Mechanical Stability of Novel Highly Porous Metal Acetabular Components in Revision Total Hip Arthroplasty

Highly porous metal acetabular components have emerged for revision hip arthroplasty. However, superior mechanical stability over traditional cementless components has not been demonstrated. Three different cementless acetabular components, including 2 highly porous tantalum designs, were inserted into hemipelvis specimens with a superolateral defect. Mechanical testing was performed to failure using a servohydraulic testing machine. The porous tantalum designs exhibited superior stability over the traditional cementless implant (P < .05). There was no difference in mechanical stability between the rigid modular tantalum shell and the more flexible revision tantalum shell (P > .46). In acetabular revision, highly porous tantalum acetabular components provide superior mechanical stability. However, these results suggest that improved frictional resistance is a more important design feature over implant flexibility with this particular implant.     

Constrained Acetabular Liners Cemented Into Cages During Total Hip Revision Arthroplasty

The combination of acetabular bone loss and hip instability is challenging. Sixteen patients underwent revision total hip arthroplasty using constrained acetabular liners cemented into cages. The average follow-up was 28 months (range, 24-60 months). Clinical evaluation was obtained using the Harris hip score along with radiographic data. At latest follow-up, 13 patients were available for evaluation. Although the average postoperative Harris hip score was 62 points, which was better than the preoperative score of 27 points, the overall radiographic failure rate was 23%. The combination of poor acetabular bone stock and altered stresses from the increased constraint likely led to the poor outcome. We would only recommend use of a cemented, constrained acetabular liner in combination with a protrusio cage as a bail out or salvage procedure.     

A 2- to 16-Year Clinical Follow-Up of Revision Total Hip Arthroplasty Using a New Acetabular Implant Combined With Impacted Bone Allografts and a Cemented Cup

Background

Treatment of acetabular bone loss with impaction bone grafting (IBG) at revision total hip arthroplasty is highly dependent on mechanical stability and graft compression for clinical success. Here, we describe a new technique to further compress and stabilize the acetabular graft bed with a thin, perforated titanium shell.

Distal Interlocking Screws With a Modular Revision Stem for Revision Total Hip Arthroplasty in Severe Bone Defects

A prospective study of 15 patients was designed to examine whether the modular cementless revision stem (Revitan curved; Zimmer GmbH, Winterthur, Switzerland) is suitable for stem revisions with a defective isthmus when distal interlocking screws are also used for fixation. During a follow-up period of 35.4 ± 11.4 months (24-70 months), there was one stem loosening with screw breakage in a case of a stem that was too thin. According to Engh et al, bony ingrowth fixation of the stem occurred in 12 cases and stable fibrous fixation in 2 cases. The Harris Hip Score rose continuously from 44.7 ± 12.9 points preoperatively to 75 ± 10 points at 24 months. This concept of additional stem fixation with distal interlocking screws represents a useful treatment option for revision arthroplasty in rare cases of a defective isthmus.     

Acetabular Reconstruction With the Medial Protrusio Technique for Complex Primary and Revision Total Hip Arthroplasties

Background

In the setting of acetabular deficiency during total hip arthroplasty (THA), the medial protrusio technique (MPT) allows for increased component coverage while avoiding excessive component abduction or elevation of the hip center. The technique involves controlled reaming through the medial acetabular wall while maintaining the continuity of the anterior and posterior columns. The purpose of this study is to analyze the results of the largest reported series to date of primary and revision THAs using the MPT.

Isolated Acetabular Revision Hip Arthroplasty with the Use of Uncemented Cup

We evaluated the clinical and radiological results of isolated acetabular revision hip arthroplasty. Forty-three hips underwent isolated acetabular revision with uncemented cup and were followed up for an average of 76 months. The monoblock femoral stems were used in 20 hips and modular femoral stems in 23 hips. The average Harris Hip Score improved to 87 at last follow-up from 57 preoperatively. All femoral stems maintained stable fixation with bone ingrowth and no subsidence at last follow-up. Five hips with the monoblock stem underwent rerevision due to loosening of cup with osteolysis. The isolated acetabular revision is encouraging, but in reflection of the results of the monoblock head, the visual inspection of the femoral head is not enough for evaluation of its surface status.     

Isolated Acetabular Revision With Ceramic-on-Ceramic Bearings Using a Ceramic Head With a Metal Sleeve

The purpose of this study is to evaluate results of isolated acetabular revision with ceramic-on-ceramic bearings using a ceramic head with a metal sleeve. A retrospective review of fifty-three hips was performed. The mean patient age was 49.9 years and the mean follow-up period was 5.7 years. The mean modified Harris hip score improved from 47.5, pre-operatively, to 84.7 at the time of last follow-up (P < 0.001). Two patients reported squeaking of the hip. Three patients experienced loosening cup, necessitating re-revision surgery. There was a significant difference of acetabular bone defect between loose cup group and stable cup group (P = 0.018). There were no ceramic fractures and no osteolysis. The survival rate of the acetabular cup at the mid-term follow-up was 94.3%. In conclusion, ceramic head with a metal sleeve can be a reliable option for isolated acetabular revision.     

Porous-Coated Cementless Acetabular Components Without Bulk Bone Graft in Revision Surgery

We previously reported the average 9.3-year (range, 5-13 years) results of 74 patients (83 hips) with porous-coated acetabular components that were placed without bulk bone graft at revision surgery. Since the previous report, 7 patients (7 hips) died before the minimum follow-up of 10 years, and 1 patient (1 hip) was lost to follow-up. We now report the average 15.6-year (range, 10-20 years) results for 66 patients (75 hips). Three additional acetabular components were removed or revised again: 2 for infection and 1 for dislodgement of the polyethylene liner from the metal shell. Overall, 7 (7%) components required removal or repeat revision. No shell was revised for aseptic loosening, and none was categorized as loose during the entire follow-up period.     

Early Results of 827 Trabecular Metal Revision Shells in Acetabular Revision

We evaluated the survival of 827 acetabular revisions with Trabecular Metal Revision Shell using data from a nationwide arthroplasty register. The mean age of the patients was 69.1 years. The 3-year overall survivorship was 92% (95% confidence interval, 88-95), which coincides with earlier reports. Revision rate for aseptic loosening was only 2%. The most common reason for revision was dislocation of the prosthesis with or without malposition of the socket (60%). Age was found to have significant effect on cup survivorship: each additional year in age decreased the risk of revision by 2.4% (95 % confidence interval, 0.1-4.7; P = .044). We found no differences in survival rates between aseptic and septic revisions. Furthermore, sex, diagnosis, and hospital volume did not affect the survival.     

Acetabular Revision Using Trabecular Metal Augments for Paprosky Type 3 Defects

Background

Trabecular Metal (TM) augments are one option when reconstructing bone loss during acetabular side revision surgery.

Initial Implant Stability Predicts Migration But Not Failure in Cementless Acetabular Revision with Bone Grafting

Host bone contact of less than 50% is perceived but not proven to cause migration and loosening after actetabular revision. A prospective analysis of cementless acetabular revision cases with impaction grafting was performed to determine if this was an independent risk factor for these events. Sixty-two hips in 54 patients were assessed at a mean follow-up of 84.5 months (range 61–112) yielding a probability of 94.6% of retaining the acetabular component using revision for aseptic loosening as the end point. No single factor was independently causative for loosening, although Type III fixation was associated with migration (p = 0.0159); subanalysis suggested that achieving host–bone contact in at least part of the dome and posterior column is important.     

Massive Bone Defect Compromises Postoperative Cup Survivorship of Acetabular Revision Hip Arthroplasty with Impaction Bone Grafting

We evaluated 66 acetabular revision arthroplasties using cemented cup with impaction bone grafting (IBG) to detect the extent that bone defect affects the outcome. We defined the maximum acetabular defect distance (MADD), which indicates the greatest depth of the grafted layer. Cup survival analysis with aseptic loosening as the endpoint revealed that the “MADD ≤ 20 mm” group showed higher survivorship than the “MADD > 20 mm” group (95% vs. 74%, P = 0.034), and that the simple-wall-defect group (none or one mesh used) showed higher survivorship than the complex-wall-defect group (two meshes used) (96% vs. 73%, P = 0.044). A favorable indication for acetabular IBG reconstruction is cases in which those cups can be placed at ≤ 20 mm MADD with a simple wall defect.     

Long-Term Results of Acetabular Reconstruction Using Ganz Acetabular Rings

Background

Our study examines the long-term results of acetabular reconstruction using the Ganz acetabular reinforcement ring (GRR) in total hip arthroplasty.

Midterm Outcomes After Reconstruction of Superolateral Acetabular Defects Using Flying Buttress Porous Tantalum Augments During Revision Total Hip Arthroplasty

BackgroundPorous tantalum augments are versatile tools in reconstructing complex acetabular defects during revision total hip arthroplasty (THA). This study examines the clinical and radiographic outcomes of porous tantalum augments placed in the type I (flying buttress) configuration at two to 17-year follow-up in the largest cohort to-date in the literature.MethodsWe retrospectively analyzed 59 consecutive revision THAs involving the use of flying buttress augments between 2003 and 2018. The mean patient age and follow-up duration were 63.9 ± 11.6 years (range, 35-87) and 8 years (range, 2-17), respectively. The Oxford hip score was used to assess clinical outcome. The modified Moore classification was used to assess acetabular augment and shell osseointegration. Kaplan-Meier survival analysis with 95% confidence interval (CI) was used to assess implant survivorship.ResultsThe mean Oxford hip score improved from 15.9 ± 6.2 preoperatively to 35.0 ± 6.5 at a mean follow-up of eight years (P < .0001). Radiographic assessment using the modified Moore classification demonstrated five signs of osseointegration in 49 hips (83.1%), four signs in six hips (10.2%), three signs in one hip (1.7%), and one sign in one hip (1.7%). Kaplan-Meier analysis demonstrated ten-year survivorship of 88.9% (95% CI 74.4-95.4) with all-cause revision as end point and 94.3% (95% CI 83.1-98.2) with revision for acetabular aseptic loosening as end point.ConclusionTreatment of superolateral acetabular defects during revision THA using porous tantalum augments placed in the type I (flying buttress) configuration provides excellent implant survivorship and favorable clinical outcomes at mid-term follow-up.Level of EvidenceTherapeutic Level IV.     

Results of Isolated Femoral Component Revision With Well-Fixed Acetabular Implant Retention

The present study was undertaken to evaluate the clinical and radiological results of isolated femoral revisions conducted while retaining well-fixed cementless acetabular sockets. Thirty-nine patients that underwent isolated femoral stem revisions were reviewed. Mean age at time of surgery was 60.5 years, and mean follow-up duration was 4.2 years. Decisions to retain acetabular sockets were based on clinical and radiographic findings and intraoperative stabilities. During revisions, polyethylene liners were exchanged for metal-inlay polyethylene liners to have a metal-on-metal bearing surface in 23 cases. Mean Harris hip score improved from 58 points preoperatively to 85 points at final follow-up (P < .001). With the exception of one patient, no increases in acetabular radiolucent line numbers or thicknesses were observed during follow-up visits. Isolated femoral stem revisions with acetabular socket retention were found to provide excellent clinical and radiographic results.     

Cementless Acetabular Socket Revisions Using Metasul Metal-on-Metal Bearings

Thirty-four hips were treated with cementless acetabular socket revisions using a metal-on-metal bearing. The causes of revision were aseptic loosening in 33 hips and septic loosening in 1 hip. Revisions were performed for acetabular sockets in 28 hips and for acetabular sockets and femoral stems in 6 hips. Mean follow-up duration was 6.2 years (range, 4.0-9.1 years), and mean Harris Hip Scores improved from 56 to 92 points. No hip required further revision for aseptic loosening. Focal femoral osteolysis newly developed in zone I in 1 hip, which was treated by curettage and bone grafting. The authors suggest that second-generation metal-on-metal bearings in cementless acetabular socket revisions can achieve good medium-term clinical and radiographic results.     

Fifteen-Year to Twenty-Year Results of Cementless Harris-Galante Porous Femoral and Harris-Galante Porous I and II Acetabular Components

This study examined long-term survivorship of primary total hip arthroplasty (THA) using cementless Harris-Galante porous femoral and Harris-Galante porous I or II acetabular components. Of 113 hips (101 patients) studied, 60 hips (53 patients) were available for follow-up at a mean of 17.2 years after surgery. A total of 10 hips had documented revision, and 2 hips had failed radiographically. The average Harris hip score was 82. Radiographically, 12 hips demonstrated eccentric wear, 8 had osteolysis, and 1 had a broken tine. The overall survival rate was 87.7%; the mean volumetric wear rate was 74.96 mm³; and the mean polyethylene linear penetration rate was 0.153 mm/y, similar to that of well-cemented THA in other series. This long-term outcome for an early-generation cementless THA is promising and provides a standard by which to judge the newer generation of cementless implants.     

Acetabular Revision With Intramedullary and Extramedullary Iliac Fixation for Pelvic Discontinuity

BackgroundParallel to the increase in revision hip procedures surgeons face more and more complex anatomical challenges with pelvic discontinuity (PD) being one of the worst-case scenarios. Here we report on our clinical results using an asymmetric acetabular component for the treatment of PD. The implant is armed in a monoblock fashion with an extramedullary iliac flange and provides the possibility to augment it with an intramedullary iliac press-fit stem.MethodsIn a single-center retrospective cohort study we analyzed prospectively collected data of 49 patients (35 female, 14 male) suffering from unilateral periprosthetic PD treated with an asymmetric acetabular component between 2009 and 2017. The mean follow-up was 71 months (21-114). Complications were documented and radiographic and functional outcomes were assessed.ResultsKaplan-Meier analysis revealed a 5-year implant survival of 91% (confidence interval 77%-96%). The 5-year survival with revision for any cause was 87% (CI 74%-94%). The overall revision rate was 16% (n = 8). Two patients required acetabular component revision due to aseptic loosening. Four patients (8%) suffered from periprosthetic infection: one patient was treated with a 2-stage revision, and another one with resection arthroplasty. The other 2 patients were treated with debridement, irrigation, and exchange of the mobile parts. Of 6 patients (12%) suffering from hip dislocation, 2 required implantation of a dual mobility acetabular component. The mean Harris Hip Score improved from 41 preoperatively to 79 at the latest follow-up (P < .001).ConclusionOur findings demonstrate that an asymmetric acetabular component with extramedullary and optional intramedullary iliac fixation is a reliable and safe treatment method for periprosthetic PD resulting in good clinical and radiographic mid-term results.     

A Distal Fluted,Proximal Modular Femoral Prosthesis in Revision Hip Arthroplasty

Most reports on the use of modular femoral stems during revision surgery have involved short follow-up periods. The authors evaluated the clinical and radiographic performance of 59 patients fitted with a distal fix modular stem. The average follow-up period was 8.2 years. Average Harris hip score was improved from 47 to 87.6. Of 19 patients with trochanteric osteotomy, 4 had a displaced greater trochanter. Re-revision was performed in 5 patients, and 3 of these were for subsidence (of these 3, subsidence was associated with dissociation of the coupling part in 1 and with osteotomy nonunion in other 2 [proximal component only]). Modular distally fixed femoral stems were found to offer intraoperative flexibility, but to suffer from subsidence and intraoperative greater trochanter and metaphyseal femoral fractures.     

Multiple Revision Surgeries and Acetabular Bone Defect Size May Predict Daily Activity After Revision Total Hip Arthroplasty

Background

We identified preoperative predictors and size of acetabular bone defects for poor return to daily activity after revision total hip arthroplasty.