Evaluation of placebo fidelity and trial design methodology in placebo-controlled surgical trials of musculoskeletal conditions: a systematic review

Delivering Load-Modifying Gait Retraining Interventions via Telehealth in People With Medial Knee Osteoarthritis: A Pilot Randomized Placebo-Controlled Clinical Trial

We aimed to investigate the effects of delivering 3 gait retraining interventions (toe-in, toe-out, and placebo gait) on proxy measures of medial knee load (early- and late-stance peak knee adduction moment [KAM], KAM impulse, and varus thrust) in people with knee osteoarthritis, using a hybrid model of face-to-face and telehealth-delivered sessions over 5 months. This was an originally planned 3-arm randomized placebo-controlled clinical trial. However, during the 2021 COVID-19 outbreak and lockdown in Sydney, Australia, the study became a pilot randomized controlled trial with the remainder of interventions delivered via telehealth. Nine individuals with symptomatic medial knee osteoarthritis were allocated to receive either a toe-in, toe-out, or posture re-education (placebo) gait retraining intervention. Primary outcomes of early- and late-stance peak KAM, KAM impulse, and varus thrust were assessed at baseline and follow-up. Eight participants returned for their follow-up gait assessment. Participants in both active intervention groups (toe-in and toe-out) achieved foot progression angle changes at follow-up. Overall, knee biomechanics in the placebo group did not change at follow-up. It is possible to achieve biomechanical changes in individuals with medial knee osteoarthritis when delivering gait retraining interventions via a hybrid model of face-to-face and telehealth.

Challenges of conducting a randomised placebo-controlled trial of spinal surgery: the SUcceSS trial of lumbar spine decompression

Although placebo-controlled trials are considered the gold standard for evaluating the efficacy of healthcare interventions, they can be perceived to be controversial and challenging to conduct for surgical treatments. The SUcceSS trial is the first placebo-controlled trial of lumbar decompression surgery for symptomatic lumbar canal stenosis. The SUcceSS trial has experienced common issues affecting the implementation of randomised placebo-controlled surgery trials, accentuated by the COVID-19 pandemic. Using the SUcceSS trial as an example, we discuss key challenges and mitigation strategies specific to the conduct of a randomised placebo-controlled surgical trial. Overall, the key lessons learned were (i) involving key stakeholders early and throughout the trial design phase may increase clinician and patient willingness to participate in a placebo-controlled trial of surgical interventions, (ii) additional resources (e.g. budget, staff time) are likely required to successfully operationalise trials of this nature, (iii) the level of placebo fidelity, timing of randomisation relative to intervention delivery, and nuances of the surgical procedure under investigation should be considered carefully. Findings are based on one example of a placebo-controlled surgical trial; however, researchers may benefit from employing or building from the strategies described and lessons learned when designing or implementing future trials of this nature.

Toe-in and toe-out gait retraining interventions to reduce proxy measures of medial knee joint load in people with medial knee osteoarthritis: Protocol for a randomised placebo-controlled trial

OBJECTIVE

Our primary aim is to determine the effect of a six-week toe-in, toe-out and active placebo gait retraining program on proxy measures of medial knee joint load and varus thrust in people with medial knee osteoarthritis. Our secondary aim is to determine the intervention effects on patient reported outcomes and physical function and determine if changes are maintained at three-months follow-up.

METHODS

We will conduct a three-arm randomised placebo-controlled trial. Ninety participants with medial knee osteoarthritis will be randomised and stratified via varus thrust status (presence/absence) to: toe-in, toe-out or placebo gait retraining (an intervention that does not change proxy measures of medial knee joint load). The intervention involves weekly clinician-supervised sessions with biofeedback, knee osteoarthritis education, motor learning and behaviour change principles, and daily gait retraining practice. Primary outcomes are proxy measures of medial knee joint load: knee adduction moment (early- and late-stance peaks and impulse), and varus thrust (presence/absence). Secondary outcomes include pain, physical function, medication and health care utilisation, quality of life, work ability, treatment blinding, intervention credibility and other biomechanical outcomes. Assessment timepoints are at baseline, six weeks (post intensive training), and three-months following the six-week intervention.

CONCLUSION

Our trial will determine whether toe-in or toe-out gait retraining is most effective at reducing proxy measures of medial knee joint load and varus thrust in people with medial knee osteoarthritis. This study will also evaluate if toe-in or toe-out gait retraining interventions are superior at improving pain, physical function and quality of life compared to placebo.

CLINICAL TRIAL REGISTRATION

This clinical trial protocol is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12621000414819).

Further considerations for placebo controls in surgical trials

The use of invasive placebo controls in surgical trials can be challenging. The ASPIRE guidance, published in the Lancet in 2020, provided advice for the design and conduct of surgical trials with an invasive placebo control. Based on a more recent international expert workshop in June 2022, we now provide further insights into this topic. These include the purpose and design of invasive placebo controls, patient information provision and how findings from these trials may be used to inform decision-making.