Guide Pin Insertion Research Articles

Improved accuracy of computer assisted glenoid implantation in total shoulder arthroplasty: An in-vitro randomized controlled trial

Glenoid replacement is challenging due to the difficult joint exposure and visualization of anatomical reference landmarks. Improper positioning of the glenoid component or inadequate correction of the retroversion using currently available instrumentation may lead to early failure. The objective of this study was to evaluate a computer-assisted technique to achieve a more accurate placement of the glenoid component compared to traditional techniques. Sixteen paired cadaveric shoulders were randomized to either traditional or computer-assisted glenoid implantation. Preoperative planning consisting of CT scanning with 3-dimensional image modeling of the shoulder specimens and intraoperative tracking with real-time feedback provided to the surgeon was employed in the computer-assisted group. A validated, previously published, standardized protocol for tracking the orientation of the glenoid in space using 3 glenoid surface landmarks was employed. All phases of glenoid implantation (initial guide pin insertion, reaming, drilling of the peg holes, and final component implantation) were tracked and recorded by the computer. A post-implantation CT scan was performed in both groups to compare how accurately the implants were placed. The computer-assisted technique was more accurate in achieving the correct version during all phases of glenoid implantation and as measured on the post-implantation CT scan (P < .05). The largest errors with traditional glenoid implantation were observed during drilling and, more so, during reaming. The trend was to overly retrovert the glenoid. Computer assisted navigation results in a more accurate glenoid component placement relative to traditional techniques. Basic Science Study.

Risk of Iatrogenic Injury to the Peroneal Nerve during Posterolateral Femoral Tunnel Placement in Double-Bundle Anterior Cruciate Ligament Reconstruction

Background There has been concern for iatrogenic injury to the peroneal nerve with posterolateral femoral tunnel placement in double-bundle anterior cruciate ligament reconstruction. Hypothesis The common peroneal nerve and biceps tendon are at increased risk for injury by the guide wire as the knee is brought into increased extension. Study Design Controlled laboratory study. Methods An anatomical descriptive study was performed on 10 cadaveric knees (ages 49-67 years). After the native anterior cruciate ligament was removed arthroscopically, the posterolateral femoral tunnel starting point was identified using standardized measurements from the articular cartilage rim. With the use of a low-medial accessory portal and one cortical entry point, guide pins were inserted at 120°, 90°, and 70° of knee flexion. The guide pins were kept in situ, and the lateral structures of the knee were dissected. The distance between guide pins and the common peroneal nerve, as well as the relationship to the biceps tendon, were analyzed. Results The common peroneal nerve was not directly injured during any guide pin insertion. The mean distance from the guide pin at 120° of flexion was 44.3 mm (range, 36-53 mm), compared with 28.6 mm (range, 25-32 mm) at 90° of flexion and 22.8 mm (range, 20-28 mm) at 70° of flexion. The differences between all 3 groups were statistically significant (P < .0001). Guide pins inserted at 70° of flexion were also noted to pierce the biceps femoris tendon in all cases. Conclusion and Clinical Relevance During posterolateral femoral tunnel placement, the risk of injury to the common peroneal nerve is minimal but is increased as the knee is placed in less flexion. Guide pin placement at knee flexion of 120° is recommended to ensure safety of the peroneal nerve and the biceps tendon.

Fixation of Proximal Fifth Metatarsal Fractures

In athletes or in high-demand patients, requiring return to preinjury physical activity status as soon as possible, fixation of proximal fifth metatarsal fractures using intramedullary cannulated screw techniques is a safe and efficient management alternative. Appropriate screw diameter and length, corresponding to the patient's stature, metatarsal dimensions, and shaft curvature, must be chosen. Optimal guide pin insertion under fluoroscopic control is mandatory. Postoperative management and fixation protection should be individualized. Under these conditions, quick union is predictably achieved with very low complication rates and satisfactory mean time of return to preinjury activity levels.