Artificial Intelligence Based Hierarchical Clustering of Patient Types and Intervention Categories in Adult Spinal Deformity Surgery: Towards a New Classification Scheme that Predicts Quality and Value.

STUDY DESIGN: Retrospective review of prospectively-collected, multicenter adult spinal deformity (ASD) databases. OBJECTIVE: To apply artificial intelligence (AI)-based hierarchical clustering as a step toward a classification scheme that optimizes overall quality, value, and safety for ASD surgery. SUMMARY OF BACKGROUND DATA: Prior ASD classifications have focused on radiographic parameters associated with patient reported outcomes. Recent work suggests there are many other impactful preoperative data points. However, the ability to segregate patient patterns manually based on hundreds of data points is beyond practical application for surgeons. Unsupervised machine-based clustering of patient types alongside surgical options may simplify analysis of ASD patient types, procedures, and outcomes. METHODS: Two prospective cohorts were queried for surgical ASD patients with baseline, 1-year, and 2-year SRS-22/Oswestry Disability Index/SF-36v2 data. Two dendrograms were fitted, one with surgical features and one with patient characteristics. Both were built with Ward distances and optimized with the gap method. For each possible n patient cluster by m surgery, normalized 2-year improvement and major complication rates were computed. RESULTS: Five hundred-seventy patients were included. Three optimal patient types were identified: young with coronal plane deformity (YC, n = 195), older with prior spine surgeries (ORev, n = 157), and older without prior spine surgeries (OPrim, n = 218). Osteotomy type, instrumentation and interbody fusion were combined to define four surgical clusters. The intersection of patient-based and surgery-based clusters yielded 12 subgroups, with major complication rates ranging from 0% to 51.8% and 2-year normalized improvement ranging from -0.1% for SF36v2 MCS in cluster [1,3] to 100.2% for SRS self-image score in cluster [2,1]. CONCLUSION: Unsupervised hierarchical clustering can identify data patterns that may augment preoperative decision-making through construction of a 2-year risk-benefit grid. In addition to creating a novel AI-based ASD classification, pattern identification may facilitate treatment optimization by educating surgeons on which treatment patterns yield optimal improvement with lowest risk. LEVEL OF EVIDENCE: 4.

Craniofacial Approaches to Pediatric Orbital Tumors.

Primary pediatric orbital tumors requiring surgery are uncommon and often require multidisciplinary management. Commonly used surgical approaches to the orbit include transconjunctival, transcutaneous (eyelid), transcranial, or extracranial osteotomies. This paper reviews a 10-year experience of cases that required a transcranial or extracranial surgical approach at the Birmingham Children's Hospital. A total of 9 patients were identified between the years 2008 to 2017. Pathologies included rhabdomyosarcoma, juvenile ossifying fibroma, optic nerve glioma, and retinoblastoma. Surgical approaches to the orbit included supraorbital bar osteotomy (transcranial) or lateral orbitotomy (extracranial). Surgical team members included neurosurgery, craniofacial surgery, and ophthalmology. This study aims to review the role of surgery in management as well as the specific indications for performing transcranial or extracranial osteotomies. It also highlights the excellent access achieved with the use of these osteotomies in certain cases, especially when compared with transconjunctival or transcutaneous approaches.

Adult cervical deformity: radiographic and osteotomy classifications.

Cervical spine deformity represents a broad spectrum of pathologies that are both complex in etiology and debilitating towards quality of life for patients. Despite advances in the understanding of drivers and outcomes of cervical spine deformity, only one classification system and one system of nomenclature for osteotomy techniques currently exist. Moreover, there is a lack of standardization regarding the indications for each technique. This article reviews the adult cervical deformity (ACD) and current classification and nomenclature for osteotomy techniques, highlighting the need for further work to develop a unified approach for each case and improve communication amongst the spine community with respect to ACD.

En bloc resection of pelvic sarcomas with sacral invasion: a classification of surgical approaches and outcomes.

Aims: The sacrum is frequently invaded by a pelvic tumour. The aim of this study was to review our experience of treating this group of patients and to identify the feasibility of a new surgical classification in the management of these tumours. Patients and Methods: We reviewed 141 patients who, between 2005 and 2014, had undergone surgical excision of a pelvic tumour with invasion of the sacrum. In a new classification, pelvisacral (Ps) I, II, and III resections refer to a sagittal osteotomy through the ipsilateral wing of the sacrum, through the sacral midline, or lateral to the contralateral sacral foramina, respectively. A Ps a resection describes a pelvic osteotomy through the ilium and a Ps b resection describes a concurrent resection of the acetabulum with osteotomies performed through the pubis and ischium or the pubic symphysis. Within each type, surgical approaches were standardized to guide resection of the tumour. Results: The mean operating time was 5.2 hours (sd 1.7) and the mean intraoperative blood loss was 1895 ml (sd 1070). Adequate margins were achieved in 112 (79.4%) of 141 patients. Nonetheless, 30 patients (21.3%) had local recurrence. The mean Musculoskeletal Tumor Society (MSTS93) lower-limb function score was 68% (sd 19; 17 to 100). According to the proposed classification, 92 patients (65%) underwent a Ps I resection, 33 patients (23%) a Ps II resection, and 16 (11%) patients a Ps III resection. Overall, 82 (58%) patients underwent a Ps a resection and 59 (42%) patient a Ps b resections. The new classification predicted surgical outcome. Conclusion: We propose a comprehensive classification of surgical approaches for tumours of the pelvis with sacral invasion. Analysis showed that this classification helped in the surgical management of such patients and had predictive value for surgical outcomes. Cite this article: Bone Joint J 2018;100-B:798-805.

Youngswick-Austin versus distal oblique osteotomy for the treatment of Hallux Rigidus.

BACKGROUND: Hallux Rigidus is the most common degenerative joint pathology of the foot. Several procedures are described for the management of this deformity. In this prospective study we compared Youngswick-Austin and distal oblique osteotomy in the treatment of grade II Hallux Rigidus, in terms of clinical outcomes, efficacy and complications. MATERIAL AND METHODS: Forty-six patients (50 feet) with moderate Hallux Rigidus (Regnauld grade II) were recruited and operated between March 2009 and December 2012. Surgical technique was Youngswick-Austin osteotomy (Group A) or distal oblique osteotomy (Group B). RESULTS: Mean follow-up was 42.7 ±12.2 (range, 24-70) months. Both groups achieved significant improvement of AOFAS score and first metatarsophalangeal joint range of motion (p value <.05). The mean AOFAS score improved from a preoperative score of 44.1 ±11.8 to 89.2 ± 9.4 (24 months) in Group A and from 40.9 ±11.3 to 89.5 ±7.2 (24 months) in Group B. At 24 months, the average improvement of first metatarsophalangeal joint range of motion was 20.9° in Group A and 22.4° in Group B. The postoperative AOFAS score and joint range of motion were comparable in both groups. DISCUSSION: For this specific patient population Youngswick-Austin and distal oblique osteotomies provides subjective patient improvement and increases the first metatarsophalangeal joint range of motion. The results of grade II Hallux Rigidus treatment were comparable when using a Youngswick-Austin or distal oblique osteotomy. LEVEL OF EVIDENCE: Level II, prospective comparative study.

The prevention of a lateral hinge fracture as a complication of a medial opening wedge high tibial osteotomy: a case control study.

AIMS: We aimed to investigate factors related to the technique of medial opening wedge high tibial osteotomy which might predispose to the development of a lateral hinge fracture. PATIENTS AND METHODS: A total of 71 patients with 82 osteotomies were included in the study. Their mean age was 62.9 years (37 to 80). The classification of the type of osteotomy was based on whether it extended beyond the fibular head. The level of the osteotomy was classified according to the height of its endpoint. RESULTS: At a mean follow-up of 20 months (6 to 52), a total of 15 lateral hinge fractures (18.3%) were identified. A sufficient osteotomy, in which both anterior and posterior tibial cortices were involved with extension into the lateral aspect of the plateau in relation to an anteroposterior line tangential to the medial edge of the fibular head in the CT axial plane, was seen in 48 knees (71.6%) in those without a lateral hinge fracture and in seven (46.7%) in those with a lateral hinge fracture. An osteotomy which ended above the level of the fibular head was seen in nine (13.4%) of the knees without a lateral hinge fracture and seven (46.7%) of the those with a lateral hinge fracture. There was a significant relationship between the absence of a lateral hinge fracture and both a sufficient osteotomy and one whose endpoint was at the level of the fibular head (p = 0.0451 and p = 0.0214, respectively). CONCLUSION: A sufficient osteotomy involving both the anterior and posterior cortices, whose endpoint is at the level of the fibular head, should be performed when undertaking a medial opening wedge high tibial osteotomy if a lateral hinge fracture is to be avoided as a complication. Cite this article: Bone Joint J 2017;99-B:887-93.

Comparison of the Modified McBride Procedure and the Distal Chevron Osteotomy for Mild to Moderate Hallux Valgus.

Distal metatarsal osteotomy and the modified McBride procedure have each been used for the treatment of mild to moderate hallux valgus. However, few studies have compared the results of these 2 procedures for mild to moderate hallux valgus. The purpose of the present study was to compare the results of distal chevron osteotomy and the modified McBride procedure for treatment of mild to moderate hallux valgus according to the severity of the deformity. We analyzed the data from 45 patients (49.5%; 48 feet [49.0%]), who had undergone an isolated modified McBride procedure (McBride group), and 46 patients (50.5%; 50 feet [51.0%]), who had a distal chevron osteotomy (chevron group). We subdivided each group into those with mild and moderate deformity and compared the clinical and radiologic outcomes between the groups in relation to the severity of the deformity. The improvements in the American Orthopaedic Foot and Ankle Society scale score and the visual analog scale for pain were significantly better for the chevron group for both mild and moderate deformity. The chevron group experienced significantly greater correction in the hallux valgus angle and intermetatarsal angle for both mild and moderate deformity. The chevron group experienced a significantly greater decrease in the grade of sesamoid displacement for patients with moderate deformity. The McBride group had a greater risk of recurrence than did the chevron group for moderate deformity (odds ratio 14.00, 95% confidence interval 3.91 to 50.06, p < .001). The results of the present study have demonstrated the superiority of the distal chevron osteotomy over the modified McBride procedure for mild to moderate deformity. For patients with moderate deformity, the McBride group had a greater risk of hallux valgus recurrence than did the distal chevron group. Therefore, we recommend distal chevron osteotomy rather than a modified McBride procedure for the treatment of mild and moderate hallux valgus.

The Mau-Reverdin Osteotomy: A Short-Term Retrospective Analysis.

We reviewed 33 consecutive Mau-Reverdin osteotomies in 23 patients performed for correction of hallux abducto valgus from November 2010 to May 2013. All patients were followed up and evaluated for a mean of 401 days and median of 360 days after surgery. In each foot, the preoperative first intermetatarsal angle, hallux abductus angle, and proximal articular set angle were obtained. The mean correction of these angles was as follows: intermetatarsal angle 10.5° ± 3.31°, hallux abductus angle 24.4° ± 8.8°, and proximal articular set angle 28.39° ± 11.2°. Furthermore, we evaluated for metatarsus elevates, and no statistically significant first metatarsal elevation was present in any of the 33 feet (p < .0001). Additionally, 21 of the 33 feet (63.6%) were available for first metatarsophalangeal joint American Orthopaedic Foot and Ankle Society scale score evaluation. The mean preoperative score was 25.5 ± 16.7. After correction, the mean American Orthopaedic Foot and Ankle Society scale score had increased to 95.4 ± 5.7. All these differences were statistically significant (p < .0001), and the patients had a very high level of satisfaction. In all 33 feet, no deep infection, malunion, nonunion, avascular necrosis of the first metatarsal, or hardware failure developed. One patient developed hallux varus deformity. The Mau-Reverdin osteotomy is a very effective and reproducible procedure that successfully corrects large bunion deformities and provides patients with a high level of satisfaction and a low complication rate.

A Comparison between Osteotomy and Corticotomy-Assisted Tooth Movement.

Osteotomies and corticotomies used in combination with orthodontic tooth movement can activate different bone responses that may be exploited to accelerate tooth movement. Segmental osteotomies around dental roots can create a tooth-bearing transport disk that may be distracted and positioned with orthodontic appliances and archwires. In difficult craniofacial repairs, alveolar segments can be guided into position with archwires and orthodontic mechanics. The corticotomy extending into the marrow space can activate bone injury repair mechanisms that accelerate bone turnover as the alveolar bone surrounding the dental roots transitions from a demineralization phase to a fibrous replacement phase and, finally, a mineralization phase. The controlled demineralization and replacement of alveolar bone provides a window of opportunity for roots to move though less dense bone prior to remineralization. Although the corticotomies and osteotomies are minor surgeries compared to orthognathic surgery, the goal of future research is to produce similar bone responses by using smaller surgeries or by eliminating the surgeries altogether.

Trifactorial classification system for osteotome sinus floor elevation based on an observational retrospective analysis of 926 implants followed up to 10 years.

OBJECTIVE: A novel osteotome trifactorial classification system is proposed for transcrestal osteotome-mediated sinus floor elevation (OSFE) sites that includes residual bone height (RBH), sinus floor anatomy (contour), and multiple versus single sites OSFE (tenting). METHOD AND MATERIALS: An analysis of RBH, contour, and tenting was retrospectively applied to a cohort of 926 implants placed using OSFE without added bone graft and followed up to 10 years. RBH was divided into three groups: high (RBH > 6 mm), mid (RBH = 4.1 to 6 mm), and low (RBH = 2 to 4 mm). The sinus "contour" was divided into four groups: flat, concave, angle, and septa. For "tenting", single versus multiple adjacent OSFE sites were compared. RESULTS: The prevalence of flat sinus floors increased as RBH decreased. RBH was a significant predictor of failure with rates as follows: low- RBH = 5.1%, mid-RBH = 1.5%, and high-RBH = 0.4%. Flat sinus floors and single sites as compared to multiple sites had higher observed failure rates but neither achieved statistical significance; however, the power of the study was limited by low numbers of failures. CONCLUSION: The osteotome trifactorial classification system as proposed can assist planning OSFE cases and may allow better comparison of future OSFE studies.

The comprehensive anatomical spinal osteotomy classification.

BACKGROUND: Global sagittal malalignment is significantly correlated with health-related quality-of-life scores in the setting of spinal deformity. In order to address rigid deformity patterns, the use of spinal osteotomies has seen a substantial increase. Unfortunately, variations of established techniques and hybrid combinations of osteotomies have made comparisons of outcomes difficult. OBJECTIVE: To propose a classification system of anatomically-based spinal osteotomies and provide a common language among spine specialists. METHODS: The proposed classification system is based on 6 anatomic grades of resection (1 through 6) corresponding to the extent of bone resection and increasing degree of destabilizing potential. In addition, a surgical approach modifier is added (posterior approach or combined anterior and posterior approaches). Reliability of the classification system was evaluated by an analysis of 16 clinical cases, rated 2 times by 8 different readers, and calculation of Fleiss kappa coefficients. RESULTS: Intraobserver reliability was classified as 'almost perfect'; Fleiss kappa coefficient averaged 0.96 (range, 0.92-1.0) for resection type and 0.90 (0.71-1.0) for the approach modifier. Results from the interobserver reliability for the classification were 0.96 for resection type and 0.88 for the approach modifier. CONCLUSION: This proposed anatomically based classification system provides a consistent description of the various osteotomies performed in spinal deformity correction surgery. The reliability study confirmed that the classification is simple and consistent. Further development of its use will provide a common frame for osteotomy assessment and permit comparative analysis of different treatments.

Osteotomies in the treatment of spinal deformities: indications, classification, and surgical planning.

The surgical treatment of adult spinal deformity has been shown to offer superior clinical and radiographic outcomes compared with nonoperative approaches; furthermore, osteotomies are increasingly applied for treating spinal deformities. Establishing a plan for a patient suffering from marked spinal deformity is a matter of consideration of certain radiographic parameters which correlate with health-related quality of life scores, adherence to consistent principles of alignment and established formulas, and selecting the appropriate osteotomies. This is a review of the most recent work on vertebral osteotomies and includes a summary of a systematic and anatomically based osteotomy classification. A universal classification will facilitate communication, standardize outcomes research, and establish a framework upon which indications can be properly studied and described. Ongoing multicenter collaboration is certain to drive a more evidence-based approach to the complex clinical scenarios of patients suffering from spinal deformity.

The comprehensive anatomical spinal osteotomy classification.

BACKGROUND: Global sagittal malalignment is significantly correlated with health-related quality-of-life scores in the setting of spinal deformity. In order to address rigid deformity patterns, the use of spinal osteotomies has seen a substantial increase. Unfortunately, variations of established techniques and hybrid combinations of osteotomies have made comparisons of outcomes difficult. OBJECTIVE: To propose a classification system of anatomically-based spinal osteotomies and provide a common language among spine specialists. METHODS: The proposed classification system is based on 6 anatomic grades of resection (1 through 6) corresponding to the extent of bone resection and increasing degree of destabilizing potential. In addition, a surgical approach modifier is added (posterior approach or combined anterior and posterior approaches). Reliability of the classification system was evaluated by an analysis of 16 clinical cases, rated 2 times by 8 different readers, and calculation of Fleiss kappa coefficients. RESULTS: Intraobserver reliability was classified as "almost perfect"; Fleiss kappa coefficient averaged 0.96 (range, 0.92-1.0) for resection type and 0.90 (0.71-1.0) for the approach modifier. Results from the interobserver reliability for the classification were 0.96 for resection type and 0.88 for the approach modifier. CONCLUSION: This proposed anatomically based classification system provides a consistent description of the various osteotomies performed in spinal deformity correction surgery. The reliability study confirmed that the classification is simple and consistent. Further development of its use will provide a common frame for osteotomy assessment and permit comparative analysis of different treatments.

A standardized nomenclature for cervical spine soft-tissue release and osteotomy for deformity correction: clinical article.

OBJECT: Cervical spine osteotomies are powerful techniques to correct rigid cervical spine deformity. Many variations exist, however, and there is no current standardized system with which to describe and classify cervical osteotomies. This complicates the ability to compare outcomes across procedures and studies. The authors' objective was to establish a universal nomenclature for cervical spine osteotomies to provide a common language among spine surgeons. METHODS: A proposed nomenclature with 7 anatomical grades of increasing extent of bone/soft tissue resection and destabilization was designed. The highest grade of resection is termed the major osteotomy, and an approach modifier is used to denote the surgical approach(es), including anterior (A), posterior (P), anterior-posterior (AP), posterior-anterior (PA), anterior-posterior-anterior (APA), and posterior-anterior-posterior (PAP). For cases in which multiple grades of osteotomies were performed, the highest grade is termed the major osteotomy, and lower-grade osteotomies are termed minor osteotomies. The nomenclature was evaluated by 11 reviewers through 25 different radiographic clinical cases. The review was performed twice, separated by a minimum 1-week interval. Reliability was assessed using Fleiss kappa coefficients. RESULTS: The average intrarater reliability was classified as "almost perfect agreement" for the major osteotomy (0.89 [range 0.60-1.00]) and approach modifier (0.99 [0.95-1.00]); it was classified as "moderate agreement" for the minor osteotomy (0.73 [range 0.41-1.00]). The average interrater reliability for the 2 readings was the following: major osteotomy, 0.87 ("almost perfect agreement"); approach modifier, 0.99 ("almost perfect agreement"); and minor osteotomy, 0.55 ("moderate agreement"). Analysis of only major osteotomy plus approach modifier yielded a classification that was "almost perfect" with an average intrarater reliability of 0.90 (0.63-1.00) and an interrater reliability of 0.88 and 0.86 for the two reviews. CONCLUSIONS: The proposed cervical spine osteotomy nomenclature provides the surgeon with a simple, standard description of the various cervical osteotomies. The reliability analysis demonstrated that this system is consistent and directly applicable. Future work will evaluate the relationship between this system and health-related quality of life metrics.

Classification of maxillectomy defects: a systematic review and criteria necessary for a universal description.

STATEMENT OF PROBLEM: Maxillectomy defects are complex and involve a number of anatomic structures. Several maxillectomy defect classifications have been proposed with no universal acceptance among surgeons and prosthodontists. Established criteria for describing the maxillectomy defect are lacking. PURPOSE: This systematic review aimed to evaluate classification systems in the available literature, to provide a critical appraisal, and to identify the criteria necessary for a universal description of maxillectomy and midfacial defects. MATERIAL AND METHODS: An electronic search of the English language literature between the periods of 1974 and June 2011 was performed by using PubMed, Scopus, and Cochrane databases with predetermined inclusion criteria. Key terms included in the search were maxillectomy classification, maxillary resection classification, maxillary removal classification, maxillary reconstruction classification, midfacial defect classification, and midfacial reconstruction classification. This was supplemented by a manual search of selected journals. After application of predetermined exclusion criteria, the final list of articles was reviewed in-depth to provide a critical appraisal and identify criteria for a universal description of a maxillectomy defect. RESULTS: The electronic database search yielded 261 titles. Systematic application of inclusion and exclusion criteria resulted in identification of 14 maxillectomy and midfacial defect classification systems. From these articles, 6 different criteria were identified as necessary for a universal description of a maxillectomy defect. Multiple deficiencies were noted in each classification system. Though most articles described the superior-inferior extent of the defect, only a small number of articles described the anterior-posterior and medial-lateral extent of the defect. Few articles listed dental status and soft palate involvement when describing maxillectomy defects. CONCLUSIONS: No classification system has accurately described the maxillectomy defect, based on criteria that satisfy both surgical and prosthodontic needs. The 6 criteria identified in this systematic review for a universal description of a maxillectomy defect are: 1) dental status; 2) oroantral/nasal communication status; 3) soft palate and other contiguous structure involvement; 4) superior-inferior extent; 5) anterior-posterior extent; and 6) medial-lateral extent of the defect. A criteria-based description appears more objective and amenable for universal use than a classification-based description.

Biomechanical effects of surgical cut direction in unilateral mandibular lengthening by distraction osteogenesis using a finite element model.

Although the precise prediction of the results before distraction is important, performing three-dimensional (3D) simulations for all distraction osteogenesis patients is not practical. Formulating general guidelines based on the factors affecting the 3D results of distraction treatment is recommended. This study was performed on a 3D mandible based on a finite element method. Three surgical cuts (oblique, vertical and horizontal) were made in the right side of the mandible. The amount and direction of movement of proximal and distal segments were evaluated after simulation of 15 mm of distraction. In the distal segment, the maximum displacement in the pogonion occurred in the vertical cut. In the proximal segment, the maximum displacement occurred in the coronoid process in horizontal and oblique cuts in a superior direction. The condylar process rotated in the clockwise direction when the vertical cut was used and the coronoid process moved inferiorly. To make the gonial angle more prominent the vertical cut should be used. A horizontal cut is used to lengthen the ramus. Vertical and oblique cuts can be used in patients with long anterior facial height, but all other conditions being equal horizontal cuts are better used in short faced patients.

Osteotomies in the crooked nose.

The crooked nasal pyramid and upper third of the nose can be straightened with various osteotomes. Appropriate solutions to maximize successful nasal straightening require a thorough knowledge of the anatomy, a comprehensive preoperative plan, and the appropriate osteotomy choice.

Temporalis muscle flap for immediate reconstruction of maxillary defects: review of 39 cases.

This study evaluated the advantages and complications associated with immediate reconstruction of maxillary defects after maxillectomy and the relationship between defect tissues classification and postoperative results after using the temporalis muscle flap. In this retrospective study, the records of 39 patients who underwent immediate reconstruction surgery using temparolis myofascial flap following maxillectomy from April 1989 to February 2009 were reviewed. Demographic data, features of the disease, follow-up, outcome and complications were analysed. Patients were classified into three groups, to ascertain the influence between defect classification and functional results, aesthetic outcomes and complications in each group. Of the 39 cases, all tissue flaps survived. 5 patients underwent postoperative radiotherapy, which did not seem to influence the outcome of the reconstructive procedure. There was one case of oroantral fistula, which could easily be obturated with the prosthesis. One patient developed haematoma in the donor site 5 days after surgery. Postoperative speech was good, facial appearance was normal and ocular function remained unchanged. Postoperative aesthetic and functional results were satisfying. The temporalis muscle flap can be considered as a first-line reconstructive option for maxillary defects. Acceptable functional and aesthetic outcomes can be expected in high rates.

A nine-year review of orthognathic surgery at the University of Otago.

OBJECTIVE: To describe the demographic characteristics of patients undergoing orthognathic surgery at the University of Otago over a nine-year period. METHODS: The case notes of patients who underwent orthognathic surgery procedures at the University of Otago from 2001 to 2009 were reviewed retrospectively. This was augmented with a brief literature review of surgical considerations and complications in orthognathic surgery among older patients. RESULTS: The 92 patients included in the study were aged 15 to 56 years. The mean patient age increased over the nine-year observation period, from 22.1 years (sd, 9.4) during 2001-2003, 25.0 years (sd, 12.7) during 2004-2006, to 27.7 years (sd, 11.4) during 2007-2009. Most patients were from New Zealand European or European backgrounds, with only 5.5% identifying as Maori, and 3.3% as Asian. A female preponderance was observed (with a female:male ratio of 1.6:1). Complications were encountered with 24 patients (26.1%). Ten patients had long-term (lasting for one year or more) sensory nerve disturbance; all of those had undergone a mandibular bilateral sagittal split osteotomy (BSSO) procedure (they comprised 12.7% of all BSSO patients treated); half of those patients were over 35 years old, and four were over 40 years old. CONCLUSIONS: There has been an increase in the proportion of older patients undergoing orthognathic surgery at the University of Otago. Observations from this case series support findings from other studies demonstrating a higher rate of sensory nerve disturbance among older BSSO patients.