Technique

Beach chair vs lateral decubitus: what the evidence says, and what you need to know before you scrub

The orthobro · 2026-08-26 · 7 min read

You will be asked which position is better. The honest answer is that the outcome literature does not support a clear winner, and that the person asking almost certainly has a preference anyway.

So the useful knowledge is not "which is better." It is what each position buys, what it costs, and what your job is during setup.

What the outcome data shows

For arthroscopic anterior shoulder stabilization, a retrospective comparison found that surgical position did not significantly affect recurrent instability, complications, or patient-reported outcomes. Across both groups, the overall recurrent dislocation rate was 7.8% at a mean of 3.3 years.

There were no significant differences in postoperative dislocations, subjective instability, reoperations, revisions, or complications. There was a trend toward a higher revision rate in the beach chair group — 6.1% against 1.9% — but it did not reach significance (P = .069), and a trend in one retrospective series is a reason to keep looking, not a reason to change practice.

Return to sport and postoperative ASES, SANE and OSI scores showed no significant difference between groups.

Broader reviews land in the same place: both positions are safe and effective for arthroscopic shoulder stabilization, with comparable rates of recurrent instability, revision, return to sport and patient-reported outcomes.

So the choice is made on other grounds.

What each position actually buys

The short version most residents end up carrying:

Lateral decubitus gives better access to the glenohumeral joint, easier visualisation of the labrum, and greater circumferential access. That is why it is favoured for instability and posterior work.

Beach chair puts the shoulder in an orientation that matches how you learned the anatomy, and converts to an open approach without repositioning. That is why it is favoured when open conversion is plausible, and why it dominates in trauma and arthroplasty settings.

Neither of those is a claim about outcomes. They are claims about the operation being easier to do, which is a different and entirely legitimate reason to pick one.

The beach chair setup

Trunk elevated to roughly 30–45°. The operative extremity draped free so the shoulder can be moved, which matters for reduction and for access through range.

The safety list is short and every item on it is somebody's job before the drapes go on:

• Head rest well padded, neck in neutral. Not extended, not rotated.
• Buttock or leg bolster placed so the patient does not slide caudally as the back comes up.
• Pillow or wedge under the knees.
• Bony prominences padded on the non-operative arm and both legs.
• Blood pressure monitoring appropriate to the position.

That last one is the one with a literature behind it, and it is the reason the position gets discussed at all outside of orthopaedics. When the trunk is elevated, the pressure at the head is lower than the pressure at the cuff on the arm. Whether and how to correct for that is an anaesthesia decision, not yours — but knowing that it is a live question is the difference between a resident who understands the position and one who has only memorised the angle.

The lateral decubitus setup

The trade for better access is that traction is doing work, and traction is what injures nerves.

The things to watch:

• Axillary roll. Placed to offload the down-side shoulder and protect the brachial plexus. Confirm it is where it is supposed to be, not where it was when it was thrown on the table.
• Traction weight and arm position. Both are set for the case. Both drift.
• Down-side arm. Padded, supported, and in a position somebody has actually looked at.
• Peroneal nerve on the down leg. Padded. This is the classic and it is entirely preventable.
• Hips and knees. Flexed and supported so the patient is stable through the whole case.

The failure mode nobody warns you about

Positioning injuries are not usually caused by ignorance of positioning. They are caused by the position changing after it was checked.

The table gets tilted. The back comes up further. The traction is adjusted for access and not adjusted back. Somebody leans on the leg. Ninety minutes pass.

There is a documented example of exactly this in beach chair: lateral femoral cutaneous nerve palsies from tight leg straps in patients with high BMI, where the straps get tighter as the patient is brought upright because the hips abduct and externally rotate. The straps were fine when they were applied. The position changed.

So the useful habit is not memorising the padding list. It is re-checking after any change to the table. That is a thing a junior resident can genuinely own and be valued for.

What to actually know before you scrub

Not the debate. The specifics of this case:

• Which position, and why this surgeon chose it for this patient.
• Who positions, and what your part is.
• Where the C-arm or tower comes in, and therefore where you will be standing.
• What the conversion plan is, if there is one.
• What this surgeon checks before the drapes go on, so you can check it first.

That last item is the one that gets you asked back. Every surgeon has a positioning detail they always verify, and it is never on the preference card either. Write down what it is the first time you notice, because you will not remember it three weeks later, and it is the exact thing that makes the second case with them go differently from the first.