Mark Lenz

Purpose: To investigate the biomechanical influence of distal screw number in palmar plate fixation of unstable intra-articular distal radius fractures with radiodorsal metaphyseal comminution. Methods: Nine matched pairs of cryopreserved human radii were prepared using a standardized AO/OTA 2R3 C2.1 fracture model with a defined radiodorsal metaphyseal defect zone. For each pair, specimens were randomized to palmar fixation using a 2.4-mm variable-angle locking plate with either four or six distal screws. After embedding, constructs were subjected to cyclic axial loading (150 N, 5,000 cycles) simulating early postoperative rehabilitation. Global axial deformation and fragment-specific three-dimensional interfragmentary motion were recorded using an optical motion-tracking system. Statistical analysis was performed using non-parametric tests ( p < 0.05). Results: Two specimens from one donor pair were excluded, leaving 16 radii (8 pairs) for analysis. Bone mineral density and initial construct stiffness did not differ between groups. The six-screw configuration showed significantly lower axial deformation after cyclic loading ( p = 0.047) and lower radial fragment–shaft translation at both time points ( p = 0.028; p = 0.045). Radial fragment–shaft rotation was lower in the six-screw group at baseline ( p = 0.018), but no rotational difference remained after cyclic loading. In the overall cohort, axial deformation decreased after cyclic loading ( p = 0.015). Conclusion: In this unstable intra-articular fracture model with radiodorsal metaphyseal comminution, six distal screws reduced post-cyclic axial deformation and radial fragment–shaft micromotion compared with four screws. The clinical relevance of these findings remains to be determined.

Background: Wound complications and unplanned revision surgery remain common after soft tissue sarcoma (STS) resection. Established risk models focus on patient- and tumour-related factors, while the role of operative and perioperative variables is less well defined. Methods: This retrospective single-centre study included 95 patients undergoing STS resection between 2021 and 2025. Associations with unplanned revision surgery were evaluated using univariate and exploratory multivariable logistic regression analyses. Receiver operating characteristic (ROC) analysis assessed the discriminatory performance of postoperative drainage output. Results: Unplanned revision surgery occurred in 23 patients (24%). On univariate analysis, several intraoperative and postoperative variables were associated with revision, whereas most patient- and tumour-related factors were not statistically significant. In multivariable analysis, intraoperative crystalloid administration was the only intraoperative factor associated with unplanned revision (OR 1.45 per 500 mL, 95% CI 1.05–2.02; p = 0.026). Among postoperative parameters, drainage output remained associated with revision (OR 1.45 per 100 mL, 95% CI 1.15–1.82; p = 0.005). In patients without planned secondary reconstruction, drainage output showed good exploratory discriminatory performance (AUC 0.927), with a cutoff of 925 mL providing high specificity (94.4%) with acceptable sensitivity (75%). Conclusions: In this cohort, unplanned revision was more frequently associated with markers of surgical complexity, including higher intraoperative crystalloid administration, and the early postoperative course, particularly drainage output. Drainage output appears to reflect an evolving complication rather than an independent predictor and may serve as an early clinical warning signal. Findings are hypothesis-generated and require external validation.

Introduction: This biomechanical study compared the fracture stability of a palmar plate combined with a headless compression screw (HCS) with that of a radiopalmar double-plate construct for AO/OTA 23-C2.1 distal radius fractures with metaphyseal defect zones. Materials and Methods: Eleven matched pairs of cryopreserved human radii were prepared with standardized AO/OTA 23-C2.1 fractures. Left radii (n = 11) were fixed with a palmar plate plus HCS, while right radii (n = 11) received a radiopalmar double-plate construct. Construct stiffness and axial displacement were assessed using a universal testing machine. Interfragmentary range of motion (ROM) and rotation (ROT) were quantified using an optical three-dimensional motion-tracking system. Measurements were obtained before and after 5000 cycles of dynamic axial loading at 150 N. Two specimen pairs were excluded due to early failure or incomplete data acquisition. Results: Both constructs demonstrated comparable stiffness and axial displacement, with no implant loosening or hardware failure observed. Interfragmentary ROM did not differ significantly between groups. However, the plate–HCS construct showed greater variability in rotational parameters. Initial radial-shaft rotation was significantly greater in the plate–HCS group (1.14° vs. 0.51°, p = 0.02). After cyclic loading, ulnar-shaft rotation increased significantly in the plate–HCS group (0.97° to 1.16°, p = 0.02) but not in the double-plate group. Conclusion: In this cadaveric model, fixation with a palmar plate combined with an HCS provided comparable axial stability but demonstrated greater variability and less consistent rotational control compared with radiopalmar double plating. Clinical studies are required to determine whether this less invasive construct achieves equivalent outcomes in vivo.

Purpose: The aim of this study is to analyse the effect of an additional radial buttress plate for palmar plate osteosynthesis in an AO/OTA 2R3 C2.1 fracture model. Methods: Nine pairs of freshly frozen radii were analysed for pathology and bone mineral density and divided into two matched groups. One group was treated with a variable-angle palmar locking plate alone, while the second group received an additional radial buttress plate for radiopalmar double plating. An AO/OTA 2R3 C2.1 fracture was created in all specimens. The biomechanical tests were performed according to previously published protocols. Stiffness, axial displacement of the construct, as well as fragment-specific movements and rotations were assessed. Results: No implant failure was observed. In the total cohort, stiffness increased ( p < 0.01) and axial construct displacement decreased ( p < 0.05). The mobility of the ulnar fragment to the shaft during cyclic testing was lower with double plating, both at baseline and endpoint (all p < 0.01). Fragment movements increased over the course of testing and were significant for the radial articular fragment relative to the shaft in the total cohort ( p < 0.01). Baseline rotation of the ulnar fragment and endpoint rotation of the radial fragment in relation to the shaft were lower with double plating (all p < 0.05). In both constructs, the rotation of the ulnar fragment relative to the shaft was lower than that of the radial fragment at both timepoints (all p < 0.05). Conclusion: Biomechanically, the addition of a radial buttress plate to a standard palmar locking plate did not alter global construct stiffness, but demonstrated advantages in fragment-specific stability in comminuted distal radius fractures.

Background/Objectives: Metastatic bone disease (MBD) poses an increasing challenge in orthopaedic oncology due to prolonged survival. While clinical prognostic factors are well established, the role of socio-economic determinants remains unclear, particularly within universal healthcare systems. Methods: We retrospectively analysed 243 patients who underwent surgery for MBD (excluding spine) between 2005 and 2024 at a German sarcoma centre. Socio-economic indicators were derived from national databases and linked to patients’ residential districts. Survival was analysed using Kaplan–Meier estimates and Cox regression, adjusting for clinical confounders. Results: Median postoperative survival was 22 months. Several socio-economic indicators—income, education, and employment—were associated with survival in univariate analysis. In multivariate models, only residential area size remained independently significant (p = 0.047). Patients from villages (100,000) had poorer survival than those from small or medium-sized towns. This effect persisted after adjustment for tumour type, pathological fractures, and year of surgery. Conclusions: Within a universal healthcare system, residential area size was associated with survival after surgery for MBD, suggesting that regional disparities may persist despite equal formal access to care. Further studies integrating individual-level socioeconomic data are needed to identify mechanisms and guide interventions to reduce geographic inequalities.

Background and Objectives: The surgical treatment of proximal humeral shaft fractures usually considers application of either long straight plates or intramedullary nails. By being able to spare the rotator cuff and avoid the radial nerve distally, the implementation of helical plates might overcome the downsides of common fixation methods. The aims of the current study were (1) to explore the biomechanical competence of different plate designs and (2) to compare their performance versus the alternative treatment option of using intramedullary nails. Materials and Methods: Twenty-four artificial humeri were assigned to the following four groups for simulation of an unstable proximal humeral shaft fracture and instrumentation: Group 1 (Straight-PHILOS), Group 2 (MULTILOC-Nail), Group 3 (45°-Helical-PHILOS), and Group 4 (90°-Helical-PHILOS). All specimens underwent non-destructive, quasi-static biomechanical testing under loading in axial compression, torsion in internal/external rotation, and pure bending in four directions, accompanied by motion tracking. Results: Axial stiffness/displacement in Group 2 was significantly higher/smaller than in all other groups (p ≤ 0.010). Torsional displacement in Group 2 was significantly bigger than in all other groups (p ≤ 0.017). Significantly smaller coronal plane displacement was identified in Group 2 versus all other groups (p < 0.001) and in Group 4 versus Group 1 (p = 0.022). Significantly bigger sagittal plane displacement was detected in Group 4 versus all other groups (p ≤ 0.024) and in Group 1 versus Group 2 (p < 0.001). Conclusions: Intramedullary nails demonstrated higher axial stiffness and smaller axial interfragmentary movements compared with all investigated plate designs. However, they were associated with bigger torsional movements at the fracture site. Although 90°-helical plates revealed bigger interfragmentary movements in the sagittal plane, they demonstrated improved resistance against displacements in the coronal plane when compared with straight lateral plates. In addition, 45°-helical plates manifested similar biomechanical competence to straight plates and may be considered a valid alternative to the latter from a biomechanical standpoint.

Vernarbungen und Dysbalancen zwischen extrinsischem und intrinsischem System machen die sekundäre Strecksehnenrekonstruktion zu einer fordernden Aufgabe mit oft unbefriedigenden Resultaten. Neben generellen Hinweisen für die lokalisationsspezifische Versorgung zeigt der Beitrag typische Fallstricke auf. Scarring and dysbalances between extrinsic and intrinsic system make secondary extensor tendon reconstruction a challenging task with often unsatisfactory results. In addition to general tips for localization-specific care, the article points out typical pitfalls. Article published online: 14 November 2023 © 2023. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Plantar plate positioning has been demonstrated as biomechanically superior. However, some operators remain resentful about the morbidity of the surgical approach. To provide improved plate fixation for first tarsometatarsal joint arthrodesis with respect to the tibialis anterior tendon, a medio-plantar plate was developed. The purpose of this biomechanical study was to compare its construct stability to that of a plantar plate construct. Twelve pairs of fresh frozen human specimens were used in a matched pair test. Each pair was fixed with a 4 mm compression screw and either a plantar locking plate or a medio-plantar locking plate. A cantilever beam test was performed in dorsiflexion. Before and after cyclic loading (5000 cycles; 40 N), bending stiffness and relative movements at the joint space were monitored in a quasi-static test including optical motion tracking. Maximum load and bending moment to failure were investigated in a load-to-failure ramp test. The bending stiffness of both groups did not significantly differ before (plantar 49.9 N/mm ± 19.2; medio-plantar 53.9 N/mm ± 25.4, p = 0.43) or after (plantar 24.4 N/mm ± 9.7; medio-plantar 35.3 N/mm ± 22.0, p = 0.08) cyclic loading but decreased significantly in both groups (p < 0.01) after cyclic loading. Relative movement increased significantly during cyclic testing in both groups (p < 0.01) but did not differ significantly between the groups before (p = 0.29) or after (p = 0.16) cyclic loading. Neither load nor bending moment to failure were significantly different (plantar 225 N ± 78, 10.8 Nm; medio-plantar 210 N ± 86, 10.1 Nm, p = 0.61). Both plate constructs provided equivalent construct stability, both being well suited for Lapidus arthrodesis.