Architectural changes in occurring in the proximal femur (resorption) after total hip arthroplasty (due to stress shielding) continues to be a problem. In an attempt to reduce these bony changes the concept of short and femoral neck sparing stem designs have been advocated. The purpose of this study was to evaluate the early clinical and radiological results, especially stem fixation and bone remodeling of proximal femur after total hip arthroplasty.

A total of forty-five patients (fifty-four hips) were included in the study. There were twenty men and twenty-five women. The mean age at the time of operation was 53.9 years (range, twenty-six to seventy-five years). Clinical and radiological evaluation were performed at each follow-up. Bone densitometry was carried out on all patients one week after operation and at the final follow-up examination. The mean follow-up was 1.3 years (range, one to two years).

The mean preoperative Harris hip score was 45 points (range, 15 to 48 points), which improved to a mean of 96 points (range, 85 to 100 points) at the final follow-up. No patient complained of thigh pain at any stage. No acetabular or femoral osteolysis was observed and no hip required revision for aseptic loosening of either component. One hip (2%) required open reduction and fixation with a cable for calcar femorale fracture. Bone mineral densitometry revealed a minimal bone remodeling in the acetbulum and proximal femur.

The geometry of this ultra-short anatomic neck sparing cementless femoral stem has proved to provide effective initial stability even without the diaphyseal portion of the stem. We believe that femoral neck preservation and lateral flare of the stem provide an axial and torsional stability and more natural loading of the proximal femur.

Modified posterior approach preserving short external rotators would be able to contribute greatly to prevent dislocation after total hip arthroplasty. We modified the posterior approach to the hip by preserving the external rotator muscles in order to enhance joint stability after total hip arthroplasty in patients with osteonecrosis of the femoral head. The aim of the this study was to determine the influence of external rotator preserving posterior approach in primary total hip replacement on early dislocation and clinical outcome.

Three hundred sixty-four primary total hip replacements were divided into two groups based on how the external rotators were treated at surgery. External rotator preservation (Group 1, 165 hips) group was compared with reattachment (Group 2, 199 hips) group by evaluating the clinical and radiographic outcome at one year postoperative. Anteversion was significantly less in Group 1 as compared to Group 2 (P < 0.001). There was no significant difference in inclination between the groups (P > 0.05 in all comparisons). No dislocations were found in 165 hips with external rotator preservation whereas dislocations was noted in 11 (3.9%) in Groups 2, respectively. Group 1 had the higher mean Harris hip score (97.2±2.9 points) as compared with Group 2(94.9±3.4).

The results of this study showed that external rotators could play an important role in preserving joint stability after total hip arthroplasty in patients with osteonecrosis of the femoral head. It can be implied that this modified posterior approach would be able to contribute greatly to prevention of dislocation, and improve clinical outcome after total hip arthroplasty.

There was used cement in first generation total ankle arthroplasty, but first generation of ankle arthroplasty was abandoned because of aseptic loosening of component. For the treatment of aseptic loosening of ankle arthroplasty, there had been many methods. One of methods of revisional ankle arthroplasty is the ankle arthodesis. The authors report a case of revisional ankle arthroplasty using allograft with hybrid external fixation.

45 year old male had surgery of cemented total ankle arthroplasty on his right ankle 20 years ago. He went to our clinics because of motionless and pain of his right ankle. He got the mild pain on his right ankle after 5 years surgery. His pain was managed by oral NSAIDS for 15 years. The pain was aggravated recently. There were osteophytes on posterior aspect of ankle joint and radiolucency around the implant, subtalar arthrosis at the radiograph. There was also sclerosis around the ankle joint.

The authors decided revisional surgery. At the operative findings, we can see the loosening of talar and tibial component and large posterior osteophyte bridging between remained talus and tibial bone. There were no infection signs. After remove the implant, there was big space remained. For the regaining the limb length, we used femoral head allograft. The graft was fixed with 6.5 mm cannulated screws and addition fixed with ilizarov external fixation. Also additional auto bone graft from the osteophytes was applied. Compression over the ilizarov external fixation was done at the end of the operation. Weight bearing was allowed immediate after surgery. Ilizarov ring was removed 6 weeks after surgery. At the 3 months after surgery, bony union was obtained on radiographs.

AOFAS score was improved from 30 to 70 6 mo after surgery. There was no pain on his right ankle. Patient satisfied with arthrodesis with allograft at final follow-up.

The purpose of this study is to compare the two prosthesis which were used for total ankle arthroplasty. From Sept. 2003 to Jun 2007, 13 patients and 14 ankles that could be follow up more than 2 years. Semiconstrained type (Group I, 7cases) and Unconstrained type (Group II, 7cases) were used for total ankle arthroplasty. Mean age was 63.2 year-old, 12 ankles are men and 2 ankles were women. Mean follow up periods were 31.1 months. The criteria to compare the clinical result were postoperative range of motion (ROM), AOFAS foot score and residual bone stock of medial malleolus.

Postoperative ROM of group I was 37.5±7.1 degree and of group II was 51.4±8.9. Postoperative AOFAS score of group I was 76.1±13.8 and of group II was 86.0±5.7. Residual bone stock in medial malleolus of group I was 6.1mm±0.7 and of group II was 11.5mm±0.9. Total number of complication in our study was 9 cases. 3 cases were a malleolar fracture, two occurred at intra-operation, the other at follow-up period. Re-operation was done in 6 cases, 3 cases were calcaneal corrective osteotomy, 2 cases were resection of a heterotopic bone and one case was pedicular flap operation for skin problem.

In our hospital, mobile bearing type prosthesis showed good result than a semiconstrained type in respect of ROM improvement and of residual bone stock in medial malleolus. AOFAS score between two groups showed no definite difference. But small number of patients and short term follow up period is a defect in our study, afterward more population and long term follow up period are needed.

Recently, it has been reported that the posterior stabilised implant clinically used for the total knee replacement (TKR) may have a risk of failures caused by pressure and stress concentrated on the tibial post. Malalignment of the implant or variable loading applied to the implant are one of the major causes of the failure in posteriori stabilised TKR. The purpose of this study is to biomechanically analyse the effect of implant malalignment on the failure risk of the implant in posteriori stabilised TKR by estimating von-Mises stress on the implant.

Finite element models of a knee joint and a posteriori stabilised implant were developed from 1mm slices of CT images and 3D CAD software, respectively. The posterior stabilised implant consists of a femoral component, a tibial post, and a tibial tray. The finite element models of TKR for the neutral alignment case as well as the different malalignment cases (3° and 5° of valgus and varus angulations, 2° and 4° of anterior and posterior tilts, and 3° of external rotation) were developed. Then, the von-Mises stress, which is which was chosen as the fracture risk parameter, acting on the implant were analysed by using CAE software. Loading condition at the 40% of one whole gait cycle such as 2000N of compressive load, 25N of anterior-posterior load, and 6.5Nm of torque was applied to the TKR models.

The maximum von-Mises stresses were concentrated on the anterior region of the tibial post regardless of the oblique loadings. In the rotationally additional loading (3° of external rotation), excessive stresses occurred in the anterior medial and posterior lateral areas. The maximum stress was 18.3MPa in neutral position. The maximum stress increased by 10% in anterior tilt 2°, 15% in anterior tilt 4°, 25% in posterior tilt 2°, 54% in posterior tilt 4°, 116% in varus 3°, 262% in varus 5°, 318% in valgus 3°, 389% in valgus 5°, 6% in external rotation 3° compared with that in the neutral position case. In addition, 32.0MPa of maximum stress occurred on the posterior lateral area of the base component in rotationally additional loading.

The results showed that the implant malalignment could accelerate the stress concentration on the anterior region of the tibial post as in the result of clinical study. In the case of additional rotation, high stress concentration on the anterior medial and posterior lateral areas as well as on the tibial base surface could generate wear or fracture of tibial post. From the additional rotation case, we can expect that higher conformity implant will generate higher stress concentrations than lower conformity implant even though we did not compare the effect of conformity ratio on the stress concentration in the tibial polyethylene component. This study showed that careful consideration of the implant malalignment would be necessary to improve the clinical outcome in the posteriori stabilised TKR.

We developed a modified posterior approach that preserved the short external rotator muscles to prevent dislocation after THA or BHA. The present study aimed to evaluate the effectiveness of short external rotator preserving posterior(ERP) approach for bipolar hemiarthroplasty in treatment of femoral neck fractures in patients with neurologic disorders. Between March 2004 and February 2006, we performed 187 cementless bipolar hemiarthroplasties for displaced femoral neck fractures on 36 patients with neurologic disorders, who were operated on by ERP approach (Group 1) and 151 patients without neurologic deficits, who were operated on by conventional posterolateral approach (Group 2). We compared operation time, the amount of postoperative blood loss, the early postoperative complication rates, the dislocation rate within 1 year, and duration of hospital stay between two groups.

The amount of postoperative blood loss was significantly decreased in group 1(p < 0.01). There were no significant differences in mean operation time and early postoperative complication rate including wound problem, deep vein thrombosis or infection and duration of hospital stay. There was no dislocation after operation in group 1, but seven patient (4.6%) had dislocation in group 2. Nine patients (25.0%) died within postoperative 1 year in group 1 and twenty six patients (17.2%) died in group 2.

Cementless bipolar hemiarthroplasty through ERP approach provides a favorable outcome for treatment of displaced femoral neck fracture in patients with neurologic disorders who is considered as high risk of dislocation. Also, it decreases the postoperative blood loss and the needs of postoperative abduction brace.

The use of stem provides consistent component alignment with immediate stable fixation and protects grafted bone by reducing stress on metaphyseal area in revision total knee arthroplasty. One of major concern with use of stems involves stem tip pain in cementless diaphyseal engaging stem. The purpose of this study is to evaluate the effect of stem design and method of fixation on stem tip pain in revision total knee arthroplasty by finite element analysis.

3D finite element model of normal tibia was reconstructed from CT scan images of 26 year old male and the CAD model of revision total knee arthroplasty was developed using commercial software(CATIA^®, Dassault system, USA, version 8.20). The tibia component models were assembled based on conventional surgical procedure. The design changes of stem such as the length, diameter and slot were performed and methods of fixation including press fit and coefficient of friction was considered. The contact pressure and von-Mises stress around the stem and the micromotion at the interface were evaluated for a 2000 N of external load by finite element analysis to investigate the effect of stem design and methods of fixation on stem tip pain. The longer length and larger diameter press fit stem significantly increase the contact pressure & stress at the end of stem. The distal slot reduces the contact pressure & stress at the end of stem. Less displacement between tibial component and bone was noted in the increased coefficient of friction.

It would be better to avoid using press fit stem with extended length and larger diameter in revision total knee arthroplasty. More flexibility of stem tip would be favorable because of less concentration of stress. Stem fixation with higher coefficient of friction would be recommended for less displacement of tibial component. Stem with shorter length enough to engage proximal diaphysis, closer diameter of proximal canal and minimal press fit could be accepted to reduce stem tip pain if patient’s surgical anatomy such as bone loss and quality is tolerable in revision total knee arthroplasty.

Introduction: The purpose of this study was to evaluate the effectiveness of free vascularized fibular grafting (VFG) for the treatment of osteonecrosis of the femoral head.

Materials and Methods: We reviewed the results in a consecutive series of 115 hips (88 patients) who had undergone free VFG between July 1991 and February 1999. Among them, 46 hips (32 patients, 28 males and 4 females) were available with periodic follow-up of at least 5 years. The mean follow up period was 7.1 years (range, 5 to 13 years). An average age of patients was 37.6 years at the time of VFG. We performed survival analysis by the Kaplan-Meier method according to the stage, etiology, age of patients, size of involvement, and degree of collapse of the femoral head. We used the Harris hip score for clinical evaluation, and used plain radiographs and MRIs for radiological evaluation.

Results: The survival rates were 85% in Ficat stage 2a, 34.7% in stage 2b, and 76.2% in stage 3. Eleven hips were evaluated as failures of VFG of which 7 hips were converted to a prosthetic joint. Harris Hip Scores were 67.8 points preoperatively, and increased to 80.4 points postoperatively. Good or excellent results were found in 69.5% of hips clinically and 56.5% of the hips radiologically. Age and size of necrosis affected the postoperative Harris Hip Score significantly, but other factors did not.

Discussion: Free VFG for the early osteonecrosis of femoral head revealed satisfactory results with good survival of the joint and improvements in Harris Hip Scores.

One hundred twenty eight revision hip arthroplasties performed before Dec. 1995 using the Wagner self locking prosthesis were followed for five to ten years. Obviously, the shape of this revision prosthesis complements optimal primary stability; however, one must pay attention not to undersize the stem. Hence, the most significant feature contributing to this self-locking type is the accomplishment of appropriate canal filling when revision with optimum anchorage length of prosthetic component. According to the clinical and radiological data obtained from our midterm results, we confirm the excellent validity of this system for treating the advanced cases of bone resorption for revision. Obviously the classification based on the femoral bone deficiency by the AAOS and DGOT are well documented. Even though we agree with the recent concept of Bourne-Rorabeck that is worthwhile tending to revert to a simple, but practical classification based on the cancellous bone’s quality and the intactness of the cortical tube, we believe that four of Bourne-Rorabeck had better be five in order to be clearer. Furthermore, additional seven various cases series of recent for subsidence of the femoral components were included in this study.

We beieve that the only contraindication is conversion from arthrodesis when the patient has long standing history of heavy plate and screws because of undue discrepancy of the stress shielding. Lastly, it is very unusual, however, we describe the operative technique which Wagner stem is inevitably removed.

The purpose this prospective, randomized clinical trial was to determine if unilateral or bilateral simultaneous total hip arthroplasty procedures resulted in a differing incidence of fat embolization, degree of hemodynamic compromise, levels of hypoxemia or mental status changes. Also, the incidence of fat embolization was compared between the cemented and cementless total hip arthroplasty in the patients with a unilateral- and bilateral simultaneous total hip arthroplasty.

One hundred and fifty-six consecutive patients undergoing primary total hip arthroplasty were enrolled prospectively in the study after giving informed consent. The group consisted of fifty patients undergoing bilateral simultaneous total hip arthroplasty and 106 patients undergoing unilateral total hip arthroplasty. One hundred and three hips were cemented and 103 hips were cementless. To determine the hemodynamic changes and to detect the fat and bone marrow embolization, arterial and right atrial blood samples were obtained before implantation (baseline) and at one, three, five and ten minutes after implantation of the acetabular component. Also, arterial and right atrial blood samples were obtained at one, three, five and ten minutes after implantation of the femoral component. And then blood samples were obtained at twenty-four and forty-eight hours after the operation. Arterial blood pressure, right atrial pressure, arterial oxygen tension and carbon-dioxide tension were monitored at corresponding times. The presence of lipid was determined with oil red O fat stain and the presence of cellular contents of bone marrow was determined with Wright-Giemsa stain.

The incidence of fat embolism was not statistically different (P=1.000) between the patients with a bilateral total hip arthroplasty (twenty seven patients or 54 per cent) and the patients with a unilateral total hip arthroplasty (fifty-two patients or 49 per cent). In the semiquantitative analysis of fat globules in both groups, there was no tendency to have a higher number of fat globules in the bilateral group than in the unilateral group. Also, the incidence of bone marrow embolization was not statistically different (P=0.800) between the patients with a bilateral total hip arthroplasty (eight patients or 16 per cent) and the patients with a unilateral total hip arthroplasty (fourteen patients or 13 per cent). There was no statistical difference (P=0.800) in the incidence of the presence of fat globule between the cemented total hip (thirty-four patients or 34 per cent) and the cementless total hip arthroplasty (forty-seven patients or 44 per cent). Also, there was no statistical difference (P=0.627) in the incidence of the presence of bone marrow cells between the cemented total hip arthroplasty (thirteen patients or 13 per cent) and the cement-less total hip arthroplasty (twelve patients or 11 per cent). Four patients with positive bone marrow cells had neurological manifestation. All of these four patients developed diffuse encephalopathy with confusion and agitation for about twenty-four hours.

The present study confirmed that the incidence of fat and bone marrow embolization is similar in the patients with a bilateral simultaneous-and unilateral total hip arthroplasty as well as in the patients with cemented and cementless total hip arthroplasty. The patients with bone marrow cell emboli had a significantly lower arterial oxygen tension (p=0.022) and oxygen saturation (p=0.017) than the patients without bone marrow cell emboli. On the contrary, the number of fat globules did not affect the perioperative hemodynamic changes. Encephalopathy is related to the biochemical and/or mechanical changes by bone marrow cells.

Introduction: It is very important to evaluate the healing process in the femoral head after free vascularized fibular graft (VFG) in osteonecrosis of the femoral head (ONFH). Bone scintigraphy combined with a pinhole collimator, which is simple and not expensive, is used for very high resolution images of small organs, such as thyroid and certain skeletal regions. The purpose of this study was to assess the changes using pinhole bone scintigraphy in ONFH after VFG.

Materials and Methods: Changes of Tc-99m-HDP pinhole bone scintigraphy were analyzed in 22 cases of ONFH which were treated with VFG and had satisfactory results in patient evaluations at least 2 years after surgery. Harris Hip Scores were 90 points or more; and femoral head collapse was less than 2 mm.

Results: The results were: (1) At 1 week, the pinhole image showed no significant change in cold area but two linear RI uptakes corresponding to the fibular graft were noted. (2) At 3 months, localized hot uptakes just above the tip of the graft were observed in 17 cases (77.2%), and diffuse increased uptake surrounding the cold area were observed. (3) At 6 months, localized hot uptake were increased in size and replaced cold areas and delineated the shape of the superolateral aspect of the femoral head. (4) At 1 year, increased RI uptake of the superolateral aspect of the femoral head expanded medially in all cases. (5) After 2 years, cold areas faded away in 18 cases (81.8%).

Discussion: In conclusion, the authors believe that the Tc-99m-HDP pinhole bone scintigraphy is an excellent method to delineate the healing process in ONFH after VFG.

Introduction: A potential cause of premature loosening of the total hip prosthesis in patients with osteonecrosis is abnormal cancellous bone in the acetabulum and proximal femur. The purpose of this prospective study was to investigate the hypothesis that osteonecrosis is not confined to the femoral head but may extend proximally into acetabulum and distally into the proximal femoral bone. Also, the clinical and radiographic results of total hip arthroplasty with so-called third-generation cementless total hip prostheses were evaluated in sixty-three consecutive patients with osteonecrosis of the femoral head.

Materials and Methods: Twenty-five patients who had simultaneous bilateral total hip arthroplasty, and thirty-eight patients who had a unilateral total hip arthroplasty were included in the study. A cementless acetabular and femoral component were used in all hips. There were fifty-five men and eight women. The mean age at the time of the arthroplasty was 47 years (range, twenty-five to sixty-four years). We performed histological examination of the femoral heads and cancellous bone biopsies from five regions of the hip in patients undergoing total hip arthroplasty. Clinical and radiographic evaluations were performed preoperatively; at six weeks; at three, six, and twelve months; and yearly thereafter. The average duration of follow-up was 4.9 years.

Results: The majority of patients with idiopathic or alcohol induced osteonecrosis had normal bone in the acetabulum and proximal femur. The average Harris hip scores in the group treated with unilateral arthroplasty (96 points) and the group treated with bilateral arthroplasty (94 points) were similar at the time of final follow-up. No component had aseptic loosening. In one hip (1%), an acetabular component and a femoral component were revised because of infection. No hip had detectable wear or osteolysis in the acetabulum or in the proximal femur.

Conclusions: Normal or nearly normal cancellous bone in the acetabulum and proximal femur and advancements in surgical technique and better designs have greatly improved the intermediate-term survival of cementless total hip implants in young patients with osteonecrosis of the femoral head. An absence of osteolysis in these high-risk young patients is partly related to use of ceramic-on-ceramic bearing; solid fixation of the component; and short-term follow-up.

Introduction: The hypothesis that combined necrotic angle measurements using magnetic resonance imaging (MRI) scans predicts the subsequent risk of collapse of femoral head osteonecrosis was tested.

Materials and Methods: Thirty-seven hips with early-stage osteonecrosis in 33 consecutive patients were investigated. The arc of the necrosis was measured by the method of Kerboul et al using mid-coronal and mid-sagittal MRI scans of the femoral head instead of anteroposterior and lateral radiographs, and the two angles were added. Hips were classified into four categories based on the magnitude of the added angle; grade 1 (< 200°), grade 2 (200°–249°), grade 3 (250°–299°), and grade 4 (≥300°). After the initial evaluations, the hips were randomly assigned to a core-decompression group or conservatively-treated group. Patients underwent regular follow-up until femoral head collapse or for a minimum of five years.

Results: Seven hips in the grade 4 category and 16 hips in the grade 3 category developed femoral head collapse in 36 months; six out of nine hips in the grade 2 category, and none of five hips in the grade 1 category developed collapse (log rank test, p< 0.01). In a retrospective analysis, none of the four hips with a combined necrotic angle < 190° (low risk group) collapsed, whereas all 25 hips with a combined necrotic angle > 240° (high risk group) collapsed, and four (50%) of eight hips with a combined necrotic angle between 190° and 240° (moderate risk group) collapsed during the study.

Discussion: The Kerboul combined necrotic angle ascertained by MRI scans instead of radiographs is a major predictor of future collapse.

Introduction: The rate of failure of primary total hip arthroplasty in patients with osteonecrosis of the femoral head is higher than in patients with osteoarthritis. The purpose of this prospective study was to document the clinical and radiographic results of arthroplasty with so-called third generation cementing and the results of second generation cementless total hip arthroplasty in ninety-eight consecutive patients with osteonecrosis of the femoral head.

Materials and Methods: Fifty patients who had simultaneous bilateral total hip arthroplasties with a cemented stem in one hip and a cementless stem in the other and forty-eight patients who had unilateral total hip arthroplasties with a cementless stem were included in the study. A cementless acetabular component was used in all hips. The presumed cause of the osteonecrosis was ethanol abuse in fifty-seven patients, unknown in twenty-seven, fracture of the femoral neck in nine, and steroid use in five. There were eighty men and eighteen women. The mean age the time of the arthroplasty was 47 years (range, twenty-six to fifty-eight years). Clinical and radiographic evaluations were performed preoperatively, at six weeks, at three, six, and twelve months; yearly thereafter. The average duration of follow-up was 9.3 years.

Results: The average Harris hip scores in the group treated with unilateral arthroplasty (97 points) and the group treated with bilateral arthroplasty (94 points) were similar at the time of final follow-up. They were also similar between the group treated with cement (mean, 96 points) and that treated without cement (95 points). No component had aseptic loosening in either group. In one hip, a cemented femoral stem (2 %) and a cementless cup were revised because of infection. Two cementless stems (2%) were revised because of fracture of the proximal part of the femur with loosening of the stem. Annual wear of the polyethylene liner averaged 0.22 mm in the group treated with cement (a zirconia head) and 0.14 mm in the group treated without cement (a cobalt-chrome head). The prevalence of osteolysis in zones 1 and 7 of femur was 16 % in the femur was 16% in the group treated with cement and 24% in the group treated without cement.

Discussion: Advances in surgical technique and better designs have greatly improved the long-term survival of cemented and cementless implants in young patients with osteonecrosis of femoral head. Although there was no aseptic loosening of the components, the high rate of linear wear of the polyethylene liner and high rate of osteolysis in these high risk young patients remain challenging problems.

Introduction: Necrotic fatty marrow is yellow, thick, and turbid like pus and the fat cell is counted as white blood cell in automated cell counting. When necrotic fatty marrow leaks into the hip joint through a crack in the cartilage of the osteonecrotic femoral head, a misdiagnosis of pyogenic infection can be made. The authors report cases of osteonecrosis of the femoral head, in which a misdiagnosis of pyogenic infection was made during the operation.

Materials and Methods: Between September 1997 and December 2001, pyogenic arthritis was suspected during the operation in seven patients who were operated on due to advanced osteonecrosis of the femoral head. The markers of infection including white blood cell count, erythrocyte sedimentation rate, and C reactive protein in preoperative laboratory examination were normal in all of the seven patients. Total hip arthroplasty was scheduled for all patients. When the hip joint capsule was incised, joint fluid gushed out in all patients. The appearance, white blood cell count in automated cell counting, microscopic findings, and the results of culture of the joint fluid were evaluated.

Results: The joint fluid was yellow, thick and turbid like pus. A pyogenic arthritis was suspected and the joint fluid was sent to the laboratory for automated blood cell count, smear and culture. The count of white blood cells ranged from 5800 to 18000 in automated cell counting. No microorganism was identified on joint fluid smear. On microscopic cell counting using a hemocytometer, white blood cells were rarely seen and the majority of cells which were counted as white blood cells, were necrotic fat cell. Total hip arthroplasty was performed immediately after microscopic examination of the joint fluid. No microorganism was identified in cultures of the joint fluid. There was no evidence of infection after total hip arthroplasty at a minimum of two-year followup.

Discussion: When necrotic fatty marrow leaks into the hip joint, the joint fluid looks like pus and white blood cell counts of the joint fluid is increased in automated cell counting because fat cells are counted as white blood cells. In this situation, microscopic examination of the joint fluid is necessary. If the white blood cell count is not increased in microscopic cell counting, replacement arthroplasty can be performed without risk of infection.

Introduction: Some patients with collapsed osteonecrosis of the femoral head do not need any specific treatment because of mild symptoms or disability. The general features of this patient population were evaluated.

Materials and Methods: Forty-five cases of collapsed osteonecrosis of the femoral head in 38 patients were included in this study. These patients visited outpatient clinics for the first time from January 1996 to December 2002. In all cases, pain developed at least 3 years before the last follow-up, but no specific treatment was necessary. There were 27 men and 11 women. The mean age at the onset of pain was 41 years (range, 17 to 72 years). The duration from the onset of pain to the last follow-up was 36 to 167 months (mean, 73 months). The general and radiological features were evaluated.

Results: Risk factors included steroid therapy in 18, alcoholism in 16, other in 1 case; 10 cases had no risk factors (idiopathic). In 29 patients, both femoral heads were involved. Extent of the necrosis was 37 to 89 percent (mean, 62 percent). The amount of depression was 0.5 to 17 mm (mean, 2.2 mm).

Discussion: Steroid therapy was the most frequent risk factor in this patient population. In most cases, the amount of depression was less than 3 mm. Most patients remembered that the pain was most severe at its onset and improved over the next several months.

Introduction: Stress fracture of the femoral head is a rare condition and usually occurs in people with poor bone quality as an insufficiency fracture. We evaluated the clinical aspects of subchondral fatigue fractures of the femoral head (SFFFH) that occurred in young healthy people.

Materials and Methods: Between January 1998 and November 2001, 7 cases of SFFFH in 5 patients were treated. The characteristics of this condition were ascertained by assessing the clinical course and findings of radiographs, bone scintigrams, and magnetic resonance (MR) images.

Results: All patients were male military recruits in their early twenties. Pain developed within 6 months after recruitment. On initial radiographs, definite abnormal findings were observed in 3 hips of 2 patients. In 2 of them, the femoral head was markedly collapsed. In the other 4 hips, no definite abnormal findings were noticed. The bone scintigrams showed increased radionuclide uptake in the femoral head. MR images demonstrated localized abnormal signal intensity areas (bone marrow edema pattern) in the femoral head. In all cases, MR crescent signs were observed. In the cases without collapse of the femoral head, the pain decreased gradually and disappeared completely in 6 months with improving findings on follow-up MR images. The collapsed cases needed surgical treatment: total hip arthroplasty or strut iliac bone grafting.

Discussion: When a military recruit or an athlete is complaining of hip pain, a high index of suspicion for SFFFH is necessary to prevent the collapse of the femoral head. Bone scintigrams are of great value as a screening tool. Osteonecrosis of the femoral head can be differentiated by the findings on MR images.

Introduction: Osteonecrosis of the femoral head (ONFH), a disease of unknown pathogenesis usually involves subchondral bone and shows an improper repair process. The temperature of the subchondral bone of the femoral head was found to increase by a maximum of 2.5 °C in a simulation of walking performed in cadavers. A greater increase in the temperature is expected in the necrotic bone in ONFH because there is no heat dissipation by blood flow. The purpose of this study was to confirm the possibility that hyperthermia is a cause of the poor regeneration of the necrotic bone in ONFH.

Materials and Methods: Necrotic and living bone extracts were prepared from the femoral heads of 4 ONFH patients. Human umbilical vein endothelial cells (HUVECs) were cultured with endothelial cell growth media-2 (EGM-2), EGM-2 supplemented with necrotic bone extracts, and EGM-2 supplemented with living bone extracts. HUVECs were also cultured at temperatures of 40, 40.5, 41 and 42 °C, while controls were maintained at 37 °C. Viable cell numbers of HUVECs were determined by MTS assay at days 1, 4, 6, 8, and 11.

Results: The number of viable cells decreased in hyperthermic conditions of 40.5 to 42 °C (p< 0.05). The addition of living bone extracts induced a significant increase in the number of viable cells during the culture periods (p< 0.05). Necrotic bone extracts did not induce such a significant increase.

Discussion: Local subchondral hyperthermia might be a possible cause of the poor regeneration of the necrotic area in ONFH.

We report our early Boston experience with the technique of Ganz, et al., for surgical dislocation of the hip, which provides a safe, powerful approach to certain major intraarticular hip problems.

Materials and Methods: Forty-seven hips with various mechanical disorders have been treated using the Ganz technique of trochanteric flip osteotomy and anterior dislocation (JBJS 83-B: 1119-1124, 2001). Diagnoses include slipped epiphysis 14, Perthes 12, aspherical head/ anterior offset 12, dysplasia 14, multiple exostoses 2, other 3.Seven patients had simultaneous femoral oste-otomies; four had subcapital osteotomies for epiphys-iolysis. All patients had pain and limitation of motion preoperatively, and more than fifty percent had severe deformity and/or some arthrosis. Follow-up was six months to five years. Ages at surgery were eight to forty-eight years (mean twenty years).

Results: The variety of pathologies render objective analysis difficult, though all patients reported greatly reduced pain and increased motion post operatively. Only five patients were totally pain free and had objectively totally normal hips. No patient felt unimproved. No patient had radiographic signs of osteonecrosis.

Conclusion: Paralleling the Bernese experience of more than eight hundred cases, we find the Bernese technique of surgical dislocation to be a safe, effective tool for treating intra-articular hip pathology, increasing treatment possibilities for hip joint preservation. We anticipate greatly expanding its use in the future.

To evaluate the results critically of cemented total hip arthroplasty using a fourth generation cement technique and polished femoral stem, a prospective study was performed in patients under 50 years of age who underwent primary total hip arthroplasty. 55 patients (64 hips) were enrolled in the study (43 were male and 12 were female). Average age of patients was 43.4 years (21–50 years). Elite plus stems (DePuy, Leeds, UK) were cemented and cementless Duraloc cups (DePuy, Warsaw, IN.) were implanted in all hips. 22 mm zirconia femoral head (DePuy, Leeds UK) was used in all hips. All surgeries were performed by one surgeon (YHK). The diagnosis was osteonecrosis (43 hips or 67%), osteoarthritis (5 hips or 4%), O.A. 2° to childhood T.B. or pyogenic arthritis (4 hips or 6%), R.A, (3 hips or 5%), DDH (2 hips or 3%) and others (7 hips or 11%). The average F.U. was 7.2 years (6–8 years). The 4th generation cement technique was utilized including: medullary plug, pulsatile lavage, vaccum mixing of Simplex P cement; cement gun, distal centralizer and proximal rubber seal to pressurize cement. Thigh pain was evaluated using a visual analog scale (10 points). Clinical (Harris hip score) and x-ray follow-up was performed at 6 weeks, 3 months, 6 months, 1 year and then annually. Cementing technique was graded. Abductor moment arm, femoral offset, neck and limb length, center of rotation of hips, cup angle and anteversion were measured in all hips. Linear and volumetric wear were measured by software program. Osteolysis was identified. There was no aseptic loosening or subsidence of components. One hip was revised due to late infection. Incidence of thigh pain was 11% (7 hips). All thigh pain disappeared at 1 year postoperatively. Preoperative Harris hip score was 47.2 (7–67) points and 92.2 (81–100) points at the final F.U. Femoral cementing was classified as grade A in 50 hips (78%), grade B in 6 hips (9%), and grade C1 in 8 hips (13%). There was no cases in grades C2 and D. All bones had type A femoral bone. The average linear wear and annual rate were 1.25 and 0.21 mm, respectively. The average volumetric wear was 473.48 mm3. There was statistically significant relationship between the liner wear, age (under 40), male patient, and the cup angle. Yet there was no statistical relationship between the wear and Dx., wt., hip score, R-O-M, anteversion, anbductor moment arm, femoral offset, neck and limb length and center of rotation of hip. Osteolysis was identified in zone 7A in 6 hips (9%). No hip had distal osteolysis. Advanced cementing technique, polished improved stem design, strong trabecular bone, and utilizing a smaller head and thick polys greatly improved the mid-term survival of the implants in these young patients. Good cementing technique eliminated distal osteolysis and markedly reduced the proximal osteolysis. Yet high linear and volumetric wear of polyethylene liner remains to be a challenging problem.

To determine the results critically of cementless third generation prosthesis (proximal fit, porous coated, and tapered distal stem), a prospective study was performed only in Charnley class A patients under 50 years of age who underwent primary total hip arthroplasty. 50 patients (50 hips) were included in study (37 were male and 13 were female). Average age of patients was 45.4 years (26–50 years). IPS(Immediate Postoperative Stability) stems (DePuy, Leeds, UK) were implanted in all hips. Cementless Duraloc cups (DePuy, warsaw, IN.) were used in all hips. 22 mm zirconia femoral head was used in all hips. All surgeries were performed by one surgeon (YHK). The redominant Dx. was osteonecrosis (30 hips or 60%), O.A. 2° to childhood T.B. or pyogenic arthritis (8 hips or 16%) and others (12 hips or 24%). The average F.U. was 6.3 years (5–7 years). Thigh pain was evaluated using a visual analog scale (10 points). Clinical (Harris hip score) and x-ray follow-up was performed at 6 weeks, 3 months, 6 months, 1 year and then annually. Linear and volumetric wear were measured by software program. Abductor moment arm, femoral offset, neck and limb length, center of rotation of hips, cup angle and anteversion were measured and the results were compared between normal and operated hips. All hips had satisfactory fit in A-P and lateral planes. There was no aseptic loosening or subsidence of components. Incidence of thigh pain was 14% (7 of 50 hips). All thigh pain disappeared at 3 years postoperatively. Preoperative Harris hip score was 52.3 (7–64) points and 92.9 (80–100) points at the final F.U. The values of abductor moment arm, femoral offset, neck and limb length, center of rotation of hips, cup angle and anteversion of operated hips were comparable to normal unoperated hips. The average linear wear and annual wear rate were 1.25 and 0.21 mm, respectively. The average volumetric wear was 473.48 mm3. There was statistically significant relationship between the liner wear, age (under 40), male patient, and the cup angle. Yet there was no statistical relationship between the wear and Dx., wt., hip score, R-O-M, anteversion, abductor moment arm, femoral offset, neck and limb length and center of rotation of hip. Osteolysis was identified in zones 1A and 7A in 4 hips (8%). No hip had distal osteolysis. Close fit cementless stem in coronal and saggital planes without having distal stem fixation were proved to have an excellent mechanical fixation and provided favorable mechanical loading. Close fit in the proximal canal with a circumferential porous coating reduced the incidence of osteolysis. Factors contributing to good results in this young patient group are improved design of the prosthesis, improved surgical technique, strong trabecular bone and the use of smaller femoral head and thick polys. Although there was no aseptic loosening of the hip, high incidence of linear and volumetric wear of polyethylene liner in these young patients remains to be a challenging problem.

Objectives: To assess the effectiveness of the two different types of C-D instrumentation constructs on the unstable thoracolumbar and lumbar spine fractures.

Material and Method: 45 fractures in 42 patients(age range, 18 to 57 years) were treated with C-D instrumentation and posterolateral fusion, and were followed up over 2 years(26±72 months). The level of injuries were T12 in 6 cases, L1 in 15, L2 in 12, L3 in 3, L3-4 in 6, and L4-5 in 3. The fracture types were bursting in 21, flexion-distraction in 15, fracture-dislocation in 9. Three had both L1 flexion-distraction and L3 bursting fractures. 9 had incomplete paralysis. Vertebral height and kyphosis angle were measured. All fractures were reduced by normally contoured rod handling without distraction or compression, and the vertebrae one above and one below the fractured spine were fused posterolaterally. 9 had posterior decompression surgery including reduction of retropulsed fragment. In 21 cases long rodding(group-I : over three level stabilization) and in 18 cases short rodding(group-II : one above and below) were performed.

Results: Fracture consolidation was achieved at 6.5 months (5±10 months). Overall fusion rate was 78.6%: 75% in Group-I and 83.3% in Group-II. In group-I average kyphosis at preop, immediate and fi nal postop follow-up were 20.3°, 7° and 11.4°, respectively, while in group-II those were 14.7°, 2.4° and 8.4°, respectively. The losses of correction in group-I and group-II were 4.4° and 5.7°. In group-I and group-II anterior body height losses at preop, immediate postop and fi nal follow-up were 45.6%, 14.6%, 17.1% and 40.3%, 15.8%, 23.7%, respecitvely. Complications were : screw breakage in group-I and II were 3 and 6 cases : plug dislodgement in 3 cases of group-I, and hook dislodgement in 3 of group-II.

Conclusion: Long rodding and posterior fusion is preferably recommended to minimize the loss of reduction.