Bj. Vanvechten et al., A COMPARISON OF 4 DIFFERENT METHODS OF FIXATION OF OSTEOCHONDRAL FRAGMENTS, Veterinary and comparative orthopaedics and traumatology, 6(2), 1993, pp. 80-84
Fixation methods for osteochondral shell grafts were studied using rep
lacement of a femoral trochlear autograft in rabbits as the model. Twe
nty skeletally mature rabbits were divided into four groups with five
rabbits in each. The articular cartilage of the femoral trochlea, incl
uding 2.0 mm of subchondral bone, was removed using a sagittal bone sa
w. The grafts were immediately reattached using either small Kirschner
pins (K-pins), polydioxanone pins (PDP), polydioxanone suture (PDS),
or polymethylmethacrylate (PMMA) cement. Six months postoperatively th
e rabbits were killed and the graft sites compared to the contralatera
l control using radiography, gross examination, Safranin-0 and H & E s
taining, and sulphate-35 radioactive uptake. Mild degenerative joint c
hanges were evident radiographically in all of the operated joints. Ar
ticular surface defects at the graft sites were common and included sm
all craters and erosions; a few had larger areas devoid of cartilage.
Defects associated with the pin entrance sites were common in the K-pi
n and PDP groups. The PDS group had the least number of animals with a
rticular surface defects. Safranin-O staining was complete in the PDS
group, partial or complete in the K-pin and PDP groups, and partial in
all of the joints in the PMMA group. H & E preparations of the cartil
age sections were graded from 1 (normal cartilage) to 5 (multiple fiss
ures, severe degradation). The PDS group had a mean (SD) score of 1.8
(0.8), the PDP group 2.4 (1.1), the K-pin group 2.5 (1.3), and the PMM
A group 4.6 (0.6). The scores for the PMMA group were significantly gr
eater then the scores for the other groups (p < 0.05). The mean (SD) f
or radioactive counts per minute/mg tissue in treated graft sites as a
percent of control was PDS: 130 (83); PDP: 115 (14); K-pins: 92 (42);
PMMA: 91 (29). The relative percentages for radioactive uptake were n
ot significantly different (P > 0.05). Graft fixation using PDS, PDP,
or K-pins was technically easy to perform and the results were general
ly satisfactory. Fixation using PMMA was technically demanding and his
tological evidence of moderate to severe cartilage degradation was pre
sent in all treated joints.