Paper # 257: Femoral Tunnels' Length Changes with Knee Flexion Angle in Anterior Cruciate Ligament Reconstruction

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ABSTRACTS

months after surgery, but the ADULT only reached 7% at the same time point (p⬍0.01). Similar results were found for the maximum load to failure. In addition, the linear stiffness of the untreated healing ACL in the JUVENILE knees was double that found for the ADULT knees, although the difference only approached statistical significance (p⫽0.09). Interestingly, the AP laxity at 60 degrees was 25% lower in the ADULT knees than in either the ADOLESCENT or JUVENILE knees (p⬍0.01 for both comparisons). The ligaments repaired using the collagen-PRP composite also had biomechanical properties that were dependent on animal age. The yield load in the ADOLESCENT animals with repair was 50% greater than that of the ADULT animals (p⬍0.01). The maximum load of both the ADOLESCENT and JUVENILE animals after repair was 40% greater than that of the ADULT animals (p⬍0.01 for both comparisons). The AP laxity at 90 degrees of flexion was 30% lower in the ADOLESCENT and JUVENILE knees than in the ADULT knees (p⬍0.01). Finally, the stiffness of the repaired ADOLESCENT and JUVENILE animals was 50% greater than the stiffness of the repair tissue in the ADULT animals (p ⬍0.01). Discussion: The results of this study support the hypothesis that the capacity for functional healing of a ligament after injury and enhanced repair is dependent on the level of skeletal maturity of the animal. JUVENILE animals had a more productive repair response to ACL transection than the older animals, with the repair tissue having a higher maximum load and stiffness. The ADOLESCENT animals derived the most benefit from suture repair using a collagen-platelet composite, with a doubling of the yield load in this group with treatment. The ADULT animals had the least functional repair response, both in terms of intrinsic healing (no treatment of the transected ACL) and enhanced suture repair. This work demonstrates partial healing of the ACL with an enhanced suture repair technique may provide a new treatment alternative – to stimulate healing of this important ligament rather than developing new ways to replace or reconstruct it.

Paper # 256: Prevention of Infection in ACL Reconstruction with Vancomycin Release from Presoaked Tendon Grafts CHRISTOPHER JOHN VERTULLO, MBBS, FRACS (ORTH), FA ORTH A, AUSTRALIA JANE GRAYSON, PHD, AUSTRALIA ANDREW JONES, FRACP, FRCPA, AUSTRALIA · Griffith University Gold Coast, QLD, AUSTRALIA

Summary: In this single surgeon, historically controlled series, the presoaking of hamstring grafts significantly reduced the post-operative infection rate. Abstract: Introduction: Infection from ACL Reconstruction is an uncommon but devastating event, with reported rates of 0.5% to 1.5%, typically due to bacterial colonization during harvesting. Poor post-infective outcomes have been described, including chondral damage, arthrofibrosis and graft failure. The outcomes of a novel technique of local antibiotic prophylaxis is reported. Methods: A longitudinal series of 885 consecutive single surgeon primary ACLR using identical operative techniques including prophylactic intravenous antibiotics were included. The initial 285 (Group A) acted as historical controls, and the subsequent 600 (Group B) underwent Vancomycin saturation of the hamstring tendons prior to implantation. Vancomycin concentrations were designed to be above minimum inhibitory concentrations for staphylococcus and below tissue toxicity levels. The Vancomycin concentration to achieve appropriate elution levels was investigated as part of a separate in-vitro animal study. Results: In the control Group A, with standard intravenous prophylaxis only, an infection rate of 1.45% resulted. This included 3 confirmed infections with coagulase negative staphylococcus and one presumed, culture negative, infection. This patient presented with low grade fever, rising CRP and responded to arthroscopic lavage with parental antibiotics. In Group B, with standard intravenous prophylaxis and local Vancomycin graft prophylaxis, an infection rate of 0% resulted. Graft failure was similar in both groups. No adverse response to the Vancomycin was observed. The difference was statistically significant using either Fischer’s Exact Test (p ⫽ 0.0106) or ChiSquared Test with Yates Correction (p ⫽ 0.0177). Conclusion: In this single surgeon, historically controlled series, the presoaking of hamstring grafts significantly reduced the post-operative infection rate. Paper # 257: Femoral Tunnels’ Length Changes with Knee Flexion Angle in Anterior Cruciate Ligament Reconstruction JULIO CESAR GALI, MD, BRAZIL HEETOR OLIVEIRA, MD, BRAZIL BRUNO ASPRINO CIÂNCIO, MD, BRAZIL RICARDO KOBAYASHI, MD, BRAZIL MARCOS VIANNA PALMA, MD, BRAZIL FREDDIE H. FU, MD, USA · Catholic University of São Paulo Sorocaba, São Paulo, BRAZIL

ABSTRACTS Summary: Drilling femoral tunnels with knee flexed at 110° provides sufficient tunnels’ length for good bone-graft interface, however for the posterolateral femoral tunnel, it may be safer to flex the knee up to 130°. Abstract: Introduction: Graft tunnel positioning is influenced, among other factors, by the knee’s intraoperative flexion angle during drilling in anterior cruciate ligament reconstruction (ACL). The ideal way to reach the anteromedial (AM) and posterolateral (PL) femoral insertions of the ACL is through the accessory anteromedial (AAM) portal. However, this method may produce shorter femoral tunnels than the transtibial technique, which might compromise the quality of bone-graft interface. The objective of our study was to evaluate the effect of knee flexion angle for drilling in femoral tunnel’s length. Methods: We measured the femoral AM and PL tunnels’ length in 20 anatomical unpaired pieces, 10 rights and 10 lefts, with the articular cartilage and cruciate ligaments intact. Tunnel drilling was done with the knees flexed at 90°, 110° and 130° of flexion, through AAM portal with a 2.5mm drill. Statistical analysis was done by Friedman’s variance analysis and Mann-Whitney U test. The Mann-Whitney U test, in our study, was used for testing whether right and left knees tunnels’ length means were equal or not. Results: The average AM femoral tunnels’ length we measured, evaluated at 90°, 110° and 130° of flexion was 33.7 (⫾ 3.72) mm, 37.4 (⫾ 2.93) mm and 38.8 (⫾ 3.31) mm, respectively. For the PL femoral tunnels’ length the results were 32.1 (⫾ 4.24) mm, 37.3 (⫾ 4.85) mm and 38.4 (⫾ 2.51) mm. The Friedman’s variance analysis showed significant difference between the checked tunnels’ length with 90° and 110° of flexion angle, but showed no significant difference between the 110° and 130° (p ⬍ 0.05). The Mann-Whitney U test showed that samples came from different populations, i.e. right and left knees could be added to form just one heterogeneous group (P ⬍⫽ 0.05). Discussion and Conclusion: Clinical outcome of ACL reconstruction is influenced by different factors, among them the amount of graft inside the tunnel, which is determined by the tunnels’ length itself. The 90° flexion angle seems to provide better arthroscopic view to prevent incorrect graft placement. However, knee flexion angle while drilling can determine tunnels’ length. Technical reports suggest that tunnels’ placement should be done at 90° of flexion, while others advise 110° or even 130° of flexion. Cadaver studies, like ours, may reflect more accurately individual’s variation. The average AM

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femoral tunnels’ length we measured, evaluated at 90°, 110° and 130° of flexion was 33.7 (⫾ 3.72) mm, 37.4 (⫾ 2.93) mm and 38.8 (⫾ 3.31) mm, respectively. For the PL femoral tunnels’ length the results were 32.1 (⫾ 4.24) mm, 37.3 (⫾ 4.85) mm and 38.4 (⫾ 2.51) mm. The Friedman’s variance analysis showed significant difference between the checked tunnels’ length with 90° and 110° angle flexion, but showed no significant difference among the 110° and 130° (p ⬍ 0.05). Femoral fixation with Endobutton may provide better collagen filling in tunnels than with interference screws, and 15mm of graft inside the tunnel may be the minimal amount of graft for a good bone-graft integration. We believe that femoral insertion location’s mark should be done at 90° of flexion; however, as the minimal Endobutton length is 20mm, it is better to drill the femoral AM tunnel through the AAM tunnel with the knee flexed at 110° in a way to provide a minimal length sufficient for a good bone-graft interface. On the other hand for the PL femoral tunnel, it may be safer to flex the knee up to 130°. Paper # 258: Prospective Clinical Comparisons of Semitendinosus versus Semitendinosus and Gracilis Tendon Autografts for Anatomic Double-bundle Anterior Cruciate Ligament Reconstruction YUSUKE INAGAKI, MD, JAPAN EIJI KONDO, MD, PHD, JAPAN NOBUTO KITAMURA, MD, JAPAN HARUKAZU TOHYAMA, MD, PHD, JAPAN TOMONORI YAGI, MD, PHD, JAPAN YASUHITO TANAKA, MD, JAPAN KAZUNORI YASUDA, MD, PHD, JAPAN · Hokkaido University School of Medicine Sapporo, Hokkaido, JAPAN Summary: Concerning the postoperative side-to-side anterior laxity, the peak muscle torque, the Lysholm knee score, and the IKDC evaluation, there were no significant differences between the 2 graft types (Semitendinosus tendon alone or Semitendinosus and Gracilis tendons) after anatomic double-bundle ACL reconstruction. Abstract: Introduction: Recently, double-bundle ACL reconstruction has attracted a great deal of attention as a potential procedure to improve results of single-bundle ACL reconstruction. We have developed the anatomic doublebundle ACL reconstruction using hamstring tendon autografts.[1] More recently, authors reported that anatomic double-bundle procedure was significantly better than single-bundle procedure concerning the anterior and ro-