Sequential MR imaging demonstrates evolution of a fibular intraneural ganglion cyst after knee dislocation

Abstract

The basis for the articular (unified) theory for the formation of intraneural ganglion cysts is a capsular disruption through which joint (cyst) fluid egresses into the articular branch and then a parent nerve (Spinner et al., 2003). Trauma has been associated with intraneural ganglion cysts. A recent meta-analysis revealed trauma being associated with intraneural ganglion cysts in 12% of cases (Desy and Spinner, 2014). Our group has described the pathoanatomy by which direct and indirect trauma may give rise to the most common form, fibular (peroneal), and its rarer corollary, tibial intraneural ganglion cysts, both derived from the superior tibiofibular joint (STFJ) (Lalezari et al., 2012; Spinner et al., 2012a,b;Cesmebasi et al., 2014). In direct trauma, there would be a force generated near the proximal leg/knee region that would affect the STFJ (Ogden, 1972(Ogden, , 1974Sekiya and Kuhn, 2003); in indirect trauma, forces would be translated from the ankle region (such as in ankle sprains or fracture) via the interosseous membrane to the proximal leg (Cesmebasi et al., 2014). A direct causeeffect relationship between traumatic injury and intraneural ganglion cyst formation has yet to be definitively established.A 20-year-old man tripped off a curb and fell on his left knee. He sustained a multi-ligamentous knee injury as a result from a knee dislocation. He presented to an emergency room with exquisite pain and foot drop from a common fibular nerve (CFN) palsy and was discharged after negative plain radiographs were obtained. Several days later, he noted increasing pain and was found to have elevated leg compartment pressures for which he underwent four compartment fasciotomies. MRI performed 7 days after the initial injury revealed a posterolateral corner injury involving disruption of the fibular collateral and posterior cruciate ligaments, posterolateral capsule, and the musculotendinous junction of the popliteus, lateral meniscus, and medial patellofemoral ligament. There was edema and thickening of the CFN extending from the fibular neck to a point just distal to the sciatic nerve bifurcation (Figs. 1A-1C). He was referred to colleagues at our institution for definitive care of the multi-ligament injury and the CFN injury. Repeat MRI 3 months after the injury confirmed the previous findings referable to the ligamentous injury. The CFN was markedly enlarged in the popliteal fossa. There was anterior and lateral compartment musculature atrophy consistent with denervation. Electromyography (EMG) confirmed a complete common fibular neuropathy. He underwent staged reconstruction over the course of 9 months: (1) exploration and nerve grafting of the left CFN with 2 cable grafts (9 cm in length) using the superficial fibular nerve; (2) high tibial wedge osteotomy with allograft bone graft; and (3) multi-ligament knee reconstruction. At last follow-up, 15 months post nerve grafting, he had no return of neurologic function but had regained a stable knee. It was recommended he undergo tendon transfer for persisten...

Intraneural ganglion cysts: a systematic review and reinterpretation of the world's literature

“…Understanding the etiology of these lesions has allowed for the refinement of surgical techniques. 77,132,138 Contrary to the most popular form of treatment (cyst resection) or even a more radical approach (nerve resection with or without nerve grafting or nerve transfer), 14,17,18,23,24,48,57,78,91,95,104,105,108,155,162,164,171 we recommend treating the articular branch connection and/or the joint. Even with isolated nerve transfer, 91 the articular branch remains connected to the neighboring joint, which would conceivably allow for cyst recurrence.…”

“…69,83,86,[88][89][90]107,124,141,147,149,160,161,175 Trauma, which was identified in 13% of patients, has also been found to play a role in intraneural ganglion cyst formation. Either direct articular trauma 17 or an indirect mechanism of injury, such as a torsional load applied away from the joint can cause a capsular defect that permits cyst fluid extravasation. 16,127,145 We believe that the articular (synovial) theory fits with the principle of Occam's razor and provides a single logical explanation for the formation of not only intraneural ganglion cysts but all para-articular cysts.…”

Imaging Nerve Pathology of the Knee: Magnetic Resonance Imaging and Ultrasound

“…Resultant capsular injury may be followed by extracapsular extension of fluid-filled cysts. 25 The extracapsular cyst migration may be extraneural or intraneural. The extraneural ganglia are more common and may cause external compression on the peroneal nerve and its branches.…”

Large Intraneural Ganglion Cyst in the Peroneal Nerve

“…The intraneural ganglion cyst is thought to be caused by a microtrauma of the peroneal nerve, followed by infiltration of the synovial cells from the superior tibiofibular joint into the nerve and production of the synovial fluid [ 1 ]. Identified risk factors for cyst formation include degenerative changes in the neighboring joint [ 1 ] and direct or torsional trauma [ 3 , 4 ]. Owing to the topographic distribution of fascicles of the common peroneal nerve, the fascicles of the deep peroneal nerve are usually affected more severely and prior to those of the superficial peroneal nerve [ 5 ].…”