全膝关节置换术的假体旋转不良的CT分析

目的应用CT技术测量全膝关节置换术股骨假体和胫骨假体旋转角度,探讨假体旋转性和髌股关节并发症之间的关系。方法以股骨髁上轴和胫骨结节为参考点,对股骨假体和胫骨假体的旋转角度进行测量,并比较了20例功能良好膝关节和30例产生髌股关节并发症的膝关节的假体旋转性。结果髌股关节并发症组的假体存在过度内旋,其内旋度数和值与髌股关节并发症的严重程度成正相关。轻度假体内旋(1°～4°)导致髌骨倾斜和轨迹外移;中度假体内旋(3°～8°)导致髌骨半脱位;重度假体内旋(7°～17°)导致早期的髌骨脱位和晚期的髌骨置换失败。功能良好组的假体外旋10°～0°。结论在机械轴线正常时,假体的内旋放置可能是导致髌股关节并发症的主要原因;利用CT扫描图像,行假体旋转度测量可用于术中以指导手术,术后也可以作为是否需要翻修的评价指标。     

Using real‐time MRI to quantify altered joint kinematics in subjects with patellofemoral pain and to evaluate the effects of a patellar brace or sleeve on joint motion

Abnormal patellofemoral joint motion is a possible cause of patellofemoral pain, and patellar braces are thought to alleviate pain by restoring normal joint kinematics. We evaluated whether females with patellofemoral pain exhibit abnormal patellofemoral joint kinematics during dynamic, weight‐bearing knee extension and assessed the effects of knee braces on patellofemoral motion. Real‐time magnetic resonance (MR) images of the patellofemoral joints of 36 female volunteers (13 pain‐free controls, 23 patellofemoral pain) were acquired during weight‐bearing knee extension. Pain subjects were also imaged while wearing a patellar‐stabilizing brace and a patellar sleeve. We measured axial‐plane kinematics from the images. Females with patellofemoral pain exhibited increased lateral translation of the patella for knee flexion angles between 0°and 50° (p = 0.03), and increased lateral tilt for knee flexion angles between 0° and 20° (p = 0.04). The brace and sleeve reduced the lateral translation of the patella; however, the brace reduced lateral displacement more than the sleeve (p = 0.006). The brace reduced patellar tilt near full extension (p = 0.001), while the sleeve had no effect on patellar tilt. Our results indicate that some subjects with patellofemoral pain exhibit abnormal weight‐bearing joint kinematics and that braces may be effective in reducing patellar maltracking in these subjects. Published by Wiley Periodicals, Inc. J Orthop Res 27: 571–577, 2009     

Dynamic activity dependence of in vivo normal knee kinematics

Dynamic knee kinematics were analyzed for normal knees in three activities, including two different types of maximum knee flexion. Continuous X‐ray images of kneel, squat, and stair climb motions were taken using a large flat panel detector. CT‐derived bone models were used for model registration‐based 3D kinematic measurement. Three‐dimensional joint kinematics and contact locations were determined using three methods: bone‐fixed coordinate systems, interrogation of CT‐based bone model surfaces, and interrogation of MR‐based articular cartilage model surfaces. The femur exhibited gradual external rotation throughout the flexion range. Tibiofemoral contact exhibited external rotation, with contact locations translating posterior while maintaining 15° to 20° external rotation from 20° to 80° of flexion. From 80° to maximum flexion, contact locations showed a medial pivot pattern. Kinematics based on bone‐fixed coordinate systems differed from kinematics based on interrogation of CT and MR surfaces. Knee kinematics varied significantly by activity, especially in deep flexion. No posterior subluxation occurred for either femoral condyle in maximum knee flexion. Normal knees accommodate a range of motions during various activities while maintaining geometric joint congruency. © Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:428–434, 2008     

The Quadriceps Angle and its Relation to Femoral Torsion

In 29 patients with patellofemoral complaints paired values of Q-angle and internal hip rotation were determined. In addition the patellar height index of Insall & Salvati (1971) was calculated from measurements on lateral radiographs of the knees.

Both Q-angle and internal hip rotation were significantly higher in women than in men and there was a statistically significant correlation between these two measurements. There was no significant correlation between Q-angles and patellar height indexes.

As external hip rotation can generally be taken as a measure of internal femoral torsion, these findings favour the hypothesis of a torsional malalignment syndrome of the patellofemoral joint.     

Optimizing femoral component rotation in total knee arthroplasty.

Femoral component rotation is important in total knee arthroplasty to optimize patellofemoral and tibiofemoral kinematics. More recently, the epicondylar axis has been cited as the definitive landmark for femoral component rotation. However, there are few studies to support the validity of this rotational landmark and its effect on the patellofemoral and tibiofemoral articulations. In the current study, a total knee arthroplasty was done in 11 knees from cadavers. The knees were tested with various femoral component rotations from 5 degrees internal rotation to 5 degrees external rotation referenced to the epicondylar axis and to the posterior femoral condyles. Each knee acted as its own internal control. The knees were actively ranged from 0 degrees to 100 degrees by a force on the quadriceps tendon in an Oxford knee simulator. Three-dimensional kinematics of all three components were measured whereas a multiaxial transducer imbedded in the patella measured patellofemoral forces. Femoral component rotation parallel to the epicondylar axis resulted in the most normal patellar tracking and minimized patellofemoral shear forces early in flexion. This optimal rotation also minimized tibiofemoral wear motions. These beneficial effects of femoral rotation were less reproducibly related to the posterior condyles. Rotating the femoral component either internal or external to the epicondylar axis worsened knee function by increasing tibiofemoral wear motion and significantly worsening patellar tracking with increased shear forces early in flexion. Based on the current study, the femoral component should be rotationally aligned parallel to the epicondylar axis to avoid patellofemoral and tibiofemoral complications.     

The Quadriceps Angle and its Relation to Femoral Torsion

In 29 patients with patellofemoral complaints paired values of Q-angle and internal hip rotation were determined. In addition the patellar height index of Insall & Salvati (1971) was calculated from measurements on lateral radiographs of the knees.

Both Q-angle and internal hip rotation were significantly higher in women than in men and there was a statistically significant correlation between these two measurements. There was no significant correlation between Q-angles and patellar height indexes.

As external hip rotation can generally be taken as a measure of internal femoral torsion, these findings favour the hypothesis of a torsional malalignment syndrome of the patellofemoral joint.     

Is cartilage thickness different in young subjects with and without patellofemoral pain?

OBJECTIVE: To determine the differences in load-bearing patellofemoral joint cartilage thickness between genders. To determine the differences in load-bearing cartilage thickness between pain-free controls and individuals with patellofemoral pain. METHODS: The articular cartilage thickness of the patella and anterior femur was estimated from magnetic resonance images in 16 young, pain-free control subjects (eight males, eight females) and 34 young individuals with patellofemoral pain (12 males, 22 females). The average age of all subjects was 28+/-4 years. The cartilage surfaces were divided into regions approximating the location of patellofemoral joint contact during knee flexion. The mean and peak cartilage thicknesses of each region were computed and compared using a repeated-measures Analysis of Variance. RESULTS: On average, males had 22% and 23% thicker cartilage than females in the patella (P < 0.01) and femur (P < 0.05), respectively. Male control subjects had 18% greater peak patellar cartilage thickness than males with patellofemoral pain (P < 0.05); however, we did not detect differences in patellar cartilage thickness between female control subjects and females with patellofemoral pain (P = 0.45). We detected no significant differences in femoral cartilage thickness between the control and pain groups. CONCLUSIONS: Thin cartilage at the patella may be one mechanism of patellofemoral pain in male subjects, but is unlikely to be a dominant factor in the development of pain in the female population.     

Computational approach to correcting joint instability in patients with recurrent patellar dislocation

Patellar dislocation is a debilitating injury common in active adolescents and young adults. Conservative treatment after initial dislocation is often recommended, but almost half of these patients continue to suffer from recurrent dislocation. The objective of this study was to compare preoperative patellofemoral joint stability with stability after a series of simulated procedures, including restorative surgery to correct to pre-injury state, generic tibial tubercle osteotomy, patient-specific reconstructive surgery to correct anatomic abnormality, less invasive patient-specific surgery, and equivalent healthy controls. Three-dimensional, subject-specific finite element models of the patellofemoral joint were developed for 28 patients with recurrent patellar dislocation. A 50 N lateral load was applied to the patella to assess the lateral stability of the patellofemoral joint at 10° intervals from 0° to 40° flexion. Medial patellofemoral ligament reconstruction, along with reconstructive procedures to correct anatomic abnormality were simulated. Of all the simulations performed, the healthy equivalent control models showed the least patellar internal–external rotation, medial–lateral translation, and medial patellofemoral ligament restraining load during lateral loading tests. Isolated restorative medial patellofemoral ligament reconstruction was the surgery that resulted in the most patellar internal–external rotation, medial–lateral translation, and medial patellofemoral ligament reaction force across all flexion angles. Patient-specific reconstruction to correct anatomic abnormality was the only surgical group to have non-significantly different results compared with the healthy equivalent control group across all joint stability metrics evaluated. Statement of clinical significance: This study suggests patient-specific reconstructive surgery that corrects underlying anatomic abnormalities best reproduces the joint stability of an equivalent healthy control when compared with the pre-injury state, generic tibial tubercle osteotomy, and less invasive patient-specific surgery. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:768-776, 2020     

Hip Pain after Distal Femoral Derotational Osteotomy for a Patient with Patellar Instability: A Case Report

Background

Increased torsional deformity of femur is one of the most important factors in recurrent patellofemoral instability. And distal femoral derotational osteotomy is an effective treatment option in patients with increased femoral torsional deformity. However, groin pain is a rare complication after femoral derotational osteotomy.

Case presentation

The patient was a 23-year-old female suffering from anterior knee pain and patellar instability in her left leg. Continuous CT scans of the hip, knee, and ankle were performed and the femoral anteversion was 44.99°. Considering the significant enlargement of the femoral internal torsion which may contribute most for dislocation of patella, we did a derotational osteotomy of distal femur. The anterior knee pain and patellar instability were resolved after surgery. The femoral internal torsion angle was corrected to 21.47°. But she developed left hip pain in the groin area which she had never encountered before 1 year after the surgery. We believed that the hip pain was closely related to the surgery. And the imaging and follow-up partly confirmed this.

Conclusions

The situation of the hip joint should be carefully evaluated before doing derotational osteotomy in recurrent patellofemoral instability and patient should be informed that derotational osteotomy may cause hip pain. Clinical studies are needed to further clarify the impact of derotational osteotomy on the hip.     

Contact areas and pressures between native patellas and prosthetic femoral components

Contact areas and pressures between native patellas and a prosthetic condylar design femoral component were measured at flexion angles of 30°, 60°, and 90°. These were compared to measurements obtained with a domed all-polyethylene patellar component. Mean native patellar contact areas were found to be fourfold greater than seen with the prosthetic patellar component. Contact stresses in the native patellas were below the yield strength of articular cartilage in 80% of the contact area. By contrast, stresses measured in the prosthetic patella exceeded the yield strength of ultrahigh molecular weight polyethylene in 64% of the measured contact area. Contact areas and stresses were not significantly effected by flexion angle. Although contact areas and stresses reflect only a part of the dynamics of the patellofemoral articulation this information would support the selective retention of the native patella in total knee arthroplasty.     

Three‐dimensional patellar motion at the natural knee during passive flexion/extension. An in vitro study

Patellar maltracking may result in many patellofemoral joint (PFJ) disorders in the natural and replaced knee. The literature providing quantitative reference for normal PFJ kinematics according to which patellar maltracking could be identified is still limited. The aim of this study was to measure in vitro accurately all six‐degrees‐of‐freedom of patellar motion with respect to the femur and tibia on 20 normal specimens. A state‐of‐the‐art knee navigation system, suitably adapted for this study aim, was used. Anatomical reference frames were defined for the femur, tibia, and patella according to international recommendations. PFJ flexion, tilt, rotation, and translations were calculated in addition to standard tibiofemoral joint (TFJ) kinematics. All motion patterns were found to be generally repeatable intra‐/interspecimens. PFJ flexion was 62% of the corresponding TFJ flexion range; tilt and translations along femoral mediolateral and tibial proximodistal axes during TFJ flexion were found with medial, lateral, and distal trends and within 12°, 6 and 9 mm, respectively. No clear pattern for PFJ rotation was observed. These results concur with comparable reports from the literature and contribute to the controversial knowledge on normal PFJ kinematics. Their consistence provides fundamental information to understand orthopedic treatment of the knee and for possible relevant measurements intraoperatively. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1426–1431, 2009     

Radiographic evaluation of patellofemoral alignment in kinematically aligned total knee arthroplasty: A comparative study with mechanically aligned total knee arthroplasty

BackgroundKinematically aligned total knee arthroplasty (KA-TKA), in which femoral component is placed 3–5° of internal rotation relative to mechanically aligned (MA)-TKA, may have a potential risk of patellofemoral malalignment. This study aimed to assess patellofemoral alignment and compare the data between KA-TKA and MA-TKA, and the relationship with patellofemoral radiographic parameters and patient reported outcomes.MethodsAmong patients who underwent TKA in 2015 and 2016 in our institute, 28 KA-TKAs with a metal-backed patellar component were retrospectively assessed for patellofemoral alignment, and 28 MA-TKAs with a metal-backed patellar component served as controls. A year postoperatively, patellar tilt and shift at 30°, 60°, and 90° knee flexion were measured on Merchant views and compared between the two TKAs. Implant positioning in each patient was assessed based on preoperative CT images and correlations of femoral component positioning with patellar tilt/shift were assessed.ResultsPatellar shift at 30° flexion was significantly greater in KA-TKA than in MA-TKA (p = 0.04), whereas patellar tilt angle was comparable between the two TKAs. No statistical correlation was evident between femoral component positioning and patellar shift/tilt, regardless of knee flexion angle in the two TKAs. Knee Society Score 2011 at 1 year follow-up was comparable in all subcategories between the two TKAs.ConclusionRadiographic analysis of KA-TKA revealed lateral shift of the patella at 30° knee flexion at 1 year postoperatively, however patients with patellar shift were asymptomatic. Further long-term observation is required to examine the impact of KA-TKA on the patellofemoral complication.     

基于筋束骨理论铍针松解髌骨外侧支持带改善髌股关节应力集中的有限元分析

目的:在筋束骨理论指导下,基于膝关节有限元模型研究铍针松解髌骨外侧支持带改善髌股关节应力集中的机制,阐释铍针松解术改变髌骨运行轨迹及降低髌股关节压力的生物力学机制.方法:获取 1 名正常男性(年龄29 岁,身高171 cm,体重58 kg)膝关节CT 资料,从膝关节的三维有限元模型构建入手,经几何重建、逆向工程、网格划...     

The effect of built-in external femoral rotation on patellofemoral tracking in the genesis II total knee arthroplasty

External rotation of the femoral component during total knee arthroplasty (TKA) has been suggested to improve flexion space balancing and patellofemoral tracking. Incorporation of external rotation into the design of the femoral component offers an alternative method to achieve this goal. This study compared 150 TKAs performed with traditional external rotation of the femoral component on the distal femur with a similar group of 150 TKAs performed with an implant that incorporates 3 degrees of external rotation into the femoral component. Statistical improvements were noted in the latter group, with respect to the need for intraoperative lateral retinacular release and in postoperative patellar tracking. Incorporation of 3 degrees of external rotation into the design of the femoral component seems to improve the overall result of TKA, especially with respect to patellofemoral resurfacing.     

Patellofemoral joint contact area is influenced by tibiofemoral rotation alignment in individuals who have patellofemoral pain

STUDY DESIGN: Observational, cohort study. OBJECTIVES: To test the hypothesis that patellar alignment and tibiofemoral rotation alignment explain unique portions of variance in patellofemoral joint contact area in individuals with patellofemoral pain (PFP) and in pain-free control subjects. BACKGROUND: PFP has been proposed to result from increased patellofemoral joint stress due to decreased contact area. Patellar malalignment (lateral displacement and tilt) is believed to be the main contributor to decreased contact area. Recent studies suggest that transverse plane rotation of the femur and/or tibia may also contribute to decreased contact area. METHODS AND MEASURES: Twenty-one subjects with PFP (16 female, 5 male) and 21 pain-free subjects (14 female, 7 male) participated. Subjects underwent magnetic resonance imaging with the knee in full extension and the quadriceps contracted. Measures of patellofemoral joint contact area, lateral patellar displacement, patellar tilt angle, tibiofemoral rotation angle, and patellar width were obtained. Hierarchical multiple regression analyses were performed for each group using contact area as the dependent variable. The order of independent variables was patellar width, patellar tilt angle, and tibiofemoral rotation angle. To avoid multicolinearity, lateral patellar displacement was not included. RESULTS: In the PFP group, patellar width and tibiofemoral rotation angle explained 46% of the variance in contact area. In pain-free subjects, patellar width was the only predictor of contact area, explaining 31% of its variance. Patellar tilt angle did not predict contact area in either group. CONCLUSION: Addressing factors that control tibiofemoral rotation may be indicated to increase contact area and reduce pain in individuals with PFP. Future studies should investigate the contributions of patellar alignment and tibiofemoral rotation to patellofemoral joint contact area at a variety of knee flexion angles.     

Differences in patellofemoral kinematics between weight‐bearing and non‐weight‐bearing conditions in patients with patellofemoral pain

Patellar maltracking is thought to be one source of patellofemoral pain. Measurements of patellar tracking are frequently obtained during non‐weight‐bearing knee extension; however, pain typically arises during highly loaded activities, such as squatting, stair climbing, and running. It is unclear whether patellofemoral joint kinematics during lightly loaded tasks replicate patellofemoral joint motion during weight‐bearing activities. The purpose of this study was to: evaluate differences between upright, weight‐bearing and supine, non‐weight‐bearing joint kinematics in patients with patellofemoral pain; and evaluate whether the kinematics in subjects with maltracking respond differently to weight‐bearing than those in nonmaltrackers. We used real‐time magnetic resonance imaging to visualize the patellofemoral joint during dynamic knee extension from 30° to 0° of knee flexion during two conditions: upright, weight‐bearing and supine, non‐weight‐bearing. We compared patellofemoral kinematics measured from the images. The patella translated more laterally during the supine task compared to the weight‐bearing task for knee flexion angles between 0° and 5° (p = 0.001). The kinematics of the maltrackers responded differently to joint loading than those of the non‐maltrackers. In subjects with excessive lateral patellar translation, the patella translated more laterally during upright, weight‐bearing knee extension for knee flexion angles between 25° and 30° (p = 0.001). However, in subjects with normal patellar translation, the patella translated more laterally during supine, non‐weight‐bearing knee extension near full extension (p = 0.001). These results suggest that patellofemoral kinematics measured during supine, unloaded tasks do not accurately represent the joint motion during weight‐bearing activities. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:312–317, 2011     

Identifying alignment parameters affecting implanted patellofemoral mechanics

Complications of the patellofemoral (PF) joint remain a common cause for revision of total knee replacements. PF complications, such as patellar maltracking, subluxation, and implant failure, have been linked to femoral and patellar component alignment. In this study, a dynamic finite element model of an implanted PF joint was applied in conjunction with a probabilistic simulation to establish relationships between alignment parameters and PF kinematics, contact mechanics, and internal stresses. Both traditional sensitivity analysis and a coupled probabilistic and principal component analysis approach were applied to characterize relationships between implant alignment and resulting joint mechanics. Critical alignment parameters, and combinations of parameters, affecting PF mechanics were identified for three patellar designs (dome, modified dome, and anatomic). Femoral internal–external (I‐E) alignment was identified as a critical alignment factor for all component designs, influencing medial–lateral contact force and anterior–posterior translation. The anatomic design was sensitive to patellar flexion–extension (F‐E) alignment, while the dome, as expected, was less influenced by rotational alignment, and more by translational position. The modified dome was sensitive to a combination of superior–inferior, F‐E, and I‐E alignments. Understanding the relationships and design‐specific dependencies between alignment parameters can aid preoperative planning, and help focus instrumentation design on those alignment parameters of primary concern. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1167–1175, 2012     

Patellar osteotomy and Albee's procedure for dysplastic patellar instability

Four patients with symptomatic patellar instability and dysplasia of the patella and femoral trochlea had a dorsal closed-wedge intraarticular sagital plane patellar osteotomy and elevation of lateral femoral condyle-Albee's procedure. All patients also had a "Modified Fulkerson-Elmslie Trillat" osteotomy of the tibial tuberosity, along with a proximal realignment-lateral release and medial plication either prior to or at the time of index surgery of patellar osteotomy and Albee's procedure. At a mean follow-up of 1 (range 3 1/2–1) year, all patients had a stable patellofemoral joint. Mean loss of range of terminal flexion was 15° (range10–20°). All patients had residual patellofemoral pain, and the results at best can be described as fair. The results of this series are encouraging in this complex group of patients with patellofemoral trochlear dysplasia with patellar instability, and we do recommend this procedure as a palliative procedure in this group of patients.