Acetabulum anatomy

1. Anatomy of the Acetabulum Dr Zahid Askar MBBS, FCPS(Ortho),FRCS( Tr & Ortho) Prof. of Orthopaedics Khyber Medical College Peshawer

2. Acetabulum  ( Gr :  ὀξίς ,  ὀξύβαφον ,  ὀξυβάφιον ) was a vinegar-cup, used by Greeks and Romans  placed on the dining-table .

3. The acetabulum is the point where the three components of the pelvis ( ilium ,  ischium , and pubis) meet.

4. The articular   Lunate Surface/DOME   The nonarticular A cetabular Fossa The inferior   Acetabular Notch . Anatomical restoration of the dome with concentric reduction of the femoral head beneath this dome is the goal of both operative and nonoperative treatment.

5. Embryology At 4 to 6 gestational weeks, the hip joint develops from the cartilaginous analogue            - By 7 weeks a cleft appears By 11 weeks, hip joint formation is mostly complete                    

6. At late gestation, femoral head grows more rapidly At birth the femoral head is < 50% covered Acetabulum continues to grow till 7 years with maximum growth is in the first 4 years.

7. ASIS AIIS Ischial Tuberosity Pubis Ischial Spine tendon of obturator internus m. internal pudendal a. internal pudendal v. pudendal n. nerve to obturator internus - 7 nerves:      - Sciatic Nerve      - Superior Gluteal Nerve      - Inferior Gluteal Nerve      - Internal Pudendal Nerve:      - Posterior Femoral Cutaneous Nerve      - Nerve to  Quadratus Femoris      - Nerve to Obturator Externus - 3 Vessel Sets:      - Superior Gluteal Artery & Vein      - Inferior Gluteal Artery & vein      - Internal Pudendal Artery & vein - 1 Muscle:      -  Piriformis

8. Forces Across The Hip Joint Walking upto 4 times BW Running upto 7 times BW Supported gait (w/ a walker or a cane) 2-3 BW Tuesday, December 16, 2014 8 Supine straight leg raising 2 times BW. Getting on & off bed pan 4 times BW Jogging and very fast walking both raised the forces to about 5.5 BW. Stumbling on one occasion caused magnitudes of 7.20 BW

9. 1. promontory of sacrum  2. ala of sacrum  3. arcuate line of ilium   4. pecten pubis ( pectineal line)   5. pubic crest   6. pubic symphysis

10. Iliopectineal line The iliopectineal line is the border of the iliopubic eminence. It can be defined as a compound structure of the arcuate line and pectineal line. With the sacral promontory, it makes up the linea terminalis   I liopubic eminence  (or  iliopectineal eminence ), which marks the point of union of theilium  and pubis

11. Ant. Column The two Columns Post. Column Acetabulum These two columns serve as struts, mechanically representing the coalescence of bony trabeculae along lines of stress

12. A nterior C olumn (white) Consists of Anterior half of the Iliac crest, The Iliac spines, Anterior half of the acetabulum , and the pubis.  ;

13. P osterior Column(red) Consists of: Ischium , the ischial spine, the posterior half of the acetabulum , the dense bone forming the sciatic notch.

14. The posterior column ends at its intersection with the anterior column at the top of the sciatic notch

15. Post Post

16. 3D Anatomy of the Innominate Bone Anterior Acetabulum Mean lateral inclination of 40 to 48 degrees Anteversion of 18 to 21 degrees

17. G. Maximus G. Medius G. Minimus piriformis Quadratus

18. Sciatic Nerve Superior/ Inf Gluteal N.V Bundle Corona mortis

19. Sciatic Nerve The largest and longest nerve in the body Arises from the lumber and sacral plexus Comes out of the pelvis through the Sciatic Notch Runs anterior (deep) to  Piriformis and lies posterior (superficial) to the short external rotators

20. Leaves pelvis through the greater sciatic notch along-with superior gluteal artery and vein It runs over the piriformis between the gluteus medius and minimus supplying these muscles Superior Gluteal Nerve Do not split gluteus medius more than 5-7 cm proximal to greater trochanter due to risk of denervating the muscle at risk during the lateral ( Hardinge ) approach to the hip

21. Leaves the pelvis through the greater sciatic foramen Runs underneath the piriformis Divides into muscular branches to supply the  Gluteus Maximus Inferior Gluteal Nerve

22. From the front

23. Vessels near the Acetabulum Schematic showing the excessively long screws on the quadrilateral intrapelvic surface relative to the iliac arterial system.

24. corona mortis "corona mortis" or crown of death Chances of significant hemorrhage An anastomosis between the obturator and the external iliac or inferior epigastric arteries or veins. Located behind the superior pubic ramus at a variable distance from the symphysis pubis (range 40-96 mm). 60% had a large diameter (>3 mm)

25. “We carried out forty cadaver dissections (80 hemi-pelvises) through the ilioinguinal approach. A vascular anastomosis was found in 83% of specimens. Of these, 60% had a large diameter (>3 mm) channel along the posterior aspect of the superior pubic ramus ” “In clinical practice, however, 492 anterior approaches (to the best of our knowledge the largest series described) have been carried out over the last 15 years by the senior author (MB) and only five of these problematic vessels were discovered, and in only two cases was there troublesome bleeding . “ Darmanis S, Lewis A,  Mansoor A,  Bircher M Corona mortis: an anatomical study with clinical implications in approaches to the pelvis and acetabulum . Clin Anat .  2007 May;20(4):433-9.

26. Where to put the screws???

27. Thank You !!!