Associations Among Changes in Body Composition, Activity, Muscle Recovery, and Obesity Following Total Knee Arthroplasty: A Retrospective Study.

Purpose: Total knee arthroplasty (TKA) is expected to improve knee pain and enable patients to regain the ability to walk, but the associations between preoperative and postoperative changes in body composition, muscle strength, and activity remain unclear. In this study, we investigated the association between changes in body composition before and after TKA surgery, the recovery process of muscle strength, and changes in activity, as well as the effects of obesity on TKA.

Methods: A total of 124 patients with unilateral knee osteoarthritis (OA) who underwent TKA were retrospectively evaluated.

Unveiling the dynamics of intraoperative contamination in total hip arthroplasty: the discrepancy between particulate and microbial contamination in surgical site infection risk.

Background: Surgical site infection (SSI) is a major problem following total hip arthroplasty (THA). This study investigated the impact of a standard intraoperative routine where the surgical team wears full-body exhaust suits (space suits) within a laminar airflow (LAF)-ventilated operating room (OR) on environmental contamination. Our primary objective was to identify potential modifiable intraoperative factors that could be better controlled to minimize SSI risk.

Investigation of the effectiveness of intermittent electromagnetic field stimulation for early internal cartilaginous ossification in prechondrocytic ATDC5 cells.

Pulsed electromagnetic field (PEMF) stimulation has been widely applied clinically to promote bone healing; however, its detailed mechanism of action, particularly in endochondral ossification, remains elusive, and long-term stimulation is required for its satisfactory effect. The aim of this study was to investigate the involvement of the mammalian target of rapamycin (mTOR) pathway in chondrocyte differentiation and proliferation using a mouse prechondroblast cell line (ATDC5), and establish an efficient PEMF stimulation strategy for endochondral ossification. The changes in cell differentiation (gene expression levels of aggrecan, type II collagen, and type X collagen) and proliferation (cellular uptake of bromodeoxyuridine [BrdU]) in ATDC5 cells in the presence or absence of rapamycin, an mTOR inhibitor, was measured.

Early Postoperative Change in Hip Rotation Angle and Factors Contributing to It for Patients Undergoing Total Hip Arthroplasty.

Objective: A possible impairment in hip proprioception after total hip arthroplasty (THA) has been an issue of concern. The aims of this study were to investigate the extent of early postoperative change in standing hip rotation angle (HRAng) in patients with osteoarthritis (OA) undergoing THA and to consider a possible mechanism behind this.

Materials And Methods: A total of 82 hips (82 patients; 63 women and 19 men) undergoing unilateral primary THA with total capsulectomy were included.

A novel diagnostic examination for dropped head syndrome (DHS) (Prone position cervical extension test; DHS test).

Background: Dropped head syndrome (DHS) is followed by severe cervical extension muscle weakness that results in chin-on chest deformity. However, maintaining a neutral cervical position can be temporarily possible, and the diagnosis of DHS might sometimes be difficult. The purpose of the present study is to examine a novel clinical test (DHS test) as the diagnostic utility for objective evaluation that focuses on cervical extension condition in the prone position.

Bacterial Contamination in Total Joint Replacement: Should We Change into a New Set of Clean Scrub Suits Whenever Entering the Operating Room?

Background: The aims of this study are as follows: (1) to investigate the level and probability of bacterial contamination on scrub suits over time for medical personnel working inside and/or outside the operating room (OR) area; (2) to discuss the protective role of cover gowns against bacterial contamination; and (3) to consider the necessity of changing into clean suits whenever entering the OR in terms of preventing periprosthetic joint infection (PJI) in total joint replacement (TJR).

Methods: The bacterial colony count was examined on the chest area of the scrub suits worn during various daily clinical practices. The genus/species of the contaminants were identified by matrix-assisted laser deposition ionization-time of flight mass spectrometry (MALDI-TOF MS).

Do polyethylene wear particles affect the development of pseudotumor in total hip arthroplasty? A minimum 15-year follow-up.

Background: Adverse local tissue reactions have been problematic as an implant-related complication in total hip arthroplasty (THA). Despite the absence of significant metal wear and corrosion, granulomatous pseudotumor has been reported to be caused by polyethylene wear. We performed a long-term follow-up study investigating the relationship between polyethylene wear and pseudotumor formation in THA.

Does intraoperative mechanical prophylaxis prevent venous thromboembolism in total knee arthroplasty? - effectiveness of passive-assisted ankle motion in surgical/non-surgical side.

Background: Gradual compression stocking (GCS) and intermittent pneumatic compression device (IPCD) are used for intraoperative mechanical prophylaxis against venous thromboembolism (VTE) during total knee arthroplasty (TKA). In this study, we applied a passive-assisted ankle motion in combination with GCS and IPCD during TKA and evaluated its effectiveness in preventing postoperative VTE.

Methods: We included 77 patients who underwent primary unilateral TKA.

Adverse Tissue Reactions and Metal Ion Behavior After Small-Head Metasul Hip Arthroplasty: A Long-Term Follow-Up Study.

Objective: To investigate the long-term survivorship, incidence of adverse reactions to metal debris (ARMD), and metal ion behavior in patients who underwent small-head Metasul metal-on-metal (MoM) total hip arthroplasty (THA).

Methods: Between February 1998 and September 2003, a retrospective study was performed on 43 consecutive patients (43 hips) who underwent unilateral cementless Metasul MoM THAs at our institution. Of them, 35 patients (nine males and 26 females) who were available for follow-up more than 15 years after THA were enrolled in this study and underwent metal artifact reduction sequence magnetic resonance imaging (MARS-MRI) to identify ARMD.

IL-17A-Mediated Immune-Inflammatory Periarticular Mass and Osteolysis From Impingement in Ceramic-On-Ceramic Total Hip Arthroplasty.

We present a rare case of symptomatic adverse local tissue reaction in a 54-year-old female patient who had undergone total hip arthroplasty with ceramic-on-ceramic bearing. Inflammatory periarticular mass and osteolysis developed in the absence of cobalt chrome alloy interfaces and a modular neck component. On the pathologic images, there was no clear evidence of gross metal staining of tissues, metal corrosion, and ceramic or metal wear particles.

Risk factors for preoperative nasal carriage of methicillin-resistant bacteria in total hip and knee arthroplasty patients.

Background: The present study aimed to identify risk factors for preoperative nasal carriage of resistant bacteria - MRSA methicillin-resistant Staphylococcus (S.) aureus, MRSE (methicillin-resistant Staphylococcus epidermidis), and MRCNS (methicillin-resistant coagulase negative staphylococci) in total hip and knee arthroplasty (THA and TKA) patients.

Methods: Nasal cultures were obtained from 538 patients before THA (262 primary and 26 revision) and TKA (241 primary and 9 revision).

Prostaglandin E induces dual-specificity phosphatase-1, thereby attenuating inflammatory genes expression in human osteoarthritic synovial fibroblasts.

Characteristic features of osteoarthritis (OA) are joint pain and cartilage degeneration. The degeneration is caused by excess induction of matrix metalloproteinases (MMPs) and the pain is caused by nerve growth factor (NGF)-dependent nerve invasion into synovial tissue in addition to nociceptive pain by prostaglandin (PG)E The objective of this study was to clarify the suppressive mechanism of PGE on the regulation of MMPs and NGF by focusing on mitogen-activated protein kinases (MAPKs) and their endogenous phosphatase, dual-specificity phosphatase (DUSP)-1 in human synovial fibroblasts. PGE strongly increased DUSP-1 and suppressed IL-1β-induced MAPKs phosphorylation.

Impact of surgical clothing and footwear on operating room contamination during standstill and intraoperative stepping motion.

Background: In view of preventing surgical site infection (SSI) in the orthopedic operating room (OR), evidence concerning types of footwear and clothing is limited. This study aimed to investigate how different footwear and clothing affect the cleanliness of the OR environment.

Methods: The airborne dust concentration in a bioclean room (NASA class 100) was measured around an operator by using a handheld particle counter under the following conditions: (I) wearing a sterilized full-type space suit with OR dedicated clean sandals; (II) wearing a sterilized full-type space suit with non-dedicated (outside) shoes or severely contaminated outside shoes with surgical glove powder (2 µm mean particle size); and (III) wearing an unsterilized medical scrub uniform with OR dedicated sandals.

Do Polyethylene Supra-Macroparticles Lead to Pseudotumor Formation in Metal-on-Polyethylene Total Hip Arthroplasty?

We describe 2 cases of pseudotumors induced by an unusual size of polyethylene wear particle after metal-on-polyethylene total hip arthroplasty (MoP THA). The supra-macroparticles of size >100 μm originated from a polyethylene liner with relatively small cup anteversion, potentially leading to excessive loading and increased wear of the anterior edge of the polyethylene liner. Histopathology showed a foreign-body reaction to the polyethylene particles without an adverse reaction to metal debris and with no severe signs of corrosion at the head-neck junction, which have been noted in past reports of pseudotumors in MoP THA.

Does artificial aging correctly predict the long-term in-vivo degradation behavior in zirconia hip prostheses?

Background: Accelerated hydrothermal aging has long been one of the most widely accepted quality control tests for simulating low-temperature degradation (LTD) in zirconia-containing implants used in total hip arthroplasty (THA). However, it is still unclear how much consistency there is between the experimental prediction from the internationally-standardized tests and the actual measurements from surgically-removed implants after a long period of implantation. This question is fundamentally related to a lack of understanding of mechanical/tribological contribution to the in-vivo LTD kinetics.

Influence of liner offset and locking mechanism on fatigue durability in highly cross-linked polyethylene total hip prostheses.

Highly cross-linked, ultrahigh molecular weight polyethylene (HXLPE) acetabular liners are inherently associated to a risk of fatigue failure due to femoral neck impingement. Different thicknesses and designs employed with HXLPE liners greatly affect mechanical loading scenario. The purpose of this study was to clarify the influence of liner offset (lateralization) and locking mechanism (presence/absence of anti-rotation tabs in the external surface) on fatigue durability in annealed and vitamin E-blended HXLPE liners with a current commercial design.

Intermittent pulsed electromagnetic field stimulation activates the mTOR pathway and stimulates the proliferation of osteoblast-like cells.

Pulsed electromagnetic fields (PEMFs) have been shown to be a noninvasive physical stimulant for bone fracture healing. However, PEMF stimulation requires a relatively long period of time and its mechanism of action has not yet been fully clarified. Recently, the mammalian target of rapamycin (mTOR) pathway has been shown to be involved in bone formation.

Clinical course of asymptomatic deep vein thrombosis after total knee arthroplasty in Japanese patients.

Purpose: The purpose of the present study was to follow up Japanese patients with deep vein thrombosis (DVT) after total knee arthroplasty (TKA) and also to examine factors associated with residual thrombus within the sixth postoperative month.

Methods: DVT evaluation was performed by noninvasive venous ultrasonography. We retrospectively reviewed 88 Japanese patients (88 knees) receiving primary unilateral TKA, who had no preoperative DVT.

Do rim cracks and backside grinding affect the aging kinetics of alumina-matrix composite acetabular liners?

The acetabular liner malalignment and rim impingement have been problematic issues in ceramic-on-ceramic (CoC) total hip arthroplasty (THA). Commercial ceramic liners made of alumina-matrix composite (AMC) have polished articulation and rim, and roughly ground backside with a button-like apical projection (post) to resist tilting. In this study, we hypothesized that rim cracks and backside grind critically affect the aging kinetics of tetragonal zirconia dispersed in AMC structure.

Effect of stem alignment on long-term outcomes of total hip arthroplasty with cementless Bi-Metric femoral components.

We investigated the effects of varus-valgus alignment on the long-term outcomes after cementless total hip arthroplasty (THA) using a porous coated version of Bi-Metric femoral stems. The Kaplan-Meier survival analysis was performed in 71 hips. The survival rate with femoral revision for aseptic loosening as the end point was 100% at 17 years.

The aging micromechanisms of alumina matrix composite (AMC) used in total hip arthroplasty.

Background: The aim of the present study is to simulate and better understand the long-term interplay between alumina matrix composite (AMC) femoral head and aqueous environment. In particular, we focused on clarifying the role of alumina grains on zirconia phase stability and mechanical equilibrium in AMC head during aging processes in a clinically-relevant time frame.

Methods: The tested AMC head consists of an alumina matrix (82 vol.

Does modern space suit reduce intraoperative contamination in total joint replacement? An experimental study.

Background: The purpose of this study was to evaluate a potential risk of intraoperative contamination associated with clothing systems and surgeon's motion in total joint replacement.

Methods: The airborne particle concentrations at different locations around a single operating surgeon wearing standard surgical gown (SG) or modern "space suit" (SS) were compared. The particles in the size of ≥0.

Post-deformation shape-recovery behavior of vitamin E-diffused, radiation crosslinked polyethylene acetabular components.

The in-vivo progression of creep and wear in ultra-high molecular weight polyethylene (UHMWPE) acetabular liners has been clinically evaluated by measuring radiographic penetration of femoral heads. In such clinical assessments, however, viscoelastic strain relaxation has been rarely considered after a removal of hip joint loading, potentially leading to an underestimation of the penetrated thickness. The objective of this study was to investigate shape-recovery behavior of pre-compressed, radiation crosslinked and antioxidant vitamin E-diffused UHMWPE acetabular liners, and also to characterize the effects of varying their internal diameter (ID) and wall thickness (WT).

Improved Resistance to Neck-Liner Impingement in Second-Generation Highly Crosslinked Polyethylene-The Role of Vitamin E and Crosslinks.

Background: Radiation crosslinking of ultrahigh molecular weight polyethylene (UHMWPE) results in the reduced tensile strength and fracture toughness as an expense of dramatic increase in the wear resistance. Clinical rim fracture has been reported due to neck-liner impingement on a first-generation highly crosslinked UHMWPE acetabular component. The objective of this study was to investigate whether a second-generation, vitamin E-blended highly crosslinked UHMWPE possesses the improved impingement resistance.

Size and thickness effect on creep behavior in conventional and vitamin E-diffused highly crosslinked polyethylene for total hip arthroplasty.

Since the early 2000s, the use of large femoral heads is becoming increasingly popular in total hip arthroplasty (THA), which provides an improved range of motion and joint stability. Large femoral heads commonly necessitate to be coupled with thinner acetabular liners than the conventionally used because of the limited sizes of outer shells (especially for patients with small pelvic size). However, the influence of the liner thinning on the mechanical performance is still not clearly understood.