Leg Bone Misalignment at Knee Linked to Severe Arthritis

Patients undergoing knee surgery are especially vulnerable to developing degenerative arthritis if the leg bones are not properly aligned above and below the knee, according to researchers at Duke University.

Bow-leggedness can also lead to serious problems for knee surgery patients, according to the researchers. They suggest that physicians should closely monitor all young people who undergo reconstructive knee surgery to ensure that the leg bones stay in proper alignment, and in some cases surgically correct the bowleggedness. Such preventive measures could prevent future development of severe arthritis of the knee.

"Even a relatively small malalignment in normal knees can cause dramatic alterations in the pressures within the knee joint, and this negative effect can be greatly magnified if the cartilage within the knee has been damaged," said Dr. Joseph Guettler, orthopedic surgeon and sports medicine fellow at Duke. "With early recognition and intervention of the malalignment, we can perhaps prevent the development of serious osteoarthritis from occurring in the future."

Researchers developed a study to analyze the effects of malalignment on the knee joints of patients who had suffered damage to the cartilage within the knee. Specifically, they looked at the pressures within the knee joint over the cartilage after the creation of a defect in the cartilage and removal of the meniscus, the fibrous cartilage within the knee that acts as a shock absorber.

Eight human knees, taken from cadavers, were placed in an apparatus that creates weight across the knee joint. The researchers then measured the pressures created over the cartilage within the knee joint.

Researchers found that even three degrees of malalignment, which can only be detected by an x-ray, can lead to profound deformation of the cartilage. Over time, this deformation can lead to uneven wear and tear, leading to painful and debilitating osteoarthritis, according to the study presented at the 28th annual meeting of the American Orthopedic Society for Sports Medicine.

"Past studies have shown that between 20 and 50 percent of patients who have had significant knee cartilage damage developed severe arthritis," said Guettler. "What hasn't been shown is why some patients do and some do not. Our studies would suggest that a very important factor is the subtle changes in alignment of the leg bones relative to the joint and the pressure they place on the cartilage within the knee."

Patient with significant cartilage damage and those who have had damaged cartilage removed should be evaluated for correct alignment. If any evidence of deterioration is seen, surgery should be considered to correct it.

"In these cases, the surgery is seen more as a preventive measure against future osteoarthritis, as opposed to a treatment for a specific disorder," said Guettler. "This is an invasive procedure with known complications, yet it should be considered for these high-risk patients."

Other sources: Duke University