Femoral tunnel enlargement after anatomic ACL reconstruction: A biological problem?

Military Hospital D. Pedro V, Avenida da Boavista, Porto, Portugal.
Knee Surgery Sports Traumatology Arthroscopy (Impact Factor: 3.05). 09/2010; 18(9):1189-94. DOI: 10.1007/s00167-010-1046-z
Source: PubMed


Tunnel enlargement after anterior cruciate ligament (ACL) reconstruction may compromise revision surgery. The cause of this tunnel enlargement is not yet fully understood, but it is thought to be multifactorial, with biomechanical and biological factors playing a role. Tunnel enlargement has been described particularly in patients who underwent ACL reconstruction with hamstring tendons with extracortical fixation devices. The purpose of our study was to evaluate prospectively with magnetic resonance imaging (MRI) the changes in femoral tunnel diameter following arthroscopic anatomic ACL reconstruction with hamstring tendons. At 3-month post-op, all tunnels had enlarged compared to the diameter of the drill and most tunnels enlarged more in the midsection than at the aperture. In the posterolateral tunnels, the entrance increased 16% in diameter and the middle of the tunnel increased 30% in diameter. In the anteromedial femoral tunnels, the tunnels enlarged 14% at the aperture and 35% in the midsection. All femoral tunnels enlarged and most of them enlarged in a fusiform manner. The biological factors explain better our findings than the mechanical theory, although mechanical factors may play a role and the cortical bone at the entrance of the tunnel may modify the way tunnels respond to mechanical stress.

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Available from: Alcindo Silva, Feb 23, 2014
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    • "Tunnel widening or tunnel enlargement is a previously unrecognized phenomenon associated with ACL reconstruction , which is referred to in the literature over the last two decades [1] [2] [3] [4] [5] [6] [7]. The clinical relevance of the phenomenon has been questioned [1] [3] [6] [8] but there are studies that consider this an important complication [9] making revision surgery problematic [10] [11] [12] [13]. "
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    ABSTRACT: Purpose. In this study, the early and midterm clinical and radiological results of the anterior cruciate ligament (ACL) reconstruction surgery with or without the use of platelet rich plasma (PRP) focusing on the tunnel-widening phenomenon are evaluated. Methods. This is a double blind, prospective randomized study. 51 patients have completed the assigned protocol. Recruited individuals were divided into two groups: a group with and a group without the use of PRPs. Patients were assessed on the basis of MRI scans, which were performed early postoperatively and repeated at least one-year postoperatively. The diameter was measured at the entrance, at the bottom, and at the mid distance of the femoral tunnel. Results. Our study confirmed the existence of tunnel widening as a phenomenon. The morphology of the dilated tunnels was conical in both groups. There was a statistical significant difference in the mid distance of the tunnels between the two groups. This finding may support the role of a biologic response secondary to mechanical triggers. Conclusions. The use of RPRs in ACL reconstruction surgery remains a safe option that could potentially eliminate the biologic triggers of tunnel enlargement. The role of mechanical factors, however, remains important.
    Full-text · Article · Nov 2014
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    • "Currently, MRI is used not only for diagnosis, but also for the measurement of the size and inclination angle of the ACL, pre-operative assessment of the size of autograft sources and post-operative evaluation of graft healing [1, 15]. MRI has also been used in several other evaluations related to ACL reconstruction, such as tunnel enlargement [25], roof impingement [13], tibiofemoral relation [27] and cartilage degenerative changes after ACL injury [18]. This paper focuses on all applications of MRI in anatomic ACL reconstruction. "
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    ABSTRACT: Purpose Magnetic resonance imaging (MRI) is the most current diagnostic imaging procedure for suspected ACL injuries. It is an accurate, highly sensitive and specific tool for the diagnosis of ACL tears, graft tears and associated injuries. However, it can also be used for various other aspects of anatomic ACL reconstruction. Methods Special sequences as the oblique sagittal plane should be obtained from a parallel line to the lateral epicondyle, ensuring a proper visualization of both bundles of the ACL. Another special set of images, the oblique-coronal sequence, allows for the ACL long-axis evaluation. The coronal-oblique sequence increases the sensitivity and specificity of diagnosing isolated AM or PL bundle injuries and also helps to visualize the proximal insertion of the bundles for haemorrhage and rupture. Results Quantitative measurements can be taken from a proper MRI protocol, so as to determine the rupture pattern; measure insertion site size, inclination angle and autograft size; and evaluate for post-operative complications. These parameters help surgeons to objectively decide for a better graft and technique for an individualized approach and to evaluate the anatomic placement of the graft. Conclusions MRI can be used in different ways, serving as a very valuable tool in anatomic ACL reconstruction. Special protocols can provide accurate visualization of the double-bundle anatomy. Objective parameters to aid in pre-operative decisions and graft’s anatomic placement evaluation can be also extracted from the MR images.
    Full-text · Article · Aug 2012 · Knee Surgery Sports Traumatology Arthroscopy
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