Tendon Subluxation

Porter D, McCarroll J, Knapp E, Torma J. Peroneal tendon subluxation in athletes fibular groove deepening and retinacular reconstruction. Foot Ankle Int 2005 26(6) 436-41. 

Certain abnormalities may not be visualised if the transducer pressure is too great. Fluid and effusions may be compressed, leading to underestimation of volume. When examining for a muscle hernia or tendon subluxation the pressure of the probe may prevent visualisation. Similarly, when assessing Doppler flow the vessels maybe inadvertently compressed. The use of copious ultrasound gel is the simplest way to avoid applying excessive pressure. 

Rupture of the superior peroneal retinaculum, which extends from the lateral aspect of the distal fibular to the calcaneus, may result in peroneal tendon subluxation. Sometimes there is an associated avulsion fracture of the lateral aspect of the distal fibula. Typically, the patient will complain of painful clicking of the ankle, particularly on dorsiflexion and eversion of the foot. The diagnosis is often obvious... 

Levine CD, Miller JJ, Stanislau G et al (1997) Sarcoid myopathy imaging findings. J Clin Ultrasound 25 515-517 Lopez-Ben R, Lee DH, Nicolodi DJ (2003) Boxer knuckle (injury of the extensor hood with extensor tendon subluxation) diagnosis with dynamic US - report of three cases. Radiology 228 642-646... 

Nehrer S, Breitenseher M, Brodner W et al (1997) Clinical and sonographic evaluation of the risk of rupture in the Achilles tendon. Arch Orthop Trauma Surg 116 14-18 Neustadter J, Raikin SM, Nazarian LN (2004) Dynamic sonographic evaluation of peroneal tendon subluxation. AJR Am J Roentgenol 183 985-988... 

Chronic inflammation of the synovial tissue lining the joint capsule results in tissue proliferation (pannus formation). Pannus invades cartilage and eventually the bone surface, producing erosions of bone and cartilage and leading to joint destruction. The end results may be loss of joint space, loss of joint motion, bony fusion (ankylosis), joint subluxation, tendon contractures, and chronic deformity. 

The end results of the chronic inflammatory changes are variable. Loss of cartilage may result in a loss of the joint space. The formation of chronic granulation or scar tissue can lead to loss of joint motion or bony fusion (called ankylosis). Laxity of tendon structures can result in a loss of support to the affected joint, leading to instabihty or subluxation. Tendon contractures also may occur, leading to chronic deformity. ... 

Disruption of the cranial third of the subscapularis tendon, either in isolation or associated with supraspinatus tendon tear, is often associated with biceps instability (Bennett 2001). When the cranial third of the subscapularis is torn, the biceps tendon tends to sublux superficial to it on cranial transverse scans and to rest in a normal position on caudal transverse scans (Fig. 6.117). When the subscapularis tear becomes complete, the biceps slips medially within the glenohumeral joint (Ptasznik and Hennesy 1995 Farin et al. 1995 Farin 1996 Prato et al. 1996). The US diagnosis of biceps tendon dis-... 

Fig. 10.71. Caput ulnae syndrome in rheumatoid arthritis. Schematic drawing of a transverse view through the distal radioulnar joint outlines the rupture of the triangular fibrocartilage (arrowheads) and marginal erosions at the distal radio-ulnar joint level due to intra-articular pannus (asterisks). As a result, the ulna subluxes dorsally (gray arrow). Pannus (star) inside the extensor carpi ulnaris tendon (open arrow) sheath leads to cortical erosions, tear of the retinaculum and tendon thinning and splitting. St, styloid of the ulna Rad, radius...

Instability of the peroneal tendons, including subluxation or dislocation, most often occur in skiers and... 

Fig.l6.50a,b. Peroneal tendon instability (type 1 injury). Transverse 12-5 MHz US images over the retromalleolar groove obtained a at rest and b during forced eversion and dorsiflexion of the foot. In a the superior peroneal retinaculum (arrowheads) is disrupted but still inserted onto the lateral malleolus (asterisk). The peroneus longus (pi) and peroneus brevis (pb) tendons lie posterior to the tip of the malleolus. Note the edematous changes in the soft tissues of the perimalleolar region. In b, the peroneal tendons are seen while subluxing over the lateral malleolus... 

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