New research from Finland suggests many thousands of people who have arthroscopic knee surgery to fix a torn cartilage could be wasting their time.

A report on the Finnish Degenerative Meniscal Lesion Study (FIDELITY), published recently in the New England Journal of Medicine, finds that the benefits of keyhole operations to repair degenerative meniscal tears are no better than sham operations.

Previous studies have shown that keyhole surgery on the knee does not help patients with osteoarthritis and such procedures have become less common for arthritis sufferers.

In the meantime, keyhole surgery to repair torn cartilage has risen significantly, despite lack of evidence that it actually helps, says the Finnish team.

Knee problems other than arthritis that cause stiffness and pain are very common, and are most often caused by gradual wear and tear rather than sudden injury or trauma. The most common diagnosis that requires treatment is a torn meniscus, a crescent-shaped cartilage that acts like a shock absorber and helps stabilize the knee.

The usual procedure for repairing a torn meniscus is keyhole surgery or arthroscopy, where the surgeon inserts a scope through a small incision to examine the joint and, if required, also partially removes the damaged cartilage through another incision.

In this new study, the Finnish team recruited 146 patients aged from 35 to 65 with meniscal tears that had developed through wear and tear rather than injury or trauma. None of the patients had arthritis of the knee.

The researchers randomnly assigned the patients to one of two groups: one underwent keyhole surgery to partially remove the damaged meniscus and the other underwent a sham procedure.

In the sham procedure, the surgeons simulated the real operation. They manipulated the patient’s knee and handled surgical instruments near the knee so the patient was under the impression they were being operated on.

Thus both groups underwent arthroscopy, where the scope in inserted into the keyhole so the surgeon can look at the torn cartilage, but only one group actually had part of the cartilage removed.

But neither the patients, the people caring for them after the operation, nor the researchers analyzing the results knew which patients had undergone the real procedure and which had just had the sham operation.

The results show that a year later, both groups of patients had an equally low rate of symptoms and were equally satisfied with the overall situation of their knee.

Both groups of patients said they believed their knee felt better than before the operation.

When asked if they would choose the same procedure again, 93% of the partial meniscectomy group said they would, as did 96% of the sham procedure group.

The researchers conclude:

In this trial involving patients without knee osteoarthritis but with symptoms of a degenerative medial meniscus tear, the outcomes after arthroscopic partial meniscectomy were no better than those after a sham surgical procedure.”

Speaking of the impact the study is likely to have, lead author Raine Sihvonen, a specialist in orthopedics and traumatology at Hatanpää Hospital in Tampere in southern Finland, says:

“It’s difficult to imagine that such a clear result would result in no changes to treatment practices.”

He explains that in nearly all Western countries, this operation is now the most common surgical procedure after cataract surgery, adding that:

“By ceasing the procedures which have proven ineffective, we would avoid performing 10,000 useless surgeries every year in Finland alone. The corresponding figure for US is at least 500,000 surgeries.”

Co-author and state adjunct professor Teppo Järvinen, of the Helsinki University Central Hospital, says:

Based on these results, we should question the current line of treatment according to which patients with knee pain attributed to a degenerative meniscus tear are treated with partial removal of the meniscus, as it seems clear that instead of surgery, the treatment of such patients should hinge on exercise and rehabilitation.”

Earlier this year, an important discovery about knee anatomy made its mark when knee surgeons in Belgium for the first time described a new knee ligament called the anterolateral ligament (ALL).