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How well do anatomical reconstructions of the posterolateral corner restore varus stability to the posterior cruciate ligament-reconstructed knee?
Am J Sports Med. 2007 Jul; 35(7):1117-22.AJ

Abstract

BACKGROUND

With grade 3 posterolateral injuries of the knee, reconstructions of the lateral collateral ligament, popliteus tendon, and popliteofibular ligament are commonly performed in conjunction with a posterior cruciate ligament reconstruction to restore knee stability.

HYPOTHESIS

A lateral collateral ligament reconstruction, alone or with a popliteus tendon or popliteofibular ligament reconstruction, will produce normal varus rotation patterns and restore posterior cruciate ligament graft forces to normal levels in response to an applied varus moment.

STUDY DESIGN

Controlled laboratory study.

METHODS

Forces in the native posterior cruciate ligament were recorded for 15 intact knees during passive extension from 120 degrees to 0 degrees with an applied 5 N .m varus moment. The posterior cruciate ligament was removed and reconstructed with a single bundle inlay graft tensioned to restore intact knee laxity at 90 degrees . Posterior cruciate ligament graft force, varus rotation, and tibial rotation were recorded before and after a grade 3 posterolateral corner injury. Testing was repeated with lateral collateral ligament, lateral collateral ligament plus popliteus tendon, and lateral collateral ligament plus popliteofibular ligament graft reconstructions; all grafts were tensioned to 30 N at 30 degrees with the tibia locked in neutral rotation.

RESULTS

All 3 posterolateral graft combinations rotated the tibia into slight valgus as the knee was taken through a passive range of motion. During the varus test, popliteus tendon and popliteofibular ligament reconstructions internally rotated the tibia from 1.5 degrees (0 degrees flexion) to approximately 12 degrees (45 degrees flexion). With an applied varus moment, mean varus rotations with a lateral collateral ligament graft were significantly less than those with the intact lateral collateral ligament beyond 0 degrees flexion; mean decreases ranged from 0.8 degrees (at 5 degrees flexion) to 5.6 degrees (at 120 degrees flexion). Addition of a popliteus tendon or popliteofibular ligament graft further reduced varus rotation (compared with a lateral collateral ligament graft) beyond 25 degrees of flexion; both grafts had equal effects. A lateral collateral ligament reconstruction alone restored posterior cruciate ligament graft forces to normal levels between 0 degrees and 100 degrees of flexion; lateral collateral ligament plus popliteus tendon and lateral collateral ligament plus popliteofibular ligament reconstructions reduced posterior cruciate ligament graft forces to below-normal levels-beyond 95 degrees and 85 degrees of flexion, respectively.

CONCLUSIONS

With a grade 3 posterolateral corner injury, popliteus tendon or popliteofibular ligament reconstructions are commonly performed to limit external tibial rotation; we found that they also limited varus rotation. With the graft tensioning protocols used in this study, all posterolateral graft combinations tested overconstrained varus rotation. Further studies with posterolateral reconstructions are required to better restore normal kinematics and provide more optimum load sharing between the PCL graft and posterolateral grafts.

CLINICAL RELEVANCE

A lower level of posterolateral graft tension, perhaps applied at a different flexion angle, may be indicated to better restore normal varus stability. The clinical implications of overconstraining varus rotation are unknown.

Authors+Show Affiliations

UCLA Department of Orthopaedic Surgery, Biomechanics Research Section, 1000 Veteran Ave, UCLA Rehabilitation Center, Room 21-67, Los Angeles, CA 90095-1759, USA. kmarkolf@mednet.ucla.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17581975

Citation

Markolf, Keith L., et al. "How Well Do Anatomical Reconstructions of the Posterolateral Corner Restore Varus Stability to the Posterior Cruciate Ligament-reconstructed Knee?" The American Journal of Sports Medicine, vol. 35, no. 7, 2007, pp. 1117-22.
Markolf KL, Graves BR, Sigward SM, et al. How well do anatomical reconstructions of the posterolateral corner restore varus stability to the posterior cruciate ligament-reconstructed knee? Am J Sports Med. 2007;35(7):1117-22.
Markolf, K. L., Graves, B. R., Sigward, S. M., Jackson, S. R., & McAllister, D. R. (2007). How well do anatomical reconstructions of the posterolateral corner restore varus stability to the posterior cruciate ligament-reconstructed knee? The American Journal of Sports Medicine, 35(7), 1117-22.
Markolf KL, et al. How Well Do Anatomical Reconstructions of the Posterolateral Corner Restore Varus Stability to the Posterior Cruciate Ligament-reconstructed Knee. Am J Sports Med. 2007;35(7):1117-22. PubMed PMID: 17581975.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - How well do anatomical reconstructions of the posterolateral corner restore varus stability to the posterior cruciate ligament-reconstructed knee? AU - Markolf,Keith L, AU - Graves,Benjamin R, AU - Sigward,Susan M, AU - Jackson,Steven R, AU - McAllister,David R, PY - 2007/6/22/pubmed PY - 2007/9/27/medline PY - 2007/6/22/entrez SP - 1117 EP - 22 JF - The American journal of sports medicine JO - Am J Sports Med VL - 35 IS - 7 N2 - BACKGROUND: With grade 3 posterolateral injuries of the knee, reconstructions of the lateral collateral ligament, popliteus tendon, and popliteofibular ligament are commonly performed in conjunction with a posterior cruciate ligament reconstruction to restore knee stability. HYPOTHESIS: A lateral collateral ligament reconstruction, alone or with a popliteus tendon or popliteofibular ligament reconstruction, will produce normal varus rotation patterns and restore posterior cruciate ligament graft forces to normal levels in response to an applied varus moment. STUDY DESIGN: Controlled laboratory study. METHODS: Forces in the native posterior cruciate ligament were recorded for 15 intact knees during passive extension from 120 degrees to 0 degrees with an applied 5 N .m varus moment. The posterior cruciate ligament was removed and reconstructed with a single bundle inlay graft tensioned to restore intact knee laxity at 90 degrees . Posterior cruciate ligament graft force, varus rotation, and tibial rotation were recorded before and after a grade 3 posterolateral corner injury. Testing was repeated with lateral collateral ligament, lateral collateral ligament plus popliteus tendon, and lateral collateral ligament plus popliteofibular ligament graft reconstructions; all grafts were tensioned to 30 N at 30 degrees with the tibia locked in neutral rotation. RESULTS: All 3 posterolateral graft combinations rotated the tibia into slight valgus as the knee was taken through a passive range of motion. During the varus test, popliteus tendon and popliteofibular ligament reconstructions internally rotated the tibia from 1.5 degrees (0 degrees flexion) to approximately 12 degrees (45 degrees flexion). With an applied varus moment, mean varus rotations with a lateral collateral ligament graft were significantly less than those with the intact lateral collateral ligament beyond 0 degrees flexion; mean decreases ranged from 0.8 degrees (at 5 degrees flexion) to 5.6 degrees (at 120 degrees flexion). Addition of a popliteus tendon or popliteofibular ligament graft further reduced varus rotation (compared with a lateral collateral ligament graft) beyond 25 degrees of flexion; both grafts had equal effects. A lateral collateral ligament reconstruction alone restored posterior cruciate ligament graft forces to normal levels between 0 degrees and 100 degrees of flexion; lateral collateral ligament plus popliteus tendon and lateral collateral ligament plus popliteofibular ligament reconstructions reduced posterior cruciate ligament graft forces to below-normal levels-beyond 95 degrees and 85 degrees of flexion, respectively. CONCLUSIONS: With a grade 3 posterolateral corner injury, popliteus tendon or popliteofibular ligament reconstructions are commonly performed to limit external tibial rotation; we found that they also limited varus rotation. With the graft tensioning protocols used in this study, all posterolateral graft combinations tested overconstrained varus rotation. Further studies with posterolateral reconstructions are required to better restore normal kinematics and provide more optimum load sharing between the PCL graft and posterolateral grafts. CLINICAL RELEVANCE: A lower level of posterolateral graft tension, perhaps applied at a different flexion angle, may be indicated to better restore normal varus stability. The clinical implications of overconstraining varus rotation are unknown. SN - 0363-5465 UR - https://www.unboundmedicine.com/medline/citation/17581975/How_well_do_anatomical_reconstructions_of_the_posterolateral_corner_restore_varus_stability_to_the_posterior_cruciate_ligament_reconstructed_knee L2 - http://journals.sagepub.com/doi/full/10.1177/0363546507299240?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -