Hour-Long Procedure Repairs Battered Knees

wo years ago, plastic surgeon A. Lee Dellon, M.D., became the first Hopkins part-time faculty member to receive a promotion to full professor. Dellon has made something of a mark for himself with another first, too—a brand new microscopic procedure structured for the 3 percent of patients with extreme knee pain whose distress is not resolved with arthroscopic surgery. He’s gone on to teach the novel approach to his colleague Maurice Y. Nahabedian, M.D., a faculty member in the Division of Plastic Surgery, who’s now performed it dozens of times, too.

Denervation microscopic surgery is an unusual operation, the two doctors agree, but only in view of the fact that most physicians don’t recognize the role that nerves around the knees play in ongoing disabilities. “It’s unbelievable if you think about it,” Dellon says, “but even current anatomy books don’t illustrate these nerves.” Due to the oversight, the common approach to continuing pain following knee replacement surgery has been structural, focusing on bone, cartilage or ligaments.

“Total knee arthroplasty is a highly successful operation,” the plastic surgeon makes clear. “Most patients don’t continue to have problems with pain.” But those who do—some 6,000 people a year in this country—can have difficulty in finding relief. Some undergo more than a dozen arthroscopies and open operations for the problem and become regulars at pain clinics. “Few physicians stop to consider,” Dellon says, “that the approach to stopping the pain should focus primarily on torn or stretched nerves to those areas.”

What’s incredible is that sensory nerves to the knee do exist: In 1993, Dellon and medical student Greg Horner located them via meticulous dissections of cadavers. Then, three years ago, in collaboration with orthopedic surgeons David Hungerford, M.D., and Michael A. Mont, M.D., Dellon and then Nahabedian began eliminating the pain by surgically knocking out those nerves. Now, more than 200 patients later, partial denervation microsurgery, done on an outpatient basis, is both well-established and successful, with fewer than 5 percent of patients requiring a second session.

Candidates for the procedure first undergo a complete orthopedic evaluation to rule out structural problems or infections. Also, enough time must have elapsed following orthopedic surgery to make sure the pain won’t go away on its own. Dellon or Nahabedian then injects an anesthetic to pinpoint suspect nerves—often those medial and lateral to the knee joint. When patients say the pain has disappeared, the doctors know they’ve hit the right nerve. The surgeon makes a 6-centimeter incision at the side of the knee. Then, peering through a jeweler’s loupe, he follows the specific, tiny blood vessel that marks the nerve around the knee’s other structures and cuts away a portion of the nerve that’s responsible for the pain. The surgery takes less than two hours and “patients get up and walk out,” the doctors report. “They don’t need rehab.”

—MC