Abstract: We included a total of 39 studies (36 randomised controlled trials (RCTs) and 3 quasi-RCTs) that involved a total of 2492 adults. Most studies were small (median = 59 participants). Participants' mean ages ranged from 34 years to 59 years. When reported, most participants had heel pain for several months. The trials were usually conducted in outpatient specialty clinics of tertiary care hospitals in 17 countries. Steroid injection was given with a local anaesthetic agent in 34 trials. Follow-up was from one month to over two years. With one exception, trials were assessed at high risk of bias in one or more domains, mostly relating to lack of blinding, including lack of confirmation of allocation concealment. With two exceptions, we rated the available evidence as very low quality, implying in each case that we are 'very uncertain about the estimate'. The 39 trials covered 18 comparisons, with six of the seven trials with three or four groups providing evidence towards two comparisons. Eight trials (724 participants) compared steroid injection versus placebo or no treatment. Steroid injection may lead to lower heel pain visual analogue scores (VAS) (0 to 100; higher scores = worse pain) in the short-term (< 1 month) (MD -6.38, 95% CI -11.13 to -1.64; 350 participants; 5 studies; I² = 65%; low quality evidence). Based on a minimal clinically significant difference (MCID) of 8 for average heel pain, the 95% CI includes a marginal clinical benefit. This potential benefit was diminished when data were restricted to three placebo-controlled trials. Steroid injection made no difference to average heel pain in the medium-term (1 to 6 months follow-up) (MD -3.47, 95% CI -8.43 to 1.48; 382 participants; 6 studies; I² = 40%; low quality evidence). There was very low quality evidence for no effect on function in the medium-term and for an absence of serious adverse events (219 participants, 4 studies). No studies reported on other adverse events, such as post-injection pain, and on return to previous activity. There was very low quality evidence for fewer treatment failures (defined variously as persistent heel pain at 8 weeks, steroid injection at 12 weeks, and unrelieved pain at 6 months) after steroid injection. The available evidence for other comparisons was rated as very low quality. We are therefore very uncertain of the estimates for the relative effects on people with heel pain of steroids compared with other interventions in: 1. Tibial nerve block with anaesthetic (2 trials); orthoses (4 trials); oral NSAIDs (2 trials); and intensive physiotherapy (1 trial). 2. Physical modalities: ESWT (5 trials); laser (2 trials); and radiation therapy (1 trial). 3. Other invasive procedures: locally injectable NSAID (1 trial); platelet-rich plasma injections (5 trials); autologous blood injections (2 trials); botulinum toxin injections (2 trials); cryopreserved human amniotic membrane injection (1 trial); localised peppering with a needle (1 trial); dry needling (1 trial); and mini scalpel needle release (1 trial). We are also uncertain about the estimates from trials testing different techniques of local steroid injection: ultrasonography-guided versus palpation-guided (5 trials); and scintigraphy-guided versus palpation-guided (1 trial). An exploratory analysis involving pooling data from 21 trials reporting on adverse events revealed two ruptures of plantar fascia (reported in 1 trial) and three injection site infections (reported in 2 trials) in 699 participants allocated to steroid injection study arms. Five trials reported a total of 27 participants with less serious short-term adverse events in the 699 participants allocated steroid injection study arms. Reported treatments were analgesia, ice or both. Given the high risk of selective reporting for these outcomes and imprecision, this evidence was rated at very low quality. We found low quality evidence that local steroid injections compared with placebo or no treatment may slightly reduce heel pain up to one month but not subsequently. The available evidence for other outcomes of this comparison was very low quality. Where available, the evidence from comparisons of steroid injections with other interventions used to treat heel pain and of different methods of guiding the injection was also very low quality. Although serious adverse events relating to steroid injection were rare, these were under-reported and a higher risk cannot be ruled out. Further research should focus on establishing the effects (benefits and harms) of injected steroids compared with placebo in typical clinical settings, subsequent to a course of unsuccessful conservative therapy. Ideally, this should be preceded by research, including patient involvement, aimed to obtain consensus on the priority questions for treating plantar heel pain.

Plain-language summary: We included 39 studies that involved a total of 2492 adults. The average ages of the participants in the studies ranged from 34 years to 59 years. When reported, most participants had heel pain for several months. Studies were usually conducted in outpatient specialty clinics of hospitals in 17 countries. Steroid injections were usually given with a local anaesthetic agent. Study follow-up was from one month to over two years. The studies compared steroid injection with placebo or no treatment (8 studies); tibial nerve block with anaesthetic (2 studies); heel pads (4 studies); oral anti-inflammatory drugs (NSAIDs) (2 studies); an intensive exercise programme (1 study); shock wave therapy (5 studies); laser (2 studies); radiation therapy (1 study); local NSAID injection (1 study); platelet-rich plasma injections (5 studies); injection of the person's own (autologous) blood (2 studies); botulinum toxin (Botox) injections (2 studies); frozen (cryopreserved) human amniotic membrane injection (1 study); localised peppering involving multiple pricking of the tissues using an inserted needle (1 study); dry needling (1 study); and mini scalpel-needle release (1 study). We also compared different techniques of local steroid injection (5 studies). The eight studies comparing steroid injection with placebo or no steroid injection control provided evidence on heel pain, function, serious adverse events and treatment failure. No studies reported on time to return to work or other activities or short-term adverse events, such as injection-site pain. Steroid injection may slightly reduce heel pain for up to one month after treatment, but not in the longer term including up to six months. We are very unsure whether steroid injection affects longer-term function or reduces treatment failure. There were no serious adverse events, such as infection, reported by these studies. However, these are known to be rare events and we looked at the evidence from all of the studies in the review. Of the 21 studies that reported on adverse events, two studies reported three infections and two ruptures of heel tissues in relation to steroid injection. The evidence for all reported outcomes, including heel pain, for the other comparisons was always very low quality. This means we are very unsure of the results of these trials. There is low quality evidence that local steroid injections may slightly reduce heel pain up to one month but not subsequently. Although serious complications relating to steroid injection were rare, these were under-reported in the included studies and more cannot be ruled out.