Mallet fractures: a prospective comparison of treatment outcomes
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AJOPS | ORIGINAL ARTICLE
Hnd
PUBLISHED: 31-03-2021
Mallet fractures: a prospective comparison of treatment
outcomes
Jessica A Savage MBChB FRACS,1,2 Clara Miller MBChB MRCS,1,3 Shirley Collocott MHSc,1
Devlin Elliott MBChB,1 Karen Smith MBChB FRACS1
1 Auckland Regional Plastic Reconstructive and Hand Abstract
Surgery Unit
Background: The optimal management of mallet
Otahuhu, Auckland
fractures is controversial. Currently, published
NEW ZEALAND
evidence does not clearly define the role of surgery in
2 Department of Plastic, Reconstructive and Hand Surgery managing these fractures or identify when splinting
The Leeds Teaching Hospitals NHS Trust alone is suitable.
Leeds, England
UNITED KINGDOM Methods: An observational, prospective cohort study
was undertaken between 2012 and 2015 evaluating
3 Cardiff and Vale University Health Board
patient experience, and radiological and functional
Cardiff, Wales
outcomes following mallet fractures managed with
UNITED KINGDOM
splinting alone or surgery combined with post-
OPEN ACCESS operative splinting. This study was registered with
Correspondence our local research facility and ethical approval was
granted by the New Zealand Northern B Health and
Name: Jessica Savage
Disability Ethics Committee Health and Disability
Address: Department of Plastic, Reconstructive
Ethics Committee (HDEC) #13/NTB/202. All patients
and Hand Surgery
provided formal written consent.
The Leeds Teaching Hospitals NHS Trust
Great George Street Results: A total of 109 adult patients with 113 mallet
Leeds LS1 3EX
fractures were enrolled in the study and 85 patients
UNITED KINGDOM
with 89 fractures completed follow-up. Mean follow-
Email: Jessica.savage1@nhs.net up was 190 days. Fractures initially associated with
Phone: +44 (0)113 392 2896 subluxation of the distal interphalangeal (DIP) joint
treated with splinting alone were five times more
Citation: Savage JA, Miller C, Collocott S, Elliott D, Smith K.
Mallet fractures: a prospective comparison of treatment likely to fail to meet a minimum standard of success
outcomes. Australas J Plast Surg. 2021;4(1):48–55. than those fixed with surgery. When the fracture
DOI https://doi.org/10.34239/ajops.v4n1.222 fragment occupies between one and two thirds of
Manuscript received: 21 April 2020 the joint surface, even in the absence of initial DIP
Manuscript revised: 17 September 2020 joint subluxation, 13/35 (37%) joints subluxed during
Manuscript accepted: 11 October 2020 splint treatment.
Copyright © 2021. Authors retain their copyright in the Conclusion: This study aids clinicians by highlighting
article. This is an open access article distributed under the
where splinting is likely to fail and providing a means
Creative Commons Attribution Licence 4.0 which permits
unrestricted use, distribution and reproduction in any of identifying injuries in which surgery must be
medium, provided the original work is properly cited. considered.
Section: Hand
Keywords: avulsion fractures, splints, finger phalanges,
follow-up studies, surgery
Australasian Journal of Plastic Surgery 48 2021 Volume 4 Number 1Savage et al: Mallet fractures: a prospective comparison of treatment outcomes AJOPS | ORIGINAL ARTICLE
to inadequate outcome assessment. As a result,
only four studies were included, all published
prior to 1993, and only one compared surgery and
splinting.2,4,10
There is no universal measure of a successful
outcome for mallet fracture treatment.4 The most
frequent outcomes reported are joint enlocation
or Crawford’s criteria.2,4,11,12 Using joint enlocation
Fig 1. Botero’s 2016 illustration of the Wehbé and Schneider
classification:4 Fracture fragment grade is comprised of a number
alone lacks patient focus and using Crawford’s
reflecting the type of injury (1=not subluxed, 2=Subluxed, 3=Epiphyseal criteria lacks reproducibility, defining a poor
and physeal injury) and a letter reflecting the percentage of joint surface
involved (A 66%)
outcome as extensor lag >25 degrees and persistent
pain, without detailing how pain was assessed.
Introduction We have combined these into a defined and
Mallet fractures are caused by avulsion of the reproducible outcome measure.
extensor tendon from the distal phalanx and may The purpose of this study is to provide a patient-
be associated with distal interphalangeal (DIP) focused, multifaceted assessment of surgical and
joint subluxation. Treatment aims to improve non-surgical treatment of acute mallet fractures.
the early clinical outcome and prevent long-term We compare continuous external splinting,
arthritis, deformity and pain. Maintenance of primary surgical intervention plus splinting and
range of motion (ROM), strength and function, delayed surgery which follows a failed attempt
with absence of deformity or complication, is key at splinting. We aim to answer the question: Is
to patient wellbeing. splinting or surgery the best treatment for acute
Mallet fractures range in severity from small, mallet fractures?
minimally displaced avulsions with enlocated
Method
joints to large, displaced fracture fragments with
Between June 2012 and June 2015, adult patients
associated joint subluxation.1,2 The Wehbé and
presenting with mallet fractures, in Auckland and
Schneider classification for bony mallet injuries
Counties Manukau District Health board regions
assigns a number to reflect joint subluxation and
of New Zealand, were identified by their treating
a letter to reflect the percentage of joint surface
clinician and referred to our research team. A
involved (Figure 1).3,4
written consent process was undertaken. Table 1
Various surgical techniques have been described
details inclusion and exclusion criteria. Weekly
in mallet fracture treatment. Frequently a trans-
review of discharge coding minimised missing
DIP joint Kirschner (K) wire is employed. Ishiguro
potential participants.
first described the closed extension block pinning
The research team prospectively populated a
technique, which adds a second blocking K-wire,
database using clinical records and radiographs,
a technique modified by other authors since.5,6
becoming involved in patient assessment only
Alternatively Kronlage, Teoh and Theivendran
after three months. At enrolment, the first author
have all illustrated open reduction and internal
reviewed the best available, splint-free lateral
fixation with screws or a plate.7,8,9
radiograph, and the injury was classified according
Currently, published evidence does not clearly
to Wehbé and Schneider classification.
define the role of surgery in managing mallet
The study was observational. Enrolment did not
fractures. Handoll and colleagues attempted a
alter the patient’s treatment. We measured patient
Cochrane review in 2004 to assess the efficacy of
experience and outcomes over time, following
different treatment methods. They concluded that
initiation of either surgery or splinting. We did not
many studies were methodologically flawed, due
analyse the clinical decision-making process.
Australasian Journal of Plastic Surgery 49 2021 Volume 4 Number 1Savage et al: Mallet fractures: a prospective comparison of treatment outcomes AJOPS | ORIGINAL ARTICLE
Table 1: Inclusion and exclusion criteria motion was assessed using a dorsally placed hand-
Inclusion criteria Exclusion criteria
held goniometer. An illustrated protocol promoted
Acute bony mallet injury of Mallet thumb fractures
consistent measurements between researchers.
a digit
Patients completed validated patient-rated
PresentingSavage et al: Mallet fractures: a prospective comparison of treatment outcomes AJOPS | ORIGINAL ARTICLE
Table 2: Demographics
Splinting Surgery Delayed P value
surgery (ifSavage et al: Mallet fractures: a prospective comparison of treatment outcomes AJOPS | ORIGINAL ARTICLE
analysis. Significantly more type IIB injuries criteria for success than those in the surgery group
were treated surgically than with splinting alone (hazard ratio 5.04, CI 1.24–20.5; p value 0.03).
(28/40) (Table 2). The splinted group comprised 46
patients—eight type IA fractures, 27 type IB, two Secondary outcome analysis
type IIA and nine type IIB. Type IB (without subluxation, moderate fragment)
Of the 10 IIB fractures initially managed with Of the 40 IB fractures, 35 were initially splinted
splinting, one was operated on at three weeks to and five were operated on. No surgically managed
reduce the subluxation (moved to the delayed fingers subluxed following treatment (0/5). Of those
surgery group), two presented late and another IB fractures managed with splinting, 37 per cent
was deemed unfit for surgery, so subluxation was (13/35) subluxed during treatment. Eight of these
accepted. Of the remaining six, five were reduced were re-allocated to the delayed surgery cohort.
and maintained enlocation with a customised The remaining five either were not detected or the
splint. The sixth was pain free with DIP joint ROM decision was made to continue splinting.
0/65 so the result was accepted.
Type IIB (subluxed, moderate fragment)
Nine fractures (in nine patients) underwent delayed
surgery following a period of splinting alone. Of Of the 37 IIB fractures, 27 were operated on from
these eight were initially classified as IB fractures, the outset and 10 were initially managed with
but subluxed after commencing splinting, and one splinting. Of those surgically managed, 20 were
was IIB (mentioned above) but a trial of splinting without subluxation on final radiograph (20/27),
failed to maintain reduction. six subluxed and one failed to complete the final
radiograph. Of the 10 splinted, one was operated
Overall success on within the first week of splinting and this was
Overall treatment success was defined as achieving without subluxation at six months. Five of the nine
a minimum standard in three key outcomes (joint that continued splinting were without subluxation
enlocation, pain score and extensor lag). Of the on final radiograph. Kaplan-Meier estimates were
89 fractures, four fractures in three patients had used to account for the different follow-up dates
insufficient data for assessment of all criteria—two and revealed that the likelihood of a joint being
lacked radiographs at >70 days post injury and two without subluxation at six months with splinting
failed to complete pain score questionnaires. versus surgery was 52 per cent versus 80 per cent
When all injury grades were combined, no (p value 0.11, log rank test).
significant differences in success were seen
Predicting subluxation
between treatments—80 per cent success for
The size of the fracture fragment is correlated to
splinted versus 85.7 per cent for surgical patients
the risk of subluxation, with larger fragments
(hazard ratio 7.88, CI 2.14–29; p value 0.09 [adjusted
more likely to sublux. In those that did not sublux
for confounders]).
at any point, the fracture fragment occupied a
Primary outcome analysis mean of 42 per cent of the joint surface (SD=12.7)
Type IB (without subluxation, moderate fragment) compared with a mean of 48 per cent in those that
did sublux during treatment (SD=9.1, p value=0.02).
No significant difference in final overall treatment
Fractures occupying over 46 per cent of the joint
success was seen between the splinting and surgery
surface have a significantly increased chance of
groups for IB fractures (hazard ratio 0.91, CI 0.10–
subluxation compared with those occupying less
8.28; p value 0.93).
than 46 per cent (67% versus 42%). Every one per
Type IIB (subluxed, moderate fragment) cent increase in fracture fragment size increases
the risk of subluxation by five per cent (OR 1.054
Type IIB injuries treated with splinting alone were
(1.01, 1.10)). Despite enlocation at presentation,
five times more likely to fail to meet our minimum
when a grade 1B fracture fragment reaches 43 per
Australasian Journal of Plastic Surgery 52 2021 Volume 4 Number 1Savage et al: Mallet fractures: a prospective comparison of treatment outcomes AJOPS | ORIGINAL ARTICLE
cent of the joint surface, the fracture has a 50 per in both treatment groups achieved normal mean
cent chance of subluxation. Q-DASH subjective function scores.13
Pain score (PRWHE pain assessment) Satisfaction
There was no significant difference in pain scores With all injury grades combined, significantly
between the splinting and surgery groups at late lower PEM2 satisfaction scores were found in the
follow-up (median score 6, IQR 1–13 and 12, IQR surgery group at six months (median 79%; IQR: 59.1,
4–18, respectively) 89.4) compared with the splinting group (median
91%; IQR: 82.6, 98.5), with a median difference in
Range of motion
score of 11 per cent (1.18, 21.1, p value 0.029). A
Mean extension deficit was 9.53 degrees (SD=9.5) in higher PEM2 score means a more satisfied patient.
the splinted fractures and 10.9 degrees (SD 12.2) in When injury grades were analysed separately, no
surgically managed fractures. The difference was significant differences were noted between the
not significant. An apparent difference of mean treatment groups.
flexion deficit between the splinting group (13.4°,
SD=19.2) and the surgery group (26.1°, SD=12.9) did Complications
not reach statistical significance when adjusted for Surgery had a high rate of complications, especially
covariates in injury type, follow-up time and delay in the delayed surgery group. In fractures that
in treatment. failed initial splinting. Infection was frequent,
occurring in 3/9 (33%) fractures. Failed fracture
Quick-DASH scores reduction occurred in 2/9 fractures (22%) (Table 3).
There was no significant difference in subjective
functional outcome between the splinting and Discussion
surgery groups or in subgroup injury grade analyses Historically the treatment of mallet fractures has
when measured with Q-DASH. Quick-DASH scores been conservative. A recent systematic review of
remained stable at early and late follow-up. At late 44 studies included just five comparing surgical
follow-up, the splinting group Q-DASH mean score interventions with splinting in acute mallet
was 6.8 (SD=8.96) and for the surgery group it was injuries, four of which were published prior to
13.6 (SD=13.5). These scores suggest that patients Handoll and colleagues 2004 Cochrane review10
Table 3: Complications
Splinting Surgery Delayed surgery
n=46 n=34 n=9
Fingers affected by one or more complications 19 23 8
Major complications
Infection*† 0 3 (9%) 3 (33%)
Failed fracture reduction 12 (26%) 8 (24%) 2 (22%)
Need for unplanned surgery 0‡ 6 (18%) 4 (44%)
Minor complications (Clavien-Dindo grade I)
Dorsal lump/callus 11 12 4
Nail deformity 0 3 4
Irritation of skin from splint/ metalware 2 6 3
Wound-healing problem n/a 2 1
Metalware malposition* n/a 10 1
† Infection defined as requiring admission or washout
‡ 9/55 (16%) of the patients initially in the splint cohort required unplanned delayed surgery (delayed surgery cohort)
* metalware displaced on final radiograph (deemed to be in joint line or loosened and backed-out of fragment)
Australasian Journal of Plastic Surgery 53 2021 Volume 4 Number 1Savage et al: Mallet fractures: a prospective comparison of treatment outcomes AJOPS | ORIGINAL ARTICLE and in total included only 90 mallet fractures.10,12 This study highlights the risk of subluxation in Current management is based on 40-year-old fractures initially presenting enlocated—37 per research, with the tendency to avoid surgery. A cent of the IB fractures in this study subluxed. survey conducted in the United Kingdom in 2017 Once the fragment exceeded 46 per cent of the reported that 88 per cent of bony mallet injuries joint surface, subluxation during treatment was are being managed conservatively.14 significantly more likely (67% versus 42%). If not This current study is unique. To the authors’ detected and corrected, that fracture will fail to knowledge, it is the largest published prospective, meet our minimum standard of success. Surgery comparative study of mallet fractures. In line with could be considered at an early stage. If splinting the Handoll and colleagues recommendations, is commenced, we advocate early detection of defined and reproducible outcome assessments subluxation as delayed surgery appears to be have been used, complications reported and associated with more complications. We subscribe thorough statistical analysis conducted. One of the to Crawford’s recommendation to attain a lateral strengths of this study is that it includes patients radiograph of the joint once in the splint, then treated in hospitals and hand therapy practices in weekly for the first three weeks.11 our region. We did not alter treatment or question Although not statistically significant, surgery was the rationale of initiating certain treatments. This associated with a high complication rate, especially methodology highlights variation in practices in the delayed surgery group. These findings were and shows that rules which percolate surgical not dissimilar to previous studies led by Wehbé, communities do not dictate all practices. We Kang and Yoon.4,15,16 observed 10 IIB fractures that commenced splinting We acknowledge limitations with our research. This and six grade I fractures that were operated on is a non-randomised observational study and the from the outset. surgical techniques used were heterogeneous—a We acknowledge that we did not find a significant reflection of the number of surgeons involved. difference in overall success between the splinting This limits recommendations for specific surgical and surgery groups, which would align with techniques. We achieved a median follow-up time existing literature. However, the surgery group of 190 days (six months) but it is the senior author’s consisted of more complex and unstable fracture opinion that further symptomatic improvement patterns. Subgroup analysis showed that patients would occur beyond six months. with type IIB fractures managed with splinting We believe that in certain fractures, with a large alone have a five times greater risk of treatment fragment and early subluxation, surgery must failure (hazard ratio 5.04, CI 1.24–20.5) compared be considered and offers a significantly greater with surgery. There is a higher likelihood that their chance of treatment success than splinting alone. joint will remain subluxed but the consequences of this long term are unknown. Conclusion As with any surgical intervention, the risks and In the treatment of bony mallet fractures, we potential benefits must be weighed up against strive for DIP joint enlocation, maintained range of the individual patient’s goals and comorbidities. motion and a pain-free outcome. Type IIB fractures While surgery may be advantageous in certain are significantly less likely to meet our minimum subgroups for certain outcome measures it leads standard of success with splinting alone and to significantly lower satisfaction when all injury surgery is recommended. Type IB fractures can be grades are analysed together. This may reflect treated successfully by splinting alone; however, worse fracture severity in the surgery group. No this study highlights the significantly increased difference in satisfaction (PEM2) score was seen risk of subluxation as the fracture fragment size analysing the injury grades separately. increases. Australasian Journal of Plastic Surgery 54 2021 Volume 4 Number 1
Savage et al: Mallet fractures: a prospective comparison of treatment outcomes AJOPS | ORIGINAL ARTICLE
This is the largest recent comparison study 7 Kronlage SC, Faust D. Open reduction and screw fixation
of mallet fractures. J Hand Surg. 2004 Apr;29(2):135–38.
for the treatment of bony mallet fractures and
https://doi.org/10.1016/j.jhsb.2003.10.012 PMid:15010158
provides thorough, reproducible, patient-focused
8 Teoh LC, Lee JY. Mallet fractures: a novel approach to inter-
outcome measures. Our results provide guidance
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for surgeons who strive for joint enlocation, Feb;32(1):24–30. https://doi.org/10.1016/j.jhsb.2006.09.007
highlighting which fractures are likely to fail and PMid:17134796
providing clinicians with data to compare their 9 Theivendran K, Mahon A, Rajaratnam V. A novel hook
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Disclosure
10 Handoll HH, Vaghela MV. Interventions for treating mallet
The authors have no financial or commercial
finger injuries. Cochrane Database Syst Rev. 2004(3). https://
conflicts of interest to declare. doi.org/10.1002/14651858.CD004574.pub2
This work was supported by the Sir William and 11 Crawford GP. The moulded polythene splint for mallet fin-
Lois Manchester Trust. Reduced radiology costs ger deformities. J Hand Surg Am. 1984;9(2):231–37. https://
doi.org/10.1016/S0363-5023(84)80148-3
were offered by our local imaging providers
12 Lin JS, Samora JB. Surgical and nonsurgical management
Auckland Radiology Group, Mercy Radiology, The
of mallet finger: a systematic review. J Hand Surg. 2018 Feb
Radiology Group and Horizon Radiology. 1;43(2):146–63. https://doi.org/10.1016/j.jhsa.2017.10.004
PMid:29174096
Acknowledgements
13 Aasheim T, Finsen V. The DASH and the QuickDASH instru-
The authors wish to acknowledge Irene Zeng, and ments: normative values in the general population in Nor-
Christin Coomarasamy, biostatisticians, for their way. J Hand Surg (Eur Vol). 2014 Feb;39(2):140–44. https://
doi.org/10.1177/1753193413481302 PMid:23520389
invaluable assistance with this project.
14 Tolkien Z, Potter S, Burr N, Gardiner MD, Blazeby JM, Jain
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