Purpose. To determine the characteristics of MSCs from hip and compare them to MSCs from knee. Methods. Synovial tissues were obtained from both the knee and the hip joints in 8 patients who underwent both hip and knee arthroscopies on the same day. MSCs were isolated from the knee and hip synovial samples. The capacities of MSCs were compared between both groups. Results. The number of cells per unit weight at passage 0 of synovium from the knee was significantly higher than that from the hip (P < 0.05). While it was possible to observe the growth of colonies in all the knee synovial fluid samples, it was impossible to culture cells from any of the hip samples. In adipogenesis experiments, the frequency of Oil Red-O-positive colonies and the gene expression of adipsin were significantly higher in knee than in hip. In osteogenesis experiments, the expression of COL1A1 and ALPP was significantly less in the knee synovium than in the hip synovium. Conclusions. MSCs obtained from hip joint have self-renewal and multilineage differentiation potentials. However, in matched donors, adipogenesis and osteogenesis potentials of MSCs from the knees are superior to those from the hips. Knee synovium may be a better source of MSC for potential use in hip diseases.

Synovial cells from the cotyloid fossa synovium of patients with femoroacetabular impingement syndrome are more robust in vitro, suggesting that MSCs from this source may be strongly considered for stem cell therapy.

Background: The acetabular labrum plays important roles in proprioception, nociception, synovial fluid seal effect, and static and dynamic joint stability and as a shock absorber. Clinical and radiographic risk factors for unsalvageable labral tear in femoroacetabular impingement (FAI) are not well established. Purpose: To identify predictors of unsalvageable labral tear during initial hip arthroscopic management of FAI. Study Design: Case-control study; Level of evidence, 3. Methods: Patients were included who underwent primary hip arthroscopic treatment for FAI between March 2009 and March 2014. Patients were excluded who had <2-year follow-up, underwent bilateral surgery, or had a history of surgery, osteoarthritis (Tönnis grade 2 or 3), and other diagnoses, including lateral center-edge angle <25° diagnosed as developmental hip dysplasia. Patients were divided into 2 groups according to their labral condition: reconstruction and refixation. Unsalvageable labral tear was defined as any irreparable labral tear, including severe degenerative tear, frayed labrum, labral ossification, flattened labrum, and failed prior repair during surgery. Univariate and multivariate analyses identified risk factors for segmental labral reconstruction. Patient-reported outcome scores and postoperative revision rates were also assessed. Results: Twenty-five hips (18 male, 7 female) and 126 hips (65 male, 61 female) were included in the reconstruction and refixation groups, respectively. The mean ± SD ages were 52.6 ± 15.0 and 36.5 ± 16.1 years in the reconstruction and refixation groups, respectively. In the reconstruction group, the mean modified Harris Hip Score significantly improved from 67.3 ± 14.9 preoperatively to 95.0 ± 8.1 at final follow-up ( P < .001), and the mean Nonarthritic Hip Score improved from 63.0 ± 18.3 preoperatively to 89.5 ± 10.1 at final follow-up ( P < .001). In the refixation group, the mean modified Harris Hip Score significantly improved from 69.2 ± 18.6 preoperatively to 93.0 ± 11.2 at final follow-up ( P < .001), and the mean Nonarthritic Hip Score improved from 60.7 ± 18.8 preoperatively to 88.6 ± 15.0 at final follow-up ( P < .001). No significant difference was noted in patient-reported outcome scores and revision hip arthroscopy rates. The rate of conversion of total hip arthroplasty was higher in the reconstruction group than in the refixation group. Risk factors for unsalvageable labral tear were age ≥45 years (odds ratio [OR], 8.83; P < .007), body mass index ≥23.1 kg/m2 (OR, 13.05; P < .001), and vertical center anterior angle ≥36° (OR, 19.03; P < .001). Furthermore, in this study, unsalvageable labral tears were present in cases with at least 2 of the 3 risk factors. Conclusion: Age ≥45 years, body mass index ≥23.1 kg/m2, and vertical center anterior angle ≥36° are risk factors for unsalvageable labral tear at initial hip arthroscopic surgery for patients with FAI.

Background: There is a dearth of knowledge regarding the correlation between femoroacetabular impingement (FAI) and osteitis pubis (OP) among symptomatic soccer players. Purpose: To elucidate whether arthroscopic FAI correction is effective for young competitive soccer players with FAI combined with OP or perisymphyseal pubic bone marrow edema (BME). Study Design: Case series; Level of evidence, 4. Methods: A total of 577 consecutive patients who underwent arthroscopic FAI correction were retrospectively reviewed with a minimum 2-year follow-up. Competitive soccer players who were professional, college, and high school athletes were included. The authors assessed the modified Harris Hip Score and Nonarthritic Hip Score preoperatively and at 6 months, 1 year, and 2 years after surgery. In addition, players were divided into groups according to radiographic evidence of OP and BME (2 groups each). Clinical outcomes, return to play, and radiographic assessments were compared between groups. Results: Twenty-eight hips met the inclusion criteria. The median modified Harris Hip Score significantly improved after hip arthroscopy (81.4, preoperatively; 95.7 at 6 months, P = .0065; 100 at 1 year, P = .0098; 100 at 2 years, P = .013). The median Nonarthritic Hip Score also significantly improved (75.0, preoperatively; 96.3 at 6 months, P = .015; 98.8 at 1 year, P = .0029; 100 at 2 years, P = .015). Furthermore, 92.0% of players returned to play soccer at the same or higher level of competition at a median 5.5 months (range, 4-15 months); 67.8% had radiological confirmation of OP; and 35.7% had pubic BME. The alpha angle was significantly higher in pubic BME group than the no–pubic BME group (64.8° vs 59.2°, P = .027), although there was no significant difference between the OP and no-OP groups. The prevalence of tenderness of the pubic symphysis significantly decreased preoperatively (32.1%) to postoperatively (3.6%). Magnetic resonance imaging findings confirmed that pubic BME disappeared in all players at a median 11 months (range, 6-36) after initial surgery. Conclusions: Arthroscopic management for FAI provides favorable clinical outcomes, a high rate of return to sports, and, when present, resolution of pubic BME among competitive soccer players.

Purpose: To establish the characteristics of synovium-derived mesenchymal stem cells (MSCs) from the hip joints of patients with femoroacetabular impingement syndrome (FAIS) and osteoarthritis (OA), particularly their proliferation and differentiation potentials. We further investigated their functional differences. Methods: Synovium samples were harvested from 21 patients with FAIS who underwent hip arthroscopic surgery and from 14 patients with OA who underwent total hip arthroplasty. The MSC number, colony-forming units, cell viability, and differentiation potential were compared. Real-time polymerase chain reaction assessed the differentiation potential into adipose, bone, and cartilage tissues. Results: The number of colonies at a density of 10 4 at passage 0 from OA synovium was significantly greater than that from FAIS synovium (P < .01). However, their proliferation and viability were significantly lower than those of FAIS synovium cells (P ¼ .0495). The expression of lipoprotein lipase mRNA in OA synovium cells was greater than that in FAIS synovium cells (P < .01). Meanwhile, the fraction of colonies positive for von Kossa and alkaline phosphatase staining, as well as the level of bone gamma-carboxyglutamate protein expression in OA synovium cells, were greater than those in FAIS synovium cells (P < .01). In chondrogenic pellet culture experiments, the expression of COL10A1 mRNA was lower in OA synovium than in FAIS synovium (P < .01). Conclusions: Synovial MSCs from patients with OA had greater colony numbers but less viability and proliferative potential. They also showed greater osteogenic and adipogenic potentials, whereas those from patients with FAIS showed greater chondrogenic potential. Clinical relevance: MSCs from patients with FAIS exhibited good potential as cell sources for stem cell therapy in case of cartilage damage in the hip joint.