What’s the lasting effect of surgical knee repair?

Knee injuries, especially to the cartilage in the joint, are a common cause of pain and impaired movement, especially in young, active people. These injuries often happen in conjunction with other injuries to the meniscus or anterior cruciate ligament in the knee.

The Norwegian alpine champion Aksel Lund Svindal is a prime example of this, says Svend Ulstein, a specialist in orthopedic surgery at Akershus University Hospital and the researcher behind the new study.

He says cartilage injury can make it impossible for top athletes to get back to their elite competitive level again.

“If you have severely damaged your knee cartilage, it can’t heal by itself. For a long time, we haven’t known very much about what happens with patients who have damaged their knee cartilage, and neither doctors nor researchers agree on what is the best treatment method,” Ulstein said.

Depth of cartilage damage affects prognosis

In his doctoral dissertation at the Faculty of Medicine, University of Oslo, Ulstein studied how injuries to the knee cartilage and surgical treatment affect the function of the knee 5-10 years after surgery.

Ulstein says that injuries to the knee cartilage are relatively common, and that Norwegian surgeons perform roughly 2,500-3,000 procedures to repair this type of injury every year.

The researcher looked all patients in Norway and Sweden who had anterior cruciate ligament repair, or ACL surgery, from 2005–2008, to see how they had fared compared to patients who had this surgery but had also injured their knee cartilage.

“We found that the 5-year prognosis is worse in patients who had injured their knee cartilage along with ACL damage,” Ulstein said.

He also found that the depth of the damage to the cartilage, as opposed to size of the damage, had a negative impact on the prognosis. The deeper the damage, the harder it is for the body to heal. The message from the studies is that knee cartilage damage can cause significant impaired knee function, pain and reduced quality of life for 5-10 years after the injury.

Compared surgical methods

Ulstein also compared the two most common surgical methods, microfracturing and mosaicplasty for isolated knee cartilage damage. Ulstein says that microfracturing is the most common.

In this case, the surgeon drills small holes in the damaged cartilage in the bone, allowing bone marrow cells to flow into the area and supply healthy cells that form new cartilage. The surgeon also cleans up the loose cartilage that is floating around in the knee.

With mosaicplasty, the surgeon retrieves cartilage from healthy areas of the joint and moves it to the injured area.

Ulstein says that both methods resulted in improvement of knee function, but that neither resulted in normal knee function in patients.

“We saw that the knees of patients in both groups were better than they were before surgery, but neither approach stood out as the best option. We also found that a large number of patients had to be operated on again later,” says Ulstein.

Surgical treatments showed no effect

In patients who had both a knee cartilage injury and anterior cruciate ligament injury, the researcher found no effect on the 5-year prognosis of surgical treatment compared to those who were not operated on.

"Based on these findings, we recommend being a bit careful with the use of surgical cleansing and especially microfracturing in patients with an ACL injury," says Ulstein.

He says he looked at the results of three groups: the first group had been operated on, the second group had had their knees surgically cleaned up, and the last one was a control group, which received no surgical treatment.

“We saw that there was no point in doing microfracturing in this situation for ACL patients. They do just as well without the operation,” says Ulstein.

Benefits don’t last very long

In many cases, doctors see that patients do better initially, but that after three years their function declines. Ulstein says that the benefits from microfracturing do not last particularly long.

Several other studies have had the same findings, but in those studies, researchers did not compare their results with a control group.

Ulstein says more research needs to be done into the best way to treat these injuries in the future.

“There are other techniques that seem promising, but we don't have any strong evidence to say anything definitive yet,” says Ulstein.

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Read the Norwegian version of this article at forskning.no