Role of CT angiography in reliability of distally based hemisoleus muscle flap for lower third leg defects

Surgical procedures: Under spinal or general Anathesia, patient in supine Position with semi flexed knee during flap harvest and extended at flap sitting, pre operative flap design and markings of CT angiography findings on the leg.Debridement of devitalized tissues at the defect, a longitudinal cutaneous incision is performed on the medial-side of the leg 1cm parallel to the medial border of the tibia. The major and secondary pedicles identified. Careful meticulous dissection of the secondary pedicles that were identified by CT angiography preoperative to enables a larger arc of rotation and, consequently, greater flap reach. The most distal secondary pedicles identified by MD CT angiography were ranging from 6 to 10 cm above medial malleolus, Such perforators appears with small caliber about 1.1 to 1.5 mm and directed medially within the distal soleus muscle.The flap is then rotated to the defect and covered with partial-thickness skin grafts. The donor site is closed directly with Suction drains are used and non-compressive dressing with immobilization.

RESULTS

Table 2: CT Angiography findings.

Table 3: Operative findings.

Fig 1: Correlation between pre operative CT angiography findings and intra operative clinical findings of the distal soleus muscle perforator with exact location.

Clinical example 1: 41 years old male patient with post traumatic chronic unstable scar with multiple sinus in the lower third of Rt leg (A) pre operative (B) marking of CT angiography perforator findings (C) Intra operative distal pedicles identification with the most distal pedicle about 9 cm above medial malleolus. (D&E) Axial and Coronal CT Angiography with identification of distal perforator (D.P) to soleus muscle originating from posterior tibial artery (P.T.A) about 9 cm above medial malleolus with caliber about 1.2 mm. (F) Immediate post operative (G) After 1 month (H) 3 months post operative follow up.

Clinical example 2: 49years old male patient with post traumaticraw area in the distal third of the lt leg (A) pre-operative (B) markings (C) flap harvest with distal pedicle identification about 10 cm above medial malleolus (D&E) Axial and coronal cuts of CT Angiography with identification of distal perforator (D.P) to soleus muscle originating from posterior tibial artery (P.T.A) about 10 cm above medial malleolus and caliber about 1.1 mm. (F) immediate post-operative  (G) 1 week post-operative (H) 3 months post-operative follow up.

DISCUSSION

High energy leg injuries frequently lead to soft tissues losses and skin imperfections and are commonly associated with bony fractures or even bony defects. These damages may be severe enough to be associated with major leg vessel injuries rendering reconstructive options limited. The lower one third skin defects of leg frequently represented a reconstructive challenging and the use of local skin flaps and distally based  fasciocutaneous flaps can be restricted particularly if their vascular pedicels fall within the area of injuries. ¹²

The reversed flow hemi-soleus flap with sacrifice of the posterior tibial artery to be included within the flaps was defined by Guyron in 1982. But the flaps didn’t became more popular as it has the great dis-advantage of sacrificing main blood vessels. ¹³

The distally based medial hemisoleus flap was first described by Tobin  in 1985 and associated high complication rate.

This work aim to assess the usage of CTA as adjunctive procedure to expect site, course, and calibre of the pedicle of distally based hemisoleus perforator flap to make this a more reliable choice for lower third leg defects to decrease complication rate with preservation of the major leg vessels.              

This study included 30 patients ( 22 males and 8 females )  all with lower third leg defects caused by deferent causes mostly post traumatic, all cases managed with distally based medial hemisoleus muscle flap based on distal secondary pedicle that preoperatively was identified by CT angiography using GE 128 Slice CT scan machine with injected Optiray 350 (radiopaque contrast agent), The most distal secondary pedicles were ranging from 6 to 10 cm above medial malleolus, Such perforators appears with caliber about 1.1 to 1.5 mm and directed medially within the distal soleus muscle.

All perforators identified by the CT angiography examinations were located intraoperationally nearly the same site in 17 cases . The distances between the intraoperational positions of the perforators and the positions established by the CT angiography analysis were 0.5 cm in 12 cases and 1 cm in 1 case.

Our study can be supported by the study by Higueras et al., ¹⁴ aimed to describe CTA as a planning tool in perforator flap operations in the lower limbs. The study enrolled 18 cases underwent perforator flaps for lower limb reconstruction. Ages mean was 57-yrs old. 9 cases (50%) were male.

As well the study by Feng et al.,¹⁵ matched the utilization of color Doppler US and CTA in pre-operative planning of lower limb perforator flap. They enrolled 40 cases with lower extremities defects who undergoing reconstruction with perforator flap.

In a series of 10 cases, Houdek et al.,¹⁶ performed a preoperative CT Angio to assess the posterior tibial vessels pedicle(s) to the distal soleus muscle, they also performed interoperative confirmation of the pedicle before flap harvest. They recommended a caliber of 1mm minimum for the distal arterial perforator and a caliber of 1.5mm or more for the accompanying vein to ensure flap reliability for Coverage of Distal Third Leg Wounds. The mean defect measured 23 cm2 (range 8–45 cm2)

As regard Clinical characteristics of the soft tissue defects of the studied patients we found that the mean lesion size 29.0 ± 7.58 cm2, 20 patients (66.7%) had the lesion on the right-side, and 10 cases (33.3%) had the lesion on the left-side. Meanwhile, 7 patients (23.3%) had bone fracture.

Regarding postoperative complications of the studied patients, 1 patient suffered from partial loss of the flap that healed by secondary intention and 2 patients (6.7%) suffered from graft loss due to congestion that were re grafted. Finally, there were 27 patients (90%) were excellent, 2 patients (6.7%) were good, and one patient (3.3%) were poor.

Whereas the study by Higueras et al.,¹⁴ reported that the evaluation of all flaps was acceptable, excluding in 3 cases with peroneal artery perforator flaps, which existing necrosis of the distal part because of venous congestions and healed by secondary intentions. These flaps were maybe overfilled owing to an improper location, twisted pedicle or attendant pathology. So, they settled that the usage of CTA scanning was precise and a beneficial in surgical planning, easing more precise flaps designs and straight closures later.

The study by Feng et al.,¹⁵ reported that all cases have no complications except 2 cases have necrosis in the distal area of the flaps (2 × 2 cm). There was 95% success rate. Based on their comparative study of color Doppler US and CTA in the pre-operative mapping of lower limbs perforators. As well, color Doppler US still the only choice for cases with an allergy to the difference or in cases of renal deficiency.

Furthermore, the study by Houdek et al.,¹⁶ reported successful reconstruction in all cases, with only minor flap tip loss in one patient. Deserving mention, repeat skin grafting was needed in 4 out of the 10 cases.

CONCLUSION

CT Angiography has a great role to identify the distal perforators of soleus muscle (site, caliber and course) with great role to detect pre-operative viability that make distally based hemisoleus muscle flap a reliable option for lower third leg defects. This method simplifies operative planning, may decrease operative period, rises the consistency of the usage of these flaps and makes operation more safe.