This document discusses graft selection for ACL reconstruction. It describes the advantages of autografts like low risk of reaction and strength loss after implantation. The most common autograft choices are bone-patellar tendon-bone and quadrupled hamstring grafts. Allografts and synthetics are also options but have higher risk of reaction and disease transmission. Proper sterilization of allografts is important to reduce these risks. While allografts have advantages like no donor site morbidity, autografts generally have better incorporation and tend to fail less often in the long run. Proper graft selection depends on factors like graft strength and fixation options.

1. ACL reconstruction
Graft Selection

2. Graft Selection
• Autograft tissue is used most commonly
• but allografts and synthetics also are available
• Autografts
• advantages
– low risk of adverse inflammatory reaction
– virtually no risk of disease transmission.
– As a biological graft, an autograft undergoes
revascularization and recollagenization
• but initially a 50% loss of graft strength occurs after implantation
• Therefore, it is desirable to begin with a graft stronger than the
tissue to bereplaced

3. • Virtually every structure around the knee has been used as
a substitute
• The most common current graft choices
– bone–patellar tendon–bone graft
– the quadrupled hamstring tendon graft.
• The bone–patellar tendon–bone graft
– an 8- to 11-mm-wide graft
– taken from the central third of the patellar tendon
– with its adjacent patella and tibial bone blocks
– High ultimate tensile load (approximately 2300 N)
– its stiffness (approximately 620 N/mm)
– the possibility for rigid fixation with its attached bony ends.

5. the hamstring tendon graft
• increased in recent years because of its relatively low donor site
morbidity.
• single strand of the semitendinosus or gracilis tendon is inadequate
– because the semitendinosus tendon has only 75% and the gracilis
tendon only 49% the strength of the anterior cruciate ligament
• A triple- or quadruple-stranded semitendinosus graft
• A quadruple-stranded semitendinosus-gracilis tendon graft with
both ends folded in half and combined
– an ultimate tensile load reported to be as high as 4108 N.
– provides a multiplebundle replacement graft that may better
approximate the function of the two-bundle ACL
• Disadvantages
– the concern over tendon healing within the osseous tunnels
– the lack of rigid bony fixation.

6. The quadriceps tendon graft
• attracted interest recently.
• harvested with a portion of patellar bone or
entirely as a soft tissue graft
• the ultimate tensile load of this graft to be as
high as 2352 N.
• an alternative replacement graft, especially for
revision ACL surgeries and for knees with
multiple ligament injuries.

9. Comparison of BPTB graft or a quadrupled
hamstring graft
• Slight increased laxity on arthrometer testing was reported in the
hamstring group
• pain with kneeling was greater for the patellar tendon group
• only one of nine studies showed increased anterior knee pain in
the patellar tendon group.
• Frequency of additional surgery seemed to be related to the
fixation method and not the graft type.
• No study reported a significant difference in graft failure between
patellar tendon and hamstring tendon autografts;
– graft failure rates for the combined populations of the nine studies
were 3.1% for patellar tendon grafts and 4.1% for hamstring grafts.
• Objective differences (range of motion, isokinetic strength,
arthrometer testing) were not detected between groups in most of
the studies,
– suggesting that their sensitivity to detect clinical outcomes may be
limited.

10. Comparison of BPTB graft or a quadrupled
hamstring graft
• Using ultrasonographic and power Doppler evaluation, Jarvela et al.
studied the morphologic changes in the patellar tendon of 31
patients 10 years after harvest of its central third and closure of the
defect.
– They found intratendinous calcification in nine patients, hypoechoic lesions in 20
patients, a hyperechoic lesion in one patient, and peritendinous changes in one
patient. Only three of the 31 patients had no changes in the harvested patellar tendon.
– In most patients, the harvested patellar tendon was significantly thicker than the
contralateral tendon.
• Harvest of the hamstring tendons has raised
concerns about potential weakness of knee flexion.
– Most studies have reported no significant difference in hamstring muscle torque
between the surgical extremity and the control extremity at 2 years after surgery,
possibly because of regeneration of these tendons, as shown in MRI studies by Rispoli
et al.
– However, Tashiro et al. reported significant weakness of hamstring muscle strength
with both isokinetic and isometric measurements when subjects’ knees were at
positions of 70 degrees or more of flexion.

11. SYNTHETIC MATERIALS FOR
LIGAMENT RECONSTRUCTION
• disappointing early clinical results.
• theoretical advantages
• no autogenous tissues are sacrificed
• the increased morbidity associated with the harvest of autogenous
tissues is avoided
• If autogenous tissues have been used in a failed reconstruction
• if they are unacceptable, the use of a readily available synthetic device is
appealing.
• a simpler and easier reconstructive technique (frequently arthroscopic)
• allow a more rapid rehabilitation because they do not become weak
during tissue revascularization and reorganization.
• Although there has been a rapid development of new materials and
surgical techniques for artificial ligament implantation, the long-term
effects of these devices are not yet known.

12. • Artificial ligaments function in one of three ways:
• (1) as a prosthetic ligament, that is, the prosthesis is implanted as a
permanent replacement for the normal ligament
• (2) as a stent temporarily protecting or augmenting an autogenous
graft
• (3) as a scaffold providing support for and stimulating the
ingrowth of collagen tissue.
• No long-term studies of the artificial ligaments currently used
support their routine use.
• At present, it is prudent to use them cautiously and to reserve
them for salvage procedures when autogenous grafting and
reconstructive procedures have failed

13. ALLOGRAFT LIGAMENT REPLACEMENT
• The ideal ligament replacement should be
readily available;
• It should be of sufficient length and diameter;
• it should have biomechanical properties
similar to the ligament it replaces;
• it should not disturb normal structures;
• it should retain or develop a vascular supply.

14. ALLOGRAFT LIGAMENT REPLACEMENT
• Although autogenous tissues currently are the
most commonly used grafts for reconstruction of
the cruciate ligament
• disadvantages of these techniques:
1. these transfers sacrifice a normal
musculotendinous structure in an already deficient
knee
2. adding to the functional disturbance
3. Extensive surgical exposure
4. long tourniquet times
5. prolonged rehabilitation

15. ALLOGRAFT LIGAMENT REPLACEMENT
• Autografts and allografts both go through four stages
after transplantation:
• necrosis, revascularization, cellular proliferation, and
remodeling.
• After incorporation, however, neither autograft nor
allograft tendons have been demonstrated to return to
their original strength 30% to 40% ultimate load
strengths.
• most surgeons prefer to use grafts or combinations
of grafts that begin with more than 100% of ACL
strength, which should result in sufficient strength
after incorporation

16. • Minami et al. studied collagen allografts after various treatment regimens
both in vivo and in vitro. They found no evidence of cytotoxicity, no
histological signs of rejection, and no activity with antisera from collagen
allografts pretreated by freezing and thawing.
• They also showed that the immunoreactivity of the allograft depended
solely on the cellular component of the graft;
• they concluded that the freezing and thawing treatment effectively
neutralized the immunological antigens by killing the tendon cells.
• Sterilization and preservation techniques have been shown to affect
immunological response.
– Freeze-drying reduces the response more than fresh freezing does,
– Although cryopreservation techniques that preserve cellularity still evoke an
immunological response.
– This seems to support the hypothesis that immune response is directed
toward the cellular components within allografts rather than to the antigens
of the collagen scaffold.

17. • elevated antibody titers predominantly in the
joint
• This finding raises concern for the potential
for graft-versus-host reactions, which may
account for the relative delay in the
incorporation of allografts compared with
autografts.

18. • The cited advantages of allografts over
autografts
• No donor site morbidity
• shorter operative times
• smaller incisions
• greater availability—have been somewhat

19. • the risk of disease transmission
• reports of serious infection associated with allografts heightening these
concerns.
• transmission of hepatitis or AIDS.
• Lochemes et al. demonstrated active viral replication in cells infected
with HIV 1 after exposure to 2.5 Mrad of gamma irradiation, the maximal
dosage that can be used without destroying the clinical usefulness of the
allograft.
• Even though the donor may not demonstrate detectable antibodies to
these viruses, a certain “window of vulnerability” exists between the time
the patient may have contracted the virus and the production of
measurable antibodies, which may be as long as several months.
• Emerging pathogens
– West Nile virus, severe acute respiratory syndrome (SARS), coronavirus and
prion disease, also have become a concern in the use of allografts.
• The risks of disease transmission are small, however, when the allograft is
obtained with sterile technique and disinfection and secondary
sterilization procedures are carried out

20. • STERILIZATION OF THE GRAFT
• ethylene oxide has been questioned
– because of the residual of ethylene glycol remaining in the sterilized tissues,
which has been cited as a cause of some sterile effusions in late failures.
• Freeze-drying of the allograft does not appear to significantly alter the
mechanical properties compared with deep-freezing, but clinical reports
reveal frequent late failures of freeze-dried allograft tissues.
• Gamma irradiation of the allografts with up to 2 Mrad has been shown
not to significantly affect the initial mechanical properties of the allograft
tissue, but effects are significant after use of 3 Mrad.
• Electron-beam radiation has been used for sterilization of soft tissue
grafts because of its lower penetrability compared with gamma
irradiation and higher processing speed—seconds, compared with hours
for gamma irradiation.
• Currently, the most commonly used method of sterilization probably is a
combination of lower doses of irradiation (1 to 3.5 Mrad) and other
processing techniques, such as antibiotic soaks

21. autograft Vs. allograft ?
• remains a matter of controversy.
• A systematic review of the literature that included 31 studies found that the
percentage of patients receiving a final IKDC score of “A” (normal knee) was
statistically higher for allografts (44%) than for autografts (28%);
• however, the graft failure rate was 8.2 per 100 reconstructions for allograft
compared with 4.7 for autografts,
• a slightly higher complication rate for allografts.
• The authors concluded that, from currently available data, the graft source has a
minimal effect on the outcomes of ACL reconstruction.
• Although a number of reports have documented good results with allograft
reconstructions, worse outcomes have been reported with the use of anterior
tibial tendon allografts in young, active patients.
• Singhal et al. reported an overall reoperation rate of 38% after primary anterior
cruciate ligament reconstruction with anterior tibial tendon allografts in 125
young patients (≤25 years of age); the failure rate in patients younger than 25
years was 55% compared with 24% in those older than 25 years.