Effect of femoral posterior condyle offset on knee joint function after total knee replacement: a network meta-analysis and a sequential retrospective cohort study

Background This study was conducted with the aim to compare the effect of posterior condyle offset (PCO) changes on knee joint function of patients following total knee replacement (TKR). Methods Electronic and manual searches were performed in the PubMed, Embase, and Cochrane Library databases from inception to September 2019. Network meta-analysis combined direct and indirect evidence to assess the weighted mean difference (WMD) and surface under the cumulative ranking curves (SUCRA) of different PCO changes (PCO ≤ − 2 mm, − 2 mm < PCO < 0 mm, 0 mm ≤ PCO < 2 mm and PCO ≥ 2 mm) on knee joint function after TKR. Then 103 OA patients undergoing unilateral TKR were included and the effect of PCO on the postoperative knee function was examined. Results Totally, 5 cohort studies meeting the inclusion criteria were enrolled in this analysis. The results of meta-analysis showed that patients with 0 mm ≤ PCO < 2 mm after TKR had a better recovery of joint function (flexion contracture: 28.67%; KS functional score: 78.67%; KS knee score: 75.00%) than the remaining three groups. However, the knee flexion (77.00%) of patients with PCO ≤ − 2 mm after TKR was superior to the other three groups. Retrospective study also revealed a significant correlation between PCO changes and the flexion contracture, further flexion and KS functional score of patients after TKR, in which each functional knee score of patients with 0 mm ≤ PCO < 2 mm was better than the others. Conclusion These findings suggest a close correlation between PCO magnitude and knee joint function after TKR and that 0 mm ≤ PCO < 2 mm is superior to other changes for joint function after TKR.

Morphometric Analysis and Three-Dimensional Computed Tomography Reconstruction of Thai Distal Femur

This study evaluates the distal femur morphology of the Thai population using a three-dimensional (3D) measurement method, measuring the distance between the triangular point of the femoral 3D model. The 3D model of 360 Thai femoral obtained from 180 volunteers (90 males, 90 females; range 20–50 years, average 32.8 years) was created using reverse engineering techniques from computed tomography imaging data. Using the 3D identified landmark method, the morphometric parameters evaluated included transepicondylar axis length (TEA), mediolateral length (ML), anteroposterior width (AP), medial anteroposterior width (MAP), lateral anteroposterior width (LAP), medial condyle width (MCW), lateral condyle width (LCW), intercondylar notch width (WIN), intercondylar notch depth (DIN), medial posterior condyle height (MPC), lateral posterior condyle height (LPC), femoral aspect ratio (ML/AP), lateral femoral aspect ratio (ML/LAP), and medial femoral aspect ratio (ML/MAP). The measured data were summarized for the analysis of an average value and standard deviation. Statistical analysis was performed using the independent samples t-test, unequal variances t-test, and linear regression. A p-value less than 0.05 (<0.05) was regarded as statistically significant and indicates strong evidence of the hypothesis. Additionally, the K-means clustering analysis of Thai distal femoral to the optimum size of the prosthesis with the correlation between ML length and AP width was performed. The results found that the morphometric parameters of the Thai male distal femur were significantly different and higher than those of Thai females, except for the ratio of ML/AP and ML/MAP. Comparatively, there was a significant difference between the specific size of Thai distal femur and that of the Korean population, which was also smaller than that for Caucasians. In addition, there was a mismatch between the distal femoral component sizing of knee prosthesis and what is available and commonly used in Thailand. At least six sizes of ML and/or AP should be recommended for the reasonable design of distal femoral prosthesis for covering the anatomy of Thais. These data are useful for predicting the morphometric parameters in forensic anthropology and provide basic data for the design of knee prostheses suitable for the Thai population.

A comparison of femoral component rotation after total knee arthroplasty in Kanekasu radiographs, axial CT slices and 3D reconstructed images

Objective To compare the posterior condylar angle measured with Kanekasu radiograph and 2D-CT with the gold standard 3D-CT following primary total knee arthroplasty (TKA). Methods Eighty-two knees with pain following TKA were included in this retrospective study. Two independent raters measured the anatomical and surgical posterior condylar angles twice on each Kanekasu radiograph and 2D-CT. These measurements were compared against the 3D-CT measurement. The intra- and interrater reliability of the Kanekasu radiograph and 2D-CT and the correlation with 3D-CT were calculated. Results The intra- and interrater reliability for measurements of the anatomical posterior condyle angle for the Kanekasu radiograph and the 2D-CT were excellent for both raters (0.85–0.92). For the less experienced rater 1, the intrarater reliability was significantly better for 2D-CT than Kanekasu radiograph for measuring both the surgical (p < 0.01) and anatomical posterior condyle angles (p < 0.05). For the experienced rater 2, the intrarater reliability was significantly better for Kanekasu radiograph than 2D-CT for measurement of the surgical posterior condyle angle (p < 0.05). The correlation with 3D-CT is higher in 2D-CT than in Kanekasu radiograph (p < 0.01). While the Kanekasu radiograph predicts the 3D-CT angle with 65.9%, 2D-CT can measure the true angle with 82.9% certainty. Conclusion Measurements using the anatomical transepicondylar axis are easier to replicate compared to the surgical transepicondylar axis. In comparison with the gold standard 3D-CT, 2D-CT showed a significantly higher correlation with 3D-CT than the Kanekasu measurements. If 3D-CT is available, it should be preferred over 2D-CT and Kanekasu view radiograph for femoral component rotation measurements.

Vertebrae Cervical of Egret (Egretta garzeta)

Egret is a long-necked bird that is often found in several regions in Indonesia. Egret have different neck bone structure than the other birds. When flying position the neck can be folded to from the letter S and when taking food the neck can bend down unt il it reaches the ground surface. His neck is strong and cannot be broken. Egret’s neck is composed of 13 vertebrae, each of which has a different structure and functions. In sections C5 to C7 have special characteristics. The sixth neck bone lengthens and the arrangement of muscle connections is elastic. To observe the cervical vertebrae in Egret done by cleaning all attached tissue then observed using a binocular stereo microscope wurh a magnification of 0.8x. The observations show that at C5 it has a longer segment than the others and has posterior condyle. Then in C6 there is a pivot point that allows the Egret to pull their necks into an S shape and allows Egret to push the head forward and catch prey at high speed (Wheler, 1929)

Increasing posterior condyle cut for high-flex knee prosthesis may injure popliteus tendon origin: a cadaveric study

Background: High-flex total knee prosthesis designs were proposed to improve flexion in total knee replacement (TKA). One of high-flex features is increasing posterior condyle cut which put popliteal tendon in higher risk of injury and may result in gap changes. Methods: Thirty-six popliteal origin sites from eighteen fresh cadavers were measured distances between the posterior rim of popliteal tendon origin and posterior border of the lateral femoral condyle (distance A) using digital “Vernier caliper”. The mean distances were compared to posterior condyle thickness of different prosthesis designs. Results: The mean of distance A on the right knee was 9.59 ±1.66 mm (6.03-12.70) while the mean of distance A on the left knee was 9.13 ± 1.78 mm (5.80-11.07). Posterior condyle thickness of the femoral prostheses varies upon their design and size from 7.4 to 10 mm for standard model and from 8.2 to 12.5 mm for high-flex design. Possibilities of popliteal tendon injury during posterior condyle bone cut were 16.7% to 66.7% for standard model and 27.8% to 97.2% for the high-flex design. Conclusion: High-flex TKA prosthesis with thicker posterior condyle relates to higher possibility of popliteal tendon origin injury compared to standard one.

QUANTITATIVE ANALYSIS OF THE VASCULARITY OF SKELETALLY IMMATURE FEMORAL CONDYLES: A CADAVER STUDY USING CONTRAST-ENHANCED MAGNETIC RESONANCE IMAGING

Background: The arterial supply to the chondroepiphysis is of paramount importance for proper nutrition and development. Previous animal studies had demonstrated that ischemic necrosis of the chondroepiphysis plays an important role in subsequent development of osteochondritis dissecans (OCD). Previous studies using susceptibility weighted imaging, a magnetic resonance image (MRI) sequence, demonstrated a pattern of disappearance of the arterial system over time at predilection sites for OCD lesions. The purposed of this study is to quantify distribution of the arterial perfusion in different zones of the immature distal femoral chondroepiphysis. Methods: We utilized 5 fresh frozen skeletally immature human cadaver knees (aged 0-6 months). The superficial femoral artery was cannulated proximal to the knee joint and major arteries distal to the knee joint were tied off. For volumetric analysis, comparisons were performed between contrast-enhanced and pre-contrast MRI. Regions of interest were developed to quantify the contrast enhancement in different zones of the chondroepiphysis, excluding the secondary ossification center. (Fig.1) Results: Quantitative MRI analysis demonstrated equivalent enhancement within the medial and lateral condyles in the 5 month and one of the 2 month specimens. The 0 month and 6 month specimens demonstrated greater enhancement in the medial condyle. One of the 2 months specimen demonstrated greater perfusion in the lateral condyle. The distal condyle analysis demonstrated equivalent enhancement in the 0 month, one of the 2 months and the 6 months specimens. The 5 month specimen demonstrated greater enhancement in the lateral distal condyle. The other 2 months specimen demonstrated greater enhancement in the medial distal condyle. The posterior condyle analysis demonstrated greater enhancement in the posterior lateral condyle in one of the 2 month specimen, and the 5 month and the 6 month specimens. The 0 month specimen demonstrated greater enhancement in the medial side. The other 2 month specimen demonstrated equivalent enhancement between medial and lateral side. Analyzing the medial condyle revealed equivalent enhancement in the medial and lateral zone in the 5 month and 6 month specimens. The 0 month specimen demonstrated greater enhancement laterally. Both 2 months specimens demonstrated greater enhancement in the medial side. Conclusion: This study expands the knowledge on the vascularity of the developing distal femoral chondroepiphysis, which may have an impact on our future understanding of OCD etiology, physeal growth, and peri-articular infections. The majority of the specimens demonstrated diminished perfusion in the posterior aspect of the medial femoral condyle when compare to the lateral posterior condyle. This is where the predilected area for the development of OCD lesions is located. Future studies in human and other mammals susceptible to knee OCD, along with the ongoing development of animal models of OCD will benefit from this information.