Ganglion cyst of the anterior cruciateligament: A case report

B Dinakar, T Khan, AC Kumar, A KumarFujairah Hospital, Fujairah, UAE

CASE REPORT

A 16-year-old man presented to Fujairah Hospital inMarch 2004 with pain in his right knee joint for theprevious 8 months. He was serving in the military andengaged in regular heavy physical activity. He hadmildly twisted his right knee joint one year earlier andhad been treated with anti-inflammatory medications.He recovered well and continued with his regularactivities.

On presentation, the patient had difficultybending his right knee. He had no history of lockingor giving way of the knee, but had pain on standing.On clinical examination, there was mild wasting of thequadriceps muscle, some swelling of the right kneejoint, and local tenderness over the medial joint line.The range of movement of his knee was full, with noloss of extension, but the terminal knee flexion (thefinal 10 to 15 degrees) was painful. McMurray’s testwas negative, and the collateral and cruciate ligamentswere clinically stable. The patellar articular surface wasnot tender, and patellar movements were normal. The

Address correspondence and reprint requests to: Dr B Dinakar, Specialist Orthopaedic Surgeon, P.O. Box 10, Fujairah Hospital,Fujairah, UAE. E-mail: begurdinakar@yahoo.com

ABSTRACT

A ganglion is a cystic swelling that usually arisesclose to tendons or joints. Its occurrence inside a jointis rare, and its diagnosis is usually incidental duringmagnetic resonance imaging or arthroscopy. It maybe painful or asymptomatic. Some patients mayhave a trauma history. Ganglia may mimic intra-articular lesions like tears of the anterior cruciateligament or meniscus. Magnetic resonance imagingis the investigation of choice for diagnosis. Gangliacommonly arise from the anterior cruciate ligament,but can also arise from other structures such as theposterior cruciate ligament or meniscus. Gangliaare typically treated by arthroscopic excision anddebridement. We report a case of ganglion cyst ofthe anterior cruciate ligament in a 16-year-old man.

Key words: anterior cruciate ligament; arthroscopy; ganglion cysts

Journal of Orthopaedic Surgery 2005:13(2):181-185

182 B Dinakar et al. Journal of Orthopaedic Surgery

cause of his pain was presumed to be due to internalderangement of the knee, probably caused by a mildmeniscal injury.

Magnetic resonance imaging (MRI) of the rightknee showed a moderate amount of loculated fluidin the intercondylar fossa, with septations. Theradiologist interpreted the MRI as a cyst involving theposterior horn of the medial meniscus. The swellingextended in front of the anterior cruciate ligament(ACL), in between the ACL and the posterior cruciateligament (PCL), and further extended posterior to thePCL (Fig 1).

The patient underwent arthroscopy of his rightknee joint under general anaesthesia through thestandard anteromedial and anterolateral portals. Theposterior portal was once considered an option whileplanning the procedure. As we were able to visualisethe swelling clearly and were also able to excise a majorpart of it through the anterior portals, a furtherposterior approach was not considered.

During the procedure, the cyst was visualised well;it was located in front of the ACL and partially within

the ACL close to the femoral attachment. It was ovoidin shape measuring about 15 mm in diameter. The cystwas well demarcated and its origin from the ACL wasclearly visualised (Fig. 2). It was transparent andfreely mobile. There were no adhesions or signs ofinflammation surrounding the swelling. The cyst wasthin-walled and easily punctured by the probe. Thewall of the cyst lying posterior to the PCL was brokenby the probe, and approximately three quarters of thecyst and its wall were excised.

A diagnosis of a cyst arising from the ACL wasmade. The medial and lateral menisci were normal.Transparent gelatinous fluid came out of the cyst whenit was punctured. The major portion of the cyst wallwas resected using the arthroscopy resector. The areaaround the ACL was probed, and all the septa werebroken. The knee was then put through a full range ofmotion. All other structures within the knee jointwere found to be normal.

The cyst wall was sent for histopathologicalexamination. The postoperative course wasuneventful. The patient was mobilised in hospital

Figure 1 Magnetic resonance images of the knee showing (a) the extension of the cyst, (b) the posterior cruciate ligament inbetween, and (c) the cyst in the intercondylar fossa.

(a) (b) (c)

Figure 2 Arthroscopic photographs of the knee showing the cyst (a) in front of, (b) arising from, and (c) beside the anteriorcruciate ligament.

(a) (b) (c)

Cyst

ACL

Cyst

ACL

Cyst

ACL

Vol. 13 No. 2, August 2005 Ganglion cyst of the anterior cruciate ligament 183

and discharged home the next day. The histopathologyreport showed greyish-white membranous bitsmeasuring 1.3x0.6x0.3 cm. Microscopic sectionsshowed lobulated fibro-fatty tissue coveredsuperficially by flattened synovial cells. A confluentarea of fibrinoid/hyaline change of the stromawas observed, as well as a moderate infiltration bymononuclear leukocytes. Multinucleated giantcells were not seen. All these features weresuggestive of a ganglion cyst.

The patient was followed up in an orthopaedicout-patient regularly. At the final follow-up ofpostoperative 6 months, the patient did not have anycomplaints and the follow-up MRI showed nosigns of any residual cyst (Fig. 3).

Clinical features

Intra-articular swellings such as ganglion cystsmay present with pain and/or limitation of themovements of the joint. These may be due tomechanical blocking effects. Some patients presentwith a clicking sensation and interference duringextreme flexion and extension movement. Cystsanterior to ACL tend to limit extension, whereasthose posterior to the PCL tend to limit flexion. Theremaybe joint line tenderness and retropatellar pain.Ganglion cysts may present as palpable massesaround the knee joint. Symptoms may grow worsewith activity, especially running, jumping, orsquatting. The duration of symptoms may last froma few weeks to as long as 5 years. The symptoms arenon-specific, and investigations are needed to

diagnose the lesion, which usually be foundincidentally during MRI or arthroscopy.

Ganglion cysts are differentiated from pigmentedvillo-nodular synovitis, fibroma, haemangioma,synovial sarcoma, synovial proliferation, myxoma,synovial chondromatosis, aneurysm, and intra-articular lipoma.1

Investigations

MRI and arthroscopy are the usual tools for diagnosingACL cysts. MRI is the most sensitive, specific, accurate,and non-invasive method for diagnosing theselesions. It can also detect other intra-articular lesions.The ganglion cysts are usually ovoid and wellcircumscribed on MRI. They have homogeneouslylow signal intensity on T1-weighted images and highsignal intensity on T2-weighted images. They canextend towards the joint line and around the knee joint.MRI is also useful in detecting any associated internalderangement of the knee, such as ACL or meniscaltears. Other diagnostic modalities such as ultrasound,computed tomography (CT), and arthrography havealso been used.

Treatment

Asymptomatic cysts need to be treated and excised;otherwise , they may become symptomaticlater. Arthroscopic resection, debridement, andexcision are the treatments of choice for ganglioncysts. Other treatment methods include ultrasound-,CT-, and arthroscopic-guided needle aspiration, butthese are usually associated with a higher rate ofrecurrence.

DISCUSSION

Caan first described the ACL ganglion cyst during aroutine autopsy in 1924. In the early 1990s, only a fewsporadic cases and one main case report were foundin the literature.2–12 With widespread use of MRI andarthroscopy in daily practice, an increasing numberof cases have been discovered.

Ganglion is a cystic swelling that usuallyarises close to the tendons or joints. Most often it isencountered over the dorsum of the hand, but it canoccur in any part of the body. Its occurrence inside ajoint is very rare. The incidence of finding intra-articular cystic masses is 1.3% by MRI and 0.6% duringarthroscopy. They may be single or multiple,13 as wellas unilateral or bilateral.14 The cysts could be gangliaor synovial cysts. The term ganglion cyst is used to

Figure 3 Magnetic resonance image of the knee 3 monthsafter surgery showing no evidence of the cyst

184 B Dinakar et al. Journal of Orthopaedic Surgery

include both lesions. The common site for cystic lesionsinside the knee joint is the ACL, followed by PCL, thenmenisci, especially the medial meniscus. Other raresites of occurrence are at the infrapatellar fat pad,medial plica, from a subchondral cyst, popliteustendon, from chondral fractures or subchondral bonecysts. They may arise from alar folds that cover eitherthe infrapatellar fat pad15 or the cruciate ligaments.The cysts of the cruciate ligaments can distendoutside along the fibres (anterior to the ACL andposterior to the PCL), between the 2 cruciateligaments (intercruciate distension—as in our case),or interspersing within the fibres. Nearly two thirdsof all ganglion cysts originate from the ACL. Theyusually arise from tibial insertion. In our case, it wasfrom the substance of the ACL close to the femoralattachment. Meniscal cysts arise both from anteriorand posterior horns. Cystic lesions posterior to PCLrequire additional portals such as posteromedial andposterolateral portals for access during arthroscopy.Intra-ligamentous ganglion cysts are detectable byintra-fibrous probing during surgery, which yields anoutflow of whitish or yellowish gelatinous material.The shape of ganglion cysts could be fusiform, spindle-shaped, rounded, ovoid, and well-demarcated outlineswith a normal size of 5 to 30 mm, rarely up to 40 mmin diameter. They appear uni- or multi-locular and areusually found alone in each knee.16

The cause of ganglion cyst may be due to synovialtissue herniation, connective tissue degeneration aftertrauma, mucin deterioration of connective tissue,ectopia of synovial tissue, or proliferation ofpluripotential mesenchymal stem cells. Patients mayhave a history of knee trauma.

The clinical features may suggest internalderangement of the knee. Pain is the most commonsymptom. There are often fusiform swellings on MRIexamination. Intra-articular ganglion cysts can besymptomatic or asymptomatic. Krudwig et al.16

reported 85 cases of intra-articular ganglion cysts, ofwhich 9 were symptomatic and 76 were asymptomatic.All the 9 symptomatic patients had no history oftrauma. The definite history of trauma in our patientis a significant finding. The possible aetiology may beconnective tissue degeneration or re-activation of

dormant ectopic synovial tissue in the joint followingthe trauma.

Brown and Dandy3 found that 95% of their patientshad good or excellent results after arthroscopic excisionof ganglionic cysts. No recurrence after arthroscopicexcision was reported. Intra-articular ganglia of theknee have also been reported to be successfully treatedwith CT-guided aspiration. Nokes et al.17 aspirated 2ganglion cysts of the PCL of the knee with an 18-gaugeneedle and syringe holder, using CT guidance to avoidthe popliteal vessels. Thick straw-coloured gelatinousmaterial was aspirated. Both patients had relief of painand had no recurrence of the ganglia 2 years aftersurgery. Recurrence is unlikely if the ganglion cyst istreated by excision during arthroscopy.18

CONCLUSION

Diagnosis of intra-articular ganglion cysts should beconsidered in cases of internal derangement of theknee. Trauma can incite changes in ectopic dormantsynovial tissue and lead to cyst formation. Theseintra-articular ganglion cysts can mimic meniscaltears. Elderly patients may present with pain andtenderness over the joint line, suggestive of intra-articular degenerative lesion. Clinical diagnosis ofsuch cases may be difficult because of their rareoccurrence. MRI is helpful in diagnosis and depictingthe size and location of the cyst. Arthroscopicresection is the treatment of choice. Slight damage tothe wal l may resul t in wal l co l lapse anddisappearance of the cyst. All the septa should beruptured to prevent possible recurrence. Recurrenceis very rare following complete resection but canoccur after aspiration.

ACKNOWLEDGEMENTS

We wish to thank Dr Kavya Dinakar for her assistancein preparing this manuscript, Dr Mohammed Haroonfor interpreting the MRI, Mr Shakeeb Mohammed forpreparing the pictures, and Dr Issac Olude forinterpreting the histopathological slides.

REFERENCES

1. Marui T, Yamamoto T, Kimura T, Akisue T, Nagira K, Nakatani T, et al. A true intra-articular lipoma of the knee in a girl.Arthroscopy 2002;18:E24.

2. Bromley JW, Cohen P. Ganglion of the posterior cruciate ligament: report of a case. J Bone Joint Surg Am 1965;47:1247–9.3. Brown MF, Dandy DJ. Intra-articular ganglia in the knee. Arthroscopy 1990;6:322–3.

Vol. 13 No. 2, August 2005 Ganglion cyst of the anterior cruciate ligament 185

4. Calvisi V, Collodel M, Romanini L. Synovial ganglia of the central pivot of the knee. Ital J Orthop Traumatol 1991;17:305–11.

5. Chang W, Rose DJ. Ganglion cysts of the anterior cruciate ligament. A case report. Bull Hosp Jt Dis Orthop Inst 1988;48:182–6.

6. Garcia A, Hodler J, Vaughn L, Haghighi P, Resnick D. Case report 677. Intraarticular ganglion arising from the posteriorcruciate ligament. Skeletal Radiol 1991;20:373–5.

7. Kaempffe F, D’Amato C. An unusual intra-articular ganglion of the knee with interosseous extension. A case report. J BoneJoint Surg Am 1989;71:773–5.

8. Lee KR, Cox GG, Neff JR, Arnett GR, Murphey MD. Cystic masses of the knee: arthrographic and CT evaluation. Am JRoentgenol 1987;148:329–34.

9. McLaren DB, Buckwalter KA, Vahey TN. The prevalence and significance of cyst-like changes at the cruciate ligamentattachments in the knee. Skeletal Radiol 1992;21:365–9.

10. Muckle DS, Monahan P. Intra-articular ganglion of the knee: report of two cases. J Bone Joint Surg Br 1972;54:520–1.11. Passler J, Hofer HP, Fellinger M, Peicha G. Intraarticular meniscal cysts of the knee. Report of two cases. Int Orthop 1991;

15:357–8.12. Sundaram M, McGuire MH, Fletcher J, Wolverson MK, Heiberg E, Shields JB. Magnetic resonance imaging of lesions of

synovial origin. Skeletal Radiol 1986;15:110–6.13. Wang CJ. Multiple ganglion cysts of the knee. Arthroscopy 2002;18:E42.14. Noda M, Kurosaka M, Maeno K, Mizuno K. Case report ganglion cysts of the bilateral cruciate ligaments. Arthroscopy 1999;

15:867–70.15. Kang CN, Kim DW, Kim Dj, Kim SJ. Intra-articular ganglion cysts of the knee. Arthroscopy 1999;15:373–8.16. Krudwig WK, Schulte KK, Heinemann C. Intra-articular ganglion cysts of the knee joint: a report of 85 cases and review of

the literature. Knee Surg Sports Traumatol Arthrosc 2004;12:123–9.17. Nokes SR, Koonce TW, Montanez J. Ganglion cysts of the cruciate ligaments of the knee: recognition on MR images and CT-

guided aspiration. Am J Roentgenol 1994;162:1503.18. Bui-Mansfield LT, Youngberg RA. Intraarticular ganglia of the knee: prevalence, presentation, etiology, and management.

Am J Roentgenol 1997;168:123–7.