The Use of Augment Devices in Revision Acetabular Surgery

Long-term results of combined porous tantalum augments and titanium-coated cups for Paprosky type III bone defects in acetabular revision

PURPOSE

The use of porous tantalum augments and titanium-coated cups in primary total hip arthroplasty (THA) with acetabular defects has shown satisfactory outcomes in our centre. The aim of this study was to report the long-term radiological and clinical outcomes of using this combination for Paprosky type III acetabular bone defects in acetabular revision.

PATIENTS AND METHODS

Between January 2007 and January 2015, 45 patients with Paprosky type III acetabular defects underwent acetabular revision using a combination of porous tantalum augments and titanium-coated cups. Among these, 41 patients (41 hips) had complete follow-up. Thirty-one patients had a Paprosky type IIIA defect, and ten patients had a Paprosky type IIIB defect. No patients had pelvic discontinuity. There were 20 males and 21 females with an average age of 63.2 years (range 35-80) at the time of revision surgery.

RESULTS

The mean follow-up was 122.8 months (range 69-165). The Harris Hip Score (HHS) improved significantly from 32.1 points (range 17-58) pre-operatively to 85.3 points (63-98) at the last follow-up. The Short Form-12 (SF-12) and Hip Dysfunction and Osteoarthritis Outcome Score (HOOS) improved significantly for each item at the last follow-up. Two patients had a high hip centre post-operatively. One patient had recurrent dislocation but did not require re-revision. No further revision of the acetabular components was required, and all hips remained stable at the last follow-up with bony ingrowth of the acetabular components according to the criteria of Moore et al. CONCLUSION: The combination of tantalum augments and conventional titanium-coated cups achieved satisfactory long-term radiographic and clinical outcomes for Paprosky type III acetabular bone defects without pelvic discontinuity.

The Utilization of Metal Augments Allows Better Biomechanical Reconstruction of the Hip in Revision Total Hip Arthroplasty With Severe Acetabular Defects: A Comparative Study

BACKGROUND

Reconstructing the normal hip biomechanics is important for a successful revision total hip arthroplasty (THA). Little is known about whether using metal augments in revision THA is biomechanically superior to traditional techniques.

METHODS

A retrospective review was conducted on 74 consecutive THAs revised using metal augments with a cementless hemispherical cup and 77 consecutive THAs revised using the jumbo cup, all with a minimum 2-year follow-up. Biomechanical parameters were measured before and immediately after the revision. Radiological and clinical outcomes at follow-ups were also evaluated.

RESULTS

The metal augment group had a reconstructed center of rotation (COR) that was 6.5 mm closer to the anatomic COR in height (P < .001), had 3.6 m smaller cup size (P < .001), and had 5.7 mm less head-cup difference (P < .001). Moreover, there was a reconstructed COR that was much closer to the anatomic COR (vertical distance: 1.8 vs 14.1 mm, P < .001; horizontal distance: -2.1 vs 7.9 mm, P = .013), had 4.1 mm greater femoral offset (P = .006), and had 8 mm less leg length discrepancy (P = .035) in the subgroup of Paprosky type III bone defects when compared to the jumbo cup group. All cup-augment constructs were radiologically stable with a higher mean postoperative Harris Hip Score (P = .012). One jumbo cup was radiologically unstable.

CONCLUSION

In revision THA, utilizing metal augments helps to restore the COR position more precisely, avoid using a larger cup, reduce head-cup difference, rebuild femoral offset, and decrease leg length discrepancy, particularly with Paprosky type III bone defects. Moreover, it provides satisfactory radiological and clinical outcomes in the short term.

Clinical and radiological outcomes of trabecular metal systems and antiprotrusion cages in acetabular revision surgery with severe defects: a comparative study

INTRODUCTION

Acetabular revision surgery poses a challenge due to the increased frequency of severe defects and poor quality of the remaining bone. We compare the clinical and radiological outcomes, complications, and survival of two systems commonly used in complex acetabular revisions (AAOS types II, III, and IV): trabecular metal system (TM) and Burch-Schneider antiprotrusion cages (BS).

METHODS

Eighty-four patients underwent acetabular revision surgery with TM or BS in our centre between 2008 and 2014. Comparison was made of demographic and clinical characteristics, satisfaction, radiographic parameters, complications, and survival of the implants. A BS was implanted in 30.9% of the patients, while 69.1% received a TM implant. The mean follow-up was 4.77 years.

RESULTS

The BS group required a significantly greater number of constrained implants (p = 0.001) and more walking aids (p = 0.04). The mean satisfaction (p = 0.02) and HHS scores at the end of the follow-up were higher in the TM group (p = 0.003). No differences were observed in the incidence of complications, though the only two cases of implant rupture corresponded to the BS group. The overall survival rate was 88.1% after 7.5 years.

CONCLUSION

TM implants afforded better clinical outcomes and greater patient satisfaction than antiprotrusion cages in the treatment of severe acetabular defects.