At a Glance
- Patellar dislocation is often caused by an anatomical abnormality that can only be corrected with surgery
- UVA is one of the few centers offering trochleoplasty, a procedure that deepens the bony groove that contains the kneecap
- Case study reveals the risks and benefits of trochleoplasty
- Video shows the steps involved in a trochleoplasty procedure
As you know, patellar dislocation is not uncommon. Though often caused by a trauma such as a sports injury, for some patients, dislocation of the kneecap is a recurrent problem caused by an anatomical abnormality that can only be corrected with surgery. In these patients, the ordinarily smooth trochlear groove of the femur has a bump that impedes alignment and kicks the kneecap off to the side.
This congenital dislocation is typically evident during a patient’s childhood or teenage years. Once the kneecap slips out of place, associated tearing of the medial patellofemoral ligament (MPFL), which restrains the kneecap, makes the patient susceptible to future dislocations. “We can do a lot to reconstruct the ligament, but ultimately you have to repair the bump. That is the problem,” says UVA orthopedic surgeon David R. Diduch, MD.
Diduch is one of the few surgeons in the country providing a relatively new and complex procedure to deepen the bony groove that contains the kneecap. This procedure is called trochleoplasty and it was pioneered in 1987 by French orthopedic surgeon Henri DeJour, MD. “I got to know DeJour’s son, David, who followed his footsteps, when I was an editor of a surgical textbook,” says Diduch. “I picked his brain, and he was patient and gracious enough to teach me the technique.”
What Is Trochleoplasty?
Trochleoplasty involves reshaping the trochlear groove to achieve a normal anatomical state and proper positioning of the patella. Just how much bone removal is necessary varies from patient to patient. “This is not a cookbook surgery,” says Diduch. “You have a menu of options and it takes experience to identify what works for each patient.”
Who Is Eligible?
To be eligible for the procedure, patients should be between the ages of 13 and 30 and experience recurrent patellar dislocation. “Typically, trochleoplasty patients are in their teens,” says Diduch. “They have to have stopped growing and they can’t have arthritis — it makes the bone too dense and we cannot reshape it — so there’s a limit to how old a patient can be as well.”
What Are the Risks?
What makes this procedure challenging is the precision required to reshape the trochlear without damaging it. There is also a high risk of arthritis and joint stiffness if the proper steps are not taken to preserve the cartilage within the joint. “There is a lot of risk with this procedure,” explains Diduch. “This is why some surgeons are hesitant to do it. But I have done over 50 procedures in the past five years with excellent results. Now I’m training other surgeons how to do the procedure.”
Diduch is spreading the word because he believes the benefits outweigh the risks. “Dislocation is very painful and incapacitating, so patients are very grateful when their knee finally stays in place,” he says. “They may have had other procedures in the past that did not fix the problem, but this is a game changer.”
Do you have a patient with recurrent patellar dislocation? Learn more about trochleoplasty, its risks and benefits in the case study below.
Case Study: Trochleoplasty
Patient: Olivia Kitelinger, 20
Assessed by: UVA orthopedic surgeon David R. Diduch, MD
Presented with: Knee pain
“All of my life, since age five, I have had knee pain,” says Kitelinger. “I played sports anyway, but I took lots of Advil. In 2009, my knee popped out and stayed out, so I went to the ER. They just popped it back in place and told me to wear a knee brace; there wasn’t another treatment option at that time. I was afraid it would happen again, so I limited myself and I was more cautious. But the pain continued. That’s why I was referred to Dr. Diduch.”
Diagnosis: Patellar instability due to trochlear dysplasia
“The X-rays and MRI scans showed a kneecap that rested in a tilted position, poised to slip off the side, and a bony prominence called a spur or bump that kicked the kneecap to the side and prevented it from finding the normal groove,” says Diduch. In fact, the normal concave groove was replaced by a convex bump. This bony prominence can be seen on a lateral X-ray, but can be subtle, explains Diduch. An MRI or CT scan makes it easier to see the spur in cross section.
Prior to the procedure, Kitelinger received nerve blocks to numb her leg. A 10-cm incision was made in the front of her knee for exposure. “The trochlear groove was deepened by first using an osteotome, a device similar to a chisel, to remove the spur on the front of the femur and open up a wedge around the edge of the cartilage,” says Diduch. “A high-speed burr was then used to remove bone underneath the joint surface of the trochlea, leaving a shell of bone and cartilage that flexed like a diving board. The new trochlear shape was marked with a pen on the surface, and then a large blade was used to cut through the shell where we wanted the new groove to be. The shell could then be molded into a new shape.” Sutures were secured above and below the new groove using absorbable anchors; these sutures were pulled tight — similar to a cargo net — to compress the shell in the new position for healing. Lastly, one of Kitelinger’s hamstring tendons was harvested to make a new MPFL ligament to restrain the kneecap and prevent it from sliding to the side. This was fixed to the femur with an absorbable screw and to the patella through drill holes.
Recovery: 5-6 months total
Trochleoplasty is an outpatient procedure, so Kitelinger was discharged from the hospital the same day, outfitted with a leg brace to support the knee and crutches. “I didn’t feel any pain until the block wore off two days after surgery, but it wasn’t excruciating and I didn’t require pain medication,” she says.
Physical therapy began a few days after surgery. Over time, Kitelinger was transitioned into greater degrees of motion by adjusting the brace hinges, allowing the knee to bend gradually.
“If the patient doesn’t move right away, then scar tissue can set in, leading to stiffness and possibly more surgery,” says Diduch. “Physical therapy typically lasts for three months as patients build up their strength, but for some it takes longer. By six months, recovery is complete and patients should be back to playing sports.”
Outcome: Fully functional and no side effects from surgery
“Since the surgery, I have no limitations,” says Kitelinger. “I returned to work after six weeks, I go to the gym and I go running. I feel great and I’m happy with the outcome.”
As with any new procedure, monitoring patients over time is important. Diduch is following his trochleoplasty patients prospectively with X-rays and outcomes scores to look for long-term results. “Thus far, no patient has had a repeat dislocation, which is remarkable considering how unstable many were prior to surgery,” he says.