Outcomes and prognostic factors in revision hip arthroplasty for severe intra-pelvic cup protrusion: 246 cases

Intrapelvic Cup Migration Following Revision Total Hip Arthroplasty: A Case Report and Review of the Literature

Intrapelvic acetabular cup migration is a rare but serious complication that can occur following either primary or revision total hip arthroplasty. Medial acetabular wall weakening is considered the main predisposing factor for acetabular protrusion. A thorough preoperative plan is essential to advocate proper pelvic anatomy reconstruction, including osteosynthesis of the pelvis, if necessary, preservation of muscle and bone stock, and selection of the right prosthetic components without damaging adjacent anatomical structures. We present a rare case of an 84-year-old woman with a hip dislocation and complete intrapelvic migration of the acetabular component, nine years after her second revision surgery of a hip prosthesis placed 60 years ago due to congenital hip dysplasia. The protruded acetabulum was not removed since preoperative CT and digital subtraction angiography (DSA) revealed no vascular compromise. A non-cemented, tantalum acetabular cup, reinforced by a short flange titanium acetabular cage, was placed with a cemented, polyethylene-bearing surface, which was revised to a cemented, constrained acetabular insert three months postoperatively due to dislocation after mobilization on the bed. We conducted a literature review to elucidate the causes, proper diagnostic tools, and preoperative planning of this rare occurrence while trying to evaluate a potential treatment protocol.

The Diagnosis and Treatment of Acetabular Bone Loss in Revision Hip Arthroplasty: An International Consensus Symposium

Despite growing evidence supporting the evaluation, classification, and treatment of acetabular bone loss in revision hip replacement, advancements have not been systematically incorporated into a single document, and therefore, a comprehensive review of the treatment of severe acetabular bone loss is needed. The Stavros Niarchos Foundation Complex Joint Reconstruction Center at Hospital for Special Surgery held an Acetabular Bone Loss Symposium on June 21, 2019, to answer the following questions: What are the trends, emerging technologies, and areas of future research related to the evaluation and management of acetabular bone loss in revision hip replacement? What constitutes the optimal workup and management strategies for acetabular bone loss? The 36 international experts convened were divided into groups, each assigned to discuss 1 of 4 topics: (1) preoperative planning and postoperative assessment; (2) implant selection, management of osteolysis, and management of massive bone loss; (3) the treatment challenges of pelvic discontinuity, periprosthetic joint infection, instability, and poor bone biology; and (4) the principles of reconstruction and classification of acetabular bone loss. Each group came to consensus, when possible, based on an extensive literature review. This document provides an overview of these 4 areas, the consensus each group arrived at, and directions for future research.

Preoperative optimization for vascular involvement complicating revision total hip arthroplasty

Vascular complications in revision total hip arthroplasty may occur in cases where the components of the hip implant migrate through the acetabular wall, through the iliopectineal line of the pelvis, and into the pelvic cavity. This migration may lead to substantial intrapelvic vascular compromise, drastically increasing the surgical complexity and potential risk for morbidity and mortality in these surgical cases. Here, we present a case of a 78-year-old woman with significant acetabular protrusio, which resulted in intraoperative compromise of the external iliac artery with rapid extravasation. As a result of prudent preoperative planning, interdisciplinary collaboration, and precautionary measures, significant patient morbidity and mortality was averted.

Level of Evidence

Level V, Case Report.

Hip malformation is a very common finding in young patients scheduled for total hip arthroplasty

INTRODUCTION

In Denmark, 20% of all registered total hip arthroplasties (THA) from 1995 to 2014 has been patients younger than 60 years with primary idiopathic osteoarthritis (OA). It is speculated that hip malformations may be a major contributor to early OA development. It has been shown that hip malformation may compromise implant position and, therefore, identifying and knowing the incidence of malformations is important. Our aim was to assess the prevalence and type of hip malformations in a cohort of younger patients undergoing THA.

MATERIALS AND METHODS

In this prospective two center cohort study, 95 consecutive patients (106 hips) met the inclusion criteria. One observer performed radiographic measurements for malformations and radiographic OA. Inter- and intraobserver variability was assessed.

RESULTS

From 95 patients (male n = 52 and female n = 43) age ranged from 35 to 59 years and prevalences of hip malformations were; CAM-deformity 50.9 and 25.5%, coxa profunda 33 and 27.4%, acetabular retroversion 33 and 29.2%, and acetabular dysplasia 10.4 and 3.8%. All patients showed minimum of one malformation. Prevalences of Tönnis grade 0-1 were 22.6% and 2-3 were 77.4%.

CONCLUSION

All patients showed malformations, especially high prevalences were found for CAM-deformity, coxa profunda and acetabular retroversion. Identifying these malformations is fairly simple and recognizing the high prevalence may help surgeons avoid pitfalls during implant positioning in THA surgery. Further, focus on hip malformations may facilitate correct referral to joint-preserving surgery before OA develops.

The impact of trabecular metal on hip centre of rotation in revision and complex primary hip arthroplasty, a radiological review

INTRODUCTION

Total hip arthroplasty (THA) is a very successful procedure. Revision THA is becoming increasingly common. Recent developments to improve outcomes include the development of large trabecular metal (TM) acetabular cups and augments. There is a paucity of data on the benefit of these new techniques.

METHODS

A single-centre retrospective review consisting of a radiological review of post-op revision THA anteroposterior pelvis. Data collection was performed using the Irish National Orthopaedic Register (INOR) and from a previous project. We used a technique developed by Fessy et al in 1999 to measure the centre of rotation (COR) of the hip. We then compared our study to that of a study measuring the COR of healthy native hips.

RESULTS

127 revision THA analysed. Native COR calculated by Fessy et al showed a mean horizontal (x) axis 33.6 mm (standard deviation [SD] 5.74) and a vertical (y) axis 16.4 mm (SD 4.67). Non-TM revisions showed a mean x axis of 29 mm (SD 3.9) and y axis 17.9 (SD 5.9). TM Augments had a mean x axis 29.2 mm (SD 7.9) and y axis of 21.5 (SD 8.4). TM Cups alone had a mean x axis 27 mm (SD 6.9) and y axis 22 mm (SD 10.18).

CONCLUSIONS

COR of TM implants showed considerable deviation from the norm. Non-TM implants showed a COR within acceptable physiological range. TM components consistently failed to restore a natural COR in our cohort. The implications of this remain uncertain but must be considered in any decision to use TM.

Subperitoneal approach in revision arthroplasty for acetabular component protrusion: Analysis of practices within the French Hip and Knee Society (SFHG)

INTRODUCTION

The complications related to revision for acetabular component protrusion with material migrating into the intrapelvic region remain rare but potentially serious. Today, the literature reports no epidemiological data on the subperitoneal approach (SPA) in revision total hip arthroplasty (RTHA) for protrusion. Therefore we conducted a retrospective study on a large revision arthroplasty database to answer the following questions: (1) What is the frequency of this approach in this population? (2) What are the factors related to this procedure? (3) Is morbidity and mortality of the SPA higher than for an isolated conventional approach?

HYPOTHESIS

Major protrusions with material in the superomedial quadrant (SMQ) have a higher probability of being operated using a SPA.

MATERIAL AND METHODS

This multicenter retrospective study included 260 cases of THA with endopelvic protrusion of material at least 15mm inside the Kohler line. The degree of protrusion was assessed on the AP pelvic X-ray with the construction of the SMQ. The reason for the subperitoneal approach, the duration of surgery, and the preoperative exams were also collected.

RESULTS

Nineteen procedures out of the 260 RTHAs included (7.8%) had a SPA in addition to the approach for the revision THA. The frequency of the SPA varied among centers (range: 1.7-50%). In four cases, the SPA was indicted to care for a vascular complication identified preoperatively. For one patient, the SPA was indicated intraoperatively. The other indications were either to extract the implant (n=7) or prevent a potential intraoperative assault of neurovascular structures (n=9). The cases presenting major protrusion on the AP X-ray with material in the SMQ were more often operated through the SPA (12/19; 63.2%) than cases with no SMQ involvement (4/241; 1.7%) (P<0.001). Vascular structures were explored with imaging in 15 out of 19 (88.9%) of the SPA cases versus 26 out of 177 (14.7%) of the revisions without the SPA (41 with no information in the non-SPA group) (P<0.001). Early mortality (before 45 days) of patients who had undergone the SPA (1/19; 5.3%) was not significantly different than for the patients who had not undergone the SPA (3/241; 1.2%) (P=0.26). Although the duration of surgery was longer in the SPA group (210±88 [range: 70-360] versus 169±52 [range: 60-300]; P=0.04), bleeding was not greater in the SPA group (1488±1770mL [range: 500-5000mL]) than in the non-SPA group (1343±987mL [range: 75-3500mL]; p>0.05).

DISCUSSION

Despite the limitations related to the retrospective and multicenter design of this study, to our knowledge it is the only one that examines SPA procedures within the context of severe material protrusion with THA. Based on these results, it seems preferable to plan for SPA every time there is an acetabular protrusion in the SMQ, after exploration with CT angiography. The SPA does not result in greater mortality or morbidity.

LEVEL OF EVIDENCE

IV, retrospective study.

Safe zone for transacetabular screw fixation using a Kerboull cross-plate: A CT-scan templating prospective study

BACKGROUND

Implantation of Kerboull acetabular reinforcement cross-plates (Kerboull plate) carries a risk for injury to vascular structures and pelvic organs. To our knowledge, there is no study assessing anatomical assessment related to this risk with this specific design. Therefore, we performed a prospective study to answer the following four questions: 1) What is the minimum distance and angle between the plate and iliac vessels? 2) What is the distance between the plate and the inner cortex of the ilium? 3) What is the ratio of views with muscle tissue present on the inner surface of the ilium? 4) What are the boundaries of the safe zone for transacetabular screw fixation for a Kerboull plate?

HYPOTHESIS

A safe zone for fixation screws would be defined by a narrow range of insertion angles.

MATERIALS AND METHODS

This is a CT-based 3D templating prospective study. Simulations were performed for 18 patients fitted with a Kerboull plate. An original Kerboull plate (Stryker, Mahwah, NJ, USA) was placed at a 45° abduction angle relative to the X-axis (alignment A) and the palette was placed vertically to the X-axis (alignment B). We measured the distance from the centre of the plate to the inner surface of the cortex of the ilium, the shortest distance to vessels and the angle of existing vessels, and the ratio of muscles on the inner surface of the ilium.

RESULTS

The shortest distance to the vascular structures increased with increasing angle of insertion of the fixation screws, 85.8±12.1mm for A and 111.4±12.0mm for B at 45°. The distance to the inner cortex was further increased for screws inserted in posterior direction. At insertion angles ≥40°, the screws passed through muscle before invading the pelvis in most cases. However, at anterior-posterior angle (AP angles) ≤-10°, the risk of direct insertion of screws into the sacroiliac joint increased.

DISCUSSION

The safe zone for transacetabular screws would be insertion at an angle≥40°, with an AP angle between 0° and -10° (slight posterior direction).

LEVEL OF EVIDENCE

Level IV prospective diagnostic study.