Determination of cell-bound Fc receptors using a cell adherence test (CAT)

The determination of membrane-bound Fc receptors as rosette forming cells with antibody-coated erythrocytes (EA-RFC) is a tedious and time consuming method. Here, we describe a modification of the assay delineated by Eisenbarth et al. (J. Immunol. Methods (1980) 39, 387) for the detection of Fc receptors on cell surfaces. V-shaped microtiter plates were coated with an antigen (e.g., fluorescein isothiocyanate (FITC) coupled to bovine serum albumin (BSA] and subsequently with monoclonal anti-FITC antibodies of different isotypes. Cells to be tested were added, incubated for a short time or centrifuged immediately. Cells expressing FcR, became bound to the flanks of the V-shaped wells, whereas cells lacking the receptor were pelleted to the tip of the well. This cell adherence test (CAT) is independent of the agglutinating abilities of the antibodies, and since it is very fast and highly reproducible, large numbers of different cells can be screened for FcR expression. Anti-receptor antibodies can also be tested for their binding to FcR.     

On calculating the finite centre of rotation for rigid planar motion

In this technical note, a simpler least squares derivation for calculating the angle of rotation and finite centre of rotation of a set of marker points undergoing rigid planar rotation and translation is shown. The major advantage of the approach, other than the simple derivation, is the automatic inclusion of the calculation of a scaling factor between the two point sets - the calculation of which was not obvious in previous approaches [Challis J. Estimation of the finite center of rotation in planar movements. Med Eng Phys 2001;23(3):227-33, Spoor C, Veldpaus F. Rigid body motion calculated from spatial coordinates of markers. J Biomech 1980;13:391-3]. The final numerical calculations are similar to those of [Challis J. Estimation of the finite center of rotation in planar movements. Med Eng Phys 2001;23(3):227-33] and are trivial to implement. A matlab routine for computing the two quantities, and the scaling factor, is included. We demonstrate the method on a clinical example using lateral radiographs of the lumbar spine.     

MRI analysis for rotation of total knee components

PurposeThe aim of this study was to analyze rotation of total knee (TKA) implant components using magnetic resonance imaging (MRI) and to assess the reproducibility of results. It was hypothesized that rotation of both femoral and tibial implants would be reliably reproduced.MethodsA retrospective analysis of 55 MRI studies in subjects with painful TKA implants was conducted. There were 27 zirconium and 28 cobalt/chrome/molybdenum alloy (CoCrMo) femoral components in the group. The rotation angle of femoral and tibial components was measured and determined. Statistical analysis included tests for reliability, variance between implant groups, standard deviations and confidence intervals.ResultsThere was a sufficient inter- and intra-observer reliability determined for rotation in all implants. The inter-observer reliability was notably higher in the zirconium femur group with significant less variance and lower standard deviations than the CoCrMo femoral component comparison group. Standard deviations for femoral rotational analysis were within a clinically acceptable range. The standard deviations were considerably higher in the tibial component rotational analysis.ConclusionMRI analysis of the rotation of femoral implants after TKA allows good reproducibility, especially with review of zirconium implants. There is less reproducibility for tibial components related to the applied geometric method to quantify rotation and not to the MRI technique.     

An MRI study of the meniscofemoral and transverse ligaments of the knee

Our aim was to assess the anatomic localization, dimensions and incidence of the transverse and meniscofemoral ligaments, which can show anatomic variations or be mistaken for some pathologic conditions. In 100 healthy subjects (52 female, 48 male) whose ages ranged from 12 to 84 years, sagittal and coronal magnetic resonance images of the knee were obtained. There was at least one anterior or posterior meniscofemoral ligament in 82 cases. The anterior meniscofemoral ligament was present in 8 of the female and 4 of the male subjects. The posterior meniscofemoral ligament was found in 20 female and 22 male subjects. Both the anterior and posterior meniscofemoral ligaments were present in 15 female and 13 male subjects. The transverse ligament of knee was encountered in 19 female and 12 male subjects. In the females, average lengths of the anterior and posterior meniscofemoral ligaments were 9.87 +/- 4.79 mm and 25.60 +/- 5.50 mm, respectively. The corresponding values in the males were 11.11 +/- 2.57 mm and 28.80 +/- 5.49 mm, respectively. In the females, average width of the anterior and posterior meniscofemoral ligaments were 2.45 +/- 1.02 mm and 2.30 +/- 1.15 mm, respectively. The corresponding values in the males were 2.52 +/- 0.87 mm and 2.30 +/- 1.15 mm, respectively. On MRI assessment, in order to differentiate intra-articular lesions such as osteochondral and meniscal fragments or pseudotear of the lateral meniscus from the normal ligamentous anatomy of knee, the orientation and characteristic localization of the meniscofemoral ligaments should be taken into account. The French version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00276-002-0023-8.     

3．OTMRI 3D扫描对膝横韧带的观察

目的研究3．OTMRI3D扫描对膝横韧带的显示价值。方法回顾性分析利用3．0TMRI进行膝关节3D扫描的137例患者资料,共152个膝关节．除外严重外伤、肿瘤、关节感染及大量关节积液患者,共90人、100个膝关节纳入研究,平均年龄42岁．男性42位,女性48位。通过横断面及曲面重建观察并测算膝横韧带的出现率、长度、宽度、N-L分型、并测量其后缘与前交叉韧带胫骨附着点前缘的距离。结果共观察到膝横韧带54例,出现率54％;平均长度36．99mm（范围18．8-48．8mm）,平均宽度1．4mm（范围约0．80-2．53 mm）,N-L分型中,Ⅰ型、Ⅱ型、Ⅲ型所占比例分别为59．3％、25．9％、14．8％;其后缘与前交叉韧带胫骨附着点前缘的距离5．25mm（范围1．4-8．6mm）。结论3.0T MRI 3D扫描可从不同方位显示膝横韧带并对其解剖特点进行细致观察。     

Internal/external rotation moment arms of muscles at the knee: moment arms for the normal knee and the ACL-deficient knee

Knowledge of the three-dimensional balance of loads at the knee joint is required to adequately assess the treatment and rehabilitation of the malfunctioning knee. This report focuses upon the moment arms for the knee in internal/external (IE) rotation motion. It augments prior work that defined flexion/extension moment arms. Muscle excursions and angular motion of the lower leg during IE rotation were measured in 17 fresh-frozen hemi-pelvis specimens. Moment arms were calculated as the derivatives of excursion with respect to the angle. Rotational motion was performed for the normal and anterior cruciate ligament (ACL)-deficient knee. Of the 13 muscles measured at the knee, seven were significant contributors to IE rotation: the biceps femoris long and short head externally rotate opposite the gracilis, sartorious, semimembranosis, semitendonosus and popliteus, functioning as internal rotators. Moment arm magnitudes were greatest with the knee in a flexed position (internal [external] rotators peaked at 70° [90°] flexion). At 30° flexion, the IE rotation moment arm minima and maxima were 10.1–11.6, 6.8–9.0, 6.0–15.7, 8.2–14.1 and 0.0–10.4 mm for the semimembranosis, semitendonosus, gracilis, sartorius and popliteus, and 14.7–27.9 and 18.5–31.5 mm for the biceps femoris short and long, respectively. Moment arms for the ACL-deficient condition were significantly changed only at extremes of flexion–extension.     

Geometry of the facies articularis superior tibiae and rotation of the knee

Summary The authors studied the geometry of the facies articularis superior tibiae. The results of this study allowed to establish a relationship between the geometric features of these articular surfaces and rotation of the knee. The medial glenoid surface of the tibia can be likened to the base of an inclined ellipsoid while the lateral glenoid surface resembles part of an inclined elliptic torus. In the course of axial rotation of the knee, the medial intercondylar tubercle acts as a swivel whereas the lateral intercondylar tubercle is submitted to a movement of sliding. The data presented are based on the measurement of these articular surfaces in 30 anatomical specimens.

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Géométrie des surfaces articulaires supérieures du tibia et rotation du genou

Résumé Les auteurs étudient la géométrie du facies articularis superior tibiae. Ils établissent une concordance entre les résultats géométriques et la rotation du genou. La glène tibiale médiale est assimilable à la base d'une ellipsoïde inclinée et la glène tibiale latérale à un fragment de tore elliptique incliné. L'épine tibiale médiale a un rôle de pivot alors que l'épine tibiale latérale supporte un mouvement de glissement pendant la rotation axiale du genou. Des mensurations moyennes de ces surfaces ont été effectuées sur 30 pièces anatomiques.

     

Advanced functional biomechanical analysis of medial rotation knee arthroplasty

BackgroundThe Medacta GMK-Sphere total knee arthroplasty (TKA) is designed to mimic the movements and stabilimidty of a natural knee for optimal post-operative function and mobility. This study aimed to quantify the early functional outcome of patients with this implant.MethodsPatients due to undergo TKA to treat end-stage osteoarthritis were recruited into this study. Functional tests of knee range of motion (ROM), strength, and gait kinematics were carried out pre-operatively and one year post-operatively at routine clinics. Motion capture technology and a force transducer were used to collect all data. Normality tests were completed on all data sets to confirm normal distribution of the data, then paired t-tests were used to statistically compare the results. The level of significance was set as α = 0.05.ResultsSixty-three patients underwent pre-operative assessments; of which 30 returned one year post-operatively and consented to have follow-up testing. The operative knee was found to have poorer function than the contralateral knee pre-operatively (p < 0.05). Post-operatively, knee ROM significantly improved on the operative side to a mean of 116.1 ± 19.0. Gait kinematics also improved, especially in the frontal plane, but some abnormal traits remained in the sagittal plane. Knee strength decreased post-operatively.ConclusionsThe Medacta GMK-Sphere TKA improves knee range of motion sufficiently within the first postoperative year to allow patients to carry out most activities of daily living (> 110° knee flexion), but continued poor knee strength may limit their abilities to complete tasks which are more biomechanically demanding than walking.     

具备内外旋自由度的双侧减压辅具对膝关节生物力学的影响

目的针对传统膝关节辅具对人体下肢运动自由度限制的问题,为辅具提供一种顺应膝关节内外旋自由度的设计方案。方法通过在辅具中增加双自由度铰链的设计释放内外旋自由度,设置佩戴具备和不具备双自由度铰链的双侧减压辅具实验组、未佩戴辅具对照组进行步态及力学实验测试。结果步态过程中,相比不具备双自由度铰链的辅具,具备双自由度铰链的辅具对膝关节内外旋运动的限制较小,且辅具可以为人体膝关节提供一定牵引力。结论顺应内外旋自由度的设计方案可以有效减少双侧减压辅具对膝关节运动的限制。     

Pitfalls in assessing limb alignment affected by rotation and flexion of the knee after total knee arthroplasty: Analysis using sagittal and coronal whole-body EOS radiography

BackgroundInappropriate posture during radiographic assessment may lead to misunderstanding of postoperative alignment after total knee arthroplasty (TKA). The EOS system assesses coronal and sagittal alignment simultaneously. This study aimed to evaluate the effect of flexion and/or rotation on alignment, and identify the patterns of knee posture with serial follow-up using the EOS system.MethodsOne-hundred and fifteen patients of TKA and serial whole-body EOS were included. The hip–knee–ankle (HKA) angle in the coronal and sagittal planes, femoral component rotation ratio (FCR), tibial component rotation ratio (TCR), and fibular overlap ratio (FO) were measured immediately and at six months and one year postoperatively. Total and partial correlation, using flexion and rotation as a control variable was performed.ResultsThe mean HKA values and flexion immediately post-operation were different compared with the values noted at six months and one year postoperatively (for all, P < 0.05). The FCR and FO were correlated with the HKA angle during all periods (for both, P < 0.05). The Pearson correlation coefficients of the HKA angle with rotation parameters decreased when flexion was controlled.ConclusionsCombined rotation and flexion of the knee joint has a greater effect on coronal alignment compared with isolated flexion or rotation and was more frequently observed during the early postoperative period. Therefore, surgeons should be made aware of the potential knee rotation and flexion errors after TKA.     

A clinical method for locating the femoral head centre during total knee arthroplasty

Localisation of the femoral head centre (FHC) during total knee arthroplasty (TKA) is necessary when assessing the overall alignment of the leg using an extramedullary guide for the femur. On-table radiographs for this purpose are time consuming and inconvenient. We describe a clinical method for estimating the FHC: it is marked 1.5 cm lateral to the point where the femoral artery crosses the line joining the pubic tubercle and the anterior superior iliac spine. Using this method the estimated FHC was within 15 mm of the anatomic centre in 84% of cases, and within 24 mm in 99%. This translates into possible knee alignment errors of 2 degrees and 3 degrees, respectively. As alignment error of up to +/-3 degrees is compatible with satisfactory clinical results of TKA, our method provides useful approximation of the FHC. For greater accuracy however, an on-table radiograph is recommended.     

An automatic method for determining the centre of rotation of a mechanically scanned reflection UCT system

A method will be described for determining the centre of rotation of a mechanically scanned reflection ultrasound computed tomography system. It is based on the principle of obtaining opposing images of a test object containing many point targets. The method is automatic in the sense that the centre of rotation is calculated by a computer without the need for an operator to make direct measurements on the mechanical system. For the particular reflection UCT system described here, the centre of rotation is obtained in 3-5 min with a repeatability (+/-2 SD) of +/-0.3 mm. Ways in which even higher accuracy can be obtained are discussed. The basic principle of the method is applicable to any concentric imaging system for which a good approximation to an ideal point target can be produced.     

External rotation of the tibial component should be avoided in lateral unicompartmental knee arthroplasty

BackgroundLateral unicompartmental knee arthroplasty (UKA) leads to good clinical outcomes for isolated lateral osteoarthritis. However, the impact of the tibial component position on postoperative outcomes in lateral UKA is yet to be determined.PurposeThis study investigated the influence of tibial component malposition on clinical outcomes in lateral UKA.MaterialsThis was a retrospective study of 50 knees (mean age 73.5 years) who underwent lateral UKA between September 2013 and January 2019. The Oxford Knee Score (OKS), Knee Society Score – Knee (KSSK), and Knee Society Score – Function (KSSF) were evaluated. The coronal alignment, posterior slope of tibial component, tibial component rotation relative to Akagi’s line (angle α), and femoral anteroposterior (AP) axis (angle β) were measured postoperatively. The average follow up period was 2.3 (range, 1–4.9) years.ResultsClinical scores were significantly improved after lateral UKA. The mean coronal alignment was 0.9° ± 3.2° varus (range, 9.1° varus to 5.5° valgus), the mean posterior slope was 6.8° ± 3.8° (range, 0.8° to 14.8°). The mean α and β angles, were 4.1° ± 5.8° (range, −9.7° to 16.5°) and 6.7° ± 7.1° (range, −7.0° to 20.5°) external rotation. The angle α had significant negative correlations with postoperative OKS (r = −0.36), KSSK (r = −0.28), and KSSF (r = −0.39), and angle β had significant negative correlations with postoperative OKS (r = −0.34) and KSSK (r = −0.46).ConclusionExcessive external rotation of the tibial component could negatively influence the postoperative outcomes of lateral UKA.     

Effective measurement of knee alignment using AP knee radiographs

The gold standard for measuring knee alignment is mechanical axis determined using full-limb radiographs (FLR). Measurement of joint alignment using antero-posterior (AP) knee radiographs is more accessible, economical and involves less radiation exposure to the patient compared with using full-limb radiographs. The aim of this study was to compare and assess the reproducibility of knee joint axial alignment on full-limb radiographs and conventional AP knee radiographs. Knee alignment was measured in 40 subjects (80 knees) from the TwinsUK registry. Measurement of mechanical knee alignment was from FLR, and anatomic knee alignment from weight-bearing AP knee radiographs. Reproducibility was assessed by intra-class correlation coefficients and kappa statistics. Reproducibility of knee alignment for both methods was good, with intra-observer ICC's of 0.99 for both FLR and AP radiographs. The mean alignment angle on FLR was 178.9 degrees (SD 2.1, range 173-183 degrees ), and 179.0 degrees (SD 2.1, range 173-185 degrees ) on AP films. 58.8% of knees on FLR and 66.3% on AP films were of varus alignment. Good correlations were seen between results for FLR and AP radiographs, with ICC ranging from 0.87-0.92 for left and right knees, and kappa statistics of 0.65-0.74. Standard AP knee radiographs can be used to measure knee alignment with good reproducibility, and provide comparable results to those obtained from FLR. This will facilitate measurement of knee alignment in existing cohort studies to assess malalignment as a risk factor of incident OA, and in clinical practice.     

Determination of gender by measuring the size of the maxillary sinuses in computerized tomography scans

Background Identification of corpses is a difficult forensic procedure and it is mandated by laws and social rules. Comparison of ante mortem and post-mortem medical records, such as dental documents, plays an important role in the identification of corpses. However, typical identification methods may be inconclusive, especially when certain extreme post-mortem changes have developed. Gender has long been determined from the skull, the pelvis and the long bones with an epiphysis and a metaphysis in unknown skeletons. The aim of this study was to investigate whether the width, the length and the height of the maxillary sinuses could be used for determination of gender. Materials and Methods The width, the length and the height of the maxillary sinuses were measured in 127 adult patients who were admitted to the Department of Radiology for computed tomography scans of their sinuses. Of 127 patients, 62 (48.8%) were females and 65 (51.2%) were males. The width, the length and the height of the maxillary sinuses were measured in Computerized Tomography scans (Hitachi Radix Turbo computed tomography) when the patients were in prone position without sedation or contrast medium. The data were subjected to a discriminative analysis using the SPSS package program (Version 11.5). Results The discriminative analysis showed that the accuracy of maxillary sinus measurements—i.e. the ability of the maxillary sinus size to identify gender—was 69.4% in females and 69.2% in males. Conclusion Computerized Tomography measurements of maxillary sinuses may be useful to support gender determination in forensic medicine; however, with a relatively low-accuracy rate (less than 70%).     

MCL及ACL切断对膝内旋和外旋运动影响的实验研究

目的：研究膝内侧副韧带及前交叉韧带在膝旋转稳定性中的作用。方法：１４例膝关节，分为２组，分别切断内侧副韧带或前交叉韧带后，再切断另一韧带。分别测量切断前后的膝内旋外旋运动范围。结果：正常膝关节内旋外旋角度分别为２５．５°±４．８°及２１．４°±２．７°，两者差异显著。单纯切断前交叉韧带，对内、外旋无显著性影响；单纯切断内侧副韧带后，内旋运动范围有显著性增大，外旋也有显著性增大，当联合有前交叉韧带的切断时，对膝关节旋转运动影响更显著。结论：正常膝关节的内旋、外旋运动范围不等。前交叉韧带对内旋外旋无显著的限制作用；内侧副韧带是膝关节旋转运动的主要限制韧带     

Combined use of transverse and scout computed tomography scans to localize radioactive seeds in an interstitial brachytherapy implant

Various techniques have been developed to localize radioactive sources in brachytherapy implants. The most common methods include the orthogonal film method, the stereo-shift film method, and recently, direct localization from a series of contiguous CT transverse images. The major advantage of the CT method is that it provides the seed locations relative to anatomic structures. However, it is often the case that accurate identification and localization of the sources become difficult because of partial source artifacts in more than one transverse cut and other artifacts on CT images. A new algorithm has been developed to combine the advantages of using a pair of orthogonal scout views with the advantages of using a stack of transverse cuts. In the new algorithm, a common reference point is used to correlate CT transverse images and two orthogonal scout CT scans (AP and lateral). The radioactive sources are localized on CT transverse images. At the same time, the sources are displayed automatically on the two CT scout scans. In this way, the individual sources can be clearly distinguished and ambiguities arising from partial source artifacts are resolved immediately. Because of the finite slice thickness of transverse cuts, the longitudinal coordinates are more accurately obtained from the scout views. Therefore, the longitudinal coordinates of seeds localized on the transverse cuts are adjusted so that they match the position of the seeds on scout views. The algorithm has been tested on clinical cases and has proved to be a time saving and accurate method.     

Association of knee flexion angle after posterior-stabilized total knee arthroplasty with postoperative tibial external position relative to the femur and the extent of tibial internal rotation from knee extension to flexion

BackgroundThis study evaluated the relationship between preoperative and postoperative knee kinematics, moreover, investigated tibial rotational position and the extent of tibial internal rotation from knee extension to flexion as factors to obtain significant knee flexion after total knee arthroplasty (TKA).MethodsFifty-four patients (60 knees total; 15 males, 16 knees; 39 females, 44 knees) who underwent posterior-stabilized TKA using a navigation system were included. Intraoperative knee kinematics involving tibial rotational position relative to the femur and the extent of tibial internal rotation were examined at two time points: 1) after landmarks registration (pre-TKA) and 2) after skin closure (post-TKA). The relationship between the knee flexion angle at one year postoperatively and intraoperative tibial rotational position, or the extent of tibial rotation among several knee flexion angles calculated with a navigation system were investigated.ResultsThe postoperative knee flexion angle was positively associated with the preoperative flexion angle and intraoperative knee kinematics at post-TKA involving tibial external position relative to the femur at knee extension and the extent of tibial internal rotation from extension to 90° of flexion or to maximum flexion. There was a positive relationship between the extent of tibial internal rotation at pre-TKA and that at post-TKA.ConclusionsThe intraoperative kinematics of the extent of tibial internal rotation at post-TKA was influenced by that at pre-TKA. The greater external position of the tibia relative to the femur at knee extension and the greater extent of tibial internal rotation at post-TKA might lead to good knee flexion angle.     

Investigation of morphotypes of the knee using cluster analysis

BackgroundObjects that manifest in several characteristic shapes, or morphotypes, are typically caused by some hidden variable. For example, the gender of a person influences the width of their pelvis. This is important when reconstructing natural shapes, e.g., in knee implant design. The aim of this study was to identify such morphotypes.MethodsThis work investigated the shapes of roughly 1000 knee joints acquired from computed tomography, including the distal femur and proximal tibia. Two comprehensive feature sets were utilized to describe the bone shapes, one based on morphological measurements and the other on statistical shape model (SSM) weights. We normalized the data by size and performed a cluster analysis with different algorithms, namely k-means and high dimensional data clustering. The clusters were evaluated using several metrics.ResultsThe data showed a low tendency to form clusters. Only one of 12 experiments slightly exceeded the thresholds for actual clusters suggested by the literature. k-Means outperformed high dimensional data clustering in all cases.ConclusionAfter anisotropic normalization by size, which removes size and aspect ratio related differences, the data exhibited no morphotypes. This showed that there are no relevant hidden variables, e.g., gender, body type or ethnicity, which influence the shape of the knee joint. Instead, knee shape is highly individual. Investigating the three-dimensional shape, variations occur for a wide range of different shape parameters, not just for anterior–posterior and mediolateral size.