Good mid-term results with Charité lumbar TDR in 82% of 700 patients

Researchers reported very good results in old patients, but worse outcomes in obese patients from a series begun in 1999.

Issue: June 2005

NEW YORK — Korean surgeons who implanted more than 825 Charité lumbar total disc prostheses in more than 700 patients recently reported good surgical results in elderly patients.

They also successfully extended the indications for total disc replacement beyond the chronic lumbar back pain and disease cited by their initial patients to include those with combination of back pain and radicular leg pain.

Kang-jun Yoon, MD, who practices at St. Peter’s Hospital in Seoul, Korea, and his colleagues began treating patients with the Charité III lumbar total disc replacement (TDR) prosthesis in 1999. He presented five-year results from this growing series of cases at the Spine Arthroplasty Society Global Symposium on Motion Preservation Technology, held here.

“In order to get the good outcome in surgical approach, we should be aware of sympathetic chain damage located just medial to the psoas muscle,” Yoon told Orthopedics Today.

The vertebral body retractor shown here, developed by Kang-jun Yoon helped him and his fellow spine surgeons in Seoul implant the Charité total disc prosthesis in their patients.

Courtesy of Kang-jun Yoon

The data included results of 92 two-level and four three-level procedures, however surgeons did most of the TDR procedures at L4-5 or L5-S1. “There is no statistically significant difference between the one-level and multilevel applications,” said Yoon, who is affiliated with Hanllym University Hospital in Seoul.

Age not a factor

Interestingly, patient age did not affect surgical outcomes in this extremely large series, according to Yoon. Typical indications for the Charité III implant (DePuy Spine, a Johnson & Johnson company) do not include older patients with poor bone quality. But, when Yoon compared results in those patients younger than 65 years with those for a group of patients older than 65 years, he found “no significant difference between the two groups.” Ages ranged from 21 to 81 years, 44.8 years, mean.

Achieving such good TDR outcomes depended on thoroughly knowing the surgical anatomy, selecting the proper prosthesis size for the patient, and then implanting it in an optimal position, according to Yoon, who also cited good visualization as a key requirement. For example, when operating at L4-L5, ligating the iliolumbar vein helped him gain better control of the entire implantation process.

Yoon developed a vertebral body retractor (VBR), which enabled him to better see and remove sequestered or migrated disc material. VBR allowed him to “deimplant” one of the prostheses and re-implant it in a better position during the same procedure.

Yoon stressed that implanting the Charité device in the right position was critical to the outcome: “By using the VBR, we can change [the position] a couple of times without any damage to the vertebral bodies, without any damage of the endplate.” The VBR is also useful when revising a Charité implant, which he typically does through a lateral approach.

Should a prosthesis at L5-S1 need revising, he recommended removing the failed prosthesis using an approach opposite from that used during the original surgery. So, a device at L5-S1 implanted from the left would be revised using the VBR to decompress the L5-S1 nerve root and then removing the TDR implant from the right.

Yoon identified three poor prognosis factors for TDR, including malpositioned implants and cases where the endplate cartilage was damaged. Also, obese patients with over 40% body fat have suboptimal outcomes, he said.

For more information:

Yoon K, Hwange I, Ha S, et al. Artificial disc replacement with Charité III lumbar disc disease: 5 years follow up on 653 patients. Presented at the Spine Arthroplasty Society Global Symposium on Motion Preservation Technology. May 4-7, 2005. New York.