Measurements of in vivo intra-articular gentamicin levels from antibiotic loaded articulating spacers in revision total knee replacement

moverNov 18, 2024

	Authors Mutimer J, Gillespie G, Lovering AM, Porteous AJ
	Institute Trauma and Orthopaedics, Southmead Hospital, Bristol, United Kingdom.
	Journal Knee. 2009 Jan;16(1):39-41.

Take Home message:

Preformed spacers guarantee therapeutic concentrations of antibiotic in synovial fluid surrounding the joint throughout the period of implantation
The key is the antibiotic release performance, not the antibiotic dose

Study details		Score	Range
Subject	Clinical	–	–
Type	Retrospective study	1	1-3
Journal	The Knee	2	1-3

Summary

A high concentration of gentamicin was found in synovial liquid of 12 patients which received Spacer-K on the day of spacer removal.

Patients characteristics
12 patients (6 M, 6 F) with a mean age of 71 years
Pathogens: Coagulase-negative Staphyococcus (10), Stapylococcus aureus (2)

Treatment
Spacer-K was fixed with gentamicin-loaded cement. Drains removed after 24h. A 14-day regime of parenteral ABX followed by a further 4 weeks of oral ABX.
No patients received further administration of gentamicin.

Median spacer implantation (range)
99 days (63 – 274)
Two implants were left in situ more due to patients comorbidities

Mean FU
10 months

Results

Infection eradication
100% (12/12 patients)

Gentamicin concentration in synovial fluid
From 0,24 to 2,36 mg/L (0,46 mg/L)

Gentamicin concentration in blood samples
Very low or below the limit of detection

Key points:

Therapeutic concentration (0,46 mg/L) of Gentamicin in synovial fluid around the joint after 99 days of spacer implantation
Low concentration of Gentamicin (0,06 mg/L) in blood: no toxicity (recommended max daily dose limit 5 mg/Kg/day)
Antibiotic release from preformed spacers depends on polymer matrix, and not on the antibiotic dose

Score

Study value	Description
*	Retrospective study
* *	Retrospective comparative Retrospective Register study
* * *	Prospective study Systematic review Meta-analysis