Good results seen with highly porous acetabular implants in revision THA

Radiographic evidence of osseointegration occurred in all cases, and there were no complications in patients who underwent revision THAs.

Issue: November 2013

Highly porous, commercially pure, titanium matrix acetabular components are safe and efficacious in patients who underwent revision total hip arthroplasties, according to a study recently presented.

Perspective from Michael A. Mont, MD; and Kimona Issa, MD

“We prefer these highly porous jumbo cups for treatment of chronic discontinuity with major bone loss,” Morteza Meftah, MD, of Ranawat Orthopaedics, Hospital for Special Surgery (HSS) in New York City said. “Non-cemented custom cages, cemented cup/cage combination, or allograft are alternative choice if you want to treat Paprosky III or chronic pelvic discontinuity due to osteolysis. In our hands, Tritanium jumbo cups have reduced or eliminated the need for cup/cage combinations in such cases.”

He added, “The new porous Tritanium theoretically needs less bone (bleeding surface) to osteointegrate. This is important in major revision surgery when the bleeding surface is less than primary. We found that much less (around 30%) of bleeding bony surface is required for fixation with these implants.”

Jumbo cups

Researchers evaluated 24 patients who underwent revision total hip arthroplasty for major acetabular defects with Tritanium acetabular components (Stryker; Mahwah, NJ) between 2007 and 2010, and had a mean follow-up of 4 years. Most patients had a preoperative Paprosky classification of IIIA or IIIB with pelvic discontinuity. There were 10 men and 14 women, and patients had a mean age of 69 years.

This patient had a pelvic Paprosky type IIIB
and discontinuity and was revised with a
Tritanium jumbo cup.

Images: Meftah M

Meftah noted the Tritanium cups consist of trabecular metal implants, designed to resemble the trabecular bone structure. The trabecular implants are a highly porous 3-D surface utilizing commercially pure titanium (CPTi) powder technology.

“The jumbo cups are about 10 mm larger than the native socket, 58 mm or larger in women and 62 mm or larger in men,” Meftah said. “The use of these highly porous cups has theoretically improved osseointegration, due to a small percentage of the bleeding bone that is required.”

During the revision procedures, surgeons performed progressive reaming to obtain a bleeding bone interface. The interference fit between the anterior inferior iliac spine, pubis and ischium was achieved with the use of Tritanium jumbo cups. Bone graft was utilized before placement of the cup in the non-bleeding portions of the defect.

“It is a good idea to use a trial component to test the stability prior to the actual implant. Use the distraction technique in chronic discontinuity to obtain a wedge interface with 2-mm to 5-mm oversize jumbo cups and at least two to five screws to enhance fixation,” Meftah said. There were no cup/cages or wedges used in this series. Most patients required a cup diameter of 62 mm or bigger, according to Meftah.

Results

The investigators analyzed patients’ radiographic and clinical results, and extent of osseointegration. The WOMAC score was 30.5 points, the patient-administered questionnaire (PAQ) score was 25.2 and HSS score was 25.3, with Meftah noting that lower numbers for the WOMAC and PAQ are better and higher numbers for the HSS are better. All three clinical outcomes were good at final follow-up.

The abduction angle was 43° with an anteversion of 20°. Osseointegration occurred in all cups, with a minimum osseointegration incidence of 30% and maximum of 75%. “The most osseointegration was in zone I, which was superior, and zone VI, which was posterior,” Meftah said.

He added, “We had good patient satisfaction with significant improvement of pain. None of the patients had any complications, dislocations, infections or failure of osseointegration at final follow-up.” – by Renee Blisard Buddle

Reference:

Meftah M. Paper #13-3352. Presented at: EFORT Congress; June 5-8, 2013; Istanbul, Turkey.

For more information:

Morteza Meftah, MD, can be reached at Hospital for Special Surgery, 535 E. 70th St., New York, NY 10021; email: meftahm@hss.edu.
Disclosure: Meftah has no relevant financial disclosures.

Perspective

Michael A. Mont, MD; and Kimona Issa, MD

Management of acetabular bone loss and pelvic discontinuity in the setting of revision total hip arthroplasty (THA) can be challenging. In addition, reconstruction cages in patients who have Paprosky type 3A and 3B acetabular defects may have sub-optimal outcomes, according to studies by Paprosky and colleagues and Perka and colleagues. The new, highly porous metal implants (titanium or tantalum) were designed in an attempt to provide better primary stability, enhanced osseointegration and improved physiological stress distribution. These metals may mimic cancellous bone in appearance, structure and pore size, and be valuable in acetabular reconstruction. According to a systemic review by Banerjee and colleagues, these implants have provided excellent implant survivorship and clinical outcomes in the setting of primary THA and at a mean 5-year follow-up. However, there is a paucity of reports for revision procedures using these highly-porous titanium cups, according to Ramappa and colleagues.

Meftah and colleagues evaluated safety and efficacy of highly-porous titanium cups in 28 consecutive revision THAs in 26 patients who had major acetabular defects. They reported excellent implant survivorship with no incidence of loosening or cup migration at a mean follow-up of 4 years. Furthermore, the most osseointegration was seen in superior and posterior zones (zones I and VI) and the least osseointegration was seen in the medial and anterior zones (zone II and IV, respectively). These preliminary data by Meftah and colleagues are encouraging and should be used as a preliminary report for future studies. We commend the authors for their research and hope that this early work encourages others to better evaluate these implants with larger sample sizes and at longer follow-up.

References:

Paprosky W. Clin Orthop Relat Res. 2006.
Perka C. J Arthroplasty. 2001.
Banerjee S. Hip Int. 2013;doi: 10.530/hipint.5000064.
Ramappa M. Hip Int. 2009.

Michael A. Mont, MD; and Kimona Issa, MD

Rubin Institute for Advanced Orthopedics

Center for Joint Preservation and Replacement

Sinai Hospital of Baltimore

Baltimore

Disclosures: Mont receives royalties from Stryker; is a consultant for Janssen, Sage Products Inc., Salient Surgical, Stryker, OCSI and TissueGene; receives institutional support from Stryker and is on the Speakers Bureau for Sage Products Inc. Issa has no relevant financial disclosures.