Abstract
Introduction
Osteochondral defects (OCDs) of the talus are treated initially by arthroscopic bone marrow stimulation. For both large and secondary defects, current alternative treatment methods have disadvantages such as donor site morbidity or two-stage surgery. Demineralized bone matrix (DBM) was published for the treatment of OCDs of rabbit knees. Autologous platelet-rich plasma (PRP) may improve the treatment effect of DBM. We previously developed a goat model to investigate new treatment methods for OCDs of the talus. The aim of the current study was to test whether DBM leads to more bone regeneration than control OCDs, and whether PRP improves the effectiveness of DBM.
Methods
A standardized 6-mm OCD was created in 32 ankles of 16 adult Dutch milk goats. According to a randomized schedule, 8 goats were treated with commercially available DBM (Bonus DBM, Biomet BV, Dordrecht, the Netherlands) hydrated with normal saline, and 8 were treated with the same DBM but hydrated with autologous PRP (DBM+PRP). The contralateral ankles (left or right) were left untreated and served as a control. The goats were sacrificed after 24 weeks and the tali were excised. The articular talar surfaces were assessed macroscopically using the international cartilage repair society (ICRS) cartilage repair assessment, with a maximum score of 12. Histologic analysis was performed using 5-μm sections, and histomorphometric parameters (bone% and osteoid%) were quantified on representative areas of the surface, center, and peripheral areas of the OCDs. Furthermore, μCT-scans of the excised tali were obtained, quantifying the bone volume fraction, trabecular number, trabecular thickness, and trabecular spacing in both the complete OCDs and the central 3-mm cylinders.
Results
All goats recovered well and were able to bear full weight within 24 hours after surgery. The mean ICRS-score of the ankles treated with DBM was 8.0 ± 1.0, compared to a score of 8.4 ± 1.5 in the contralateral ankle (NS); those treated with DBM+PRP scored 6.9 ± 2.4, compared to 7.4 ± 2.0 in the contralateral ankle (NS). Histologic analysis showed four different patterns of healing, distributed evenly over the treatment and control groups: type 1 (n = 4), almost completely healed; type 2 (n = 11), restoration of the subchondral bone with a cystic lesion underneath; type 3 (n = 14), superficial defect with regeneration from the margins and bottom; type 4 (n = 3), no healing tendency. Histomorphometry and μCT revealed no statistically significant difference between treatment (DBM or DBM+PRP) and contralateral control or between both treatment groups in any of the parameters investigated.
Conclusion
No treatment effect of DBM was found compared to control defects, and the addition of PRP was not beneficial.
