Bilateral sequential total knee replacement with a Zimmer NexGen prosthesis (Zimmer, Warsaw, Indiana) was carried out in 30 patients. One knee was replaced using a robotic-assisted implantation (ROBOT side) and the other conventionally manual implantation (CON side). There were 30 women with a mean age of 67.8 years (50 to 80).

Pre-operative and post-operative scores were obtained for all patients using the Knee Society (KSS) and The Hospital for Special Surgery (HSS) systems. Full-length standing anteroposterior radiographs, including the femoral head and ankle, and lateral and skyline patellar views were taken pre- and post-operatively and were assessed for the mechanical axis and the position of the components. The mean follow-up was 2.3 years (2 to 3).

The operating and tourniquet times were longer in the ROBOT side (p < 0.001). There were no significant pre- or post-operative differences between the knee scores of the two groups (p = 0.288 and p = 0.429, respectively). Mean mechanical axes were not significantly different in the two groups (p = 0.815). However, there were more outliers in the CON side (8) than in the ROBOT side (1) (p = 0.013). In the coronal alignment of the femoral component, the CON side (8) had more outliers than the ROBOT side (1) (p = 0.013) and the CON side (3) also had more outliers than the ROBOT side (0) in the sagittal alignment of the femoral component (p = 0.043). In terms of outliers for coronal and sagittal tibial alignment, the CON side (1 and 4) had more outliers than the ROBOT side (0 and 2).

In this series robotic-assisted total knee replacement resulted in more accurate orientation and alignment of the components than that achieved by conventional total knee replacement.

Introduction: The aim of this study was to report the clinical and radiographic results of a modified transtrochanteric rotational osteotomy (MTRO) for osteonecrosis of the femoral head.

Materials and Methods: A MTRO was performed in 43 hips with osteonecrosis. The mean age was 34 years (range, 20 to 51 years). According to the classification system of the Association Research Circulation Osseous, 17 hips were stage 2 and 26 stage 3. We performed simple MTRO in 15 cases, combination of MTRO and simple bone grafting in 3 cases, and a combination of MTRO and muscle pedicle bone grafting in 25 cases.

Results: At a mean 37 months after surgery, there was further collapse of the femoral head in 3 hips. All these lesions were in the lateral location, and 2 were large lesions. One of these 3 hips was converted to a total hip arthroplasty. The overall survival rate was 93 percent. Among the surviving 40 cases, excellent results were obtained in 26 hips, good results in 11, and fair results in 3 hips.

Conclusion: A MTRO is an effective method for delaying the progression of collapse in the treatment of osteonecrosis of the femoral head in selected cases.

Introduction: To compare the effect of complete and incomplete osteotomy of the medial cortex of proximal tibia in closing wedge high tibial osteotomy

Materials and methods: Total 153 cases of high tibial osteotomy (average age: 59.7 years) were divided into two groups: Group I; 57 cases of incomplete osteotomy of medial cortex and Group II; 96 cases of complete osteotomy. All osteotomies were fixed with 90¨¬angled blade plate. Two groups were evaluated to verify the difference of complete and incomplete osteotomies regarding the radiological changes of the mechanical axes.

Results: After average 3.5 years of follow-up (minimum 2.4 years), Group I showed recurrence of varus in 21 cases (36.8%) with average 10¨¬ correction loss, while Group II showed recurrence of varus in 11 cases (11.5%) with average 3¨¬ correction loss(P< 0.05). The blade plate fixation of high tibial osteotomy was not rigid enough to prevent loss of correction in case of osteoporosis of the proximal tibia as far as the medial cortex was left intact.

Conclusion: Authors recommend complete osteotomy of the medial cortex in closing wedge high tibial osteotomy in order to maintain the valgus correction by avoiding the spring effect of medial cortex. Blade plate fixation also provides more physiological tibiofemoral axis for future total knee surgery by lateral translation of the distal tibia after complete osteotomy of medial cortex.

Introduction: The purpose of this study was to evaluate the result of treatment of the infected total knee arthroplasty by two-stage revision using antibiotics-impregnated cement spacer and beads.

Materials and methods: Out of 56 total knee arthroplasty revisions, 26 revisions were performed for infected total knee arthroplasties between 1985 and 1996. Two cases of infected total knee arthroplasties were treated by immediate replacement and four cases by arthrodesis. Twenty infected total knee arthroplasties had been revised by two-stage revision and followed-up for 38.6 months in average (range, 18–105 months). They were nine male and eleven female patients of 61.6 years old in average. The primary cause of arthroplasty was osteoarthritis in all. Infection was diagnosed by physical finding, radiography, preoperative aspiration, culture of the pus from draining sinus and culture of surgical specimen. Twelve cases revealed positive growth of causative bacteria, while eight were not identified. The protocol for two-stage revision began with the removal of infected implants and cement. The surrounding bony and soft tissue were thoroughly debrided and cleaned. The dead space between femur and t

Results: Two-stage revision was successful in nineteen cases. One case revealed the recurrence of infection eleven months after reimplantation and underwent the repetition of the same two-stage procedure. At the final follow-up, the average Hospital for Special Surgery score was 81.1 points, the average Knee Society knee score was 78.6 points and the average function score was 76.7 points. Patients could regain average 105 degrees of knee flexion.

Conclusion: The result of two-stage revision for infected total knee arthroplasty is satisfactory, showing that this can be the method of choice for infection treatment and functional restoration. This procedure using antibiotics-impregnated cement spacer and beads can control infection and improve functional results.

The purpose of current study was to describe the results of complex acetabular fractures treated with open reduction using transtrochanteric approach and arthrotomy of the hip joint. Fourteen consecutive patients with both column fractures of the acetabulum were treated with open reduction and internal fixation. All patients had various associated injuries. Among them, one patient had pelvic abscess associated with traumatic bowel perforation. The acetabulum was approached with Y-shaped triradiate incision, osteotomy of the greater trochanter, and arthrotomy of the hip joint. During the operation, the osteochondral fragments were removed and torn labrum was resected. In 6 patients the fracture was fixed with reconstruction plates and in 8 patients the fracture was fixed with plates and wires. All the patients were followed for an average of 4.6 years(range, 2–8 years). The clinical evaluation was done by the method of Merle d’Aubigne. All the fractures and all osteotomies united at the latest follow up. One patient had delayed hematogenous infection at 5.5 years after the operation. Although myositis ossificans developed in 3 patients it was neither progressive after 1 year nor associated with significant limitation of hip motion. Four patients had narrowing of the hip joint space. Three of them had osteophyte formation around the femoral head. No femoral head necrosis was observed. Eleven patients had excellent or good outcomes in clinical score. No patient underwent total hip arthroplasty. This extensile approach allowed a good exposure of the fracture site, more accurate reduction, and easier fixation of fracture fragments. It also allowed the removal of osteochondral fragments and the resection of torn labrum. However, 3 patients showed osteophyte formation around the femoral head. We are concerned about the further progression of the osteophyte and its clinical implication.

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.

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.

Stable fixation after a corrective supracondylar osteotomy in adults is difficult because of the irregularity of the area of bony contact, displacement of the fragments, the predominance of cortical bone, and the need for early mobilisation.

We have used the Ilizarov apparatus for fixation in 15 patients who were treated by complex osteotomies with displacement of fragments for cubitus varus or valgus. Most patients with cubitus varus required medial displacement with rotation of the distal fragment. Those with cubitus valgus required lateral shift of the distal fragment to reduce the medial prominence of the elbow that would otherwise result.

All osteotomies united within the expected time without loss of correction, despite early mobilisation. Complications related to the fixation were few and had resolved at the long-term follow-up.

We performed a randomised trial on 37 hips (33 patients) with early-stage osteonecrosis (ON). After the initial clinical evaluation, including plain radiography and MRI, 18 hips were randomly assigned to a core-decompression group and 19 to a conservatively-treated group. All the patients were regularly followed up by clinical evaluation, plain radiography and MRI at intervals of three months. Hip pain was relieved in nine out of ten initially symptomatic hips in the core-decompression group but persisted in three out of four initially painful hips in the conservatively-treated group at the second assessment (p < 0.05). At a minimum follow-up of 24 months, 14 of the 18 core-decompressed hips (78%) and 15 of the 19 non-operated hips (79%) developed collapse of the femoral head. By survival analysis, there was no significant difference in the time to collapse between the two groups (log-rank test p = 0.79). Core decompression may be effective tin symptomatic relief, but is of no greater value than conservative management in preventing collapse in early osteonecrosis of the femoral head.