Prosthetic joint infection (PJI) may be underreported because of difficulty in making a diagnosis, especially in infections with low-virulence organisms. Reports of PJI cases misdiagnosed as aseptic loosening suggest that current screening and diagnostic tools are not sensitive enough to detect all infections and that PJI likely is underdiagnosed. We reviewed the literature on recently developed novel synovial biomarkers and polymerase chain reaction (PCR) technologies, of which several have proved promising as highly sensitive and specific tools for detecting PJI. We followed the recommendations of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Of 90 papers screened by title or abstract and then by full text, 15 met our inclusion criteria. Sensitivities reported in the included studies ranged from 63% to 100% for α-defensin, from 46.8% to 90.9% for interleukin 6, from 28.6% to 100% for leukocyte esterase, and from 67.10% to 95.7% for PCR. Specificities ranged from 95% to 100% for α-defensin, from 85.7% to 97.6% for interleukin 6, from 63.6% to 96.5% for leukocyte esterase, and from 12.3% to 97.8% for PCR. α-Defensin is a highly sensitive and specific screening tool that may help improve the accuracy of PJI detection, particularly in low-grade infections.