Dear Editors,

McInerney and colleagues have done the field a service in drawing together the functional evidence on dorsal preservation rhinoplasty (DPR).Reference McInerney, Eustace and Amin¹ Their conclusion, that preservation does not cost airway, accords with our own experience. We write to suggest that the review’s most valuable contribution may lie in defining what the present evidence cannot yet address and to propose where the next studies should look.

Firstly, the issue is one of resolution. The Nasal Obstruction Symptom Evaluation, the Standardised Cosmesis and Health Nasal Outcomes Survey obstruction subscale, the 22-item Sino-Nasal Outcome Test and visual analogue scales are global measures of perceived obstruction. None localises symptoms to the internal nasal valve, which is the very structure that dorsal preservation is claimed to protect. A patient whose septum has been straightened will report a substantial fall in symptom score whether or not the valve angle has altered by a few degrees in either direction. The instruments dominating this literature are therefore insensitive to the hypothesis being tested. Site-specific assessment, with the valve angle and minimum cross-sectional area measured at defined landmarks under a standardised decongestion protocol, would answer the anatomical question that symptom scores cannot.

Secondly, we would caution against treating push-down and let-down as interchangeable. The review found no functional difference between the variants, but the two manoeuvres are not mechanically equivalent. Push-down impacts the bony pyramid towards, and partly within, the piriform aperture, whereas let-down removes a bony wedge so that the pyramid descends without impaction.Reference Saban, Daniel, Polselli, Trapasso and Palhazi^2, Reference Toriumi³ Whatever their equivalence at the middle vault, their predicted effects differ at the bony vault and the piriform rim, and no included study had measured the airway at that level. Pooling them may be concealing a real difference at the one site where the techniques genuinely diverge.

Thirdly, and to our mind the most interesting gap, the review’s framework is entirely geometric. Perceived nasal patency depends substantially on trigeminally mediated mucosal cooling, rather than on cross-sectional area alone,Reference Zhao, Blacker, Luo, Bryant and Jiang⁴ a physiological principal present in this field since Cottle’s original account of restoring nasal function.Reference Cottle and Loring⁵ Dorsal preservation avoids degloving the middle vault and leaves the upper lateral cartilage mucoperichondrium, and the sensory innervation it carries, largely undisturbed, whereas structural techniques open this region to place spreader grafts or flaps. If preservation confers an advantage in perceived breathing at equivalent geometry, sensory preservation is a plausible mechanism and a testable one. It would also account for the recurring pattern across the included studies, in which subjective gains are consistent, while objective differences are not.

Fourthly, the population studied is the one least able to reveal harm. Candidates for DPR are selected for straight dorsa, favourable, keystone anatomy and limited septal deviation. The literature therefore answers whether preservation damages an airway that was already adequate. The clinically pressing question, whether preservation is appropriate for patients presenting with significant baseline obstruction, remains open and can be settled only by studying that group directly.

A study designed to advance this field would, we suggest, recruit patients with documented baseline obstruction; randomise those anatomically eligible for either approach; pre-specify a non-inferiority margin against a minimal important difference for the chosen instrument, as the comparative studies to date were not powered for the equivalence they are taken to show; measure the valve at defined landmarks under a standardised protocol; report push-down and let-down separately; and follow patients beyond two years, the failure modes of preservation being late rather than early. Until such a study exists, the position the data comfortably supports is that dorsal preservation has not been shown to impair the nasal airway and that superiority remains undemonstrated in either direction. That claim is a narrower than functional equivalence, but it is a secure one and it points clearly to the work that still needs doing.