Blackburn, J.T.

Frank, B.S.

Harkey, M.S.

Jordan, J.M.

Luc, B.A.

Mauntel, T.C.

Padua, D.A.

Pamukoff, D.N.

Pietrosimone, B.

Spang, J.T.

Stanley, L.E.

Elsevier - Publisher Connector 

Abstracts / Osteoarthritis and Cartilage 23 (2015) A82eA416 A109associations of peak vGRF and vGRF rate of loading with biomarker
concentrations of both serum C2C and CPII. Next, we determined
associations for peak vGRF and vGRF rate of loading with a breakdown
to synthesis turnover ratio (C2C:CPII), where a higher ratio indicates
more collagen break down compared to synthesis. Pearson Product (r)
Moment and Spearman (r) rank order correlations were used to asso-
ciate normal and non-normally distributed data, respectively. An alpha
level of 0.05 was used for all analyses.
Results: Peak vGRF (1.13 ± 0.07 %BW; r¼ - 0.53, P¼0.02) and vGRF
loading rate (7.52 ± 2.29 BW/s; r¼ - 0.47, P¼0.04) were negatively
associated with the serum C2C:CPII concentration ratio (0.33 ± 0.13).
Peak vGRF was not signiﬁcantly associated with C2C (145.22±19.29 ng/
ml; r¼ - 0.25, P¼0.33) or CPII (510.53 ± 207.1 ng/ml; r¼ 0.32, P¼0.18)
individually. Similarly, vGRF loading rate was not signiﬁcantly asso-
ciated with C2C (r¼ - 0.18, P¼0.45) or CPII (r¼ 0.27, P¼0.27) individu-
ally. Post hoc analyses, found no associations between time since ACLr
or contralateral vGRF and serum biomarkers.
Conclusions: There were signiﬁcant moderate associations linking
higher peak vGRFs and vGRF loading rates with lower collagen type II
breakdown to synthesis ratios, an average of 3.5-4 years following ACLr.
These ﬁndings are contrary to our a priori hypotheses that higher peak
and rate of loading would associate with more collagen breakdown
relative to synthesis. Individually C2C and CPII concentrations did not
signiﬁcantly associate with peak vGRF or vGRF loading rate, yet more
loading (peak and higher rate) weakly associated with less breakdown
and more synthesis. The associations between greater loading and
lower serum C2C:CPII concentration ratios may be driven by higher
overall concentrations of collagen synthesis, in the involved limb of
ACLr individuals with more joint loading. An increase in collagen syn-
thesis may be a response to higher loads exerted in the ACLr limb. More
collagen synthesis may be necessary to continue to tolerate higher loads
at an injured joint. Future research should examine if patients that
develop PTOA synthesize collagen differently in response to higher
loading during gait.
148
KINETIC GAIT ADAPTATIONS FOLLOWING ANTERIOR CRUCIATE
LIGAMENT RECONSTRUCTION: IMPLICATIONS FOR POST-
TRAUMATIC KNEE OSTEOARTHRITIS
J.T. Blackburn, B. Pietrosimone, D.A. Padua, B.S. Frank, M.S. Harkey,
B.A. Luc, T.C. Mauntel, D.N. Pamukoff, L.E. Stanley, J.T. Spang,
J.M. Jordan. Univ. of North Carolina at Chapel Hill, Chapel Hill, NC, USA
Purpose: Anterior cruciate ligament injury and reconstruction surgery
(ACLR) incur a 3-5x increase in the risk of developing post-traumatic
knee osteoarthritis (PTOA). This OA phenotype progresses rapidly, with
as many as 25% of patients developing radiographic joint changes
within 5 years. Furthermore, these injuries typically occur in individuals
15-25 years of age, thus PTOA resulting from ACLR represents a long-
term health concern. While development of PTOA is multifactorial,
loading characteristics of the articular cartilage have received sub-
stantial attention in the literature, with greater loading hypothesized to
result in greater cartilage degradation. Given the repetitive nature of
walking and its integral role in human locomotion, gait biomechanics
are commonly evaluated in efforts to identify loading characteristics
that inﬂuence cartilage degradation. While cartilage loading cannot be
directly quantiﬁed in vivo, peak impact forces and joint moments are
commonly evaluated as biomechanical surrogates. Additionally, animal
models suggest that the rate of loading may play a more important role
in cartilage degradation than the magnitude of loading. While loading
rates during gait have been evaluated in individuals diagnosed with
knee OA, we are unaware of any literature evaluating the potential role
of loading rates in the development of PTOA following ACLR. Therefore,
the purpose of this investigation was to compare gait kinetics between
the healthy and surgically reconstructed limbs following ACLR. We
hypothesized that greater loading and loading rates would be observed
in the ACLR limb compared to the healthy limb.
Methods: Three-dimensional gait biomechanics were obtained from
twenty-three individuals with a history of unilateral ACLR (15 females, 8
males; age ¼ 22±4 years, mass ¼ 74±20 kg, height ¼ 1.70±0.12 m, time
since ACLR¼ 39±29 months) via an optoelectric motion capture system
integrated with force plates. Subjects walked along a 6m walkway at a
self-selected speed. The force plates were staggered such that data for
both limbs could be obtained in a single trial. Peak vertical ground
reaction force (vGRF; N) and instantaneous loading rate (vGRF-LR; N/s),internal knee extension moment (KEM; Nm), and sagittal plane knee
stiffness (KS; Nm/) were identiﬁed during the ﬁrst 50% of the stance
phase. vGRF-LR was calculated as the 1st time-derivative of the vGRF;
KEM was calculated via standard inverse dynamics; and KS was cal-
culated as the ratio of the change in KEM to the change in knee ﬂexion
angle. Forces were normalized to body weight (xBW) and moments
were normalized to the product of body weight and height (%BW*Ht).
All dependent variables were compared between healthy and ACLR
limbs via paired-samples t-tests (p0.05).
Results: No differences were observed between limbs for peak vGRF
(1.13±0.07 xBW vs. 1.14±0.09 xBW, p¼0.318) or peak vGRF-LR
(59.97±17.51 BW/s vs. 55.44±17.59 BW/s, p¼0.216). However, peak KEM
(4.4±1.2 %BW*Ht vs. 5.0±1.5 %BW*Ht, p¼0.003) and KS (0.35±0.11 %
BW*Ht/ vs. 0.40±0.12 %BW*Ht/, p¼0.003) were signiﬁcantly greater in
the healthy limb compared to the ACLR limb.
Conclusions: While ground reaction force characteristics did not differ
between the ACLR and healthy limbs, knee extension moment and
stiffness were greater in the healthy limb than in the ACLR limb. The
vGRF reﬂects the summative loading of all lower extremity joints. In
contrast, KEM and KS are joint-speciﬁc. Reduced knee joint-speciﬁc
loading in the ACLR limb in the presence of similar vGRF characteristics
between-limbs suggests that contributions from the ankle and hip
extensors to the vGRF are increased in the ACLR limb to compensate for
reduced contributions from the knee extensors. These data may also
suggest that insufﬁcient, rather than excessive, loading may contribute
to PTOA following ACLR. Insufﬁcient loading may alter nutrient and
waste exchange characteristics, thus resulting in a cellular energy
imbalance due to the avascular nature of articular cartilage. Fur-
thermore, altered joint-speciﬁc loading may disrupt the normal
catabolic and anabolic processes that are necessary to regulate articular
cartilage remodeling. Quadriceps dysfunction is a common, lingering
complication following ACLR. As the quadriceps is the primary con-
tributor KEM and KS, future research is necessary to determine if
interventions targeting quadriceps dysfunction improve gait bio-
mechanics in manners that would reduce the risk of PTOA following
ACLR.
149
GAIT ADAPTATIONS TO EXERCISE-INDUCED FLARES OF
OSTEOARTHRITIS RELATED KNEE PAIN
K.A. Boyer, C. Jewell, J. Hafer. Univ. of Massachusetts-Amherst, Amherst,
MA, USA
Purpose: To evaluate the effect of a 20 minute walking stimulus
(20MWS) that is intended to simulate participation in daily activity on
self-reported pain, ambulatory function (walking speed, vertical ground
reaction force (GRF), and stance time) and knee joint kinetics in older
adults with chronic knee pain. Acute exercise is known to exacerbate
pain in osteoarthritis (OA) on a short term basis, however very little is
known about patient compensations to acute ﬂares of OA pain.
Understanding the motor system adaptations to pain may provide
insight into short and long term efﬁcacy of pain therapies and their
impact on joint health. We hypothesized that therewould be signiﬁcant
increases in pain and concomitant decreases in ambulatory function
and joint kinetics in response to the 20MWS in adults with OA related
knee pain.
Methods: Seven older adults (62.3 þ/- 6.2 years; 24.8 þ/-2.8 kg/m2)
were enrolled in the study after completing the informed consent
process and a Physical Activity Readiness Questionnaire (PAR-Qþ).
Inclusion criteria were ages 50-75 years, BMI <35 kg/m2, good general
health, met the American College of Rheumatology clinical classiﬁcation
criteria for OA in at least 1 knee, ability to walk unaided, no history of
cardiovascular or neurological disorders. Knee symptoms were eval-
uated using the Knee Osteoarthritis Outcome Score (Table 1). For the
20MWS, subjects walked on a treadmill at a pace similar to their pre-
ferred overground speed. Pain was evaluated on an 11 point verbal
numeric pain rating scale in the ﬁrst and ﬁnal 2 minutes.
Gait analysis was performed pre and post 20MWs while subjects
walked overground on an 11m walkway at preferred and faster than
preferred speeds. 3 trials per speed were collected at each timepoint.
External inter-segmental moments were calculated for the lower limb
using an inverse dynamics procedure. The primary gait outcomes were:
walking speed, maximum vertical GRF, time in stance on more affected
leg, peak external knee ﬂexion, adduction, and internal and external
rotation moments on the more affected leg. A 2 x 2 factor Analysis of


Kinetic gait adaptations following anterior cruciate ligament reconstruction: Implications for post-traumatic knee osteoarthritis 

file:///data/remote/core/dit/data/elsevier/pdf/7b5/aHR0cDovL2FwaS5lbHNldmllci5jb20vY29udGVudC9hcnRpY2xlL3BpaS9zMTA2MzQ1ODQxNTAwOTQ3NA==.pdf

Kinetic gait adaptations following anterior cruciate ligament reconstruction: Implications for post-traumatic knee osteoarthritis

Abstract

Similar works

Full text

Available Versions

Elsevier - Publisher Connector

Elsevier - Publisher Connector