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Acetabular impaction grafting with proper fixation successful with less than 50% host bone contact
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ORLANDO, Fla., USA — Impaction grafting with a cementless hemispherical porous-coated acetabular cup is well-established in revision surgery, with outcomes likely to improve in the future as biological stimulation widens the indications for bone allograft and synthetic impaction allografting, according to an orthopaedic surgeon from London.
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“The goals, particularly for this technique, are a stable acetabular bed, secure durable prosthetic fixation, getting your orientation right and restoring the hip center and biomechanics — and of course trying to restore bone stock whenever possible,” Prof. Fares S. Haddad, MB, FRCS, an Orthopaedics Today Europe Editorial Board member, said at the Current Concepts in Joint Replacement 2010 Winter Meeting, here.
Access, soft tissue scarring, bone loss and poor bone biology are the challenges associated with impaction grafting, Haddad said, noting that the acetabular side is much more complex then the femoral side.
Stability is key
Indications for the technique, according to Haddad, include Paprosky types 1 and 2 defects and Gross types 1, 2 and 3; contraindications include severe osteopenia, osteonecrosis, metabolic bone disorders, tumors and pelvic dissociation.
Haddad presented a series of 62 revision total hip arthroplasty (THA) patients with 5-year follow-up, with the majority of patients undergoing revision of cemented implants for aseptic loosening. Host bone contact was less than 50% in 42 patients. No immediate failures occurred; the center of rotation was restored in a majority of the cases; and the average postoperative Harris Hip score was 88.
“The key finding in this series is that we set out to address the issue of whether a 50% or more host bone contact, or the strength of fixation, hence the importance of early micromotion, was more important.” Haddad told Orthopaedics Today Europe. “We found that stability of the fixation is the key finding and that, provided there is some host bone contact — particularly in the posterior wall — we would expect this technique to be successful with less than 50% contact.”
Biological stimulation
In another study in a goat model, Haddad and colleagues investigated the effects of stem cells on bone growth on the acetabular component and evaluated the amount of fibrous tissue and bone formation at the interface. With stem cells, the team observed less fibrous tissue and more bone apposition and formation.
“More importantly, we see 30% greater bone formation,” he said.
According to Haddad, his team’s bone marrow work has been experimental so far, but is now being translated to the clinical setting. They feel it will enhance bone ingrowth into acetabular and hopefully femoral components to further expand the indications for this impaction grafting technique.
“The synthetic option is an attractive one due to the lack of allografts and ultimately we would hope to identify idealized combinations of synthetic and allograft tissue so as to limit the need for allograft, which is sometimes difficult to source,” Haddad said. – by Thomas M. Springer
Reference:
- Haddad FS. The role of impaction grafting: An EU phenomenon. Paper #62. Presented at the Current Concepts in Joint Replacement 2010 Winter Meeting. December 8-11, 2010. Orlando, Fla., USA.
- Prof. Fares S. Haddad, MB, FRCS, can be reached at Princess Grace Hospital, 42 Nottingham Place, London W1U 5NY, United Kingdom; +44 20 79356083; e-mail: fareshaddad@aol.com.
- Disclosure: Haddad is a paid consultant to Finsbury, Mitek, Smith & Nephew and Stryker. He also receives royalties from and is a panel member for Smith & Nephew.
