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.
“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.”
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.
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.
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.