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An in-vitro biomechanical study of different fixation techniques for the extended trochanteric osteotomy in revision THA.

Zhu Z, Ding H, Shao H, Zhou Y, Wang G - J Orthop Surg Res (2013)

Bottom Line: Ten cadaveric femurs were chosen in this study.The tension to the greater trochanter was from 0 to 500N in vertical and lateral direction, respectively.The translation and rotation of the greater trochanter with respect to the bony bed were captured by an optical tracking system.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Tsinghua University, Beijing, China.

ABSTRACT

Background: The wire fixation and the cable grip fixation have been developed for the extended trochanteric osteotomy (ETO) in the revision of total hip arthroplasty (THA). Many studies reported the postoperative performance of the patients, but with little quantitative biomechanical comparison of the two fixation systems.

Methods: An in-vitro testing approach was designed to record the loosening between the femoral bed and the greater trochanter after fixations. Ten cadaveric femurs were chosen in this study. Each femur underwent the THA, revision by ETO and fixations. The tension to the greater trochanter was from 0 to 500N in vertical and lateral direction, respectively. The translation and rotation of the greater trochanter with respect to the bony bed were captured by an optical tracking system.

Results: In the vertical tension tests, the overall translation of the greater trochanter was observed 0.4 mm in the cable fixations and 7.0 mm in the wire fixations. In the lateral tension tests, the overall motion of the greater trochanter was 2.0 mm and 1.2° in the cable fixations, while it was 6.2 mm and 5.3° in the wire fixations. The result was significantly different between the two fixation systems.

Conclusions: The stability of the proximal femur after ETO using different fixations in the revision THA was investigated. The cable grip fixation was significantly more stable than the wire fixation.

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The local coordinate system of the femoral bed: the origin was 6.5 cm from horizontal cut; The X-Y plane was decided by all the 6 markers on the bone. The 6 DOF of motion of the extended greater trochanter in one test was shown in the vertical tension test (a) and the lateral tension test (b).
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Figure 4: The local coordinate system of the femoral bed: the origin was 6.5 cm from horizontal cut; The X-Y plane was decided by all the 6 markers on the bone. The 6 DOF of motion of the extended greater trochanter in one test was shown in the vertical tension test (a) and the lateral tension test (b).

Mentions: The motion of the greater trochanter relative to the femoral bed was calculated in translations and rotations {tx,ty,tz,α,β,γ} [23]. The deformation of each tracked object was observed less than 0.5 mm, so the femoral bed and the greater trochanter were approximately rigid bodies. During data processing, all motion data was presented in the local coordinate system (O-XYZ) of the femoral bed (Figure 4). The origin (O) of the femoral bed was 6.5 cm from the horizontal cut on the line AC (Figure 3(a)). The Y axis pointed to the marker C. The X-Y plane was decided by all the six markers (from A to F) on the bone to approximate the coronal plane using the least square method. The X axis pointed to the anterior side of the femur. The Z axis was decided using the right-handed coordinate system definition. The point P1 on the proximal end of the extended greater trochanter was 13cm from the horizontal cut on the line DF (Figure 3(a)).


An in-vitro biomechanical study of different fixation techniques for the extended trochanteric osteotomy in revision THA.

Zhu Z, Ding H, Shao H, Zhou Y, Wang G - J Orthop Surg Res (2013)

The local coordinate system of the femoral bed: the origin was 6.5 cm from horizontal cut; The X-Y plane was decided by all the 6 markers on the bone. The 6 DOF of motion of the extended greater trochanter in one test was shown in the vertical tension test (a) and the lateral tension test (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3643827&req=5

Figure 4: The local coordinate system of the femoral bed: the origin was 6.5 cm from horizontal cut; The X-Y plane was decided by all the 6 markers on the bone. The 6 DOF of motion of the extended greater trochanter in one test was shown in the vertical tension test (a) and the lateral tension test (b).
Mentions: The motion of the greater trochanter relative to the femoral bed was calculated in translations and rotations {tx,ty,tz,α,β,γ} [23]. The deformation of each tracked object was observed less than 0.5 mm, so the femoral bed and the greater trochanter were approximately rigid bodies. During data processing, all motion data was presented in the local coordinate system (O-XYZ) of the femoral bed (Figure 4). The origin (O) of the femoral bed was 6.5 cm from the horizontal cut on the line AC (Figure 3(a)). The Y axis pointed to the marker C. The X-Y plane was decided by all the six markers (from A to F) on the bone to approximate the coronal plane using the least square method. The X axis pointed to the anterior side of the femur. The Z axis was decided using the right-handed coordinate system definition. The point P1 on the proximal end of the extended greater trochanter was 13cm from the horizontal cut on the line DF (Figure 3(a)).

Bottom Line: Ten cadaveric femurs were chosen in this study.The tension to the greater trochanter was from 0 to 500N in vertical and lateral direction, respectively.The translation and rotation of the greater trochanter with respect to the bony bed were captured by an optical tracking system.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Tsinghua University, Beijing, China.

ABSTRACT

Background: The wire fixation and the cable grip fixation have been developed for the extended trochanteric osteotomy (ETO) in the revision of total hip arthroplasty (THA). Many studies reported the postoperative performance of the patients, but with little quantitative biomechanical comparison of the two fixation systems.

Methods: An in-vitro testing approach was designed to record the loosening between the femoral bed and the greater trochanter after fixations. Ten cadaveric femurs were chosen in this study. Each femur underwent the THA, revision by ETO and fixations. The tension to the greater trochanter was from 0 to 500N in vertical and lateral direction, respectively. The translation and rotation of the greater trochanter with respect to the bony bed were captured by an optical tracking system.

Results: In the vertical tension tests, the overall translation of the greater trochanter was observed 0.4 mm in the cable fixations and 7.0 mm in the wire fixations. In the lateral tension tests, the overall motion of the greater trochanter was 2.0 mm and 1.2° in the cable fixations, while it was 6.2 mm and 5.3° in the wire fixations. The result was significantly different between the two fixation systems.

Conclusions: The stability of the proximal femur after ETO using different fixations in the revision THA was investigated. The cable grip fixation was significantly more stable than the wire fixation.

Show MeSH
Related in: MedlinePlus