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: 2.68). 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.

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    ABSTRACT: The purpose of this study is to assess the incidence of post-operative femoral bone tunnel communication after anterior cruciate ligament double-bundle reconstruction (ACL-DBR) with two drilling techniques by transparent 3-dimensional computed tomography (CT) and elucidate the factors associated with post-operative femoral bone tunnel communication. Fifty-five patients underwent ACL-DBR using outside-in technique (Group A, 25 patients) and transportal technique (Group B, 30 patients) for the drilling of femoral tunnel. CT was taken at 1 week and 6 months post-operatively. The femoral and tibial bone tunnel orientation, position, the divergency and the distance of bone bridge between the tunnels were measured using reconstructed CT images. In order to identify the factors related to post-operative femoral bone tunnel communication, patients were divided into two groups depending on whether femoral bone tunnels communicated (Group F-C) or remained (Group F-R) at 6 months post-operatively. Femoral bone tunnels in Group B were orientated horizontally and dorsally compared to those in Group A. Tunnel divergency between two femoral tunnels was greater in Group A (11.7°) than in Group B (10.0°). Average distance of bone bridge at 1 week post-operatively was 1.8 mm in Group A and 1.7 mm in Group B (n.s.). Post-operative femoral bone tunnel communication occurred in 16 patients (64 %) in Group A and in 18 patients (60 %) in Group B at 6 months after ACL-DBR, respectively (n.s.). Regarding tibial tunnels, there were no significant differences in tunnel orientation, position, divergency and incidence of post-operative tibial tunnel communication between Groups A and B. Mean distance of femoral bone bridge at 1 week in Group F-R (2.5 mm) was significantly greater than in Group F-C (1.3 mm) (p < 0.001). There was no significant difference in the incidence of post-operative femoral tunnel communication between two techniques. To avoid post-operative femoral tunnel bone communication, more than 2 mm distance of bone bridge at surgery is recommended. Retrospective comparative study, Level III.
    Knee Surgery Sports Traumatology Arthroscopy 07/2013; · 2.68 Impact Factor
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    ABSTRACT: Background: Augmentation consisting of a selective reconstruction of the ruptured bundle while preserving the remnant bundle has been proposed as a treatment option for partial anterior cruciate ligament (ACL) tears. Good clinical outcomes after selective anteromedial (AM) bundle augmentation have been reported, whereas little is known about selective reconstruction of the pos- terolateral (PL) bundle with preservation of the AM bundle remnant. Purpose: The purpose of this study was to evaluate the clinical outcomes and the magnetic resonance imaging (MRI) charac- teristics of selective PL bundle reconstruction with a median follow-up of 24 months. Study Design: Case series; Level of evidence, 4. Methods: In a consecutive series of 741 ACL reconstructions, 44 patients underwent a selective PL bundle reconstruction with preservation of the AM remnant. Four patients with contralateral knee ligament surgery and 1 patient who sustained a traumatic rupture of his graft were excluded, leaving 39 patients for final evaluation. Clinical evaluation of knee function and laxity were recorded preoperatively and at a mean 24.2-month follow-up. Magnetic resonance imaging was performed on 35 patients at a mean 25.9-month follow-up for evaluation of graft and remnant bundle continuity, tunnel enlargement, and graft remodeling status by measuring the signal intensity of the graft (contrast/noise quotient [CNQ]). Results: Tegner and Lysholm knee scores were significantly improved after surgery. The subjective International Knee Docu- mentation Committee (IKDC) score was 43.5 + 16.6 preoperatively and 89.9 + 6.6 at the final follow-up (P < .01). The objective IKDC score was ‘‘B’’ for 17 patients, ‘‘C’’ for 21 patients, and ‘‘D’’ for 1 patient preoperatively, while it was ‘‘A’’ for 34 patients and ‘‘B’’ for 5 patients postoperatively (P < .01). The mean side-to-side anteroposterior laxity was 5 mm (range, 4-10 mm) preopera- tively and 1.5 mm (range, 􏰀1 to 4 mm) at final follow-up (P < .01). On MRI, the graft was visible and continuous in all cases. No cyclops lesions were noted. The average CNQ for the PL graft and the AM remnant bundle was 3.2 + 1 and 2.9 + 1.2, respectively. Minimum bone tunnel enlargement was found. Conclusion: Selective PL bundle reconstruction restores knee stability and function. At final follow-up, MRI showed continuity of the PL graft without signs of dramatic tunnel enlargement or cyclops syndrome. Keywords: ACL partial tear; anterior cruciate ligament; posterolateral (PL) bundle
    Orthopaedic Journal of Sports Medicine. 08/2013;
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    ABSTRACT: To investigate changes in femoral tunnel diameter, dimension, and volume after anterior cruciate ligament reconstruction with notchplasty. Porcine knee specimens were divided into 2 groups of 10 specimens each. Group A did not receive notchplasty. A 2-mm notchplasty was conducted in group B. Seven-millimeter-diameter femoral tunnels were drilled and a doubled flexor digitorum profundus tendon was inserted and fixed with an EndoButton (Smith & Nephew, Andover, MA) in each knee specimen. Samples were mounted on a materials testing machine. Each group was preloaded at 10 N and subjected to 20 loading cycles (between 0 and 40 N), followed by 1,000 loading cycles in the elastic region (between 10 and 150 N). High-resolution computed tomography with 1.0-mm slices was conducted with all samples before and after testing. A 3-dimensional model was constructed to evaluate the degree of the tunnel change. In group B the mean longest diameter and dimension of the femoral tunnel significantly increased after the test (P = .005 and P = .001, respectively). The volumetric loss of bony structure after the test in group B was significantly greater than that in group A (P = .039). Meanwhile, no significant difference was found before and after the test in terms of tunnel diameter, dimension, and volumetric loss around the tunnel in group A. The intra-articular orifice of the femoral tunnel was enlarged after the uniaxial cyclic loading test after notchplasty. An enlarged tunnel orifice may lead to a discrepancy between the tunnel and the graft at the tunnel aperture. The data may have an implication that suspensory fixation with a notchplasty has a negative effect on the full graft accommodation at the tunnel aperture. Aperture widening may affect graft positioning, leading to subtle changes in graft biomechanics and laxity.
    Arthroscopy The Journal of Arthroscopic and Related Surgery 04/2014; · 3.10 Impact Factor


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