Search

It is known that the proximal femoral osteometry is different between Asians and whites. An uncemented femoral stem was therefore designed by us specifically for Asians, and we now report the medium-term clinical results. Results of a proximally porous-coated femoral component anatomically matched for Asians were analyzed in a consecutive cohort of 48 hips. The mean follow-up was 10.3 years. The mean Harris hip score was 39.4 preoperatively and 94.2 at last follow-up (P < .001). All stems had bone ingrowth. Stem survival was 100% up to 14 years using revision as the end point. Eight acetabular component revisions were performed for bearing surface failures and osteolysis. This femoral stem, specifically designed for better fit in an Asian population, had excellent clinical and radiologic outcome., (Copyright 2010 Elsevier Inc. All rights reserved.)

Purpose: To assess inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside's line in a cadaveric model mimicking total knee arthroplasty., Methods: Four cadaveric knees with intact soft tissues were used. The knees were exposed anteriorly using the Insall approach, with the patella everted laterally. Three observers (2 surgeons and one trainee) took turns to identify the anatomic landmarks of the transepicondylar axis and Whiteside's line. Each observer repeated the process 20 times. Each identification was photographed and referenced with the true values obtained from the knees after they were stripped of all soft tissue. Inter- and intra-observer errors in the anatomic landmarks were compared., Results: Inter-observer error was significant with both the transepicondylar axis and Whiteside's line (p<0.001, one-way ANOVA). The intra-observer variation was greater for Whiteside's line than the transepicondylar axis (standard deviation, 4.2 vs 2.5 degrees). The maximum potential errors in the transepicondylar axis and Whiteside's line were 13 degrees and 24 degrees, respectively., Conclusion: The accuracy of rotational alignment of the transepicondylar axis and Whiteside's line were operator-dependent, and their intra-operative reproducibility was low.

Unlabelled: Postoperative alignment of the implanted prosthesis in computer-navigated TKA has been reported to be superior to that using the conventional technique. There is an assumption that use of computer navigation techniques can make an inexperienced or occasional TKA surgeon perform more like an expert TKA surgeon. To assess improved accuracy in recreation of mechanical alignment in TKA performed using computer navigation, a retrospective review of the experience of one of the authors (WPY) before and after using computer navigation was performed. We reviewed the radiographic results of 104 TKAs (52 computer navigation, 52 conventional technique) and found the accuracy of postoperative radiographic alignment of the implanted prosthesis was not improved by using computer navigation as judged by (1) overall limb alignment (case: varus 1.3 degrees ; control: varus 0.3 degrees ); (2) femoral component alignment (case: 90.3 degrees ; control: 90.3 degrees ); and (3) tibial component alignment (case: 89 degrees ; control: 90 degrees ). Significant factors that affected postoperative overall mechanical alignment in the current navigation series included severity of the preoperative deformity, amount of error in making bone cuts, and experience of the surgeon in using the computer navigation system., Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Correct rotation of the femoral component is critical in avoiding patellar instability in total knee arthroplasty. This study attempted to compare the precision of 4 commonly used methods (transepicondylar axis [TEA], 3 degrees external rotation [ER] from posterior condylar line [PCL], perpendicular cut to Leo Whiteside line [WSL], and balanced flexion gap [GAP]) in determining the rotational alignment of the femoral prosthesis in an in vivo setting. The ranges of error were as follows: (1) TEA, 28 degrees (17 degrees internal rotation [IR] to 11 degrees ER); (2) PCL, 27 degrees (13 degrees IR to 14 degrees ER); (3) WSL, 32 degrees (17 degrees IR to 15 degrees ER); (4) GAP, 26 degrees (14 degrees IR to 12 degrees ER). If an error of more than 5 degrees from neutral alignment is defined as an outlier, 56% in TEA, 72% in PCL, 60% in WSL, and 20% in GAP methods would fall in the outlier zone.

We evaluated the relationship between the radiological indices that assessed the proximal femoral morphology and the degree of osteoporosis in 45 Chinese cadaveric femora. Canal-calcar ratio, canal flare index, morphological cortical index, and canal bone ratio were determined in the plain anteroposterior radiographs. Canal bone ratio is the ratio between the endosteal and outer diameters of the proximal femur at 10 cm below the lesser trochanter. Bone mineral density of the proximal femora was measured with dual-energy x-ray absorptiometry, and T score that depicted the degree of osteoporosis was determined. Canal bone ratio showed a strong correlation with the T score (r = -0.71, P < .001) and the best overall performance in diagnosing osteoporosis with receiver operating characteristic curve analysis. The proximal femur was likely to be osteoporotic if the canal bone ratio was 0.49 or higher.

We followed up 92 patients with total knee replacement and a pre-operative knee flexion of at least 90 degrees . The patients were followed up regularly at 3 months, 6 months and 1 year. The outcome measured was the amount of maximum passive knee flexion at the end of 1 year after replacement. The potential factors affecting the final flexion range were investigated. After regression analysis, apart from pre-operative knee flexion (p<0.001), the most significant independent surgical factors that predict the amount of post-operative flexion were presence of residual posterior femoral condyle osteophyte (p=0.046) and overstuffing the patella by more than 2 mm during resurfacing of the patella (p<0.001).

Purposes: The importance of the femoral sagittal bowing on total knee arthroplasty is under-recognized. The bowing could lead to potential errors in positioning of the femoral component if it is ignored. We aimed to document the femoral sagittal bowing at different segments of the Chinese femur and to discuss the implications of this sagittal bowing on total knee arthroplasty., Methods: One hundred lateral radiographs of the entire lower limbs of 85 Chinese patients admitted for total knee arthroplasty were digitized. The radii of curvature of the intramedullary canal of the proximal, middle and distal one-third of the femora were measured., Results: The average age of the patients was 67.3 years. The radii of curvature of the proximal, middle and distal one-third of the femora were 1081.6, 926.2 and 715.1 mm, respectively. The distal one-third of the femora was significantly more bowed than the other parts of the femora (p<0.001). The distal femoral bowing was more profound in rheumatoid patients and in those with a short femur., Conclusions: The lateral contour of the Chinese femur is like a hockey stick. This exaggerated sagittal bowing in the Chinese femur can affect the final sagittal position of the femoral component and has implications for the choice of implant design. In revision setting, a long and straight press-fit stem might either endanger the anterior cortex or deflect the femoral component to an abnormally extended position.

Objective: 39 sets of preoperative hip X-rays were studied to find out whether Chinese patients need revision femoral components with a different shape and size from western patients., Methods: From July 1998 to June 2001, the pre-revision X-rays of 39 revision total hip replacements among 38 Chinese patients (21 men and 17 women) were studied. The component size that produced the best distal canal-filling in the anteroposterior X-ray was determined by using templates of 200-mm femoral components used commonly for Caucasian patients., Results: The diameter of the component needed was 13.5 mm or less in 54% of cases, compared with only 17% for Caucasian patients as reported in the literature (p<0.01). When lateral templates of the corresponding size were put over the lateral X-rays, the anterior cortex of the 200-mm straight stem was shown to have thinned by 2.0 mm or more in 36% of hips; for 200-mm bowed stem, there was thinning of the anterior cortex by 2.0 mm or more in only 5% of hips (p<0.01)., Conclusion: Chinese patients are likely to need smaller femoral components than Caucasian patients, and may benefit from bowed-stem components in femoral revision.