Foot surgery for adults with Charcot-Marie-Tooth disease.

People with Charcot-Marie-Tooth (CMT) disease often undergo foot and ankle surgery, as foot deformities are common and cause a degree of functional limitations impairing quality of life. Surgical approaches are variable and there are no evidence-based guidelines. A multidisciplinary approach involving neurology, physical therapy and orthopaedic surgery is ideal to provide guidance on when to refer for surgical opinion and when to intervene. This review outlines the range of foot deformities associated with CMT, their clinical assessment, and their conservative and surgical and postoperative management.

Forefoot Morphotypes in Cavovarus Feet: A Novel Assessment of Deformity.

BACKGROUND: The cavovarus foot is a complex 3-dimensional deformity. Although a multitude of techniques are described for its surgical management, few of these are evidence based or guided by classification systems. Surgical management involves realignment of the hindfoot and soft tissue balancing, followed by forefoot balancing. Our aim was to analyze the pattern of residual forefoot deformities once the hindfoot is corrected, to guide forefoot correction. METHODS: We included 20 cavovarus feet from 16 adult patients with Charcot-Marie-Tooth who underwent weightbearing CT (mean age 43.4 years, range: 22-78 years, 14 males). Patients included had flexible deformities, with no previous surgery. Using specialized software (Bonelogic 2.1, Disior) a 3-dimensional, virtual model was created. Using morphologic data captured from normal feet in patients without pathology as a guide, the talonavicular joint of the cavovarus foot was digitally reduced to a "normal" position to simulate the correction that would be achieved during surgical correction. Models of the corrected position were exported and geometrically analyzed using Blender 3.64 to identify anatomical trends. RESULTS: We identified 4 types of cavovarus forefoot morphotypes. Type 0 was defined as a balanced forefoot (2 cases, 10%). Type 1 was defined as a forefoot where the first metatarsal was relatively plantarflexed to the rest of the foot, with no significant residual adduction after talonavicular joint correction (12 cases, 60%). Type 2 was defined as a forefoot where the second and first metatarsals were progressively plantarflexed, with no significant adduction (4 cases, 20%). Type 3 was defined as a forefoot where the metatarsals were adducted after talonavicular derotation (2 cases, 10%). CONCLUSION: In this relatively small cohort, we identified 4 forefoot morphotypes in cavovarus feet that might help surgeons to recognize and anticipate the residual forefoot deformities after hindfoot correction. Different treatment strategies may be required for different morphotypes to achieve balanced correction. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Classifications in adult pes cavus - A scoping review.

AIMS: The adult cavus foot represents a challenging clinical problem, with varied aetiology and complex, 3-dimensional deformities. Thus far, the cavus foot has eluded a unified classification. The aim of this paper was to appraise the literature to identify classification systems which guide the operative management of neurological cavus feet in adults. METHODS: As the aim of this paper was broad, a scoping review was conducted. The review was conducted in line with published frameworks. Our principal research question was 'what classification systems that guide surgical management currently exist for neurological cavus feet in adults'. We searched CINAHL, Embase, OVID, Proquest, Pubmed, Scopus and Web of Science databases using MESH and non-MESH terms. Two authors independently reviewed abstracts / papers and a data extraction sheet was used to collect the relevant data. RESULTS: A total of 1140 articles were initially screened, identifying 125 articles for which a full text review was performed. Only three articles met all our inclusion criteria. All these articles reported an anatomical classification with suggestions for treatment based on the classification. All were considered to comprise Level V evidence, and none reported outcomes of treatment based on the classification. CONCLUSIONS: There is currently a paucity of robust classifications to guide treatment in neurological cavus feet in adults. The few classifications systems that exist are varied and do not as yet have sufficient evidence to support their widespread use. Further work is required, aimed at identifying specific features of cavus feet that would guide operative treatment.

The position, orientation, and relative size of the fibularis longus tubercle in normal patients: A weightbearing CT assessment.

The fibularis longus attaches to the base of the first metatarsal at the fibularis/peroneus longus tubercle (FLT/PLT). Theoretically, differences in FLT morphology may reflect changes in the function of the fibularis longus. This study defines the normal limits of the FLT position, orientation, and size in patients with morphologically normal foot anatomy. A retrospective analysis of 131 feet without deformity in 72 patients undergoing weightbearing CT (WBCT) at a single center was conducted. The position and morphology of the FLT was assessed with novel measurements including tubercle-floor distance, tubercle-metatarsal angle, and the angle between the floor and a line bisecting the FLT (bisecting angle). Roundness of the FLT was compared to a triangle limiting its shape (triangular ratio), with lower values indicating increasing roundness. We also report relative size of the FLT to the first metatarsal (X/Y ratio), and relative size of the first metatarsal and FLT to the second metatarsal (XY/Z ratio). There were no significant side to side differences for any measurement (p > 0.05). Mean values were: tubercle-floor distance 28.02 ± 2.63 mm, tubercle-metatarsal angle 32.7 ± 6.32 degrees, bisecting angle 65.58 ± 6.27 degrees, triangular ratio 0.69 ± 0.04, X/Y ratio 1.13 ± 0.20, and XY/Z ratio 3.44 ± -0.72. Bisecting angle strongly correlated with tubercle-metatarsal angle (Pearson correlation 0.840, p < 0.001) suggesting FLT rotation occurred independent of foot position. ICC was >0.943 for all measurements. This study reports the morphology of the FLT in individuals with normal feet. This normative data may be used in future studies examining differences between groups of patients with foot pathology, helping us better understand the role of fibularis longus in the development and treatment of foot disorders.

Talar neck rotation angle in adults with clubfoot deformity: Observed values and intra- and inter-observer reliability using weightbearing CT.

INTRODUCTION: Adults presenting with symptomatic clubfoot represent a challenging cohort of patients. An appreciation of the location and degree of deformities is essential for management. Talar anatomy is often abnormal with varus within the talar neck, however, there are few reproducible methods which quantify talar neck deformity in adults. We describe a technique of assessing talar neck deformity, and report on observed values and intra- / inter-observer reliability. METHODS: This was a single-centre, retrospective study including 96 feet from 56 adult patients with clubfeet (82 feet had clubfoot deformity, 14 were normal). Mean age was 34.3 ± 16.9 years and 31 (55.3%) were male. Weight-bearing CT scans captured as part of routine clinical care were analysed. Image reformats were oriented parallel to the long axis of the talus in the sagittal plane. In the corresponding axial plane two lines were drawn (on separate slices): 1) a line perpendicular to the intermalleolar axis, 2) a line connecting the midpoints of the talar head and narrowest part of the talar neck. The talar neck rotation angle (TNR angle) was the angle formed between these lines. Intraclass correlation coefficients (ICC) were performed for intra- and inter-observer reliability. RESULTS: Mean TNR angle in clubfeet was 27.6 ± 12.2 degrees (95%CI = 25.0 to 30.2 degrees). Mean TNR angle in normal feet was 18.7 ± 5.1 degrees (95%CI = 16.0 to 21.4 degrees) (p < 0.001). The ICC for clubfeet was 0.944 (95%CI = 0.913 to 0.964) for intra-observer agreement, and 0.896 (95%CI = 0.837 to 0.932) for inter-observer agreement. CONCLUSION: This measurement technique demonstrated excellent intra- and inter-observer agreement. It also demonstrated that compared to normal feet, clubfeet had about 9 degrees of increased varus angulation of the talar neck. This technique and data may be used for future research into clubfoot deformity and in planning treatment. LEVEL OF CLINICAL EVIDENCE: 3.

Hindfoot Fusions in the Cavovarus Foot: What Is the Key for a Successful Outcome?

The aim of hindfoot fusions in the cavovarus foot is to establish a painless, plantigrade, balanced and stable foot. A comprehensive clinical and radiographic assessment enables the surgeon to fully understand the patient's deformity and plan a reliable surgical strategy for deformity correction. Pre-operative planning and intraoperative techniques are discussed.

Outcomes of Tenosynovial Giant Cell Tumor of the Foot and Ankle.

BACKGROUND: Tenosynovial giant cell tumor (TGCT) is a benign proliferative disease affecting synovial membranes. There are 2 forms, localized (L-TGCT) and diffuse (D-TGCT), which although histologically similar behave differently. It is locally invasive and is treated in most cases by operative excision. The aim of this study was to assess current practice, how the patients' presentation affected their outcome, as well as review the recurrence rates and complications. METHODS: A retrospective analysis of 123 cases was performed in patients treated between 2003 and 2019 with TGCT of the foot and/or ankle. Data were collected on age at presentation, radiologic pattern of disease, location of disease, treatment provided, and recurrence rates. The minimum follow-up was 2 years with a mean of 7.7 years. RESULTS: There were 61.7% female patients with a mean age of 39 (range, 11-76) years. L-TGCT accounted for 85 (69.1%) cases and D-TGCT for 38 (30.9%). The most prevalent preoperative symptoms were a palpable mass (78/123) and pain (65/123). Radiologically confirmed recurrence in the operative group was noted in 14.5% (16/110) cases. This comprised 4% (3/75) of operatively treated L-TGCT and 37% (13/35) of operatively treated D-TGCT. Patients with pain on presentation and those with erosive changes on presenting magnetic resonance imaging (MRI) were more likely to have persistent postoperative pain (P < .001 for both). Where patients had both preoperative pain and erosive changes, 57.1% had postoperative pain. Thirteen cases were managed nonoperatively where symptoms were minimal, with 1 case requiring surgery at a later date. CONCLUSION: Outcomes of TGCT management are dependent on the disease type, extent of preoperative erosive changes, and presence of preoperative pain. These data are useful for counseling patients regarding the outcomes of surgical intervention and help guide the timing of intervention. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Ankle Joint Bone Density Distribution Correlates with Overall 3-Dimensional Foot and Ankle Alignment.

BACKGROUND: Altered stress distribution in the lower limb may impact bone mineral density (BMD) in the ankle bones. The purpose of the present study was to evaluate the spatial distribution of BMD with use of weight-bearing cone-beam computed tomography (WBCT). Our hypothesis was that BMD distribution would be even in normal hindfeet, increased medially in varus hindfeet, and increased laterally in valgus hindfeet. METHODS: In this study, 27 normally aligned hindfeet were retrospectively compared with 27 valgus and 27 varus-aligned hindfeet. Age (p = 0.967), body mass index (p = 0.669), sex (p = 0.820), and side (p = 0.708) were similar in the 3 groups. Hindfoot alignment was quantified on the basis of WBCT data sets with use of multiple measurements. BMD was calculated with use of the mean Hounsfield unit (HU) value as a surrogate. The HU medial-to-lateral ratio (HUR), calculated from tibial and talar medial and lateral half-volumes, was the primary outcome of the study. RESULTS: The 3 groups significantly differed (p < 0.001) in terms of tibial HUR (median, 0.91 [interquartile range (IQR), 0.75 to 0.98] in valgus hindfeet, 1 [IQR, 0.94 to 1.05] in normal hindfeet, and 1.04 [IQR, 0.99 to 1.1] in varus hindfeet) and talar HUR (0.74 [IQR, 0.50 to 0.80] in valgus hindfeet, 0.82 [IQR, 0.76 to 0.87] in normal hindfeet, and 0.92 [IQR, 0.86 to 1.05] in varus hindfeet). Linear regression showed that all hindfoot measurements significantly correlated with tibial and talar HUR (p < 0.001 for all). The mean HU values for normally-aligned hindfeet were 495.2 ± 110 (medial tibia), 495.6 ± 108.1 (lateral tibia), 368.9 ± 80.3 (medial talus), 448.2 ± 90.6 (lateral talus), and 686.7 ± 120.4 (fibula). The mean HU value for each compartment was not significantly different across groups. CONCLUSIONS: Hindfoot alignment and medial-to-lateral BMD distribution were correlated. In varus hindfeet, an increased HU medial-to-lateral ratio was consistent with a greater medial bone density in the tibia and talus as compared with the lateral parts of these bones. In valgus hindfeet, a decreased ratio suggested greater bone density in the lateral as compared with the medial parts of both the tibia and the talus. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

3-D joint space mapping at the ankle from weight-bearing CT: reproducibility, repeatability, and challenges for standardisation.

OBJECTIVES: We present a 3-D approach to joint space width (JSW) measurement across the ankle from weight-bearing CT (WBCT) to demonstrate inter-operator reproducibility, test-retest repeatability, and how differences in angulation affect ankle JSW distribution. METHODS: One side from repeat WBCT imaging of both feet and ankles was analysed from 23 individuals as part of their routine clinical care pathway. Joint space mapping was performed at four facets across the talus: talonavicular, talar dome and medial gutter (dome-medial), lateral gutter, and posterior subtalar. Inter-operator reproducibility was calculated for two users, while test-retest repeatability was calculated by comparing the two visits, both presented as Bland-Altman statistics. Statistical parametric mapping determined any significant relationships between talocrural joint space angulation and 3-D JSW distribution. RESULTS: The average ± standard deviation interval between imaging was 74.0 ± 29.6 days. Surface averaged bias ± limits of agreement were similar for reproducibility and repeatability, the latter being: talonavicular 0.01 ± 0.26 mm, dome-medial 0.00 ± 0.28 mm, lateral gutter - 0.02 ± 0.40 mm, and posterior subtalar 0.02 ± 0.34 mm. Results are presented as 3-D distribution maps, with optimum test-retest repeatability reaching a smallest detectable difference of ± 0.15 mm. CONCLUSIONS: Joint space mapping is a robust approach to 3-D quantification of JSW measurement, inter-operator reproducibility, and test-retest repeatability at the ankle, with sensitivity reaching a best value of ± 0.15 mm. Standardised imaging protocols and optimised metal artefact reduction will be needed to further understand the clinical value of these 3-D measures derived from WBCT. CLINICAL RELEVANCE STATEMENT: Weight-bearing computed tomography is an increasingly important tool in the clinical assessment of orthopaedic ankle disorders. This paper establishes the performance of measuring 3-D joint space width using this technology, which is an important surrogate marker for severity of osteoarthritis. KEY POINTS: • Joint space width values and error metrics from across the ankle measured from weight-bearing CT can be presented as 3-D maps that show topographic variation. • The best sensitivity for detecting meaningful change in 3-D joint space width at the ankle was ± 0.15 mm, a value less than the isotropic imaging voxel dimensions. • Standardised imaging protocols and optimised metal artefact reduction will be needed to understand the clinical value of 3-D measures from weight-bearing CT.

First Metatarsal Rotation After Scarf Osteotomy for Hallux Valgus.

BACKGROUND: Recurrence after surgical correction of hallux valgus may be related to coronal rotation of the first metatarsal. The scarf osteotomy is a commonly used procedure for correcting hallux valgus but has limited ability to correct rotation. Using weight-bearing computed tomography (WBCT), we aimed to measure the coronal rotation of the first metatarsal before and after a scarf osteotomy, and correlate these to clinical outcome scores. METHODS: We retrospectively analyzed 16 feet (15 patients) who had a WBCT before and after scarf osteotomy for hallux valgus correction. On both scans, hallux valgus angle (HVA), intermetatarsal angle (IMA), and anteroposterior/lateral talus-first metatarsal angle were measured using digitally reconstructed radiographs. Metatarsal pronation angle (MPA), alpha angle, sesamoid rotation angle, and sesamoid position were measured on standardized coronal WBCT slices. Preoperative and postoperative (12 mo) clinical outcome scores (Manchester Oxford Foot Questionnaire and Visual Analogue Scores) were captured. RESULTS: Mean HVA was 28.6 ± 10.1° preoperatively and 12.1 ± 7.7° postoperatively (P < .001). Mean IMA was 13.7 ± 3.8° preoperatively and 7.5 ± 3.0° postoperatively (P < .001). Before and after surgery, there were no significant differences in MPA (11.4 ± 7.7 and 11.4 ± 9.9°, respectively; P = .75) or alpha angle (10.9 ± 8.0 and 10.7 ± 13.1°, respectively; P = .83). There were significant improvements in sesamoid rotation angle (SRA) (26.4 ± 10.2 and 15.7 ± 10.2°, respectively; P = .03) and sesamoid position (1.4 ± 1.0 and 0.6 ± 0.6, respectively; P = .04) after a scarf osteotomy. There were significant improvements in all outcome scores after surgery. Poorer outcome scores correlated with greater postoperative MPA and alpha angles (r = .76 (P = .02) and .67 (P = .03), respectively). CONCLUSION: A scarf osteotomy does not correct first metatarsal coronal rotation, and worse outcomes are linked to greater postoperative metatarsal rotation. Rotation of the metatarsal needs to be measured and considered when planning hallux valgus surgery. Further work was needed to compare postoperative outcomes with rotational osteotomies and modified Lapidus procedures when addressing rotation.Level of Evidence: 4.

Assessing the coronal plane deformity in Charcot Marie Tooth Cavovarus feet using automated 3D measurements.

BACKGROUND: This study assesses the coronal-plane deformities in cavovarus feet secondary to Charcot-Marie-Tooth disease (CMT) using Weightbearing-CT (WBCT) and semi-automated 3D-segmentation software. METHODS: WBCTs from 30 CMT-cavovarus feet were matched to 30 controls and analysed using semi-automatic 3D-segmentation (Bonelogic, DISIOR). The software used automated cross-section sampling with subsequent straight-line representation of weighted centre points to calculate 3D axes of bones in the hindfoot, midfoot and forefoot. Coronal relationships of these axes were analysed. Supination/pronation of the bones in relation to the ground and within each joint were measured and reported. RESULTS: The most significant deformity in CMT-cavovarus feet occurred at the talonavicular joint (TNJ) with 23 degrees more supination than normal feet (6.4 ± 14.5 versus 29.4 ± 7.0 degrees, p < 0.001). This was countered by relative pronation at the naviculo-cuneiform joints (NCJ) of 7.0 degrees (-36.0 ± 6.6 versus -43.0 ± 5.3 degrees, p < 0.001). Combined hindfoot varus and TNJ supination resulted in an additive supination effect not compensated by NCJ pronation. The cuneiforms in CMT-cavovarus feet were therefore supinated by 19.8 degrees to the ground relative to normal feet (36.0 ± 12.1 versus 16.2 ± 6.8 degrees, p < 0.001). The forefoot-arch and 1st metatarsal-ground angles demonstrated similar supination to the cuneiforms suggesting no further significant rotation occurred distally. CONCLUSION: Our results demonstrate coronal plane deformity occurs at multiple levels in CMT-cavovarus feet. Majority of the supination arises at the TNJ, and this is partially countered by pronation distally, mainly at the NCJ. An understanding of the location of coronal deformities may help when planning surgical correction. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

What is the best fixation technique for isolated talonavicular arthrodesis? - A systematic review.

Talonavicular arthrodesis is associated with a rate of non-union that ranges from 3 % to 37 %. Various fixation devices have been reported for talonavicular arthrodesis including screws, staples, plates, K-wires and intraosseous fix systems, however there is no definitive gold standard. This systematic review aims to compare clinical outcomes between different fixation devices for talonavicular arthrodesis. METHODS: MEDLINE, EMBASE, CENTRAL and Google Scholar were reviewed for studies reporting on outcomes of different fixation techniques for talonavicular arthrodesis indicated for osteoarthritis, inflammatory and post-traumatic arthritis from 1946 to 2021. The primary outcome measure was union rate. Secondary outcome measures included functional improvement, cost, quality of life and patient satisfaction. RESULTS: 9 articles involving 141 cases of talonavicular arthrodesis were identified. Fusion rates were as follows: screw fixation (n = 75): 87.5 % to 100 %, staple fixation (n = 13): 100 %, intraosseous fix system (n = 16): 100 %, and K-wire fixation (n = 2): 100 %. One study utilised a dorsal locking plate with two supplemented compression screws (n = 9, fusion rate= 100 %) and two studies used a combination of screws with staples (n = 26, fusion rate= 96 %). 7 of 9 studies measured functional outcomes and pain relief with improvement demonstrated in all fixation techniques. Quality of life, satisfaction and cost were inadequately reported amongst the included studies. All studies were rated as serious risk of bias. CONCLUSION: This systematic review consolidates the evidence for outcomes of different fixation techniques for TN arthrodesis, however a definitive judgement regarding the best fixation technique is unobtainable from current clinical evidence, due to lack of high-quality studies. With review of biomechanical studies and the limited clinical data, fixation with plate plus screw is most promising and would warrant further comparative study. LEVEL OF EVIDENCE: IV.

Semi-automated 3-dimensional analysis of the normal foot and ankle using weight bearing CT - A report of normal values and bony relationships.

BACKGROUND: Foot and ankle deformities have translational and rotational components in multiple planes, at multiple levels. Semi-automatic segmentation is a relatively new technology, which when used with weight-bearing CT (WBCT), can build an accurate model of the foot and calculate the orientation and relationships of bones under physiological load. However, few papers report reference values using these techniques. We report normative values for key bony relationships based on semi-automated analysis of WBCT. METHODS: This was a single-centre, retrospective analysis of 100 feet without deformity from 55 adult patients undergoing WBCT as part of routine clinical activity (mean age 40.5 ± 17.3 years). Imaging was analysed using Bonelogic 2.1 (DISIOR, Finland). Semi-automatic segmentation was used to compute the various bony axes in 3-dimensional space. Selected coronal, axial and sagittal plane relationships were then calculated for bones of the hindfoot, midfoot and forefoot. RESULTS: Data is presented on axial and sagittal plane relationships between the metatarsals in the forefoot, and the metatarsals and cuneiforms in the midfoot. In the hindfoot, the calcaneal pitch, talar-first-metatarsal angles, talonavicular coverage angles and Saltzman angles are reported. Coronal plane axes and their relationships are reported at multiple levels from hindfoot to forefoot. Results are presented as mean values with standard deviations and 95% confidence intervals. CONCLUSIONS: We present an observational analysis of the normal values from non-deformed feet. We highlight the major relationships in the axial, sagittal and coronal planes as obtained by semi-automated analysis of WBCT. This data may serve as a reference for future research. LEVEL OF EVIDENCE: Basic science study.

Total Ankle Replacement Versus Arthrodesis for End-Stage Ankle Osteoarthritis: A Randomized Controlled Trial.

BACKGROUND: End-stage ankle osteoarthritis causes severe pain and disability. There are no randomized trials comparing the 2 main surgical treatments: total ankle replacement (TAR) and ankle fusion (AF). OBJECTIVE: To determine which treatment is superior in terms of clinical scores and adverse events. DESIGN: A multicenter, parallel-group, open-label randomized trial. (ISRCTN registry number: 60672307). SETTING: 17 National Health Service trusts across the United Kingdom. PATIENTS: Patients with end-stage ankle osteoarthritis, aged 50 to 85 years, and suitable for either procedure. INTERVENTION: Patients were randomly assigned to TAR or AF surgical treatment. MEASUREMENTS: The primary outcome was change in Manchester-Oxford Foot Questionnaire walking/standing (MOXFQ-W/S) domain scores between baseline and 52 weeks after surgery. No blinding was possible. RESULTS: Between 6 March 2015 and 10 January 2019, a total of 303 patients were randomly assigned; mean age was 68 years, and 71% were men. Twenty-one patients withdrew before surgery, and 281 clinical scores were analyzed. At 52 weeks, the mean MOXFQ-W/S scores improved for both groups. The adjusted difference in the change in MOXFQ-W/S scores from baseline was -5.6 (95% CI, -12.5 to 1.4), showing that TAR improved more than AF, but the difference was not considered clinically or statistically significant. The number of adverse events was similar between groups (109 vs. 104), but there were more wound healing issues in the TAR group and more thromboembolic events and nonunion in the AF group. The symptomatic nonunion rate for AF was 7%. A post hoc analysis suggested superiority of fixed-bearing TAR over AF (-11.1 [CI, -19.3 to -2.9]). LIMITATION: Only 52-week data; pragmatic design creates heterogeneity of implants and surgical techniques. CONCLUSION: Both TAR and AF improve MOXFQ-W/S and had similar clinical scores and number of harms. Total ankle replacement had greater wound healing complications and nerve injuries, whereas AF had greater thromboembolism and nonunion, with a symptomatic nonunion rate of 7%. PRIMARY FUNDING SOURCE: National Institute for Health and Care Research Heath Technology Assessment Programme.

An update on imaging of tarsal tunnel syndrome.

Tarsal tunnel syndrome (TTS) is an entrapment neuropathy of the tibial nerve (TN) within the tarsal tunnel (TT) at the level of the tibio-talar and/or talo-calcaneal joints. Making a diagnosis of TTS can be challenging, especially when symptoms overlap with other conditions and electrophysiological studies lack specificity. Imaging, in particular MRI, can help identify causative factors in individuals with suspected TTS and help aid surgical management. In this article, we review the anatomy of the TT, the diagnosis of TTS, aetiological factors implicated in TTS and imaging findings, with an emphasis on MRI.

2D Manual vs 3D Automated Assessment of Alignment in Normal and Charcot-Marie-Tooth Cavovarus Feet Using Weightbearing CT.

BACKGROUND: The complex deformities in cavovarus feet may be difficult to assess and understand. Weightbearing computed tomography (WBCT) is increasingly used in evaluating complex deformities. However, the bone axes may be difficult to calculate in the setting of severe deformity. Computer-assisted 3D axis calculation is a novel approach that may allow for more accurate assessment of foot alignment or deformity. This study aimed to assess differences in measurements done manually on 2D slices of WBCT vs 3D computer models in normal and cavus feet. METHODS: We retrospectively analyzed WBCT scans from 16 normal and 16 cavus feet in patients with Charcot-Marie-Tooth disease. Six measurements were assessed: talar-first metatarsal angle (axial plane), forefoot arch angle (coronal plane), and Meary angle, calcaneal pitch, and cuneiform and navicular to floor distances (sagittal plane). 2D measurements were performed manually and 3D measurements were performed using specialized software (Bonelogic, DISIOR). Bland-Altman plots and linear regression were used to analyze differences. RESULTS: There were no significant biases in measured variables in normal feet. In the cavovarus group, automated assessment calculated increased sagittal plane deformity (fixed bias 7.31 degrees for Meary angle, 2.39 degrees for calcaneal pitch) and less axial plane deformity (fixed bias 10.61 degrees for axial talar-first metatarsal angle). The latter also demonstrated proportional bias indicating greater discrepancy with increasing adduction. CONCLUSION: Measurements were comparable in normal feet suggesting automated techniques can reliably assess the alignment of bony axes. However, automated calculations show greater sagittal and less axial deformity in cavovarus feet than measured by manual techniques. This discrepancy may relate to rotational deformity seen in cavovarus feet, which may not be easily assessed manually. 3D automated measurements may therefore play a role in better assessing and classifying the cavovarus foot, which may ultimately inform treatment algorithms. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Side-to-Side Difference of Metatarsal Rotation in Normal Individuals.

BACKGROUND: A previous study defined the normal first metatarsal pronation angle (MPA) as <16 degrees and normal α angle as <18 degrees. The primary purpose of this study was to assess the side-to-side variation in first metatarsal pronation between feet in normal individuals. METHODS: MPA and α angles were measured on standardized coronal weightbearing computed tomography slices. Pairedt tests were used to test significance of mean side-to-side differences in a population of 63 normal, asymptomatic individuals. RESULTS: The mean side-to-side difference in first metatarsal pronation was 4.3 degrees (95% CI 3.3, 5.2 degrees) for MPA and 4.9 degrees (95% CI 3.8, 6.0 degrees) for α angle. The normative range for side-to-side difference was calculated as 12 degrees for MPA and 14 degrees for α angle, as defined by 2 SDs from the mean. CONCLUSION: In a cohort of normal patients, the mean difference in first metatarsal pronation between sides was approximately 4 to 5 degrees based on MPA and α angle. However, considerable variation in differences was observed. These findings may be considered when assessing first metatarsal pronation using population-based values as it may influence thresholds for identifying pathology in an individual.

Extracorporeal shock wave treatment in foot and ankle fracture non-unions - A review.

BACKGROUND: The authors reviewed the current evidence and conducted a comprehensive review on the use of extracorporeal shock wave therapy (ESWT) in the treatment of foot and ankle fracture non-unions. METHODS: Four databases were searched to identify relevant studies in the available literature. RESULTS: Eight studies were reviewed, demonstrating union rates of 65%-100% and 90-100% at 3- and 6-months following ESWT treatment respectively. No major complications were seen in any of the studies. Minor complications included local soft tissue swelling, petechiae, bruising and pain. CONCLUSIONS: The literature that is currently available is limited to case series of relatively small sample sizes, highlighting the need for a prospective randomised controlled trial to further investigate the efficacy of ESWT in the treatment of foot and ankle fracture non-unions.

Imaging Findings and First Metatarsal Rotation in Hallux Valgus.

BACKGROUND: Failure to identify and correct malrotation of the first metatarsal may lead to recurrent hallux valgus deformity. We aimed to identify the proportion of hallux valgus patients with increased first metatarsal pronation using weightbearing computed tomography (WBCT) and to identify the relationship with conventional radiographic measurements. METHODS: WBCT scans were analyzed for 102 feet with a hallux valgus angle (HVA) and intermetatarsal angle (IMA) greater than or equal to 16 and 9 degrees, respectively. Metatarsal pronation angle (MPA), alpha angle, sesamoid rotation angle (SRA), and sesamoid position were measured on standardized coronal WBCT slices. Pronation was recorded as positive. Hindfoot alignment angle (HAA) was assessed using dedicated software. Pearson correlation and multiple regression analyses were used to assess differences between groups. RESULTS: Mean HVA was 29.8±9.4 degrees and mean IMA was 14.1±3.7 degrees. Mean MPA was 11.9±5.8 (range 0-26) degrees and mean alpha angle was 11.9±6.8 (range -3 to 29) degrees. In a previous study, we demonstrated the upper limit of normal MPA as 16 degrees and alpha angle as 18 degrees. Based on these criteria, we identified abnormal metatarsal pronation in 32 feet (31.4%). We found a strong positive correlation between SRA and HVA/IMA (R = 0.67/0.60, respectively, P < .001). IMA and HAA weakly correlated with MPA and alpha angle (IMA: R = 0.26/0.27, respectively, P < .01; HAA: R = 0.26/0.27, respectively, P < .01). Regression analyses suggested that increasing IMA was the most significant radiographic predictor of increased pronation. In this cohort, there was no correlation between HVA or sesamoid position and MPA / alpha angle (HVA: P = .36/.12, respectively, sesamoid position, P = .86/.77, respectively). CONCLUSION: In this cohort of 102 feet that met plain radiographic criteria for hallux valgus deformity, first metatarsal pronation was found abnormal in 31.4% of patients. We found a weak association between the IMA and hindfoot valgus, but not the HVA.

The use of intramedullary devices for fixation of metatarsal osteotomies in hallux valgus surgery - A systematic review.

BACKGROUND: Hallux valgus is a common foot condition with numerous surgical techniques described. Minimally invasive surgery is becoming more popular, with resultant development of suitable fixation devices. The aim of this systematic review was to evaluate the evidence on the use of intramedullary devices in hallux valgus first metatarsal corrective osteotomies, and describe clinical and radiological outcomes, with an overview of techniques and implants used. METHODS: We searched PubMed, Medline, Embase and EMCare databases, conforming to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Radiological outcomes including the hallux valgus angle (HVA) and intermetatarsal angle (IMA) were recorded, as well as clinical outcome scores and complications. Methodological quality of included studies was assessed using the MINORS score. RESULTS: Ten studies were included, comprising 696 feet in 745 patients. Data pooling and metanalysis was not possible due to overall low quality of evidence. Four implants were reported (Endolog, ISO Plate, V-Tek Plate, Link Fixator) and used with distal first metatarsal osteotomies, with improvement in HVA, IMA, and clinical outcome scores comparable to other fixation techniques. There were no reported cases of non-union. Complication rates were variable (all cause range of 0-21%) across all studies, with an overall low rate. CONCLUSION: Intramedullary devices are viable and safe to use for hallux valgus first metatarsal osteotomies, with comparable radiological and functional outcomes to other techniques. Current evidence base is of low methodological quality, therefore high quality studies are required to further evaluate these devices.