4 Efficacy

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 99 patients with symptomatic medial knee osteoarthritis refractory to conservative treatment who received a load absorber reported improvements in the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire (WOMAC). Statistically significant mean improvements of 56%, 50% and 38% were observed for the WOMAC pain, function and stiffness scales respectively (all p<0.001) during a mean follow‑up period of 17 months. All WOMAC domain scores improved significantly during this follow‑up period (p<0.01), independent of age, gender, BMI or disease severity (K–L grade). WOMAC clinical success rates (defined as 20% or more improvement from baseline) were 78% for pain, 78% for function and 69% for stiffness.

4.2 The case series of 99 patients reported that knee pain severity improved significantly after the procedure, from 59±19 at baseline to 23±22 (assessed on a 0–100 visual analogue scale) at 1 year, representing a 60% reduction in pain (p<0.001). The authors reported that the percentage of patients achieving the 'minimal clinically important difference' for pain severity increased throughout the follow‑up period, from 60% at 6 weeks to 76% at 1 year.

4.3 The case series of 99 patients reported that the mean range of motion of the knee decreased from 119°±13° at baseline to 105°±19° at 6 weeks after the operation. It gradually increased to baseline levels at 1‑year follow‑up.

4.4 The case series of 99 patients reported that all devices were successfully implanted and activated.

4.5 The specialist advisers listed key efficacy outcomes as reduction in knee pain, improved function and activity, patient‑reported outcomes (for example, Oxford Knee Score; WOMAC scores; Knee Society Score; University of California Los Angeles activity score; EQ‑5D; patient satisfaction scales) and delayed need for knee replacement.

  • National Institute for Health and Care Excellence (NICE)