The early results of gender-specific total knee arthroplasty in Thai patients

Is standard total knee arthroplasty with lateral femoral overhanging a cause of anterior knee pain? A randomized controlled trial

Introduction: Anterior knee pain (AKP) may persist after total knee arthroplasty (TKA), even if well aligned and stable, and is reported in up to 30% of patients, leading to patient dissatisfaction. The gender-specific knee prostheses have been designed to reduce femoral component overhanging in females and improve patient satisfaction. The purpose of this study was to determine AKP between gender-specific knee prosthesis and unisex knee prosthesis following minimally invasive surgery (MIS) TKA with patellar resurfacing. Methods: This study was a randomized trial comparing a gender-specific vs. unisex knee prosthesis in females with knee osteoarthritis. Follow-up occurred at 6 weeks, 3 months, 6 months, 1 year, and 2 years. Pre- and postoperative AKP were measured at each follow-up. Intraoperative lateral overhanging of the femoral component and patellar tracking were also measured and compared between the two groups. Results: Sixty females were recruited; 30 underwent gender-specific knee prosthesis (Gp1) and 30 underwent unisex knee prosthesis (Gp2). No patients were lost to follow-up. The incidence rates of AKP and visual analog scale AKP pain scores at 2 years were 7 vs. 7% (p = 1.00) and 0.95 ± 0.31 (0–1) points vs. 1.10 ± 0.28 (0–1) points (p = 0.68) for gender and unisex prostheses, respectively. Patellar tilt and patellar shift were similar between the two groups. Patellar tilt and patellar shift were 2.56° ± 2.03 (0–8) vs. 2.67° ± 2.35 (0–9) (p = 0.46) and 1.25 ± 1.09 (0–3.2) mm vs. 1.15 ± 0.97 (0–2.9) mm (p = 0.34) for Gp1 and Gp2, respectively. Mean lateral femoral overhanging was 0.23 ± 0.63 mm (range: 1–2 mm, Gp1) vs. 1.57 ± 1.36 mm (range: 1–3 mm, Gp2) (p ≤ 0.001). Conclusion: Both types of prostheses had similar incidence rates of AKP, VAS scores for AKP. Lateral femoral overhanging of ≤ 3 mm was not the cause of AKP.

Gender differences in femoral trochlea morphology

PURPOSE

This study aimed to analyze the morphology of the anterior femoral condyle using a quantitative three-dimensional reconstruction method. The morphological data were compared between genders.

METHODS

Computed tomography scans of femurs were taken from 90 healthy subjects and then reconstructed in 3D modeling software. Coaxial cutting planes were created at 10° increments to measure the lateral and medial anterior condylar heights (LACH and MACH, respectively), lateral and medial trochlear groove widths (LTW and MTW, respectively), and for trochlear groove tracking. The absolute values and normalized data were compared between male and female subjects. The sulcus angle and deepest point of the trochlear groove at each cross-section were also analyzed to determine the differences in the depth of the trochlear groove.

RESULTS

The absolute dimensions of LACH, MACH, LTW, and MTW were significantly smaller in the female subjects, by 10.5%, 36.9%, 10.3%, and 11.0%, respectively, than in the males (p < 0.05). After normalization, no significant difference was found in the condylar height between the genders. However, the female subjects had a significantly larger value of approximately 7.9% for the normalized trochlear width.

CONCLUSION

Male subjects had greater condylar heights and widths than the female subjects. Although the trajectory of the trochlear groove varied greatly among the subjects, the trochlear groove appeared to be wider and shallower in the female subjects than in the male subjects. These results provide important information for the design of femoral trochlea to fit Asian female patients.

LEVEL OF EVIDENCE

III.

Patterns of Change Over Time in Knee Bone Shape Are Associated with Sex

BACKGROUND

Knee osteoarthritis (OA) is more common in females than in males; however, the biological mechanisms for the difference in sex in patients with knee OA are not well understood. Knee shape is associated with OA and with sex, but the patterns of change in the bone's shape over time and their relation to sex and OA are unknown and may help inform how sex is associated with shape and OA and whether the effect is exerted early or later in life.Questions/purposes (1) Does knee shape segregate stably into different groups of trajectories of change (groups of knees that share similar patterns of changes in bone shape over time)? (2) Do females and males have different trajectories of bone shape changes? (3) Is radiographic OA at baseline associated with trajectories of bone shape changes?

METHODS

We used data collected from the NIH-funded Osteoarthritis Initiative (OAI) to evaluate a cohort of people aged 45 to 79 years at baseline who had either symptomatic knee OA or were at high risk of having it. The OAI cohort included 4796 participants (58% females; n = 2804) at baseline who either had symptomatic knee OA (defined as having radiographic tibiofemoral knee OA and answering positively to the question "have you had pain, aching or stiffness around the knee on most days for at least one month during the past 12 months") or were at high risk of symptomatic knee OA (defined as having knee symptoms during the prior 12 months along with any of the following: overweight; knee injury; knee surgery other than replacement; family history of total knee replacement for OA; presence of Heberden's nodes; daily knee bending activity) or were part of a small nonexposed subcohort. From these participants, we limited the eligible group to those with radiographs available and read at baseline, 2 years, and 4 years, and randomly selected participants from each OAI subcohort in a manner to enrich representation in the study of the progression and nonexposed subcohorts, which were smaller in number than the OA incidence subcohort. From these patients, we randomly sampled 473 knees with radiographs available at baseline, 2 years, and 4 years. We outlined the shape of the distal femur and proximal tibia on radiographs at all three timepoints using statistical shape modelling. Five modes (each mode represents a particular type of knee bone shape variation) were derived for the proximal tibia and distal femur's shape, accounting for 78% of the total variance in shape. Group-based trajectory modelling (a statistical approach to identify the clusters of participants following a similar progression of change of bone shape over time, that is, trajectory group) was used to identify distinctive patterns of change in the bone shape for each mode. We examined the association of sex and radiographic OA at baseline with the trajectories of each bone shape mode using a multivariable polytomous regression model while adjusting for age, BMI, and race.

RESULTS

Knee bone shape change trajectories segregated stably into different groups. In all modes, three distinct trajectory groups were derived, with the mean posterior probabilities (a measure of an individual's probability of being in a particular group and often used to characterize how well the trajectory model is working to describe the population) ranging from 84% to 99%, indicating excellent model fitting. For most of the modes of both the femur and tibia, the intercepts for the three trajectory groups were different; however, the rates of change were generally similar in each mode. Females and males had different trajectories of bone shape change. For Mode 1 in the femur, females were more likely to be in trajectory Groups 3 (odds ratio 30.2 [95% CI 12.2 to 75.0]; p < 0.001) and 2 than males (OR 4.1 [95% CI 2.3 to 7.1]; p < 0.001); thus, females had increased depth of the intercondylar fossa and broader shaft width relative to epicondylar width compared with males. For Mode 1 in the tibia, females were less likely to be in trajectory Group 2 (OR 0.5 [95% CI 0.3 to 0.9]; p = 0.01) than males (that is, knees of females were less likely to display superior elevation of tibial plateau or decreased shaft width relative to head width). Radiographic OA at baseline was associated with specific shape-change trajectory groups. For Mode 1 in the femur, knees with OA were less likely to be in trajectory Groups 3 (OR 0.4 [95% CI 0.2 to 0.8]; p = 0.008) and 2 (OR 0.6 [95% CI 0.3 to 1.0]; p = 0.03) than knees without OA; thus, knees with OA had decreased depth of the intercondylar fossa and narrower shaft width relative to epicondylar width compared with knees without OA. For Mode 1 in the tibia, knees with OA were not associated with trajectory.

CONCLUSIONS

The shapes of the distal femur and proximal tibia did not change much over time. Sex and baseline knee radiographic OA status are associated with the trajectory of change in the bone's shape, suggesting that both may contribute earlier in life to the associations among trajectories observed in older individuals. Future studies might explore sex-related bone shape change earlier in life to help determine when the sex-specific shapes arise and also the degree to which these sex-related shapes are alterable by injury or other events.

LEVEL OF EVIDENCE

Level III, prognostic study.

An anatomical study of the proximal aspect of the medial femoral condyle to define the proximal-distal condylar length

Objective:

Despite its possible role in knee arthroplasty, the proximal-distal condylar length (PDCL) of the femur has never been reported in the literature. We conducted an anatomic study of the proximal aspect of the medial femoral condyle to propose a method for measuring the PDCL.

Materials and Methods:

Inspection of dried bone specimens was carried out to assure the most proximal condylar margin (MPCM) as the eligible starting point to measure the PDCL. Simulation surgery was performed on seven pairs of cadaveric knees to verify the clinical application of measuring the PDCL after locating the MPCM. Interobserver reliability of this procedure was also analyzed.

Results:

Observation of the bone specimens showed that the MPCM is a concavity formed by the junction of the distal end of the supracondylar ridge and the proximal margin of the medial condyle. This anatomically distinctive structure made the MPCM an unambiguous landmark. The cadaveric simulation surgical dissection demonstrated that the MPCM is easily accessed in a surgical setting, making the measurement of the PDCL plausible. The intraclass correlation coefficient was 0.78, indicating good interobserver reliability for this technique.

Conclusion:

This study has suggested that the PDCL can be measured based on the MPCM in a surgical setting. PDCL measurement might be useful in joint line position management, selection of femoral component sizes, and other applications related to the proximal-distal dimension of the knee. Further investigation is required.

Morphometry of femoral rotation for total knee prosthesis according to gender in a Korean population using three-dimensional magnetic resonance imaging

BACKGROUND

We aimed to evaluate differences in femoral arthometric data for 700 osteoarthritic knees (587 females and 113 males) with respect to gender in a Korean population.

METHODS

We identified and measured the mediolateral (ML) and anteroposterior (AP) lengths, femoral aspect ratio (ML/AP), surgical epicondylar axis (SEA), and Whiteside's line (WL). In addition, the anterior, posterior, and distal bone resections of the implanted femurs were evaluated using SEA and WL as references using a three-dimensional analysis method.

RESULTS

ML and AP lengths significantly differed according to gender. ML dimension and aspect ratio were greater in males than in females for a given AP dimension in the femur. No statistically significant differences in femoral rotation with SEA as a reference were observed between male and female knees; however, a significant difference was shown using WL as a reference and both affected the amount of bone resection irrespective of gender.

CONCLUSION

This study provides important guidelines for gender-specific femoral prosthesis design with different ML and AP aspect ratios and femoral rotation based on SEA and WL for Korean populations.

Anthropometric measurements of the femur change with component positioning in total knee arthroplasty

BACKGROUND

To analyze aspect ratio (AP size/ (ML) size) of osteoarthritic knees at four different areas of the femur and to observe if proximalization of the femoral cut would change the ML size as well as confirm that external rotation increases the measurements for the AP dimensions of the femur.

METHOD

From the available MyKnee database (Medacta International, Castel San Pietro, Switzerland) 1030 patients were randomly selected within 20° of deformity consisting of 400 men with a mean (SD) age of 67.5 (9) years and 630 women with a mean (SD) age of 69 (10) years (p<0.0001). A specific software program was developed to measure AP and ML dimensions of the femur on CT-scans for (3D) planning in four areas. The AP femoral size was measured with neutral axial rotation following the epicondylar axis and without accepting anterolateral notching.

RESULTS

Proximalization of the femur resulted in no changes except for a larger ML3 area in men. Increased axial rotation increased the AP dimensions for the same femur by a mean (SD) 2.5 (1) mm for males and females.

CONCLUSIONS

The crucial area for overhang of the femoral component is the anterior region (ML1) with an aspect ratio of about ±, but with an important range. Proximalization of the femoral cut is not accompanied by narrowing of the anterior femur but ML widening of the more posterior femur in men. Increased external rotation leads to a measurement of bigger AP size leading to an AP versus ML mismatch and change in aspect ratio.

A lateralized anterior flange improves femoral component bone coverage in current total knee prostheses

BACKGROUND

Poor femoral implant fit to resected bone surfaces recently has been the motivation for several new total knee arthroplasty implant designs. Implant overhang risks adverse soft-tissue interaction while uncovered cut bone surfaces (underhang) risks increased postoperative bleeding or development of heterotopic bone.

METHODS

Femoral implant fit was studied systematically, and without the influence of surgical variation, by virtually implanting standard and narrow width femoral components (Bi-Surface 5) using preoperative computed tomography data for 150 varus osteoarthritic knees in Japanese patients. Overhang and underhang rates and bone widths were determined by gender.

RESULTS

Narrow femoral components helped avoid or minimize overhang in most female and some male knees. Although anterior width in the narrow components closely matched female bone width, the femoral component was necessarily displaced laterally to avoid overhang in the anteromedial portion. Consequently, there was significant medial underhang in the distal and posterior zones.

CONCLUSIONS

Ideally, the anterior femoral flange should be shifted 2 to 2.5mm laterally relative to the distal and posterior aspects to provide optimal femoral bone coverage in this prosthesis. The current study also confirmed that this modification can be generalized to the other two currently available "narrow type" prostheses. This geometric modification might allow surgeons to select a femoral component with slightly wider mediolateral dimensions in the distal and posterior aspects to minimize underhang, while eliminating anterior overhang.

LEVEL OF EVIDENCE

III.

Clinical Outcomes in Men and Women following Total Knee Arthroplasty with a High-Flex Knee: No Clinical Effect of Gender

While it is generally recognized that anatomical differences exist between the male and female knee, the literature generally refutes the clinical need for gender-specific total knee prostheses. It has been found that standard, unisex knees perform as well, or better, in women than men. Recently, high-flex knees have become available that mechanically accommodate increased flexion yet no studies have directly compared the outcomes of these devices in men and women to see if gender-based differences exist. We retrospectively compared the performance of the high-flex Vanguard knee (Biomet, Warsaw, IN) in 716 male and 1,069 female knees. Kaplan-Meier survivorship was 98.5% at 5.6–5.7 years for both genders. After 2 years, mean improvements in Knee Society Knee and Function scores for men and women (50.9 versus 46.3; 26.5 versus 23.1) and corresponding SF-12 Mental and Physical scores (0.2 versus 2.2; 13.7 versus 12.2) were similar with differences not clinically relevant. Postoperative motion gains as a function of preoperative motion level were virtually identical in men and women. This further confirms the suitability of unisex total knee prostheses for both men and women.

Gender-specific total knee arthroplasty in Singaporean women

PURPOSE

To compare the outcome of 145 women who underwent conventional total knee arthroplasty (TKA) with 77 women who underwent gender-specific TKA.

METHODS

Records of 222 women who underwent primary TKA using a conventional (n=145) or gender-specific (n=77) size E or F prosthesis for end-stage osteoarthritis were reviewed. The gender-specific prosthesis has a narrower mediolateral dimension. Patients were assessed for flexion, Oxford Knee Score, Knee Society function and knee scores, and Short Form-36 Health Survey preoperatively and postoperatively (at 6 months and 2 years).

RESULTS

The 2 groups were comparable in terms of age (67.8 vs. 68.1 years, p=0.789), body mass index (28.6 vs. 27.8 kg/m(2), p=0.189), and preoperative scores. 12 women with conventional TKA and 4 women with gender-specific TKA were lost to followup. Compared with women with conventional TKA, women with gender-specific TKA had better flexion at 6 months (116° vs. 121.9°, p=0.007) and 2 years (118.7° vs. 124.6°, p=0.006), better bodily pain score at 2 years (65.1 vs. 72.4, p=0.049), and greater improvement in bodily pain score from baseline to 2 years (30 vs. 38.5, p=0.034).

CONCLUSION

Gender-specific TKA enables better knee flexion and less bodily pain in women who have a high propensity to develop mediolateral overhang of the femoral component.

Results of gender-specific total knee arthroplasty: comparative study with traditional implant in female patients

Purpose

To compare the incidence of overhang between two distinct femoral components and whether there is clinical and radiological benefit of gender-specific implants in short-term follow-up.

Materials and Methods

One hundred and four knees in consecutive 66 female patients who underwent primary total knee arthroplasty due to primary osteoarthritis were included in this study. Overhang was measured and recorded in every cut surface of femur with both gender-specific and traditional trial femoral components respectively in every patient. Then, the knees were divided into two groups according to the type of the permanent femoral component they received. Clinical and radiological outcomes were compared between 2 groups at minimum 3 years after operation.

Results

Mean follow-up duration was 41.3 months (range, 36 to 50 months). Sixty two knees (59.6%) showed femoral overhang at least in one area with a traditional trial component, while 26 knees (25.0%) did with a gender-specific trial component (p<0.001). In terms of range of motion, Hospital for Special Surgery knee score, radiographic result, patella tilt angle and displacement, no significant difference was observed between two groups.

Conclusions

The use of gender-specific implants substantially reduced the incidence of femoral overhang but did not demonstrate any clinical, functional or radiologic benefit in short-term follow-up.

Preoperative morphometric differences in the distal femur are based on skeletal size in Japanese patients undergoing total knee arthroplasty

PURPOSE

The objectives of this study were to measure the morphometric parameters of preoperative distal femurs to determine the differences by diagnosis and gender after accounting for skeletal size.

METHODS

One-hundred and seventy-nine Japanese patients who underwent total knee arthroplasty (TKA) (25 males and 154 females) were assessed. The anteroposterior length (AP), mediolateral width (ML), aspect ratio (AR), surgical epicondylar axis (SEA) to posterior condylar axis (PCA) angle, and Whiteside to SEA angle were measured on preoperative computed tomography scans. The AP/ML, AR/ML, SEA/PCA, and Whiteside/PCA relationships were evaluated and compared by patient diagnosis and gender. The results were also compared with the sizes of 10 currently available TKA implants in Japan.

RESULTS

The mean AP, ML, AR, SEA/PCA angle, and Whiteside/PCA angle were 58.8 mm, 64.7 mm, 0.91, external rotation (ER) 3.5°, and ER 1.6°, respectively. AP and AR each were significantly correlated with ML (p < 0.001). AP, ML, and AR were not significantly different between patients diagnosed with osteoarthritis and rheumatoid arthritis. AP/ML and AR/ML were significantly correlated within each diagnosis (p < 0.001), but the analysis of covariance showed no significant differences between the diagnoses. AP and ML were significantly longer (p < 0.001) in males (63.6, 72.7 mm) than in females (58.1, 63.4 mm), while AR was smaller in males (0.88 vs. 0.92), with significant correlations for AP/ML (male: p < 0.010, female: p < 0.001) and AR/ML (male: p = 0.002, female: p < 0.001) in each gender. However, the analysis of covariance showed no significant differences between gender in the AP/ML and AR/MR correlations. The AP/ML ratio of our data was similar to the size variations of the 10 TKA implants, but the AR/ML ratio was quite different from almost all the implants.

CONCLUSIONS

No differences in preoperative femur morphometry were found between patients with different diagnoses, but the gender difference in AR was related to the difference in skeletal size between males and females.

LEVEL OF EVIDENCE

Case series with no comparison groups, Level IV.

Femoral sizing in total knee arthroplasty is rotation dependant

PURPOSE

The mismatch between the medio-lateral (ML) and the antero-posterior (AP) size of femoral components in total knee arthroplasty (TKA) has been linked to gender, ethnicity, morphotype and height differences in patients. The hypothesis of this study was that the AP size measurement of a femoral component increases with more external rotation in posterior referencing TKA.

METHODS

During a 2-year period, 201 patients were included in this prospective study. The AP distance of the distal femur was measured with an AP sizer of the Vanguard (Biomet, Warsaw, US) knee system. This AP sizer allows to dial in external rotation by 1° increments and to determine the femoral size with an anterior boom. AP size was noted at 0°, 3° and 5° of external rotation and then compared for ML matching.

RESULTS

Antero-posterior and corresponding ML sizes match perfectly for the Vanguard at 0° of external rotation and a central boom position on the anterior femoral surface. Then, the anterior boom was positioned on the antero-lateral cortex and the AP size increased a mean (SD) 1 (0.5) mm. With 3° of external rotation, the AP size increased a mean (SD) 2.3 (0.4) mm and for 5° a mean (SD) 3.8 (0.3) mm (P < 0.05). This increase in AP size resulted in ML overhang of 2.2 (1.2) mm for 3° and 4.8 (2.6) mm for 5° (P < 0.05).

CONCLUSIONS

Antero-posterior size measurement of the distal femur is determined by the anatomy of the anterior surface with a higher antero-lateral cortex and the amount of external rotation that is dialled in during surgery. Since these parameters vary case per case, the availability of narrow components offers more surgical options to the surgeon and its importance extends beyond the gender aspect allowing different amounts of external rotation to be used without ML overhang.

LEVEL OF EVIDENCE

II.

Female-specific vs conventional knee prostheses after total knee arthroplasty: A meta-analysis

AIM: To study whether female-specific prostheses are superior to conventional prostheses after total knee arthroplasty (TKA) by conducting this meta-analysis to evaluate the effects of the 2 different designs.

METHODS: A systematic electronic search was conducted in the databases of PubMed, EMBASE and the Cochrane Library for prospective and retrospective trials. Meta-analysis was performed for the outcomes, including range of motion (ROM), Knee Society score, Hospital for Special Surgery scores (HSS) and complications including deep infection, manipulation under anesthesia (MUA), revisions, anterior knee pain, deep vein thrombosis and overhang rate. Meta-analysis was conducted where applicable. Weighted mean difference (WMD) and odds ratio were calculated according to study type.

RESULTS: Seven studies including 1174 knees were eligible for data extraction and pooled analysis. The overhang rate of female-specific prostheses was significantly lower than the conventional ones (WMD, 3.25; 95%CI: 0.00-0.27; P = 0.001). ROM in the female-specific prostheses group after TKA tended to be greater than the conventional prostheses group; however, with insignificant difference (WMD, 2.48; 95%CI: -0.83-5.78; P = 0.14). HSS (WMD, 0.48; 95%CI: -1.45-0.88; P = 0.63) and complications including deep infection (WMD, 0.39; 95%CI: 0.19-3.08; P =0 .70), MUA (WMD, 1.53; 95%CI: 0.02-1.61; P = 0.13) and revisions (WMD, 0.55; 95%CI: 0.07-4.34; P = 0.13) were all comparable between the two groups with at least 1 year follow-up. Other indexes were revealed to be similar between the two treatments with a descriptive analytical method.

CONCLUSION: Although the overhang rate is lower with female-specific prostheses, the current evidence does not support that female-specific prostheses outweigh conventional ones after TKA.

No clinical benefit of gender-specific total knee arthroplasty

BACKGROUND AND PURPOSE

There is no consensus regarding the clinical relevance of gender-specific prostheses in total knee arthroplasty (TKA). We summarize the current best evidence in a comparison of clinical and radiographic outcomes between gender-specific prostheses and standard unisex prostheses in female patients.

METHODS

We used the PubMed, Embase, Cochrane, Science Citation Index, and Scopus databases. We included randomized controlled trials published up to January 2013 that compared gender-specific prostheses with standard unisex prostheses in female patients who underwent primary TKAs.

RESULTS

6 trials involving 423 patients with 846 knee joints met the inclusion criteria. No statistically significant differences were observed between the 2 designs regarding pain, range of motion (ROM), knee scores, satisfaction, preference, complications, and radiographic results. The gender-specific design (Gender Solutions; Zimmer Inc, Warsaw, Indiana) reduced the prevalence of overhang. However, it had less overall coverage of the femoral condyles compared to the unisex group. In fact, the femoral prosthesis in the standard unisex group matched better than that in the gender-specific group.

INTERPRETATION

Gender-specific prostheses do not appear to confer any benefit in terms of clinician- and patient-reported outcomes for the female knee.

Are gender-specific femoral implants for total knee arthroplasty necessary?

The purpose of this study was to determine the effect of gender on epiphyseal morphology and using this information to determine if an implant product line with a single width provides sufficient bone coverage for the entire population of knees being replaced. Morphology of the distal femoral epiphysis from 420 continuous knees was acquired with a surgical navigation system during primary TKA. A three-dimensional model of the distal femur was generated and used to determine the anterioposterior (AP) and mediolateral (ML) dimensions on 19 different virtual knee sections. Female knees had smaller AP and ML dimensions than male knees. The ML width of the distal femoral epiphysis was associated with femur length, not gender. Measurements derived from surgical navigation confirm that distal femoral epiphysis dimensions are related to femur length only independently of gender.

Gender-based differences in the dimensions of the femoral trochlea and condyles in the Chinese population: correlation to the risk of femoral component overhang

BACKGROUND

Femoral component overhang has been observed in total knee arthroplasty with different prostheses. The purpose of this study is to assess gender-based anatomical differences of the distal femur and femoral trochlea in the Chinese population and analyze the risk sites of femoral component overhang in relation to any significant anatomical differences.

METHODS

Measurements of distal condylar and femoral trochlea were made through three-dimensional computed tomographic modeling of 200 normal Chinese knees; the anatomical differences between genders and its relations to the femoral component overhang were analyzed. Four implants were also measured and compared.

RESULTS

The ML/AP ratios of the femoral condyles showed statistically significant gender-based variation (Men:Women=1.06:1.03, P<0.0001). Both the proximal and distal ML widths of the trochlea were generally larger in the men than those of the women. Regression analysis of the morphological data showed that as the measuring level moves distally along the femur, the coronal width deviation between genders progressively increases to peak at the distal condyles. Female subjects had a smaller aspect ratio than those of four implants and a smaller trochlear ML width than those of three implants.

CONCLUSIONS

The males show significantly greater coronal dimensions of the trochlea than women which are likely to contribute to the higher prevalence of prosthetic overhang in women with some standard implants.

CLINICAL RELEVANCE

The overhang is most likely to occur in the distal femoral condyle and the distal region of the femoral trochlea when a standard knee prosthetic system is used in the Chinese women.

How the gender or morphological specific TKA prosthesis improves the component fit in the Chinese population?

The purpose of this study was to evaluate how the gender specific or morphological specific total knee prostheses improve the component fit in the distal femur of the Chinese population. The data showed that the perfect fit rate of the femoral component remarkably increased in both the male and female subjects when using the gender specific (Nexgen-LPS GSF, Zimmer) or morphological specific (Advance Stature Knee, Wright Medical Technology) knee prostheses, compared to their standard counterparts. The highest femoral component perfect fit rate was achieved when both the standard and the corresponding gender or morphological specific knee prostheses were available for selection. Additionally, the percentage of the gender or morphological specific prosthesis selection in the females was significantly higher than the males.

Computed tomography morphometric study of gender differences in osteoarthritis proximal tibias

One hundred and thirty osteoarthritic knees(65 males, 65 females) from a Chinese population were measured by computed tomography for tibial mediolateral (ML), middle anteroposterior (AP), medial anteroposterior (MAP), lateral anteroposterior (LAP) dimensions and ML/AP aspect ratio. The ML/AP aspect ratio were classified into 3 groups based on AP dimensions(<48 mm, 48-52 mm, >52 mm) to compare the morphologic differences of proximal tibia between males and females. The mean ML, AP, MAP and LAP dimensions of proximal tibia showed significant differences for sex (P < .01). We found a progressively decreased in the ML/AP aspect ratio with an increasing AP dimension, and males have larger ML/AP aspect ratio than that of females under a given AP dimension (P < .01). This indicates that under a given AP dimension prosthesis, the tibial ML dimension have the potential to be undersized in males and to overhang in females. This study may provide important reference in designing proper gender-specific tibia prosthesis with different ML/AP aspect ratio for Chinese males and females.

Do we need a gender-specific total knee replacement? A randomised controlled trial comparing a high-flex and a gender-specific posterior design

The purpose of this study was to investigate whether a gender-specific high-flexion posterior-stabilised (PS) total knee replacement (TKR) would offer advantages over a high-flex PS TKR regarding range of movement (ROM), 'feel' of the knee, pain and satisfaction, as well as during activity. A total of 24 female patients with bilateral osteoarthritis entered this prospective, blind randomised trial in which they received a high-flex PS TKR in one knee and a gender-specific high-flexion PS TKR in the other knee. At follow-up, patients were assessed clinically measuring ROM, and questioned about pain, satisfaction and daily 'feel' of each knee. Patients underwent gait analysis pre-operatively and at one year, which yielded kinematic, kinetic and temporospatial parameters indicative of knee function during gait. At final follow-up we found no statistically significant differences in ROM (p = 0.82). The median pain score was 0 (0 to 8) in both groups (p = 0.95). The median satisfaction score was 9 (4 to 10) in the high-flex group and 8 (0 to 10) in the gender-specific group (p = 0.98). The median 'feel' score was 9 (3 to 10) in the high-flex group and 8 (0 to 10) in the gender-specific group (p = 0.66). Gait analysis showed no statistically significant differences between the two prosthetic designs in any kinematic, kinetic or temporospatial parameters. Both designs produced good clinical results with significant improvements in several gait parameters without evidence of any advantage in the gender-specific design.

The correctness of fit of current total knee prostheses compared with intra-operative anthropometric measurements in Korean knees

We aimed to obtain anthropometric data on Korean knees and to compare these with data on commonly available total knee arthroplasties (TKAs). The dimensions of the femora and tibiae of 1168 knees were measured intra-operatively. The femoral components were found to show a tendency toward mediolateral (ML) under-coverage in small femurs and ML overhang in the large femurs. The ML under-coverage was most prominent for the small prostheses. The ML/anteroposterior (ML/AP) ratio of Korean tibiae was greater than that of tibial components. This study shows that, for different reasons, current TKAs do not provide a reasonable fit for small or large Korean knees, and that the 'gender-specific' and 'stature-specific' components help for large Korean femurs but offer less satisfactory fits for small femurs. Specific modifications of prostheses are needed for Asian knees.

Hi-flexion and gender-specific designs fail to provide significant increases in range of motion during cruciate-retaining total knee arthroplasty

The effects of different femoral component designs on intraoperative range of motion were examined in 40 female patients during primary cruciate-retaining (CR) total knee arthroplasty. After complete bone resection and soft tissue balancing, standard CR, high-flexion, and gender-specific knee trials were sequentially inserted, and maximal flexion and extension under gravity were measured using a navigation system. Average maximal flexions were 134.3° for standard CR knees, 136.2° for high-flexion knees, and 136.4° for gender-specific knees. No significant intergroup differences in intraoperative maximal flexion and extension were found (P > .05). High-flexion and gender-specific femoral designs were found to show subtle increases in intraoperative range of motion as compared with the standard design but no significant differences.

Do we need gender-specific total joint arthroplasty?

BACKGROUND

Gender-specific differences in knee and hip anatomy have been well documented. Although it has been accepted these differences exist, there is controversy regarding if and how these differences should be addressed with gender-specific implant designs.

QUESTIONS/PURPOSES

(1) What are the anatomic and morphologic differences, if any, in the knee and hip between men and women? (2) Do gender-specific TKA designs provide better clinical functioning, survivorship, and improved fit in women? (3) How have anatomic differences in the hip been addressed, if at all, by THA?

METHODS

We conducted a systematic review of the MEDLINE database to identify all articles reviewing basic science and clinical outcomes of gender-specific total knee and total hip implants. From these, we reviewed 253 studies.

RESULTS

The anatomic studies elucidated multiple differences in the anatomy of knees and hips between men and women. All reviewed studies report similar clinical function and satisfaction scores between men and women for gender-specific TKA and no improvement in these scores when comparing gender-specific TKA to unisex TKA. Current modularity in THA appears to accommodate any anatomic differences in the hip.

CONCLUSIONS

Based on the available literature, there is no difference in the outcome of patients with a gender-specific knee arthroplasty versus a unisex arthroplasty. It does not appear gender-specific THAs would provide any benefit over current systems.