Surgeons discontinue mini mid-vastus TKA after prospective randomized trial

Complications occurred in patients with TKA with a mini mid-vastus approach.

Issue: October 2013

Complications and a longer operating time were the main reasons investigators from The Netherlands stopped using a mini mid-vastus approach for cemented total knee arthroplasty after they obtained their patients’ 1-year results. The investigators concluded the procedure was no more successful in their hands than implanting the same prosthesis with a conventional approach in adults with knee osteoarthritis.

“We can say there are no clear advantages for using minimal invasive technique with this study. The hypothetical benefits of minimal invasive surgery for total knee arthroplasty are therefore questionable,” Hennie Verburg, MD, said in a presentation at the EFORT Congress in Istanbul.

Verburg and colleagues conducted a prospective randomized controlled study of minimally invasive total knee arthroplasty (TKA) performed in 50 adult patients with a mini mid-vastus approach and compared the patients to 50 adults who underwent TKA with a conventional approach. Surgeons used the NextGen LPS Hi Flex prosthesis (Zimmer; Warsaw, Ind., USA) in both groups.

Investigators took this CT scan of the proximal tibia 2 mm distal of the prosthesis, which shows the cement remnants and the overhang of the tibia component on both the medial and lateral sides. These features were not visible on a conventional anteroposterior or lateral radiograph.

Two experienced orthopaedic surgeons performed the surgeries between August 2007 and June 2009 in patients with similar ages and body mass index. Intraoperatively they used a tourniquet and Palacos cement with gentamicin (Zimmer) in both groups, Verburg said.

Learning curve

Before the study began, both surgeons completed cadaver work to familiarize themselves with the mini mid-vastus approach.

“Hereafter, they had a clinical learning curve of at least 50 procedures each in the year before starting the comparative study,” Verburg told Orthopaedics Today Europe.

The skin incision in the minimally invasive surgery (MIS) group was an average of 12.4 cm long.

“The vastus medialis muscle was split, with a mean length of 2.8 cm, in line with its fibers. A rip frequently appears increasing the size of the vastus incision, with a mean [length] of 0.6 cm at the end of the operation,” Verburg said during his presentation.

The conventional group had significantly longer skin incisions of 14.9 cm average. Eight patients in the conventional group and one patient in the MIS group required a lateral parapatellar release.

Differences that mattered

The surgery time in the MIS group was 86 minutes vs. 80 minutes in the conventional group, a difference that was statistically significant.

“Complications during operations were seen in three patients, all in the minimal invasive group,” Verburg said.

Radiographic follow-up showed no significant differences in tibial or femoral component slope or position with either approach. In both groups radiographs revealed one instance each of grade 3 femoral prosthesis notching, he said.

“We stopped with the mini mid-vastus approach after the study was finalized and the results from the 1-year follow-up were known,” Verburg told Orthopaedics Today Europe. The surgeons now limit their use of this MIS TKA approach to patients who want a smaller scar, but the investigators always explain to these patients all the disadvantages and possible complications of MIS TKA before proceeding with surgery, Verburg said. – by Susan M. Rapp

Reference:
Verburg H. Paper #13-2327. Presented at: EFORT Congress; June 5-8, 2013; Istanbul.

For more information:
Hennie Verburg, MD, can be reached at Department of Orthopaedic Surgery and Traumatology, Reinier de Graaf Group, 2600 GA, Delft, Netherlands; email: hverburg@rdgg.nl.

Disclosure: Verburg has no relevant financial disclosures.