Graft incorporation after acetabular and femoral impaction grafting with washed irradiated allograft and autologous marrow

Management of Bone Loss in Revision Total Knee Arthroplasty: An International Consensus Symposium

The evaluation, classification, and treatment of significant bone loss after total knee arthroplasty (TKA) continue to be a complex and debated topic in revision TKA (rTKA). Despite the introduction of new evidence and innovative technologies aimed at addressing the approach and care of severe bone loss in rTKA, there is no single document that systematically incorporates these newer surgical approaches. Therefore, a comprehensive review of the treatment of severe bone loss in rTKA is necessary. The Stavros Niarchos Foundation Complex Joint Reconstruction Center Hospital for Special Surgery, dedicated to clinical care and research primarily in revision hip and knee replacement, convened a Management of Bone Loss in Revision TKA symposium on June 24, 2022. At this meeting, the 42 international invited experts were divided into groups; each group was assigned to discuss questions related to 1 of the 4 topics: (1) assessing preoperative workup and imaging, anticipated bone loss, classification system, and implant surveillance; (2) achieving durable fixation in the setting of significant bone loss in revision TKA; (3) managing patellar bone loss and the extensor mechanism in cases of severe bone loss; and (4) considering the use of complex modular replacement systems: hinges, distal femoral, and proximal tibial replacements. Each group came to consensus, when possible, based on an extensive literature review and interactive discussion on their group topic. This document reviews each these 4 areas, the consensus of each group, and directions for future research.

Allograft Chip Incorporation in Acetabular Reconstruction: Multiscale Characterization Revealing Osteoconductive Capacity

BACKGROUND

Impacted bone-grafting with morselized allograft chips is commonly used to reconstruct acetabular bone defects in revision total hip arthroplasty (THA). While the overall clinical outcome of this procedure is described to be excellent, the microstructural basis and histological determinants of allograft incorporation remained to be further elucidated.

METHODS

The acetabula of 23 individuals with documented previous use of allograft chips during revision THA were explanted post mortem. The time that the allografts were in situ averaged 10.3 ± 4.5 years (range, 1.2 to 19.8 years). The host bone (HB)-allograft bone (AB) interface was characterized using a suite of high-resolution (HR) imaging techniques including HR-peripheral quantitative computed tomography (HR-pQCT), histological analysis, cellular histomorphometry, and scanning electron microscopy.

RESULTS

AB could be identified in 16 of the 23 cases. The HB and AB showed overlap (i.e., ingrowth) in 91.3% of the total interface. The mean ingrowth was 2.2 ± 1.0 mm with a maximum of 4.7 ± 2.1 mm. The periphery of the AB showed a tight interconnection with the HB associated with increased bone remodeling indices and increased trabecular thickness. While no association between the time in situ and the ingrowth was observed, the bone defect area was positively associated with the thickness of a fibrosis layer separating the ingrowth zone from the AB.

CONCLUSIONS

Allograft chips in revision THA form an adequate osseous foundation with successful incorporation through ingrowth of the HB (i.e., osteoconduction). While complete remodeling was not observed, larger defects were associated with fibrosis formation, which may compromise stability.

CLINICAL RELEVANCE

Our study provides the first systematic, multiscale long-term evaluation of chip allograft incorporation in revision THA to underscore its successful clinical use. As larger defects were associated with fibrous ingrowth, structural allografts may be superior for larger defects in terms of long-term outcomes.

The quality assessment of the University hospital bone bank in Central Serbia: the second audit after fourteen years

We analyzed the prevalence and predisposing factors for the overall rejection rate after retrieval of 267 fresh femoral head allografts over the past 7 years. The present study aimed to assess the quality system of institutional bone banking that can provide high-standard allografts with a low infection rate. Retrospective analysis of bone banking from June 2013 to December 2019 was conducted on 267 donors and 153 recipients. Of the 267 donated femoral heads, 74 were rejected, giving an overall rejection rate of 27.71%. The leading cause of allograft rejection was the inability to perform serology tests due to donor death; the absence of serological tests itself, and the donor refusal to perform the serology 6-month retest in 42 donors (15.72%). At retrieval, 12 allografts were positive, giving an overall contamination rate of 4.49%. Seven (2.62%) of the 267 allografts failed the blood screening tests. Thirteen allografts (4.86%) were discarded because of suspected damage to the packaging or disuse during surgery. An infection rate of 1.30% was found following transplantation. Over the past 7 years of bone banking, our results show that the overall rejection rate and the allograft-related infection rate correlate with international standards. The leading cause of allograft rejection was the inability to perform serology tests due to donor death and their refusal to perform the serology retests. Besides stringent aseptic allograft handling, donor motivation to participate in bone banking is extremely important for its efficient functioning.

A novel, multi-level approach to assess allograft incorporation in revision total hip arthroplasty

The successful use of allografts in reconstructive orthopedic surgery, including revision total hip arthroplasty (THA), has been outlined repeatedly. Nonetheless, as previous studies were primarily based on clinical follow-ups, we aimed to create an algorithm that accurately determines the extent of allograft incorporation in the acetabulum and femur using a suite of high-resolution imaging techniques. This study is based on a large patient database including > 4,500 patient data with previous revision THA and simultaneous use of allografts. While the database was continuously matched with the deceased individuals at the local forensic medicine department, complete hips were retrieved in case of a positive match. A positive match was achieved for n = 46 hips at a mean follow-up of 11.8 ± 5.1 years. Comprehensive imaging included contact radiography, high-resolution computed tomography (HR-pQCT), undecalcified histology of ground sections and quantitative backscattered electron imaging (qBEI). We here define a histomorphometric toolkit of parameters to precisely characterize the incorporation of structural (bulk) and morselized (chip) allografts in the acetabulum (n = 38) and femur (n = 8), including the defect area and interface length, microstructural and cellular bone turnover parameters as well as overlap and fibrosis thickness. This collection of samples, through its unique study design and precise definition of incorporation parameters, will provide the scientific community with a valuable source for further in-depth investigation of allograft incorporation and, beyond that, the regenerative potential of this osteoconductive scaffold.

Cellular Mechanisms Responsible for Success and Failure of Bone Substitute Materials

Bone grafts, i.e., autologous, allogeneic or synthetic bone substitute materials play an increasing role in reconstructive orthopedic surgery. While the indications and materials differ, it is important to understand the cellular mechanisms regarding their integration and remodeling, which are discussed in this review article. Osteoconductivity describes the new bone growth on the graft, while osteoinductivity represents the differentiation of undifferentiated cells into bone forming osteoblasts. The best case is that both mechanisms are accompanied by osteogenesis, i.e., bone modeling and remodeling of the graft material. Graft incorporation is mediated by a number of molecular pathways that signal the differentiation and activity of osteoblasts and osteoclasts (e.g., parathyroid hormone (PTH) and receptor activator of nuclear factor κβ ligand (RANKL), respectively). Direct contact of the graft and host bone as well as the presence of a mechanical load are a prerequisite for the successful function of bone grafts. Interestingly, while bone substitutes show good to excellent clinical outcomes, their histological incorporation has certain limits that are not yet completely understood. For instance, clinical studies have shown contrasting results regarding the complete or incomplete resorption and remodeling of allografts and synthetic grafts. In this context, a foreign body response can lead to complete material degradation via phagocytosis, however it may also cause a fibrotic reaction to the bone substitute. Finally, the success of bone graft incorporation is also limited by other factors, including the bone remodeling capacities of the host, the material itself (e.g., inadequate resorption, toxicity) and the surgical technique or preparation of the graft.

Burch-Schneider ring associated with morselized bone allografts, survival and clinical outcomes after acetabular revision surgery

INTRODUCTION AND OBJECTIVES

Acetabular revision surgery is a challenge due to the appearance of bone defects that make primary fixation of implants difficult when extracting loosened components. Reinforcement rings, such as Burch-Schneider (BS), have been shown to be allies in moderate or severe bone defects. The objective of the study is to evaluate the results and survival of these types of implants in acetabular revision surgery in the medium follow-up.

MATERIAL AND METHODS

Retrospective study on a cohort of 64 patients (67 replacements) with BS rings associated with morselized bone allografts in a 2 years minimum follow-up. Data were collected regarding clinical outcomes, graft incorporation, implant mobilization, survival and complications.

RESULTS

The mean follow-up was 5.06 years (R=2.2-12). The Merle scale improved from 8 points to 15 points at the end of follow-up (P<.0001) with 76.11% of good or excellent results. Reproduction of the anatomical centre of rotation was associated with a better result (P<.05). There was total or subtotal incorporation of the bone allograft in 97% of the patients, although this did not prevent a significant migration of the ring according to Gill criteria in 6 cases. We observed an overall survival of the implant for any cause of 93.4% at 5 years, and 84.6% at 10 years.

CONCLUSIONS

The BS reinforcement ring shows good results in the medium and long term enabling anatomical reconstruction in revision surgery as well as replacement of the bone stock. These results are also comparable and are a vast improvement on other rings.

[Management of complex acetabulum fractures and their consequences]

In the structure of pelvic bone injuries, acetabular fractures are the most complex type and, according to different authors, account for up to 20% [1]. The severity of these injuries is confirmed by the fact that early descriptions of acetabular fracture were based only on the results of autopsies of patients who had suffered a combined injury. Thus, as early as 1788, Callisen reported an acetabular fracture, but without a detailed description of the nature of the injury. In 1909, Schroeder provided a detailed report of 49 cases of acetabular fractures reported in the literature. Most of them were described during autopsies of patients who died from complications associated with hemorrhagic shock or the onset of sepsis [2]. Fractures of the acetabulum in most observations are the result of high-energy impacts, usually as a result of traffic accidents; therefore, the mechanism of injury determines the combined and multiple nature of the injuries in the victims. A significant proportion of acetabular fractures (up to 60%) are accompanied by fragment displacement and dislocation of the femoral head, in which the most severe tissue changes occur [3].

Clinical trial and in-vitro study comparing the efficacy of treating bony lesions with allografts versus synthetic or highly-processed xenogeneic bone grafts

Background

Our study aim was to compare allogeneic cancellous bone (ACB) and synthetic or highly-processed xenogeneic bone substitutes (SBS) in the treatment of skeletal defects in orthopedic surgery.

Methods

232 patients treated for bony lesions with ACB (n = 116) or SBS (n = 116) within a 10-year time period were included in this case–control study. Furthermore, both materials were seeded with human osteoblasts (hOB, n = 10) and analyzed by histology, for viability (AlamarBlue®) and protein expression activity (Luminex®).

Results

The complication rate was 14.2 %, proportion of defects without bony healing 3.6 %; neither outcome parameter differed comparing the intervention groups. Failed consolidation correlated with an increase in complications (p < 0.03). The rate of complications was further highly significant in association with the location of use (p < 0.001), but did not depend on age, ASA risk classification, BMI, smoking behavior or type of insurance. However, those factors did significantly influence the bony healing rate (p < 0.02). Complication and consolidation rates were independent of gender and the filling substances employed within the different locations. Histological examination revealed similar bone structures, whereas cell remnants were apparent only in the allografts. Both materials were biocompatible in-vitro, and seeded with human osteoblasts. The cells remained vital over the 3-week culture period and produced microscopically typical bone matrix. We observed initially increased expression of osteocalcin, osteopontin, and osteoprotegerin as well as leptin and adiponectin secretion declining after 1 week, especially in the ACB group.

Conclusion

Although both investigated materials appeared to be similarly suitable for the treatment of skeletal lesions in-vivo and in-vitro, outcome was decisively influenced by other factors such as the site of use or epidemiological parameters.

Supercharging irradiated allografts with mesenchymal stem cells improves acetabular bone grafting in revision arthroplasty

PURPOSE

The procedure of bone allografting associated with a reinforcement device is widely used for acetabulum revision. However in absence of biologic fixation of the allograft, failure of the reconstruction may occur. We made the hypothesis that it would be possible to load these grafts with bone marrow derived mesenchymal stem cells (MSC) to rescue the osteogenic capacity of an allogenic dead bone and therefore enhance incorporation of allografts with the host bone and decrease the number of failures related to the allograft.

METHOD

We identified 60 patients who had undergone acetabular component revision for aseptic failure of cemented implants associated with massive periacetabular osteolysis and Paprosky type 3A or 3B classification (without pelvic discontinuity) between 1996 and 2001. The study group of 30 patients received MSCs in the allograft and at the host graft junction. The average total number of MSCs received by each patient was 195,000 cells (range 86,000-254,000 cells). The control group of 30 patients had no MSCs in the allograft. Patients were matched for the size of periacetabular osteolysis (Paprosky type 3A or 3B). We compared the evolution of the allografts and evaluated cup migration and revision of the hips as end points at a minimum of 12 years or until failure.

RESULT

Better radiographic graft union rates and less allograft resorption were observed with allografts loaded with stem cells. Allograft resorption was significantly decreased in the group with allograft loaded with MSCs (1.2 cm(2) -range 0-2.3 cm(2)-of resorption on radiographs in the group with MSCs; versus 6 cm(2), range 2.1-8.5 cm(2) in the group without MSCs). The rate of mechanical failure was highest (p = 0.01) among the 30 patients with allograft without stem cells (9/30; 30 %) compared with no failures for patients with allograft loaded with stem cells. Revision of the cup was necessary in nine patients in the control group. No revision was performed in the 30 patients of the study group with MSCs.

CONCLUSION

For acetabular defect reconstruction, loading the allograft with MSCs has resulted in a lower rate of failure as compared with allograft without MSCs.

Supercharging allografts with mesenchymal stem cells in the operating room during hip revision

PURPOSE

Bone marrow derived mesenchymal stem cells (BM-MSCs) have been proposed to improve allografts used during hip revision. However, no study has reported the number of MSCs that could be associated with the allograft and the best technique to load MSCs in allografts. The optimal loading technique should combine methods to increase the initial cell density and create an appropriate environment to accelerate the efficiency of the cell-allograft constructs into clinically applicable grafts. We designed a study to evaluate the number of MSCs in an autograft femoral head considered as the gold standard and to determine the best operating room procedure for loading in allograft with MSCs to approach the same number as in an autograft femoral head. Therefore this study explored a potential of charging whole femoral head allografts with autologous MSCs from iliac crest aspirate for hip revision procedures.

METHODS

First, the study evaluated the total number of mesenchymal stem cells (MSCs) in 1 cc of an average autograft femoral head; this number then serves as a target for loading allografts, in order to achieve the same density of MSCs. For the loading technique itself, several questions were asked and hence several options were investigated. For example, is it better to load the whole allograft or break it up into several fragments? Which way of injecting works best for the whole femoral head allograft (through cartilage or femoral neck)? How concentrated (in terms of MSCs) should the injected iliac crest marrow be? Bone marrow for injection in allografts was obtained from residual marrow from patients undergoing surgical procedures with concentrated bone marrow. With this bone marrow (with and without concentration) we tested different techniques (injection and soaking) to load stem cells in allografts of different sizes: bulk allografts, pieces or blocks (8 or 1 cm(3) blocks) and morselized fragments (from 125 to 8 mm(3)) or particules (1 mm(3)). We also evaluated the release of MSCs from fragments of autografts and allografts loaded with MSCs in cultured medium.

RESULTS

The femoral head autografts contained a lower concentration of MSCs than the iliac crests of the same patient. However, in absence of concentration, with bone marrow aspirated from the iliac crest, we were not able to load in the femoral head allograft the same number of MSCs as the number present in an autograft. The loaded volume of bone marrow (and the corresponding number of MSCs) depended on the technique (injecting, soaking) as well as on the volume and shape of the allografts. The seeding efficiency of loading MSCs in allografts increased with the concentration of MSCs in the bone marrow. With concentrated bone marrow, supercharging the allograft with MSCs (as compared with an autograft) was possible in the operating room, and the number of MSCs supercharged in allografts was predictable.

CONCLUSIONS

The loaded volume of bone marrow depended on the technique (injecting, soaking) as well as on the volume and shape of the allografts. With concentrated bone marrow, the allograft could be charged with a similar or higher number of MSCs than the number present in a femoral head autograft.

Impaction grafting of the acetabulum with ceramic bone graft substitute: high survivorship in 43 patients with a mean follow-up period of 4 years

BACKGROUND AND PURPOSE

Loss of bone stock remains a challenge in revision hip surgery. Grafting with allograft is well established, but there are problems with availability, cost, infection, antigenicity, reproducibility, and stability of the created construct. BoneSave is a biphasic porous ceramic consisting of sintered 80% tricalcium phosphate and 20% hydroxyapatite. In vitro and in vivo studies, including its use mixed with allograft, have shown good results in impaction grafting. This is the first reported series of its use alone in impaction grafting of the acetabulum.

METHODS

We conducted a retrospective review of a cohort of 43 consecutive patients undergoing impaction grafting of contained acetabular defects by multiple surgeons at a single centre. All patients received uncemented acetabular components. They were followed up radiographically, together with self-reported satisfaction scale (SAPS), Oxford hip score (OHS), and Short-Form 12 (SF12) health survey. Kaplan-Meier survivorship analysis was performed with revision of the acetabular component, revision of any part of the construct, and reoperation as endpoints.

RESULTS

The fate of all cases was known. Mean follow-up was 4 years. 5 patients died during follow-up, with their constructs in situ. The survivorship of the acetabular component was 98% (95% CI: 85-100) at 7 years. 1 acetabular component was revised for infection and there was 1 radiographic acetabular failure. The median OHS was 36 (6-48), the median SF12 PCS was 36 (14-57), the median SAPS was 75 (0-100), and the median SF12 MCS was 50 (23-64). The graft material had incorporated in all 3 zones of the acetabulum in 33 out of 37 cases with complete radiographic follow-up.

INTERPRETATION

Medium-term results show that BoneSave alone is a reliable material for impaction grafting of contained defects in the acetabulum at revision surgery.

Impaction grafting of the acetabulum with ceramic bone graft substitute mixed with femoral head allograft: high survivorship in 43 patients with a median follow-up of 7 years: a follow-up report

BACKGROUND AND PURPOSE

Restoration of bone stock at revision hip surgery remains a challenge. Alternative graft materials with suitable mechanical properties for impaction grafting have been sought due to issues with infection, antigenicity, cost, and availability of allograft. We have previously presented good short-term results of the use of BoneSave, a biphasic porous ceramic bone graft substitute, consisting of sintered 80% tricalcium phosphate and 20% hydroxyapatite, in a 50:50 mix with femoral head allograft. We now present the medium-term results.

METHODS

We conducted a retrospective review of a cohort of 43 consecutive patients undergoing impaction grafting of contained acetabular defects by multiple surgeons at a single center. 34 patients received uncemented acetabular components and 9 received cemented components. Patients were followed up radiographically and with the self-reported satisfaction scale (SAPS), Oxford hip score (OHS), and the Short-Form 12 (SF12) health survey. Kaplan-Meier survivorship analysis was performed with revision of the acetabular component, revision of any part of the construct, and reoperation as endpoints.

RESULTS

The fate of all cases was known. Median follow-up of the surviving patients was 80 (69-106) months. 15 patients died during the follow-up period, 14 with their construct in situ. The survivorship of the grafted acetabulum and acetabular component was 94% (95% CI: 99-78) at 7 years. 1 patient had been revised for aseptic loosening of the acetabulum and 1 for deep infection. The mean OHS was 31 (SD 12), the mean SF12 physical-component score (PCS) was 38 (SD 13), the median SAPS was 83 (0-100), and the median SF12 mental-component score (MCS) was 55 (23-65). The graft material became incorporated in all 3 zones of the acetabulum in 23 out of 24 cases that had complete radiographic follow-up.

INTERPRETATION

These medium-term results show that BoneSave is a reliable material for impaction grafting of the acetabulum when used in conjunction with femoral head allograft.

Femoral impaction grafting

Femoral impaction grafting is a reconstruction option applicable to both simple and complex femoral component revisions. It is one of the preferred techniques for reconstructing large femoral defects when the isthmus is non-supportive. The available level of evidence is primarily derived from case series, which shows a mean survivorship of 90.5%, with revision or re-operation as the end-point, with an average follow-up of 11 years. The rate of femoral fracture requiring re-operation or revision of the component varies between several large case series, ranging from 2.5% to 9%, with an average of 5.4%.

Acetabular impaction grafting in total hip replacement

BACKGROUND AND PURPOSE

Acetabular impaction grafting has been shown to be very effective, but concerns regarding its suitability for larger defects have been highlighted. We report the use of this technique in a large cohort of patients, and address possible limitations of the technique.

METHODS

We investigated a consecutive group of 339 cases of impaction grafting of the cup with morcellised impacted allograft bone for survivorship and mechanisms for early failure.

RESULTS

Kaplan Meier survival was 89.1% (95% CI 83.2 to 95.0%) at 5.8 years for revision for any reason, and 91.6% (95% CI 85.9 to 97.3%) for revision for aseptic loosening of the cup. Of the 15 cases revised for aseptic cup loosening, nine were large rim mesh reconstructions, two were fractured Kerboull-Postel plates, two were migrating cages, one was a medial wall mesh failure and one had been treated by impaction alone.

INTERPRETATION

In our series, results were disappointing where a large rim mesh or significant reconstruction was required. In light of these results, our technique has changed in that we now use predominantly larger chips of purely cancellous bone, 8-10 mm3 in size, to fill the cavity and larger diameter cups to better fill the aperture of the reconstructed acetabulum. In addition we now make greater use of i) implants made of a highly porous in-growth surface to constrain allograft chips and ii) bulk allografts combined with cages and morcellised chips in cases with very large segmental and cavitary defects.

Bioactive and osteoinductive bone graft substitutes: definitions, facts and myths

The use of artificial bone grafts has been developed over recent years and is expected to increase further, for some indications even replacing the gold standard, autograft, in trauma and reconstructive surgery. However, the effectiveness of these materials is still a subject of debate, mostly because of unclear definitions or limited market surveillance. In this overview several facts and myths regarding bone-graft substitutes are summarized.

The survival and fate of acetabular reconstruction with impaction grafting for large defects

BACKGROUND

Impaction bone grafting has been used for acetabular reconstruction in revision surgery. However, most series do not establish differences in survival in revisions with differing severity of bone loss.

QUESTIONS/PURPOSES

We therefore determined (1) the survival rate for rerevision associated with varying degrees of bone loss; (2) the frequency with which bone graft resorption occurred; and (3) whether the reconstruction restored the anatomic center of rotation of the hip.

METHODS

We retrospectively reviewed 165 patients (181 hips) who underwent rerevision for major bone loss. Using the classification of Paprosky et al. 98 hips had a Grade 3A defect and 83 a Grade 3B. We determined survival rates for revision and graft resorption. Cup position was determined measuring vertical and horizontal positions and the distance from the center of the prosthetic femoral head to the normal center of rotation of the hip in both groups according to Ranawat. The minimum followup until rerevision or the latest evaluation was 0.3 years months (mean, 7.5 years; range, 0.3-17.7 years).

RESULTS

The survival rate for revision at 8 years was 84% (95% confidence interval: 61-100) for Grade 3A and 82% (95% confidence interval: 68-100) for Grade 3B. Twelve hips were rerevised. Seventeen grafts showed bone resorption. Acetabular cup position was anatomically restored in both Grades 3A and 3B.

CONCLUSIONS

The midterm results for impacted bone allograft and cemented all-polyethylene cups were similar in both Grade 3A and Grade 3B hips. Acetabular reconstruction allows anatomic positioning of the cups and is associated with a low rate of rerevision.

Fresh-frozen vs. irradiated allograft bone in orthopaedic reconstructive surgery

The use of allograft bone is increasingly common in orthopaedic reconstruction procedures. The optimal method of preparation of allograft bone is subject of great debate. Proponents of fresh-frozen graft cite improved biological and biomechanical characteristics relative to irradiated material, whereas fear of bacterial or viral transmission warrants some to favour irradiated graft. Careful review of the literature is necessary to appreciate the influence of processing techniques on bone quality. Whereas limited clinical trials are available to govern the selection of appropriate bone graft, this review presents the argument favouring the use of fresh-frozen bone allograft as compared to irradiated bone.

Impaction bone grafting of the acetabulum at hip revision using a mix of bone chips and a biphasic porous ceramic bone graft substitute

BACKGROUND AND PURPOSE

One of the greatest problems of revision hip arthroplasty is dealing with lost bone stock. Good results have been obtained with impaction grafting of allograft bone. However, there have been problems of infection, reproducibility, antigenicity, stability, availability of bone, and cost. Thus, alternatives to allograft have been sought. BoneSave is a biphasic porous ceramic specifically designed for use in impaction grafting. BoneSave is 80% tricalcium phosphate and 20% hydroxyapatite. Previous in vitro and in vivo studies have yielded good results using mixtures of allograft and BoneSave, when compared with allograft alone. This study is the first reported human clinical trial of BoneSave in impaction grafting.

METHODS

We performed a single-institution, multi-surgeon, prospective cohort study. 43 consecutive patients underwent revision hip arthroplasty using BoneSave and allograft to restore missing bone in the acetabulum. 9 patients had cemented acetabular components implanted and 34 uncemented. 10 patients had cemented femoral components implanted and 1 had an uncemented femoral component. 32 patients did not have their femoral component revised.

RESULTS

No patients were lost to follow-up. At a mean follow-up of 24 (11-48) months, there were no re-revisions and there was no implant migration. 1 acetabular component had confluent lucent lines at the implant-graft interface. Complications were rare (1 fracture, 2 dislocations). Patient satisfaction with the procedure was high.

INTERPRETATION

Short-term results indicate that impaction grafting of BoneSave and allograft is an effective method of dealing with loss of bone stock at revision hip surgery.

Subsidence of the stem after impaction bone grafting for revision hip replacement using irradiated bone

Loss of bone stock is a major problem in revision surgery of the hip. Impaction bone grafting of the femur is frequently used when dealing with deficient bone stock. In this retrospective study a consecutive series of 68 patients (69 hips) who had revision of a hip replacement with femoral impaction grafting were reviewed. Irradiated bone allograft was used in all hips. Radiological measurement of subsidence of the stem, incorporation of the graft and remodelling was carried out and showed incorporation of the graft in 26 of 69 hips (38%). However, there was no evidence of trabecular remodelling. Moderate subsidence of 5 mm to 10 mm occurred in ten hips (14.5%), and massive subsidence of > 10 mm in five (7.2%). The results of this study are less favourable than those of others describing studies of revision of the femoral stem using impaction bone grafting. The absence of the characteristic changes of graft remodelling noted in other series raises the question as to whether irradiated bone graft may be a significant factor influencing the post-operative outcome.

Acetabular bone reconstruction in revision arthroplasty: a comparison of freeze-dried, irradiated and chemically-treated allograft vitalised with autologous marrow versus frozen non-irradiated allograft

Deficiencies of acetabular bone stock at revision hip replacement were reconstructed with two different types of allograft using impaction bone grafting and a Burch-Schneider reinforcement ring. We compared a standard frozen non-irradiated bone bank allograft (group A) with a freeze-dried irradiated bone allograft, vitalised with autologous marrow (group B). We studied 78 patients (79 hips), of whom 87% (69 hips) had type III acetabular defects according to the American Academy of Orthopaedic Surgeons classification at a mean of 31.4 months (14 to 51) after surgery. At the latest follow-up, the mean Harris hip score was 69.9 points (13.5 to 97.1) in group A and 71.0 points (11.5 to 96.5) in group B. Each hip showed evidence of trabeculation and incorporation of the allograft with no acetabular loosening. These results suggest that the use of an acetabular reinforcement ring and a living composite of sterile allograft and autologous marrow appears to be a method of reconstructing acetabular deficiencies which gives comparable results to current forms of treatment.

Allograft and bone morphogenetic proteins: an overview

Allograft is frequently used in orthopaedic and trauma surgery. On top of safety issues its biological activity is limited also due to processing. Consequently, the combination of allograft with osteoinductive substances may increase its effectiveness and decrease failure rates. In particular Bone Morphogenetic Proteins (BMPs) seem to be a promising partner for clinical applications. This overview focuses on the combined application of allograft/BMPs. Current points of view from available literature are summarized.

Favorable survival of acetabular reconstruction with bone impaction grafting in dysplastic hips

Acetabular bone loss hampers implantation of a total hip arthroplasty in patients with developmental dysplasia of the hip. The bone impaction grafting technique in combination with a cemented total hip can restore the bone stock in these patients, but do these reconstructions yield satisfying long-term results? We used this technique in 28 hips (22 consecutive patients). The degree of dislocation was graded preoperatively as Crowe I in five hips, Crowe II in eight hips, Crowe III in nine hips, and Crowe IV in four hips. We present the long-term results of this bone impaction grafting technique a minimum of 10 years after surgery. Two patients died before the minimum followup of 10 years, leaving 20 patients (26 hips). Two cups were revised, one cup for a sciatic nerve palsy (at 2 years) and the other for aseptic loosening after 12 years. The cumulative survival of the cup with revision for any reason as the end point was 96% at 10 years and 84% at 15 years. There were no femoral revisions during followup. The bone impaction grafting technique in combination with a cemented cup is an effective technique for developmental dysplasia of the hip with favorable long-term results.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.