Suspected Iliopsoas Tendinopathy
A 7yo FS mixed breed was referred to us for imaging due to suspected iliopsoas tendinopathy. Historically, she has demonstrated an intermittent LHL lameness, reluctance to fully use the hind end, and consistent pain on palpation of the iliopsoas tendons bilaterally. Appropriate treatment was initiated by the referring veterinarian, but the patient took a sudden turn for the worse after being startled by another dog, and is now lame on both hind limbs.
On presentation for the day of imaging, the iliopsoas tendons were painful bilaterally, enough that I was unable to do more than light palpation without eliciting substantial discomfort. During this appointment, the owner emphasized that often, the patient is reluctant to move at all. We proceeded to imaging, taking orthogonal radiographs of the stifles and lumbopelvic region, as well as ultrasound images of the iliopsoas tendons. A clear core lesion was found in the left iliopsoas tendon (Figure 1).
Figure 1: Longitudinal ultrasound view of the iliopsoas tendon. The tendon itself runs horizontally (blue arrows), attaching to the lessor trochanter on the right (orange arrow). The core lesion appears as a hypoechoic (dark) region indicated by the green arrow.
Iliopsoas or psoas major pain is a common physical examination finding, one that is almost always coupled with other symptoms of non-specific back pain. It appears that back pain can lead to iliopsoas (or psoas major) pain, and that iliopsoas pain will give rise to back pain. By the time the patient presents, we are left wondering who is the chicken, and who is the egg.
Subjectively, I’ve found that when the iliopsoas pain is mild, bilateral, and particularly when it is within the belly of the psoas major muscle itself, it is secondary to primary back pain. It also frequently appears secondary to appendicular disease such as hip OA or cruciate insufficiency. Unilateral cases, particularly those with consistent severe pain affecting the tendonous region with no underlying appendicular disease, are more likely to be primary iliopsoas tendinopathy.
Because secondary psoas muscular pain is more common than primary tendinopathy, my first line treatment approach is address the back and psoas pain, and monitor the response. In my hands, I’ve had the best luck by combining acupuncture (both TCM and dry needling/IMS techniques) with manual therapy, and photobiomodulation. Typically, I expect to see measurable clinical improvement within days of a second treatment; if the patient returns for a third treatment and there is still no observable improvement, I recommend imaging.
Typically, we recommend combining radiographs of the lumbopelvic and stifle regions with ultrasound of the iliopsoas tendon itself. Although we sometimes see radiographic changes on the lessor trochanter, the insertion point of the iliopsoas tendon (Figure 2), I am mostly using the radiographs to rule out co-morbidities such as hip dysplasia, intervertetral disc disease (IVDD), degenerative lumbosacral stenosis (DLSS), or cruciate disease. If I have a high suspicion of IVDD or DLSS, I will proceed to CT imaging instead of radiographs. If a co-morbidity exists, then it may need to be resolved before we can expect the iliopsoas to demonstrate long-term improvement (eg: TPLO repair the ruptured cruciate, then address the iliopsoas pain as part of the post-surgical rehabilitation program).
Figure 2: VD hip extended view radiograph showing soft tissue mineralizion of the iliopsoas tendon on the right (orange arrow). The opposite lessor trochanter is showing mild enthesophytic change (lipping) as well. There is mild subluxation of the femoral head on the right suggestive of soft tissue laxity.
When ultrasounding the iliopsoas, I will concurrently image the hip joint to look for inflammation not detected on the radiographs. In this particular case, that led to an important finding (to be discussed in part 2 of this blog).
If the ultrasound findings are normal, or if they show non-specific changes such as thickening with no fiber disruption, extracorporeal shockwave (ESWT) becomes my first line therapy. If there are visible macroscopic changes, such as in this case, then my first choice treatment is regenerative medicine – combining some sort of stem cell product with platelet rich plasma and injecting it directly into the lesion under ultrasound guidance. Some clients elect to start with ESWT, and if they aren’t happy with the response, proceeding to stem cells as the next step. Similarly, we prefer to augment our stem cell cases with ESWT during the recovery phase.
ESWT or stem cells are always combined with an appropriate therapeutic exercise program, a structured return to exercise, and ongoing photobiomodulation. With the above program we have found there is an excellent prognosis for returning to full activity (unless otherwise restricted by an underlying co-morbidity).
In the end though, despite the persistent iliopsoas tendon pain, and the obvious core lesion evident on ultrasound, iliopsoas tendinopathy ended up not being the primary cause of this patient’s lameness. Hold on to your seats as we learn about the real diagnosis in part 2 of this blog.
(Stay tuned for next week!)