Good implant survival after acetabular revision with extensive impaction bone grafting and uncemented components

Bone allograft impregnated with tobramycin and vancomycin delivers antibiotics in high concentrations for prophylaxis against bacteria commonly associated with prosthetic joint infections

Local delivery of antibiotics as prophylaxis for prosthetic joint infections (PJIs) is frequently used during total hip replacement surgery. Morselized bone allograft impregnated with vancomycin and tobramycin (TobraVanc) could provide effective prophylaxis against bacteria commonly associated with PJIs. In this study, the concentrations of antibiotics released by bone allograft impregnated with TobraVanc were determined by using an in vitro bioassay system entailing measuring inhibition zone diameters caused by antibiotic-impregnated bone chips cast in agar against standard curves. The concentrations were determined in samples of TobraVanc-impregnated bone graft taken before and after the application of the bone graft in the patients undergoing acetabular revision surgery. Antibiotic-impregnated bone grafts, sampled prior to application in the patient, delivered antibiotics in the concentration ranges of 730-9,800 mg/L for tobramycin and 1,300-11,000 mg/L for vancomycin. Samples taken after application in the patient released lower concentrations of tobramycin (490-1,900 mg/L; P < 0.01) and vancomycin (3,000-5,100 mg/L; P < 0.05); however, these concentrations remained well above the tobramycin minimum inhibitory concentrations (MICs) for investigated, highly tobramycin-resistant Staphylococcus epidermidis strains (MICs > 256 mg/L). At the tested concentrations, bone graft material mixed with TobraVanc delivered antibiotics in potent concentrations above the MICs for bacteria causing PJIs. Clinical trials are needed to evaluate the efficacy and risk of TobraVanc-impregnated bone graft as a prophylactic agent for patients undergoing hip replacement surgery.IMPORTANCEAntibiotic prophylaxis is the cornerstone of successful joint replacement surgery, reducing the risk for the dreaded complication of prosthetic joint infection (PJI) to roughly 0.5%-2% in standard total hip replacement (THR). In addition to systemic antibiotics, antibiotics added locally have the potential to reduce the PJI risk even further, because of the high concentrations that can be achieved in the joint with limited risk for systemic toxicity. The results in the current study show that bone chips impregnated with a combination of tobramycin and vancomycin (TobraVanc) release antibiotics in concentrations that are potent against common bacteria causing PJIs. Especially in high-risk patients, our results support the prophylactic use of TobraVanc in hip replacement surgery requiring the use of a bone graft. A clinical study testing the efficacy of TobraVanc-impregnated bone graft in reducing the incidence of PJI in hip replacement surgery is currently ongoing (EudraCT: 2021-001708-14).

Preoperative Three-Dimensional Planning Using Computed Tomography Improves Screw Placement in Patients Undergoing Acetabular Revision Surgery

Background

Stable fixation of joint replacement implants is essential to achieve osseointegration in uncemented implants. In acetabular revisions, screws often need to be utilized in quadrants other than the historically so-called "safe" zones to attain sufficient stability. The primary aim of this study was to determine whether preoperative three-dimensional (3D) planning for acetabular revision surgery influences screw length, specifically in the superior pubic ramus (SPR).

Methods

Between March 2017 and December 2021, 20 patients underwent preoperative two-dimensional (2D) planning (2D group), and 30 patients underwent 3D planning following the implementation of a new 3D planning software into clinical practice in September 2019 (3D group). Two observers, blinded to the groups, measured the total screw length, screw penetration depth, and cup position on available postoperative computed tomography examinations. For statistical comparisons, the mean measurement from the 2 observers was used.

Results

The median total screw lengths in the SPR were 16 mm in the 2D group and 25 mm in the 3D group (P = .004) and 40.5 mm compared with 50.5 mm in the ilium (P = .019). Median screw penetration depths in the SPR were 0 mm in the 2D group and 1.25 mm in the 3D group (P = .049).

Conclusion

Longer screws were used in the SPR and ilium when preoperative 3D planning was conducted. Due to the study design, we were not able to evaluate whether longer screws lead to better fixation. Further studies are needed to elucidate this question.

Outcomes of Impaction Bone Grafting in the Management of Acetabular Defects with the Use of Uncemented Acetabular Cups: Do Autografts and Irradiated Femoral Head Allografts Integrate?

Introduction

Acetabular impaction bone grafting (AIBG) has been used widely to reconstruct acetabular defects in complex primary and revision cases. The aim of this study was to look at the outcomes AIBG using either frozen irradiated femoral head allografts or autografts with uncemented acetabular cups.

Method

We retrospectively reviewed 38 patients who had AIBG and uncemented cup reconstruction of the acetabulum performed between 2008 and 2021 for complex primary and revision surgery. Graft incorporation, radiological loosening and cup migration were evaluated in follow-up X-rays.

Result

There were 24 complex primary and 14 revision total hip arthroplasty. Autografts were used in 10 hips with smaller defects, while 28 hips with larger defects required frozen irradiated femoral head allografts. Using Paprosky classification to evaluate acetabular defects; 8 patients were classified as 2A, 12 as 2B, 7 as 2C, 8 as 3A and 3 as 3B. The Kaplan-Meier survival rate for AIBG with uncemented cups in our series is 89.70% in 10 years. Acetabular cup position was anatomically restored in all autograft AIBG cases and in 25 out of 28 in the allograft group. The mean pre-operative Oxford Hip Score (OHS) was 19 (range 10-24) and post-operative OHS was 39 (range 21-48) (p < 0.001).

Conclusions

The mid- to long-term results for AIBG and uncemented acetabular cups is good. With newer and more porous uncemented cups especially revision cups, it may serve as an extended indication to achieve solid fixation together with AIBG technique in managing acetabular defects of ≤ 3A.

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.

Mid- to Long-term Follow-up of Severe Acetabular Bone Defect after Revision Total Hip Arthroplasty Using Impaction Bone Grafting and Metal Mesh

OBJECTIVE

In revision total hip arthroplasty (THA), reconstruction of severe acetabular bone defect continues to be problematic for orthopedic surgeons. This study reports the mid- to long-term survivorship, radiological outcomes, and complications of impaction bone grafting (IBG) and metal mesh with a cemented acetabular component in the reconstruction of severe acetabular bone defects in revision THA.

METHODS

This retrospective consecutive study included 26 patients (29 hips: type II B, four; type II C, three; type III A, 10; and type III B, 12) who underwent revision THA, which was performed using IBG and metal mesh, between 2007 and 2014 in our institution. All patients were followed up regularly for clinical and radiographical assessments. Migration and loosening of prosthesis graft integration and complications were observed and analyzed. Survival analysis was performed using a Kaplan-Meier survival analysis.

RESULTS

At the time of revision, 75.9% of the hips (22 hips) were classified as type III bone defects. The average follow-up period was 9.4 ± 2.8 (range, 2.4-14.0) years. Of the 29 hips, four hips (13.8%) were assessed as clinical failures; at the last follow-up, two had undergone re-revision THA, and two had not been scheduled for re-revision THA despite radiological failure of the acetabular component. Among them, three clinical failures (10.3%) were due to aseptic loosening, and one (3.4%) was due to infection. Radiographic evaluation showed bone graft integration in all hips during the follow-up. The Kaplan-Meier survivorship analysis revealed an acetabular reconstruction survival rate of 86.5% (95% confidence interval, 61.4%-95.7%) at 10 years.

CONCLUSION

IBG and metal mesh with a cemented acetabular component for revision THA is an effective technique for treating severe acetabular bone defects, with effective mid- to long-term outcomes due to the solid reconstruction of the acetabular bone defect and restoration of the hip rotation center.

Biphasic bone graft substitute in revision total hip arthroplasty with significant acetabular bone defects : a retrospective analysis

AIMS

Large acetabular bone defects encountered in revision total hip arthroplasty (THA) are challenging to restore. Metal constructs for structural support are combined with bone graft materials for restoration. Autograft is restricted due to limited volume, and allogenic grafts have downsides including cost, availability, and operative processing. Bone graft substitutes (BGS) are an attractive alternative if they can demonstrate positive remodelling. One potential product is a biphasic injectable mixture (Cerament) that combines a fast-resorbing material (calcium sulphate) with the highly osteoconductive material hydroxyapatite. This study reviews the application of this biomaterial in large acetabular defects.

METHODS

We performed a retrospective review at a single institution of patients undergoing revision THA by a single surgeon. We identified 49 consecutive patients with large acetabular defects where the biphasic BGS was applied, with no other products added to the BGS. After placement of metallic acetabular implants, the BGS was injected into the remaining bone defects surrounding the new implants. Patients were followed and monitored for functional outcome scores, implant fixation, radiological graft site remodelling, and revision failures.

RESULTS

Mean follow-up was 39.5 months (36 to 71), with a significant improvement in post-revision function compared to preoperative function. Graft site remodelling was rated radiologically as moderate in 31 hips (63%) and strong in 12 hips (24%). There were no cases of complete graft site dissolution. No acetabular loosening was identified. None of the patients developed clinically significant heterotopic ossification. There were twelve reoperations: six patients developed post-revision infections, three experienced dislocations, two sustained periprosthetic femur fractures, and one subject had femoral component aseptic loosening.

CONCLUSION

Our series reports bone defect restoration with the sole use of a biphasic injectable BGS in the periacetabular region. We did not observe significant graft dissolution. We emphasize that successful graft site remodelling requires meticulous recipient site preparation.Cite this article: Bone Jt Open 2022;3(12):991-997.

Uncemented Cups and Impaction Bone Grafting for Acetabular Bone Loss in Revision Hip Arthroplasty: A Review of Rationale, Indications, and Outcomes

Total hip arthroplasty (THA) is increasingly performed in young patients and the number of revisions is estimated to rise over time. Acetabular osteolysis and bone loss are frequently encountered during revision and may be classified and treated in different ways. Impaction bone grafting (IBG) with morselized allograft offers a viable option. IBG was introduced over 40 years ago in combination with cemented cups, and is also used with uncemented cups. The impacted bone chips act as a void filler to restore bone stock; once incorporated they are substituted by host bone. Surgery entails assessment of the defect, acetabular preparation, preparation of the morselized graft, impaction of the graft, and cup implantation. Satisfactory medium- and long-term results have now been reported in most studies. With the advent of high-porosity cups, indications have been extended, enhancing the potential of IBG, in which primary stability of the cup to the host bone is essential for a successful procedure. Synthetic bone substitutes have also been used in combination with allogenic grafts and may extend the original technique for which long-term studies are warranted.

Measurement of safe acetabular medial wall defect size in revision hip arthroplasty with a porous cup

INTRODUCTION

The majority of acetabular revisions can be performed with an uncemented, porous acetabular component with or without bone grafting. These are contained acetabular defects, with an intact acetabular rim (Paprosky type I and II). As defects of the medial wall of the acetabulum are a challenge situation revision surgery, we performed this biomechanical study on a pig pelvis model with contained acetabular defects to determine the size of medial wall defect at which the acetabular cup will have sufficient primary stability.

MATERIALS AND METHODS

In 24 pig pelvis models, different diameter of medial wall defects were created, followed by acetabular component placement. The acetabulum externally loaded, and the force at a level in which the acetabular component remains stable for each diameter of defect, or at which point the acetabular cup moves into the pelvis for >2 mm.

RESULTS

In the models with acetabular medial wall defects of 10 and 20 mm, 2 mm acetabular displacement occurred under a force between 1000 and 1500 N. In those with a medial wall defect of 25 mm, the force that caused acetabular instability was between 700 and 1000 N. In the models with 30 mm of medial wall defect all acetabular components were unstable under a force of 700 N.

CONCLUSIONS

According to our results, acetabular component should be stable if the defect of the medial wall of the acetabulum is less than 68% of the diameter of the acetabular component or if the uncovered surface area of the acetabular component is not greater than 27%, and the force <700 N. For a load of 1000 N, the medial wall defect should not exceed 45% of acetabular component diameter or 18% of uncovered acetabular component surface.

A Review and Description of Acetabular Impaction Bone Grafting: Updating the Traditional Technique

Restoring acetabular bone loss in revision hip arthroplasty is a major challenge for the orthopaedic surgeon. This paper discusses the traditional cemented technique of impaction bone grafting as applied to the acetabulum, as well as the evolution of the technique to employ uncemented implants. Some of the recent published literature regarding these techniques is reviewed and the personal experiences of the senior author with these techniques are also reported.

Impaction bone grafting in hip re-revision surgery

AIMS

Bone stock restoration of acetabular bone defects using impaction bone grafting (IBG) in total hip arthroplasty may facilitate future re-revision in the event of failure of the reconstruction. We hypothesized that the acetabular bone defect during re-revision surgery after IBG was smaller than during the previous revision surgery. The clinical and radiological results of re-revisions with repeated use of IBG were also analyzed.

METHODS

In a series of 382 acetabular revisions using IBG and a cemented component, 45 hips (45 patients) that had failed due to aseptic loosening were re-revised between 1992 and 2016. Acetabular bone defects graded according to Paprosky during the first and the re-revision surgery were compared. Clinical and radiological findings were analyzed over time. Survival analysis was performed using a competing risk analysis.

RESULTS

Intraoperative bone defect during the initial revision included 19 Paprosky type IIIA and 29 Paprosky type IIIB hips; at re-revision, seven hips were Paprosky type II, 27 type IIIA and 11 were type IIIB (p = 0.020). The mean preoperative Harris Hip Score was 45.4 (SD 6.4), becoming 80.7 (SD 12.7) at the final follow-up. In all, 12 hips showed radiological migration of the acetabular component, and three required further revision surgery. The nine-year cumulative failure incidence (nine patients at risk) of the acetabular component for further revision surgery was 9.6% (95% confidence interval (CI) 2.9 to 21.0) for any cause, and 7.5% (95% CI 1.9 to 18.5) for aseptic loosening. Hips with a greater hip height had a higher risk for radiological migration (odds ratio 1.09, 95% CI 1.02 to 1.17; p = 0.008).

CONCLUSION

Bone stock restoration can be obtained using IBG in revision hip surgery. This technique is also useful in re-revision surgery; however, a better surgical technique including a closer distance to hip rotation centre could decrease the risk of radiological migration of the acetabular component. A longer follow-up is required to assess potential fixation deterioration. Cite this article: Bone Joint J 2021;103-B(3):492-499.