Buechel and Pappas invented a modified version of LCS RP system (Co-Cr) with light material (Titanium), axial rotation limiting bar and improved conformity. The purpose of this prospective randomized study was to compare the minimum 3-year clinical outcomes including lightness, preference, and instability between the Co-Cr implant system and the Titanium implant system in bilateral total knee arthroplasty.

We prospectively enrolled 108 patients and 20 patients were lost to follow-up. Therefore, 88 patients (176 knees; mean age, 69.9±6.0years) were included in the study. The range of motion and clinical scores such as Knee Society score (KSS), Hospital for Special Surgery score (HSS) and Western Ontario and McMaster University (WOMAC) scores were measured preoperatively and postoperatively. At each follow-up, patients also complete a Likert scale questionnaire regarding subjective pain, lightness, left-right side preference (naturalness and satisfaction) and subjective instability.

There were no significant differences in all preoperative variables between two groups (p>.05). Mean follow-up period was 46.3±8.8 (36 to 72) months. The mean weight of Titanium implants was three times lighter than that of Co-Cr implants (133.9g versus 390.1g, p<.01). At the minimum of 3-year follow-up, there were no significant differences in pain, range of motion (ROM), clinical scores including KSS, HSS, and WOMAC between both groups. Also, the study showed no significant differences with subjective pain, lightness, preference (convenience, naturalness, and satisfaction), and subjective instability between the Co-Cr protheses and the Titanium protheses (p>.05).

No differences in clinical outcomes as well as subjective side-to-side differences between the Co-Cr prostheses and the Titanium prostheses were observed in the minimum 3-year follow-up. This implies that patients do not feel differently with two different weighted implants in mid-term follow-up.

Recently, several preliminary reports have been issued on the application of computer assistance to bone tumour surgery. Surgical navigation systems can apply three-dimensional images such as CT and MR images to intraoperative visualization. Although CT is better at describing cortical bone status, MRI is considered the best method for defining the extent of marrow involvement for bone tumours and for planning surgical resection in bone tumour surgery. There have been a few reports on the application of MR imaging to navigation-assisted bone tumour surgery through CT–MR image fusion. However, the CT–MRI fusion technique requires additional costs and exposure of the patient to radiation from the preoperative CT, as well as additional time for image fusion. Above all, the image fusion process is a kind of registration (image to image registration) that inevitably leads to registration error. Herein we describe a new method for the direct application of MR images to navigation-assisted bone tumour surgery as an alternative to CT–MRI fusion.

Six patients with an orthopaedic malignancy were employed for this method during navigation-assisted tumour resection. Resorbable pin placement and rapid 3-dimensional spoiled gradient echo sequences made the direct application of MR images to computer-assisted bone tumour surgery without CT–MR image fusion possible. A paired-point registration technique was employed for patient-image registration in all patients. It took 20 min on average to set up the navigation (range 15 to 25 minutes). The mean registration error was 0.98 mm (range 0.4 to 1.7 mm). On histologic examination, distances from tumours to resection margins were in accord with preoperative plans. Mean duration of follow-up was 25.8 months (range 18 to 32 months). No patient had a local recurrence or distant metastasis at the last follow-up.

Direct patient-to-MRI registration is a very useful method for bone tumour surgery, permitting the application of MR images to intraoperative visualization without any additional costs or exposure of the patient to radiation from the preoperative CT scan.

Aims: To evaluate the outcomes of the primary total hip arthroplasties using nonmodular cementless acetabular component with titanium mesh coating þxed by press-þt technique. Methods: Eighty-two primary total hip arthroplasties in 75 patients were performed consecutively. Sixty-two hips were eligible for follow up of average 62 months (range, 48–84). The mean age was 59 years. The clinical evaluation was done by modiþed Harris hip score (HHS) and radiologic evaluation including stability of component, polyethylene wear rate (Dorr method) and remodeling pattern was done. Results: Mean HHS improved from 50.2 points preoperatively to 90.5 points at the last follow up. Excellent or good results were found in 52 hips (84%). All components were stable radiologically. The average thickness of polyethylene was 13.06mm. The linear polyethylene wear rate was 0.073mm/years (range, 0.01–0.23). Wear rate was correlated with the thickness of polyethylene signiþcantly (p=0.049). Any pelvic osteolysis was not found. The polar gap was found in 25 hips (40%) at initial radiographs and has disappeared during follow up in 22 hips (88%). One hip was revised due to chronic unreduced dislocation. There were 9 heterotrophic ossiþcations, 6 nonrecurrent dislocations, and 2 transient sciatic nerve palsies. Conclusion: Total hip arthroplasty using nonmodular cementless acetabular component seemed to enhance satisfactory early mid-term result in terms of stability and acetabular remodeling with minimal wear and pelvic osteolysis.

Aims: To evaluate the early midterm outcomes of primary total hip arthroplasty (THA) using Hydroxyapatite (HA)-coated on smooth surface acetabular component with 28 mm metal head on polyethylene liner articulation. Methods: Seventy primary THA in 63 patients with HA-coated acetabular component were performed consecutively between June 1993 and August 1996. Fifty-four cases were eligible for follow-up of average 71 months (48–104) and the mean age of index operation was 49 years (23–71). The clinical results were analyzed by modiþed Harris hip score, and the radiologic evaluation in terms of stability, polyethylene wear rate (Dorr method), osteolysis around acetabular component was done. Results: Mean Harris hip score improved from 50.9 to 82.2 at the last follow-up. Excellent or good results were found in 38 cases (70%). Eight cases (15%) were unstable radiologically. Pelvic osteolysis was found at 18 cases (33%). The mean polyethylene wear rate was 0.146 mm/year (0.01–0.45). Wear rate of hip dyaplasia was greater than osteonecrosis signiþcantly (p< 0.05). Seven cases (13%) were revised (5 mechanical failures, 2 deep infections). Any bone ongrowth was not found during revision surgery for loose components. Complications included 5 heterotrophic ossiþcations, 2 deep infections, and 1 nonrecurrent dislocation. Conclusion: Primary THA using HA-coated on smooth surface acetabular component showed unsatisfactory clinical results, accelerated polyethylene wear rate accompanying high incidence of osteolysis, and high loosening rate due to lack of bony ongrowth at early midterm.

In countries where Confucianism is popular, it is extremely difþcult to get allograft. Twenty seven cases of limb salvage with recycled autogenous bone were performed after wide resection of malignant tumors. Recycling was done in 9 cases with pasteurization and in 18 cases with irradiation. Pasteurization was done in 60¡-30minutes with thermostatic saline bath. Irradiation was performed in sterile plastic jar þlled with saline. 25 Gy radiation was given þrst anteroposteriorly and then another 25Gy posteroanteriorly. Internal þxation was done either with plate and/or intramedullay nail, and in 13 cases, intramedullary packing of bone cement was added. Among 9 pasteurized cases, 5 were intercalary diaphyseal resection, 2 whole bone resection of metatarsals, and 2 prosthesis-pasteurized bone composite arthroplasty. Among 18 irradiated cases, 12 were osteoarticular, and 6 intercalary resections. Follow-up period was 16 to 112 months (mean: 46 months). There was no recycled bone-related local recurrence. Time for union varied greatly.(4 to 14 months). There was no statistical difference in union time between pasteurized and irradiated bone (Wilcoxon rank test). Complications were 9 delayed or non-union, 3 fractures of recycled bone, and 2 cases of separation-resorption of growth plate. Irradiation seems much better than pasteurization because it could preserve mechanical property of articular cartilage and soft tissues such as tendon and capsule. We recommend intraoperative-extracorporeal irradiation as a good substitute for osteoarticular allograft because soft tissue attachment could be saved. Intramedullary packing of bone cement was proved as a good method to enhance the stability of þxation and to prevent fracture.

Introduction: The purpose of this study was to compare the results of the efficacy of two decompressive methods (multiple drilling vs standard core decompression) for the treatment of precollapse osteonecrosis of the femoral head.

Methods: The results in a consecutive series of 54 patients (65 hips) who had undergone multiple drilling (31 patients, 35 hips) or core decompression (23 patients, 30 hips) for the treatment of precollapse osteonecrosis of the femoral head between September 1991 and July 2001 were reviewed. The average duration of follow up was 60.3 months (range, 24–103 months) in the multiple drilling group and 44.8 months (range, 24 to 84 months) in the core decompression group. The presence of collapse and radiographic progression in each group was evaluated prospectively with collapse of the femoral head defined as a failure. Harris hip scores (HHS) were used to evaluate clinical status preoperatively and at the most recent follow up.

Results: Radiographically and clinically, high failure was significantly related to the larger size and laterally located lesion (LHI of less than 12%, Urbaniak IIC, Ohzono IC and Kerboul index of more than 240 degrees) in both groups. The average preoperative and the last HHS was 86.7 to 73.7 in the core decompression group and 87.0 to 74.6 in the multiple drilling group. Compared to the core decompression group, the multiple drilling group had significantly longer times before collapse (mean 42.3 months vs 22.6 months, p=0.011) and a lower rate of collapse within 3 years after operation (55.0% vs 85.7%, p=0.03).

Discussion: Decompressive methods have worse outcomes in case of lesions of larger size and lateral location, even in precollapse stage. Multiple drilling has significantly longer time before collapse and a lower rate of collapse within 3 years after operation than standard core decompression.

Seventy-four mobile bearing total knee arthroplasties (LCS) without patellar resurfacing were analysed in 54 patients who were followed for a minimum of one year. We examined the congruence angle on Merchant’s view, the component rotation to the epicondylar line of the femur on computed tomography(CT), the femorotibial angle on weight-bearing anteroposterior radiograph to assess the contributing factors for the patellofemoral malalignment. The statistical analysis was performed by ANOVA test, student t test, and chi sguare test.

The patellofemoral pain was noted in 17 knees(23%). The incidence of patellofemoral pain was significantly increased in the knee when its congruence angle was more than 16 degrees (p=0.034). But the pain did not correlate with the status of the articular cartilage of the patella on operation. The average congrunce angle was 4¢ªdegrees preoperatively and 24.2 degrees postoperatively. The congruence angle in 29 knees with lateral release was significantly lower than that in 45 knees without lateral release (p=0.037). All femoral components were internally rotated on CT scan with average of 6.7 degrees. More significant increase of the congruence angle was observed in 42 knees with femoral or tibial component rotation than in 15 knees with normal or minimal rotation of both components(p=0.017). Pre-operative congruence angle and postoperative femorotibial angle also affected the patellofemoral alignment, which increased postoperative congruence angle respectively.

Based on our findings, it seems that the excessive internal rotation of one component and excessive valgus of the femorotibial angle should be avoided to prevent the patellofemoral maltracking. We believe that “no thumb test” should be done carefully and the lateral release performed without hesitation if patellar tracking is a concern.