Til consensusrapporter Til Forskning Til Index
Participants: Henrik Aagaard MD PhD, Svend Erik Christiansen MD, Lars Engebretsen MD professor, Peter Faunø MD, Mogens Strange Hansen MD, Michael Kjær MD professor, Michael Krogsgaard MD, Robert LaPrade MD, Martin Søe Steinke, Jens Ole Storm MD, Fred Wentorf MS, Søren Winge MD, Bent Wulff Jakobsen MD.
Allografts in knee surgery.Legislation:
Conserning harvesting grafts after the diagnose of braindeath, you need a written consent from the dead or the family before you can remove tissue. A protocol, approved by authorities must be made.
To make more ligament tissue available, donors registered in the central donor register should know that ligament tissue can also be donated.
When donor is over 50 years old, the mechanical properties of the tissue seems to decrease, so ligament donors should be below 50 years. Menisci may degenerate at an earlier age.
Exclusion: Infectious disease, high risk, degenerative diseases, cancer, neurologic diseases, haemophiliacs.
Preservation: At present fresh frozen preservation is the best choice, as the mechanical properties seems to be unchanged after freezing. Freeze-drying may be an option in the future.
How many allograft banks are necessary:
Expenses for taking grafts out, for testing patients and keep the records should be covered by the users, i. e. should be reimbursed when a graft is used.
Initially one bank should be opened to gain experience and reduce costs.
Recommendations for the use of the allografts should be written up, and should be followed by the users. Basically any orthopaedic surgeon should have access to bank.
Procedures: See exclusion.
Lab tests: According to the recommendations from the National Board of Health.
The bank should include ligaments and menisci.
Risk of disease transmission in allograft transplantation?.
HIV: less than 1/1,5 mio i USA
Lab tests: as before.
Immune reactions: Very rare, but it is not fully investigated. It is recommended that failed grafts are sent for histological examination to exclude immune reactions are responsible for graft failure. There may be a correlation between tunnel enlargement/graft failure and immune reactions, but it is not fully understood. The slightly higher failure rate after allografts may be due to rejection.
Are properties of allograft
inferior to autografts?
It is unknown if freezing reduces the mechanical properties of the graft in the long term, but there doesn’t seem to be any short term effect. Other available preservation methods reduce the mechanical properties of the grafts. It is unknown how long you can store the fresh frozen grafts before the mechanical properties of the graft decrease, but one report could indicate a higher failure rate after 260 days of storage.
The possibility of larger and stronger grafts is the greatest advantage of allografts. The recovery time after harvest of the largest possible autograft – the quadriceps autografts - is long (several years). Large grafts are important in revision with tunnel enlargements and in great los of tissue. There seems to be less stiffness of the knee after use of allografts compared to autografts, but the donor site morbidity is not solely connected to graft harvesting but also to the reconstructive procedure itself. Other advantages are shorter operation time, unlimited amount of tissue and smaller scars.
A potential risk of transmitting serious diseases exist, although it does not seen to been a problem in the cases done so far.
Immunologic reactions towards the graft does not seem to be a major problem, probably due to the low vascularity and cellularity of tendons and ligaments compared to e.g. kidney tissue. However, there has been reports about total eradication of the graft about one year after the reconstructive surgery.
Autografts have a shorter remodelling time than allografts, and the biomechanical profile after remodelling is less favourable for allografts than autografts.
A study by Fahey and Indelicato showed than tunnel widening is larger for allografts compared to autografts, but no objective or subjective clinical differences were detected.
It has been postulated that allografts should not be used intra articulary, but there is no clinical observation to back this up.
Indications for the use of allografts:
Allografts should be made generally available in Denmark. Because of the limited number of allografts available, they should primary be available for acute and chronic multiple ligament injuries and revision cases with lack of autografts. As the mechanical properties of allografts is inferior to autografts, allografts should not be used for single ligament reconstructions (ACL).