THR: Cementless Acetabular Component - Wheeless' Textbook of Orthopaedics

- See: Total Hip Replacement Menu:
- acetabular component revision:
- operative considerations for hip dyplasia
- protrusio
- reaming technique:
- component insertion:
- component position:
- screw placement:
- bone grafting for acetabular defects:
- acetabular component revision:

- Discussion:
- design of acetabular components: (see surface coating)
- acetabular component loosening:
- osteolysis
- normal bone ingrowth:
- generally for bone ingrowth to occur, component must lie with 50 micrometers of the acetabulum, and have enough mechanical stability (less than 40 to
                  50 micrometers) inorder for host bone ingrowht to occur;
- as noted by RD Bloebaum et al 1997, bone ingrowth into the component averages only 12%, eventhough 84% of cup surface
                  was in contact with periprosthetic bone;
- bone ingrowth was found to be uniform in all zones, most likely due to the uniform distribution of stresses from the metal backing;
            - ref: Histologic and xray assessment of well functioning porous coated acetabular components: A human postmortem retrieval study.
                      CA Engh. JBJS. Vol 75-A. 1993. p 814-824.
    - acetabular offset and latealized acetabular liner:
- this may induce additional torque and shear at the metal osseous surface leading to loosening;
- references:
- Offset acetabular components introduce torsion on the implant and may increase the risk of fixation failure.
- Histological and radiographic assessment of well functioning porous-coated acetabular components. A human postmortem retrieval study.
- Acetabular Revision With a 7-mm Lateral Offset Component Inserted Without Cement in Patients Who Have Acetabular Deficiency.
- Midterm Radiographic Comparison of Cementless Acetabular Shells Containing Lateralized and Nonlateralized Liners.
- types of press fit surfaces:
    - acetabular liner / femoral head size:
- as pointed out by M. Jasty et al (JBJS 1997), the thickness of the polyethylene component is especially important in metal backed press fit components;
- w/ smaller acetabular components consider using a 26 mm rather than a 28 mm head in order to better prevent osteolysis;
- as noted by Cobb et al 1997, there was no indication of early loosening of elevated rim liners at 5 years as compared to neutral liners;
- optimally orthopaedists should be able to choose specific liners based on long term data of liner survival;
- Hylamer liner from DePuy is associated w/ early signs of wear and osteolytic changes.
- references:
- Effect of femoral head size on wear of the polyethylene acetabular component.
- Size of the femoral head and acetabular revision in total hip-replacement arthroplasty.
- Effect of the elevated rim acetabular liner on loosening after THR. TK Cobb et al. JBJS. Vol 79-A. No 9. Sep 1997. p 1361.
- Elevated rim acetabular components. Effect on range of motion and stability in THR. RJ Krushell et al. J. Arthroplasty. Vol 6. 1991. p S53-S58.
- Complications of THR associated w/ use of an acetabular component with a Hylamer liner. BJ Livingston MD et al. JBJS Vol 79-A No 10. Oct 1997.
- Impingement and loosening of the long posterior wall acetabular component. DW Murray. JBJS Vol 74-B. 1992. p 377-379.
- outcomes:
- as noted by Bohm and Bosche 1998, the 11 year survivorship of press fit Harris Galante components was 97.7%;
- there was only one case of osteolysis in this study;
- mean postoperative inclination was 42 deg;
- holes in the acetabular component did not correlate with pelvic osteolysis;
- references:
- Acetabular augmentation in primary and revision total hip arthroplasty with cementless prostheses.
- Comparison of porous-threaded and smooth-threaded acetabular components of identical design. Two- to four-year results.
- Comparison of in vivo cementless acetabular fixation.
- A preliminary report of the use of a cementless acetabular component with a cemented femoral component.
- Metal-backed acetabular cups in total hip arthroplasty.
- Further follow-up on socket fixation using a metal-backed acetabular component for total hip replacement. A minimum ten-year follow-up study.
- Range of motion caused by design of the total hip prosthesis.
- Hip Replacement with a Threaded Acetabular Cup. A Follow-up Study.
- Total hip replacement with insertion of an acetabular component without cement and a femoral component with cement. Four to seven-year results.
- Early failure of acetabular components inserted without cement after previous pelvic irradiation.
- Cementless press-fit cup. Principles, experimental data, and three-year follow-up study.
- Development and first experience with an uncemented press-fit cup.
- Postmortem Analysis of Bone Ingrowth into Porous Coated Acetabular Components. RD Bloebaum PhD  JBJS Vol 79-A, No 7, Jul. 1997. p 1013.
- Histo and xray assessment of well f(x)ing porous coated acetabular components: A human postmortem retrieval study.  JBJS Vol 75-A. 1993. p 814-824.
- Fixation of acetabular cups w/o cement in THR. A comparison of 3 different implant surfaces at a minimum duration of follow up of 5 yrs.  JBJS. Vol 80-A. No 8. Aug 1998.
- Survival analysis of the Harris Galante I acetabular cup. P. Bohm and R. Bosche. JBJS. Vol 80-B. No 3. May 1998. p 396
- Fixation of the acetabular component: the case for cementless bone ingrowth modular sockets. LD Dorr. J. Arthroplasty. Vol 11. 1996.

- Radiographic Evaluation:
- preop acetabular x-ray evaluation:
- protrusio:
- references:
- Radiographic measurements in protrusio acetabuli.
- bone grafting for acetabular defects:
- references:
- The acetabular teardrop and its relevance to acetabular migration.
- Bone-grafting in total hip replacement for acetabular protrusion.
- postop radiographic evaluation:
- acetabular component loosening:
- component position;
- polyethylene wear:
- osteolysis:
- references:
- Severe Osteolysis of the Pelvis in Association with Acetabular Replacement without Cement.
- The relationship between design, position, and articular wear of acetabular components inserted w/o cement and development of pelvic osteolysis.
- The relationship between design, position, and articular wear of acetabular components inserted w/o cement and development of pelvic osteolysis.
- Are cementless acetabular components the cause of excess wear and osteolysis in total hip arthroplasty.

- Complications:
- acetabular fracture:
- acetabuli should not be underreamed by more than 1 mm, especially in osteoporotic bone;
- underreaming of the acetabulum by two milimeters may result in frx in 20-25% of cases;
- when intra-operative fracture is recognized intra-operatively, then augment the component with as many acetabular screws as possible;
- acetabular component loosening:
- dislocation
- screw insertion injuries;
- osteolysis
- protrusio:
- references:
- Periprosthetic fractures of the acetabulum during and followingg total hip arthroplasty. JJ Callaghan. JBJS Vol 79-A. No 9. Sep 1997. p 1416.
- Fracture of the acetabulum during insertion of an oversized hemispherical component.
- The elevated-rim acetabular liner in total hip arthroplasty: relationship to postoperative dislocation.

Secondary total hip replacement after fractures of the femoral neck.

Current status of acetabular fixation in primary total hip arthroplasty.

Failure of the Mecring screw-ring acetabular component in total hip arthroplasty. A three to seven-year follow-up study.

The definition and measurement of acetabular orientation. DW Murray. JBJS. Vol 75(2)-B. 1993. p 228-232.

Cementless Acetabular Fixation at Fifteen Years. A Comparison with the Same Surgeon's Results Following Acetabular Fixation with Cement.