Objective: The development of adjacent segment disease or the progression of spondylosis following the surgical treatment of spinal stenosis and spondylolisthesis is well documented and can lead to subsequent functional decline after a successful index surgery. The early detection of negative inflection points during patients’ functional recovery can improve timely intervention. In this study, we developed machine learning (ML) models to predict the occurrence of post-operative decline in patient mobility. Methods: Patients receiving spine surgery for degenerative spinal stenosis or spondylolisthesis were retroactively consented and enrolled. Activity data (steps-per-day) previously recorded across a 4-year peri-operative were collected alongside relevant clinical and demographic variables. Logistic regression (LR), random forest (RF), and extreme gradient boosting (XGBoost) ML models were constructed and trained on 80% of the dataset and validated using the remaining 20%. The study’s primary endpoint was the models’ ability to predict post-operative decline in patient mobility. Results: A total of 75 patients were included. Following training, RF and XGBoost models achieved accuracy values of 86.7% (sensitivity 80%, specificity 90%) and 80% (sensitivity 60%, specificity 90%), respectively, in predicting post-operative functional decline. The LR model was the least effective with an accuracy of 73.3% (sensitivity 50%, specificity 88.8%). Receiver operating characteristic curves showed an area under the curve of 0.80 for RF, 0.70 for XGBoost, and 0.69 for LR. Conclusions: ML models trained on activity data collected from smartphones successfully forecast functional decline in post-operative activity following spine surgery. These results lay the groundwork for the future integration of ML into the surgeon’s toolbox for prognostication and surgical planning.

Background/Objectives: Utilization of polyetheretherketone (PEEK) cages for spinal fusion has surged in the U.S., yet comprehensive comparisons evaluating its postoperative effectiveness with alternative materials remain limited. This systematic review investigates the efficacy of PEEK cages against traditional fusion materials across various surgery types, elucidating PEEK’s impact on fusion rates, postoperative outcomes, and long-term success. Methods: A systematic search of PubMed, CINAHL, Scopus, Embase, and Web of Science was conducted through 14 October 2024. Included studies were randomized controlled trials (RCTs) comparing PEEK cages with titanium, silicon nitride, and metal-coated PEEK cages for anterior cervical discectomy and fusion (ACDF), posterior lumbar interbody fusion (PLIF), and transforaminal lumbar interbody fusion (TLIF). Article quality was assessed using GRADE criteria. Results: From 288 initially screened articles, 25 RCTs involving 2046 patients (mean follow-up 23.1 ± 18.2 months) met inclusion criteria and were determined as moderate (n = 21) or high (n = 4) quality. Fusion rates by cage material for PEEK (n = 1041), Ti-PEEK (n = 291), and titanium (n = 53) were 85.63 ± 18.00%, 80.05 ± 19.9%, and 92.75 ± 11.31%, respectively. In ACDF, titanium cages achieved higher fusion rates than PEEK (100% vs. 94%). In PLIF and TLIF, coated PEEK outperformed uncoated PEEK (75% vs. 71% and 94% vs. 84%, respectively). Uncoated PEEK achieved fusion rates of 94.04 ± 5.04% for ACDF, 71.21 ± 21.93% for PLIF, and 83.50 ± 24.66% for TLIF, with titanium outperforming PEEK in early fusion outcomes. Coated PEEK demonstrated potential improvements in fusion rates over uncoated PEEK in PLIFs and TLIFs. Conclusions: Selection of cage material for spinal fusions should be tailored to surgical requirements and patient needs. While titanium and PEEK are effective, their performance varies across contexts. New materials and surface modifications may enhance these outcomes further, warranting future research in long-term studies and development of novel materials. These findings can help surgeons choose cage materials according to procedure type, patient characteristics, and imaging needs.

Over recent years, medial pivot total knee arthroplasty (MP-TKA) has gained traction as it more closely replicates native knee kinematics. This review traces the evolution from early TKA designs through modern "ball-and-socket" concepts and describes how MP implants stabilize the medial compartment while allowing for physiologic lateral rollback. We aim to provide an overview of the biomechanical rationale of the MP-TKA design and analyze contemporary literature on survivorship and patient satisfaction. Recent fluoroscopic and motion capture investigations confirm that MP devices can reduce paradoxical anterior translation and improve sagittal-plane stability. However, pivot behavior varies by activity, implant geometry, and alignment strategy, and differences in kinematic measurement methods, such as low-point versus contact-point tracking, can influence interpretation. Despite these methodological differences, many MP designs demonstrate favorable in vivo performance. Several small-to-large clinical series, registries, and randomized trials report promising patient-reported outcome measures and survivorship rates comparable to, or better than, traditional posterior-stabilized TKA. However, comparative studies have noted higher revision rates with specific MP implants. Design variations, surgical technique, and patient selection may significantly affect outcomes. While preliminary findings are encouraging, large-scale and long-term research is needed to clarify whether enhanced kinematics consistently translate into clinical benefit. This review highlights key implant designs, biomechanical considerations, and evolving evidence to guide surgeons who are considering MP-TKA.

Background/Objectives: The success of lumbar interbody fusion depends on the implant design and the surgical approach used. This study evaluated the clinical and radiographic outcomes of lateral lumbar interbody fusion (LLIF) and anterior lumbar interbody fusion (ALIF) using a 3D-printed porous titanium interbody cage system. Methods: A retrospective, single-center review of 48 patients treated for degenerative lumbar spine disease was conducted. Patients underwent LLIF, ALIF, or a combination of both using a 3D-printed titanium cage system (J&J MedTech, Raynham, MA, USA). The Oswestry disability index (ODI) and Patient-Reported Outcomes Measurement Information System (PROMIS) metrics were assessed after 6 weeks, 3 months, 6 months, and 12 months. Linear mixed-effects models evaluated the pre- and post-operative differences. Fusion performance and complications were assessed using the Bridwell grading system over 24 months. Results: A total of 78 levels (62 LLIF and 16 ALIF) were analyzed. Fusion rates were 90.3% (56/62) for LLIF levels and 81.3% (13/16) for ALIF levels by the end of 12 months. ODI scores improved significantly after 3 months (MD −13.0, p < 0.001), 6 months (MD −12.3, p < 0.001), and 12 months (MD −14.9, p < 0.001). PROMIS Pain Interference scores improved after 3 months (MD −6.1, p < 0.001), 6 months (MD −3.4, p < 0.001), and 12 months (MD −5.8, p < 0.001). PROMIS Physical Function scores improved after 3 months (MD +3.4, p = 0.032) and 12 months (MD +4.9, p < 0.001). Conclusions: This novel interbody cage demonstrated high fusion rates, significant pain and function improvements, and a favorable safety profile, warranting further comparative studies.

Background: Adult spinal deformity (ASD) is a prevalent condition often treated with circumferential spinal fusion (CF), which can be performed as staged or same-day procedures. However, evidence guiding the choice between these approaches is lacking. Objective: This study aims to compare patient outcomes following staged and same-day CF for ASD. Methods: Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a comprehensive literature search was conducted in PubMed, MEDLINE, Embase, Cochrane CENTRAL, Web of Science, and Scopus. Eligibility criteria included studies comparing outcomes following staged and same-day CF in adults with ASD. Searches were exported to Covidence, and records were deduplicated automatically. Title and abstract screening, full-text review, and data extraction were performed by two independent reviewers, with all conflicts being resolved by a third reviewer. A meta-analysis was conducted for outcomes reported in 3 or more studies. Results: Seven studies with 741 patients undergoing CF for ASD were included in the review (staged: n=331, 44.7% and same-day: n=410, 55.3%). Four studies that had comparable outcomes were merged for the quantitative meta-analysis and split based on observed measures. The meta-analysis revealed significantly shorter hospital length of stay (mean difference 3.98, 95% CI 2.23-5.72 days; P<.001) for same-day CF. Three studies compared the operative time between staged and same-day CF, with all reporting a lower mean operative time for same-day CF (mean between 291-479, SD 129 minutes) compared to staged CF (mean between 426-541, SD 124 minutes); however, inconsistent reporting of mean and SD made quantitative analyses unattainable. Of the 4 studies that compared estimated blood loss (EBL) in the relevant groups, 3 presented a lower EBL (mean between 412-1127, SD 954 mL) in same-day surgery compared to staged surgery (mean between 642, SD 550 to 1351, SD 869 mL). Both studies that reported intra- and postoperative adverse events showed more intraoperative adverse events in staged CF (10.9% and 13.6%, respectively) compared to same-day CF (9.1% and 3.6%, respectively). Four studies measuring any perioperative adverse events showed a higher incidence of adverse events in staged CF than all studies combined. However, quantitative analysis of EBL, intraoperative adverse events, and perioperative adverse events found no statistically significant difference. Postoperative adverse events, reoperation, infection rates, and readmission rates showed inconsistent findings between studies. Data quality assessment revealed a moderate degree of bias for all included studies. Conclusions: Same-day CF may offer shorter operating time and hospital stay compared to staged CF for ASD. However, there was marked heterogeneity in perioperative outcomes reporting, and continuous variables were inconsistently presented. This underscored the need for standardized reporting of clinical variables and patient-reported outcomes and higher evidence of randomized controlled trials to elucidate the clinical superiority of either approach. Trial Registration: PROSPERO CRD42022339764; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=339764 International Registered Report Identifier (IRRID): RR2-10.2196/42331