Background: Failure of unicompartmental knee arthroplasty (UKA) is a distressing and technically challenging complication. Conventional conversion techniques (CCT) with rods and jigs have produced varying results. A robotic-assisted conversion technique (RCT) is an unexplored, though possibly advantageous, alternative. We compare our reconstructive outcomes between conventional and robotic methods in the management of failed UKA. Methods: Thirty-four patients with a failed UKA were retrospectively reviewed. Patients underwent conversion total knee arthroplasty (TKA) with either a CCT or RCT. Seventeen patients were included in each group. All procedures were done by a single surgeon at a single institution, with a mean time to follow-up of 3.6 years (range, 1 to 12). The primary outcome measures were the need for augments and polyethylene thickness. Secondary outcome measures were complications, need for revision, estimated blood loss (EBL), length of stay, and operative time. Results: The mean polyethylene thickness was 12 mm (range, 9 to 15) in the CCT group and 10 mm (range, 9 to 14) in the RCT groups, with no statistical difference between the two groups (P = 0.07). A statistically significant difference, however, was present in the use of augments. In the CCT group, five out of 17 knees required augments, whereas none of the 17 knees in the RCT group required augments (P = 0.04). Procedurally, roboticassisted surgery progressed uneventfully, even with metal artifact noted on the preoperative computerized tomography (CT) scans. Computer mapping of the residual bone surface after implant removal was a helpful guide in minimizing resection depth. No further revisions or reoperations were performed in either group. Conclusions: Robotic-assisted conversion TKA is technically feasible and potentially advantageous. In the absence of normal anatomic landmarks to guide conventional methods, the preoperative CT scans were unexpectedly helpful in establishing mechanical alignment and resection depth. In this limited series, RCT does not seem to be inferior to CCT. Further investigation of outcomes is warranted.

OBJECTIVE The use of technology-enhanced methods in spine surgery has increased immensely over the past decade. Here, the authors present the largest systematic review and meta-analysis to date that specifically addresses patient-centered outcomes, including the risk of inaccurate screw placement and perioperative outcomes in spinal surgeries using robotic instrumentation and/or augmented reality surgical navigation (ARSN). METHODS A systematic review of the literature in the PubMed, EMBASE, Web of Science, and Cochrane Library databases spanning the last decade (January 2011–November 2021) was performed to present all clinical studies comparing robot-assisted instrumentation and ARSN with conventional instrumentation techniques in lumbar spine surgery. The authors compared these two technologies as they relate to screw accuracy, estimated blood loss (EBL), intraoperative time, length of stay (LOS), perioperative complications, radiation dose and time, and the rate of reoperation. RESULTS A total of 64 studies were analyzed that included 11,113 patients receiving 20,547 screws. Robot-assisted instrumentation was associated with less risk of inaccurate screw placement (p < 0.0001) regardless of control arm approach (freehand, fluoroscopy guided, or navigation guided), fewer reoperations (p < 0.0001), fewer perioperative complications (p < 0.0001), lower EBL (p = 0.0005), decreased LOS (p < 0.0001), and increased intraoperative time (p = 0.0003). ARSN was associated with decreased radiation exposure compared with robotic instrumentation (p = 0.0091) and fluoroscopy-guided (p < 0.0001) techniques. CONCLUSIONS Altogether, the pooled data suggest that technology-enhanced thoracolumbar instrumentation is advantageous for both patients and surgeons. As the technology progresses and indications expand, it remains essential to continue investigations of both robotic instrumentation and ARSN to validate meaningful benefit over conventional instrumentation techniques in spine surgery.

Background: The statistical significance of a given study outcome can be liable to small changes in findings. P values are common, but imperfect statistical methods to convey significance, and inclusion of the fragility index (FI) and fragility quotient (FQ) may provide a clearer perception of statistical strength. Purpose/Hypothesis: The purpose was to examine the statistical stability of studies comparing primary single-bundle to double-bundle anterior cruciate ligament reconstruction (ACLR) utilizing autograft and independent tunnel drilling. It was hypothesized that the study findings would be vulnerable to a small number of outcome event reversals, often less than the number of patients lost to follow-up. Study Design: Systematic review; Level of evidence, 2. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the authors searched PubMed for comparative studies and randomized controlled trials (RCTs) published in select journals, based on impact factor, between 2005 and 2020. Risk-of-bias assessment and methodology scoring were conducted for the included studies. A total of 48 dichotomous outcome measures were examined for possible event reversals. The FI for each outcome was determined by the number of event reversals necessary to alter significance. The FQ was calculated by dividing the FI by the respective sample size. Results: Of the 1794 studies screened, 15 comparative studies were included for analysis; 13 studies were RCTs. Overall, the mean FI and FQ were 3.14 (IQR, 2-4) and 0.050 (IQR, 0.032-0.062), respectively. For 72.9% of outcomes, the FI was less than the number of patients lost to follow-up. Conclusion: Studies comparing single-bundle versus double-bundle ACLR may not be as statistically stable as previously thought. Comparative studies and RCTs are at substantial risk for statistical fragility, with few event reversals required to alter significance. The reversal of fewer than 4 outcome events in a treatment group can alter the statistical significance of a given result; this is commonly less than the number of patients lost to follow-up. Future comparative study analyses might consider including FI and FQ with P values in their statistical analysis.

Tumors of the craniocervical junction (CCJ) are complicated pathologies with high patient mortality or low quality of life. In the pediatric population, these tumors are less prevalent, with various symptomatic presentations that include motor and neurological manifestations. Three of the most common neoplasms at the CCJ in children are meningiomas, schwannomas, and chordomas. In this review, we will characterize the tissue biomarkers, clinical presentation, treatment methods, and surgical outcomes for these pediatric tumors at the CCJ. A comprehensive literature review was used using the PubMed Database. Keywords used were "craniocervical junction", "pediatric", "meningiomas", schwannomas", and "meningiomas". Articles that were not related to the CCJ, included only adult cases, and non-English studies were filtered. Our search yielded a total of 11 studies, with a total of 239 pediatric patients with tumors at the CCJ. These studies were broken down as five for meningiomas, one for schwannomas, and eight for chordomas. In conclusion, resection of pediatric neoplasms at the CCJ is challenging due to anatomical limitations and the size of the patient. Within the CCJ, chordomas were the most prevalent tumor type, with schwannomas being the least prevalent. Literature findings indicate that genetic mutations of the NF2 gene associated with neurofibromatosis type II, as well as incomplete tumor resection, are predictors of poor outcomes. Further developments of monoclonal antibody chemotherapy and endoscopic approaches could expand treatment options for aggressive pediatric neoplasms at the skull base.

Purpose Failed femoral neck fracture (FNF) fixation with in situ pinning presents a surgical challenge. Osteoporotic bone, retained hardware, and a typically elderly population magnify the risks of surgery. Here, outcomes of conversion total hip arthroplasty (THA) using two separate incisions in these high-risk patients were examined. Materials and Methods Medical records for 42 patients with a prior history of FNF fixation who underwent conversion THA with hardware removal between 2009 and 2019 were retrospectively reviewed. Surgery was performed by a single surgeon at a single institution. All patients underwent hardware removal followed by direct anterior approach (DAA) THA using two separate incisions. Clinical outcomes, radiographic findings, and perioperative morbidity and mortality are reported. Results Clinically, there were no postoperative dislocations, periprosthetic fractures, or infections at follow-up. After a mean follow-up of 4 years, the mean hip disability and osteoarthritis outcome score, junior (HOOS, Jr) was 91. Radiographically, the mean postoperative cup abduction was 44 degrees and the mean cup anteversion was 21 degrees with an improvement in preoperative leg length discrepancy. Perioperative complications included one case of immediate foot drop and two readmissions for medical issues. One patient died one month after conversion THA. Conclusion Salvage of failed FNF treatment may be managed with conversion THA and DAA with a separate incision for hardware removal. Preservation of posterior soft tissues using a DAA and intraoperative fluoroscopy may mitigate well-known complications related to fracture and dislocation. While favorable clinical outcomes are possible, salvage surgery is still not without substantial surgical and medical risks.