Yoowang Choi

Computer-assisted surgical navigation does not improve the alignment and orientation of the components in total knee arthroplasty.

BACKGROUND Whether total knee arthroplasty with use of computer-assisted surgical navigation can improve the limb and component alignment is a matter of debate. We hypothesized that total knee arthroplasty with use of computer-assisted surgical navigation is superior to conventional total knee arthroplasty with regard to the precision of implant positioning. METHODS Sequential simultaneous bilateral total knee arthroplasties were carried out in 160 patients (320 knees). One knee was replaced with use of a computer-assisted surgical navigation system, and the other was replaced conventionally without use of computer-assisted surgical navigation. The two methods were compared for accuracy of orientation and alignment of the components as determined by radiographs and computed tomography scans. The mean duration of follow-up was 3.4 years. RESULTS The mean preoperative Knee Society score was 26 points, with an improvement to 92 points postoperatively, in the computer-assisted total knee arthroplasty group and 25 points, with an improvement to 93 points postoperatively, in the conventional total knee arthroplasty group. Preoperative and postoperative ranges of motion of the knees were similar in both groups. The operating and tourniquet times were significantly longer in the computer-assisted total knee arthroplasty group than in the conventional total knee arthroplasty group (p < 0.001). The groups were not significantly different with regard to the accuracy of component positioning and the number of outliers for the various radiographic parameters (p > 0.05). CONCLUSIONS Our data demonstrate that total knee arthroplasty with use of computer-assisted surgical navigation did not result in more accurate implant positioning than that achieved in conventional total knee arthroplasty, as determined by both radiographs and computed tomography scans.

Functional outcome and range of motion of high-flexion posterior cruciate-retaining and high-flexion posterior cruciate-substituting total knee prostheses. A prospective, randomized study.

BACKGROUND Although the design features of the high-flexion posterior cruciate-retaining and high-flexion posterior cruciate-substituting total knee prostheses reportedly improve the range of knee motion, a clinical comparison of both systems with regard to range of motion has not been reported, to our knowledge. The purpose of the present study was to compare the range of motion and functional outcome in knees receiving either a high-flexion posterior cruciate-retaining or a high-flexion posterior cruciate-substituting total knee prosthesis. METHODS Two hundred and fifty patients (mean age, 71.6 years) received a high-flexion posterior cruciate-retaining total knee prosthesis in one knee and a high-flexion posterior cruciate-substituting total knee prosthesis in the contralateral knee. Ten patients were men, and 240 were women. At the time of each follow-up (minimum duration of follow-up, two years; mean, 2.3 years), the patients were assessed clinically and radiographically with use of the knee-rating systems of the Knee Society and the Hospital for Special Surgery. In addition, each patient completed the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) questionnaire. Non-weight-bearing and weight-bearing ranges of knee motion were determined in both groups. RESULTS The mean postoperative Knee Society knee score was 94 points for the knees treated with a high-flexion cruciate-retaining prosthesis and 95 points for those treated with a high-flexion posterior cruciate-substituting prosthesis. The mean postoperative Hospital for Special Surgery knee score was 90 points for the knees that had been treated with a high-flexion posterior cruciate-retaining prosthesis and 91 points for those that had been treated with the high-flexion posterior cruciate-substituting prosthesis. At the time of the latest follow-up, the knees that had been treated with a high-flexion posterior cruciate-retaining prosthesis had a mean non-weight-bearing range of motion of 133 degrees and a mean weight-bearing range of motion of 118 degrees. The knees that had been treated with a high-flexion posterior cruciate-substituting prosthesis had a mean non-weight-bearing range of motion of 135 degrees and a mean weight-bearing range of motion of 122 degrees. No knee had aseptic loosening, revision, or osteolysis. CONCLUSIONS After a minimum duration of follow-up of two years, there was no difference in range of motion or clinical and radiographic results between knees that had received a high-flexion posterior cruciate-retaining total knee prosthesis and those that had received a high-flexion posterior cruciate-substituting total knee prosthesis.

Influence of Patient-, Design-, and Surgery-Related Factors on Rate of Dislocation After Primary Cementless Total Hip Arthroplasty

We performed clinical, radiographic, and computed tomography examinations on a consecutive series of 1268 patients (1648 hips) to determine the prevalence of and factors contributing to dislocation after using a primary cementless total hip system. The prevalence of posterior dislocation was 3.6% (60 hips). Significant risk factors (Fisher exact test or chi(2) test, P < .05) were female sex, advanced age, high American Society of Anesthesiologists score (3 or 4), fracture of the femoral neck, nonrepair of the posterior soft-tissue sleeve, low or high cup anteversion, low or high stem anteversion, and low height of hip rotation center.

Range of motion of standard and high-flexion posterior cruciate-retaining total knee prostheses a prospective randomized study.

BACKGROUND The main goals of total knee arthroplasty are pain relief and improvement in function and the range of motion. The purpose of this study was to compare the ranges of motion of the knees of patients treated with a standard posterior cruciate-retaining total knee prosthesis in one knee and a high-flexion posterior cruciate-retaining total knee prosthesis in the other. METHODS Fifty-four patients (mean age, 69.7 years) received a standard posterior cruciate-retaining total knee prosthesis in one knee and a high-flexion posterior cruciate-retaining total knee prosthesis in the contralateral knee. Five patients were men, and forty-nine were women. At a mean of three years postoperatively, the patients were assessed clinically and radiographically with the knee-rating systems of the Knee Society and the Hospital for Special Surgery and with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. RESULTS The mean postoperative Knee Society and Hospital for Special Surgery knee scores were 93.7 and 89 points, respectively, for the knees with a standard posterior cruciate-retaining prosthesis, and they were 93.9 and 90 points, respectively, for the knees with a high-flexion posterior cruciate-retaining prosthesis. The mean postoperative WOMAC score was 22 points. Postoperatively, the mean ranges of motion without and with weight-bearing were 131 degrees (range, 90 degrees to 150 degrees) and 115 degrees (range, 75 degrees to 145 degrees), respectively, in the knees with a standard prosthesis and 133 degrees (range, 90 degrees to 150 degrees) and 118 degrees (range, 75 degrees to 145 degrees), respectively, in those with a high-flexion prosthesis. Patient satisfaction and radiographic results were similar in the two groups. No knee had aseptic loosening, revision, or osteolysis. CONCLUSIONS After a minimum duration of follow-up of three years, we found no significant differences between the two groups with regard to the range of knee motion or the clinical or radiographic parameters.

Comparison of a Standard and a Gender-Specific Posterior Cruciate-Substituting High-Flexion Knee Prosthesis. A Prospective, Randomized, Short-Term Outcome Study

BACKGROUND Recently, much debate has focused on the effect of gender-specific total knee arthroplasty. The purpose of the present study was to compare clinical and radiographic results as well as femoral component fit in patients receiving either a standard posterior cruciate-substituting LPS-Flex or gender-specific posterior cruciate-substituting LPS-Flex total knee prosthesis. METHODS Sequential simultaneous bilateral total knee arthroplasty was performed for eighty-five patients (170 knees). Eighty-five women (mean age, 69.7 years) received a standard LPS-Flex prosthesis in one knee and a gender-specific LPS-Flex prosthesis in the contralateral knee. The mean duration of follow-up was 2.13 years. At each follow-up, the Knee Society score, the Hospital for Special Surgery knee score, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score, and radiographs were evaluated. The aspect ratio of the distal part of the femur was compared with those of the standard LPS-Flex prosthesis and the gender-specific LPS-Flex prosthesis. RESULTS The mean postoperative Knee Society scores (95.5 points in the standard implant group, compared with 96.5 points in the gender-specific implant group) and Hospital for Special Surgery knee scores (90.7 points in the standard implant group, compared with 91.2 points in the gender-specific implant group) were similar in both groups. The mean postoperative WOMAC score was 36.6 points. Postoperatively, the mean ranges of knee motion in the supine position (125 degrees in the standard implant group, compared with 126 degrees in the gender-specific implant group), patient satisfaction (8.3 points in the standard implant group, compared with 8.1 points in the gender-specific implant group), and radiographic results were similar in both groups. The femoral component in the standard implant group fit significantly better than that in the gender-specific implant group (p < 0.0001). CONCLUSIONS The present study did not show any clinical benefits of a gender-specific LPS-Flex total knee prosthesis at the time of short-term follow-up. Longer follow-up is needed to determine whether there will be an advantage in terms of longer-term function. LEVEL OF EVIDENCE Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.

Comparison of Bone Mineral Density Changes Around Short, Metaphyseal-Fitting, and Conventional Cementless Anatomical Femoral Components

We investigated the incidence and degree of stress shielding and clinical and radiographic results in 2 groups of patients. Fifty patients (60 hips) in each group were enrolled for a randomized study. One group received a short, metaphyseal-fitting femoral component and another group received a conventional metaphyseal- and diaphyseal-filling femoral component. The mean follow-up was 3.35 years in both groups. Bone mineral density was significantly increased in femoral zone 1 but slightly decreased in zone 7 in the short, metaphyseal-fitting stem group. In the conventional metaphyseal- and diaphyseal-fitting stem group, bone mineral density was markedly decreased in both zones 1 and 7. Clinical and radiographic results were similar between the 2 groups. No hip in either group required revision of the component.

Intermediate Results of Simultaneous Alumina-on-Alumina Bearing and Alumina-on-Highly Cross-Linked Polyethylene Bearing Total Hip Arthroplasties

This study compared the clinical and radiographic results and the prevalence of osteolysis between alumina-on-alumina and alumina-on-highly cross-linked polyethylene bearings after cementless total hip arthroplasties in the 100 patients younger than 50 years of age. There were 66 men and 34 women; the mean age at the time of surgery was 45.3 years (range, 25 to 49 years). The mean duration of follow-up was 5.6 years (range, five to seven years). The pre-and postoperative Harris hip scores were similar (39 and 41 points, respectively and 93 points and 94 points, respectively). No acetabular or femoral component had aseptic loosening in either group. The mean annual penetration of the highly cross-linked polyethylene was 0.06 +/- 0.03 mm. No hip in either group had acetabular or femoral osteolysis.

Cementless Total Hip Arthroplasty With Alumina-on-Highly Cross-Linked Polyethylene Bearing in Young Patients With Femoral Head Osteonecrosis

We asked whether total hip arthroplasties (THAs) using alumina-on-highly cross-linked polyethylene bearing would improve functional activity and reduce aseptic loosening, polyethylene wear, and osteolysis. Consecutive primary THAs were performed in 71 patients (73 hips) who were younger than 50 years (mean age, 45.5 years) with femoral head osteonecrosis. There were 48 men (50 hips) and 23 women (23 hips). Osteolysis was evaluated using radiographs and computed tomographic scanning. The average follow-up was 8.5 years (range, 7-9 years). The mean preoperative Harris hip score was 50.6 points, which improved to 96 points at the final follow-up. Preoperative functional activity was improved significantly at the latest follow-up. The mean polyethylene linear penetration was 0.05 ± 0.02 mm/y and no hip had aseptic loosening or osteolysis.

Osteolysis after unidirectional and multidirectional mobile-bearing total knee arthroplasty in young patients.

We questioned whether a difference exists between multidirectional and unidirectional mobile-bearing total knee arthroplasties in terms of clinical results and the prevalence of polyethylene wear and periprosthetic osteolysis. We studied 62 patients who underwent simultaneous bilateral total knee arthroplasties, with a unidirectional prosthesis implanted in 1 knee and a multidirectional one in the other. Of the patients, 9 were men and 53 were women, with a mean age of 57.6 years (35-60 years). The minimum follow-up was 11 years (mean, 11.8 years; range, 11-13 years). Preoperative and postoperative knee and functional scores were not different between the 2 groups. No knee in either group had detectable tibial polyethylene liner wear or osteolysis on radiographs or on computed tomography scans. Two (3%) knees in each group were revised.

RATES OF OSTEOLYSIS IN WELL-FUNCTIONING ALUMINA-ON-HIGHLY CROSS-LINKED POLYETHYLENE BEARING CEMENTLESS THA IN PATIENTS YOUNGER THAN FIFTY WITH FEMORAL HEAD OSTEONECROSIS

We asked whether total hip arthroplasties (THAs) using alumina-on-highly cross-linked polyethylene bearing would improve functional activity, and reduce aseptic loosening, polyethylene wear, and osteolysis. Consecutive primary THAs were performed in 71 patients (73 hips) who were younger than 50 years old (mean age, 45.5 years) with femoral head osteonecrosis. There were 48 men (50 hips) and 23 women (23 hips). Osteolysis was evaluated using radiographs and computer tomographic scanning. The average follow-up was 8.5 years (7–9 years). The mean preoperative Harris hip score was 50.6 points, which improved to 96 points at the final follow-up. Preoperative functional activity was improved significantly at the latest follow-up. The mean polyethylene linear penetration was 0.05 ± 0.02 mm per year and no hip had aseptic loosening or osteolysis.