The mechanical model of femur mid-diaphysis with a rectangular open section in the exterior cortex was developed and a finite element method was adopted in calculating and analysing the changes of torsional stiffness and the stress distribution when the dimension of the open section altered. It showed that the open section with a length of 1 OD (femur mid-diaphysis diameter) had little influence on the femur torsional stiffness or stress distribution. The torsional stiffness decreased most dramatically as the length increased from 2 to 4 OD. Shear stress peaked at the center of the open section. This conclusion provides an important theoretical ground for the operative methods and the dimension control of an open section in clinical orthopaedics.
Biomechanical Phenomena ; Femur ; physiopathology ; surgery ; Humans ; Models, Theoretical

BACKGROUNDFeatures of necrotic lesions and various interventions could affect the biomechanics of the femoral head. A three-dimensional finite-element analysis was designed to demonstrate necrotic femoral head stress changes with various sizes of necrotic lesions, and evaluate the effect of tantalum rods on preventing femoral head cracking.

METHODSFemoral computed tomography scans were used to build a normal three-dimensional finite-element femoral head model in a computer. Based on the normal model, necrotic models of different lesion diameters (15 mm, 20 mm and 30 mm) were created, as were the repaired models with tantalum rods for each diameter. After a series of meshing and force loading, the von Mises stress distributions, simulating single-legged stance, and stresses on specific points under loaded conditions were determined for each model.

RESULTSDeep exploration into the burdened area of the femoral head indicated that higher stresses to the femoral head were observed with a larger necrotic lesion; the largest stress concentration, 91.3 MPa, was found on the femoral head with a lesion diameter of 30 mm. By contrast, topical stress on the surface of the necrotic regions was lowered following implantation of a tantalum rod, and the changes in stress were significant in models with lesions of 15 mm and 30 mm in diameter, with the best biomechanical benefit from the tantalum rod found with a lesion diameter of 15 mm.

CONCLUSIONSFemoral heads with larger necrotic lesions usually have a higher stress concentration and a higher risk of collapse. Various sized lesions on the femoral head can benefit from the mechanical support offered by the implantation of a tantalum rod; however, femoral heads with smaller sized lesions may benefit more. A thorough evaluation of the lesion size should be conducted prior to the use of tantalum rod implants in the treatment of femoral head necrosis.

Femur Head ; physiology ; Femur Head Necrosis ; physiopathology ; Finite Element Analysis ; Humans ; Stress, Mechanical

OBJECTIVETo evaluate the clinical results of continuing skeletal traction and impaction granular bone grafting via window in femoral neck for the treatment of avascular necrosis of femoral head.

METHODSFrom August 2000 to October 2004, 23 patients (35 hips) with femoral head necrosis were treated by continuing skeletal traction and impacting granular bone grafting via bone window on femoral neck. There were 18 males, 5 females, with an average age of 32 years ranging from 19 to 52 years, which included 7 hips of stage II, 28 hips of stage III. All patients had various degrees of hip joint pain and suffered from limited hip motion. The necrotic bone, granulation tissue and hardening zone were completely cleaned via bone window on the femoral neck. The autogenous granular iliac bone was grafted, and impacted persistently. Skeletal traction through femur condyles was applied continually after the operations. The effects before and after operation were compared by the hip pain, function, joint activity and X-ray.

RESULTSRegular follow-up was carried out after the patients were dismissed from the hospital. The follow-up period was 6 months, 1 year, 2 years, 3 years, 4 years, 5 years respectively. According to Wang's standard, the average score was increased from (52.66 +/- 12.53) preoperatively to (88.94 +/- 5.84) preoperatively at half a year, (89.78 +/- 6.18) at 1 year, (86.37 +/- 7.46) at 2 years, (84.08 +/- 7.57) at 3 years, (83.76 +/- 8.08) at 4 years, and (76.83 +/- 8.98) at 5 years. Scores of operation were greatly increased and the difference had statistical significance.

CONCLUSIONContinuing skeletal traction after the operation, completely cleaning the necrotic bone and impacting granular bone grafting via window on femoral neck can greatly raise the satisfactory rate of clinical effect and delay the progression of disease for avascular necrosis of femoral head.

Adult ; Bone Transplantation ; methods ; Female ; Femur Head Necrosis ; physiopathology ; surgery ; Femur Neck ; Humans ; Male ; Middle Aged

Chronic myelogenous leukemia (CML) is a malignant clonal disorder of hemopoietic stem cells characterized by abnormal proliferation and accumulation of immature granulocyte. Leukostasis is one of the complications of CML and is characterized by partial or total occlusion of microcirculation by aggregation of leukemic cells and thrombi leading to respiratory, ophthalmic or neurologic symptoms. We experienced a rare case of avascular necrosis of the femoral head as the initial presentation of chronic myelogenous leukemia. A 24-year-old male patient was admitted to our hospital with pain in the right hip joint. The patient was diagnosed to be suffering from chronic myelogenous leukemia by packed marrow with granulocytic and megakaryocytic hyperplasia and the presence of Philadelphia chromosome. The right hip joint pain was attributed to avascular necrosis of the femoral head. And the avascular necrosis could be considered as the complication of chronic myelogenous leukemia due to microcirculatory obstruction of the femoral head. The avascular necrosis of the right femoral head was treated with bipolar hemiarthoplasty.
Male ; Leukemia, Myeloid, Chronic/*diagnosis/physiopathology ; Humans ; Femur Head Necrosis/*diagnosis/physiopathology ; Adult

Recent studies in Western countries have reported a significant association between glomerular filtration rate (GFR) and bone mineral density (BMD) in the absence of dialysis among the general population. However, there have been few studies regarding renal function and BMD among Korean or Asian subjects with moderate to severe (stage 3 or 4) chronic kidney disease (MS-CKD). The aim of the present study was to investigate the association between MS-CKD and BMD in the general Korean population. BMD, serum creatinine and other measures were obtained from 3,190 subjects (1,428 males and 1,762 females; the fourth Korean National Health and Nutrition Examination Survey). GFR was estimated using the Cockcroft-Gault formula, with adjustment for body surface area. After adjustment for all variables, multiple regression analysis showed that BMD in the femur neck, total femur and lumbar spine were positively associated with eGFR in both males and females. Additional analysis showed that MS-CKD was also significantly associated with osteoporosis in both males and females (odds ratio [OR] 2.20, 95% confidence interval [CI] 1.15-4.20 in males; and OR 1.96, 95% CI 1.33-2.88 in females). Individuals with MS-CKD may be at higher risk of osteoporosis even among Asians.
Adult ; Aged ; *Bone Density ; Creatinine/blood ; Female ; Femur/physiopathology ; Femur Neck/physiopathology ; Glomerular Filtration Rate ; Humans ; Lumbar Vertebrae/physiopathology ; Male ; Middle Aged ; Nutrition Surveys ; Odds Ratio ; Osteoporosis/etiology ; Regression Analysis ; Renal Insufficiency, Chronic/complications/*physiopathology ; Republic of Korea ; Severity of Illness Index

OBJECTIVETo investigate the effects of the attachment site of grafts and the tunnel angle on the function of knee joint after anterior cruciate ligament reconstruction.

METHODSFrom January 2006 to May 2009, 47 patients(32 males and 15 females, ranging in age from 19 to 51 years old, with an average of 35.3 years old) were treated with single-bundle reconstruction of anterior cruciate ligament. Several indexes were measured at the latest follow-up as follow: attachment sites of graft on the femoral condyle were recorded, the femoral tunnel angles on coronal and sagittal planes were measured on postoperative X-ray films. According to the IKDC score, these patients were divided into two groups. In the first group, 38 patients were found the IKDC score more than 90 at the latest follow-up, and in the second group 9 patients were found IKDC score less than 90. By comparing the two groups, the relation of the indexes and postoperative function of knee was analyzed.

RESULTSThe IKDC which was more than 90 at the latest follow-up was found in 38 patients, whose femoral attachments site of ACL was positioned at (29.73 +/- 4.31)% (ranged from 16.21% to 53.82%) from the posterior end of Blumensaat's line. IKDC which was less than 90 was found in 9 patients, whose femoral attachments site of ACL was positioned at (46.61 +/- 3.43)% (ranged from 27.18% to 72.34%). There was significant difference between the two groups (P = -0.000 7). The IKDC more than 90 at the latest follow-up was found in 38 patients,whose femoral tunnel angle on coronal plane was (49.5 +/- 4.72) degrees (ranged from 33 degrees to 67 degrees) and on sagittal plane was (31.3 +/- 5.12) degrees (ranged from 11 degrees to 45 degrees) were significantly less than those whose IKDC less than 90 at the latest follow-up on coronal plane was (67.6 +/- 3.09) degrees (ranged from 41 degrees to 81 degrees) and on sagittal plane was (41.2 +/- 5.69) degrees (ranged from 23 degrees to 56 degrees) (P = 0.000 7, P = -0.000 8).

CONCLUSIONThere is close relation between the attachment site of grafts and the tunnel angle with the function of knee, so in anterior cruciate ligament should be anatomic reconstructed with the anterior medial approach.

Adult ; Anterior Cruciate Ligament Reconstruction ; Female ; Femur ; surgery ; Humans ; Knee Joint ; physiopathology ; Male ; Middle Aged

Avascular necrosis is a progressively devastating disease and primarily affects weight-bearing joints. The hip is the most commonly affected joint. In early stage, nonoperative (including pharmacologic intervention and biophysical treatments) and operative modalities for protecting hip joint have become the main therapeutic methods. However there is still no satisfied mothod with reasonable effect. According to the treatment of the avascular necrosis of the femoral head of the pre-collapse stage, core decompression with modification of technique is still one of the safest and most commonly employed procedures. Recently there have been attempts to enhance the effect of core decompression with use of various growth and differentiation factors. Which is the hot spot of current research. Early diagnosis is the key to the treatment of the avascular necrosis of the femoral head. Comprehensive treatment which is based on the core decompression is still the main treatment of today.
Biophysical Phenomena ; Femur Head Necrosis ; drug therapy ; physiopathology ; surgery ; therapy ; Humans ; Weight-Bearing

BACKGROUNDThere is a relatively high failure rate of the femoral component in patients with avascular necrosis at the intermediate-term follow-up. Improving the geometrical fit of the femoral stem against the medullary canal may help to provide long-term survivorship of the hip replacement for patients with avascular necrosis.

METHODSWe designed a specific stem, based on morphometric studies of proximal femoral canals in Chinese avascular necrosis patients and evaluated the stem by finite element analyses, comparing the novel stem with two commercially available and commonly used stems.

RESULTSThe morphometric data from avascular necrosis patients showed specific geometric differences in the proximal femoral canal, including profile curves in both the sagittal and coronary planes than the patients with femoral neck fracture. The shorter stemmed prostheses (Fitmore(®) and our stem) performed better than the longer stemmed prosthesis (VerSys(®)).

CONCLUSIONSThis is the first study to investigate the femoral geometries of Chinese avascular necrosis patients. Our stem provides better stability and is theoretically beneficial to bone ingrowth, which may increase the long-term stability and fixation of the implant.

Adult ; Aged ; Biomechanical Phenomena ; Female ; Femur Head Necrosis ; physiopathology ; Finite Element Analysis ; Humans ; Male ; Middle Aged

Changes in bone stress in the proximal femur following implantation can be estimated with the use of composite beam theory. The aim of this study was to construct the mathematical analytical models for predicting the degree of stress shielding and to test the validity of the predictions using finite element simulation. To define the periprosthetic bone stress values, the proximal femur was divided into eleven equidistant cross sections, then each section was divided into four quadrants corresponding to the anterior, posterior, medial and lateral aspects of the femur. Bone stress values were calculated by both mathematical analytical models and finite element analysis, then linear regression analyses produced slopes and R-values that show numerical and finite element results corresponding well to intact femur and both the types of fixation with/without cement. And the results also showed that femoral bone stress shielding by both the prostheses occurred in most periprosthetic zones. The most serious regions occurred in the proximal medial quadrant. This study has succeeded in creating the mathematical analytical models to predict the bone, cement and prostheses stress values, and thus can help us to evaluate the mechanical behavior of total hip replacement, to further understand the distinction between different fixation, and to make advances in implant design, surgical technique and long-term results.
Arthroplasty, Replacement, Hip ; Biomechanical Phenomena ; Femur ; physiopathology ; Humans ; Models, Theoretical ; Stress, Mechanical ; Tensile Strength

OBJECTIVEUltrasound scanning can provide the information of acoustic impedance through the ultrasonic reflection theory. This study tries to introduce the application of the ultrasonic technique in predicting biomechanical properties of cancellous bone.

METHODSThe rat femoral head embedded in plexiglass was used as the bone specimens for ultrasound scanning and the gray scale images scanned by ultrasound microscope were collected and analyzed.

RESULTSThe value of acoustic impedance was calculated by analyzing the gray scale image.

CONCLUSIONThe application of ultrasonic microscopy can show more value about the microstructure of biomechanical properties of bone tissue.

Animals ; Biomechanical Phenomena ; Bone Density ; Femur Head ; diagnostic imaging ; physiology ; Microscopy, Acoustic ; methods ; Osteoporosis ; physiopathology ; Rats