Ask the Doctors April 2012 Issue

Ask The Doctors: April 2012

Knee Tears and Arthritis...Bone-Healing ‘Stimulators’...Methotrexate Interactions

Q. I had arthroscopic procedures for ACL and MCL tears to my knees in my younger days. Do these injuries lead to early arthritis? Is arthroscopy always recommended for ACL and MCL injuries?

A. Any trauma to a joint, even surgery, can potentially start a cascade of events in the joint that lead to cartilage destruction and osteoarthritis. Osteoarthritis has been reported to develop within 10 to 20 years in over half of patients with ACL injuries. However, some research suggests that osteoarthritis is less likely to occur when the torn ACL is reconstructed than when the patient is left with an “ACL-deficient” knee. If the menisci are intact, fewer than 10 percent of patients have signs of arthritis 10 years after surgery. One recent study found that patients who regained normal knee motion after an ACL injury were less likely to develop arthritis than those who lost knee motion. ACL reconstruction is almost always done arthroscopically or with a combination of open surgery and arthroscopy. Because arthroscopic reconstruction uses several small incisions rather than a large incision that exposes the entire knee joint, recovery is faster and less painful. Arthroscopy is not used for repair or reattachment of the MCL because it is outside the joint; surgery is performed through a small incision on the inside of the knee.

Q. What can you tell me about “stimulators” that help bones heal? In particular, I’ve been told that damaged bones can be repaired through the use of ultrasound.

A. During the past two decades, several methods have been introduced for stimulating bone healing. Two of the more successful methods are electrical stimulation and low-intensity ultrasound. Electrical bone-growth stimulators may be noninvasive (composed of coils or electrodes placed on the skin near the fracture for varying amounts of time each day) or invasive (wires are inserted through the skin to the bone, or a generator is surgically placed under the skin). The ultrasound device sends out low-frequency sound waves and is applied to the skin through an opening in the cast, usually for about 20 minutes a day. The exact mechanism through which ultrasound stimulates bone healing is unknown. Reports have described varying success with these devices, although most indicate accelerated bone healing through the use of both electrical stimulation and ultrasound. The advantage of these stimulators is that most are noninvasive and easy to use. Disadvantages are their cost, their dependence on patient compliance, and the fact that they often can be used only on certain bones and are difficult to use in obese or very muscular patients.

Q. I’m taking methotrexate for my rheumatoid arthritis, but I’ve heard that it doesn’t react well with penicillin. Are there any other drugs I should not take while on methotrexate?

A. There are potential interactions between methotrexate and several drugs. Penicillin has been reported to increase the renal clearance of methotrexate and increase serum levels, which could increase liver toxicity. Although nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to increase methotrexate’s liver toxicity, methotrexate has been successfully used with NSAIDs and antibiotics. Most physicians feel they can be used together without incident, but they do require careful monitoring through blood tests that look for increased liver function and blood counts.