Inverted
posture
‘A Rearfoot
good fit?’
Table 3: Results of binary logistic regression analysis of the association between calcaneus inverted angle and the
presence of PFOA (n = 68)
Odds ratio (95% CI)*
Independent variable
Calcaneus inverted
angle, per degrees
Inverted calcaneus
Dependent variable
Crude model Propensity adjusted model
No PFOA (n = 30) vs. ANY
PFOA (n = 38) 1.118 (1.018–1.245) † 1.134 (1.013–1.291) †
No PFOA (n = 30) vs.
MIXED PFOA (n = 19) 1.166 (1.031–1.356) † 1.135 (0.958–1.406)
No PFOA (n = 30) vs.
MEDIAL PFOA (n = 22) 1.180 (1.044–1.368) †† 1.118 (1.018–1.245) †
No PFOA (n = 30) vs.
LATERAL PFOA (n = 26) 1.109 (1.010–1.235) †† 1.078 (0.965–1.213)
6 (15.8) 2 (6.7)
PFOA: patellofemoral osteoarthritis; 95% CI: 95% confidence interval
*Adjusted for propensity to prescribe as a function of age, (continuous), sex (0: male, 1: female), body mass index (continuous), tibiofemoral
joint Kellgren/
Logistic regression analyses (Table 3) revealed
that rearfoot posture was associated with
PFOA in a non-compartment specific manner.
Calcaneus inverted angle was significantly
associated with higher odds of the presence of
any (OR=1.134, 95% CI [1.013, 1.291], p=0. 028)
and medial PFOA (OR=1.180, 95% CI [1.005, 1.
439], p=0.043); however, significant relationships
were not confirmed mixed (OR=1.135, 95%
CI [0.958, 1.406]; p=0.147) and lateral PFOA
(OR=1.078, 95% CI [0.965, 1.213], p=0.183).
Discussion
This exploratory study showed that patients
with coexisting PFOA and medial TFOA on
average had an inverted calcaneus 3.1° greater
than those with isolated medial TFOA after
32
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adjusting for covariates, although approximately
70% of patients in both groups had a normal
range of calcaneus angle. Increased calcaneus
inverted angle was significantly associated
with higher odds of any and medial PFOA and
likely to be associated with higher odds of
the presence of mixed and lateral PFOA. The
association between rearfoot alignment was in
the same direction for medial or lateral PFOA,
thereby rearfoot alignment appears not to be
associated with compartmental distribution
of PFOA. Potential risk factors associated
with PFOA involve patellar alignment relative
to trochlea; muscle weakness, such as in the
quadriceps; and abnormal biomechanics [38].
While an extensive literature review found
similarities in clinical symptoms, structure,
Lawrence grade (continuous), corrected anatomical axis angle (continuous), presence of varus thrust (0: absence, 1: presence), and knee
flexion range of motion (continuous)
† p <0.05; †† p <0.01