DISCUSSION

Magnetic resonance imaging (MRI) with its excellent soft tissue contrast and resolution with no operator dependence and no ionizing radiation is the imaging modality of choice for evaluation of hip joint abnormalities. MRI offers valuable information regarding occult bony and cartilage injury such as stress fractures, avascular necrosis, and osteoarthritis, as well as soft tissue abnormalities such as muscle tears and bursitis. MRI provides a useful assessment of patients in whom a femoro-acetabular impingement is clinically suspected. The present hospital based cross-sectional study was conducted to estimate the role of MRI in early evaluation of hip joint pathologies. The study was conducted in Department of Radio diagnosis from December 2016 to October 2018. A total sample size of 50 patients referred to the department of Radio diagnosis with clinical history of hip pain was included in the study. Patients with history of acute trauma, history of metallic implants insertion, cardiac pacemakers and metallic foreign body in situ and patient with congenital abnormality were excluded. In present study the MRI findings in avascular necrosis among patients showed that majority of patients showed focal subchondral signal abnormality (100%) followed by double line sign (75%) The other findings include marrow edema (43.75%) and joint effusion (37.5%). MRI findings in avascular necrosis among patients by Mitchelles classification showed that majority of patients had Stage C AVN (37.5%) followed by Stage B (25%) while by Ficat and Arlet classification majority of patients had Stage III AVN (43.75%) followed by Stage II (31.25%). Takatori Y et al.⁵ reported that 85% of the patients of avascular necrosis show a characteristic “double line“ sign on T2 weighted images which is a specific finding that consists of concentric low- and high signal intensity rims that surround the area of marrow signal intensity change within the femoral head. In study by Hayam Abd et al.,⁸ the characteristic “double line“ sign on T2 weighted images was seen in 80% of patients with AVN (20 patient) . In the study done by the Khaladkar Sanjay M et al.⁹ double line sign on T2 weighted images was seen in 56.8% of patients of AVN. A double line sign seen in AVN as an outer low signal intensity rim and an inner high-intensity band on T2W images was seen in 75% of cases which is consistent with the previous studies by Mitchell et al. ¹¹ and Mitchell et al. ¹⁰ found it in 80% and 71% of the cases, respectively. These data support the hypothesis that early non-traumatic osteonecrosis is associated with hyperemia and/or an increase in capillary permeability rather than acute devascularization and that diffuse marrow edema is the initial finding in early non-traumatic osteonecrosis. In a study done by Arvind kumar Vaghamashi et al.¹² on imaging findings depicted on MRI in patients with a painful hip joint most common MRI finding of AVN was focal subchondral signal abnormality which was present in 100 % of the lesions. Chaudhari NH et al. ¹³ assessed the role of MRI in early diagnosis of AVN and found that out of total 60 femoral heads (bilateral femoral heads of 30 patients) 51 were showing features of AVN, while 9 were normal. Out of 51 femoral heads showing AVN, 21 showed subchondral collapse. Bone marrow edema was seen in 34 femoral heads out of 51 femoral heads with AVN. Joint effusion was observed in 37 femoral heads out of 51 femoral heads with AVN. It our present study it was observed that majority of patients showed focal subchondral signal abnormality (100%) followed by double line sign (75%) The other findings includes marrow edema (43.75%) and joint effusion (37.5%). In the study done by Mitchell D et al.l ⁶ joint effusion is found is 58% of the total AVN patients. While in our study is found in 37.5% of the patients. The MRI findings in osteoarthritis among patients showed that majority of patients showed patients showed joint effusion (100%) followed by synovial thickening (71.42%) The other findings include marrow edema (71.42%), subchondral cysts (57.14%), joint space narrowing (57.14%), marginal osteophytes (57.14%) and soft tissue edema (42.86%). Hayashi¹⁴ reviewed that bone marrow signal alteration (bone marrow edema) is a common magnetic resonance imaging feature of hip OA and the degree of bone marrow edema, as assessed by MRI, correlates with the severity of hip pain in cases with osteoarthritis. Tushar Kalekar et al.¹⁴ assessed the role of MRI in early evaluation of painful hip joint observed that commonest MRI abnormality seen in cases of osteoarthritis was signal loss in the femoral head and neck on T1W images which was found in 90% cases. Boutry et al.¹⁶ demonstrated joint effusion (100%), bone marrow edema (83%) and subchondral cysts (83%) in his study on hip osteoarthritis. Osteoarthritis (OA) is a disease-causing destruction of synovial joint. The risk for disability and dependency from changes of OA is comparable with that of cardiovascular disease in the elderly. MRI has some credible role as a non-invasive method of depicting early changes of OA when compared with standard radiograph, histology, and other techniques, however still Radiography continues to be used as a confirmatory imaging modality by clinicians due to its ready availability and cost effectiveness. The signs on MRI include joint effusion, reduced joint space, marrow edema, osteophytes, cartilage defects and subchondral cysts and fissures.  In our study cartilage is affected in nearly 71.42% of the patients. This finding is well correlated with the study done by Teichtahl, A. J.¹⁷ Iidaka T et al.¹⁸ studied on Osteoarthritis/ osteoporosis against disability on the basis of radiographic evidence and found that males are more commonly affected than females while the severity of osteoarthritis is more common in females. While in our study total 5 out of 8 patients of osteoarthritis were female. In the present study, the MRI findings in osteoporosis showed that majority of patients had marrow edema of femoral head and neck (100%) followed by joint effusion (75%) and marrow edema of the acetabulum (50%).

CONCLUSION

It was observed that MRI was very useful in the assessment of the severity and extent of the underlying lesion in various conditions of painful hip joint.

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