Purpose: End-stage knee osteoarthritis (OA) is frequently treated by total joint replacement (TKP). In 40% of the cases this relative expensive treatment is performed under the age of 65 years, while the procedure has a higher risk of failure in younger patients, due to higher physical demands. Knee joint distraction (KJD) is an experimental treatment for end-stage knee OA, aimed at unloading the joint cartilage and subchondral bone by use of an external fixation frame. The technique proved to be clinically effective for end-stage ankle OA. The present study describes an exploratory, open, uncontrolled trial to verify whether KJD has the potency to postpone a TKP by inducing clinical improvement and cartilage repair. Methods: Twenty patients, under 60 years of age, with end-stage knee OA were treated with KJD for 2 months. Two monotubes with internal coil springs were placed parallel on the medial and lateral side bridging the knee joint and subsequently lengthened for 2 mm. In the following three days the joint was distracted twice a day for 0.5 mm, bringing the total distraction to 5 mm for the remaining time. Patients were encouraged to load the knee during distraction. After 2 months, tubes and pins were removed. At home, under supervision of a physiotherapist function was practiced, without imposed restrictions. Most patients (n=17) suffered from single or multiple pin tract infections, all being successfully treated with antibiotics. The primary structural outcome was cartilage thickness by use of quantitative MRI and digital analyses of standardized X-rays. Primary clinical outcome was pain and function by use of the WOMAC questionnaire. Secondary outcome parameters were, MRI determined decrease in area of denuded bone, increase in cartilage area and volume as well as biochemical markers of cartilage collagen type II synthesis and breakdown. For secondary clinical outcome VAS pain was documented. Results: Quantitative MRI analysis, at one year after distraction, showed an increase in cartilage thickness of the most affected compartment from 2.4 to 3.0 mm (p<0.01). The total area of denuded bone decreased from 22% to 5% (p<0.01). Cartilage area and volume increased from 15.6 to 18.9 cm2 and 2.3 to 2.8 cm<sup>3</sup> (both p<0.05). X-ray analysis, at one year, corroborated the MRI findings by an increased mean JSW from 2.7 to 3.6 mm (p<0.05). The minimum JSW increased accordingly from 1.0 to 1.9 mm (p<0.01). Long term changes in biomarkers (6 and 12 months follow-up) showed a trend towards a decrease of collagen type II breakdown marker CTX II (-11%; p=0.07) and an increase of collagen type II synthesis marker PIIANP (+103%; p=0.06). The average change in the ration of PIIANP/CTXII of each patient was in favor of synthesis (p<0.056). Increase in cartilage thickness and decrease in denuded bone area correlated with the increase in collagen type II synthesis biomarker. One year after distraction the total WOMAC score improved significantly from 45% at baseline to 77% (p<0.001). This improvement is supported by a decrease in VAS pain score from 73 to 31 mm (p<0.001). Conclusions: Joint distraction in treatment of end-stage knee osteoarthritis is able to induce significant intrinsic joint cartilage repair, based on MRI, X-ray and biochemical marker analyses. These significant tissue structure changes are accompanied by clinical improvement in pain and function.
Intema, F., Wiegant, K., van Roermund, P. M., Marijnissen, A. C., Cotofona, S., Felix, E., … Lafeber, F. P. (2010). 321 TISSUE STRUCTURE MODIFICATION IN END-STAGE KNEE OSTEOARTHRITIS BY USE OF JOINT DISTRACTION. Osteoarthritis and Cartilage, 18, S142. https://doi.org/10.1016/s1063-4584(10)60348-2