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Articles by A. D. Pearle
Total Records ( 4 ) for A. D. Pearle
  B. T Feeley , M. S Muller , A. A Allen , C. C Granchi and A. D. Pearle
  Background

The medial collateral ligament is a broad ligament that functions as the primary stabilizer against valgus knee stress, particularly at 30° of flexion.

Hypothesis

A double-bundle reconstruction technique that better restores the native medial collateral ligament anatomy will restore valgus and external rotation stability to a medial collateral ligament–deficient knee.

Study Design

Controlled laboratory study.

Methods

Seven fresh-frozen cadaveric knees were studied. A surgical navigation system was used to determine valgus opening and external rotation at 0° and 30° with a 9.8-N·m valgus stress applied to the tibia graft isometry at multiple points on the tibia and femur. Intact and disrupted medial collateral ligament knees were used as controls. Four repair techniques were tested: Bosworth, modified Bosworth, anatomical single bundle, and anatomical double bundle.

Results

Complete sectioning of the medial collateral ligament resulted in an increase in valgus opening of 5° at 0° and 7.7° at 30°. External rotation increased 4.6° at 0° and 9.7° at 30°. Single-bundle techniques (Bosworth, anatomical single bundle) did not restore valgus laxity at 0° or 30°; the anatomical single bundle did not restore external rotation at 0°. Double-bundle techniques (modified Bosworth, anatomical double bundle) restored valgus laxity and external rotation to the native knee conditions at 0° and 30°. At 30°, the modified Bosworth was 0.3° tighter and the anatomical double bundle 0.2° tighter than was the intact knee. The center of the medial collateral ligament origin on the femur to the proximal insertion of the superficial medial collateral ligament resulted in the most isometric graft position.

Conclusion

Medial collateral ligament reconstruction configurations that use a double-bundle reconstruction better resist valgus and external rotations in response to valgus stress than do single-bundle techniques.

Clinical Relevance

Although the medial collateral ligament often heals without surgical intervention, surgical reconstruction is occasionally necessary in grade III medial collateral ligament and combined ligamentous injuries to the knee. Double-bundle reconstruction of the medial collateral ligament better resists valgus forces across the knee and may allow for better surgical outcome after medial collateral ligament reconstruction.

  R. H Brophy and A. D. Pearle
  Background:

Conventional endoscopic single-bundle transtibial anterior cruciate ligament (ACL) reconstruction from the posterolateral tibial footprint to the anteromedial femoral footprint results in a vertical graft. A more oblique horizontal graft from the anteromedial tibial footprint to the posterolateral femoral footprint may offer a better alternative for all endoscopic ACL reconstruction.

Hypothesis:

When compared with a conventional ACL single-bundle position, the horizontal graft ACL position has more obliquity and so undergoes a greater change in length during anterior translation and internal rotation.

Study Design:

Controlled laboratory study.

Methods:

A computer navigation system was used to acquire kinematic data during a flexion-extension cycle and outline the anteromedial and posterolateral aspects of the tibial and femoral footprints on 5 fresh-frozen cadaveric knees. Three virtual graft positions were defined: conventional (posterolateral tibia–anteromedial femur), central, and horizontal (anteromedial tibia– posterolateral femur). After transection of the ACL, the obliquity, anisometry, absolute length change, and apparent strain were computed for each graft position during the Lachman test, the anterior drawer test, and internal rotation at 0° and 30° of flexion.

Results:

The horizontal position was more oblique than the other positions (P < .05). There were no differences in anisometry. The horizontal position elongated more than the other positions during the Lachman test (P < .05) and more than the conventional position during the anterior drawer test (P = .009). During internal rotation at 30° flexion, the horizontal position elongated more than the other positions (P < .05). The central and horizontal positions had more apparent strain than that of the vertical position during the Lachman test and internal rotation (P < .05); no significant difference was found during the anterior drawer test.

Conclusion:

In ACL-deficient cadaveric knees, the horizontal graft position has greater obliquity and so undergoes greater elongation without increased apparent strain when compared to the central graft position, in response to anterior translation and internal rotation maneuvers.

Clinical Relevance:

Horizontal graft placement of a single-bundle ACL may result in greater control of translation and rotation.

  J Robinson , F. C Stanford , D Kendoff , V Stuber and A. D. Pearle
  Background:

The native anterior cruciate ligament (ACL) does not behave as a simple bundle of fibers with constant tension but as a continuum of ligament fibers with differential length change during knee flexion/extension. Computer-assisted navigation can be used to assess length change in different fibers within the native ACL and to evaluate how different reconstruction grafts replicate the range of native ligament fiber length change behavior.

Hypothesis:

Anterior cruciate ligament reconstruction graft size and configuration (single-vs double-bundle) are deciding factors as to how much of the native ACL fiber length change behavior is replicated.

Study Design:

Controlled laboratory study.

Methods:

The fiber length change behavior of the entire native ACL was assessed by measuring the length change pattern of representative anteromedial (AM) and posterolateral (PL) bundle fibers (1 at the center and 4 at the periphery of each bundle). The tibial and femoral ACL attachment areas in 5 fresh-frozen cadaveric knees were digitized, and the length change of each representative fiber was recorded during knee flexion/extension using an image-free, optical navigation system. Subsequently, single-bundle ACL reconstructions of different diameters (6, 9, and 12 mm) positioned at the center of the overall native femoral and tibial attachment sites were modeled to assess how much of the range of ligament fiber length change of the native ligament was captured. This was compared with a double-bundle graft using 6-mm-diameter AM and PL grafts positioned at the centers of the femoral and tibial attachment sites of each separate bundle.

Results:

The 6-, 9-, and 12-mm single-bundle grafts simulated 32%, 51%, and 66% of the ligament fiber length change behavior of the native ACL, respectively. The length change patterns in these grafts were similar to the central fibers of the native ACL: the PL fibers of the AM bundle and AM fibers of the PL bundle. However, even a 12-mm graft did not represent the most AM and PL native fibers. The 6-mm AM and PL bundle grafts (equivalent in cross-sectional area to a 9-mm single-bundle graft) simulated 71% of the native ACL and better captured the extremes of the range of native ligament fiber length change.

Conclusion:

Increasing single-bundle graft size appears to capture more of the range of native ACL fiber length change. However, for a similar graft cross-sectional area, a 2-bundle graft simulates the length change behavior of the native ligament more precisely and thus may better emulate the synergistic actions of anisometric and isometric fibers of the native ligament in restraining knee laxity throughout the range of flexion.

Clinical Relevance:

The range of native ACL fiber length change behavior is better replicated by larger diameter grafts but may be best reproduced by double-bundle reconstruction.

  V Musahl , M Citak , P. F O'Loughlin , D Choi , A Bedi and A. D. Pearle
 

Background: The pivot shift is a dynamic test of knee stability that involves a pathologic, multiplanar motion path elicited by a combination of axial load and valgus force during a knee flexion from an extended position.

Purpose: To assess the stabilizing effect of the medial and lateral meniscus on anterior cruciate ligament-deficient (ACL-D) knees during the pivot shift examination.

Study Design: Controlled laboratory study.

Methods: A Lachman and a mechanized pivot shift test were performed on 16 fresh-frozen cadaveric hip-to-toe lower extremity specimens. The knee was tested intact, ACL-D, and after sectioning the medial meniscus (ACL/MM-D; n = 8), lateral meniscus (ACL/LM-D; n = 8), and both (ACL/LM/MM-D; n = 16). A navigation system recorded the resultant anterior tibial translations (ATTs). For statistical analysis an analysis of variance was used; significance was set at P < .05.

Results: The ATT significantly increased in the ACL-D knee after lateral meniscectomy (ACL/LM-D; P < .05) during the pivot shift maneuver. In the lateral compartment of the knee, ATT in the ACL-D knee increased by 6 mm after lateral meniscectomy during the pivot shift (16.6 ± 6.0 vs 10.5 ± 3.5 mm, P < .01 for ACL/LM out vs ACL out). Medial meniscectomy, conversely, had no significant effect on ATT in the ACL-D knee during pivot shift examination (P > .05). With standardized Lachman examination, however, ATT significantly increased after medial but not lateral meniscectomy compared with the ACL-D knee (P < .001).

Conclusion: Although the medial meniscus functions as a critical secondary stabilizer to anteriorly directed forces on the tibia during a Lachman examination, the lateral meniscus appears to be a more important restraint to anterior tibial translation during combined valgus and rotatory loads applied during a pivoting maneuver.

Clinical Relevance: This model may have implications in the evaluation of surgical reconstruction procedures in complex knee injuries.

 
 
 
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