Background: The effectiveness of intra-articular platelet-rich plasma (PRP) injections has been evaluated in knee chondroplasty and osteoarthritis (OA); however, little evidence of its efficacy in hip OA exists. Purpose: To compare the therapeutic efficacy of autologous PRP, hyaluronic acid (HA), or a combination of both (PRP+HA) in hip OA. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: Patients aged between 18 and 65 years who were treated with outpatient surgery and who had hip OA and pain intensity at baseline of >20 on a 100-mm visual analog scale (VAS) were recruited for this study. Exclusion criteria were extensive surgery; presence of excessive deformities; or rheumatic, infective, cardiovascular, or immune system disorders. The primary outcome measure was a change in pain intensity as assessed by the VAS at 2, 6, and 12 months after treatment. Secondary outcome measures were the Harris Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and concentration of growth factors in PRP and their correlation with clinical outcomes. Clinical outcomes were evaluated by assessors and collectors blinded to the type of treatment administered. Results: A total of 111 patients were randomly assigned to 3 groups and received 3 weekly injections of either PRP (44 patients), PRP+HA (31 patients), or HA (36 patients). At all follow-ups, the PRP group had the lowest VAS scores. In particular, at 6-month follow-up, the mean VAS score was 21 (95% CI, 15-28) in the PRP group, 35 (95% CI, 26-45) in the PRP+HA group, and 44 (95% CI, 36-52) in the HA group ( P < .0005 [PRP vs HA] and P = .007 [PRP vs PRP+HA]; F = 0.663). The WOMAC score of the PRP group was significantly better at 2-month follow-up (mean, 73; 95% CI, 68-78) and 6-month follow-up (mean, 72; 95% CI, 67-76) but not at 12-month follow-up. A significant, “moderate” correlation was found between interleukin-10 and variations of the VAS score ( r = 0.392; P = .040). Significant improvements were achieved in reducing pain and ameliorating quality of life and functional recovery. Conclusion: Results indicated that intra-articular PRP injections offer a significant clinical improvement in patients with hip OA without relevant side effects. The benefit was significantly more stable up to 12 months as compared with the other tested treatments. The addition of PRP+HA did not lead to a significant improvement in pain symptoms.

Limited joint mobility is frequently observed in elderly people and in patients suffering from diabetes, who represent a growing segment of the population of western countries. Our review wishes to offer the state of art about this interesting topic, which may have important clinical implications, leading to impairment of both basic and instrumental activities of daily living. The main causes of a reduced range of motion are degenerative joint diseases and increased stiffness of collagen tissue. The main biochemical abnormality, common to aging and diabetes, is the non-enzymatic glycosilation of collagen, with advanced glycation end product (AGE) formation, which in turn leads to an increase of collagen cross-links. The most extensive accumulation of AGEs occurs in tissues that contain proteins with low turnover, such as the collagen in the extracellular matrix of articular capsule, ligaments and muscle-tendon units. The increase in collagen cross-linking alters the mechanical properties of these tissues with a decrease in elasticity and tensile strength, and an increase in mechanical stiffness. Besides this, AGEs react with specific cell surface receptors (RAGEs). The engagement of the ligand by RAGEs triggers cell-specific signalling, resulting in enhanced generation of reactive oxygen species and sustained up-regulation of pro-inflammatory mediators and adhesion molecules. An appropriate control of the glucose levels and a diet rich in antioxidant agents are recommended in patients with diabetes. Stretching and strengthening programmes are widely used, in order to prevent and to reduce joint stiffness, but the improvements with physiotherapy are little and short-lasting. Several drugs, which can interfere with AGE formation and removal, or with the cellular effects of AGEs, are under study (among them pyridoxamine, an active form of Vitamin B6, AGE-breaker compounds, glucosamine, rutin and derivatives, soluble RAGE isoforms, and statins). In experimental animal models, these drugs are effective in reducing diabetic complications due to AGE formation; however, further study is necessary before their extensive use in the clinical setting.

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