The Linear Hallux Valgus Offsete A novel way to measure Hallux Valgus A. Saad a , Karthikeyan P. Iyengar c , John Fitzpatrick b , C. Azzopardi b , H. Panchal d , R. Botchu b, * a Department of Orthopaedics, Royal Orthopaedic Hospital, Birmingham, UK b Department of Musculoskeletal Radiology, Royal Orthopaedic Hospital, Birmingham, UK c Southport and Ormskirk NHS Trust, Southport, UK d Sanyapixel Diagnostics, Ahmedabad, India article info Article history: Received 5 February 2022 Received in revised form 29 April 2022 Accepted 11 May 2022 Available online 18 May 2022 Keywords: Hallux valgus Bunion Radiography Hallux valgus angle Intermetatarsal angle Reliability abstract Introduction: Hallux Valgus (HV) is a complex deformity involving the first ray of the forefoot and a common cause of forefoot pain. Several radiological measurements such as Hallux Valgus Angle (HVA), First Metatarsophalangeal Angle (IMA) and Distal metatarsal articular angle (DMAA) exist to calculate the severity of HV and direct patient management. However, these are angular measurements are prone to error with variable intra- and inter-observer reliability. Purpose: To describe a new radiological linear hallux valgus offset (LHVO) to measure HV deformity. Patient and methods: We performed a retrospective cohort study looking at Antero-posterior, weight- bearing foot radiographs of 100 consecutive patients with forefoot pain referred to our foot and ankle clinic. Demographic details, clinical indication, HVA (hallux valgus angle) and LHVO were measured for each patient and data were analyzed using the student t-test. Intraclass Correlation Coefficient (ICC) analysis was evaluated to assess the intra-class reliability between observers. Results: There was a female predominance of approximately 2:1, with 51.3 years (range 13e86 years). There was a statistically significant difference of LHVO between normal and hallux valgus cohorts with a p-value of 0.0001. The LHVO gave moderate intra-observer and inter-observer reliability on ICC analysis of 0.7. Conclusion: The LHVO can be an additional measure of assessing severity of hallux valgus. In contrary to the traditional angular measurements, this linear measure is easier to calculate and reproducible on plain, weight bearing radiographs. LHVO measurement has shown a moderate inter-observer reliability in the study to complement traditional radiological evaluation of hallux valgus alignment. © 2022 Delhi Orthopedic Association. All rights reserved. 1. Introduction Hallux Valgus (HV), either adult or adolescent, is a common, complex deformity of the first ray of the forefoot. 1 It is described by medial angulation of the first metatarsal and the lateral deviation of the proximal phalanx at the level of the first metatarsophalangeal (MTP) joint. 2,3 Adolescent or Juvenile HV is often bilateral, and patients may present with significant angular deformities involving the first ray at the articular level. This primarily leads to cosmetic complaints and is commonly associated with flatfoot or hypermo- bility features. 4,5 Contrary to Adult HV, which is often insidious, developing over a prolonged period of time, typically affecting middle-aged and older women, and attributed to wearing constrictive footwear. 6 HV deformity, commonly referred to as a bunion, is a recognized cause of forefoot pain and can lead to foot malignment, inability to wear appropriate footwear, loss of function and disability in affected patients. 7 The aetiology of HV is multifactorial. The intrinsic factors such as pes planus, generalised joint laxity, hypermobility of the first ray articulations, arthropathies and neuromuscular disorders and extrinsic factors such as footwear, hereditary predisposition have been associated with the development of HV. 8 The pathophysiology * Corresponding author. Royal Orthopaedic Hospital, Bristol Road South North- field, Birmingham, UK. E-mail address: [email protected] (R. Botchu). Contents lists available at ScienceDirect Journal of Clinical Orthopaedics and Trauma journal homepage: www.elsevier.com/locate/jcot https://doi.org/10.1016/j.jcot.2022.101898 0976-5662/© 2022 Delhi Orthopedic Association. All rights reserved. Journal of Clinical Orthopaedics and Trauma 30 (2022) 101898
The Linear Hallux Valgus Offsete A novel way to measure Hallux Valgus
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The Linear Hallux Valgus Offset- A novel way to measure Hallux ValgusContents lists avai
journal homepage: www.elsevier .com/locate/ jcot
The Linear Hallux Valgus Offsete A novel way to measure Hallux Valgus
A. Saad a, Karthikeyan P. Iyengar c, John Fitzpatrick b, C. Azzopardi b, H. Panchal d, R. Botchu b, *
a Department of Orthopaedics, Royal Orthopaedic Hospital, Birmingham, UK b Department of Musculoskeletal Radiology, Royal Orthopaedic Hospital, Birmingham, UK c Southport and Ormskirk NHS Trust, Southport, UK d Sanyapixel Diagnostics, Ahmedabad, India
a r t i c l e i n f o
Article history: Received 5 February 2022 Received in revised form 29 April 2022 Accepted 11 May 2022 Available online 18 May 2022
Keywords: Hallux valgus Bunion Radiography Hallux valgus angle Intermetatarsal angle Reliability
* Corresponding author. Royal Orthopaedic Hospit field, Birmingham, UK.
E-mail address: [email protected] (R. Botchu)
https://doi.org/10.1016/j.jcot.2022.101898 0976-5662/© 2022 Delhi Orthopedic Association. All
a b s t r a c t
Introduction: Hallux Valgus (HV) is a complex deformity involving the first ray of the forefoot and a common cause of forefoot pain. Several radiological measurements such as Hallux Valgus Angle (HVA), First Metatarsophalangeal Angle (IMA) and Distal metatarsal articular angle (DMAA) exist to calculate the severity of HV and direct patient management. However, these are angular measurements are prone to error with variable intra- and inter-observer reliability. Purpose: To describe a new radiological linear hallux valgus offset (LHVO) to measure HV deformity. Patient and methods: We performed a retrospective cohort study looking at Antero-posterior, weight- bearing foot radiographs of 100 consecutive patients with forefoot pain referred to our foot and ankle clinic. Demographic details, clinical indication, HVA (hallux valgus angle) and LHVO were measured for each patient and data were analyzed using the student t-test. Intraclass Correlation Coefficient (ICC) analysis was evaluated to assess the intra-class reliability between observers. Results: There was a female predominance of approximately 2:1, with 51.3 years (range 13e86 years). There was a statistically significant difference of LHVO between normal and hallux valgus cohorts with a p-value of 0.0001. The LHVO gave moderate intra-observer and inter-observer reliability on ICC analysis of 0.7. Conclusion: The LHVO can be an additional measure of assessing severity of hallux valgus. In contrary to the traditional angular measurements, this linear measure is easier to calculate and reproducible on plain, weight bearing radiographs. LHVO measurement has shown a moderate inter-observer reliability in the study to complement traditional radiological evaluation of hallux valgus alignment.
© 2022 Delhi Orthopedic Association. All rights reserved.
1. Introduction
Hallux Valgus (HV), either adult or adolescent, is a common, complex deformity of the first ray of the forefoot.1 It is described by medial angulation of the first metatarsal and the lateral deviation of the proximal phalanx at the level of the first metatarsophalangeal (MTP) joint.2,3 Adolescent or Juvenile HV is often bilateral, and patients may present with significant angular deformities involving the first ray at the articular level. This primarily leads to cosmetic
al, Bristol Road South North-
.
rights reserved.
complaints and is commonly associated with flatfoot or hypermo- bility features.4,5 Contrary to Adult HV, which is often insidious, developing over a prolonged period of time, typically affecting middle-aged and older women, and attributed to wearing constrictive footwear.6
HV deformity, commonly referred to as a bunion, is a recognized cause of forefoot pain and can lead to foot malignment, inability to wear appropriate footwear, loss of function and disability in affected patients.7
The aetiology of HV is multifactorial. The intrinsic factors such as pes planus, generalised joint laxity, hypermobility of the first ray articulations, arthropathies and neuromuscular disorders and extrinsic factors such as footwear, hereditary predisposition have been associatedwith the development of HV.8 The pathophysiology
A. Saad, K.P. Iyengar, J. Fitzpatrick et al. Journal of Clinical Orthopaedics and Trauma 30 (2022) 101898
is complex. It stems from a disruption in the balance between the extrinsic and intrinsic muscles of the foot. The stronger lateral structures (adductor hallucis muscle, collateral ligaments and peronei) eventually displace the first metatarsal medially and the hallux (big toe) laterally, leading to medial capsule strain, rupture and deformity.8
Diagnosis of HV is made based on history and clinical exami- nation. However, radiological imaging is crucial in confirming the diagnosis, assessing the deformity's severity, and analysing joint congruity to guide treatment.9
Plain radiography tends to be the primary imaging modality to assess HV. Various radiological angles on weight-bearing ante- roposterior (AP), oblique, lateral and sesamoid axial views of the foot allow measurement of HV deformity, assess articular changes in sagittal or coronal planes and aid clinicians in planning patient management.10 (Table 1). Traditionally used radiological measure- ments such as Hallux Valgus Angle (HVA), First Meta- tarsophalangeal Angle (IMA) and Distal metatarsal articular angle (DMAA) all involve measurements of angles between the bones of the first ray or adjacent foot articulations. These angular mea- surements are quantitative measures of hallux valgus. Conse- quently, comparative inter-observer and intra-observer reliability of these radiographic measurements in the estimation of symp- tomatic HV can be variable.11,12
This article highlights a novel linear measurement- The Linear Hallux Valgus Offset (LHVO) to evaluate HV deformity. The LHVO we feel is easier to calculate on conventional weight-bearing plain foot AP radiographs and reproducible with good intra-observer reliability in the radiographic assessment of HV deformity in patients.
2. Patients and methods
2.1. Study design and inclusion criteria
Following hospital ethical committee approval, we performed a retrospective evaluation of our Radiology Information System (RIS) and Picture Archiving and Communication System (PACS) to iden- tify 100 consecutive cases of patients referred to our foot and ankle clinics over a 3month period with forefoot pain and first ray deformity. Amongst them, there was a female predominance of approximately 2:1, with 69 females and 31male patients. Themean age of our patients was 51.3 years (range 13e86 years). The imaging protocol includedweight bearing, antero-posterior and lateral view plain radiographs of the foot, where the requesting clinician had stated 'bunion' or 'hallux valgus' evaluation as the indication in the clinical details section. Patients with a previous surgical history
Table 1 Traditionally used radiological indices to assess and measure Hallux Valgus on Plain X-ra Weightbearing view.
Name Calculation
1 Hallux Valgus Angle (HVA)
The angle is formed by a line drawn through the longitudinal that of a line drawn through the longitudinal axis of the firs
2 First Metatarsophalangeal Angle (IMA)
The angle is formed by a line drawn through the longitudinal that of a line drawn through the longitudinal axis of the SEC
3 Distal metatarsal articular angle (DMAA)
DMMA is formed between first metatarsal axis and line thro
AbbreviationsX-ray ¼ Radiographs; AP ¼ Antero-posterior; MTP ¼ Metatarsophalangeal
2
involving the HV, forefoot or midfoot region with or without metalwork were excluded from our cohort group.
2.2. Image analysis
The radiographs were reviewed by the senior author (RB), a fellowship-trained musculoskeletal radiologist with more than 10 years’ experience, another fellowship-trained musculoskeletal radiologist, and a musculoskeletal Radiology fellow for analysis. In addition, RB repeated the measurements after a week to assess intra-observer reliability. Finally, the radiographs were evaluated for features of alignment abnormalities, degenerative changes and the 'Hallux Valgus Angle (HVA) was calculated using standard technique.9,10
3. Calculation of the Hallux Valgus Angle (HVA)
The 'Hallux Valgus Angle (HVA) is calculated by determining the angle between two lines - a line along the first metatarsal long axis and a line parallel to the longitudinal axis of the first proximal phalanx of the hallux.13 A normal angle is interpreted as 15, whereas a greater value indicates the presence of a hallux valgus.14
3.1. Calculation of the Linear Hallux valgus Offset (LHVO)
The LHVO is calculated on an AP weight-bearing plain radio- graph of the foot. The calculation method involves drawing a straight vertical line from the tip of the distal phalanx down to the lateral edge of the base of the first metatarsal (LINE A). A second 90
horizontal line is drawn from line A to the lateral border of the metatarsophalangeal joint of the first Metatarsal (LINE B). The distance between lines A and B is measured and corresponds to LHVO. (Fig. 1).
3.2. Calculation of the Linear Hallux valgus Offset (LHVO) index
To explore the clinical significance of LHVO further, we measured the first ray metatarsal head width and correlated it with LHVO to produce a LHVO Index.
The first ray metatarsal head width was measured at the broadest part (Fig. 2) The corresponding LHVO was divided by this measure C (Metatarsal headwidth) to derive the LHVO Index. LHVO index measurement would guide whether a distal metatarsal osteotomy such as Chevron or Scarf osteotomy would adequately correct the HV deformity, or a proximal based osteotomy would be needed.
y Antero-posterior
Normal Value
axis of the first metatarsal with that t proximal phalanx.
Less than 15
Identifies first MTP deformity Anything greater than 15 indicates hallux valgus Severity Classification
9, 10
Less than 9
Signifies first MTP Incongruity
joint.
Fig. 1. Schematic showing calculation of Linear Hallux Valgus Offset: Weight-bearing anteroposterior x-ray showing line A(formed by joining the middle of the tip of distal phalanx of the great toe and lateral part of the base of the first metatarsal) and line B (distance between the lateral part of the 1st MTPJ and line A).
Fig. 2. Schematic showing calculation of LHVO Index: line A(formed by joining the middle of the tip of distal phalanx of big toe and lateral part of the base of the first metatarsal) and line B (LHVO- distance between the lateral part of the 1st MTPJ and line A). Width of metatarsal head is line C. LHVO index is calculated as B/C. MT- Metatarsal, PP- proximal phalanx, DP- distal phalanx.
A. Saad, K.P. Iyengar, J. Fitzpatrick et al. Journal of Clinical Orthopaedics and Trauma 30 (2022) 101898
4. Methodology
4.1. Data collection
Our data included patient demographics details, clinical indi- cation for imaging, the standard radiological measurement of the HVI and an LHVO measurement calculated for every patient within our cohort. Data was recorded on a Microsoft Excel data spread- sheet and using SPSS 24.0 software (SPSS Inc. Chicago, Illinois, USA). The data was analysed using the student's t-test, and an Intraclass Correlation Coefficient (ICC) analysis to assess the reliability. The ICC usually falls between 0 and 1. The reliability value is as follow: below 0.5 indicate poor, between 0.5 and 0.75 moderate, between 0.75 and 0.9 good, and above 0.9 indicate excellent reliability.15
5. Results
Amongst 100 consecutive cases in our cohort, there was a fe- male predominance of approximately 2:1, with 69 females and 31 male patients. The mean age of our patients was 51.3 years (range 13e86 years) (Table 2).The LHVO measurement was calculated for all the cases and described in Table 3. There was a statistically significant difference of LHVO between normal and hallux valgus cohorts with a p-value of 0.0001. There was moderate intra and interobserver reliability with an ICC of 0.7, suggesting moderate
3
reliability. The LHVO was proportionately increased with an in- crease in the degree of hallux valgus (0.7 for mild hallux valgus, 1 for moderate and 1.6 for severe hallux valgus).
Linear Hallux valgus Offset (LHVO) Index calculation is depicted in Table 4.Table 4.
6. Discussion
Radiographic parameters have played a critical role in assessing the severity and guiding clinicians in the surgical management of HV. Commonly used methods are based on angular measurements and include; the hallux valgus angle (HVA), Intermetatarsal angle (IMA) and distal metatarsal articular angle (DMAA).16
These are often measured by direct visual estimation based on weight-bearing foot plain radiographs.17e19 The accuracy of these measurements for clinical and research purposes is debatable in the literature. As a result, many attempts have been instigated to improve the reliability of these angles. Nonetheless, these mea- surements must be reliable and reproducible.11,12,18,19
The HVA is the traditionally used measurement obtained by joining a line between themidline axis of the proximal phalanx and first metatarsal. An angle of <15 is thought to be within normal limits, whilst an angle of >40 represents a severe deformity.20
Although many studies have shown a high test-retest reliability of the HVA,11,12,19,21 it lacks a standardised approach for measuring
Table 2 The ‘Linear Hallux Valgus Offset’ (LHVO) linear measurements in the study group of 100 patients (n ¼ 100).
HVA in patients Number of patients ¼ n Average LHVO Maximum LHVO Minimum LHVO
Normal 39 0.6 cm 0.9 cm 0 cm Hallux Valgus patients 61 0.9 cm 2.1 cm 0.4 cm Total 100
Abbreviations: Hallux Valgus Angle ¼ HVA; Linear Hallux Valgus Index ¼ LHVI.
Table 3 Descriptive statistics of the normal and hallux valgus cohorts.
normal hallux valgus
Number of cases 39 61 Average age (years) 48.49 52.76 Maximum age(years) 79 86 Minimum age(years) 13 24 Male 15 18 Female 24 43 Mean (cm) 0.6 0.95 Standard deviation (cm) 1.24 0.34 Standard error of mean 0.2 0.04 95% confidence interval 0.2e1.17 0.86e1.04 Median (cm) 0.3 0.9
Table 4 LHVO index calculation in normal and hallux valgus cohorts.
HVA in patients Average LHVI Minimum LHVI Maximum LHVI
Normal 0.42 0.3 0.58 Hallux Valgus patients 0.65 0.36 1.1
Abbreviations: Hallux Valgus Angle ¼ HVA; Linear Hallux Valgus Offset Index ¼ LHVI.
A. Saad, K.P. Iyengar, J. Fitzpatrick et al. Journal of Clinical Orthopaedics and Trauma 30 (2022) 101898
these angles, with various methods mentioned in the literature. Moreover, some clinicians, especially those in early specialty training, are challenged by complexities in identifying the long axis of the metatarsus, drawn between either the center of the proximal or distal metaphyseal bone. Therefore, depending on the method utilised, the outcomes may not be as reliable, and hence, confound the approach to surgical management.18,19
The IMA is another commonly used measurement for HV. It is calculated by angle between longitudinal axes of the first and secondmetatarsal shaft on an axial weight-bearing viewof the foot. A normal value is under 9.22,23 The IMA, like the HVA, can similarly be affected by the measurement method and subjected to potential risk in error. However, studies have shown no improvement in reliability based on experience.24 Furthermore, the IMA can be mistakenly increased due to metatarsal deviation during the pro- gression of HV or due to metatarsal rotation, and therefore, deemed only reliable in the late stages of disease progression.25,26
Linear measurements used to evaluate the HV are generally easier than angular measurements.19 The LHVO is a novel, more simplified method that can be utilised to assess the severity of HV, with an ICC of moderate reliability. We also found that the pro- portionate increase in the LHVO has allowed us to categorise HV into mild, moderate, and severe objectively. Moreover, we feel that the LHVO can be an additional method to measure the HV, aid with surgical planning, and use other measurements to improve reli- ability outcomes and simpler to calculate for junior trainees.
To consolidate the results of our study and evaluate the clinical significance of the LHVO, wemeasured the first raymetatarsal head width and correlated it with LHVO to produce a LHVO Index. A LHVO Index less than 1 suggests that a distal metatarsal osteotomy such as Chevron or Scarf osteotomy would adequately correct the HV deformity and as such guide clinical management.We hope that
4
our simple technique may be used in the future research and clinical settings. We suggest that the overall improvement in the reliability of the measurements of the HV are best achieved by adopting a standardised technique, evaluating the measurements as a minimum of two calculations and estimating the results.
6.1. Limitations of the study
Our study has certain limitations. This is a retrospective study with a small sample size subject to confounding factors. There was lack of appropriate length of follow-up. Moreover there was no documented communication of the findings between the MSK ra- diologists and surgeons undertaking the procedure to consolidate the findings. However, our LHVO had moderate reliability with an ICC of 0.7, and this reinforces our confidence in this measurement.
7. Conclusion
This study describes a novel linear measurement that can be used to assess the severity of hallux valgus. Compared to the traditional angular measurements of HV, the LHVO is easier to calculate and has good inter-observer reliability to complement the current radiological evaluation of HV. Further larger, multi-center collaborative cohort studies will be helpful to reinforce our find- ings and applicability of the LHVO in routine assessment of hallux valgus deformity to guide management decisions.
Funding
References
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2. Doty JF, Harris WT. Hallux valgus deformity and treatment: a three- dimensional approach. Foot Ankle Clin. 2018 Jun;23(2):271e280. https:// doi.org/10.1016/j.fcl.2018.01.007.
3. Coughlin MJ. Hallux valgus. Instr Course Lect. 1997;46:357e391. PMID: 9143980.
4. Coughlin MJ, Jones CP. Hallux valgus and first ray mobility. A prospective study. J Bone Joint Surg Am. 2007 Sep;89(9):1887e1898. https://doi.org/10.2106/ JBJS.F.01139.
5. Marshall TJ, Shung JR, Khoury JG. Adolescent hallux valgus revisited. Orthope- dics. 2014 Aug;37(8):531e535. https://doi.org/10.3928/01477447-20140728- 05.
6. Yu G, Fan Y, Fan Y, et al. The role of footwear in the pathogenesis of hallux valgus: a proof-of-concept finite element analysis in recent humans and Homo Naledi. Front Bioeng Biotechnol. 2020 Jun 30;8:648. https://doi.org/10.3389/ fbioe.2020.00648.
7. Nix SE, Vicenzino BT, Smith MD. Foot pain and functional limitation in healthy adults with hallux valgus: a cross-sectional study. BMC Muscoskel Disord. 2012 Oct 16;13:197. https://doi.org/10.1186/1471-2474-13-197.
8. Perera AM, Mason L, Stephens MM. The pathogenesis of hallux valgus. J Bone Joint Surg Am. 2011 Sep 7;93(17):1650e1661. https://doi.org/10.2106/ JBJS.H.01630.
9. Heineman N, Liu G, Pacicco T, Dessouky R, Wukich DK, Chhabra A. Clinical and imaging assessment and treatment of hallux valgus. Acta Radiol. 2020
Jan;61(1):56e66. https://doi.org/10.1177/0284185119847675. Epub 2019 May 13.
10. Karasick D, Wapner KL. Hallux valgus deformity: preoperative radiologic assessment. AJR Am J Roentgenol. 1990 Jul;155(1):119e123. https://doi.org/ 10.2214/ajr.155.1.2112832.
11. Lee KM, Ahn S, Chung CY, Sung KH, Park MS. Reliability and relationship of radiographic measurements in hallux valgus. Clin Orthop Relat Res. 2012 Sep;470(9):2613e2621. https://doi.org/10.1007/s11999-012-2368-6. Epub 2012 Apr 28.
12. Menz HB, Munteanu SE. Radiographic validation of the Manchester scale for the classification of hallux valgus deformity. Rheumatology. 2005 Aug;44(8): 1061e1066. https://doi.org/10.1093/rheumatology/keh687. Epub 2005 May 18.
13. Garrow AP, Papageorgiou A, Silman AJ, Thomas E, Jayson MI, Macfarlane GJ. The grading of hallux valgus. The Manchester Scale. J Am Podiatr Med Assoc. 2001 Feb;91(2):74e78. https://doi.org/10.7547/87507315-91-2-74.
14. Karasick D, Wapner KL. Hallux valgus deformity: preoperative radiologic assessment. AJR Am J Roentgenol. 1990 Jul;155(1):119e123. https://doi.org/ 10.2214/ajr.155.1.2112832.
15. Koo TK, Li MY. A guideline of selecting and reporting Intraclass correlation coefficients for reliability research. J Chiropr Med. 2016 Jun;15(2):155e163. https://doi.org/10.1016/j.jcm.2016.02.012. Epub 2016 Mar 31. Erratum in: J Chiropr Med. 2017 Dec;16(4):346.
16. Robinson AH, Limbers JP. Modern concepts in the treatment of hallux valgus. J Bone Joint Surg Br. 2005;87(8):1038e1045. https://doi.org/10.1302/0301- 620X.87B8.16467. Mann RA: Decision-making in bunion surgery. Instr Course Lect. 1990, 39: 3-1045.
17. Hawkins FB, Mitchell CL, Hedrick DW. Correction of hallux valgus by metatarsal osteotomy. J Bone Joint Surg. 1945;27:387e394.
5
18. Schneider W, Csepan R, Knahr K. Reproducibility of the radiographic meta- tarsophalangeal angle in hallux surgery. J Bone Joint Surg Am. 2003;85-A:494, 9.
19. Resch S, Ryd L, Stenstrom A, Johnsson K, Reynisson K. Measuring hallux valgus: a comparison of conventional radiography and clinical parameters with regard to measurement accuracy. Foot Ankle Int. 1995;16:267e270.
20. Zhou J, Hlavacek P, Xu B, Chen W. Approach for measuring the angle of hallux valgus. Indian J Orthop. 2013 May;47(3):278e282. https://doi.org/10.4103/ 0019-5413.109875.
21. van der Woude P, Keizer SB, Wever-Korevaar M, Thomassen BJW. Intra- and interobserver agreement in hallux valgus angle measurements on weight- bearing and Non-weightbearing radiographs. J Foot Ankle Surg. 2019 Jul;58(4): 706e712. https://doi.org/10.1053/j.jfas.2018.11.032.
22. Schneider W, Knahr K. Metatarsophalangeal…
journal homepage: www.elsevier .com/locate/ jcot
The Linear Hallux Valgus Offsete A novel way to measure Hallux Valgus
A. Saad a, Karthikeyan P. Iyengar c, John Fitzpatrick b, C. Azzopardi b, H. Panchal d, R. Botchu b, *
a Department of Orthopaedics, Royal Orthopaedic Hospital, Birmingham, UK b Department of Musculoskeletal Radiology, Royal Orthopaedic Hospital, Birmingham, UK c Southport and Ormskirk NHS Trust, Southport, UK d Sanyapixel Diagnostics, Ahmedabad, India
a r t i c l e i n f o
Article history: Received 5 February 2022 Received in revised form 29 April 2022 Accepted 11 May 2022 Available online 18 May 2022
Keywords: Hallux valgus Bunion Radiography Hallux valgus angle Intermetatarsal angle Reliability
* Corresponding author. Royal Orthopaedic Hospit field, Birmingham, UK.
E-mail address: [email protected] (R. Botchu)
https://doi.org/10.1016/j.jcot.2022.101898 0976-5662/© 2022 Delhi Orthopedic Association. All
a b s t r a c t
Introduction: Hallux Valgus (HV) is a complex deformity involving the first ray of the forefoot and a common cause of forefoot pain. Several radiological measurements such as Hallux Valgus Angle (HVA), First Metatarsophalangeal Angle (IMA) and Distal metatarsal articular angle (DMAA) exist to calculate the severity of HV and direct patient management. However, these are angular measurements are prone to error with variable intra- and inter-observer reliability. Purpose: To describe a new radiological linear hallux valgus offset (LHVO) to measure HV deformity. Patient and methods: We performed a retrospective cohort study looking at Antero-posterior, weight- bearing foot radiographs of 100 consecutive patients with forefoot pain referred to our foot and ankle clinic. Demographic details, clinical indication, HVA (hallux valgus angle) and LHVO were measured for each patient and data were analyzed using the student t-test. Intraclass Correlation Coefficient (ICC) analysis was evaluated to assess the intra-class reliability between observers. Results: There was a female predominance of approximately 2:1, with 51.3 years (range 13e86 years). There was a statistically significant difference of LHVO between normal and hallux valgus cohorts with a p-value of 0.0001. The LHVO gave moderate intra-observer and inter-observer reliability on ICC analysis of 0.7. Conclusion: The LHVO can be an additional measure of assessing severity of hallux valgus. In contrary to the traditional angular measurements, this linear measure is easier to calculate and reproducible on plain, weight bearing radiographs. LHVO measurement has shown a moderate inter-observer reliability in the study to complement traditional radiological evaluation of hallux valgus alignment.
© 2022 Delhi Orthopedic Association. All rights reserved.
1. Introduction
Hallux Valgus (HV), either adult or adolescent, is a common, complex deformity of the first ray of the forefoot.1 It is described by medial angulation of the first metatarsal and the lateral deviation of the proximal phalanx at the level of the first metatarsophalangeal (MTP) joint.2,3 Adolescent or Juvenile HV is often bilateral, and patients may present with significant angular deformities involving the first ray at the articular level. This primarily leads to cosmetic
al, Bristol Road South North-
.
rights reserved.
complaints and is commonly associated with flatfoot or hypermo- bility features.4,5 Contrary to Adult HV, which is often insidious, developing over a prolonged period of time, typically affecting middle-aged and older women, and attributed to wearing constrictive footwear.6
HV deformity, commonly referred to as a bunion, is a recognized cause of forefoot pain and can lead to foot malignment, inability to wear appropriate footwear, loss of function and disability in affected patients.7
The aetiology of HV is multifactorial. The intrinsic factors such as pes planus, generalised joint laxity, hypermobility of the first ray articulations, arthropathies and neuromuscular disorders and extrinsic factors such as footwear, hereditary predisposition have been associatedwith the development of HV.8 The pathophysiology
A. Saad, K.P. Iyengar, J. Fitzpatrick et al. Journal of Clinical Orthopaedics and Trauma 30 (2022) 101898
is complex. It stems from a disruption in the balance between the extrinsic and intrinsic muscles of the foot. The stronger lateral structures (adductor hallucis muscle, collateral ligaments and peronei) eventually displace the first metatarsal medially and the hallux (big toe) laterally, leading to medial capsule strain, rupture and deformity.8
Diagnosis of HV is made based on history and clinical exami- nation. However, radiological imaging is crucial in confirming the diagnosis, assessing the deformity's severity, and analysing joint congruity to guide treatment.9
Plain radiography tends to be the primary imaging modality to assess HV. Various radiological angles on weight-bearing ante- roposterior (AP), oblique, lateral and sesamoid axial views of the foot allow measurement of HV deformity, assess articular changes in sagittal or coronal planes and aid clinicians in planning patient management.10 (Table 1). Traditionally used radiological measure- ments such as Hallux Valgus Angle (HVA), First Meta- tarsophalangeal Angle (IMA) and Distal metatarsal articular angle (DMAA) all involve measurements of angles between the bones of the first ray or adjacent foot articulations. These angular mea- surements are quantitative measures of hallux valgus. Conse- quently, comparative inter-observer and intra-observer reliability of these radiographic measurements in the estimation of symp- tomatic HV can be variable.11,12
This article highlights a novel linear measurement- The Linear Hallux Valgus Offset (LHVO) to evaluate HV deformity. The LHVO we feel is easier to calculate on conventional weight-bearing plain foot AP radiographs and reproducible with good intra-observer reliability in the radiographic assessment of HV deformity in patients.
2. Patients and methods
2.1. Study design and inclusion criteria
Following hospital ethical committee approval, we performed a retrospective evaluation of our Radiology Information System (RIS) and Picture Archiving and Communication System (PACS) to iden- tify 100 consecutive cases of patients referred to our foot and ankle clinics over a 3month period with forefoot pain and first ray deformity. Amongst them, there was a female predominance of approximately 2:1, with 69 females and 31male patients. Themean age of our patients was 51.3 years (range 13e86 years). The imaging protocol includedweight bearing, antero-posterior and lateral view plain radiographs of the foot, where the requesting clinician had stated 'bunion' or 'hallux valgus' evaluation as the indication in the clinical details section. Patients with a previous surgical history
Table 1 Traditionally used radiological indices to assess and measure Hallux Valgus on Plain X-ra Weightbearing view.
Name Calculation
1 Hallux Valgus Angle (HVA)
The angle is formed by a line drawn through the longitudinal that of a line drawn through the longitudinal axis of the firs
2 First Metatarsophalangeal Angle (IMA)
The angle is formed by a line drawn through the longitudinal that of a line drawn through the longitudinal axis of the SEC
3 Distal metatarsal articular angle (DMAA)
DMMA is formed between first metatarsal axis and line thro
AbbreviationsX-ray ¼ Radiographs; AP ¼ Antero-posterior; MTP ¼ Metatarsophalangeal
2
involving the HV, forefoot or midfoot region with or without metalwork were excluded from our cohort group.
2.2. Image analysis
The radiographs were reviewed by the senior author (RB), a fellowship-trained musculoskeletal radiologist with more than 10 years’ experience, another fellowship-trained musculoskeletal radiologist, and a musculoskeletal Radiology fellow for analysis. In addition, RB repeated the measurements after a week to assess intra-observer reliability. Finally, the radiographs were evaluated for features of alignment abnormalities, degenerative changes and the 'Hallux Valgus Angle (HVA) was calculated using standard technique.9,10
3. Calculation of the Hallux Valgus Angle (HVA)
The 'Hallux Valgus Angle (HVA) is calculated by determining the angle between two lines - a line along the first metatarsal long axis and a line parallel to the longitudinal axis of the first proximal phalanx of the hallux.13 A normal angle is interpreted as 15, whereas a greater value indicates the presence of a hallux valgus.14
3.1. Calculation of the Linear Hallux valgus Offset (LHVO)
The LHVO is calculated on an AP weight-bearing plain radio- graph of the foot. The calculation method involves drawing a straight vertical line from the tip of the distal phalanx down to the lateral edge of the base of the first metatarsal (LINE A). A second 90
horizontal line is drawn from line A to the lateral border of the metatarsophalangeal joint of the first Metatarsal (LINE B). The distance between lines A and B is measured and corresponds to LHVO. (Fig. 1).
3.2. Calculation of the Linear Hallux valgus Offset (LHVO) index
To explore the clinical significance of LHVO further, we measured the first ray metatarsal head width and correlated it with LHVO to produce a LHVO Index.
The first ray metatarsal head width was measured at the broadest part (Fig. 2) The corresponding LHVO was divided by this measure C (Metatarsal headwidth) to derive the LHVO Index. LHVO index measurement would guide whether a distal metatarsal osteotomy such as Chevron or Scarf osteotomy would adequately correct the HV deformity, or a proximal based osteotomy would be needed.
y Antero-posterior
Normal Value
axis of the first metatarsal with that t proximal phalanx.
Less than 15
Identifies first MTP deformity Anything greater than 15 indicates hallux valgus Severity Classification
9, 10
Less than 9
Signifies first MTP Incongruity
joint.
Fig. 1. Schematic showing calculation of Linear Hallux Valgus Offset: Weight-bearing anteroposterior x-ray showing line A(formed by joining the middle of the tip of distal phalanx of the great toe and lateral part of the base of the first metatarsal) and line B (distance between the lateral part of the 1st MTPJ and line A).
Fig. 2. Schematic showing calculation of LHVO Index: line A(formed by joining the middle of the tip of distal phalanx of big toe and lateral part of the base of the first metatarsal) and line B (LHVO- distance between the lateral part of the 1st MTPJ and line A). Width of metatarsal head is line C. LHVO index is calculated as B/C. MT- Metatarsal, PP- proximal phalanx, DP- distal phalanx.
A. Saad, K.P. Iyengar, J. Fitzpatrick et al. Journal of Clinical Orthopaedics and Trauma 30 (2022) 101898
4. Methodology
4.1. Data collection
Our data included patient demographics details, clinical indi- cation for imaging, the standard radiological measurement of the HVI and an LHVO measurement calculated for every patient within our cohort. Data was recorded on a Microsoft Excel data spread- sheet and using SPSS 24.0 software (SPSS Inc. Chicago, Illinois, USA). The data was analysed using the student's t-test, and an Intraclass Correlation Coefficient (ICC) analysis to assess the reliability. The ICC usually falls between 0 and 1. The reliability value is as follow: below 0.5 indicate poor, between 0.5 and 0.75 moderate, between 0.75 and 0.9 good, and above 0.9 indicate excellent reliability.15
5. Results
Amongst 100 consecutive cases in our cohort, there was a fe- male predominance of approximately 2:1, with 69 females and 31 male patients. The mean age of our patients was 51.3 years (range 13e86 years) (Table 2).The LHVO measurement was calculated for all the cases and described in Table 3. There was a statistically significant difference of LHVO between normal and hallux valgus cohorts with a p-value of 0.0001. There was moderate intra and interobserver reliability with an ICC of 0.7, suggesting moderate
3
reliability. The LHVO was proportionately increased with an in- crease in the degree of hallux valgus (0.7 for mild hallux valgus, 1 for moderate and 1.6 for severe hallux valgus).
Linear Hallux valgus Offset (LHVO) Index calculation is depicted in Table 4.Table 4.
6. Discussion
Radiographic parameters have played a critical role in assessing the severity and guiding clinicians in the surgical management of HV. Commonly used methods are based on angular measurements and include; the hallux valgus angle (HVA), Intermetatarsal angle (IMA) and distal metatarsal articular angle (DMAA).16
These are often measured by direct visual estimation based on weight-bearing foot plain radiographs.17e19 The accuracy of these measurements for clinical and research purposes is debatable in the literature. As a result, many attempts have been instigated to improve the reliability of these angles. Nonetheless, these mea- surements must be reliable and reproducible.11,12,18,19
The HVA is the traditionally used measurement obtained by joining a line between themidline axis of the proximal phalanx and first metatarsal. An angle of <15 is thought to be within normal limits, whilst an angle of >40 represents a severe deformity.20
Although many studies have shown a high test-retest reliability of the HVA,11,12,19,21 it lacks a standardised approach for measuring
Table 2 The ‘Linear Hallux Valgus Offset’ (LHVO) linear measurements in the study group of 100 patients (n ¼ 100).
HVA in patients Number of patients ¼ n Average LHVO Maximum LHVO Minimum LHVO
Normal 39 0.6 cm 0.9 cm 0 cm Hallux Valgus patients 61 0.9 cm 2.1 cm 0.4 cm Total 100
Abbreviations: Hallux Valgus Angle ¼ HVA; Linear Hallux Valgus Index ¼ LHVI.
Table 3 Descriptive statistics of the normal and hallux valgus cohorts.
normal hallux valgus
Number of cases 39 61 Average age (years) 48.49 52.76 Maximum age(years) 79 86 Minimum age(years) 13 24 Male 15 18 Female 24 43 Mean (cm) 0.6 0.95 Standard deviation (cm) 1.24 0.34 Standard error of mean 0.2 0.04 95% confidence interval 0.2e1.17 0.86e1.04 Median (cm) 0.3 0.9
Table 4 LHVO index calculation in normal and hallux valgus cohorts.
HVA in patients Average LHVI Minimum LHVI Maximum LHVI
Normal 0.42 0.3 0.58 Hallux Valgus patients 0.65 0.36 1.1
Abbreviations: Hallux Valgus Angle ¼ HVA; Linear Hallux Valgus Offset Index ¼ LHVI.
A. Saad, K.P. Iyengar, J. Fitzpatrick et al. Journal of Clinical Orthopaedics and Trauma 30 (2022) 101898
these angles, with various methods mentioned in the literature. Moreover, some clinicians, especially those in early specialty training, are challenged by complexities in identifying the long axis of the metatarsus, drawn between either the center of the proximal or distal metaphyseal bone. Therefore, depending on the method utilised, the outcomes may not be as reliable, and hence, confound the approach to surgical management.18,19
The IMA is another commonly used measurement for HV. It is calculated by angle between longitudinal axes of the first and secondmetatarsal shaft on an axial weight-bearing viewof the foot. A normal value is under 9.22,23 The IMA, like the HVA, can similarly be affected by the measurement method and subjected to potential risk in error. However, studies have shown no improvement in reliability based on experience.24 Furthermore, the IMA can be mistakenly increased due to metatarsal deviation during the pro- gression of HV or due to metatarsal rotation, and therefore, deemed only reliable in the late stages of disease progression.25,26
Linear measurements used to evaluate the HV are generally easier than angular measurements.19 The LHVO is a novel, more simplified method that can be utilised to assess the severity of HV, with an ICC of moderate reliability. We also found that the pro- portionate increase in the LHVO has allowed us to categorise HV into mild, moderate, and severe objectively. Moreover, we feel that the LHVO can be an additional method to measure the HV, aid with surgical planning, and use other measurements to improve reli- ability outcomes and simpler to calculate for junior trainees.
To consolidate the results of our study and evaluate the clinical significance of the LHVO, wemeasured the first raymetatarsal head width and correlated it with LHVO to produce a LHVO Index. A LHVO Index less than 1 suggests that a distal metatarsal osteotomy such as Chevron or Scarf osteotomy would adequately correct the HV deformity and as such guide clinical management.We hope that
4
our simple technique may be used in the future research and clinical settings. We suggest that the overall improvement in the reliability of the measurements of the HV are best achieved by adopting a standardised technique, evaluating the measurements as a minimum of two calculations and estimating the results.
6.1. Limitations of the study
Our study has certain limitations. This is a retrospective study with a small sample size subject to confounding factors. There was lack of appropriate length of follow-up. Moreover there was no documented communication of the findings between the MSK ra- diologists and surgeons undertaking the procedure to consolidate the findings. However, our LHVO had moderate reliability with an ICC of 0.7, and this reinforces our confidence in this measurement.
7. Conclusion
This study describes a novel linear measurement that can be used to assess the severity of hallux valgus. Compared to the traditional angular measurements of HV, the LHVO is easier to calculate and has good inter-observer reliability to complement the current radiological evaluation of HV. Further larger, multi-center collaborative cohort studies will be helpful to reinforce our find- ings and applicability of the LHVO in routine assessment of hallux valgus deformity to guide management decisions.
Funding
References
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