It is known that the gait dynamics of elderly substantially differs from that of young people. However, it has not been well studied how this age-related gait dynamics affects the knee biomechanics, e.g., cartilage mechanical response. In this study, we investigated how aging affects knee biomechanics in a female population using subject-specific computational models. Two female subjects (ages of 23 and 69) with no musculoskeletal disorders were recruited. Korea National Institute for Bioethics Policy Review Board approved the study. Participants walked at a self-selected speed (SWS), 110% of SWS, and 120% of SWS on 10 m flat ground. Three-dimensional marker trajectories and ground reaction forces (Motion Analysis, USA), and lower limbs’ muscle activities were measured (EMG, Noraxon USA). Knee cartilage and menisci geometries were obtained from subjects’ magnetic resonance images (3T, GE Health Care). An EMG-assisted musculoskeletal finite element modeling workflow was used to estimate knee cartilage tissue mechanics in walking trials. Knee cartilage and menisci were modeled using a transversely isotropic poroviscoelastic material model. Walking speed in SWS, 110%, and 120% of SWS were 1.38 m/s, 1.51 m/s, and 1.65 m/s for the young, and 1.21 m/s, 1.34 m/s and 1.46 m/s for the elderly, respectively. The maximum tensile stress in the elderly tibial cartilage was ~25%, ~33%, and ~32% lower than the young at SWS, 110%, and 120% of SWS, respectively. These preliminary results suggest that the cartilage in the elderly may not have enough stimulation even at 20% increases in walking speed, which may be one reason for tissue degeneration. To enhance these findings, further study with more subjects and different genders will investigate how age-related gait dynamics affects knee biomechanics.
Persistent medial laxity increases the risk of failure for ACL reconstruction. To address this, multiple reconstruction techniques have been created. To date, no single strand reconstruction constructs have been able to restore both valgus and rotational stability. In response to this, a novel single strand Short Isometric Construct (SIC) MCL reconstruction was developed. Eight fresh-frozen cadaveric specimens were tested in three states: 1) intact 2) after sMCL and dMCL transection, and 3) after SIC MCL reconstruction. In each state, four loading conditions were applied at varying flexion angles: 90N anterior drawer, 5Nm tibial external rotation torque, 8Nm valgus torque, and combined 90N anterior drawer plus 5Nm tibial external rotation torque.Abstract
Introduction
Methods
Historic MCL reconstruction techniques focused on the superficial MCL to restore valgus stability while overlooking tibial external rotation and the deep MCL. This study assessed the ability of a contemporary medial collateral ligament (MCL) reconstruction and a deep MCL (dMCL) reconstruction to restore rotational and valgus knee stability. Six pairs fresh-frozen cadaveric knee specimens with intact soft tissue were tested in four states: 1) intact 2) after sMCL and dMCL sectioning, 3) contemporary MCL reconstruction (LaPrade et al), and 4) dMCL reconstruction. In each state, four loading conditions were applied at varying flexion angles: 8Nm valgus torque, 5Nm tibial external rotation torque, 90N anterior drawer, and combined 90N anterior drawer plus 5Nm tibial external rotation torque.Abstract
Introduction
Methods
In theory, Finite Element Analysis (FEA) is an attractive method for elucidating the mechanics of modular implant junctions, including variations in materials, designs, and modes of loading. However, the credence of any computational model can only be established through validation using experimental data. In this study we examine the validity of such a simulation validated by comparing values of interface motion predicted using FEA with values measured during experimental simulation of stair-climbing. Two finite element models (FEM) of a modular implant assembly were created for use in this study, consisting of a 36mm CoCr femoral head attached to a TiAlV rod with a 14/12 trunnion. Two head materials were modelled: CoCr alloy (118,706 10-noded tetrahedral elements), and alumina ceramic (124,710 10-noded tetrahedral elements). The quasi-static coefficients of friction (µs) of the CoCr-TiAlV and Ceramic-TiAlV interfaces were calculated from uniaxial assembly (2000N) and dis-assembly experiments performed in a mechanical testing machine (Bionix, MTS). Interface displacements during taper assembly and disassembly were measured using digital image correlation (DIC; Dantec Dynamics). The assembly process was also simulated using the computational model with the friction coefficient set to µs and solved using the Siemens Nastran NX 11.0 Solver. The frictional conditions were then varied iteratively to find the value of µ providing the closest estimate to the experimental value of head displacement during assembly. To validate the FEA model, the relative motion between the head and the trunnion was measured during dynamic loading simulating stair-climbing. Each modular junction was assembled in a drop tower apparatus and then cyclically loaded from 230–4300N at 1 Hz for a total of 2,000 cycles. The applied load was oriented at 25° to the trunnion axis in the frontal plane and 10° in the sagittal plane. The displacement of the head relative to the trunnion during cyclic loading was measured by a three-camera digital image correlation (DIC) system. The same loading conditions were simulated using the FEA model using the optimal value of µ derived from the initial head assembly trials.INTRODUCTION
MATERIALS and METHODS
In recent years, there has been an increase in hip joint replacement surgery using short bone-preserving femoral stem. However, there are very limited data on postoperative periprosthetic fractures after cementless fixation of these stem although the periprosthetic fracture is becoming a major concern following hip replacement surgery. The purpose of this study is to determine incidence of postoperative periprosthetic femoral fractures following hip arthroplasty using bone preserving short stem in a large multi-center series. We retrospectively reviewed 897 patients (1089 hips) who underwent primary total hip arthroplasty (THA) or bipolar hemiarthroplasty (BHA) during the same interval (2011–2016) in which any other cementless, short bone-preserving femoral stem was used at 7 institutions. During the study, 1008 THAs were performed and 81 BHAs were performed using 4 different short femoral prostheses. Average age was 57.4 years (range, 18 – 97 years) with male ratio of 49.7% (541/1089). Postoperative mean follow-up period was 1.9 years (range, 0.2 – 7.9 years).Introduction
Materials & Methods
Recent clinical studies have suggested that systemic metal ion levels are significantly elevated at midterm follow-up after ceramic-on-metal (COM) bearing. However, it is not clear whether there is a correlation between patient- and surgical-related factors including the lifestyle and elevated levels of serum metal ions following COM total hip arthroplsty (THA). Two hundred and one patients (234 hips) including 121 COM patients (140 hips) and 80 non-COM patients (94 hips) were enrolled in accordance with the inclusion criteria. The patients were divided into three groups based on the type of surgical bearings used. The Harris Hip Score (HHS), University of California, Los Angeles (UCLA) activity scale score, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score were measured, and radiographs were obtained for the analysis. Serum metal ion levels of cobalt and chromium were measured using a high-resolution inductively coupled plasma mass spectrometry. Patient- and surgical-related factors were analyzed to determine which group of patients is at a high risk of metal ion-related problems.Background
Material and Methods
To promote rapid bone healing, an adequate stable fixation implant with a percutaneous reduction instrument should be used for Vancouver type B1 or C fractures. The objective of this study was to describe radiographic and clinical outcomes of patients with periprosthetic fracture (PPF) around a stable femoral stem, treated with a distal femoral locking plate alone or with a cerclage cable. A total of 21 patients with PPF amenable to either a reverse distal femoral locking plate (LCP DF®) alone or with a cerclage cable, with a mean age of 75.7 years, were included. In these patients, 10 fractures were treated with a reverse LCP DF® alone and were classified as group I, and 11 additionally received a cerclage cable and were classified as group II.[Fig.1]Purpose
Materials and Methods
This meta-analysis was designed to evaluate the effects of computer navigation on blood conservation after total knee arthroplasty (TKA) by comparing postoperative blood loss and need for allogenic blood transfusion in patients undergoing computer navigation and conventional primary TKAs. Studies were included in this meta-analysis if they compared change in haemoglobin concentration before and after surgery, postoperative blood loss via drainage or calculated total blood loss, and/or allogenic blood transfusion rate following TKA using computer navigation and conventional methods. For all comparisons, odds ratios and 95 % confidence intervals (CI) were calculated for binary outcomes, while mean difference and 95 % CI were calculated for continuous outcomes.Purpose
Methods
A matched comparison was made between femoral neck-preserving short, tapered stems (n = 50) and conventional length femoral stems (n = 50) in cementless total hip arthroplasty between January 2008 and January 2012. Patients were matched for age, sex, body mass index, height, surgical approach, and surgeon. In group A, mean preoperative HHS and WOMAC scores of 55.0 and 53.0, respectively, improved to mean postoperative scores of 98.6 and 3.3, respectively, at an average follow–up of 37.2 months. In group B, mean preoperative HHS and WOMAC scores of 53.0 and 49.5, respectively, improved to mean postoperative scores 97.8 and 4.4, respectively, at an average follow–up of 35.3 months. In addition, no significant differences in mean postoperative HHS (
We prospectively analyzed 83 patients who underwent ceramic-on-ceramic THA using preassembled (n = 22) or modular acetabular components (n = 61) between June 2010 and June 2012. No radiographic evidence of progressive radiolucency, osteolytic lesions, acetabular fractures, or component migration was detected in either group. Furthermore, no patient required revision surgery for instability or ceramic breakage. Table 1 shows the mean postoperative HHS, WOMAC score, and acetabular component inclination and anteversion in groups A and B. No significant differences in mean postoperative HHS (P < 0.056), WOMAC score (P < 0.258), acetabular component inclination (P < 0.827), or anteversion (P < 0.549) were observed between the two groups according to the independent sample t-test. However, the chi-square (Fisher's exact) test showed a significant difference between the two groups with respect to the gender of the patients (P < 0.001, Table 2). These findings indicate that half of the women had smaller acetabular diameters accommodating a cup size of only 48–50-mm. Thus a preassembled ceramic liner is a very good option for women with a small acetabulum, which could permit the use of a larger femoral head (36-mm) with thin-walled acetabular components. In contrast, the component-specific complications between the two groups were quite similar. One patient (group B) had transient squeaking that disappeared after a few months. One patient (group B) had a mild limp caused by abductor muscle weakness, and one patient (group B) had a superficial wound infection that was treated with local debridement and antibiotics. Early dislocation (P < 0.488) occurred in three patients (one in group A and two in group B). Two patients (one in group A and one in group B) reported postoperative falling events at their bedside. The other in group B was a female with rheumatoid arthritis, which can lead to a much higher risk of dislocation due to soft tissue laxity around the hip joint. All of these patients were treated by closed reduction without further incident. Three patients (one in group A and two in group B) had mild iliopsoas pain (P < 0.488) that was not associated with loosening; however, the pain did not limit their activities (Table 3). In conclusion, we found no significant differences in the mean postoperative radiographic or functional outcomes or complications between the two groups, showing satisfactory performance at the 2 year follow up. Only the gender of the patient was significantly different between the two goups, demonstrating that a larger number of women had smaller acetabular diameters accommodating a cup size of only 48–50-mm. Although a preassembled cup with a 36-mm ceramic liner has proven safety in the short term, future research should focus on its long-term risks.
The purpose of this study was to identify the factors contributing to the development and progression of periacetabular osteolytic lesions and to identify which of these lesions can progress at an early stage following THA using repeated computed tomography scans. We also evaluated the accuracy of radiographs in assessing periacetabular osteolysis after THA with uncemented acetabular components and compared it with results of CT analysis. CT scans were done in ninety-seven patients (118 hips) who had undergone primary THA between 1996 and 2004 at our hospital at a minimum of two-years postoperatively, from April to August 2006. All the CT images were acquired using high resolution multi-detector row CT (MDCT). The mean age of the patients at the time of surgery was 46.2 years (range, 21–65 years). The mean follow-up at the time of obtaining CT scan was 82.1 months (range, 18–234 months). The second CT scans were obtained in sixty three hips of 49 patients (36 males and 13 females) in 2009. The mean of patient's age was 52.7 years (range, 30 to 76 years). At the time of initial CT scan, the mean duration of implantation was 76.9 months (range, 17–156 months). The volume of periacetabular osteolysis was measured using Rapidia 3D software version. Linear wear of the PE was measured in digitalized radiographs obtained within 3 months of the surgery.Introduction
Methods
A retrospective analysis of 63 primary total hip arthroplasty cases was done using repeated computed tomography scans to evaluate the pelvic osteolytic lesions in early stage. The progression rate of osteolysis of hips with small osteolytic volume less than 766.97 mm(3) in initial CT was 85.82 mm(3)/year, and that of hips with osteolysis more than 766.97 mm(3) was 456.3 mm(3)/year (P < 0.001). Younger patients less than 52 years old with good Harris Hip Scores (more than 80) frequently showed much faster progression in volume of osteolytic lesions. The rate of osteolysis was accelerated when the amount of osteolysis reached a certain threshold volume in active young patients in a cascade manner even in early stage.
To investigate treatment patterns and efficacy of postoperative strong opioids in patients who underwent total knee arthroplasty (TKA) in Korea A prospective, non-interventional study of 301 patients who underwent TKA and received strong opioids following patient controlled analgesia (PCA) was conducted by reviewing patient charts and diaries from 19 teaching hospitals. Clinical characteristics, strong opioid treatment patterns, efficacy of strong opioid on a scale of 0–10, and opioid-related adverse events (AEs) were investigated during hospitalization and at first outpatient visit. Safety analysis was conducted on 301 patients, and efficacy analysis was conducted on full analysis set (FAS) which consisted of all the patients who had at least 1 efficacy result among 301 patients.Purpose:
Methods:
The use of polymethylmethacrylate (PMMA) in orthopaedic reconstructive surgery can increase the possibility of cardiovascular dysfunction remains a debate. This study was undertaken to determine if cemented hemiarthroplasty is safe in treatment of femoral neck fracture in patients with ischemic heart disease. Between March 1999 and February 2004, we performed cemented hemiarthroplasties for displaced femoral neck fractures on 158 consecutive patients. This retrospective study consisted of 44 patients with ischemic heart disease(group 1) and 58 patients of age matched control(group 2). We compared the mortality rate, the incidence of deep vein thrombosis (DVT), pulmonary embolism, cerebrovascular disease, dislocation, deep infection, the amount of postoperative blood loss, and the grade of cementation by Barrack in radiograph between two groups. No difference was found in perioperative mortality rate, deep infection rate, the incidence of DVT or pulmonary embolism, the newly developed heart ischemic event or brain hemorrhagic lesion between the two groups. But there were more incidence of dislocation related to weakness by past brain ischemic lesion and the newly developed brain ischemia in patients of group 1 than group 2(p <
0.05). More importantly, six patients in group 1 had transient symptoms of dyspnea, signs of hypotension, and bradycardia during two days postoperatively, which is suspicious of embolic phenomenon, even though it was not confirmed. More closer and careful observations for the occurrence of dislocation related to previous brain ischemia, or newly developed brain ischemic lesion or embolic phenomenon and appropriate thromboprophylaxis are necessary in patients with ischemic heart disease after a cemented hemiarthroplasty for the treatment of femoral neck fracture.
Biocompatibility of Co-Cr alloy was significantly improved by forming rough TiO2 layer on the surface. The TiO2 layer was formed by coating the Co-Cr alloy with Ti through electron beam deposition followed by micro-arc oxidation (MAO) of the Ti. Biocompatibility of Co-Cr alloy was enhanced by coating with titanium, and it was improved further by micro-arc oxidation treatment. MAO process was dependent on the thickness of coated titanium layer and applied voltage. There were close relationships between the phase, morphology and thickness of TiO2 layer and the applied voltage. Biocompatibility of the specimens coated with Ti and MAO treated after Ti coating were evaluated by in vitro ALP activity tests.
The purpose of this study was to review the total ankle arthroplasties performed in consecutive series of 78 ankles and to determine the short-term results in cases with over 12 months follow-up. Preoperative diagnoses were post-traumatic osteoarthritis in 40 ankles (51.3%), primary osteoarthritis in 32 ankles (41.0%), and systemic arthritis in six ankles (7.7%). HINTEGRA® (Newdeal SA, Lyon, France) total ankle system was used in all cases Fifty-five total ankle arthroplasties including four revision cases, followed up for over 12 months (range, 13~49 months) were included in this study. Ankles were divided into three groups according to the coronal plane deformity in preoperative standing ankle AP radiograph; Varus (≥10°; 20 ankles (39.2%)), neutral (<
10° varus or valgus; 25 ankles (49%)), and valgus (≥10° valgus; 6 ankles (11.8%)). Various additional surgeries were performed simultaneously with the arthroplasty to correct the deformities; deltoid ligament release (25 cases), posterior tibialis tendon lengthening (2 cases), peroneus longus tendon transfer to brevis (5 cases), lateral ankle reconstruction with modified Broström procedure (4 cases), lateral closed-wedge calcaneal osteotomy (3 cases), percutaneous heel cord lengthening (19 cases), and gastrocnemius recession (1 case). In one patient with severe valgus deformity, staged total ankle arthroplasty was conducted after primary triple arthrodesis. Preoperative and postoperative visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) score, range of motion (ROM), as well as patient’s satisfaction and willingness to receive the operation again were evaluated The results were compared among the three groups. Serial radiographs were reviewed for any radiological changes. AOFAS score has improved from 54.3 ± 11.4 pre-operatively to 79.2 ± 11.4 at last follow-up. VAS has decreased from 6.8 ± 1.6 to 3.2 ± 1.6. Mean improvement in ROM was 15.6 ± 16.2 degrees. Forty-eight cases (873%) were satisfied with excellent or good results and 49 cases (89.1 %) were willing to receive the operation again. No significant differences in the postoperative VAS (p=0.14), AOFAS score (p=0.79), and ROM (p=0.06) were found among the three groups. Hetero-topic ossifications were observed in 12 cases (23.5%) and periosteal reactions proximal to medial malleolus occurred in four cases (7.8%). Perioperative complications include one intraoperative medial malleolus fracture which was successfully managed with two cannulated-screws, and one medial malleolar stress fracture at six weeks after surgery which has healed spontaneously. One case with osteolysis around tibial screws was managed with bone graft. One case with deep fungal infection was converted to arthrodesis after infection control. Four ankles had to be revised including three cases of polyethylene bearing change due to dislocation, and one case of tibial component and bearing change due to loosening. The patient with revised tibial component was converted to arthrodesis due to recurred loosening. The Kaplan-Meier cumulative survival rate was 90.9% at 12 months and 87.8% at 49 months postoperatively. The short term clinical results of HINTEGRA ankles showed favorable results. No significant differences were observed among different groups of coronal plane deformities when adequate additional surgeries were performed simultaneously. Long term follow-up study is required.
Modified posterior approach preserving short external rotators would be able to contribute greatly to prevent dislocation after total hip arthroplasty. We modified the posterior approach to the hip by preserving the external rotator muscles in order to enhance joint stability after total hip arthroplasty in patients with osteonecrosis of the femoral head. The aim of the this study was to determine the influence of external rotator preserving posterior approach in primary total hip replacement on early dislocation and clinical outcome. Three hundred sixty-four primary total hip replacements were divided into two groups based on how the external rotators were treated at surgery. External rotator preservation (Group 1, 165 hips) group was compared with reattachment (Group 2, 199 hips) group by evaluating the clinical and radiographic outcome at one year postoperative. Anteversion was significantly less in Group 1 as compared to Group 2 (P <
0.001). There was no significant difference in inclination between the groups (P >
0.05 in all comparisons). No dislocations were found in 165 hips with external rotator preservation whereas dislocations was noted in 11 (3.9%) in Groups 2, respectively. Group 1 had the higher mean Harris hip score (97.2±2.9 points) as compared with Group 2(94.9±3.4). The results of this study showed that external rotators could play an important role in preserving joint stability after total hip arthroplasty in patients with osteonecrosis of the femoral head. It can be implied that this modified posterior approach would be able to contribute greatly to prevention of dislocation, and improve clinical outcome after total hip arthroplasty.
We developed a modified posterior approach that preserved the short external rotator muscles to prevent dislocation after THA or BHA. The present study aimed to evaluate the effectiveness of short external rotator preserving posterior(ERP) approach for bipolar hemiarthroplasty in treatment of femoral neck fractures in patients with neurologic disorders. Between March 2004 and February 2006, we performed 187 cementless bipolar hemiarthroplasties for displaced femoral neck fractures on 36 patients with neurologic disorders, who were operated on by ERP approach (Group 1) and 151 patients without neurologic deficits, who were operated on by conventional posterolateral approach (Group 2). We compared operation time, the amount of postoperative blood loss, the early postoperative complication rates, the dislocation rate within 1 year, and duration of hospital stay between two groups. The amount of postoperative blood loss was significantly decreased in group 1(p <
0.01). There were no significant differences in mean operation time and early postoperative complication rate including wound problem, deep vein thrombosis or infection and duration of hospital stay. There was no dislocation after operation in group 1, but seven patient (4.6%) had dislocation in group 2. Nine patients (25.0%) died within postoperative 1 year in group 1 and twenty six patients (17.2%) died in group 2. Cementless bipolar hemiarthroplasty through ERP approach provides a favorable outcome for treatment of displaced femoral neck fracture in patients with neurologic disorders who is considered as high risk of dislocation. Also, it decreases the postoperative blood loss and the needs of postoperative abduction brace.
