Locking versus standard screw fixation for acetabular cups: is there a difference?

Early clinical and radiological outcomes of the new porous titanium shell in combination with locking screw in revision total hip arthroplasty

INTRODUCTION

Extensive acetabular bone loss and poor bone quality are two key challenges often encountered in revision total hip arthroplasty. A new 3D-printed porous acetabular shell has been made available with the option to insert multiple variable-angle locking screws. We sought to evaluate the early clinical and radiological outcomes of this construct.

METHODS

A retrospective review of patients operated by two surgeons was performed in a single institution. Fifty-nine revision hip arthroplasties were performed in 55 patients (34 female; mean age 68.8 ± 12.3 years) for Paprosky defects I (n = 21), IIA/B (n = 22), IIC (n = 9), III (n = 7) between February 2018 and January 2022 using the novel porous titanium acetabular shell and multiple variable angle locking screws. Postoperative clinical and radiographic outcomes were locally maintained. Patient-reported outcome measures collected included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Oxford Hip Score, and the 12-item Short Form Survey.

RESULTS

After a mean follow-up of 25.7 ± 13.9 months, two cases of shell migration were noted. One patient had a failed constrained mechanism and received revision to a cemented dual mobility liner. No other acetabular shells showed any evidence of radiographic loosening at the final follow-up. Preoperatively, 21 defects were classified as Paprosky grade I, 19 grade IIA, 3 grade IIB, 9 IIC, 4 grade IIIA, and 3 IIIB. The mean postoperative WOMAC function score was 84 (SD 17), WOMAC (stiffness) 83 (SD 15), WOMAC (pain) 85 (SD 15), and WOMAC (global) 85 (SD 17). The mean postoperative OHS was 83 (SD 15), and mean SF-12 physical score was 44 (SD 11).

CONCLUSION

The additional augmentation of porous metal acetabular shells with multiple variable-angle locking screws provides reliable initial fixation with good clinical and radiological outcomes in the short term. Further studies are needed to establish the medium- and long-term outcomes.

LEVEL OF EVIDENCE

IV.

Total Hip Arthroplasty with Cemented Dual Mobility Cup into a Fully Porous Multihole Cup with Variable Angle Locking Screws for Acetabular Fractures in the Frail Elderly

Purpose

The purpose was to examine the clinical and radiological outcomes after surgical treatment of acetabular fractures with total hip arthroplasty with a dual mobility cup cemented into a porous multihole cup in the population of frail elderly patients.

Materials and Methods

A retrospective review of 16 patients who underwent surgery (mean age, 76.7 years) with a mean follow-up period of 36.9 months was conducted. Following surgery, patients underwent postoperative follow-up at six weeks, three, six, and 12 months and clinical and radiological examinations were performed.

Results

Classification of fractures was based on the Letournel classification. Following surgery, all patients were allowed weight-bearing as tolerated immediately postoperative. Fourteen patients showed maintenance of preoperative mobility status at one year. The mean Harris hip score was 64.8 (range, 34.7-82.8) and 80.0 (range, 60.8-93.8) at three months and one year, respectively. The mortality rate was 12.5% at one year (2/16). Complications included heterotopic ossification (2/16), deep venous thrombosis (1/16), heamatoma (1/16), and femoral revision due to a Vancouver B2 fracture (1/16). No case of deep infection, dislocation, or implant loosening was reported.

Conclusion

Total hip arthroplasty using a dual mobility cup cemented into a porous multihole cup with locking screws resulted in a stable construct with a capacity for immediate weight-bearing as tolerated with rapid relief of pain. The findings of this study suggest that this procedure can be regarded as a safe method that has shown promising clinical and radiological outcomes for treatment of patients with medical frailty.

Minimum 2-Year Outcomes of a Novel 3D-printed Fully Porous Titanium Acetabular Shell in Revision Total Hip Arthroplasty

Background

Fully porous acetabular shells are an appealing choice for patients with extensive acetabular defects undergoing revision total hip arthroplasty (rTHA). This study reports on the early outcomes of a novel 3-D printed fully porous titanium acetabular shell in revision acetabular reconstruction.

Methods

A multicenter retrospective study of patients who received a fully porous titanium acetabular shell for rTHA with a minimum of 2 years of follow-up was conducted. The primary outcome was rate of acetabular revision.

Results

The final study cohort comprised 68 patients with a mean age of 67.6 years (standard deviation 10.4) and body mass index of 29.5 kg/m² (standard deviation 5.9). Ninety-four percent had a preoperative Paprosky defect grade of 2A or higher. The average follow-up duration was 3.0 years (range 2.0-5.1). Revision-free survivorship at 2 years was 81% for all causes, 88% for acetabular revisions, and 90% for acetabular revision for aseptic acetabular shell failure. Eight shells were explanted within 2 years (12%): 3 for failure of osseointegration/aseptic loosening (4%) after 15, 17, and 20 months; 3 for infection (4%) after 1, 3, and 6 months; and 2 for instability (3%). At the latest postoperative follow-up, all unrevised shells showed radiographic signs of osseointegration, and none had migrated.

Conclusions

This novel 3-D printed fully porous titanium shell in rTHA demonstrated good survivorship and osseointegration when used in complex acetabular reconstruction at a minimum of 2 years.

Level of evidence

IV, case series.

Are additional screws required for press-fit fixation of cementless acetabular cups? A systematic review and meta-analysis

Background

Press-fit cementless acetabular cup is widely used in total hip arthroplasty (THA). However, the use of additional screws for the acetabular cup has been extensively debated. The purpose of this review is to compare the stability, revision rate, wear rate, and clinical scores of cementless acetabular cups with and without screws in THA.

Materials and Methods

Comprehensive literature searches of the following databases were performed: Cochrane Library, Pubmed, Web of Science, OVID, Elsevier ClinicalKey, Clinicaltrials.gov, and EMBASE. We searched for trials that compared cementless acetabular cups with screws or without screws, and were published in the English language. We evaluated the stability of the prosthesis by osteolysis and migration. The clinical scores included Harris hip scores (HHS) and pain scores.

Results

Nineteen articles involving 4046 THAs met the inclusion criteria. Our analysis revealed that additional screws did not increase the stability of acetabular cups, and there was no statistical significance between the groups with and without screws in osteolysis and clinically relevant migration. Revision rates showed no significant difference between the groups with and without screws. There was no difference in wear between the two groups. Our analysis showed no difference in pain scores and HHS between groups.

Conclusion

Press-fit without screws could achieve sufficient acetabular cup stability. Acetabular cups without screws showed no difference from acetabular cups with screws in many outcomes. Additional screws are not required for cementless acetabular cups.

Level of evidence: Level III.

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.

Does the Use of Locking Screws Decrease the Rate of Hardware Removal in Ankle Fractures?

Background. While biomechanical characteristics of locking screw fixation versus traditional plating has been studied extensively in orthopaedic literature, clinical outcome studies are lacking. The goal of this study was to evaluate the efficacy and complications rate of locking versus traditional nonlocking screws in complex ankle fractures employing distal fibula internal fixation with 1/3 semitubular small fragment plates. Methods. A retrospective review was performed between January 2010 and June 2013 of all patients in whom internal fixation of the fibula in an ankle fracture (open or closed) was performed using only 1/3 semitubular small fragment fibular plates. Patient characteristics, fracture patterns, specific screw choice that were placed in the most distal 2 fibular plate holes (either locking or nonlocking), infectious wound complications, and concomitant syndesmotic injury and the need and corresponding purpose for hardware removal were recorded. Results. A total of 135 patients were found to meet inclusion criteria and were analyzed for this study. Of the patients with locking screws, 25 of 98 (25%) elected to have hardware removed, while 13 of 37 (35%) of those with nonlocking screws elected hardware removal. This did not reach statistical significance (P = .30). There was no statistically significant difference between the groups with regards to age, smoking status, body mass index, diabetes, or use of syndesmotic screw fixation. There was no significant difference in loss of fixation, infection, or other surgical complications in between the groups. Conclusions. There was no significant decrease in the rate of hardware removal with the use of 1/3 tubular locking versus nonlocking plates in the treatment of distal fibula fractures. Despite these screws locking flush to the plate, the hardware is equally symptomatic in both groups. There was no significant difference in the rate of complications between the 2 groups and our data suggest that the added expense of using locking screws routinely when fixing lateral malleolar fractures should be carefully considered, especially if the fracture pattern does not warrant locking technology. Levels of Evidence: Prognostic, Level III.

Changes in acetabular component alignment due to screw fixation in patients with hip dysplasia

INTRODUCTION

Adequate initial stability of the acetabular cup is essential for total hip arthroplasty (THA). However, changes in the alignment of the acetabular component caused by screw fixation are concerning in patients with inadequate bone stock. This study aimed to investigate the effects of screw fixation on the alignment of the acetabular component in THA patients with hip dysplasia.

METHODS

We retrospectively examined 256 hips (range 28-87 years) that underwent THA using a navigation system. Patients were divided into 2 groups based on the presence or absence of changes in the alignment of the intraoperative acetabular cup, and univariate and multivariate analyses were performed to identify factors that were predictive of changes in acetabular component alignment after screw fixation in 2 dimensions: inclination and anteversion.

RESULTS

Screw fixation led to a mean change in inclination of 1.6° (range 0-10°) and a mean change in anteversion of 1.4° (range 0-14°). The Crowe classification, the presence of bone cysts, and the use of an inferior quadrant screw were identified as factors that correlated with acetabular cup alignment changes in inclination (odds ratios, 6.01, 5.94 and 0.03, respectively). Only the Crowe classification was identified as a factor that correlated with intraoperative alignment changes in anteversion (odds ratio, 2.08).

CONCLUSIONS

Screw fixation altered the acetabular cup alignment. The inclination changes were related to the extent of the dysplasia, and the risk was reduced when the inferior quadrant screw was used. Surgeons should use caution during screw fixation in THAs performed on severely dysplastic hips.

Early aseptic loosening of the Tritanium primary acetabular component with screw fixation

Ultraporous acetabular components were developed to improve osseointegration and fit for increased longevity and better outcomes after total hip arthroplasty. There is a paucity of literature detailing this acetabular component's clinical performance, with even less detailing those with screw fixation. We identify 5 patients at our institution who underwent revision total hip arthroplasty for early aseptic acetabular cup loosening of an ultraporous acetabular component known as the Tritanium primary cup with secondary screw fixation. They all presented with groin and hip pain after index surgery and underwent follow-up radiographic examination consistent with component loosening requiring revision surgery. This case series reports on the risk of early acetabular cup loosening and its associated clinical presentation, workup, and surgical management in patients with the Tritanium primary cup augmented with screws.

Evaluation of the effect of custom burr holes on a surgeon's sense of screw fixation in revision porous metal cups

BACKGROUND/AIMS

It is common practice to burr custom holes in revision porous metal cups for screw insertion. The objective of this study was to determine how different hole types affect a surgeon's sense of screw fixation.

METHODS

Porous revision cups were prepared with pre-drilled and custom burred holes. Cups were held in place adjacent to synthetic bone material of varying density. Surgeons inserted screws through the different holes and materials. Surgeon subjective rating, compression, and torque was recorded.

RESULTS

The torque achieved was greater (p = 0.002) for screws through custom holes than pre-fabricated holes in low and medium density material, with no difference for high density. Peak compression was greater (p = 0.026) through the pre-fabricated holes only in high density material.

CONCLUSION

Use of burred holes affects the torque generated, and may decrease the amount of cup-acetabulum compression achieved.

No effect of additional screw fixation of a cementless, all-polyethylene press-fit socket on migration, wear, and clinical outcome

Background and purpose - Additional screw fixation of the all-polyethylene press-fit RM cup (Mathys) has no additional value for migration, in the first 2 years after surgery. However, the medium-term and long-term effects of screw fixation remain unclear. We therefore evaluated the influence of screw fixation on migration, wear, and clinical outcome at 6.5 years using radiostereometric analysis (RSA). Patients and methods - This study involved prolonged follow-up from a previous randomized controlled trial (RCT). We analyzed RSA radiographs taken at baseline and at 1-, 2-, and 6.5-year follow-up. Cup migration and wear were assessed using model-based RSA software. Wear was calculated as translation of the femoral head model in relation to the cup model. Total translation, rotation, and wear were calculated mathematically from results of the orthogonal components. Results - 27 patients (15 with screw fixation and 12 without) were available for follow-up at 6.5 (5.6-7.2) years. Total translation (0.50 mm vs. 0.56 mm) and rotation (1.01 degrees vs. 1.33 degrees) of the cup was low, and was not significantly different between the 2 groups. Wear increased over time, and was similar between the 2 groups (0.58 mm vs. 0.53 mm). Wear rate (0.08 mm/year vs. 0.09 mm/year) and clinical outcomes were also similar. Interpretation - Our results indicate that additional screw fixation of all-polyethylene press-fit RM cups has no additional value regarding medium-term migration and clinical outcome. The wear rate was low in both groups.

Polyaxial locking and compression screws improve construct stiffness of acetabular cup fixation: a biomechanical study

Bone ingrowth into uncemented acetabular components requires intimate cup-bone contact and rigid fixation, which can be difficult to achieve in revision hip arthroplasty. This study compares polyaxial compression locking screws with non-locked and cancellous screw constructs for acetabular cup fixation. An acetabular cup modified with screw holes to provide both compression and angular stability was implanted into a bone substitute. Coronal lever out, axial torsion and push-out tests were performed with an Instron testing machine, measuring load versus displacement. Polyaxial locking compression screws significantly improved construct stiffness compared with non-locked or cancellous screws. This increased construct stiffness will likely reduce interfacial micromotion. Further research is required to determine whether this will improve bone ingrowth in vivo and reduce cup failure.