MUSCULOSKELETAL RADOLOGY SECTON www.cambridge.org
Achilles tendonopathy/rupture Characteristics Describes pathology of the combined tendon of the gastro-soleus complex, which inserts onto the calcaneum. Three stages of injury: 1 Paratenonitis. 2 Tendonosis with or without paratenonitis. 3 Rupture partial or full. A complete tear may be acute or chronic, sometimes with no prior symptoms. Clinical features Relate to the stage of the injury: 1 Localised tenderness proximal to the insertion, and crepitus on ankle movement. 2 Tendonosis paratenonitis. Nodular thickening and degenerative change within the tendon presents as focal thickening within the tendon, which is only tender in the presence of paratenonitis. 3 Rupture classically a middle-aged patient (M > F) who undergoes a sudden, forceful contraction of gastro-soleus during infrequently performed sporting activity thought was kicked in the back of the leg. The classic gap may not be palpable, but Simmonds Test will be abnormal in the vast majority of ruptures (>95%). Achilles tendonopathy/rupture Radiological features USS and MR can be used in the diagnosis of all three stages of Achilles tendonopathy. USS: Normal tendon uniform thickness <7 mm. Tendonosis fusiform swelling. heterogeneous echo pattern. hypoechoic foci (mucoid degeneration). n an acute full-thickness tear, in the presence of good clinical signs there is no need for imaging; if there is doubt over partial continuity, then both USS and MR are diagnostic. Management Stage 1 NSADs, identify/eliminate triggers, stretching (eccentric loading), orthoses to correct any hindfoot malalignment (varo-valgus) and off load the tendon by a heel raise. Controversial role for local anaesthetics steroid injection into the paratenon. Operative treatment in the form of tenosynovectomy is only required if the above fails. 3 www.cambridge.org
A Z of Musculoskeletal and Trauma Radiology Ultrasound of a normal Achilles tendon. Achilles tendonopathy. Note the fusiform swelling within the proximal tendon (asterisk). Stage 2 n addition to the above, longitudinal tendon opening and excision of central necrotic tissue is performed, to promote healing within the degenerate area. Stage 3 Chronic rupture needs surgical reconstruction. Acute tears can be managed operatively (open or percutaneous repair) or nonoperatively by functional bracing or traditional serial casting. 4 www.cambridge.org
Achilles tendonopathy/rupture Ultrasound of ruptured Achilles tendon. Note the echo-poor haematoma between the two ends of the ruptured tendon. 5 www.cambridge.org
A Z of Musculoskeletal and Trauma Radiology Sagittal STR MR: High signal within the substance of the Achilles tendon, secondary to a partial rupture (arrow). 6 www.cambridge.org
Aneurysmal bone cysts Characteristics Can occur at any age. Commonest in 10 30 year olds with the majority arising prior to epiphyseal fusion. Any bone may be affected but most commonly occur in long-bone metaphyses, especially the lower limb. Aetiology unknown. Clinical features Pain associated with expansile lesions. Pathological fractures may occur. May be visible or palpable if sufficiently large. Aneurysmal bone cysts Radiological features Well-defined radiolucent cyst, often eccentric within bone. Marked soap-bubble expansion may be seen. Usually trabeculated with a thin intact cortex (narrow transition zone). No periosteal reaction (except when fractured). Within the spine, posterior elements are more commonly involved. May be mistaken for other cyst-like lesions see Bone cysts. MR/CT fluid levels within cyst due to blood sedimentation (in up to 35%). Management Curettage and bone grafting, or substitute grafting. f the ABC recurs, then consider bone cement rather than bone graft in the revision procedure. 7 www.cambridge.org
A Z of Musculoskeletal and Trauma Radiology Aneurysmal bone cyst: well-defined cyst seen expanding the head of the fibula. 8 www.cambridge.org
Aneurysmal bone cysts Aneurysmal bone cyst: coronal T1 and STR MR. The lesion is isointense on T1 and hyperintense on STR with a narrow zone of transition. 9 www.cambridge.org
A Z of Musculoskeletal and Trauma Radiology Ankylosing spondylitis Characteristics Spondyloarthropathy affecting 5/1000 of the Caucasian population only 10% develop significant symptoms. Predominantly a genetic aetiology (>90%) with HLA B27 conferring a relative risk increase of 120, although this is not the only genetic inheritance factor in ankylosing spondylitis. Young adults, M : F ¼ 3:1. Clinical features Thoracolumbar and lower back pain with stiffness. Buttock pain with radiation down the posterior thigh but not below the knee. Morning stiffness and night pain are common. Costochondral/costovertebral pain, sometimes causing respiratory disease. Coexistent plantar fasciitis, iritis (30%), Achilles tendonopathy, inflammatory bowel disease (10%), psoriasis (10%) and major-joint involvement (20%). Cardiac problems occur in 1%. Progressive lumbar flattening and thoracic kyphosis, in conjunction with soft-tissue flexion contractures of the hip produce the characteristic question mark posture. Further exacerbation of the thoracic kyphosis may be due to osteoporotic wedge fractures, which are not uncommon. Radiological features Sacroiliitis is a pre-requisite for diagnosis. Look for early marginal sclerosis on the iliac side of the sacroiliac joint (SJ), usually starting in the inferior 1/3 (synovial part) of the SJ. Complete SJ ankylosis is a late sign. Osteitis results in squaring of vertebral bodies. The earliest signs of spondylitis are manifest as small erosions at the corners of the vertebral bodies the so-called Romanus lesion. Syndesmophyte formation eventually lead to classical bamboo spine. Osteoporosis and kyphosis occur with long-standing disease. Extra-axial skeletal involvement mimics mild rheumatoid arthritis. Management NSADs and physiotherapy form the bulk of treatment. 10 www.cambridge.org
Ankylosing spondylitis Ankylosing spondylitis: squaring-off of the vertebral bodies with anterior syndesmophyte formation. 11 www.cambridge.org