MR IMAGING FINDINGS OF HAEMOPHILIC ARTHROPATHY OF THE ELBOW IN CHILDREN

the elbow is an uncommon causeof elbow pain and swelling in children and adolescents. HA due to recurrent haemarthrosis is the most common musculo skeletal manifestation of haemo philia and one of the most disabling complications of this disease. Children with severe haemophilia suffer from recurrent and acute joint haemorraghe. The therapy consists of factor VIII or IX replacement infusions (treatment on demand). The aim of this therapy is to keep the deficient factor > 1% of its normal value to convert severe haemophilia into a milder form of the disorder. The importance of starting replacement therapy early has been stressed in recent literature (13). The aim of this study is to define the MR imaging features of HA arthropathy of the elbow at initial MR imaging.

Haemophilic arthropathy (HA) of the elbow is an uncommon cause of elbow pain and swelling in children and adolescents.
HA due to recurrent haemarthrosis is the most common musculoskeletal manifestation of haemophilia and one of the most disabling complications of this disease.Children with severe haemophilia suffer from recurrent and acute joint haemorraghe.The therapy consists of factor VIII or IX replacement infusions (treatment on demand).The aim of this therapy is to keep the deficient factor > 1% of its normal value to convert severe haemophilia into a milder form of the disorder.The importance of starting replacement therapy early has been stressed in recent literature (1)(2)(3).
The aim of this study is to define the MR imaging features of HA arthropathy of the elbow at initial MR imaging.

Materials and methods
A retrospective study was performed in a pediatric tertiary care centre.Institutional ethics approval was obtained.
Subjects with documented HA of the elbow were identified using a radiology information system database keyword search of final radiology reports over a 10 year period.Patients with haemophilia presenting with elbow lesions in the setting of acute musculoskeletal trauma were excluded (Fig. 1-5).If the subject had undergone more than one MRI examination, only the first set of MRI images was reviewed.Twelve the first age of life and received factor substitution therapy since.
The images were reviewed by two pediatric radiologists.Both reviewing radiologists were not blinded to the original reported findings but used the report only as a means to identify patients for inclusion into the study.
The presence of joint effusion and synovial hypertrophy was assessed.Synovial haemosiderin deposition was considered present if blooming artefact was evident on gradient patients were identified meeting inclusion criteria for the study.The mean age was 12.2 years (range 4.1-16.6years).All patients had been diagnosed with haemophilia within JBR-BTR, 2010, 93: 247-251.Sagittal T2 PD-weighted MR image.There is a small joint effusion of the elbow predominantly in the coronoid fossa (long arrow) and anterior elbow joint recess (short arrow).echo MR imaging.Joint effusion was graded to be moderate or extensive (extension of all joint spaces).Synovial hypertrophy was graded to be small (< 2 mm), moderate (2-5 mm) or large (> 5 mm).Synovial haemosiderin deposition was determined to be present or absent.

MR IMAGING FINDINGS OF HAEMOPHILIC ARTHROPATHY OF THE ELBOW IN CHILDREN
The presence of associated findings including osteochondral lesions, bone erosions, subchondral cysts and presence of loose bodies was analysed.Joint alignment, joint narrowing and epiphyseal overgrowth were assessed.

MR examination
All studies were performed on 1.5 Tesla system (Avanto, Siemens Medical, Erlangen, Germany) with the affected elbow imaged in a small flex extremity four-channel phased circular polarised or array coil (Siemens Medical, Erlangen, Germany).Sequences obtained during MR included sagittal, and coronal oblique fat-saturated T1-

Results
No normal elbow joints were identified.In all patients, MR imaging findings in keeping with HA of the elbow were identified (Fig. 1-5).
Joint effusion was identified in 10 patients (83%).Of these patients, Subchondral cysts were present in 7 patients (58%), all demonstrating multiple cysts in at least one bone of the joint.No patients with articular loose bodies were identified.
Bone marrow edema was present in 8 patients (75%).Focal bone marrow edema in only one bone was identified in 4 patients; extensive multifocal bone marrow edema was identified in 4 patients.
The joint alignment was anatomic in 7 patients (58%) and abnormal in 5 patients (42%).In 3 patients, irregu larity of the articular surfaces was identified.Severe misalignment of the elbow joint was demonstrated in 2 patients, with epiphyseal overgrowth in 1 patient.

Discussion
Our study has shown that MRI clearly depicts early changes in haemophiliac arthropathy of the elbow.
In haemophilia, arthropathy predominantly occurs in only a few joints, most notably the knees, ankles and elbows (4).MRI delineates soft tissue, both cartilage and bone and is accurate in the detection of joint effusion and haemosiderin deposition in HA of the elbow.This is why MRI is a precise non-invasive tool for the assessment of early joint changes still undetectable by physical examination or conventional radiography in the haemophilic setting (5).
Early diagnosis of HA of the elbow is mandatory, since it has been stressed that factor substitution therapy from early age decreases the number of rebleeds of the synovial and thus slows down the progressive severity of the arthropathy.Development of late stage disease, with radiosynoviorthesis and ultimately arthroplasty of the elbow, may be prevented (6)(7).
Several schemes for the radiological diagnosis, classification and follow-up of HA have been proposed.The Petterson scoring system of radiological evaluation of haemophilic arthropathy (Table I) is widely recognized (8).This scoring system, however, is based on radiographic findings only.It has been well demonstrated that MR depicts subtle early joint changes in HA that are not depicted by conventional radiography (5).
Several MR scoring systems have been presented that entail two different strategies: the pathology is scored either according to the characteristic stages of development or 7 presented with moderate and 3 with large joint effusion.
Chondral lesions were identified in 11 patients (92%).Partial thickness cartilage loss was present in 6 patients; complete cartilage loss was present in 5 patients.Changes of subchondral bone or joint margins were identified in 7 patients (58%).(11).
In HA of the elbow, other findings of clinical significance may be present.These features include sprain and tear of ligaments, strain of muscles, presence of soft tissue pseudotumor and late arthropathic degenerative changes.Our study did not focus on these associated findings.However, since these associated findings may be of importance in the clinical setting, awareness of these entities is mandatory.and may prevent progressive joint destruction and surgery.
Gadolinium enhanced MRI may play a role in the differentiation of synovial hypertrophy versus joint fluid.However, contrast administration in the pediatric age group remains a traumatic experience.Given the fact that non enhanced MR imaging provides information of the most common imaging features of HA of the elbow, arthrography was not routinely performed in this study.

Conclusion
The most common findings in haemophiliac arthropathy of the elbow consist of joint effusion, the presence of (osteo)chondral lesions, synovial hypertrophy and synovial haemosiderin deposits.MRI clearly depicts these early changes.Early diagnosis of joint haemorrhage alters the therapeutic management

Fig. 1 .
Fig. 1. -Early stage haemophilic arthropathy of the elbow in a 15 year-old boy.Sagittal T2 PD-weighted MR image.There is a small joint effusion of the elbow predominantly in the coronoid fossa (long arrow) and anterior elbow joint recess (short arrow).

Fig. 3 .
Fig. 3. -Haemophilic arthropathy of the elbow in a 13-yearold boy.A: Coronal FS T2-weighted MR image.An ill defined area of hyperintense signal abnormality is present on the articular side of the trochlea and ulna (small arrows), in keeping with focal edema.Extensive edema of the radial head is identified (long arrow).B: Coronal FS GRE MR image demonstrates small focal subchondral osseous defects in the articular side of the trochlea and ulna (short arrows), as well as an osteochondral defect of the medial aspect of the radial head (long arrow).

Fig. 5 .
Fig. 5. -Haemophilic arthropathy of the elbow in a 4-year-old boy.A: Coronal FS PD-weighted MR image demonstrates haemosiderin deposition in the synovium of the elbow joint (long arrows).Haemosiderin is identified on the articular surface of capitellum and radial head (short arrow).B: Axial T2-weighted image demonstrates discrete hypointense signal return from the synovium in keeping with haemosiderin deposition (arrows).No synovial thickening is identified.Moderate joint effusion is present.

Table II .
-The Denver MRI scale classifying the arthropathy in different stages in relation to the most severe finding.The score is progressive, the maximum score is 10.

Table III .
-The European MRI score given in the format A(e:s:h).The A component is the sum of values for changes in following categories: subchondral cysts, irregularity/erosion of subchondral cortex and chondral destruction.The statements are evaluated to weather they are present, for each present feature 1 point is added to the A component.The factors e (effusion), s (synovial hypertrophy) and h (haemosiderin deposition) are evaluated according to a five-point scale.The maximum score is 16(4:4:4).Present in at least one bone Present in at least two bones More than three cysts in at least one bone More than three cysts in at least two bones Largest size more than 4 mm in at least one bone Largest size more than 4 mm in at least two bonesIrregularity/erosion of subchondral cortex (part of A)Present in at least one bone Present in at least two bones Involves more than half of joint surface in at least one bone Involves more than half of joint surface in at least two bonesChondral destruction (part of A)Present in at least one bone Present in at least two bones Full-thickness defect in at least one bone Full-thickness defect in at least two bones Full-thickness defect involves more than one third of the joint surface in at least one bone Full-thickness defect involves more than one third of the joint surface in at least two bones