Allograft, prosthesis use evolving in hip revisions for proximal femoral bone loss

U.K. surgeon says overall goal is to recreate the hip center, length, offset and to preserve host bone.

Proximal femoral bone loss that is severe enough to require revision femoral arthroplasty presents constant surgical challenges, but can be effectively managed by following basic surgical principles in conjunction with using proximal femoral allografts or replacements, according to a British orthopaedist.

In these cases, which are frequently multiply revised, “Patients should be managed in specialized units … dealt with in specialized ways with structural femoral allografts or custom or tumor prostheses,” Fares S. Haddad, MCh(Orth), FRCS(Orth), said.

During the 25th Annual Current Concepts in Joint Replacement Winter Meeting, Haddad reviewed the advantages and disadvantages of each approach and discussed their indications and key considerations, such as time to complete them in the operating room, rates of union, fracture and resorption, and costs.

For experts

“If we look at the survivorship in expert hands, whichever of these techniques you look at, you can see 85% survivorship at 5 to 15 years,” Haddad said in support of experienced surgeons using either option.

Furthermore, he emphasized that regardless of the approach used, “The plan needs to be to recreate the hip center, length and offset,” preserving distal host bone, the abductors and restoring joint stability through abductor attachment.

Whatever it takes, “Get secure distal fixation of the femur in order to facilitate early rehabilitation,” Haddad noted.

Allograft advantages

Although not readily available, Haddad mainly recommended using allografts for their potential to restore bone stock that is similar to the host femur. “If you can replace like with like, that is a method worthy of consideration,” he said.

Haddad cited the success Allan E. Gross, MD, FRCSC, of Mount Sinai Hospital in Toronto, has using proximal femoral allografts for massive proximal femoral bone loss.

This patient had a failed total hip replacement with considerable proximal femoral bone loss, proximal migration of the greater trochanter and breakage of multiple screws distally from the previous interlocking device.

The surgeons revised with a constrained acetabular component and cemented a proximal femoral replacement into the distal femur. Images: Haddad FS

Among the advantages of allografts he mentioned are their flexibility, capacity to unite or incorporate at the graft/distal bone junction, especially if biological augmentation was used, and the ease of reattaching the abductors and other soft tissues.

“[They] may facilitate later revision, particularly if you preserve and do not cement into the distal femur,” Haddad said.

Risks and rates

He said that allografts also have downsides: occasional poor quality, high cost and risk of disease transmission. Furthermore, they require two lengthy, simultaneous procedures in the operating room to prepare the femur and allograft.

“Patients face risks of nonunion, fracture and resorption,” sometimes coupled with more than 5 months of healing time, Haddad explained.

Despite his extensive allograft experience, Haddad said Gross has reported 6% nonunion, 8% dislocation and 4% infection rates.

“It is ideal for young patients with a good distal femur and no infection,” Haddad said. “But remember, the natural history is union, not incorporation.”

A total femur replacement with preservation of the bone as much as possible around the hip in order to maintain soft tissue attachments.

Prosthetic options

Proximal femoral replacement prostheses are indicated for the most severe cases of distal bone loss, particularly in elderly patients, according to Haddad. He said the advantages of using replacements are shortened surgical times, modular implants that aid in later conversions to total femoral replacements and early postoperative mobilization.

“It is not just salvage,” he noted.

Recent modifications of femoral replacements, including hydroxyapatite-coated collars and/or porous coatings, allowed new bone formation at the interface. “We get bone ingrowth with hydroxyapatite coating, which leads to distal load sharing,” Haddad said, noting most revision femoral procedures at his center involve proximal femoral implants, along with some total femurs and interlocking stems.

For more information:

• Fares S. Haddad, MCh(Orth), FRCS(Orth), can be reached at University College Hospital London, or Princess Grace Hospital, 42-52 Nottingham Place, London W1U 5NY, England; +44-0207-935-6083; e-mail: ortho@fareshaddad.net. He is a consultant to Smith & Nephew Orthopaedics.

Reference:

• Haddad FS. Massive bone loss: Heavy metal or proximal femoral allograft. #56. Presented at the 25th Annual Current Concepts in Joint Replacement Winter Meeting. Dec. 10-13, 2008. Orlando, U.S.A.