[Callus Distraction in the Treatment of Post-Traumatic Defects of the Femur and Tibia].

PURPOSE OF THE STUDY Evaluation of the results in patients treated for post-traumatic defects by the method of callus distraction of the femur and tibia using a monolateral external fixator. MATERIAL AND METHODS The group comprised 42 patients, 38 men and 4 woman, who underwent callus distraction using a monolateral external fixator in the Trauma Hospital Brno in the period from 2003 to 2010. The average age of the patients on the day gradual callus distraction was commenced was 32 (18-64) years. Post-traumatic bone defects were treated in 31 patients and deformities resulting from resection of post-traumatic infection loci in 11 patients. The tibia was involved in 34 and the femur in eight patients. The average follow-up in the out-patient department was 24.3 months (range, 7 to 118 months) after the fixator had been removed. The monolateral external fixator LRS Orthofix (Italy) was used in all patients. RESULTS The average length of defects treated by callus distraction was 5.5 cm (3-16 cm). The average interval between osteotomy and distraction commencement was 6.1 days (4-8 days). The average duration of distraction was 74 days (33-162 days); the average time of fixator application was 168 days (138-416 days). The average healing index was 42 days per cm of bone (26-88 days per cm). The treatment of soft tissue loss during callus distraction was necessary in six patients (14.3%). Of these, two (4.8%) had local fasciocutaneous flap skin coverage, and four (9.5%) free issue transfer. A total of 38 complications were treated, i.e., 0.9 complication per each callus distraction of the femur or tibia. Of them, pin-tract infection was most frequent and was recorded in 21 patients (50%). It was usually managed by regimen arrangement and oral antibiotic therapy. The screw had to be removed due to septic loosening in five patients (11.9%). Breakage of a fixator pin occurred in three patients (7.1%). No fracture after fixator removal was recorded. Callus angulations were managed by correction of fixator during distraction in two patients (4,8%). In one patient (2.4%), premature healing of fibular osteotomy was treated by a new resection osteotomy. One patient (2.4%), following callus distraction, underwent Achilles tenotomy. The docking site after segmental bone transport did not heal in two patients (4.8%) who subsequently underwent revision surgery involving spongioplasty; bone union was achieved. Callus distraction in all patients was completed with the use of external fixators initially applied. All patients achieved full weight-bearing on the treated extremity. DISCUSSION In this study we evaluated the results of callus distraction carried out by means of a monolateral external fixator. This type of fixation seems very useful because the telescopic system allows for adjustment without necessity to change its assembly. Dynamic adjustment is important at the stage of callus maturation. A monolateral fixator is better tolerated by patients than is a circular fixator, though both systems give the same results. The process of callus distraction is associated with many different complications. Neither the height of femoral or tibial osteotomy, nor the method of its performance had any significant effect on callus formation. Spin-tract infection is the most common complication. Its frequency can be reduced by using 6-mm pins coated with hydroxyapatite. Delayed healing is rare in simple callus distraction but occurs in the cases of segmental bone transport or repeated osteotomy. CONCLUSIONS The method of callus distraction is effective in the management of large bone defects. The treatment procedure depends on the extent of bone loss, size and type of soft tissue damage and presence or absence of infection. We prefer the use of monolateral external fixators for their ability of form adjustment and of 6-mm pins coated with hydroxyapatite. Key words: callus distraction, post-traumatic bone defect, external fixator.