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Orthopaedic Proceedings
Vol. 107-B, Issue SUPP_1 | Pages 20 - 20
10 Feb 2025
Gomaa A Apata-Omisore J Aslam S Marsh L Paramasivan A Ward N Galhoum A Mason L
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Introduction. Fifth metatarsal fractures have been regularly classified by zones, with the description of a Jones fracture commonly being misrepresented. The aim of this study was to map the fracture patterns across the entire metatarsal shaft, and correlate with their outcomes. Methods. A historic cohort study was completed of all fifth metatarsal fractures presenting to our unit between February 2016 – July 2021. Fracture patterns were individually mapped and designated as zone 1-shaft, including designation of fractures which bridge each zone (zone 1–2 etc). Fracture patterns were cumulatively combined using GNU Image Manipulation Program to show the combined fracture map patterns per outcome. The clinical notes were examined to assess patient outcome. Results. 1331 fractures were included in this study and presented graphically as fracture maps by outcome. The number of fractures which did not propagate across more than 1 zone was 78.59% (1046/1331). The fracture type which had the highest rate of discharge at VFC without reattendance was Zone 1 fractures (360/519, 69.36%), with the lowest being fractures where the fracture spanned zone 1-shaft (p<0.001). The total number of fractures that underwent surgery was 1.35% (18/1331). The fracture pattern which had the highest rate of surgical intervention was a fracture that spanned zone 2–3 (5/43, 11.63%) followed by a fracture that spanned zone 1–3 (1/11, 9.9%). The number of appointments given to patients ranged from discharged from VFC to 7 face to face appointments. The patients with the lowest discharge rate prior to 4 appointments was zone 2–3. Conclusions. In our series, almost a quarter of fractures spanned across the previously described fracture zones. This would explain the low inter-observer rating in previous studies. The classic Jones fracture would span zones 2/3, which in our series had the highest rate requiring surgery and lowest rate of discharge before 4 appointments


Orthopaedic Proceedings
Vol. 107-B, Issue SUPP_1 | Pages 8 - 8
10 Feb 2025
Aamir J Kumar RM Ali M Abdullah BS McEvoy J Wyatt C Pillai A Mason L
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Background. Medial wall blowout (MWB) ankle fractures have not previously been described in the literature. Our aim in this study was to analyse the morphology of medial wall blowout fractures and their radiological outcomes. Methods. The MWB fracture fragments were characterised into four groups. A type 1A fracture was described as an anteromedial column fragmentation. Type 1B fractures consisted of posteromedial column fragmentation. Type 2 fracture consisted of both column wall fragmentation and type 3, any medial wall fragmentation with medial joint impaction. Results. Over 2000 patients were identified across ten years with medial malleolar fractures across two centres; of these, 196 had MWB fractures with CT imaging. There were 95 1A fractures (48.5%), 31 1B fractures (15.8%), 40 Type 2 fractures (20.4%) and 30 type 3 fractures (15.3%). Type 1B fractures were significantly more likely to undergo plate fixation than other types (p = .001). MWB fractures occurred most in PER fracture types (50.8%). Type 2 fractures were different because they occurred more with SER-type mechanisms. PM fractures were a common association (82.4%), most commonly M+M type 1. MWB type 1B occurred more with M+M 2B fractures. The overall malreduction rate was 11.8%, although 1B fracture types had significantly higher malreductions (22.6%, p=.041). The overall nonunion rate was 20.6%, the highest nonunion reported in the type 2 fractures (33.3%), although not significant. Tibialis posterior tendon entrapment was common (47.3%), although it was significantly more likely in type 2 fractures (74.4%, p = 0.001). Conclusion. The MWB fractures are an uninvestigated subtype of ankle fractures. The 1B type has a higher rate of malreduction, which could be due to its higher association with PM fractures. Tib post needs specific attention with these fracture types, especially Type 2 fractures


Orthopaedic Proceedings
Vol. 107-B, Issue SUPP_1 | Pages 17 - 17
10 Feb 2025
Vijapur A Shaath M Patel S Cullen N Welck M Malhotra K
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Aims. The distal metatarsal metaphyseal articular angle (DMMA) is a measurement used in the surgical decision making of hallux valgus correction. However, it is difficult to measure on plain radiographs, is subject to projection bias, and its role in pathology is unclear. With the advent of weight-bearing CT (WBCT), our understanding of hallux valgus as a multiplanar deformity has evolved. The aim of this study was to investigate whether there is a relationship between the DMAA and pronation of the first metatarsal head in patients with hallux valgus. Methods. This was a single-centre, retrospective analysis of 50 patients with hallux valgus deformity who had WBCTs obtained as part of routine pre-operative work-up. Patients with metatarsophalangeal joint arthritis, hindfoot deformity and previous surgery were excluded. From the WBCT images digital radiographs were created and the DMMA measured. Measurements were taken by 2 authors, each repeated twice and the average of all four measurements used in analysis. We also measured intermetatarsal angle (IMA), hallux valgus angle (HVA) and metatarsal pronation angle (MPA). Results. There were 41 females and 9 males, mean age 52.4±15.8 years. IMA was 14.5±3.3 degrees, HVA was 29.3±8.4 degrees, MPA was 11.7±6.3 degrees, and DMMA was 15.5±5.3 degrees. Intraclass correlation coefficient (ICC) for intra-observer reliability was 0.829 for assessor 1 and 0.910 for assessor 2. ICC for inter-observer reliability was 0.727. Pearsons correlation revealed no link between IMA and DMAA, nor HVA and DMMA. However, there was a significant (albeit small) correlation between MPA and DMMA (r=0.337, p=0.017). Conclusion. There was reasonable reliability in measuring DMMA between authors on WBCT. Despite this, DMMA appeared to increase with increasing metatarsal pronation. The DMMA may therefore be (in part) projection artefact secondary to metatarsal pronation and surgeons should be aware of this during surgical planning


Orthopaedic Proceedings
Vol. 107-B, Issue SUPP_1 | Pages 10 - 10
10 Feb 2025
Mangwani J See A Houchen-Wolloff L
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Introduction. The treatment of critical-sized bone defects in foot and ankle surgery remains challenging. Traditional methods, such as bone transport, bulk allograft, vascularized bone graft, and Masquelet procedures carry risks including multiple surgeries, donor site morbidity, infection, and non-union. Recently, custom 3D-printed implants have emerged, offering improved anatomical compatibility, eliminating the need for tissue harvesting, and often requiring only a single operation. This study aims to present the largest UK series of custom 3D-printed implants in foot and ankle surgery. Methods. A retrospective multicentre collaborative study was conducted in 10 NHS Trusts. Demographic, surgical and radiographic variables were recorded including: age; sex; side; type of operation; complications; and postop imaging at 6 weeks, 3 months, 6 months and 12 months. Baseline characteristics were described for demographic variables. Categorical variables were expressed as frequencies and percentages. Results. Data was collected on a total of 34 patients. The mean age of patients was 54 years (range 29 to 83). 68% of patients were men. Avascular necrosis was the most common indication for surgery (35%) followed by trauma (21%), total ankle replacement failure (21%), infection (12%), Charcot arthropathy (6%) and AVN and infection (3%). The most common operation performed was a fusion augmented with a truss (44%) and 91% of patients had a combination of regional and general anaesthetic. All patients had an ASA grade of less than 4. Of the patients that had follow-up imaging, the implants were reported intact by 94% at 6 weeks, 78% at 3 months, 68% at 6 months and 67% at 12 months. Discussion. This is the largest case series of custom-made foot and ankle implants in the UK to date. The clinical and radiographic outcomes at one year Follow-up are satisfactory. Further work is required to assess long term implant survivorship


Orthopaedic Proceedings
Vol. 107-B, Issue SUPP_1 | Pages 13 - 13
10 Feb 2025
Welck M Beer A Al-Omar H Najefi A Patel S Cullen N Koç T Malhotra K
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Aims. First metatarsal Pronation is increasingly recognised as an important component of Hallux valgus (HV) and can contribute towards intraoperative malreduction, postoperative recurrence and patient reported outcome measures (1,2,3). There are numerous radiological ways to measure metatarsal rotation on plain radiographs and weight bearing CT (WBCT), however there are no clinical tests to evaluate metatarsal pronation pre- or intra-operatively. This study therefore aimed to examine the relationship between clinical pronation of the toe and metatarsal pronation. Methods. Single-centre, retrospective analysis over 5 years. Measurements were performed on WBCT images with digital reconstructions to add soft tissues. First metatarsal rotation was measured using the Metatarsal Pronation Angle as previously described (4). Toe rotation was measured by the Phalangeal Condylar Angle (PCA), the angle between the condyles of the proximal phalanx and the floor, and the Nail Plate Angle (NPA), the angle of the base of the nail plate to the floor in the coronal Plane. These were obtained from 50 feet in Hallux valgus patients, and 50 control patients with CTs done for osteochondral lesions without hallux valgus or hindfoot malalignment. Results. The HV group comprised 41 women and 9 men, mean age 52.4. Control group, 23 women and 23 male, mean age 40.25. Inter and Intra Observer reliability both excellent (ICC &gt;0.95) for all measurements. When comparing HV vs control, MPA was 11.7 vs 6.0 (p&lt;0.001), PCA 31.8 vs 4.7 (p&lt;0.001), NPA 18.3 vs 6.0 (p&lt;0.0001). NPA correlated with PCA. NPA and PCA correlate with Hallux valgus Angle (p&lt;0.001), but not with MPA (p 0.567). Conclusion. These results suggest that clinical toe pronation increases as HV angle increases but not with metatarsal pronation, which therefore cannot be used as a clinical marker. Toe pronation is similar at the base and at the nail, suggesting rotation happens at the MTPJ


Bone & Joint Open
Vol. 6, Issue 2 | Pages 164 - 177
10 Feb 2025
Clement ND Scott CEH Macpherson GJ Simpson PM Leitch G Patton JT

Aims

Unicompartmental knee arthroplasty (UKA) is associated with an accelerated recovery, improved functional outcomes, and retention of anatomical knee kinematics when compared to manual total knee arthroplasty (mTKA). UKA is not universally employed by all surgeons as there is a higher revision risk when compared to mTKA. Robotic arm-assisted (ra) UKA enables the surgeon to position the prosthesis more accurately when compared to manual UKA, and is associated with improved functional outcomes and a lower early revision risk. Non-randomized data suggests that, when compared to mTKA, raUKA has a clinically meaningful greater functional benefit. This protocol describes a randomized controlled trial that aims to evaluate the clinical and cost-effectiveness of raUKA compared to mTKA for individuals with isolated medial compartment osteoarthritis (OA).

Methods

The total versus robotic-assisted unicompartmental knee arthroplasty (TRAKER) trial is a patient- and assessor-blinded, pragmatic parallel two-arm randomized superiority trial of adults undergoing elective primary knee arthroplasty for primary medial compartment OA at a single NHS hospital (ClinicalTrials.gov NCT05290818). Participants will be randomly allocated on a 1:2 basis to either raUKA or mTKA, respectively. The primary analysis will compare the Oxford Knee Score (OKS) six months after surgery. Secondary outcomes measured at three, six, and 12 months include the OKS, Forgotten Joint Score, patient expectations, EuroQol five-dimension questionnaire (EQ-5D), and EQ-visual analogue scale (EQ-VAS), patient satisfaction, range of motion, postoperative complications, need for further surgery, resource use, and financial costs. Cost-effectiveness will be measured over a ten-year time span. A total of 159 patients will be randomized (n = 53 raUKA vs n = 106 mTKA) to obtain 80% power to detect a five-point difference in OKS between the groups six months after surgery.


Bone & Joint Open
Vol. 6, Issue 2 | Pages 155 - 163
8 Feb 2025
Konishi T Hamai S Kawahara S Hara D Sato T Motomura G Utsunomiya T Nakashima Y

Aims

This study aimed to investigate whether the use of CT-based navigation enhances: 1) the accuracy of cup placement; and 2) the achievement rate of required range of motion (ROM). Additionally, we investigated the impact of using a large femoral head and dual-mobility liner on the achievement rates.

Methods

This retrospective study analyzed 60 manual and 51 CT-based navigated primary total hip arthroplasties performed at a single facility. Postoperative CT scans and CT-based simulation software were employed to measure the cup orientation and to simulate the ROM. We compared the absolute errors for radiological inclination (RI) and radiological anteversion (RA) between the two groups. We also examined whether the simulated ROM met the required ROM criteria, defined as flexion > 110°, internal rotation > 30°, extension > 30°, and external rotation > 30°. Furthermore, we performed simulations with 36 mm femoral head and dual-mobility liner.


Bone & Joint Open
Vol. 6, Issue 2 | Pages 135 - 146
6 Feb 2025
Sherratt FC Swaby L Walker K Jayasuriya R Campbell L Mills AJ Gardner AC Perry DC Cole A Young B

Aims

The Bracing Adolescent Idiopathic Scoliosis (BASIS) study is a randomized controlled non-inferiority pragmatic trial of ‘full-time bracing’ (FTB) compared to ‘night-time bracing’ (NTB) for the treatment of adolescent idiopathic scoliosis (AIS). We anticipated that recruiting patients to BASIS would be challenging, as it is a paediatric trial comparing two markedly different bracing pathways. No previous studies have compared the experiences of AIS patients treated with FTB to those treated with NTB. This qualitative study was embedded in BASIS to explore families’ perspectives of BASIS, to inform trial communication, and to identify strategies to support patients treated in a brace.

Methods

Semi-structured interviews were conducted with parents (n = 26) and young people (n = 21) who had been invited to participate in BASIS at ten of the 22 UK paediatric spine services in hospitals recruiting to BASIS. Audio-recorded interviews were transcribed and analyzed thematically.


Bone & Joint Research
Vol. 14, Issue 2 | Pages 93 - 96
6 Feb 2025
Wignadasan W Fontalis A Shaeir M Haddad FS


Bone & Joint Research
Vol. 14, Issue 2 | Pages 97 - 110
6 Feb 2025
Zhang D Zhu T Bai J Chen C Wen J Zhou Y Guan X

Aims

In our previous research, we have found that melatonin (MEL) affects the osteoporotic process. By balancing bone remoulding, autophagy is involved in age-related bone loss. However, as a regulator of autophagy, whether MEL influences senile osteoporosis via regulating autophagy remains unclear.

Methods

Cellular, radiological, and histopathological evaluations were performed on 36 16-month-old male C57BL6/L mice or aged bone marrow-derived mesenchymal stem cells. A MEL-gelatin methacrylamide system was constructed to aid osteoporotic fracture healing.


Bone & Joint Open
Vol. 6, Issue 2 | Pages 126 - 134
4 Feb 2025
Schneller T Kraus M Schätz J Moroder P Scheibel M Lazaridou A

Aims. Machine learning (ML) holds significant promise in optimizing various aspects of total shoulder arthroplasty (TSA), potentially improving patient outcomes and enhancing surgical decision-making. The aim of this systematic review was to identify ML algorithms and evaluate their effectiveness, including those for predicting clinical outcomes and those used in image analysis. Methods. We searched the PubMed, EMBASE, and Cochrane Central Register of Controlled Trials databases for studies applying ML algorithms in TSA. The analysis focused on dataset characteristics, relevant subspecialties, specific ML algorithms used, and their performance outcomes. Results. Following the final screening process, 25 articles satisfied the eligibility criteria for our review. Of these, 60% focused on tabular data while the remaining 40% analyzed image data. Among them, 16 studies were dedicated to developing new models and nine used transfer learning to leverage existing pretrained models. Additionally, three of these models underwent external validation to confirm their reliability and effectiveness. Conclusion. ML algorithms used in TSA demonstrated fair to good performance, as evidenced by the reported metrics. Integrating these models into daily clinical practice could revolutionize TSA, enhancing both surgical precision and patient outcome predictions. Despite their potential, the lack of transparency and generalizability in many current models poses a significant challenge, limiting their clinical utility. Future research should prioritize addressing these limitations to truly propel the field forward and maximize the benefits of ML in enhancing patient care. Cite this article: Bone Jt Open 2025;6(2):126–134


Bone & Joint Research
Vol. 14, Issue 2 | Pages 77 - 92
4 Feb 2025
Spanninga BJ Hoelen TA Johnson S Cheng B Blokhuis TJ Willems PC Arts JJC

Aims

Autologous bone graft (ABG) is considered the ‘gold standard’ among graft materials for bone regeneration. However, complications including limited availability, donor site morbidity, and deterioration of regenerative capacity over time have been reported. P-15 is a synthetic peptide that mimics the cell binding domain of Type-I collagen. This peptide stimulates new bone formation by enhancing osteogenic cell attachment, proliferation, and differentiation. The objective of this study was to conduct a systematic literature review to determine the clinical efficacy and safety of P-15 peptide in bone regeneration throughout the skeletal system.

Methods

PubMed, Embase, Web of Science, and Cochrane Library were searched for relevant articles on 13 May 2023. The systematic review was reported according to the PRISMA guidelines. Two reviewers independently screened and assessed the identified articles. Quality assessment was conducted using the methodological index for non-randomized studies and the risk of bias assessment tool for randomized controlled trials.


Bone & Joint Open
Vol. 6, Issue 2 | Pages 119 - 125
3 Feb 2025
Husum H Hellfritzsch MB Maimburg RD Møller-Madsen B Henriksen M Lapitskaya N Kold S Rahbek O

Aims

To establish cut-off values for lateral pubofemoral distance (PFD) measurements for detecting hip dysplasia in early (four days) and standard care (six weeks) screening for developmental dysplasia of the hip (DDH).

Methods

All newborns, during a one-year period (October 2021 to October 2022), were offered a PFD ultrasound (US) examination in addition to the existing screening programme for DDH. Newborns who were referred for standard care hip US, suspected for DDH, received a secondary PFD US examination in conjunction with the standard care Graf/Harcke hip US examination. Receiver operating characteristic curves and empirically optimal cut-off values were calculated with a true positive defined as a Graf type ≥ IIc hip.


Bone & Joint 360
Vol. 14, Issue 1 | Pages 15 - 18
1 Feb 2025

The February 2025 Hip & Pelvis Roundup360 looks at: Postoperative periprosthetic femoral fractures after hip arthroplasty: quantifying the other half of the picture; Hip arthroscopy in patients with borderline dysplasia: how do we know when it will not work?; The morbidly obese patient remains a challenge for arthroplasty surgeons; Unexpected positive cultures in aseptic revision hip and knee arthroplasty: does it make a difference?; Failed spinal anaesthesia in hip and knee arthroplasty surgery; Clinical failure of femoral neck fracture is associated with varus necks; Navigating the angles: how variations in femoral and acetabular versions influence hip pain and treatment; High-tech or hands-on? Similar outcomes in direct anterior total hip arthroplasty.


The Bone & Joint Journal
Vol. 107-B, Issue 2 | Pages 204 - 212
1 Feb 2025
Trouwborst NM Oldhoff MGE ten Duis K van Helden SH Hermans E Jaarsma RL van Lieshout EMM Reininga IHF Tromp TN Verhofstad MHJ de Vries JPM Wijffels MME Meesters AML IJpma FFA

Aims

The aim of the study was to apply 3D measurements for fracture displacement in minimally to moderately displaced acetabular fractures treated nonoperatively, and to evaluate whether this measurement can be used to estimate the likelihood of conversion to total hip arthroplasty (THA) at follow-up.

Methods

A multicentre, cross-sectional study was performed on 144 patients who were treated nonoperatively for an acetabular fracture in four level 1 trauma centres between January 2000 and December 2020. For each patient, fracture displacement was measured on CT-based 3D models. The 3D gap area represents fracture displacement (mm2) between all fracture fragments. A receiver operating characteristic curve was generated to determine a 3D gap area threshold representing the optimal sensitivity and specificity to predict conversion to THA. Native hip survival was reported using Kaplan-Meier curves. Predictors of conversion to THA were determined using Cox regression analysis.


Aims

Sagittal lumbar pelvic alignment alters with posterior pelvic tilt (PT) following total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH). The individual value of pelvic sagittal inclination (PSI) following rebalancing of lumbar-pelvic alignment is unknown. In different populations, PT regresses in a linear relationship with pelvic incidence (PI). PSI and PT have a direct relationship to each other via a fixed individual angle ∠γ. This study aimed to investigate whether the new PI created by acetabular component positioning during THA also has a linear regression relationship with PT/PSI when lumbar-pelvic alignment rebalances postoperatively in patients with Crowe type III/IV DDH.

Methods

Using SPINEPARA software, we measured the pelvic sagittal parameters including PI, PT, and PSI in 61 patients with Crowe III/IV DDH. Both PSI and PT represent the pelvic tilt state, and the difference between their values is ∠γ (PT = PSI + ∠γ). The regression equation between PI and PT at one year after THA was established. By substituting ∠γ, the relationship between PI and PSI was also established. The Bland-Altman method was used to evaluate the consistency between the PSI calculated by the linear regression equation (ePSI) and the actual PSI (aPSI) measured one year postoperatively.


Bone & Joint 360
Vol. 14, Issue 1 | Pages 46 - 47
1 Feb 2025

The February 2025 Research Roundup360 looks at: Walk your way to longer life: quantifying physical activity’s role in extending longevity; Is information about musculoskeletal malignancies from large language models or web resources at a suitable reading level for patients?; Contemporary surgical management of osteosarcoma and Ewing’s sarcoma; L-arginine and tendon healing; What you can’t hear might not stress you out as much.


Bone & Joint 360
Vol. 14, Issue 1 | Pages 7 - 10
1 Feb 2025
Ollivere B


The Bone & Joint Journal
Vol. 107-B, Issue 2 | Pages 188 - 192
1 Feb 2025
Tse S Van de Kelft A Simister SK Forster DA Lee M Prinja A Rajesparan K Rashid A

Aims. Complex elbow fracture-dislocations often result in suboptimal outcomes and necessitate a thorough understanding of injury patterns to guide effective management and reduce adverse sequelae. The Wrightington Classification System (WCS) offers a comprehensive approach and considers both bony and soft-tissue disruption, providing clearer guidance for treatment. This is the first external study to assess the reliability of the WCS for elbow fracture-dislocations. Methods. A blinded study of patients with elbow fracture-dislocations at a single institution between December 2014 and December 2022 was conducted. Five assessors with a range of experience, including orthopaedic surgeons and radiologists, independently classified injuries using the WCS across three image methods: plain radiograph, 2D CT, and 2D and 3D CT reconstruction images, on two occasions with an eight-week interval. Interobserver and intraobserver reliability were evaluated using kappa statistics and the Landis and Koch criteria. Results. A total of 73 patients were included in the study. Interobserver reliability was moderate, with mean kappa values of 0.518 (95% CI 0.499 to 0.537), 0.557 (95% CI 0.537 to 0.577), and 0.582 (95% CI 0.562 to 0.601), for radiographs, 2D CT, and 2D and 3D CT reconstructions, respectively. Intraobserver agreement was substantial (mean kappa 0.695 (SE 0.067), 0.729 (SE 0.071), and 0.777 (SE 0.070) for radiographs, 2D CT, and 3D CT reconstructions, respectively). Conclusion. The WCS is a reliable and valuable tool for characterizing elbow fracture-dislocations and guiding surgical interventions. This study found moderate reliability in using the WCS, with higher reliability with combined 2D and 3D CT imaging. Further refinement within the WCS in differentiating between coronoid avulsions, basal, anteromedial, and/or anterolateral facet injuries may help improve reliability and reproducibility. Cite this article: Bone Joint J 2025;107-B(2):188–192


Bone & Joint Research
Vol. 14, Issue 2 | Pages 69 - 76
1 Feb 2025
Tripon M Lalevee M van Rooij F Agu C Saffarini M Beaudet P

Aims. To evaluate how fore- and midfoot coronal plane alignment differs in feet with hallux valgus (HV), using 3DCT when measured in standard weightbearing (SWB) versus sesamoid view (SV) position, and to determine whether first metatarsophalangeal (MTP) dorsiflexion affects the relationship between the first metatarsal (M1) head and the sesamoid bones. Methods. A consecutive series of 34 feet that underwent 3DCT in SWB and SV positions for symptomatic HV was assessed, of which four feet were excluded for distorted or incomplete images. Two foot and ankle clinicians independently digitized a series of points, and measured a series of angles according to a pre-defined protocol. Measurements include navicular pronation angle, M1 head (Saltzman angle), and metatarsosesamoid rotation angle (MSRA). Results. The mean age of the 30 patients was 57.5 years (SD 13.4). The mean navicular pronation angle was significantly smaller in the SV position (9.6° (SD 4.4°)) compared to the SWB position (16.4° (SD 5.8°); p < 0.001). There was a difference in MSRA between the SWB and SV positions, revealing an increase in MSRA in 22 patients, while there was a decrease in eight patients. In patients where the MSRA increased, the mean Saltzman angle was 2.5° (SD 5.7°) lower in the SV position versus the SWB position, while in patients where MSRA decreased, the mean Saltzman angle was 3.4° (SD 3.6°) greater in the SV position versus the SWB position. Conclusion. MTP dorsiflexion causes supination of the navicular, while other first ray parameters remain unchanged, and has a greater influence on the M1 head coronal alignment than on the sesamoids. MTP dorsiflexion induces axial rotations of M1, which vary in direction and magnitude from one patient to another. Cite this article: Bone Joint Res 2025;14(2):69–76