Background. Femoroacetabular impingement (FAI) may be a predisposing factor in progression of osteoarthritis. The use of hip arthroscopy is in its infancy with very few studies currently reported. Early reports show favourable results for treatment of young patients with FAI. This prospective study over a larger age spectrum represents a significant addition to this expanding field of minimally invasive surgery. Methods. Over a twenty-two month period all patients undergoing interventional hip arthroscopy were recorded on a prospective database. Patient demographics, diagnosis, operative intervention and complications were noted. Patients were scored pre-operatively and postoperatively at 6 months and 1 year using the McCarthy score. Results. 94 patients met the criteria for inclusion in this study. Median age was 39 (15–66) years with 57.4% female, 16 patients were over the age of 50 years. At operation, 50 patients had a labral tear, 70 had cam impingement and 62 had chondral damage, with 21 of these deemed severe (grade 3 or 4). For all patients a mean increase in the McCarthy score of 14.6 (p=<0.0001) was seen at 6 months and 19.1 (p=0.0002) at 1 year postoperatively. For those over 50 years, at 6 months an increase of 11.9 (p=0.08) was seen, improving to 33.8 (p=<0.0001) at 1 year. Eight patients underwent THR, of these, 2 were over 50 years of age. All of this group of patients had chondral damage (50% judged as severe at arthroscopy). At 6 months postoperatively these patients had severe pain and their mean score worsened by −16.3 (p=0.2). Few complications were seen, 7 patients had tight access (5 males), 3 of which received chondral scuffing and 1 had the procedure abandoned, 1 patient had groin labral bruising and 2 patients had transient parasthesia. Conclusions. Patients see a gradual and significant improvement post hip arthroscopy, with symptoms continuing to improve until 1 year. This is a well-tolerated procedure with a low complication rate and the opportunity for treatment of a range of hip pathology. Patients over the age of 50 gain a significant improvement from this procedure. Two groups of patients who gain no improvement are those with inflammatory arthropathy and those with dysplastic acetabulae

Femoroacetabular impingement (FAI) is a significant cause of osteoarthritis in young active individuals but the pathophysiology remains unclear. Increasing mechanistic studies point toward an inflammatory component in OA. This study aimed to characterise inflammatory cell subtypes in FAI by exploring the phenotype and quantification of inflammatory cells in FAI versus OA samples. Ten samples of labrum were obtained from patients with FAI (confirmed pathology) during open osteochondroplasty or hip arthroscopy. Control samples of labrum were collected from five patients with osteoarthritis undergoing total hip arthroplasty. Labral biopsies were evaluated immunohistochemically by quantifying the presence of macrophages (CD68 and CD202), T cells (CD3), mast cells (mast cell tryptase) and vascular endothelium (CD34). Labral biopsies obtained from patients with FAI exhibited significantly greater macrophage, mast cell and vascular endothelium expression compared to control samples. The most significant difference was noted in macrophage expression (p<0.01). Further sub typing of macrophages in FAI using CD202 tissue marker revealed and M2 phenotype suggesting that these cells are involved in a regenerate versus a degenerate process. There was a modest but significant correlation between mast cells and CD34 expression (r=0.4, p<0.05) in FAI samples. We provide evidence for an inflammatory cell infiltrate in femoroacetabular impingement. In particular, we demonstrate significant infiltration of mast cells and macrophages suggesting a role for innate immune pathways in the events that mediate hip impingement. Further mechanistic studies to evaluate the net contribution and hence therapeutic utility of these cellular lineages and their downstream processes may reveal novel therapeutic approaches to the management of early hip impingement