We studied prospectively the long-term results of the Charnley Elite-Plus femoral stem in 184 consecutive young patients (194 hips). There were 130 men and 54 women with a mean age of 49.1 years (21 to 60). The predominant diagnosis was osteonecrosis of the femoral head (63.6%, 117 patients). Clinical and radiological evaluation was undertaken at each follow-up. The mean follow-up was 11.2 years (10 to 12).

The mean pre-operative Harris hip score was 43.4 (12 to 49) which improved to 91 (59 to 100) at the final follow-up. The survival of the femoral stem at 12 years was 99% with revision as the end-point. The mean annual linear wear of the polyethylene liner was 0.17 mm (0.13 to 0.22). The prevalence of acetabular osteolysis was 10.8% (21 hips) and osteolysis of the calcar femorale 12.9% (25 hips).

A third-generation cementing technique, accurate alignment of the stem and the use of a 22 mm zirconia head were important factors in the prevention of aseptic loosening of the Elite Plus femoral stem in these high-risk young patients.

Our aim in this prospective study was to compare the bone mineral density (BMD) around cementless acetabular and femoral components which were identical in geometry and had the same alumina modular femoral head, but differed in regard to the material of the acetabular liners (alumina ceramic or polyethylene) in 50 patients (100 hips) who had undergone bilateral simultaneous primary total hip replacement. Dual energy X-ray absorptiometry scans of the pelvis and proximal femur were obtained at one week, at one year, and annually thereafter during the five-year period of the study.

At the final follow-up, the mean BMD had increased significantly in each group in acetabular zone I of DeLee and Charnley (20% (15% to 26%), p = 0.003), but had decreased in acetabular zone II (24% (18% to 36%) in the alumina group and 25% (17% to 31%) in the polyethylene group, p = 0.001). There was an increase in the mean BMD in zone III of 2% (0.8% to 3.2%) in the alumina group and 1% (0.6% to 2.2%) in the polyethylene group (p = 0.315). There was a decrease in the mean BMD in the calcar region (femoral zone 7) of 15% (8% to 24%) in the alumina group and 14% (6% to 23%) in the polyethylene group (p < 0.001). The mean bone loss in femoral zone 1 of Gruen et al was 2% (1.1% to 3.1%) in the alumina group and 3% (1.3% to 4.3%) in the polyethylene group (p = 0.03), and in femoral zone 6, the mean bone loss was 15% (9% to 27%) in the alumina group and 14% (11% to 29%) in the polyethylene group compared with baseline values. There was an increase in the mean BMD on the final scans in femoral zones 2 (p = 0.04), 3 (p = 0.04), 4 (p = 0.12) and 5 (p = 0.049) in both groups.

There was thus no significant difference in the bone remodelling of the acetabulum and femur five years after total hip replacement in those two groups where the only difference was in the acetabular liner.

Introduction: A hypothesis that combined necrotic angle measurement using 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 a non-operatively-treated group. Patients underwent regular follow-up until femoral head collapse or for a minimum of five years.

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

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: Hyperlipidemia is related to hypercoagulability and hypofibrinolysis, which may cause a tendency to intravascular thrombosis and result in osteonecrosis (ON). Recently PPARs were confirmed to induce adipocyte differentiation, and fatty acids were identified as the transcriptional effectors for PPARs, which may cause the hyperlipidemia and fatty marrow. The aim of this study was to identify whether the adipocytic differentiation was increased in the bone marrow obtained from the femoral head in patients with osteonecrosis.

Materials and Methods: A lipid profile (cholesterol, triglyceride, LDL, and free fatty acid) was performed for patients with osteonecrosis of the femoral head. The PPARγ2 expression was checked as to whether the mesenchymal stem cells differentiate toward adipocytes rather than osteogenic cells. RT-PCRs were completed using the bone marrow stroma cells obtained during THA from 11 patients with osteonecrosis and 9 control patients. As not all of alcoholics and steroid users develop osteonecrosis, genetic differences may relate to susceptibility to the osteonecrosis. Therefore, we determined the polymorphism of the PPARγ2 gene for 34 osteonecrosis patients and 76 controls.

Results: Among 89 cases of osteonecrosis, increased free fatty acid (above 580mg%) was the most frequent finding (40.8%), and triglyceride was the next (29.6%). Cholesterol was increased in only 9.0%. Seven of the osteonecrosis cases (63.6%) and 4 of the control cases (44.4%) expressed PPARγ2. Pro/Ala (C/G) polymorphism was found in seven (20.6%) ON cases and four control cases (5.3%), and Ala/Ala (G/G) polymorphism was found in only 1 case in the control group. The numbers of patients with elevated triglyceride among osteonecrosis were much higher (71.4%) in polymorphism (C/G) than osteonecrosis (21.5%) without polymorphism.

Discussion: In conclusion, hyperlipidemia and higher expression of the PPARγ2 were found in ON, and Pro/Ala PPARγ2 polymorphism was more common in ON.

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: It is desirable to delay or avoid total joint replacement in young patients who have osteonecrosis of femoral head. There are some head preserving surgical procedures that attempt this including osteotomy, core decompression, and bone grafting. The vascularized fibular graft has been reported to be a reliable procedure, but unfortunately it has donor site morbidity and is considered technically demanding. Therefore, materials have been developed to substitute for structural fibular graft. New trabecular metal has been developed to be used for osteonecrosis of femoral head. The purpose of this study was to review the clinical outcomes of trabecular metal as a treatment intervention method for osteonecrosis of the femoral head.

Materials and Methods: Seven patients (8 hips) with osteonecrosis of femoral head received core decompression and a trabecular metal implant, beginning in March 2003. The stage of osteonecrosis was I or II according to Ficat and Arlet except for one case (stage III). The procedure consists of a core decompression and insertion of trabecular metal rod (porous tantalum, Zimmer Inc./ Implex Incorporation). A Harris Hip Score was obtained pre-operatively, and at three and at three and six months. Radiographic data was collected at the same time of clinical follow-up.

Results: All 7 patients are doing well. Radiographic review shows no evidence of further femoral head collapse.

Discussion: Even though this is short term follow-up, the authors propose that the use of trabecular metal in osteonecrosis patients is simple, safe, and effective for the salvage of the hip.

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.

There are many reports concerning the aetiology and prophylaxis of deep-vein thrombosis (DVT) but little is known about its natural history. The purpose of our study was to identify the incidence and site of DVT, the risk factors for pulmonary embolism and the natural history of DVT after total hip replacement (THR) in patients who do not receive any form of prophylactic or therapeutic treatment for DVT.

Two hundred patients who had a primary THR were included: 100 had one-staged bilateral THR and 100 had unilateral THR and 150 implants were cemented and 150 cementless. Coagulation assays, a full blood count, blood typing and serum chemical profile tests were performed for all patients on three separate occasions. Bilateral simultaneous or unilateral venograms were performed on the sixth or seventh postoperative day and perfusion lung scans preoperatively and on the seventh or eighth postoperative day. Further venograms were performed in all patients who had thrombi six months later.

In the patients with bilateral THR, 52 (26%) venograms were positive for thrombi, while in the patients with unilateral THR 20 (20%) were positive (p = 0.89). In the patients with a cemented THR, 31 venograms (20.7%) were positive for thrombi, while in those with a cementless THR 41 (27.3%) were positive (p = 0.654). Further venograms in all 72 patients who had thrombi at six months after operation showed that they resolved completely and spontaneously regardless of their site and size. No patients had symptoms of pulmonary emboli and none were seen on the perfusion lung scans. Two patients died from unrelated causes.

Although the prevailing opinion is that patients with proximal venous thrombosis should be treated with anticoagulants, our study has shown that all thrombi regardless of their site and size resolve spontaneously without associated pulmonary embolism.

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.

We have evaluated prospectively the incidence and location of deep-vein thrombosis (DVT), the risk factors for pulmonary embolism, and the natural history of thrombosis after total knee replacement (TKR) in patients who did not receive prophylactic or therapeutic treatment for DVT.

We studied 227 patients who underwent primary TKR; 116 had one-stage bilateral and 111 unilateral procedures. Coagulation assays, the full blood count and blood typing tests for the serum chemical profile were undertaken in all patients on three separate occasions. Bilateral simultaneous or unilateral venograms were carried out at six or seven days after operation. Perfusion lung scanning was undertaken before and at seven or eight days after operation. Bilateral simultaneous or unilateral venograms were repeated six months after operation in all patients who had thrombi.

In the 116 patients with a bilateral replacement, 97 of 232 venograms (41.8%) were positive for fresh thrombi while there were 46 positive venograms (41.4%) in the 111 patients with a unilateral replacement (p = 1.000). Of the 116 venograms in knees with a cemented replacement, 45 (38.8%) were positive for thrombi while 52 of the 116 venograms (44.8%) were positive in those with a cementless replacement (p = 0.675). Further venograms at six months after operation in all 143 limbs which had thrombi showed that all had completely resolved regardless of the size or location. No pulmonary embolism occurred as shown by negative perfusion lung scans and the absence of symptoms.

Although the current prevailing opinion is that patients with thrombosis in the proximal veins should receive anticoagulant treatment, our study has shown that all thrombi regardless of their size or location resolved without causing pulmonary embolism.

We describe the results of total knee arthroplasty (TKA) undertaken for severe, neurosyphilitic Charcot arthropathy in ten patients (19 knees). A cemented condylar, constrained prosthesis was implanted in all but two knees. The mean follow-up was 5.2 years (5 to 6). The mean knee score before operation was 36.5 points (30 to 42) which improved to 76 points (58 to 90) after operation as judged by the Hospital for Special Surgery score. At final follow-up three knees (16%) had aseptic loosening which required salvage by an arthrodesis, six (31%) were functioning poorly and ten (53%) were satisfactory.

We conclude that although Charcot arthropathy is not an absolute contraindication to total knee replacement, there is a high incidence of serious complications.

We have reviewed 70 patients with bilateral simultaneous total hip arthroplasties to determine the rate of failure and to compare polyethylene wear and osteolysis between an implant with a cobalt-chrome head and Hylamer liner with that of a zirconia head and Hylamer liner. The mean thickness of the polyethylene liner was 11.0 mm (8.8 to 12.2) in the hip with a zirconia head and 10.7 mm (8.8 to 12.2) in that with a cobalt-chrome head.

At follow-up at 6.4 years no acetabular or femoral component had been revised for aseptic loosening and no acetabular or femoral component was loose according to radiological criteria in both the cemented and cementless groups. The mean rate of linear wear and annual wear rate were highest in the 22 mm zirconia femoral head (1.25 mm (SD 1.05) and 0.21 mm (SD 0.18), respectively) and lowest in the 22 mm cobalt-chrome femoral head (0.70 mm (SD 0.39) and 0.12 mm (SD 0.07), respectively). The mean volumetric wear was highest in the 28 mm zirconia femoral head (730.79 mm³) and lowest in the 22 mm cobalt-chrome femoral head (264.67 mm³), but if the results were compared by size of the femoral head and type of material there was no statistical difference (p > 0.05). Sequential measurements of annual wear showed that the zirconia femoral head had a relatively higher rate of penetration than the cobalt-chrome head over the first three years; thereafter the rate of wear was reduced and compared favourably with that of cobalt-chrome heads.

There was a statistically significant relationship between the wear of the polyethylene liner and the age of the patient, male gender and the degree of abduction angle of the cup, but not diagnosis, weight, hip score, range of movement, or amount of anteversion. Osteolysis was identified on both sides of the acetabulum in six patients (9%). Of 12 hips with acetabular osteolysis, six had a 28 mm cobalt-chrome femoral head and the remaining six a 28 mm zirconia head. Osteolysis was observed in zones 1A and 7A of the femur in two hips (3%) with a 28 mm zirconia head (cemented hip) and in four (6%) with a 28 mm cobalt-chrome femoral head (cementless hip).

Our findings suggest that although the performance of a zirconia femoral head with a Hylamer liner was not statistically different from that of a cobalt-chrome femoral head and Hylamer liner, there was a trend for the zirconia head to be worse than the cobalt-chrome femoral head.

Six pairs of human cadaver femora were divided equally into two groups one of which received a non-cemented reference implant and the other a very short non-dependent experimental implant. Thirteen strain-gauge rosettes were attached to the external surface of each specimen and, during application of combined axial and torsional loads to the femoral head, the strains in both groups were measured.

After the insertion of a non-cemented femoral component, the normal pattern of a progressive proximal-to-distal increase in strains was similar to that in the intact femur and the strain was maximum near the tip of the prosthesis. On the medial and lateral aspects of the proximal femur, the strains were greatly reduced after implantation of both types of implant. The pattern and magnitude of the strains, however, were closer to those in the intact femur after insertion of the experimental stem than in the reference stem. On the anterior and posterior aspects of the femur, implantation of both types of stem led to increased principal strains E1, E2 and E3. This was most pronounced for the experimental stem.

Our findings suggest that the experimental stem, which has a more anatomical proximal fit without having a distal stem and cortex contact, can provide immediate postoperative stability. Pure proximal loading by the experimental stem in the metaphysis, reduction of excessive bending stiffness of the stem by tapering and the absence of contact between the stem and the distal cortex may reduce stress shielding, bone resorption and thigh pain.

The rate of success of transtrochanteric rotational osteotomy for osteonecrosis of the femoral head may be improved if patients are preselected using MRI. We have used three criteria for selection for osteotomy (i) minor collapse of the infarcted area, loss of congruity or the crescent sign, without narrowing of the joint space or acetabular involvement (ii) patients younger than 55 years and with a painful hip (iii) patients with an intact area constituting an arc of more than 120° between the central vertical line of the femoral head and the posterior or anterior margin of the necrotic portion as seen on a midsagittal MRI. Seventeen patients were selected, with a follow-up of more than 42 months. A bone scan four weeks after operation showed adequate perfusion of the proximal segment in all hips. The hip score of Merle d’Aubigné et al improved from 13.5 points before operation to 17.2 points at the latest follow-up. Further collapse of the femoral head did not occur.

The use of MRI instead of plain radiographs for the selection of patients has improved the success rate of transtrochanteric rotational osteotomy.

We reviewed 26 patients who had had internal fixation of an open intra-articular supracondylar fracture of the humerus. All operations were performed using a posterior approach, 13 with a triceps split and 13 with an olecranon osteotomy. The outcome was assessed by means of the Mayo Elbow score, the Disability of the Arm, Shoulder and Hand (DASH) score and the SF-36 Physical Function score. Patients with an olecranon osteotomy had less good results.

Between June 1993 and December 1994, we performed total knee arthroplasty (TKA) on 27 knees in 24 patients with spontaneous bony ankylosis in severe flexion. The mean age at operation was 43.5 years (30 to 60). No patient had preoperative pain. Three were unable to walk and 21 could manage less than five blocks. The mean duration of the ankylosis was 18.7 years (13 to 25) and its mean position was 105° flexion (75 to 135).

The preoperative Hospital for Special Surgery Knee Score of 60 points was improved to 87 at the final follow-up three to five years later. All knees were free from pain. The mean range of active flexion in 24 knees was 97° (78 to 115) and the mean arc of movement 91° (78 to 98). The mean fixed flexion deformity was 6° (0 to 25) and the extension lag 8° (0 to 25). Angular deformity was corrected to between 0° and 10° of valgus. Four patients were able to walk one block and 20 five to seven blocks. Thirteen knees (48%) showed some necrosis at the skin edge; one knee required arthrodesis and another resection arthroplasty. One had a recurrence of tuberculous infection requiring arthrodesis. One patient had a rupture of the quadriceps tendon. To date no prosthesis has required revision for loosening. Radiolucency of 1 mm or less about the tibial prosthesis was observed at follow-up in four of the 24 knees.

Our results have shown that one-stage TKA and skeletal traction after operation can achieve correction of severe flexion deformity of the knee with marked improvement in the function and quality of life.