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Purpose: Remnant preservation, in anterior cruciate ligament (ACL) reconstruction, has potential biological advantages. However, graft positioning remains vital to functional outcome and the prevention of failure. The aim of this study was to investigate the accuracy and precision of tibial tunnel positioning in remnant preservation single-bundle hamstring reconstruction., Methods: Fifty consecutive adult patients, with isolated ACL rupture, were recruited to a prospective study. Remnant preservation was performed in all cases where > 25% of the native ACL was present. Three-dimensional computer tomography was preformed 3-6 months post-operatively to assess tibial tunnel position (using a grid-based measurement). Accuracy and precision of this technique were assessed against published anatomical data in direct comparison with the group where remnant preservation could not be performed., Results: Two patients withdrew following surgery. In the remaining groups (31 remnant preservation; 17 non-remnant preservation), no difference was demonstrated in tunnel position (40.4 ± 6.7% (anterior-to-posterior) and 47.4 ± 1.5% (medial-to-lateral) vs. 38.8 ± 4.9% and 46.7 ± 1.5%, respectively; n.s.), accuracy (6.1% vs. 4.8%; n.s.) or precision (3.9% vs. 2.8%; n.s.)., Conclusions: Remnant preservation can be safely performed without compromising tunnel position. Therefore, the potential benefits of this technique can be utilised, in clinical practice, without sacrificing the ability to optimize tibial tunnel positioning., Level of Evidence: III.

Purpose: The hyperflexion required for femoral tunnel drilling in anterior cruciate ligament reconstruction can be challenging in patients with increased body habitus or musculature. Whilst allowing femoral tunnel creation without hyperflexion, additional benefits of flexible reamers have been proposed in terms of tunnel dimensions. The purpose of this study was to examine whether these theoretical benefits are seen in a clinical study., Methods: Fifty adult patients (with isolated anterior cruciate ligament rupture) were randomised to reconstruction with either flexible or rigid femoral reamers. Femoral tunnel drilling was performed at 100° flexion (flexible system) or maximal hyperflexion (rigid system). Otherwise, the procedure was standardised. Femoral tunnel measurements were performed by a consultant musculoskeletal radiologist who was blinded to the method of femoral drilling. Tunnel position, length and angles (axial and coronal) were measured alongside aperture shape and exit point using three-dimensional computed tomography 3-6 months post-operatively., Results: With no difference in tunnel position, tunnel length was found to increase with the use of the flexible system (37.8 ± 3.7 vs 35.0 ± 4.4 mm; p = 0.024). In addition, the exit point and fixation device were more anterior on the lateral femur using the flexible reamers (p = 0.016). No difference was seen in either tunnel angles or aperture shape. One case of incomplete posterior blow-out was seen in each of the study groups., Conclusions: This comparative study shows that flexible reamers can reproduce a desired femoral tunnel position with only small improvements of no clinical relevance. As this can be achieved without hyperflexing the knee, these systems can be used for all patients (even when hyperflexion is a challenge)., Level of Evidence: I.

Objective: The magnetic resonance imaging (MRI) appearance of the anterolateral ligament (ALL) has been described. However, the appearance of this structure and injury, in the presence of anterior cruciate ligament (ACL) injury, is less well defined. We studied the incidence of injury to the ALL and the pattern of this injury on MRI., Materials and Methods: Following Institutional Review Board approval, a retrospective study of 375 consecutive MRI studies was performed. Cases were identified from a prospective database of ACL reconstruction patients. Following exclusions, 280 MRIs (277 patients; 197 males: 80 females; mean age 30.2 years, range, 16-54) were evaluated. Injury was defined as full thickness, partial thickness, or an avulsion fracture. Each study was independently assessed by two consultant musculoskeletal radiologists., Results: Injury to the ALL was identified (by at least one observer) in only 10.7% of cases (2.50% full thickness, 7.50% partial thickness, and 0.71% avulsion fracture). There was an almost perfect level of interobserver agreement for both the identification of an injury (κ = 0.854) and grading of injury (κ = 0.858). The MRI incidence of ALL injury was significantly greater within 6 weeks of the knee injury (18.5 vs. 8.37%; p < 0.05)., Conclusions: ALL injury was identified in only one-tenth of cases of ACL rupture. MRI changes can be reliably identified with strong agreement between observers. ALL injury is found more frequently on MRI within 6 weeks of the knee injury (compared to scans performed after this time period) suggesting that some injuries may resolve or become less visible.