Auswirkungen der EU-Geweberichtlinie 2004/23/EG auf deutsche Knochenbanken

[A clinical radiological score for femoral head grafts : Establishment of the Tabea FK score to ensure the quality of human femoral head grafts]

INTRODUCTION

Transplantation of cancellous tissue from human femoral heads (FK) is an established method in the reconstruction of bony defects in orthopedic and trauma surgery. Standardized rating systems with respect to the morphological quality of this tissue are not available.

MATERIALS AND METHODS

In 91/105 patients who had been a regular, clinically-indicated surgery (arthroplasty of the hip joint) the respective femoral head (FK) was taken under standardized conditions. Using a checklist defined clinical and radiological criteria of FK are judged in terms of their quality (cysts, necrosis, calcification, deformities, osteoporosis) and divided by the Tabea FK score into three classes (best/middle/poor quality). This was followed by a blinded repeated scoring, now as macroscopic assessment of three sawed layers from the same femoral head. The femoral heads are examined by peripheral quantitative computed tomography (pQCT) and a standardized histological examination of the bony tissue. We evaluated the accordance of the Tabea FK score with complementary assessments by calculation of sensitivity and specificity.

RESULTS

Femoral heads from 91/105 patients (ages: 68.4 ± 9.9 , n = 60 women, n = 31 men) were explanted and included in the study. The correlation between the primary radiologic clinical score (Tabea FK score) and the macroscopic second review of the sawn FK with respect to middle/best and poor/middle quality was classified as good (sensitivity 77% and 81%, respectively; specificity 76% and 84%, respectively). The correlation of histology and macroscopic second review was worse and in relation to discrimination of middle/best and poor/middle quality had a sensitivity of 85% and 54%, respectively, and a specificity of 66% and 97%, respectively. The pQCT showed a sensitivity of 82% only in discrimination of middle/best, while sensitivity in discrimination of poor/middle and poor/middle + best, respectively, was <10%.

DISCUSSION

The corresponding correlation between the primary and the second clinical score was evaluated as good. This emphasizes the long-standing skills of operationally active orthopedic surgeons to classify the quality of cancellous bone correctly already on the basis of X‑ray images and intraoperative findings. In this respect, the introduction of the Tabea FK score as a quality assurance tool in the routines of bone banks can be recommended.

CT Lesion Model-Based Structural Allografts: Custom Fabrication and Clinical Experience

BACKGROUND

Patients requiring knee and hip revision arthroplasty often present with difficult anatomical situations that limit options for surgery. Customised mega-implants may be one of few remaining treatment options. However, extensive damage to residual bone stock may also be present, and in such cases even customised prosthetics may be difficult to implant. Small quantities of lost bone can be replaced with standard allografts or autologous bone. Larger defects may require structural macro-allografts, sometimes in combination with implants (allograft-prosthesis composites).

METHODS

Herein, we describe a process for manufacturing lesion-specific large structural allografts according to a 3D, full-scale, lithographically generated defect model. These macro-allografts deliver the volume and the mechanical stability necessary for certain complex revisions. They are patient-and implant-matched, negate some requirements for additional implants and biomaterials and save time in the operating theatre by eliminating the requirement for intra-operative sizing and shaping of standard allografts.

CONCLUSION

While a robust data set from long-term follow-up of patients receiving customised macro-allografts is not yet available, initial clinical experience and results suggest that lesion-matched macro-allografts can be an important component of revision joint surgery.

[Bone allografting]

Bone allografts facilitate bone reconstruction in orthopedic surgery. Appropriate donor selection and processing of grafts minimize the risk of disease transfer. After implantation, bone allografts become necrotic but are incorporated and remodeled in the recipient bone with good regenerative capacity. We use bone allografts in about 3% of all elective orthopedic operations in our hospital. We use bone allografts regularly in acetabuloplasty in cases of severe residual hip dysplasia. These transplants simplify and shorten the operation and improve the results in our hands. Bone allografts are most often used in revision total joint arthroplasty. In cases of reconstruction of defects in benign bone tumors and tumor-like lesions, bone allografts are often suitable. In fibrous dysplasia, corticocancellous bone allografts are even the treatment of choice.

Effektivitätsanalyse einer klinikinternen allogenen Knochenbank

BACKGROUND

The EU guidelines 2004/23/EG and 2006/17/EG and their national implementation redefine the framework for allogenic bone banking and transplantation. Against this background an established internal hospital bone bank was analysed concerning threshold of allogenic bone and cost effectiveness in comparison to alternative methods.

METHOD

Over a 30-month period we registered all arrivals and outgoings of our bone bank and their destination. We further noted all declined donations. We analysed all costs incurred and calculated costs for alternative methods.

RESULTS

By means of our bone bank we are currently able to meet our own demand for bone substitutes. The maintenance costs are below the prices of alternative methods. Some donations (8%) have to be discarded due to procedural errors.

CONCLUSION

Maintaining an internal hospital bone bank utilizing fresh-frozen allogenic bone is an efficient and cost-effective method of supplying bone substitutes even under the new EU guidelines if the existing process covers most conditions of the producer authorisation according to section sign 13 AMG. By harmonizing the organizational process it is possible to further improve its effectiveness.

Strukturelle Femurkopfallografts in der Revisionschirugie von gelockerten Hüftendoprothesenpfannen

BACKGROUND

Treatment of acetabular bone defects presents a great challenge in revision total hip arthroplasty (THA). Many methods of acetabular reconstruction have been described. The purpose of this study was to evaluate the midterm results of structural femoral head allografts for acetabular reconstruction.

METHODS

Thirty-six patients (33 females and 3 males) with acetabular defects ranging from type 2C to type 3B according to Paprosky's classification were included in the study. In all cases acetabular defects were closed using allografts from femoral heads. In 13 cases an uncemented press-fit cup, in 17 cases a cemented polyethylene socket, and in 6 cases a Burch-Schneider antiprotrusion cage was implanted. The mean follow-up period was 84.2 months (range: 5-147).

RESULTS

Four acetabular components failed. All 36 grafts were osseointegrated radiographically and formed a mechanically stable construction. The mean Harris Hip Score at the most recent follow-up was 79.8 points. The distance from the obturator line to the prosthesis head center was 3.73 cm (1.17-5.80 cm) preoperatively and 2.79 cm (0.85-4.8 cm) postoperatively (p<0.05). The distance from the teardrop figure to the prosthesis head center was 3.02 cm (1.0-5.8 cm) preoperatively and 3.25 cm (1.6-4.8 cm) postoperatively (p<0.001).

CONCLUSIONS

Closure of acetabular defects of types 2C to 3B according to Paprosky's classification can be satisfactorily accomplished using femoral head allografts. These allografts may facilitate future revision surgery. Femoral heads are readily available due to widespread primary total hip replacement surgery. However, the use of structural femoral head allografts for acetabular reconstruction is cost intensive. Individual patient-related aspects, such as the function of revision arthroplasty, have to be considered when planning revision arthroplasty using femoral head allografts.

Die Überbrückung von posttraumatischen Knochendefekten

Bony defects as a result of injury or disease can be caused by a variety of conditions such as acute injury, fall fractures in osteoporotic patients or tumours and congenital malformations of the musculoskeletal system which necessitate the resection of affected parts of the bone. This results in a multitude of defects concerning localisation and specificity as well as a number of conditions involving both hard and soft tissue structures and various situations of different patients. A reasonable classification of defects which is relevant for practical purposes includes four basic types: defects of the spine, metaphyseal defects as well as partial and complete diaphyseal defects of long bones. A variety of options exists for the treatment of these conditions. The aim of all efforts is to reinstall the integrity of affected structures long-lastingly and dependably and at the same time guarantee the normal function of joints involved. In addition to classical treatment strategies which involve the use of autogenous and allogenous corticocancellous bone grafts a great number of bone substitute materials can also be used. Further options lie in complex reconstructive methods such as the transport of whole segments or the transplantation of vascularised bone grafts. The field of new regenerative strategies including tissue engineering as well as stem cell and gene therapy holds great promise for the future. The aim of this review is to derive a ranking from the evaluation of biological and mechanical characteristics for the treatment of posttraumatic defects.