After an injury, the biological reattachment of tendon to bone is a challenge because healing takes place between a soft (tendon) and a hard (bone) tissue. Even after healing, the transition zone in the enthesis is not completely regenerated, making it susceptible to re-injury. In this study, we aimed to regenerate Achilles tendon entheses (ATEs) in wounded rats using a combination of kartogenin (KGN) and platelet-rich plasma (PRP). Wounds created in rat ATEs were given three different treatments: kartogenin platelet-rich plasma (KGN-PRP); PRP; or saline (control), followed by histological and immunochemical analyses, and mechanical testing of the rat ATEs after three months of healing.Objectives
Methods
Self tapping bone screw has been widely used in the fixation of Arthroplasty implants and bone graft. But the unwanted screw or driver breakage can be a direct result of excessive driving torque due to the thread cutting resistance. Previous studies showed that bone drill bit cutting rake angle was a critical factor and was inversely related to the bone cutting efficiency.1, 2, 3, 4 (Figure 1) However to date there was no data for how the rake angle could influence the performance of self tapping bone screw. The purpose of this study was to investigate the torque generated by the self tapping cortical screw in simulated bone insertion as a function of the screw tip cutting flute rake angle. Two 5 mm thick BM5166 polyurethane block were stacked together and drilled through with 2.5mm diameter holes. Five 30mm long 3.5 mm diameter Ti6AL4V alloy self tapping cortical screws with 0°rake angle cutting flutes (Figure 2) were inserted in the holes and driven by the spanner attached to the test machine (Z5.0TN/TC-A-10) with a displacement control of 3 revolutions/min and 30N constant axial loading. The screws were driven into the stacked polyurethane block for 8mm depth. The maximum driving torque was recorded. Procedure was repeated for five same screws but with 7° rake angle cutting flutes. (Figure 2) The driving torqueses were compared. Student t test was performed with confidence level of 95% was assumed.Introduction
Methods
The purpose of this study was to investigate how rim poly locking scallop cutting depth could affect the rigidity of acetabular cup. (11) generic FEA models including (5) 50mm OD Ti6Al4VELI hemispherical acetabular shells with thicknesses of 3.0, 3.5, 4.0, 4.5 and 5.0mm, and (6) 4mm thick hemispherical shells with standard rim poly indexing scallops varied in cutting depths from inner diameter of the cup in 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5mm. All cups were analyzed in ANSYS® Workbench™ FEA software with a loading condition of 2000N applied to the cup rim per V15 ISO/TC 150/SC 4 N. Verification was carried out by the physical test of a same generic Ti6Al4VELI 50mmOD and 5mm thick solid hemispherical shell under 2000N rim directed load. The cup deformation was compared with FEA results. The maximum deformation of FEA scalloped cups were compared with that of solid hemispherical cups with different shell thickness.Objective
Materials and Methods
Mechanical properties of irradiated Ultra High Molecular Weight Polyethylene (UHMWPE) after aging have been well documented. However there was no sufficient data for the dimensional change due to irradiation and aging. This change may have adverse effects to the implant modular locking mechanism. The purpose of this study was to characterize the dimensional change of UHMWPE after irradiation and aging. Total (30) ø15mm × 50mm virgin GUR 1050 UHMWPE rods were cleaned, dried, inspected, vacuum packaged and stored in 20°C environment for 2 days. Among them, (20) samples were measured along the 50mm length at 20°C +/-2°C before and after two conditions: 1, (10) were submerged in 40°C DI water for 2 hours and dried in 40°C to simulate the cleaning process and 2, (10) were soaked in 37°C saline for 14 days to simulate initial in-vivo environment. Remaining (10) samples were measured in the same way after irradiation of 30KGy dosage and then measured again after soaking in 37°C saline for 14 days to simulate the actual radiation sterilization and in-vivo soaking conditions. Same samples were measured once more after accelerated aging per ASTM-1980-07 for 80 days to simulate the 3 year in vivo life. The differences in measurements between virgin and end conditions were documented as the percentage dimensional change. After the measurements, in the groups of DI water, saline soaking and radiation + aging, (3) samples were randomly selected for DSC measurements. The results were compared with dimensional measurements. Statistical analysis was performed by the student t test to compare virgin condition and the conditions after each treatment. 95% significance level was assumed.Introduction
Materials and Method
The purpose of this study was to compare the proximal femoral morphology between normal Chinese and Caucasian populations by 3D analysis derived from CT data. 141 anonymous Chinese femoral CT scans (71 male and 70 female) with mean age of 60.1years (range 20–93) and 508 anonymous Caucasian left femoral CT scans (with mean age of 64.8years (range 20–93). The CT scans were segmented and converted to virtual bones using custom CT analytical software. (SOMA™ V.4.0) Femoral Head Offset (FHO) and Femoral Head Position (FHP) were measured from head center to proximal canal central axis and to calcar or 20mm above Lesser Trochanter (LT) respectively. The Femoral neck Anteversion (FA) and Caput-Collum-Diaphyseal (CCD) angles were also measured. The Medial Lateral Widths(MLWn) of femoral canal were measured at 0, -10, LT, -30, -40, -60, -70 and -100mm levels from calcar. Anterior Posterior Widths (APWn) were measured at 0, -60 and -100mm levels. The Flare Index (FI) was derived from the ratio of widths at 0 and -60mmor FI=W0/W−60. All measurements were performed in the same settings for both populations. The comparison was analyzed by Student T test. P<0.05 was considered significant.Objective
Materials and Methods
Soft tissue tension and intra-articular pressure distribution plays a crucial role in postoperative function and survivorship of TKA prosthesis. Although posterior stabilized (PS) and cruciate retaining (CR) knees have both been successful in relieving pain and restore function, it is reported that the joint gaps were significantly distinct between the two designs during flexion. The aim of this study is to find out what is the difference in intra-articular pressure distribution between PS and CR knees. We prospectively included 45 consecutive patients (50 knees) scheduled for total knee arthroplasty between August, 2013 and April, 2014 in our hospital. 23 patients (25 osteoarthritic knees) received a Genesis II CR TKA (Smith & Nephew, Memphis, USA), and the other 22 patients (25 osteoarthritic knees) received Genesis II PS TKA (Smith & Nephew, Memphis, USA). During operation, after the bone osteotomy and soft tissue balance were completed, we measured and compared the intra-articular pressure distribution at 0°, 30°, 45°, 60°, 90°, and 120° flexion with a previously validated “Wireless Force Measurement System (WFMS)”. Joint gaps were measured at extension and 90° flexion. The soft tissue was not considered balanced until the medial and lateral joint gap difference ≤ 2mm at extension and 90° flexion. There are no significant differences in age, gender, BMI, varus angle and flexion deformity, and preoperative range of motion between the two groups. The medial-lateral pressure distribution and total pressure were compared at different angles between CR and PS knees.Background
Methods
By retrospective analysis of clinical data, to find new risk factors for postoperative dislocation after total hip replacement and the dose-effect relationship when multiple factors work simultaneously. A nested case-control study was used to collect the dislocated hips from 5513 primary hip replacement case from 2000 to 2012. Apart from the patients with given cause of dislocation, 39 dislocated hips from 38 cases were compared with 78 hip from 78 cases free from dislocation postoperatively, which matched by the admission time. The factors that may affect the prosthetic unstable was found by the univariate analysis, and then they were performed multivariate logistic regression analysis and evaluation of a dose-effect factors.Objective
Methods
Implant-related infection (IRI) is closely related to the local immunity of peri-implant tissues. The generation of reactive oxygen species (ROS) in activated macrophages plays a prominent role in the innate immune response. In previous studies, we indicated that implant wear particles promote endotoxin tolerance by decreasing the release of proinflammatory cytokines. However, it is unclear whether ROS are involved in the damage of the local immunity of peri-implant tissues. In the present study, we assessed the mechanism of local immunosuppression using titanium (Ti) particles and/or lipopolysaccharide (LPS) to stimulate RAW 264.7 cells. The results indicate that the Ti particles induced the generation of a moderate amount of ROS through nicotinamide adenine dinucleotide phosphate oxidase-1 (NOX-1), but not through catalase. Pre-exposure to Ti particles inhibited ROS generation and extracellular regulated protein kinase (ERK) activation in LPS-stimulated macrophages. These findings indicate that chronic stimulation by Ti particles may lead to a state of oxidative stress and persistent inflammation, which may result in the attenuation of the immune response of macrophages to bacterial components such as LPS. Eventually, immunosuppression develops in peri-implant tissues, which may be a risk factor for IRI.
The development of T-smart tomosynthesis has greatly improved the imaging quality of THA by reducing the peri-implant artifacts. In order to find out whether these improvements could lead to diagnostic advantages on stability of cementless THA arthroplasty components, we conducted a diagnostic research by comparing T-smart tomosynthesis, X-ray, and computed tomography. We retrospectively included 48 patients who undergone THA revisions in our center between Aug, 2013 and Mar, 2014. For patients with hybrid fixation as their primary prosthesis, the femoral or acetabular components with cement fixation were excluded. There were 41 cementless femoral stems and 35 cementless acetabular cups remained for evaluation. All patients took anterior-posterior and lateral view x-ray examination, anterior-posterior T-smart tomosynthesis scan, and computed tomography before revision surgery. As the gold standard, intraoperative pull-out tests and twisting tests were done for every patient to examine the stability of all implants. 7 orthopedic surgeons evaluated the preoperative images independently, who were divided into the senior group (3 doctors with 6∼13 years’ clinical experience) and the junior group (4 doctors with 2∼4 years’ clinical experience). The x-rays were evaluated first, followed by computed tomography 4 weeks later, and after another 4 weeks’ interval the T-smart tomosynthesis were assessed. All doctors used the same criteria for diagnosis. Diagnostic accuracy for each imaging examination was calculated by comparing with the results of intraoperative tests. The diagnostic accuracy, kappa values between 3 imaging techniques were calculated, and chi-square tests were conducted to examine the difference between the senior and junior groups for each technique.Background
Methods
Periacetabular spherical osteotomy for the treatment of dysplastic hip is effective but technically demanding. To help surgeons perform this difficult procedure reliably and safely, a computer assisted navigation technique has been developed and evaluated. Computed tomographic scans of 5 cadaveric pelvises were obtained and three-dimensional models were generated. The osteotomy was planned preoperatively. The pelvises were registered using an optimized algorithm. Periacetabular spherical osteotomy was performed at one side of each pelvis with navigation and at another side without navigation. The deviation of the real osteotomized surface from the planned surface was measured.Objective:
Methods:
The origin of a valgus deformity affects the algorithmic and individualized approach used in total knee arthroplasty in valgus knees. We developed a new physical examination technique, the swing test, to evaluate whether valgus malalignment is present when the knee flexes. We performed the swing test on 44 valgus knees in 44 consecutive patients, and we conducted traditional malalignment analysis on each patient's long-film radiographs and computed tomography images to evaluate origin of valgus deformity. We did a diagnostic test to compare the results of the swing test with those of traditional malalignment analysis.Background:
Methods:
The Q angle is an index of the vector of combined pull of the quadriceps and the patellar tendon. However, the Q angle is traditionally measured with the knee extended and static. The indexation of the Q angle measured using the traditional method therefore is questionable. We asked if the Q angle would change when the knee flexed; if it did change, how it changed; and if it changed with different patterns in females and males.Background
Questions/purposes
Posterior lumbar interbody fusion (PLIF) is indicated
for many patients with pain and/or instability of the lumbar spine.
We performed 36 PLIF procedures using the patient’s lumbar spinous
process and laminae, which were inserted as a bone graft between
two vertebral bodies without using a cage. The mean lumbar lordosis
and mean disc height to vertebral body ratio were restored and preserved
after surgery. There were no serious complications. These results suggest that this procedure is safe and effective.
Prosthetic reconstruction of high-riding hips is technically demanding. Insufficient bony coverage and osteopenic bone stock frequently necessitate transacetabular screw fixation to augment primary stability of the metal shell. We sought to determine the validity of the previously reported quadrant system, and if needed, to define a specialized safe zone for augmentation of screw fixation to avoid vascular injuries in acetabular cup reconstruction for high-riding hips. Volumetric data from computed tomography enhancement scanning and CT angiography of eighteen hips (twelve patients) were obtained and input into a three-dimensional image-processing software. Bony and vascular structures were reconstructed three-dimensionally; we virtually reconstructed a cup in the original acetabulum and dynamically simulated transacetabular screw fixation. We mapped the hemispheric cup into several areas and, for each, measured the distance between the virtual screw and the blood vessel. We found that the rotating centers of the cups shifted more anterior-inferiorly in high-riding hips than those in ordinary cases, and thus the safe zone shifted as well. Screw fixation guided by the quadrant system frequently injured the obturator blood vessels in high-riding hips. We then defined a specialized safe zone for transacetabular screw fixation for high-riding hips. We conclude that the quadrant system can be misleading and of less value in guiding screw insertion to augment metal shells for high-riding hips. A new safe zone specific to high-riding hips should be used to guide transacetabular screw fixation in these cases.
We developed a device for the treatment of Ficat and Arlet stage II and III osteonecrosis of the femoral head. This device, which we named the “super-elastic cage,” was designed to provide mechanical support for the necrotic weight-bearing area of the femoral head to prevent its collapse. The cage was used in combination with surgical removal of necrotic bone, insertion of vascularized pedical bone graft, or impacted autologous cancellous bone graft. A total of 93 hips in 62 patients at Ficat stage II to III were included in a 8-year study. Implantations were performed by 2 different approaches: Smith-Peterson approach and minimal invasive approach by the lateral side of great trochanter. The follow-up period was between 72 and 107 months. Of the femoral heads in this study, 82.7% survived. The superelastic cage implantation technique may offer an alternative treatment to the early and middle stages of osteonecrosis of the femoral head.
The patho-anatomy of a valgus knee could be divide into two categories as bony hypolasia and/or deficiency and soft tissue imbalance. The soft tissue in the lateral side of the knee (Including illio-tial band, lateral collateral ligament, poplitious tendon, posterior-lateral ligament, and hamstrings etc) is contracted with or without medial soft tissue attenuation. There are many reasons explain why dealing with a valgus knee is much more difficult than dealing with a varus knee. The most important three factors are:
There is much less room or space to release a LCL, The MCL could be attenuated, A fixed valgus deformity is always associated with bone deficiency or hypoplasia. However, it is arbitrary, and in many times, it is wrong to take it for granted that a valgus knee is always associated with a tight LCL. In this article, the author mainly introduce the rationale and clinical application of a LCL tension based classification and treatment algorithm of a valgus knee. The details of how to judge if the LCL is tight, loose or normally tensioned; Is the valgus knee purely or associated with an extra-articular deformity will also be discussed.
Femoral deformity Type F1 Valgus in Extension only F1a Intra-articular deformity, LCL is loose when the knee extends, while LCL maintains normal tension when the knee flexes. F1b Extra-articular deformity which is close to knee joint(supra-condylar deformity), LCL remains normal length and tension through all the range of motion. Type F2 Valgus in both extension and flexion Intra-articular deformity, LCL is tight through all the range of motion, hypoplasia or bone deficiency in both distal and posterior lateral femoral condyle. Tibial deformity Type T1 Intra-articular deformity, lateral tibial plateau deficiency Type T2 Extra-articular deformity, tibial metaphyseal orshaft deformity. Treatment algorithm of a valgus knee Type F1a This type valgus knee is the easiest to deal with. The LCL length is well maintained, and LCL is loose when knee extends. What is tight and restrains the deformity as a fixed valgus one is: ITB and posterior-lateral capsule instead of LCL and poplitous tendon. The deformity is corrected simply by releasing ITB &
posterior-lateral capsule and bony graft or using a metal block to augment the deficient or hypoplastic lateral distal femoral condyle. At the same time, the loose LCL is properly tensioned by bone graft of metal augmentation. Since both ITB &
posterior capsule are secondary stabilizers, the LCL and poplitous tendon is properly tensioned, the knee is pretty stable. Type F1b This type of valgus deformity actually comes from juxta supera-condylar area, the deformity is very close to the joint, or in other words, close to the collateral ligament frame, this type deformity is also regard as a type of valgus knee. According to severity of the deformity, patient’s age, and surgeon’s preference, the following methods are commonly used.
Since a F1b valgus knee is actually a normal knee combined with a supera-condylar deformity, it is understandable to correct deformity by an supera-condylar osteotomy. The osteotomy can be done in one stage or two stage style. Theoretically, a supera-condylar osteotomy is done in the most deformed region, and is done within cancellous bone, bone union can be predictably expected. But if a total knee and osteotomy is performed in one stage, the operator could encounter the following difficulties:
Conventional instruments can not guarantee correct bone cut because a supera-condylar deformity deviates intramedullary guiding rod; the canal in distal femoral metaphyseal part is quite expended, it is difficult to achieve solid fixation either by a stem extension or retrograde intramedullary nailing. Total knee replacement, supera-condylar osteotomy and intramedullary could severely damage blood supply to osteotomy line leading to nonunion. The author prefer a two stage TKA and osteotomy for a F1b valgus knee. In one stage TKA and osteotomy, the author will use frontal epicondyle axis instead of intra-medullary rod to guide distal femoral cut. TypeF2 This type knee is consistently valgus no matter the knee extends of flexes, indicating both distal distal and posterior part of lateral femoral condyle is deficient of dysplastic and LCL is contracted. Lateral soft tissue, including LCL and some times popolitous tendon, is inevitable in managing type F2 valgus knee. If soft tissue releasing alone can’t balance medial and lateral part of the knee, a bidirectional sliding osteotomy can be done to shift proximal insertion of LCL both distally and posteriorly, releasing the LCL. Type T deformity Type T deformity is sparse, Type T1 is typically seen in a rheumatoid arthritis, and Type T2 is usually iatrogenic(over corrected high tibia osteotomy) or after malunion of a tibia metapyseal or proximal shaft fracture. It is possible try to augament the lateral tibial plateau deficiency and release the lateral soft tissue for a Type T1 valgus knee. But for a Type T2 knee, a correctional osteotomy concomitant to a total knee is usually needed.
Dislocation after THA is the most common complication in modern THA, The reported failure rate of reoperation for recurrent instability is higher than any other indication for revision surgery. Treatment of dislocation after THA Non-operative treatment The first episode of dislocation after THA is usually treated by close reduction with or without brace treatment. There is no agreement about the role and effectiveness of bracing. Generally, bracing is indicated in the following circumstances:
First dislocation Early laxity No component malposition Patients with poor general condition The main management issues are about managing recurrent instability. Treatment choice is often complex and management begins by identifying the cause of instability. Causes to consider:
Component issue Impingement Soft tissue imbalance Laxtiy Abductor weakness Trochanteric non-uion Surgical Treatment The decision to use operative treatment to stabilize the hip joint is complex and the surgeon must take into consideration:
How many times the hip dislocated Interveral between dislocation How long after THA the dislocation occur Can the problem be solved by an operation Operative risks Treatment choices depends on the underlying mechanism of dislocation:
Correction of malposition Correction of soft tissue laxity Release contractures Addressing problems of impingement Using a large femoral head Constrained liners
