Roentgen Coach Rheumatology

Erosions

Erosion, general aspects
Typically, they are located in the vicinity of capsular insertions on bone, referred to as "marginal" erosions.
Depending on the special anatomy of individual joints, erosions may have a typical location and extension as in the metacarpo-phalangeal and proximal interphalangeal joints of the thumb and the digits.
In addition to marginal erosions, two other types of bony erosion have been observed in the hands of patients with rheumatoid arthritis: compressive (pressure) erosions and resorptive erosions.
Compressive erosions are related to the effect of muscular forces acting on osteoporotic bones and are a prominent feature of many articular disorders. The muscular forces are considerable, particularly at the metacarpophalangeal joints.
Destruction of cartilage produces increased forces on the adjacent osteoporotic bone, leading to compression of the end of one bone to the other. Irregular notching and splaying of the apposing reciprocal bony surfaces are detected.
Resorptive erosions occur beneath inflamed tendon sheaths can be evident in the diaphyses and metaphyses of the phalanges without the appearance of abnormalities in the adjacent articulations. They are commonly observed at the distal end of the ulna and on the first metacarpophalangeal joint as well as on the first interphalangeal joint. The involved cortices appear thin, with fraying of the subperiosteal margin. Associated periosteal proliferation can be seen, although the finding is quite subtle.

Erosion of the Finger Joints

Erosion of the PIP-joints of the hands
At both proximal interphalangeal and metacarpo-phalangeal joint locations, the erosions are larger on the proximal bone that constitutes the joint which is explained that the areas uncovered from cartilage are more extensive at these sites.

Erosion of the MCP-joints 2 - 5
At both proximal interphalangeal and metacarpo-phalangeal joint locations, the erosions are larger on the proximal bone that constitutes the joint which is explained that the areas uncovered from cartilage are more extensive at these sites.
At the metacarpo-phalangeal joints, the radial aspect of the bone is more significantly affected than the ulnar aspect; the radiovolar portion of the metacarpal head may reveal the most prominent erosion.

Erosion of the MCP-joint I
In the thumb, a characteristic deep erosion may appear at the ulnar side of the volar aspect of the base of the distal phalanx about the interphalangeal articulation near the insertion of the flexor pollicis longus and at the radial and ulnar sides of the first metacarpo-phalangeal articulation.
The MCP I is a typical location of resorptive erosions which may be observed at the dorsal aspect of the first metacarpal bone subjacent to the extensor pollicis longus tendon.

Erosion of the IP I of thumbs
The IP I is a typical location of resorptive erosions which may be observed at the dorsal aspect of the first metacarpal bone subjacent to the extensor pollicis longus tendon and on the proximal phalanx at the insertions of the flexor pollicis brevis and adductor pollicis muscles.

Erosion of the DIP of fingers
Marginal erosions about the distal interphalangeal joints generally are small compared with those of the more proximal digital joints, although any distal interphalangeal joint can reveal focal marginal defects. The erosions at these articulations may be more common if coexisting osteoarthritis is present.

Erosion of the Wrist

Erosion in the ulnocarpal compartment
The most common location of a so-called resorptive erosion is at the distal end of the ulna where the bone is in close contact with the tendon sheath of the flexor carpi ulnaris tendon.
Erosion in the inferior radioulnar compartment
In the inferior radioulnar compartment, findings include shallow surface defects, which progress to become extensive scalloped erosions, and sharply angular surfaces on the distal portions of the radius and ulna. The intimate relationship of the radius and the ulna often leads to secondary compression erosions.
Erosion of the Triquetral and Pisiform Bones
Erosions of the triquetrum and the pisiform bones are common in early rheumatoid arthritis and occur at three sites: the proximal medial portion of the triquetrum, the distal medial portion of the triquetrum, and the adjacent surfaces of the triquetrum and the pisiform. Abnormalities at these three sites have been noted in 38 per cent, 23 per cent, and 41 per cent, respectively, of 100 rheumatoid arthritis patients.
Initially, a shallow marginal erosion can be seen on the proximal portion of the triquetrum at the medial limit of the radiocarpal compartment . Repeated contact with an irregular ulnar styloid process that projects through the opening of the prestyloid recess exacerbates enlargement of the osseous defect. These well-recognized compressive forces on the triquetrum may lead to flattening, sclerosis, and fragmentation of the ulnar styloid process and the triquetrum.
The medial limit of the midcarpal compartment is another site at which marginal erosion of the triquetral bone occurs. Abnormal pooling of contrast material may be seen at this site in an arthrogram of a wrist in a patient with rheumatoid arthritis. An associated marginal erosion of the adjacent hamate bone is frequent.
The pisiform-triquetral compartment is seen tangentially in "reverse" oblique radiographs made with the wrist in a semisupinated position. Arthrography of the wrist in rheumatoid arthritis frequently reveals a corrugated synovial pattern and lymphatic filling in this area. Plain radiographs may disclose superficial or deep erosion on the palmar surface of the triquetral bone and the dorsal surface of the pisiform bone. Because these abnormalities are not visible on posteroanterior radiographs and because they may be present even in the absence of narrowing of the radiocarpal and the midcarpal compartments and in the absence of erosion of the radial and the ulnar styloid processes, radiography in the reverse oblique projection is suggested for evaluation of the wrist in rheumatoid arthritis.
See also Ulnocarpal Swelling

Erosion in the Radiocarpal Compartment

Radial Styloid Process and Scaphoid
Synovial inflammation within the radiocarpal compartment leads to rheumatoid erosion of the distal end of the radius and the adjacent scaphoid bone. Although not so frequent as erosive abnormality of the ulnar styloid process, erosion of the radial styloid process has been noted in 11 per cent of rheumatoid wrists. At this site, there is an unprotected or "bare" area on the surface of the bone adjacent to the radial collateral ligament. Alterations on the lateral midportion of the scaphoid bone likewise are characteristic and have been noted in 36 per cent of rheumatoid wrists. This site also is devoid of cartilage and vulnerable to erosion. Irregular defects of variable size and eventual fragmentation of the bone are not unusual. Erosion and surface irregularity at this site must be distinguished from a normal degree of notching of the scaphoid, which is not uncommon.
Palmar Aspect of the Distal Radius
Radiocarpal arthrograms of the normal wrist show multiple finger-like projections that extend for a short distance beneath the distal end of the radius. These projections are the palmar radial recesses. In arthrograms of the rheumatoid wrist, the outline of a corrugated synovial lining within these recesses is visible. Radiographs of the rheumatoid wrist frequently reveal erosion of the neighboring bone. These erosions appear as irregular radiolucent shadows overlying the midportion of the distal radius in posteroanterior radiographs. Their palmar location is recognized more readily on steep oblique and lateral radiographs.

Erosion of the Carpometacarpal Radial Compartment
Marginal erosion of the trapezium adjacent to the attachment of the radial collateral ligament and on the radial aspect of the capitate bone has been noted. Marginal erosion of the radial aspect of the base of the first metacarpal bone indicates rheumatoid involvement of the first carpo-metacarpal compartment; scalloped erosion of the base of one or more of the other four metacarpal bones reflects synovial proliferation within the inter-metacarpal compartments.

Erosion of the Carpo-Metacarpal Ulnar Compartment

Erosion of the Feet

Erosion of the MTP-joint I
In the great toe, the changes in the metatarsal head and the proximal phalanx about the metatarso-phalangeal joint are accompanied by osteoporosis, joint space loss, and erosions of the adjacent sesamoids . To visualize the sesamoid abnormalities adequately, tangential radiographs frequently are required.

Erosion of the IP-joint I of greater toe
Especially characteristic is an elongated surface irregularity that appears on the medial margin of the proximal phalanx adjacent to the interphalangeal joint, and that may be associated with smaller erosions on the medial aspect of the adjacent distal phalanx. Abnormalities on the lateral aspect of the joint and articular space loss may not accompany this medial erosion. Although moderate-sized erosions about the central portion of the joint and articular subluxation occasionally are noted, severe destructive arthritis, as may be evident in psoriasis and Reiter's syndrome, is unusual at this site in rheumatoid arthritis.

		Erosion, general aspects Typically, they are located in the vicinity of capsular insertions on bone, referred to as "marginal" erosions. Depending on the special anatomy of individual joints, erosions may have a typical location and extension as in the metacarpo-phalangeal and proximal interphalangeal joints of the thumb and the digits. In addition to marginal erosions, two other types of bony erosion have been observed in the hands of patients with rheumatoid arthritis: compressive (pressure) erosions and resorptive erosions. Compressive erosions are related to the effect of muscular forces acting on osteoporotic bones and are a prominent feature of many articular disorders. The muscular forces are considerable, particularly at the metacarpophalangeal joints. Destruction of cartilage produces increased forces on the adjacent osteoporotic bone, leading to compression of the end of one bone to the other. Irregular notching and splaying of the apposing reciprocal bony surfaces are detected. Resorptive erosions occur beneath inflamed tendon sheaths can be evident in the diaphyses and metaphyses of the phalanges without the appearance of abnormalities in the adjacent articulations. They are commonly observed at the distal end of the ulna and on the first metacarpophalangeal joint as well as on the first interphalangeal joint. The involved cortices appear thin, with fraying of the subperiosteal margin. Associated periosteal proliferation can be seen, although the finding is quite subtle.
		Erosion of the Finger Joints
		Erosion of the PIP-joints of the hands At both proximal interphalangeal and metacarpo-phalangeal joint locations, the erosions are larger on the proximal bone that constitutes the joint which is explained that the areas uncovered from cartilage are more extensive at these sites.

		Erosion of the MCP-joints 2 - 5 At both proximal interphalangeal and metacarpo-phalangeal joint locations, the erosions are larger on the proximal bone that constitutes the joint which is explained that the areas uncovered from cartilage are more extensive at these sites. At the metacarpo-phalangeal joints, the radial aspect of the bone is more significantly affected than the ulnar aspect; the radiovolar portion of the metacarpal head may reveal the most prominent erosion.
		Erosion of the MCP-joint I In the thumb, a characteristic deep erosion may appear at the ulnar side of the volar aspect of the base of the distal phalanx about the interphalangeal articulation near the insertion of the flexor pollicis longus and at the radial and ulnar sides of the first metacarpo-phalangeal articulation. The MCP I is a typical location of resorptive erosions which may be observed at the dorsal aspect of the first metacarpal bone subjacent to the extensor pollicis longus tendon.
		Erosion of the IP I of thumbs The IP I is a typical location of resorptive erosions which may be observed at the dorsal aspect of the first metacarpal bone subjacent to the extensor pollicis longus tendon and on the proximal phalanx at the insertions of the flexor pollicis brevis and adductor pollicis muscles.
		Erosion of the DIP of fingers Marginal erosions about the distal interphalangeal joints generally are small compared with those of the more proximal digital joints, although any distal interphalangeal joint can reveal focal marginal defects. The erosions at these articulations may be more common if coexisting osteoarthritis is present.

		Erosion of the Wrist
		Erosion in the ulnocarpal compartment The most common location of a so-called resorptive erosion is at the distal end of the ulna where the bone is in close contact with the tendon sheath of the flexor carpi ulnaris tendon. Erosion in the inferior radioulnar compartment In the inferior radioulnar compartment, findings include shallow surface defects, which progress to become extensive scalloped erosions, and sharply angular surfaces on the distal portions of the radius and ulna. The intimate relationship of the radius and the ulna often leads to secondary compression erosions. Erosion of the Triquetral and Pisiform Bones Erosions of the triquetrum and the pisiform bones are common in early rheumatoid arthritis and occur at three sites: the proximal medial portion of the triquetrum, the distal medial portion of the triquetrum, and the adjacent surfaces of the triquetrum and the pisiform. Abnormalities at these three sites have been noted in 38 per cent, 23 per cent, and 41 per cent, respectively, of 100 rheumatoid arthritis patients. Initially, a shallow marginal erosion can be seen on the proximal portion of the triquetrum at the medial limit of the radiocarpal compartment . Repeated contact with an irregular ulnar styloid process that projects through the opening of the prestyloid recess exacerbates enlargement of the osseous defect. These well-recognized compressive forces on the triquetrum may lead to flattening, sclerosis, and fragmentation of the ulnar styloid process and the triquetrum. The medial limit of the midcarpal compartment is another site at which marginal erosion of the triquetral bone occurs. Abnormal pooling of contrast material may be seen at this site in an arthrogram of a wrist in a patient with rheumatoid arthritis. An associated marginal erosion of the adjacent hamate bone is frequent. The pisiform-triquetral compartment is seen tangentially in "reverse" oblique radiographs made with the wrist in a semisupinated position. Arthrography of the wrist in rheumatoid arthritis frequently reveals a corrugated synovial pattern and lymphatic filling in this area. Plain radiographs may disclose superficial or deep erosion on the palmar surface of the triquetral bone and the dorsal surface of the pisiform bone. Because these abnormalities are not visible on posteroanterior radiographs and because they may be present even in the absence of narrowing of the radiocarpal and the midcarpal compartments and in the absence of erosion of the radial and the ulnar styloid processes, radiography in the reverse oblique projection is suggested for evaluation of the wrist in rheumatoid arthritis. See also Ulnocarpal Swelling

		Erosion in the Radiocarpal Compartment Radial Styloid Process and Scaphoid Synovial inflammation within the radiocarpal compartment leads to rheumatoid erosion of the distal end of the radius and the adjacent scaphoid bone. Although not so frequent as erosive abnormality of the ulnar styloid process, erosion of the radial styloid process has been noted in 11 per cent of rheumatoid wrists. At this site, there is an unprotected or "bare" area on the surface of the bone adjacent to the radial collateral ligament. Alterations on the lateral midportion of the scaphoid bone likewise are characteristic and have been noted in 36 per cent of rheumatoid wrists. This site also is devoid of cartilage and vulnerable to erosion. Irregular defects of variable size and eventual fragmentation of the bone are not unusual. Erosion and surface irregularity at this site must be distinguished from a normal degree of notching of the scaphoid, which is not uncommon. Palmar Aspect of the Distal Radius Radiocarpal arthrograms of the normal wrist show multiple finger-like projections that extend for a short distance beneath the distal end of the radius. These projections are the palmar radial recesses. In arthrograms of the rheumatoid wrist, the outline of a corrugated synovial lining within these recesses is visible. Radiographs of the rheumatoid wrist frequently reveal erosion of the neighboring bone. These erosions appear as irregular radiolucent shadows overlying the midportion of the distal radius in posteroanterior radiographs. Their palmar location is recognized more readily on steep oblique and lateral radiographs.
		Erosion of the Carpometacarpal Radial Compartment Marginal erosion of the trapezium adjacent to the attachment of the radial collateral ligament and on the radial aspect of the capitate bone has been noted. Marginal erosion of the radial aspect of the base of the first metacarpal bone indicates rheumatoid involvement of the first carpo-metacarpal compartment; scalloped erosion of the base of one or more of the other four metacarpal bones reflects synovial proliferation within the inter-metacarpal compartments.
		Erosion of the Carpo-Metacarpal Ulnar Compartment
		Erosion of the Feet
		Erosion of the MTP-joint I In the great toe, the changes in the metatarsal head and the proximal phalanx about the metatarso-phalangeal joint are accompanied by osteoporosis, joint space loss, and erosions of the adjacent sesamoids . To visualize the sesamoid abnormalities adequately, tangential radiographs frequently are required.
		Erosion of the IP-joint I of greater toe Especially characteristic is an elongated surface irregularity that appears on the medial margin of the proximal phalanx adjacent to the interphalangeal joint, and that may be associated with smaller erosions on the medial aspect of the adjacent distal phalanx. Abnormalities on the lateral aspect of the joint and articular space loss may not accompany this medial erosion. Although moderate-sized erosions about the central portion of the joint and articular subluxation occasionally are noted, severe destructive arthritis, as may be evident in psoriasis and Reiter's syndrome, is unusual at this site in rheumatoid arthritis.