MIS bunion correction offers advantages over open technique, but questions remain

One surgeon finds serious complications with the technique and calls it ‘simply poor surgery.’

Issue: Issue 3 2007

SAN DIEGO — Italian surgeons are advocating a technique for minimally invasive bunion correction, but a few surgeons continue to question the visual capabilities and accuracy of such a technique.

After performing the standard chevron osteotomy for some time, Sandro Giannini, MD, and his colleagues turned to a minimally invasive bunion correction technique they named SERI – an acronym for simple, effective, rapid and inexpensive.

Giannini switched to this technique – performed through a 1-cm incision – “in order to have a more versatile procedure as well as the possibility to [treat] a posterior hallux valgus deformity,” which is not possible with the chevron osteotomy, he said.

However, Mark S. Myerson, MD, is wary of the SERI technique. He has performed the technique and conducted a prospective, randomized study comparing it to the traditional chevron approach.

“Unfortunately, 2.5 months following initiation of the study, we had to abandon it, due to frequent complications,” Myerson said. “Some of these complications were quite serious.” He and Giannini debated the topic at the American Orthopaedic Foot and Ankle Society Specialty Day Meeting.

Myerson said he prefers open bunion correction because he can modify the angle of the bone cuts according to the length of the metatarsal and the distal metatarsal articular angle.

With open bunion correction, surgeons can also tension the capsule as necessary, as seen here.

Images: Myerson MS

The SERI

Using the SERI technique, surgeons can correct all deformities, including rotation, plantar flexion and dorsiflexion, Giannini said. They can also evaluate the osteotomy planes, displacement and the stability of the first metatarsal head after pin fixation.

In addition, the technique requires only 3 minutes to complete, compared to 45 minutes with the chevron osteotomy. This reduction in surgical time ultimately lowers the costs, he said.

But Myerson countered, “To perform an open osteotomy correctly, safely and reliably, this cannot and should not be performed in less than 45 minutes.”

Features of this technique include dorsoplantar displacement in the sagittal plane with 15° of inclination, tilting of the metatarsal head to correct the distal metatarsal articular angle, and K-wire fixation.

“It’s very important that [we use] K-wire fixation because we do not do wedge removal,” Giannini said. “With forced bending of the K-wire, it is possible to see the compression into the medial cortical [compartment] and to have a greater stability of fixation.”

Patients have acceptable range of motion at 4 weeks after undergoing the open chevron osteotomy.

Besides an acceptable range of motion, patients also experience quick healing and cosmesis, Myerson said.

He and his colleagues achieved good to excellent results with the SERI technique in 90% of grade 0 arthritis patients and in 82% of grade 1 arthritis patients.

Giannini cautioned colleagues that the SERI technique requires the correct indications and technique for success. It also entails a manipulation of the big toe in order to release the lateral sesamoid, stretching the lateral capsule and abductor muscles. “As for all surgeries, a learning curve of 30 cases is required. For this reason, Dr. Myerson’s results are based on 20 patients, which is an insufficient number,” he said. “Also, the technique was not performed according to the one I presented.”

He added: “The indications are any type of hallux valgus except for severe arthritis, severe instability and metatarsophalangeal joint stiffness.”

SERI vs. Kramer and Bösch

The SERI technique offers advantages over other minimally invasive bunion correction techniques, according to Giannini. Although the SERI, Kramer and Bösch procedures are similar because they include one K-wire and a linear osteotomy, important differences exist.

Sandro Giannini, MD
Sandro Giannini

The Kramer procedure is more invasive than the SERI approach, requiring a longer incision, greater soft tissue release, complete opening of the capsule, removal of the bony wedge and a vertical osteotomy in the sagittal plane – which make the osteotomy more unstable, he explained.

The Bösch procedure is a percutaneous technique, which complicates visualization and requires X-ray control. It is not a mini-open technique like SERI, which allows a direct line of vision of the surgical steps, he said. Surgeons also typically use a high-frequency reamer for this procedure, rather than a normal saw, which can cause bone resection and shortening of the metatarsal.

Open chevron osteotomy

Intrigued by Giannini’s work in Italy, Myerson undertook an Institutional Review Board-approved randomized pilot study on 20 patients to compare the minimally invasive osteotomy to the chevron procedure. He abandoned the study after 2.5 months.

“We had recurrent hallux valgus in six of 13 patients, dorsal malunion in nine of 13 … nonunion in one patient, avascular necrosis in one … and cellulitis, pin problems and stiffness of the metatarsophalangeal joint in every single patient,” Myerson said.

The presumed advantages of minimally invasive surgery (MIS) are obvious, Myerson said: surgery is fast and easy, patients have minimal postoperative swelling and can begin ambulating immediately, and healing and cosmesis are quicker.

“But when you look at the known advantages of open traditional surgery, [one of them is] you can see what you are doing; you cannot see anything with MIS. The osteotomy can be planned; you have to guess the alignment when you’re doing this percutaneously,” he said.

Multiplanar correction

Also with MIS, multiplanar correction is not possible and fixation is transarticular. In other words, it is not as anatomic-based as open traditional surgery, according to Myerson.

Furthermore, “Healing and cosmesis are acceptable, and range of motion at 4 weeks following the chevron osteotomy is quite acceptable,” Myerson said. “[The chevron procedure] is not a long procedure, and it’s reliable and safe.”

SERI technique used to treat patient
This 49-year-old patient presented with hallux valgus. Giannini treated her with bunion correction, using the SERI technique.

SERI technique using K-wire
This patient underwent the SERI technique, which is a minimally invasive technique using K-wire.

1-year follow up of SERI technique using K-wire
Here is the same patient at 1-year follow-up.

Images: Giannini S

For more information:
Sandro Giannini, MD, can be reached at Instituto Ortopedico Rizzoli, via GC Pupilli, 1, 40136, Bologna, Italy; +39-51-636-6827; e-mail: giannini@ior.it. He has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.
Mark S. Myerson, MD, can be reached at The Institute for Foot & Ankle Reconstruction at Mercy, 301 Saint Paul Place, Baltimore, MD 21202, U.S.A.; +1-410-554-2866; e-mail: mark4feet@aol.com. He has no direct financial interest in the products discussed in this article, nor is he a paid consultant for any companies mentioned.
Giannini S. Debate I: Are MIS techniques better? Mini-incision bunion correction.
Myerson MS. Debate I: Are MIS techniques better? Open bunion correction. Both presented at the American Orthopaedic Foot and Ankle Society Specialty Day Meeting. Feb. 17, 2007. San Diego.