The use of structural distal femoral allografts for acetabular reconstruction. Surgical technique

The biological acetabular reconstruction with bone allografts in hip revision arthroplasty

BACKGROUND

Reconstructions in case of acetabular bone loss in hip revision arthroplasty are challenging. A few techniques have been proposed, with inconstant outcomes. Biological reconstructions using bone allografts may address the acetabular bone loss and restore the hip anatomy. Aim of this work was the description of the surgical technique and the evaluation of the outcomes using a regional arthroplasty register.

MATERIALS AND METHODS

Minor or massive bone allografting was performed in hip revision arthroplasties in a tertiary center. Bulk allografts were used in severe acetabular bone losses. Fresh-frozen femoral heads were impacted in the bone cavity and porous cups were implanted; multihole sockets were used when necessary. In DeLee A zone, no grafts were used in order to reduce overstress graft resorption. The results were evaluated using a regional arthroplasty register, and a comparison with revisions without bone grafts was performed investigating re-revision rates and reasons for further revisions.

RESULTS

At 10 years, acetabular revisions with bone allografts achieved a similar survival rate than revisions without bone grafts. The re-revisions occurred more frequently in revisions without bone allografts (10.8 vs. 9.7%). In the allograft cohort, septic loosening was lower (0.3 vs. 2.6%), whereas a higher rate of aseptic cup loosening was experienced (2.7 vs. 1.4%).

CONCLUSIONS

Bone allografts may provide a good restoration of the acetabular bone stock and the hip biomechanics. Septic loosening does not seems a major concern, whereas a higher rate of aseptic cup loosening should be expected when bone grafts are used.

Bone grafts, bone graft extenders, substitutes and enhancers for acetabular reconstruction in revision total hip arthroplasty

Acetabular bone loss is a relevant concern for surgeons dealing with a failed total hip arthroplasty.

Since the femoral head is no longer available, allografts represent the first choice for most reconstructive solutions, either as a structural buttress or impacted bone chips.

Even though fresh-frozen bone is firmly recommended for structural grafts, freeze-dried and/or irradiated bone may be used alternatively for impaction grafting. Indeed, there are some papers on freeze-dried or irradiated bone impaction grafting, but their number is limited, as is the number of cases.

Xenografts do not represent a viable option based on the poor available evidence but bioactive bioceramics such as hydroxyapatite and biphasic calcium phosphates are suitable bone graft extenders or even substitutes for acetabular impaction grafting.

Bone-marrow-derived mesenchymal stem cells and demineralised bone matrix seem to act as reliable bone graft enhancers, i.e. adjuvant therapies able to improve the biological performance of standard bone grafts or substitutes. Among these therapies, platelet-rich plasma and bone morphogenetic proteins need to be investigated further before any recommendations can be made.

Cite this article: EFORT Open Rev 2016;1:431-439. DOI:10.1302/2058-5241.160025

Development of a Three-Dimensional (3D) Printed Biodegradable Cage to Convert Morselized Corticocancellous Bone Chips into a Structured Cortical Bone Graft

This study aimed to develop a new biodegradable polymeric cage to convert corticocancellous bone chips into a structured strut graft for treating segmental bone defects. A total of 24 adult New Zealand white rabbits underwent a left femoral segmental bone defect creation. Twelve rabbits in group A underwent three-dimensional (3D) printed cage insertion, corticocancellous chips implantation, and Kirschner-wire (K-wire) fixation, while the other 12 rabbits in group B received bone chips implantation and K-wire fixation only. All rabbits received a one-week activity assessment and the initial image study at postoperative 1 week. The final image study was repeated at postoperative 12 or 24 weeks before the rabbit scarification procedure on schedule. After the animals were sacrificed, both femurs of all the rabbits were prepared for leg length ratios and 3-point bending tests. The rabbits in group A showed an increase of activities during the first week postoperatively and decreased anterior cortical disruptions in the postoperative image assessments. Additionally, higher leg length ratios and 3-point bending strengths demonstrated improved final bony ingrowths within the bone defects for rabbits in group A. In conclusion, through this bone graft converting technique, orthopedic surgeons can treat segmental bone defects by using bone chips but with imitate characters of structured cortical bone graft.

Evaluation of the fixation of the trabecular metal wedge in patients undergoing revision of total hip arthroplasty

OBJECTIVE

this study aimed to evaluate the fixation of the trabecular metal wedge in patients undergoing revision of total hip arthroplasty.

METHODS

twenty-three cases with minimum grading of Paprosky II-B that were operated between July 2008 and February 2013 were evaluated. These cases were evaluated based on radiographs before the operation, immediately after the operation and later on after the operation. Loss of fixation was defined as a change in the abduction angle of the component greater than 10° or any mobilization greater than 6 mm.

RESULTS

it was found that there was 100% fixation of the acetabula after a mean of 29.5 months. One case underwent removal of the implanted components due to infection.

CONCLUSIONS

there is still no consensus regarding the best option for reconstructing hips with bone loss. However, revision using a trabecular metal wedge has presented excellent short- and medium-term results. This qualifies it as an important tool for achieving a fixed and stable acetabular component.

Combined debridement, bone graft and articular cavity sealing using synovium in treating metaphyseal osteomyelitis involving knee joints

The aim of this study was to investigate the efficacy of combined debridement, bone graft and articular cavity sealing using synovium in the treatment of metaphyseal osteomyelitis involving the knee joint. Eleven patients with metaphyseal osteomyelitis, which involved femurs in 4 patients and tibiae in 7, were included. The patients received a novel treatment, which combined debridement, bone graft and articular cavity sealing using the synovium. Of the 11 patients, 4 patients with knee joint instability received a structural allograft and 7 with a stable knee joint underwent a particulate bone graft. The 11 patients underwent regular clinical and radiological evaluation; the average follow-up was 74 months (range, 58–96). Infection recurrence in the joint and bone graft area was not observed in 10 of the 11 cases. In one patient, who underwent a lateral granular cancellous bone allograft in the right tibial plateau, the infection recurred 2 weeks later in the graft area. The infection was arrested 3 months after re-debridement and a bilateral ilium bone graft to eliminate the dead space. Combined debridement, bone graft and articular cavity sealing using the synovium may be a feasible treatment for metaphyseal osteomyelitis involving the knee joint.

Multiple Acetabular Revisions in THA - Poor Outcome Despite Maximum Effort

A consecutive series of 52 acetabular revisions was evaluated retrospectively. Inclusion criteria for all patients were at least one former exchange of the acetabular component. Reconstruction was performed with reliable techniques and implants other than extensively porous coated device (e.g. tantalum). The mean follow up was 5.63 (0.01-14.05) years. Cumulative survival at 14.05 years with removal of the acetabular component due to aseptic loosening or the worst case criterion (removal of the acetabular component for any cause and/or lost to follow-up) as the end point was 66.38 (95 % C.-I.: 47.80-84.96) % and 58.42 (95 % C.-I.: 41.01-75.83) %, respectively. The cumulative survival rate with mechanical failure of the acetabular reconstruction as the endpoint was significantly lower in patients with two or more previous revisions in comparison to those with only one former procedure (log rank test: p=0,0112 respectively). The mean Merle d'Aubignée-score improved from 7.3 (0-14) preoperatively to 10.6 (0-17) points at latest follow up examination.Survival of acetabular reconstructions with common techniques and implants is decreasing with the number of previous revisions. This may cause major concerns with regard to the rising number of patients needing repeated revisions. Maximizing durability of primary THA, precise preoperative planning as well as improved techniques and implants for revision may decrease this problem in the long term.

Tantalum augments for Paprosky IIIA defects remain stable at midterm followup

BACKGROUND

Initial reports with short-term followup of porous tantalum acetabular components and augments for Paprosky IIIA acetabular defects demonstrate high hip scores, low rates of aseptic loosening, and low rates of complications. However, longer-term followup with a larger cohort is needed to determine the durability of these reconstructions.

QUESTIONS/PURPOSES

We therefore determined the functional scores, rates of aseptic loosening, and complications in patients with Paprosky IIIA acetabular defects treated with porous tantalum acetabular components and augments.

METHODS

We retrospectively reviewed 37 acetabular revisions in 36 patients (one patient with bilateral revisions) treated with a porous tantalum acetabular component and augment. All patients had defects classified as Type IIIa using the system of Paprosky et al. Harris hip scores were obtained and radiographic examination was performed before surgery and through most recent followup. The minimum followup was 26 months (mean, 60 months; range, 26-106 months).

RESULTS

One patient developed aseptic loosening of the acetabular reconstruction requiring revision; seven other patients required further surgery for periprosthetic femoral fracture (two), acute infection (three), and recurrent dislocation (two). Thirty-five of 37 hips had no or occasional pain at final followup. Mean Harris hip scores improved from 33.0 preoperatively (range, 12.6-58.7) to 81.5 postoperatively (range, 27.0-99.8).

CONCLUSIONS

Although the complication rate requiring further surgery was considerable, most patients with these reconstructions had pain relief and reasonable function with low rates of loosening at midterm followup.

LEVEL OF EVIDENCE

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

Does an enhanced surface finish improve acetabular fixation in revision total hip arthroplasty?

High-porosity "cancellous metal" coatings have been introduced to increase the fixation and biologic incorporation of acetabular cups. The strength of initial fixation provided by a cancellous metal cups vs conventional alternatives in the deficient revision acetabulum was investigated. Cancellous, plasma-sprayed, and beaded cups (n = 9) were implanted under controlled conditions into a validated model of the revision acetabulum. The greatest differences were seen in resistance to catastrophic (spin-out) failure that, for the cancellous shell, averaged 1076 ± 265 N, which was 25% greater than the plasma-sprayed implant (859 ± 214 N, P = .04) and 218% greater than the beaded implant (338 ± 123 N, P < .01). The cancellous coating also provided greater resistance to ultimate failure. These results suggest that these new cancellous metal coatings may represent a promising alternative for fixation in revision total hip arthroplasty.

Does a cemented cage improve revision THA for severe acetabular defects?

BACKGROUND

Evidence suggests a growing incidence of revision total hip arthroplasty (THA) including a subset with large acetabular defects. Revision THA for severe acetabular bone loss is associated with a relatively high rate of mechanical failure.

QUESTIONS/PURPOSES

We questioned whether cementing a cage to the reconstructed acetabular defect and pelvis would improve the rate of mechanical failure for patients with Type 3 defects (Paprosky et al.) with and without pelvic discontinuity in comparison to historical controls.

METHODS

We retrospectively collected data on 33 patients who underwent 35 revision THAs using an acetabular reconstruction cage cemented to morselized allograft and either structural allograft or trabecular metal augmentation for Type 3 defects in the presence (n = 13) and absence (n = 22) of pelvic discontinuity at a mean followup of 59 months (range, 24-92 months). The primary outcome was mechanical failure, defined as revision of the acetabular reconstruction for aseptic loosening.

RESULTS

Revision surgery for mechanical failure occurred in four of the 13 patients with pelvic discontinuity and two of the 22 patients without discontinuity. Radiographic loosening occurred in one patient with and one patient without pelvic discontinuity. Seven of the 35 revisions were subsequently revised for deep infection all in patients who were immunocompromised.

CONCLUSIONS

Cementing the cage to the pelvis can offer an advantage for treating severe acetabular defects. Trabecular metal augmentation appears to provide better initial mechanical stability than a structural allograft, but successful allograft reconstruction may restore bone stock.

LEVEL OF EVIDENCE

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

[Reconstruction of the acetabulum with structured bone graft in press-fit technique]

OBJECTIVE

Reconstruction of defects of the superior acetabular rim with structured bone grafts in press-fit technique before total hip replacement.

INDICATIONS

Defects of the superior acetabular rim following hip dysplasia Crowe type II-IV, avascular necrosis of the femoral head Ficat stage IV, or aseptic loosening of the cup with acetabular defects Paprosky type 2a and 2b.

CONTRAINDICATIONS

Acetabular defects Paprosky type 2c, 3a and 3b, septic loosening, severe osteoporosis.

SURGICAL TECHNIQUE

Exposure of the acetabular defect and debridement with a spherical reamer to create a concave bleeding graft bed. Shaping of the bone graft with an inverted reamer of corresponding size and oscillating saw. Press-fit insertion of the bone graft into the defect and temporary fixation with Kirschner wires. Rereaming of the acetabulum with the spherical reamer. Implantation of a cemented cup of corresponding size. Removal of Kirschner wires after setting of cement.

POSTOPERATIVE MANAGEMENT

Full weight bearing in case of small or medium graft, 6-week non-weight bearing in case of big load-bearing graft. Mobilization on 1st day postoperatively. Stair climbing on 7th day postoperatively. Suture removal after 10 days.

RESULTS

In 46 patients with 55 total hip replacements with structured grafts in press-fit technique, the Harris Hip Score improved from 38.9 points to 92.3 points after 29.4 months (12.0-84.4 months). There were two cases of delayed wound healing and one cup exchange because of aseptic loosening. Radiologically, one graft sintering by 5 mm was detected.

Grading acetabular defects: the need for a universal and valid system

Preoperative classification of acetabular bone loss in revision total hip arthroplasty has been problematic. An evidence-based approach involves having a validated and widely accepted system of classification. A prerequisite would be a system that describes each defect in terms that are mutually exclusive, hierarchical, surgically relevant, and corresponding to experienced clinicians' preoperative estimates of surgical complexity. Of the 6 systems reviewed, only 1 demonstrated the reliability and validity required for a standardized grading system. Although high-grade defects were seen in only 17% of the 1094 hips, the failure rate associated with them was 30%. A larger population of high grade defects is necessary to determine which treatment alternatives are successful.

Is an impacted morselized graft in a cage an alternative for reconstructing segmental diaphyseal defects?

Large diaphyseal bone defects often are reconstructed with large structural allografts but these are prone to major complications. We therefore asked whether impacted morselized bone graft could be an alternative for a massive structural graft in reconstructing large diaphyseal bone defects. Defects in the femora of goats were reconstructed using a cage filled with firmly impacted morselized allograft or with a structural cortical autograft (n = 6 in both groups). All reconstructions were stabilized with an intramedullary nail. The goats were allowed full weightbearing. In all reconstructions, the grafts united radiographically. Mechanical torsion strength of the femur with the cage and structural cortical graft reconstructions were 66.6% and 60.3%, respectively, as compared with the contralateral femurs after 6 months. Histologically, the impacted morselized graft was replaced completely by new viable bone. In the structural graft group, a mixture of new and necrotic bone was present. Incorporation of the impacted graft into new viable bone suggests this type of reconstruction may be safer than reconstruction with a structural graft in which creeping substitution results in a mixture of viable and necrotic bone that can fracture. The data suggest that a cage filled with a loaded morselized graft could be an alternative for the massive cortical graft in reconstruction of large diaphyseal defects in an animal model.

High rate of failure of impaction grafting in large acetabular defects

We reviewed the results of 71 revisions of the acetabular component in total hip replacement, using impaction of bone allograft. The mean follow-up was 7.2 years (1.6 to 9.7). All patients were assessed according to the American Academy of Orthopedic Surgeons (AAOS) classification of bone loss, the amount of bone graft required, thickness of the graft layer, signs of graft incorporation and use of augmentation. A total of 20 acetabular components required re-revision for aseptic loosening, giving an overall survival of 72% (95% CI, 54.4 to 80.5). Of these failures, 14 (70%) had an AAOS type III or IV bone defect. In the failed group, poor radiological and histological graft incorporation was seen. These results suggest that impaction allografting in acetabular revision with severe bone defects may have poorer results than have previously been reported.