Revision Acetabulum Treatment Options: Liner Exchange in Revision Hip Arthroplasty

David Hedden, M.D., FRCSC
Winnipeg, MB

Isolated acetabular liner exchange is most often employed when dealing with progressive pelvic osteolysis in the presence of well-fixed and orientated implants. A liner exchange may also be required with isolated femoral component revision. Retention of the cup potentially simplifies the revision and minimizes damage to pelvic bone stock.

Pelvic Osteolysis
Expansile osteolysis is the pattern usually seen with liner wear in cementless acetabular components1. Many of these patients are asymptomatic. Standard AP radiographs, although appropriate for assessing polyethylene wear, underestimate the extent of the osteolysis. Additional imaging such as oblique views and spiral CT have been shown to improve accuracy in assessing the extent of the disease1,2. Indications for revision include: 1) serial imaging demonstrating rapidly progressive osteolysis, 2) greater than 50% involvement of the shell circumference and 3) imminent liner wear through3.

The goal of liner exchange is to halt the progression of the osteolysis and allow the pelvic bone to heal. A stable, biomechanically sound reconstruction, avoiding recreation of the environment that led to the development of the osteolysis, is the key to success.

Preoperative Planning
Infection should be excluded with the usual preoperative investigation. The old operative reports need to be obtained and the appropriated vendor contacted to plan the reconstructive options. Equipment required will include instrumentation to remove the liner and test the cup stability. Locking mechanism replacement parts should be available if required. Trial liners and heads of various sizes (if available) are extremely useful to allow assessment of intra-operative stability. Replacement liners with various options (elevated rims and offset) and improved wear properties (cross-linked polyethylene) should be available. The head (if modular) should not be downsized to avoid increasing the risk of dislocation. Bone graft or appropriate substitutes should be available.

A back-up plan for complete acetabular revision and pelvic bone grafting if required is essential. Explant device, revision cups, cages and bulk grafts or tantalum augments need to be on standby.

Operative Technique
Surgical exposure may be either anterior or posterior although higher dislocation rates are reported with the use of the posterior approach4. If exposure is difficult, a trochanteric osteotomy (trochanteric slide with a cemented stem or an extended trochanteric osteotomy with an uncemented stem) can greatly improve visualization.

After wide exposure, the liner and all screws are removed and the cup position and stability are assessed. Trial components, if available, can now be used to assess stability, leg length and offset. The locking mechanism should be checked, particularly if a locking ring is employed as this may be damaged during liner removal and require replacement. The liner and modular head can then be inserted.

If the cup is malpositioned, if hip stability is poor, or if the cup size is too small to allow adequate head size and polyethylene thickness, the cup should be removed.

In the face of a damaged or poor locking mechanism, cementing of the liner into the shell can be performed. The stability of this construct has been extensively investigated and shown to be durable7,8. To optimize fixation, the liner should not be oversized and, if not designed for cementing, backside roughening is required. Cup modification is not required if screw holes are present5,6. This technique may also allow mismatching of cup and liner. Cementing of constrained liners and metal liners has been reported9,10.

Debridement and grafting of osteolytic lesion is controversial. There is evidence that replacement of the liner alone may arrest the progression of the disease with up to 1/3 of the lesions resolving whether or not bone grafting is performed11. Intuitively, however; it does make sense to debride and graft accessible lesions. Generally lesion in the dome and posterior column are accessible, either though screw holes or utilizing a trap door technique. Morselized allograft or bone substitutes may be used to fill the voids.

Results
In the appropriate setting, the results of isolated liner exchange have been excellent12.

However, a recent report from the Norwegian Arthroplasty Register noted higher further cup revision rates with liner exchange when compared with complete acetabular component revision13. This data suggests that the threshold for revision of well-fixed cups should be lowered. Modern cup removal techniques have significantly reduced the time required and bone damage caused by cup extraction14.

Summary
Isolated liner exchange is a reasonable option in dealing with liner wear and progressive pelvic osteolysis. Careful preoperative planning and intra-operative assessment is necessary to ensure optimal results. Instability is the most common reason for re-operation and the threshold for complete cup revision should be low.


References

  1. Chiang P.P., Burke D.W., Freiberg A.A., Rubash H.E. Osteolysis of the pelvis: evaluation and treatment. Clin Orthop Relat Res. 2003 Dec;(417):164-74. Review.
  2. Lombardi A.V. Jr, Berend K.R. Isolated acetabular liner exchange. J Am Acad Orthop Surg. 2008 May;16(5):243-8.
  3. Mehin R., Yuan X., Haydon C., Rorabeck C.H., Bourne R.B., McCalden R.W., MacDonald S.J. Retroacetabular osteolysis: when to operate? Clin Orthop Relat Res. 2004 Nov;(428):247-55
  4. Boucher H.R., Lynch C., Young A.M., Engh C.A. Jr, Engh C. Sr. Dislocation after polyethylene liner exchange in total hip arthroplasty. J Arthroplasty. 2003 Aug;18(5):654-7.
  5. Delanois R.E., Seyler T.M., Essner A., Schmidig G., Mont M.A. Cementation of a polyethylene liner into a metal shell. J Arthroplasty. 2007 Aug;22(5):732-7. Epub 2007 Apr 20.
  6. Mauerhan D.R., Peindl R.D., Coley E.R., Marshall A. Cementation of Polyethylene Liners Into Well-Fixed Metal Shells at the Time of Revision Total Hip Arthroplasty.  J Arthroplasty. 2008 Jan 18.
  7. Haft G.F., Heiner A.D., Dorr L.D., Brown T.D., Callaghan J.J. A biomechanical analysis of polyethylene liner cementation into a fixed metal acetabular shell. J Bone Joint Surg Am. 2003 Jun;85-A(6):1100-10.
  8. Bonner K.F., Delanois R.E. Harbach G., Bushelow M., Mont M.A. Cementation of a polyethylene liner into a metal shell. Factors related to mechanical stability. J Bone Joint Surg Am. 2002 Sep;84-A(9):1587-93
  9. Ebramzadeh E., Beaulé P.E., Culwell J.L., Amstutz H.C. Fixation strength of an all-metal acetabular component cemented into an acetabular shell: a biomechanical analysis. J Arthroplasty. 2004 Dec;19(8 Suppl 3):45-9.
  10. Mountney J., Garbuz D.S., Greidanus N.V., Masri B.A., Duncan C.P.  Cementing constrained acetabular liners in revision hip replacement: clinical and laboratory observations. Instr Course Lect. 2004;53:131-40. Review
  11. Maloney W.J., Paprosky W., Engh C.A., Rubash H. Surgical treatment of pelvic osteolysis. Clin Orthop Relat Res. 2001 Dec;(393):78-84
  12. O'Brien J.J., Burnett R.S., McCalden R.W., MacDonald S.J., Bourne R.B., Rorabeck C.H. Isolated liner exchange in revision total hip arthroplasty: clinical results using the direct lateral surgical approach. J Arthroplasty. 2004 Jun;19(4):414-23
  13. Lie S.A., Hallan G., Furnes O., Havelin L.I., Engesaeter L.B. Isolated acetabular liner exchange compared with complete acetabular component revision in revision of primary uncemented acetabular components: a study of 1649 revisions from the Norwegian Arthroplasty Register. J Bone Joint Surg Br. 2007 May;89(5):591-4.
  14. Mitchell P.A., Masri B.A., Garbuz D.S., Greidanus N.V., Wilson D., Duncan C.P. Removal of well-fixed, cementless, acetabular components in revision hip arthroplasty. J Bone Joint Surg Br. 2003 Sep;85(7):949-52.
     

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