1. Volume 91(Supplement 6):121-128
Sex Differences in Hip Morphology: Is Stem Modularity Effective for Total Hip Replacement?
by Francesco Traina, Manuela De Clerico, Federico Biondi, Federico Pilla, Enrico Tassinari, and Aldo Toni
J Bone Joint Surg Am
Volume 91(Supplement 6):
November 1, 2009
©2009 by The Journal of Bone and Joint Surgery, Inc.

2. Anatomic differences in hip morphology between men and women.
Anatomic differences in hip morphology between men and women. CCD = cervicodiaphyseal.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

3. Femoral offset (FO), which is the perpendicular distance from the center of rotation of the hip to the long axis of the femur.
Femoral offset (FO), which is the perpendicular distance from the center of rotation of the hip to the long axis of the femur.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

4. Schematic diagram showing hip mechanics.
Schematic diagram showing hip mechanics. The body weight lever arm (B) is the distance from the center of the femoral head to a vertical line through the symphysis pubis. The abductor lever arm (A) is the perpendicular distance from the center of the femoral head to a line drawn from the anterior superior iliac spine and tangential to the greater trochanter. Since B is greater than A, the abductor force required to balance the body in an upright position should be larger than the body weight.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

5. Diagram showing how, with monoblock stems, femoral offset (yellow arrows) is proportionally dependent on stem size while this is not true with modular neck stems.
Diagram showing how, with monoblock stems, femoral offset (yellow arrows) is proportionally dependent on stem size while this is not true with modular neck stems.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

6. Radiographs showing hip shapes that are difficult to restore with use of monoblock stems: large shaft, short neck, low offset (a); thin shaft, long neck, high offset (b); large shaft, short neck, high offset (c); and thin shaft, long neck, low offset (d).
Radiographs showing hip shapes that are difficult to restore with use of monoblock stems: large shaft, short neck, low offset (a); thin shaft, long neck, high offset (b); large shaft, short neck, high offset (c); and thin shaft, long neck, low offset (d).
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

7. Six different neck models were available: straight, varus-valgus (8°), anteverted-retroverted (8° and 15°), and the combination of 6° of varus and 4.5° of retroversion for the left and the right side.
Six different neck models were available: straight, varus-valgus (8°), anteverted-retroverted (8° and 15°), and the combination of 6° of varus and 4.5° of retroversion for the left and the right side.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

8. Diagram showing how implant offset (X) and neck length (Y) were calculated in each patient.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

9. Estimated Kaplan-Meier survival curve with 95% confidence intervals at eleven years for the 2131 modular neck prostheses.
Estimated Kaplan-Meier survival curve with 95% confidence intervals at eleven years for the 2131 modular neck prostheses.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

10. Comparison of estimated Kaplan-Meier survival curves at eleven years between 1080 prostheses implanted in women and 1051 prostheses implanted in men (p = 0.07).
Comparison of estimated Kaplan-Meier survival curves at eleven years between 1080 prostheses implanted in women and 1051 prostheses implanted in men (p = 0.07).
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

11. Distribution of modular neck lengths in men and women.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

12. An anteverted-retroverted (AR) neck was used more frequently in women than in men.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

13. Offset distribution correlated with stem size distribution in both women and men.
Offset distribution correlated with stem size distribution in both women and men. Offset in women was lower than that in men independent of stem size.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

14. Distribution of stem sizes in women and men.
Distribution of stem sizes in women and men. The implant used in this series is available in eight different sizes. Smaller stems were predominantly used in women.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

15. A patient with a small femoral canal and a long femoral neck.
A patient with a small femoral canal and a long femoral neck. Prosthetic modularity allowed restoration of proper anatomy, with avoidance of limb-length discrepancy and restoration of femoral offset.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

16. A patient with a large femoral canal and a short femoral neck, anatomy typical of older women.
A patient with a large femoral canal and a short femoral neck, anatomy typical of older women. In this case, a short neck of the femoral component allowed the surgeon to restore offset and lower-limb length independent of the large stem size required to fill the femoral canal and achieve good primary stability.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

17. a: A patient with a thin femoral shaft, a large femoral offset, and a short neck.
a: A patient with a thin femoral shaft, a large femoral offset, and a short neck. A monoblock prosthesis was used to achieve equal lower-limb lengths, and the offset was reduced. b: A patient with a large femoral shaft, a large offset, and a short neck. A modular neck prosthesis allowed the surgeon to restore hip offset, equalizing the lower-limb lengths. c: A patient with a thin femoral shaft, a long neck, and a low offset. A modular neck prosthesis allowed the surgeon to restore the hip anatomy.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

18. Diagram showing how a retroverted neck helps to reduce the risk of implant impingement and dislocation in hip adduction-external rotation.
Diagram showing how a retroverted neck helps to reduce the risk of implant impingement and dislocation in hip adduction-external rotation.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

19. A woman with a short straight modular neck, reducing lower-limb length and decreasing hip offset.
A woman with a short straight modular neck, reducing lower-limb length and decreasing hip offset. After dislocation (center), revision surgery was performed. A long retroverted neck was implanted in order to equalize the limb lengths, restore femoral offset, and avoid impingement in adduction and external rotation.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.

20. The relative risk of failure of modular implants in men and women.
The relative risk of failure of modular implants in men and women. Analysis of the demographic characteristics of the two populations under investigation in this study showed a lower risk of neck failure in women than in men. This lower risk of failure in women is due to an average lower implant offset (a), smaller stem size (b), and lower body weight (c). High offset, large stems, and high body weight increase the risk of modular neck failure.
Francesco Traina et al. J Bone Joint Surg Am 2009;91:
©2009 by The Journal of Bone and Joint Surgery, Inc.