The APS group had significant improvements in lameness grade, asymmetry indices of vertical peak force, and range of joint motion by 14 days, compared with baseline or control group values. No adverse effects associated with APS treatment were evident. Clients assessed lameness and comfort as improved at 12 and 52 weeks. The APS had greater likelihood (OR, to ) of a therapeutic response in horses with a lameness score < 4, < 10% vertical force asymmetry, or absence of marked osteophyte formation, subchondral sclerosis, or joint space narrowing. Concentration of interleukin-1 receptor antagonist in APS was times that in blood.
Whichever approach is used, the actual injection site can be marked with a fingernail imprint or the barrel of a pen. Next, sterile preparation with a povidone iodine preparation (Betadine) and alcohol can be performed. A 22- to 25-gauge needle can be used for the injection. Local anesthesia with lidocaine before the injection can be used, but with a small gauge needle this is not always necessary. Alternatively, an ethyl chloride spray can be used for local anesthesia. Following puncture through the skin and into the joint space, the injection is accomplished. If resistance is encountered, redirection of the needle may be necessary.
Six articles (739 patients, 817 knees, 39% males, mean age of years, with 38 weeks average follow-up) were analyzed. All studies met minimal clinical important difference criteria and showed significant improvements in statistical and clinical outcomes, including pain, physical function, and stiffness, with PRP. All but one study showed significant differences in clinical outcomes between PRP and hyaluronic acid (HA) or PRP and placebo in pain and function. Average pretreatment Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were and for the PRP and HA groups, respectively (P = .420). Mean post-treatment WOMAC scores for PRP were significantly better than for HA at 3 to 6 months ( and , respectively; P = .0008) and at 6 to 12 months ( and , respectively; P = .0062). None of the included studies used corticosteroids.