The modified Kocher criteria for septic hip: Does it apply to the knee?

Abstract

Background: Pediatric septic arthritis is a surgical emergency and timely diagnosis prevents serious complications. To differentiate between septic hip and transient synovitis, the predictive value of four original Kocher criteria (fever, inability to bear weight, elevated serum white blood cell count, and elevated erythrocyte sedimentation rate) plus Caird’s addition of elevated C-reactive protein have been studied, termed the modified Kocher criteria. These criteria have not been tested extensively on septic knee. This study tested the utility of the modified Kocher criteria in predicting septic knee while validating it for septic hip. Methods: A retrospective chart review was conducted of pediatric patients evaluated at a single institution for irritable hip or knee between 2009 and 2018. Patients who underwent arthrocentesis were included and the modified Kocher criteria were applied to all. Results: One hundred fifty-five patients (96 hips and 59 knees) were identified. One hundred four (67.1%) patients had septic arthritis with 44/59 (74.6%) of knees and 60/96 (62.5%) of hips. The strongest predictors for septic hip and knee were elevated C-reactive protein (odds ratio = 26.9, p < 0.0001) and refusal to bear weight (odds ratio = 14.5, p < 0.0001), respectively. For hips, 5/5 criteria produced a 100% positive predictive value for septic arthritis. For knees, the combination of inability to bear weight and elevated C-reactive protein had a positive predictive value of 89.7%. Conclusion: While all five of the modified Kocher criteria are not predictive of pediatric septic knee, the combination of two specific factors (inability to bear weight and elevated C-reactive protein) is strongly predictive. This study validates previous work that the modified Kocher criteria are predictive of septic hip. Level of evidence: level III

Comparison of Clinical Prediction Rules in Pre-school Aged Children With Septic Hip Arthritis Due to Different Pathogens

“…One study, for instance, reported that CRP and ESR were predictive for septic hip arthritis compared to transient synovitis but that they were not predictive for septic knee arthritis. 25 Limited performance of the KC in children with K. kingae septic hip arthritis was also reported by Yagupsky et al 22 Unexpectedly, the scores of both clinical prediction rules did not differ between K. kingae and S. aureus infections, or other microbiologically confirmed infections. However, we might be limited to detect small differences between pathogen groups, due to our sample size.…”

“…Furthermore, children with K. kingae hip arthritis could have more invasive disease leading to a more severe presentation compared to the presentation in K. kingae knee arthritis. One study, for instance, reported that CRP and ESR were predictive for septic hip arthritis compared to transient synovitis but that they were not predictive for septic knee arthritis 25 …”

Diagnostic Utility of Synovial Fluid Cell Counts and CRP in Pediatric Knee Arthritis: A 10-Year Monocentric, Retrospective Study

“…Despite its limitations, this retrospective study is one of the few studies concentrated on the knee joint effusion of pediatric patients and the potential distinguishing parameters between septic and non-septic arthritis [ 26 , 27 , 28 , 29 ]. Kocher predictive criteria for the hip joint are not applicable for the prediction of septic knee arthritis [ 26 ], and neither is the modified Kocher–Caird [ 2 , 30 ]. However, in recent studies, the combination of two specific factors (the inability to bear weight and an elevated C-reactive protein) was found to be strongly predictive [ 2 , 30 ].…”

“…Kocher predictive criteria for the hip joint are not applicable for the prediction of septic knee arthritis [ 26 ], and neither is the modified Kocher–Caird [ 2 , 30 ]. However, in recent studies, the combination of two specific factors (the inability to bear weight and an elevated C-reactive protein) was found to be strongly predictive [ 2 , 30 ]. As an alternative to the original Kocher criteria, Baldwin et al found that by increasing the number of criteria they achieved higher predictive values which included: pain with an arc of motion below 30 degrees, CRP level >4.0 mg/L, notion of episodes of fever, and an age below 2 years were all positive predictive values which were able to help distinguish septic arthritis of the knee from non-septic forms such as Lyme arthritis [ 27 ].…”

Sore knee – why and when to call a cardiologist

“…The inclusion of CRP of >20 mg/L (modified Kocher’s criteria), with the other four features, was independently found to have a 98% positive predictive value 5. It has also been shown that the presence of high CRP (>40) and inability to weight bear with a sore knee had an 89.7% positive predictive value for a septic knee over other diagnoses 6…”