Indian Journal of Radiology Indian Journal of Radiology  

   Login   | Users online: 1456

Home Bookmark this page Print this page Email this page Small font sizeDefault font size Increase font size     

 

MUSCULOSKELETAL Table of Contents   
Year : 2010  |  Volume : 20  |  Issue : 3  |  Page : 208-210
Case Series: Cyclops lesion - extension loss after ACL reconstruction


Department of Diagnostic and Interventional Radiology, Kokilaben Dhirubhai Ambani Hospital and Research Centre, Mumbai, India

Click here for correspondence address and email

Date of Web Publication14-Sep-2010
 

   Abstract 

Localized anterior arthrofibrosis (cyclops lesion) is the second most common cause of extension loss after anterior cruciate ligament (ACL) reconstruction. We present and discuss two patients with prior ACL reconstructions, who presented with pain and loss of extension following surgery. MRI and arthroscopy of the knee revealed typical features of a cyclops lesion. The patients showed significant symptomatic improvement following arthroscopic resection of these lesions.

Keywords: Anterior cruciate ligament; cyclops lesion; localized anterior arthrofibrosis; MRI

How to cite this article:
Dhanda S, Sanghvi D, Pardiwala D. Case Series: Cyclops lesion - extension loss after ACL reconstruction. Indian J Radiol Imaging 2010;20:208-10

How to cite this URL:
Dhanda S, Sanghvi D, Pardiwala D. Case Series: Cyclops lesion - extension loss after ACL reconstruction. Indian J Radiol Imaging [serial online] 2010 [cited 2018 Aug 19];20:208-10. Available from: http://www.ijri.org/text.asp?2010/20/3/208/69361

   Introduction Top


Cyclops lesion or localized anterior arthrofibrosis, an arthroscopically treatable complication of anterior cruciate ligament (ACL) reconstruction, is a fibrous nodule located in the intercondylar notch anterior to the ACL graft. [1] The lesion has a typical MRI and arthroscopic appearance. We describe MRI features of the cyclops lesions in two patients who presented with restriction of motion following ACL reconstruction.


   Case Reports Top


Case 1

An 18-year-old boy had undergone left ACL reconstruction 8 months back. He presented with pain and stiffness of the left knee for the last 6 months. MRI [[Figure 1]A-C] was performed to diagnose the cause of stiffness and also to evaluate meniscal and chondral integrity, tunnel size and position. A soft tissue nodule was seen in the intercondylar notch anterior to and attached to the reconstructed ACL. The nodule appeared hypointense on T1W and isointense to muscle on T2W and proton density-weighted (PDW) images. The tunnel position and size were adequate. Both the menisci appeared normal in shape, configuration and signal intensity. The cartilage lining the tibial, femoral and patellar articular surfaces appeared normal in thickness and signal intensity. On arthroscopy, the nodule had a head-like appearance with a focal area of discoloration resembling an eye [[Figure 1]D]. In view of the typical clinical, radiological and arthroscopic features, the diagnosis of a cyclops lesion was made. The lesion was treated with arthroscopic excision. Histopathology examination of the specimen showed fibrocartilagenous tissue. Follow-up after 1 month showed full extension of the knee joint.
Figure 1 :(A-D) Case 1: Fat-suppressed sagittal proton-density weighted (A) and T2W (B) MRI images show an anterior cruciate ligament (ACL) graft (arrow) with a hypointense nodule (arrowhead) attached to its anterior surface in the intercondylar notch. Sagittal T1W MRI image (C) shows the hypointense nodule (arrow) to be indistinguishable from the synovial fluid. Arthroscopic image (D) shows the cyclops lesion (arrowheads) attached to the ACL (arrow) with a head-like appearance, showing a focal area of discoloration resembling an eye (curved arrow)

Click here to view


Case 2

A 52-year-old man presented with pain and extension loss of the left knee for 3 months after ACL reconstruction surgery performed 6 months back. MRI [[Figure 2] A-C] revealed a soft tissue nodule in the anterior intercondylar notch contiguous with and attached to the reconstructed ACL. The nodule appeared hypointense on T1W and isointense to hypointense on T2W and PDW images. The lesion had a bulbous head-like appearance with a characteristic focal area of reddish-blue discoloration on arthroscopy. These clinical, radiological and arthroscopic features favored the diagnosis of a cyclops lesion. The nodule was arthroscopically excised and routine post-operative mobilization was prescribed. On histopathology, the nodule showed central granulation tissue surrounded by dense fibrous tissue. Significant improvement in the range of extension was noted during the post-operative period.
Figure 2 :(A-C) Case 2: Fat-suppressed sagittal proton-density weighted (A) and T2W (B) MRI images show a hypointense to isointense nodule (arrowhead) attached to the anterior surface of the anterior cruciate ligament (ACL) graft (arrow). Sagittal T1W MRI image (C) shows a hypointense nodule (arrowhead) in the anterior intercondylar notch

Click here to view



   Discussion Top


MRI is the primary post-operative investigative tool in patients with failed ACL reconstruction and is used to evaluate complications, the cause of graft failure, post-operative re-injury and pre-operative planning for repeat surgery. Important complications of ACL reconstruction include graft instability, disruption, extension loss, hardware failure (screw displacement and bone plug dislodgment) and patellar fracture (unique to the use of the patellar tendon autograft). [1]

Loss of motion, particularly loss of knee extension, is a frequent cause of morbidity in patients with prior ACL reconstructions. Localized anterior arthrofibrosis, also called the cyclops lesion, is the second most common cause of extension loss after ACL reconstruction, with a frequency of 1-9.8%, the most common being graft impingement, which develops due to anterior placement of the tibial tunnel. [2] Other less-frequent causes of loss of extension include suprapatellar or intercondylar adhesions, fibrosis of the fat pad, entrapment of the patella and capsular contracture. [2] The pathogenesis of the cyclops lesion is multifactorial; it may be due to debris raised during drilling of the tibial tunnel or impingement of the exposed fibers of the ACL on the intercondylar notch. [2],[3],[4]

On histopathology, the lesion consists of central granulation tissue surrounded by dense fibrous tissue. [4] The cyclops lesion has been shown to evolve from an early stage showing fibrosis to a late stage showing fibrocartilaginous soft tissue. Fibrous tissue, fibrocartilage, bone, synovium and fat from the infrapatellar fat pad may all contribute towards the formation of the cyclops lesions. [5]

The nodule is located in the intercondylar notch anterior to the ACL graft. It may be attached to the graft fibers via a pedicle. The nodule gets pinched between the tibia and femur, which then causes a mechanical block to terminal extension. On MRI, the lesion has signal characteristics consistent with fibrous tissue. On T1W images, it may be indistinguishable from the adjacent joint fluid due to its low signal intensity. However, on T2W images, it has a heterogenous low signal intensity, enabling clear differentiation from high signal intensity joint fluid. On MRI arthrography, it can be outlined against the intra-articular contrast. [3] On arthroscopy, the lesion has a head-like appearance with a focal area of reddish-blue discoloration due to venous channels that resemble an eye. Hence, it is called the "cyclops lesion." The lesion is removed arthroscopically with additional notchoplasty if necessary. [2],[3],[6] Aggressive physical therapy does not improve extension loss associated with cyclops lesions. [7],[8]

The cyclops syndrome was first described by Jackson and Schaefer in patients with ACL reconstruction as a condition presenting with loss of full extension, with development of an audible and palpable "clunk" in terminal extension. [6]The cyclops syndrome has also recently been reported in patients with ACL injury without a history of reconstructive surgery. [6] Additionally, cyclops nodules have also been described in post-trauma patients with a clinically or radiologically intact ACL, probably a reaction to microtrauma leading to subclinically torn ACL fibers. [6]

In conclusion, it is important to recognize a cyclops nodule as a possible cause of extension loss in any patient with ACL injury because it is readily amenable to arthroscopic resection and good patient outcome.

 
   References Top

1.Recht MP, Kramer J. MR Imaging of the postoperative Knee: A pictorial essay. Radiographics 2002;22:765-74.  Back to cited text no. 1  [PUBMED]  [FULLTEXT]  
2.Recht MP, Piraino DW, Cohen MA, Parker RD, Bergfeld JA. Localized anterior arthrofibrosis (cyclops lesion) after reconstruction of the anterior cruciate ligament: MR imaging findings. AJR Am J Roentgenol 1995;165:383-5.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]  
3.Recht MP, Piraino DW, Applegate G, Richmond BJ, Yu J, Parker RD, et al. Complications after anterior cruciate ligament reconstruction: Radiographic and MR findings. AJR Am J Roentgenol 1996;167:705-10.   Back to cited text no. 3  [PUBMED]  [FULLTEXT]  
4.Sheldon PJ, Forrester DM, Learch TJ. Imaging of intra-articular masses. Radiographics 2005;25:105-19.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]  
5.Bradley DM, Bergman AG, Dillingham MF. MR Imaging of cyclops lesions. AJR Am J Roentgenol 2000;174:719-26.  Back to cited text no. 5      
6.Runyan BR, Bancroft LW, Peterson JJ, Kransdorf MJ, Berquist TH, Ortiguera CJ. Cyclops lesions that occur in the absence of prior anterior ligament reconstruction. Radiographics 2007;27:e26.  Back to cited text no. 6  [PUBMED]  [FULLTEXT]  
7.Shelbourne KD, Johnson GE. Outpatient surgical management of arthrofibrosis after anterior cruclate ligament surgery. Am J Sports Med 1994;22:192-7.   Back to cited text no. 7  [PUBMED]    
8.Dodds JA, Keene JS, Graf BK, Lange RH. Results of knee manipulations after anterior cruciate ligament reconstructions. Am J Sports Med 1991;19:283-7.  Back to cited text no. 8  [PUBMED]    

Top
Correspondence Address:
Sunita Dhanda
512-F Karan, Versova, Andheri (West), Mumbai - 400 061
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-3026.69361

Rights and Permissions


    Figures

  [Figure 1], [Figure 2]

This article has been cited by
1 Anterior cruciate ligament reconstruction: Magnetic resonance imaging and factors influencing outcome
Galal, A., Abdul-Maksoud, S., Al-Kandary, S., Abdul-Salam, S., Awad, A.
Egyptian Journal of Radiology and Nuclear Medicine. 2011; 42(2): 193-200
[Pubmed]
2 Anterior cruciate ligament reconstruction: Magnetic resonance imaging and factors influencing outcome
Amr Galal,Safia Abdul-Maksoud,Salwa Al-Kandary,Samir Abdul-Salam,Atef Awad
The Egyptian Journal of Radiology and Nuclear Medicine. 2011; 42(2): 193
[Pubmed] | [DOI]



 

Top
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Email Alert *
    Add to My List *
* Registration required (free)  


    Abstract
    Introduction
    Case Reports
    Discussion
    References
    Article Figures

 Article Access Statistics
    Viewed7428    
    Printed255    
    Emailed4    
    PDF Downloaded355    
    Comments [Add]    
    Cited by others 2    

Recommend this journal