Augmented reality in the operating room: a clinical feasibility study.

BACKGROUND: Augmented Reality (AR) is a rapidly emerging technology finding growing acceptance and application in different fields of surgery. Various studies have been performed evaluating the precision and accuracy of AR guided navigation. This study investigates the feasibility of a commercially available AR head mounted device during orthopedic surgery. METHODS: Thirteen orthopedic surgeons from a Swiss university clinic performed 25 orthopedic surgical procedures wearing a holographic AR headset (HoloLens, Microsoft, Redmond, WA, USA) providing complementary three-dimensional, patient specific anatomic information. The surgeon's experience of using the device during surgery was recorded using a standardized 58-item questionnaire grading different aspects on a 100-point scale with anchor statements. RESULTS: Surgeons were generally satisfied with image quality (85 ± 17 points) and accuracy of the virtual objects (84 ± 19 point). Wearing the AR device was rated as fairly comfortable (79 ± 13 points). Functionality of voice commands (68 ± 20 points) and gestures (66 ± 20 points) provided less favorable results. The greatest potential in the use of the AR device was found for surgical correction of deformities (87 ± 15 points). Overall, surgeons were satisfied with the application of this novel technology (78 ± 20 points) and future access to it was demanded (75 ± 22 points). CONCLUSION: AR is a rapidly evolving technology with large potential in different surgical settings, offering the opportunity to provide a compact, low cost alternative requiring a minimum of infrastructure compared to conventional navigation systems. While surgeons where generally satisfied with image quality of the here tested head mounted AR device, some technical and ergonomic shortcomings were pointed out. This study serves as a proof of concept for the use of an AR head mounted device in a real-world sterile setting in orthopedic surgery.

Validation of a Virtual Reality-Based Hip Arthroscopy Simulator.

PURPOSE: To assess construct and face validity of a novel virtual reality-based hip arthroscopy simulator using the previously validated Arthroscopic Surgery Skills Evaluation Tool (ASSET), metric parameters, and a questionnaire. METHODS: Metric parameters including task completion time, camera path, and grasper path were recorded, and the ASSET score was used to assess construct validity. Face validity was evaluated using a questionnaire. RESULTS: Nine hip arthroscopy experts, of whom the majority performed more than 200 procedures (age, 48 ± 7.3; range, 38-61 years; 8 men, 1 woman), and 33 nonexperts (age, 33 ± 7.9; range, 26-62 years; 25 men, 8 women) performed 3 individual tasks on a virtual reality-based arthroscopy simulator of a left hip. The ASSET global rating scale showed a statistically significant difference between the hip arthroscopy expert and the nonexpert group, indicating strong construct validity (25.0 in the expert group, range, 17-34, versus 15.30 in the nonexpert group, range, 8-30 [P < .001], respectively). This also applied to most metric parameters recorded by the simulator. The simulator also demonstrated high face validity. The overall impression in terms of realism was graded "completely realistic" by 17% and "close to realistic" by 62% of participants. CONCLUSIONS: The tested simulator demonstrated high construct and face validity. CLINICAL RELEVANCE: This study demonstrates the construct and face validity of a novel hip arthroscopy simulator. The device proved to be an adequate model for the simulation of some arthroscopic procedures of the hip.

Efficacy of standardized training on a virtual reality simulator to advance knee and shoulder arthroscopic motor skills.

BACKGROUND: Most studies demonstrated, that training on a virtual reality based arthroscopy simulator leads to an improvement of technical skills in orthopaedic surgery. However, how long and what kind of training is optimal for young residents is unknown. In this study we tested the efficacy of a standardized, competency based training protocol on a validated virtual reality based knee- and shoulder arthroscopy simulator. METHODS: Twenty residents and five experts in arthroscopy were included. All participants performed a test including knee -and shoulder arthroscopy tasks on a virtual reality knee- and shoulder arthroscopy simulator. The residents had to complete a competency based training program. Thereafter, the previously completed test was retaken. We evaluated the metric data of the simulator using a z-score and the Arthroscopic Surgery Skill Evaluation Tool (ASSET) to assess training effects in residents and performance levels in experts. RESULTS: The residents significantly improved from pre- to post training in the overall z-score: - 9.82 (range, - 20.35 to - 1.64) to - 2.61 (range, - 6.25 to 1.5); p < 0.001. The overall ASSET score improved from 55 (27 to 84) percent to 75 (48 to 92) percent; p < 0.001. The experts, however, achieved a significantly higher z-score in the shoulder tasks (p < 0.001 and a statistically insignificantly higher z-score in the knee tasks with a p = 0.921. The experts mean overall ASSET score (knee and shoulder) was significantly higher in the therapeutic tasks (p < 0.001) compared to the residents post training result. CONCLUSIONS: The use of a competency based simulator training with this specific device for 3-5 h is an effective tool to advance basic arthroscopic skills of resident in training from 0 to 5 years based on simulator measures and simulator based ASSET testing. Therefore, we conclude that this sort of training method appears useful to learn the handling of the camera, basic anatomy and the triangulation with instruments.

Total knee arthroplasty in patients with a history of illicit intravenous drug abuse.

PURPOSE: Injection drug users are at high risk for both infection with blood-borne pathogens, namely, human immune deficiency virus (HIV), hepatitis-B, -C virus, various bacterial infections, as well as early primary and secondary joint degeneration. When total knee arthroplasty (TKA) is anticipated the risk of septic complications is a major concern. The purpose of this study was to assess the clinical and radiographic outcome of patients with a history of intravenous drug use after total knee arthroplasty. The primary outcome was revision rate. Secondary outcomes were the Western Ontario and McMaster Universities Arthritis Index (WOMAC), Knee Society Score (KSS) and radiographic loosening. METHODS: We retrospectively reviewed the records of 1,692 TKA performed or revised in our institution. Data of 18 TKA in 12 patients (11 male, 1 female; average age 42, range 23-62 years) with a history of intravenous opioid abuse were available for final analysis. RESULTS: The mean follow up was 125 (range 25-238) months. Seven patients required revision surgery due to periprosthetic joint infection after 62 months (range 5-159): one two staged revision, three arthrodesis and three amputations. The median prosthesis survival was 101 (95%-CI 48-154) months. CONCLUSION: Total knee arthroplasty in patients with a history of intravenous drug abuse is associated with major complications, including above-the-knee amputation. If permanent abstinence from intravenous drug abuse is doubtful, other therapeutic options including primary arthrodesis should be considered.

Postoperative alignment of TKA in patients with severe preoperative varus or valgus deformity: is there a difference between surgical techniques?

BACKGROUND: There have been conflicting studies published regarding the ability of various total knee arthroplasty (TKA) techniques to correct preoperative deformity. The purpose of this study was to compare the postoperative radiographic alignment in patients with severe preoperative coronal deformity (≥10° varus/valgus) who underwent three different TKA techniques; manual instrumentation (MAN), computer navigated instrumentation (NAV) and patient specific instrumentation (PSI). METHODS: Patients, who received a TKA with a preoperative coronal deformity of ≥10° with available radiographs were included in this retrospective study. The groups were: MAN; n = 54, NAV; n = 52 and PSI; n = 53. The mechanical axis (varus / valgus) and the posterior tibial slope were measured and analysed using standing long leg- and lateral radiographs. RESULTS: The overall mean postoperative varus / valgus deformity was 2.8° (range, 0 to 9.9; SD 2.3) and 2.5° (range, 0 to 14.7; SD 2.3), respectively. The overall outliers (>3°) represented 30.2% (48 /159) of cases and were distributed as followed: MAN group: 31.5%, NAV group: 34.6%, PSI group: 24.4%. No significant statistical differences were found between these groups. The distribution of the severe outliers (>5°) was 14.8% in the MAN group, 23% in the NAV group and 5.6% in the PSI group. The PSI group had significantly (p = 0.0108) fewer severe outliers compared to the NAV group while all other pairs were not statistically significant. CONCLUSIONS: In severe varus / valgus deformity the three surgical techniques demonstrated similar postoperative radiographic alignment. However, in reducing severe outliers (> 5°) and in achieving the planned posterior tibial slope the PSI technique for TKA may be superior to computer navigation and the conventional technique. Further prospective studies are needed to determine which technique is the best regarding reducing outliers in patients with severe preoperative coronal deformity.

Multidisciplinary and Coordinated Management of Osteoporotic Vertebral Compression Fractures: Current State of the Art.

Osteoporotic vertebral compression fractures (OVCFs) present a significant health concern, affecting a substantial portion of the older adult population worldwide. This narrative review explores the prevalence, diagnostic challenges and management strategies for OVCFs. Despite the increasing incidence and impact on morbidity and mortality, existing clinical guidelines lack consistency and clear diagnostic and therapeutic recommendations. The review addresses key questions faced by physicians dealing with older adult patients experiencing acute back pain, offering insights into triage, radiological assessments and classification systems. We propose a comprehensive algorithm for clearing OVCF, considering clinical presentation, radiological findings and morphological aspects. Emphasis is placed on the importance of medically treating osteoporosis alongside OVCF management. The review encompasses relevant literature from 1993 to 2023, provides a detailed discussion on triage issues and incorporates a clinically oriented classification system developed by the German Society for Orthopaedics and Trauma. The Material and Methods section outlines the extensive literature search carried out in PUBMED, encompassing clinical and experimental studies, systematic reviews and meta-analyses. The articles retained focused mainly on answering critical questions regarding radiological assessments, imaging modalities and the presence of a specific classification system for OVCFs. The review emphasises that the evaluation and management of OVCFs necessitates a multidisciplinary approach involving spine specialists and bone disease experts. It also addresses the role of conservative versus surgical treatments, with a focus on percutaneous vertebral augmentation. The conclusion summarises the algorithm derived for use in emergency departments and general practice, aiming to streamline OVCF management, reduce unnecessary examinations and ensure optimal patient care. The algorithm recommends primary diagnosis using computed tomography, with magnetic resonance imaging reserved for specific cases. The review advocates a holistic approach, integrating medical and surgical interventions to address the complex challenges posed by OVCFs in ageing populations.

Long-term outcome of patients with adolescent idiopathic scoliosis seeking nonoperative treatment after a mean follow-up of 42 years.

PURPOSE: Adolescent idiopathic scoliosis (AIS) affects up to 3% of otherwise healthy adolescents. The extreme long-term outcomes of nonoperative treatment are underreported. This study aimed to investigate the long-term outcome of nonoperative-treated AIS patients. Comparison between a bracing and an observation approach were performed. METHODS: In a retrospective cohort study, 20 nonoperatively treated AIS patients were observed concerning patient-related outcome measures (PROM) (visual analog scale (VAS), Short Form Health Survey 36 item (SF 36), Scoliosis Research Society (SRS 24), Oswestry Low Back Pain Disability Index (ODI), Psychological General Well-Being Index (PGWBI)), radiological curve progression and health-related quality of life (HRQoL). Baseline characteristics and radiological imaging were collected. At follow-up, anteroposterior and lateral X-rays as well as questionnaires were analyzed. RESULTS: Twenty patients (16 females, mean age: 14.6 ± 3.2 years) with a follow-up time of 42 ± 9 years were included. Nine patients (initial Cobb 35° ± 19°) were treated with bracing for a mean time of 26 ± 9 months, while the other 11 patients (initial Cobb 29° ± 11°) were observed. The primary curve progressed from 32° ± 15° to 52° ± 25° in average with no significant difference between the cohorts (p = 0.371). At final follow-up, a mean ODI score of 7 ± 7.9 points with no difference depending on the treatment (p = 0.668) was seen. No significant differences were observed for PROMs. Curve magnitude correlated neither at diagnosis (p = 0.617) nor at follow-up (p = 0.535) with the ODI score at final follow-up. CONCLUSION: After a mean of 42 years, patients with nonoperative treatment of moderate AIS demonstrated a good clinical outcome despite progression of the deformity. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Occult infection in pseudarthrosis revision after spinal fusion.

BACKGROUND CONTEXT: Pseudarthrosis after attempted spinal fusion is yet not sufficiently understood and presents a surgical challenge. Occult infections are sometimes observed in patients with pseudarthrosis and no inflammatory signs of infection. The prevalence of such occult infection and its association with patient demographics and inflammatory markers are largely unknown. PURPOSE: To determine the prevalence of unexpected low-grade infection in spinal pseudarthrosis revision surgery, and to evaluate whether such infection is associated with patient demographics and inflammatory markers. STUDY DESIGN: Retrospective observational study. PATIENT SAMPLE: One-hundred-and-twenty-eight patients who underwent thoracolumbar revision surgery due to presumed aseptic pseudarthrosis after spinal instrumentation. OUTCOME MEASURES: Culture-positive infections or noninfectious pseudarthrosis. METHODS: Samples were routinely taken for microbiological examination from all adults (n=152) who underwent revision surgery for presumed aseptic thoracolumbar pseudarthrosis between 2014 and 2019. A full intraoperative microbiological workup (at least three intraoperative tissue samples) was done for 128 (84%) patients, and these patients were included in further analyses. Patient characteristics, medical history, inflammatory markers, and perioperative data were compared between those with and without microbiologically-confirmed infection based on samples obtained during pseudarthrosis revision. RESULTS: The microbiological workup confirmed infection in 13 of 128 cases (10.2%). The predominant pathogen was Cutibacterium acnes (46.2%), followed by coagulase-negative staphylococci (38.5%). The presence of infection was associated with the body mass index (30.9±4.7 kg/m2 [infected] vs. 28.2±5.6 kg/m2 [controls], p=.049), surgery in the thoracolumbar region (46% vs. 18%, p=.019), and a slightly higher serum C-reactive protein level on admission (9.4±8.0 mg/L vs. 5.7±7.1 mg/L, p=.031). Occult infection was not associated with age, sex, prior lumbar surgeries, number of fused lumbar levels, American Society of Anesthesiologist score, Charlson Comorbidity Index, presence of diabetes mellitus, and smoking status. CONCLUSIONS: Occult infections were found in 10% of patients undergoing pseudarthrosis revision after spinal fusion, even without preoperative clinical suspicion. Occult infection was associated with higher body mass index, fusions including the thoracolumbar junction, and slightly higher C-reactive protein levels. Intraoperative microbiological samples should be routinely obtained to exclude or identify occult infection in all revision surgeries for symptomatic pseudarthrosis of the spine, as this information can be used to guide postoperative antibiotic treatment.

HoloYolo: A proof-of-concept study for marker-less surgical navigation of spinal rod implants with augmented reality and on-device machine learning.

BACKGROUND: Existing surgical navigation approaches of the rod bending procedure in spinal fusion rely on optical tracking systems that determine the location of placed pedicle screws using a hand-held marker. METHODS: We propose a novel, marker-less surgical navigation proof-of-concept to bending rod implants. Our method combines augmented reality with on-device machine learning to generate and display a virtual template of the optimal rod shape without touching the instrumented anatomy. Performance was evaluated on lumbosacral spine phantoms against a pointer-based navigation benchmark approach and ground truth data obtained from computed tomography. RESULTS: Our method achieved a mean error of 1.83 ± 1.10 mm compared to 1.87 ± 1.31 mm measured in the marker-based approach, while only requiring 21.33 ± 8.80 s as opposed to 36.65 ± 7.49 s attained by the pointer-based method. CONCLUSION: Our results suggests that the combination of augmented reality and machine learning has the potential to replace conventional pointer-based navigation in the future.

Disproportionate Case Reduction After Ban of Elective Surgeries During the SARS-CoV-2 Pandemic.

STUDY DESIGN: This is a retrospective case analysis. OBJECTIVE: The objective of this study was to illustrate the numerical effects of regulatory restrictions of elective surgery at an orthopaedic university hospital. SUMMARY OF BACKGROUND DATA: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic all over the world places extraordinary demands on health care systems which are forced to ensure structural and personnel capacities. Consequently, hospitals may only perform urgent interventions. Spine patients, however, often need urgent surgery and, moreover, bear an above-average perioperative risk frequently requiring postoperative surveillance on intensive care units (ICUs). Facing this dilemma, we want to share our practice and its unexpected numerical effects. METHODS: We compare case statistics during normal operation, directly before and after implementation of regulatory measures. We also analyzed the differences in ICU utilization, complexity and duration of interventions and the patient population. RESULTS: Spine surgical interventions have been reduced by 42.7%. Regulatory restriction of "elective surgeries" in pandemic situations results in reduced ICU utilization, however in a disproportionate manner. Although other specialized surgeries can be reduced by 59%, surgical spine cases are only diminishable by 24%. The spine surgery-related ICU occupancy has been reduced by 35%. CONCLUSION: The disproportionate effect of case reduction needs to be considered while calculating resources released by regulatory limitation of "elective surgeries" on a (inter-)national level.

Long-Term Outcomes of Pectoralis Major Transfer for the Treatment of Irreparable Subscapularis Tears: Results After a Mean Follow-up of 20 Years.

BACKGROUND: One recognized salvage option in the treatment of an irreparable subscapularis tear is the pectoralis major tendon transfer (PMT). We aimed to analyze the long-term clinical and imaging outcome of PMT for irreparable subscapularis deficiency. METHODS: Twenty-eight consecutive patients representing 30 shoulders underwent PMT at a mean age of 53.0 years (range, 35 to 67 years). At a mean of 19.7 years (range, 18 to 22 years) postoperatively, 24 shoulders (80%) were clinically examined and 21 were radiographically and sonographically assessed. The long-term results were compared with preoperative findings and previously published short-term results. RESULTS: The mean relative Constant score (percentage of age and sex-matched normal scores; CS%) and the Subjective Shoulder Value (SSV) both improved significantly from preoperatively (CS%, 47%, and SSV, 22%) to postoperatively (CS%, 77%, and SSV, 71%; p < 0.001 for both). All patients rated their results as good or excellent. Active anterior elevation was improved from preoperatively (120°) to postoperatively (131°), but the difference was not significant. Active internal and external rotation decreased significantly from the short-term (32-month) follow-up to the time of the latest follow-up (p = 0.005 and p = 0.002, respectively); however, internal rotation remained at 6 points compared with the 8 points recorded at short-term follow-up and external rotation decreased only from a mean of 51° to 39°. Loss of active range of motion was not observed subjectively and was not subjectively limiting, represented by the high ultimate SSV and overall satisfaction. Four shoulders (19%) showed evidence of glenohumeral arthropathy (Samilson and Prieto grade 3), but clinically were mildly symptomatic to asymptomatic at the time of the latest follow-up (CS% range, 67% to 88%; SSV range, 70% to 80%). Rupture of the PMT was sonographically identified in 2 patients (10%) and was associated with radiographic evidence of advanced cuff tear arthropathy (Hamada stages ≥4). Six (20%) of the initial 30 shoulders were revised, and 1 (4%) of the 24 shoulders that were clinically examined underwent reverse total shoulder arthroplasty. CONCLUSIONS: At long-term follow-up, PMT for isolated and combined subscapularis tears is associated with good to excellent clinical results. Although one-third of the shoulders developed mildly symptomatic or asymptomatic osteoarthritis, the need for salvage with use of reverse total shoulder arthroplasty was rare. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Risk factors for perioperative morbidity in spine surgeries of different complexities: a multivariate analysis of 1,009 consecutive patients.

BACKGROUND CONTEXT: There is a broad spectrum of complications during or after surgical procedures, with differing incidences reported in the published literature. Heterogeneity can be explained by the lack of an established evidence-based classification system for documentation and classification of complications in a standardized manner. PURPOSE: The objective of this study was to identify predictive risk factors for perioperative and early postoperative morbidities in spine surgeries of different complexities in a large cohort of consecutive patients. STUDY DESIGN: This study is a retrospective case series. OUTCOME MEASURES: The outcome measures are the occurrence of perioperative and early postoperative morbidities. METHODS: A classification of surgical complexity (Grades I-III) was created and applied to 1,009 patients who consecutively underwent spine surgery at a single university hospital. The incidence and the type of perioperative and early postoperative morbidities were documented. Multivariate binary logistic regression analyzed risk factors for (1) hospital stay of ≥10 days, (2) intermediate care unit (IMC) stay of ≥24 hours, (3) blood loss of >500 mL, and occurrence of a (4) surgical or (5) medical morbidity. RESULTS: A deviation from the regular postoperative course (defined as "morbidity") included surgical reasons, such as relapse of symptoms of any kind (3.3%), wound healing problems (2.4%), implant-associated complications (1.6%), postoperative neurologic deficits (1.5%), infection (1.5%), fracture (0.8%), and dural tear in need of revision (0.6%). Medical reasons included anemia (1.8%), symptomatic electrolyte derailment (1.0%), and cardiac complications (0.7%), among others. An independent risk factor associated with a surgical reason for an irregular postoperative course was male gender. Risk factors associated with a medical reason for an irregular postoperative course were identified as preoperatively high creatinine levels, higher blood loss, and systemic steroid use. Independent risk factors for a prolonged hospitalization were preoperatively high C-reactive protein level, prolonged postoperative IMC stay, and revision surgery. Spinal stabilization or fusion surgery, particularly if involving the lumbosacral spine, age, and length of surgery were associated with blood loss of >500 mL. Higher surgical complexity, involvement of the pelvis in instrumentation, American Society of Anesthesiologists Grade ≥III, and preoperatively higher creatinine levels were associated with a postoperative IMC stay of >24 hours. CONCLUSIONS: The present study confirms several modifiable and non-modifiable risk factors for perioperative and early postoperative morbidities in spine surgery, among which surgical factors (such as complexity, revision surgery, and instrumentation, including the pelvis) play a crucial role. A classification of surgical complexity is proposed and validated.