A few months back I had a debate with another trainer about the use of the neutral grip on an upright chest press machine. I had learned that the neutral grip was better for the anterior shoulder capsule; the grip took some of the stress off of the area. I've had numerous recurring shoulder injuries over the past 12 years, and I can feel a difference between the conventional and neutral grips. Additionally, I've learned that front raises for the anterior deltoid should be done with the palms facing one another to prevent impingement. However, the other trainer disagreed with the neutral grip.
Perhaps you can shed light on this for me
I fully understand the confusion and rightly so when one reviews the difference between topographic anatomy and functional anatomy. Topographic anatomy teaches how to map around the body, whereas functional anatomy explores the functional interaction of the neuromusculoskeletal system. Both studies are necessary but need delineation for proper discussion with a question like yours.
When one performs a traditional pulldown with palms facing away and elbows out by their sides, they are in a neutral radioulnar position. Using the same fixed hand position, bring your elbows in front of your body and you have moved from neutral at the radioulnar joint to pronation, which will in fact changes muscle recruitment patterns. Always remember to explore what neutral is compared to pronation and supination.
Do not look at hand position relative to the world; examine the position of the bones that make up the joint and then the muscles best suited to recruit the movement you are debating.
What you will find most often is the debate is subjective to ones understanding or in some cases lack of understanding of functional anatomy. As for shoulder stress, there is research that the scapular plane is a plane that provides greater glenohumeral congruency and better positioning for optimal recruitment of the shoulder muscle complex. When there is greater congruency, (providing your form is perfect throughout the chain), there will be less strain placed on the healthy shoulder.
Another important point: If you have had multiple shoulder injuries, it may of your best interest to seek a qualified person to assess your entire body seeing as the shoulder is just one component of complex interactions. So often we chase symptoms rather than look for the possible causes of strain that can perpetuate repetitive problems.