Foot & Ankle International - July 2018 - 868

868
In 2004, both Egol et al13 and McConnell et al36 published results of patient cohorts with apparent isolated fibula fractures that underwent manual stress radiography.
McConnell et al36 reported on 138 patients of which 97
patients presented with an isolated fibular fracture and an
intact mortise. Using manual external rotational stress testing, 36 patients (37%) demonstrated instability relative to
the manual stress applied. Egol et al13 examined 101 patients
with similar pathology and noted that 66 (65%) who presented with an anatomic mortise had a positive stress radiograph. Force of stress application was not quantified in
either study, and despite using the same manual external
rotation test, it is notable that instability was reported as
near double the rate in Egol's cohort as compared with the
work of McConnell. This discrepancy may lend support to
the concept that stability of the mortise is a relative concept
and depends on the amount of stress applied.
While these and other earlier studies reported on the use
of manual stress views, providers found that patient discomfort, operator dependence, and time investment was not
insignificant. Accordingly, the use of gravity stress views,
as suggested in Michelson's original work, was further
investigated. In 2007, Gill et al16 examined a cohort of 25
patients with SER injuries and assessed ankle stability
based on talar shift and MCS change. A manual external
rotation stress radiograph, along with a gravity stress radiograph, was performed for each patient, and radiographic
results were compared. In the SER II group, the average
MCS was 4.15 and 4.26 mm on the manual and gravity
stress radiographs, respectively (P = .50). In the SER IV
group, the average MCS was 5.21 and 5.00 mm on the manual and gravity stress radiographs, respectively (P = .69).17
Their findings suggested that gravity stress radiography
was similar to manual testing and likely better tolerated by
patients. Gill's findings were duplicated by Schock et al56 in
a cohort of 29 patients. A subsequent study by LeBa et al32
echoed Gill and Schock's findings, making the argument
for gravity stress views relatively convincing.
What is the effect of gravity stress on the normal, uninjured ankle? Recently, Jastifer et al25 examined gravity
stress radiographic examination in a cohort of 50 asymptomatic patients. Mean MCS was 3.6 mm as compared with
3.3 mm and 3.1 mm on AP and mortise views, respectively.
No patients displayed MCS widening more than 0.2 mm as
compared with unstressed radiographs.

Physiologic Loading and Instability
Can physiologic loading (ie, weight bearing) elucidate
instability? Increasingly, some have argued that the use of
gravity or manual stress views may overestimate the need
for surgery by eliciting subtle instability treatable by conservative means and that (1) either weight-bearing radiographs at time of injury and/or (2) a trial of protected weight

Foot & Ankle International 39(7)
bearing with repeat x-rays may be a better predictor of mortise stability.7,10,22,47,55,64,65
A cadaveric study by Stewart and colleagues in 201259
sought to elucidate the effect deltoid incompetence has on
the integrity of the ankle mortise with an applied axial load.
Twelve cadavers were divided into 3 groups: intact ankles,
isolated oblique fibular osteotomies, and osteotomized
ankles with complete deltoid ligament transection. Each
group was then loaded sequentially with 0, 25, 36, and 50
kg to simulate weight bearing with radiographs taken at
each successive load. Instability and therefore deltoid
incompetence was defined as a greater than 2-mm change in
the MCS from the intact ankle. With this criterion, the
authors found no statistical MCS widening with simulated
axial weight bearing with an isolated osteotomy or osteotomy in conjunction with a sectioned deltoid ligament. These
findings imply that weight-bearing radiographs cannot elucidate instability or at least not instability relative to those
forces applied with manual or gravity stress views. Clinical
investigations have borne this out.
Hoshino et al23 prospectively examined 36 patients with
initial, non-weight-bearing radiographs demonstrating normal alignment but with MCS widening on manual stress
testing. Patients were placed in a short-leg walking cast
with repeat examination 7 days later, at which time weightbearing radiographs were obtained. Nonoperative management was continued if the MCS remained less than 4 mm,
while operative treatment was recommended for those demonstrating increased diastasis. At final follow-up, anatomic
mortise alignment was demonstrated, and the authors advocated for the use of weight-bearing radiographs instead of
manual stress views to aid in clinical decision making and
prevent unnecessary surgeries. In 2010, Weber et al64 demonstrated similar findings. His group defined instability as
an MCS greater than 4 mm, MCS greater than 1 mm wider
than the SCS, or lateral talar subluxation relative to the tibial plafond and concluded that weight-bearing radiographs
were an "easy, pain-free, safe and reliable" method for
determining ankle stability.
While these and other authors have demonstrated the
utility of weight-bearing radiographs to predict eventual
mortise alignment, a careful distinction should be made
once again between stability and the anatomic relationship
of the talus with the tibial plafond. These studies did not
demonstrate the utility of weight-bearing radiographs to
predict a stable mortise but instead to identify patients who
may do equally well with nonoperative treatment if anatomic alignment was seen. Hoshino, Weber, Stewart, and
others' works appear to demonstrate the ability of weightbearing (axial load) to "normalize" mortise alignment in
proven unstable ankles. By definition, a shift in talar alignment with gravity/manual stress as demonstrated in their
patient cohorts indicates instability. Specifically, these studies identified patients who may do well with nonoperative

Table of Contents for the Digital Edition of Foot & Ankle International - July 2018