New approach supports long-term bone growth

For most children, healing from a broken bone is relatively simple. They may spend a few weeks or months in a cast. But their bones heal, and they continue to grow normally. That isn’t the case for all pediatric patients.

Many children suffer fractures that affect a growth plate or physis. While most of these bone breaks mend without incident, some form bone bridges—called physeal bars—that can stop bones from growing normally.

Surgical removal (excision) of the physeal bar is the most effective treatment option. It encourages new bone growth, but the procedure isn’t always precise. And, sometimes, surgeons unintentionally leave behind small bone segments that can continue to inhibit growth.

To overcome this problem, orthopedic surgery specialists in the Cincinnati Children’s Division of Orthopaedics are utilizing a more targeted procedure that uses 3D imaging to ensure complete physeal bar excision. According to Wendy Ramalingam, MD, co-director of the Limb Lengthening and Reconstruction Center and a biomedical engineer, it’s a more accurate technique that increases surgeon confidence and improves outcomes.

“This interoperative imaging gives us a 3D view of the growth plate. It helps us navigate to the exact area of bone overgrowth,” she says. “This way, we can be very precise about what we’re removing. Then, we can confirm with the technology that we’ve taken out all the physeal bar.”

The Frequency and Impact of Growth Plate Fractures

Between 15% and 30% of fractures in children are physeal fractures that affect growth plates. Physeal bars form and stop bone growth in 5% to 10% of cases.

Ramalingam says patients can experience multiple problems when their bones stop growing.

“If the area of the growth plate affected by a fracture stops growing, but the unaffected part of the growth plate keeps growing, children can develop an angular deformity at the end of the bone at the joint,” she says. “Or it can cause the entire growth plate to tether so it doesn’t grow at all. That can lead to a limb-length difference.”

Left untreated, physeal bars also can cause joint hyperextension or range-of-motion loss. Additionally, joints that don’t line up properly may cause pain or contribute to early arthritis.

Traditional Physeal Bar Excision

Historically, surgeons use pre-surgery X-ray imaging to pinpoint the physeal bar’s location, Ramalingam says.

“You can figure out where you’re going to operate based on the X-ray images alone. But that’s a limited approach because it’s a one-dimensional image,” she says. “That makes it more challenging to be entirely sure that you’re in the right spot.”

By relying on traditional X-ray imaging guidance, surgeons complete physeal bar excision through a small incision near the growth plate. They can drill through the physeal bar, cut it away from the rest of the bone, and remove it. Using an arthroscope to visualize the edges of the remaining growth plate, they try to see whether any physeal bar remains in the physis.

“Arthroscopes can be used to look into the surrounding physis to ensure complete removal of the physeal bar,” she says. “But not all orthopaedic surgeons routinely perform arthroscopy.”

Physeal Bar Excision with 3D Imaging

To potentially improve the procedure and better encourage new bone growth, Ramalingam partnered with musculoskeletal interventional radiologist Neil Johnson, MB, BS, MMed.

Between summer of 2020 and December 2022, they enrolled five of Ramalingam’s pediatric patients in a study. These children either had an angular deformity or at least partial bone growth arrest due to physeal bars that accounted for up to 12% of their growth plate. Each child had at least two years remaining for potential growth.

Ramalingam and Johnson conducted each procedure in Cincinnati Children’s hybrid operating room. They used the XperCT system from Philips Healthcare to capture intraoperative 3D imaging guidance. Those pictures helped them precisely target each patient’s physeal bar.

During the minimally invasive surgeries, they used dilators to stretch and protect the soft tissue during the approach to the physeal bar. Then, using cylindrical Corb trephine drills and curettes to saw through the bone, they removed the bars and injected bone cement to prevent regrowth of the physeal bar.

Follow-up assessments at regular intervals postoperatively revealed all patients experienced positive results without any complications. On average, children with angular deformities saw 8.5 degrees of angular correction over 11.5 months, averaging 0.8 degrees of correction per month. The surgery also prompted more than 2 cm of new bone growth over 21 months for one child with a leg-length discrepancy.

“This child had a really big limb-length difference,” Ramalingam says. “But he did well with this surgery. Over time, his length discrepancy decreased. Not only did the affected growth plate keep growing, but he also saw some rebound growth to make up for the original inequality.”

Benefits to Both Surgeons and Patients

In addition to improved patient results, using 3D imaging guidance for physeal bar excision also benefits surgeons. According to Ramalingam, it doesn’t make the procedure faster, but it does give surgeons greater self-assurance.

“With the greater level of precision, I feel satisfied that I have confirmation that I’ve accomplished what I set out to do for the patient,” she says. “We see the problem on the CT scan. We remove the problem, and we have immediate confirmation on a new scan that the growth plate looks the way we want it to.”

Ultimately, Ramalingam hopes this research will expand the use of 3D imaging for physeal bar excision.

“My goal is to help these patients by doing as little as possible,” she says. “This one surgery provides a quick recovery. There’s a small incision that heals after a couple of weeks. They have no activity restrictions, and they can start weight-bearing right away. Ultimately, we’re helping to alleviate the need for more extensive surgeries, like osteotomies and external fixators.”

(Published December 2023)

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