07/07/2009 05:12 am ET | Updated Nov 17, 2011

Follow Up -- Innovative MRI Technique Helps Identify Mystery Knee Pain following Knee Replacement

This is a follow up from last week's posting about using MRI after a total knee replacement and presents an actual patient case study. Whenever I have interesting case histories I will post them.

Recently, a police officer underwent two surgeries including a partial knee replacement . When he walked he had severe pain and would hear a "popping noise." He also had trouble walking, even with a cane. As a police officer he needed to be mobile.

Directed by a friend to see an Alejandro Gonzalez Della Valle, M.D., Assistant Attending Orthopaedic Surgeon, Hospital for Special Surgery. Dr. Della Valle suspected that the ligament that prevents the shin bone (tibia) from sliding backwards, the posterior cruciate ligament (PCL), was deficient and was causing the pain and popping noises as he walked.

The diagnosis was challenging because of the partial knee replacement. To confirm his suspicions, Dr. Della Valle sent his patient for a Magnetic Resonance Imaging examination, in the Department of Radiology and Imaging at Hospital for Special Surgery.

"The standard x-rays that had been taken in the past were masking the real problem. An x-ray cannot image soft tissue such as the PCL," stated Dr. Potter Chief, Magnetic Resonance Imaging at Hospital for Special Surgery. "The MRI Division has worked on the development of MRI protocols that allow us to capture images of the soft tissue around a total joint replacement. This technique helped us determine that the PCL was, in fact, deficient. In the past it was impossible to image soft tissue using MRI, because the metal in replacement hardware would negatively interact with the high powered imaging magnets. Our research and new techniques have helped to change that fact."

After the PCL deficiency was diagnosed, the patient was scheduled for surgery for a total knee replacement. The day after surgery the patient was up and walking and felt much better. The popping noises had stopped and after only four weeks and had no pain. The total knee replacement allowed the patient to return to his normal life and level of activity.

Five months after his surgery, the patient brought his 88- year-old mother to see Dr. Della Valle for debilitating arthritis in her left hip. Her X-Rays showed there was very little cartilage left in the hip, causing severe pain. When she saw Dr. Della Valle she was in a wheel chair. One month after her first visit, she underwent a left total hip replacement and within six weeks she was out of her wheel chair and walking with a cane. A year later, she is back to her regular routine, taking the bus to the senior center to see her friends and going fishing with her son.