[The effect of osteoprotegerin on tendon-bone healing after reconstruction of the anterior cruciate ligament: a histomorphological and radiographical study in the rabbit].
OBJECTIVE
Improvement of the bony incorporation of a soft-tissue graft after ACL reconstruction by local administration of Osteoprotegerin between the bone and tendon graft.


METHODS
Fifteen New Zealand White rabbits underwent unilateral anterior cruciate ligament (ACL) reconstruction using an autologous semitendinosis tendon graft. We compared the effect of three OPG doses (5 microg, 50 microg, or 100 microg) at the tendon-bone interface to the controls (OPG carrier) and ACL reconstruction only. Specimens were analyzed at 3 weeks using radiology, histology and histomorphometry to investigate the effect of OPG on the bony incorporation of the tendon graft.


RESULTS
Animals treated with OPG 100 microg had a significant (p = 0.007) increase in newly-formed bone around the graft compared to the control group (0.16 +/- 0.01 mm(2); 0.06 +/- 0.02 mm(2)). No significant differences were found between the controls and the other groups (tendon graft only, OPG 5 microg, and 50 microg) (p > 0.05). Bone mineral density, measured in image-pixel brightness (IPB; reference range: 0-255), along the edge of the bone tunnel was greater in the OPG 100 microg group (169.5 +/- 5.9 IPB) compared to the control group (150.3 +/- 4.3 IPB) but this was not statistically significant (p = 0.083). There was a significant decrease in the number of osteoclasts per high-power microscopic fields (HPF) lining the bone tunnel in the OPG 100 microg group compared to the control group (4.4 +/- 2.5 cells/HPF; 6.4 +/- 1.8 cells/HPF) (p = 0.022). No significant differences were found between the control group and the other groups in osteoclast numbers (p > 0.05).


CONCLUSIONS
Since tendon-bone healing requires new bone formation and bone ingrowth around a tendon graft, OPG may improve biologic graft fixation. A potential implication could be earlier return to function or better conditions in revision surgery.
Dynybil
C
C
Klinik für Orthopädie, Centrum für Muskuloskeletale Chirurgie, Charité-Universitätsmedizin Berlin. christian.dynybil@charite.de
Kawamura
S
S
Kim
H J
HJ
Ying
L
L
Perka
C
C
Rodeo
S A
SA
D000818:Animals; D016118:Anterior Cruciate Ligament / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology / Q000601:surgery*; D017024:Chemotherapy, Adjuvant; D004305:Dose-Response Relationship, Drug; D005269:Femur / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology / Q000601:surgery; D006023:Glycoproteins / Q000008:administration & dosage*; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology / Q000601:surgery*; D008297:Male; D053244:Osteoprotegerin; D011817:Rabbits; D011859:Radiography; D018160:Receptors, Cytoplasmic and Nuclear / Q000008:administration & dosage*; D018124:Receptors, Tumor Necrosis Factor / Q000008:administration & dosage*; D019651:Plastic Surgery Procedures / Q000379:methods; D013710:Tendons / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology / Q000601:surgery*; D013977:Tibia / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome; D014945:Wound Healing / Q000187:drug effects
D006023:Glycoproteins; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor