The optimal management of an infrapopliteal deep venous thrombosis (IDVT) following total knee arthroplasty (TKA) remains unknown. The risk of DVT propagation and symptom progression must be balanced against potential haemorrhagic complications associated with administration of anticoagulation therapy. The current study reports on a cohort of patients diagnosed with IDVT following TKA who were treated with aspirin, followed closely for development of symptoms, and scanned with ultrasound to determine resolution of IDVT. Among a cohort of 5,078 patients undergoing TKA, 532 patients (695 TKAs, 12.6%) developed an IDVT between 1 January 2014 to 31 December 2019 at a single institution, as diagnosed using Doppler ultrasound at the first postoperative visit. Of the entire cohort of 532 patients with IDVT, 91.4% (486/532) were treated with aspirin (325 mg twice daily) and followed closely. Repeat lower limb ultrasound was performed four weeks later to evaluate the status of IDVT.Aims
Methods
A variety of porous coatings and substrates have been used to obtain fixation at the bone-implant interface. Clinical studies of porous tantalum, have shown radiographically well-fixed implants with limited cases of loosening. However, there has been limited retrieval analysis of porous tantalum hip implants. The purpose of this study was to investigate factors affecting bone ingrowth into porous tantalum hip implants. 126 porous tantalum acetabular shells and 7 femoral stems, were collected under an IRB-approved multicenter retrieval program. Acetabular shells that were grossly loose, cemented or complex revisions were excluded. Shells with visible bone on the surface were chosen. 20 acetabular shells (10 primary) and all femoral stems were dehydrated, embedded, sectioned, polished and bSEM imaged (Figure-1). Main shell revision reasons were infection (n=10,50%), femoral loosening (n=3,15%) and instability (n=3,15%). Analyzed implants were implanted for 2.3±1.7 years (shells) and 0.3±0.3 years (stems). Eight slices per shell and 5–7 slices per stem were analyzed. The analysis included bone area/pore area (BA/PA), BA/PA zonal depth analysis, extent of ingrowth and maximum depth of bone ingrowth. BA/PA zone depths were: Zone-1 (0–500um), Zone-2 (500–1000um) and Zone-3 (1000um-full depth). Nonparametric statistical tests investigated differences in bone measurements by location within an implant and implant type (Friedman's Variance and Kruskal-Wallis). Post-hoc Dunn tests were completed for subsequent pairwise comparisons. Spearman's rank correlation identified correlations between bone measurements and patient related variables (implantation time, age, height, weight, UCLA Activity Score). Statistical analyses were performed using PASW Statistics package.Introduction
Methods
Recent implant design trends have renewed concerns regarding metal wear debris release from modular connections in THA. Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Comparatively little is known about head-neck taper corrosion with ceramic femoral heads or about how taper angle clearance influences taper corrosion. This study addressed the following research questions: 1) Could ceramic heads mitigate electrochemical processes of taper corrosion compared to CoCr heads? 2) Which factors influence stem taper corrosion with ceramic heads? 3) What is the influence of taper angle clearance on taper corrosion in THA? 100 femoral head-stem pairs were analyzed for evidence of fretting and corrosion. A matched cohort design was employed in which 50 ceramic head-stem pairs were matched with 50 CoCr head-stem pairs based on implantation time, lateral offset, stem design and flexural rigidity. Fretting corrosion was assessed using a semi-quantitative scoring scale where a score of 1 was given for little to no damage and a score of 4 was given for severe fretting corrosion. The head and trunnion taper angles were measured using a roundness machine (Talyrond 585, Taylor Hobson, UK). Taper angle clearance is defined as the difference between the head and trunnion taper angles.Introduction
Methods
The release of metal debris and ions has raised concerns in joint arthroplasty. In THA metal debris and ions can be generated by wear of metal-on-metal bearing surfaces and corrosion at modular taper interfaces, currently understood to be mechanically assisted crevice corrosion (MACC) [1]. More recently, inflammatory-cell induced corrosion (ICIC) has been identified as a possible source of metal debris and/or ions [2]. Although MACC has been shown to occur at modular junctions in TKA, little is known about the prevalence of other sources. The purpose of this study was to determine the sources of metallic debris and ion release in long-term implanted (in vivo > 15y) TKA femoral components. Specific attention was paid to instances of ICIC as well as damage at the implant-bone interface. 1873 retrieved TKA components were collected from 2002–2013 as part of a multi-center, IRB-approved retrieval program. Of these, 52 CoCr femoral condyles were identified as long term TKA (Average: 17.9±2.8y). These components were predominantly revised for loosening, PE wear and instability. 40/52 of the components were primary surgeries. Components were examined using optical microscopy to confirm the presence of 5 damage mechanisms (polyethylene failure, MACC corrosion of modular tapers, corrosion damage between cement and backside, third-body wear, and ICIC). Third-body wear was evaluated using a semi-quantitative scoring method based on the percentage of damaged area. A score of 1 had minimal damage and a score of 4 corresponded to severe damage. Polyethylene components were scored using the Hood method and CoCr components were scored similarly to quantify metal wear. The total area damaged by ICIC was quantified using photogrammetry. Images were taken using a digital SLR with a calibrated ruler in the same focal plane. Using known pixel dimensions, the ICIC damaged area was calculated.Introduction
Methods
Degradation of modular head-neck tapers was raised as a concern in the 1990s (Gilbert 1993). The incidence of fretting and corrosion among modern, metal-on-polyethylene and ceramic-on-polyethylene THA systems with 36+ mm femoral heads remains poorly understood. Additionally, it is unknown whether metal debris from modular tapers could increase wear rates of highly crosslinked PE (HXLPE) liners. The purpose of this study was to characterize the severity of fretting and corrosion at head-neck modular interfaces in retrieved conventional and HXLPE THA systems and its effect on penetration rates. 386 CoCr alloy heads from 5 manufacturers were analyzed along with 166 stems (38 with ceramic femoral heads). Metal and ceramic components were cleaned and examined at the head taper and stem taper by two investigators. Scores ranging from 1 (mild) to 4 (severe) were assigned in accordance with the semi-quantitative method adapted from a previously published technique. Linear penetration of liners was measured using a calibrated digital micrometer (accuracy: 0.001 mm). Devices implanted less than 1 year were excluded from this analysis because in the short-term, creep dominates penetration of the head into the liner.Introduction:
Patients & Methods:
Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Less is known about head-neck taper corrosion with ceramic femoral heads. We asked (1) whether ceramic heads resulted in less taper corrosion than CoCr heads; (2) what device and patient factors influence taper fretting corrosion; and (3) whether the mechanism of taper fretting corrosion in ceramic heads differs from that in CoCr heads.Background:
Questions/purposes:
Sequentially annealed highly crosslinked polyethylenes (HXLPEs) were introduced in total knee replacement (TKR) starting in 2005 to reduce wear and particle-induced osteolysis. Few studies have reported on the clinical performance of HXLPE knees. In this study, we hypothesized that due to the reduced free radicals, sequentially annealed HXLPE would have lower oxidation levels than gamma inert-sterilized controls. 145 tibial components were retrieved at consecutive revision surgeries at 7 different surgical centers. 74 components were identified as sequentially annealed HXLPE (X3, Stryker) while the remainder (n = 71) were conventional gamma inert sterilized polyethylene. The sterilization method was confirmed by tracing the lot numbers by the manufacturer. The conventional inserts were implanted for 1.7 years (Range: 0.0–9.3 years), while the X3 components were implanted 1.1 years (Range: 0.0–4.5 years). Surface damage was assessed using the Hood method. Oxidation analysis was performed in accordance with ASTM 2102 following submersion in boiling heptane for 6 hours to remove absorbed lipids. 30 of the conventional and 29 of the HXLPE inserts were available for oxidation analysis.Introduction
Methods
Wear debris generation in metal-on-metal (MOM) total hip arthroplasty (THA) has emerged as a compelling issue. In the UK, clinically significant fretting corrosion was reported at head-taper junctions of MOM hip prostheses from a single manufacturer (Langton 2011). This study characterizes the prevalence of fretting and corrosion at various modular interfaces in retrieved MOM THA systems used in the United States. 106 MOM bearing systems were collected between 2003 and 2012 in an NIH-supported, multi-institutional retrieval program. From this collection, 88 modular MOM THA devices were identified, yielding 76 heads and 31 stems (22 modular necks) of 7 different bearing designs (5 manufacturers) for analysis. 10 modular CoCr acetabular liners and 5 corresponding acetabular shells were also examined. Mean age at implantation was 58 years (range, 30–85 years) and implantation time averaged 2.2 ± 1.8 years (range, 0–11.0 years). The predominant revision reason was loosening (n=52). Explants were cleaned and scored at the head taper, stem taper, proximal and distal neck tapers (for modular necks), liner, and shell interfaces in accordance with the semi-quantitative method of Goldberg et al. (2002).Introduction
Methods and Materials
The purpose of this multicenter study was to assess the oxidative stability, mechanical behavior, wear and reasons for revision of 2nd generation sequentially annealed HXLPE, X3, and compare it to 1st generation XLPE, Crossfire. We hypothesized that X3 would exhibit similar wear rates but lower oxidation than Crossfire. 182 hip liners were consecutively retrieved during revision surgeries at 7 surgical centers and continuously analyzed over the past 12 years in a prospective, multicenter study. 90 were highly crosslinked and annealed (Crossfire; Implanted 4.2±3.4 years, max: 11 years), and 92 were highly crosslinked and annealed in 3 sequential steps (X3; Implanted 1.2±1.5 years; max: 5 years). Oxidation was characterized in accordance with ASTM 2102 using transmission FTIR performed on thin sections (∼200μm) from the superior/inferior axis. Mechanical behavior was assessed via the small punch test (ASTM 2183).Introduction
Methods
