Iliopsoas tendon impingement associated with total hip arthroplasty was first reported, to the best of our knowledge, in the English-language literature in 1995 by Trousdale et al.1. They described two cases in which the iliopsoas tendon impinged on a prominent, retroverted acetabular cup. Since that report, other etiologies of iliopsoas tendon impingement have been described2-7.
Iliopsoas tendinitis can occur in patients with no malalignment or anterior prominence of the acetabular component2,8,9. After total hip arthroplasty, it is often difficult to diagnose and treat patients with persistent groin pain when the components appear to be well fixed on the radiograph and when there is no clear cause of the pain10.
It is well known that iliopsoas impingement can occur with tendon abutment on a prominent acetabular component1,2,5,11. However, iliopsoas tendon impingement on the femoral head component is rarely discussed. Intuitively, the increased diameter of the femoral head may cause attritional wear of the iliopsoas tendon, resulting in persistent groin pain after total hip arthroplasty or hip resurfacing. To the best of our knowledge, a correlation between increased femoral head size with metal-on-polyethylene bearings in hip arthroplasties and iliopsoas tendon impingement has not been previously described.
This case report illustrates that iliopsoas tendon impingement can occur after total hip arthroplasty with use of large-diameter femoral heads (>28 mm) in conjunction with highly crosslinked polyethylene liners. The patient was informed that data concerning her case would be submitted for publication, and she provided consent.
A forty-year-old woman presented with groin pain on the right side, exacerbated by long periods of sitting, that developed six months after a right total hip arthroplasty for osteoarthritis, which had been performed sixteen months prior to presentation. The patient also had previously had a left total hip arthroplasty, which was asymptomatic.
The symptomatic right hip arthroplasty had been performed via an anterolateral approach. A 52-mm Trilogy acetabular shell (Zimmer, Warsaw, Indiana) fixated with two screws had been placed in 40° abduction and 25° anteversion with a highly crosslinked polyethylene liner. A press-fit 11-mm Trabecular Metal femoral stem (Zimmer) with a neutral neck length and a 36-mm femoral head had been inserted into the femur (Figs. 1-A and 1-B).
On clinical examination of the right hip, the patient demonstrated a Trendelenburg gait. There was no clinical evidence of infection or abductor insufficiency, determined by abductor strength testing. Hip flexion was 90°. Active straight leg raise was painful and reproduced the groin pain. With external rotation of the hip and simultaneous hip extension, the patient had reproducible pain but no audible or palpable snapping. Leg lengths were symmetric both clinically and radiographically. There was no evidence that the joint center was too distal, which could cause a lengthening of the iliopsoas tendon. In addition, the prosthetic femoral head was smaller than the patient’s native femoral head. Radiographs and computed tomography revealed no evidence of component loosening or of a prominent acetabular component that could contribute to iliopsoas tendon impingement. An arthrocentesis did not reveal any evidence of infection. Transiently, the patient had dramatic relief of the pain for three days after a fluoroscopic-guided iliopsoas bursal injection of bupivacaine and methylprednisolone acetate. A trial of physical therapy did not provide relief of the groin pain.
Because of the patient’s recalcitrant groin pain and the transient relief provided by the iliopsoas bursal injection of bupivacaine and methylprednisolone acetate, the patient agreed to an arthroscopic iliopsoas tenotomy. The procedure, adapted from the method of Ilizaliturri et al.12, was performed with the patient in the supine position. An anterolateral inferior portal was created 2 to 3 cm below and 1 to 2 cm anterior to the anterosuperior corner of the greater trochanter. Under arthroscopic guidance, a guidewire was passed over a spinal needle placed into the iliopsoas bursa next to the lesser trochanter. A cannulated system was passed over the guidewire to insert the 30-degree arthroscope into the iliopsoas bursa adjacent to the lesser trochanter. The bursa was insufflated at a pressure of 40 mm Hg. An accessory portal was established by making a second incision 3 to 4 cm distal to the arthroscopic portal, and fluoroscopic triangulation was used to place a radiofrequency device at the iliopsoas insertion (Fig. 2). Under both arthroscopic and fluoroscopic guidance, the iliopsoas tendon was completely released from its insertion on the lesser trochanter (Figs. 3-A, 3-B, and 3-C).
Postoperatively, the patient was allowed to walk as tolerated. At the six-week follow-up, the patient was able to perform an independent, active straight leg raise, but hip flexor strength was substantially less than the contralateral side. The Trendelenburg gait had resolved by three months, and she had a strong active straight leg raise test without pain. At the three-month follow-up, hip flexor strength was symmetric with the contralateral side. At the thirteen-month follow-up, the patient’s Single Assessment Numeric Evaluation (SANE) rating was 90%. The activities of daily living subscale of the Hip Outcome Score was 80%, and the patient rated the current level of function during activities of daily living at 90%13. The modified Harris hip score was 86%. Subjectively, the patient reported that she was satisfied with the symptomatic improvement after the arthroscopic iliopsoas tenotomy.
To the best of our knowledge, this is the first report of a postoperative iliopsoas impingement caused by a large-diameter metal femoral head after total hip arthroplasty with use of a highly crosslinked polyethylene acetabular bearing. We have treated one other patient with a similar presentation and outcome. A previous case report discussed the treatment of iliopsoas tendon impingement with botulinum toxin type A after implantation of a large-diameter femoral head on a polyethylene bearing surface, but the authors did not attribute the iliopsoas tendon impingement to the larger size of the femoral head14.
Browne et al. described three cases of iliopsoas tendon impingement caused by larger diameter femoral heads with a metal-on-metal articulation15. In all three cases, the diameter of the femoral ball appeared larger than the native head. All patients had revision arthroplasty through a posterior approach with downsizing of the femoral head and revision of the acetabular component to allow for a polyethylene insert. Partial or complete release of the iliopsoas was performed at the lesser trochanter.
In our case, arthroscopic release via a bursal approach was successfully performed. This minimally invasive approach is advantageous for several reasons. Intuitively, arthroscopic surgery has better cosmetic results, is less painful, and may have a reduced risk of infection compared with open incisional approaches. In addition, the benefits of a large-diameter femoral head with respect to hip motion and stability are maintained by not having to downsize the femoral head. The arthroscopic approach is safe and effective for treating iliopsoas pathology in native hips12,16-21 as well as after total hip arthroplasty9.
Diagnosis of postoperative iliopsoas tendinitis and bursitis is often difficult. These entities can often be confused with aseptic loosening of the acetabular component. Although we were not able to definitively prove that the iliopsoas tendon was impinging on the femoral head since our patient was treated arthroscopically, the fact that the patient had transient relief of symptoms after the iliopsoas bursal injection of bupivacaine and methylprednisolone acetate and had dramatic pain relief lasting at least one year post-tenotomy is highly suggestive of this diagnosis.
Previous studies have suggested that the prevalence of iliopsoas bursitis in patients after traditional total hip arthroplasty is 4.3%3,22, with the prevalence of surgery required to treat postoperative iliopsoas tendinitis reported to be 0.37%2. The prevalence of iliopsoas tendon impingement after large-diameter metal-on-metal hip replacement was reported to be 8% in a recent study23. The increase in the prevalence of the use of large-diameter femoral heads seen in these studies suggests that increased femoral head size may be a risk factor for iliopsoas tendon impingement after total hip arthroplasty.
In addition, a patient’s sex may play a role in the incidence of iliopsoas tendon impingement after hip arthroplasty. When reviewing the literature (as well as our case), we found that the majority of patients with this problem are women (forty-five men and eighty-three women)1-4,6-8,11,14,15,24-31. Women had a greater incidence of groin pain after metal-on-metal hip resurfacing32, which may be caused by impingement of the psoas tendon across the larger femoral head used for resurfacing33. Anatomical variation in women is a possible mechanism for iliopsoas tendinitis. Noble et al. have shown that the femora differ in size and shape in men and women34. The height of the femoral head above the lesser trochanter was 14% greater in men than in women34. Consequently, the course of the iliopsoas tendon may exhibit a sex variation as it traverses the postarthroplasty femoral head-neck junction, thereby increasing the risk of iliopsoas tendon impingement in women after total hip arthroplasty.
Iliopsoas impingement after total hip arthroplasty may be preventable. In addition to ensuring that the acetabular component is not prominent, we recommend intraoperative manual testing of the tension of the iliopsoas as it traverses the femoral head-neck junction to assess for patients at risk for postoperative iliopsoas tendon impingement. In patients determined to be at risk, one can consider a prophylactic iliopsoas tenotomy, particularly in women and in patients with large-diameter femoral heads used in hip arthroplasty procedures, regardless of the bearing surfaces.