Joint distraction for knee osteoarthritis without alignment correction

4 Efficacy

This section describes efficacy outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.

4.1 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).

4.2 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).

4.3 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).

4.4 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).

4.5 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.

4.6 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.