Differences between the sexes in the anatomy of the anterior condyle of the knee

The Vascular Anatomy and Harvesting of the Lateral Femoral Condyle Flap in Pigs

BACKGROUND

 Clinically, there has been increasing employment of the lateral femoral condyle flap. The objective of this study was to explore the vascular anatomy of the lateral femoral condyle in pigs and to explore the feasibility of using pigs as an animal model of the lateral femoral condyle flap.

METHODS

 A total of 20 fresh cadaveric hindlimbs of 4-week-old hybrid pigs were used in this study. The origination, course, and branches of the nourishing vessels of the lateral femoral condyle were observed in 15 specimens. The primary parameters included the variability in the anatomy of the vessels and the length and outer diameter of the vessels. Surgical procedures for the lateral femoral condyle flap were conducted on five specimens.

RESULTS

 The primary nourishing arteries of the lateral femoral condyle in pigs were the first superolateral geniculate artery, which was observed in all 15 specimens and had a diameter and length of 1.99 ± 0.44 mm and 2.27 ± 0.46 cm, respectively, as measured at their origination. The operation was performed in the lateral position. A 10-cm skin incision was made from the lower edge of the patella to the posterior lateral side of the distal femur. After blunt dissection of the intermuscular septum between the biceps femoris and vastus lateralis, the whole course of the first superolateral geniculate artery was exposed.

CONCLUSION

 The vascular anatomy of the lateral femoral condyle in pigs and that of humans exhibited great similarities. The harvesting of the lateral femoral condyle flap in pigs was as easy as that in humans. Pigs could serve as a suitable animal model for the lateral femoral condyle flap.

Morphological Measurement and Clinical Significance of Abnormal Development of Distal Femur with Hemophilia Knee Arthritis: A Consideration on the Renewal of Total Knee Prosthesis

OBJECTIVE

The knee joint of hemophiliacs may face the result of local morphological changes due to long-term irritation of synovitis. This study aims to elucidate the morphological characteristics of distal femur in hemophilic arthritis (HA) and compare the compatibility of three types of prostheses with the anteroposterior (AP) and mediolateral (ML) dimensions of the femoral osteotomy surface.

METHODS

This study retrospectively and randomly selected 50 patients with HA registered for treatment at our hospital from June 2016 to August 2022 as the study subjects, with an equal number of male osteoarthritis (OA) patients and healthy male individuals set as the control group. This study used medical digitalization software to simulate osteotomies on the distal femur during total knee arthroplasties (TKA) for 50 patients with HA, OA patients, and the healthy population, respectively, and measure the morphological parameters to compare with three commonly used femoral components of TKA in clinical practice. The differences between the femur resection of anteroposterior and mediolateral (FRAP, FRML) osteotomy surface and the prosthesis's BOX-AP/ML were compared in three prostheses. One-way ANOVA and multiple Kruskal-Wallis H test were used for the normal or non-normal distribution data, and pairwise comparisons between groups were conducted using the Bonferroni method, and the linear correlation analysis was utilized to assess the relationship between section femoral morphological data and prosthesis parameters.

RESULT

In HA patients, the morphological characteristics of the distal femur were shown as shorter than femur AP (FAP), medial and lateral condyle anterior-posterior dimension (FMCAP, FLCAP), notch width (NW), posterolateral condyle height (PLCH), posteromedial condyle width (PMCW), and posterior condylar axis length (PCAL) dimension. They had comparatively smaller femur section aspect ratios (p < 0.005). They showed longer posterolateral condyle width (PLCW), anterior condyle mediolateral dimension (FRACML), anterolateral condyle height (ALCH), and femur resection anterior condylar mediolateral (FRACML) dimension (p < 0.005). They showed larger distal femur aspect ratio and resection aspect ratio (FAR, FRAR, p < 0.005). All selected prostheses showed ML undercoverage under similar AP dimensions, and ML undersizing of Attune systems was more obvious in three femoral prostheses.

CONCLUSION

The distal femur morphological change of HA patient is shown as smaller AP dimension, narrow posterior condyle spacing, lower and shallower trochlear, thinner anterior condyle, wider and lower intercondylar notch and higher posterior-lateral condyle. The selected prostheses showed ML undercoverage under similar AP dimensions. This typical morphological tendency of the distal femur seems to warrant consideration in the process of knee joint prosthesis upgrading.

Femoral anterior condyle height decreases as the distal anteroposterior size increases in total knee arthroplasty: A comparative study

PURPOSE

The anterior flange height of the current femoral component increases with an increasing distal femoral anteroposterior dimension. During total knee arthroplasty (TKA), we have observed that a large femur may have a thinner anterior condyle, whereas a small femur may have a thicker anterior condyle. The first purpose of this study was to examine whether the femoral anterior condyle height decreases as the distal femoral anteroposterior size increases and whether gender differences exist in anterior condyle height.

METHODS

A total of 1218 knees undergoing TKA intraoperative and computed tomography scans from 303 healthy knees were used to measure the anterior lateral condylar height (ALCH), anterior medial condylar height (AMCH), and the lateral anteroposterior (LAP) and medial anteroposterior (MAP) dimensions of distal femurs. The LAP and MAP measurements were used for adjustments to determine whether gender differences exist in anterior condyle heights. Linear regression analysis was performed to determine correlations between ALCH and LAP or between AMCH and MAP.

RESULTS

There were significant differences between males and females in ALCH in both the CT and TKA groups and AMCH in the CT group (all P<0.01). After adjusting for LAP and MAP, there were significant gender differences in the lateral and medial condylar heights in both groups (P<0.01). There were significant negative correlations between ALCH and LAP values and between AMCH and MAP values in both CT and TKA measurements, with the LAP and MAP values increasing as ALCH and AMCH decreased.

CONCLUSIONS

The results demonstrate that femoral anterior condylar height decreased with increasing anteroposterior dimension in both the medial and lateral condyle. In addition, this study also showed that anterior condylar heights are highly variable, with gender differences. The data may provide an important reference for designing femoral anterior flange thickness to precisely match the natural anterior condylar anatomy.

Diversity in Orthopaedic Surgery Medical Device Clinical Trials: An Analysis of the Food and Drug Administration Safety and Innovation Act

INTRODUCTION

Demographic factors contribute markedly to orthopaedic surgery outcomes. However, women and minorities have been historically excluded from clinical trials. The United States passed the Safety and Innovation Act (Food and Drug Administration Safety and Innovation Act [FDA-SIA]) in 2012 to increase study diversity and mandate reporting of certain demographics. The purpose of this study was to investigate demographic reporting and analysis among high-risk orthopaedic medical device trials and evaluate the effectiveness of the FDA-SIA in increasing diversity of study enrollment.

METHODS

The premarket approval database was queried for all original submissions approved by the Orthopedic Advisory Committee from January 1, 2003, to July 1, 2022. Study demographics were recorded. Weighted means of race, ethnicity, and sex were compared before and after FDA-SIA implementation with the US population.

RESULTS

We identified 51 orthopaedic trials with unique study data. Most Food and Drug Administration device trials reported age (98.0%) and sex (96.1%), but only 49.0% and 37.3% reported race and ethnicity, respectively. Only 23 studies analyzed sex, six analyzed race, and two analyzed ethnicity. Compared with the US population, participants were overwhelmingly White (91.36% vs. 61.63%, P < 0.001) with a significant underrepresentation of Black (3.65% vs. 12.41%, P = 0.008), Asian (0.86% vs. 4.8%, P = 0.030), and Hispanic participants (3.02% vs. 18.73%, P < 0.001) before 2013. The FDA-SIA increased female patient enrollment (58.99% vs. 47.96%, P = 0.021) but did not increase the enrollment of racial or ethnic minorities.

CONCLUSION

Despite efforts to increase the generalizability of studies within the FDA-SIA, orthopaedic medical devices still fail to enroll diverse populations and provide demographic subgroup analysis. The study populations within these trials do not represent the populations for whom these devices will be indicated in the community. The federal government must play a stronger role in mandating study diversity, enforcing appropriate statistical analysis of the demographic subgroups, and executing measures to ensure compliance.

LEVEL OF EVIDENCE

I.

Cartilage assessment using preoperative planning MRI for femoral component rotational alignment

BACKGROUND

Surgical planning of posterior referencing total knee arthroplasty (TKA) using computed tomography (CT) might lead to over-rotation of the femoral component because CT could not detect cartilage thickness of the posterior femoral condyle. The purpose of this study was to examine the rotational alignment difference of the femoral component between magnetic resonance imaging (MRI) and CT.

METHODS

For elderly varus osteoarthritic patients, 66 varus osteoarthritic knee patients that underwent primary TKA were selected. Twenty-seven young patients who underwent primary anterior cruciate ligament reconstruction were selected as control. After the transepicondylar axis (CEA), the surgical epicondylar axis (SEA) and the posterior femoral condylar line (PCL) were drawn on CT and on MRI at the same angles as CT. Then, the practical PCL was drawn on MRI considering the cartilage thickness (the cartilage PCL). The angle between the SEA and the cartilage PCL (the cartilage posterior condylar angle (PCA)) was measured as preoperative planning. To investigate the accuracy of preoperative MRI measurement, the cartilage thickness on posterior femoral condyles was directly measured during TKA.

RESULTS

The cartilage PCA for varus osteoarthritic patients averaged 1.3 ± 1.3°. The cartilage PCA was 1.8 ± 1.0° significantly smaller than the bone PCA (the PCA measured on CT). Meanwhile, the cartilage PCA was 0.2 ± 0.4° significantly larger than the bone PCA in young people. The preoperative angle measurement on MRI strongly correlated with the direct measurement of cartilage thickness during TKA.

CONCLUSION

There was 1.8° of divergence between MRI and CT in varus osteoarthritic patients due to cartilage degeneration of the medial femoral condyle. Cartilage assessment using MRI was useful for femoral component rotational alignment.

Gender-Related Aspects in Osteoarthritis Development and Progression: A Review

Osteoarthritis (OA) is a common degenerative joint disease treated mostly symptomatically before approaching its definitive treatment, joint arthroplasty. The rapidly growing prevalence of OA highlights the urgent need for a more efficient treatment strategy and boosts research into the mechanisms of OA incidence and progression. As a multifactorial disease, many aspects have been investigated as contributors to OA onset and progression. Differences in gender appear to play a role in the natural history of the disease, since female sex is known to increase the susceptibility to its development. The aim of the present review is to investigate the cues associated with gender by analyzing various hormonal, anatomical, molecular, and biomechanical parameters, as well as their differences between sexes. Our findings reveal the possible implications of gender in OA onset and progression and provide evidence for gaps in the current state of art, thus suggesting future research directions.

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.

High and Varied Anterior Condyle of the Distal Femur Is Associated with Limited Flexion in Varus Knee Osteoarthritis

OBJECTIVE

This study aimed to evaluate variations in anterior condylar height (ACH) of the distal femur in varus knee osteoarthritis and evaluate the association between ACH and knee flexion.

DESIGN

Computed tomography (CT) images of 171 knees (143 patients; age 73.7 ± 8.3 years; 132 females, 39 males) with symptomatic primary knee osteoarthritis and varus alignment undergoing primary total knee arthroplasty, unilateral knee arthroplasty, or high tibial osteotomy were evaluated. Several other anatomic parameters were measured on CT or radiography. The ACH and knee flexion correlation was analyzed, and factors contributing to knee flexion were determined using multivariable regression analysis.

RESULTS

Medial ACH (mean, 8.1 mm; range, -2.8 to 19.9 mm) was smaller (P < 0.001) but more variable (F = 1.8, P < 0.001) than lateral ACH (mean, 10.7 mm; range, 3.6-18.3 mm). Medial ACH was moderately correlated with flexion (r = -0.44, 95% confidence interval [CI], -0.55 to -0.32), whereas lateral ACH was weakly correlated (r = -0.38; 95% CI, -0.50 to -0.25). On multivariable linear regression analysis of knee flexion, body mass index (B [partial regression coefficient] = -1.1), patellofemoral Kellgren-Lawrence grade (B = -4.3), medial ACH (B = -1.2), medial posterior condylar offset (B = 1.2), age (B = -0.4), and varus alignment (B = -0.6) remained significant independent variables (adjusted R² = 0.35).

CONCLUSIONS

Wide variation and anteriorization of the anterior condyle of the distal femur was observed in advanced osteoarthritis, as an independent determinant of limited knee flexion.

Anthropometric measurements of non-arthritic knees in an Egyptian population: an MRI-based study

Background

Knee anthropometric characteristics were evaluated for different ethnicities; however, data from North African populations are deficient. The primary aim was to investigate the Egyptian knees’ anthropometric characteristics as a representative of North African populations. Secondary aims are as follows: (1) to study the anthropometric gender difference, (2) to compare results with other ethnic groups, and (3) to study the mismatch in comparison to geometric characteristics of modern TKA implant designs.

Methods

Two hundred normal knee MRI scans (100 females and 100 males, aging from 18 to 60) were obtained for analysis. Linear measurements (anteroposterior (AP), mediolateral (ML), and aspect ratio (AR)) of the planned cut surface of the distal femur (f) and the proximal tibia (t) were evaluated.

Results

A significant difference between both sexes was found, males had larger measurements in anteroposterior [fAP: 60.97 ± 3.1 vs 54.78 ± 3.3 (P < 0.001), tAP: 46.89 ± 3.0 vs 41.35 ± 2.9 (P < 0.001)] and mediolateral [fML: 74.89 ± 3.2 vs 67.29 ± 3.7 (P < 0.001), tML: 76.01 ± 3.0 vs 67.26 ± 3.2 (P < 0.001)], the mean femoral and tibial AP and ML measurements were different from other ethnic groups. None of the seven studied TKA systems matched the largest ML or the smallest AP dimensions of the distal femur in the current study population.

Conclusion

A significant difference was found between males’ and females’ knee anthropometric characteristics. Some of the commonly used TKA implants in our area could not provide a perfect fit and coverage.

Trial registration

ClinicalTrials.gov identifier: NCT03622034, registered on July 28, 2018.

The patellofemoral morphology and the normal predicted value of tibial tuberosity-trochlear groove distance in the Chinese population

Background

Our objective was to obtain normal patellofemoral measurements to analyse sex and individual differences. In addition, the absolute values and indices of tibial tuberosity-trochlear groove (TT-TG) distances are still controversial in clinical application. A better method to enable precise prediction is still needed.

Methods

Seventy-eight knees of 78 participants without knee pathologies were included in this cross-sectional study. A CT scan was conducted for all participants and three-dimensional knee models were constructed using Mimics and SolidWorks software. We measured and analysed 19 parameters including the TT-TG distance and dimensions and shapes of the patella, femur, tibia, and trochlea. LASSO regression was used to predict the normal TT-TG distances.

Results

The dimensional parameters, TT-TG distance, and femoral aspect ratio of the men were significantly larger than those of women (all p values < 0.05). However, after controlling for the bias from age, height, and weight, there were no significant differences in TT-TG distances and anterior-posterior dimensions between the sexes (all p values > 0.05). The Pearson correlation coefficients between the anterior femoral offset and other indexes were consistently below 0.3, indicating no relationship or a weak relationship. Similar results were observed for the sulcus angle and the Wiberg index. Using LASSO regression, we obtained four parameters to predict the TT-TG distance (R² = 0.5612, p < 0.01) to achieve the optimal accuracy and convenience.

Conclusions

Normative data of patellofemoral morphology were provided for the Chinese population. The anterior-posterior dimensions of the women were thicker than those of men for the same medial-lateral dimensions. More attention should be paid to not only sex differences but also individual differences, especially the anterior condyle and trochlea. In addition, this study provided a new method to predict TT-TG distances accurately.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04454-8.

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.

No clinical benefit from gender-specific total knee replacement implants: a systematic review

Introduction: Total knee arthroplasty (TKA) remains the treatment of choice for severe osteoarthritis of the knee and nearly 60% of patients undergoing TKA are women. Females present three notable anatomic differences. Thus, gender-specific (GS) components were introduced to accommodate the females’ anatomic differences. No systematic review has been published since 2014. The aim of this study was to perform a recent systematic review of the literature to determine whether there is any clinical benefit of gender-specific implants compared to conventional unisex implants in total knee arthroplasty (TKA). Methods: This study included prospective randomized controlled trials (PRCTs) comparing clinical and radiological outcomes, and complications in TKA with gender-specific implants and conventional implants. All studies had a minimum follow-up of two years. Results: Three PRCTs published between 2010 and 2012 were included. These studies showed a low risk of bias and were of very high quality. We did not find superior clinical outcomes for gender-specific prostheses compared to conventional prostheses. However, gender-specific TKA reduced the number of patients with femoral component overhang compared to conventional TKA. Conclusion: In our systematic review, despite a lower overhang rate, gender-specific implants in female TKA showed no clinical benefit over standard unisex implants. Good clinical results with significant improvement were observed with both designs. There is a notable absence of new studies on this subject in recent years, and further research needs to be performed using various gender-specific implant designs to further define the role of gender-specific implants. Level of evidence: Systematic review, Level IV

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.

A greater reduction in the distal femoral anterior condyle improves flexion after total knee arthroplasty in patients with osteoarthritis

BACKGROUND

The effect of an anterior condylar height (ACH) change after total knee arthroplasty (TKA) is not well-known. The effect of an ACH change was evaluated on postoperative knee flexion, New Knee Society Scores (2011KSS), and patellofemoral contact force.

METHODS

The study included 101 knees that underwent TKA. The medial or lateral ACH was measured using pre-operative and postoperative computed tomography. Pearson correlation between the change in ACH and knee flexion was calculated. The determinant of the change in flexion was evaluated using multivariable linear regression. The association between ACH and 2011KSS was assessed. Using the cases with the three highest and three lowest pre-operative medial ACHs, computer simulation was performed to detect the changes in patellofemoral contact forces.

RESULTS

A postoperative reduction in ACH correlated with increased flexion at one year (medial ACH, R = 0.58; lateral ACH, R = 0.48). On multivariable linear regression, reductions in medial ACH (β = 1.7, P < 0.001) and pre-operative flexion (β = -0.3, P < 0.001) were associated with increased flexion. A decrease in ACH was associated with improvements in advanced activities (medial, R² = 0.06; lateral, R² = 0.08) in 2011KSS. On computer simulation, all three cases with reduced and increased medial ACHs showed decreased and increased patellofemoral contact forces, respectively.

CONCLUSIONS

A change in ACH was an independent predictor of knee flexion after TKA. Greater reduction in ACH was associated with improved flexion after TKA, whereas an increase in postoperative ACH may be a risk factor for flexion loss.

Medium-term Results Evaluation between Gender-Specific x Conventional Total Knee Arthroplasty Prostheses

Objective  To compare the postoperative functional result of total knee arthroplasty (TKA) with gender-specific prosthesis versus TKA with conventional prosthesis in a 5-year period.

Methods  Retrospective study with functional evaluation of 30 patients (15 patients from each group) using scores (Knee Injury and Osteoarthritis Outcome Score [KOOS], Western Ontario and McMaster Universities arthritis index [WOMAC], and The Knee Society Clinical Rating System [KSS]) and range of motion (ROM) as methods of assessment.

Results  The differences found between the score values and ROM were not statistically significant.

Conclusion  The gender-specific prosthesis presents functional results equal to those of conventional prosthesis after 5 years postoperatively.

Gender-related morphological differences in sulcus angle and condylar height for the femoral trochlea using magnetic resonance imaging

PURPOSE

This study aimed to elucidate the primary differences in trochlear morphology between men and women utilizing three-dimensional magnetic resonance image reconstruction of the femoral trochlea.

METHODS

Differences in anthropometric femoral trochlea data of 975 patients (825 women, 150 men) were evaluated. The following morphological parameters were measured at three flexion angles (15°, 30°, and 45°) of the femoral trochlea: the sulcus angle, condylar height, and the trochlear groove orientation and mediolateral groove position.

RESULTS

The sulcus angle was significantly greater in women than in men at 15° and 45° flexions (P < 0.05). However, there was no gender difference found in the sulcus angle at 30° flexion. Medial and lateral condylar height values were greater in men than in women for the three flexion angles (P < 0.01). The trochlear groove orientation and mediolateral groove position showed no gender-related differences.

CONCLUSIONS

Magnetic resonance image reconstruction demonstrated that measurement of trochlear morphology varied significantly between men and women. This study provides guidelines for the design of a suitable femoral component for total knee arthroplasty, considering gender-specific differences in the Korean population. Biomechanical guidelines for total knee arthroplasty in Korean individuals can be optimized using our finding, so as the risk of patellar dislocation to be decreased. Surgeons should be aware of gender differences in femoral trochlear to optimize choice of implant.

LEVEL OF EVIDENCE

III.

Gender differences in knee morphology and the prospects for implant design in total knee replacement

BACKGROUND

Morphological differences between female and male knees have been reported in the literature, which led to the development of so-called gender-specific implants. However, detailed morphological descriptions covering the entire joint are rare and little is known regarding whether gender differences are real sexual dimorphisms or can be explained by overall differences in size.

METHODS

We comprehensively analysed knee morphology using 33 features of the femur and 21 features of the tibia to quantify knee shape. The landmark recognition and feature extraction based on three-dimensional surface data were fully automatically applied to 412 pathological (248 female and 164 male) knees undergoing total knee arthroplasty. Subsequently, an exploratory statistical analysis was performed and linear correlation analysis was used to investigate normalization factors and gender-specific differences.

RESULTS

Statistically significant differences between genders were observed. These were pronounced for distance measurements and negligible for angular (relative) measurements. Female knees were significantly narrower at the same depth compared to male knees. The correlation analysis showed that linear correlations were higher for distance measurements defined in the same direction. After normalizing the distance features according to overall dimensions in the direction of their definition, gender-specific differences disappeared or were smaller than the related confidence intervals.

CONCLUSIONS

Implants should not be linearly scaled according to one dimension. Instead, features in medial/lateral and anterior/posterior directions should be normalized separately (non-isotropic scaling). However, large inter-individual variations of the features remain after normalization, suggesting that patient-specific design solutions are required for an improved implant design, regardless of gender.

Differences between sexes in the standard and advanced dimensioning of lateral meniscal allografts

BACKGROUND

There are many different methods of meniscal allograft measurements, which depend on individual tissue bank procedures. Due to the lack of a standardised method of dimensioning, measurement results may vary between individual cases. Consequently, allograft may be mismatched to the patient's knee anatomy. The purpose of this study was to measure four meniscal dimensions - two standard and two specific - and then compare them between sexes.

METHODS

Fourteen cadaveric lateral menisci (seven male and seven female) were scanned using a microtomography scanner. The obtained three-dimensional (3-D) models of each meniscus were analysed, taking into account four dimensions: circumference, width, central meniscal concavity, and total meniscal volume. The computer researcher was not informed of the original data of the meniscal samples until the calculations were completed.

RESULTS

No statistical between-sex differences were found in the standard dimensions. The specific dimensions, in turn, presented statistically significant between-sex differences (P>0.05). The mean difference between male and female total volume of the meniscus was equal to 36.59%, and the mean difference between male and female central meniscal concavity surface was equal to 31.22%.

CONCLUSION

This study found that sex should be taken into account as an important factor during a matching procedure performed by tissue bank staff.

Role of Patellofemoral Offset in Total Knee Arthroplasty: A Randomized Trial

Total knee arthroplasty occasionally does not meet expectations. This randomized clinical trial assessed the effect of restoration of the native patellofemoral height on clinical outcomes. Group I underwent standard patellar bone resection; group II underwent modified patellar bone resection that adjusted the amount of anterior condylar bone removed and the anterior flange thickness. There were no differences in anterior knee pain, Western Ontario and McMaster Universities Arthritis Index scores, or Knee Injury and Osteoarthritis Outcome Score scores. Patellofemoral compartment height restoration versus patellar height alone does not appear to significantly reduce pain or improve function.

What Differences in Morphologic Features of the Knee Exist Among Patients of Various Races? A Systematic Review

BACKGROUND

Most TKA prostheses are designed based on the anatomy of white patients. Individual studies have identified key anthropometric differences between the knees of the white population and other major ethnic groups, yet there is limited understanding of what these findings may indicate if analyzed collectively.

QUESTION/PURPOSE

What are the differences in morphologic features of the distal femur and proximal tibia among and within various ethnicities?

METHODS

A systematic review of the PubMed database and a hand-search of article bibliographies identified 235 potentially eligible English-language studies. Studies were excluded if they did not include morphology results or had insufficient data for analysis, were unrelated to the distal femur or proximal tibia, were conducted in pediatric patients or those undergoing unicondylar knee arthroplasty, or bone surface measurements were obtained for trauma products. This left 30 eligible studies (9050 knees). Study quality was assessed and reported as good, fair, or poor according to the NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Morphometric data for the distal femur and proximal tibia were available for four ethnic groups: East Asian (23 studies; 5543 knees), white (11 studies; 3111 knees), Indian (three studies; 283 knees), and black (three studies; 113 knees). Although relatively underrepresented, the knees from the Indian and black studies were maintained for hypothesis-generating purposes and to highlight crucial gaps in the data. The two key dimensions for selecting a suitable implant based on a patient's unique anatomy-AP length and mediolateral (ML) width-were assessed for the femur and tibia, in addition to aspect ratio, calculated by dividing the ML width by the AP length. Study measurement techniques were compared visually when possible to ensure that each pooled study conducted a similar measurement process. Any significant measurement outliers were reviewed for eligibility to determine if the measurement techniques and landmarks used were comparable to the other studies included.

RESULTS

White patients had larger femoral AP measurements than East Asians (62 mm, [95% CI, 57-66 mm] vs 59 mm, [95% CI, 54-63 mm]; mean difference, 3 mm; p < 0.001), a smaller femoral aspect ratio than East Asians (1.20, [95% CI, 1.11-1.29] vs 1.25, [95% CI, 1.16-1.34]; mean difference, 0.05; p = 0.001), and a larger tibial aspect ratio than black patients (1.55, [95% CI, 1.40-1.71] vs 1.49, [95% CI, 1.33-1.64]; mean difference, 0.06; p = 0.005).

CONCLUSIONS

This analysis uncovered differences of size (AP height and ML width of the femur and tibia) and shape (tibial and femoral aspect ratios) among knees from white, East Asian, and black populations. Future research is needed to understand the clinical implications of these discrepancies and to provide additional data with underrepresented groups.

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.

Tibiofemoral joint subchondral surface conformity: Individual variability with race and sex-specific trends

BACKGROUND

Femoral and tibial subchondral surface morphology has been extensively studied to aid in anatomically correct total knee arthroplasty (TKA) implant design. Emphasis has been placed on shape variations in individual bones, and person-to-person variability in joint conformity has been overlooked. The purpose of this study is to 1) determine individual variability in key measures of tibiofemoral joint conformity, and 2) determine whether variability differs by sex or race.

METHODS

Laser-scanner-generated surface models of tibiofemoral joints were obtained from 165 archival skeletons (at death: age 28.8±7.6years; 85 African-American, 80 Caucasian, 86 men, 79 women). Ratios and correlations were determined among related femoral and tibial subchondral surface areas (SA), alignment, curvatures, and linear dimensions between opposing surfaces with stratification by race and sex.

RESULTS

Anterior-posterior length (R=0.80, p<0.001) and medial-lateral width (R=0.93, p<0.001) were the only linear measures that were highly correlated between the femur and tibia. Tibial and femoral surface areas were correlated among Caucasian men only (R=0.58, p<0.001; R<0.20), with a wide range of surface area ratios regardless of sex or race (SA ratio total sample: 2.32±0.39, range 1.36 to 3.62).

CONCLUSIONS

There is high individual variability in tibiofemoral joint conformity at the subchondral surface, and for some measures this variability is sex-or-race specific. Key measures of joint conformity including surface area, curvature, width, and depth covary weakly or not at all, and a wide range of TKA component sizes and shapes would be required to accurately replicate native joint conformity in most people.

The C-reactive protein level after total knee arthroplasty is gender specific

PURPOSE

Laboratory diagnostics are part of the routine before and after operations. In all specialist surgical disciplines, including orthopaedic surgery, the acute-phase protein CRP is used to detect inflammatory processes, especially infections. The potential influence of patient gender on the postoperative course of CRP after TKA implantation is still unclear. In order to achieve a more precise evaluation of the complication-free general CRP course after TKA, the objective of the present study is to test the hypothesis that the p.o. course and level of CRP is gender specific in the first 10 days after TKA.

METHODS

A total of 1068 consecutive patients who had been treated with a unilateral primary cemented total knee replacement due to primary osteoarthritis of the knee over a 36-month period were retrospectively included in the study. For all patients, the preoperative CRP value and the postoperative course of CRP from postoperative days 1-10 were recorded and tested for gender specificity.

RESULTS

On days 2-5 and 7-8 after surgery, men had significantly higher CRP values than women. The maximum difference was 45 mg/L on the fourth p.o. day (men 170 mg/L, women 125 mg/L, p = 0.019).

CONCLUSION

The present study was able to show, for the first time, that the complication-free course of CRP in the first 10 days after TKA implantation is gender specific. The impact of the finding on diagnostic is that the gender-specific CRP course provides a more precise evaluation of the complication-free course of CRP after TKA. These results have clinical relevance to the interpretation of postoperative CRP values in order to avoid unnecessary investigations such as puncture or surgical care in female and male patients with uncomplicated TKA. Level of evidence Diagnostic study, III.

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.

Intraoperative anthropomorphic study of anterior femoral condyles compared with sizing of femoral arthroplasty

PURPOSE

The present study was designed to compare the dimensions of the anterior femoral condyle with those of the anterior component flange using intraoperative morphological data.

METHODS

Overall, 1227 knees in 962 patients were included in this study. The height of the anterior lateral/medial condylar height (ALCH/AMCH) was measured and compared between men and women. These morphological data were compared with the dimensions of the chosen component for each patient. The lateral/medial anterior femoral offset was calculated, and the over-/understuffing rates were compared between men and women.

RESULTS

The median ALCH in men was 8.5 mm (6.5, 10.0 mm) versus 7.0 mm (6.0, 9.0 mm) in women. The median AMCH in men was 4.0 mm (2.5, 6.0 mm) versus 3.5 mm (2.5, 6.0 mm) in women. There was a significant difference between the genders with respect to ALCH (p < 0.05). When the dimensions of the component were compared with those of the native knee, the anterior lateral flange height was smaller than the native knees (1.3 mm in male, 0.7 mm in female), but the anterior medial flange height was larger than the corresponding condyle (1.8 mm in male, 1.8 mm in female). A significant difference was observed between the genders with respect to the ideal fit rate of ALCH (p < 0.01).

CONCLUSION

The results demonstrate that gender differences exist in the anterior lateral condyles of knees. The anterior flange of component is not designed to precisely reproduce normal trochlear anatomy.

LEVEL OF EVIDENCE

II.

Lateral Femoral Condyle Flap: An Alternative Source of Vascularized Bone From the Distal Femur

PURPOSE

To elucidate the vascular anatomy of the superolateral geniculate artery (SLGA) and its supply to the periosteum of the lateral femoral condyle (LFC) and to provide guidelines for flap design and describe an illustrative case.

METHODS

Thirty-one fresh cadaveric limbs were dissected. The vascular anatomy of the SLGA and its distal branches to skin, muscle, and periosteum were identified. Fluoroscopic images were taken during continuous perfusion of a radiopaque contrast dye into the SLGA. Intra-arterial injections of latex rubber were performed in 12 cadaver limbs. The vascular territory was traced from the SLGA to its distal branches, and surrounding soft tissues were dissected.

RESULTS

The SLGA originated from the popliteal artery 4.9 ± 1.2 cm (range, 2.8-7 cm) from the knee joint and its pedicle diameter was 1.8 ± 0.5 mm (range, 1-3 mm). SGLA pedicle-specific fluoroscopic angiography demonstrated a dense filigree of vessels over the lateral distal femur. Arterial latex injections confirmed that the SLGA supplied the periosteum of the LFC and distal femur shaft. The proximal-most extent of periosteal perfusion was 11.7 ± 2.1 cm (range, 9.3-14.1 cm) from the knee joint. The average pedicle length of LFC osteoperiosteal flaps was 4.8 ± 0.9 cm (range, 3.5-6.3 cm).

CONCLUSIONS

The LFC flap consistently demonstrated almost 12 cm of femur length perfusion based on the SLGA pedicle. The anatomy of this flap enables chimeric designs combining soft tissue, bone, and cartilage.

CLINICAL RELEVANCE

The vascularized LFC flap is an option for reconstruction of osseous defects of the upper extremity.

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.

No sex differences exist in posterior condylar offsets of the knee

BACKGROUND

Restoration of posterior condylar offset during TKA is believed to be important to improving knee kinematics, maximizing ROM, and minimizing flexion instability. However, controversy exists regarding whether there are important anatomic differences between sexes and whether a unisex knee prosthesis can restore the anatomy of knees in males and females.

QUESTIONS/PURPOSES

The purposes of our study were to determine if sex differences exist in (1) absolute posterior condylar offset size, (2) relative posterior condylar offset size in relation to total condylar height, and (3) posterior condylar articular cartilage thickness.

METHODS

We identified 100 patients (50 men and 50 women) without a history of arthritis, deformity, dysplasia, osteochondral defect, fracture, or surgery about the knee who had MRI of the knee performed. All MR images were ordered by primary care medical physicians for evaluation of nonspecific knee pain. Using a previously described three-dimensional MRI protocol, we measured posterior condylar offset, total condylar height, and articular cartilage thickness at the medial and lateral femoral condyles and compared values to evaluate for potential sex differences. We performed an a priori power calculation using a 2-mm posterior condylar offset difference as the minimum clinically important difference; with 2n = 100, our power to detect such a difference was 99.8%.

RESULTS

Compared with females, males had greater medial posterior condylar offset (30 mm [95% CI, 29.3-30.7 mm; SD, 2.5 mm] vs 28 mm [95% CI, 27.0-28.5 mm; SD, 2.7 mm]), lateral posterior condylar offset (27 mm [95% CI, 26.2-27.3 mm; SD, 2.0 mm] vs 25 mm [95% CI, 24.2-25.4 mm; SD, 2.0 mm]), medial condylar height (63 mm [SD, 3.2 mm] vs 57 mm [SD, 4.4 mm]), and lateral condylar height (71 mm [SD, 5.2 mm] vs 65 mm [SD: 4.0 mm]) (all p values < 0.001). However, the mean ratio of medial posterior condylar offset to medial condylar height (0.48 [SD, 0.04] vs 0.49 [SD, 0.05]) and the mean ratio of lateral posterior condylar offset to lateral condylar height (0.38 [SD, 0.05] vs 0.38 [SD, 0.03]) were not different between sexes (p = 0.08 and p = 0.8, respectively). There also was no sex difference in mean articular cartilage thickness at either condyle (medial condyle: 2.7 mm [SD, 0.5 mm] vs 2.5 mm [SD, 0.7 mm]; lateral condyle: 2.6 mm [SD, 0.6 mm] vs 2.5 mm [SD, 0.8 mm]) (both p values ≥ 0.1).

CONCLUSIONS

Results of our study showed that knees in males exhibited greater posterior condylar offset and greater total condylar height at the medial and lateral femoral condyles, however, there were no sex differences in the ratio of posterior condylar offset to condylar height at either condyle.

CLINICAL RELEVANCE

These findings suggest that a unisex knee prosthesis design is adequate to recreate the normal posterior condylar offsets for men and women.

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.

The surgical epicondylar axis is a consistent reference of the distal femur in the coronal and axial planes

PURPOSE

Various rotational landmarks including the surgical epicondylar axis (SEA) are used for preoperative planning and intra-operative reference of total knee arthroplasty (TKA) in the axial plane. The aim of the study was to elucidate the relationships between the SEA and other femoral anatomical landmarks, including the mechanical axis, distal and posterior knee joints, the trochlear groove, and the anterior femoral condyle, in both the coronal and axial planes.

METHODS

Angular and linear measurements were taken of sixty femora using Orthomap3D, which has a tool to analyse computed tomography image data that makes it possible to measure three-dimensional distances and angles precisely. The inter- and intra-observer reliabilities of these measurements were evaluated. Comparisons were made according to height, weight, body mass index, and gender.

RESULTS

The angle between the mechanical axis and the SEA was 90.2° (95% CI 90.0°-90.4°). There was a significant correlation for each linear measurement between the SEA and the distal/posterior knee joint line and for each linear measurement between the SEA and the anterior medial/lateral femoral condyle. A significant difference was observed between genders in the linear measurements. Significant correlations were found between height and weight and linear parameters.

CONCLUSION

Knowledge of the relationships between the SEA and other femoral anatomical landmarks is useful in preoperative planning, intra-operative landmark, and postoperative assessment of TKA. The SEA is a consistent parameter of femoral alignment in the coronal plane and a stable reference for femoral rotation in the axial plane.

LEVEL OF EVIDENCE

III.

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.

[Early results of gender-specific posterior stabilized total knee arthroplasty without patella resurfacing]

INTRODUCTION

To address anatomical gender differences in total knee arthroplasty (TKA) specific total knee prostheses have been developed for women. Potential benefits of these modified prostheses are currently under debate. The present study investigated whether the modified design features bring benefits compared to uni-sex TKA.

METHODS

A total of 80 prospectively blinded and randomized patients underwent implantation of unilateral TKAs with NexGen LPS Gender Solutions (Zimmer, Warsaw, USA, group gender-specific GS prosthesis, n = 40) or NexGen LPS Flex (Zimmer, Warsaw, USA, control group standard prosthesis ST, n = 40) The follow-up was carried out 10 days and 6 weeks postoperatively. Clinical data and the subjective assessment of quality of life were evaluated using the Knee Society Clinical Rating System (KSS), the short form 36-item health survey (SF-36) and the Western Ontario and McMaster Universities OA Index (WOMAC).

RESULTS

The two groups showed equal values in KSS, SF-36 and WOMAC preoperatively and ten days postoperatively the GS group reached an average KSS knee score of 62.6 ± 16.1 points (ST group 56.9 ± 14.7, p = 0.184) and a functional score of 28.5 ± 12.1 (ST group 24.3 ± 15.3, p = 0.082). In the overall score the GS group reached 91.1 ± 24.1 points (ST group 81.0 ± 27.1, p = 0.104). The GS group reached a knee score of 85.5 ± 14.4 points (ST group 77.8 ± 16.8, p = 0.03) and a functional score of 68.1 ± 20.7 points (ST group 62.3 ± 18.5, p = 0.185) 6 weeks postoperatively. In the overall score the GS group reached 153.7 ± 30.7 points (ST group 139.6 ± 32.4, p = 0.048). The analysis of SF-36 and WOMAC showed no significant differences at all time points. No evidence of loosening or migration was observed in both groups.

CONCLUSIONS

Based on the data presented, gender-specific TKA type NexGen LPS Gender Solutions has advantages in terms of early functional outcome. This result is not reflected in the patient satisfaction and is not considered to be clinically relevant.

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 analysis of the anterior femoral condyle geometry of the knee

BACKGROUND

No study has used 3-D anatomic knee models to investigate the gender differences in anterior femoral condyles. Therefore, this study aims to determine the morphologic differences between genders in anterior femoral condyles of the knees using 3-D anatomic knee models.

METHODS

Ninety-six male and sixty-five female 3D anatomic knee models were used to measure lateral and medial anterior condyle heights, anterior trochlear groove heights, and anterior condyle width, which were normalized by the anterior-posterior and medial-lateral dimensions of the knee, respectively. The shape of anterior condyle groove was also analyzed.

RESULTS

The mean lateral anterior condyle height, medial anterior condyle height and anterior condyle width of females were 6.6±1.8 mm, 2.0±2.3 mm, and 44.7±4.2 mm, respectively. These data were significantly smaller (p<0.05) than those of males (7.7±1.8 mm, 2.9±2.0 mm and 50.0±3.4 mm). However, after normalizing by the femur size, the aspect ratios had no gender differences. Both the ranges of lateral and medial condyle of females were significantly smaller than those of males, and the geometry curve of anterior condyle was different between genders.

CONCLUSION

Although the gender differences in anterior femoral condyle sizes no longer existed after normalization with the femur size, the shape and the peak position of anterior condyle groove still have gender differences. The data may have important implications on the current debate of gender-specific TKAs.

CLINICAL RELEVANCE

This study provides a better understanding of gender differences in anterior femoral condyle geometry.

Comparative study of sex differences in distal femur morphology in osteoarthritic knees in a Chinese population

OBJECTIVES

The purpose of this study was to investigate sex differences in resected distal femoral morphology in Chinese osteoarthritic knees.

METHODS

The study included 130 osteoarthritic knees in 65 men and 65 women in China. None had anterior femoral osteophyte or serious patellar femoral joint degeneration. The following were measured using computed tomography and analyzed to identify morphological differences according to sex in the resected distal femurs: anterior lateral condylar height (ALCH), anterior medial condylar height (AMCH), and mediolateral (ML) and anteroposterior (AP) dimensions. The ML/AP aspect ratio was calculated.

RESULTS

The average ALCH and AMCH were 8.2±1.8 mm, 3.1±1.5 mm for men and 7.4±1.7 mm, 3.6±1.5 mm for women. There were significant differences between men and women in ALCH values (P = 0.014) but not in AMCH values (P = 0.09). Women had smaller ML/AP aspect ratios than men for a given AP dimension. This indicated that the femoral ML dimension of a prosthesis with a given AP dimension may have overhang in women.

CONCLUSIONS

This study suggested that sex differences should be taken into account in the design of femoral prosthesis for Chinese men and women.

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.

Gender differences in tibio-femoral kinematics and quadriceps muscle force during weight-bearing knee flexion in vitro

PURPOSE

Females have a higher risk in terms of anterior cruciate ligament injuries during sports than males. Reasons for this fact may be different anatomy and muscle recruitment patterns leading to less protection for the cruciate- and collateral-ligaments. This in vitro study aims to evaluate gender differences in knee joint kinematics and muscle force during weight-bearing knee flexions.

METHODS

Thirty-four human knee specimens (17 females/17 males) were mounted on a dynamic knee simulator. Weight-bearing single-leg knee flexions were performed with different amounts of simulated body weight (BW). Gender-specific kinematics was measured with an ultrasonic motion capture system and different loading conditions were examined.

RESULTS

Knee joint kinematics did not show significant differences regarding anteroposterior and medial-lateral movement as well as tibial varus-valgus and internal-external rotation. This applied to all simulated amounts of BW. Simulating 100 N BW in contrast to AF50 led to a significant higher quadriceps overall force in female knees from 45° to 85° of flexion in contrast to BW 50 N. In these female specimens, the quadriceps overall force was about 20 % higher than in male knees being constant in higher flexion angles.

CONCLUSIONS

It is indicated by our results that in a squatting movement females compared with males produce higher muscle forces, suggesting an increased demand for muscular stabilization, whereas tibio-femoral kinematics was similar for both genders.

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.

Comparison of outcomes after bilateral simultaneous total knee arthroplasty using gender-specific and unisex knees

The clinical and radiologic results of a gender-specific total knee arthroplasty design were compared with those of a conventional unisex design in 50 female patients with bilateral osteoarthritis and a minimum follow-up of 2 years. Total knee arthroplasty was performed using a conventional unisex implant in one knee and a gender-specific implant in the other. Clinical outcomes, which included range of motion, Hospital for Special Surgery scores, and Western Ontario and McMaster Universities Osteoarthritis Index scores, were compared. In addition, patients' subjectively preferred sides were noted, and radiologic results based on implant positions, posterior offsets, anterior offsets, and patellofemoral alignments were evaluated. No significant differences were observed between range of motion, Hospital for Special Surgery score, or Western Ontario and McMaster Universities Osteoarthritis Index scores. Patient subjective preferences and radiologic results were also similar for both sides. In conclusion, gender-specific knees in female total knee patients showed no advantages over standard unisex knees in terms of clinical or radiologic outcomes.

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

We prospectively evaluated a consecutive series of 314 patients (265 females and 49 males) who underwent unilateral TKA and received an average of 2 years of follow-up. In all patients, a standard (STD) or a gender-specific (GS) femoral component was selected based on the presentation of intra-operative medio-lateral overhanging of the femoral cutting guide over the femoral condyle. There were no significant differences in the pre-operative parameters of both groups. At the last follow-up, both STD and GS groups had similarly improved KS clinical scores (92.9 vs. 92.1 points), function scores (89.5 vs. 89.7 points) and ROM (133.5° vs. 134.1°) with no difference in the rate of lateral retinacular release. The overall percentage of the GS component selection was 52.5% (165/314) and was significantly higher in female patients than male patients (60.8% vs. 8.2%, p<0.0001). In addition, selected GS prostheses increased significantly with increasing femoral size (25% for size C, 53% for size D, 86% for size E, and 100% for size F, respectively). There were no complications or early loosening related to the GS prosthesis. The mean post-operative limb alignment was 5.5° of the anatomical valgus with no difference between groups. We concluded that the GS femoral component did not provide better clinical outcomes than the standard femoral component; however, it provided surgical ease to minimize prosthesis overhanging in patients with narrow femoral condyles.

Mathematical reconstruction of human femoral condyles

There is a direct correlation between ligament function and the articulating surface of the normal knee, and changes to any of these structures can affect the other. This is also true for knee replacements, where the articulating surface is greatly changed compared to the natural knee. This study investigated the morphometry of healthy knees and proposes a method to predict original normal knee profiles. A variety of mathematical techniques are compared in terms of the accuracy with which they can represent the original knee joint geometry. Additionally, a method of predicting the irregular femoral condyle geometry for an individual knee is described by making use of the mathematical techniques presented, and the accuracy of this method is also investigated. The mathematical approach using B-splines provides flexibility and can accurately describe the complex geometry of the femoral condyles in both the sagittal and transverse planes. It was further found that the condyles are highly asymmetrical; therefore simpler methods cannot portray the condyles sufficiently and are especially inaccurate in representing the lateral condyle. The study proposes a method for predicting the geometry of the femoral condyles with good accuracy. The B-spline model showed best results.

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.

Gender differences in the anatomy of the distal femur

Recently, gender-specific designs of total knee replacement have been developed to accommodate anatomical differences between males and females. We examined a group of male and female distal femora matched for age and height, to determine if there was a difference in the aspect ratio (mediolateral distance versus anteroposterior distance) and the height of the anterior flange between the genders. The Hamann-Todd Collection provided 1207 skeletally mature cadaver femora. The femoral length, the anteroposterior height, height of the lateral and medial flanges and the mediolateral width were measured in all the specimens. The mechanical axis of the femur, the cut articular width and the aspect ratio were assessed. Statistical analysis of the effect of gender upon the aspect ratio and the lateral and medial flanges was undertaken, controlling for age, height and race. The mean aspect ratio of male femora was 1.21 (SD 0.07) and of female femora it was 1.16 (SD 0.06) (p < 0.001). There was no significant difference between male and female specimens in the mean size of the lateral flange (6.57 mm (SD 2.57) and 7.02 mm (SD 2.36), respectively; p = 0.099) or of the medial flange (3.03 mm (SD 2.47) and 3.56 mm (SD 2.32), respectively; p = 0.67). Future work in the design of knee prostheses should take into account the overall variability of the anatomy of the distal femur.

Method for selection of femoral component in total knee arthroplasty (tka)

A method is proposed enabling a surgeon to preoperatively determine the preeminent type and size of prosthesis, from those available, to be used in a particular patient undergoing knee replacement surgery. Parameters of healthy knee geometry were estimated by employing an unsupervised neural network. These estimated parameters were then applied in a χ(2) goodness of fit (GoF) test to determine which femoral prosthesis type and size delivers the most appropriate fit. This approach was used to determine the most suitable match of three implants for 34 different cases. Implant C performed the best and was the optimal fit in 59% of the cases, Implant A was the best fit in 38% of the cases and Implant B the best fit in 3% of the cases. This method shows promise in aiding a surgeon to select the optimal prosthesis type and size from an array of different conventional total knee replacements.

Ethnic and gender differences in the functional disparities after primary total knee arthroplasty

BACKGROUND

The benefits of TKA have been well documented. Whether these benefits apply equally across gender and ethnic groups is unclear. Given the underuse of TKA among certain demographic groups, it is important to understand whether gender or ethnicity influence pain and function after TKA.

QUESTIONS/PURPOSES

We determined (1) the influence of race, gender, and body mass index (BMI) on primary TKA functional scores and ROM before gender-specific implants; and (2) whether comorbidities influenced ROM and functional scores.

PATIENTS AND METHODS

We reviewed all 202 patients who underwent primary TKAs in 2004. We contacted 185 of the 202 patients, including 90 African-Americans, 87 Caucasians, four Asians, and four Hispanics (55 men, 130 women). Their average age was 66 years, and average BMI was 34.4 (range, 20-55). Knee Society scores (KSS) and ROM, patient demographics, and the Charlson Comorbidity Index (CCI) were recorded. Minimum followup was 24 months (average, 29.1 months; range, 24-60.3 months).

RESULTS

African-Americans had longer delays to presentation, higher BMI, and worse 2-year KSS. Women (all races) had higher BMI and worse preoperative flexion/arc ROM. African-American women had worse final ROM and had similar final gains in ROM (postoperative minus preoperative ROM) after controlling for confounders.

CONCLUSIONS

Gender and race affected functional KSS and ROM variables. The worse results experienced by African-American women may be attributable to a longer delay to presentation. However, the scores and motion were high for all subgroups, and underuse of TKA in women and African-Americans cannot be justified based on a perception of lesser functional gains.