Introduction: Percutaneous iliosacral screws are commonly used for the fixation of the posterior pelvis. The procedure is technically demanding because of the limitations of radiological visualisation of the relevant landmarks. There have been several reports of misplaced screws and other complications, occasionally with serious consequences. To achieve a secure surgical procedure we routinely use a CT-guided technique for percutaneous pelvic screw fixation since 2004.

Methods: Between September 2004 and January 2009, 39 patients were treated using CT-guided screw fixation. Under general anaesthesia patients were placed on a vacuum mattress in a stable lateral position within the CT gantry (Siemens SOMATOM definition; i-Fluoro: 20mAs; Hand CARE mode). The scanner bed was on a calibrated track so the same images could be used and repeated throughout the procedure. Gantry and patient were draped under sterile conditions. The laser sights of the CT indicated the cutaneous site which corresponded to the underlying osseous level (first or second sacral pedicle). At this the CT scan trajectory in the CT-fluoro mode indicated the extrapolated position of the guide-wire. A 3.2mm guide-wire was inserted using battery-powered equipment or hammer blows. When the guide-wire was in a correct position a self-drilling cannulated lag screw was placed (6.5mm DePuy). Two screws were inserted in sacral fractures, one screw in sacroiliac ligament ruptures.

Results: 19 of 39 patients were polytraumatized. In 10 cases there were both side injures. Overall 71 screws were placed. Median time for the procedure was 36 minutes in unilateral lesions and 48 min in bilateral lesions. There were no cases of infection, non-union or neurological deficit. Postoperative CT revealed correct screw positions in all cases. Screw removal was done routinely in the patients younger than sixty years to resolve the blocked sacroiliac joint.

Conclusions: CT-guided is a safe and feasible treatment option in patient with instable pelvic ring lesions. A close collaboration between interventional radiologist and surgeon is essential. Compared to other procedures g.e. internal plate fixation or fluoroscopic guided procedures CT-guided screw insertion seems to be more secure and could strongly be advocated.

Over the last 10 years ACI (Autologous Chondrocyte Implantation) has become an important surgical technique for treating large cartilage defects. The original method has been improved by using cell seeded scaffolds for implantation. The aim of our prospective study was to evaluate the efficiency of a matrix based ACI (MACI) with a collagen type I scaffold for repairing large cartilage defects of the knee. We present the clinical and radiological results of 22 pts. one year after collagen scaffold based ACI.

Out of 39 pts. treated with ACI for cartilage defects of the knee 22 had reached the one year follow up. We documented preoperatively and postoperatively (3, 6 and 12 months) the clinical situation with the IKDC Knee Examination Form. MRI scans were evaluated at all time points.

41% of the pts. were female, 59% male. The average age was 33 yrs. (min:15; max:49), the average BMI 25,4 (min:19; max:36). One third of the cartilage defects were localized retropatellar, the remaining on the medial or lateral femoral condyle. The average defect size was 5.7 cm2. In about 75% of the cases an additional surgical procedure was performed (ACL-reconstruction, lateral release, meniscal surgery). One major complication (a deep wound infection) occured. The IKDC score improved over time during follow up significantly. Patients with retropatellar defects have a poorer outcome compared to femoral defects. The MRI showed an improvement of the implanted scaffold over time as well.

The present study confirms the benefits of MACI in young patients with large cartilage defects of the knee. The matrix based ACI is a surgically less demanding technique then the traditional ACI. We expect a good long term outcome from MACI comparable to that of traditional ACI.