The accuracy of needle placement may
have efficacy and safety implications
By KEITH M. SMART, PhD | 30 April
2012
Dr Smart is a clinical specialist
physiotherapist at St Vincent’s University Hospital in Dublin.
ABSTRACT: Intra-articular injections
have been recommended as adjunctive treatment for patients with knee
osteoarthritis (OA). The many anatomical-based approaches through which to
administer therapeutic injections into the knee include the extended leg
lateral and medial midpatellar portals and the bent leg anteromedial and
anterolateral portals. Agreement about the most accurate approach is lacking.
In “dry” knee OA—in which the knee does not have a clinically detectable
effusion—the accuracy of intra-articular needle placement is less certain
because confirmation of placement by aspiration is not possible. The accuracy
of needle placement may have implications for the efficacy and safety of
intra-articular injections of the knee. Several studies that used various
subjects and methodologies have evaluated the accuracy of intra-articular knee
injections. (J Musculoskel Med. 2012;29:114-117)
Intra-articular injections of
corticosteroids or hyaluronate have been recommended for use in patients with
moderate to severe osteoarthritis (OA) of the knee.1,2 Systematic reviews and
meta-analyses suggest that intra-articular injections of corticosteroids
provide short-term (about 1 to 4 weeks), clinically significant improvements in
pain in patients with knee OA.3-6 Intra-articular injections of hyaluronate may
provide longer-term (conservatively estimated as up to about 3 months)
improvements in pain and function.7,8
FIGURE
(MORE: Self-Reported Knee Pain in
Women With Osteoarthritis Fluctuates Over Time)
Several palpation-based, anatomical
landmark–guided approaches for the administration of therapeutic injections
into the knee have been described, including the extended leg lateral
midpatellar (LMP) and medial midpatellar (MMP) portals and the bent leg
(flexed to 90°) anteromedial (AM) and anterolateral (AL) portals (Figure).9,10
Agreement about the most accurate approach through which to administer
therapeutic intra-articular injections into the knee is lacking—practices
appear to vary widely and choices ultimately depend on the preference of the clinician
who is administering the injection.11
When an intra-articular effusion is
present in patients with knee OA, the accuracy of needle placement has been
suggested to be confirmed by the return of synovial fluid during joint
aspiration.10 In the absence of an effusion (“dry” knee OA), however, the
accuracy of intra-articular needle placement is less certain because
confirmation of placement by aspiration is not possible.12
The accuracy of needle placement may
have implications for the efficacy and safety of intra-articular injections of
the knee, particularly of hyaluronate. It also may affect the diagnosis of
joint-related pathologies, such as infective arthritis and crystal
diseases.13,14
In this article, I review the
evidence evaluating the accuracy of needle placement during intra-articular
injections for dry OA of the knee using various anatomical portals. I establish
whether the evidence supports the use of one particular approach from those
available such that recommendations for the administration of intra-articular
knee injections in clinical practice may be made.
STUDIES
A few studies that used various
methodologies evaluated the accuracy of needle placement during intra-articular
injections of the dry OA knee joint performed with anatomical landmark–guided
approaches. Jackson and associates15 compared the accuracy of needle placement
of 3 landmark-guided intra-articular injection approaches in a prospective
series of 240 hyaluronate injections in 80 patients with symptomatic dry knee
OA. Injections were administered by 1 orthopedic surgeon through 1 of 3
portals—AM, AL, or LMP—using a 21-gauge, 5.1-cm needle.
Each patient received 1 injection
through each portal; thus, the potential for sampling bias was eliminated.
Accuracy was determined by an acceptable gold standard of real-time
fluoroscopic imaging with dispersion of contrast material within the joint
space together with “coating” of the articular surfaces indicative of accurate
needle placement.
LMP Approach Recommended
The LMP approach was significantly
more accurate than the other approaches studied (intra-articular placement
achieved on the first attempt 93% of the time, compared with 75% and 71% for
the AM and AL approaches, respectively). The authors recommended the use of the
LMP approach for intra-articular joint injections in patients with dry OA knee
disease.
However, the order in which the
injections were administered was not randomized. Therefore, an order effect
could have confounded the results. Because injections were administered by a
single clinician, the accuracy of the LMP approach should be evaluated in
defined cohorts of clinicians to test the generalizability of this approach in
clinical practice.
Accuracy and Severity Comparisons
In another study, Toda and
Tsukimura10 compared the accuracy of intra-articular hyaluronate knee
injections performed with the modified Waddell (an AM approach with
manipulative ankle traction at 30° of knee flexion), seated AM (knee flexion to
90°), and extended leg superolateral patellar (SLP) approaches in 50 patients
with dry OA of the knee of grade II, III, or IV severity on the
Kellgren-Lawrence radiographic scale (equivalent to minimal, moderate, or
severe joint changes, respectively16). Injections were performed by 1
orthopedic surgeon using a 23-gauge, 3.2-cm needle. Each patient received 1
injection (combined with contrast material) through each portal in a random
order over a 3-week period. Accuracy was determined by postinjection
radiographs; it was confirmed when contrast material was deemed to shape the
outline of the suprapatellar pouch and meniscus.
Modified Waddell Approach Advocated
The overall accuracy rates for the
modified Waddell, seated AM, and extended leg SLP approaches were 86%, 62%, and
70%, respectively. There were no significant differences in accuracy rates
between approaches for patients classified with Kellgren-Lawrence scale grades
II and III. The accuracy rate for the modified Waddell approach was
significantly higher (100%) than those for the seated AM and extended leg SLP
approaches (55% each) in patients with Kellgren-Lawrence scale grade IV
changes. On the basis of these results, the authors advocated that clinicians
change the approach used for hyaluronate injections according to the severity
of knee OA and recommended the use of the modified Waddell approach in patients
who have more severe OA changes of the knee.
In the Toda and Tsukimura study,10
all patients received an injection through each portal in a randomized fashion,
which eliminated the potentially confounding influences of sampling bias and
order effects. However, when the robustness of the findings and the validity of
the conclusion are being considered, the following methodological flaws invite
caution:
• The needle length (3.2 cm) may have
been insufficient to allow for accurate intra-articular needle placement.
Jackson and colleagues15 recommended a needle length of about 5 cm to clear
periarticular structures and reach the intra-articular space.
• With small patient numbers in each
Kellgren-Lawrence scale grade, the study probably was insufficiently powered to
allow for valid subgroup analyses.
• Definitions of Kellgren-Lawrence
scale grades are not specified; consequently, the external validity and
generalizability of the results are limited. In addition, the Kellgren-Lawrence
grading system may lack validity as a method of subgrouping the severity of
knee OA because operational definitions and interpretations of its grades
vary.17
Modified Bent Knee Approach Evaluated
In a recent study, Chavez-Chiang and
associates9 evaluated the accuracy of a modified bent knee (knee flexion to
90°) AL approach (Mod-AL). They targeted the synovial membrane of the medial
femoral condyle in 76 consecutive injections of corticosteroid with local
anesthetic in patients with dry knee OA via a 21-gauge, 5.1-cm needle. Accuracy
was determined using real-time ultrasonography (US) and defined as
visualization of (1) the needle tip at the interface of the synovial membrane
and cartilage, (2) the free flow of fluid into the intra-articular space, and
(3) dilation of the intra-articular space with injected fluid. Injection via the
Mod-AL approach had an accuracy rate of 97%.
Chavez-Chiang and associates9
suggested that the Mod-AL approach provides accuracy similar to that achieved
with the LMP approach. They noted that the approach might be useful for
patients who cannot lie down or transfer to an examination couch or extend
their knee, such as some older, obese, or wheelchair-bound persons and those
who have flexion contractures. Although the authors assumed parity between the
Mod-AL and LMP approaches, the lack of a direct comparison limited the study’s
usefulness.
Also, whether the injection and US
were performed by the same or different physicians is not clear. If the
accuracy was determined by same physician who administered the injection, the
results could be subject to a degree of operator bias that could have inflated
the accuracy rate. In addition, the characteristics of the clinicians who
administered the injections are not described and their professional background
and competence cannot be ascertained. These factors limit the generalizability
of the study’s findings as well as its replicability.
Cadaver Study
Several other studies that used
various subjects and methodologies have evaluated the accuracy of
intra-articular knee injections. In a cadaver study, Esenyel and colleagues18
compared the accuracy of the bent knee AL and AM (5.1-cm needle) and extended
leg LMP and MMP approaches. Cadaveric knees were injected with methylene blue,
and accuracy was determined by surgical dissection and inspection of the needle
tip and diffusion of the methylene blue.
Accuracy rates for the AL, AM, LMP,
and MMP approaches were 85%, 73%, 76%, and 56%, respectively. There were no
statistically significant differences among the AL, AM, and LMP approaches, but
the MMP approach was significantly less accurate than the others. Esenyel and
colleagues18 suggested that any of the AL, AM, and LMP portals could be used
clinically.
Extended Leg Comparisons
Another study compared the accuracy
of extended leg medial, midlateral, and superolateral approaches during
US-guided intra-articular injections of corticosteroid, local anesthetic, and
contrast agent via a 25-gauge, 3.8-cm needle into 126 dry OA knees.19 The
accuracy rates were 95% and 100% for the midlateral and superolateral portals,
respectively, compared with 75% for the medial portal.
A recent systematic review of
accuracy rates of various intra-articular injection approaches for the knee
joint found the extended leg SLP approach to be the most accurate (pooled
accuracy, 91%), followed by the LMP (85%), AM (72%), and AL (67%) approaches.13
However, the review included studies that involved patient populations that had
knee disorders with various causes, such as rheumatoid arthritis; patients
admitted for arthroscopy; patients with effusions; and one cadaveric study.
Therefore, that evidence supporting the SLP approach as the most accurate may
not generalize specifically enough to patients who have dry knee OA.
CONCLUSIONS
The studies’ heterogeneity limits
direct comparisons. Overall, however, the data that specifically evaluated the
accuracy of various landmark-guided approaches for intra-articular injections
of dry knee OA suggest that the LMP approach probably offers the most accurate
route for the administration of injectable therapeutic agents into the
intra-articular space of the knee. Data to support this assertion are limited,
and further studies using multiple clinicians and validly defined subgroups of
patients are required before any clear clinical recommendation can be made.
Other studies and reviews provide
mixed results about the accuracy of knee joint injections through various
anatomical portals such that clear evidence of the accuracy of one approach
over any other remains equivocal. Therefore, the anatomical portals through
which intra-articular injections of the knee are currently administered are
likely to remain dependent on clinician preference unless clarification comes
from future research.
Take Home Points
• Limited evidence suggests the
lateral midpatellar portal to be the most accurate approach through which to
administer intra-articular injections for “dry” knee osteoarthritis (OA).
• Additional limited evidence
suggests that clinicians might alter their injection approach according to the
severity of knee OA.
• Further studies to evaluate the
accuracy of various injection approaches are required before any clinical
recommendations can be made.
