Evaluation Of Osteoarthritis Of The Knee With Magnetic Resonance Imaging And Correlating It With Radiological Findings In The Indian Population.
V JOSHI, R Singh, N Kohli, U Parashari, A Kumar, V Singh
kl score, mri, osteoarthritis
V JOSHI, R Singh, N Kohli, U Parashari, A Kumar, V Singh. Evaluation Of Osteoarthritis Of The Knee With Magnetic Resonance Imaging And Correlating It With Radiological Findings In The Indian Population.. The Internet Journal of Orthopedic Surgery. 2008 Volume 14 Number 1.
Worldwide, osteoarthritis is the most common form of arthritis.
Recent focus on the development of disease-modifying therapeutic agents for OA has emphasized the need for imaging techniques capable of depicting relevant early abnormalities of OA over relatively short times. Simultaneously, there is increasing acknowledgment that OA, particularly in the knee, can be regarded as a whole-organ degenerative process , with an emphasis on the contribution of multiple articular and periarticular abnormalities in the clinical expression of the disease. Dr. Peterfy, co-founder and Chief Medical Officer of Synarc, was the first to develop whole-organ MRI scoring (WORMS) for the knee. WORMS combines semi-quantitative assessments of a total of 11 structural features, including the articular cartilage, subarticular marrow-edema, cysts and bone attrition in 8 different locations in the knee; osteophytes along 16 articular margins; the medial and lateral menisci; the anterior and posterior cruciate ligaments; and the medial and lateral collateral ligaments . MRI is an excellent diagnostic modality in osteoarthritis. The superior soft tissue contrast of MRI provides the ability to diagnose cortical bone, articular cartilage and soft tissues abnormalities in the joints that improves early detection of osteoarthritic changes in knee joint.
The study was performed to grade various stages of osteoarthritis by using Kellgren-Lawrence grading scale , to evaluate the osteoarthritis of knee using magnetic resonance imaging , to correlate MR findings of osteoarthritis with that of radiographically diagnosed osteoarthritis .
Subjects And Methods
One hundred twenty eight patients have formed the study group in a prospective fashion. All patients underwent Anteroposterior radiography of affected knee in weight bearing extended positions and subsequently MRI of the knee was performed. For the reporting of abnormalities at MR imaging according to compartment, simple counts (numbers and percentages) were estimated. In the analysis of MR imaging findings for the OA of the knee, the single knee (the most symptomatic knee at inclusion in the study) for each subject was analyzed. For subjects in whom both knees equally fit the categorical criteria, the self-described dominant knee was chosen as the examined knee. Patients with knee pain/stiffness/limitation of movement were included and osteoarthritis of knee was diagnosed by clinicoradiological American Rheumatism Association Criteria, viz;
Age >40 yrs
Joint stiffness<30 minute
For diagnosing osteoarthritis presence of 1,2 and one of 3 ,4or 5 is essential.
Exclusion criteria were claustrophobia , non cooperative patients, patients with obvious inflammation, secondary osteoarthritis e.g. trauma, operated knee joint, inflammatory arthritis eg.rheumatoid arthritis, morning stiffness>1 hr in hand joints ,diseased ipsilateral hip joint ,fibromyalgia ,depression ,local wound/ulcer around knee joint or presence of peripheral neuropathy.
Radiographic Findings And KL Score
Technique Of Magnetic Resonance Imaging In Knee Osteoarthritis
MR imaging of the knee was performed with a 1.5-T MR imager (Signa; GE Medical Systems), by using a quadrature receiver knee coil for signal reception. Since patients with symptomatic knees were examined by using a fairly long acquisition protocol, patients were immobilized by using hook-and- loop straps. MR Imaging were performed by using T2 FSE sequence in axial plane; PD Fat Sup, T1 SE, T2 fr FSE and SPGR sequence in sagittal plane and STIR FSE,T2 GRE & T1 FSE in coronal plane. For STIR and SPGR matrix of 256 x192 was used. For rest of the sequences matrix of 320x224 was used. FOV (field of view) of 18 mm was used in all sequences. Slices were obtained at 4-5 mm thickness with an interscan gap of 0.5-1 m. In SPGR sequence slice thickness was 2mm, with no spacing. Each
Subchondral trabecular BME.—BME was defined as noncircumscribed areas of abnormally high signal intensity on IW fast spin-echo images obtained with fat saturation in a subchondral location and verified in at least two imaging planes [11,12]. BME lesions were recorded according to site and
Marginal osteophytes.—Osteophytes were defined as any abnormal bone growth that arose from the margin
Subchondral cysts.—Subchondral cysts were defined as marginated circular or oval areas
Subchondral sclerosis.—Definite focal thickening
Joint effusion.—Joint effusion was defined as the presence
Baker’s cyst/Synovial cysts.—Synovial cysts were fluid-filled collections that arose from the joint, extended between the semimembranosis and semitendinosis tendons and the medial head
Synovitis.—Synovitis was defined as increased linear striations within the infrapatellar (H
Meniscal abnormalities.—By using accepted MR imaging criteria described in a study
Ligamentous abnormalities.—Cruciate ligamentous abnormalities were assigned grades as follows: grade 0, normal; grade 1, increased edema within or surrounding the ligament, with a normal course, and at least some intact fibres present; or grade 2, complete tear, acute or chronic. Collateral ligamentous abnormalities were assigned grades as follows: grade 0, normal ligament; grade 1, substantial periligamentous edema, with the ligament intact; grade 2, partial tear; or grade 3, complete tear.
Osteochondral bodies/loose bodies-
Subluxation in knee joint.
Sample profile was described in terms of means ± SD and proportion. Chi square(c)2 statistics was applied to test the association between two categorical variables. Spearman's correlation was reported to estimate the strength of association between KL score and severity of osteoarthritis. . Two sample t-test was applied to test the difference between the mean of two different groups, if data was normally distributed otherwise Mann Whitney test was applied. In case of more than 2 groups, one way Analysis of Variance or Kruskal Walli's test, whichever is applicable, was used. Data were analyzed using statistical software package, STATA 9.2 and the difference was considered to be significant if 'P' value was <0.05.
All the patients presented at an age equal to or more than 40 years. Most of the patients (n=48, 37.50%) were 40-45 years of age. The study population included ninety two females (71.87%) and thirty six males (28.13%) and a higher incidence of osteoarthritis was seen in female population in the age group of 40-45 years Also the peak prevalence of osteoarthritis in our study was at a lower age in females as compared to males.
Our study population was graded by Kellgren-Lawrence scores according to the severity of osteoarthritis as diagnosed on X-ray features. 48 patients (37.50%) of study population were categorized as having a KL score of Grade 2, 60 patients (46.87%) were diagnosed as having a KL score of Grade 3 and 20 patients (15.63%) were diagnosed as having a KL score of Grade 4. The association between various compartment specific MRI findings and KL score have been shown in table .
There is a high correlation between MR severity of osteophytes ,subchondral cysts, bone marrow edema ,cartilage defects and radiographic findings (P value = 0.000, 0.000.0.000,0.000,0.030,0.001 ,0.000 ; P=0.40, 0.000, 0.000 ,0.000,0.014,0.050 ,0.005; P=0.022,0.000,0.000,0.000,0.002,0.006,0.018; P=0.000,0.000,0.000,0.000,0.001,0.000,0.000 respectively for osteophytes, subchondral cysts, bone marrow edema and cartilage defects in medial condyle of femur, medial condyle of tibia ,lateral condyle of femur, lateral condyle of tibia ,femur trochlea, medial and lateral patellar facets respectively). A positive association was also seen between radiographic findings and MRI detected subchondral sclerosis in medial tibial condyle, femur trochlea and medial and lateral articulating facets of patella (P=0.000, 0.046, 0.008 and 0.008 respectively).
The frequency of non compartment specific MR imaging findings has been shown in the
A significant association with high KL score was found with meniscal and ligamentous injuries( P= 0.000 and 0.000 in medial and lateral meniscal injuries ,P=0.000 and 0.004 in medial and lateral collateral ligament injuries and P=0.032 and 0.001 in anterior and posterior cruciate ligamentous injuries respectively).A significant statistical association was seen between radiographic findings and baker’s cysts, joint effusion and synovitis (P=0.000,0.000 ,0.001 and 0.000 respectively. Osteochondral bodies were seen in 15.63%of study population and were significantly associated with KL score (P=0.000).
MRI, being a multiplanar diagnostic tool is an excellent modality for evaluation of patients of osteoarthritis of knee joint. It accurately defines the extents of bony and soft tissue changes in knee joint. In this study MRI was compared with a plain radiograph of knee joint and MRI was found to be a much better diagnostic tool for evaluating the changes in bones and soft tissues in osteoarthritis of knee. Few findings from our study are noteworthy. Firstly frequency and severity of MRI changes in various tissues strongly correlated with Kellgren Lawrence grade of osteoarthritis of the knee at radiography. Secondly, MR imaging defined abnormalities were more frequent in tibiofemoral compartment than in the patellofemoral compartment.
In our study the tibiofemoral compartment which was more frequently and more severely involved in osteoarthritis of knee joint than the patellofemoral compartment. In western population, it was the patellofemoral compartment which was more frequently and more severely involved. This difference is due to sitting in squatting posture in Indian population. . Prolonged squatting has been associated with development of osteoarthritis of knee joint in tibiofemoral compartment but only slightly associated with development of osteoarthritis in patellofemoral compartment[20,21,22].
Most frequent site of osteophytosis was medial tibiofemoral joint in our study (100%) while in
The most common site of bone marrow edema in our study was tibiofemoral compartment with the highest incidence in medial condyle of femur (78.12% ) while in a previous study the patellofemoral compartment was the most common site showing bone marrow edema.This difference could also be explained by the squatting posture adopted by Indian population
Subchondral cysts were also most commonly found in the tibiofemoral compartment i.e. in medial condyle of femur (62.50%) followed by in medial condyle of tibia(53.12%). Grade II subchondral cysts were most frequently seen in medial condyle of tibia (25%)
Almost all patients in our study showed presence of cartilage defects, the tibiofemoral compartment being more commonly involved than the patellofemoral compartment. Grade III B cartilage defects were most commonly seen in medial tibial condyle (40.62%) and medial femoral condyle (34 .37%). In contrast, Curtis
It is noticeable that defects of cartilage of Grade II a or higher and bone marrow edema were evident on MR images, even on those knees which were classified as normal on radiography
In our study subchondral sclerosis and cysts were more commonly seen in tibiofemoral joint than the patellofemoral joint as reported earlier in literature .Medial articulating surface of tibia showed the highest frequency of subchondral sclerosis (75%of study subjects) and also subchondral sclerosis of larger size , followed by medial articulating surface of femur( 59.37% of study subjects).
The incidence of medial and lateral meniscal injuries are almost equal in our study( 90.62% and 96.87% respectively)of which 46.87% and 53.13% of patients showed Grade II tears of medial and lateral meniscus respectively. These findings are in accordance with the previous study .. Collateral ligament injury was rarely seen in our study. Anterior cruciate ligament and posterior cruciate ligament injury was seen in 25% and 34.37% of cases, respectively Joint effusion of varying grades was seen in 78.13% of cases in our study. Mild grade of synovitis was seen in 25% of patients. Baker’s cysts of varying grades were seen in 40.63% of study population. Osteochondral bodies were seen in 15.63% patients. 25 % patients showed presence of subluxation of tibia, lateral subluxation being the most common.
We found a statistically significant correlation between majority of MRI changes of osteoarthritis in tibiofemoral compartment of knee joint and KL score. There is a poor correlation between MRI and KL score for diagnosing changes in the patellofemoral compartment. This could be explained, as lateral or skyline views of the knee were not used in the categorization of the radiographic severity of OA in our subjects, that is why radiographically determined patellofemoral involvement was relatively underdiagnosed.The disparity in sensitivity between MR imaging and standard radiography for detection of abnormalities, especially in the patellofemoral compartment, may partly explain the observation that anatomical changes in OA of the knee long precedes the radiographic evidence of OA of the knee but can be diagnosed by MRI at an early stage. Our data show that there were more frequent and more severe abnormalities detected at MR imaging as the radiographically determined grades of OA of the knee increased.
Increasing Kellgren Lawrence scores were associated with more frequent and more severe defects of cartilage, bone marrow edema, osteophytes, subchondral sclerosis and subchondral cysts in tibiofemoral compartment, joint effusion, osteochondral bodies and presence of meniscal tears. These finding reinforce the evolving concept that OA of the knee is a whole-organ disease and that MR imaging is capable of showing the bone and soft-tissue evidence of OA of the knee at an early stage .