Risk factors of recurrent hamstring injuries: a systematic review.

BACKGROUND: Although recurrent hamstring injury is a frequent problem with a significant impact on athletes, data on factors determining the risk for a recurrent hamstring injury are scarce. OBJECTIVE: To systematically review the literature and provide an overview of risk factors for re-injury of acute hamstring muscle injuries. STUDY DESIGN: Prospective studies on risk factors for re-injury following acute hamstring injuries were systematically reviewed. Medical databases and reference lists of the included articles were searched. Two reviewers independently selected potential studies and assessed methodological quality; one reviewer extracted the data. A best-evidence synthesis of all studied risk factors was performed. RESULTS: Of the 131 articles identified, five prospective follow-up studies fulfilled our inclusion criteria. These studies reported a recurrence incidence of 13.9-63.3% in the same playing season up to 2 years after initial injury. Limited evidence for three risk factors and one protective factor for recurrent hamstring injury was found; patients with a recurrent hamstring injury had an initial injury with a larger volume size as measured on MRI (47.03 vs 12.42 cm(3)), more often had a Grade 1 initial trauma (Grade 0: 0-30.4%; Grade 1: 60.9-100%; Grade 2: 8.7%) and more often had a previous ipsilateral anterior cruciate ligament (ACL) reconstruction (66.6% vs 17.1%) independent of graft selection. Athletes in a rehabilitation programme with agility/stabilisation exercises rather than strength/stretching exercises had a lower risk for re-injury (7.7% vs 70%). No significant relationship with re-injury was found for 11 related determinants. There was conflicting evidence that a larger cross-sectional area is a risk factor for recurrent hamstring injury. CONCLUSIONS: There is limited evidence that athletes with a larger volume size of initial trauma, a Grade 1 hamstring injury and a previous ipsilateral ACL reconstruction are at increased risk for recurrent hamstring injury. Athletes seem to be at lower risk for re-injury when following agility/stabilisation exercises.

IL4-10 Fusion Protein Shows DMOAD Activity in a Rat Osteoarthritis Model.

OBJECTIVE: Ideally, disease-modifying osteoarthritis (OA) drugs (DMOAD) should combine chondroprotective, anti-inflammatory, and analgesic effects in a single molecule. A fusion protein of interleukin-4 (IL-4) and IL-10 (IL4-10 FP) possesses these combined effects. In this study, the DMOAD activity of rat IL4-10 FP (rIL4-10 FP) was tested in a rat model of surgically induced OA under metabolic dysregulation. DESIGN: rIL4-10 FP was produced with HEK293F cells. Bioactivity of purified rIL4-10 FP was determined in a whole blood assay. Male Wistar rats (n = 20) were fed a high-fat diet (HFD) to induce metabolic dysregulation. After 12 weeks, OA was induced according to the Groove model. Two weeks after OA induction, rats were randomly divided into 2 groups and treated with 10 weekly, intra-articular injections of either rIL4-10 FP (n = 10) or phosphate buffered saline (PBS; n = 10). Possible antibody formation was evaluated using ELISA, cartilage degeneration and synovial inflammation were evaluated by histology and mechanical allodynia was evaluated using the von Frey test. RESULTS: Intra-articular injections with rIL4-10 FP significantly reduced cartilage degeneration (P = 0.042) and decreased mechanical allodynia (P < 0.001) compared with PBS. Only mild synovial inflammation was found (nonsignificant), limiting detection of putative anti-inflammatory effects. Multiple injections of rIL4-10 FP did not induce antibodies against rIL4-10 FP. CONCLUSION: rIL4-10 FP showed chondroprotective and analgesic activity in a rat OA model with moderate cartilage damage, mild synovial inflammation, and pain. Future studies will need to address whether less frequent intra-articular injections, for example, with formulations with increased residence time, would also lead to DMOAD activity.

Local and systemic inflammatory lipid profiling in a rat model of osteoarthritis with metabolic dysregulation.

OBJECTIVE: Bioactive oxidised lipids (oxylipins) are important signalling mediators, capable of modulating the inflammatory state of the joint and anticipated to be of importance in joint homeostasis and status of osteoarthritis. The aim of this study was to quantify oxylipin levels in plasma and synovial fluid from rats with experimentally induced osteoarthritis to investigate the potential role of oxylipins as a marker in the disease process of early osteoarthritis. DESIGN: Forty rats were randomly allocated to a standard or high-fat diet group. After 12 weeks, local cartilage damage was induced in one knee joint in 14 rats of each diet group. The remaining 6 rats per group served as controls. At week 24, samples were collected. Oxylipin levels were quantified by liquid chromatography-mass spectrometry. RESULTS: Overall, 31 lipid-derived inflammatory mediators were detected in fasted plasma and synovial fluid. Principal component analysis identified four distinct clusters associated with histopathological changes. Diet induced differences were evident for 13 individual plasma oxylipins, as well as 5,6-EET in synovial fluid. Surgical-model induced differences were evident for three oxylipins in synovial fluid (15-HETE, 8,9-DHET and 17R-ResolvinD1) with a different response in lipid concentrations for synovial fluid and plasma. CONCLUSIONS: We demonstrate the quantification of oxidised lipids in rat plasma and synovial fluid in a model of early experimental osteoarthritis. Oxylipins in the synovial fluid that were altered as consequence of the surgically induced osteoarthritis were not represented in the plasma. Our findings suggest differential roles of the oxylipins in the local versus peripheral compartment.

Controlled release of celecoxib inhibits inflammation, bone cysts and osteophyte formation in a preclinical model of osteoarthritis.

Major hallmarks of osteoarthritis (OA) are cartilage degeneration, inflammation and osteophyte formation. COX-2 inhibitors counteract inflammation-related pain, but their prolonged oral use entails the risk for side effects. Local and prolonged administration in biocompatible and degradable drug delivery biomaterials could offer an efficient and safe treatment for the long-term management of OA symptoms. Therefore, we evaluated the disease-modifying effects and the optimal dose of polyesteramide microspheres delivering the COX-2 inhibitor celecoxib in a rat OA model. Four weeks after OA induction by anterior cruciate ligament transection and partial medial meniscectomy, 8-week-old female rats (n = 6/group) were injected intra-articular with celecoxib-loaded microspheres at three dosages (0.03, 0.23 or 0.39 mg). Unloaded microspheres served as control. During the 16-week follow-up, static weight bearing and plasma celecoxib concentrations were monitored. Post-mortem, micro-computed tomography and knee joint histology determined progression of synovitis, osteophyte formation, subchondral bone changes, and cartilage integrity. Systemic celecoxib levels were below the detection limit 6 days upon delivery. Systemic and local adverse effects were absent. Local delivery of celecoxib reduced the formation of osteophytes, subchondral sclerosis, bone cysts and calcified loose bodies, and reduced synovial inflammation, while cartilage histology was unaffected. Even though the effects on pain could not be evualated directly in the current model, our results suggest the application of celecoxib-loaded microspheres holds promise as novel, safe and effective treatment for inflammation and pain in OA.