Computed tomographic evaluation of femoral component rotation in total knee arthroplasty

Background:

Optimal femoral component rotational alignment in total knee arthroplasty (TKA) is crucial to establish a balanced knee reconstruction. Unbalanced knees can lead to instability, patellofemoral problems, persistent pain, stiffness, and generally poorer outcomes including early failure. Intraoperative techniques to achieve this optimal femoral component rotation include the use of the transepicondylar axis (TEA), the posterior-condylar-cut-parallel-to-the-tibial-cut (PCCPTC) technique and the anteroposterior axis technique (Whiteside''s line). The purpose of this study was to compare the PCCPTC technique to the TEA technique using computed tomography (CT) scans to assess femoral component rotational alignment.

Materials and Methods:

This study used postoperative CT scans to compare the degree of femoral component rotation obtained with the use of PCCPTC technique and the TEA. The femoral component rotation of 30 TKA was measured on postoperative CT scans the angle of deviation between the two lines radiographic trans-epicondylar axis (rTEA) and femoral prosthesis posterior condylar line (FPPCL) was determined. This angle represented the rotation of the femoral component relative to the true rTEA.

Results:

The degree of rotation measured 2.67 ± 1.11 degrees in the PCCPTC group and 5.60 ± 1.64 degrees in the TEA group.

Conclusion:

The use of the TEA technique for determining rotational alignment in TKR results in excessive external rotation of the femoral component compared to the PCCPTC technique.     

Hip Arthroscopy: The Use of Computer Assistance

Background:

Hip arthroscopy is rapidly becoming the mainstay of treatment for femoroacetabular impingement (FAI), but remains technically demanding and has its limitations. The failures of arthroscopic FAI surgery due to inaccurate and inadequate resection are reported to be increasing. Computer-assisted surgery (CAS) can theoretically improve the accuracy and precision of the osseous resections required to treat FAI. It does so by providing a preoperative assessment tool, an intraoperative tracking device, and a robotic-assisted cutting instrument.

Questions/Purposes:

The purpose of this review is to discuss the evolution of CAS to address the current limitations of arthroscopic FAI surgery and propose the features required of the ideal CAS solution for FAI.

Methods:

A computerized keyword search of MEDLINE was performed for studies that investigated the use of computer assistance in FAI surgery. Data was collected on preoperative assessment tools, intraoperative navigation programs, and robotic-assisted execution of FAI surgery.

Results:

Sixty-one articles were identified after the keyword search. Nineteen studies met our inclusion criteria. Thirteen studies were selected to address our study questions: three studies were analyzed for preoperative planning, six for navigated osseous resection, and four for robotic-assisted execution.

Conclusion:

Navigation and robotic-assisted surgery can preoperatively plan and execute osseous resection with greater accuracy compared to freehand techniques, although the clinical success and cost-effectiveness has yet to be demonstrated. The ideal CAS solution must be able to virtually plan a resection, guide the surgeon towards accurate execution of the plan, and facilitate post-resection assessment of the adequacy of resection.     

The impact of modern cement techniques on acetabular fixation in cemented total hip replacement

A radiographic study was performed to assess acetabular fixation in 78 total hip replacements performed between 1971 and 1980. In 1979, the technique of acetabular component insertion was modified to include water-pik lavage, preservation of subchondral bone of the acetabulum during reaming, multiple fixation holes in the pubis ischium and ilium, and devices that improve pressurization of the cement into the cancellous bone surfaces. The impact of these techniques was studied. A cumulative radiolucency score was calculated for each acetabulum from 5-year follow-up radiographs, and the mean cup radiolucency scores for two chronologic groups were compared using the t-test for independent samples. No significant differences in patient age, weight, or sex, type of prosthesis, or approach used was found between groups. The acetabular components inserted between 1979 and 1980 had significantly lower cup radiolucency scores than those inserted between 1971 and 1978, at 5-year follow-up evaluation. Modern cement technique may be responsible for significantly enhanced durability of acetabular fixation in cemented total hip replacement.     

A New Perspective on the Quercetin Paradox in Male Reproductive Dysfunction

Dietary bioflavonoids represent a large class of polyphenolic compounds found in most plants. A significant number of flavonoids are reported to have beneficial health effects. Quercetin is one such flavonoid which has been reported to possess strong antioxidant properties. However, as far as male reproduction and fertility are concerned, controversial reports exist in the literature highlighting the antioxidant as well as a prooxidant character of quercetin, leaving much to the researcher's speculation. The present review therefore, aimed at addressing this paradoxical behavior of quercetin by taking into account the in vitro and in vivo studies conducted till date regarding its role in the maintenance of male reproductive potential. From the detailed survey of the published data, it appears that the conflicting biological effects of quercetin might relate to its dose and the redox state of the cell. Thus, the cellular toxicity of quercetin metabolites might overshadow the beneficial effects of its supplementation in subjects having reproductive dysfunction coupled with elevated oxidative stress leading to the paradoxical behavior of the flavonoid. Copyright © 2012 John Wiley & Sons, Ltd.     

Rhizospheric Flora and the Influence of Agronomic Practices on Them: A Review

Plants and most of the microorganisms in the rhizosphere have symbiotic relationships. While rhizodeposits (root exudates having lysates, mucilages) provide the food and influence the structure and number of microorganisms in the rhizosphere, the latter benefit the plants through secretion of a number of growth promoting hormones, organic acids and siderophores that help in increased availability and uptake of nutrients by plants. The interactions of roots and microflora may influence the plant growth positively through a variety of mechanisms, including fixation of atmospheric nitrogen by different classes of proteobacteria, increased biotic and abiotic stress tolerance imparted by the presence of endophytic microbes, and direct and indirect advantages imparted by plant growth-promoting rhizobacteria. The soil microorganisms affect plant growth, and are affected by plant growth, but there is incomplete understanding of their cumulative and interactive effects on plant performance, especially under varied crop production regimes. The diversity of cropping systems in both time and space (by rotations, intercropping, and so on) creates a mosaic of soil resources and niches, which in turn, enhances belowground biodiversity and improves the resilience of the system as a whole. Therefore, agronomic practices such as crop rotation, tillage, addition of organic manures, chemical fertilizers and mulches influence the structure and number of microorganisms in the rhizosphere. However, very little data are available on this subject. There is a need to generate such data to develop a strategy for sustainable agriculture.     

Anthropometric measurements to design total knee prostheses for the Indian population

An anthropometric computed tomography scan study was undertaken to design femoral components in 86 knees (47 osteoarthritic Indians-21 men, 26 women) who matched standards suggested by the Indian Council of Medical Research, 1990. Patients were classified into 3 random groups based on anteroposterior diameter (<55 mm, 55-59 mm, >59 mm). Most Indian men (86.8%) could have the femoral component satisfactorily replaced by available designs. A statistically significant number of women (60.4%, P < .001) had femoral anteroposterior diameters smaller than the smallest available (55 mm) femoral component. Splaying in mediolateral dimension (> 10 mm) in a given anteroposterior size was noted in all 3 groups. This pilot study representative of the Indian population can be used to manufacture prosthetic inventories suitable for most of the Asian-Pacific population having smaller anthropometric measurements than Western populations.     

Clinical and radiographic evaluation of the Harris-Galante cup: incidence of wear and osteolysis at 7 to 9 years follow-up

A retrospective evaluation of the clinical and radiographic results of the Harris-Galante acetabular cups was performed in 112 patients with 127 total hip arthroplasties. Patients with 14 hips had died, and patients with 20 hips were lost to follow-up. A total of 82 patients with 93 hips was available for follow-up. There were 67 men and 45 women. The mean follow-up was 87 months (range, 48-113 months). There were a total of 9 revisions: 2 for recurrent dislocations, 1 for a loose cup, and 6 for wear and osteolysis. Radiographic evaluation demonstrated that 22 (24%) hips had periacetabular osteolysis, and 16 of these 22 (73%) were associated with the screws. Twenty-two hips (23%) demonstrated osteolytic lesions around the femoral stem. Mean femoral head displacement was of 1.00 mm (range, 0.40-4.5 mm) with a rate of 0.16 mm/yr (range, 0.05-0.44 mm/yr). The Harris-Galante socket has maintained a low implant failure rate at intermediate term, even in these young patients. As follow-up increases, wear of the polyethylene and periprosthetic osteolysis may become growing concerns.     

Effect of stem stiffness and bone stiffness on bone remodeling in cemented total hip replacement

The hypothesis in this study is that the stem stiffness-to-bone stiffness ratio influences the incidence and type of bone remodeling and fixation with cemented total hip arthroplasty. Ninety-one patients with 99 hips had cemented stems using 3 different anatomic porous replacement designs. The APR I and APR II titanium stems with proximal porous coating on the proximal one fourth of the stem were cemented into 49 and 35 patients. The APR II-C stem, which is a cobalt-chrome stem only for cemented fixation, was cemented into 15 patients. These 3 different stem designs were used to study different metals as well as different stem shapes. The average follow-up was 4.3 years (range, 2-10 years) with all hips having 2 years' follow-up and 42 hips at least 5 years' follow-up. Bone remodeling was measured as stress shielding, calcar resorption, and distal hypertrophy on anteroposterior and lateral radiographs of the hip. Stress shielding was measured by the 4 grades described by Engh. A stem stiffness-to-femoral bone stiffness ratio was calculated from the plain radiographs with the stem stiffness known from the manufacturer and the bone stiffness calculated using measurements of the outer and inner diameters of the femur. There was no statistical difference for bone remodeling and fixation between the 3 stem shapes or 2 metal types used in these hips. No stem was loose, and only 10 had radiolucent lines. Stress shielding was statistically related to stem stiffness but was more strongly related to the axial stiffness ratio, mediolateral bending stiffness ratio, anteroposterior stiffness ratio, and torsional stiffness ratio. Stress shielding grade 3 and 4 was present in 20% of hips with a torsional stiffness ratio < 0.33, in 38% of hips with a torsional stiffness ratio of 0.34 to 0.5, and in 70% of hips with a torsional stiffness ratio > 0.5. Five-year results showed no statistical change in stress shielding, calcar resorption, and distal hypertrophy from the 2-year observations. The stem stiffness-to-bone stiffness ratio influenced bone remodeling but not fixation of these cemented stems.     

A fifteen-year follow-up study of one hundred Charnley low-friction arthroplasties

This two-part study concerns the fate of 100 Charnley low-friction arthroplasties performed in 92 patients at The Hospital for Special Surgery. The first part of the study is a clinical and radiographic evaluation of the 40 hips that were available for follow-up at an average of 15.3 years after surgery. The second part is a survival analysis of the arthroplasty, the individual components, and the patients, using data from all 100 arthroplasties. The authors conclude that the vast majority of older patients who undergo cemented total hip arthroplasty will not require a subsequent arthroplasty, and will have satisfactory pain relief for the remainder of their lives.