OTA 1999 Posters

Poster #111

Transcutaneous Oximetry and Laser Doppler Flowmetry as a Predictor of Healing Complications following High-Energy Fractures of the Distal Tibia

Laura S. Phieffer, MD; Matthew J. Weresh, MD; Kenneth A. Egol, MD; Stephen S. Sims, MD; James F. Kellam, MD; Michael J. Bosse, MD, Carolinas Medical Center, Charlotte, North Carolina, Charlotte, NC

Purpose: To determine if transcutaneous oximetry (TcPO2) and laser doppler flowmetry (LDF) can be used as a standard, reliable and objective means to assess the severity of soft tissue injury in distal tibia fractures, as evidenced by outcome and complications of fracture healing.

Methods: This IRB-approved prospective observational study analyzes high-energy distal tibia fractures, as delineated in the fracture and dislocation compendium of the Orthopaedic Trauma Association, that presented within 36 hours of injury. Only OTA type 43-A3, 43-B3, 43-C2 and 43-C3 fracture patterns were included. Soft tissue injuries were graded according to the Gustilo and Anderson and Tscherne classification systems. After informed consent was obtained, a standard protocol was followed. Initial TcPO2 and LDF measurements were collected within 36 hours of the time of injury. TcPO2 data was collected by certified technicians. LDF measurements were collected by trained research fellows. Three separate measurement sites about the distal tibia were evaluated. Serial measurements, taken every 72 hours, at all sites were recorded until definitive stabilization was performed. A final postoperative measurement was then obtained 24 hours after the definitive procedure. Outcome measures included infection, wound necrosis, and need for additional procedures to achieve union (excluding bone loss). Standard statistical methods, utilizing SAS software, were employed. T-tests were used when data was normally distributed, otherwise Wilcoxan Rank Sum tests were employed.

Results: 35 consecutive adult patients met the inclusion criteria for the study. Six patients were excluded (2 deaths, 1 declined from the study, 1 requiring initial free-flap coverage, 1 four-compartment fasciotomy, 1 lost to follow-up). The remaining 29 patients form the basis of this study. Average age was 43.2 years (range 20 ­ 79.3). There were 13 females and 16 males. Mechanisms of injury were 19 motor vehicle collisions, 9 falls >from height and 1 pedestrian versus car. There were six 43-A3, four 43-B3, seven 43-C2 and twelve 43-C3 fractures involved. Nine patients had open injuries (3 Gustilo and Anderson type I, 1 type II, 4 type IIIA, and 1 type IIIB). There were a total of sixteen complications (eight soft-tissue and eight bony complications) in eleven patients; of these, eight required subsequent surgical procedures. There was a higher proportion of complications in patients with C3 fracture patterns or open injuries. Statistically, initial injury TcPO2 measurements were able to predict bony healing complication (p=0.0078). However, they could not predict soft tissue complications (p=0.061). TcPO2 values for bony union were 21.3 ± 25.1 mmHg (mean ± SD) range 1.0 to 99.0 mmHg vs. non-union 5.0 ± 7.7 mmHg (mean ± SD) range 1 to 23 and values for soft tissue healing were 19.5 ± 24.1 mmHg (mean ± SD) range 1.0 to 99.0 mmHg vs. soft-tissue complication 9.6 ± 18.2 mmHg (mean ± SD) range 1.0 to 54.0 mmHg. No pre-operative LDF measurements showed significance (p=0.09). Neither postoperative TcPO2 or LDF were predictive of bony or soft tissue complications.

Discussion: The ability to evaluate and quantify the severity of soft tissue injury in connection with fractures is elemental in successfully treating traumatic skeletal injuries. This issue is exemplified by the current dilemma in treating high-energy distal tibia fractures. Failing to properly identify soft tissue injury leads to complications such as infection, wound necrosis, delayed union, and nonunion. Recent emphasis has been placed on developing a classification for soft tissue disruption that can be used in conjunction with the existing fracture classifications. Current soft tissue classifications are useful insofar as they categorize soft tissue injury, but the categorization is subjective. An objective means of measuring soft tissue injury is needed. The ability to quantify the severity of soft tissue injury would enable physicians to identify patients at higher risk for complication, to better determine the appropriate timing and technique of treatment, and to compare similar presentations and outcomes with other clinical investigators. Vascularity and oxygen delivery are critical aspects of tissue injury and healing and can be measured with current technology. TcPO2 has been recognized as a useful predictor of soft tissue healing by several authors, while the use of LDF as a predictor of soft tissue healing has been less successful. Our study shows similar results. Although, on average, statistical significance with TcPO2 measurements was found, a clear definition of values for the healing compared to the non-healing groups was unable to be delineated due to the wide ranges of values reported in each group despite standardization of procedures. This differs from published studies on ischemic limbs and prediction of amputation level healing where authors have found clear definitions of values between the healing and non-healing groups.

Conclusions: High-energy distal tibia fractures remain a difficult treatment problem due to the difficulty of soft tissue management. Open injuries and multi-fragmentary intra-articular fractures are associated with poor outcomes. Laser doppler flowmetry does not appear to be of any value as a predictor of postoperative complications. Transcutaneous oxygen measurements were of no value in predicting soft tissue complications but appeared to correlate with bony complications. Clear critical values, however, could not be established.