Two-Year Outcomes After Total Ankle Replacement With a Novel Fixed-Bearing Implant By a Single Surgeon Non-Inventor.

Total ankle arthroplasty continues to gain popularity amongst surgeons and patients as an alternative to arthrodesis. Historically the designs of early implants were plagued with complications and frequently abandoned. Since that time the procedure and materials have undergone significant advancements in both surgical approach as well as design and function of the available implants. In this study, 40 consecutive patients who received a semiconstrained prosthesis with a unique fixed-bearing polyethylene insert were identified. Minimum follow-up was 2 y. Demographic, social, and past medical data was retrospectively reviewed. Concomitant procedures were also recorded. Radiographic analysis included lateral ankle radiograph postoperative range of motion (ROM) with maximum dorsiflexion and maximum plantarflexion weight bearing at the most recent clinic visit. Clinical outcomes included VAS, FFI, and AOFAS scores. Lateral radiographs taken in the office at a minimum 2-y follow-up showed mean maximum dorsiflexion of 11.8 degrees and plantarflexion of 13.9 degrees. VAS, FFI, and AOFAS scores improved from 8.1, 92.9, and 44.8 to 1.4, 15.3, and 90.1 postoperatively, respectively. A total of 2.5% (n = 1) required revision surgery for poly failure, and 5.0% (n = 2) underwent local wound care in the office setting postoperatively and healed without complications. Overall survivorship was 97.5% at the minimum follow-up of 2 y. In conclusion, similar studies have reported survivorship from 90% to 100% with modern ankle implants in short to mid-term follow-up. Although this is a small sample size, our data shows a 97.5% survivorship at 2 y postoperatively with favorable patient-reported statistically significant functional outcome scores, and ankle range of motion consistent with existing literature.

Fixed-bearing versus mobile-bearing total ankle replacement survivorship. A meta-analysis.

BACKGROUND: Main objective of this research is to know if there is a different survival rate between fixed bearing (FB) and mobile bearing (MB) total ankle replacement (TAR). We hypothesized that there are no differences between the survival rates of both implants. METHODS: A systematic search was performed in PubMed, Cochrane, EMBASE and ClinicalTrials.gov databases to identify published studies from August 2018 to September 2022 including results for FB and MB TAR survivorship. Inclusion criteria included 1) primary TAR in one or both feet in which implant could be identified , 2) a minimum of 20 procedures reported, 3) reported implant survivorship or calculable and 4) a minimum of 12 months follow-up for level 1-3 studies or 60 months for level 4 studies. RESULTS: 3902 ankles in 28 studies were included. 719 were FB and 3104 MB with an overall survivorship of 94% (95% CI [0.89; 0.97]) and 89% (95% CI [0.86; 0.92]) respectively. After subgroup analysis, we did not find differences among both groups (p =  0.429 ). Meta-regression analysis showed that longer follow-up was associated with lower survival rates in MB group (p = 0.000) while no other relationships were found with other factors (age, level of evidence or conflict of interests). CONCLUSIONS: No differences in survival rates between both groups were found. Age and other studied confounders were not found to be related with implant survivorship. However, longer follow-up was found to be related with lower survival rates. Studies with longer follow-up and higher level of evidence are needed to confirm results. LEVEL OF EVIDENCE: IV, systematic review of level I to IV studies.

Early experience with a 3-D printed porous surface, fixed-bearing, total ankle arthroplasty: A minimum of 2-year follow-up.

BACKGROUND: This is a pilot study reviewing patients undergoing ankle replacement with the 3-D printed INFINITY™ with ADAPTIS™ total ankle arthroplasty (TAA) system. METHODS: A retrospective review was conducted of patients with a minimum two-year follow-up who underwent TAA with the INFINITY™ with ADAPTIS™ implant system. Outcome measures include implant survivorship, complications with subsequent reoperations, patient reported outcomes, and radiologic subsidence or radiolucency. RESULTS: Thirty patients were included with median follow-up of 26 months (range, 24-36). Implant survival rate was 90% (27/30). Two patients experienced linear radiolucency > 2 mm: one required a revision TAA secondary to tibial subsidence; the other patient was asymptomatic and nonprogressive on serial radiographs. No cystic radiolucencies > 5 mm were identified. VAS, PROMIS PF, and FADI scores improved significantly. CONCLUSION: TAA performed with the 3-D printed INFINITY™ with ADAPTIS™ implant technology led to ninety percent short term implant survivorship and improvement in patient reported outcomes with comparable results to other 4th generation arthroplasty systems as a treatment modality for end-stage ankle arthritis. LEVEL OF EVIDENCE: Level III, Retrospective cohort study, Prognostic.

Patient-specific instrumentation (PSI) in total ankle arthroplasty: a systematic review.

BACKGROUND: Patient-specific instrument (PSI) may theoretically make total ankle arthroplasty (TAA) more accurate. Several studies have reported the outcomes of PSI TAA. The aim of this study is to systematically review the literature of PSI TAA. METHODS: PubMed, Embase, Web of Science, and Cochrane Library databases were systematically reviewed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines for PSI TAA. The quality of the included studies was evaluated according to Methodological Index for Non-Randomized Studies (MINORS). RESULT: Nine articles were ultimately included in the systematic review. The implant position and function outcome of TAA was similar between PSI and SI. Prediction accuracy of implant size remained great difference. PSI can shorten the operative time and fluoroscopy time. The quality of current studies on PSI TAA is insufficient to produce high-level evidence. CONCLUSION: PSI can get similar implant position and clinical outcome in TAA compared to SI, but current evidence is not strong enough to evaluate PSI TAA.

Three-dimensional morphological analysis and clinical application of ankle joint in Chinese population based on CT reconstruction.

PURPOSE: To study the anatomical features of the ankle joint in Chinese northeast healthy adults and provide accurate data for the design of the total ankle arthroplasty (TAA) prosthesis. METHODS: Computer tomography (CT) images from 156 healthy subjects, 86 males and 70 females, were collected and reconstructed through Mimics software. The 3D morphology of the distal tibia/fibula section and the whole talar was analyzed by measuring 28 parameters including maximal tibial thickness (MTiTh), anterior-posterior inclination angle, trochlea tali width (TaW), distal tibial width (TiW) and trochlea tali arc chode length (TaAL) and calculating MTiTh/TiW, TaAL/TaW. Gender difference and accuracy of CT images were evaluated. The measurements were compared with previously reported data from Caucasian subjects and Asian subjects. Statistical analysis was conducted by independent-samples t test through SPSS software. RESULTS: (1) Twenty two out of the 28 parameters were found significantly different between males and females. Most of the parameters in males were found larger than that in females (p < 0.05). (2) The difference was found larger in comparison with the Caucasian subject groups than that with Asian subject groups. (3) All the selected 11 parameters measured by CT images were found to be smaller than those by X-ray images (p < 0.05). CONCLUSION: The morphological parameters were found different between the Caucasian and Chinese northeast populations. Precise data of the ankle joint morphology were provided for the design and clinical application of TAA in the Chinese population.

Better implant survival with modern ankle prosthetic designs: 1,226 total ankle prostheses followed for up to 20 years in the Swedish Ankle Registry.

Background and purpose - We have previously reported on the prosthetic survival of total ankle replacements (TAR) in Sweden performed between 1993 and 2010. Few other reports have been published on 5- and 10-year survival rates. Furthermore, there is a lack of long-term outcome data on modern prosthetic designs. Therefore, we compared early and current prosthetic designs after a mean 7-year follow-up.Patients and methods - On December 31, 2016, 1,230 primary TARs had been reported to the Swedish Ankle Registry. We analyzed prosthetic survival, using exchange or permanent extraction of components as endpoint for 1,226 protheses with mean follow-up of 7 years (0-24). Differences between current (Hintegra, Mobility, CCI, Rebalance, and TM Ankle) and early prosthetic designs (STAR, BP, and AES) were examined by log rank test.Results - 267/1,226 prostheses (22%) had been revised by December 31, 2016. We found an overall prosthetic survival rate at 5 years of 0.85 (95% CI 0.83-0.87), at 10 years 0.74 (CI 0.70-0.77), at 15 years 0.63 (CI 0.58-0.67), and at 20 years 0.58 (CI 0.52-0.65). For early prosthetic designs the 5- and 10-year survival rates were 0.81 (CI 0.78-0.84) and 0.69 (CI 0.64-0.73) respectively, while the corresponding rates for current designs were 0.88 (CI 0.85-0.91) and 0.84 (CI 0.79-0.88). Current prosthetic designs had better survival (log rank test p < 0.001).Interpretation - Our results point to a positive time trend of prosthetic survival in Sweden; use of current prosthetic designs was associated with better prosthetic survival. Improved designs and instrumentation, more experienced surgeons, and improved patient selection may all have contributed to the better outcome.

A Novel Technique for Creating an Articulating Cement Spacer for Ankle Prosthetic Joint Infections.

Total ankle arthroplasty has been increasing as a treatment for end-stage ankle arthritis. With this increase, the incidence of total ankle prosthetic infections will also increase. Treatment of these infections depends on the duration of symptoms and whether the infection is acute or chronic in presentation. The treatment of choice for chronic infections is a 2-stage procedure, the removal of implants and placement of a static cement spacer. We describe a technique for creating an articulating antibiotic cement spacer through an anterior approach in a patient with an infected total ankle arthroplasty. The articulating antibiotic cement spacer allows high doses of local antibiotics, decreases soft tissue contractures, and allows continued motion of the joint.

A new ligament-compatible patient-specific 3D-printed implant and instrumentation for total ankle arthroplasty: from biomechanical studies to clinical cases.

BACKGROUND: Computer navigation and patient-specific instrumentation for total ankle arthroplasty have still to demonstrate their theoretical ability to improve implant positioning and functional outcomes. The purpose of this paper is to present a new and complete total ankle arthroplasty customization process for severe posttraumatic ankle joint arthritis, consisting of patient-specific 3D-printed implant and instrumentation, starting from a ligament-compatible design. CASE PRESENTATION: The new customization process was proposed in a 57-year-old male patient and involved image analysis, joint modeling, prosthesis design, patient-specific implant and instrumentation development, relevant prototyping, manufacturing, and implantation. Images obtained from a CT scan were processed for a 3D model of the ankle, and the BOX ankle prosthesis (MatOrtho, UK) geometries were customized to best fit the model. Virtual in silico, i.e., at the computer, implantation was performed to optimize positioning of these components. Corresponding patient-specific cutting guides for bone preparation were designed. The obtained models were printed in ABS by additive manufacturing for a final check. Once the planning procedure was approved, the models were sent to final state-of-the-art additive manufacturing (the metal components using cobalt-chromium-molybdenum powders, and the guides using polyamide). The custom-made prosthesis was then implanted using the cutting guides. The design, manufacturing, and implantation procedures were completed successfully and consistently, and final dimensions and location for the implant corresponded with the preoperative plan. Immediate post-op X-rays showed good implant positioning and alignment. After 4 months, clinical scores and functional abilities were excellent. Gait analysis showed satisfactory joint moment at the ankle complex and muscle activation timing within normality. CONCLUSIONS: The complete customization process for total ankle arthroplasty provided accurate and reliable implant positioning, with satisfactory short-term clinical outcomes. However, further studies are needed to confirm the potential benefits of this complete customization process. LEVEL OF EVIDENCE: 5.

Early clinical and radiological evaluation in patients with total ankle replacement performed by lateral approach and peroneal osteotomy.

BACKGROUND: The Zimmer Trabecular Metal Total Ankle Replacement (Zimmer TM TAR) is a recent ankle arthroplasty approved for use in the United States and Europe. Many of the studies reporting the results of this implant are provided by surgeons involved at least in the initial design of the implant under study. The aim of this study is to describe the early clinical and radiological outcomes in patients who underwent this procedure performed by non-designer surgeons. METHODS: A total of thirty consecutive patients underwent total ankle replacement with a Zimmer TM TAR surgery between July 2013 to January 2016.All clinical assessments were collected pre- and post-operatively with minimum follow-up of 12 months for each patient using the American Orthopedic Foot and Ankle (AOFAS) score, the Foot Function Index (FFI) and a visual analogue scale (VAS) for pain. Radiographic outcomes included ankle orientation assessed with angle "α","ß" and "γ" according to Wood. Furthermore, the anteroposterior offset ratio was measured in weight-bearing lateral ankle radiographs at the last follow-up. RESULTS: The mean preoperative FFI-pain (FFI-P) value was 53.67, the FFI-disability (FFI-D) was 64.19. At the last follow-up visit, the FFI-P and FFI-D was 16.95 and 20.76 respectively (p<0.01 for the both scales). Preoperatively, the mean VAS for pain and AOFAS score was 7.81 and 40.95 respectively, and at the last follow-up 2.29 and 86.38 (p<0.01 for the both scales). The mean angle calculated using Wood and Deakin's method were "α"= 89.02°, "ß"= 85.11 and "γ"= 27.54 post-operatively. At the last follow-up the same values were respectively 89.43, 85.18 and 29.94. At the last follow-up, the mean offset ratio was 0.06 (range 0.003/-0.17). CONCLUSIONS: These early results show high levels of patient satisfaction, and we are encouraged to continue with lateral approach total ankle arthroplasty.

Synovial Metallosis After Ceramic Total Ankle Arthroplasty Treated With a Total Talar Prosthesis: A Case Report.

Total ankle arthroplasty is a useful surgical procedure for osteoarthritis of the ankle, but aseptic loosening of components is an issue. We report here a case of aseptic implant loosening with metallosis after total ankle arthroplasty using the TNK ankle (Kyocera, Kyoto, Japan), which occurred despite the components being ceramic. We also report favorable results from our method of treatment using a total talar prosthesis in the revision surgery. During the revision surgery, synovial metallosis was found, probably related to superficial damage to the screw affixing the tibial component to the bone. Because both the tibial and talar components were loose, all the components and the remaining talar bone were removed. A new tibial component and a custom-made alumina-ceramic total talar prosthesis was inserted. Pain relief was achieved and maintained through the latest follow-up visit at 42 months after revision surgery. Dorsiflexion of the ankle improved from 0° to 5° and plantarflexion remained unchanged from its preoperative range of 20°. The American Orthopaedic Foot & Ankle Society ankle-hindfoot score improved from 38 to 80 points. To the best of our knowledge, this is the first reported case of an alumina-ceramic total ankle prosthesis loosening caused by metallosis resulting from screw abrasion. Favorable treatment results were obtained by using a total talar prosthesis in the revision surgery.

Use of Three-Dimensional Printing Techniques in the Management of a Patient Suffering From Traumatic Loss of the Talus.

Traumatic loss of the whole talus is extremely rare, and its possible treatment options are limited. Our experience of treatment of a 30-year-old male suffering from traumatic loss of the whole talus with the insertion of an anatomical antibiotic-loaded talus cement spacer using 3-dimensional printing techniques as an interim measure was reviewed and reported. A young motorcyclist was brought to the emergency department after a road traffic accident. He sustained multiple injuries including traumatic loss of his left talus. Despite repeated surgeries of debridement and insertion of external fixator to his injured ankle, the patient had residual problem of ankle instability, ankle infection, and absence of his involved talus. With the help of computerized 3-dimensional printing techniques, an anatomical talus cement spacer was produced in the operating room and inserted into the patient's ankle 7 weeks after the initial trauma. The external fixator was kept for another 3 weeks before removal. At 14 months after the insertion of cement spacer, the patient could walk independently without any pain for 15 minutes with the help of a crutch occasionally. However, the range of motion of his left ankle was limited to 15° in the flexion-extension arc and minimal subtalar motion. The infection of the left ankle was under control.

Revision of Failed Total Ankle Replacement With a Custom 3-Dimensional Printed Talar Component With a Titanium Truss Cage: A Case Presentation.

An innovative technique is presented for salvage of a failed total ankle replacement resulting from talar subsidence with the use of a custom 3-dimensional printed articulating talar component with a titanium truss cage. This introduces a better alternative to an ankle arthrodesis with which ankle joint function and range of motion may be preserved.

Early outcomes and radiographic alignment of the Infinity total ankle replacement with a minimum of two year follow-up data.

BACKGROUND: The Infinity total ankle replacement (Wright Medical Technology, Memphis, TN) is a low profile, fluoroscopically navigated, fixed-bearing device. We hypothesised that the fluoroscopic navigation would allow more accurate alignment of the prosthesis than conventional techniques. We present our minimum two year follow up data of Infinity ankle replacements. METHODS: All total ankle replacements (TARs) performed at our institution were prospectively followed-up with EQ5-D and MOx-FQ scores as well as intra-operative radiation exposure and radiographic alignment data. Post-operative radiographs were used to measure the alignment of the prostheses. We identified 20 implants with minimum of two year follow up which were compared to a control group of 20 Zenith TAR's (Corin, Cirencester, UK). RESULTS: Intra-operative fluoroscopic navigation has allowed excellent alignment of all prostheses. Median deviations from 90° alignment to the anatomical axis of the tibia were 1.5° and 1.2° in the anterior-posterior (AP) and lateral planes respectively, compared to 2.8° and 3.1° in the Zenith group. This difference reached significance (p=<0.05) using the Mann-Whitney U test. At 2 years, MOx-FQ scores had fallen from pre-operative mean of 63.9∓17.1 to 15∓12.7. EQ-5D VAS scores had improved from 71.3∓17.3 to 81.4∓9.7 points. Radiation exposure had a mean screening time of 82∓29.4s and a decrease in exposure per patient was observed over time. No patients have undergone, or are awaiting, revision surgery. Complications include one intraoperative medial malleolar tip avulsion fracture, one medial malleolar stress fracture, and one patient who developed CRPS. CONCLUSIONS: We present evidence that this system achieves better anatomical alignment of the components when compared to techniques without fluoroscopic navigation. The implant survival and complication profile at a minimum of two years is satisfactory.

Accuracy of patient-specific instrumentation in total ankle arthroplasty: A comparative study.

BACKGROUND: Patient-specific instrumentation (PSI) for TAA is a novel technology with several potential benefits. The primary goal of this study was to compare the use of PSI with the standard referencing guide (SRG) in regards to accuracy of tibial implant positioning. Operative time, fluoroscopy time and accuracy of PSI preoperative reports were also evaluated. METHODS: A retrospective analysis of 99 patients who underwent a primary TAA with the INFINITY prosthesis (Wright Medical, Memphis, TN) was performed. Patients were divided in two groups based on the type of instrumentation used during the TAA (75 in the PSI group vs 24 in the SRG group). There was no significant difference between groups in regards to age at the time of surgery (P=0.122), sex (P=0.138), number of concomitant procedures performed during surgery (P=0.567) and etiology (P=0.841). However, preoperative deformity was significantly smaller in the PSI group (P=0.002). RESULTS: Tibial implant positioning was similar between groups. In the coronal plane, the absolute deviation of the tibial implant from the intended alignment was 1.7±1.4° for the SRG and 1.6±1.2° for PSI (P=0.710). In the sagittal plane, the absolute alignment deviation of the tibial implant was 1.8±1.4° for the SRG and 1.9±1.5° for PSI (P=0.675). Operative time (167 vs 190min, P=0.040) and fluoroscopy time (85 vs 158s, P<0.001) were significantly decreased in the PSI group. The PSI preoperative plan report correctly predicted the implant size in 73% of cases for the tibial component and in 51% of cases for the talar component. CONCLUSIONS: PSI provided similar tibial component alignment as standard instrumentation. Additionally, PSI preoperative plan reports were poor predictors of implant sizing. Therefore, the final decision should always be based on surgeon's experience in order to prevent errors in implant sizing and positioning. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

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

BACKGROUND: Total ankle arthroplasty (TAA) is an alternative to arthrodesis, but no randomized trial has examined whether a fixed bearing or mobile bearing implant provides improved gait mechanics. QUESTIONS/PURPOSES: We wished to determine if fixed- or mobile-bearing TAA results in a larger improvement in pain scores and gait mechanics from before surgery to 1 year after surgery, and to quantify differences in outcomes using statistical analysis and report the standardized effect sizes for such comparisons. METHODS: Patients with end-stage ankle arthritis who were scheduled for TAA between November 2011 and June 2013 (n = 40; 16 men, 24 women; average age, 63 years; age range, 35-81 years) were prospectively recruited for this study from a single foot and ankle orthopaedic clinic. During this period, 185 patients underwent TAA, with 144 being eligible to participate in this study. Patients were eligible to participate if they were able to meet all study inclusion criteria, which were: no previous diagnosis of rheumatoid arthritis, a contralateral TAA, bilateral ankle arthritis, previous revision TAA, an ankle fusion revision, or able to walk without the use of an assistive device, weight less than 250 pounds (114 kg), a sagittal or coronal plane deformity less than 15°, no presence of avascular necrosis of the distal tibia, no current neuropathy, age older than 35 years, no history of a talar neck fracture, or an avascular talus. Of the 144 eligible patients, 40 consented to participate in our randomized trial. These 40 patients were randomly assigned to either the fixed (n = 20) or mobile bearing implant group (n = 20). Walking speed, bilateral peak dorsiflexion angle, peak plantar flexion angle, sagittal plane ankle ROM, peak ankle inversion angle, peak plantar flexion moment, peak plantar flexion power during stance, peak weight acceptance, and propulsive vertical ground reaction force were analyzed during seven self-selected speed level walking trials for 33 participants using an eight-camera motion analysis system and four force plates. Seven patients were not included in the analysis owing to cancelled surgery (one from each group) and five were lost to followup (four with fixed bearing and one with mobile bearing implants). A series of effect-size calculations and two-sample t-tests comparing postoperative and preoperative increases in outcome variables between implant types were used to determine the differences in the magnitude of improvement between the two patient cohorts from before surgery to 1 year after surgery. The sample size in this study enabled us to detect a standardized shift of 1.01 SDs between group means with 80% power and a type I error rate of 5% for all outcome variables in the study. RESULTS: This randomized trial did not reveal any differences in outcomes between the two implant types under study at the sample size collected. In addition to these results, effect size analysis suggests that changes in outcome differ between implant types by less than 1 SD. Detection of the largest change score or observed effect (propulsive vertical ground reaction force [Fixed: 0.1 ± 0.1; 0.0-1.0; Mobile: 0.0 ± 0.1; 0.0-0.0; p = 0.0.051]) in this study would require a future trial to enroll 66 patients. However, the smallest change score or observed effect (walking speed [Fixed: 0.2 ± 0.3; 0.1-0.4; Mobile: 0.2 ± 0.3; 0.0-0.3; p = 0.742]) requires a sample size of 2336 to detect a significant difference with 80% power at the observed effect sizes. CONCLUSIONS: To our knowledge, this is the first randomized study to report the observed effect size comparing improvements in outcome measures between fixed and mobile bearing implant types. This study was statistically powered to detect large effects and descriptively analyze observed effect sizes. Based on our results there were no statistically or clinically meaningful differences between the fixed and mobile bearing implants when examining gait mechanics and pain 1 year after TAA. LEVEL OF EVIDENCE: Level II, therapeutic study.

Contact stresses, pressure and area in a fixed-bearing total ankle replacement: a finite element analysis.

BACKGROUND: Mobile-bearing ankle implants with good clinical results continued to increase the popularity of total ankle arthroplasty to address endstage ankle osteoarthritis preserving joint movement. Alternative solutions used fixed-bearing designs, which increase stability and reduce the risk of bearing dislocation, but with a theoretical increase of contact stresses leading to a higher polyethylene wear. The purpose of this study was to investigate the contact stresses, pressure and area in the polyethylene component of a new total ankle replacement with a fixed-bearing design, using 3D finite element analysis. METHODS: A three-dimensional finite element model of the Zimmer Trabecular Metal Total Ankle was developed and assembled based on computed tomography images. Three different sizes of the polyethylene insert were modeled, and a finite element analysis was conducted to investigate the contact pressure, the von Mises stresses and the contact area of the polyethylene component during the stance phase of the gait cycle. RESULTS: The peak value of pressure was found in the anterior region of the articulating surface, where it reached 19.8 MPa at 40% of the gait cycle. The average contact pressure during the stance phase was 6.9 MPa. The maximum von Mises stress of 14.1 MPa was reached at 40% of the gait cycle in the anterior section. In the central section, the maximum von Mises stress of 10.8 MPa was reached at 37% of the gait cycle, whereas in the posterior section the maximum stress of 5.4 MPa was reached at the end of the stance phase. DISCUSSION: The new fixed-bearing total ankle replacement showed a safe mechanical behavior and many clinical advantages. However, advanced models to quantitatively estimate the wear are need. CONCLUSION: To the light of the clinical advantages, we conclude that the presented prosthesis is a good alternative to the other products present in the market.

[Endoprosthesis failure in the ankle joint : Histopathological diagnostics and classification]. / Endoprothesenversagen im oberen Sprunggelenk : Histopathologische Diagnostik und Klassifikation.

INTRODUCTION: Endoprostheses of the ankle joint show higher revision rates of 3.29 revisions per 100 component years. The aims of this study were the application and modification of the consensus classification of the synovia-like interface membrane (SLIM) for periprosthetic failure of the ankle joint, the etiological clarification of periprosthetic pseudocysts and a detailed measurement of proliferative activity (Ki67) in the region of osteolysis. MATERIAL AND METHOD: Tissue samples from 159 patients were examined according to the criteria of the standardized consensus classification. Of these, 117 cases were derived from periprosthetic membranes of the ankle. The control group included 42 tissue specimens from the hip and knee joints. Particle identification and characterization were carried out using the particle algorithm. An immunohistochemical examination with Ki67 proliferation was performed in all cases of ankle pseudocysts and 19 control cases. RESULTS: The consensus classification of SLIM is transferrable to endoprosthetic failure of the ankle joint. Periprosthetic pseudocysts with the histopathological characteristics of the appropriate SLIM subtype were detectable in 39 cases of ankle joint endoprostheses (33.3%). The mean value of the Ki67 index was 14% and showed an increased proliferation rate in periprosthetic pseudocysts of the ankle (p-value 0.02037). CONCLUSION: In periprosthetic pseudocysts an above average higher detection rate of type 1 SLIM induced by abrasion (51.3%) with an increased Ki67 proliferation fraction (p-value 0.02037) was found, which can be interpreted as local destructive intraosseus synovialitis. This can be the reason for formation of pseudocystic osteolysis caused by high mechanical stress in ankle endoprostheses. A simplified diagnostic classification scoring system of dysfunctional endoprostheses of the ankle is proposed for collation of periprosthetic pseudocysts, ossifications and the Ki67 proliferation fraction.

Results at a minimum follow-up of 5 years of a ligaments-compatible total ankle replacement design.

BACKGROUND: A new design of 3-part ankle replacement was developed to achieve compatibility with the natural ligaments by allowing certain fibers to remain isometric during passive motion. METHODS: We evaluate 75 ankle prostheses implanted from July 2003 to December 2008, at a mean follow-up 6.5±1.1years (range 5-9 years). The mean age at surgery was 62±13years (range 29-82). RESULTS: The mean AOFAS scores achieved at pre-op and at last follow-up were respectively 37±5 (23-45) and 78±8 (64-98). (p<0.001). Clinical range of motion of the ankle measured by goniometer pre op was 1°±2 of dorsiflexion and 12°±4° of plantarflexion; at last follow-up range of motion increased to 6°±5° in dorsiflexion (p<0.01) and 18°±7° in plantarflexion (p<0.05). Radiographs showed no loosening and little signs of radiolucency. Two revisions necessitated component removal, neither for implant loosening. The overall survival rate was 97.3%. CONCLUSIONS: Function and Range-of-motion showed significant improvements. These results demonstrate that ligaments-compatible shaped talar and tibial components, with a fully conforming interposed meniscal bearing, can provide satisfactory survival rates and clinical outcomes in the middle term.

Geometric analysis of the talus and development of a generic talar prosthetic.

BACKGROUND: Trauma to the talus can result in fracture, avascular necrosis and structural collapse. Treatment has been limited to surgical fusion and total ankle arthroplasty. Total ankle arthroplasty may not be an appropriate treatment for avascular necrosis while surgical fusion of the joint limits mobility. Custom-made implants have recently been used to address these limitations but have lengthy delays between injury and surgery and higher associated costs. A generic talar prosthesis available in various sizes may serve as a suitable alternative. METHODS: The geometric variation between shapes of individual tali was determined using 3D geometric models of 91 tali created from CT-scan data. Comparisons were done to determine if tali are one shape. The best shape was determined for each sex, and was compared to determine if a unisex implant would be possible. A geometric template for the implant in multiple sizes was created and compared to the models. RESULTS: The average of the average deviation between tali after volume scaling was found to be less than 1mm on the main articulating surfaces. One shape group was found for the talus. The female and male tali were found to be similar and a unisex implant template was created. CONCLUSIONS: Ten generic talar implant sizes were determined to be sufficient to match the size and shape of the 91 tali examined in this study.

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.