Page 117 - Canine Lameness

6.6 Clinical Significance 89

MPS has been categorized as primary (unrelated to other medical conditions) or secondary
(associated with a comorbid medical condition; Weller et al. 2018). An acute muscle strain injury
that results in the formation of MTPs is an example of the former, whereas an example of the latter
includes the formation of MTPs in the functional unit muscles secondary to any articular dysfunc-
tion (Table 6.1).
Chronic cranial cruciate ligament disease (CCLD) is a good example of secondary MPS in the
functional muscle units. In this scenario, the functional muscle units are those that flex and extend
the stifle joint. Pelvic limb muscles that assist in stifle extension include the cranial head of the
sartorius, tensor fasciae latae, rectus femoris, and the vastus group. Predominant stifle flexors
include the semitendinosus, semimembranosus, biceps femoris, and gastrocnemius. Additionally,
these muscles provide dynamic stabilization and the demand placed upon them may be increased
due to the deficiency in static joint stabilization. Careful evaluation of these muscles for evidence
of taut bands and MTPs should be performed in dogs with CCLD. MTPs can also be found in the
gracilis and adductor due to their attempts to counter the slight pelvic limb abduction seen with
CCLD as described by Tashman et al. (2004). Severity of MPS is directly related to the chronicity
and severity of the CCLD.
Articular dysfunction of the coxofemoral joint related to hip dysplasia can also lead to MTP for-
mation in its functional muscle units. The pectineus muscle in particular can become exquisitely
painful and taut. Myalgia in this small muscle is almost always the result of articular disturbance
and mechanical overload of the muscle due to its attempt to counter the subluxation of the femoral
head. Other muscles that may show MTPs include the gluteal muscles and hip flexors including
the iliopsoas, and iliocostalis lumborum near its origination.
Pelvic limb disorders, both orthopedic and neurologic, can result in increased distribution of
body weight to the thoracic limbs. The formation of MTPs in the triceps, infraspinatus, supraspi-
natus, deltoids, latissimus dorsi, in the region of its fusion with the teres major, and/or serratus
ventralis can be observed. The more chronic and severe the pelvic limb problem(s) are the more
profound the MPS in the muscles described above.
MTPs can also be related to radiculopathy, such as thoracic limb lameness related to structural,
compressive lesions of the C6–T2 region. Clinically MTPs can be observed in any of the muscles
receiving innervation from an irritated spinal nerve(s). A pattern of increased development of
MTPs in the triceps on the affected side in a C6–T2 radiculopathy is often observed.

6.6 Clinical Significance

MPS and MTPs in human healthcare are not without their skeptics and critics: A critical literature
review published in 2014 dismissed MPS and MTP concepts and hypotheses (Quintner et al. 2015).
However, in this author’s opinion, Quintner et al. (2015) provided a biased review and failed to
review current literature. In contrast, the rather lengthy published response of Dommerholt and
Gerwin (2015) based on more current scientific advances supported the concepts of MPS and MTP.
This controversy is in part due to the reliance upon palpation and pain responses when diagnos-
ing MPS. Further research is needed to clearly answer the clinical implications of MPS and MTP
in people and dogs. However, the use of ultrasound and magnetic resonance elastography offers a
method for more objective identification of MTPs (Gerwin 2016). For example, recent research
utilizing MRI has confirmed the presence of taut bands in people but also showed that they are
overestimated by clinicians (Chen et al. 2016).
Muscle pain and dysfunction resulting from the presence of MTPs should be considered in
canine lameness as a potential cause (primary MPS) and/or a finding (secondary MPS) associated