[Osteotomies in rhinoplasty]

Using an impact hammer to perform biomechanical measurements during osteotomies: Study of an animal model

Osteotomies are common surgical procedures used for instance in rhinoplasty and usually performed using an osteotome impacted by a mallet. Visual control being difficult, osteotomies are often based on the surgeon proprioception to determine the number and energy of each impact. The aim of this study is to determine whether a hammer instrumented with a piezoelectric force sensor can be used to (i) follow the displacement of the osteotome and (ii) determine when the tip of the osteotome arrives in frontal bone, which corresponds to the end of the osteotomy pathway. Seven New Zealand White rabbit heads were collected, and two osteotomies were performed on their left and right nasal bones using the instrumented hammer to record the variation of the force as a function of time during each impact. The second peak time τ was derived from each signal while the displacement of the osteotome tip D was determined using video motion tracking. The results showed a significant correlation between τ and D (ρ² = 0.74), allowing to estimate the displacement of the osteotome through the measurement of τ. The values of τ measured in the frontal bone were significantly lower than in the nasal bone (p<10^-10), which allows to determine the transition between the nasal and frontal bones when τ becomes lower than 0.78 its initial averaged value. Although results should be validated clinically, this technology could be used by surgeons in the future as a decision support system to help assessing the osteotome environment.

Using an Impact Hammer to Estimate Elastic Modulus and Thickness of a Sample During an Osteotomy

Performing an osteotomy with a surgical mallet and an osteotome is a delicate intervention mostly based on the surgeon proprioception. It remains difficult to assess the properties of bone tissue being osteotomized. Mispositioning of the osteotome or too strong impacts may lead to bone fractures which may have dramatic consequences. The objective of this study is to determine whether an instrumented hammer may be used to retrieve information on the material properties around the osteotome tip. A hammer equipped with a piezo-electric force sensor was used to impact 100 samples of different composite materials and thicknesses. A model-based inversion technique was developed based on the analysis of two indicators derived from the analysis of the variation of the force as a function of time in order to (i) classify the samples depending on their material types, (ii) determine the materials stiffness, and (iii) estimate the samples thicknesses. The model resulting from the classification using support vector machines (SVM) learning techniques can efficiently predict the material of a new sample, with an estimated 89% prediction performance. A good agreement between the forward analytical model and the experimental data was obtained, leading to an average error lower than 10% in the samples thickness estimation. Based on these results, navigation and decision-support tools could be developed and allows surgeons to adapt their surgical strategy in a patient-specific manner.

3D photogrammetric analysis in hump nose correction based on nasal tip projection without dorsal augmentation in Asian rhinoplasty

INTRODUCTION

Hump nose in Asians should be managed differently in consideration of the lateral profile and the balance between the dorsal height and nasal tip projection. We suggest an alternative approach comprising mild rasping and nasal tip projection using a septal extension graft.

MATERIAL AND METHODS

In this retrospective study, patients who underwent hump nose correction with rhinoplasty between March 2012 and July 2015 were recruited. Instead of applying conventional dorsal augmentation after humpectomy, our approach involved only smooth dorsal contouring in limited cases. 15 patients were evaluated, with surgical outcomes demonstrated using three-dimensional photogrammetry.

RESULTS

Over the postoperative period, hump height decreased (pre 2.77 ± 2.07, post 0.31 ± 0.55, p = 0.001). Regarding the efficacy of tip projection, both nasal tip protrusion (pre 17.64 ± 4.82, post 20.46 ± 4.05, p = 0.001) and tip projection (pre 19.75 ± 4.26, post 21.83 ± 4.17, p = 0.023) were increased. The hump nose reduction ratio was 84.94% after 6 months and 76.47% after 1 year, whereas increases in nasal tip projection and dorsal augmentation were minimal, with ratios of 14.75% and 12.76%, respectively, after 6 months).

CONCLUSION

Therefore, creating a balance between the nasal tip and nasal dorsum in hump nose correction is more important than dorsal augmentation after hump resection in Asians.

Medial Osteoectomy as a Routine Procedure in Rhinoplasty: Six-Year Experience with an Innovative Technique

BACKGROUND

Medial osteotomy is an integral part of most rhinoplasty procedures, and when improperly performed, it is associated with postoperative complications and nasal contour deformities. In this article, we present a minimally traumatic and easy-to-perform medial osteoectomy technique with a pair of pliers, as a routine procedure, instead of the traditional medial osteotomy with osteotome and hammer. We report our experience with the use of the technique in a series of rhinoplasty procedures and review in brief the existing literature.

METHODS

One hundred and thirty-five patients underwent rhinoplasty operations to correct aesthetic nose deformities, with the use of the suggested surgical technique. Two different types of medial osteoectomy, performed with the pliers, were used: Type I for dorsal nasal hump reduction and slight narrowing of the nose and type II for the management of a wide nasal dorsum along with or without hump removal.

RESULTS

Postoperative results were favorable, by both clinical examination and comparison of preoperative and postoperative photographs, in 98.5% of patients. Only two patients with wide nasal dorsums had inadequate narrowing of their broad nose and underwent successful revision surgery.

CONCLUSIONS

The suggested technique is easy to perform, has a short learning curve, provides high accuracy over the location and amount of the nasal bone to be removed, but inflicts minimal trauma. As a result of the aforementioned advantages, the risk of postoperative complications is low, and most importantly, reliable, consistent, and aesthetically pleasing results are easily ensured.

LEVEL OF EVIDENCE IV

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