|Year : 2017 | Volume
| Issue : 2 | Page : 128-132
Magnetic resonance imaging evaluation of cruciate ligaments after arthroscopic reconstruction
Amit Kharat, Sahil Garg, Vipul Sehrawat, SG Gandage
Department of Radiodiagnosis, Dr. D.Y. Patil Medical College, Hospital and Research Centre, Dr. D.Y. Patil Vidyapeeth, Pune, Maharashtra, India
|Date of Web Publication||14-Mar-2017|
H. NO. 1320, Sector-12, Huda, Panipat - 132 103, Haryana
Source of Support: None, Conflict of Interest: None
Background: Due to increase in road traffic and sports injuries, tears of anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) of the knee are common. Magnetic resonance imaging (MRI) is emerging as an important tool of diagnosis and evaluation of these injuries. Methods: We carried out a prospective study on role of MRI on ten patients who had undergone ACL or PCL repair over a period of six months. In this report we present three illustrative cases to capture the spectrum of findings in our series to underline the role of MRI in management of such injuries and discuss the modalities of the procedure. Results: In our series, as demonstrated by the cases, MRI had an important role in diagnosis and evaluation of injuries to the cruciate ligaments. Conclusion: MRI can play an important role, particularly in tertiary centres, in diagnosis and evaluation of reconstructed ACL and PCL ligaments of the knee joint.
Keywords: Anterior cruciate ligament, arthroscopy, cyclops lesion, femoral and tibial tunnel, graft, magnetic resonance imaging, posterior cruciate ligament
|How to cite this article:|
Kharat A, Garg S, Sehrawat V, Gandage S G. Magnetic resonance imaging evaluation of cruciate ligaments after arthroscopic reconstruction. Med J DY Patil Univ 2017;10:128-32
|How to cite this URL:|
Kharat A, Garg S, Sehrawat V, Gandage S G. Magnetic resonance imaging evaluation of cruciate ligaments after arthroscopic reconstruction. Med J DY Patil Univ [serial online] 2017 [cited 2017 May 26];10:128-32. Available from: http://www.mjdrdypu.org/text.asp?2017/10/2/128/202116
| Introduction|| |
Traditionally, radiography was the primary diagnostic modality for knee injuries, but they were only able to diagnose joint space narrowing, alignment of the knee, and major trauma with very limited information about ligaments injuries. Over the past 15 years, magnetic resonance imaging (MRI) has emerged as a primary imaging tool in the assessment of knee pain primarily in suspected cases of meniscal and ligament injuries as well as plays an equally important role in postoperative reconstruction cases to assess the success of the procedure. Arthroscopic reconstruction of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) is the modality of choice for high-grade tears. However, may present with various complications and persistent morbidity due to knee pain even after the treatment. We hereby review complications of reconstructed ACL and PCL with the help of MRI and its role as a diagnostic modality of choice.
| Materials and Methods|| |
A prospective study was carried out on ten patients in the Department of Radio-diagnosis, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Pimpri, Pune over a period of 6 months. Patients from all age groups including both men and women who had undergone postoperative ACL or PCL repair and who have undergone arthroscopy for ACL/PCL pathologies were included. No contrast media was used in ours. Clearance from the ethical committee was taken.
MRI was performed with SIEMENS 1.5 Tesla MAGNETOM AVANTO Machine. The size of bore was 60 cm, and overall length of the system was 160 cm. The MRI system used zero helium boil-off technology. An eight-channel knee coil was used. The coil had eight integrated preamplifiers and was iPAT compatible.
MRI examination of the knee was performed in axial, coronal, and sagittal planes. Patients were positioned in supine position with the knee placed in 10–15° of external rotation. An axial acquisition, through patellofemoral joint, was used as an initial localizer for subsequent sagittal and coronal plane images. Axial images were obtained from distal quadriceps tendon to insertion of patellar tendon on tibial tuberosity. Sagittal images were obtained from medial to lateral femoral condyles, and coronal images were obtained with line parallel to femoral condyles.
| Results|| |
A 25-year-old male patient had a history of reconstruction of complete ACL tear 2 months back. Preoperative MRI PDfs and T2-weighted imaging (T2-WI) showed nonvisualization of ACL at its femoral attachment and PCL buckling suggestive of high-grade tear of ACL [Figure 1].
|Figure 1: Left knee magnetic resonance imaging sagittal sequence (right) and T2-weighted imaging sagittal sequence (left) showing nonvisualization of anterior cruciate ligament at its femoral attachment and posterior cruciate ligament buckling suggestive of high-grade tear of anterior cruciate ligament|
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The same patient went arthroscopic treatment and bone patella tendon bone graft was used. MRI T2-WI showed the normal femoral tunnel, the normal hypointense ACL graft, and the normal tibial tunnel [Figure 2].
|Figure 2: Left knee magnetic resonance imaging T2 sagittal sequence showing the normal femoral tunnel (above left), the normal hypointense anterior cruciate ligament graft (above right), and the normal tibial tunnel (below)|
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A 28-year-old male patient underwent ACL reconstruction 6 months back and presented with recurrent pain and inability to move the knee. On MRI T2-WI and MRI Sagittal PDfs, ACL flap is visualized in distal part of tibia, however, it is not visualized in femoral tunnel. Collection was noted around the tibial tunnel. These findings were suggestive of a complete tear of reconstructed ACL [Figure 3].
|Figure 3: Magnetic resonance imaging T2-weighted imaging (right) and magnetic resonance imaging sagittal PDfs (left) showing nonvisualization of anterior cruciate ligament flap in femoral tunnel with collection was noted around the tibial tunnel. These findings were suggestive of complete tear of reconstructed anterior cruciate ligament|
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A 37-year-old male patient came with complaints of difficulty in extension of the knee with pain in the knee after ACL reconstruction 5 months back. MRI was performed for routine ACL graft integrity. Tibial and femoral tunnels containing the ACL graft was noted. The tibial tunnel was parallel to Blumensaat's line. The femoral tunnel was at its normal 11 o'clock position on coronal images. There was no evidence of marrow edema along the tibial tunnels or cysts within. A tiny nodular lesion was seen in the intercondylar notch anterior to ACL measuring approximately 0.9 cm in transverse dimension and appearing iso to hyperintense on T2-WI and PDfs. This was indicative of arthrofibrosis/cyclops lesion [Figure 4].
|Figure 4: Magnetic resonance imaging T2-weighted imaging (right) and PDfs (left) postoperative reconstruction anterior cruciate ligament knee (5 months after the surgery) showing a tiny nodular lesion (blue arrow) in the inter-condylar notch anterior to anterior cruciate ligament graft indicative of arthrofibrosis/cyclops lesion|
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| Discussion|| |
The two primary ACL reconstruction procedures are the autologous bone – patella tendon – bone graft and the autologous four-strand hamstring graft, which is also known as the doubled semitendinosus and gracilis tendon graft. The bone – patella tendon – bone graft is harvested by taking bone blocks from the patella and the tibial tubercle with the intervening central third of the patellar tendon. The second graft is composed of the distal semitendinosus and gracilis tendons, which are harvested from the musculotendinous junction to their tibial insertion. They are then sutured together and doubled back, giving four-strands.
The most important part of the process is the imaging of the positioning and imaging of the femoral and tibial tunnel. The positioning of the femoral tunnel is the primary factor in maintaining graft isometry. Femoral tunnel positioning must be assessed in both the sagittal and coronal planes. The position of the tunnel can be assessed in the sagittal plane by drawing a line along the posterior cortex of the femur and another line along the roof of the intercondylar notch. The inferior portion of the tunnel should be located at the intersection of these two lines.
The positioning of the tibial tunnel is the primary factor in preventing impingement of the graft against the roof of the intercondylar notch. On sagittal images, the tibial tunnel should be oriented parallel to the Blumensaat line (Blumensaat line is a line drawn on conventional radiographs along the intercondylar roof). The distal portion of the tunnel should start near the tibial tuberosity, and the intraarticular opening of the tunnel should be completely posterior to where the Blumensaat line, or the Blumensaat line equivalent on MRI, intersects the tibia.
A normal ACL graft should have low signal intensity on short-TE sequences. Intermediate signal is often seen within grafts from approximately 4–8 months after reconstruction, decreasing with time and usually completely resolving by 12 months the increased signal is thought to be due to graft revascularization and synovialization.
An important distinction between the doubled semitendinosus and gracilis tendon graft and the bone – patella tendon – bone graft should be considered. Because the doubled semitendinosus and gracilis tendon graft is composed of four separate strands, intermediate signal, and even fluid signal can normally be seen between the strands of the graft on T2-weighted sequences. This finding is abnormal for a bone – patella tendon – bone graft, which is composed of a single strand. This normal intermediate or high signal is always oriented along the fibers of a doubled semitendinosus and gracilis tendon graft and is distinguishable from a tear, which is perpendicular to the graft.,
MRI is seldom used for evaluating PCL grafts as repair of the injured PCL is performed much less commonly than that of the ACL. Almost half of all PCL injuries are partial tears that typically heal with conservative treatment. Similar grafts are used like ACL reconstruction, i.e., bone – patella tendon – bone graft and doubled semitendinosus and gracilis tendon graft. Intact PCL graft has magnetic resonance (MR) findings analogous to those of the reconstructed ACL. Normal grafts have uniformly low signal intensity at T1- and T2-WI, as seen with the normal native PCL. Similar revascularization phenomenon occur in the PCL graft like ACL grafts, and most grafts have mild to moderate intrasubstance signal intensity at T1- and T2-WI during the 1st postoperative year. After 1 year PCL graft gradually resumes its low signal intensity on T1- and T2-WI.,
There are certain complications included with imaging of ACL and PCL reconstruction. Complications after ACL reconstruction can be divided into two groups on the basis of clinical symptoms: decreased motion and laxity. The main complications found in patients with decreased range of motion are impingement and arthrofibrosis (focal and diffuse forms). Less common causes of decreased range of motion include intraarticular bodies and ganglion cysts. The main complications in patients with increased laxity are graft disruption and graft stretching.
Arthrofibrosis also known as cyclops lesion can be diffuse or focal and limits complete extension of the knee because the graft is trapped between the femur and tibia and presents after 4–6 months of ACL reconstruction on MRI, both forms present as low signal intensity on T1-weighted sequences and are predominantly low signal on T2-weighted sequence.,
Tibial tunnel positioning is the primary factor affecting impingement. Both the femoral and tibial tunnels are most commonly malpositioned too far anteriorly and results in persistent pain. On MRI, there is malpositioned tunnel with increased signal on T2 and T1 in the graft in cases of notch impingement. Signal changes from notch impingement will persist after 1 year as compared to signal changes due to revascularization.
Intraarticular bodies may be secondary to postoperative ACL reconstruction or secondary to an associated chondral injury that occurred during the initial trauma, but that were not noticed at the time of ACL reconstruction. Signal intensity varies on MRI as it can be composed of articular cartilage, cortical bone, or cancellous bone but will be intermediate to low signal on T2-WI images. Cystic degeneration of the graft occurs within the tibial tunnel within the graft and follows fluid signal on all pulse sequences. Ganglion cysts may cause pain and if large enough, may limit motion, but they have not been shown to be a primary cause of graft failure.
Imaging complication associated with laxity usually includes graft tear and graft stretching. Graft tear usually occurs approximately 4–8 months after surgery as they are most susceptible during remodeling process. Primary signs of graft tear include graft signal abnormalities, namely, increased signal on T2-weighted sequences, graft thickness, and fiber discontinuity. Secondary signs of graft tear include anterior tibial translation and an uncovered posterior horn of the lateral meniscus.
Femoral tunnel and tibial tunnel may be malpositioned and placed too anteriorly. If the femoral tunnel is placed too anteriorly, then the graft is subjected to strain when the knee is flexed and can lead to graft tightening or stretching. MRI findings may include posterior bowing of the graft seen in the sagittal plane., In 2013 Khedr et al. studied 51 patients, both females and males who underwent ACL reconstruction followed by MRI. The study revealed complete ACL graft discontinuity was an important sign in diagnosis of full thickness tear with high specificity of 91% but had 58% specificity in discriminating full thickness tear from partial tear. In 2015, Kulczycka et al. studied that postoperative laxity of the ACL plasty was deemed to be a surgical failure and occurred in 1–8% of patients who underwent ACL ligament plasty and, which had a complication rate of 10–25%. In 2011, Galal et al. conducted a study on 48 patients to determine the MRI findings in a case of complication following ACL reconstructive surgery and found MRI to be most valuable imaging modality for postoperative evaluation of the knee. El Ameen et al. in 2014, on 34 patients studied the role of MRI in the evaluation of tibial tunnel and correlate findings with the rate of post anterior cruciate ligament repair complication and found that the graft impingement was the most frequently encountered complication representing 54.1%. In 2014, Alcalá-Galiano et al. studied the normal postsurgical anatomy and appearance of PCL reconstructions on MRI with the different operative techniques considering the type of tibial fixation, use of a single or double bundle, type of tendon graft, and the fixation material.
MRI arthrography of knee joint performed with direct injection of contrast media into the joint or indirect injection of contrast media through intravenous injection improves the visualization of ACL and PCL graft integrity. Gadolinium has lower viscosity than synovial fluid allowing greater imbibition into smaller clefts, and also the joint distension allows the separation of opposed edges. McCauley et al., in 2003, studied 27 patients with ACL reconstruction who had undergone MR arthrography and concluded that it accurately determines the graft tear whereas localized anterior arthrofibrosis and graft impingement were less accurately diagnosed with greater interobserver variability.
Thus, MRI plays and important diagnostic role in assessing the reconstructed ACL and PCL ligaments and diagnose the complications and cause of persistent knee pain. They have better spatial and temporal resolution than computed tomography, or conventional radiography is used as a gold standard diagnostic nowadays.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]