Arthrodesis, or joint fusion, is a surgical procedure that aims to alleviate pain by permanently connecting two or more bones in a joint. A key factor in the success of this procedure is joint compression, which is typically achieved using screws. The subtalar joint, located in the foot, is one area where this procedure is commonly performed. However, the effectiveness of different screw types and configurations in achieving optimal compression has been a subject of ongoing research.
Traditionally, conventional screws have been used to generate compression in the subtalar joint. These screws have a head that is larger than the body of the screw, which allows them to exert pressure on the bone surface and create compression. However, a newer type of screw, known as a headless screw, has been gaining popularity. These screws have a variable thread pitch, which means the distance between the threads varies along the length of the screw. This design allows the screw to achieve bony contact and generate compression without the need for a large head.
Despite the increasing use of headless screws, there has been a lack of research assessing the amount of compression they can generate in the subtalar joint. A recent study aimed to fill this gap by measuring the compression achieved by two posteriorly placed headless screws and quantifying the additional compression gained by placing a third screw anteriorly.
The study used ten unpaired fresh-frozen cadaveric subtalar joints and fixed them using different screw configurations. The configurations included two diverging posterior screws, two parallel posterior screws, and two parallel screws with an additional anterior screw. A custom-built measuring device was used to directly quantify joint compression during screw insertion.
The results showed that two diverging posterior screws generated a mean compression of 246 N. Two parallel posterior screws produced 294 N of compression. The addition of a third, anterior screw increased compression to 345 N, a significant increase. Interestingly, the compression achieved by two-screw fixation was slightly less than that reported for subtalar joint fixation with two conventional lag screws. However, when a third screw was added, the compression was comparable.
These findings have important implications for clinical practice. Headless screws are particularly advantageous in areas where prominent screw heads can cause problems, such as the load-bearing surface of the foot. Therefore, understanding their effectiveness compared to other screws is crucial for making informed decisions about screw selection. The study suggests that while two headless screws may generate slightly less compression than conventional screws, the addition of a third screw can enhance compression significantly. This could be particularly beneficial in situations where conditions for fusion are suboptimal.
In conclusion, this study provides valuable insights into the use of headless screws in subtalar joint arthrodesis. It highlights the potential of these screws to achieve comparable compression to conventional screws when used in a three-screw configuration. This information can serve as an objective basis for screw selection and may lead to improved outcomes in subtalar joint arthrodesis.
To read the full journal article, head to http://feedproxy.google.com/~r/FootAnkleInternational/~3/N2b-Ze0ubYA/1357