Original article
Graft Length Changes in the Bi-Socket Anterior Cruciate Ligament Reconstruction: Comparison Between Isometric and Anatomic Femoral Tunnel Placement

https://doi.org/10.1016/j.arthro.2005.08.018Get rights and content

Purpose: To compare the length change of grafts in bi-socket anterior cruciate ligament (ACL) reconstruction between isometric and anatomic placement. Type of Study: Case series. Methods: The subjects were 110 knees of 110 patients with a mean age of 27 years. All knees were reconstructed using multistranded autogenous semitendinosus tendon and the bi-socket procedure. Of those, 43 knees were reconstructed in the isometric position, around the isometric point (group I) and the remaining 67 in the anatomic position, mimicking the anatomic footprint of ACL (group II). Grouping was performed based on the femoral socket position. Each femoral socket for the anterior medial graft (AMG) and the posterolateral graft (PLG) for the left knee was positioned at 1 o’clock and 2 o’clock to 2:30 in group I, or 2 o’clock and 3 o’clock in group II in the posterior border of the notch. Their positioning for the right knee was at 11 o’clock and 9:30 to 10 o’clock in group I, or 10 o’clock and 9 o’clock in group II. The length changes of grafts were intraoperatively measured while extending the knee from 120° to full extension, using a commercially available isometric positioner. The Student t test was used for statistical analysis. Results: All the grafts showed the pattern of elongation approaching extension. The length change of AMG and PLG was 1.3±0.6 mm and 2.2±1.0 mm in the group I, 1.4±0.7 mm and 2.5±0.9 mm in the group II, respectively. There was no statistically significant difference in the values of AMG (P = .51) and PLG (P = .074) between the 2 groups. Conclusions: The length change of ACL grafts placed in the anatomic position was not significantly different from that positioned in the isometric position. Level of Evidence: Level IV, case series.

Section snippets

Patients

Bi-socket ACL reconstruction with multistranded hamstring tendon grafts was performed on 230 knees by 3 surgeons between January 1999 and February 2002 in our facilities. Among these, we intraoperatively measured the length change of both anteromedial and posterolateral grafts in 116 knees operated by the senior author (K.S.). The remaining 114 knees were excluded from this study because they were operated by the other authors. Of the 116 knees, we selected 110 knees of 110 patients (53 female

Results

All grafts showed elongation approaching extension. The average length change of AMG and PLG was 1.3 ± 0.6 mm and 2.2 ± 1.0 mm in group I, 1.4 ± 0.7 mm and 2.5 ± 0.9 mm in group II, respectively. There was no significant difference in length changes of AMG (P = .51) or PLG (P = .074) between the 2 groups (Table 1).

Discussion

Multistranded hamstring tendon grafts are widely used and the bi-socket technique is becoming increasingly popular.1, 2, 3, 4, 21 Although the isometric bi-socket ACL reconstruction is performed to mimic the 2 bundles of the normal ACL, the anatomic reconstruction has been recently found to achieve not only more natural fiber orientation of the ACL but also better function against rotational stress to the tibia as well as anterior tibial load in several biomechanical studies.15, 16, 17, 18

Conclusions

There were no statistically significant differences in length change of the AMG or PLG throughout the range of motion between the isometric and the anatomic reconstruction.

References (28)

  • M. Odensten et al.

    Functional anatomy of the anterior cruciate ligament and a rationale for reconstruction

    J Bone Joint Surg Am

    (1985)
  • J.A. Sidles et al.

    Ligament length relationships in the moving knee

    J Orthop Res

    (1989)
  • W.R. O’Brien et al.

    Fiber recruitment of the cruciate ligaments

  • A.A. Amis et al.

    Functional anatomy of the anterior cruciate ligament

    J Bone Joint Surg Br

    (1991)
  • Cited by (0)

    View full text