From January 1987 to September 1990, 132 displaced intraarticular calcaneal fractures were treated operatively using a lateral approach, lag screws, and side plate without bone graft. To evaluate the results, a classification for intraarticular calcaneal fractures was developed, based on standardized coronal and transverse computed tomography (CT) scans of both feet. Type 1 fractures were nondisplaced (and received nonoperative treatment); Type II were two-part or split fractures; Type III were three-part or split depression fractures; and Type IV were four-part or highly comminuted articular fractures. Results were evaluated using the Maryland Foot Score and repeat CT scans. One hundred twenty cases were available for a minimum of one year follow-up evaluation (range, 12-56 months; mean, 29.3 months). Roentgenographic evaluation of calcaneal body dimensions showed restoration of heel height (98%), width (110%), and length (100%) to virtually normal in all cases, regardless of preoperative displacement. Roentgenographically, articular reduction was anatomic in 68 of 79 (86%) Type II fractures, 18 of 30 (60%) Type III fractures, and 0 of 11 (0%) Type IV fractures. Excellent or good clinical results occurred in 58 of 79 (73%) Type II fractures, 21 of 30 (70%) Type III fractures, and one of 11 (9%) Type IV fractures. When excellent and good clinical results were compared by year, a distinct learning curve appeared (1987, 27%; 1988, 54%; 1989, 74%; 1990, 84%). Despite an improved outcome for Type II and III fractures with increasing surgical experience, the results of operative intervention in Type IV fractures were no better, even after four years.(ABSTRACT TRUNCATED AT 250 WORDS)