The Popliteal Artery is Safe in Medial Meniscal Repair Using All Inside Devices in Adults: An MRI-Based Simulation Study.

Introduction: This simulation study on MRI of the knee was performed to assess the risk of injury to the popliteal artery (PA) and common peroneal nerve (CPN) during all-inside meniscal repairs in adults. Methods: We simulated repair of the posterior horn of both medial (PHMM) and lateral menisci (PHLM) through anteromedial (AM) and anterolateral (AL) portals, using straight and curved devices, on 200 magnetic resonance imaging (MRI) scans taken with the knee in extension. For simulation using straight devices, the shortest distance from the menisco-capsular junction (MCJ) and the free edge of the meniscus to PA and CPN in vectors of AM and AL portals was measured. In curved devices, the closest extracapsular distance from the device tip to PA was measured. Results: With a straight device through AM portal, the mean distance from the MCJ of PHMM to the PA was 20.7 ± 3.15 mm (13.5-27.4). In PHMM repair through AM portal using a curved device, the mean extracapsular distance from the device tip to PA was 18.8 ± 4 mm (7.7-27.2) while pointing toward and 26 ± 4.5 mm (15.5-35.6) while pointing away from the midline. When using straight devices, the average distance from free edge of LM to PA was 18.5 ± 3.3 mm (9.6-31.2) and from MCJ to PA was 8.9 ± 2.4 mm (3.5-18.8). The average distance measured from the MCJ to CPN through AM and AL portals using straight devices was 19.4 ± 2.8 mm (10.2-32.5) and 22 ± 2.8 mm (10.4-36.7) respectively. Conclusion: In adults, PA is safe in PHMM repairs using both straight and curved devices irrespective of depth and direction of insertion. In PHLM repairs, the PA is at risk with both straight and curved devices. We recommend adjusting the depth of insertion to as minimum as possible to just penetrate the capsule. The CPN is safe in LM repairs using all-inside devices. Level of Evidence: Level IV.

Manual extraction is superior to power tools when removing stripped titanium locking screws.

INTRODUCTION: Removal of screws from a titanium locking plate is often difficult once the screw has seized and the head is damaged. Such stripped screws are removed with an extraction screw, which can be used manually or on power. We aim to compare the extraction rates using both these methods. MATERIAL AND METHODS: We used 50, 3.5 mm diameter/20 mm long titanium locking screws. Fourth-generation saw bone models (radii) were used and 3.5 mm locking plates were fixed. The screws were deliberately over tightened and heads were damaged using a carbide drill to mimic stripped, seized screws. A left turn conical extraction screw coupled with a power tool was used for the first 25 screws and extraction screws coupled with a T handle for the remaining 25. A high-definition camera with a 60 fps frame rate was used to record the event. The time taken to remove screws from the plate was recorded. RESULTS: When the extraction screw was used manually with T handle, we could remove 23 out of 25 screws (92%). When we used the extraction screw along with a power tool, 15 out of 25 (60%) locking screws were successfully removed. CONCLUSION: We recommend manual extraction with a T handle, rather than a power tool when removing the stripped locking screws (p-value <0.001). We feel that the haptic feedback provided when using manual extraction allows the surgeon to engage the extraction screws onto the damaged heads, thereby improving the extraction rates.

Brodie's Abscess Following Radiofrequency Ablation of an Atypical Osteoid Osteoma.

A 15 years old boy presented with an atypical osteoid osteoma (OO) in distal femur. He underwent radiofrequency ablation (RFA) elsewhere. He presented to our centre a year later with persisting pain. MR scan showed incomplete ablation of the nidus as there was only a single pass of the RF probe for a 14 mm long linear lesion. We also found penumbra sign and wall enhancement on contrast MRI suggestive of a Brodie's abscess (BA). Under CT guidance the OO was drilled and BA was saucerised. Following this he was treated with culture sensitive antibiotics and his symptoms resolved. BA and OO are common differential diagnoses. RFA of OO leading to BA has not been reported in literature. Atypical linear OO requires multiple probe placements to ablate the long nidus. Diligent care should be taken to avoid intraoperative contamination in CT room which could lead to infection.