Session III Tibia

Internal Fixation vs Small Wire Circular External Fixation of Pilon Fractures: Treatment Protocol Based on Severity of Soft Tissue Injury

J. Tracy Watson, MD, Berton R. Moed, MD, David E. Karges, DO, Kathryn E. Cramer, MD

Henry Ford Hospital, Department of Orthopaedics, Detroit, MI

Introduction: Pilon fractures are often a combination of skeletal and soft tissue injury. Most complications related to traditional ORIF techniques are soft tissue related. Circular external fixation has been noted to have encouraging results for use in these injuries, however, no specific recommendations are present to determine indications for their use. The purpose of this study was to establish the efficacy of a treatment protocol based on the severity of soft tissue injury. ORIF techniques were undertaken for injuries accompanied by minor soft tissue compromise. Small wire circular external fixation was performed on those fractures with severe soft tissue damage.

Materials and Methods: From January 1989 through July of 1995, 107 pilon fractures were treated at our institution according to a staged prospective protocol. All fractures were immediately stabilized by application of a 2 pin external fixator or calcaneal pin traction. Open fractures were taken to the operating room for immediate I&D and stabilized as above. All articular injuries were then evaluated by CT scan. At a second procedure, definitive fixation was achieved. Patient's with Tscherne Grade 0 or I injuries underwent standard ORIF techniques (41 patients). Patients with Tscherne Grade II and III soft tissue injury or open fractures underwent secondary fixation using limited incisions for articular reduction and stabilization with small wire circular external fixators (64 patients). Follow-up included radiographic and functional evaluation (modified Mazur score). Average follow-up was 3.9 years (range 8 months - 6.4 years). Eleven patients were lost to follow-up within 1 year of treatment and 2 open Grade Ill-C injuries underwent immediate amputation, all were eliminated from the study group.

Results: The study group included 36 fractures in the internal fixation group (IF) and 58 fractures in the external fixation group (EF). For the EF group, there were 28 closed and 30 open fractures: 8 Grade I, 9 Grade II, 8 Grade Ill-A, 4 Grade Ill-B, 1 Grade Ill-C open fractures. For closed injuries; 13 Tscherne Grade II and 15 Tscherne Grade III. A/O classification for the EF group included 15 Type A, 14 Type B and 29 Type C fractures. In the IF group, there were 11 Type A, 15 Type B, and 10 Type C injuries with equal numbers of Tscherne Grade 0 and I. Planned secondary procedures in the EF group included 4 tree flaps, 3 skin grafts and 9 bone grafts to achieve union. In the IF group 5 bone grafts were performed at the time of fixation.

Overall, for all fracture types, 81% of the EF group and 75% of the IF group had good or excellent results (not significant). For the severe skeletal injuries (Type C) both groups demonstrated poorer results when compared to less severe fracture types (P=0.00l). Severe wound complications occurred in 15% of the IF group requiring 2 additional free flaps and 3 STSG with resultant 5% deep infection rate, (all in C-Type fractures). Late loss of reduction 15%, nonunion 11%, and malunion 4% also occurred. The IF group demonstrated multiple secondary surgeries including 5 osteotomies for malunion, 27% late hardware removal and 3 late arthrodeses (all Type C fractures). EF demonstrated a 4% rate of superficial wound complications requiring local wound care only. No deep bone infection or chronic pin track sequela occurred. All patients had some degree of minor pin track infection or pin related problem. Late complications included 3% non union, 5% loss of reduction and late malunion, (all C-Type injuries). Three patients required late osteotomy for malunion. Four patients underwent arthrodesis (all C-Type injuries).

Discussion: The outcome of C-Type injuries is generally worse than those injuries with less severe fracture patterns regardless of the treatment method. Variables that significantly affected functional outcome includes the presence of articular incongruency or defect >2 mm, malalignment of the mechanical axis and the degree of soft tissue injury. Those injuries that were accompanied by a higher Grade soft tissue injury all had a poor outcome regardless of the fracture type, even for A Type injuries. IF techniques demonstrated a higher incidence of soft tissue and bony complication, when treating C Type fractures. EF demonstrated a decreased incidence of complications and thus should be utilized on those fractures with significant soft tissue injury or on C Type fractures. However, IF is still the treatment of choice for A and B Type fractures presenting with a low grade soft tissue injury.