Heard BJ, Solbak NM, Chung M, Achari Y, Shrive NG, Frank CB, Hart DA. The infrapatellar fat pad is affected by injury induced inflammation in the rabbit knee: use of dexamethasone to mitigate damage.
Inflamm Res 2016;
65:459-70. [PMID:
26898767 DOI:
10.1007/s00011-016-0928-z]
[Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 02/08/2016] [Accepted: 02/10/2016] [Indexed: 01/22/2023] Open
Abstract
OBJECTIVE AND DESIGN
The health of the infrapatellar fat pad (IFP) has been linked to pain, joint inflammation, and the onset of post-traumatic osteoarthritis. Thus, early inflammation effects on the IFP could have long term sequelae on joint integrity. This study was designed to characterize the natural history of the IFP in a model of surgically induced knee injury and inflammation, and to test the efficacy of one intra-articular (IA) administration of dexamethasone (DEX) immediately following surgery.
METHODS
An IA bone drill hole injury to the rabbit knee was conducted and immediately treated with DEX (n = 12). Early and late post-surgical time-points were investigated (48 h and 9 weeks) and the outcome measures were analysis of IFP histology, mRNA levels for relevant molecules, and protein levels for a subset of cytokines. Data were analyzed against a surgical control (injury without treatment; n = 12), a surgical sham (capsular incision only; n = 12), and normal control (n = 6).
TREATMENT
Single IA injection of DEX (0.5 mg/kg), administered at the completion of surgery.
RESULTS
IFPs from injured joints exhibited significantly increased cellularity and early fibrosis at 48 h post surgery. While the histological inflammation from a capsular incision alone resolved, knee injured animals progressed to a significantly more fibrotic IFP by 9 weeks. DEX significantly lowered histological scores at 48 h, but not at the 9 weeks. DEX did not influence mRNA levels for IL-1β, 6, and 8, however, protein analysis indicated that IL-8 levels were lower in DEX treated joints. DEX resulted in significantly elevated expression of mRNA for MCP-1, leptin, and VEGF.
CONCLUSION
One IA administration of a glucocorticoid appears to mitigate the initial inflammation within the joint, but is not sufficient to protect the joint to 9 weeks post-surgery.
Collapse