Effects of denosumab on bone mineral density around proximal femoral prosthesis after total hip replacement in postmenopausal osteoporotic patients / 中国骨伤

OBJECTIVE@#To evaluate the effect of denosumab on bone mineral density around proximal femoral prosthesis after total hip arthroplasty(THA) in the postmenopausal osteoporotic patients.@*METHODS@#Fifty-four consecutive patients underwent unilateral primary THA were included in this retrospective study. Twenty-five patients received denosumab for osteoporosis as the treatment group, and the twenty-nine without denosumab were the control group. At 1 week, 3month, 6 months, and 12 months after THA, bone turnover markers and proximal femoral periprosthetic bone mineral density (BMD) were measured.@*RESULTS@#At 3, 6 and 12 months after operation, the level of TRACP-5b in the control group was significantly higher than that in the treatment group (P<0.05);the level of bone-specific alkaline phosphatase (BALP) between two groups showed significant difference in 12 months after operation (control group was higher than treatment group, P<0.05). The BMD of Gruen 1 and Gruen 7 decreased at 3, 6 and 12 months after operation compared with 1 week after operation. Comparing the treatment group and the control group, the differences of the the decrease of BMD in Gruen 1 and Gruen 7 were no significant at 3 months after surgery. In Gruen 1, Gruen 7 at 6 months after operation and Gruen 1, Gruen 7 at 12 months after operation, the decrease of BMD in the control group was significantly higher than that in the treatment group(P<0.05). It is suggested that desudumab could inhibit the loss of BMD after 6 months, and continuously show a protective effect on bone mass at 12 months after operation.@*CONCLUSION@#After THA in postmenopausal patients with osteoporotic femoral neck fracture, Desuzumab can reduce the loss of BMD around the proximal femoral prosthesis and effectively inhibit bone resorption.

Construction and evaluation of a nomogram prediction model for periprosthetic fractures after total hip arthroplasty / 中国骨伤

OBJECTIVE@#To construct and evaluate nomogram prediction model for periprosthetic fractures in patients undergoing total hip arthroplasty (THA).@*METHODS@#A total of 538 patients who underwent THA from April 2013 to February 2019 were selected as the research subjects, including 318 males and 220 females, aged 40 to 60 years old with an average age of (50.79±6.37) years old. All patients with THA were divided into non-fracture group (506 patients) and fracture group (32 pathents) according to the 3-year follow-up results. Univariate and multivariate Logistic regression analyses were performed to analyze the influencing factors of postoperative periprosthetic fractures in patients with THA. A nomogram prediction model for periprosthetic fractures in patients undergoing THA was constructed, and the validity and discrimination of the prediction model were evaluated.@*RESULTS@#The proportion of patients with osteoporosis, trauma history, and hip revision in the fracture group were higher than those in the non-fracture group(P<0.05), and the proportion of bone cement prosthesis was lower than that in the non-fracture group(P<0.05). The osteoporosis status[OR=4.177, 95%CI(1.815, 9.617), P<0.05], trauma history[OR=7.481, 95%CI(3.104, 18.031), P<0.05], and hip revision[OR=11.371, 95%CI(3.220, 40.153, P<0.05] were independent risk factors for postoperative periprosthetic fractures in patients undergoing THA, cemented prosthesis [OR=0.067, 95%CI(0.019, 0.236), P<0.05] was an independent protective factor for postoperative periprosthetic fractures in patients undergoing THA(P<0.05). Hosmer-Lemeshow goodness of fit test showed that χ2=7.864, P=0.325;the area under the curve (AUC) for periprosthetic fractures in patients undergoing THA was 0.892 with a sensitivity of 87.5% and a specificity of 77.7% by receiver operating characteristic(ROC) curve.@*CONCLUSION@#The nomogram prediction model for periprosthetic fractures after THA constructed in this study has good discrimination, which is beneficial to clinical prediction of periprosthetic fractures in patients undergoing THA, and facilitates individualized fracture prevention.

Effects of Total Hip Arthroplasty on Proximal Femoral Bone Remodeling / 医用生物力学

Objective To analyze the influence of total hip arthroplasty (THA) on the process of proximal femoral bone remodeling by using the Wolff bone remodeling theory. Methods According to control equation of bone remodeling, the program of bone remodeling was written in Python language. Preoperative femur model and postoperative femur and prosthesis finite element models were established respectively in ABAQUS software. The process of bone reconstruction before and after THA operation was compared to analyze the effect of prosthesis implantation on mechanical properties of the femur in the middle and long term after THA operation. Results The stress in proximal femur continued to decrease after prosthesis implantation, and the stress site was transferred from the femoral head to the prosthesis, resulting in an obvious stress shielding phenomenon. Bone loss in the stress shielding area was serious. The femoral shaft cortical bone became thinner and the stress shielding was relieved. The medial side at the bottom of the prosthesis was compressed, and the stress was significantly higher than that of the lateral side, where the bone was unevenly distributed. Conclusions After THA operation, obvious stress shielding occured at proximal medial side of the femur, leading to bone loss and prosthesis loosening. The difference in stress levels on both sides at the bottom of the prosthesis resulted in an uneven bone distribution, causing the discordance between the prosthesis and the femur, as well as postoperative pain in the middle part of the thigh.

Mortality Rate and Ten Years Survival of Elderly Patients Treated with Total Hip Arthroplasty for Femoral Neck Fractures

@#Introduction: Mortality following traumatic femoral neck fractures in the elderly (age >60 years) is influenced by many factors. Addressing some of them may reduce the mortality rate thus improving patient survival and quality of life. Materials and methods: This study was a retrospective research using data collected from Hospital Sultanah Bahiyah, Kedah between the years 2008-2018. We measured outcomes such as age, gender, hospital stay, default rate, ambulation post-surgery, American Society of Anaesthesiologists score (ASA) and surgical timing in correlation with mortality rate and 10-year survival of elderly patients treated with Total Hip Arthroplasty for femoral neck fractures in this centre. Results: A total of 291 traumatic femoral neck fractures aged above 60 years post total hip arthroplasty performed were included. There was higher number of female (n =233) compared to male (n=53) Estimated 10 years survival from Kaplan Meier was 42.88% (95% CI: 33.15, 52.54). One year mortality rate in our study was found to be 18.9%. The average time to event was 7.1 years (95% CI:33.15, 52.24) with a mean age group of 75. Discussion: Total hip arthroplasty patients not ambulating after surgery had a 4.2 times higher hazard ratio compared to ambulators. Those with pre-existing systemic disease (ASA III and IV) were found to have the highest hazard ratio, almost five times that of healthy patients, after adjusting for confounding factors. Delay of more than seven days to surgery was found to be a significant factor in 10-year survival with a hazard ratio of 3.8, compared to surgery performed earlier. Conclusion: Delay of more than 7 days to surgery in 10 years survival was significant with high hazard ratio. It is a predictor factor for survival in 10 years. A larger sample size with a prospective design is required to confirm our findings regarding “unacceptable surgical timing” for femoral neck fractures in patients above 60 years of age.

Preoperative Measurement to Estimate Stem Anteversion in DDH Patients after Total Hip Arthroplasty / 医用生物力学

Objective Based on the principle of uncemented stem design, the femoral anteversion in different CT planes before total hip arthroplasty (THA) and stem anteversion after THA was compared, so as to find out the preoperative measurement to estimate stem anteversion in patients with developmental dysplasia of the hip(DDH) after THA. Methods Twenty-one primary THA patients (28 hips) who were diagnosed with DDH between September 2007 and May 2013 in Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine were selected. Preoperative and postoperative CT scans were performed on all patients. The femoral anteversion angle was defined as the angle between the midcortical line between the anterior and posterior cortical line in five CT slices and the posterior condylar axis. The slice levels for the 4 femoral sites were selected，including the area just distal to the femoral head, the center of the lesser trochanter，1 cm height above center of the lesser trochanter, 2 cm height above center of the lesser trochanter (marked as femoral anteversion 1-4). Femoral anteversion 5 was defined as the midcortical line of the anterior cortical line in the slice of 2 cm height above center of the lesser trochanter and the posterior cortical line in the slice of 50% of the distance from the top of greater trochanter to the center of the lesser trochanter above the center of the lesser trochanter. The stem anteversion angle was defined as the angle formed by the stem neck major axis and the posterior aspect of the femoral condylar line. The cup version and stem alignment were also calculated. The difference value and correlation coefficients of femoral anteversion 1-5 and stem anteversion were compared. Results Femoral anteversion 1-5 was 17.70°±10.54°, 35.59°±7.21°, 31.09°±7.98°, 24.71°±9.11°, 21.94°±10.10°, respectively。Stem anteversion was 20.52°±10.90°. The difference value between stem anteversion and femoral anteversion 1-5 was 2.82°±6.27°, -15.08°±7.99°, -13.80°±15.68°, -4.19°±5.69°, -1.42°±4.07°, respectively. Cup anteversion was 25.60°±11.65°, and combined antevertion was 46.11°±13.28°，sagittal stem tilt was 1.13°±1.53°. There were statistically significant differences between femoral anteversion 1-4 and stem anteversion (P＜0.05), and no statistical difference was found between femoral anteversion 5 and stem anteversion. The correlation coefficients of femoral anteversion 1-5 and stem anteversion were 0.829, 0.681, 0.689, 0.853, 0.928, respectively. Conclusions Femoral anteversion 5 had a highly positive correlation with stem anteversion, which was an effective a substitute of stem anteversion before THA.

Effects of Femoral Offset on Musculoskeletal Multi-Body Dynamics and Contact Mechanics of Artificial Hip Joint for DDH Patients / 医用生物力学

Objective To investigate the biomechanical effects of femoral offset (FO) on total hip arthroplasty (THA) patients with developmental dysplasia of the hip (DDH). Methods Based on the musculoskeletal dynamic software AnyBody and the related data from a female patient with Crowe Ⅳ DDH, the corresponding patient-specific lower extremity musculoskeletal multi-body dynamic model was constructed to analyze both hip joint forces and abductor forces within ±20 mm variation of FOs. The dynamic finite element (FE) model of S-ROM stem with varying offsets was also established. The dynamic load during a whole walking gait cycle calculated by the multi-body musculoskeletal model was applied to this FE models, and the Von Mises stress, contact stress, and stem-sleeve micromotion were then analyzed. Results A variation of ±20 mm offset had small influences on peak forces of hip joints. However, the decrease in FO could lead to an obvious increase in peak abductor force, while the increase in FO could lead to an obvious increase in the maximum Von Mises stress, contact stress, and micromotion of S-ROM prosthesis stem. Conclusions The change in FO had an obvious influence on the abductor forces, the maximum Von Mises stress, the contact pressure and the consequent fretting wear of THA patients with DDH, which should be carefully considered by surgeons.

Preoperative Measurement to Estimate Stem Anteversion in DDH Patients after Total Hip Arthroplasty / 医用生物力学

Objective Based on the principle of uncemented stem design, the femoral anteversion in different CT planes before total hip arthroplasty (THA) and stem anteversion after THA was compared, so as to find out the preoperative measurement to estimate stem anteversion in patients with developmental dysplasia of the hip(DDH) after THA. Methods Twenty-one primary THA patients (28 hips) who were diagnosed with DDH between September 2007 and May 2013 in Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine were selected. Preoperative and postoperative CT scans were performed on all patients. The femoral anteversion angle was defined as the angle between the midcortical line between the anterior and posterior cortical line in five CT slices and the posterior condylar axis. The slice levels for the 4 femoral sites were selected，including the area just distal to the femoral head, the center of the lesser trochanter，1 cm height above center of the lesser trochanter, 2 cm height above center of the lesser trochanter (marked as femoral anteversion 1-4). Femoral anteversion 5 was defined as the midcortical line of the anterior cortical line in the slice of 2 cm height above center of the lesser trochanter and the posterior cortical line in the slice of 50% of the distance from the top of greater trochanter to the center of the lesser trochanter above the center of the lesser trochanter. The stem anteversion angle was defined as the angle formed by the stem neck major axis and the posterior aspect of the femoral condylar line. The cup version and stem alignment were also calculated. The difference value and correlation coefficients of femoral anteversion 1-5 and stem anteversion were compared. Results Femoral anteversion 1-5 was 17.70°±10.54°, 35.59°±7.21°, 31.09°±7.98°, 24.71°±9.11°, 21.94°±10.10°, respectively。Stem anteversion was 20.52°±10.90°. The difference value between stem anteversion and femoral anteversion 1-5 was 2.82°±6.27°, -15.08°±7.99°, -13.80°±15.68°, -4.19°±5.69°, -1.42°±4.07°, respectively. Cup anteversion was 25.60°±11.65°, and combined antevertion was 46.11°±13.28°，sagittal stem tilt was 1.13°±1.53°. There were statistically significant differences between femoral anteversion 1-4 and stem anteversion (P＜0.05), and no statistical difference was found between femoral anteversion 5 and stem anteversion. The correlation coefficients of femoral anteversion 1-5 and stem anteversion were 0.829, 0.681, 0.689, 0.853, 0.928, respectively. Conclusions Femoral anteversion 5 had a highly positive correlation with stem anteversion, which was an effective a substitute of stem anteversion before THA.

Analysis of the Functional Outcome of Limb Length Discrepancy after Total Hip Replacement

Background: The Aim of the study was to analyze the functional outcome of limb length discrepancy after total hip replacement. . Methods: It is a Prospective study on 21 patients who underwent total hip replacement with different hip pathology between November 2015 and October 2017. Results: 13 males and 8 females patients with a mean age of 35.31±7.42 (21-50) were followed up for a time of 12months. Limb length discrepancy and hip function of 21 patients who underwent primary total hip arthroplasty were assessed before surgery and 1month, 3 month and 12 month after surgery. Limb length discrepancy was evaluated before and after surgery by clinical and radiological method, Functional outcome assessed by using the Oxford hip score (OHS) and Harris hip score(HHS). Preoperatively all patients had shorter limb length as compared to contra lateral side. Postoperatively in 42.9% (9/21) the limb operated on was longer, in 19 %( 4/21) of cases limb operated on was shorter and in 31 %( 8/21) postoperative limb length were equal. Postoperatively limb length discrepancy was present in 61.9 %( 13/21) & was perceived by 53.8 %( 7/13 of cases) when either shortening or lengthening exceeded 10mm. Oxford hip score (OHS) and Harris hip score (HHS) were significantly increased at subsequent follow up (at 1, 3 and 12 months). Functional scores (OHS and HHS) were excellent in patients with equal limb length as compared to those having shorter or longer limb length. Conclusion: Patient with limb length discrepancy had negative influence in relation to limping and pain. Patients should be counseled preoperatively about possible limb length differences and associated symptoms.

A Practical Method for Acetabulum Component Assembling in Total Hip Arthroplasty with Lateral Position / 中国运动医学杂志

Objective To get a controllable acetabulum component inclination angle during the total hip arthroplasty(THA) with the lateral position,a new method using a self-made instrument was introduced.Methods Totally 80 consecutive patients undergoing THA at the lateral position were enrolled.Forty acetabular components were assembled using a new method with a self-made instrument referring to the 42 degrees' angle drawn on the wall(group A),while another 40 acetabular cups were implanted free-handedly(group B).The postoperative inclination angle was evaluated on the anterior-posterior pelvic radiographs.Results The average inclination angle was 43.3° ± 3.7°(34.7°～49.1°) in group A and 40.3 ± 4.5o(32.8°～50.7°) in group B.Moreover,40/40 of group A and 38/40 of group B were in the Lewinnek's inclination safe zone(P＞0.05),without significant differences between the two groups.Conclusion It is practical and reliable to decide the acetabular component orientation using the lateral position instrument and reference angle on the wall.

To evaluate the operation effect of total hip arthroplasty with portable gait analyzer / 医用生物力学

Objective To assess the surgical and rehabilitation effects of total hip arthroplasty (THA) through comparing changes of gait parameters in patients before and after THA.MethodsThe gaits of 7 THA patients during their natural walking before THA and in the 25th week after THA were tested by using a portable gait analyzer (IDEEA, MiniSun, USA). The gait parameters including single limb support (SLS) time, double-limb support (DLS) time, SLS/DLS, stride length, foot fall strength were collected for statistic analysis by SPSS 16.0 and Excel 2010. Results The SLS of the healthy leg after THA significantly decreased (P<0.05); for the majority of THA patients, the SLS of the diseased leg decreased, the DLS and SLS/DLS of the healthy leg also decreased obviously, while the foot fall strength of the diseased leg increased after THA. Conclusions The SLS of the healthy leg can be used as a sensitive parameter to evaluate the operation effect of THA. The portable gait analysis system can quantitatively reflect the subject’s gait, thus it is a non-invasive and convenient method of evaluating the operation effect in clinic.

Periacetabular stress distributions during normal gait cycle and its guiding function in acetabular reconstruction of THA / 医用生物力学

Objective To study the basic regular patterns of stress distributions inside and outside periacetabular districts during normal gait cycle of healthy adults, so as to provide clinical guidance for acetabular reconstruction of total hip arthroplasty (THA). Methods Based on CT scans of a male and a female healthy adult volunteer, The three-dimensional model including pelvis and proximal femur was reconstructed. By using an inhomogeneous material distribution scheme which was based on CT data to calculate elastic modulus and convergence analysis, each element was given a corresponding material attribute. The dynamic change of hip contact force during a normal gait cycle was used as the load condition to the model. Von Mises stress of the nodes inside and outside the model was considered as the criterion to assess the results. Results During normal gait, the stress on the hip surface of two volunteers was mainly transmitted from postersuperior part of acetabulum to auricular surface along posterolateral of iliac wing, and the maximum stress was at the district near greater sciatic. As for the superior, middle and inferior section of two volunteers' acetabulum, the stress was distributed both on cortical and cancellous bone of postersuperior part. However, in terms of acetabular anterior and posterior column, the stress distribution was mainly found on cortical bone. Conclusions According to the observed acetabular stress distribution pattern of health adults during normal gait cycle, choosing acetabular component with more suitable size and controlling the placement of acetabular component with more accuracy could obtain some acetabular reconstruction plan better in accordance with stress distributions during normal gait.

Influence from acetabular component orientation on stress distributions of periacetabulum / 医用生物力学

Abstract： Objective To study the influence from different placement angles of acetabular component on inner and outer stress distributions of periacetabulum in acetabular reconstruction of total hip arthroplasty (THA), so as to explore proper orientation for improving stability of acetabular component after THA. Methods Based on model with inhomogeneous material property assignment, nine THA models with acetabular component at different anteversion angles(15°, 20°, 25°) and abduction angles(40°, 45°, 50°) as well as one normal hip model were constructed. The maximal hip contact force in phase of single leg stance during normal gait cycle was chosen as the loading condition. In addition, according to the qualitative and quantitative principle, inner and outer stress distributions on 9 THA models were analyzed and compared with the normal hip model as control. Results When abduction angle of acetabular component was the nearest to anatomic angle (19° anteversion, 46° abduction) of acetabulum, the phenomenon of stress shielding on periacetabulum was the most obvious. When abduction angle of acetabular component was placed at 45° and anteversion angle changed from 15° to 25°, no significant influence was exerted on the whole stress distributions of THA models. Meanwhile, when anteversion angle of acetabular component was 15°, the THA model had good stability in stress distributions, and the phenomenon of stress shielding on cortical and cancellous bone was obviously improved. Conclusions For patients who have normal anatomic acetabulum and need to be treated with THA, the abduction angle of acetabular component should be placed at 45°, as that of normal acetabulum; the anteversion angle should be 5° smaller than that of normal acetabulum and between 15° and 20°.

Biomechanical analysis and reasoning on dislocation failure after total hip arthroplasty / 医用生物力学

Objective To propose a detailed method on the diagnosis of dislocation failure by studying the mechanism of mechanical failure and causes of dislocation occurrence after the total hip arthroplasty (THA). Methods The correlation between dislocation failure and clinical situation, product design and patients was analyzed by establishing the dislocation model to study the biomechanical mechanism of dislocation procedure. Results The reasoning route for dislocation analysis after THA was proposed and the visual hip prosthesis motion analysis software was developed and validated. Conclusions Case study on dislocation failure after THA shows that the proposed method and developed software can judge the cause of dislocation incidence in detail, and determine the relationship between implanting position for the hip prosthesis and dislocation incidence. Meanwhile, it can find the best implanting position before operation and analyze the risk of dislocation incidence, which will be helpful for the prosthesis design.

Biomechanical analysis and reasoning on aseptic loosening failure after total hip arthroplasty / 医用生物力学

Objective To propose some detailed methods for diagnosis of aseptic loosening failure in clinic by studying the mechanical mechanism and the specific causes of aseptic loosening failure after the total hip arthroplasty (THA). Methods The causes of aseptic loosening were investigated from the view of biomechanics, such as strength of the bone cement layer, interface fretting, stress shielding, wear and osteolysis; the relationships between aseptic loosening failure and products, clinical and patient factors were analyzed; the method to detect loosening before the revision surgery was also studied. Results The reasoning route for aseptic loosening failure analysis after THA was proposed, and detection of aseptic loosening with fluoroscopic analysis (FSA) technique before the revision surgery was conducted successfully. Conclusions The reasoning route for aseptic loosening failure analysis can help to discover reasons of failure occurrence. Loosening can be detected and confirmed in vivo by FSA method, which can also assist the clinician for diagnosis and treatment of aseptic loosening after the THA.

Dislocation risk after total hip arthroplasty / 医用生物力学

Objective To investigate and analyze the risk of dislocation failure after total hip arthroplasty (THA). Methods The optical motion capture system was used to obtain the kinematic data of the lower limbs during actions of daily living (ADLs) from normal people. The visual hip prosthesis motion analysis software was designed and developed to measure the maximum safe motion space of the hip prosthesis with different design parameters and judge the safety of the hip prosthesis by analyzing the relative motion relation between the cup and prosthetic stem. Results Based on the measured kinematics data, the motion analysis software could compare the range of motion of the natural joints and that after THA. Thus, the relationship between the dislocation of hip prosthesis and ADLs was obtained and the dislocation risk after THA was investigated. Conclusions There is a high risk when activities that require a high flexion motion are performed, especially for the kneeling and squatting activity.

Cementless Total Hip Arthroplasty with Fourth Generation Ceramic-on-Ceramic Articulation: Minimum Two Years of Follow-up / 대한고관절학회지

PURPOSE: The purpose of this study is to report clinical and radiographic results over a period of two 2 years after cementless total hip arthroplasty (THA) with fourth generation ceramic-on-ceramic articulation. MATERIALS AND METHODS: We studied 22 patients, 23 cases which were followed up for two years among 25 patients, 26 patients who underwent cementless THA with the fourth generation ceramic between April 2009 and December 2009. The average age of the patients was 55.9 years old(22 to 72 years old), and the average follow-up duration was 28 months(24 to 32 months). A clinical evaluation was performed using the Harris hip score (HHS), and radiologic evaluation was based on acetabular cups and osteolysis of the femoral stems, instability, distance, angle, and so on. RESULTS: HHS showed an increase, from 54 for before-surgical treatment, to 91 at the last follow-up. Inguinal pain was observed in one case, and femoral pain was observed in two cases. Stable fixation was achieved in all cases, and no instability, osteolysis, or movement of acetabular cups and femoral stems was observed. CONCLUSION: Clinical and radiological short-term results for use ofthe fourth generation ceramic-on-ceramic cementless THA have favorable so far. Further follow-up study should be performed for evaluation of the long-term results.

Effect of total hip arthroplasty on biomechanical behavior of natural femur / 医用生物力学

Objective To study the deformation and stress distribution of femur after total hip arthroplasty (THA) and its influence on the vibration mode and natural frequency of femur. Method Two finite element models of natural femur and femur after THA were developed on the basis of computed tomography (CT) scans from a normal young man to investigate the biomechanical behavior of the subjectunder gait condition and make the modal analysis. Results (1) After THA, obvious stress concentration was obtained around the prosthesis neck, and the stress shielding was observed; (2) The peak stress of femur model after THA increased to 4.36 times of the original one; (3) The natural frequency for constrained mode was much higher than that of free mode; (4) With the increase of vibration mode, the differences in natural frequency between two models became larger; (5) Bending and twisting were the main vibration mode of femur, and there were no significant changes in vibration mode before and after THA. Conclusions The prosthesis could change the mechanical and structural properties of the original femur. In order to avoid prosthesis loosening derived from sympathetic vibration, the vibration property of femur must be taken into consideration in the design of prosthesis.

Comparison of Bipolar Hemiarthroplasty and Total Hip Arthroplasty using Large Heads in Patients with Femoral Neck Fractures / 대한정형외과학회잡지

PURPOSE: To compare the short-term clinical outcomes of total hip arthroplasty (THA) with a large diameter femoral head (36 mm) and bipolar hemiarthroplasty (BA) in physiologically active elderly patients with femoral neck fractures. MATERIALS AND METHODS: This non-concurrent clinical trial included 169 patients with femoral neck fractures, who had been treated with prosthetic replacement from February 2004 and June 2007. Eighty-nine and 80 cases underwent BA and THA, respectively. The mean follow-up period was 36 months (18-52). The clinical outcomes were analyzed, and the latest follow-up radiographs were assessed to determine the number of complications. RESULTS: The mean operation time was longer in the THA group. The pain, mobility, and walking ability factors were better in the THA group than in the BA group. There was no limitation in the range of motion in the early post-operative period and no dislocations were encountered in either group. CONCLUSION: THA with a large diameter femoral head is recommended for the management of patients with femoral neck fractures.

Early Results after the Treatment with Total Hip Arthroplasty with Larger Diameter Femoral Head versus Bipolar Arthroplasty in Patients with Femoral Neck Fractures

PURPOSE: To study the short-term clinical outcomes of THA with a large diameter femoral head (36 mm) and BA in physiologically active elderly patients with displaced femoral neck fractures MATERIALS AND METHODS: This non-concurrent clinical trial included 40 patients with displaced femoral neck fractures, who had been treated with prosthetic replacement from February 2004 and December 2004. Twenty patients underwent either THA or BA. The mean follow-up period was 18 months(12~26). The clinical outcome was analyzed, and the latest follow-up radiographs were assessed to determine the number of complications, such as osteolysis, loosening, fracture, dislocation, etc. RESULTS: The clinical and functional results were better in the THA group than in the BA group. The mean operation time was significantly shorter in the BA group than in the THA group. The mean intra-operative blood loss was similar in the two groups. Despite there being no limitation of the range of motion in the early post-operative period, there was no dislocation encountered in either group. CONCLUSION: A THA with a large diameter femoral head is recommended for the management of patients with femoral neck fractures because THA produces a better result than BA.

The Effect of Implant Positionon Postoperative Dislocation after Total Hip Arthroplasty / 대한정형외과학회잡지

PURPOSE: This study evaluated the effect of the implant position on a postoperative dislocation after total hip arthroplasty (THA) using computed tomography. MATERIALS AND METHODS: 1171 THAS were performed by one surgeon from March 1993 to September 1996, and from May 1998 to October 2004. There were 41 postoperative dislocations. Of these, 20 cases of the dislocated group and 20 cases of the control group were available for CT to check the acetabular and femoral anteversion of the implanted prostheses. Both groups were matched according to the type and size of the prosthesis, patient factors, and the surgical approach in order to eliminate the possible effect of these factors on a dislocation. All dislocations involved in this study occurred posteriorly. The cup anteversion, stem anteversion, acetabular inclination, vertical off-set, horizontal off-set and leg length discrepancy were measured using the CT and conventional radiographs on the PACS system. RESULTS: The cup anteversion was significantly lower in the dislocated group than in the non-dislocated group (p<0.001, chi-square test) respectively. The other variables were not different significantly in both groups. CONCLUSION: These findings suggests that among the variables of the implant positions, cup anteversion is the most important risk factor for a posterior dislocation after THA.