Activity is increasingly being recognized as a highly relevant parameter in all areas of healthcare for diagnosis, treatment, or outcome assessment, especially in orthopaedics where the movement apparatus is directly affected. Therefore, the aim of this study was to develop, describe, and clinically validate a generic activity-monitoring algorithm, satisfying a combination of three criteria. The algorithm must be able to identify, count, and time a large set of relevant daily activities. It must be validated for orthopaedic patients as well as healthy individuals, and the validation must be in a setting that mimics free-living conditions. Using various technical solutions, such as a dual-axis approach, dynamic inclinometry (hip flexion), and semiautomatic calibration (gait speed), the algorithms were designed to count and time the following postures, transfers, and activities of daily living: resting/sitting, standing, walking, ascending and descending stairs, sit-stand transitions, and cycling. In addition, the number of steps per walking bout was determined. Validation was performed with healthy individuals and patients who had undergone unilateral total joint arthroplasty, representing a wide spectrum of functional capacity. Video observation was used as the gold standard to count and time activities in a validation protocol approaching free-living conditions. In total 992 and 390 events (activities or postures) were recorded in the healthy group and patient group, respectively. The mean error varied between 0% and 2.8% for the healthy group and between 0% and 7.5% for the patient group. The error expressed in percentage of time varied between 2.0% and 3.0% for both groups. Activity monitoring of orthopaedic patients by counting and timing a large set of relevant daily life events is feasible in a user- and patient-friendly way and at high clinical validity using a generic three-dimensional accelerometer and algorithms based on empirical and physical methods. The algorithms performed well for healthy individuals as well as patients recovering after total joint replacement in a challenging validation set-up. With such a simple and transparent method real-life activity parameters can be collected in orthopaedic practice for diagnostics, treatments, outcome assessment, or biofeedback.

Aims: One of the instruments in the orthopaedic surgeon’s armamentarium to face the challenges associated with periprosthetic fracture around the stem of a hip replacement is the tapered, fluted, modular, titanium (TFMT) stem. Our aim was to study its clinical and radiological outcomes. Patients and Methods: During the period 2010–2016 86 patients (55 females; median age 78.2 years; mean BMI 26.3 kg/m²; median ASA classification 2) underwent 87 revisions for a Vancouver B periprosthetic fracture using a Stryker Restoration Cone-Conical stem. Results: After a median follow-up of 2.9 years no stem had to be revised and no case of stem fracture was found. Dislocation was the most common complication and occurred in 18% of patients. Other major complications were deep infection ( n = 4), subsidence >5 mm ( n = 7), and nonunion ( n = 5). 3-month and 1-year mortality was 10% and 15% respectively and was strongly correlated with age, deep infection, and ASA classification. The median EQ-5D health state index at final follow-up was 0.78 and all patients were ambulatory. Conclusions: The complication most commonly encountered was dislocation and can likely be prevented by the use of large heads, adequate reduction and fixation of the trochanteric area and restoration of the native anatomy. Contrary to previous concerns, fracture and subsidence of these modular stems do not appear to be a significant problem in this geriatric population.

Purpose: The aim of this systematic review was to evaluate the outcomes and complications associated with technology‐assisted revision total knee arthroplasty (revTKA).Methods: A systematic search of PubMed, EMBASE, Web of Science and the Cochrane Library was conducted from inception to 31 October 2024. The inclusion criteria were experimental or observational studies with ≥10 patients undergoing robotic revTKA, evaluating clinical and/or radiological outcomes and/or complication rates. The exclusion criteria were isolated patellar revision, in vitro studies, letters to the editor, book chapters, conference papers, and studies without accessible full text. Each study was given a quality rating using the methodological index for non‐randomised studies (MINORS). The included studies were divided into those reporting revision from TKA and those from unicompartmental knee arthroplasty (UKA), for both qualitative and quantitative synthesis. Random‐effects meta‐analyses were performed where appropriate. Mean differences with 95% confidence intervals (CIs) were calculated for radiographic parameters. Heterogeneity was assessed using the I² statistic.Results: Across 20 studies (795 cases), 10 assessed revTKA and 10 examined revUKA. Of the revTKA studies, four were comparative cohorts, while among the revUKA studies, seven were comparative cohorts. Technology‐assisted revTKA showed fewer outliers in hip–knee–ankle angle (13.3% [95% CI, 8.7%–19.0%] vs. 26.1% [95% CI, 16.3%–38.1%]), superior component positioning within ±3° for the lateral distal femoral angle (88.4% [95% CI, 83.2%–92.4%] vs. 79.7% [95% CI, 68.8%–87.5%]) and for the medial proximal tibial angle (91.2% [95% CI, 86.3%–94.6%] vs. 82.6% [95% CI, 72.0%–89.8%]), and better joint line restoration (79.5% vs. 58.3% within 4 mm). Procedures required an additional 15–24 min. Complication rates were comparable between groups. For UKA revisions, outcomes were generally similar between technology‐assisted and conventional techniques, with mixed results on alignment accuracy and clinical scores.Conclusion: Technology‐assisted revTKA achieves optimal alignment parameters and reduces the occurrence of outliers compared with conventional techniques. However, these radiographic improvements do not consistently translate into enhanced clinical outcomes or reduced complication rates.Level of Evidence: Level IV.

Aims: Tibial fixation in revision total knee arthroplasty (rTKA) can present surgical challenges. It has been suggested that appropriate fixation in at least two of the three anatomical zones (epiphysis, metaphysis, and diaphysis) is essential for implant survival. However, supporting clinical data are lacking. In this retrospective case-control study, we investigated the relationship between zonal fixation of hybrid rTKA tibial components and re-revision total knee arthroplasty for aseptic loosening (rrTKA-AL).Methods: All consecutive rTKAs with hybrid tibial components (May 2006 to December 2020) were screened for subsequent rrTKA-AL. A control group was randomly selected from the remaining cohort. Postoperative radiographs of rTKAs were scored in random order by three blinded observers for zonal fixation in the epiphysis (bone resection level below, at, or above fibular head; 0 to 2), metaphysis (number of sufficiently cemented zones; 0 to 4), and diaphysis (canal filling ratio (CFR); %). The intraclass correlation coefficient (ICC) was calculated to quantify the agreement between observers. Multivariate logistic regression analysis was performed to assess the relationship between zonal fixation and rrTKA-AL.Results: Overall, 33 patients underwent a further rrTKA-AL from a total of 1,173 rTKAs where hybrid tibial components (2.8%) were used. Patients requiring rrTKA-AL had a significantly lower epiphyseal bone resection level (OR 0.43; 95% CI 0.23 to 0.76; p = 0.006), lower number of adequately cemented zones (OR 0.50; 95% CI 0.30 to 0.79; p = 0.004), but no difference in CFR (p = 0.858). Furthermore, patients needing rrTKA-AL had more frequently previous revisions (p = 0.047), a higher rate of a prior use of a stemmed tibial component (p = 0.011), and a higher Anderson Orthopaedic Research Institute classification (p < 0.001). Agreement of zonal fixation between observers was good (ICC 0.79 to 0.87).Conclusion: Patients in need of subsequent rrTKA-AL had lower epiphyseal bone resection levels and a lower number of sufficiently metaphyseal cemented zones following rTKA. These results emphasize the importance of appropriate metaphyseal fixation at rTKA. With this information, orthopaedic surgeons can identify patients at greater risk for rrTKA-AL and optimize their surgical technique in revision knee arthroplasty surgery.Cite this article: Bone Joint J 2025;107-B(1):65–71.