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Development of a Large Animal Model of Osteochondritis Dissecans of the Knee: A Pilot Study.

Pfeifer CG, Kinsella SD, Milby AH, Fisher MB, Belkin NS, Mauck RL, Carey JL - Orthop J Sports Med (2015)

Bottom Line: This study successfully developed a large animal model of OCD-like lesions in the knee joint of Yucatan minipigs.These findings set the stage for ongoing model refinement as well as exploration of novel interventional therapies to restore function and bone and cartilage patency in individuals affected by this rare but significant disease.This developed model will serve as a platform on which to further investigate the natural course as well as emerging treatment options for OCD.

View Article: PubMed Central - PubMed

Affiliation: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA. ; Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania, USA.

ABSTRACT

Background: Treatment of osteochondritis dissecans (OCD) of the knee is challenging, and evidence for stage-dependent treatment options is lacking. Basic science approaches utilizing animal models have provided insight into the etiology of OCD but have yet to produce a reliable and reproducible large animal model of the disease on which to test new surgical strategies.

Purpose/hypotheses: The purpose of this study was to develop an animal model featuring an OCD-like lesion in terms of size, location, and International Cartilage Repair Society (ICRS) grading. The hypothesis was that surgical creation of an osteochondral defect followed by placement of a barrier between parent bone and progeny fragment would generate a reproducible OCD-like lesion.

Study design: Controlled laboratory study.

Methods: Bilateral osteochondral lesions were created in the medial femoral condyles of 9 Yucatan minipigs. After lesion creation, a biodegradable membrane was interposed between the progeny and parent bone. Five different treatment groups were evaluated at 2 weeks: a control with no membrane (ctrl group; n = 4), a slowly degrading nanofibrous poly(∊-caprolactone) membrane (PCL group; n = 4), a fenestrated PCL membrane with 1.5-mm holes covering 25% of surface area (fenPCL group; n = 4), a collagen membrane (Bio-Gide) (CM group; n = 3), and a fenestrated CM (fenCM group; n = 3). Five unperturbed lateral condyles (1 from each treatment group) served as sham controls. After euthanasia on day 14, the lesion was evaluated by gross inspection, fluoroscopy, micro-computed tomography (micro-CT), and histology. To quantify changes between groups, a scoring system based on gross appearance (0-2), fluoroscopy (0-2), and micro-CT (0-6) was established. Micro-CT was used to quantify bone volume per total volume (BV/TV) in a defined region surrounding and inclusive of the defect.

Results: The no scaffold group showed healing of the subchondral bone at 2 weeks, with continuity of subchondral bone elements. Conversely, condyles treated with PCL or CM showed substantial remodeling, with loss of bone in both the progeny fragment and surrounding parent bone. When these membranes were fenestrated (fenPCL and fenCM groups), bone loss was less severe. Histological analysis showed no integration in the cartilage layer in any treatment group, while fibrous tissue formed between the parent and progeny fragments. Micro-CT showed significant differences in mean BV/TV between the PCL (27.4% ± 2.3%) and the sham (47.7% ± 1.4%) or no scaffold (54.9% ± 15.1%) groups (P < .01 and P < .05, respectively). In addition, a significant difference in bone loss was evident between the PCL and fenPCL groups (mean BV/TV, 46.6% ± 15.2%; P < .05), as well as between the PCL and fenCM (mean BV/TV, 50.9% ± 3.5%) and fenPCL groups (P < .01). Grading by 6 blinded reviewers using an OCD scoring system with 3 subcategories showed a significant difference between control and PCL groups.

Conclusion: This study successfully developed a large animal model of OCD-like lesions in the knee joint of Yucatan minipigs. The lesions generated matched characteristics of an ICRS grade 3 OCD lesion in humans. These findings set the stage for ongoing model refinement as well as exploration of novel interventional therapies to restore function and bone and cartilage patency in individuals affected by this rare but significant disease.

Clinical relevance: This developed model will serve as a platform on which to further investigate the natural course as well as emerging treatment options for OCD.

No MeSH data available.


Related in: MedlinePlus

Immunohistochemical analysis. Immunhistochemistry for (A-D) collagen type 2 and (E-H) collagen type 1 at 14 days postoperatively. (A and E) full nanofibrous poly(∊-caprolactone) (PCL) membrane, (B and F) fenestrated PCL, (C and G) full collagen membrane, (D and H) fenestrated collagen membrane. *Progeny bone/cartilage; **parent bone. Scale bar = 100 μm.
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fig6-2325967115570019: Immunohistochemical analysis. Immunhistochemistry for (A-D) collagen type 2 and (E-H) collagen type 1 at 14 days postoperatively. (A and E) full nanofibrous poly(∊-caprolactone) (PCL) membrane, (B and F) fenestrated PCL, (C and G) full collagen membrane, (D and H) fenestrated collagen membrane. *Progeny bone/cartilage; **parent bone. Scale bar = 100 μm.

Mentions: Histological analysis revealed no evidence of parent-progeny cartilage integration in any group (Figure 5). Progeny cartilage stained as intensely for collagen and proteoglycans as did parent cartilage. Inspection of the bony interface showed findings consistent with those seen on micro-CT. Namely, PCL and CM groups showed no signs of bony bridging, and remnants of the scaffold were present. Similar staining of the interface for fibrous tissue was observed in Saf-O and PR sections. That being said, the remaining implanted scaffold layer was much thinner in fenPCL and fenCM groups, and fenestrations were observable in some samples. Parent-progeny bone bridging was evident in the no scaffold groups across nearly the entire interface. Immunostaining showed the interface to stain intensely for collagen I (Col 1) and collagen II (Col 2), supporting the existence of a fibrous interlayer between the progeny and parent bone (Figure 6).


Development of a Large Animal Model of Osteochondritis Dissecans of the Knee: A Pilot Study.

Pfeifer CG, Kinsella SD, Milby AH, Fisher MB, Belkin NS, Mauck RL, Carey JL - Orthop J Sports Med (2015)

Immunohistochemical analysis. Immunhistochemistry for (A-D) collagen type 2 and (E-H) collagen type 1 at 14 days postoperatively. (A and E) full nanofibrous poly(∊-caprolactone) (PCL) membrane, (B and F) fenestrated PCL, (C and G) full collagen membrane, (D and H) fenestrated collagen membrane. *Progeny bone/cartilage; **parent bone. Scale bar = 100 μm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2 - License 3
Show All Figures
getmorefigures.php?uid=PMC4555612&req=5

fig6-2325967115570019: Immunohistochemical analysis. Immunhistochemistry for (A-D) collagen type 2 and (E-H) collagen type 1 at 14 days postoperatively. (A and E) full nanofibrous poly(∊-caprolactone) (PCL) membrane, (B and F) fenestrated PCL, (C and G) full collagen membrane, (D and H) fenestrated collagen membrane. *Progeny bone/cartilage; **parent bone. Scale bar = 100 μm.
Mentions: Histological analysis revealed no evidence of parent-progeny cartilage integration in any group (Figure 5). Progeny cartilage stained as intensely for collagen and proteoglycans as did parent cartilage. Inspection of the bony interface showed findings consistent with those seen on micro-CT. Namely, PCL and CM groups showed no signs of bony bridging, and remnants of the scaffold were present. Similar staining of the interface for fibrous tissue was observed in Saf-O and PR sections. That being said, the remaining implanted scaffold layer was much thinner in fenPCL and fenCM groups, and fenestrations were observable in some samples. Parent-progeny bone bridging was evident in the no scaffold groups across nearly the entire interface. Immunostaining showed the interface to stain intensely for collagen I (Col 1) and collagen II (Col 2), supporting the existence of a fibrous interlayer between the progeny and parent bone (Figure 6).

Bottom Line: This study successfully developed a large animal model of OCD-like lesions in the knee joint of Yucatan minipigs.These findings set the stage for ongoing model refinement as well as exploration of novel interventional therapies to restore function and bone and cartilage patency in individuals affected by this rare but significant disease.This developed model will serve as a platform on which to further investigate the natural course as well as emerging treatment options for OCD.

View Article: PubMed Central - PubMed

Affiliation: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA. ; Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania, USA.

ABSTRACT

Background: Treatment of osteochondritis dissecans (OCD) of the knee is challenging, and evidence for stage-dependent treatment options is lacking. Basic science approaches utilizing animal models have provided insight into the etiology of OCD but have yet to produce a reliable and reproducible large animal model of the disease on which to test new surgical strategies.

Purpose/hypotheses: The purpose of this study was to develop an animal model featuring an OCD-like lesion in terms of size, location, and International Cartilage Repair Society (ICRS) grading. The hypothesis was that surgical creation of an osteochondral defect followed by placement of a barrier between parent bone and progeny fragment would generate a reproducible OCD-like lesion.

Study design: Controlled laboratory study.

Methods: Bilateral osteochondral lesions were created in the medial femoral condyles of 9 Yucatan minipigs. After lesion creation, a biodegradable membrane was interposed between the progeny and parent bone. Five different treatment groups were evaluated at 2 weeks: a control with no membrane (ctrl group; n = 4), a slowly degrading nanofibrous poly(∊-caprolactone) membrane (PCL group; n = 4), a fenestrated PCL membrane with 1.5-mm holes covering 25% of surface area (fenPCL group; n = 4), a collagen membrane (Bio-Gide) (CM group; n = 3), and a fenestrated CM (fenCM group; n = 3). Five unperturbed lateral condyles (1 from each treatment group) served as sham controls. After euthanasia on day 14, the lesion was evaluated by gross inspection, fluoroscopy, micro-computed tomography (micro-CT), and histology. To quantify changes between groups, a scoring system based on gross appearance (0-2), fluoroscopy (0-2), and micro-CT (0-6) was established. Micro-CT was used to quantify bone volume per total volume (BV/TV) in a defined region surrounding and inclusive of the defect.

Results: The no scaffold group showed healing of the subchondral bone at 2 weeks, with continuity of subchondral bone elements. Conversely, condyles treated with PCL or CM showed substantial remodeling, with loss of bone in both the progeny fragment and surrounding parent bone. When these membranes were fenestrated (fenPCL and fenCM groups), bone loss was less severe. Histological analysis showed no integration in the cartilage layer in any treatment group, while fibrous tissue formed between the parent and progeny fragments. Micro-CT showed significant differences in mean BV/TV between the PCL (27.4% ± 2.3%) and the sham (47.7% ± 1.4%) or no scaffold (54.9% ± 15.1%) groups (P < .01 and P < .05, respectively). In addition, a significant difference in bone loss was evident between the PCL and fenPCL groups (mean BV/TV, 46.6% ± 15.2%; P < .05), as well as between the PCL and fenCM (mean BV/TV, 50.9% ± 3.5%) and fenPCL groups (P < .01). Grading by 6 blinded reviewers using an OCD scoring system with 3 subcategories showed a significant difference between control and PCL groups.

Conclusion: This study successfully developed a large animal model of OCD-like lesions in the knee joint of Yucatan minipigs. The lesions generated matched characteristics of an ICRS grade 3 OCD lesion in humans. These findings set the stage for ongoing model refinement as well as exploration of novel interventional therapies to restore function and bone and cartilage patency in individuals affected by this rare but significant disease.

Clinical relevance: This developed model will serve as a platform on which to further investigate the natural course as well as emerging treatment options for OCD.

No MeSH data available.


Related in: MedlinePlus