Surgical repair of large segmental bone loss with the induced membrane technique: patient reported outcomes are comparable to nonunions without bone loss.

OBJECTIVE: To compare the outcomes of patients with segmental bone loss who underwent repair with the induced membrane technique (IMT) with a matched cohort of nonunion fractures without bone loss. DESIGN: Retrospective analysis on prospectively collected data. SETTING: Academic medical center. PATIENTS: Two cohorts of patients, those with upper and lower extremity diaphyseal large segmental bone loss and those with ununited fractures, were enrolled prospectively between 2013 and 2020. Sixteen patients who underwent repair of 17 extremities with segmental diaphyseal or meta-diaphyseal bone defects treated with the induced membrane technique were identified, and matched with 17 patients who were treated for 17 fracture nonunions treated without an induced membrane. Sixteen of the bone defects treated with the induced membrane technique were due to acute bone loss, and the other was a chronic aseptic nonunion. MAIN OUTCOME MEASUREMENTS: Healing rate, time to union, functional outcome scores using the Short Musculoskeletal Functional Assessment (SMFA) and pain assessed by the Visual Analog Scale (VAS). RESULTS: The initial average defect size for patients treated with the induced membrane technique was 8.85 cm. Mean follow-up times were similar with 17.06 ± 10.13 months for patients treated with the IMT, and 20.35 ± 16.68. months for patients treated without the technique. Complete union was achieved in 15/17 (88.2%) of segmental bone loss cases treated with the IMT and 17/17 (100%) of cases repaired without the technique at the latest follow up visit. The average time to union for patients treated with the induced membrane technique was 13.0 ± 8.4 months and 9.64 ± 4.7 months for the matched cohort. There were no significant differences in reported outcomes measured by the SMFA or VAS. Patients treated with the induced membrane technique required more revision surgeries than those not treated with an induced membrane. CONCLUSION: Outcomes following treatment of acute bone loss from the diaphysis of long bones with the induced membrane technique produces clinical and radiographic outcomes similar to those of long bone fracture nonunions without bone loss that go on to heal. LEVEL OF EVIDENCE: III.

Ten-step minimally invasive slalom unilateral laminotomy for bilateral decompression (sULBD) with navigation.

BACKGROUND: Unilateral laminotomy for bilateral decompression (ULBD) is a MIS surgical technique that offers safe and effective decompression of lumbar spinal stenosis (LSS) with a long-term resolution of symptoms. Advantages over conventional open laminectomy include reduced expected blood loss, muscle damage, mechanical instability, and less postoperative pain. The slalom technique combined with navigation is used in multi-segmental LSS to improve the workflow and effectiveness of the procedure. METHODS: We outline ten technical steps to achieve a slalom unilateral laminotomy for bilateral decompression (sULBD) with navigation. In a retrospective case series, we included patients with multi-segmental LSS operated in our institution using the sULBD between 2020 and 2022. The primary outcome was a reduction in pain measured by Visual Analogue Scale (VAS) for back pain and leg pain and Oswestry Disability Index (ODI). RESULTS: In our case series (N = 7), all patients reported resolution of initial symptoms on an average follow-up of 20.71 ± 9 months. The average operative time and length of hospital stay were 196.14 min and 1.67 days, respectively. On average, VAS (back pain) was 4.71 pre-operatively and 1.50 on long-term follow-up of an average of 19.05 months. VAS (leg pain) decreased from 4.33 to 1.21. ODI was reported as 33% pre-operatively and 12% on long-term follow-up. CONCLUSION: The sULBD with navigation is a safe and effective MIS surgical procedure and achieves the resolution of symptoms in patients presenting with multi-segmental LSS. Herein, we demonstrate the ten key steps required to perform the sULBD technique. Compared to the standard sULBD technique, the incorporation of navigation provides anatomic localization without exposure to radiation to staff for a higher safety profile along with a fast and efficient workflow.

Microbiome of infected fracture nonunion: Does it affect outcomes?

BACKGROUND: Infected fracture nonunions often require prolonged treatment and recovery courses. It is unclear whether the bacterial microbiome influences the time to healing as well as the eradication of infection. The goals of this study are (1) to assess the bacterial microbiome affecting infected nonunions and (2) to evaluate the effects of bacterial speciation on associated outcomes. METHODS: Between 2006 and 2022, data from 551 adult patients from a single academic institution who presented with a fracture nonunion were analyzed retrospectively for infection. All patients underwent revision surgery with three sets of cultures obtained intra-operatively. Patients with significant intra-operative cultures were grouped into gram-positive and gram-negative culture cohorts. These patients were managed with a standardized protocol involving surgical debridement, nonunion site fixation, and culture-directed antibiotic treatment. Primary outcome was time to fracture union. Secondary outcomes included number of re-operations and eventual amputation or reconstructive surgery. RESULTS: 56 nonunion patients (10 %) were diagnosed with an infected nonunion (44 g-positive, 12 g-negative). Of these, 3 g-positive patients received an amputation or arthroplasty procedure prior to fracture union, and seven were lost to follow-up. There were no significant differences in age, gender, or nonunion site between cohorts. Most nonunions occurred in the lower extremity. The most common bacteria were staph species (54.3 %). 36 g-positive and 10 g-negative patients achieved fracture union. Time to union was on average 158.4 days longer in the gram-negative cohort-but did not reach statistical significance (446.8 days gram-positive, 662.3 days gram-negative, p = 0.69). There was no difference in re-operation rates (1.9 % gram-positive, 2.2 % gram-negative, p = 0.84). CONCLUSIONS: Patients with infected nonunions had wide-ranging bacterial contamination that were treated successfully using a standardized protocol. However, patients with any gram-negative culture trended toward a delay in time to union.

Patient obesity is associated with severity of proximal humerus fractures, not outcomes.

PURPOSE: The purpose of this study is to evaluate the effect of obesity on the outcome of operatively treated proximal humerus fractures. METHODS: Between December 2003 and October 2020, 240 patients with proximal humerus fractures requiring surgery were prospectively followed and classified according to the international AO/Orthopedic Trauma Association (AO/OTA) and Neer classifications. Patients' body mass indexes (BMI) were calculated and used to identify two groups, BMI ≥ 30 kg/cm (obese) and < 30 kg/cm (non-obese). Independent t tests were used for statistical analysis of continuous variables and χ2 tests for categorical variables. Regression analysis was performed to determine if BMI was a predictor of fracture pattern severity as determined by the AO/OTA classification. RESULTS: Overall, 223 patients who sustained proximal humerus fractures were analyzed. Patient age at time of injury was 60.5 ± 13.7 years. There were 67 AO/OTA 11A, 79 AO/OTA 11B, and 77 AO/OTA 11C fracture types. Seventy-two patients (32.3%) were obese. No significant differences were seen between groups in regard to demographic variables, Neer classification, or functional and clinical outcomes as determined by DASH scores and shoulder ROM, respectively. Statistical analyses confirmed that obesity is associated with more severe fracture patterns of the proximal humerus as categorized by the AO/OTA classification. An independent t test confirmed that BMI was significantly higher in the complex fracture group based on the AO/OTA classification (p = 0.047). Regression analysis also demonstrated that age (p = 0.005) and CCI (p = 0.021) were predictors of more severe fractures, while BMI approached significance (p = 0.055) based on the AO/OTA classification. CONCLUSION: A significantly higher incidence of complex proximal humerus fracture patterns is observed in patients with higher body mass indexes based on the AO/OTA classification. Age and CCI are also associated with more severe fracture patterns of the proximal humerus as determined by the AO/OTA classification. No differences were seen in outcomes or complication rates between obese patients and non-obese patients. LEVEL OF EVIDENCE: Level III.

Image-Guided Spine Surgery.

The realm of spine surgery is undergoing a transformative shift, thanks to the integration of image-guided navigation technology. This innovative system seamlessly blends real-time imaging data with precise location tracking. While the indispensable expertise of experienced spine surgeons remains irreplaceable, navigation systems bring a host of valuable advantages to the operating room. By offering a comprehensive view of the surgical anatomy, these systems empower surgeons to conduct procedures with accuracy, while minimizing radiation exposure for both patients and medical professionals. Moreover, image-guided navigation paves the way for integration of other state-of-the-art technologies, such as augmented reality and robotics. These innovations promise to further revolutionize the field, providing greater precision and expanding the horizons of what is possible in the world of spinal procedures. This article explores the evolution, classification, and impact of image-guided spine surgery, underscoring its pivotal role in enhancing efficacy and safety while setting the stage for the incorporation of future technological advancements.

Expandable cages that expand both height and lordosis provide improved immediate effect on sagittal alignment and short-term clinical outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

Background: Failure to restore lordotic alignment is not an uncommon problem following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF), even with expandable cages that increase disc height. This study aims to investigate the effect of the expandable cage that is specifically designed to expand both height and lordosis. We evaluated the outcomes of MIS TLIF in restoring immediate postoperative sagittal alignment by comparing two different types of expandable cages. One cage is designed to solely increase disc height (Group H), while the other can expand both height and lordosis (Group HL). Methods: Patients undergoing MIS TLIF using expandable cages were retrospectively reviewed, including 40 cases in Group H and 109 cases in Group HL. Visual analog scores of back and leg pain, and Oswestry disability index were collected. Disc height, disc angle, and sagittal alignment were measured. Complications were recorded, including early subsidence which was evaluated with computed tomography. Results: Clinical and radiographic outcomes significantly improved in both groups postoperatively. Group HL showed superior improvement in segmental lordosis (4.4°±3.5° vs. 2.1°±4.8°, P=0.01) and disc angle (6.3°±3.8 vs. 2.2°±4.3°, P<0.001) compared to Group H. Overall incidence of early subsidence was 23.3%, predominantly observed during initial cases as part of the learning curve, but decreased to 18% after completion of the first 20 cases. Conclusions: Expandable cages with a design specifically aimed at increasing lordotic angle can provide favorable outcomes and effectively improve immediate sagittal alignment following MIS TLIF, compared to conventional cages that only increase in height. However, regardless of the type of expandable cage used, it is crucial to avoid applying excessive force to achieve greater disc height or lordosis, as this may contribute to subsidence and a possible reduction in lordotic alignment restoration. Long-term results are needed to evaluate the clinical outcome, fusion rate, and maintenance of the sagittal alignment.

The Use of Augmented Reality as an Educational Tool in Minimally Invasive Transforaminal Lumbar Interbody Fusion.

BACKGROUND AND OBJECTIVES: One of the major challenges in training neurosurgical and orthopedic residents the technique for minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is the lack of visualization of surgical landmarks (pedicle, pars, lamina). This is due to the limited access to the bony spine through a tubular retractor, in addition to a smaller working corridor or patient-specific factors such as bony overgrowth, disk space collapse, and listhesis. These factors increase the possibility for surgical error and prolonged surgery time. With augmented reality (AR), relevant surgical anatomy can be projected directly into the user's field of view through the microscope. The purpose of this study was to assess the utility, accuracy, efficiency, and precision of AR-guided MIS-TLIF and to determine its impact in spine surgery training. METHODS: At 2 centers, 12 neurosurgical residents performed a one-level MIS-TLIF on a high-fidelity lumbar spine simulation model with and without AR projection into the microscope. For the MIS-TLIF procedures with AR, surgical landmarks were highlighted in different colors on preoperative image data. These landmarks were visualized in the spinal navigation application on the navigation monitor and in the microscope to confirm the relevant anatomy. Postprocedural surveys (National Aeronautics and Space Administration Task Load Index) were given to the residents. RESULTS: Twelve residents were included in this trial. AR-guided procedures had a consistent impact on resident anatomical orientation and workload experience. Procedures performed without AR had a significantly higher mental demand (P = .003) than with AR. Residents reported to a significantly higher rate that it was harder work for them to accomplish their level of performance without AR (P = .019). CONCLUSION: AR can bring a meaningful value in MIS teaching and training to confirm relevant anatomy in situations where the surgeon will have less direct visual access. AR used in surgical simulation can also speed the learning curve.

A Good Tip-Apex Distance Does Not Make Up For a Poor Reduction in Intertrochanteric Hip Fractures Treated with an Cephalomedullary Nail: The Utility of the Neck-Shaft Angle in Preventing Fixation Failure.

PURPOSE: Determine if any fracture characteristics or radiographic parameters were predictive of fixation failure [FF] within 1 year following cephalomedullary nailing for intertrochanteric fractures. METHODS: A consecutive series of intertrochanteric hip fracture patients (AO/OTA 31A) treated with a cephalomedullary nail were reviewed. Pre-fixation (neck-shaft angle [NSA], distance from ischial tuberosities to greater and lesser trochanters, integrity of lesser trochanter, and fracture angulation) and post-fixation (post-fixation NSA, posteromedial cortex continuity, lag screw position, tip to apex distance [TAD], and post-fixation angulation and translation) radiographic parameters were measured by blinded independent reviewers. The FF and non-FF groups were statistically compared. Logistic regression was performed to determine radiographic parameter correlates of FF. RESULTS: Of 1249 patients, 23 (1.8%) developed FF within 1 year. The FF patients were younger than their non-FF counterparts (77.2 years vs 81.0 years, p=0.048), however there were no other demographic differences. The FF cohort did not differ in frequency of TAD over 25 mm (4.3% vs 9.6%, p=0.624) and had decreased mean TAD (13.6mm vs 16.3mm, p=0.021) relative to the non-FF cohort. The FF cohort had a higher rate of a post-fixation coronal plane NSA more than 10° different from the contralateral side (delta NSA>10°, 34.8% vs 13.7%, p=0.011) with the majority fixed in relative varus. For every 1° increase in varus compared to the contralateral side the odds of FF increased 7% (OR=1.065, 95%CI[1.005-1.130], p=0.034) on univariate analysis. On univariate logistic regression, patients with an absolute post-fixation NSA of 10° or more of varus compared to contralateral were significantly more likely to have a FF (OR=3.139, 95%CI[1.067-8.332], p=0.026). CONCLUSION: Despite an acceptable TAD, post-fixation NSA in relative varus as compared to the contralateral side was significantly associated with failure in intertrochanteric hip fractures fixed with a cephalomedullary nail. LEVEL OF EVIDENCE: Prognostic Level III.

Complications in Minimally Invasive Spine Surgery in the Last 10 Years: A Narrative Review.

OBJECTIVE: Minimally invasive spine surgery (MISS) employs small incisions and advanced techniques to minimize tissue damage while achieving similar outcomes to open surgery. MISS offers benefits such as reduced blood loss, shorter hospital stays, and lower costs. This review analyzes complications associated with MISS over the last 10 years, highlighting common issues and the impact of technological advancements. METHODS: A systematic review following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines was conducted using PubMed, MEDLINE, Embase via OVID, and Cochrane databases, covering publications from January 2013 to March 2024. Keywords related to MISS and complications were used. Studies on adult patients undergoing MISS with tubular, uniportal, or biportal endoscopy, reporting intraoperative or postoperative complications, were included. Non-English publications, abstracts, and small case series were excluded. Data on MISS approach, patient demographics, and complications were extracted and reviewed by 2 independent researchers. RESULTS: The search identified 880 studies, with 137 included after screening and exclusions. Key complications in cervical MISS were hematomas, transient nerve root palsy, and dural tears. In thoracic MISS, complications included cerebrospinal fluid leaks and durotomy. In lumbar MISS, common complications were incidental dural injuries, postoperative neuropathic conditions, and disc herniation recurrences. Complications varied by surgical approach. CONCLUSION: MISS offers reduced anatomical disruption compared to open surgery, potentially decreasing nerve injury risk. However, complications such as nerve injuries, durotomies, and hardware misplacement still occur. Intraoperative neuromonitoring and advanced technologies like navigation can help mitigate these risks. Despite variability in complication rates, MISS remains a safe, effective alternative with ongoing advancements enhancing its outcomes.

Flexible support material maintains disc height and supports the formation of hydrated tissue engineered intervertebral discs in vivo.

Background: Mechanical augmentation upon implantation is essential for the long-term success of tissue-engineered intervertebral discs (TE-IVDs). Previous studies utilized stiffer materials to fabricate TE-IVD support structures. However, these materials undergo various failure modes in the mechanically challenging IVD microenvironment. FlexiFil (FPLA) is an elastomeric 3D printing filament that is amenable to the fabrication of support structures. However, no present study has evaluated the efficacy of a flexible support material to preserve disc height and support the formation of hydrated tissues in a large animal model. Methods: We leveraged results from our previously developed FE model of the minipig spine to design and test TE-IVD support cages comprised of FPLA and PLA. Specifically, we performed indentation to assess implant mechanical response and scanning electron microscopy to visualize microscale damage. We then implanted FPLA and PLA support cages for 6 weeks in the minipig cervical spine and monitored disc height via weekly x-rays. TE-IVDs cultured in FPLA were also implanted for 6 weeks with weekly x-rays and terminal T2 MRIs to quantify tissue hydration at study endpoint. Results: Results demonstrated that FPLA cages withstood nearly twice the deformation of PLA without detrimental changes in mechanical performance and minimal damage. In vivo, FPLA cages and stably implanted TE-IVDs restored native disc height and supported the formation of hydrated tissues in the minipig spine. Displaced TE-IVDs yielded disc heights that were superior to PLA or discectomy-treated levels. Conclusions: FPLA holds great promise as a flexible and bioresorbable material for enhancing the long-term success of TE-IVD implants.

High Accuracy of Three-Dimensional Navigated Kirschner-Wire-Less Single-Step Pedicle Screw System (SSPSS) in Lumbar Fusions: Comparison of Intraoperatively Planned versus Final Screw Position.

(1) Background: Our team has previously introduced the Single-Step Pedicle Screw System (SSPSS), which eliminates the need for K-wires, as a safe and effective method for percutaneous minimally invasive spine (MIS) pedicle screw placement. Despite this, there are ongoing concerns about the reliability and accuracy of screw placement in MIS procedures without traditional tools like K-wires and Jamshidi needles. To address these concerns, we evaluated the accuracy of the SSPSS workflow by comparing the planned intraoperative screw trajectories with the final screw positions. Traditionally, screw placement accuracy has been assessed by grading the final screw position using postoperative CT scans. (2) Methods: We conducted a retrospective review of patients who underwent lumbar interbody fusion, using intraoperative 3D navigation for screw placement. The planned screw trajectories were saved in the navigation system during each procedure, and postoperative CT scans were used to evaluate the implanted screws. Accuracy was assessed by comparing the Gertzbein and Robbins classification scores of the planned trajectories and the final screw positions. Accuracy was defined as a final screw position matching the classification of the planned trajectory. (3) Results: Out of 206 screws, 196 (95%) were accurately placed, with no recorded complications. (4) Conclusions: The SSPSS workflow, even without K-wires and other traditional instruments, facilitates accurate and reliable pedicle screw placement.

No decay in outcomes at a mean 8 years following surgical treatment for aseptic fracture nonunion.

PURPOSE: The purpose of this study is to compare medium to long term patient reported outcomes to one-year data for patients treated surgically for an aseptic fracture nonunion. METHODS: 305 patients surgically treated for a fracture-nonunion were prospectively followed. Data collected included pain scores measured by the Visual Analog Scale (VAS), clinical outcomes assessed by the Short Musculoskeletal Functional Assessment (SMFA), and range of motion. 75% of patients in this study had lower extremity fracture nonunions and 25% had upper extremity fracture nonunions. Femur fracture nonunions were the most common. Data at latest follow-up was compared to one-year follow-up using the independent t-test. RESULTS: Sixty-two patients were available for follow-up data at an average of eight years. There were no differences in patient reported outcomes between one and eight years according to the standardized total SMFA (p = 0.982), functional index SMFA (p = 0.186), bothersome index SMFA (p = 0.396), activity index SMFA (p = 0.788), emotional index SMFA (p = 0.923), or mobility index SMFA (p = 0.649). There was also no difference in reported pain (p = 0.534). Range of motion data was collected for patients who followed up in clinic for an average of eight years after their surgical treatment. 58% of these patients reported a slight increase in range of motion at an average of eight years. CONCLUSION: Patient functional outcomes, range of motion, and reported pain all normalize after one year following surgical treatment for fracture nonunion and do not change significantly at an average of eight years. Surgeons can feel confident in counseling patients that their results will last and they do not need to follow up beyond one year, barring pain or other complications. LEVEL OF EVIDENCE: Level IV.