「Instep, legs spread wide open with knees bent」to reveal all, with「emissions」and「gasping erection curled within a no-longer-integrated foot」describes a client and service provider in the heat of the action with her foot meat CURLED around his penis, in motion.
　「Service provider's no-longer-integrated feet」with「burning sensation」and「penis wrapped with tension and gasping」refers to the INEVITABLE CURLING of a foot with all the bones mashed into pulp around an erection in order to masturbate into the slimy skin fold created by bending the sole:「Qing Dynasty sex manuals listed 48 different ways of playing with women's bound feet.」
　　[　https://en.wikipedia.org/wiki/Foot_binding 2012-12-17　]　
　Contracting a sexually transmittable infection from a sexual service provider causes CURLING: a male human's DISEASED PENIS, not in a healthy condition. Scarring from sexually transmitted diseases can cause both a shortened penis and a bent, curled penis as is depicted by this element, especially when attempting to become erect. Gonorrhea and other such diseases cause scar tissue to form within the urethra:
　「Peyronie's Disease,…also known as 'Induratio penis plastica,' or more recently 'Chronic Inflammation of the Tunica Albuginea (CITA),' is a connective tissue disorder involving the growth of fibrous plaques in the soft tissue of the penis affecting up to 10% of men. Specifically, scar tissue forms in the tunica albuginea, the thick sheath of tissue surrounding the corpora cavernosa causing pain, abnormal curvature, erectile dysfunction, indentation, loss of girth and shortening. …The disease may cause pain. Hardened, big, cord-like lesions (scar tissue known as 'plaques'). Or abnormal curvature of the penis when erect due to chronic inflammation of the tunica albuginea (CITA). Although the popular conception of Peyronie's Disease is that it always involves curvature of the penis, the scar tissue sometimes causes divots or indentations rather than curvature. The condition may also make sexual intercourse painful and/or difficult…」
　　[　https://en.wikipedia.org/wiki/Peyronie%27s_disease 2012-08-15　]　
　Without a doubt, the Irish also have knowledge of their own to pass along in these trying times:「Masturbation will not spread coronavirus, especially if you wash your hands (and any sex toys) with soap and water for at least 20 seconds before and after.」Nonetheless and regrettably, unlike in dynastic China, it must be undertaken alone to truly be a preventative countermeasure but still achieve the desired result with some degree of safety.
　 　[　https://www.sexualwellbeing.ie/sexual-health/sex-and-coronavirus/ 2020-03-31　]　
　The Dutch, too have the same solution—it seems masturbation has become mainstream in the media the world over due to the coronavirus (it has always been 'the main stream' in reality, albeit covertly for most folks):
　「'Don't have sex with your partner if they have been isolated because of (suspected) coronavirus infection,' the RVIM says. 'Sex with yourself or with others at a distance is possible (think of telling erotic stories, masturbating together).'」
　　[　https://www.theguardian.com/world/2020/may/15/dutch-official-advice-to-single-people-find-a-sex-buddy-for-lockdown-coronavirus 2020-05-16　]　
　Needless to point out perhaps, but Chinese shamans from antiquity hit upon the same solution as a pandemic preventative countermeasure, honed for ultimate client satisfaction by utilizing naked females with no-longer-integrated feet as masturbatory sex buddies available for short-term rental with erotic visualization of live prepubescent female genitalia engaging in autoerotic stimulation herself, as a solution to the same problem facing us now, but in pre-Internet days.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: to curl up
Unihan extended: curled, coiled
EDRDG: curled; coiled