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Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_8 | Pages 87 - 87
1 May 2016
Kataoka T Iizawa N Mori A Oshima Y Matsui S Takai S
Full Access

Introduction

Many factors can influence post-operative kinematics after total knee arthroplasty (TKA). These factors include intraoperative surgical conditions such as ligament release or quantity of bone resection as well as differences in implant design. Release of the medial collateral ligament (MCL) is commonly performed to allow correction of varus knee. Precise biomechanical knowledge of the individual components of the MCL is critical for proper MCL release during TKA. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on valgus and rotatory stability in TKA.

Materials and Methods

This study used six fresh-frozen cadaveric knees with intact cruciate ligaments. All TKA procedures were performed by the same surgeon using CR-TKA with a CT-free navigation system. Each knee was tested at 0°, 20°, 30°, 60°, and 90° of flexion. One sequential sectioning sequence was performed on each knee, beginning with an intact knee (S0), and thereafter femoral arthroplasty only (S1), tibial arthroplasty (S2), release of the dMCL (S3), and finally, release of the POL (S4). The same examiner applied all external load of 10 N-m valgus and a 5 N-m internal and external rotation torque at each flexion angle for the each cutting state. All data were analyzed statistically using one-way ANOVA and we investigated the correlation between the medial gap and the rotation angle. A significant difference was determined to be present for P < .05.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_8 | Pages 48 - 48
1 May 2016
Iizawa N Mori A Majima T Kawaji H Matsui S Takai S
Full Access

Precise biomechanical knowledge of individual components of the MCL is critical for proper MCL release during TKA. This study was to define the influences of the deep MCL and the POL on valgus and rotatory stability in TKA using six cadaveric knees with sequential sectioning sequence. A CT-free navigation system monitored motion after application of valgus loads and internal and external rotation torques at 0°, 20°, 30°, 60°, and 90°of knee flexion. Significant increases of rotatory instability were seen on release of the deep MCL. And, rotatory instability further increased after release of the POL. Surgical approach of retaining the deep MCL and POL has a possibility to improve the outcome after primary TKA.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_8 | Pages 47 - 47
1 May 2016
Iizawa N Mori A Oshima Y Matsui S Kataoka T Takai S
Full Access

Introduction

Many factors can influence post-operative kinematics after total knee arthroplasty (TKA). These factors include intraoperative surgical conditions such as ligament release or quantity of bone resection as well as differences in implant design. Release of the medial collateral ligament (MCL) is commonly performed to allow correction of varus knee. Precise biomechanical knowledge of the individual components of the MCL is critical for proper MCL release during TKA. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on kinematics in TKA.

Materials and Methods

This study used six fresh-frozen cadaveric knees with intact cruciate ligaments. All TKA procedures were performed by the same surgeon using CR-TKA with a CT-free navigation system. Each knee was tested at 0°, 20°, 30°, 60°, and 90° of flexion. One sequential sectioning sequence was performed on each knee, beginning with femoral arthroplasty only (S1), and thereafter sequentially; medial half tibial resection with spacer (S2), ACL cut (S3), tibial arthroplasty (S4), release of the dMCL (S5), and finally, release of the POL (S6). The same examiner applied all external loads of 10 N-m valgus and 5 N-m internal and external rotation torques at each flexion angle and for each cut state. The AP locations of medial and lateral condyles were determined as the lowest point on each femoral condyle. All data were analyzed statistically using paired t-test. A significant difference was determined to be present for P < .05.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_2 | Pages 58 - 58
1 Jan 2016
Iizawa N Mori A Matsui S Oba R Satake Y Takai S
Full Access

Introduction

Many factors can influence post-operative kinematics after total knee arthroplasty (TKA). These factors include intraoperative surgical conditions such as ligament release or quantity of bone resection as well as differences in implant design. Release of the medial collateral ligament (MCL) is commonly performed to allow correction of varus knee. Precise biomechanical knowledge of the individual components of the MCL is critical for proper MCL release during TKA. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on valgus and rotatory stability in TKA.

Materials and Methods

This study used six fresh-frozen cadaveric knees with intact cruciate ligaments. All TKA procedures were performed by the same surgeon using CR-TKA with a CT-free navigation system. Each knee was tested at 0°, 20°, 30°, 60°, and 90° of flexion. One sequential sectioning sequence was performed on each knee, beginning with femoral arthroplasty only (S1), and thereafter sequentially, medial half tibial resection with spacer (S2), ACL cut (S3), tibial arthroplasty (S4), release of the dMCL (S5), and finally, release of the POL (S6). The same examiner applied all external loads of 10 N-m valgus and 5 N-m internal and external rotation torques at each flexion angle and for each cut state. All data were analyzed statistically using two-way ANOVA and paired t-test. A significant difference was determined to be present for P < .05.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 354 - 354
1 Dec 2013
Iizawa N Mori A Matsui S Oba R Ito T Takai S
Full Access

Purpose:

Biomechanical knowledge of the medial collateral ligament (MCL) is important for MCL release during knee arthroplasty. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on valgus and rotatory stability in knee arthroplasty.

Methods:

Six cadaveric knees were divided into 2 groups with unique sequential sectioning sequences of the dMCL and the POL. Group A (n = 2) first received femoral arthroplasty only, and thereafter sequentially received medial half tibial resection with spacer, ACL cut, dMCL cut, POL cut, and finally tibial arthroplasty. Group B (n = 4) first received femoral arthroplasty only, and thereafter sequentially received medial half tibial resection with spacer, ACL cut, tibial arthroplasty, dMCL cut, and finally, POL cut. A CT-free navigation system monitored motion after application of valgus loads (10 N-m) and internal and external rotation torques (5 N-m) at 0°, 20°, 30°, 60°, and 90°of knee flexion.


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_IV | Pages 419 - 419
1 Apr 2004
Tomita N Sakuramoto Mori A Onmori N Aoyama E
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Introduction: Our previous study1) suggested that addition of vitamin E(dl-α-Tocopheror) at the grain boundarie of UHMWPE dramatically prevented delamination destruction. This study examined the microscopic and macroscopic mechanical performances of the vitamin E added UHMWPE by using micro indenter testing and high-speed tensile testing.

Methods: UHMWPE powder (GUR1050, Ticona) was directly molded at 10MPa with and without Vitamin E (DL-α-Tocopherol, Wako Pure Chemical Industries. Ltd.) addition. The Vitamin E was compounded to UHMWPE powder in air using a blend mixer. Gamma-ray irradiation (a dose of 25kGy) was performed on each group at room temperature in air, and then, the specimens were aged at 80°C for 23 days. Hardness at grain boundary was measured using dynamic micro indentation testing machine (Shimadzu Dynamic Ultra Micro Hardness Tester, DUH-200) where triangular-pyramid indenter with 115 degrees point angle was used. High-speed tensile testing was performed to dumbbell-shaped test specimens (JIS K7113 No.2, thickness=3mm) with crosshead speed of 1000 mm/min (corresponding strain rates : 0.4/s).

Results and discussion: Results of micro indenter test showed that the dynamic hardness at grain boundary was higher than that in grain and was increased by gamma irradiation. This hardening at grain boundary was reduced by adding vitamin E. Results of high-speed tensile test showed no significant change in Young’s modulus and strength by the vitamin-E addition. However, the elongation at break was increased to more than 10 times as much as that of virgin (aged) UHMWPE.

These results suggest that mechanism for the prevention of delamination by vitamin-E-addition is caused by increased elongation at break by increasing toughness at grain boundary. The addition of vitamin E is a simple and extremely effective method to prevent destruction of UHMWPE joint component.