Bony and cartilaginous anatomy of the patellofemoral joint

The patella as the largest sesamoid bone of the human body forms the patellofemoral joint with the patellar groove of the femur. The patellofemoral joint is a complex articulation with high functional and biomechanical requirements. Several anatomical variants of both patella and the trochlea exist. Multiple clinical problems of the knee may be caused by anatomical and physiological abnormalities of this joint. Exact knowledge about the anatomy, the biomechanics and the function of the patellofemoral joint is therefore required to understand its wide range of pathology.     

Patellofemoral characteristics in patients with increased femoral anteversion

In this study, the association between increased femoral anteversion and the characteristics of the patellofemoral joint was investigated in adults. In 17 female control patients, the anteversion angle of the femoral neck measured 12°±8° and 11°±9° for the right and left side, respectively. The sulcus angle of the patellofemoral joint was 145°±10° and 146°±11°, the congruence angle 7.2°±14° and 7.8°±15°, and the lateral patellofemoral angle 5.9°± 6° and 5.7°±6°, respectively. In 15 female patients who were evaluated for clinical symptoms of increased femoral anteversion, the anteversion angle of the femoral neck was 30°±7° and 31°±8° degrees for the right and left side, respectively. The sulcus angle was 143°±8° and 147°±9°, the congruence angle 7.3°±12° and 7.1°±13°, and the lateral patellofemoral angle 6.4°±8° and 6.1°±7°, respectively. There was no correlation between the degree of femoral anteversion and the indices of the patellofemoral relationships. Thus, this study indicates that there is no association between increased femoral anteversion and abnormal patellofemoral characteristics.     

Is there a relationship between anterior knee pain and femoral trochlear dysplasia? Assessment of lateral trochlear inclination by magnetic resonance imaging

It may be very difficult to diagnose the pathology in patients with anterior knee pain. Patients with chronic anterior knee pain have been reviewed for the study. Our aim was to delineate the presence of subtle trochlear dysplasia by measuring lateral trochlear inclination (LTI) in axial magnetic resonance imaging (MRI) scans. While there were 109 knees in the study group with anterior knee pain (AKP), control group consisted of 74 knees without AKP. The LTI measurements were performed at the level of proximal cartilaginous area of trochlear groove in axial scans. The condition was termed to be trochlear dysplasia when LTI was below 11o. Parameters in both groups were statistically analyzed and compared for their association with LTI. There was no significant difference between LTI values of male and female subjects in each group. The mean LTI values in anterior knee pain and control groups were 17.32o and 21.5o, respectively, and the difference was statistically significant (P < 0.05). The ratio of knees with trochlear dysplasia was 16.5% in AKP group, which was only 2.7% in control. In the AKP group, the ratio of trochlear dysplasia was significantly high (P < 0.05). Although trochlear dysplasia has been generally detected in cases with patellar instability, this study revealed that the frequency of this finding in patients with other causes of anterior knee pain was also considerably high. Measurement of lateral trochlear inclination in axial MRI scans with radiologic assessment seems to be a valuable diagnostic criterion, especially in patients in whom etiology of anterior knee pain could not be identified.     

股骨髁髌股、胫股关节运动重叠接触区域测定

 目的描记膝关节运动过程中胫股、髌股关节在股骨髁关节面接触的重叠区域,明确其具体范围,为进一步研究膝关节髌骨、胫骨和股骨三者对应解剖关系以及生物力学特性,为优化股骨假体设计奠定基础.方法Instron 8501生物力学测试仪模拟生理状态下膝关节站立到下蹲屈膝过程,收集8具新鲜膝关节尸体标本,通过染色法分别描记髌股、胫股关节运动在股骨髁面的接触区域,标记其重叠范围.结果髌股、胫股关节在股骨髁关节面运动存在重叠接触区域,范围大致相当股骨髁面全髌股关节接触区域的开始于屈膝75°髌股接触区域的后部分.结论膝关节股骨假体的设计应该考虑股骨髁与髌股关节、胫股关节运动的重叠接触区域解剖特点.     

The femoral sulcus in total knee arthroplasty

The position of the femoral sulcus relative to the midline of the distal femoral resection in total knee arthroplasty (TKA) was studied to determine if centralized placement of the femoral component on the distal femur was justified in terms of aligning the prosthetic sulcus with the native femoral sulcus. The location of the femoral sulcus was studied in 112 consecutive patients undergoing TKA. The mean sulcus position was 0.7 mm lateral to the midline of the distal femoral resection (SD 1.4, 95% CI, 0.5–1.0 mm). However, the variation in sulcus positions ranged from 4 mm medial to 4 mm lateral to the midline. The mean sulcus position in valgus knees was 1.0 mm lateral to the midline (SD 1.8), and that in varus knees was 0.7 mm lateral to the midline (SD 1.2) (P = 0.501). It appears prudent to centre the femoral component on the native sulcus rather than the midline of the distal femoral resection, so as to ensure accurate alignment of the prosthetic sulcus with the native sulcus and to encourage normal patella tracking.     

Ultrasonography versus computed tomography in evaluation of the femoral trochlear groove morphology: a pilot study on healthy, young volunteers

The aim of the study was to verify the efficacy of ultrasonography (US) in evaluating the morphology of normal trochlea, especially the sulcus angle and the trochlear depth, in comparison with computed tomography (CT) (gold standard). The knees of 11 asymptomatic volunteers were subjected to US and CT evaluation of the same section planes and the results were compared. For statistical evaluation Spearman's correlation coefficient analysis was used. A statistically significant correlation was found between the two diagnostic procedures (sulcus angle: r = 0.820; trochlear depth: r = 0.802; Spearman's correlation coefficient) and the intra-observer variability for the US measurements (sulcus angle: r = 0.966; trochlear depth: r = 0.914; Spearman's correlation coefficient). The mean value of sulcus angle and trochlear depth was 132 ° and 5.6 mm, respectively, similar to those reported in the literature. We conclude that evaluation by US of both sulcus angle and trochlear depth is as reproducible and sensitive as that performed with CT. Received 22 January 1996; Revision received 11 April 1997; Accepted 22 May 1997     

Development of the femoral trochlear groove in rabbits with patellar malposition

Purpose

The geometry of the trochlear groove is considered to be an important determinant in the pathogenesis of the patellofemoral joint disorders. However, the effect of patellar position during the development of the femoral trochlear groove is unclear. This animal study aimed to investigate the relationship between the position of the patella and development of the femoral trochlear groove in growing rabbits.

Methods

Thirty-two knees from 16 rabbits were included in this study and were divided into two groups. First group consisted of the left knees and was used as a control group with no surgical interventions. The second group involved the right knees on which patellar tendon Z-plasty lengthening was performed to cause patellar malposition (patella alta) before 1 month of age. Computed tomographic (CT) evaluations of both knees were obtained when the animals were 1 month age before the surgical intervention and also at 6 months after the surgical intervention. Angle and depth measurements were acquired from the proximal, middle, and distal reference points along the femoral trochlear groove. After the CT scan acquisition at 6 months following the surgical procedures, rabbits were killed and additional measurements of the trochlear groove angles were performed manually.

Results

The mean middle and distal trochlear groove angles for the experiment group with patella alta were significantly higher compared to that of control group (p < 0.017). The increase in mean trochlear depth for the animals in the control group was found to be significantly higher compared to experiment group at the distal zone (p < 0.017).

Conclusion

Distal femoral groove with an inadequately positioned patella becomes more flattened and this may be a predisposing factor for patellar instability.

Level of evidence

Controlled laboratory study, Level II.     

Osteochondritis dissecans of the patellofemoral groove in athletes: unusual cases of patellofemoral pain

Five athletes who developed osteochondritis dissecans in the patellofemoral groove in the course of sports events at high school and college league level are described. They were male athletes complaining of anterior knee pain. When examining young people engaged in violent sports, it is well to remember that they might have osteochondritis dissecans in the patellofemoral groove. Clinically, four of the five patients under discussion were characterized by tight movements of the patella in a direction parallel to its transversal axis. X-ray studies in lateral projections and CT scans provided useful tools for definitive diagnosis, but AP radiography was no help in diagnosis. Release of a tight lateral retinaculum with or without drilling on the degenerated cartilage was effective in the treatment of osteochondritis dissecans of the patellofemoral groove in three of the four patients.     

股骨滑车轴作为全膝置换股骨旋转截骨轴线的可靠性评估

目的 研究股骨滑车轴( trochleare line,TL)作为全膝置换股骨假体旋转对位标志的可靠性. 方法 对89例正常成人膝关节CT扫描,在横断面图像上定位外科经股骨上髁轴(surgical transepicondylar axis,STEA)、股骨后髁轴(posterior condylar line,PCL)和TL.测量TL相对于STEA旋转的角度(TSA)、TL相对于PCL旋转的角度(TPA)、PCL相对于STEA旋转的角度(PCA),比较它们相对STEA的可靠性. 结果 TSA为(6.77±3.12)°、TPA为(4.22±2.64)°、PCA为(2.95±1.77)°,三种角度2×2析因分析性别、左右差异均无统计学意义(P＞0.05),秩和检验( HC=66.837,P＜0.01)结果 提示三组角度总体分布不同.TSA的变异系数较小,但标准差较大(3.12°).结论 TL仅可作为股骨假体旋转对位的辅助性标志.     

Sexing based on measurements of the femoral head parameters on pelvic radiographs

Background and aimPrevious studies have shown that the collo-diaphysial angle varies by race and sex in different populations. This study was performed to compare the femoral head parameters in the two sexes using pelvic radiography in Iranian adults during the August 2011 to August 2012 period.Materials and methodsThis cross-sectional study was done on 100 male and 100 female. After taking hip radiography, collo-diaphysial angle, maximum femoral head diameters and minimum femoral neck width were measured on both sides. Dominant hand, height, weight and body mass index were also recorded. Data were analyzed using SPSS software. Sex differences were tested using independent t-test and ROC curve.ResultsThe mean of the right and left maximum femoral head diameters and the minimum width of the femoral neck were significantly higher in men than in women (p < 0.001). The mean of the right collo-diaphysial angle of the femur was significantly higher in men than in women (p = 0.01), but there was no significant difference between the left collo-diaphysial angle in the two sex. The accuracy of sex prediction with the right and left maximum femoral head diameter was 78%. This figure is 77% for the right and left minimum femoral neck widths and 59% for the right collo-diaphysial angle.ConclusionIf only the proximal part of the femur is available, the sex can be predicted with a relatively high accuracy by taking a radiograph. In our study, the evaluation of the collo-diaphysial angle was not very helpful in sexing.     

髋关节置换后外伤性假体周围骨折的治疗

目的 探讨髋关节置换术后外伤致假体周围骨折的治疗方法。方法 回顾1998年6月～2003年6月收治的髋关节置换术后外伤致假体周围骨折患者5例，男2例，女3例；年龄52～7l岁，平均59岁。其中自行跌伤4例，交通伤l例。原实施髋关节置换术的原发病：3例为股骨头无菌性坏死，2例为陈旧性股骨颈骨折不愈合。施行全髋关节置换4例(5髋)，股骨头置换1例。外伤致髋关节骨折距原髋关节置换时间为1个月～17年。按Vancouver假体周围骨折分型标准，B型3例，C型2例。2例(B型l例，C型1例)采用牵引行保守治疗，2例(B型)应用加长柄关节翻修术及形状记忆合金锯齿臂环抱内固定器或钢缆捆扎治疗，l例(C型)应用解剖钢板内固定。结果 5例患者均得到随访，随访时间2个月～5年，骨折均愈合。无感染、骨折不愈合、内固定断裂等并发症发生。结论 髋关节置换术后，外伤致假体周围骨折的治疗比较困难，由于骨折部位、原置换假体有无松动、患者骨质量、身体状况的不同，选择的治疗方案也不同。Vancouver假体周围骨折分型标准及治疗方案是较好的指导原则。     

Magnetic resonance imaging of the femoral trochlea: evaluation of anatomical landmarks and grading articular cartilage in cadaveric knees

Purpose The purpose of the study was to define magnetic resonance imaging (MRI) findings before and after contrast medium opacification of the knee joint in cadaveric specimens to demonstrate anatomical landmarks of the trochlear surface in relation to the neighboring structures, and to evaluate different MRI sequences in the detection of cartilage defects of the trochlear and patellar surface of the knee. Materials and Methods The morphology and relationship of the proximal trochlear surface to the prefemoral fat of the distal femur were investigated by use of different MR sequences before and after intra-articular gadolinium administration into the knee joint in ten cadaveric knees. Anatomic sections were subsequently obtained. In addition, evaluation of the articular surface of the trochlea was performed by two independent observers. The cartilage surfaces were graded using a 2-point system, and results were compared with macroscopic findings. Results Of 40 cartilage surfaces evaluated, histopathologic findings showed 9 normal surfaces, 20 containing partial-thickness defects, and 11 containing full-thickness defects. Compared with macroscopic data, sensitivity of MR sequences for the two reviewers was between 17 and 90%; specificity, 75 and 100%; positive predictive value, 75 and 100%; negative predictive value, 20 and 100%, depending on patellar or trochlea lesions. Interobserver variability for the presence of disease, which was measured using the kappa statistic, was dependent on the MR sequence used between 0.243 and 0.851. Conclusion Magnetic resonance imaging sequences can be used to evaluate the cartilage of the trochlear surface with less accuracy when compared with the results of grading the articular cartilage of the patella.     

全髋人工关节置换术治疗股骨转子下骨折伴股骨头缺血性坏死

目的探讨股骨转子下骨折伴股骨头缺血性坏死经一次性全髋人工关节置换术的手术可行性和疗效。方法自1998年4月至2003年4月，对12例外伤性股骨转子下新鲜骨折伴股骨头缺血性坏死患者行一次性全髋人工关节置换术。其中男2例，女10例；年龄57～84岁，平均71．5岁。均伴有股骨头缺血性坏死。股骨头坏死按照Ficat分类，Ⅱ型3例，Ⅲ型5例，Ⅳ型4例。骨折类型按照AO分类均为A型长斜形股骨转子下骨折，按照Russell—Taylor分类均为IA型转子下骨折。均采用美国DePuy公司的Solution全涂层长柄股骨假体。结果1例发生术中再骨折，术后早期并发症有泌尿系统感染3例，深静脉栓塞4例。术后绝对卧床1个月。术后随访6～24个月，平均14．6个月。8例患者在术后4个月恢复步行能力，4例在1年后仍需扶拐步行。经美国特种外科医院（Hospital for Special Surgery，HSS）评分为84～92分，平均87分。结论伴股骨头缺血性坏死的老年患者发生股骨转子下骨折经一次性全髋人工关节置换术，虽然手术增加了一定的危险性，但可以减少二次手术的痛苦。     

Dependency of lower limb joint reaction forces on femoral version

BackgroundMusculoskeletal (MSK) models based on literature data are meant to represent a generic anatomy and are a popular tool employed by biomechanists to estimate the internal loads occurring in the lower limb joints, such as joint reaction forces (JRFs). However, since these models are normally just linearly scaled to an individual’s anthropometry, it is unclear how their estimations would be affected by the personalization of key features of the MSK anatomy, one of which is the femoral version angle.Research QuestionHow are the lower limb JRF magnitudes computed through a generic MSK model affected by changes in the femoral version?MethodsWe developed a bone-deformation tool in MATLAB (shared at https://simtk.org/projects/bone_deformity) and used it to create a set of seven OpenSim models spanning from 2˚ femoral retroversion to 40˚ anteversion. We used these models to simulate the gait of an elderly individual with an instrumented prosthesis implanted at their knee joint (5th Grand Challenge dataset) and quantified both the changes in JRFs magnitude due to varying the skeletal anatomy and their accuracy against the correspondent in vivo measurements at the knee joint.ResultsHip and knee JRF magnitudes were affected by the femoral version with variations from the unmodified generic model up to 17.9 ± 4.5% at the hip and 43.4 ± 27.1% at the knee joint. The ankle joint was unaffected by the femoral geometry. The MSK models providing the most accurate knee JRFs (root mean squared error: 0.370 ± 0.068 body weight, coefficient of determination: 0.757 ± 0.104, peak error range: 0.09−0.42 body weight) were those with femoral anteversion angle closer to that measured on the segmented bone of the individual.SignificanceFemoral version substantially affects hip and knee JRFs estimated with generic MSK models, suggesting that personalizing key MSK anatomical features might be necessary for accurate estimation of JRFs with these models.     

The internal calcar septum (femoral thigh spur) in computed tomography and conventional radiography

Objective. The femoral ”thigh spur”, a cortical septum in the region of the lesser trochanter of the human femur, was first described and named by the German anatomist Merkel in 1874, but it was never examined in detail. To evaluate the frequency and the shape of this structure, a combined anatomical and radiological study was performed using saw-cuts from specimens, high-resolution CT and conventional radiography. Design. Thirty human cadaveric femora of central European origin were analyzed by high-precision computed tomography (CT) using thin slices and high-resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of high-density bone formations and for three-dimensional imaging. Additionally three macerated femur specimens were cut exactly corresponding to the CT slices. The computed images were validated with the anatomical saw-cuts. Results. A dense trabecular ridge protruding endosteally from the posteromedial cortex was found in all femora. This cortical septum reaching from the femoral neck to the distal part of the lesser trochanter separated the femoral cavity from the cancellous bone inside the lesser trochanter. On conventional radiography the femoral thigh spur could be visualized best in the frog-lateral view of the hip. Conclusion. The internal calcar septum is a constant cortical structure. It should be recognized when radiographs or CT images of the proximal femur are interpreted. It could be of importance for metaphyseal fitting of an endoprosthetic stem. Received: 19 June 2000 Revision requested: 9 August 2000 Revision received: 5 October 2000 Accepted: 30 October 2000     

Kinematic and dynamic axial computerized tomography of the normal patellofemoral joint

Fourteen normal volunteers with no history suggesting previous or current knee pathology underwent axial computed tomographic examination of the patellofemoral joint. There were 11 men and 3 women, whose ages ranged from 10 to 46 years (average 25 years). Axial images were obtained at 0°, 10°, 20°, 30°, 40°, and 60° flexion both with and without contraction of the thigh muscles. Thus, 12 images were obtained for each individual. The CT scanner was focused at the midpatellar level prior to each image. Three measurements were made on 24 knees for each individual: congruence angle (CA), patellar tilt angle (PTA), and sulcus angle (SA). PTA increased slightly from 0° to 20°, and decreased slightly with more flexion (not significant, NS). The lower limit of PTA was usually 9°–10°: it was not lower than 7° in any knee position. Muscle contraction increased PTA slightly at each degree of flexion (NS). Mean CA was +18.3° (SD 20.8°) at 0°, which means that normal individuals may have CAs as high as +39° at full extension. There was a gradual decrease in CAs with knee flexion. The mean values became negative between 20° and 60° flexion. Contraction of the thigh muscles caused lateralisation of the patella except at 30° and 40° flexion. This lateral pull was statistically significant at full extension (P<0.01) and at 10° flexion (P<0.05). The SA decreased gradually as the flexion of the knee increased. Angles at 0°, 10°, and 20° flexion were significantly higher than those at 40° and 60° flexion (P<0.05). This study shows that CA, PTA and SA change depending on the degree of flexion of the knee, and that these angles show wide variations in the normal population. One should not rely on axial images taken at full extension, as this may erroneously lead to a diagnosis of subluxation in a normally tracking patella. The values obtained in this study may provide a basis for determining the type of patellar instability at different knee positions, and thus give a better profile or patellar tracking. This is a new concept. Besides, comparison of dynamic values obtained in this study with the ones in abnormal patellofemoral joints may also reveal useful information.     

神经母细胞瘤股骨远端干骺端骨转移全身骨显像分析

目的 评价全身骨显像半定量分析在神经母细胞瘤股骨远端干骺端骨转移中的应用价值.方法 45例经病理证实的神经母细胞瘤患儿,按骨髓涂片、X线片、CT、MRl或临床随访结果等将其分为股骨远端干骺端转移组和无转移组,术前或术后行99Tcm-MDPSPECT全身骨显像,以两种方法对其进行分析:①半定量分析法:对每个患儿双侧股骨远端干骺端及股骨骨下中段勾画ROI,并测定其平均计数,计算每个患儿干骺端/骨干的放射性比值;②视觉分析法:根据骨显像视觉分析诊断患儿是否存在股骨远端干骺端转移.比较这两种方法的诊断结果有无差异.结果 半定量分析法:转移组及无转移组干骺端/骨干的放射性比值差异有统计学意义(t=8.334,P＜0.01).半定量分析法诊断股骨远端干骺端转移的灵敏度、特异度、准确率、阳性预测值及阴性预测值分别为90.5％、95.7％、94.4％、86.4％及97.1％;视觉分析法分别为81％、100％、95.6％、100％及94.5％.两种方法诊断结果的差异无统计学意义(x2=0.68,P＞o.05).结论 放射性核素全身骨显像对神经母细胞瘤骨转移的诊断具有重要的价值,结合视觉分析法及半定量分析法可提高诊断的准确率.     

Referencing the sulcus line of the trochlear groove and removing intraoperative parallax errors improve femoral component rotation in total knee arthroplasty

Purpose

Firstly, to assess and compare the accuracy and reproducibility of the sulcus line compared to Whiteside’s line. Secondly, to assess the accuracy of intraoperative techniques for using the rotational alignment of the trochlear groove to set femoral rotation. Thirdly, to assess the reproducibility of a trochlear alignment guide which removes parallax errors that occur when projecting the sulcus line onto the surface of the femur. Finally, to measure the result of combining the geometrically accurate sulcus line and the posterior condylar axis.

Methods

Three surgeons measured eight rotational angles on ten cadaveric femora. This included Whiteside’s line, the sulcus line and the techniques in which they can be referenced during surgery.

Results

Relative to the anatomical epicondylar axis, the sulcus line (mean ?2.8°, SD 2.0°, range ?5.4° to 0.8°) had significantly lower variance (F = 5.16, p = 0.036) than Whiteside’s line (mean ?2.0°, SD 3.7°, range ?6.0° to 3.4°). The trochlear alignment guide produced the best results of the intraoperative techniques by maintaining the accuracy of the sulcus line and projecting it onto the distal cut surface of the femur without change in rotational angle.

Conclusion

The sulcus line is more accurate and reproducible than Whiteside’s line. Removing parallax errors during surgery improves femoral component rotation. The trochlear alignment guide produced accurate results suggesting that it may be beneficial in a clinical setting. Averaging the sulcus line and posterior condylar axis on the cut surface of the femur improved accuracy over the individual landmarks. Femoral component malrotation is a common cause of patient dissatisfaction and revision surgery. By isolating the rotational alignment of the trochlear groove using the sulcus line, and maintaining its accuracy with an intraoperative guide, we can decrease the risk of femoral component malrotation and improve patient outcomes.

     

The effect of heel-to-toe drop of running shoes on patellofemoral joint stress during running

BackgroundTraditional running shoes with heel-to-toe drops is thought to be a contributor to increased patellofemoral joint stress, which is proposed as a mechanism of patellofemoral pain.Research questionIs there an increase in patellofemoral joint stress when running in shoes with drops compared to running in shoes without a drop?MethodsLower limbs kinematics and ground reaction force were collected from eighteen healthy runners during over-ground running in shoes with 15 mm, 10 mm, 5 mm drops, and without a drop. Patellofemoral joint force and stress were calculated from the kinematic and kinetic data using a biomechanical model of the patellofemoral joint.ResultsThe peak patellofemoral joint stress was increased by more than 15% when running in shoes with 15 mm and 10 mm drops compared to running in shoes without a drop (p = 0.003, p = 0.001). The knee flexion angle was significantly increased when running in shoes with 15 mm, 10 mm and 5 mm drops (p = 0.014, p = 0.003, p = 0.002), the knee extension moment (p = 0.009, p = 0.002) and patellofemoral joint force (p = 0.003, p = 0.001) were increased when running in shoes with 15 mm and 10 mm drops, compared to running in shoes without a drop.SignificanceCompared to running in shoes without a drop, running in shoes with drops > 5 mm increase the peak patellofemoral joint stress significantly, which is mainly due to the increased knee extension moment.