Posterior Soft Tissue Repair After Primary THA is Durable at Mid-term Followup: A Prospective MRI Study

Abstract

Background The enhanced posterior soft tissue repair has reduced the frequency of dislocation after primary THA performed through the posterolateral approach. However, the long-term integrity of the repair is unknown and could influence surgeon choice regarding surgical technique and THA approach. Questions/Purposes We asked: (1) What is the durability of the enhanced posterior soft tissue repair at a minimum of 49 months using MRI to evaluate soft tissue to bone integrity? (2) How does the appearance of the posterior soft tissues change during this time? (3) Are there patient characteristics associated with the long-term imaging appearance of the posterior repair? Methods All patients without a contraindication for MRI who were undergoing unilateral primary uncemented THA through a posterior approach between February and May 2005 were eligible for inclusion. Ninety percent consented to participate (36 of 40 patients), and 30 patients were followed prospectively with MRI postoperatively and again at 3 months; of those, 22 (73%; 12 men, 10 women) completed the study by having another MRI study at a minimum of 49 months (mean, 51 months; range, 49-59 months). Each patient underwent metal-artifact-reduction sequence MRI to evaluate the integrity of the posterior soft tissues, which had been repaired anatomically during primary THA at a minimum of 4 years earlier. The results were compared with those of prior MR images obtained immediately after surgery and at 3 months postoperatively. All patients were given a self-reported modified Harris hip score at the time of the most recent MRI study (maximum score = 81). Results At latest followup, 21 of 22 (96%) patients had a posterior capsule in contact with bone, and 21 of 22 (96%) had an intact quadratus femoris. Twenty-one patients (96%) had soft tissue or a scar from the piriformis and

Imaging near orthopedic hardware

“…Longitudinal analysis of this repair technique using MRI has shown that the piriformis and conjoined tendons form hypointense scar that aligns along the long axis of the original tendon, preventing clinical instability despite early failure of the repair. 83,84 Recurrent hemarthrosis may occur in patients following arthroplasty due to hyperemic, friable synovium and/or areas of synovial impingement. On MRI, hemarthrosis appears as a complex synovitis with bulky intermediate signal intensity deposits.…”

“…In a classic posterior surgical approach, the short external rotators tendons are released and subsequently repaired. Longitudinal analysis of this repair technique using MRI has shown that the piriformis and conjoined tendons form hypointense scar that aligns along the long axis of the original tendon, preventing clinical instability despite early failure of the repair (83,84)…”

Advanced MRI Techniques for the Hip Joint: Focus on the Postoperative Hip

“…To mitigate this risk, posterior soft-tissue reconstruction is often performed at the time of surgery to enhance hip joint stability [23]. As such, it is imperative to assess the integrity of the posterior joint capsule and short external rotator muscles.…”

“…Posterior capsular dehiscence can be appreciated at MRI by a lack of continuity of the posterior pseudocapsule and short external rotators with the greater trochanter, often showing a fluid-filled gap interposed between the two, with or without associated anterior pseudocapsular thickening and hyperintensity. Longitudinal MRI studies indicate that the repairs fail early but that the retracted tendons form scar-in-continuity that aligns with the tendon long axis and prevents instability in most cases [23]. …”

Direct Repair of the Superior Band of Bigelow's Ligament after Hip Arthroplasty: A Surgical Technique

“…tendons are in continuity directly, or through scar, with the greater trochanter in 96% of patients [12]. The soft tissue restraint conferred by this technique is effective at reducing dislocation incidence but does not eliminate it [5,10].…”