The Blocking Points: The Keys to Consistency in Preservation Rhinoplasty

Goals/Purpose: Dorsal preservation is a growing area of interest amongst rhinoplasty surgeons. A challenge that is unique to dorsal preservation is the phenomenon of hump recurrence, owing to the existence of anatomical blocking points. Blocking points are resistant tensile forces that either impede dorsal lowering intraoperatively or push the dorsum back to its native convexity over time. Anatomic blocking points have been previously described, but their relevancy to particular preservation techniques remain unclear. The goal of this study was to better define the blocking points and their proposed solutions by exploring their anatomical basis in a cadaveric model.

Methods/Technique: A cadaveric dissection was performed to identify the relevant blocking points encountered during dorsal preservation rhinoplasty. The noses were degloved to expose the underlying anatomic structures, and dorsal lowering was simulated after performing each of the following: high septal strip, subdorsal Z-flap, and low septal strip. Mobilization of the bony pyramid consisted of lateral and transverse osteotomies. The push down maneuver was performed, followed by the let down maneuver. This sequence allowed the authors to identify the key blocking points for both impaction methods and three septal resection methods.

Results/Complications:

In total, seven blocking points were identified. These were identified as structures that caused direct impingement or increased resistance when attempting to lower the dorsum. Five of these have been previously described, which the authors expound upon and propose an additional two:

(i) Cartilaginous septum: septal blocking points were relevant to all three resection types when imprecise septal cuts left remnant spicules blocking reduction. In the high septal strip technique, a remnant subdorsal strip of cartilage remained after the resection and blocked lowering of the dorsum. Performing vertical chondrotomies beneath the K area allowed for the necessary expansion to facilitate dorsal lowering without tension.

(ii) Perpendicular plate of the ethmoid (PPE): this blocking point was relevant to all septal resection techniques. Full mobility of the dorsum was only possible when septal cuts were performed to the level of the radix osteotomy and bony edges were free of spicules or irregularities.

(iii) Lateral osteotomy: when employing the push down technique, the thick bones of the frontal process of the maxilla presented another blocking point. Osteotomies that were made horizontally along the surface of the maxilla created an unfavorable leading edge that impeded descent of the nasal pyramid. This can be minimized by changing the direction of the bony cuts from a horizontal to a sagittal plane, or by using the let down technique.

(iv) Webster’s triangle: preserving Webster’s triangle at the caudal lateral osteotomy created a bony protuberance that restricted impaction of the nasal pyramid during the push down technique. This blocking point can be removed or bypassed by utilizing the let down maneuver.

(v) Internal mucoperiosteum of the maxillary bone: elevating the mucoperiosteum from the inner maxillary surface alleviated the periosteal tissue resistance to dorsal lowering by creating added space to accommodate descent of the bony vault into the pyriform aperture.

(vi) Medial Canthal Ligament: resistance was noted at the region of the medial canthal ligament during dorsal lowering, which was relieved after undermining this area. However, it was noted to drop the radix height, therefore the authors recommend preserving this ligament unless this is a primary intention.

(vii) Lateral keystone area: dense attachments at this interface formed by the pyriform ligaments and fused periosteum of the nasal bones and perichondrium of the ULCs prevented the anterior and caudal expansion required at the lateral K area to facilitate flattening of the dorsal convexity in all specimens. Separation of these attachments at the lateral K area, known as the Ballerina maneuver, enabled the extension necessary to allow flattening.

Conclusion: Seven anatomic blocking points were identified during the authors’ cadaveric dissection. Knowledge of these key blocking points, their proposed solutions, and relevancy to the surgeon’s chosen dorsal preservation technique is critical in minimizing hump recurrence and ensuring consistent, long-term results.