Background: Proximal tibiofibular joint (PTFJ) ganglion cyst is a rare condition with a high rate of recurrence. Optimal treatment has not yet been determined. Purpose: We aimed to answer the following questions: (1) What are the most common treatments for PTFJ cysts and their associated recurrence rates? (2) What are the risk factors for failure to completely recover from symptoms? (3) What are the risk factors for cyst recurrence? Methods: A systematic review was performed using PubMed and EMBASE databases. Studies were assessed for inclusion and exclusion criteria, and quality analysis following the PRISMA guidelines. Information on demographic, clinical, and treatment characteristics was retrieved from articles. Results: The most common surgical treatment was cyst excision (75.3%). Patients with PTFJ arthrodesis and PTFJ resection had the lowest recurrence rates at 0% and 4.4%, respectively. Complete recovery from symptoms was more common in PTFJ resection (70.8%) than in PTFJ arthrodesis (42.9%). Risk factors for failure to achieve complete recovery from symptoms included intraneural compromise (odds ratio [OR] = 3.93), cyst recurrence (OR = 6.04), and being a contact sports athlete (OR = 9.85). Ligation of the articular branch of the peroneal nerve (PN) was a protective factor (OR = 0.29). A history of knee arthritis was the most important risk factor for cyst recurrence (OR = 20.01); PTFJ arthrodesis was a protective factor (OR = 0.04). Conclusion: This systematic review of level-IV studies found PTFJ resection or arthrodesis to be the most effective treatment options. Intraneural compromise of the common peroneal nerve, cyst recurrence, and participation in contact sports are risk factors for incomplete symptom recovery, and ligation of the articular branch of the PN is a protective factor. Knee arthritis is a risk factor for cyst recurrence. More rigorous study is needed.

Intraneural ganglion cysts (IGCs) are mucinous cysts located within peripheral nerves, often associated with an articular nerve branch and the adjacent synovial joint capsule. These cysts, while rare, can occur in various nerves, with the tibial nerve being an infrequent site. Tibial nerve IGCs are rare pathologies. We present a case of a tibial nerve IGC in a 78-year-old male patient with pre-existing grade III gonarthrosis. Furthermore, we performed a brief review of the existing literature for tibial nerve IGCs. To our knowledge, we present the second case of an IGC in a patient with known pre-existing gonarthrosis. This case raises the potential association between IGCs and degenerative knee pathologies and underscores the crucial role of early and accurate diagnosis. Differential diagnosis of nerve sheath tumors and extra-articular calf neuropathy is essential not only for definitive treatment but also to rule out more serious alternative diagnoses. While ultrasound-guided aspiration of cystic fluid with steroid injection and conservative management are also treatment methods defined in the literature, we believe that exploratory surgery is the critical point of treatment. Early and accurate diagnosis is paramount, as delayed diagnosis and treatment may cause persistent functional and sensory deficits.

The sciatic nerve is the body's largest peripheral nerve. Along with their two terminal divisions (tibial and fibular), their anatomic location makes them particularly vulnerable to trauma and iatrogenic injuries. A thorough understanding of the functional anatomy is required to adequately localize lesions in this lengthy neural pathway. Proximal disorders of the nerve can be challenging to precisely localize among a range of possibilities including lumbosacral pathology, radiculopathy, or piriformis syndrome. A correct diagnosis is based upon a thorough history and physical examination, which will then appropriately direct adjunctive investigations such as imaging and electrodiagnostic testing. Disorders of the sciatic nerve and its terminal branches are disabling for patients, and expert assessment by rehabilitation professionals is important in limiting their impact. Applying techniques established in the upper extremity, surgical reconstruction of lower extremity nerve dysfunction is rapidly improving and evolving. These new techniques, such as nerve transfers, require electrodiagnostic assessment of both the injured nerve(s) as well as healthy, potential donor nerves as part of a complete neurophysiological examination.

Intraneural ganglia are benign mucinous cystic formations that originate within the epineurium of peripheral nerves. Different treatments have been recommended, with an overall satisfactory outcome. In this paper, we aim to evaluate the long-term outcomes of surgical treatment of peroneal intraneural ganglia by reviewing our local institutional experience.

We performed a case series review of peroneal intraneural ganglia surgical treatment performed by the senior author. Demographic and surgical details were abstracted from the medical record for each patient. Electrodiagnostic studies and magnetic resonance imaging (MRI) were performed in all patients pre- and postoperatively.

Eight men were enrolled, with an average age at time of surgery of 47.5 years (range 28-68 years). Motor testing revealed a preoperative deficit of dorsiflexion, eversion, and toe extension in 7 patients, with a median preoperative Medical Research Council (MRC) score of 0/5. Sensory loss in the distribution of the common peroneal nerve was present in 7 patients. Mean clinical follow-up time was 113 months (range 32-189 months). Significant pain relief was achieved in all patients. Overall neurologic function was improved, more so for motor function. The median postoperative dorsiflexion, eversion, and toe extension at last follow-up were MRC score of 5/5. No complications occurred postoperatively. There was no clinical evidence of intraneural recurrence, as confirmed in postoperative MRI. In 2 patients, an extraneural cystic formation was visible in the anterior muscular compartment.

The data from our series support excellent long-term postoperative motor outcomes with a low recurrence rate. To avoid extraneural recurrence, resection of the superior tibiofibular joint is necessary.

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.

There are many causes for the paralysis of the external sciatic popliteal nerve , such as the intraneural ganglion cyst. In this case, we evaluate a 52-year-old woman with no relevant personal record, who was admitted with paresis of the right foot of 4 months of evolution associated with alterations in the sensitivity that rose up to the posterolateral region of the leg. The diagnosis was based on MR and cyst decompression and disconnection of the articular branch. Given the low incidence of these lesions, their origin is still subject to controversy. The most widely accepted theory is the unifying articular theory described by Spinner in the year 2003. Intraneural ganglion cysts must be included in the differential diagnosis of progressive paralysis of the sciatic nerve, lesions of the nerve root at L5 and nerve sheath tumours that start at the lateral compartment of the knee. The treatment of a fibular intraneural ganglion cyst must be surgical and the operation must be performed as soon as possible.

Clinical compression neuropathy caused by para-articular cysts is rare. Only recently, the unifying articular theory was proposed to clarify its true etiologic nature. The authors attribute 17 cases to this theory in order to illustrate the shift in the diagnostic and treatment protocol, and the possible impact on patient outcome.

Eight intraneural and nine extraneural cysts were included. The proposed diagnostic protocol includes electromyography and ultrasound, followed by magnetic resonance imaging to characterize the cyst. The proposed treatment protocol consists of (1) ligation of the pedicle connecting the cyst with the afflicted joint, (2) decompression of the nerve and, when needed and (3) disarticulation of the superior tibiofibular joint (in case of peroneal nerve involvement).

Outcome was good to excellent in all patients, with recovery of sensory and motor function. Cyst recurrence was observed in three intraneural cases (18 %). Analysis of our own diagnostic protocol showed that atypical compression neuropathies should follow a strict diagnostic protocol to exclude missing the presence of a cyst. Ultrasound needs to play a crucial role, with MRI for cyst characterization and pedicle identification.

Retrospective proof in favor of the articular theory was found in all cases. An explanation for the cyst recurrences was formed based on the articular theory. In addition, a diagnostic and therapeutic protocol is proposed for all atypical peripheral compression neuropathies with the ultimate goal to achieve optimal patient outcome.

We report a case of synovial cyst that induced the compression of the peroneal nerve. The patient presented with foot drop and impossibility to stand on his right heel associated with numbness of anterolateral surfaces of the right shin and the dorsal surface of the foot within a 1-month period. Based on the clinical examination and electroneuromyography data, the compression of nerve by soft elastic mass was confirmed. We treated the patient by total microsurgical excision of the soft elastic mass adherent to the right peroneal nerve at the top third of the patient's shin. Histological study revealed the cyst of synovial membrane. During the postoperative period, a force in extensors of the right foot was restored. On the seventh day, the patient began to step on his right heel, while the zone of tenderness and temperature hypoesthesia in the area of the peroneal nerve innervation remained.