (range, 36 to 182 months), and subsequently divided them into 2 groups: the osteolysis group (79 ankles) and non-osteolysis group (171 ankles). Clinical and radiographic outcomes were compared between the 2 groups, and a bivariable logistic regression analysis was performed to identify predisposing factors for the development of osteolysis.

RESULTS

In the osteolysis group (31.6% of the 250 ankles), the mean time of detection was 28.8 months postoperatively. Forty of these ankles were closely monitored without surgical treatment. Another 29 ankles underwent bone grafting and exchange of the polyethylene inlay, and the remaining 10 ankles underwent revision TAA or arthrodesis. All clinical outcome variables were significantly lower in patients with osteolysis, compared with those without osteolysis, at the final follow-up (p < 0.05). In the investigation of predisposing factors, only rheumatoid arthritis was identified as having a significant association with an increased prevalence of osteolysis (p = 0.030).

CONCLUSIONS

This study demonstrated that the prevalence of periprosthetic osteolysis after TAA was considerable and that the development of osteolysis negatively affected the clinical outcome. Therefore, the prevention and appropriate treatment of osteolysis are crucial for the satisfactory long-term survival of TAA.

LEVEL OF EVIDENCE

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

LIM Homeobox Transcription Factor 1-β Expression is Upregulated in Patients with Osteolysis after Total Ankle Arthroplasty and Inhibits Receptor Activator of Nuclear Factor-κB Ligand-Induced Osteoclast Differentiation in Vitro

BACKGROUND

Osteolysis is one of the most common problems that occurs after total hip and knee arthroplasty and has recently become a significant problem after total ankle arthroplasty (TAA). In this study, we investigated the role of LIM homeobox transcription factor 1-β (Lmx1b) in osteoclast differentiation. By evaluating the expression profiles associated with osteolysis following TAA treatment, Lmx1b was found to be differentially expressed in patients with osteolysis after TAA.

METHODS

To identify the important genes associated with osteolysis after TAA, RNA sequencing was performed by analyzing 8 patient samples: 5 primary TAA samples (control group) and 3 TAA samples revised for flexion instability (osteolysis group). By analyzing the differentially expressed genes and gene ontologies, Lmx1b expression was found to be upregulated in the osteolysis group compared to that in the control group. Focusing on the role of Lmx1b in bone cells, Lmx1b was overexpressed by a retrovirus in osteoclast precursor cells. The cultured cells were stained with tartrate-resistant acid phosphatase, and the expression of osteoclast-related genes was analyzed using real-time polymerase chain reaction.

RESULTS

Lmx1b overexpression in osteoclast precursors suppresses osteoclast formation and resorptive activity. The expression of osteoclast marker genes was significantly reduced during osteoclast differentiation by Lmx1b overexpression. Furthermore, Lmx1b is associated with nuclear factor of activated T cells 1 (NFATc1) and inhibited NFATc1 translocation into the nucleus.

CONCLUSIONS

These results provide novel insights into the anti-bone resorptive effect of Lmx1b on osteolysis after TAA and may lead to the development of effective preventative and therapeutic strategies for peri-implant osteolysis.

CT Scan Assessment and Functional Outcome of Periprosthetic Bone Grafting After Total Ankle Arthroplasty at Medium-term Follow-up

BACKGROUND

Periprosthetic cysts can occur in up to 95% of total ankle arthroplasties (TAA) and have been correlated with implant failure. The aim of this study was to determine the clinical and radiologic outcomes, using computed tomographic (CT) scan, after periprosthetic cyst bone grafting and assess for the minimum cyst size that should be grafted.

METHODS

A retrospective review was performed of all TAA procedures performed between 2007 and 2014 (n=93). A CT scan was done to assess cyst size and operative planning. Eight patients with 9 periprosthetic cysts larger than 1.75 cm³ were grafted and specimens sent for histology. The mean time to bone grafting was 7.3 (3.8-9.5) years. Functional outcome was assessed using the American Orthopaedic Foot & Ankle Society ankle score, visual analog scale, and Self-reported Foot and Ankle Score. A CT scan was performed at follow-up to assess graft incorporation and cyst size progression. The mean time to CT scan post grafting was 3.0 (0.7-4.7) years.

RESULTS

There was no implant malalignment identified and no differences in the pre- and postoperative functional scores. Preoperatively cysts had a mean volume of 8.16 (2.04-14.03) cm³. The mean percentage incorporation was 89% (69%-100%). Eight of the grafted cysts were considered successful on CT, with the ninth having 69% incorporation. Five cysts were not grafted, as they were below 1.75 cm³, and remained the same size or had minimal enlargement.

CONCLUSION

The satisfactory results in this small cohort suggests that prophylactic bone grafting may extend implant survival. We recommend that periprosthetic cysts greater than 1.75 cm³ be prophylactically bone grafted, and that cysts smaller than 1.75 cm³ be monitored for progression in size.

LEVEL OF EVIDENCE

Level IV, Case Series.

Low Rate of Peri-implant Osteolysis in Trabecular Metal Total Ankle Replacement on Short- to Midterm Follow-up

BACKGROUND

Peri-implant osteolysis is one of the major complications related to total ankle replacement. The aim of this study was to investigate the short- to midterm incidence of peri-implant osteolysis using computed tomography (CT) as imaging method for the Trabecular Metal Total Ankle (TMTA) implant representing a novel total ankle replacement (TAR) implant design regarding material and surgical technique.

METHODS

In total, 104 consecutive patients who had a primary TMTA replacement between March 2013 and October 2017 were included in the study. The radiographic evaluation included weightbearing anteroposterior and lateral views at baseline and after 3, 6, and every 12 months postoperatively. A helical CT was undertaken preoperatively and of the 80 patients available to follow up at least 12 months postoperatively, with average time interval between the TAR operation and the latest CT of 39 (range, 12-85) months.

RESULTS

Eight of 80 patients had altogether 11 osteolytic lesions around the components on CT images. Seven lesions were found in tibia, 3 in talus, and 1 in distal fibula. Four of the tibial lesions were situated in the medial malleolus and were not in contact with the prosthesis component. The sizes of the osteolytic lesions ranged between 7 and 20 mm, and the average volume of the lesions was 689 mm³.

CONCLUSION

We conclude that the risk of peri-implant osteolysis with the TMTA implant is minimal in short to midterm. The anatomic configuration, unique material, and surgical technique may all contribute to the TMTA implant having a low rate of peri-implant osteolysis.

LEVEL OF EVIDENCE

Level IV, case series.

The Hintegra total ankle replacement: survivorship, failure modes and patient reported outcomes in seventy consecutive cases with a minimum five year follow-up

PURPOSE

The Hintegra total ankle replacement (TAR) has been widely used worldwide for ankle arthroplasty since its introduction in 2000. The implant survivorship, patient reported outcomes, rate of periprosthetic cyst formation and reoperation rates are variably reported. The purpose of this study is to determine the functional outcomes and survivorship of the Hintegra TAR, in consecutive cases by multiple surgeons in a single UK institution, with a minimum of five year follow-up.

METHODS

A retrospective review of prospectively collected data for 70 consecutive Hintegra TAR cases performed between 2010 and 2014. Data collected included patient demographics, complications, reoperations, revisions and patient reported outcome measures (PROMS: AOS, MOX-FQ, pain VAS and EQ-5D 3L).

RESULTS

Seventy patients underwent Hintegra TAR (54 male/16 female) with an average age of 69 (range 48-84 years). Mean follow up was 76 months (range 60-104), 10 patients died during the follow-up. Implant survivorship was 81.7% at most recent follow-up. The commonest radiographic finding was periprosthetic cysts (n = 28, 40%): size range (7-40 mm). Nine patients required re-operation: six periprosthetic cyst debridement and grafting at a mean of 61 months (range 27-91), one lateral gutter debridement, one periprosthetic fracture and one debridement for deep infection. PROMS data was available for the majority of patients. Mean final follow-up scores were total AOS 35 (range: 0-97), MOX-FQ 36 (range: 2-93), pain VAS 34.6 (range: 0-100) and EQ-5D 3L Index 0.69 (range: 0.08-1.00).

CONCLUSION

Our experience demonstrates implant survivorship similar to other TAR studies. We have identified a high incidence of periprosthetic cysts and would recommend ongoing surveillance of these patients.

Mobile Anatomical Total Ankle Arthroplasty-Improvement of Talus Recentralization

Introduction: Total ankle arthroplasty (TAA) is becoming a more frequent treatment option for end-stage ankle osteoarthritis (OA) as outcomes measures are improving. However, there is concern that malalignment of TAA can result in premature failure of the implant. One of the malalignment issues is the talar sagittal malposition. However, a consensus on the significance of the sagittal translation of the talus in TAA is yet to be established. The aim of this study was, therefore, to clarify whether talus OA subluxation is normalized after the implantation of a mobile TAA. Methods: Forty-nine consecutive patients with symptomatic end-stage ankle OA underwent 50 cementless three-component mobile-bearing VANTAGE TAA with 21 right ankles (42%) and 29 left ankles (58%). Clinical and radiographic outcomes were assessed: Clinical variables: American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score (0–100), visual analogue scale (VAS, 0–10), and ankle range of motion (ROM). Radiological variables: medial distal tibial articular angle (mDTAA), anterior distal tibial articular angle (aDTAA) and lateral talar station (LTS). Results: The clinical results showed the mean improvement in AOFAS hindfoot score from 42.12 ± SE 2.42 (Range: 9–72) preoperatively, to 96.02 ± SE 0.82 (Range: 78–100) at a mean follow-up of 12 months, with a highly statistically significant difference (p < 0.00001). Pain score (VAS) was 6.70 ± SE 0.28 (Range 0–10) preoperatively, and 0.26 ± SE 0.12 (Range: 0–3) at 12-month follow-up, with a highly statistically significant difference (p < 0.00001). ROM measurements preoperatively showed a mean of 22.55° ± SE 1.51° (Range: 0–50°), which showed a statistically significant improvement (p < 0.0001) to 45.43° ± SE 1.56° (Range: 25–60°) 12 months postoperatively. The radiological analyses revealed the following results: On the coronal view, the mDTAA preoperatively was 88.61 ± SE 0.70 (Range: 78.15–101.10), which improved to 89.46 ± SE 0.40 (Range: 81.95–95.80) at 12 months (not statistically significant—p = 0.94). On the sagittal view, the preoperative values of the aDTAA showed 82.66 ± SE 0.84 (Range: 70.35–107.47), which improved to 88.98 ± SE 0.47 (Range: 82.83–96.32) at 12 months postoperatively, with a highly statistically significant difference between preoperative and 12-months values (p < 0.00001). The mean LTS values for all patients were 3.95 mm ± SE 0.78 (Range: −11.52 to 13.89) preoperatively and 1.14 mm ± SE 0.63 (Range: −10.76 to 11.75) at 12 months, with a statistically significant difference between preoperative and 12-month follow-up (p = 0.01). The review of the radiological TAA osteointegration at 12 months showed no cases of loosening of the implanted TAAs. Two cases (4%) showed a radiolucency and one case (2%) a cyst on the tibial component; no cases had a change on the talar component. No TAA complication/revision surgeries were documented. Conclusion: In the present study, the lateral talar station of anteriorly subluxated ankles showed a significant improvement, i.e., physiological centralization of the talus, in the postoperative period when a mobile-bearing TAA was performed. The anterior/posterior congruency between the talar component and the mobile polyethylene insert of the mobile-bearing VANTAGE TAA allows the sagittal translation of the talus relative to the flat tibial component, reducing the prosthesis strain and failure.

Patient-Reported Outcome Measures and Radiological Outcomes in Mobile-Bearing Total Ankle Arthroplasty With Varus or Valgus Deformity

BACKGROUND

There is increasing evidence that varus deformity does not negatively affect total ankle arthroplasty (TAA) outcomes, but there is a sparsity of evidence for valgus deformity. We present our outcomes using a mobile-bearing prosthesis for neutral, varus, and valgus ankles.

METHODS

This is a retrospective cohort study of consecutive cases identified from a local joint registry. In total, 230 cases were classified based on preoperative radiographs as neutral (152 cases), varus greater than 10 degrees (60 cases), or valgus greater than 10 degrees (18 cases). Tibiotalar angle was again measured postoperatively and at final follow-up (mean follow-up of 55.9 months). A total of 164 cases had adequate patient-reported outcome measures data (Foot and Ankle Outcome Score, Short Form-36 [SF-36] scores, and patient satisfaction) for analysis (mean follow-up of 61.6 months). The groups were similar for body mass index and length of follow-up, but neutral ankles were younger (P = .021).

RESULTS

Baseline scores were equal except SF-36 physical health, with valgus ankles scoring lowest (P = .045). Valgus ankles had better postoperative pain (P = .025) and function (P = .012) than neutral. Pre- to postoperative change did not reach statistical significance except physical health, in which valgus performed best (P = .039). Mean final angle for all groups was less than 5 degrees. There was no significant difference in revision rates.

CONCLUSION

Our study is consistent with previous evidence that varus deformity does not affect outcome in TAA. In addition, in our cohort, outcomes were satisfactory with valgus alignment. Postoperative coronal radiological alignment was affected by preoperative deformity but within acceptable limits. Coronal plane deformity did not negatively affect radiological or clinical outcomes in TAA.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Pathogenesis, Evaluation, and Management of Osteolysis Following Total Ankle Arthroplasty

Periprosthetic osteolysis is a common occurrence after total ankle arthroplasty (TAA) and poses many challenges for the foot and ankle surgeon. Osteolysis may be asymptomatic and remain benign, or it may lead to component instability and require revision or arthrodesis. In this article, we present a current and comprehensive review of osteolysis in TAA with illustrative cases. We examine the basic science principles behind the etiology of osteolysis, discuss the workup of a patient with suspected osteolysis, and present a review of the evidence of various management strategies, including grafting of cysts, revision TAA, and arthrodesis.Level of Evidence: Level V, expert opinion.

Six year results of the Rebalance mobile bearing total ankle replacement

BACKGROUND

We report the outcomes of a prospective consecutive series of 267 total ankle replacements (TARs) using a new mobile bearing Rebalance® prosthesis.

METHODS

Between April 2011 and December 2018, 267 consecutive Rebalance® prostheses were implanted in 255 patients at 3 different centers. Estimated survival curves with 95% confidence intervals were produced with the Kaplan-Meier method. 110 ankles were followed for at least 5 years and clinical and radiological outcomes were assessed in 92 of these ankles.

RESULTS

Twenty-one ankles were revised at a mean of 34 (7-60) months. The estimated survival was 90% (95% CI 86-95) at 5 years and 88.3% (95% CI 83.-94 at 6 years. The ankles followed for at least 5 years demonstrated a median Likert score of 1 (1-4). Radiolucent zones were detected in 14% and osteolytic cysts in 3%.

CONCLUSION

The survival rate of the Rebalance prosthesis conforms with other reports of similar designs. The satisfaction rate was high. Radiological zones and osteolytic cysts were found at a lower rate than usually reported for mobile bearing TARs. These results favour further use of this implant.

Results of Trabecular-Metal Total Ankle Arthroplasties With Transfibular Approach

BACKGROUND

Total ankle arthroplasty is an alternative for arthrodesis. The objective of this study was to investigate the safety of trabecular-metal ankle prosthetic system with transfibular approach and external frame and its association with changes in clinical and functional scores.

METHODS

Between May 2013 and June 2017, a total of 104 consecutive patients underwent primary total ankle arthroplasty with a trabecular metal implant. The prospective clinical and radiographic data were collected. The mean follow-up time was 43.6 (14.6) months.

RESULTS

Of 104 patients, 88 (89%) reported improved functioning and 65 (66%) were very satisfied with the surgery. Of the patients, 51 (50%) did not report any pain at the end of follow-up at all. The average Kofoed score was 37.6 (SD 17.4) points at baseline and 74.8 (SD 20.6) points at the end of follow-up. There were 37 additional procedures, and the complication rate was nearly 20%.

CONCLUSION

Trabecular-metal total ankle prosthesis showed promising clinical results concerning pain and function. At 5-year follow-up, osteolysis and component loosening were rare.

LEVEL OF EVIDENCE

Level IV, case series.

Does Patient-Specific Instrumentation Have a Higher Rate of Early Osteolysis Than Standard Referencing Techniques in Total Ankle Arthroplasty? A Radiographic Analysis

Introduction: Patient-specific instrumentation (PSI) has been developed for total ankle arthroplasty (TAA), with proven benefits. One concern regarding PSI is the need for more soft tissue dissection in order to accurately position the PSI guides, which has the theoretical disadvantage of increased osteolysis. The purpose of our study is to compare the incidence and magnitude of osteolysis for the INFINITY Total Ankle System between PSI and standard referencing (SR) techniques. Methods: Sixty-seven patients who underwent primary TAA using Prophecy (PSI) or SR technique between 2013 and 2015 were reviewed in a retrospective observational study. Osteolysis was assessed on radiographs at 2 years. The incidence was calculated by binomial distribution. The number of zones compromised and the magnitude of osteolysis was calculated using the median as a summary statistic and interquartile range as dispersion statistic. Fisher exact test was used to compare both groups, then a regression model was estimated to calculate the odds ratio for osteolysis. Results: Of the 67 TAAs, 51 were in the PSI group and 16 in the SR group. In the PSI group the incidence, number of compromised zones (CZ), and magnitude was 41% (25%-59%), 1 [1-2], and 2 [2-3], respectively. In the SR group these were 36% (13%-65%), 3 [2-3], and 3 [2-4], respectively. No significant differences were found (P = .46, P = .12, P = .33). A slightly higher risk of osteolysis was found in the PSI group (odds ratio = 1.33 [0.36-4.83]) (P = .46). The majority of lesions were in 1 zone with size of 2 to 5 mm (63% for all cohort, 64% PSI, 60% SR). Two cases underwent revision for aseptic loosening, 1 in the SR group and 1 in the PSI group. Conclusion: According to our data, there is no significant difference between PSI and SR in terms of risk, incidence, size and magnitude of osteolysis in the INFINITY Total Ankle System at 2 years. Levels of Evidence: Therapeutic, Level III, Retrospective cohort study.

3D, Weightbearing Topographical Study of Periprosthetic Cysts and Alignment in Total Ankle Replacement

BACKGROUND

We investigated the association between hindfoot residual malalignment assessed on weightbearing computed tomography (WBCT) images and the development of periprosthetic cysts (PPCs) after total ankle replacement (TAR). We hypothesized that PPCs would be found predominantly medially in the varus configuration and laterally in the valgus configuration.

METHODS

Cases of primary TAR with available WBCT imaging of the ankle were included in this retrospective study. The location of the PPC was marked and the following volumes were calculated: total (TCV), medial (MCV), central (CCV), and lateral (LCV) cyst volumes. Hindfoot alignment was measured as Foot and Ankle Offset (FAO), with 95% confidence intervals (95% CIs) calculated to define varus (<95% CI) and valgus (>95% CI) groups. Cyst volumes were compared between these 2 groups. The American Orthopaedic Foot & Ankle Society (AOFAS) score at the time of the WBCT was also retrieved. Receiver operating characteristic (ROC) curves were used to determine FAO thresholds for predicting an increased risk of PPC.

RESULTS

Forty-eight TARs (mean follow-up, 44.6 months) were included, 81% of which had at least 1 PPC. The mean FAO was 0.12% (95% CI, -1.12 to 1.36). Patients with greater residual malalignment (P < .001) and those with longer follow-up (P < .001) presented with increased TCV. In varus cases, the MCV was greater than the LCV (P = .042), with a threshold FAO value of -2.75% or less predicting an increased MCV. In valgus cases, the LCV was greater than the MCV (P = .049), with a FAO threshold value of 4.5% or more predicting an increased LCV.

CONCLUSION

In this series, the PPC volume after primary TAR significantly correlated with postoperative hindfoot malalignment and longer follow-up.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.

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.

The HINTEGRA total ankle arthroplasty

Aims

The purpose of this study was to determine the functional outcome and implant survivorship of mobile-bearing total ankle arthroplasty (TAA) performed by a single surgeon.

Patients and Methods

We reviewed 205 consecutive patients (210 ankles) who had undergone mobile-bearing TAA (205 patients) for osteoarthritis of the ankle between January 2005 and December 2015. Their mean follow-up was 6.4 years (2.0 to 13.4). Functional outcome was assessed using the Ankle Osteoarthritis Scale, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, 36-Item Short-Form Health Survey (SF-36) score, visual analogue scale, and range of movement. Implant survivorship and complications were also evaluated.

Results

There were significant improvements in all functional outcome categories between the preoperative and final follow-up assessments (p < 0.001). Patients showed marked improvement in clinical outcomes in terms of pain, function, and quality of life. The overall implant survivorship was 91.7% at a mean follow-up of 6.4 years. In all, 33 major complications were identified with a 15.7% rate, resulting in 12 prosthesis failures (5.7%). Periprosthetic osteolysis (19 cases; 9.0%) was the most frequent complication.

Conclusion

Mobile-bearing TAA resulted in improved functional outcomes, a low major complication rate, and excellent implant survivorship at a mean follow-up of 6.4 years. Cite this article: Bone Joint J 2019;101-B:695–701.

Conversion of painful tibiotalocalcaneal arthrodesis to total ankle replacement using a 3-component mobile bearing prosthesis

BACKGROUND

The aim of this study was to assess the short-term clinical and radiographic outcomes in patients who underwent conversion of a painful tibiotalocalcaneal arthrodesis to a total ankle replacement.

METHODS

Six patients with painful ankle arthrodesis after tibiotalocalcaneal arthrodesis were included in this study. In all patients, conversion to total ankle replacement was performed using a 3^rd-generation, non-constrained, cementless three-component prosthesis. The outcomes were analyzed at a mean follow-up of 3.4±1.9years (range 1.0-6.5).

RESULTS

One patient with painful arthrofibrosis underwent two open arthrolysis procedures at 1.2 and 5.6 years post index surgery, respectively. No revision of tibial or talar prosthesis components was necessary in this study. All patients reported significant pain relief and significant improvement in functional status.

CONCLUSION

In the present study, the conversion of a painful ankle arthrodesis following tibiotalocalcaneal arthrodesis to a total ankle replacement was a reliable surgical treatment.

Peri-prosthetic bone cysts after total ankle replacement. A systematic review and meta-analysis

BACKGROUND

Periprosthetic cystic osteolysis is a well-known complication of total ankle replacement. Several theories have been proposed for its aetiology, based on individual biomechanical, radiological, histopathology and outcome studies.

METHODS

Studies that met predefined inclusion/exclusion criteria were analysed to identify literature describing the presence of peri-prosthetic ankle cystic osteolysis. Quantitative data from the selected articles were combined and statistically tested in order to analyse possible relations between ankle peri-prosthetic bone cysts and specific implant characteristics.

RESULTS

Twenty-one articles were elected, totalizing 2430 total ankle replacements, where 430 developed peri-prosthetic cystic osteolysis. A statistically significant association (P<.001) was found between the presence of bone cysts and non-anatomic implant configuration, hydroxyapatite-coating, mobile-bearing and non tibial-stemmed implants. No significant association existed between the type of constraining and the presence of cysts (P>.05).

CONCLUSIONS

Non-anatomic, mobile-bearing, hydroxyapatite-coated and non tibial-stemmed total ankle replacements are positively associated with more periprosthetic bone cysts.

Revision of failed total ankle arthroplasty to a hindfoot fusion

Aims

The aim of this study was to present a series of patients with aseptic failure of a total ankle arthroplasty (TAA) who were treated with fusion of the hindfoot using a nail.

Patients and Methods

A total of 23 TAAs, in 22 patients, were revised for aseptic loosening and balloon osteolysis to a hindfoot fusion by a single surgeon (NH) between January 2012 and August 2014. The procedure was carried out without bone graft using the Phoenix, Biomet Hindfoot Arthrodesis Nail. Preoperative investigations included full blood count, CRP and ESR, and radiological investigations including plain radiographs and CT scans. Postoperative plain radiographs were assessed for fusion. When there was any doubt, CT scans were performed.

Results

The mean follow-up was 13.9 months (4.3 to 37.2). Union occurred at the tibiotalar joint in 22 ankles (95.6%) with one partial union. Union occurred at the subtalar joint in 20 ankles (87%) of cases with two nonunions. The nail broke in one patient with a subtalar nonunion and revision was undertaken. The only other noted complication was one patient who suffered a stress fracture at the proximal aspect of the nail, which was satisfactorily treated conservatively.

Conclusion

This study represents the largest group of patients reported to have undergone revision TAA to fusion of the hindfoot with good results Cite this article: Bone Joint J 2018;100-B:475–9.

Early Clinical and Radiographic Outcomes of Trabecular Metal Total Ankle Replacement Using a Transfibular Approach

BACKGROUND

In the last 2 decades, total ankle replacement has gained greater acceptance as a treatment option in patients with end-stage ankle osteoarthritis. However, there is a lack of literature on total ankle replacement using a lateral transfibular approach. Therefore, we sought to report early clinical and radiographic results for a patient cohort treated with total ankle replacement using a lateral transfibular approach, performed by a single surgeon.

METHODS

From October 2012 to December 2014, 55 primary total ankle arthroplasties using the Zimmer Trabecular Metal Total Ankle implant were performed in 54 patients (29 male and 25 female; mean age, 67.0 years). Clinical assessment, including pain evaluation and measurement of ankle range of motion, was conducted preoperatively and at the latest follow-up. Weight-bearing radiographs were used to determine angular alignment of the tibial and talar components and to analyze the bone-implant interface. Intraoperative and postoperative complications, revision surgeries, and survivorship were evaluated.

RESULTS

Implant survival was 93% at 24 months of follow-up. There were 3 revisions of a tibial component due to aseptic loosening. In 10 of the 55 cases, a secondary procedure was performed during follow-up. The mean follow-up duration was 26.6 ± 4.2 months. No delayed union or nonunion was observed for fibular healing. The average visual analog scale (VAS) pain score decreased significantly, from 7.9 ± 1.3 to 0.8 ± 1.2. The average total range of motion increased significantly, from 22.9° ± 12.7° to 40.2° ± 11.8°.

CONCLUSIONS

Early results of total ankle replacement using the Zimmer trabecular metal implant and the lateral transfibular approach demonstrated improved patient-reported outcomes and increased ankle motion at a minimum follow-up of 2 years. In the 55 consecutive cases, the fibular osteotomy required for access to the ankle healed without complications. Painful early loosening due to lack of osseous ingrowth required revision in 3 of 55 cases.

LEVEL OF EVIDENCE

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

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.

Bone cyst formation after ankle arthroplasty may be caused by stress shielding. A numerical simulation of the strain adaptive bone remodelling

BACKGROUND

The history of total ankle arthroplasty (TAA) has different evolution steps to improve the outcome. The third generation implants show an overall 8-year survival rate up to 93%. The main reported reason for early failure of TAA is aseptic loosening, cyst formation is also frequently reported. The aim of the present study is to use the finite element (FE) method to analyze the adaptive bone remodeling processes, including cyst formation after TAA.

METHODS

Bone characteristics applied to the model corresponded to information obtained from computed tomography. Finite element models for the tibia and the talus were developed and implant components were virtually implanted.

RESULTS

The calculated total bone loss is 2% in the tibia and 17% in the talus. Cysts and areas of increased bone density were detectable dependent on prosthesis design in the tibia and talus.

CONCLUSION

Our FE simulation provides a theoretical explanation for cyst formation and increasing bone density depending on implant design. However, cysts are not mono-causal, histo-chemical reactions should also be considered. Further clinical studies are necessary to evaluate the relevance of cyst formation and therapeutic strategies.

Can a Three-Component Prosthesis be Used for Conversion of Painful Ankle Arthrodesis to Total Ankle Replacement?

BACKGROUND

In patients with painful ankle arthrodesis, the surgical treatment is challenging, and may include takedown of ankle arthrodesis and conversion to a total ankle replacement (TAR). This procedure is technically demanding given the altered anatomy after arthrodesis. Few studies have evaluated TAR in the setting of prior arthrodesis.

QUESTIONS/PURPOSES

(1) What intraoperative and perioperative complications were observed in patients who underwent conversion of an ankle arthrodesis to a TAR? (2) Was durable fixation achieved at short term, and what was the alignment of the components? (3) What subsequent surgical procedures were performed, including revisions? (4) What improvements were observed in pain, tibiotalar range of motion (ROM), and quality of life?

METHODS

Between January 2007 and December 2014, 18 patients with a painful ankle arthrodesis underwent conversion to TAR at our tertiary referral center. During this period, the indications for conversion of ankle arthrodesis to TAR were tibiotalar nonunion or malunion after attempted arthrodesis in patients who declined revision ankle arthrodesis. The goal of revision surgery was to help patients regain hindfoot mobility and to decrease pain. During the study period, all patients who met indications were treated with a conversion procedure. Of the 18 patients included, 14 were men and four were women. The mean age of the patients was 51 ± 7 years. The mean followup was 54 ± 27 months, with no loss to follow up observed. The initial ankle arthrodesis was performed 6 ± 3.5 years before conversion to TAR. In all patients, the conversion to TAR was performed using a nonconstrained cementless three-component prosthesis. Intraoperative and postoperative complications, revision procedures, and prosthesis component loosening were evaluated. Weightbearing radiographs were used to determine the angular alignment of the tibial and talar components using α/β/γ angles and to analyze the bone-implant interface. Osseointegration was defined as visible trabecular structures at the bone-implant interface without radiolucent lines. The criteria for radiographic loosening was defined as subsidence or migration of prosthesis components and/or a cystic lesion with a diameter at least 2 mm. Clinical assessment included pain evaluation, measurement of ankle ROM, and quality of life.

RESULTS

Two of the 18 patients sustained an intraoperative medial malleolar fracture. In three patients, delayed wound healing was observed. At latest followup, four patients had incomplete osseointegration (posterior quarter of the bone-prosthesis interface on the tibial side). None of the 18 patients had prosthesis loosening. In all patients, both components were neutrally aligned. Two patients had painful arthrofibrosis with reduced ROM, which we treated with an open arthrolysis and exchange of mobile-bearing inlay; one other patient is considering a revision for substantial tibial component medial tilt with collapse of the medial arch. At the latest followup, the mean dorsiflexion and plantar flexion were 8.5° ± 3° and 15° ± 5°, respectively. The mean visual analog scale (VAS) score decreased from 9 ± 0.8 to 1.7 ± 1.6 (p < 0.001). The Short Form Health Survey questionnaire (SF-36) physical and mental outcome scores improved from 34 ± 5 to 74 ± 11 (p < 0.001) and from 49 ± 4 to 75.5 ± 7 (p < 0.001).

CONCLUSIONS

Conversion of an ankle arthrodesis to a TAR is a technically challenging procedure. In this small series, it was associated with frequent complications including arthrofibrosis, and functional outcomes including postoperative ROM were lower than reported for primary TAR. However, pain and function did improve. Further studies are necessary to address long-term clinical and radiographic outcomes in this patient cohort.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Patient selection for total ankle arthroplasty

Total ankle arthroplasty is a treatment option for end-stage osteoarthritis of the ankle, as is ankle arthrodesis. Many variables, including patient characteristics, are thought to influence clinical outcome and survival. As with any surgery, but especially with total ankle replacement (TAR), patient selection is considered critical for good (long-term) outcome. In this review, we summarize the available scientific evidence regarding patient characteristics and its influence on the results of TAR.

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.

Osteolysis in Total Ankle Replacement: How Does It Work?

Aseptic loosening of implants remains the most common reason for revision surgery for hip, knee, or ankle prostheses. Although a great scientific effort has been made to explain the underlying mechanisms it remains poorly understood, complex, and multifactorial. Many factors, including age, body weight, activity lesions, implant design, fixation methods, material proprieties, immunologic responses, and biomechanical adaptations to total ankle replacement all contribute to the development of periprosthetic osteolysis.

Medium to long-term results of 130 Ankle Evolutive System total ankle replacements-Inferior survival due to peri-implant osteolysis

BACKGROUND

The study reports the medium to long-term results of 130 Ankle Evolutive System total ankle replacements operated at a single-centre. Previously high amount of peri-implant osteolysis was reported from the same material.

METHODS

Between 2002 and 2008 one hundred and thirty consecutive ankles replaced with AES ankle prosthesis were followed both radiologically and clinically.

RESULTS

The five-year survival was 87.3% (95% confidence interval (CI) 80.0-92.0%), and ten-year survival 74.9% (95% confidence interval (CI) 65.4-82.2%) at a median follow-up time of 96 months (range 2-161; 8 years). Peri-implant osteolysis was found in 91 (70%) ankles, marked in 78 (60%). 44 ankles (34%) have been revised by filling of the cavities, 24 (18%) by fusion, and 6 by further replacement, resulting in the revision rate of 58%. Osteolysis was the main reason for all revisions. The improvement of the Kofoed Score and pain points was significant (all p<0.0001), and the subjective patient satisfaction was good.

CONCLUSIONS

Outcome of the current study was seriously affected by osteolysis and is inferior compared to previous reports.

Management of Talar Component Subsidence

Component subsidence has been found to be the top complication that leads to failure of the total ankle arthroplasty (TAA). The cause of subsidence formation is unclear, and is multifactorial. Talar subsidence is more frequently met than tibial subsidence, and the subsequent big bone loss is demanding to handle. As a revision treatment option, neither a revision TAA nor a salvage ankle and/or hindfoot arthrodesis procedure is easy to perform or can obtain a definite outcome. The Salto XT can be used to treat most of the TAA systems available for use in the United States with acceptable short-term outcomes.

Are periprosthetic osteolytic lesions in ankle worth bone grafting?

BACKGROUND

We retrospectively evaluated the medium-term follow-up of bone grafting due to periprosthetic osteolytic lesions in ankles.

METHODS

34 ankles (32 patients) with total ankle arthroplasty (TAA) underwent re operation. Indications were large periprosthetic osteolytic lesions or continuous growing of the lesions. The osteolytic lesions were imaged by CT before reoperation and once a year after that. The mean CT follow-up after re operation was 3.8 years (range, 2-6.2 years). Patient's clinical outcome was also monitored.

RESULTS

Osteolysis continued to progress in 44 bone grafted lesions (68%) in CT follow-up. Pain (p=0.04) and location of the lesion (p=0.03) were associated with progression of osteolysis. In 18 bone grafted osteolytic lesions (28%) the radiological survival remained excellent. 25 out of 34 ankles showed improvement of the function after bone grafting.

CONCLUSIONS

There is no established treatment protocol for osteolysis around TAA. Bone grafting is one alternative in the treatment of osteolytic lesions.

Change in Talar Translation in the Coronal Plane After Mobile-Bearing Total Ankle Replacement and Its Association with Lower-Limb and Hindfoot Alignment

BACKGROUND

Mobile-bearing total ankle replacement (TAR) enables motion at the tibial implant-polyethylene insert interface. This motion could lead to coronal translation of the talus relative to the tibia and may affect radiographic outcome. We aimed to assess the translation of the talus before and after mobile-bearing TAR to determine whether translation of the talus after TAR is associated with coronal plane alignment of the lower limb and hindfoot as well as to investigate the complications associated with talar translation.

METHODS

In this retrospective cohort study, we enrolled 153 patients (159 ankles) with a minimum follow-up of 3 years who underwent mobile-bearing TAR. The location of the talus in the coronal plane was quantified with use of talar center migration (TCM) on anteroposterior radiographs both preoperatively and at postoperative intervals, and the relationship between them was investigated. Radiographic parameters in the coronal plane-including mechanical axis deviation (MAD), lateral distal tibial angle (LDTA), hindfoot alignment angle, and hindfoot moment arm-were measured. The relationship between TCM and radiographic parameters in the coronal plane was assessed in each group. The complications associated with talar translation were examined during the same period.

RESULTS

During the 36-month follow-up period, the postoperative TCM showed a strong relationship with the preoperative TCM. Moreover, MAD, LDTA, and hindfoot alignment were significantly related to talar translation (p < 0.01). Complications included medial malleolar impingement in 5 cases (including delayed medial malleolar fracture due to medial impingement in 2 cases), insert dislocation in 1 case, and edge-loading in 2 cases; all of the cases with complications demonstrated implant overhang with talar translation.

CONCLUSIONS

Talar translation in the coronal plane after mobile-bearing TAR correlates with the preoperative talar translation. Talar translation arises from deformities of MAD, LDTA, and hindfoot alignment, and it may be accompanied by various complications, as observed on coronal radiography. Therefore, additional realignment procedures for coronal malalignment should be considered to prevent talar translation after mobile-bearing TAR.

LEVEL OF EVIDENCE

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

In-Patient Trends and Complications After Total Ankle Arthroplasty in the United States

The number of total ankle arthroplasties (TAAs) performed annually in the United States has increased. The purpose of this study was to evaluate the in-patient demographics, complications, and readmission rates of patients after TAA at academic medical centers in the United States. The University HealthSystems Consortium administrative database was searched for patients who underwent TAA in 2007 to 2011. A descriptive analysis of demographics was performed, followed by a similar analysis of clinical benchmarks, including hospital length of stay, hospital direct cost, in-hospital mortality, and 30-day readmission rates. The study included 2340 adult patients with a mean age of 62 years (47% men and 53% women) who underwent TAA. The majority of patients were Caucasian (2073; 88.5%). Average hospital length of stay was 2.2±1.26 days. Average total direct cost for the hospital was $16,212±7000 per case, with 49.7% of patients having private insurance. In-hospital mortality was less than 1%, and overall complications were 1.4%. Complications after discharge included deep venous thrombosis (2.3%), reoperation (0.7%), and infection (3.2%). A readmission rate of 2.7% within the first 30 days from the time of discharge occurred. Total ankle arthroplasty in the United States is a relatively safe procedure with low overall complication rates. Patients who are male, have a history of community-acquired pneumonia, and have a larger number of preoperative comorbidities had a significant increased risk of developing 1 complication within 30 days of surgery.

Ballooning osteolysis in 71 failed total ankle arthroplasties

Background and purpose - Aseptic loosening is a major cause of failure in total ankle arthroplasty (TAA). In contrast to other total joint replacements, large periarticular cysts (ballooning osteolysis) have frequently been observed in this context. We investigated periprosthetic tissue responses in failed TAA, and performed an element analysis of retrieved tissues in failed TAA. Patients and methods - The study cohort consisted of 71 patients undergoing revision surgery for failed TAA, all with hydroxyapatite-coated implants. In addition, 5 patients undergoing primary TAA served as a control group. Radiologically, patients were classified into those with ballooning osteolysis and those without, according to defined criteria. Histomorphometric, immunohistochemical, and elemental analysis of tissues was performed. Von Kossa staining and digital microscopy was performed on all tissue samples. Results - Patients without ballooning osteolysis showed a generally higher expression of lymphocytes, and CD3+, CD11c+, CD20+, and CD68+ cells in a perivascular distribution, compared to diffuse expression. The odds of having ballooning osteolysis was 300 times higher in patients with calcium content >0.5 mg/g in periprosthetic tissue than in patients with calcium content ≤0.5 mg/g (p < 0.001). Interpretation - There have been very few studies investigating the pathomechanisms of failed TAA and the cause-effect nature of ballooning osteolysis in this context. Our data suggest that the hydroxyapatite coating of the implant may be a contributory factor.

Autoinflammation Around AES Total Ankle Replacement Implants

BACKGROUND

Failure of total ankle replacement (TAR) can be characterized by early peri-implant osteolysis even in the presence of very modest numbers of wear particles. The hypothesis of the study was that this reaction is in part mediated by autoinflammatory responses mediated via damage-associated molecular patterns (DAMPs, danger signals) and pattern-recognizing danger signal receptors (PRRs).

METHODS

Peri-implant tissue and control samples from 10 patients with AES implants were immunostained for hypoxia inducible factor-1α (HIF-1α), activated caspase-3, high-mobility group box 1 (HMGB1), receptor for advanced glycation end product (RAGE), and toll-like receptors TLR2 and TLR4. Results were evaluated on a 0 to 4 scale (from 0% to >50% stained area).

RESULTS

Peri-implant tissue around failed TAR implants had a relatively high mean HIF-1α score of 3 on a scale, which however was similar in control samples. HMGB1 (a DAMP) was seen to be mobilized from nuclei to cellular cytoplasm, and the active caspase-3(+) cells were increased. All PRRs were increased in revision samples.

CONCLUSIONS

Increased expression of HMGB1 and other danger signals together with increased PRR-dependent responsiveness could contribute to autoinflammatory peri-implantitis, multilocular cyst formation, and osteolysis in failed TAR implants.

LEVEL OF EVIDENCE

Level IV, case series.

Periprosthetic osteolysis after AES total ankle replacement: Conventional radiography versus CT-scan

BACKGROUND

The aim of this study was to compare conventional X-rays and CT-scan in detecting peri-prosthetic osteolytic lesions, a major concern after total ankle replacement (TAR).

METHODS

We prospectively assessed 50 patients (mean age 56 years), consecutively operated on by the same senior surgeon, between 2003 and 2006 and with a mean follow-up period of 4 years (range, 2-6.2). The component used was AES total ankle replacement. The etiologies for total ankle arthroplasty were: posttraumatic in 50%, osteoarthritis secondary to instability in 36%. Plain radiographs were analyzed by 4 independent observers, using a 10-zone protocol (location) and 5 size categories.

RESULTS

At 4-year follow-up, all patients had been CT-scan assessed with the same protocol by 2 independent observers. Plain radiographs showed dramatic progression of severe periprosthetic lyses (>10mm): from 14% to 36% of interface cysts for the tibial component respectively at 2 and 4-year follow-up and from 4% to 30% for the talar implant. The talar component was more accurately assessed by CT-scan (mean frontal and sagittal talar lesion: from 270 mm2 to 288 mm2 for CT-scan versus 133 mm2 to 174 mm2 for X-rays). For tibial cysts, axial views showed larger lesions (313 mm2 than frontal (194 mm2) or sagittal (213.5 mm2) views. At 4-year follow-up, 24% of patients had revision with curetage or arthrodesis, and at 7 years follow-up 38% were revised.

CONCLUSION

These results are similar to recent AES series, justifying withdrawal of this device. CT-scan was more accurate than X-rays for detecting and quantifying periprosthetic osteolysis. We recommend a yearly radiological control and CT-scan in case of lesion on X-rays.

Effect of Coronal and Sagittal Alignment on Outcome After Mobile-Bearing Total Ankle Replacement

BACKGROUND

Comparably high revision rates are reported after total ankle replacement (TAR). Therefore, further critical analysis of the influence of implant position on clinical outcome is necessary.

METHODS

We analyzed the reliability and predictive value of previously published pre- and postoperative coronal and sagittal parameters in routine ankle radiographs on the clinical outcome of 84 HINTEGRA total ankle replacements (Newdeal, Lyon, France; Integra, Plainsboro, New Jersey). Mean follow-up was 4.0 years, and 15.5% of the TARs had revision surgery.

RESULTS

Mean postoperative American Orthopaedic Foot & Ankle Society ankle-hindfoot score was 71.3; mean postoperative verbal rating scale for pain was 3.1; and mean postoperative ankle range of motion was 26.4 degrees. Most tested radiologic parameters showed moderate or high intra- and interobserver reliability. With the numbers available, no significant difference in clinical outcome for all tested radiologic parameters could be detected.

CONCLUSION

Our results indicate that mild malalignment of TAR, as assessed on routine ankle radiographs, did not affect midterm clinical outcome after TAR. Further multicenter studies with longer follow-up are needed to support our findings.

LEVEL OF EVIDENCE

Level III, comparative series.

Total ankle replacement for posttraumatic arthritis. Similar outcome in postfracture and instability arthritis: a comparison of 90 ankles

BACKGROUND AND PURPOSE

Most studies on total ankle replacement (TAR) have used a case mix of patients. We evaluated the outcome of TAR performed for end-stage arthritis either because of fracture or ligamentous injury.

PATIENTS AND METHODS

We prospectively followed 88 consecutive patients (50 postfracture ankles and 40 ankles with instability arthritis (2 bilateral)) who underwent TAR between 2001 and 2009. Mean follow-up for both groups was 5 years.

RESULTS

Preoperative varus deformity of 10° or more was present in 23 ankles in the instability group. At 6 years, survival with revision or salvage fusion as an endpoint was 87% (95% CI: 74-99) in the postfracture group and 79% (95% CI: 63-94) in the instability group. Progressive periprosthetic osteolysis was seen in 23 ankles, and required salvage fusion in 6. The number of reoperations was similar in both groups. Clinical outcome, as assessed with 2 ankle scores and 2 questionnaires, showed good results and was similar at the latest follow-up.

INTERPRETATION

The outcome was similar in the postfracture and instability groups and also similar to that reported in series including a case mix of patients. In contrast to earlier reports, preoperative frontal plane deformity in this series was not identified as a risk factor for failure.

Etiopathogenesis of osteolytic cysts associated with total ankle arthroplasty, a histological study

BACKGROUND

Osteolytic cyst formation after total ankle arthroplasty has been identified in recent years and is probably an important problem with longer follow-up. The aim of this study is to describe the outcome of a histological analysis of samples from periprosthetic intra-osseous cysts and joint capsules, retrieved during revision surgery after primary total ankle arthroplasty.

METHODS

All samples (n=22) were analyzed and scored using a semi-quantitative grading system. The main items of interest were polyethylene (PE) particles, metal particles, histiocytes, and giant cells.

RESULTS

All cyst samples contained PE particles. A similar number of PE particles were found in talar and tibial cysts. No significant correlation between the number of PE particles and time to reoperation was found. Metal particles were found in 16 cysts.

CONCLUSIONS

We suggest that PE particles are not the primary cause of osteolytic cyst formation but a secondary contributing factor probably accelerating the process of osteolysis. It is likely that implant design, biomechanical factors and local anatomic-physiological factors play an important role.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level IV.