Precision of Bone Mineral Density Measurements Around Total Ankle Replacement Using Dual Energy X-ray Absorptiometry.

INTRODUCTION: Joint prosthesis survival is associated with the quality of surrounding bone. Dual-energy X-ray absorptiometry (DXA) is capable to evaluate areal bone mineral density (BMD) around different prosthetic implants, but no studies evaluated periprosthetic bone around total ankle replacement (TAR). Our aim is to determine the precision of the DXA periprosthetic BMD around TAR. METHODOLOGY: Short-term precision was evaluated on 15 consecutive patients. Each ankle was scanned 3 times both in the posteroanterior (PA) and lateral views with a dedicated patient positioning protocol. Up to four squared regions of interest (ROIs) were placed in the periprosthetic bone around tibial and talar implants, with an additional ROI to include the calcaneal body in the lateral scan. Coefficient of variation (CV%) and least significant change were calculated according to the International Society for Clinical Densitometry. RESULTS: The lateral projection showed lower mean CV values compared to the PA projection, with an average precision error of 2.21% (lateral scan) compared to 3.34% (PA scans). Overall, the lowest precision error was found at both "global" ROIs (CV = 1.25% on PA and CV = 1.3% on lateral). The highest CV value on PA was found at the medial aspect of talar side (ROI 3; CV = 4.89%), while on the lateral scan the highest CV value was found on the posterior aspect of talar side (ROI 2; CV = 2.99%). CONCLUSIONS: We found very good reproducibility BMD values of periprosthetic bone around TAR, that were comparable or even better compared to other studies that evaluated periprosthetic BMD around different prosthetic implants. DXA can be used to precisely monitor bone density around ankle prostheses, despite further long-term longitudinal studies are required to assess the clinical utility of such measurements.

Optimizing Outpatient Total Ankle Replacement from Clinic to Pain Management.

Outpatient total ankle arthroplasty is a potential significant source of cost savings. The ability to institute an effective outpatient total ankle program depends on appropriate patient selection, surgeon experience with total ankle replacement, addressing preoperative patient expectations, the involvement of an experienced multidisciplinary care team including experienced anesthesiologists, nurse navigators, recovery room nursing staff and physical therapists, and most importantly, such a program requires complete institutional logistical support.

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.

Total ankle arthroplasty versus ankle arthrodesis-a comparison of outcomes over the last decade.

BACKGROUND: The surgical treatment of end-stage tibiotalar arthritis continues to be a controversial topic. Advances in surgical technique and implant design have lead to improved outcomes after both ankle arthrodesis (AA) and total ankle arthroplasty (TAA), yet a clear consensus regarding the most ideal form of treatment is lacking. In this study, the outcomes and complications following AA and TAA are compared in order to improve our understanding and decision-making for care and treatment of symptomatic tibiotalar arthritis. METHODS: Studies reporting on outcomes and complications following TAA or AA were obtained for review from the PubMed database between January 2006 and July 2016. Results from studies reporting on a minimum of 200 total ankle arthroplasties or a minimum of 80 ankle arthrodesis procedures were reviewed and pooled for analysis. All studies directly comparing outcomes and complications between TAA and AA were also included for review. Only studies including modern third-generation TAA implants approved for use in the USA (HINTEGRA, STAR, Salto, INBONE) were included. RESULTS: A total of six studies reporting on outcomes following TAA and five reporting on outcomes following AA met inclusion criteria and were included for pooled data analysis. The adjusted overall complication rate was higher for AA (26.9%) compared to TAA (19.7%), with similar findings in the non-revision reoperation rate (12.9% for AA compared to 9.5% for TAA). The adjusted revision reoperation rate for TAA (7.9%) was higher than AA (5.4%). Analysis of results from ten studies directly comparing TAA to AA suggests a more symmetric gait and less impairment on uneven surfaces after TAA. CONCLUSIONS: Pooled data analysis demonstrated a higher overall complication rate after AA, but a higher reoperation rate for revision after TAA. Based on the existing literature, the decision to proceed with TAA or AA for end-stage ankle arthritis should be made on an individual patient basis.

[Treatment of Osteochondral Lesions in the Ankle: A Guideline from the Group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology (DGOU)]. / Behandlung osteochondraler Läsionen des Sprunggelenks: Empfehlungen der Arbeitsgemeinschaft Klinische Geweberegeneration der DGOU.

Background: Osteochondral lesions (OCL) of the ankle are a common cause of ankle pain. Although the precise pathophysiology has not been fully elucidated, it can be assumed that a variety of factors are responsible, mainly including traumatic events such as ankle sprains. Advances in arthroscopy and imaging techniques, in particular magnetic resonance imaging (MRI), have improved the possibilities for the diagnosis of OCLs of the ankle. Moreover, these technologies aim at developing new classification systems and modern treatment strategies. Material and Methods: This article is a review of the literature. Recommendations of the group "Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology (DGOU) for the treatment of OCLs of the ankle are presented. The review gives a concise overview on the results of clinical studies and discusses advantages and disadvantages of different treatment strategies. Results: Non-operative treatment shows good results for selected indications in children and adolescents, especially in early stages of osteochondritis dissecans (OCD). However, surgical treatment is usually indicated in OCLs in adolescents and adults, depending on the size and location of the lesion. Various arthroscopic and open procedures are frequently employed, including reattachment of the fragment, local debridement of the lesion with fragment removal and curettage of the lesion, bone marrow-stimulation by microfracture or microdrilling (antegrade or retrograde), and autologous matrix-induced chondrogenesis (AMIC®) - with or without reconstruction of a subchondral bone defect or cyst by autologous cancellous bone grafting. Isolated subchondral cysts with an intact cartilage surface can be treated by retrograde drilling and possibly additional retrograde bone grafting. For larger defects or as salvage procedure, osteochondral cylinder transplantation (OATS® or Mosaicplasty®) or matrix-induced autologous chondrocyte transplantation (MACT) are recommended. Transplantation of so-called (osteochondral) mega grafts, such as autologous bone grafts or allografts, are used for very large osteochondral defects that cannot be reconstructed otherwise. Implantation of the so-called "small metal implants" - such as HemiCAP Talus® - is reserved for selected cases after failed primary reconstruction. Corrective osteotomies are indicated in accompanying axial malalignments. Conclusions: There are several different treatment strategies for OCLs, but clinical studies are rare and evidence is limited. Therefore, interventional studies, e.g. randomised controlled trials (RCTs), but also observational studies, e.g. based on data of the Cartilage Registry of the German Society of Orthopaedics and Traumatology (www.knorpelregister-dgou.de), are needed and are recommended by the authors.

Intraoperative positioning of the hindfoot with the hindfoot alignment guide: a pilot study.

BACKGROUND: In a previous study, intraoperative positioning of the hindfoot by visual means resulted in the wrong varus/valgus position by 8 degrees and a relatively large standard deviation of 8 degrees. Thus, new intraoperative means are needed to improve the precision of hindfoot surgery. We therefore sought a hindfoot alignment guide that would be as simple as the alignment guides used in total knee arthroplasty. METHODS: A novel hindfoot alignment guide (HA guide) has been developed that projects the mechanical axis from the tibia down to the heel. The HA guide enables the positioning of the hindfoot in the desired varus/valgus position and in plantigrade position in the lateral plane. The HA guide was used intraoperatively from May through November 2011 in 11 complex patients with simultaneous correction of the supramalleolar, tibiotalar, and inframalleolar alignment. Pre- and postoperative Saltzman views were taken and the position was measured. RESULTS: The HA guide significantly improved the intraoperative positioning compared with visual means: The accuracy with the HA guide was 4.5 ± 5.1 degrees (mean ± standard deviation) and without the HA guide 9.4 ± 5.5 degrees (P < .05). In 7 of 11 patients, the preoperative plan was changed because of the HA guide (2 avoided osteotomies, 5 additional osteotomies). CONCLUSIONS: The HA guide helped to position the hindfoot intraoperatively with greater precision than visual means. The HA guide was especially useful for multilevel corrections in which the need for and the amount of a simultaneous osteotomy had to be evaluated intraoperatively. LEVEL OF EVIDENCE: Level IV, case series.