MR imaging of osteochondral grafts and autologous chondrocyte implantation

Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte implantation (ACI) or matrix associated autologous chondrocyte transplantation (MACT) are becoming more common. MRI has become the method of choice for non-invasive follow-up of patients after cartilage repair surgery. It should be performed with cartilage sensitive sequences, including fat-suppressed proton density-weighted T2 fast spin-echo (PD/T2-FSE) and three-dimensional gradient-echo (3D GRE) sequences, which provide good signal-to-noise and contrast-to-noise ratios. A thorough magnetic resonance (MR)-based assessment of cartilage repair tissue includes evaluations of defect filling, the surface and structure of repair tissue, the signal intensity of repair tissue and the subchondral bone status. Furthermore, in osteochondral autografts surface congruity, osseous incorporation and the donor site should be assessed. High spatial resolution is mandatory and can be achieved either by using a surface coil with a 1.5-T scanner or with a knee coil at 3 T; it is particularly important for assessing graft morphology and integration. Moreover, MR imaging facilitates assessment of complications including periosteal hypertrophy, delamination, adhesions, surface incongruence and reactive changes such as effusions and synovitis. Ongoing developments include isotropic 3D sequences, for improved morphological analysis, and in vivo biochemical imaging such as dGEMRIC, T2 mapping and diffusion-weighted imaging, which make functional analysis of cartilage possible.     

Magnetic resonance observation of cartilage repair tissue (MOCART) for the evaluation of autologous chondrocyte transplantation: determination of interobserver variability and correlation to clinical outcome after 2 years

In an observational study, the validity and reliability of magnetic resonance imaging (MRI) for the assessment of autologous chondrocyte transplantation (ACT) in the knee joint was determined. Two years after implantation, high-resolution MRI was used to analyze the repair tissue with nine pertinent variables. A complete filling of the defect was found in 61.5%, and a complete integration of the border zone to the adjacent cartilage in 76.9%. An intact subchondral lamina was present in 84.6% and an intact subchondral bone was present in 61.5%. Isointense signal intensities of the repair tissue compared to the adjacent native cartilage were seen in 92.3%. To evaluate interobserver variability, a reliability analysis with the determination of the intraclass correlation coefficient (ICC) was calculated. An "almost perfect" agreement, with an ICC value >0.81, was calculated in 8 of 9 variables. The clinical outcome after 2 years showed the visual analog score (VAS) at 2.62 (S.D. +/-0.65). The values for the knee injury and osteoarthritis outcome score (KOOS) subgroups were 68.29 (+/-23.90) for pain, 62.09 (+/-14.62) for symptoms, 75.45 (+/-21.91) for ADL function, 52.69 (+/-28.77) for sport and 70.19 (+/-22.41) for knee-related quality of life. The clinical scores were correlated with the MRI variables. A statistically significant correlation was found for the variables "filling of the defect," "structure of the repair tissue," "changes in the subchondral bone," and "signal intensities of the repair issue". High resolution MRI and well-defined MRI variables are a reliable, reproducible and accurate tool for assessing cartilage repair tissue.     

Matrix-based autologous chondrocyte implantation for cartilage repair with HyalograftC: two-year follow-up by magnetic resonance imaging

OBJECTIVE: Monitoring of articular cartilage repair after matrix-associated autologous chondrocyte implantation with HyalograftC by a new grading system based on non-invasive high-resolution magnetic resonance imaging. PATIENTS AND METHODS: In 23 patients, postoperative magnetic resonance imaging (MRI) was performed between 76 and 120 weeks. In nine of these patients, five MRI examinations were performed at 4, 12, 24, 52 and 104 weeks after HyalograftC implant. The repair tissue was described with separate variables: degree of defect repair in width and length, signal intensity of the repair tissue and status of the subchondral bone. For these variables a grading system with point scale evaluation was applied. RESULTS: CONCLUSION: High-resolution MRI provides a non-invasive tool for monitoring the development of cartilage repair tissue following HyalograftC technology, shows a good correlation with clinical outcome and may help to differentiate abnormal repair tissue from a normal maturation process.     

MR cartilage imaging in assessment of the regenerative power of autologous peripheral blood stem cell injection in knee osteoarthritis

Background

Osteoarthritis (OA) describes an age-related, heterogeneous group of disorders characterized pathologically by focal areas of loss of articular cartilage in synovial joints, associated with varying degrees of osteophyte formation, subchondral bone change, and synovitis. Currently, cartilage repair remains a major challenge for physicians, being avascular with limited regenerative capacity. Stem cell therapy opened new horizons for hyaline cartilage repair. Peripheral blood stem cells (PBSC) due to their multi-lineage potential, immunosuppressive activities, and limited immunogenicity, were tried as an intra articular injection.

Aim of study

To find out the regenerative effect of repeated intra articular injections of autologous PBSC in knee joints of OA patients using MR cartilage imaging.

Methods

10 patients (3 males and 7 females) diagnosed with bilateral knee joints OA were included in this study, they underwent history taking, clinical examination and MR cartilage imaging using the semi-quantitative whole joint assessment score of knee for OA (MOAKS). Three intra articular injections of 8 ml of autologous PBSC in each knee were administered. Clinical and MRI assessments were repeated after 1 year.

Results

A significant reduction was seen in all parameters post injection. MR images analysis showed increased cartilage thickness in 65 knee joint compartments out of 160 affected compartments.

Conclusion

Limited good level of evidence showed that repeated intra-articular injections of autologous PBSC resulted in an improvement of the quality of articular cartilage repair and physical function as observed by MRI and clinical assessment.     

Disease-specific clinical problems associated with the subchondral bone

The subchondral bone is involved in a variety of diseases affecting both the articular cartilage and bone. Osteochondral defects in distinct locations and of variable sizes are the final results of different etiologies. These include traumatic osteochondral defects, osteochondritis dissecans, osteonecrosis, and osteoarthritis. Traumatic osteochondral defects are caused by osteochondral fractures, separating an osteochondral fragment that includes articular cartilage and both subchondral and trabecular bone from the joint surface. In osteochondritis dissecans, the disease originates in the subchondral bone and secondarily affects the articular cartilage. Location, stage, size, and depth of osteochondral lesions play a role in the treatment of traumatic osteochondral defects and osteochondritis dissecans. Surgical options include fragment refixation, transplantation of osteochondral autografts, or bone restoration by impacted cancellous bone grafts combined with autologous chondrocyte transplantation. An insufficiency fracture of the subchondral bone may be the initiating factor of what was formerly believed to be a spontaneous osteonecrosis of the knee (SPONK). Recent histopathological studies suggest that each stage of SPONK reflects different types of bone repair reactions following a fracture of the subchondral bone plate. Osteoarthritis is a disease that does affect not only the articular cartilage, but also the subchondral bone. Reconstructive surgical techniques aim at preserving joint function, inducing fibrocartilaginous repair, and at correcting malalignment. This review summarizes the current status of the clinical treatment of traumatic osteochondral defects, osteochondritis dissecans, osteonecrosis, and osteoarthritis as they affect the subchondral bone region and its adjacent structures.     

Subchondral bone infractions in acute ligamentous knee injuries demonstrated on bone scintigraphy and magnetic resonance imaging.

Bone scintigraphy is used to detect radiographically silent fractures. Magnetic resonance imaging (MRI) is currently used to screen knee injuries for cartilage and ligament damage. MRI also delineates bone marrow and fractures. We investigated the bone scintigraphic findings in patients who had subchondral bone injuries demonstrated on MRI. Thirteen patients underwent MRI, three-phase bone scintigraphy with SPECT, and arthroscopic surgery after sustaining acute traumatic hemarthrosis of a knee. They all had clinically unsuspected subchondral bone injuries demonstrated on MRI with normal radiographs and normal overlying articular cartilage at arthroscopy, consistent with occult fractures. All showed focal bone repair on scintigraphy. Two of the 13 patients showed additional bone injuries only on bone scan. Two other patients scintigraphically showed focal bone repair at the medial femoral condyle due to avulsion of the medial collateral ligament. SPECT was easier to interpret than multi-view planar imaging. Bone scintigraphy confirms subchondral fractures demonstrated on MRI but also demonstrates ligament avulsion injuries and additional more subtle bone injuries.     

Aspects of Magnetic Resonance in the surgical treatment of osteochondral lesions of the knee

AIM: To assess the magnetic resonance (MR) appearance of knee cartilage chondroplasty procedures and their evolution in order to evaluate the usefulness of the method in monitoring postoperative rehabilitation. MATERIALS AND METHODS: Sixty-two patients treated with knee chondroplasty for high-grade cartilage injuries (Noyes' stages II and III) were examined with MR. Forty patients were treated with abrasion chondroplasty, fifteen with osteochondral graft in the injury site and seven with the matrix-induced autologous chondrocyte transplant technique. All patients were operated on by the same orthopaedic team and examined with the same MR protocol. The MR follow-up was performed six months and one year after surgery in the patients treated with abrasion chondroplasty and osteochondral graft, and one week, three months and one year after surgery in the patients treated with cartilage transplant. In the patients treated with abrasion chondroplasty we assessed the fibrocartilage repair and the subchondral bone features, in the patients treated with osteochondral graft we examined the cartilage, the subchondral bone and the graft borders, while in the patients treated with cartilage transplant we evaluated the features and the evolution of the transplant and the subchondral bone. Arthrosynovitis was assessed in all patients. In seven patients a cartilage repair biopsy was performed in arthroscopy. RESULTS: In all the patients MR imaging proved useful in monitoring the chondroplasty. In the patients treated with abrasion chondroplasty the cartilage repair appeared as a hypointense non-homogeneous irregular strip of tissue that replaced the articular surface. The subchondral bone was sclerotic with some geodes. In the later examination the repair was unchanged. In the patients treated with osteochondral graft the articular cartilage was similar to the adjacent hyaline cartilage, although more non-homogeneous. The subchondral bone was sclerotic and in three cases oedematous. In four cases the graft extended beyond the articular border. In the cartilage transplant the matrix appeared as a hypointense stripe after a week due to hydration and it had thinned with signal reduction in the later follow-ups. In the cases with unfavourable clinical evolution the subchondral bone was oedematous and sclerotic in the later examinations. In the cases with unfavourable clinical evolution there was moderate arthrosynovitis, regardless of the chondroplasty technique performed. CONCLUSIONS: MR imaging is useful for monitoring the maturation and the integration of knee chondroplasty and can be proposed as a replacement of arthroscopy for the assessment of postoperative rehabilitation.     

MR示踪技术在干细胞移植治疗软骨缺损中的研究进展

关节软骨缺损临床十分常见, 但目前的治疗方法均存在修复不完全的缺陷。间充质干细胞移植治疗的发展为再生修复关节软骨缺损提供了新的治疗策略, 但是作为组织修复执行者的干细胞移植后的在体迁徙分布、增殖及转归过程, 目前尚无安全无创、实时动态的监测手段, 因此难以明确外源性干细胞在关节软骨缺损再生修复中所扮演的角色。而MR在体示踪细胞技术为解决上述问题提供了新思路。MRI具有无创、无电离辐射、时间空间分辨率高、对比度好等优点, 协同MRI对比剂, 既可无创提供关节软骨的详细解剖结构信息, 还可动态评估移植干细胞的归宿。笔者就MR示踪技术在干细胞移植治疗软骨缺损中的最新研究进展进行综述, 探讨其优势、局限性及未来前景。     

Advanced morphological and biochemical magnetic resonance imaging of cartilage repair procedures in the knee joint at 3 Tesla

Morphological and biochemical magnetic resonance imaging (MRI) is due to high field MR systems, advanced coil technology, and sophisticated sequence protocols capable of visualizing articular cartilage in vivo with high resolution in clinical applicable scan time. Several conventional two-dimensional (2D) and three-dimensional (3D) approaches show changes in cartilage structure. Furthermore newer isotropic 3D sequences show great promise in improving cartilage imaging and additionally in diagnosing surrounding pathologies within the knee joint. Functional MR approaches are additionally able to provide a specific measure of the composition of cartilage. Cartilage physiology and ultra-structure can be determined, changes in cartilage macromolecules can be detected, and cartilage repair tissue can thus be assessed and potentially differentiated. In cartilage defects and following nonsurgical and surgical cartilage repair, morphological MRI provides the basis for diagnosis and follow-up evaluation, whereas biochemical MRI provides a deeper insight into the composition of cartilage and cartilage repair tissue. A combination of both, together with clinical evaluation, may represent a desirable multimodal approach in the future, also available in routine clinical use.     

Initial results of in vivo high-resolution morphological and biochemical cartilage imaging of patients after matrix-associated autologous chondrocyte transplantation (MACT) of the ankle

Objective  The aim of this study was to use morphological as well as biochemical (T2 and T2* relaxation times and diffusion-weighted imaging (DWI)) magnetic resonance imaging (MRI) for the evaluation of healthy cartilage and cartilage repair tissue after matrix-associated autologous chondrocyte transplantation (MACT) of the ankle joint. Materials and methods  Ten healthy volunteers (mean age, 32.4 years) and 12 patients who underwent MACT of the ankle joint (mean age, 32.8 years) were included. In order to evaluate possible maturation effects, patients were separated into short-term (6–13 months) and long-term (20–54 months) follow-up cohorts. MRI was performed on a 3.0-T magnetic resonance (MR) scanner using a new dedicated eight-channel foot-and-ankle coil. Using high-resolution morphological MRI, the magnetic resonance observation of cartilage repair tissue (MOCART) score was assessed. For biochemical MRI, T2 mapping, T2* mapping, and DWI were obtained. Region-of-interest analysis was performed within native cartilage of the volunteers and control cartilage as well as cartilage repair tissue in the patients subsequent to MACT. Results  The overall MOCART score in patients after MACT was 73.8. T2 relaxation times (~50 ms), T2* relaxation times (~16 ms), and the diffusion constant for DWI (~1.3) were comparable for the healthy volunteers and the control cartilage in the patients after MACT. The cartilage repair tissue showed no significant difference in T2 and T2* relaxation times (p ≥ 0.05) compared to the control cartilage; however, a significantly higher diffusivity (~1.5; p < 0.05) was noted in the cartilage repair tissue. Conclusion  The obtained results suggest that besides morphological MRI and biochemical MR techniques, such as T2 and T2* mapping, DWI may also deliver additional information about the ultrastructure of cartilage and cartilage repair tissue in the ankle joint using high-field MRI, a dedicated multichannel coil, and sophisticated sequences.     

Imaging of acute injuries of the articular surfaces (chondral, osteochondral and subchondral fractures)

Fractures involving the articulating surfaces of bone are a common cause of chronic disability after joint injury. Acute fractures of the articular surface typically run parallel to the surface and are confined to the cartilage and/or the immediate subchondral cancellous bone. They should be distinguished from vertical or oblique bone fractures with intra-articular extension. This article reviews the mechanism of acute articular surface injuries, as well as their incidence, clinical presentation, radiologic appearance and treatment. A classification is presented based on direct inspection (arthroscopy) and imaging (especially MRI), emphasizing the distinction between lesions with intact (subchondral impaction and subchondral bone bruises) and disrupted (chondral, osteochondral lesions) cartilage. Hyaline cartilage, subchondral bone plate and subchondral cancellous bone are to be considered an anatomic unit. Subchondral articular surface lesions, osteochondral fractures and solely chondral fractures are different manifestations of impaction injuries that affect the articulating surface. Of the noninvasive imaging modalities, conventional radiography and MRI provide the most relevant information. The appropriate use of short tau inversion recovery, T1-weighted and T2-weighted (turbo) spin-echo as well as gradient-echo sequences, enables MRI to classify the various acute articular surface lesions with great accuracy and provides therapeutic guidance. Received: 5 April 1999 Revision requested: 6 May 1999 Revision received: 21 June 1999 Accepted: 12 July 1999     

MR imaging of cartilage repair surgery of the knee

Articular cartilage is a complex tissue with unique properties that are essential for normal joint function. Many processes can result in cartilage injury, ranging from acute trauma to degenerative processes. Articular cartilage lacks vascularity, and therefore most chondral defects do not heal spontaneously and may require surgical repair. A variety of cartilage repair techniques have been developed and include bone marrow stimulation (microfracture), osteochondral autograft transfer system (OATS) or osteochondral allograft transplantation, autologous chondrocyte implantation (ACI), matrix-assisted chondrocyte implantation (MACI), and other newer processed allograft cartilage techniques. Although arthroscopy has long been considered as the gold standard for evaluation of cartilage after cartilage repair, magnetic resonance (MR) imaging is a non-invasive method to assess the repair site and can be scored using Magnetic resonance Observation of Cartilage Repair Tissue (MOCART). MR also provides additional evaluation of the subchondral bone and for other potential causes of knee pain or internal derangement. Conventional MR can be used to evaluate the status of cartilage repair and potential complications. Compositional MR sequences can provide supplementary information about the biochemical contents of the reparative tissue. This article reviews the various types of cartilage repair surgeries and their postoperative MR imaging appearances.     

A practical guide to imaging of cartilage repair with emphasis on bone marrow changes

Orthopedic surgeons have multiple options available to treat articular cartilage lesions, including microfracture, osteochondral autografting, and autologous chondrocyte implantation. By having basic knowledge of these surgical procedures, radiologists can more accurately interpret imaging studies obtained after surgery. In this article, we briefly review the different types of cartilage repair procedures, their appearance on magnetic resonance imaging (MRI), and pathologic MRI findings associated with postoperative complications. We also briefly discuss advanced MRI techniques (T2 mapping, delayed gadolinium-enhanced MRI of cartilage, sodium MRI) that have been recently used to assess the biochemical composition of repair tissue matrix. MRI can accurately assess the status and health of cartilage repair tissue. By providing this information to orthopedic surgeons, radiologists can play a valuable role in the management of patients who undergo cartilage repair surgery.     

MR imaging of cartilage repair surgery of the knee

Articular cartilage is a complex tissue with unique properties that are essential for normal joint function. Many processes can result in cartilage injury, ranging from acute trauma to degenerative processes. Articular cartilage lacks vascularity, and therefore most chondral defects do not heal spontaneously and may require surgical repair. A variety of cartilage repair techniques have been developed and include bone marrow stimulation (microfracture), osteochondral autograft transfer system (OATS) or osteochondral allograft transplantation, autologous chondrocyte implantation (ACI), matrix-assisted chondrocyte implantation (MACI), and other newer processed allograft cartilage techniques. Although arthroscopy has long been considered as the gold standard for evaluation of cartilage after cartilage repair, magnetic resonance (MR) imaging is a non-invasive method to assess the repair site and can be scored using Magnetic resonance Observation of Cartilage Repair Tissue (MOCART). MR also provides additional evaluation of the subchondral bone and for other potential causes of knee pain or internal derangement. Conventional MR can be used to evaluate the status of cartilage repair and potential complications. Compositional MR sequences can provide supplementary information about the biochemical contents of the reparative tissue. This article reviews the various types of cartilage repair surgeries and their postoperative MR imaging appearances.     

Review of Quantitative Knee Articular Cartilage MR Imaging

Osteoarthritis (OA) is one of the most prevalent disorders in today’s society, resulting in significant socio-economic costs and morbidity. MRI is widely used as a non-invasive imaging tool for OA of the knee. However, conventional knee MRI has limitations to detect subtle early cartilage degeneration before morphological changes are visually apparent. Novel MRI pulse sequences for cartilage assessment have recently received increased attention due to newly developed compositional MRI techniques, including: T2 mapping, T1rho mapping, delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), sodium MRI, diffusion-weighted imaging (DWI)/ diffusion tensor imaging (DTI), ultrashort TE (uTE), and glycosaminoglycan specific chemical exchange saturation transfer (gagCEST) imaging. In this article, we will first review these quantitative assessments. Then, we will discuss the variations of quantitative values of knee articular cartilage with cartilage layer (depth)- and angle (regional)-dependent approaches. Multiple MRI sequence techniques can discern qualitative differences in knee cartilage. Normal articular hyaline cartilage has a zonal variation in T2 relaxation times with increasing T2 values from the subchondral bone to the articular surface. T1rho values were also higher in the superficial layer than in the deep layer in most locations in the medial and lateral femoral condyles, including the weight-bearing portion. Magic angle effect on T2 mapping is clearly observed in the both medial and lateral femoral condyles, especially within the deep layers. One of the limitations for clinical use of these compositional assessments is a long scan time. Recent new approaches with compressed sensing (CS) and MR fingerprinting (MRF) have potential to provide accurate and fast quantitative cartilage assessments.     

Subchondral bone marrow edema in patients with degeneration of the articular cartilage of the knee joint

PURPOSE: To retrospectively determine at magnetic resonance (MR) imaging the prevalence of subchondral bone marrow edema beneath arthroscopically proved articular cartilage defects. MATERIALS AND METHODS: The study was performed in compliance with HIPAA regulations, and a waiver of informed consent was obtained from the institutional review board before the study was performed. The study consisted of 132 patients (70 men, 62 women; average age, 53 years) with articular cartilage defects of the knee joint who underwent MR imaging of the knee and subsequent arthroscopic knee surgery. At the time of arthroscopy, each articular cartilage lesion was graded by using the Noyes classification system. MR examinations were retrospectively reviewed to determine the size, depth, and location of subchondral bone marrow edema without knowledge of the arthroscopic findings. Pairwise Fisher exact tests and two-sample t tests were used to correlate MR imaging findings of subchondral bone marrow edema with the arthroscopic grade of articular cartilage degeneration. RESULTS: Subchondral bone marrow edema was seen beneath 105 (19%) of 554 articular cartilage defects identified at arthroscopy. It was not observed beneath any of the six grade 1 cartilage defects but was observed beneath eight (4.9%) of 163 grade 2A defects, 40 (14.4%) of 278 grade 2B defects, 54 (55.1%) of 98 grade 3A defects, and three (33.3%) of nine grade 3B defects. Subchondral bone marrow edema was also seen beneath four (1.4%) of 238 articular surfaces that appeared normal at arthroscopy. The mean depth and cross-sectional area of subchondral bone marrow edema increased with increasing grade of the articular cartilage lesion. CONCLUSION: Higher grades of articular cartilage defects are associated with higher prevalence and greater depth and cross-sectional area of subchondral bone marrow edema.     

Autologe Chondrozytentransplantation zur Behandlung von Knorpeldefekten des Kniegelenks

BACKGROUND: Currently the use of autologous chondrocytes as a cartilage-repair procedure for the repair of injured articular cartilage of the knee joint, is recommended. METHODS: This review presents the technique of autologous chondrocyte transplantation (ACT) and their modifications as matrix-associated autologous chondrocyte transplantation (MACT). Beside the surgical procedure the experimental and clinical results are discussed. Furthermore the major complications and the indication guidelines are presented. RESULTS: Articular cartilage in adults has a poor ability to self-repair after a substantial injury. Surgical therapeutic efforts in treating cartilage defects have focused on bringing new cells capable of chondrogenesis into the lesions. With ACT good to excellent clinical results are seen in isolated posttraumatic lesions of the knee joint in the younger patient with the formation of hyaline-like repair tissue. The major complications are periosteal hypertrophy, delamination of the transplant, arthrofibrosis and transplant failure. The current limitations include osteoarthritic defects and higher patient age. CONCLUSION: With the right indication and operative technique ACT is an effective and save option for the treatment of large full thickness cartilage defect of the knee joint.     

Magnetization transfer contrast and T2 mapping in the evaluation of cartilage repair tissue with 3T MRI

PURPOSE: To use magnetization transfer (MT) imaging in the visualization of healthy articular cartilage and cartilage repair tissue after different cartilage repair procedures, and to assess global as well as zonal values and compare the results to T2-relaxation. MATERIALS AND METHODS: Thirty-four patients (17 after microfracture [MFX] and 17 after matrix-associated autologous cartilage transplantation [MACT]) were examined with 3T MRI. The MT ratio (MTR) was calculated from measurements with and without MT contrast. T2-values were evaluated using a multiecho, spin-echo approach. Global (full thickness of cartilage) and zonal (deep and superficial aspect) region-of-interest assessment of cartilage repair tissue and normal-appearing cartilage was performed. RESULTS: In patients after MFX and MACT, the global MTR of cartilage repair tissue was significantly lower compared to healthy cartilage. In contrast, using T2, cartilage repair tissue showed significantly lower T2 values only after MFX, whereas after MACT, global T2 values were comparable to healthy cartilage. For zonal evaluation, MTR and T2 showed a significant stratification within healthy cartilage, and T2 additionally within cartilage repair tissue after MACT. CONCLUSION: MT imaging is capable and sensitive in the detection of differences between healthy cartilage and areas of cartilage repair and might be an additional tool in biochemical cartilage imaging. For both MTR and T2 mapping, zonal assessment is desirable.     

Correlation between radiographic findings of osteoarthritis and arthroscopic findings of articular cartilage degeneration within the patellofemoral joint

Objectives To correlate radiographic findings of osteoarthritis on axial knee radiographs with arthroscopic findings of articular cartilage degeneration within the patellofemoral joint in patients with chronic knee pain.Subjects and methods The study group consisted of 104 patients with osteoarthritis of the patellofemoral joint and 30 patients of similar age with no osteoarthritis of the patellofemoral joint. All patients in the study group had an axial radiograph of the knee performed prior to arthroscopic knee surgery. At the time of arthroscopy, each articular surface of the patellofemoral joint was graded using the Noyes classification system. Two radiologists retrospectively reviewed the knee radiographs to determine the presence of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts. The sensitivity and specificity of the various radiographic features of osteoarthritis for the detection of articular cartilage degeneration within the patellofemoral joint were determined.Results The sensitivity of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts for the detection of articular cartilage degeneration within the patellofemoral joint was 73%, 37%, 4%, and 0% respectively. The specificity of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts for the detection of articular cartilage degeneration within the patellofemoral joint was 67%, 90%, 100%, and 100% respectively.Conclusion Marginal osteophytes were the most sensitive radiographic feature for the detection of articular cartilage degeneration within the patellofemoral joint. Joint-space narrowing, subchondral sclerosis, and subchondral cysts were insensitive radiographic features of osteoarthritis, and rarely occurred in the absence of associated osteophyte formation.