Contamination of joints with tissue debris and hair after arthrocentesis: the effect of needle insertion angle, spinal needle gauge, and insertion of spinal needles with and without a stylet

Comparison of equine synovial sepsis rate following intrasynovial injection in ambulatory versus hospital settings

BACKGROUND

Frequency of synovial sepsis in horses following intrasynovial injection has been reported, but not compared with respect to the environment in which the injection was performed.

OBJECTIVES

To describe occurrence of synovial sepsis following intrasynovial injections performed in ambulatory vs hospital settings.

STUDY DESIGN

Retrospective cohort study.

METHODS

Records from the Colorado State University were evaluated (2014-2018) and horses receiving intrasynovial injections were identified. Patients presenting for septic synovial structures were excluded. Patient signalment, primary supervising service, medications injected, location (field/hospital), whether synovial sepsis resulted, and at what time sepsis was recognised were recorded. Logistic regression was used to estimate the contributions of covariates to the occurrence of synovial sepsis following injection.

RESULTS

During the study period, 3866 intrasynovial injections were performed in 1112 horses during 1623 sessions, with 643/1623 sessions performed in the field. The most frequently used medications were hyaluronate (846/1623, 52.1%), triamcinolone acetonide (780 /1623, 48.1%) and amikacin sulfate (684/1623, 42.1%). Four horses developed synovial sepsis (0.2% sessions, 0.1% synovial structures); 3/4 were injected in the field, 2/4 received antibiotics with the injection. The frequency of septic synovitis was 10.4 cases per 10 000 injections, or 1 in 967 injections. All horses recovered following synovial lavage and antibiotic therapy. Performing injections in the field (P = .2) or without antibiotics (P = .7) did not alter the risk of synovial sepsis.

MAIN LIMITATIONS

Limitations include the retrospective nature of data collection and low rate of infection overall, which prohibited evaluation of individual medication regimes as factors associated with resultant infection.

CONCLUSIONS

The frequency of synovial sepsis in this population of horses was not higher when injections were performed in the field or without concurrent antibiotic administration. These data may help to inform practitioners and clients regarding the relative potential risk of complications following intrasynovial medication in different environmental settings.

Investigation of synovial fluid lubricants and inflammatory cytokines in the horse: a comparison of recombinant equine interleukin 1 beta-induced synovitis and joint lavage models

BACKGROUND

Lameness is a debilitating condition in equine athletes that leads to more performance limitation and loss of use than any other medical condition. There are a limited number of non-terminal experimental models that can be used to study early inflammatory and synovial fluid biophysical changes that occur in the equine joint. Here, we compare the well-established carpal IL-1β-induced synovitis model to a tarsal intra-articular lavage model, focusing on serial changes in synovial fluid inflammatory cytokines/chemokines and the synovial fluid lubricating molecules lubricin/proteoglycan 4 and hyaluronic acid. The objectives of this study were to evaluate clinical signs; synovial membrane and synovial fluid inflammation; and synovial fluid lubricants and biophysical properties in response to carpal IL-1β synovitis and tarsal intra-articular lavage.

RESULTS

Hyaluronic acid (HA) concentrations, especially high molecular weight HA, and synovial fluid viscosity decreased after both synovitis and lavage interventions. Synovial fluid lubricin concentrations increased 17-20-fold for both synovitis and lavage models, with similar changes in both affected and contralateral joints, suggesting that repeated arthrocentesis alone resulted in elevated synovial fluid lubricin concentrations. Synovitis resulted in a more severe inflammatory response based on clinical signs (temperature, heart rate, respiratory rate, lameness and joint effusion) and clinicopathological and biochemical parameters (white blood cell count, total protein, prostaglandin E2, sulfated glycosaminoglycans, tumor necrosis factor-α and CC chemokine ligands - 2, - 3, - 5 and - 11) as compared to lavage.

CONCLUSIONS

Synovial fluid lubricin increased in response to IL-1β synovitis and joint lavage but also as a result of repeated arthrocentesis. Frequent repeated arthrocentesis is associated with inflammatory changes, including increased sulfated glycosaminoglycan concentrations and decreased hyaluronic acid concentrations. Synovitis results in more significant inflammatory changes than joint lavage. Our data suggests that synovial fluid lubricin, TNF-α, CCL2, CCL3, CCL5, CCL11 and sGAG may be useful biomarkers for synovitis and post-lavage joint inflammation. Caution should be exercised when performing repeated arthrocentesis clinically or in experimental studies due to the inflammatory response and loss of HA and synovial fluid viscosity.

Influence of clipping on bacterial contamination of canine arthrocentesis sites before and after skin preparation

OBJECTIVE

To determine the influence of hair removal as part of the aseptic skin preparation of canine arthrocentesis sites and to characterize the bacterial flora remaining after aseptic skin preparation.

STUDY DESIGN

Randomized controlled trial.

STUDY POPULATION

Thirteen shorthaired beagle-cross dogs.

METHODS

A coin toss was used to randomly determine to have one carpus, elbow, tarsus, and stifle clipped. The contralateral side was left unclipped. Aseptic skin preparation was performed on all sites with 4% chlorhexidine followed by 70% isopropyl alcohol. The skin of each site was sampled for aerobic and anaerobic bacterial cultures before and after aseptic skin preparation. Bacterial cultures were submitted for laboratory testing to determine the colony-forming units (CFU) of bacteria and bacterial species isolated for each site.

RESULTS

Each group (clipped and unclipped) included 52 sites. Aseptic skin preparation reduced bacterial CFU in both groups. There was no association between values for CFU per milliliter after skin preparation of dogs and side (P = .07), joint (P = .71), pre-aseptic skin preparation CFU (P = .94), or clipping (P = .42). Staphylococcus spp were the most common of the bacterial species cultured.

CONCLUSION

In clean shorthaired dogs without visible evidence of dermatological disease, leaving arthrocentesis sites unclipped rather than performing traditional surgical clipping did not result in increased bacterial skin counts after aseptic skin preparation.

CLINICAL SIGNIFICANCE

In this study we did not find evidence to support that clipping of canine arthrocentesis sites is required for effective aseptic skin preparation. A prospective clinical trial is required to determine whether a change in practice would be associated with increased morbidity.

Synovial sepsis is rare following intrasynovial medication in equine ambulatory practice

BACKGROUND

There are few observational studies regarding the potentially serious complication of synovial sepsis following intrasynovial medication in general equine practice. Quantification of risk is fundamental to fully inform decision-making and owner consent prior to undertaking procedures.

OBJECTIVES

To describe the occurrence of synovial sepsis following intrasynovial injections in a large ambulatory equine practice between 2006-2011.

STUDY DESIGN

Retrospective cohort study.

METHODS

Medication records were cross-referenced against synovial cytology submissions and hospital admissions for synovial sepsis. The occurrence of synovial sepsis within strata of interest, including horse age, sex and product used were described as proportions with corresponding 95% confidence intervals, and measures of attributable risks.

RESULTS

In the study period, 9456 intrasynovial medications were performed in 4331 sessions. The most frequently used medications were: corticosteroids (3869/4331, 89.3% [95% CI 88.4, 90.3%]), hyaluronate (3617/4331, 83.5% [95% CI 82.4, 84.6%]) and amikacin sulphate (4044/4331, 93.4% [95% CI 92.6, 94.1%]). Overall four horses developed post medication synovial sepsis (0.04% [95% CI 0.0, 0.08%] of all medications), two of these cases were given polysulphated glycosaminoglycans and hyaluronate (2/14, 14.3% [95% CI 0.0, 32.6%]), two were given triamcinolone acetonide (2/3592, 0.1% [95% CI 0.0, 0.1%]), and hyaluronate (2/3617, 0.06% [95% CI 0.0, 0.1%]). One of these cases had received concurrent medication with amikacin sulphate (1/4044, 0.02% [95% CI 0.0, 0.1%]). All four cases returned to racing following joint lavage.

MAIN LIMITATIONS

Due to the low frequency of cases multivariable statistical analysis was not performed. Although the study was conducted in an ambulatory setting, the population included a high number of racehorses, limiting application to the general horse population.

CONCLUSIONS

The frequency of synovial sepsis in this population of horses was 0.04%. These data may be helpful in informing clients regarding the potential risks of adverse complications resulting from intrasynovial medication.

False-positive Cultures After Native Knee Aspiration: True or False

BACKGROUND

Synovial fluid aspiration is a routine practice used by most orthopaedic surgeons to aid in the diagnosis of joint infection. In patients for whom there is a low pretest probability of infection, a positive culture-particularly if it is a broth-only culture-may be considered a contaminant, especially if the bacterial species are skin pathogens. To our knowledge no study has evaluated the incidence of contamination of aspirations from the native knee.

QUESTIONS/PURPOSES

What is the frequency of false-positive cultures among knee aspirations of the native knee?

METHODS

Two hundred patients, with a total of 200 knees, with the diagnosis of degenerative osteoarthritis undergoing a total knee arthroplasty (TKA) were identified for this study. None of these patients had symptoms, signs, or laboratory studies to suggest the presence of joint infection; a positive culture in this population therefore would be considered contaminated. Thirty-two (16%) patients were excluded secondary to a dry aspiration. One patient was enrolled in the study but did not have the knee aspirated and another patient's specimen was accidentally discarded. Each knee was aspirated under sterile conditions before performing the TKA. The fluid was sent for cell count and culture. If insufficient fluid was obtained for both cell count and culture, culture was performed rather than cell count.

RESULTS

There were no false-positive cultures (zero of 166 [0%]) in aspirations of native knees.

CONCLUSIONS

Our study would indicate that when done properly under sterile technique, cultures taken from knee arthrocentesis in patients without prosthetic joints should not be affected by perceived contaminant species. A positive specimen finding on culture should raise a strong suspicion of bacterial septic arthritis. Future studies should include more specimens as well as knees with prior TKA to help further identify the rate of false-positive cultures in knee arthrocentesis in both populations.

LEVEL OF EVIDENCE

Level I, diagnostic study.