Early clinical application of Mako robot-assisted total knee arthroplasty in knee osteoarthritis / 中国骨伤

OBJECTIVE@#To investigate the early efficacy of Mako robot-assisted total knee arthroplasty (TKA) in the treatment of knee osteoarthritis (KOA) and summarize the initial application experience.@*METHODS@#Retrospective analysis of 73 patients with KOA treated with Mako robot-assisted TKA from June 2021 to December 2021. There were 16 males and 57 females, aged from 54 to 81 years old with an average of (67.8±6.6) years old. The hip knee and ankle angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), lateral femoral component angle (LFCA) and lateral tibial component angle (LTCA) were recorded and analyzed. WOMAC score and KSS were used to compare the functional recovery of patients preoperatively, 3 and 6 months postoperatively.@*RESULTS@#All the 73 patients were successfully treated without serious complications such as vascular and nerve injury, and all the incisions healed well at stageⅠwithout infection. The patients were followed up from 4 to 11 months with an average of (7.0±2.7) months, and the satisfaction rate of the last follow-up was 90.41% (66/73). WOMAC scores were (23.1±5.4) at 3 months and (14.8±4.1) at 6 months postoperatively. KSS clinical scores were ( 76.1±4.0) at 3 months and (82.1±3.7) at 6 months postoperatively;KSS functional scores were (74.3±3.1) at 3 months and (78.6±2.1) at 6 months after operation. Postoperative imaging showed good position of the prosthesis, HKA angle was (178.5±2.1)°, LDFA was (91.2±1.8)°, MPTA was(89.9±1.5) °, LFCA was (7.6±3.1)°, LTCA was (88.2±1.1)°. The mechanical axis within ±3° in sixty cases(82.2%), and the mechanical axis within ±6° in all the patients.@*CONCLUSION@#Mako robot-assisted TKA is a safe and effective surgery in the treatment of knee osteoarthritis, which exhibited good efficacy in the correction of lower limb alignment, soft tissue balance and improvement of knee function. The long-term efficacy needs further follow-up observation.

Improvement of China's legal system for public health emergency management from the perspective of lifecycle management / 中华流行病学杂志

A crucial lesson gained through the pandemic preparedness and response to COVID-19 is that all measures for epidemic control must be law-based. The legal system is related not only to public health emergency management per se but also to all aspects of the institutional supporting system throughout the lifecycle. Based on the lifecycle emergency management model, this article analyses the problems of the current legal system and the potential solutions. It is suggested that the lifecycle emergency management model shall be followed to establish a more comprehensive public health legal system and to gather the intelligence and consensus of experts with different expertise, including epidemiologists, sociologists, economists, jurist and others, which will collaboratively promote the science-based legislation in the field of epidemic preparedness and response for the establishment of a comprehensive legal system for public health emergency management and with Chinese characteristics.

Arthroplasty versus Internal Fixation for Displaced Intracapsular Femoral Neck Fracture in the Elderly: Systematic Review and Meta-analysis of Short- and Long-term Effectiveness / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>There is conflicting evidence as to whether the femoral head should be preserved or replaced in elderly patients with displaced intracapsular femoral neck fractures. In this article, we performed a systematic review and meta-analysis to compare the short- and long-term effectiveness of arthroplasty (AR) and internal fixation (IF).</p><p><b>METHODS</b>PubMed, Embase, and the Cochrane Library were searched systematically up to January 2016. All randomized controlled trials directly comparing the effectiveness of AR and IF for displaced intracapsular fracture were retrieved with no limitation on language or publication year.</p><p><b>RESULTS</b>In total, eight prospective randomized studies involving 2206 patients were included. The results of our study showed that patients in the AR group reported significantly lower complication (risk ratio: 0.56, 95% confidence interval [CI] = 0.38-0.80), re-operation (risk ratio: 0.17, 95% CI = 0.13-0.22), revision rates (risk ratio: 0.11, 95% CI: 0.08-0.16), and better function compared with their IF counterparts, and they were less likely to suffer postoperative pain. No statistically significant differences for the rates of mortality, infection, and/or deep vein thrombosis between AR and IF were found.</p><p><b>CONCLUSIONS</b>Based on our analysis, we recommend that AR should be used as the primary treatment for displaced intracapsular femoral neck fractures in the elderly. However, IF may be appropriate for those who are very frail.</p>

Results of a Second-generation Constrained Condylar Prosthesis in Complex Primary and Revision Total Knee Arthroplasty: A Mean 5.5-Year Follow-up / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The application of second-generation constrained condylar knee (CCK) prostheses has not been widely studied. This retrospective study was carried out to evaluate the clinical and radiographic outcomes of a second-generation CCK prosthesis for complex primary or revision total knee arthroplasty (TKA).</p><p><b>METHODS</b>In total, 51 consecutive TKAs (47 patients) were performed between June 2003 and June 2013 using second-generation modular CCK prostheses. The follow-up was conducted at 3rd day, 1st, 6th, and 12th months postoperatively and later annually. Anteroposterior (AP), lateral, skyline, and long-standing AP radiographs of the affected knees were taken. The Hospital for Special Surgery (HSS) Knee Score, the Knee Society Knee Score (KSKS), the Knee Society Function Score (KSFS), and range of motion (ROM) were also recorded. Heteroscedastic two-tailed Student's t-tests were used to compare the HSS score and the Knee Society score between primary and revision TKAs. A value of P < 0.05 was considered statistically significant.</p><p><b>RESULTS</b>Four knees (two patients) were lost to follow-up, and 47 knees (31 primary TKAs and 16 revision TKAs) had a mean follow-up time of 5.5 years. The mean HSS score improved from 51.1 ± 15.0 preoperatively to 85.3 ± 8.4 points at the final follow-up (P < 0.05). Similar results were observed in terms of the KSKS and KSFS, which improved from 26.0 ± 13.0 to 80.0 ± 12.2 and from 40.0 ± 15.0 to 85.0 ± 9.3 points, respectively (P < 0.05). No significant difference in the HSS, KSKS, KSFS, or ROM was found between primary and revision TKAs (P > 0.05). Two complications were observed in the revision TKA group (one intraoperative distal femur fracture and one recurrence of infection) while one complication (infection) was observed in the primary TKA group. No prosthesis loosening, joint dislocation, patella problems, tibial fracture, or nerve injury were observed. Radiolucent lines were observed in 4% of the knees without progressive osteolysis.</p><p><b>CONCLUSIONS</b>Second-generation modular CCK prostheses are a safe and practical treatment for both primary and revision knees that cannot be balanced. However, further studies focusing on different types of constrained prostheses are required to validate these results.</p>

Medium-term follow-up outcomes of total hip arthroplasty for patients with ankylosing spondylitis / 中国骨伤

<p><b>OBJECTIVE</b>To retrospectively study medium-term follow-up outcomes of total hip arthroplasty (THA) for patients with ankylosing spondylitis (AS).</p><p><b>METHODS</b>From January 2000 to December 2008, 67 patients (88 hip joints) with AS were treated with all ceramic interface THA. And 55 patients (74 hips) were finally followed up. Among them, there were 30 males and 25 females, with an average age of 32.6 (ranged 19 to 58) years old. Sixty-one hips were treated with biological prosthesis and 13 hips were treated with hybrid prosthesis. Fifty-five patients were followed up at least 5 years, with an average of (75.2 +/- 8.6) months. Clinical symptoms and radiography information were evaluated after follow-up.</p><p><b>RESULTS</b>Harris hip score were significantly improved from 30.8 +/- 7.0 preoperatively to 85.2 +/- 5.5 at the last follow-up (P<0.01). The hip movement range increased from (21.2 +/- 8.5) degrees preoperatively to (142.0 +/- 10.2) degrees postoperatively (P<0.01). The 5-year survival of prosthesis was 95.9%. One patient were renovated because of internal wall broken caused by injury, 1 was renovated for infection, 1 was renovated for fracture arround femoral stem prostheses, and 1 was treated with conservative treatment by dislocation. Three cases with abnormal sound were cured with non-operation. 7 cases with heterotopic ossification were not treated, 2 cases with thigh pain received conservative treatment. Bone dissolve around prosthesis, loose and sink of femur and acetabulum prosthesis were occurred in other cases.</p><p><b>CONCLUSION</b>THA for the treatment of AS is a reliable method, which has a satisfied medium-term follow-up outcomes.</p>

Reconstruction of segmental bone defects in the rabbit ulna using periosteum encapsulated mesenchymal stem cells-loaded poly (lactic-co-glycolic acid) scaffolds / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Repair of large bone defects remains a challenge for clinicians. The present study investigated the ability of mesenchymal stem cells (MSCs) and/or periosteum-loaded poly (lactic-co-glycolic acid) (PLGA) to promote new bone formation within rabbit ulnar segmental bone defects.</p><p><b>METHODS</b>Rabbit bone marrow-derived MSCs (passage 3) were seeded onto porous PLGA scaffolds. Forty segmental bone defects, each 15 mm in length, were created in the rabbit ulna, from which periosteum was obtained. Bone defects were treated with either PLGA alone (group A), PLGA + MSCs (group B), periosteum-wrapped PLGA (group C) or periosteum-wrapped PLGA/MSCs (group D). At 6 and 12 weeks post-surgery, samples were detected by gross observation, radiological examination (X-ray and micro-CT) and histological analyses.</p><p><b>RESULTS</b>Group D, comprising both periosteum and MSCs, showed better bone quality, higher X-ray scores and a greater amount of bone volume compared with the other three groups at each time point (P < 0.05). No significant differences in radiological scores and amount of bone volume were found between groups B and C (P > 0.05), both of which were significantly higher than group A (P < 0.05).</p><p><b>CONCLUSIONS</b>Implanted MSCs combined with periosteum have a synergistic effect on segmental bone regeneration and that periosteum plays a critical role in the process. Fabrication of angiogenic and osteogenic cellular constructs or tissue-engineered periosteum will have broad applications in bone tissue engineering.</p>

Icariin associated with exercise therapy is an effective treatment for postmenopausal osteoporosis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>There are no conclusive studies evaluating the interaction between icariin and exercise for treatment of osteoporosis; the efficacy and safety of this treatment combination remains to be evaluated. The purpose of this study was to investigate the effects of icariin treatment combined with exercise therapy on bone parameters and body weight of ovariectomized rats.</p><p><b>METHODS</b>Ovariectomized rats were used as a model of postmenopausal osteoporosis and were exposed to either icariin treatment, exercise, hormone replacement therapy, or a combination of the above. Untreated, ovariectomized rats and sham operated rats were used as controls. After 3 months of experimental interventions the effects of the treatments on the body and uterine weights, the physical and biomechanical properties of bones, and the expression of the osteoblast-specific gene Osterix (Osx), were assessed.</p><p><b>RESULTS</b>The weight gain of the ovariectomized rats was greater than that of the treated experimental groups. Uterine weight and serum estradiol levels were significantly greater in sham operated and estrogen-treated ovariectomized rats than in the other groups. Biomechanical parameters were improved significantly in ovariectomized rats treated with exercise alone or treated with exercise and icariin. Osx expression was increased in ovariectomized rats treated with exercise and icariin or treated with just icariin.</p><p><b>CONCLUSIONS</b>Exercise combined with icariin had a synergistic effect in the early prevention of osteoporosis in ovariectomized rats. The effects of icariin and exercise on osteoporosis are worth further exploration.</p>

Effects of electromagnetic fields on bone regeneration in experimental and clinical studies: a review of the literature / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To assess the experimental and clinical data regarding the effects of electromagnetic fields (EMFs) on fracture non-union.</p><p><b>DATA SOURCES</b>The English language literature regarding EMFs on fracture non-union were searched using MEDLINE, Web of Science and Embase, for the period January 2006 to June 2011. The search terms were electromagnetic fields and non-union/bone marrow stem cells (BMSCs)/bone.</p><p><b>STUDY SELECTION</b>Articles were included in the review if they were related to the use of EMFs on BMSCs or bone tissue. Papers without full manuscripts available were excluded.</p><p><b>RESULTS</b>The basic and clinical research in this field, while somewhat limited, supports the insightful application of EMFs to ameliorate disability due to fracture non-union.</p><p><b>CONCLUSIONS</b>Further basic and clinical research to validate the use of EMFs in facilitating function and bone reparative processes in fracture non-union is required.</p>

S-ROM modular arthroplasty combined with transverse subtrochanteric shortening for Crowe type IV congenital dislocation of hip / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>This work was carried out to evaluate the clinical efficacy and the complications of S-ROM modular hip arthroplasty combined with transverse subtrochanteric shortening for Crowe type IV congenital dislocation of the hip (CDH).</p><p><b>METHODS</b>A total of 28 consecutive patients with Crowe type IV CDH received treatment using this surgical technique from June 2003 to June 2010. The follow-up was conducted at 3 days, 1, 6, and 12 months after the operation and later annually at the outpatient of our hospital. Sequential pelvic plain film and normotopia film of the affected hip joint were taken. The limp and the Trendelenburg sign were also assessed, the ischiadic nerve injury was also evaluated by electromyogram, and Harris hip scores were recorded.</p><p><b>RESULTS</b>After operation, both the alignment and the position of the transverse osteotomies were good. None of the patients had presented complications of joint infection, prosthesis loosening, joint dislocation, or nerve injury.</p><p><b>CONCLUSIONS</b>S-ROM modular hip arthroplasty combined with transverse subtrochanteric shortening was a satisfactory and safe technique for the Crowe type IV congenital hip dislocation within a mean follow up of 53 months. Transverse subtrochanteric shortening could effectively prevent the distraction injury of sciatic nerve.</p>

Total hip arthroplasty for patients with osteoarthritis secondary to hip pyogenic infection / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pyogenic hip arthritis occurs most often in young patients. Delayed treatment causes significant anatomical deformation of bony and soft tissue structures leading to premature onset of secondary osteoarthritis. Total hip arthroplasty (THA) in patients who had osteoarthritis secondary to hip pyogenic infection has been associated with high complication rates.</p><p><b>METHODS</b>We analyzed 19 THAs performed from April 2003 to July 2008 in adults with osteoarthritis secondary to hip pyogenic infection (average age 40.7 years; range 34-52 years). There were 7 males and 12 females, the average age of infection was 10.6 years (range 7-13 years) and the average quiescent period of infection was 29.5 years (range 22-41 years). The count of white blood cell (WBC), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were examined routinely before surgery. The duration of followup was 34 months (range 6-52 months).</p><p><b>RESULTS</b>There was no evidence of infection according to laboratory values, intraoperative exploration and bacterial culture of joint fluids and synovial tissues. Split fracture above the lesser trochanter occurred in two hips and healed without adverse sequelae after fixation with wires. One patient with sciatic nerve palsy was successfully treated by positioning the hip in extension and the knee in flexion with complete resolution of motor symptoms one month later. There were no cases of dislocation, deep vein thrombosis, or postoperative reinfection. The symptoms and hip joint activities were significantly improved. The median Harris hip score improved from 47.3 preoperatively to 89.7 and the median range of motion from 53 degrees to 125 degrees.</p><p><b>CONCLUSIONS</b>It is safe and efficient to perform THA in patients who had osteoarthritis secondary to pyogenic hip arthritis when the infection is quiescent. The key points of successful surgery are exclusion of active infection preoperatively, quiescent period of infection more than ten years and adequate intraoperative soft tissue releases.</p>

A preliminary report of patellofemoral arthroplasty in isolated patellofemoral arthritis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Isolated patellofemoral osteoarthritis is not uncommon. Surgical treatment of isolated patellofemoral arthritis remains controversial and poses a challenging treatment dilemma. The present study aimed to evaluate the short-term results of patellofemoral arthroplasty for patients with isolated patellofemoral osteoarthritis.</p><p><b>METHODS</b>We analyzed 11 patellofemoral arthroplasties performed from March 2006 to September 2009 in 11 patients with isolated patellofemoral arthritis. The patients comprised 2 males and 9 females with an average age of 53.7 years (range, 46 - 74 years). Standard weightbearing radiographs were taken in the anteroposterior, lateral, and 45° axial views. The knee pain and functional status were evaluated by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scales and American Knee Society (AKS) scores. For comparison, 23 total knee arthroplasties in 23 patients with primary tibiofemoral osteoarthritis were matched according to age, gender, bilaterality and body mass index. The duration of follow-up was 23.7 months (range, 12 - 47 months).</p><p><b>RESULTS</b>The majority of the 11 patients experienced improvement in their patellofemoral symptoms after patellofemoral arthroplasty. The WOMAC scores improved considerably by 7.4 points with respect to pain and by 5.2 points with respect to function. The AKS scores also improved considerably by 23.9 points with respect to pain and 44.3 points with respect to function. Although the clinical outcomes after patellofemoral arthroplasty were not better than those after total knee arthroplasty, patellofemoral arthroplasty exhibited advantages in the shorter operation time, lower blood loss and increased postoperative range of motion. At the latest follow-up, there was no clinical or radiographic evidence of patellofemoral maltracking, loosening or wear.</p><p><b>CONCLUSIONS</b>On the basis of our experience in this relatively small series of patients with a short-term follow-up, patellofemoral arthroplasty is an effective treatment alternative to total knee arthroplasty in isolated patellofemoral arthritis. MRI and arthroscopy may contribute to define those patients with isolated patellofemoral degeneration.</p>

Selection of allografts for impaction bone grafting for bone defect reconstruction on the acetabular side / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To review the choices of allografts for bone defect reconstruction in acetabular revision surgery using the technique of impaction bone grafting.</p><p><b>DATA SOURCES</b>The data cited in this review were mainly obtained from articles listed in PubMed that were published from January 1993 to July 2009. The search terms were "impaction bone grafting", "particle size", "mechanical property" and "biological behavior".</p><p><b>STUDY SELECTION</b>Articles relevant to the choices of allografts and their results for bone defect reconstruction on the acetabular side were selected.</p><p><b>RESULTS</b>Different choices of allografts, including the particle size, process of irradiation or fat reduction, composition and particle grade, are made to improve the survival rate of a prosthesis in acetabular revision surgery. This review, which compares both mechanical and biological factors, summarizes the experimental and clinical results for different techniques.</p><p><b>CONCLUSIONS</b>Fresh frozen cancellous allografts with particle sizes ranging from 7 to 10 mm are a favorable choice for reconstruction of bone defects of American Academy of Orthopedic Surgeons (AAOS) types II (cavitary defect) and III (combined cavitary and segmental defect) on the acetabular side. A fat-reducing procedure with saline or solvent/detergent is controversial. Adding autologous marrow into irradiated allografts, which provides reliable mechanical stability and biological safety, may be a substitute for fresh frozen allografts. Cortical bone can be a supplementary material in cases of insufficiency of cancellous allografts. Cartilage should be excluded from the graft material. Further research is required to demonstrate the best particle grade, and randomized controlled trials in clinical practice are required to obtain more information about the selection of allografts.</p>

Combined use of extensively porous coated femoral components with onlay cortical strut allografts in revision of Vancouver B2 and B3 periprosthetic femoral fractures / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Periprosthetic femoral fractures following total hip arthroplasty are getting more prevalent. The aim of this study was to evaluate the clinical results of combined use of uncemented extensively porous coated femoral components with onlay cortical strut allografts in revision of Vancouver type B2 and B3 periprosthetic femoral fractures.</p><p><b>METHODS</b>Thirteen hips after total hip arthroplasty in 13 patients who suffered a Vancouver B2 or B3 periprosthetic fracture were treated with an uncemented extensively porous coated femoral component combined with onlay cortical strut allografts. Each patient was assigned a Harris hip score, and a visual analog scale (VAS) score for pain and satisfaction. Radiographs were examined for component stability, fracture site and allograft-host union and allograft reconstruction.</p><p><b>RESULTS</b>At an average of 5.3-year follow-up, no patient required repeat revision. The average Harris hip score was (71.8 +/- 6.3) points, the pain VAS score was (16.6 +/- 4.3) points, and the patient satisfaction VAS score was (81.5 +/- 5.7) points. Radiographic examination showed no detectable loosening of the prostheses, and 12 cases were presented fixation by osseointegration and the other one was stable fibrous ingrown fixation. All fractures united for (5.2 +/- 1.4) months in average. And all onlay strut allografts united to host bone for about (11.5 +/- 2.6) months.</p><p><b>CONCLUSIONS</b>Combined use of uncemented, long stemmed, extensively porous coated implant with cortical onlay strut allografts can achieve good clinic results and high rate of union for both fracture site and allograft-host bone junction. This technique could be used routinely to augment fixation and healing of Vancouver B2 and B3 periprosthetic fractures.</p>

Use of mid-vastus approach in less invasive primary total knee arthroplasty / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Total knee arthroplasties (TKR) combined with the concept of reduced trauma to tissue has been performed by many doctors. The aim of this study was to retrospectively assess the early results of a group of TKR with a mid-vastus approach, which was characterized as no patellar eversion, no disruption of suprapatellar pouch and extensor mechanism, and to compare the outcome with conventional operative techniques.</p><p><b>METHODS</b>A total of 59 patients (67 knees) were followed. All patients received the same prosthesis of Genesis II posterior-stabilized total knees. Of them, 29 consecutive patients (34 knees) had a mid-vastus approach and were operated on with less invasive instruments and techniques. The mean follow-up duration was 11.6 months. Clinical evaluations were performed according to the Hospital for Special Surgery scores; radiographic assessment followed the guidelines of the Knee Society. Postoperative recovery of quadriceps strength and the extensor mechanism was also evaluated.</p><p><b>RESULTS</b>No prosthetic loosening or anterior knee pain was found at the latest follow-up; 1 patient had a superficial infection and postoperative stiffness of the knee who undertook a debridement and manipulation several months later. The angulations of tibial osteotomy were within normal range. The average preoperative and postoperative Hospital for Special Surgery scores were 57.9 points and 86.1 points respectively. The mean postoperative range of motion was 113.5 degrees . Most patients regained their quadriceps strength at the third or fourth month postoperatively.</p><p><b>CONCLUSIONS</b>The overall early results from using the mid-vastus approach were comparable with that of using a standard approach, and the exposure did not affect the accuracy of the tibial cut. The muscle maximal contraction strength recovered gradually after operation. The approach was safe and patients of this group obtained satisfactory outcomes.</p>

Changes in expression of adrenomedullin in the myocardium of streptozotocin-induced diabetic rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Adrenomedullin is a potent vasodilating peptide and involved in many cardiovascular diseases. However, whether adrenomedullin is involved in the pathogenesis of diabetic cardiomyopathy is still unknown. Our aim was to characterize the expression pattern of adrenomedullin in the myocardium of streptozotocin-induced diabetic rats.</p><p><b>METHODS</b>The weight, blood glucose, and urine glucose of 20 streptozotocin-induced diabetic rats were measured before and after model induction in the diabetic and control groups. The alteration of the adrenomedullin expression was explored in the left ventricular myocardium in both groups by immunohistochemistry. Changes in heart ultrastructure were also analyzed by using hemotoxylin and eosin staining and transmission electron microscopy. All data were analyzed by the independent samples t test.</p><p><b>RESULTS</b>The data of weight, blood glucose, and urine glucose had no significant difference between the control and the diabetic groups before animal model induction. Four weeks after the induction of diabetes, the differences between the two groups in weight, blood glucose, and urine glucose were distinct. When compared with the control group, the diabetic group showed ultrastructural changes including hypertrophy, fibrosis, myofibrillar disarrangements, mitochondrial disruption, and increase in nuclear membrane invaginations. A significant decrease of adrenomedullin expression was also observed in cardiac myocytes of the diabetic rats (P < 0.01).</p><p><b>CONCLUSIONS</b>Our study provides experimental evidence that hyperglycemia could damage cardiac myocytes. Down-regulation of cardioprotective peptide adrenomedullin in the myocardium of streptozotocin-induced diabetic rats may contribute to the diabetic cardiomyopathy and left ventricular dysfunction.</p>

Position of the prosthesis and the incidence of dislocation following total hip replacement / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Dislocation is the second most common complication of hip replacement surgery, and impact of the prosthesis is believed to be the fundamental reason. The present study employed Solidworks 2003 and MSC-Nastran software to analyze the three dimensional variables in order to investigate how to prevent dislocation following hip replacement surgery.</p><p><b>METHODS</b>Computed tomography (CT) imaging was used to collect femoral outline data and Solidworks 2003 software was used to construct the cup model with variabilities. Nastran software was used to evaluate dislocation at different prosthesis positions and different geometrical shapes. Three dimensional movement and results from finite element method were analyzed and the values of dislocation resistance index (DRI), range of motion to impingement (ROM-I), range of motion to dislocation (ROM-D) and peak resisting moment (PRM) were determined. Computer simulation was used to evaluate the range of motion of the hip joint at different prosthesis positions.</p><p><b>RESULTS</b>Finite element analysis showed: (1) Increasing the ratio of head/neck increased the ROM-I values and moderately increased ROM-D and PRM values. Increasing the head size significantly increased PRM and to some extent ROM-I and ROM-D values, which suggested that there would be a greater likelihood of dislocation. (2) Increasing the anteversion angle increased the ROM-I, ROM-D, PRM, energy required for dislocation (ENERGY-D) and DRI values, which would increase the stability of the joint. (3) As the chamber angle was increased, ROM-I, ROM-D, PRM, Energy-D and DRI values were increased, resulting in improved joint stability. Chamber angles exceeding 55 degrees resulted in increases in ROM-I and ROM-D values, but decreases in PRM, Energy-D, and DRI values, which, in turn, increased the likelihood of dislocation. (4) The cup, which was reduced posteriorly, reduced ROM-I values (2.1 -- 5.3 degrees ) and increased the DRI value (0.073). This suggested that the posterior high side had the effect of 10 degrees anteversion angle.</p><p><b>CONCLUSIONS</b>Increasing the head/neck ratio increases joint stability. Posterior high side reduced the range of motion of the joint but increased joint stability; Increasing the anteversion angle increases DRI values and thus improve joint stability; Increasing the chamber angle increases DRI values and improves joint stability. However, at angles exceeding 55 degrees , further increases in the chamber angle result in decreased DRI values and reduce the stability of the joint.</p>

Finite element analysis of impact loads on the femur / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the stress distribution and fracture mechanism of proximal femur under impact loads.</p><p><b>METHODS</b>The image data of one male's femur were collected by the Lightspeed multi-lay spiral computed tomography. A 3D finite element model of the femur was established by employing the finite element software ANSYS, which mainly concentrated on the effects of the directions of the impact loads arising from intense movements and the parenchyma on the hip joint as well as those of the femur material properties on the distribution of the Mises equivalent stress in the femur after impact.</p><p><b>RESULTS</b>The numerical results about the effects of the angle sigma of the impact loads to the anterior direction and the angle gamma of the impact loads to the femur shaft on the bone fracture were given. The angle sigma had larger effect on the stress distribution than the angle gamma, which mainly represented the fracture of the upper femur including the femoral neck fracture when the posterolateral femur was impacted. This result was consistent with the clinical one. The parenchyma on the hip joint has relatively large relaxation effect on the impact loads.</p><p><b>CONCLUSIONS</b>A 3D finite element analysis model of the femoral hip joint under dynamic loads is successfully established by using the impact dynamic theory.</p>

Total hip arthroplasty with uncemented cup and femoral head autografts for coxarthrosis due to dysplasia / 中华外科杂志

<p><b>OBJECTIVE</b>To evaluate the outcomes of total hip arthroplasty (THA) for coxarthrosis due to dysplasia with acetabular reconstruction of an uncemented cup in conjunction with a femoral head autograft.</p><p><b>METHODS</b>A retrospective study was made on 21 hips in 20 patients (18 female and 2 male; average age, 50 years) with developmental hip dysplasia treated by THA with use of an uncemented cup. The acetabular cup was placed at the level of the true acetabulum; all patients required autogenous femoral head grafts due to acetabular deficiency. The average coverage of the acetabular cup by the femoral head autograft was 31% (range, 10% to 45%). Eight hips had less than 25% cup coverage and 13 between 25% and 50%. The average follow-up period was 4.7 years (range, 1-8 years). All patients were evaluated with the use of a modified Harris hip score. Radiographic evaluations were made by preoperative and follow-up.</p><p><b>RESULTS</b>All autografts were seen to be united to host-bone. No collapse of the autograft and no hip had the evidence of loosening of component seen in all patients. According to the modified Harris hip score, the average hip score increased from 46 at preoperation to 89 at the final review. Preoperative leg-length discrepancy was greater than 2 cm seen in all except 1 patient with bilateral hip dysplasia. After surgery, only 2 of 20 patients still had a leg-length discrepancy greater than 1 cm. Three hips showed minor resorption in the lateral portion of the graft which was not supporting the cup. Three hips developed grade 1 Brooker heterotopic ossification and one had grade 2.</p><p><b>CONCLUSIONS</b>THA with an uncemented cup in conjunction with a femoral head autograft for coxarthrosis due to dysplasia could obtain favorable results. This method could provide reliable acetabular fixation and appeared to restore acetabular bone stock in patients with developmental hip dysplasia when the coverage of the cementless cup by the graft does not exceed 50%.</p>