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Clinical Trial
, 70 (8), 1441-6

Tissue Structure Modification in Knee Osteoarthritis by Use of Joint Distraction: An Open 1-year Pilot Study

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Clinical Trial

Tissue Structure Modification in Knee Osteoarthritis by Use of Joint Distraction: An Open 1-year Pilot Study

Femke Intema et al. Ann Rheum Dis.

Abstract

Background: Modification of joint tissue damage is challenging in late-stage osteoarthritis (OA). Few options are available for treating end-stage knee OA other than joint replacement.

Objectives: To examine whether joint distraction can effectively modify knee joint tissue damage and has the potential to delay prosthesis surgery.

Methods: 20 patients (<60 years) with tibiofemoral OA were treated surgically using joint distraction. Distraction (~5 mm) was applied for 2 months using an external fixation frame. Tissue structure modification at 1 year of follow-up was evaluated radiographically (joint space width (JSW)), by MRI (segmentation of cartilage morphology) and by biochemical markers of collagen type II turnover, with operators blinded to time points. Clinical improvement was evaluated by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Visual Analogue Scale (VAS) pain score.

Results: Radiography demonstrated an increase in mean and minimum JSW (2.7 to 3.6 mm and 1.0 to 1.9 mm; p<0.05 and <0.01). MRI revealed an increase in cartilage thickness (2.4 to 3.0 mm; p<0.001) and a decrease of denuded bone areas (22% to 5%; p<0.001). Collagen type II levels showed a trend towards increased synthesis (+103%; p<0.06) and decreased breakdown (-11%; p<0.08). The WOMAC index increased from 45 to 77 points, and VAS pain decreased from 73 to 31 mm (both p<0.001).

Conclusions: Joint distraction can induce tissue structure modification in knee OA and could result in clinical benefit. No current treatment is able to induce such changes. Larger, longer and randomised studies on joint distraction are warranted.

Conflict of interest statement

Competing interests None.

Figures

Figure 1
Figure 1
(A) Drawing of the monotubes placed on bone pins bridging the knee joint. Lengthening of the tubes (approximately 5 mm) induces joint distraction. Springs within the tubes (like shock absorbers) allow restricted (3 mm) axial movement without direct joint surface contact. (B) Clinical evaluation presented by the total WOMAC and Visual Analogue Scale (VAS) pain, means±SD are given. Distraction is performed during the first 2 months, at 3 months (1 month after removal of the fixator) pain has decreased and the WOMAC score has increased, sustaining for at least 12 months. (C) WOMAC subscales. **Indicates statistical significance of p<0.01, ***p<0.001. WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.
Figure 2
Figure 2
Joint space width (JSW) (KIDA measurement; mean±SD). Minimum JSW (min) continuously increased after distraction. The mean JSW of the affected (OA) compartment also increased over time. The mean JSW of the less affected compartment (NA), did not change over time. Subchondral bone density (KIDA, as mm aluminium (Al) equivalents; using a reference). The affected (OA) compartment showed a decrease in bone density, the less affected compartment (NA) did not. *p<0.05, **p<0.01. Representative radiographs before and 3 years after distraction; clear increase in JSW in affected (OA) compartment. KIDA, Knee Images Digital Analysis; OA, osteoarthritis.
Figure 3
Figure 3
Representative image of single slides before and 1 year after treatment, showing an increase in cartilage tissue in the affected compartment. Quantitative MRI analysis of cartilage of the affected compartment of the individual 20 patients (grey lines) at baseline (BL) and after 1 year of follow-up (1 YR). Black lines indicate mean values. ThCtAB, thickness of cartilage over total area of bone; dABp, area of denuded bone (both **p<0.01); ThCcAB, thickness of cartilage over area of bone covered with cartilage (p<0.062).
Figure 4
Figure 4
Correlations between the changes (compared with baseline) in cartilage thickness (ThCtAB; mm) and area of denuded bone (dABp; %) on MRI and the change in serum N-propeptide of type IIA procollagen (PIIANP; ng/ml) between 6 months and 1 year of follow-up. **p<0.01. ThCtAB, thickness of cartilage over total area of bone.

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