Iliopsoas impingement after total hip replacement

While iliopsoas impingement after total hip arthroplasty is most commonly associated with acetabular cup size and placement, other causes that have been cited include excessive osteophytosis, retained cement, excessively long screws penetrating through the ilium, and a prominent femoral collar⁹.

Treatment of Iliopsoas Impingement following Total Hip Replacement

Options for treatment of persistent iliopsoas related groin pain following total hip replacement are either non-surgical or surgical, with various methods reported for surgical intervention^4,9.

1. Non-operative treatment

Non-operative treatment options described in the scientific literature are primarily pharmacological interventions, either peritendinous injection of glucocorticoids +/- local anaesthetic or non-steroidal anti-inflammatory medication^4,9. Non-surgical interventions usually also include physical therapy, with hip flexor stretching the only modality mentioned.

No further detail is available regarding physical therapy intervention, but it would appear that there has been no testing of a standardised protocol. While one study reported a complete lack of benefit from non-surgical treatment¹⁰, Chalmers et al⁹ reported a 50% success rate. In the recent systematic review by Shapira and colleagues⁴, the authors reported that although non-surgical interventions demonstrated improvement, surgical treatment groups showed greater overall improvement.

It is important to note that non-surgical treatment options have been poorly investigated and applied. Hip flexor stretching makes little sense as a treatment strategy for iliopsoas impingement. Stretching will only more firmly impinge the iliopsoas against the uncovered acetabular cup, provoking pain.

The limited success achieved is likely only due to injections or medications that may ameliorate the provocation of stretching. However, longer term oral medications are not an ideal option and injection carries the risks of infection and possible damage to the local soft tissues, particularly with repeated corticosteroid injection.

Optimising non-operative treatment approaches with a more clinically reasoned load management and exercise therapy protocol aiming to reduce exposure to provocative loads and improve health of the iliopsoas, may return more positive results.

2. Surgical treatment

Surgical iliopsoas release (tenotomy) and acetabular component revision are the two general surgical approaches for managing persistent iliopsoas related groin pain following total hip replacement. Various procedures have been described for surgical release or lengthening of the iliopsoas tendon.

Surgery may be performed either arthroscopically or open and at the level of the femoral head or at the distal insertion at the lesser trochanter. The level of evidence for intervention studies is currently poor (predominantly Level IV small case studies), with no randomised clinical trials⁴.

A recent systematic review and meta-analysis assessed outcomes from studies that had included Patient Reported Outcome Measures for intervention for Iliopsoas impingement following total hip arthroplasty⁴. The only Level III study compared acetabular revision to iliopsoas tenotomy, reporting that patients with <8 mm of component prominence experienced mostly good outcomes and resolution of pain with iliopsoas tenotomy, while those with ≥ 8mm of acetabular cup prominence had a high success rate and excellent clinical outcomes with acetabular revision⁹.

However, Shapira et al’s review and meta-analysis of the available literature found that complications of acetabular component revision were more severe and more common - 19.4% vs 3.76% for tenotomy⁴. These authors then concluded that ‘conservative measures’ should be first line treatment for iliopsoas impingement and tenotomy second line treatment, with revision arthroplasty reserved for recalcitrant cases. In another broader systematic review of iliopsoas release for all indications, not just following total hip arthroplasty, arthroscopic tenotomy was shown reported to have lower complications that open surgery.

Release of the iliopsoas tendon may understandably impact adversely on hip flexor strength and function. No studies have assessed change in strength or physical function following tenotomy for iliopsoas impingement after total hip replacement. Longstaff’s review reported that only one study has used dynamometry to assess hip flexor strength following iliopsoas tenotomy (non-THR population). Brandenburg and colleagues reported a 25% loss of iliopsoas muscle volume measured on MRI and a 19% reduction in seated hip flexion strength, measured with hand-held dynamometry, in patients who had arthroscopic iliopsoas release performed in the context of FAI and/or chondrolabral pathology.¹¹

With the growing numbers of younger patients undergoing total hip replacement, these outcomes need to be considered and measured. Many of these patients are having their surgery earlier with the intent of returning to running or other sports, where the iliopsoas plays an important role.

So, there is a challenge here for health professionals in both prevention and management of iliopsoas impingement after total hip replacement. Surgeons need to be very mindful of their cup selection and placement in the first instance. Physiotherapists and other rehabilitative professionals need to carefully consider the application of their treatment protocol and consider whether a stretching protocol is more likely to help or hinder the process of recovery. A load management and exercise program (avoiding stretching) may have a greater chance of success. Is surgery a good universal options? There are a number of arguments against iliopsoas release.  Until we have evidence available, we must rely on the science available in similar conditions and apply evidence-informed clinical reasoning to optimise our outcomes.