OBJECTIVE To report the clinical spectrum seen in young abusers of street‐ketamine (regular recreational abusers of street‐ketamine, for its hallucinogenic effects) in Hong Kong, presenting with significant lower urinary tract symptoms (LUTS) but with no evidence of bacterial infection. PATIENTS AND METHODS We retrospectively analysed the clinical presentations, pelvic pain and urgency/frequency scores, video‐urodynamic studies, cystoscopy findings, histological features of bladder biopsies and radiological findings of 59 ketamine abusers who were referred to the urology units of Princess Margaret and Tuen Mun Hospital, Hong Kong, from March 2000 to December 2007. RESULTS Of the 59 patients, all had moderate to severe LUTS, i.e. frequency, urgency, dysuria, urge incontinence and occasionally painful haematuria. Forty‐two (71%) patients had a cystoscopy that showed various degrees of epithelial inflammation similar to that seen in chronic interstitial cystitis. All of 12 available bladder biopsies had histological features resembling those of interstitial cystitis. Urodynamically, either detrusor overactivity or decreased bladder compliance with or without vesico‐ureteric reflux was detected to some degree in all of 47 patients. Thirty patients (51%) had unilateral or bilateral hydronephrosis on renal ultrasonography, and four (7%) showed features suggestive of papillary necrosis on radiological imaging. Eight patients had a raised serum creatinine level. CONCLUSION A syndrome of cystitis and contracted bladder can be associated with street‐ketamine abuse. Secondary renal damage can occur in severe cases which might be irreversible, rendering patients dependent on dialysis. The present data do not establish the precise cause nor the incidence. Street‐ketamine abuse is not only a drug problem, but might be associated with a serious urological condition causing a significant burden to healthcare resources.

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Stainless steel and titanium alloys are the most common metallic orthopedic materials. Recently, nickel-titanium (NiTi) shape memory alloys have attracted much attention due to their shape memory effect and super-elasticity. However, this alloy consists of equal amounts of nickel and titanium, and nickel is a well known sensitizer to cause allergy or other deleterious effects in living tissues. Nickel ion leaching is correspondingly worse if the surface corrosion resistance deteriorates. We have therefore modified the NiTi surface by nitrogen plasma immersion ion implantation (PIII). The surface chemistry and corrosion resistance of the implanted samples were studied and compared with those of the untreated NiTi alloys, stainless steel, and Ti-6Al-4V alloy serving as controls. Immersion tests were carried out to investigate the extent of nickel leaching under simulated human body conditions and cytocompatibility tests were conducted using enhanced green fluorescent protein mice osteoblasts. The X-ray photoelectron spectroscopy results reveal that a thin titanium nitride (TiN) layer with higher hardness is formed on the surface after nitrogen PIII. The corrosion resistance of the implanted sample is also superior to that of the untreated NiTi and stainless steel and comparable to that of titanium alloy. The release of nickel ions is significantly reduced compared with the untreated NiTi. The sample with surface TiN exhibits the highest amount of cell proliferation whereas stainless steel fares the worst. Compared with coatings, the plasma-implanted structure does not delaminate as easily and nitrogen PIII is a viable way to improve the properties of NiTi orthopedic implants.

Ketamine cystitis is an emerging medical condition that requires a multi-disciplinary approach to manage the patients. Simple surgical management of the physical component of the contracted bladder may produce only suboptimal results, and could even cause further problems in some patients. The importance of compliance with post-operative care and abstinence from drug use should be stressed to the patients before surgery. In view of the high complication rate, the option of a simple ileal conduit should also be discussed prior to surgical intervention.

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