Joint distraction for knee osteoarthritis without alignment correction

A case series of 20 patients with end-stage knee osteoarthritis treated by joint distraction reported significant improvements in Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores (normalised to a 100‑point scale for total and subscales; 100 being the best score) of 70% at 1‑year follow-up and of 74% at 2‑year follow-up (p<0.001 for both improvements from baseline). The individual components of the WOMAC score (pain, stiffness and function) all improved significantly compared against baseline (p<0.005 for all 3 subscales at each time point: 3, 6, 12, 18 and 24 months). A case series of 6 patients with knee osteoarthritis treated by joint distraction reported a significant increase in the mean Japan orthopaedic association score (range from 0 to 100, with higher scores indicating better function) from 56 (range 55–60) before the procedure to 81 (range 70–85) at the latest follow-up (mean 3‑year follow-up, p<0.001).

A non-randomised comparative study of 61 patients treated by joint distraction and debridement (n=19) or debridement alone (n=42) reported a statistically significant improvement in pain (measured on a 4‑point Likert scale, with a higher score indicating more severe pain) in the joint distraction group 3–5 years after the procedure (p<0.004). In the debridement-only group, there was no statistically significant improvement in pain scores 3–5 years after the procedure (p=0.163). The case series of 20 patients reported a significant decrease in pain scores (measured on a 10‑point visual analogue scale, with a higher score indicating more severe pain) of -58% at 1‑year follow-up and of -61% at 2‑year follow-up (both improvements from baseline were significant; p<0.001).

The non-randomised comparative study of 61 patients treated by joint distraction and debridement or debridement alone reported a significant increase in walking capacity in the joint distraction group from 10–35 minutes before the procedure to 32–51 minutes 3–5 years after the procedure (p<0.001). In the debridement-only group, the walking capacity range was 12–23 minutes before the procedure and 20–31 minutes 3–5 years after the procedure (p=0.142). The non-randomised comparative study of 61 patients treated by joint distraction and debridement or debridement alone also reported a significant improvement in stair climbing in both groups. In the joint distraction group, none of the patients (0/19) had no difficulty in ascending or descending stairs before the procedure and 74% (14/19) of patients had no difficulty in stair climbing 3–5 years after the procedure (p<0.002). In the debridement-only group, 33% (13/42) of patients had no difficulty in stair climbing before the procedure and 67% (28/42) of patients had no difficulty in stair climbing 3–5 years after the procedure (p<0.001).

The case series of 20 patients reported a significant change in mean cartilage thickness from baseline for the total subchondral bone area of the most affected compartment of 0.6 mm (95% confidence interval [CI] 0.24 mm to 1.22 mm) at 1‑year follow-up (p=0.002) and of 0.4 mm (95% CI 0.06 mm to 0.83 mm) at 2‑year follow-up (p=0.03) (no further details reported).

The non-randomised comparative study of 61 patients treated by joint distraction and debridement or debridement alone reported mean joint spaces on X-ray in the joint distraction group of 2.5 mm before the procedure and of 4.3 mm 3–5 years after the procedure (p<0.001); in the debridement-only group, mean joint spaces were 2.7 mm before the procedure and 2.4 mm 3–5 years after the procedure (p=0.135). The case series of 20 patients reported a significant change in the minimum joint space width in the most affected compartment from baseline of 59% (0.57 mm, 95% CI 0.09 mm to 1.06 mm; p=0.03) after 2 years. The change in mean joint space width in the most affected compartment from baseline was 21% (0.36 mm, 95% CI 0.13 mm to 0.85 mm; p=0.11) after 2 years.

The specialist advisers listed key efficacy outcomes as improvement in pain symptoms, improved function, increase in joint space and a delay in the need for joint replacement.