Transverse process osteotomy for surgical drainage of primary iliopsoas abscess and secondary cases combined with spondylodiscitis

Iliopsoas abscess refers to collection of fluid in iliopsoas muscle compartment. It is well-known condition in medical history as a complication of tuberculous spine infection. Most of the cases now are due to pyogenic infection. Patient usually presents late due to delayed diagnosis. We aim to present a less invasive technique for surgical drainage of iliopsoas abscess.

It is a prospective study done between 2015 and 2018. The study included 28 patients with confirmed diagnosis of iliopsoas abscess. Laboratory investigations included CBC, ESR, and C-reactive protein that were done for all patients. MRI with contrast enhancement was gold standard for diagnosis. Ten patients underwent surgical psoas abscess drainage by transverse process osteotomy via Wiltse approach without any other spine intervention. Eighteen patients had posterior spine fixation and interbody fusion together with transverse process osteotomy and abscess drainage as treatment for spondylodiscitis. The patients were followed up for clinical improvement, and functional assessment was done by Oswestry disability index. ESR and CRP were used for laboratory follow-up of infection subsidence. Follow-up of abscess size and resolution was done by pelvic-abdominal ultrasonography.

The mean maximum width of the abscesses in MRI axial views was 38.8 mm. Patients were divided into two groups. Group (1) included ten patients who underwent drainage only while group (2) included 18 patients who underwent spine fusion for treatment of spondylodiscitis. The amount of pus drained intra-operatively was of average 234 cc in group 1 and 191.6 in group 2. The drain was removed in average 58.6 hours post-operatively in group 1 with mean of 168.4 cc of drained fluid and in average of 74.3 hours for group 2 with mean of 350.5 cc of drained fluid. The ODI and inflammatory markers improved in all patients. The follow-up period was of average 26.7 months. The organism was isolated from 19 patients (5 patients were tuberculous and 14 patients were different pyogenic pathogens). No fluid recollection was observed in pelvic-abdominal ultrasound during follow-up in our series.

Transverse process osteotomy is a safe and effective approach for drainage of psoas abscess. It can be done alone or combined with posterior spine fusion for treatment of spondylodiscitis.