Judith Olde Heuvel

Purpose: To investigate whether tibiofemoral bone and meniscus morphology were associated with dynamic anterior tibial translation (ATTd) and internal tibial rotation (ITRd) during jump‐landing tasks in anterior cruciate ligament (ACL)‐reconstructed knees. Results may provide some guidance on the use of additional surgical procedures alongside (revision) ACL reconstruction (ACLR). Methods: Patients who underwent primary ACLR were included. Morphological features were measured using pre‐surgery magnetic resonance images of the operated knee. Dependent variables included ATTd and ITRd during the landing of the single‐leg hop for distance (SLHD) and side hop (SH), measured with three‐dimensional optoelectronic motion capture. Univariate statistical parametric mapping regression analyses were conducted with morphological features as predictors. Results: Thirty patients were included at 4.7 ± 1.8 years post‐ACLR (age: 31.0 ± 4.8 years). Steeper sagittal‐plane lateral posterior tibial slope and greater medial–lateral difference in posterior tibial slope were significantly associated with less ATTd (peak r = −0.75; p = 0.048) and greater ITRd (peak r = 0.75; p = 0.047) during the SLHD and SH, but only in ACL‐reconstructed knees with a flat medial tibial plateau (−2° to +2°; n = 13 subgroup analysis). Steeper coronal‐plane tibial slope was significantly associated with less ATTd during the SLHD (peak r = −0.45; p = 0.049), and with greater ITRd during the SH (peak r = 0.47; p = 0.047). Smaller lateral meniscal slope of the posterior horn was significantly associated with greater ITRd during the SLHD (peak r = −0.46; p = 0.047). Greater lateral femoral condyle ratio was significantly associated with greater ITRd during the SLHD (peak r = 0.46; p = 0.04) and SH (peak r = 0.56; p = 0.006). Conclusions: The observed associations with greater ITRd warrant further investigation into the potential role of anterolateral corner reconstruction alongside (revision) ACLR in patients with these morphological features. Since associations between posterior tibial slopes and ITRd depended on a flat medial plateau, the role of slope‐reducing tibial osteotomy appears limited, as these procedures typically do not selectively target a single plateau. Level of Evidence: Level II.

Distal radius malunion is a frequent complication after a distal radius fracture, impairing function and quality of life. Corrective osteotomy using conven

Purpose: Positioning of an osteosynthesis plate is a key step in the preoperative 3D planning processes for the design of patient-specific guides. This step requires considerable time and expertise. To increase 3D planning efficiency, this study aims to develop an automated plate positioning algorithm. Methods: A robust algorithm was developed to optimize osteosynthesis plate positioning on the distal radius, using STL properties and anatomical landmarks. The algorithm involved alignment, landmark detection, initial placement, and final optimization. Retrospective data of 34 planned radii and corresponding plate positions, including decimated and refined mesh versions, were used to compare algorithm output to manual placement based on runtime, Hausdorff distance, translation, and rotation (mean ± SD, 95% CI), thereby assessing robustness across different mesh resolutions. Results: The average run time for the algorithm was 18.3 ± 16.8 s (95% CI 12.4–24.1 s) compared to a manual placement time of 12.45 ± 4.56 min (single expert, n = 10, 95% CI 9.22–16.28 min). The mean unpaired maximum Hausdorff distance between manual and algorithm placements was 5.5 ± 2.5 mm (95% CI 4.6–6.4 mm). The mean rotation and translation differences were 4.9 ± 3.2° (95% CI 3.8–6.0°) and 3.3 ± 1.7 mm (95% CI 2.8–3.9 mm), respectively. Conclusion: In conclusion, while some manual adjustment remains necessary, the algorithm aids in reducing planning time and offers a modular, generalizable framework adaptable to other osteotomy-plate procedures, supporting clinical 3D planning.

Purpose: To determine whether posterior tibial slope (PTS) measured to proximal anatomical axes can serve as a reliable proxy for PTS measured to the mechanical tibial axis (mTA). Methods: In patients ≥18 years with failed anterior cruciate ligament reconstruction, medial and lateral PTS were measured relative to the mTA on a lateral lower‐leg radiograph, and relative to the proximal tibial anatomical axis (PTAA), anterior tibial cortical axis (ATC) and posterior tibial cortical axis (PTC) on a lateral knee radiograph. Agreement was assessed using correlation coefficients, measurement error and Bland–Altman analysis. Diagnostic accuracy of the conventional ≥12° PTAA‐based PTS cut‐off for slope‐reducing osteotomy was determined. Results: Fifty‐nine knees were analyzed. Correlation between proximal anatomical axes and mTA‐based PTS measurements was strong ( r ≥ 0.71), but agreement was poor. Mean measurement error for PTAA was 0.1 ± 2.4° (range: −5.7° to 7.6°) and −0.5 ± 2.4° (range: −6.6° to 5.2°), for ATC −3.4 ± 2.6° (range: −8.6° to 5.9°) and −3.7 ± 2.6° (range: −9.9° to 2.7°) and for PTC 3.0 ± 2.6° (range: −2.9° to 10.4°) and 2.7 ± 2.4° (range: −3.6° to 7.8°) for the medial and lateral plateau, respectively. For PTAA, absolute measurement error ≥2° occurred in approximately 50% of knees. Bland–Altman analysis showed 95% levels of agreement ranging from −4.89° to 4.62° (medial) and −5.11° to 4.11° (lateral). Using the ≥12° cut‐off on PTAA‐based PTS values misclassified approximately one in three knees (19.5% false‐positive and 13.2% false‐negative) relative to the mTA‐based PTS reference values. Conclusion: Despite strong correlation, proximal anatomical axes‐based PTS measurements on routine lateral knee radiographs show substantial, bidirectional measurement error outside clinically acceptable limits of agreement compared to mTA‐based PTS measurements on full‐length lateral lower‐leg radiographs. Single‐exposure, full‐length lateral lower‐leg radiographs should be obtained to measure PTS relative to the mTA when considering slope‐reducing osteotomy. Level of Evidence: Level IV.

Purpose: When performing 3D planning for osteotomies in patients with distal radius malunion, the contralateral radius is commonly used as a template for reconstruction. However, in approximately 10% of the cases, the contralateral radius is not suitable for use. A shape completion model may provide an alternative by generating a healthy radius model based on the proximal part of the malunited bone. The aim of this study is to develop and clinically evaluate such a shape completion model. Method: A total of 100 segmented CT scans of healthy radii were used, with 80 scans used to train a statistical shape model (SSM). This SSM formed the base for a shape completion model capable of predicting the distal 12% based on the proximal 88%. Hyperparameters were optimized using 10 segmented 3D models, and the remaining 10 models were reserved for testing the performance of the shape completion model. Results: The shape completion model consistently produced clinically viable 3D reconstructions. The mean absolute errors between the predicted and corresponding reference models in the rotational errors were 2.6 ± 1.7° for radial inclination, 3.6 ± 2.2° for volar tilt, and 2.6 ± 2.8° for axial rotation. Translational errors were 0.7 ± 0.6 mm in dorsal shift, 0.8 ± 0.5 mm in radial shift, and 1.7 ± 1.1 mm in lengthening. Conclusion: This study successfully developed a shape completion model capable of reconstructing healthy 3D radius models based on the proximal bone. The observed errors indicate that the model is viable for use in 3D planning for patients lacking a healthy contralateral radius. However, routine use in patients with a healthy contralateral radius is not yet advised, as error margins exceed bilateral differences observed in healthy populations. The most clinically relevant error found in the model, length mismatch, can be easily corrected during 3D planning if the ipsilateral ulna remains intact.

Purpose: To reach consensus among international experts on a structured framework for standardized 3D leg alignment analysis based on 3D bone models, ensuring consistency and improving clinical applicability. Methods: A Delphi study was performed in four rounds. Rounds 1 and 2 involved a steering and rating group that developed statements based on principles preserving the 3D complexity of anatomical structures, identified through a systematic review. These statements encompassed approaches for deriving joint centres and joint orientations, and defining coordinate systems using 3D bone models. In Rounds 3 and 4, a panel of 35 international experts, including clinicians (54%) and engineers (46%), with participants from Europe (80%), Oceania (9%), Asia (6%), and the Americas (6%), evaluated these statements. Consensus was defined as ≥80% agreement. Results: Rounds 1 and 2 resulted in 31 statements to be included in the survey. Of these, 26 achieved consensus in Round 3, with the five remaining statements refined and reaching consensus in Round 4. Experts agreed on utilising all available relevant surface data to define joint centres, joint orientations, and individual femoral and tibial coordinate systems alongside a combined leg coordinate system, and adopting central 3D axes for femoral version and tibial torsion. Conclusions: This international Delphi consensus study provides a structured framework for a standardized 3D leg alignment analysis based on 3D bone models. This framework aims to enhance clinical applicability for preoperative planning and execution of uni‐ and multiplanar correction osteotomies around the knee, reduce the methodological variability in 3D leg alignment analysis literature, and improve cross‐study comparability. Level of Evidence: Level V.

Background: A corrective radius osteotomy is often performed in patients with a symptomatic distal radius malunion. In 3D-planned osteotomies, the unaffected radius is mirrored over the malunited radius after adjusting for left-right length differences using both ulnae. This approach assumes that ulnar length differences in a malunion population are similar to those in a healthy population. This study was conducted to analyze the difference in ulnar length in a distal radius malunion population and to assess the potential influence of age, sex, or malunion side on this difference. Methods: We evaluated 65 adult patients with distal radius malunion using bilateral forearm CT scans. 3D models of both ulnae were constructed, and length differences were determined along a standardized length axis. The results were compared to two populations without a radius malunion. Results: The average absolute ulnar length difference was 2.57 mm (SD 1.81), which was comparable to the two healthy populations. This difference was not significantly affected by age, sex, or malunion side. Conclusion: This study demonstrated that using the ulnar length difference to correct for radial length difference in the current 3D planning process, before using the contralateral radius as a template for a corrective osteotomy in patients with radius malunion, is safe.

Symptomatic malunion of the wrist is one of the most common posttraumatic wrist problems. This study demonstrates three patients with complex malunions of the wrist who benefited from a corrective osteotomy using preplanned 3D-printed patient-specific guides, by experiencing improvement in their wrist function, grip strength and a reduction in pain.

Forefoot osteotomies to improve the alignment are difficult procedures and can lead to a variety of complications. Preoperative planning in three dimensions might assist in the successful management of forefoot deformities. The purpose of this study was to develop a global coordinate system in the foot for the planning of forefoot corrections. Two strategies (CS1 and CS2) were developed for defining a global coordinate system that meets the criteria of being well-defined, robust, highly repeatable, clinically relevant, compatible with foot CT scans, independent of the ankle joint angle, and does not include bones in the forefoot. The absolute angle of rotation was used to quantify repeatability. The anatomical planes of the coordinate systems were visually inspected by an orthopedic surgeon to evaluate the clinical relevancy. The repeatability of CS1 ranged from 0.48° to 5.86°. The definition of CS2 was fully automated and, therefore, had a perfect repeatability (0°). Clinically relevant anatomical planes were observed with CS2. In conclusion, this study presents an automated method for defining a global coordinate system in the foot according to predefined requirements for the planning of forefoot corrections.

This case report presents a rare case of subsequent ipsilateral and contralateral subchondral insufficiency fracture of the knee (SIFK) in the trochlea of the femur within months, manifested in a professional cyclist. SIFKs in the trochlea have not yet been reported in the literature; however, their appearance in a professional cyclist might be explained by the amount of repetitive pressure on the patellofemoral joint when cycling. In both instances, atraumatic anterior knee pain occurred, resolving after conservative treatment for 6–9 weeks. The patient reached their previous activity level. The authors believe SIFK in the younger population may be more common than currently perceived due to its self-limiting behaviour and a lack of performing immediate MRIs in this younger group whenever an overload injury is suspected.