EXTRA-ARTICULAR CAUSES OF COXALGIA
BONE
A - FRACTURES
Fractures
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Plain film or CT
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MRI
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Traumatic
|
- usually diagnostic in proper setting
|
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Occult
|
|
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Stress:
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- frequently occult
- CT may assist in differentiating remodeling from osteolysis with trabecular destruction caused by neoplastic disease
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- usually diagnostic
- edema-like abnormalities or a fracture line (hypointense on both T1-weighted and fluid-sensitive sequences) at predilection sites
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A.1 - Fatigue fractures features:
( Fig. 1 and Fig. 2 )
- result from abnormal stress to normal bone;
- frequent in athletes (runners and jumpers);
Common sites:
- hip region: the proximal femur is the most typical location:
usually occur at the medial portion (compressive surface) of the femoral neck.
- pelvic region: pubic rami is the second most common site.
Fig. 2: Coronal PD Fat-Sat WI of the left hip. Fracture line on the inner facet of the femoral neck (linear hypointensity) surrounded by oedema (hyperintense signal).
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
A.2 - Insufficiency fractures features:
( Fig. 3 ,
Fig. 4 and Fig. 5 )
- result from normal stress to abnormal bone;
- frequent in elderly women suffering from osteoporosis,
but also in hyperparathyroidism,
osteomalacia,
osteogenesis imperfecta,
ricketts,
in patients who have undergone pelvic irradiation.
Common sites:
- hip region:
.
subcapital;
.
femoral neck (occur at the lateral portion of the femoral neck where tensile forces are most pronounced);
.
intertrochanteric;
- pelvic region:
.
sacral (In this location,
these fractures are usually oriented parallel to the sacroiliac joints with edema-like changes.
If no fracture line is evident bone marrow abnormalities may mimic other diseases,
such as avascular necrosis or metastatic disease,
depending on neighboring structures);
.
supra-acetabular (line paralel to the articular surface with surrounding edema);
.
pubic body or pubic rami.
B - TRANSIENT OSTEOPOROSIS OF THE HIP (TOH)
(Fig. 6,
Fig. 7 and Fig. 8)
• Seen in overweight middle-aged men and in women during the third trimester of pregnancy.
• Extensive bone marrow edema-like signal can be seen in the femoral head and neck,
eventually with joint effusion.
• Absence of additional,
circumscribed sub-chondral changes on T2- weighted or contrast-enhanced T1- weighted images has a 100% positive predictive value for the transient nature of TOH.
• Osteonecrosis is more probable if circumscribed subchondral areas of low signal intensity are present on both T1- and T2-weighted sequences.
Fig. 6: Coronal T2* Fat-Sat WI of the pelvis. Oedema of the head and neck of the left femur (arrows) with no fracture line seen.
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
C - PUBALGIA and OSTEITIS PUBIS
( Fig. 9 and Fig. 10 )
The anatomical muscle-tendinous complex around the symphisis pubis,
often responsible for groin pain in athletes,
includes:
.
inferiorly - the insertions of the adductor muscles and the gracilis muscle
.
superiorly - the conjoined tendon aponeurosis of the abdominal wall.
• Typical complaints are tenderness in the pubic symphysis (70%) and superior pubic ramus (40%),
usually due to increased mechanical stress across the symphysis with compromise of the ligamentous and capsule.
Secondary degenerative changes with vertical instabilitymay develop.
.
OSTEITIS PUBIS
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Features
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Imaging -Technique
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- variable widening of the symphysis with cortical irregularities,
erosions,
sclerosis,
and subchondral cysts
- Instability suggested when:
.widening is more than 7 mm
or
.vertical offset > 2 mm of the upper borders of the superior pubic is present
|
Standard plain films
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- irregular articular surface of the pubic bones,
bone marrow signal abnormalities on each side of the symphysis,
and subchondral cysts.
- increased signal on fluid-sensitive sequences is present within the symphysis and the adjacent soft tissue
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MRI
|
Fig. 10: Axial PD Fat-Sat WI of the pelvis. Evident oedema of the symphysis pubis.
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
.
TUMORS
Common tumors of the proximal femur are osteoid osteoma and osteoblastoma,
chondroblastoma,
chondrosarcoma,
multiple myeloma,
and metastasis.
A. METASTASIS ( Fig. 11 ,
Fig. 12 ,
Fig. 13 and Fig. 14 )
B. MYELOMA ( Fig. 15 ) /LYMPHOMA ( Fig. 16 )
Fig. 16: Axial T2 Fat-Sat WI of the pelvis. Hyperintense soft tissue mass (arrow) - lymphoma.
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
C.
PRIMARY BONE TUMORS
• Osteoid Osteoma ( Fig. 17 and Fig. 18 )
- In osteoid osteoma a small nidus surrounded by an edema-like signal is typically found and often CT is used to confirm the diagnosis.
• Chondroblastoma ( Fig. 19,
Fig. 20 and Fig. 21 )
In some types of tumors,
characterization of the lesion is possible.
For instance,
on MR imaging well-differentiated cartilaginous tumors may have a nodular appearance with high signal intensity on fluid-sensitive images and low signal foci representing calcification.
BONE TUMORS
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PLAIN FILMS
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CT
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MRI
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Main indication:
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Diagnosis
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Diagnosis
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Extension
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Advantages:
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- Better validated imaging method
- Most useful on diagnosis and differential diagnosis
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- Better in the assessment of bones in anatomically complex regions including the hip
- Cortical destruction and periosteal reaction may be better seen when compared with plain films
- May demonstrate subtle matrix calcification not seen in standard radiographs
|
- Evaluates the intramedullary and soft tissue extent of bone neoplasm,
such as: .metastasis,
.myeloma,
.lymphoma,
.giant cell tumor.
|
.
D. SOFT TISSUE TUMORS
Fig. 22: Axial T1WI of the pelvis. Right juxta-trochanteric mass with low-signal on T1 (arrows).
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
.
MUSCLES/TENDONS/BURSAE
A - MUSCLE STRAINS AND RUPTURE
( Fig. 25 ,
Fig. 26 ,
Fig. 27 ,
Fig. 28 and Fig. 29 )
• Muscle strain:
- typically involve the musculotendinous junction
- occur during eccentric contraction
- commonly seen in the rectus femoris muscle,
in the hamstrings,
adductor longus and magnus muscles.
• Muscle injuries can be classified on MR imaging.
• Sonography is very sensitive and cost effective in the early detection and grading of muscle injuries.
However,
MR imaging is often preferred because of the deep nature of the structures.
.
Muscle Strain Type
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Sonography features
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MRI features
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First - degree
(represents a minor degree of fiber disruption)
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- Loss of the normal pennated muscular architecture with linear hypoechogenicity within the muscle
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- Interstitial edema with a feathery muscle pattern (with or without hemorrhage,
which may appear hypointense,
depending on the stage of bleeding)
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Second - degree
(corresponds to a partial tear without retraction.
Part of the musculotendinous fibers is intact)
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- Hypoechoic defect with disruption of the normal architecture;
- Often associated with hematoma
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- Hematoma with intra- and extramuscular fluid
- Typically at the musculo- tendinous junction.
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Third - degree
(complete tear of the musculotendinous junction with retraction,
which allows the clinical the diagnosis)
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- Assess the extent of retraction
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- Assess the extent of retraction
|
Fig. 28: Coronal PD Fat-Sat WI of the left hip. Acute complete muscular rupture of the gluteus minimus.
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
B - TENDINOPATHY
In this category it should be considered:
1. Abductor tendinopathy ( Fig. 30 )
2. Adduction dysfunction
3. Hamstring injuries
B.1- Greater trochanter pain syndrome is usually caused by abductor abnormalities:
.
Seen in middle-aged or elderly women,
.
Typically the tendons of the gluteus medius and minimus are involved;
.
There may be tendinosis,
partial and complete tears,
and avulsion of the gluteus medius tendon from the trochanter
.
90% sensitivity and 95% specificity for the diagnosis of partial or complete tears of the gluteus medius and minimus tendons (due to the superficial position of the tendons)
.
partial tears are diagnosed by high signal intensity on fluid- sensitive sequences within the tendon that may have a normal diameter or may be thinned or thickened.
.
Focal areas of more than 1 cm in diameter superior to the greater trochanter are associated with tendon tears.
Abnormalities of the abductor tendons and muscle are also a common clinical problem after total hip arthroplasty (THA),
especially if a transgluteal approach has been used.
Fig. 30: Coronal PD Fat-Sat WI of the left hip. Tiny calcification (yellow arrow) with surrounding oedema at the enthesis of the gluteus medius muscle with bursitis (red arrows).
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
B.3- Hamstring Injuries
• Hamstring (biceps femoris,
semitendinosus,
and semi-membranosus) avulsion injuries and tendinopathy may be seen in young athletes performing soccer,
rowing,
sprinting,
and basketball players.
• Typically,
the proximal conjoined tendons of the hamstring muscles at the posterolateral ischial tuberosity are involved.
The semimembranous tendon originates anterolaterally of the conjoined tendon of the biceps femoris and the semitendinosus muscles.
• The spectrum of abnormalities includes:
.tendinosis;
.partial and complete tear;
.avulsion fractures.
C.
BURSITIS
• Trochanteric (subgluteus maximus) bursitis ( Fig. 31 )
- also a common cause of greater trochanteric pain;
- difficult to distinguish from abductor tendon abnormalities clinically;
- reported in up to 40% of patients with lesions of the gluteus minimus and medius;
- tuberculosis,
rheumatoid arthritis and other systemic inflammatory diseases are less common causes of this type of bursitis.
- fluid-filled bursa,
possibly with septations;
- enhancement of the wall after the intravenous administration of gadolinium,
can be seen.
Fig. 31: Coronal PD Fat-Sat WI of the right hip. Peri-trochanteric bursitis (arrows).
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
D - SNAPPING HIP SYNDROME
• Usually in young individuals.
• Presentation: pain and an audible or perceived snapping of the hip during movement such as exercise.
• Ethiology may be categorized as external ( Fig. 36 ),
internal,
and intra-articular:
.
EXTERNAL TYPE
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INTRA-ARTICULAR TYPE
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INTERNAL TYPE
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- Is due to catching of either the posterior iliotibial band (ITB) or the anterior aspect of the gluteus maximus muscle as it moves over the greater trochanter during flexion and extension of the hip joint;
- Typically a clinical diagnosis,
so imaging is seldom needed.
|
- Causes of this type include labral tears,
loose bodies,
synovial osteochondromatosis,
synovial folds,
and fracture fragments.
- Hip MR arthrography is usually used to assess for these intra-articular conditions
- Often require surgery for symptomatic relief.
|
- Often related to the iliopsoas tendon.
- The two most common locations of iliopsoas tendon snapping are at: the level of the iliopectineal eminence and the osseous ridge of the lesser trochanter.
|
Fig. 36: Coronal PD Fat Sat WI of the left hip. Diffuse thickening of the proximal left iliotibial band is seen with surrounding oedema.
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
.
OTHER CAUSES of Coxalgia
A. ISCHIOFEMORAL IMPINGEMENT
( Fig. 32 ,
Fig. 33 ,
Fig. 34 and Fig. 35 )
.
was first reported as a potential cause for hip pain in 1977 by Johnson.
.
may be a cause of hip pain and abnormalities of the quadratus femoris muscle.
• severe ischiofemoral narrowing (however measurements of the narrowed ischiofemoral space are yet in discussion);
• edema of the quadratus femoris muscle specially in association with sclerosis of the lesser trochanter;
• cystic changes of the ischium.
Fig. 35: Axial CT image shows right narrowing between the ischium and lesser trochanter.
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
B.
SACRAL AND LUMBAR PATHOLOGY
( Fig. 37 to Fig. 50 )
Common conditions such:
• Lumbar disc bulge
• Sciatica
• Lumbar facet joint sprain
• Spinal degeneration
• Sacroiliac joint pathology ( Fig. 44 to Fig. 50 )
may cause back pain or referred pain to the hip or groin.
Fig. 47: Coronal T2 Fat-Sat WI of the sacroiliac joints. Hyperintensity of subchondral bone marrow of the left joint, indicative of active inflamatory process in assimetric sacroiliac involvement (spondyloarthropathy).
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT
Back pain is typically caused by age related degenerative changes or by minor repetitive trauma.
Despite most patients with back pain have a benign condition,
serious destructive causes of back pain including malignancy ( Fig. 42 ),
infection ( Fig. 50 ),
ankylosing spondylitis ( Fig. 44 and Fig. 45 ) and spinal abscess,
by far more uncommon accounting for less than 1%,
must be considered during an initial evaluation (because overlooking them can have devastating consequences).
Fig. 42: Sagital T2WI. Osteosclerotic L5 bone prostatic metastasis occupying most of the vertebral body. L2 vertebral body haemangioma.
References: Hospital da Luz - MSK Imaging Unit - Lisbon/PT