OTA 2005 Posters

Scientific Poster #69 Basic Science

Chondrocyte Viability after Intra-articular Calcaneus Fractures in Humans

Scott T. Ball, MD; Alexandra K. Schwartz, MD; Robert Sah, MD, ScD;

Kyle Jadin, PhD; R. Todd Allen, MD, PhD; Michael Brage, MD

(n-all authors);

University of California, San Diego, California, USA

Purpose: Intra-articular fractures of the calcaneus can be devastating injuries with a high incidence of subsequent posttraumatic arthritis. To our knowledge, no previous study has explored the extent of direct chondral injury associated with these fractures. We sought to study the effect of intra-articular calcaneus fractures on chondrocyte viability and to correlate these effects with injury severity, time from injury to surgery, patient age, and comorbidities.

Methods: With IRB approval, irreducible chondral and osteochondral fragments from patients undergoing operative treatment for intra-articular calcaneus fractures were analyzed. The cartilage was assessed for chondrocyte viability using the Live/Dead assay followed by confocal laser microscopy. Patient demographics were recorded and included injury classification, injury severity, time from injury to surgery, patient age, and comorbidities. Data were analyzed statistically for correlations by linear regressions.

Results: Cartilage from the posterior facet of 12 calcaneus fractures was harvested and analyzed. Chondrocyte viability was variable with an average ± SD of 72.8% ± 12.9% (range, 53% to 95%). The superficial zone of the cartilage revealed the lowest viability, whereas viability in the deep zone was frequently preserved. Chondrocyte cloning was observed in a number of samples as was relative hypocellularity. Chondrocyte viability declined with higher energy injuries (P=0.13), time from injury to surgery (P=0.07), and increasing patient age (P =0.07), and was lower in smokers (P =0.07).

Conclusion/Significance: Calcaneus fractures result in decreased chondrocyte viability in the posterior facet cartilage, but the extent of chondrocyte necrosis varies from patient to patient. Direct chondral injury likely plays a role in the development of posttraumatic arthritis, and our data may help to explain the clinical observation that older patients are generally more susceptible to posttraumatic arthritis.