Buechel-Pappas Total Ankle Replacement: Use of Highly Cross-Linked Polyethylene Meniscal Bearings over a 13 - 15 Year Interval

Background: The Buechel-Pappas (BP) meniscal bearing total ankle replace-ment was initially developed as a “shallow-sulcus” talar component device using cobalt-chromium-molybdenum alloy, in 1978, and later, modified to a “deep-sulcus” talar component device using titanium nitride (TiN) ceramic and porous coating in 1989. Wear related osteolytic cysts were noted in the tibia and talus surrounding these devices that compromised long term fixation and stability when using standard ultra-high molecular weight polyethylene (UHMWPe) as a bearing material. This study explores the use of highly cross-linked UHMWPe (HXLPe) to minimize osteolysis by replacing standard UHMWPe with this more wear-resistant material. Methods: There were 12 primary and 8 revision total ankle replacements followed for 13 to 15 years. HXLPe was used in all meniscal bearings, either as primary or revision implants. All stable metallic tibial and talar components were retained in revision cases. Osteolytic cysts greater than 10 mm in diameter were bone grafted with homologous morselized banked bone through cortical windows in the tibia or talus. No adjuvant screw fixation was used to stabilize any metallic implant. Results: No HXLPe bearings failed in this study, and no re-revisions were performed. No primary total ankle replacement failed in this study, and there were no substantial osteolytic cysts (>2 mm) observed in primary total ankle replacements on plain X-rays. All bone grafted osteolytic cysts in revision ankle replacements remained stable, even though partial resorption of the grafted material was identified in most of the ankles. No loosening of porous coated and TiN coated tibial and talar components were seen;the longest surviving metal components in the revision group was 24 years with the revised bearing at 15 years. Conclusions: HXLPe has greatly improved wear resistance in meniscal-bearing BP total ankle replacements in both primary and revision arthroplasties. Osteolytic cysts can be successfully bone grafted during bearing exchange revisions. Primary and revision, cementless BP metallic total ankle components have remained well-fixed to bone in the long term (greater than 20 years), without the use of adjuvant screw fixation.

The effects of total ankle replacement on ankle joint mechanics during walking

Background:End-stage ankle arthritis impairs joint function and patients' mobility.Total ankle replacement is a surgical procedure to treat severe ankle arthritis.Salto Talaris Anatomic Ankle^(TM)(STAA) was designed to mimic the normal ankle anatomy and flexion/extension of the ankle movement.The purpose of this study was to examine the effect of an STAA ankle replacement on ankle joint function and mechanics during gait.Methods:Five patients with end-stage unilateral ankle arthritis were recruited.Patients performed level walking in a laboratory setting on 2occasions,prior to and 3 months after the STAA ankle surgeries.American Orthopedic Foot and Ankle Society(AOFAS) hindfoot score was obtained.A 12-camera motion capture system was used to perform walking analysis.Gait temporo-spatial parameters and ankle joint mechanics were evaluated.Paired Student's t tests and non-parametric Wilcoxon matched tests were performed to examine the differences in biomechanical variables between the pre-and post-surgery walking conditions.Results:Compared to the pre-surgical condition,at 3 months of post-STAA surgery,patients experienced greater improvement in AOFAS hindfoot score(p = 0.0001);the STAA ankle demonstrated a 31% increase in ankle joint excursion(p = 0.045),a 22% increase in ankle plantarflexor moment(p = 0.075),a 60% increase in ankle power absorption(p = 0.023),and a 68% increase in ankle power production(p = 0.039).Patients also demonstrated a 26% increase in walking speed(p = 0.005),a 20% increase in stride length(p = 0.013),a 15% decrease in double support time(p = 0.043),and a 5% decrease in total stance time(p = 0.055).Conclusion:Three months after surgeries,the STAA patients experienced improvements in ankle function and gait parameters.The STAA ankle demonstrated improved ankle mechanics during daily activities such as walking.

Total ankle replacement with INBONE-II prosthesis: A short-to-medium-term follow-up study in China

Background:Total ankle replacement(TAR)is a viable option for the treatment of end-stage ankle arthritis.In China,the INBONE-II implant is the only total ankle prosthesis approved since 2016.The purpose of this study is to report a large sample of findings for the TAR with INBONE-II prosthesis.Methods:A total of 64 patients with end-stage ankle arthritis,who underwent primary TAR using INBONE-II by the same surgeon from 2016 to 2019,at a single institution were included in this retrospective,single-center study.Clinical data,radiographic findings,survival rate,and complications were recorded and assessed pre-operatively and at the most recent follow-up.Results:A total of 64 patients were available for follow-up at least 2 years after surgery;the mean follow-up duration for clinical outcomes was 37.9 months(24–59 months),and for radiographic findings was 22.8 months(12–59 months).There were significant improvements(P<0.01)in the American Orthopedic Foot and Ankle Society hindfoot scale,the visual analog scale for pain,and the Short Form-36.There were statistically significant differences between pre-operative and post-operative comparisons of the talar tilt angle(TT)and the tibial lateral surface angle(TLS)in the radiographic findings(TT from 4.7±4.3°to 1.3±1.3°,TLS from 80.4±7.7°to 87.4±2.3°,P<0.01).There was no statistically significant difference in improvement of the tibial anterior surface angle(P=0.14).Ten complications(all low grade)were recorded according to the Glazebrook classification system.The survivorship of the prosthesis was 100%(64/64).Conclusion:Patients who underwent TAR with INBONE-II prosthesis demonstrated significant improvements in all measures of pain and function as well as in radiographic findings.High survival and a low incidence of complications were observed in this study.

Implications of obesity in patients with foot and ankle pathology

Obesity is a growing problem defined as a body mass index of greater than 30 kg/m2.It is predicted that by 2030,48.9%of adults will be classified as obese which expands surgical risk factors to a broad population while increasing healthcare costs at the same time in different socioeconomic groups.This specific population has been widely studied in multiple surgical fields and published studies have shown the implications in each of these fields.The impact of obesity on orthopedic surgical outcomes has been previously reported in several total hip and knee arthroscopy studies,with evidence indicating that obesity is strongly associated with an increased risk of post operative complications together with higher revision rates.In line with increasing interest on the impact of obesity in orthopedics,there has been a similar output of publications in the foot and ankle literature.This review article evaluates several foot and ankle pathologies,their risk factors associated with obesity and subsequent management.It provides an updated,comprehensive analysis of the effects of obesity on foot and ankle surgical outcomes,with the ultimate aim of educating both surgeons and allied health professionals about the risks,benefits,and modifiable factors of operating on obese patients.

Patient-specific instrumentation in total ankle arthroplasty

The recent increase in the adoption of total ankle arthroplasty(TAA)reflects the improvements in implant designs and surgical techniques,including the use of preoperative navigation system and patient-specific instrumentation(PSI),such as custom-made cutting guides.Cutting guides are customized with respect to each patient's anatomy based on preoperative ankle computed tomography scans,and they drive the saw intra-operatively to improve the accuracy of bone resection and implant positioning.Despite some promising results,the main queries in the literature are whether PSI improves the reliability of achieving neutral ankle alignment and more accurate implant sizing,whether it is actually superior over standard techniques,and whether it is cost effective.Moreover,the advantages of PSI in clinical outcomes are still theoretical because the current literature does not allow to confirm its superiority.The purpose of this review article is therefore to assess the current literature on PSI in TAA with regard to current implants with PSI,templating and preoperative planning strategies,alignment and sizing,clinical outcomes,cost analysis,and comparison with standard techniques.