Analysis reveals distinct cartilage, ACL wear in Saudi knees

Patients in Saudi Arabia require special implants, surgical techniques compared to Americans.

Issue: June 2006

CHICAGO — Researchers at the Hodge BioMotion Institute have identified patterns of knee osteoarthritis unique to Saudi patients, such as more anterior cartilage wear and a more prominent ACL wear anteriorly.

These findings came from an analysis of 32 knees of Saudi’s undergoing total knee arthroplasty (TKA). The study compared varus knee osteoarthritis (OA) patterns between the Arabian patients and a group of 106 North American knees using radiographic and intraoperative assessments. The analysis also included an intraoperative assessment of the intact, attenuated or ruptured ACLs.

Researchers presented these results at the American Academy of Orthopaedic Surgeons 73rd Annual Meeting, here.

Area of interest

The researchers sought to answer two key questions: What happens to knees that consistently perform deep flexion over a lifetime? and How does that affect the knee during total joint replacement?

“The relevance of this type of work is that, we go into cultures that are less of a standing culture and more of a kneeling culture, we need to have implants that can address their functional demands,” Melinda K. Harman, MS, one of the researchers, told Orthopedics Today.

Characteristics that researchers saw in the Saudi knees included anterior tibial-femoral contact with knee extension.

They saw more anterior-medial cartilage wear patterns of the proximal tibias in the Saudi knees, and wear area tended to be larger.

Images: Harman MK

Industry-wide interest has grown substantially regarding differences in ranges of motion (ROM), stabilities and cartilage and ligament wear patterns in all patient joint types, including those among Eastern cultures. As a result, a handful of orthopedic manufacturers have introduced some culture- and gender-appropriate knee and hip implants.

“That’s exactly what the implant manufacturers are pointing toward. How do we achieve this great ROM with knees?” Harman said.

Database comparison

W. Andrew Hodge, MD, performed the all TKA procedures for the study while at a medical center in Riyadh, Saudi Arabia. “These people have the highest knee arthritis [rates] anywhere in the world,” he said.

The researchers compared the Saudi Arabian patients’ data to intraoperative data for a group of American patients included in a similar study they published in 1998.

“[It] found that the types of activities that people were performing and how stable their knees were before surgery correlated well with the type of arthritis or the severity of arthritis we saw in their knees when the total joint [surgery] was actually done,” Harman said. This caused researchers to wonder about how different the wear patterns might be in people who do completely different activities than Americans, she said.

Anterior wear

In the latest research, which included special fluoroscopic studies of knee motion, the researchers found that cartilage wear covered 46% ± 19% of the tibial plateau in Saudi knees vs. 37% ± 16% in American knees. They also saw wear that was centered >5 mm anterior to the medial plateau in 34% of Saudi knees vs. 24% of American knees.

In both groups, cruciate ligament wear was more anterior, but it was more prominent in Saudi knees. They also detected total ACL deficiencies in 10% of Saudi knees compared to 25% of American knees, However, both groups had similarly severe posterior medial ACL wear.

“It was clear to me that the cruciate ligaments are actually longer and more lax than in both European and American populations,” Hodge told Orthopedics Today. The ligaments could be up to 30% longer in Saudi Arabians, he noted.

The trend toward anterior wear — typically a sign of instability in extension in conjunction with anterior tibial-femoral contact — may correspond to the chronic ligament stretching related to repeatedly performing high flexion activities, investigators said.

For the surgeries Hodge completed in Saudi Arabia, he sought an implant that allowed rotation and provided constraint combined with high flexion. “We went with the lateral constraint and high congruity that would allow rotation, but provide stability. It was good to see that in that population that particular concept provided enough stability in both full extension and flexion. So far, we’ve been pretty happy with it,” he said.

The researchers also recently concluded a similar study in conjunction with Hiromasa Miura, MD, Kyushu University in Fukuoka, Japan, which compared knee OA patterns in Japanese patients to those of Americans. Harman presented those results at the 79th Annual Congress of the Japanese Orthopaedic Association in Tokyo.

Researchers identified more varus deformity in the knees of American patients they studied.

More of the American knees were ACL-deficient compared to the Saudi ones.

For more information:
Harman MK, Banks SA, Hodge WA. Patterns of knee osteoarthritis in Arabian and American knees. #SE39. Presented at the American Academy of Orthopaedic Surgeons 73rd Annual Meeting. March 22-26, 2006. Chicago.