Clinical experience on postoperative balance of hemostasis and antithrombus for patients with hemophilic arthritis after arthroplasty / 中国骨伤

<p><b>OBJECTIVE</b>To observe the clinical significance of postoperative personalized antithrombotic therapy for patients with hemophilic arthritis (HA) patients after arthroplasty.</p><p><b>METHODS</b>From September 2005 to October 2013, 11 cases of arthroplasty for hemophilic arthritis in hip and knee total operation 14 times,including 1 case of double knees (calculated as one operation), operation in left knees 6 times, operation in right knees 5 times, 2 in hip. All the patients were male and the age ranged from 23 to 57 years old,with an average of (36.1 ± 11.0) years old; the average weight was (64.1 ± 8.9) kg. All the patients were preoperatively diagnosed and classified as hemophilic arthritis with the radiological images and laboratory tests. According to the function of joints, the risk of postoperative venous thromboembolism (VTE), and dynamic observation of Factor VIII:C (FVIII:C) activity, patients were treated with personalized antithrombus by adjusting the dosage of recombinant human coagulation factor VIII (Kogenate FS). All the patients were orderly divided into postoperatively distal joints moving group and none-moving group to observe the coagulation function.</p><p><b>RESULTS</b>The enrolled patients had no postoperative complication of VTE and pulmonary embolism (PE). The APTT and D-2 were different between two groups in the postoperative early stage. Length of hospital day was shorter in the moving group than none-moving group.</p><p><b>CONCLUSION</b>Because of the self-coagulation disorder, patients with HA tended to bleed. However it doesn't mean that there is no risk of postoperative thrombosis. Therefore,it's important to determine how to control the balance between postoperative antithrombus, hemostasis,and coagulation factor replacement therapy after arthroplasty for HA. Postoperative moving has proved helpful for HA, especially in reducing the risk of hemostasis and shortening the time in hospital.</p>

Finite element analysis on stress distributions during novel semi-hip prosthesis assembly / 医用生物力学

Objective To simulate the stress generated by contact with the femur during the assembly of novel semi-hip prosthesis, and discuss the operating limits and adaptive prosthesis profile in clinic. Methods CT scans were conducted on the proximal end of the femur in a male volunteer of 60 years old as a physical model. By transferring the CT data to finite element modeling software, the physical model was simplified, meshed, materialized and assembled with the model of prosthesis to establish the three-dimensional finite element model. Surface to surface contact relationship between the femur and the prosthesis was also constructed by utilizing contact elements. Relative sliding distance and stress distribution were solved while simulating the process of assembling the prosthesis. Results Additional stress was generated on the sudden change area of the contact surface when the prosthesis was seated. The greatest contact pressure came from the changing section of the ridge of the prothesis, and the maximum assembly stress and sliding distance range increased nonlinearly along with the pushing distance. The increase rate of additional stress was enhanced significantly while Δz≥0.5 mm. Conclusions Compared with the prosthesis without ridge, the prosthesis with ridge can be easily seated and obtain mechanical stabilization. However, the relevant clinical operating limits should be obeyed to avoid generating excessive additional stress during the implantation of prosthesis, which may cause treatment failure due to the damage in bone cortex.

Development and mechanical testing on TC hemi-arthroplasty prosthesis system for femoral intertrochanteric fractures / 医用生物力学

Objective To develop a new hemi-arthroplasty system-Trochanteric Prosthesis System (TC) for the treatment of unstable femoral intertrochanteric fractures in the elderly, so as to preserve bone mass and meet requirement of functional exercises at early stage. Methods A normal male adult volunteer was chosen to receive CT scanning at middle and upper regions of his both intact femur. The serial digitized image data of spiral CT in DICOM format were imported to finite element modeling software to establish a three-dimensional (3D) solid model of the proximal femur. The Pro/E software was used to conduct computer-aided design of the new hemi-arthroplasty prosthesis system and then its metal model was also made by rapid prototyping techniques. After repeated verification and improvement on cadaver femur, the femoral prosthesis was molded and assembled in the solid fracture mode for finite element analysis. The unstable femoral intertrochanteric fracture model obtained from the fresh cadaver of an elderly male was chosen to make A2.2 Type of such fracture model in AO classification system. The new hemi arthroplasty prosthesis system was implanted and assembled into the model and received mechanical testing, including material performance testing, prosthesis head/neck and stem fatigue testing, anti-compression and anti-torsion testing, according to the National Industrial Standard YY0117 and YY0118. Results The sample of new hemi-arthroplasty prosthesis sustained 5 million cycle (8 Hz) fatigue testing on the part of the head-neck and the stem body without any breakage and failure. With the sample implanted into the intertrochanteric fracture model, the maximum compressive strength and torsional strength of the sample reached over 2 kN and 15.5 N•m without failure, respectively. The contact stresses between the stem and the femur were mostly distributed at the region below the femoral trochanter, where the maximum average Von Mises stress values were 17.6~26.4 MPa. Stresses at the region of intertrochanteric fractures were at a low level. The maximum average Von Mises stress values at the greater and lesser trochanter region were 2.7 and 4.9 MPa, respectively. Conclusions The new developed hemi-arthroplasty prosthesis has the advantages of easy performance, reliable fixation, sufficient bone preservation and it is capable of fulfilling the demands of early weight bearing and functional exercises. It is suitable for the treatment of unstable femoral intertrochanteric fractures in the elderly.

Short-term curative effects of Tantalum rod treatment in early avascular necrosis / 中国骨伤

<p><b>OBJECTIVE</b>To explore the recent clinical curative effect of Tantalum rod in treating the early avascular necrosis.</p><p><b>METHODS</b>From January 2008 to November 2008, the 25 patients (39 hips) with early avascular necrosis accepted tantalum rod placement and included 9 males (11 hips) and 16 females (28 hips) with an average age of 37 years old ranging from 18 to 74 years old. Four patients (6 hips) caused by Alcoholic, 6 patients (8 hips) by hormone, 2 cases (2 hips) by traumatic, 13 cases (23 hips) by idiopathic. Steinberg preoperative stage involved 7 hips in period I, 24 hips in period II, 8 hips in period III. Curative effect analysis included preoperative and postoperative Harris score, radiographic changes and hip replacement for follow-up to accept the end of the femoral head survival rate.</p><p><b>RESULTS</b>All patients were followed up for 6 to 47 months (averaged 37.4 months). All 12 hips imaging appeard progress,including tantalum rod exit in 1 hip, hip hemiarthroplasty collapse in 3 hips, the area increased to avascular necrosis in 8 hips. Six hips accepted total hip replacement, including imaging progress in 5 hips (41.7%, 5/12), no imaging progress in 1 hip (3.7%,1/27). All hips' Kaplan-Meier survival curves showed 6-month survival rate was (97.4 +/- 2.5)% after tantalum stick insertion, 1-year survival rate was (94.7 +/- 3.6), and 2-year survival rate was (88.6 +/- 5.4)%, 3-year survival rate was (72.5 +/- 11.2).</p><p><b>CONCLUSION</b>It is effective for treatment of avascular necrosis of femoral head in Steinberg I and II by Tantalum rod, and it can effectively relieve femoral head replacement time.</p>

Total hip arthroplasty for the post-traumatic osteoarthritis after open reduction and internal fixation of acetabular fracture / 中华外科杂志

<p><b>OBJECTIVE</b>To explore the surgical strategy of traumatic osteoarthritis of the hip joint secondary to the failure of open reduction and internal fixation (ORIF) treatment on acetabular fractures.</p><p><b>METHODS</b>Eighteen cases of traumatic osteoarthritis of the hip joint received total hip arthroplasties from May 2002 to December 2009, who had undergone the surgery of ORIF after acetabular fractures. There were 12 male and 6 female with an average age of 53 years (45 to 66 years). It was average 11.2 months (6.0 to 24.0 months) from the present of pain and limp to the operation. It was average 35 months (8 to 72 months) from ORIF procedure on acetabular fracture to total hip arthroplasty. Harris score was 50 points in average (26 to 70 points).</p><p><b>RESULTS</b>All 18 cases were followed up 40 months in average (12 to 86 months). They were allowed to get out of bed on 1 week after the operation. The time of full weight bearing lagged to 2 or 3 months after the operation. All patients had the function of their hips improved with Harris score of 86 points in average (80 to 92 points).</p><p><b>CONCLUSIONS</b>The procedures of ORIF on acetabular fracture make lots of trouble to total hip arthroplasty. It is important to rebuild the normal biological mechanisms of acetabulum and uses uncement fixed prosthesis as possible as it can.</p>

The effect of rotational alignment of the femoral components on the patellofemoral biomechanics in total knee arthroplasty / 中华外科杂志

<p><b>OBJECTIVE</b>To study the effect of rotational alignment of the femoral components on the patellofemoral biomechanics in total knee arthroplasty (TKA) demonstrated on autopsy specimens, as the guide for surgeons to choose the correct reference axis for rotational alignment of the femoral components and to reduce the patellofemoral joint complications.</p><p><b>METHODS</b>Select 9 frozen fresh human cadaver knees without gross deformities or instabilities and mount specimens on a patellofemoral joint testing jig connected to a Model 8501 Instron machine (Instron Corporation, Canton, MA). The study simulated the action of squatting from the standing position with the foot firmly planted. Standard TKA was performed in each specimen by the same senior surgeon using Nexgen LPS total knee system (Zimmer Corporation, Warsaw Indiana). Alter rotational alignment of the femoral components referenced to the transepicondylar axis and the Whiteside's line respectively. Measure biomechanics of the patellofemoral joints using Fuji prescale film at 30 degrees , 60 degrees , 90 degrees , 120 degrees of knee flexion respectively. The digital values were obtained by the handheld pressure measurement systems (FPD-305E, FPD-306E) and Autocad software.</p><p><b>RESULTS</b>The rotational alignment of the femoral components paralleled to the transepicondylar axis had the best results of the peak value of the patellofemoral contact pressure (P < 0.05). There were no statistically significant differences in patellofemoral contact area (P > 0.05). But the patellofemoral contact area had the close correlations to the angles of the knee flexion and the specimens.</p><p><b>CONCLUSIONS</b>Rotational alignment of the femoral components has a great influence on the patellofemoral contact pressure in total knee arthroplasty. It is reliable for surgeons to choose the transepicondylar axis as the reference axis to rotate femoral components.</p>

The use of a closed-suction drain in total knee arthroplasty: a prospective, randomized study / 中华外科杂志

<p><b>OBJECTIVE</b>To determine the value of using a closed-suction drain in cemented knee arthroplasty.</p><p><b>METHODS</b>One hundred patients were prospectively randomized into two groups, one group underwent cemented total knee replacement with a single deep closed-suction drain, and the other group (n = 50) no drain.</p><p><b>RESULTS</b>The total blood loss was significantly greater in those with a drain although those without lost more blood into the dressings. There was no statistical difference in the postoperative swelling or pain score, ecchymosis, deep vein thromboses (DVT), time at which flexion was regained or the incidence of infection at a minimum of two years after surgery in the two groups.</p><p><b>CONCLUSION</b>There is no evidence to support the use of a closed-suction drain in cemented knee arthroplasty.</p>

Radiographic analysis of rotational malalignment between tibial component and femoral component in total knee arthroplasty / 中华外科杂志

<p><b>OBJECTIVE</b>To identify possible reasons of rotational mismatch between tibial component and femoral component in total knee arthroplasty and choose a right reference axis for placing the components in the operation and to decrease the complications.</p><p><b>METHODS</b>Forty normal Chinese knees were studied. There were 20 men and 20 women, and average age was 34 years (range, 18 - 42 years). The images of cross sections of the distal femur were obtained by spiral CT scanning (0.5 mm thickness). Scan direction was aligned to be in the plane perpendicular to the mechanical axis of the tibia. On the images of the distal femur and the proximal tibia, three baselines for the anteroposterior axis of the femoral component were drawn based on the clinical epicondylar axis and the surgical epicondylar axis and 3 degrees lateral rotated to the posterior condylar surfaces of the femur separately, and a baseline for the anteroposterior axis of the tibial component was drawn based on the medial 1/3 of the tibial tuberosity. The rotational mismatch angles were measured between each component by using the Autocad software.</p><p><b>RESULTS</b>The mean rotational mismatch angle between tibial component and femoral component is 2.94 degrees for the clinical epicondylar axis, 6.50 degrees for the surgical epicondylar axis and 6.83 degrees for 3 degrees lateral rotation of the femoral component referenced to the posterior condylar axis separately.</p><p><b>CONCLUSIONS</b>Landmarks of each bone were the intrinsic cause of the rotational mismatch in total knee arthroplasty. The clinical epicondylar axis can be chosen for the ideal reference to rotational alignment of the femoral component because of its minimal rotational mismatch between each component.</p>