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Synovial Cyst

Mucous Cyst

A synovial cyst is the result of a degenerative process in the facet joint with varied etiology. Although benign in most cases it can cause pain and cramps in the back and legs. Treatment is by conservative or surgical procedures. 


The most frequent clinical finding is radicular pain and/or motor or sensory dysfunction. Kao, et al., [13] is one of the first to report a case of symptomatic lumbar synovial cysts in three elderly patients with manifestation of nerve root pain. 

Neurogenic claudication is the second most frequently encountered symptom from 10 to 44% cases [5], [11]. Neurological defects include sensory deficits (10 to 43%), motor deficits (20 to 27%) and reflex abnormalities (up to 57%) [7], [5], [14], [15]. Other signs and symptoms are: cauda equina syndrome (1 to 13%) [16], [10], [7], [16], [5], [17], [18], lateral recess [19] and spinal stenosis syndromes [20], [21]. 

The symptomatology of lumbar synovial cyst is usually nonspecific and tend to mimic other spinal diseases (spondylosis, herniated disc, spinal stenosis). As the cyst develops, it impinges on the parasympathetic fibers to vital organs (bladder, bowel, reproductive organs), or a single dorsal root, which accounts for the diagnoses of cystocele, enterocoele, atypical sciatica, and prostatic hypertrophy [22]. Pain at night and with recumbency are considered to be the result of stretching of spinal roots over the cyst. Symptoms tend to be on-and-off as the cysts develop and multiply under mechanical stress. Mobility of roots and presence of wide intradural space permit lumbar synovial cysts to grow  big enough as to exacerbate symptoms and worsen prognosis for a successful outcome of treatment.

Paralabral hip cyst is linked to anterior hip pain, difficulty of rotatory movements, painful flexion, and snapping sensation.

Baker's cysts in the knee become evident only when the patient is undergoing neuroimaging  for some other ailment.

Spontaneous Hemorrhage
  • Few cases of spontaneous hemorrhage into synovial cysts have been reported in the literature.[ncbi.nlm.nih.gov]
  • This article describes a case of subacute cauda equina syndrome resulting from spontaneous hemorrhage into an upper lumbar synovial cyst. A 65-year-old man presented with a 3-month history of intermittent bilateral lumbar pain.[ncbi.nlm.nih.gov]
Lower Extremity Pain
  • This patient developed sudden worsening of symptoms with bilateral lower extremity pain, weakness, and radiculopathy with difficult voiding.[ncbi.nlm.nih.gov]
  • A 60-year-old woman presented with low back pain, right lower extremity pain, and paresthesias. Magnetic resonance imaging revealed a right L5-S1 facet joint cyst, which compressed the right L5 nerve root.[ncbi.nlm.nih.gov]
Arm Pain
  • A 47-year-old female school teacher with a six-week history of left-sided scapular and arm pain is presented.[ncbi.nlm.nih.gov]
Forearm Pain
  • A 37-year-old pregnant woman presented with progressive forearm pain at the gestational age of 12 weeks.[ncbi.nlm.nih.gov]
Soft Tissue Swelling
Leg Swelling
  • A 48-year-old female patient presented with leg swelling and a history of recurrent femoral venous thrombosis caused by a ganglion originating from the left hip joint.[ncbi.nlm.nih.gov]
  • Postoperatively, the patient developed worsening dysphagia and hoarseness. Failure to recognize this rare entity preoperatively resulted in unnecessary intradural exploration and cranial nerve morbidity.[ncbi.nlm.nih.gov]
Lower Abdominal Pain
  • A 67-year-old woman with rheumatoid arthritis (RA; Steinblocker stage IV, class 4) who had RA onset at 34 years of age had anterior thigh pain, femoral neuropathy and lower abdominal pain.[ncbi.nlm.nih.gov]
  • Postoperatively, the patient developed worsening dysphagia and hoarseness. Failure to recognize this rare entity preoperatively resulted in unnecessary intradural exploration and cranial nerve morbidity.[ncbi.nlm.nih.gov]
Thigh Pain
  • A 67-year-old woman with rheumatoid arthritis (RA; Steinblocker stage IV, class 4) who had RA onset at 34 years of age had anterior thigh pain, femoral neuropathy and lower abdominal pain.[ncbi.nlm.nih.gov]
Preauricular Swelling
  • The patient presented with a right preauricular swelling, 1cm anterior to the tragus. A computed tomography (CT) scan showed a small oval hypodense mass of soft tissue in the right temporomandibular region with no relation to the condyle.[ncbi.nlm.nih.gov]
  • We report the case of a 51-year-old woman who presented with dysarthria and tongue fasciculation.[ncbi.nlm.nih.gov]
Anterior Thigh Pain
  • A 67-year-old woman with rheumatoid arthritis (RA; Steinblocker stage IV, class 4) who had RA onset at 34 years of age had anterior thigh pain, femoral neuropathy and lower abdominal pain.[ncbi.nlm.nih.gov]
  • We present a case report of a 45-year-old man who presented with new onset weakness and ataxia. Physical examination revealed decreased motor function in all extremities as well as positive Hoffman sign and ankle clonus bilaterally.[ncbi.nlm.nih.gov]
  • Physical examination revealed decreased motor function in all extremities as well as positive Hoffman sign and ankle clonus bilaterally.[ncbi.nlm.nih.gov]


Lumbar spine imaging will confirm the observations obtained from physical examination and history-taking. Initially, plain radiographs can facilitate differential diagnosis.  Follow up by CT scan will reveal the presence of low density epidural cystic lesions with  a posterolateral juxta-articular location, a hyperintense rim with calcification, and hypointense, gaseous contents [23].

MRI is  the method of choice  because of its high sensitivity permitting detection of the cyst from all angles and evaluation of pathognomonic signs of degenerative spondylolisthesis and facet hypertropy. 

The appearance of cysts in MRI is varied depending on their content (blood or gas) [24] or degree of calcification of the cyst's wall.

Para-articular cysts are readily seen in routine imaging examinations, whether clinically asymptomatic or associated with pain, swelling, or impaired joint function, or with underlying joint disorders (trauma, degeneration, inflammation).

Paralabral cysts of the shoulder are not usually detected in MRI but are nonetheless important as causes of compression neuropathy of the suprascapular or axillary nerve wherever they occur, along with other manifestations . A paralabral cyst is seen as a focally well-defined sac containing fluid within 1 cm of the glenoid labrum. Cysts are either unilocular or multilocular, however MR arthrography is limited unless a T2 sequence is done. Confluence between a cyst and joint is not a usual finding.


Treatment is either conservative or surgical although the former is preferred if the synovial cyst wall is not calcified and the patients's symptoms show gradual improvement. Cases  of spontaneous remission were presumed to be the result of cyst wall collapse or abatement of inflammation . Epidural injection of corticosteroids or into the corresponding facet joint may reduce inflammation and provide temporary relief in up to 70% of patients [25].

Surgery is the ultimate but safe prescription in cases of intractable pain and persistence of other symptoms despite conservative therapy [24]. This will entail exposing a wide area to gain access to the lesions which are usually covert. Therefore, care must be taken to minimize invasive surgical procedures and to preserve adjoining normal tissues. Long-term follow up of the results will help determine whether this approach is effective enough as to eliminate the necessity for fusion. 

Lumbar synovial cyst surgery includes:

  • unilateral or bilateral laminotomies,
  • hemilaminectomies, 
  • laminectomies alone or in combination with in situ or instrumented fusion.

Surgical decompression and excision is prescribed for refractory cases. Decompression and primary fusion is recommended for patients with concomitant degenerative spondylolistheses and lumbar synovial cysts [26].

Treatment for bursal cysts resulting from acute trauma includes nonsteroidal anti-inflammatory medication, rest, decompression, and immobilization of the affected limb. Treatment of cysts secondary to other conditions include the corresponding prescriptions for those conditions such as gouty arthritisrheumatoid arthritisosteoarthritis, and antibiotics for infected cysts after being surgically drained. 

Other conditions which are known to respond to treatment by surgical excision:

  • non-bursal cysts 
  • enlarged adventitial bursal cysts caused by osteochondroma
  • enlarged Baker's cyst from intra-articular causes
  • ganglion cysts, meniscal cysts, and extraneural cysts. 


Synovial cysts can be removed with a tubular retractor instrument with the aid of a microscope or endoscope. This procedure has the advantage of minimizing soft tissue damage from the operation, extent of the incision, hemorrhage, and disruption of ligaments and bony structures. This precaution is particularly important when synovial cysts co-exist with spondylolisthesis, reducing the risk of complications and the need for fusion.

Clinical studies have shown that lumbar synovial cysts are the common cause of low back pain (LBP) and lumbar radicular pain. Patients with persistent LPB deserve thorough history-taking and physical examination for further screening and referral to a specialist. Advanced neuroimaging investigation is indicated for patients with focal neurological deficits, pain at night or in recumbent position, or who are refractory to conventional (non-invasive) treatment. Early case finding and treatment prevent complications while preoperative diagnosis will help assess the risks in surgical intervention.  

Following decompression the patient may develop progression or experience recurrence of olisthy, while those who undergo fusion do not exhibit the same postoperative effects. Outcome indicators at 1 to 2 year postoperative intervals include surgeon-based but not patient-based analysis.

Baker's cysts are notorious progenitors of synovial fistulae and are prone to infection. The strategy for cure is , firstly, to treat the underlying cause of the synovial knee cyst followed by arthroscopic treatment of injuries to the articular meniscus, cartilage, and cruciate ligament.


Although the etiology of lumbar synovial cysts is presently unclear it is generally associated with advanced deterioration of the facet joint. Cysts are usually found in close proximity to degenerated joints in older individuals. Segmental instablity and trauma may likewise characterize the disease as it is in rheumatoid arthritis [3]. Empirically, the predisposition to synovial cyst formation includes facet joint degeneration, trauma, spondylosis and spondylolisthesis.  Most cysts have been found at the L4/5 level of the lumber spine which affects mobility.

Synovial cyst of the hip joint is due to a chronic inflammatory process. However, the condition is extremely rare and is usually asymptomatic, progresses slowly, if at all, and manifests only when severe complications ensue, requiring medical intervention. Color duplex Doppler ultrasonography (CDDS) is the method of choice for early diagnosis. 

Synovial cyst causing femoral vein compression is rare; adventitial cyst is even more infrequent. CDDS or MRI can reveal the presence of cysts in the lesions but does not differentiate between these two types. On closer inspection, there is a visible demarcation between the cyst and the femoral vein but not in the case of adventitial cyst. Their histology is identical, having the same tissue origin. Four cases of femoral vein synovial cyst have been reported in the literature. 

Synovial cysts in the knee have varied origins including: meniscal cysts of intra-articular pathology, irritated and inflamed bursae, and other entities (Baker's cyst or popliteal cyst, intra-articular and extra-articular ganglia, and extraneural cysts).


The true incidence of lumbar synovial cysts is difficult to estimate since most individuals harboring these cysts remain asymptomatic until the condition becomes patent due to massive impingement on adjacent nerves. Synovial cysts in the spine are more numerous than those in the cervical and thoracic areas [4]. The ages of patients vary from 28 to 94 years, but majority are in the mid 60s [3].

Estimates of female:male ratio likewise vary among researchers thus, female bias has often been reported [3] while others refute that observation [6]. Female:male ratios of 1:1 [5], 2:1 [7] [8] [9], 3:1 and 4:1 have been cited [10] [11].  

Hip joint synovial cysts are frequently found in patients with rheumatoid arthritis [1]. Despite many cases that undergo arthroplasty for rheumatoid hips, the finding of synovial hip joint cysts is extremely rare. The implication is that asynovial cyst should be considered in the differential diagnosis of painless groin mass, especially in patients with rheumatoid arthritic.

Sex distribution
Age distribution


Synovial cysts are common in limb joints; intraspinal synovial cysts are uncommon. Limb joint cysts can cause low back pain and lumbar radiculopathy whereas lumbar zygaphophyseal joint cysts are linked to degenerative changes. This appears to be attributed to a dysfunctional segment at L4-L5, followed by L5-S1. 

Facet synovial cysts are present in degenerative spondylolisthesis [12] while lumbar synovial cysts are associated with trauma. Less commonly isolated ganglion cysts can be found in the same site but are without synovial lining.

Paralabral cysts can develop in multiple foci, usually at hip and shoulder joints, and to a lesser extent at the knee and wrist. Labrum tears are common, due to:

  •  dysplastic hips
  •  trauma from excessive activity i.e., sports injuries
  •  degenerative hip arthrosis .

Misalignment of the head of the femur with the acetabulum causes increased pressure within the joint during flexion and rotation of the hip joint. Thereupon, synovial fluid leaks through the labrum into the surrounding soft tissues.

The pathophysiology of benign knee cysts differs with the specific cause although there is commonality. For instance, a sac-like structure is formed as a natural reaction to trauma or biochemical irritant, or infection, for that matter. An epithelial-lined bursa is one such example and likewise subject to the same offensive. In time, the space within the bursa then becomes filled with fluid or exudate from damaged or pathological tissues. This then becomes a benign mucoid cyst if not resorbed. 


The goal of medical intervention is surgical extraction of cysts that grow and cause pain and to prevent complications if left untreated or when conservative (non-invasive) treatment is ineffective. Surgery for spinal cysts involves decompression and excision with or without spine fusion. The procedure entails removing the cyst and merging the affected facet joints to prevent recurrence. Patients who wish to resume  normal physical activities may opt for surgery. 


Synovial cysts are sac-like outgrowths from the membrane lining of facet joints which contain fluid. These can develop around any synovial joint in the body, bursae or tendon sheaths with or without communication between joints. The cyst wall is made up of a cuboidal or pseudostratified columnar epithelium which becomes calcified in the diseased state.

Inflammatory and non-inflammatory (osteoarthrosis) as well as post-traumatic joint diseases have been associated with the presence of synovial cysts. Ganglion and synovial cysts are most frequently isolated from lesions at the ankle and dorsum of the foot presenting with similar symptoms as those found on the wrist [1]. Pain, impaired joint movement or nerve sequestration (e.g. as in tarsal tunnel) may occur due to mass effect [2].

Although usually benign, synovial cysts in the spine have been associated with lumbar radiculopathy (nerve root disease) in several cases, causing nerve root compression and narrowing of the spinal canal and lateral thecal sac. Arthrotic dysfunction leading to degenerative spondylolisthesis (misalignment of vertebra) has been seen in 40% of patients. Most patients are in their sixth decade of life, with a male:female ratio of 2:1 to 1:1. 

Clinical findings include low back pain (LBP), radiculopathy and neurogenic claudication (absence of pain when at rest). Neurodiagnostic signs indicate the location of the cysts and degree of  lumbar stenosis. These are usually found in decreasing order of frequency at the L4-L5, L5-S1, L3-L4, and L2-L3 levels. 

Based on clinical manifestations and neurological examinations in advanced cases or those refractory to conservative (non-invasive) treatment surgical intervention is indicated consisting of varying decompression procedures and excision with or without primary fusion. 

Patient Information

  • Synovial cysts are fluid-containing, sac-like structures that protrude through a defect or torn part of degenerated facet joints. The wall of synovial cysts, consisting of cuboidal or pseudostratified columnar epithelial cells, becomes calcified in the diseased state.
  • For some known or yet unknown reason synovial cysts can develop in any synovial joint in the body - spine, hip joint, tendon sheath, and bursae, causing cramps in the back and legs, depending upon their location.
  • Although usually benign synovial cysts can mimic or accompany other spinal or neurological diseases necessitating medical intervention.
  • Conservative or non-invasive procedures are initially prescribed for treatment of early symptomatic cases. Otherwise, surgery by decompression and excision, with or without fusion is indicated in advanced cases or those who are not responding to conventional treatment, to alleviate the symptoms and/or prevent complications.
  • Synovial cysts of the spine have been associated with low back pain and lumbar radiculopathy (disease of the nerve roots) in many  cases. Pain usually occurs at night or when in recumbent position and among the elderly (in their sixth decade of life).
  • The hip joint synovial cyst is associated with chronic inflammation of the hip joint.
  • Synovial cysts of the knee have varied causes, including irritated and inflamed bursae and other less common conditions. 
  • Bursal cysts due to trauma may be treated with nonsteroidal anti-inflammatory medication, rest, and immobilization of the affected limb..
  • Ganglion and synovial cysts are linked to soft tissue lesions in the ankle and foot region.
  • Paralabral cyst causes anterior hip pain, impaired  rotatory movement and snapping sensation.
  • Baker's cysts are often detected only when the knee is undergoing neuroimaging for other medical ailments.
  • Long-term follow-up is advised in any case to assess the result of treatment.



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Last updated: 2018-06-22 12:18