Patellofemoral contact pressures and lateral patellar translation after medial patellofemoral ligament reconstruction

Paul Beck, Nicholas A.T. Brown, Patrick E. Greis, Robert T. Burks

Research output: Contribution to journalArticle

98 Citations (Scopus)

Abstract

Background: Overtensioning of medial patellofemoral ligament reconstructions may lead to adverse surgical outcomes. Hypothesis: Increasing tension on a medial patellofemoral ligament graft will increase patellofemoral contact forces and decrease lateral patellar translation. Study Design: Controlled laboratory study. Methods: Patellofemoral contact pressures were measured in 8 fresh-frozen cadaveric knees before and after transection of the medial patellofemoral ligament and after a standardized reconstruction surgery. Contact pressures were measured at 3 knee angles (30°, 60°, and 90°) and under 3 levels of tension applied to the graft (2, 10, and 40 N). For each condition, patellar translation was measured at 30° of knee flexion as a 22-N lateral force was applied. Results: Graft tension of 2 N restored normal translation, but 10 N and 40 N significantly restricted motion (5.2 mm and 1.9 mm, respectively). Compared with the intact knee, medial patellofemoral contact pressures significantly increased (P <.05) when 40 N of tension was applied to the reconstruction. Medial contact pressures were restored to normal with 2 N of graft tension. Lateral patellar translation was significantly greater (P <.05) after the medial patellofemoral ligament was cut (16.3 mm) compared with intact (7.7 mm). Conclusion: Low (2-N) tension applied to a medial patellofemoral ligament reconstruction stabilized the patella and did not increase medial patellofemoral contact pressures. Higher loads (10 N and 40 N) progressively restricted lateral patellar translation and inappropriately redistributed patellofemoral contact pressures. Clinical Relevance: Overtensioning can be avoided by applying low loads to medial patellofemoral ligament reconstructions, which reestablished normal translation and patellofemoral contact pressures.

Original languageEnglish
Pages (from-to)1557-1563
Number of pages7
JournalAmerican Journal of Sports Medicine
Volume35
Issue number9
DOIs
Publication statusPublished - 2007
Externally publishedYes

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Ligaments
Pressure
Knee
Transplants
Patella

Cite this

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title = "Patellofemoral contact pressures and lateral patellar translation after medial patellofemoral ligament reconstruction",
abstract = "Background: Overtensioning of medial patellofemoral ligament reconstructions may lead to adverse surgical outcomes. Hypothesis: Increasing tension on a medial patellofemoral ligament graft will increase patellofemoral contact forces and decrease lateral patellar translation. Study Design: Controlled laboratory study. Methods: Patellofemoral contact pressures were measured in 8 fresh-frozen cadaveric knees before and after transection of the medial patellofemoral ligament and after a standardized reconstruction surgery. Contact pressures were measured at 3 knee angles (30°, 60°, and 90°) and under 3 levels of tension applied to the graft (2, 10, and 40 N). For each condition, patellar translation was measured at 30° of knee flexion as a 22-N lateral force was applied. Results: Graft tension of 2 N restored normal translation, but 10 N and 40 N significantly restricted motion (5.2 mm and 1.9 mm, respectively). Compared with the intact knee, medial patellofemoral contact pressures significantly increased (P <.05) when 40 N of tension was applied to the reconstruction. Medial contact pressures were restored to normal with 2 N of graft tension. Lateral patellar translation was significantly greater (P <.05) after the medial patellofemoral ligament was cut (16.3 mm) compared with intact (7.7 mm). Conclusion: Low (2-N) tension applied to a medial patellofemoral ligament reconstruction stabilized the patella and did not increase medial patellofemoral contact pressures. Higher loads (10 N and 40 N) progressively restricted lateral patellar translation and inappropriately redistributed patellofemoral contact pressures. Clinical Relevance: Overtensioning can be avoided by applying low loads to medial patellofemoral ligament reconstructions, which reestablished normal translation and patellofemoral contact pressures.",
keywords = "Contact pressures, MPFL reconstruction, Patellar instability, Patellofemoral injury",
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Patellofemoral contact pressures and lateral patellar translation after medial patellofemoral ligament reconstruction. / Beck, Paul; Brown, Nicholas A.T.; Greis, Patrick E.; Burks, Robert T.

In: American Journal of Sports Medicine, Vol. 35, No. 9, 2007, p. 1557-1563.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Patellofemoral contact pressures and lateral patellar translation after medial patellofemoral ligament reconstruction

AU - Beck, Paul

AU - Brown, Nicholas A.T.

AU - Greis, Patrick E.

AU - Burks, Robert T.

PY - 2007

Y1 - 2007

N2 - Background: Overtensioning of medial patellofemoral ligament reconstructions may lead to adverse surgical outcomes. Hypothesis: Increasing tension on a medial patellofemoral ligament graft will increase patellofemoral contact forces and decrease lateral patellar translation. Study Design: Controlled laboratory study. Methods: Patellofemoral contact pressures were measured in 8 fresh-frozen cadaveric knees before and after transection of the medial patellofemoral ligament and after a standardized reconstruction surgery. Contact pressures were measured at 3 knee angles (30°, 60°, and 90°) and under 3 levels of tension applied to the graft (2, 10, and 40 N). For each condition, patellar translation was measured at 30° of knee flexion as a 22-N lateral force was applied. Results: Graft tension of 2 N restored normal translation, but 10 N and 40 N significantly restricted motion (5.2 mm and 1.9 mm, respectively). Compared with the intact knee, medial patellofemoral contact pressures significantly increased (P <.05) when 40 N of tension was applied to the reconstruction. Medial contact pressures were restored to normal with 2 N of graft tension. Lateral patellar translation was significantly greater (P <.05) after the medial patellofemoral ligament was cut (16.3 mm) compared with intact (7.7 mm). Conclusion: Low (2-N) tension applied to a medial patellofemoral ligament reconstruction stabilized the patella and did not increase medial patellofemoral contact pressures. Higher loads (10 N and 40 N) progressively restricted lateral patellar translation and inappropriately redistributed patellofemoral contact pressures. Clinical Relevance: Overtensioning can be avoided by applying low loads to medial patellofemoral ligament reconstructions, which reestablished normal translation and patellofemoral contact pressures.

AB - Background: Overtensioning of medial patellofemoral ligament reconstructions may lead to adverse surgical outcomes. Hypothesis: Increasing tension on a medial patellofemoral ligament graft will increase patellofemoral contact forces and decrease lateral patellar translation. Study Design: Controlled laboratory study. Methods: Patellofemoral contact pressures were measured in 8 fresh-frozen cadaveric knees before and after transection of the medial patellofemoral ligament and after a standardized reconstruction surgery. Contact pressures were measured at 3 knee angles (30°, 60°, and 90°) and under 3 levels of tension applied to the graft (2, 10, and 40 N). For each condition, patellar translation was measured at 30° of knee flexion as a 22-N lateral force was applied. Results: Graft tension of 2 N restored normal translation, but 10 N and 40 N significantly restricted motion (5.2 mm and 1.9 mm, respectively). Compared with the intact knee, medial patellofemoral contact pressures significantly increased (P <.05) when 40 N of tension was applied to the reconstruction. Medial contact pressures were restored to normal with 2 N of graft tension. Lateral patellar translation was significantly greater (P <.05) after the medial patellofemoral ligament was cut (16.3 mm) compared with intact (7.7 mm). Conclusion: Low (2-N) tension applied to a medial patellofemoral ligament reconstruction stabilized the patella and did not increase medial patellofemoral contact pressures. Higher loads (10 N and 40 N) progressively restricted lateral patellar translation and inappropriately redistributed patellofemoral contact pressures. Clinical Relevance: Overtensioning can be avoided by applying low loads to medial patellofemoral ligament reconstructions, which reestablished normal translation and patellofemoral contact pressures.

KW - Contact pressures

KW - MPFL reconstruction

KW - Patellar instability

KW - Patellofemoral injury

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