2015 ISAKOS Biennial Congress ePoster #1325

Bone Bridge Between Femoral Bone Tunnels Affects Bone Tunnel Enlargement After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction

Daisuke Araki, MD, PhD, Kobe, Hyogo JAPAN
Ryosuke Kuroda, MD, PhD, Kobe, Hyogo JAPAN
Yosuke Uozumi, MS, Fukui JAPAN
Nagamune Kouki, PhD, Fukui, Fukui JAPAN
Takehiko Matsushita, MD, Kobe, Hyogo JAPAN
Tomoyuki Matsumoto, MD, PhD, Kobe, Hyogo JAPAN
Koji Takayama, MD, PhD, Kobe, Hyogo JAPAN
Yuichi Hoshino, MD, PhD, Kobe, Hyogo JAPAN
Masahiro Kurosaka, MD, Kobe, Hyogo JAPAN

Kobe University Graduate School of Medicine, Kobe, Hyogo, JAPAN

FDA Status Not Applicable

Summary: This study demonstrated that a short bone bridge width between the femoral AMB and PLB tunnels may lead to bone tunnel enlargement, whereby the AMB is especially influenced, and indicated that minimum 2.3 mm bone bridge should be preserved in an effort to prevent bone tunnel enlargement.

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Abstract:

Introduction

According to the recent literatures on double-bundle (DB) anterior cruciate ligament reconstruction (ACL-R), the anteromedial bundle (AMB) and posterolateral bundle (PLB) bone tunnels should be preserved in order to avoid bone tunnel communication. However, the relationship between bone tunnel enlargement and the width of the bone bridge between the two tunnels has not been investigated. Therefore, the purpose of this study was to investigate the relationship between femoral bone tunnel volume changes and the width of bone bridge between the two femoral bone tunnels using the three-dimensional (3D) multi detector-row computed tomography (MDCT) data. The hypothesis was that a short bone bridge width may lead to bone tunnel enlargement in anatomic DB ACL-R.

Methods

Twenty patients were included in this study (9 males and 11 females; 25.1±10.0 years). Anatomic DB ACL-R was performed in all cases. In brief, the bone tunnels were created at the positions of these original insertion sites. Four-strand semitendinosus tendon autograft was used and fixed using the EndoButton CL system for the femur and a cancellous screw with washer for the tibia.
The knees were scanned at 3 weeks and 1 year after surgery by MDCT. The bone tunnel region was identified and extracted on each CT slice to obtain a 3D tunnel volume. Each extracted bone tunnel was divided into three separate sections according to the longitudinal axis of the tunnels. On femoral articular one-third sections of AMB and PLB were used for comparison. The bone tunnel changes 1 year after surgery relative to the bone tunnel volume at 3 weeks after surgery (100 %) were assessed. Based on the bone tunnel volume change, we divided the patients into two groups; the bone tunnel enlargement group (Group E) and the bone tunnel reduction group (Group R) in both AMB and PLB, respectively. Next, the width of the bone bridge was measured on the 3D-MDCT. The clinical outcomes including the Lachman test, the pivot shift test, the side-to-side difference of KT-1000 and the Lysholm score were also collected at 1 year after surgery.

Results

In the AMB, Group E included 7 patients (135.8±29.2%), whereas Group R was 13 patients (83.3±11.9%). In the PLB, Group E included 6 patients (137.1±16.9%), whereas Group R was 14 patients (77.7±13.9%). The femoral bone tunnel communication was found in 1 patient. The femoral bone tunnel communication was found in 1 patient.
Looking at the width of the bone bridge, the width in Group E showed a significant shorter value compared with Group R in the AMB (p=0.003), whereas no significant difference was observed in the PLB (p=0.248). Strong positive correlation was found between the width of bone bridge and percentage bone tunnel volume change in the AMB (r=0.740), whereas weak correlation was observed in the PLB (r=0.494). According to the receiver-operator characteristic curve, the cutoff level yielding maximal sensitivity plus specificity for predicting the presence of risk factors was 2.27 mm in AMB and 1.19 mm in PLB. In addition, our clinical results showed no significant differences between Group E and Group R in the clinical outcomes including the Lachman test, the pivot shift test, the side-to side difference of KT-1000 measurements and the Lysholm score.

Discussion

This study demonstrated that a short bone bridge width between the femoral AMB and PLB tunnels may lead to bone tunnel enlargement, whereby the AMB is especially influenced. This study indicated that minimum 2.3 mm bone bridge should be preserved in an effort to prevent bone tunnel enlargement.