Strains at the Medial Collateral Ligament and Tibiofemoral Contact Mechanics during High Tibial Osteotomy
Author(s):
Seitz A. (Germany)
,
Seitz A. (Germany)
Affiliations:
Nelitz M.
,
Nelitz M.
Affiliations:
Ignatius Anita
,
Ignatius Anita
Affiliations:
Dürselen L.
Dürselen L.
Affiliations:
ESSKA Academy. Seitz A. 05/09/18; 209577; P09-237 Topic: Biomechanics
Dr. Andreas Seitz
Dr. Andreas Seitz
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Abstract
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Objectives: There is evidence in literature, that an overtensioning of the superficial medial collateral ligament (sMCL) may lead to an undesired re-loading of the medial joint compartment [1]. Getting insight about the relationship between the strains acting at the anterior (epsant) and posterior (epspost) parts of the sMCL and the contact mechanics at the medial and lateral tibiofemoral joint could provide clinicians more information regarding partial or total release of the sMCL during open wedge high tibial osteotomy (OWO) procedures.

Methods: The medial and lateral tibial plateau of six human cadaveric knees (59.5±6.5yrs) was equipped with a calibrated pressure measurement system to measure the maximum tibiofemoral contact pressure (CPmax). Further, the anterior and posterior parts of the sMCL were equipped with two strain sensors at the level of the knee joint gap to assess epsant and epspost. The joints were placed in a material testing machine (Z010, Zwick GmbH, Germany) using a customized setup. Three loading cycles from 50N to 1kN were applied under knee extension, while the OWO angle was changed between 0°, 5° and 10°. The tests were conducted first with intact sMCL and subsequently with a released sMCL. (I) Wilcoxon testing was performed to compare epsant and epspost under OWO angles of 5° and 10°. (II) Further, the impact of an increased OWO angle on the medial and lateral CPmax was elaborated using a Friedman-test followed by a Wilcoxon test. (III) Comparisons of the lateral and medial CPmax under intact sMCL and released states at OWO angles of 0°, 5° and 10° were statistically investigated using a Wilcoxon test. p=0.05 was considered significant for all statistical analyses.

Results: (I) epsant and epspost were not different from each other under OWO angles of 5° (p=0.68) and 10° (p=0.08). Increasing the OWO angle from 5° to 10° led to a statistically significant strain increase at the anterior sMCL (p=0.04), but not at the posterior sMCL (p=0.07). (II) Friedman testing revealed no statistical difference in medial CPmax (p=0.31) while increasing the OWO angle from 0°-5°-10°. However, there was a tendency of an increasing medial CPmax. At the lateral compartment, we found a statistically significant decrease (p=0.04) in CPmax. Consecutive testing indicated no explicit changes (p=0.028). (III) Only a sMCL release resulted in a decrease of median medial CPmax under all OWO angles. At 10° the medial CPmax reduction was statistically significant (p=0.03), while laterally a significant decrease (p=0.03) of CPmax at an OWO angle of 0° was detected.

Conclusions: From a biomechanical point of view the present study corroborates and expands the findings from Agneskircher et al. [1]. Further it implies, that a release of the sMCL is strongly recommended in open wedge high tibial osteotomy. However, from a clinical standpoint, the individual ligamentary situation of the patient e.g. high laxity of the knee joint should also be taken into account as also described by Pape et al. [2].

Keywords:
open wedge high tibial osteotomy; HTO; MCL strain; medial collateral ligament; maximum contact pressure; tibiofemoral contact; knee extension; human; biomechanical study
Objectives: There is evidence in literature, that an overtensioning of the superficial medial collateral ligament (sMCL) may lead to an undesired re-loading of the medial joint compartment [1]. Getting insight about the relationship between the strains acting at the anterior (epsant) and posterior (epspost) parts of the sMCL and the contact mechanics at the medial and lateral tibiofemoral joint could provide clinicians more information regarding partial or total release of the sMCL during open wedge high tibial osteotomy (OWO) procedures.

Methods: The medial and lateral tibial plateau of six human cadaveric knees (59.5±6.5yrs) was equipped with a calibrated pressure measurement system to measure the maximum tibiofemoral contact pressure (CPmax). Further, the anterior and posterior parts of the sMCL were equipped with two strain sensors at the level of the knee joint gap to assess epsant and epspost. The joints were placed in a material testing machine (Z010, Zwick GmbH, Germany) using a customized setup. Three loading cycles from 50N to 1kN were applied under knee extension, while the OWO angle was changed between 0°, 5° and 10°. The tests were conducted first with intact sMCL and subsequently with a released sMCL. (I) Wilcoxon testing was performed to compare epsant and epspost under OWO angles of 5° and 10°. (II) Further, the impact of an increased OWO angle on the medial and lateral CPmax was elaborated using a Friedman-test followed by a Wilcoxon test. (III) Comparisons of the lateral and medial CPmax under intact sMCL and released states at OWO angles of 0°, 5° and 10° were statistically investigated using a Wilcoxon test. p=0.05 was considered significant for all statistical analyses.

Results: (I) epsant and epspost were not different from each other under OWO angles of 5° (p=0.68) and 10° (p=0.08). Increasing the OWO angle from 5° to 10° led to a statistically significant strain increase at the anterior sMCL (p=0.04), but not at the posterior sMCL (p=0.07). (II) Friedman testing revealed no statistical difference in medial CPmax (p=0.31) while increasing the OWO angle from 0°-5°-10°. However, there was a tendency of an increasing medial CPmax. At the lateral compartment, we found a statistically significant decrease (p=0.04) in CPmax. Consecutive testing indicated no explicit changes (p=0.028). (III) Only a sMCL release resulted in a decrease of median medial CPmax under all OWO angles. At 10° the medial CPmax reduction was statistically significant (p=0.03), while laterally a significant decrease (p=0.03) of CPmax at an OWO angle of 0° was detected.

Conclusions: From a biomechanical point of view the present study corroborates and expands the findings from Agneskircher et al. [1]. Further it implies, that a release of the sMCL is strongly recommended in open wedge high tibial osteotomy. However, from a clinical standpoint, the individual ligamentary situation of the patient e.g. high laxity of the knee joint should also be taken into account as also described by Pape et al. [2].

Keywords:
open wedge high tibial osteotomy; HTO; MCL strain; medial collateral ligament; maximum contact pressure; tibiofemoral contact; knee extension; human; biomechanical study
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