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

ABSTRACT 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.

Download full-text


Available from: Alcindo Silva, Feb 23, 2014
108 Reads
  • Source
    • "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. "
    [Show abstract] [Hide abstract]
    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.
    Knee Surgery Sports Traumatology Arthroscopy 08/2012; 21(7). DOI:10.1007/s00167-012-2153-9 · 3.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The potential performance enhancement of polysilicon emitters in bipolar transistors may be reduced when the contact resistance is high and nonohmic. Our experimental data shows the expected correlation between DC series resistance and AC switching performance even for polysilicon emitters without intentional interface oxides.
    VLSI Technology, 1986. Digest of Technical Papers. Symposium on; 06/1986
  • Source
    Knee Surgery Sports Traumatology Arthroscopy 09/2010; 18(9):1151-3. DOI:10.1007/s00167-010-1222-1 · 3.05 Impact Factor
Show more