title: Increased Osseous (99m)Tc-DPD Uptake in End-Stage Ankle Osteoarthritis: Correlation Between SPECT-CT Imaging and Histologic Findings.
abstract: BACKGROUND
  We analyzed the histopathologic findings in end-stage osteoarthritic ankle joint tissue that display increased uptake of bone-seeking radiotracer in single-photon emission computed tomography-computed tomography (SPECT-CT) imaging.
  
  
  METHODS
  Six consecutive patients with end-stage osteoarthritis undergoing total ankle replacement received preoperative SPECT-CT imaging using (99m)Technetium dicarboxypropane diphosphonate ((99m)Tc-DPD). Using imaging data for stratification, osteochondral tissue sections were prepared from SPECT-positive (+) and -negative (-) areas of tibial and talar resection specimens. Histomorphometric analyses of osteoblast numbers, collagen deposition, and cartilage degeneration were performed on hematoxylin and eosin, van Gieson's and Safranin-O stained tissue sections. Osteoclast activity was visualized using tartrate-resistant acid phosphatase (TRAP) staining.
  
  
  RESULTS
  Increased (99m)Tc-DPD uptake was observed exclusively subjacent to the subchondral bone plate of tibial and talar joint compartments. SPECT(-) tissues displayed typical fatty marrow morphology containing mainly collagen-positive blood vessels and few marrow and bone-lining cells. SPECT(+) tissues were characterized by increased numbers of active bone-lining osteoblasts depositing collagen fibers. Collagen area fraction of subchondral bone marrow was significantly increased in SPECT(+) (0.52 ± 0.21) compared with SPECT(-) (0.29 ± 0.13) tissues (P = .30). Multinucleated TRAP(+) osteoclasts were absent from bone formation sites, but associated with vascular structures invading articular cartilage through the subchondral bone plate. Increased (99m)Tc-DPD uptake was specifically and strongly correlated with increased osteoblast numbers (P = .011), and with collagen area fraction (P = .030) but not with Mankin score (P = .202), or with osteoclast number (P = .576).
  
  
  CONCLUSIONS
  Subchondral bone tissues in SPECT(+) areas of end-stage ankle osteoarthritis were histologically characterized by increased osteoblast-mediated bone formation in the absence of functional osteoclasts, and increased cellularity and collagen deposition in marrow tissues.
  
  
  CONCLUSIONS
  Our findings suggest a pathologic bone-remodeling process in end-stage ankle OA areas with increased (99m)Tc-DPD uptake.
authors.affiliation: Praxisklinik Rennbahn AG, Basel, Switzerland.
authors.forename: Jochen
authors.initials: J
authors.lastname: Paul
authors.affiliation: University of Utah, Salt Lake City, UT, USA alexej.barg@hsc.utah.edu.
authors.forename: Alexej
authors.initials: A
authors.lastname: Barg
authors.affiliation: University Hospital of Basel, Basel, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Kretzschmar
authors.affiliation: University Hospital of Basel, Basel, Switzerland.
authors.forename: Geert
authors.initials: G
authors.lastname: Pagenstert
authors.affiliation: University Hospital of Basel, Basel, Switzerland.
authors.forename: Ueli
authors.initials: U
authors.lastname: Studler
authors.affiliation: University Hospital of Basel, Basel, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hügle
authors.affiliation: University of Utah, Salt Lake City, UT, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Wegner
authors.affiliation: Schmerzklinik Basel, Basel, Switzerland.
authors.forename: Victor
authors.initials: V
authors.lastname: Valderrabano
authors.affiliation: University Hospital of Basel, Basel, Switzerland.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Geurts
mesh_terms: D000368:Aged; D000843:Ankle Joint / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D058737:Arthroplasty, Replacement, Ankle; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000473:pathology; D016723:Bone Remodeling; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D002452:Cell Count; D003094:Collagen; D004164:Diphosphonates; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D015609:Organotechnetium Compounds; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D010006:Osteoblasts / Q000000981:diagnostic imaging / Q000473:pathology; D019275:Radiopharmaceuticals; D013628:Talus / Q000000981:diagnostic imaging / Q000473:pathology; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
chemical_list: D004164:Diphosphonates; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C033905:technetium Tc 99m 1,1-diphosphonopropane-2,3-dicarboxylic acid; D003094:Collagen
keywords: SPECT-CT; bone scintigraphy; osteoarthritis; osteoblasts; osteoclasts; subchondral bone