Deep Fascia Condensation Mimicking Accessory Extensor Tendon Causing Snapping of Wrist: An Unusual Case

1. What is the "snapping phenomenon" of the wrist?
2. What are the causes of snapping of the wrist?
3. Why, in this case, was the anomalous structure causing snapping the deep facia condensation and not accessory tendon?
4. Other disorder reported due to condensation of deep fascia?

Snapping wrist phenomena is a clicking or catching sensation at the wrist joint during movement.¹ Snapping causes sudden jerky movement of the wrist during flexion or extension. The patient variably presents snapping as mild discomfort to painful movements.² Snapping wrist is termed as “trigger wrist” when associated with painful movements.¹ For diagnosis and confirmation of the etiology, detailed clinical examination is essential. Before planning the surgical management, an x-ray and MRI for confirmation is required. Ultrasound provides an impressive tool for investigating the snapping of the wrist. It provides good contrast images of soft tissues and tendon. Also, it provides real-time kinematic assessment of the bony cortical surfaces in relation to the snapping movement of the wrist.² Therefore this modality is especially helpful when snapping is due to bony remodeling.³

Snapping across a joint usually results from intraarticular pathology that impinges the wrist joint, like torn ligaments or bony carpal fragments and abnormal extraarticular structures like accessory tendons or tendon nodules. Intraarticular causes of snapping are uncommon. The painless dorsal snapping of wrist was reported after a fall, resulting in thickened dorsal radiotriquetral ligament indenting on the radiolunate articulation during wrist flexion and extension.⁴ Similarly, few cases of snapping are reported due to abnormality of carpal bones and cartilaginous loose body of the radiocarpal joint.^3,5 Extraarticular causes resulting in snapping of the wrist are abnormal accessory extensor tendons,^6,7 tenosynovitis of extensor muscle causing muscle rupture,⁷ and ganglion originating from the flexor tendon originating in the carpal tunnel.⁸

In this case, the cord-like structure had a broad base fascial origin from the subcutaneous tissue with no tendomuscular junction or muscle origin intraoperatively. Histopathological examination of the excised surgical specimen revealed the presence of collagenous tissue and absence of fibrosis. The cord-like structure was subcutaneously placed above the extensor retinaculum at the wrist level with no relation to the extensor muscles of the hand, all placed at their normal anatomical position in respective extensor compartments. Due to subcutaneous location, no tendomuscular junction/ muscular origin proximally, placement of the cord-like structure above extensor retinaculum at wrist level, and collagenous nature, it can be concluded that this anomalous structure is a condensation of the deep fascia at the ulnar border of the extensor aspect of forearm causing snapping of the wrist.

Very few disorders have reported abnormalities of deep fascia. These are systemic illnesses that also involve deep fascia, but snapping of wrist is not reported with these illnesses.

Shulman syndrome: Also known as eosinophollic fasciitis, it is a progressive connective tissue disorder that presents as firm, symmetric, and painful swelling of the skin and soft tissue of extremities leading to restricted joint movements.⁹ Histologically it is characterized by diffuse infiltration of lymphocytes and eosinophils. The diagnosis requires a clinical examination supported by laboratory findings. There is no fixed laid-down criteria for its diagnosis. Strong clinical suspicion with the radiological examination (MRI/PET) and full-thickness biopsy of skin including soft tissue confirms the diagnosis. Systemic steroids and immunosuppressive drugs are the mainstays of the treatment.

Myofascial pain syndrome (MPS): It is a syndrome that combines sensory, motor, and autonomic symptoms associated with regional and referred pain. The commonly involved area is the trunk, shoulder, neck, or limb. This causes weakness and a restricted range of movement.¹⁰ In addition, the syndrome is usually associated with other initiating events like trauma, overactivity, and overuse of a particular group of muscle, abnormal posture, repetitive strain, disorders like spondylitis, scoliosis, and metabolic abnormalities like hypothyroidism. Though the pathophysiology is not clearly understood, the regional pain starts from myofascial trigger points from taut bands of muscle and surrounding fascia.¹¹ The diagnosis is by clinical examination, general diagnostic criteria with presence of trigger points and pain upon palpation, a referred pain pattern, and a local twitch response.¹² The principle of management of myofascial syndrome is the treatment of myofascial pain syndrome and associated precipitating factors.⁶

Snapping wrist is a complex phenomenon that results from various causes. The condition requires thorough clinical assessment with radiological investigation before planning surgical management. Surgical correction of the causative factor results in complete relief from symptoms. Abnormal condensation of deep fascia mimicking the extensor tendon may cause snapping wrist phenomenon and is correctable by surgical excision. Abnormal condensation of deep fascia needs to be considered as differential when a patient presents with snapping wrist phenomenon.

Affiliations: ¹Department of Burns & Plastic Surgery, All India Institute of Medical Sciences, Raipur, Chhattisgarh; ²Department of Orthopedic Surgery, All India Institute of Medical Sciences, Raipur, Chhattisgarh; ³Department of General Surgery, All India Institute of Medical Sciences, Raipur, Chhattisgarh

Correspondence: Dr. Jiten Kumar Mishra; mishra.jitenkumar@gmail.com

Disclosures: The authors disclose no financial or other conflicts of interest.