Knee scores improved after medial open wedge HTO for OA, osteonecrosis

Issue: October 2015

LYON, France — Although high tibial osteotomy is a useful surgical treatment for medial osteoarthritis of the knee, the medial open wedge high tibial osteotomy procedure, in particular, performed with a locking plate, has recently become popular with orthopaedic surgeons, according to a presenter, here.

In results of a study presented at the International Society for Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine Biennial Congress by Eiji Kondo, PhD, MD, medial open wedge high tibial osteotomy (HTO) with a TomoFix (DePuy Synthes; West Chester, Pa., USA) locking plate significantly improved the mean Japan Orthopaedic Association (JOA) scores in patients who underwent the procedure due to painful medial compartment osteoarthritis or spontaneous osteonecrosis of the medial femoral condyle.

“Postoperatively, the mean JOA significantly improved from 66 to 92 points. The lateral femorotibial angle changed from 180° to 170°. The weight-bearing line shifted to 69% better from the medial edge of [the] tibial plateau,” Kondo said.

Kondo and colleagues performed a medial open wedge HTO in 58 women and 19 men with a mean age of 62 years using a biplanar osteotomy of the tibia. They then wedged hydroxyapatite or beta-tricalcium phosphate material into the opening created in the tibia.

The patients were allowed to weight bear after 2 weeks and they could fully weight bear at 4 weeks postoperatively. At a mean follow-up of 25 months, all the patients underwent clinical and radiological follow-up examinations and they all had a second surgery for plate removal.

Some patients developed serious complications and three patients required a revision surgery, according to Kondo.

“We observed one case of superficial wound infection, one case of nonunion and one for over-correction. Lateral hinge fractures were observed in 22 knees, as well,” Kondo, of Sapporo, Japan, said.

Patients with nonunions and over-corrections underwent a second HTO to address these complications. One patient had a lateral plateau fracture and was converted to a total knee arthroplasty, he said.

Among the 22 knees with lateral hinge fractures, 14 fractures were type I, three fractures were type II and five fractures were type III, according to the Takeuchi classification. About 8.8% of implants (7 cases) failed, which included four cases of proximal locking screw breakage and three cases of distal locking screw breakage.

“Proximal locking screw breakage was observed in four cases, as well as a total of five distal locking screws in three cases, which were difficult to remove. The screw head had to be destroyed using a carbide drill,” Kondo said.

The procedure helped improve JOA scores in these patients’ knees, but several complications led to revision surgery, according to the investigators. They noted a more precise surgical procedure may decrease the lateral hinge fracture rate and patients should be informed about the possible difficulty of removing the locking screws. – by Robert Linnehan

Reference:
Kondo E, et al. Paper #34. Presented at: International Society for Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine Biennial Congress; June 7-11, 2015; Lyon, France.

For more information:
Eiji Kondo, MD, PhD, can be reached at Department of Advanced Therapeutic Research for Sports Medicine, Hokkaido University Graduate School of Medicine, Kita-15 Nishi-7, Kita-ku, Sapporo, 060-8638, Japan; email: eijik@med.hokudai.ac.jp.

Disclosure: Kondo reports the Department of Advanced Therapeutic Research for Sports Medicine, Hokkaido University Graduate School of Medicine has the following financial relationships to disclose: Grant/research funding from Muto Co. Ltd., Smith & Nephew Endoscopy Japan, Olympus Terumo Biomaterials and Yufu Itonaga Co. Ltd.