Abstract: Four trials were included in the review. One new trial of botulinum toxin was identified in the updated search. Only one trial of custom-made foot orthoses fully met the inclusion criteria. Three additional studies (botulinum toxin, footwear and off-the-shelf foot orthoses), all assessing secondary outcomes were included. We could not pool data used in the four studies due to heterogeneity of diagnostic groups and outcome measures. The one trial that fully met the inclusion criteria investigated the treatment of pes cavus pain in 154 adults over three months. The trial showed a significant reduction in the level of foot pain with custom-made foot orthoses versus sham orthoses (WMD 10.90; 95% CI 3.21 to 18.59). Furthermore, a significant improvement in self-reported foot function and physical functioning was reported with custom-made foot orthoses. There was no difference in reported adverse events following the allocation of custom-made or sham orthoses. Secondary biomechanical outcomes improved with the use of custom-made foot orthoses and footwear (pedobarography), but not with intramuscular injections of botulinum toxin (radiographic) or off-the-shelf foot orthoses (electromyography). This updated review shows that custom-made foot orthoses are significantly more beneficial than sham orthoses for treating foot pain associated with pes cavus in a variety of clinical populations. We also show that some secondary biomechanical outcomes improve with custom-made foot orthoses and footwear, but not with botulinum toxin or off-the-shelf foot orthoses. There is an absence of evidence for any other type of intervention for the treatment or prevention of pes cavus.

Plain-language summary: Population based studies suggest the prevalence of pes cavus is approximately 10%, and its cause is primarily neuromuscular (for example Charcot-Marie-Tooth disease) or idiopathic (unknown) in nature. It has been estimated that 60% of people with cavus feet will experience chronic foot pain at some time in their life, most commonly beneath the forefoot (for example metatarsalgia, sesamoiditis) or heel (for example plantar fasciitis). Conditions such as these are thought to be the result of abnormal pressure distribution across the sole of the foot during walking. Many conservative therapies and surgical procedures have been recommended for cavus-related foot pain. In particular, foot orthoses (aids applied and worn on the outside of the body to support the bony structures) customised to an individual's foot shape are increasingly prescribed by podiatrists, physiotherapists, orthopaedic surgeons and rehabilitation specialists for people with pes cavus pain. This updated review analysed four relevant trials, but only one fully met the inclusion criteria. This trial with 154 adults showed that custom-made foot orthoses can reduce and redistribute plantar foot pressure and subsequently decrease foot pain by approximately 75%. Some biomechanical outcomes, such as pressure distribution, improve with custom-made foot orthoses and footwear, but many other biomechanical outcomes, such as foot alignment or muscle activity, do not improve with botulinum toxin or off-the-shelf foot orthoses, respectively. More research is needed to determine the effectiveness of other interventions for people with painful high-arched feet.