Articulating distraction arthroplasty device shows potential for treating knee OA

The device allows for joint space widening and active ROM exercises while avoiding damage to intra-articular structures.

A new distraction arthroplasty device that allows continuous active movement while applied shows potential for enhancing fibrocartilage formation from bone marrow stimulation in knees with osteoarthritis, according to a study by researchers in Japan.

The experimental device, which was developed by the study authors and manufactured by Meira Corp., is designed to preserve the joint surface and protect regenerating fibrocartilage against overloading during weight-bearing. It also is articulated to allow smooth exercising of the joint during fixation, according to the study.

Masataka Deie, MD, and colleagues at Hiroshima University, evaluated the device in six knees of six patients who averaged 49 years of age, ranging from 42 to 63 years. All cases had Kellgren-Lawrence grade 3 or higher knee osteoarthritis (OA) that had spread to both the medial and lateral tibiofemoral joints.

In all cases, surgeons first examined the knees arthroscopically, and performed a partial medial menisectomy in two knees. They then arthroscopically performed bone marrow stimulation using 1.5-mm Kirschner wires or microfracture using an ice pick.

The external distraction arthroplasty device was applied after bone marrow stimulation and removed 2 to 3 months postoperatively, according to the study, published in Arthroscopy.

To apply the device, surgeons inserted a 2-mm guide pin at the proximal tibia parallel with the joint line. After checking the position fluoroscopically, the device was fixed in place using two 6-mm pins drilled into the proximal tibia 2 cm below the tibial plateau.

"These pins indicated the optimum location of the external fixation device," the authors wrote.

Surgeons then inserted two 2-mm guide pins into the apexes of both the medial and lateral epicondyles, which are at the center of rotational knee motion, according to the study.

"These guide pins did not penetrate the intercondylar space and did not damage the intra-articular ligaments. Then, according to the original guide frame, 2-mm guide pins were inserted, followed by two 6-mm pins, which were passed through the femur bone," the authors wrote.

"After the external devices were removed, follow-up arthroscopy revealed that in all cases the regions treated with the bone marrow-stimulation procedure were covered with newly formed tissues," the authors wrote.

No patients experienced any major complications, such as nerve palsy or deep infection, they noted.

The researchers found that the procedure had significantly improved patients' mean Japanese Orthopaedic Association scores, from 56 points preoperatively to 81 points at follow-up. Range of motion (ROM) also improved, from an average of –5° to 111° preoperatively to –5° to 122° at final follow-up, according to the study.

In addition, average joint space increased from 0.4 mm preoperatively to 1.6 mm distraction and remained an average of 1.5 mm at final follow-up after removal of the device.

"This device allowed widening of the joint spaces and the continuation of ROM exercises. It was specially designed not to damage intra-articular structures, such as the anterior cruciate ligament, posterior cruciate ligament and cartilage, with no pin being inserted at the femoral center of knee motion," the authors wrote.

"In this study, we found not only enlargement of the joint space and improvement of pain, but also an increase in ROM," they wrote.

For more information:
Deie M, Ochi M, Adachi N, et al. A new articulated distraction arthroplasty device for treatment of the osteoarthritic knee joint: A preliminary report. Arthroscopy. 2007;23:833-838.