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Background: Intractable hallucal ganglion cysts (HGCs) are often a symptomatic and recurrent condition. Its connection with the ankle joint is not well understood. Our aim was to evaluate the relationship between tenosynovitis of the flexor hallucis longus (FHL) tendon at the level of the ankle with formation of an HGC. In addition, we sought to analyze the outcomes of cyst excision combined with ankle capsulorrhaphy., Methods: Nineteen patients with HGC who underwent surgical intervention were included between June 2016 and June 2019. Eight had known recurrences. Ankle arthrography and cyst excision were performed on all patients. Clinical evaluations included the American Orthopaedic Foot & Ankle Society (AOFAS) scores, visual analog scale (VAS), and evaluation of postoperative complications. The mean follow-up period was 16.5 ± 8.6 months., Results: Thirteen of the 19 HGCs (68.4%) had a connection with the FHL tendon sheath. Combined with ankle capsulorrhaphy, there was no recurrence after cyst excision. The VAS score decreased from 2.1 ± 1.5 to 0.4 ± 0.8, and AOFAS score significantly improved from 84.3 ± 8.7 to 97.4 ± 5.2 at final follow-up ( P < .001)., Conclusions: Most of these patients had a connection between the HGC and ankle joint. Ankle arthrography appeared to be useful for diagnosis, and cyst excision combined with ankle capsulorrhaphy was an effective treatment without cyst recurrence., Level of Evidence: Level IV, case series.

Case: Talocalcaneal coalition (TCC) is a common type of coalition, often neglected. This case is of a 10-year-old girl with a painful ankle mass, diagnosed with TCC and a ganglion cyst. Examination revealed stiff subtalar motion, a submalleolar prominence, and well-circumscribed, tender mass at the posteromedial ankle. Treatment options include short period of casting/observation, excision vs. aspiration of the cyst, resection of the TC coalition, or a combination of the above. She underwent TCC resection with cyst aspiration., Conclusion: At the 5-year follow-up, the patient's examination and imaging revealed normal motion without cyst recurrence, indicating resolution of the cyst with coalition resection.

Aim: To evaluate the factors affecting the clinical and radiological findings of juxtafacet cyst patients., Material and Methods: Between January 2011 and December 2018, eight patients diagnosed with juxtafacet cyst were reviewed, retrospectively. Patient demographics; signs and symptoms; and neurological examination, radiological, and surgical findings were noted., Results: The mean age was 54 years (range, 34â€"69 years) with five (62.5%) females and three (37.5%) males. There were nine juxtafacet cysts in eight patients. Five cysts (55.5%) were located at the L3â€"L4 level, two cysts (22.2%) at the L4â€"L5 level, and two cysts (22.2%) at the L5â€"S1 level. In all patients with L3â€"L4 cysts, the intercrest line was intersecting the spinal column at L4 vertebral body level. The most frequent symptoms were back pain and radiculopathy. Magnetic resonance imaging and computerized tomography revealed degenerative facet arthropathy in six patients (75%). Three patients (37.5%) had a medical history of trauma. One patient (12.5%) was treated conservatively. Seven patients (87.5%) were advised to undergo surgical treatment., Conclusion: Degeneration and instability are the main causes of juxtafacet cysts. They are mainly seen at the L4â€"L5 level due to higher movement capacity of this level. But, if the intercrest line intersects the spinal column at higher levels, degeneration and instability risks move to upper levels, and juxtafacet cysts may occur at the L3â€"L4 or upper levels.

Background: During the coronavirus disease (COVID-19) pandemic, people volunteered for sewing hand-made face masks. However, sewing-machine operating might be associated with high ergonomic risk and a negative impact on musculoskeletal health., Objective and Methods: This paper describes an ultrasonographic diagnosis of a foot ganglion - after sewing 300 face masks within two months using a foot-operated sewing machine., Results: The patient significantly improved after an ultrasound-guided aspiration and corticosteroid injection., Conclusion: In short, we highlight the importance of ultrasound examination in the management of work (overuse)-related disorders in occupational medicine practice.

Purpose: To investigate the prevalence and impact of ganglion cell layer cysts (GCLC) in patients with diabetic macular oedema (DME) under continuous anti-vascular endothelial growth factor (VEGF) therapy., Methods: The clinical findings and spectral domain optical coherence devices of baseline visits and follow-up after 12-24 and 36 months of DME patients under continuous anti-VEGF therapy were retrospectively collected and analysed for the impact of GCLC cysts. Previously established prognostic parameters were also assessed., Results: A total of 110 eyes of 110 DME patients (mean age 64 ± 10 years) were included. At baseline, 17% eyes had GCLC. With GCLC, the best-corrected visual acuity (BCVA) improvement was in mean 8.4 ± 2.4 Early-Treatment-Diabetic-Retinopathy-Study (ETDRS) letters less over the course of 36 months compared to the group lacking GCLC (p = 0.0009). Eyes with GCLC showed 68 ± 23.4 μm less central retinal thickness (CRT) decrease than eyes lacking GCLC (p < 0.0001). In the linear mixed effect models including external limiting membrane disruption, disintegration of inner retinal layer and epiretinal membrane, GCLC remained a statistical significant factor for the outcome parameter CRT, but missed statistical significance for BCVA., Conclusion: Ganglion cell layer cysts (GCLC) seem to impact outcome in DME in patients receiving long-term treatment. This prognostic factor warrants further evaluation in the context of already well-established outcome parameters., (© 2019 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Peripheral venous cannulation is one of the most commonly performed medical procedures in hospital medicine. The dorsal metacarpal veins are typically used for cannulation as they are easily accessible. We present the first case of an iatrogenic intratendinous ganglion cyst of the extensor digitorum tendon of the middle finger following intravenous cannulation.

Epidural steroid injection is one of the most commonly used non-surgical treatments for degenerative lumbar vertebral disease. Its use has increased as degenerative lumbar vertebral disease has increased in frequency. Concomitant complications are being reported more often. In this report, we report a rare case of iatrogenic hemorrhagic cyst following epidural steroid injection. The patient underwent operative treatment with complete resolution of his symptoms., (Copyright © 2017 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.)

Background: Intraneural ganglion cysts usually arise from the articular branch of the nerve. The relationship between intraneural ganglion cysts and trauma is not clear., Case Presentation: We report a case of a 62-year-old female with a rapidly progressive foot drop caused by a posttraumatic intraneural ganglion cyst of the deep peroneal nerve. We excised the ganglion cyst and performed nerve decompression. After the surgery, the patient had a functional recovery., Conclusions: The concurrence of an intraneural ganglion cyst and trauma may increase damage to the nerve, although it is difficult to diagnosis before an operation. Early diagnosis and early proactive interventions would likely be associated with a good outcome.

Background: A rare complication of hip arthroscopy is the development of a ganglion cyst. These cysts can affect structures surrounding the hip joint. In some cases, the femoral artery may be involved, leading to claudication or a pulsatile mass that can resemble an aneurysm., Case Description: We present the case of a 62 year-old male who complains of 3 months of right hip pain. Workup reveals a degenerative labrum with cam impingement. After a discussion of various treatment options, the patient elected for arthroscopy to correct the impingement. An anterior capsulotomy was created to establish access to the joint. Cam decompression was indicated to address the impingement. The patient developed a recurring ganglion cyst following the procedure that was not permanently prevented with cyst aspiration. Total hip arthroplasty with ganglion cyst decompression resolved the ganglion cyst and resolved the hip pain., Conclusions: This is the first case report that describes the development of a ganglion cyst following hip arthroscopy. Arthroplasty and ganglion cyst decompression in the presence of degenerative joint disease presents a viable treatment option for these cysts. Additionally, this case suggests interportal capsulotomy closure may prevent ganglion cyst development and should be considered when performing hip arthroscopy., Competing Interests: Conflicts of Interest: John Callaghn: Royalties and Consultant (DePuy – for intellectual property transfer of hip and knee implant designs). Royalties (Wolters Kluwer – for books edited) Board Membership (Journal of Arthroplasty, OREF, International Hip Society, Knee Society)

OBJECTIVE The etiology of intraneural ganglion cysts has been controversial. In recent years, substantial evidence has been presented to support the articular (synovial) theory for their pathogenesis. The authors sought to 1) perform a systematic review of the world's literature on intraneural cysts, and 2) reinterpret available published MR images in articles by other authors to identify unrecognized joint connections. METHODS In Part 1, all cases were analyzed for demographic data, duration of symptoms, the presence of a history of trauma, whether electromyography or nerve conduction studies were performed, the type of imaging, surgical treatment, presence of a joint connection, intraneural cyst recurrence, and postoperative imaging. Two univariate analyses were completed: 1) to compare the proportion of intraneural ganglion cyst publications per decade and 2) to assess the number of recurrences from 1914 to 2003 compared with the years 2004-2015. Three multivariate regression models were used to identify risk factors for intraneural cyst recurrence. In Part 2, the authors analyzed all available published MR images and obtained MR images from selected cases in which joint connections were not identified by the original authors, specifically looking for unrecognized joint connections. Two univariate analyses were done: 1) to determine a possible association between the identification of a joint connection and obtaining an MRI and 2) to assess the number of joint connections reported from 1914 to 2003 compared with 2004 to 2015. RESULTS In Part 1, 417 articles (645 patients) were selected for analysis. Joint connections were identified in 313 intraneural cysts (48%). Both intraneural ganglion cyst cases and cyst recurrences were more frequently reported since 2004 (statistically significant difference for both). There was a statistically significant association between cyst recurrence and percutaneous aspiration as well as failure to disconnect the articular branch or address the joint. In Part 2, the authors identified 43 examples of joint connections that initially went unrecognized: 27 based on their retrospective MR image reinterpretation of published cases and 16 of 16 cases from their sampling of original MR images from published cases. Overall, joint connections were more commonly found in patients who received an MRI examination and were more frequently reported during the years 2004 to 2015 (statistically significant difference for both). CONCLUSIONS This comprehensive review of the world's literature and the MR images further supports the articular (synovial) theory and provides baseline data for future investigators.

The etiology of intraneural ganglion cysts has been poorly understood. This has resulted in the development of multiple surgical treatment strategies and a high recurrence rate. We sought to analyze these recurrences in order to provide a pathoanatomic explanation and staging classification for intraneural cyst recurrence. An expanded literature search was performed to identify frequencies and patterns in cases of intraneural ganglion cyst recurrences following primary surgery. Two univariate analyses were completed to identify associations between the type of revision surgery and repeat cyst recurrences. The expanded literature search found an 11% recurrence rate following primary surgery, including 64 recurrences following isolated cyst decompression (Group 1); six after articular branch resection (Group 2); and none following surgical procedures that addressed the joint (Group 3). Eight cases did not specify the type of primary surgery. In group 1, forty-eight of the recurrences (75%) were in the parent nerve, three involved only the articular branch, and one travelled along the articular branch in a different distal direction without involving the main parent nerve. In group 2, only one case (17%) recurred/persisted within the parent nerve, one recurred within a persistent articular branch, and one formed within a persistent articular branch and travelled in a different distal direction. Intraneural recurrences most commonly occur following surgical procedures that only target the main parent nerve. We provide proven or theoretical explanations for all identified cases of intraneural recurrences for an occult or persistent articular branch pathway., (© 2015 Wiley Periodicals, Inc.)

Ganglion cysts around the elbow joint are rare, with fewer than 25 citations in the English-language literature, most of them case reports. Among the many causes of elbow pain, cysts are primarily a diagnosis that depends on advanced imaging. When an elbow ganglion or perineural cyst is symptomatic, treatment has ranged from nonoperative to surgical intervention. Our case is unique because it is the first documented ultrasound-guided aspiration and cortisone injection that successfully alleviated a patient's symptoms. The procedures and outcomes of minimally invasive ultrasound-guided aspiration and steroid injections have not been described for cysts around the elbow.

Unlabelled: The aim of this study was to characterize the morphology and immunophenotype of ganglion cysts (GCs) and explore their histogenetic origin., Material and Methods: A cross-sectional morphological and immunohistochemical study of 354 GCs used the following antibody panel: vimentin, specific actin, β-actin, smooth-muscle actin, smoothelin, h-caldesmon, β-catenin, desmin, calponin, podoplanin, keratins 5/6, E-cadherin, cyclooxygenase 2 (COX-2), lysozyme, CD10, CD31, CD33, CD34, CD68, Ki-67, and PCNA. Double-blind semi-quantitative analyses were conducted to evaluate the immunopositivity on a 4-point scale. Samples from 10 synovial membranes and 10 scapholunate ligaments were compared. GCs showed a hyalinized wall with mesenchymal spindle cells and were intensely positive for vimentin, actins, h-caldesmon, calponin in all cases and for podoplanin in 53% of cases, suggesting features of early muscle differentiation, without ruling out a myofibroblastic origin. Focal cavity lining of non-synovial flat or raised cells (CD34/CD31/CD10/E-cadherin-negative and podoplanin-positive in 34% of cases) was detected in 93% of cases, showing differential expression with synovial membrane and scapholunate ligament cells. Nuclear positivity for proliferative markers was observed in GC wall cells (258.1±255; 1019.3±316 positive cells/mm², Ki-67 and PCNA, respectively) but positivity for these markers was significantly lower (p⟨0.001 Mann Whitney U-test) in scapholunate ligament samples., Conclusion: In this first immunohistochemical study of GCs, focal cellular lining of the cavity was observed in almost all cases, and the immunophenotype was identical to that of GC wall cells. These cells are immunohistochemically different from synoviocytes and scapholunate ligament cells and show characteristics of myofibroblasts or mesenchymal cells undergoing early muscle differentiation.

We report an intra-articular ganglion cyst (IAGC) presenting as knee pain and a mass in a patient with longstanding Juvenile Idiopathic Arthritis (JIA). We could not find a similar case of an IAGC occurring in the knee of JIA patients in the literature. IAGC may need to be included as a possibility in patients with inflammatory arthritis with new-onset knee pain, especially in those with a palpable mass. MRI was useful in distinguishing IAGC from more worrisome causes of a knee mass. Orthopedic input was helpful in diagnosis and treatment. In addition, methotrexate therapy was effective in bringing about a long-lasting remission.

Arthroscopic meniscal repair has been a common procedure for the treatment of a torn meniscus, since the importance of meniscal preservation is widely understood. Over the years, the complications associated with suture material have been reported. Meniscal cyst is also one of those things. But ganglion cyst triggered by non-absorbable suture material was not documented in the literature. We report the case of a 19-year-old boy who underwent arthroscopic ACL reconstruction and repair of the medial meniscus by inside-out technique using 2-0 non-absorbable polyester sutures. The patient returned to our clinic at 4-year F/U with right knee pain due to medial meniscus tear and ganglion cyst. We suspect non-absorbable suture materials itself might have caused soft tissue irritation with repetitive trauma that lead to mucoid degeneration which results in ganglion cyst formation in the end., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Trauma has been loosely associated with the development of fibular intraneural ganglion cysts. Sporadic reports of direct trauma to the proximal lateral leg in the region of the superior tibiofibular joint (STFJ) capsule support the development of a capsular rent and the subsequent egress of joint fluid from the articular joint. This report provides evidence to suggest that indirect trauma from torsion can link concomitant ankle injury and fibular nerve palsy (foot drop) and fibular intraneural ganglion cysts. We present two cases to illustrate different potential mechanisms. One patient sustained an ankle ligamentous injury which was translated through the interosseous membrane (IOM) to the proximal leg region, affecting the STFJ and the fibular nerve (ascending pathway). The second patient had blunt injury to the popliteal fossa in combination with a twisting injury to the leg. In this latter case we offer two plausible explanations: (1) combined knee and ankle injury resulting in an ascending pathway mechanism; and (2) a knee injury which disrupted the STFJ, resulting in a translational force down the leg (descending pathway). We believe that fibular intraneural cysts from the STFJ result from direct and indirect trauma. Additional reports of similar cases and sophisticated biomechanical testing will allow us to delineate the exact mechanisms for these injury patterns., (© 2011 Wiley Periodicals, Inc.)

We report the case of a 72-year-old man who underwent surgery for a mobile spondylolisthesis L4-L5. Six months later, magnetic resonance imaging revealed an extradural cyst of the ligamentum flavum at L5-S1, which was then removed. Histological examination revealed a ganglion cyst of the ligamentum flavum. Cyst formation could be explained primarily according to the natural history of chronic degenerative disease of spine elements. Nevertheless, we could also consider the cyst formation as demonstrative of an adjacent segment syndrome: hypermobility of the L5-S1 segment just below three fixed vertebral segments would have triggered the mechanical stress necessary for L5-S1 ligamentum flavum degeneration.

The origin for complex intraneural cysts remains controversial despite recent emerging evidence to support their articular origin. The coexistence of intraneural and adventitial cysts has been described due to the proximate neurovascular bundle, i.e., the articular (neural) branch and vessels at the joint capsule. To clarify the pathogenesis, anatomically based imaging patterns can be identified. This paper characterizes a common finding identified on MRI describing the adventitial component originating from the superior tibiofibular joint (STFJ). MRIs of patients with fibular (peroneal) (n = 24) and tibial (n = 7) intraneural ganglion cysts were reviewed. Eleven patients with fibular intraneural ganglion cysts were identified as having a coexisting adventitial component. In all cases, the adventitial cyst extended from the anterior portion of the STFJ, within the capsular vessels, and along the anterior tibial vessels. The reproducible anatomy permitted the identification of an imaging pattern: the "vascular U" sign, consisting of cystic anterior tibial vessels running through the interosseous membrane between the proximal tibia and fibula. This sign was seen on axial MR image(s) obtained at the level of the fibular neck in all cases. To generalize these findings, the rare tibial intraneural ganglion cysts (derived from the posterior aspect of the STFJ) were examined; two cases had coexisting adventitial cysts with visualization of the vascular U sign. This new imaging pattern can improve the identification of adventitial cysts at the level of the STFJ., (Copyright © 2011 Wiley-Liss, Inc.)

The peroneal tubercle occurs in about one half of human feet. It size varies from a small nodule of less than 1mm height to a prominent spur up to 1cm in size. It had been noted to cause stenosing tenosynovitis of the peroneal tendons, especially in association with an accessory peroneal bone. The current manuscript describes two cases of symptomatic tenosynovitis developing after an ankle sprain with fracture of the peroneal tubercle. The tenosynovitis caused dysfunction of the peroneal tendons unresponsive to prolonged conservative therapy. Symptoms were resolved following surgical resection., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Two patients underwent arthroscopy-guided injections of autologous fibrin sealants to treat ganglion cysts causing suprascapular nerve palsies. After at least 2 years of follow-up, both patients had no suprascapular nerve symptoms and their external rotation strength had returned to normal. Magnetic resonance imaging revealed no evidence of ganglion cyst recurrence.

The pathogenesis of intraneural ganglia has been an issue of curiosity, controversy, and contention for 200 years. Three major theories have been proposed to explain their existence, namely, 1) degenerative, 2) synovial (articular), and 3) tumoral theories, each of which only partially explains the observations made by a number of investigators. As a result, differing operative strategies have been described; these generally meet with incomplete neurological recoveries and high rates of recurrence. Recent advances in magnetic resonance imaging and critical analysis of the literature have clarified the mechanisms underlying the formation and propagation of these cysts, thereby confirming the unifying articular (synovial) theory. By identifying the shared features of the typical cases and explaining atypical examples or clinical outliers, several fundamental principles have been described. These include: 1) a joint origin; 2) dissection of fluid from that joint along an articular nerve branch, extension occurring via a path of least resistance; and 3) cyst size, extent, and directionality being influenced by pressures and pressure fluxes. We believe that understanding the pathogenesis of these cysts will be reflected in optimal surgical approaches, improved outcomes, and decreased frequency, if not elimination, of recurrences. This article describes the ongoing process of critically analyzing and challenging previous observations and evidence in an effort to prove a concept and a theory.

Intraneural ganglion cysts have been considered a curiosity for 2 centuries. Based on a unifying articular (synovial) theory, recent evidence has provided a logical explanation for their formation and propagation. The fundamental principle is that of a joint origin and a capsular defect through which synovial fluid escapes following the articular branch, typically into the parent nerve. A stereotypical, reproducible appearance has been characterized that suggests a shared pathogenesis. In the present report the authors will provide a mechanistic explanation that can then be mathematically tested using a preliminary model created by finite element analysis.

Unlabelled: A deep peroneal intraneural cyst of the first web space of the foot is presented. Analysis of the magnetic resonance image scans revealed not only a connection with the medial aspect of the second metatarsophalangeal joint, but also the presence of an interconnected cyst within the lateral digital branch of the hallux. These characteristic magnetic resonance image findings are consistent with those previously described for a peroneal intraneural ganglion cyst that arose from the superior tibiofibular joint, and include (1) origin (ascent) from the second metatarsophalangeal joint with propagation along the articular branch and into the dorsal digital branch of the second toe, (2) cross-over within the shared epineurial sheath of the deep peroneal nerve, and (3) further propagation (descent) within the dorsal digital branch of the hallux. The analogous features between intraneural ganglion cysts affecting small and large-caliber nerves support the fundamental principles of the unified articular (synovial) theory for the formation of intraneural ganglia, including (1) a connection to a synovial joint, (2) dissection of joint fluid through a capsular rent along the articular branch into the parent nerve, and (3) intra-epineurial, pressure-dependent propagation of cyst fluid along paths of least resistance., Level of Clinical Evidence: 4.

We report a case of an asymptomatic post-tibial cyst with direct communication to the posterior orifice of the tibial tunnel after a posterior cruciate ligament (PCL) reconstruction. Two years earlier, the patient had undergone a PCL reconstruction using a transtibial technique through a lateral tibial tunnel and with a 10-mm bio-absorbable interference screw fixation. Magnetic resonance imaging (MRI) was taken with patient's consent when the patient re-visited our hospital to remove the metal post-tie screw. The patient was satisfied with the result and the cyst was an incidental finding. This complication appeared to be a consequence of direct communication between the joint and the post-tibial tunnel through the posterior orifice of the tibial tunnel because of the failed osteointegration of the graft. To our knowledge, this is the first report of cyst formation at the post-tibial tunnel after a PCL reconstruction.

Although the knee is a common location, a ganglion cyst arising from the proximal tibio-fibular joint (PTFJ) is relatively rarer. Unique diagnostic and management difficulties are encountered as these can extend into subcutaneous tissue, or spread along peroneal muscles and nerve, or erode adjacent bone. We report here a PTFJ ganglion cyst which was indolent for at least 12 years and then caused destructive and expansile changes in the fibula over a period of 6 years after a total knee arthroplasty (TKA), simulating a malignancy. Although no wear or foreign body reaction could be shown, this alarming progression of a PTFJ ganglion cyst in the fibula after the TKA is a noteworthy association, and has not been recognized and reported before. Awareness of such a lesion can aid in the diagnosis and prevent unnecessary aggressive management.

We describe the first reported case of an intraneural ganglion cyst, an ulnar ("cubital") intraneural cyst, which, on literature review, dated to 1810. For over 80 years, its original brief description by Beauchêne was wrongly attributed to Duchenne, effectively making the reference and specimen inaccessible to scrutiny. Fortunately, the intact cyst had been safely housed in the Musée Dupuytren, Paris, France, thus permitting its examination. Although originally described as a "serous" cyst, our present understanding of the anatomy of the ulnar nerve and of peripheral nerve pathology allowed us to reinterpret it as a mucin-filled, elbow-level, ulnar intraneural ganglion cyst. In addition to its description as a fusiform cystic enlargement of the nerve, we documented similar enlargement of a lumen-bearing branch, the articular branch at the level of the elbow. Based on our assessment of the specimen and with a modern perspective, we concluded that the origin of the cyst was from the postero-medial aspect of the elbow joint and that its fluid content, having dissected through a capsular defect, followed the path of the articular branch into the parent ulnar nerve. The purpose of this report is to clarify historical misconceptions regarding the pathogenesis of this controversial entity., ((c) 2008 Wiley-Liss, Inc.)

Ganglion cysts of the posterior cruciate ligament (PCL) are uncommon lesions found incidentally on MRI and arthroscopy. Twenty patients (11 males and nine females) with the mean age of 35 years presenting with a variety of knee signs and symptoms were found to have PCL cysts on MRI. Out of these, thirteen patients (65%) had isolated symptomatic PCL cysts and seven patients had associated chondral and meniscal lesions. Eight out of the 20 patients (40%) gave a history of antecedent trauma. On arthroscopy, the majority of the cysts were situated at the midsubstance of the ligament with inter-cruciate distension and no involvement of the substance of the ligament. The content of the cysts varied with the majority having yellowish viscous fluid and three containing serous and bloody fluid. All cysts were successfully treated arthroscopically through standard anterior, posteromedial and posterolateral portals with no signs of recurrence on MRI at a mean followup of 24 months. PCL cysts may clinically mimic meniscal or chondral lesions and preoperatively, MRI is essential for the diagnosis of ganglion cysts arising from the PCL. Ganglion cysts of the PCL can be successfully treated arthroscopically using standard portals.

Unlabelled: Intraneural ganglion cysts are rare in occurrence and most commonly involve the peroneal nerve at the fibular neck. We present a case of a traumatically induced intraneural ganglion cyst of the sural nerve that developed after a nondisplaced posterior malleolus ankle fracture. The intraneural ganglion cyst was connected to the subtalar joint by its articular branch and ascended several centimeters into the distal fourth of the leg. It was resected from the sural nerve proper and the posterior branch of the lateral calcaneal nerve, and the articular trunk was ligated. The patient developed subclinical intraneural recurrence, which was detected on a postoperative magnetic resonance imaging (MRI). Retrospective reinterpretation of the preoperative and postoperative MRIs revealed that ligation of the articular trunk proximal to a major branch (ie, the anterior branch of the lateral calcaneal nerve) led to increased intraneural cyst propagation distally: within the blind stump of the articular trunk and within several anterior branches of the lateral calcaneal nerve but not within the parent sural nerve or its continuation, the lateral dorsal cutaneous nerve. This mode of intraneural, but extraparental nerve recurrence can be easily understood by considering the altered fluid dynamics, particularly the increased resistance. This case report provides further evidence not only supporting the articular theory of intraneural ganglion formation but also highlighting the importance of searching for, identifying, and treating the pathologic articular branch connection near its joint connection in all cases., Level of Clinical Evidence: 4.

The appearances of intraneural ganglion cysts are being elucidated. We previously introduced the cross-over phenomenon to explain how a fibular (peroneal) or tibial intraneural ganglion cyst arising from the superior tibiofibular joint could give rise to multiple cysts: cyst fluid ascending up the primarily affected nerve could reach the level of the sciatic nerve, fill its common epineurial sheath and spread circumferentially (cross over), at which time pressure fluxes could result in further ascent up the sciatic or descent down the same parent nerve or the opposite, previously unaffected fibular or tibial nerves. In this study, we hypothesized that cross-over could occur in other nerves, potentially leading to the formation of more than one intraneural ganglion cyst in such situations. We analyzed the literature and identified a single case that we could review where proximal extension of an intraneural ganglion cyst involving a nerve at a different site could theoretically undergo cross-over in another major nerve large enough for available magnetic resonance images to resolve this finding. A case of a suprascapular intraneural ganglion cyst previously reported by our group that arose from the glenohumeral joint and extended to the neck was reanalyzed for the presence or absence of cross-over. An injection of dye into the outer epineurium of the suprascapular nerve in a fresh cadaveric specimen was performed to test for cross-over experimentally. Retrospective review of this case of suprascapular intraneural ganglion cyst demonstrated evidence to support previously unrecognized cross-over at the level of the upper trunk, with predominant ascent up the C5 and the C6 nerve roots and subtle descent down the anterior and posterior divisions of the upper trunk as well as the proximal portion of the suprascapular nerve. This appearance gave rise to multiple interconnected intraneural ganglion cysts arising from a single distant connection to the glenohumeral joint. The injection study also demonstrated the cross-over phenomenon and produced a similar pattern as the cyst dissection. This article illustrates that cross-over can occur in another nerve (apart from the prototype fibular nerve). Furthermore, understanding the more complex anatomic nature of the upper trunk cross-over model provides insight into important mechanistic information regarding the bidirectional propagation patterns and formation of primary and secondary intraneural ganglion cysts not afforded by the previously described sciatic nerve cross-over model., (Copyright 2008 Wiley-Liss, Inc.)

There is no animal model of ganglion. We describe a simple and reproducible animal model of pseudocystic diseases. First, we experimented to establish a pseudocystic model. We used cylindrical glass implants (6 mm diameter, 30 mm long) to create fibrous capsules in rats. The implants were inserted in the subcutaneous tissue in the dorsum of rats. Sixty implants were carried out (two implants per rat). Twelve weeks after implantation, the glass implants were removed and 0.5 mL sodium hyaluronate solution was injected into each cavity. Next, we tested the model by histological examination after OK-432 administration. Microscopic examination revealed that the wall was composed of a layer of collagenous fibers similar to those noted in ganglia; the lumen was retained for 3 weeks. Histopathological changes after OK-432 administration showed nonspecific inflammatory response induced by OK-432, resulting in in vivo activation of many inflammatory cells and then fast and reliable closure of cavities. No harmful reactions to OK-432 were observed histopathologically. These data suggest that our experimental cyst is a suitable model for studying pseudocystic diseases. This model can be used for research evaluating safe drug doses, conducting therapeutic comparison of several agents, and histopathological time course studies of the affected tissues. OK-432 administration on this model showed the potential of one of the ideal agents to treat pseudocystic lesions like ganglion.

New patterns of intraneural ganglion cyst formation are emerging that have not previously been explained in current pathoanatomic terms. We believe there are three important elements underlying the appearance of these cysts: (a) an articular branch of the nerve that connects to a nearby synovial joint; (b) ejected synovial fluid following the path of least resistance along tissue planes; and (c) the additional effects of pressure and pressure fluxes. The dynamic nature of cyst formation has become clearly apparent to us in our clinical, operative and pathologic practice, but the precise mechanism underlying the process has not been critically studied. To test our hypothesis that a fibular (peroneal) or tibial intraneural cyst derived from the superior tibiofibular joint could ascend proximally into the sciatic nerve, expand within it and descend into terminal branches of this major nerve, we designed a series of simple, qualitative laboratory experiments in two cadavers (four specimens, six experiments). Injecting dye into the outer or "epifascicular" epineurium of the fibular and the tibial nerves we observed its ascent, cross over and descent patterns in three of three specimens as well as its cross over after an outer epineurial sciatic injection. In contrast, injecting dye into the inner or "interfascicular" epineurium led to its ascent within the tibial nerve and its division within the sciatic nerve in one specimen and lack of cross over in a sciatic nerve injection. Histologic cross-sections of the nerves at varying levels demonstrated a tract of disruption within the outer epineurium of the nerve injected and the nerve(s) into which the dye, after cross over, descended. Those specimens injected in the inner epineurium demonstrated dye within this tract but without disruption of or dye intrusion into the outer epineurium. In no case did the dye pass through the perineurial layers. Coupled with our observations in previous detailed studies, these anatomic findings provide proof of concept that sciatic cross over occurs due to the filling of its common epineurial sheath; furthermore, these findings, support the unifying articular theory, even in cases wherein patterns of intraneural ganglion cyst formation are unusual. Additional work is needed to be done to correlate these anatomic findings with magnetic resonance imaging and surgical pathology.

Object: The pathogenesis of intraneural ganglia has been a controversial issue for longer than a century. Recently the authors identified a stereotypical pattern of occurrence of peroneal and tibial intraneural ganglia, and based on an understanding of their pathogenesis provided a unifying articular explanation. Atypical features, which occasionally are observed, have offered an opportunity to verify further and expand on the authors' proposed theory., Methods: Three unusual cases are presented to exemplify the dynamic features of peroneal and tibial intraneural ganglia formation., Results: Two patients with a predominant deep peroneal nerve deficit shared essential anatomical findings common to peroneal intraneural ganglia: namely, 1) joint connections to the anterior portion of the superior tibiofibular joint, and 2) dissection of the cyst along the articular branch of the peroneal nerve and proximally. Magnetic resonance (MR) images obtained in these patients demonstrated some unusual findings, including the presence of a cyst within the tibial and sural nerves in the popliteal fossa region, and spontaneous regression of the cysts, which was observed on serial images obtained weeks apart. The authors identified a clinical outlier, a case that could not be understood within the context of their previously reported theory of intraneural ganglion cyst formation. Described 32 years ago, this patient had a tibial neuropathy and was found at surgery to have tibial, peroneal, and sciatic intraneural cysts without a joint connection. The authors' hypothesis about this case, based on their unified theory, was twofold: 1) the lesion was a primary tibial intraneural ganglion with proximal extension followed by sciatic cross-over and distal descent; and 2) a joint connection to the posterior aspect of the superior tibiofibular joint with a remnant cyst within the articular branch would be present, a finding that would help explain the formation of different cysts by a single mechanism. The authors proved their hypothesis by careful inspection of a recently obtained postoperative MR image., Conclusions: These three cases together with data obtained from a retrospective review of the authors' clinical material and findings reported in the literature provide firm evidence for mechanisms underlying intraneural ganglia formation. Thus, expansion of the authors' unified articular theory permits understanding and elucidation of unusual presentations of intraneural cysts. Whereas an articular connection and fluid following the path of least resistance was pivotal, the authors now incorporate dynamic aspects of cyst formation due to pressure fluxes. These basic principles explain patterns of ascent, cross-over, and descent down terminal nerve branches based on articular connections, paths of diminished resistance to fluid flow within recognized anatomical compartments, and the effects of fluctuating pressure gradients.

We report a case of subcutaneous pretibial ganglion, with direct communication to the tibial tunnel after an autologous reconstruction of the anterior cruciate ligament with hamstring tendons. The tibial graft fixation was with a 9 mm poly-L-lactide interference screw 5 years earlier. The screw had undergone complete resorption at the time the cyst occurred. No joint inflammatory reaction or graft insufficiency was detected. The patient underwent cyst excision and curettage of the tibial tunnel with full recovery. This complication seems to be the consequence of a direct communication between the joint and the pretibial subcutaneous tissue through a fibrous tibial tunnel and would have occurred, as there is no full osteointegration of the graft due to the resorption of the bioabsorbable interference screw.

Ganglion cysts of the hand and wrist occur most frequently during the second through fourth decade and women are more frequently affected than men. Ganglion cysts may arise in any location in the hand and wrist but are usually adjacent to joins or tendons and sometimes bones. Patients often present with a history of an asymptomatic mass and many patients seek the advice of a physician because of the cosmetic appearance of the cyst. Observation is acceptable in most instances. Indication for operative treatment includes pain, interference with activity, nerve compression and ulceration of the mucous cysts.

Spinal extradural cyst is a rare cause of spinal cord or nerve root compression. We present a case which is unique due to both the young age of the patient and its distinctly acute haemorrhagic presentation. In what is normally considered a degenerative disease in older patients this has implications for the possibility of a traumatic aetiology in children. The literature on the classification of extradural cysts is reviewed.

We present a patient with an asymptomatic painless medial elbow swelling of one year's duration, which was diagnosed as a ganglion originating from a non-united avulsion fracture of the medial epicondyle with a pseudarthrosis. Medial elbow ganglia are unusual lesions typically arising from the medial aspect of the ulnohumeral joint capsule, often in combination with symptoms of cubital tunnel syndrome. To our knowledge, a ganglion arising from a pseudarthrosis has not been reported in the literature, and should be considered in the differential diagnoses of lesions encountered over the site of fracture non-union in proximity to a joint.