Perioperative complications and learning curve of the Mobility Total Ankle System

Analyzing Learning Curve Effects: Total Ankle Replacement Design Switch and Long-Term Survival

Different aspects of the learning curve in total ankle replacement (TAR) have been studied in the short to mid-term, with 30 cases often considered critical. However, its impact on long-term (10- and 15-year) survival remains unclear. Therefore, we retrospectively analyzed 77 consecutive TARs performed by one orthopedic surgeon. The main outcome was long-term survival between cases 1-30 and 31-77 using the Kaplan-Meier with Competing Risk Analyses. Secondarily, we used Moving Average Method with LOESS regression to confirm the learning curve based on the perioperative complications. Thirdly, associations between perioperative complications and operation time on long-term survival were assessed using Cox proportional hazard models. The 10-year survival of cases 1-30 was 89.9% (95% CI 70.4-96.5), and of 31-77, 92.4% (95% CI 7745- 97.5) (p = .58). The 15-year survival was 81.8% (95% CI 59.5-91.8) and 74.8% (95% CI 52.4-86.6), respectively (p = .97). The long-term survival rate for the TAR that endured perioperative complication was 96.70% (95% CI 90.28-103.12), and for the uncomplicated TAR 87.50% (95% CI 77.12-97.88%) (p = .24). Operating time nor occurrence of perioperative fractures were significantly associated with long-term survival (p = .11 and 0.26, respectively). However, moving average method revealed a significant decreasing trend with a cut-off value of 33 procedures regarding the marginal probability of perioperative osseous complications (p < .01). In conclusion, surgeons should note a learning curve when adapting arthroplasty procedures. After the prosthesis design switch, the learning curve regarding perioperative osseous complications was confirmed at 33 TAR. The switch did not affect long-term survival.

Effect of Preoperative Coronal Plane Alignment on Actual Versus Predicted Alignment Using Patient Specific Instrumentation in Total Ankle Replacement

Alignment in total ankle replacement is important for success and implant survival. Recently there has been the introduction and adoption of patient specific instrumentation for implantation in total ankle replacement. Current literature does not evaluate the effect of preoperative deformity on accuracy of patient specific instrumentation. A retrospective radiographic analysis was performed on 97 consecutive patients receiving total ankle replacement with patient specific instrumentation to assess the accuracy and reproducibility of the instrumentation. Subgroup analysis evaluated the effect of preoperative deformity. All surgeries were performed by fellowship trained foot and ankle surgeons without industry ties to the implants used. Preoperative and postoperative films were compared to plans based on computerized tomography scans to assess how closely the plan would be implemented in patients. Overall postoperative coronal plane alignment was within 2° of predicted in 87.6% (85 patients). Similarly, overall postoperative sagittal plane alignment was within 2° of predicted in 88.7% (86 patients). Tibial implant size was accurately predicted in 81.4% (79 patients), and talus implant size was correct in 75.3% (73 patients). Patients with preoperative varus deformity had a higher difference between predicted and actual postoperative alignment compared to valgus deformity (1.1° compared to 0.3°, p = .02). A higher average procedure time was found in varus patients, and more adjunctive procedures were needed in patients with varus or valgus deformity, but these were not significant, p > .5. Surgeons can expect a high degree of accuracy when using patient specific instrumentation overall, but less accurate in varus deformity.

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

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

Quality of Outcomes Research in Total Ankle Arthroplasty

Total ankle arthroplasty is a topic that has recently gained increasing interest, largely due to the improved outcomes, which have been demonstrated by short- and mid-term research studies on the newer, third-generation implant designs. The purpose of this review is to provide an updated assessment of the quality of outcomes research on total ankle arthroplasty.

Learning curve of total ankle arthroplasty: a systematic review

INTRODUCTION

Together with ankle arthrodesis, total ankle arthroplasty is now accepted as a first-line intervention in the management of end-stage arthritis of the ankle. The evidence regarding how outcomes are affected by surgeon experience is inconsistent; we performed a systematic review to evaluate the effect of a learning curve in total ankle arthroplasty outcomes.

METHODS

An electronic database search was performed in PubMed, Embase, ISI Web of Science and Cochrane trials. Two reviewers independently conducted a two-stage title/abstract and full text screening. English-language original research studies comparing patient-reported outcome measures (PROMs), complication/revision rates, operative time, length of stay or radiation exposure according to surgeon experience were included. Quality assessment was performed using the methodological index for non-randomised studies.

RESULTS

All but one included study report either improved PROMs, reduced complication/revision rate, reduced hospital stay length/operative time or reduced radiation exposure with increasing surgeon experience. However, the majority of these findings lack statistical significance. Two studies assessing the plateau of the learning curve report a wide range of plateau thresholds between 9 and 39 cases.

CONCLUSION

This review finds a largely non-significant trend towards improvements in PROMs, complication, and revision rates with improved surgeon experience. The lack of statistical significance in a number of studies may be partially explained by methodological flaws, with more suitably designed studies reporting significant improvements. Future research into the effect of advancements in implant design and insertion guides is required to further characterise the magnitude of the learning curve and guide both mitigation and learning strategies.

A combined FE-hybrid MCDM framework for improving the performance of the conical stem tibial design for TAR with the addition of pegs

BACKGROUND AND OBJECTIVES

The conical stemmed design of the tibial component for total ankle replacement (TAR) (example Mobility design) uses a single intramedullary stem for primary fixation. Tibial component loosening is a common mode of failure for TAR. Primary causes of loosening are lack of bone ingrowth due to excessive micromotion at the implant-bone interface and bone resorption due to stress shielding after implantation. The fixation feature of the conical stemmed design can be modified with the addition of small pegs to avoid loosening. The aim of the study is to select the improved design for conical stemmed TAR using a combined Finite Element (FE) hybrid Multi-Criteria Decision-Making (MCDM) framework.

METHODS

The geometry and material properties of the bone for FE modeling were extracted from the CT data. Thirty-two design alternatives with varying pegs in number (one, two, four, eight), location (anterior, posterior, medial, lateral, anterior-posterior, medial-lateral, equally spaced), and height (5 mm, 4 mm, 3 mm, 2 mm) were prepared. All models were analyzed for dorsiflexion, neutral, and plantarflexion loading. The proximal part of the tibia was fixed. The implant-bone interface coefficient of friction was taken as 0.5. The implant-bone micromotion, stress shielding, volume of bone resection, and surgical simplicity were the important criteria considered for evaluating the performance of TAR. The designs were compared using a hybrid MCDM method of WASPAS, TOPSIS, EDAS, and VIKOR. The weight calculations were based on fuzzy AHP and the final ranks on the Degree of Membership method.

RESULTS

The addition of pegs decreased the mean implant-bone micromotions and increased stress shielding. There was a marginal decrease in micromotion and a marginal increase in stress shielding when the peg heights were increased. The results of hybrid MCDM indicated that the most preferable alternative designs were two pegs of 4 mm height in the AP direction to the main stem, two pegs of 4 mm height in the ML direction, and one peg of 3 mm height in the A direction.

CONCLUSIONS

Outcomes of this study suggest that the addition of pegs can reduce the implant-bone micromotions. Modified three designs would be useful by considering implant-bone micromotions, stress shielding, volume of bone resection, and surgical simplicity.

Fast-Track for Total Ankle Replacement: A Novel Enhanced Recovery Protocol for Select Patients

BACKGROUND

Enhanced recovery after surgery programs, also called fast-track protocols, were developed and successfully applied in the last decade for hip and knee reconstruction. Specific fast-track protocols have not yet been applied to ankle prostheses. The aim of the study was to develop and validate an enhanced recovery protocol for total ankle replacement (TAR) evaluating the clinical and radiographic results. We hypothesize that on the basis of well-defined pre- and postoperative characteristics, the current knowledge on ankle replacement, and referring to hip and knee reconstruction, it is possible to identify a "patient type" to be safely eligible to a Fast-Track Protocol with at least comparable results and without increasing the complications risk.

METHODS

We identified 8 predictive variables that might affect the outcome of TAR. Those variables were the body mass index, the state of anxiety or depression, the functional preoperative status, ankle equinus, the coronal malalignment, the surgical time, the surgical accessory procedures, and the bone quality. These characteristics were evaluated for each patient with almost validated outcome tools attributing a specific score. Based on the score obtained, the patients were divided into 2 groups: the Standard Protocol group (Control Group) and the Fast-Track Protocol group (Study Group). The main difference between treatment of the 2 groups relates to the use of postoperative plaster casts: in the Fast-Track group the cast was removed the first day after surgery and walking was allowed in sports shoes assisted with crutches, whereas in the Standard Protocol group, the cast was removed after 3 weeks. Clinical and radiographic evaluation was performed for all patients preoperatively and postoperatively every 6 months.

RESULTS

A total of 163 patients received a score between 1 and 5 and were included in the control group (Standard Protocol); 47 patients received a score of 0 and were allocated to the study group (Fast-Track Protocol). Clinically, except for the preoperative American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot scale score, no statistically significant differences were recorded in the multiple comparisons between the 2 groups. No significant differences were found regarding complications.

CONCLUSION

In selected patients, it is possible to apply an enhanced recovery protocol of rehabilitation, focused on immediate weightbearing and mobilization without any plaster or boot.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Transfibular total ankle arthroplasty : a new reliable procedure at five-year follow-up

AIMS

This study reports updates the previously published two-year clinical, functional, and radiological results of a group of patients who underwent transfibular total ankle arthroplasty (TAA), with follow-up extended to a minimum of five years.

METHODS

We prospectively evaluated 89 patients who underwent transfibular TAA for end-stage osteoarthritis. Patients' clinical and radiological examinations were collected pre- and postoperatively at six months and then annually for up to five years of follow-up. Three patients were lost at the final follow-up with a total of 86 patients at the final follow-up.

RESULTS

A total of 86 patients were evaluated at a mean follow-up of 65.4 months (60 to 90). At five-year follow-up, statistically significant improvements (p < 0.001) were found in the mean American Orthopaedic Foot & Ankle Society Ankle Hindfoot Score (from 33.8 (SD 14.3) to 86.1 (SD 8.8)), visual analogue scale for pain (from 8.5 (SD 1.7) to 1.5 (SD 1.2)), Short Form-12 Physical and Mental Component Scores (from 29.9 (SD 6.7) and 43.3 (SD 8.6) to 47.3 (SD 7.5) and 52.2 (SD 8.0), respectively), and mean ankle dorsiflexion and plantarflexion (from 6.2° (SD 5.5°) and 9.6° (SD 5.8°) to 23.9° (SD 7.7°) and 16.9° (SD 7.2°), respectively). Radiologically, the implants maintained neutral alignment without subsidence. Tibial or talar radiolucency was found in eight patients, but none of these patients was symptomatic. At five-year follow up, 97.7% of implants (95% confidence interval 91.2 to 99.4) were free from revision or removal with 84 implants at risk. We recorded two cases (2.3%) of failure for septic loosening.

CONCLUSION

Transfibular TAA is safe and effective with a high survival rate at mid-term follow-up and satisfactory clinical and radiological results. Further studies are required to determine the long-term performance of these implants. Cite this article: Bone Joint J 2022;104-B(4):472-478.

Effect of artificial surface shapes and their malpositioning on the mechanics of the replaced ankle joint for possible better prosthesis designs

BACKGROUND

The clinical outcomes of total ankle replacement are limited by prosthesis component malpositioning during surgery. The goal of this study is to assess the mechanical impact of this malpositioning in a validated computer model.

METHODS

In a previously developed multi-body dynamic model of the human ankle complex three different artificial implants were designed, each one presenting a different approximation of the natural articular surfaces of the corresponding specimen. The most common implant translational and rotational malpositionings were defined and mimicked. Dynamic simulations of joint motion were run for the various surfaces and malpositionings. The same input loading conditions derived from a previous in-vitro experiment on the corresponding natural specimen were applied.

FINDINGS

From load-displacement graphs it was observed that all three artificial surfaces reproduced well physiological motion between the calcaneus and the tibia/fibula, with a maximum difference of 2°. It was found that antero-posterior translation of either the tibial or the talar component and inclination of the tibial component in the sagittal plane led to considerable increases in the range of motion. Antero-posterior and dorsiflexion of the tibial component resulted in an increased internal-external rotation by up to 3.5° and 4.0°, respectively. The corresponding increase of inversion-eversion was 5.0° and 6.5°.

INTERPRETATION

This study showed that relatively small surgical errors have great consequences in replaced joint mechanics. The present model can be used in future studies to analyse the effect of malpositioning with any specific current total ankle prosthesis.

Learning curve assessment for total ankle replacement using the transfibular approach

BACKGROUND

Total ankle arthroplasty is an increasingly effective option for the treatment of end-stage arthritis. One recent innovation utilizes a transfibular, lateral approach. Like any new system, there is likely a learning curve associated with its use. We analyzed a series of patients who received a total ankle arthroplasty via a transfibular approach to state if it is possible to identify and to evaluate effects of a learning curve in the use of this novel total ankle replacement system.

METHODS

76 consecutive patients meeting inclusion and exclusion criteria were retrospectively analyzed. All patients had a minimum of 24 months of follow-up. Intraoperative parameters, preoperative and postoperative subjective outcome scores, radiographic parameters, and complications were recorded and evaluated.

RESULTS

There were significant learning curve effects on various surgical and postoperative parameters. Surgical time decreased with the curve stabilizing after the 16th patient. With regard to patient outcomes, a learning curve was identified for the VAS, AOFAS, and SF-12 MCS scores. The number of patients required to stabilize these curves were 21, 13, and 16, respectively. Alignment as measured by alpha and gamma angles also improved with experience, with the curves stabilizing at 18 and 15 patients, respectively. There was a larger number cases required for complication rates, with the curve stabilizing after the 39th patient. No significant learning curve was found for ankle ROM, SF-12 PCS, beta angle, tibio-talar ratio (TTR), or tibio-talar surface angle (TTS).

CONCLUSIONS

This study demonstrates a significant learning curve with respect to operative time, patient outcomes, and radiographic parameters. Extrapolating this information, we urge surgeons to adequately familiarize themselves with any new implant through a training program in a high-volume center.

LEVEL OF EVIDENCE

IV, case series.

Total Ankle Arthroplasty and Ankle Arthrodesis Use: An American Board of Orthopaedic Surgery Part II Database Study

Total ankle arthroplasty (TAA) use has increased during the past 20 years, whereas ankle arthrodesis (AAD) use has remained constant. The purpose of this study was to examine trends in TAA and AAD use in American Board of Orthopedic Surgery Part II candidates while considering the influence of fellowship training status on treatment of end-stage ankle arthritis. The American Board of Orthopedic Surgery Part II database was queried to identify all candidates who performed ≥1 TAA or AAD from examination years 2009 through 2018. Candidates were categorized by examination year and by self-reported fellowship training status. Descriptive statistical methods were used to report procedure volumes. Trends in use of TAA and AAD were examined by using log-modified regression analyses. From 2009through 2018, there was no significant change in TAA or AAD use among all candidates (p = .92, p = .20). Candidates reporting a foot and ankle fellowship trended toward increased use of TAA relative to AAD compared with non-foot and ankle fellowship candidates, but this failed to reach statistical significance (p = .06). The use of arthroscopic AAD increased over time (p < .01) among all candidates. TAA and AAD use did not change over the study period. Volume of TAA and AAD performed by early-career surgeons remains low. The findings in this study should serve as an important reference for orthopedic trainees, early-career surgeons, and orthopedic educators interested in optimizing training curriculum for surgical management of end-stage ankle arthritis.

Early Outcomes and Complications Following Initiation of a Total Ankle Arthroplasty Program

Background:

Surgeons who lack experience with total ankle arthroplasty (TAA) may remain hesitant to introduce this procedure owing to previously published results of high complication rates during initial cases. The purpose of the present study was to report the development of a TAA program through intermediate outcomes and complications for an initial consecutive series of TAA patients of a single community-based foot and ankle fellowship–trained orthopedic surgeon with little TAA experience using a co-surgeon with similar training and TAA exposure.

Methods:

The initial 20 patients following third-generation TAA with a single surgeon were reviewed. Clinical outcomes were measured and radiographs were evaluated to determine postoperative implant and ankle position. Complications were also measured including intraoperative, early (<3 months), and intermediate postoperative complications.

Results:

With a minimum follow-up of 2 years and average follow-up of 51 months (range 24-70 months), the mean American Orthopaedic Ankle & Foot Society Ankle-Hindfoot score was 87.7 (59-100) and VAS was 1.0 (0-5.5). All patients were improved following TAA. Radiographic evaluation demonstrated no evidence of component malalignment or ankle joint incongruity. There were no intraoperative complications nor any wound complications. Three patients returned to the operating room for placement of medial malleolar screw placement, and 1 had asymptomatic tibial component subsidence.

Conclusions:

Orthopedic surgeons with a proper background and updated training may be able to perform TAA with good outcomes. A TAA program was developed to define minimum training criteria to perform this procedure in our community. Our complication rate is consistent with those reported in the literature for experienced TAA centers, which contrasts previous literature suggesting increased complication rates and worse outcomes when surgeons perform initial TAAs. Utilization of an orthopedic co-surgeon was felt to be instrumental in the success of the program.

Level of Evidence:

Level IV, retrospective case series.

In Silico Analysis of Bone Tension During Fixation of the Medial Malleolus Fracture After Ankle Joint Endoprosthesis

Total ankle arthroplasty (TAR) is a procedure alternative to arthrodesis which enables the biomechanical stabilization of the ankle joint. The procedure is associated with a high risk of complications, including fractures of the medial malleolus. In this study, the finite element method (FEM), based on CT examinations, was used to model the ankle fracture fixation after TAR. Three types of fracture stabilization were considered: screw, Blount staple, and both screw and Blount staple. In the in silico model, the maximum stress tension was found at prosthetic junctions with the base, cone, and talar components of the tibial prosthesis. When the fracture was stabilized with the Blount staple, tension along the cone of the tibial component was about 12% of the maximum tension. Stabilizations with the screw alone or Blount staple combined with a screw on the medial side of the cone induced tension in the immediate vicinity twice as high. In the area of the medial malleolus, the tension was alike for both types of stabilization. The tension was lowest when using the Blount staple alone. We conclude that, contrary to the hitherto clinical routine of using screws, fracture fixation using the Blount staple leads to the lowest bone tension around the fixation of the medial malleolus fracture after ankle joint endoprosthesis.

Fibula Fracture: Plate versus Nail Fixation

Backgroud

Intramedullary fixation has only uncommonly been used in the fibula although it may confer some advantages. Our goal was to investigate a single surgeon's learning curve with initial usage of an intramedullary device for fibular fixation based on surgical time and quality of reduction.

Methods

Prior to initiation of this study, an experienced ankle fracture surgeon performed fibular nail fixation in a sawbones and a cadaver setting. Between February and August 2018, all patients who suffered from a distal fibula fracture underwent fibula fixation (n = 20) using the Fibulock (Arthrex). Patients were retrospectively investigated and compared with a control of fibular plate fixation. The tourniquet time, time of anesthesia, and surgery time were recorded as well as the quality of reduction.

Results

In the 20 cases, the mean tourniquet time was 68.9 ± 23.2 minutes for nail fixation, while in the fibular plate fixation group, the mean time was 75.8 ± 23.9 minutes (p = 0.37). Two patients had slight malreductions (first and third cases): one was corrected with a lag screw outside the nail, the other was an elderly patient with significant blistering in whom an entirely percutaneous reduction was performed.

Conclusions

Intramedullary fixation for fibular fractures does not appear to have a significant learning curve for an experienced ankle fracture surgeon.

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.

Learning Curve for Open Reduction and Internal Fixation of Displaced Intra-articular Calcaneal Fracture by Extensile Lateral Approach Using the Cumulative Summation Control Chart

BACKGROUND

Open reduction and internal fixation (ORIF) of displaced intra-articular calcaneal fracture (DIACF) by extensile lateral approach is widely used but is technically challenging. In this study, the learning curve for ORIF of DIACF by extensile lateral approach was investigated.

METHODS

Between March 2014 and July 2018, 45 cases consisting of 40 patients underwent operative treatment for DIACF by the extensile lateral approach performed in all instances by a single surgeon. A moving average and cumulative summation control chart (CUSUM) were used for learning curve analyses. Operative failure was defined when at least 1 of the following parameters were unsatisfactory: reduction of Gissane angle and Böhler angle, posterior facet congruency, calcaneal width, subfibular impingement, axial alignment, or calcaneocuboid joint congruency.

RESULTS

The mean operating time was 117.4 minutes. Regarding the quality of reduction, the mean preoperative sum of the 7 parameters was 5.1 and improved to 0.6 postoperatively. The CUSUM for operative success peaked in the 20th case. The CUSUM and moving average graphics of operating time peaked at the 9th case and registered nadirs at the 34th case, with slight ascent and decent. The operating time for 20 cases in phase 1 (1-20) and for 25 cases in phase 2 (21-45) of the learning curve did not differ significantly. There was no statistical difference in the severity of fracture pattern. By comparison, in phase 2, patients showed a significantly better postoperative reduction quality.

CONCLUSION

As indicated by multidimensional statistical analyses, primary technical competence in improving the reduction quality of DIACF was achieved after the initial learning period with 20 cases. After the learning curve for ORIF of DIACF, a better reduction quality in the sum of reduction parameters was observed.

LEVEL OF EVIDENCE

Level III, comparative series.

Total ankle arthroplasty: what are the risks?: a guide to surgical consent and a review of the literature

AIMS

Total ankle arthroplasty (TAA) surgery is complex and attracts a wide variety of complications. The literature lacks consistency in reporting adverse events and complications. The aim of this article is to provide a comprehensive analysis of each of these complications from a literature review, and to compare them with rates from our Unit, to aid clinicians with the process of informed consent.

PATIENTS AND METHODS

A total of 278 consecutive total ankle arthroplasties (251 patients), performed by four surgeons over a six-year period in Wrightington Hospital (Wigan, United Kingdom) were prospectively reviewed. There were 143 men and 108 women with a mean age of 64 years (41 to 86). The data were recorded on each follow-up visit. Any complications either during initial hospital stay or subsequently reported on follow-ups were recorded, investigated, monitored, and treated as warranted. Literature search included the studies reporting the outcomes and complications of TAA implants.

RESULTS

There were wound-healing problems in nine ankles (3.2%), superficial infection in 20 ankles (7.2%), and deep infection in six ankles (2.2%). Intraoperative fractures occurred in medial malleoli in 27 ankles (9.7%) and in lateral malleoli in four ankles (1.4%). Aseptic loosening and osteolysis were seen 16 ankles (5.8%). Fracture of the polyethylene component occurred in one ankle (0.4%) and edge-loading in seven ankles (2.5%). We observed medial gutter pain in 31 ankles (11.1%). The incidence of thromboembolism occurred in two ankles (0.7%). The results were found to be comparable to the previously reported complications of total ankle arthroplasty in the literature.

CONCLUSION

Total ankle arthroplasty continues to evolve and improve the ankle function. Despite high overall complication rates with TAA surgery, most complications appear to be minor and do not affect final clinical outcome. Our results and literature review will help in the consent process and provide detailed complication rates for an informed consent. Cite this article: Bone Joint J 2018;100-B:1352-8.

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.

Identifying the learning curve for total ankle replacement using a mobile bearing prosthesis

BACKGROUND

Total ankle arthroplasty remains a technically demanding surgery highly influenced by the operator experience. However, no consensus exists regarding the ideal number of cases that need to be performed before a surgeon is considered proficient. The aim of this study was to identify the learning curve of a specific replacement system with regards to intraoperative and postoperative outcomes.

METHODS

The first 31 patients undergoing total ankle arthroplasty were examined. No additional procedures were performed at the time of the TAA. Intraoperative characteristics, postoperative complications, as well as clinical and radiologic outcomes were assessed with 24-month follow-up. Learning curves, examining the relationship between surgeon experience and patient outcomes, were determined using the Moving Average Method.

RESULTS

The operatory time, and the risk of intraoperative fractures decreased with increasing surgeon experience with the learning curve stabilizing after the 14th and 24th patient, respectively. Furthermore, there appeared to be a learning curve associated with most of the important clinical and radiological outcomes. The number of patients required to stabilize the learning curve for the VAS, ROM, and AOFAS was 11, 14 and 28, respectively. Radiographically, there appeared to be a learning curve of 22 patients required to stabilize the tibio-talar ratio. There was no learning curve associated with the SF-12 PCS and MCS as well as the α-, β-, and γ-angle.

CONCLUSION

This study demonstrates that a surgical learning curve does indeed exist when performing TAA. Most of the operative variables as well as clinical and radiological outcomes stabilize after a surgeon has performed 28 cases.

Short term results of the Mobility Total Ankle System: Clinical and radiographic outcome

BACKGROUND

Ankle arthroplasty is increasingly used to reduce pain and improve or maintain joint mobility in end-stage ankle arthritis. The aim of this study was to assess the clinical and radiographic short term results of the Mobility prosthesis.

METHODS

Complications, secondary operations, failures and the survival rate were retrospectively examined in 67 primary Mobility total ankle arthroplasties. Prosthesis alignment was measured and patient reported outcomes were assessed with the use of questionnaires.

RESULTS

There were two intraoperative and 13 postoperative complications, requiring seven reoperations. Failure occurred in three cases, with a survival of 95% after 61 months. Clinical scores improved after surgery and alignment was correct in 93% of the tibial and 93% of the talar components.

CONCLUSION

Despite few intraoperative complications and satisfactory clinical and radiological outcome, the incidence of postoperative complications, reoperations and failure indicate the importance of further development and research in the field of ankle arthroplasty.

Gutter Impingement in Total Ankle Arthroplasty

Gutter pain and impingement are recognized entities following total ankle arthroplasty (TAA). However, little concrete information is available in the existing literature regarding the etiology, potentiating factors, treatment and prevention of gutter disease. This comprehensive monograph discusses this problem in expansive detail and provides insight to surgeons who perform TAA, such that these complications can be minimized in the future.

LEVELS OF EVIDENCE

Level V: Expert opinion.

Post-Traumatic Periprosthetic Tibial and Fibular Fracture After Total Ankle Arthroplasty: A Case Report

Periprosthetic fractures after total ankle arthroplasty are uncommon, with most cases occurring intraoperatively. We describe a post-traumatic periprosthetic fracture of the distal tibia and fibula after total ankle arthroplasty that was treated with minimally invasive plate osteosynthesis. It is important for orthopedic surgeons not only to recognize the risk factors for postoperative periprosthetic total ankle arthroplasty fractures, but also to be familiar with the treatment options available to maximize function and minimize complications. The design of the tibial prosthesis and surgical techniques required to prepare the ankle joint for implantation are important areas of future research to limit the risk of periprosthetic fractures.

Posterior Talar Shifting in Mobile-Bearing Total Ankle Replacement

BACKGROUND

End-stage ankle osteoarthritis frequently involves multiplanar malalignment in both the coronal and the sagittal planes. Sagittal malalignment often includes anterior translation of the talus relative to the tibia. Restoration of the correct tibial and talar alignment is essential for the long-term survival of total ankle replacement.

METHODS

This study includes 66 consecutive patients who underwent total ankle arthroplasty with the Hintegra prosthesis from May 2011 to April 2014. There were 28 females (42.4%) and 38 males (57.6%) with a mean age of about 57 years (25-82 years). Patients were clinically and radiologically assessed preoperatively and at 2, 6, and 12 months postoperatively.

RESULTS

At 12 months postoperatively, there was a statistically significant increase in American Orthopaedic Foot & Ankle Society scores from 31.9 to 72.3. Range of motion significantly increased from 9.5 to 25.4 degrees. In addition, there was a statistically significant decrease in visual analog scale (VAS) pain score from 8.9 to 2.2. Furthermore, there was a significant increase in the Tibio-Talar ratio from 2 to 6 months postoperatively (34.6%-37.2%).

CONCLUSIONS

This study demonstrated significant improvements in clinical and radiologic outcomes after Hintegra total ankle arthroplasty. Significant movement of the talus occurs within the first 6 months postoperatively. This may be the result of rebalancing of muscle and ligament forces after surgery.

LEVEL OF EVIDENCE

Level IV, case series.

Anterior Approach Total Ankle Arthroplasty: Superficial Peroneal Nerve Branches at Risk

In ankle arthroplasty, little attention has been given to intraoperative nerve injury and its postoperative sequelae. The aim of the present anatomic study was to determine the relationship of the superficial peroneal nerve to the standard anterior approach for total ankle arthroplasty. The superficial peroneal nerve was dissected in 10 below-the-knee cadaver specimens. The medial and intermediate dorsal cutaneous branches were identified. A needle was placed at the ankle joint. The following measurements were recorded: bifurcation into the medial and intermediate dorsal cutaneous branches, reference needle to the branches of the medial and intermediate superficial peroneal nerve, and the crossing branches of the medial dorsal cutaneous nerve. Two specimens (20%) had a medial dorsal cutaneous branch cross from medially to laterally. Eight specimens (80%) had a crossing branch of the medial dorsal cutaneous branch within 5 cm of the incision. No intermediate dorsal cutaneous branches were within the incision. The results from the present cadaver study suggest that during an anterior ankle approach, aberrant branches of the superficial peroneal nerve could require transection in 20% of patients at the joint level and ≤80% of patients with distal extension >35 mm from the ankle joint. The risk of injury to branches of the superficial peroneal nerve is substantial. The risk of nerve injury can be decreased with meticulous operative technique, smaller incisions, and the avoidance of aggressive retraction.

Total ankle replacement

BACKGROUND

About 1% of adults suffer from painful osteoarthritis of the ankle. The current literature contains no information on the percentage of such patients who derive long-term relief of symptoms from conservative treatment. Advanced ankle osteoarthritis can be treated with non-joint-preserving measures, such as total ankle replacement and ankle fusion.

METHODS

This review is based on selected relevant publications, guidelines from Germany and abroad, and the authors' personal experience.

RESULTS

Before surgery is considered, conservative measures such as physiotherapy and orthopedic aids should be used to the fullest possible extent. No randomized trials have yet been published comparing total ankle replacement with ankle fusion. Total ankle replacement with newer types of prosthesis yields good to very good intermediate-term and long-term results, with mean success rates of up to 90% at 10 years (range, 68-100%). Independent risk factors for the failure of ankle replacement are age over 70 years (odds ratio [OR] 3.84), primary osteoarthritis (OR 7.19), post-traumatic osteoarthritis (OR 6.2), and type of prosthesis (e.g., single hydroxyapatite coating: OR 15.04). The average range of motion of the replaced ankle joint is 25° to 30°, with values as high as 60°.

CONCLUSION

Total ankle replacement is a good treatment option for complete, end-stage ankle arthritis. It can restore joint function and make the patient mobile with little or no pain. There are, however, many contraindications to be taken into account. There is a need for further studies of the biomechanics of arthritic and replaced ankle joints and for long-term follow-up studies of total ankle replacement.

Total Ankle Arthroplasty Following Prior Infection About the Ankle

BACKGROUND

We evaluated whether a history of prior infection about the native ankle joint, bone, or soft tissues was associated with a higher rate of infection following total ankle arthroplasty (TAA) when compared with that of primary TAA in the general population.

METHODS

This is a retrospective review of our institution's TAA registry to identify all patients who reported a prior history of ankle joint sepsis or osteomyelitis and who were subsequently treated with TAA with at least 1-year follow-up. The primary outcome measure was re-infection rate. Secondary outcome measures were patient-reported outcome scores, implant survival, and complications. Twenty-two TAAs were performed in 22 patients, consisting of 9 men and 13 women, with a mean age of 58.4 years (range = 30-80 years). Patients were followed for a mean of 29.3 months (range = 11.4-83.8 months). The length of complete symptom-free interval between the index infection to time of TAA was 8.8 years (range = 0-44 years). These patients had a mean 2.7 (range = 0-13) procedures involving the ipsilateral ankle joint prior to TAA.

RESULTS

No deep infection was observed in this series. Eleven patients were followed for more than 2 years, with postoperative visual analog scale scores decreasing from 53.1 (range = 12-90) to 20.6 (range = 0-89) of 100. Ten of the 11 ankles also had AOFAS ankle-hindfoot and SF-36 scores. Their AOFAS ankle-hindfoot score increased from 38.9 (range = 10-61) to 70.1 (range = 29-90), and SF-36 score improved from 40.6 (range = 3.3-76.4) to 67.6 (range = 36.4-85.4).

CONCLUSION

Single-stage TAA can be a viable option to treat arthritic ankle pain for those patients with resolved bone or ankle joint infection, producing improved outcomes in pain and function.

Incidence of Complications During the Surgeon Learning Curve Period for Primary Total Ankle Replacement: A Systematic Review

Surgeons performing primary total ankle replacement have achieved outcomes comparable to ankle arthrodesis. However, while many reports exist suggesting the presence of a surgeon learning curve period during initial performance of primary total ankle replacement, no published analysis of the actual incidence of complications encountered during this period exists. Therefore, we sought to provide such an analysis through systematic review. A total of 2453 primary total ankle replacements with 1085 complications (44.2%) were identified. Our results revealed conflicting data whether an acceptably low incidence of high-grade complications leading to total ankle replacement failure exists during the surgeon learning curve period.

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.

Posterior Tibial Artery Perforator-Based Fascial Flap for Skin Necrosis and Exposed Extensor Tendon After Revision Total Ankle Replacement

CASE

Delayed wound-healing of anterior ankle incisions can be problematic for patients who have undergone total ankle replacement. We describe the case of a patient in whom a posterior tibial artery perforator-based fascial flap was effectively used to cover skin necrosis and to repair the extensor retinaculum in a wound following revision total ankle replacement.

CONCLUSION

When a tendon is exposed in the ankle, a skin flap is generally required. The creation of a perforator-based fascial flap is a useful technique for covering a wound with an exposed tendon and is an alternative to a musculocutaneous flap.

Comparison of sagittal subluxation in two different three-component total ankle replacement systems

BACKGROUND

Malalignment following total ankle arthroplasty (TAA) has been reported in 4% to 45% of patients. However, all reports to date have been related to coronal deformity. This study compared sagittal malalignment between the Mobility and Hintegra total ankle systems and assessed the positional stability of the implant components over time.

METHODS

The study included 50 cases each of total ankle replacement arthroplasty with the Hintegra and Mobility total ankle systems performed between May 2008 and June 2010. The Mobility group included 24 men and 25 women, and the mean age was 60.3 years (range, 50.7-70.0 years). The Hintegra group included 25 men and 25 women, and the mean age was 59.8 years (range, 50.8-68.7 years). The 2 groups did not differ in terms of gender (P = .76) or age (P = .77). Three independent observers with different levels of training evaluated the radiographs and performed the measurements independently. Each observer evaluated the radiographs twice at a 6-week interval to determine the intraobserver reliability, and the anteroposterior offset ratio was evaluated.

RESULTS

The anteroposterior offset ratio intra- and interobserver reliabilities all showed good or excellent levels of agreement in the Hintegra total ankle system and the Mobility total ankle system. With respect to the stability of sagittal translation of the talus, the Mobility system (0.08 ± 0.07 immediately, 0.0 ± 0.07 at 6 weeks postoperatively, and 0.01 ± 0.07 at 1 year postoperatively) was better than the Hintegra system (0.20 ± 0.08 immediately, 0.18 ± 0.11 at 6 weeks postoperatively, and 0.15 ± 0.10 at 1 year postoperatively) (P < .0001).

CONCLUSIONS

The Mobility system had less sagittal malalignment of the talus than the Hintegra system. Consequently, when treating ankles in patients with osteoarthritis using the Hintegra system, one must pay careful attention to sagittal malalignment during surgery.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.