Introduction
Growing interest in minimally invasive surgery (MIS) has resulted with an explosion of percutaneous reconstructive techniques over the last decade. Early advocates of MIS report comparable outcomes to open surgery with reduced complications, however this remains a subject of debate with traditionalists defensibly refuting these claims, touting high reporting and selection bias.1, 2, 3 The surgical management of metatarsus quintus valgus is no exception with conflicting opinions regarding the most effective procedure and technical execution.
Historically bunionettes were considered an adaptation of the 5th metatarsal head within the tailoring trade, however modern surgeons acknowledge the deformity as a complex pathology with multifactorial structural and mechanical drivers (Table 1).4, 5, 6 Early writings explored the concept that mild 5th metatarsal splaying and 5th toe adduction were normal findings within the general population although rather ambiguously argued larger symptomatic deformities should be considered secondary pathology associated with global deformity such as pes plano valgus or hallux valgus.5 Considered an oversimplification, these ideologies have been dispelled however paucity of research, small case series and confounding limits prospective data.
Table 1
Structural and biomechanical factors contributing to tailors’ bunion deformity
Lateralisation of the 5th metatarsal contributes to a splay forefoot and presents with a typical symptomatologic triad of footwear irritation, plantar lateral callus and chronic adventitious bursal enlargement over the lateral aspect of the 5th metatarsal head.7 Adductovarus 5th toe deformity is a common associated finding which may similarly present with digital pain, rubbing and hyperkeratosis. Radiographic classification (Figure 1) continues to dominate deformity grading and determines the centre of rotation of angulation (CORA) aiding surgical planning.8 Weight bearing (WB) dorso-plantar (DP) and medial oblique (MO) views are arguably the most valuable for classifying bunionette deformities however WB lateral views of the foot and ankle facilitates charting of sagittal plane deformity such as pes planus or cavus which may be of relevance, particularly in revision cases and managing patient expectations.4, 9, 10
Figure 1
a): Radiographic classification of tailors bunions; b): Classification by Fallat and Buckholtz
Surgical reduction is primarily undertaken via 5th metatarsal osteotomy however there remains a lack of consensus regarding the most effective technique. The scarf osteotomy has been described as a versatile procedure with acceptable patient reported outcomes and deformity correction however some have challenged its efficacy reporting increased risk of complications. Increased application of MIS is challenging the status quo, specifically open techniques like the scarf osteotomy citing comparable outcomes with reduced complications owing to reduced dissection, preserved soft tissue envelope, and limited tourniquet use.11 Head-to-head trials are lacking leaving surgeons ambiguous regarding the current evidence and arguably best practice. Systematic review and meta-analysis were performed to investigate two key objectives; Whether the scarf and MIS 5th metatarsal osteotomies have comparable clinical and patient reported outcomes. Secondly, do MIS techniques reduce post-operative complications.
Materials and Methods
In compliance with the preferred reporting items for systematic re- views and meta-analyses (PRISMA), literature was sourced by 2 independent reviewers using electronic multidisciplinary bibliographic databases (Table 2). A PICO (Population, Intervention, Control, Outcome) tool (Table 3) was synthesised by the reviewers to aid research collection, standardize the search, and assist with data extraction. Negotiated medical subheadings (Mesh) and Boolean phrases “And” or “Or” provided a targeted search strategy, with all selected papers cross-referenced to avoid overlooking relevant literature.
Table 2
Bibliographic databases
Table 3
Included papers were required to meet the following criteria: studies utilising the scarf or percutaneous osteotomy for surgical reduction of tailors’ bunions in adults, studies reporting objective pre and post-operative clinical and radiological data, studies providing patient reported outcomes, studies reporting post-operative complications, studies published in English, studies produced between 2000 and 2023. A protracted search period was employed for several reasons although primarily due to paucity of research. Similarly, studies were not discriminated for including patients having concomitant foot surgery. Minimally invasive foot surgery inspired by Boesch’ 1st ray techniques was popularised in 2000, thus arguably birthing its modern concepts and formulated the baseline for this review.12, 13
Excluded papers comprised those where procedures other than 5th metatarsal scarf or percutaneous osteotomies were performed to reduce the tailors’ bunion, studies including paediatric populations, descriptive narratives, failure to disclose complications, studies failing to provide surgeon and patient reported outcomes.
51 texts were initially identified from electronic databases. Application of the PICO tool and inclusion criteria reduced the pool to 11 studies which were accepted for quality assessment: 5 scarf osteotomy and 6 MIS papers inclusive of 115 and 170 surgical episodes respectively.
Figure 2 illustrates a PRISMA flow diagram detailing the review process. Quality assessment of included articles was undertaken using the Joanna Briggs Checklist for Case Series checklist and Coleman Methodology Score due to its high reproducibility and correlation with evidence classification. A Modified Cochrane risk of bias (ROB) further scrutinised included studies.
Statistical analyses of pooled results and Coleman Methodology scoring was performed by each independent reviewer with discrepancies resolved following discussion and the final score decided as a team. Summary recommendations were unanimously agreed between reviewers according to their hierarchical level of evidence (Table 4). Score stratification was agreed between reviewers with 85–100 representing excellent quality, 70–84 good quality, 55–69 fair quality and < 55 demonstrating a poor-quality study.14
Table 4
NICE Hierarchy or evidence and recommendations grading scheme
Results
Study characteristics
11 studies (Table 5) met the inclusion criteria, 10 of which identified as retrospective case series. 1 study identified as a prospective cohort, however this was considered author error, misrepresentative and for the purposes of this project labelled as case series 1. European and South American dominance was observed across included studies, particularly MIS, with two papers including the same Brazilian faculty, illustrating industry leaders for this technique.15, 16 Two scarf osteotomy studies were conducted in the UK.17, 18 Follow up differed between procedures; 3/5 scarf osteotomy papers demonstrating mid-term review, two of which mid-long term follow up 7 years.18, 19 3/6 MIS studies presented mid-term review, mean follow up 28 months.12, 20, 21 The remaining five studies for both procedures included short term follow up, mean up 12.8 months. Patient demographics were poorly represented except for age and sex. Mean age of study participants was similar in both groups, mean 47 years. One scarf osteotomy paper demonstrated a relatively young group, mean age 26 years, lowering the scarfs average however this was considered sampling bias.22 There was a clear female: male dominance amongst both groups (Scarf 70%; MIS 88%), however 1 paper failed to report differences between sexes limiting pooled scarf numbers.22
Procedural variation
Tourniquet use
40% of included studies reported use of an ankle tourniquet however varied. 2 scarf papers referenced the use of ankle tourniquets as standard practice,18, 22 however MIS studies were more diverse, restricting application of a tourniquet to patients undergoing concomitant 1st ray procedures or complex forefoot reconstruction.12, 20
Osteotomy
Scarf osteotomy was similarly described across all 5 studies with a longitudinal dorso-lateral incision over the 5th metatarsal, layered dissection, lateral tubercle exostectomy, diaphyseal ‘Z’ osteotomy and reduction of deformity owing to medialisation of the plantar fragment. Inter-surgeon variation existed between the angle of the transverse cuts; however, the scarfs geometric interlocking cuts were unanimously maintained. 2 studies performed shortening osteotomies for all patients removing 2-4mm bone blocks from the transverse cuts to decompress the 5th MTPJ and aid mobilisation of the plantar fragment.17, 23 These studies had a similar academic panel and so this procedure modification was assumed to be institution preference. MIS demonstrated considerable variation, most notably osteotomy location and orientation of cuts. All MIS studies similarly reported use of fluoroscopy. 4/6 reported a stab incision to the lateral aspect of the 5th metatarsal, sharp and blunt dissection to expose the lateral cortex of the 5th metatarsal, and percutaneous osteotomy with a 2x12mm Shannon burr. Lui (2014) reported a medial wedge osteotomy using a Isham straight flute burr. Laffenetre et al. (2015) performed a medial closing wedge osteotomy with preservation of the lateral hinge using a long Shannon bur (12x2mm). All studies orientated the burr at 45 degrees in the sagittal plane from dorsal distal lateral to plantar proximal medial to encourage medial transposition, reduce dorsal displacement of the capital fragment and transfer metatarsalgia. One study described a traditional chevron osteotomy with 60–80-degree cuts at the level of the 5th metatarsal head 20. Sub-capital osteotomy was performed in all other studies with a degree of technical variation. 2 studies cited the importance of osteotomy performance at a pre-determined apex of deformity in keeping with Coughlin’s radiographic classification.12, 16 Remaining studies documented a vague reference point within the distal 3rd of the 5th metatarsal.1, 15 Laffenetre et al. (2015) maintained a lateral hinge to aid osteotomy stability, whilst all others performed complete osteotomies. Relevance of hypertrophic lateral tubercles varied across studies with 3 papers performing additional intra-capsular exostectomy where surgeons had concerns regarding residual prominence post-operatively.1, 12, 21
Fixation
Inter-procedure osteosynthesis differed. All scarf osteotomies were fixated with lag screws generating rigid inter-fragmentary compression and absolute stability. Marginal variation in screw fixation was observed in 1 study, with 58% receiving 2 screws, and 42% 1 screw; the rationale for the variation was not defined however it was assumed that this was based on intra-operative findings of construct stability or institution preference.17 No internal fixation was employed for MIS procedures. 1 study performed a medial closing wedge osteotomy, maintaining an intact lateral hinge which was argued to maintain a single point of fixation.12 1 study did not use internal or external fixation.21 Fixation of all other MIS procedures involved external strapping of the 5th digit and or forefoot for intervals ranging from 4-6 weeks.
Post-operative management
Weight bearing protocols varied between authors for both procedures, particularly following scarf osteotomy. 2 scarf studies kept patients non-weight bearing for 3 weeks before allowing protected weight bearing in a post-op shoe for a further 3-6 weeks.19, 23 Immediate partial weight bearing was observed in 3 papers although this ranged from 2-6 weeks.17, 18, 22 2 scarf studies also detailed an initial 4-day inpatient stay, although no rationale for this was provided; otherwise, day case surgery was undertaken.22, 23 MIS weight bearing regimes were more uniform with all cases immediately fully weight bearing in a post-operative sandal, however this ranged from 3-6 weeks based on surgeon preference.
Table 5
|
Scarf Osteotomy |
||
|
Study |
Clinical outcomes |
PROMs |
|
Necas et al.19 (2020) |
Mean reduction in 4th IM angle – 7.90
Mean reduction in 5th MTP angle – 13.60
4th IMA reduction P = 0.001 5th MPJ angle reduction P = 0.001 |
Mean AOFAS increase from 59.4 – 93 AOFAS increase P = 0.001 Coughlin satisfaction score:
79% excellent 18% Good 3% Fair |
|
Hrubina et al23 . (2015) |
Mean reduction in 4th IM angle – 7.80
Mean reduction in 5th MTP angle – 13.70
4th IMA reduction P = 0.001 5th MPJ angle reduction P = 0.001 |
Mean AOFAS increase from 59.8 – 92.3 AOFAS increase P = 0.001 Coughlin satisfaction score:
74% excellent 22% Good 4% Fair |
|
Guha et al.17 (2012) |
Mean reduction in 4th IM angle – 5.80 Mean reduction in 5th MTP angle – 13.50 4th IMA reduction P = 0.0008 5th MPJ angle reduction P = 0.0009 |
Mean AOFAS increase from 54.25 – 89.58 AOFAS increase P = 0.001 100% would refer a friend |
|
Maher & Kilmartin18 (2010) |
Mean reduction in 4th IM angle – 4.20
Mean post-op ROM 5th MTPJ – 540 4th IMA reduction P = 0.001 |
Mean AOFAS increase from 44.1 – 88.1 AOFAS increase P = 0.001 Modified satisfaction Score: Completely: 86% Reservations: 11% Dissatisfied: 3% Would undergo same procedure: Yes: 91% No:9% |
|
Seide & Petersen22 (2001) |
Mean reduction in 4th IM angle – 3.50
100% pain free ROM 5th MTPJ 4th IMA reduction P < 0.05 |
Mean FFSS increase from 29.5-73 FFSS = P < 0.05 Cosmetic score: Excellent: 80% Good: 20% |
|
MIS |
||
|
Study |
Clinical outcomes |
PROMs |
|
Nunes et al.16 (2022) |
Mean reduction in 4th IM angle – 5.80
Mean reduction in 5th MTP angle – 12.30
4th IMA reduction P = 0.001 5th MPJ angle reduction P = 0.001 |
Mean AOFAS increase from 49.6 – 92.4 AOFAS increase P = 0.001 Mean VAS decrease: 6.5 points VAS decrease P = 0.001 Coughlin satisfaction score:
83% excellent 11% Good 11% Fair |
|
Valdivia & Thull20 (2022) |
Mean reduction in 4th IM angle – 5.50
Mean reduction in 5th MTP angle – 160
4th IMA reduction P = 0.001 5th MPJ angle reduction P = 0.001 |
Mean AOFAS increase from 65.8 – 95 AOFAS increase P = 0.001 Mean VAS decrease: 6 points VAS decrease P = 0.001 |
|
De Vete Lima et al.15 (2020) |
Mean reduction in 4th IM angle – 6.20
Mean reduction in 5th MTP angle – 9.20
4th IMA reduction P = 0.001 5th MPJ angle reduction P = 0.001 |
Mean AOFAS increase from 51.3 – 94 AOFAS increase P = 0.001 Mean VAS decrease: 6.4points VAS decrease P = 0.001 |
|
Ferreira et al.1 (2020) |
Mean reduction in 4th IM angle – 7.70
Mean reduction in 5th MTP angle – 11.70
4th IMA reduction P = 0.001 5th MPJ angle reduction P = 0.001 |
Mean AOFAS increase from 58.8 – 93.7 AOFAS increase P = 0.001 Mean VAS decrease: 6.6 points VAS decrease P = 0.001 Coughlin satisfaction score:
89% excellent 7.5% Good 3.5% Fair |
|
Laffenetre et al.12 (2015) |
Mean reduction in 4th IM angle – 4.40
Mean reduction in 5th MTP angle – 11.980
4th IMA reduction P < 0.05 5th MPJ angle reduction P < 0.05
100% resolution of callus |
Mean AOFAS increase from 58 – 97 AOFAS increase P < 0.05 Mean VAS decrease: 7.4 points Coughlin satisfaction score:
97% satisfied 3% dissatisfied |
|
Lui,21 2014 |
Mean reduction in 4th IM angle – 80
Mean reduction in 5th MTP angle – 170
4th IMA reduction P < 0.0001 5th MPJ angle reduction P < 0.0001 |
Mean AOFAS increase from 61.8 – 100 AOFAS increase P < 0.0001 Coughlin satisfaction score:
100% excellent |
Clinical and patient reported outcomes
All included studies assessed changes in pre and post-operative 4th IM and 5th MTPJ angles. 2 papers reviewed post-op 5th MTPJ range of motion (ROM) although failed to include any pre-operative data.18, 22 1 study vaguely reviewed pedometric changes in plantar pressures and subjectively analysed callus patterns.12 1 study utilised the “Forefoot scoring system” (FFSS) to record PROMs, all other studies uniformly employed the AOFAS.22 Change in visual analogue scale (VAS) was measured in all MIS papers and 9/11 papers recorded patient satisfaction.15, 20
All studies demonstrated statistically significant changes in pre and post-operative outcomes measures (Table 5). Pooled mean changes (Figure 3) in 4th IM angle for scarf and MIS were 5.80 and 6.20 respectively. 3/5 scarf and 6/6 MIS papers reviewed 5th MTPJ angular change demonstrating 13.60 and 13.030 respectively. AOFAS scores increased from mean 54.4 – 91 following scarf osteotomy vs mean increase 57.55 – 95.35 following MIS. Mean change in AOFAS between groups was 36.6 and 37.8 (Scarf & MIS). The study utilising FFSS demonstrated mean increase 29.5 -73. 5/6 MIS papers recorded change in VAS; mean decrease in 6.6 points. Post-operative satisfaction following each procedure was 97.5% and 92.25% (Scarf & MIS).
Complications
Complication incidence was 11% and 15.5% for scarf and MIS respectively. Revision surgery was required in 5.2% following scarf osteotomy; the most common reasons were excision of recurrent plantar corns, fixation removal. 1 patient required 2-4 weils osteotomy due to transfer metatarsalgia. 1 individual developed a deep infection requiring wound debridement. 1 wound dehiscence was noted following MIS requiring revision debridement and closure. Infection was low for both procedures; Scarf 1.7% and MIS 0.6%. The most frequently occurring complication following scarf osteotomy were recurrent intractable hyperkeratotic lesions (2%). Conversely following MIS, hypertrophic fracture callus was more common (8%) however poorly reported as a complication. Delayed union rates where similar; Scarf 1.7% vs MIS 1.9%. However, time to union was considerably different; Scarf 14 weeks vs MIS 24 weeks. Two asymptomatic non-unions were reported following MIS.
Quality assessment
Mean modified Coleman methodology scores (Table 6) for the scarf osteotomy and MIS were similar, scoring 61.8/100 and 63.6/100 respectively, indicating fair quality studies 10/11 papers. 1 MIS study scored low quality.21 MIS papers were marginally better at reporting outcomes and had larger subject numbers in 2 studies resulting in a higher mean score.1, 12 Risk of bias (Table 7) was high for both procedures. 2/5 scarf and 3/6 MIS studies demonstrated satisfactory outcome reporting however the remaining studies reported mean outcomes limiting subgroup or individual scrutiny.15, 16, 17, 21, 22 Scarf had marginally reduced attrition as 1 paper highlighted those lost to follow up and confirmed that their findings are only representative of completed outcome measures.18 60% of studies for each procedure included participants undergoing concomitant foot surgery introducing significant confounding.12, 16, 17, 18, 20, 23 Reporting bias was considerably high in MIS studies with discrepancies between authors as to whether hypertrophic fracture callus was a complication or expectation.
Table 6
Modified coleman methodology score
|
Study |
Study size |
Mean follow up |
Surgical approach |
Study type |
Diagnostic certainty |
Description of surgical technique |
Description of post op rehab |
Outcome criteria |
Procedure of assessing outcome |
Description of selection process |
Total |
|
Necas et al.19 (2020) |
4 |
10 |
0 |
0 |
5 |
5 |
5 |
2,0,3,0 |
5,0,3,3 |
5,5,5 |
60/100 |
|
Guha et al.17 (2012) |
0 |
4 |
0 |
0 |
5 |
5 |
5 |
2,0,3,3 |
5,0,3,3 |
5,5,5 |
53/100 |
|
Hrubina et al.23 (2015) |
0 |
7 |
10 |
0 |
5 |
5 |
5 |
2,2,3,3 |
5,0,3,3 |
5,5,5 |
68/100 |
|
Maher & Kilmartin (2010)18 |
0 |
10 |
10 |
0 |
5 |
5 |
5 |
2,0,3,3 |
5,0,3,3 |
5,5,5 |
69/100 |
|
Seide & Petersen (2001)22 |
0 |
4 |
10 |
0 |
5 |
5 |
5 |
2,2,0,0 |
5,0,3,3 |
5,5,5 |
59/100 |
|
Nunes et al.16 (2022) |
0 |
4 |
10 |
0 |
5 |
5 |
5 |
2,0,3,3 |
5,0,3,3 |
5,5,5 |
63/100 |
|
Valdivia & Thull20 (2022) |
0 |
4 |
10 |
0 |
5 |
5 |
5 |
2,3,3,3 |
5,0,3,3 |
5,5,5 |
66/100 |
|
De Vete Lima et al.15 (2020) |
0 |
4 |
10 |
0 |
5 |
5 |
5 |
2,0,3,3 |
5,0,3,3 |
5,5,5 |
63/100 |
|
Ferreira et al.1 (2020) |
4 |
4 |
10 |
0 |
5 |
5 |
5 |
2,3,3,3 |
5,0,3,3 |
5,5,5 |
70/100 |
|
Laffenetre et al.12 (2015) |
4 |
4 |
10 |
0 |
5 |
5 |
5 |
2,0,3,3 |
5,0,3,3 |
5,5,5 |
67/100 |
|
Lui21 (2014) |
0 |
4 |
0 |
0 |
5 |
5 |
5 |
2,0,3,3 |
5,0,3,3 |
5,5,5 |
53/100 |
Discussion
74 years following Davies (1949) conceptualisation of tailors bunions, foot and ankle surgeons lack substantive guidance for deformity correction and have pragmatically adopted 1st ray principles to overcome this conundrum. Scarf osteotomy has remained a staple for hallux valgus reduction due to versatile and powerful correction; its rotatory capabilities making it particularly attractive for the 5th metatarsal. 18, 24, 25, 26, 27 MIS has challenged the norm and continues to be a point of contention amongst foot and ankle surgeons. Recent systematic review identified that distal 5th metatarsal osteotomies present the lowest complication rate compared to diaphyseal or basal procedures (5%, 7% and 19% respectively) albeit with the least deformity correction.6 These data are reflective of traditional open procedures and therefore cannot be easily extrapolated to MIS, leaving a substantial void within the evidence.
MIS enthusiasts claim that they can deliver comparable outcomes to open techniques with less complications, regardless of deformity classification.28 The unstable nature of ’through and through’ percutaneous osteotomies enable powerful triplanar correction with minimal insult to the soft tissue envelope arguably maintaining vascular integrity and a degree of natural constraint with the metatarsal head migrating ‘to its ideal position’. Traditional distal osteotomy is limited by a short lever arm, with research demonstrating modest reduction in IM angle despite capital fragment rotation.29 Proximal osteotomy offers the greatest corrective power through its long lever however research is limited, with recent systematic review demonstrating a conservative 2 papers.6 Perhaps unsurprisingly the scarf osteotomy has been popularised by offsetting the limitations of capital and basal procedures.
Pooled results from the 11 included studies (Figure 3) demonstrated comparable radiological reduction of deformity and patient reported outcome measures. All papers recorded statistically significant changes in 4th IM, 5th MTP angles and return of 4th IM angles to a normal range <80. Alignment, pain, and function significantly improved for both procedures according to AOFAS with MIS demonstrating a modest mean increase compared to scarf osteotomy. Patient satisfaction was high following both procedures with scarf osteotomy marginally succeeding MIS with 97.5% vs 92.25%. The researchers would caveat these results with disparity in follow up. Scarf osteotomy demonstrated 3/5 papers with mid-term review, two of which presented results following mean review 81 months compared to mean follow up 27 months following MIS.12, 18, 19, 20 Revision surgery was limited to scarf osteotomy, however studies describing revision procedures were mid-term reviews provoking uncertainty as to whether MIS patients would require revision later.
Procedure specific complications (Figure 4) differed which could have implications for clinical practice. Wound healing and infection rates were satisfactory for both however MIS demonstrated 2 (1.3%) cases of chronic regional pain syndrome (CRPS). Limiting surgical trauma is an important advantage of MIS and therefore one would consider CRPS rates to be lower than open surgery, however these assumptions are clearly flawed. Single centre study identified risk of CRPS following foot and ankle surgery 4.36%, of which 53% occurred following forefoot procedures, although it is unknown if surgery was open or percutaneous.30 Middle aged females with a history of smoking, anxiety and depression were considered the greatest risk, however a direct comparison with this study’s findings cannot be made due to methodological bias. Females of mean age 47 years represented a majority in this study however reporting bias is limiting. Recent literature reviewing the learning curve following 3rd generation percutaneous chevron / akin osteotomy for hallux valgus identified that surgeons required on average 38 cases before reaching technical proficiency; perhaps explaining the reported incidence of CRPS.31 Regulating burr temperature with intra-operative irrigation has been attributed to minimizing soft tissue necrosis however subtle variation in stab incisions was observed across MIS studies which arguably may have been responsible for nerve injury. Tourniquet use was poorly defined for both procedures. 1 study reinforced the benefit of performing surgery wet for cooling effect on the Shannon burr.1 Increased tourniquet use was observed for scarf osteotomies however this did not present any additional sequalae, and so a relationship between omitting tourniquets and reduced complication rates cannot be drawn.
Table 7
Risk of bias
Maher and Kilmartin (2010) cautioned readers regarding the recurrence of intractable plantar hyperkeratosis (IPK), particularly in the cavoid foot, citing a higher revision rate of plantar condylectomy +/- lesion excision. Absence of prospective study or additional case series identifying this relationship limits external validity as this may represent sampling bias and error in patient selection. Lesion misdiagnosis within this study also cannot be excluded. Recent histopathological analysis of IPK identified 51.2% of these lesions to include human papillomavirus (HPV) which may explain the failure to resolve following deformity correction.32
Notable variations regarding osteotomy healing were identified which should be considered on a case-by-case basis. Most percutaneous osteotomies were stabilised post-operatively with external strapping, of which there was inter-surgeon variation in technique and duration. 61% of MIS complications involved symptomatic hypertrophic osteotomy callus persisting between 3-6 months; symptoms including pain, footwear irritation and delayed return to activity.12, 15, 16 This was poorly reported with divided opinion between the MIS authors as to whether this should be considered a complication or demoted to procedure expectation. This may conflict with patient expectations revolving MIS regarding minimal convalescence and rapid return to activity. Delayed union following MIS followed a similar pattern. Although little difference was observed regarding the incidence of delayed union (1.7% vs 1.9%), mean time to union significantly differed. It should be highlighted that 1 participant with protracted time to union (10 months) significantly affected results and perhaps could be considered an outlier, however other cases of delayed union required 4-6 months to consolidate and therefore all results have been documented for reader consideration.12, 16 It is acknowledged that discrepancies in healing are secondary to reduced stability and lack of internal fixation, however attitudes regarding their severity are arguably somewhat cavalier. Growing interest in MIS for surgical offloading diabetic foot ulceration has surfaced with advocates reinforcing the benefits of minimal soft tissue injury, immediate weight bearing and absence of retained hardware.33 Early outcomes are undeniably impressive with rapid ulcer healing and minimal convalescence however risk of propagating charcot neuroarthropathy is theoretically increased with delayed / non-union in neuropathic patients: One should caveat that to the authors knowledge there have been no documented incidences of MIS triggering charcot.34 Fracture is an established risk of scarf osteotomy, with early ambulation and vulnerability to stress risers through the osteotomy or fixation considered detrimental.35 Only 1 individual sustained an early post-operative fracture, perhaps unsurprisingly this series permitted immediate weight bearing. Despite healing with continued partial weight bearing, this is overshadowed by subsequent transfer metatarsalgia.18 2 studies kept patients non-weight bearing for 3 weeks however on balance, no significant benefit was gained with delayed union and fixation migration still occurring.19, 22 Fundamentally ideological post-operative guidelines are lacking.
High risk of bias and considerable methodological diversity was observed across all papers with retrospective observational bias impairing validity. 60% of each group included concomitant surgeries introducing considerable confounding, however readers should interpret this with a degree of pragmatism and appreciate these results as a reflection of real practice. Technical execution of percutaneous osteotomy varied, further confounding results and limiting validity. Reported scarf re-operative rates also deserve some scrutiny. Necas et al. (2020) identifies a reoperation rate of 8.8% following decompressive scarf, which the authors indicate as an acceptable range. This exceeds the UK average reoperation rate following orthopaedic trauma 8.6%.36 Acceptable revision rates remain ill-defined however one would caution accepting a higher incidence of revision surgery following clean elective cases. An interesting observation was the failure to prioritise post-operative stiffness as an outcome. MIS proponents frequently attribute reduced joint stiffness with percutaneous techniques however no single study demonstrated this. This may reflect attitudes that ROM at the 5th MTPJ is less important than 1st ray, however these shortcomings marry opinions that reduced arthrofibrosis following MIS is purely theoretical and limited by selection bias.2
Strengths
Debate regarding open and percutaneous foot surgery remains both topical and contentious. These results add to the greater body of research providing the most recent evidence to guide foot and ankle surgeons when considering between an open scarf or percutaneous osteotomy for reducing tailors bunion deformity. Clear rationale and study aims were identified, exploring topical themes, and providing meaningful data to support clinicians. PICO and PRISMA facilitated a transparent and exhaustive screening process to identify existing research. Structuring a well-defined inclusion/exclusion criterion enabled repeatable data extraction of key studies. All included papers were subjected to rigorous quality assessment and review of bias using established academic tools. Mean statistical analysis of shared clinical and patient reported outcomes provided measurable data to meet the primary objective of the project. Combined quantitative analysis and detailed narrative regarding individual procedure complications enabled remaining secondary objectives to be met.
Limitations
Low study numbers limited external validity, however fortunately, surgical episodes were similar for both procedures. Quality assessment identified heterogeneity and methodological shortcomings for all studies, with poorly reported patient demographics, and confounding. PROMs (AOFAS & FFSS) in all studies were unvalidated, generally favouring surgeon outcomes, poorly correlating with perceived patient importance factors, and grossly impairing internal validity.37 Appraisal of case series was not exempt from scrutiny and remains ambiguous. Modified Coleman Methodology Scores are convenient and repeatable quality assessment tools however can be ambiguous and interpretation can be subjective.14
Conclusion
Summary recommendations:
There is insufficient evidence to determine the most effective surgical procedure to reduce buniontte deformities.