Central slip extensor tendon injuries: a systematic review of treatments

Abstract

This systematic review describes and compares outcomes of operative and non-operative management of central slip extensor tendon injuries. A PRISMA-compliant methodology identified 3785 studies. Of these, 29 underwent full text review. No randomized controlled trials were identified. Nine studies evaluated treatment modalities specific to cohorts with acute central slip injuries in adults. A range of operative and non-operative elements of management was identified although no studies directly compared the two. Where aspects of rehabilitation were studied, this was always after surgery. The evidence base regarding treatment of central slip injury is limited and the roles of different treatment strategies for open as well as closed injuries are not well-supported by evidence.

Keywords

Tendon injuries splints reconstructive surgical procedures finger injuries central slip extensor zone 3

Introduction

Extensor tendon injuries are commonly encountered with disproportionate representation of young, otherwise healthy males in the patient demographic (De Jong et al., 2014). Injury mechanisms include hyperflexion, direct blunt trauma and penetrating trauma. Blunt trauma and hyperflexion trauma often cause a closed injury, one that is commonly encountered in athletes (Weiland, 2012). Penetrating injuries have a comparatively higher incidence than blunt ones, with zone III extensor tendon injuries accounting for 13% of all open tendon injuries presenting to emergency departments (De Jong et al., 2014). When left untreated, disruption of the extensor mechanism over zone III and detachment of the central slip results in a boutonnière deformity characterized by flexion of the proximal interphalangeal (PIP) joint and hyperextension of the distal interphalangeal (DIP) joint due to volar subluxation of the lateral bands (Massengill, 1992). Disfigurement and impaired hand function are common following central slip injury and thus it represents a potential cause of significant morbidity (El-Sallakh et al., 2012).

Closed central slip injuries without substantial bony involvement can be managed non-operatively, using PIP joint extension splinting. Regimens used include immobilization, dynamic splinting and progressive static splinting (also termed serial splinting) (Evans, 1994; McAuliffe, 2011). Operative management strategies include acute central slip repair, open reduction and internal fixation (ORIF), tendon reconstruction and arthrodesis (Matzon and Bozentka, 2010). ORIF may be applicable when an amenable fracture pattern is present, and arthrodesis should be reserved for patients with PIP joint contractures and degenerative change associated with chronic injury (Imatami et al., 1997). If the central slip is repaired operatively, postoperative PIP joint extension splinting is advocated. Operative approaches might be considered most appropriate for open injuries, which necessitate exploration, debridement and irrigation (Colzani et al., 2016).

Current management strategies appear to be informed by anecdotal evidence, without reference to comparative outcome data between operative and non-operative treatment. The aim of this systematic review is to identify reported management strategies of acute open and closed central slip injury and appraise their clinical outcomes.

Methods

Methods were developed using the PRISMA statement, and the protocol was registered in the prospective register of systematic reviews (PROSPERO).

Eligibility criteria

Randomized controlled trials, non-randomized controlled trials, cohort studies, case-control studies, case series and case reports were included, irrespective of sample size. Expert opinion, review articles and narrative descriptions of operative technique without an accompanying report of novel clinical data were excluded.

Participants

All studies examining acute, acquired, open or closed central slip injury of index-little digits in adults (aged 18 or older) presenting within one month of injury were included. Studies that included patients with multiple digital injuries, including fractures and open injuries were included. Extensor pollicis longus injuries, iatrogenic central slip injuries and those presenting late with boutonnière deformity or joint destruction that would require other treatment strategies, were excluded.

Interventions and comparators

Both operative and non-operative management strategies were eligible for inclusion. Details of the type and duration of rehabilitation protocols were extracted. Given the potentially broad nature of eligible interventions, multiple comparisons were considered: operative v. non-operative strategies, comparisons between different types of operative repair, comparisons between different types of non-operative strategy, comparisons of outcome measures used following intervention, rehabilitation type and duration following operative and non-operative management strategies.

Outcomes

The outcomes assessed included active finger range of motion, joint angles, mean grip strength, the incidence of complications, the need for further salvage procedures such as arthrodesis, and patient-reported outcome measures (PROMs) used, of which generic, upper limb-specific and hand-specific might be expected.

Search strategy

Search strategies were developed using index and free text terms, in conjunction with a search strategist. Full search strategies are given in the supplementary material, Appendix S1. They were applied to Medline & In Process (1946–July 2017) EMBASE (1974–July 2017) and CINAHL (1981–July 2017) in July 2017. The reference lists of included articles were hand searched for further relevant publications. The literature search was limited to human studies. A second database search, and in addition the Cochrane Central Register of Controlled Trials (CENTRAL), was conducted on 25 August 2018.

Study selection

After pooling and electronic de-duplication, two authors (LG, JCRW) independently screened all abstracts against pre-specified stepwise inclusion criteria (see Figure 1, PRISMA flow chart). Disagreements were resolved by discussion with a third author.

Data extraction and analysis

Standardized data extraction was performed in duplicate (LG, JCRW). Extracted data was then collated and compared. Methodological quality of studies was assessed. Randomized controlled trials were assessed using the Cochrane Risk of Bias tool (Higgins et al., 2011). Non-randomized comparative studies were assessed using the Cochrane Risk of Bias in non-randomized studies of interventions (ROBINS-I) tool (Sterne et al. 2016). The National Institute of Health quality assessment tool for cohort studies was employed to assess the quality of cohort studies (National Institutes of Health, 2014). The CARE checklist was used to assess the quality of case reports (Gagnier et al., 2013).

Results

Search results

A total of 3248 records were identified through database searching: 506 from EMBASE, 2079 from Medline, 128 from CINAHL and 535 from CENTRAL. Although it was anticipated that studies discussing boutonnière deformities would be specific to chronic presentations, to minimize any data loss, a second electronic search and screening for boutonnière deformity specifically was performed. This yielded an additional 537 studies. Overall, 3785 studies were identified, and 3279 were screened after de-duplication. The combination of both searches is summarized in Figure 1. The 29 remaining full text articles were assessed for study eligibility, with nine studies meeting inclusion criteria. Given the large number of excluded studies, they are not provided here, details are available on request.

Study characteristics

There were no randomized controlled trials, and no non-randomized comparative studies were identified (Table 1). Of the included studies, eight were cohort studies based on an established definition (Dekkers et al., 2012). One case report met inclusion criteria. Two studies were prospective in study design. Data from a subset of patients in a third study reported prospective data.

Table 1.

Overview of quality included studies, using the NIH quality assessment tool for cohort studies and the CARE checklist for case reports.

Reference	Study type	n patients (digits)	Injury complexity		Open/ closed injury	Primary treatment strategy	Repair technique	Quality of evidence as per NIH and CARE checklists	Justification
Reference	Study type	n patients (digits)	Simple	Complex	Open/ closed injury	Primary treatment strategy	Repair technique	Quality of evidence as per NIH and CARE checklists	Justification
Evans et al., 1994	Cohort study	55 (64)	15	49	Open	Surgical	Not reported	Fair	Categorized extent of central slip injury before intervention. Continuous evaluation of outcome measures throughout study.
Feuvrier et al., 2014	Cohort study	4 (4)	0	4	Open	Surgical	Palmaris longus autograft	Poor	Very small sample size although 5-year follow-up period. Range of functional and patient reported outcome measures used.
Hou, 2014	Cohort study	8 (8)	0	8	Closed	Surgical	Palmaris longus autograft	Poor	Study population not clearly defined, lack of clinical information related to mechanism and extent of central slip injury. Subjective interpretation of finger straightening used as the only outcome measure.
Maddy, 1997	Cohort study	5 (7)	2	5	Open	Surgical	Not reported	Fair	Small sample size but justified. Outcome assessors not blinded to exposure status of patients. Very limited follow up.
McAuliffe et al., 2011	Case report	1 (1)	1	0	Open	Surgical	Modified Kessler	Poor	Limited injury specific details and reporting of outcome measurements.
Mehdi et al., 2011	Cohort study	8 (8)	0	8	Open	Surgical	Mitek mini bone anchor	Fair	Pre-operative measurement of functional disability although not reported. Adequate follow up (average 11 months).
O’Dwyer et al., 1990	Cohort study	99 (99)	91	8	Open	Surgical	Modified Kessler	Fair	No reporting of inclusion and exclusion criteria. Heterogeneity in splinting compliance amongst study participants.
Pratt et al., 2002	Cohort study	27 (31)	26	5	Open	Surgical	Not reported	Fair	Limited injury specific data. 34% lost to follow up, short follow up (8 weeks).
Saldana et al., 1991	Cohort study	18 (22)	22	0	Not reported	Surgical	Figure of 8	Fair	Extent of central slip injury classified, although did not analyse effect on outcome measures. No loss to follow up reported.

Quality of included studies

All studies were assessed to be fair or poor quality, as outlined in Table 1, with a mean sample size of 27 (SD 33) patients. Included studies provided varying clinical descriptions of the extent of central slip injury, management and rehabilitative strategies. The effect of potential confounding variables was seldom reported and loss to follow up varied from 0 to 34%.

Demographics and injury details

In the nine included studies, there were 225 patients with 244 digits with central slip injuries; 80% were male with a mean age of 36 (range 29–70) years. Five out of the nine included studies reported that definitive management was started within 72 hours of injury. The remaining four studies did not specify how long after initial injury definitive management was commenced. All injuries were considered to have been managed within one month of injury based on consensus discussion between authors. The mean duration of follow up was 23 (SD 30.7) months. The mechanism of injury resulted in open central slip lacerations in 251 (97%) of 259 injuries. Thus, little data describing the management of closed injuries was identified. Overall, 87 (38%) of 259 injuries involved bone and joint capsule and were thus considered complex (Evans, 1994). The majority of injuries included were simple (without bony involvement).

Interventions and rehabilitation

All studies reported operative repair as definitive management of both open and closed central slip injury, with variation in repair technique. One study reported the management of closed injuries (Hou et al., 2014), and one further study did not specify the nature of injuries (Saldana et al., 1991). The mean length of postoperative rehabilitation was seven weeks. Rehabilitation protocols also varied in terms of the number and type of splints used, the duration of dynamic and static splinting, and the total length of splinting protocols. Generally, protocols which implemented early dynamic splinting appeared to be well tolerated and were associated with favourable functional outcomes, as outlined in Table 2.

Table 2.

Rehabilitation and reported outcome data for included studies.

Reference	Rehabilitation protocol	Average rehabilitation duration	Splints used	Reported outcome

Evans et al., 1994	Group 1: Continuous immobilization followed by active flexion extension exercises	POW1–4: Immobilization with PIP joint at 0° POW5: 30° PIP and DIP flexion POW6: 40° PIP and DIP flexion POW7: 50° PIP and DIP flexion	Palmar thermostatic splint Template splints used during short arc motion to provide specified amount of PIP and DIP flexion	Mean PIP loss of active extension: 8° Mean PIP joint active flexion: 72° Mean DIP joint active flexion: 38°
Evans et al., 1994	Group 2: Early short arc motion followed by controlled mobilization at 4 weeks.	POW1: Immobilization with PIP joint at 0° POW2: 30° PIP and DIP flexion POW3: 40° PIP and DIP flexion POW4: 50° PIP and DIP flexion	Palmar thermostatic splint Template splints used during short arc motion to provide specified amount of PIPJ and DIP joint flexion	Mean PIP loss of active extension: 3° Mean PIP joint active flexion: 88° Mean DIP joint active flexion: 45°
Feuvrier et al., 2014	Unknown	Unknown	Unknown	Mean TAM: 160° Mean qDASH score: 19 Average grip strength: 41%
Hou, 2014	Unknown	Unknown	Unknown	Objective outcome reported: ‘All patients could straighten their ring fingers and make fists with the left hand.’
Maddy, 1997	Immobilization, DIP joint flexion with PIP joint in full extension commenced 7 days post-operatively followed by dynamic extension assist splinting	POW1: Immobilizationv POW2–3: DIP flexion exercise with PIP joint in full extension POW4: Dynamic extension assist splinting Static night splinting throughout	Alumofoam PIP extension splint DIP sparing PIP extension splint made from Hexcelite Modified Wynn Parry splint (thermoplastic dorsal proximal phalanx component)	Mean TAM: 175° Average grip strength: 81%
McAuliffe et al., 2011	Immobilization followed by early active short arc motion, POD3.	POW1–3 Full DIPJ and PIPJ extension when not performing active exercise. POD3–7: 30° PIPJ and DIPJ flexion POW2: 40° PIPJ and DIPJ flexion POW3: 50° PIPJ and DIPJ flexion POW4: Intermittent static splinting on a gradual basis as controlled mobilization is continued Static night splinting throughout	Palmar resting splint Template splints used during short arc motion to provide specified amount of PIPJ and DIPJ flexion	Mean PIPJ active flexion: 60° Mean PIPJ loss of active extension: 0°
Mehdi et al., 2011	Immobilization with k-wire or splint followed by gradual mobilization with passive then active PIPJ mobilization.	POW1–2: Immobilization POW3: Passive PIPJ mobilization followed by active PIPJ mobilization (time unknown)	Unknown	Mean ROM: 73% Average grip strength: 82.5%
O’Dwyer et al., 1990	Immobilization followed by dynamic extension assist splinting	POW1–2: Immobilization POW3–8: Dynamic splinting	Volar plaster slab Capener spring splint	Devised functional assessment scale. Early results: Excellent/good 70%; fair/poor 30%. Long-term results: Excellent/good: 88.6%; fair/poor: 11.4%
Pratt et al., 2002	PIPJ immobilization with hourly DIPJ flexion extension exercises followed by dynamic extension assist splinting. Active extension then commenced with strengthening exercises.	POW1–2: PIPJ Immobilization POW3–5: Dynamic splinting POW6: Active PIPJ extension	Three-quarter cylinder splint Capener spring splint Active PIPJ exercises	Mean PIPJ active flexion: 94° Mean TAM: 237°
Saldana et al., 1991	PIPJ immobilization with hourly DIPJ flexion extension exercises. Progressive flexion of MCPJ from 30° in week 1 to 90° in week 6. Followed by assisted extension with eventual dynamic extension.	POW1: PIPJ immobilization with MCPJ flexion to 30° POW2: PIPJ immobilization with MCPJ flexion to 45° POW3: PIPJ immobilization with MCPJ flexion to 60° POW4: Active MCPJ flexion to 60° POW5–7: Dynamic extension with MCPJ flexion to 90°	Dorsal finger extensor assisted splint (aluminium, wrist at 35-45° of extension) Aluminium splint removed, leather yoke under PIPJ	Mean PIPJ loss of active extension: 2.5° Mean TAM: 169°

DIPJ: distal interphalangeal joint; PIPJ: proximal interphalangeal joint; MCPJ: metacarpophalangeal joint: POD: post-operative day; POW: post-operative week; K-wire: Kirschner wire; TAM: total active motion; ROM: range of motion; qDASH: quick disabilities of the arm, shoulder and hand score.

Outcome measures

Collectively, nine different outcome measures were used across all studies, the majority of which were physician-reported measures of function. A bespoke functional scale based on flexion and extension was reported in one study, and only one study used a patient-rated outcomes measure (PROM), the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) (Feuvrier et al., 2014). All eight studies reporting functional outcome used combinations of outcome measurements at varying follow up time-points.

Outcomes

Comparison could only be made between postoperative rehabilitation involving active mobilization v. immobilization. An active mobilization rehabilitation after operative repair achieved statistically significantly better results than immobilization in the only comparative study identified in this review (Evans, 1994). Other single arm studies involved varying lengths of immobilization, typically around 3 weeks, often followed by mobilization. However, in those studies, mobilization involved spring-mounted dynamic splints to support extension, rather than the shortened arc of motion regimen.

Discussion

Suboptimal treatment of central slip injuries may result in impaired finger movement, joint stiffness and progression to boutonnière deformity (Evans and Thompson, 1992; Pratt et al., 2002). We examined the evidence for different management and rehabilitation options following acute open and closed central slip injuries in the literature. Of the nine studies that met inclusion criteria, seven reported management of open injuries, one reported the management of closed injuries and one did not specify. All studies reported operative repair of the central slip in the first instance, with various postoperative rehabilitation protocols employed. There were limited comparative data, and no consensus on outcome measurement.

We did not identify any evidence to examine the role of non-operative management or for the management of closed injuries. This may represent a dogmatic acceptance of conventional approaches to managing such injuries, or it may represent a lack of academic investment in studying such injuries, perhaps owing to the perceived success of conservative treatment of closed injuries.

Most evidence included considered rehabilitations regimens, in the context of rehabilitation after operative repair. Extrapolating this to non-operative management may not be appropriate. Different rehabilitation protocols were reported, which can be broadly classified into: PIP joint immobilization followed by an isolated PIP flexion–extension exercise, controlled early active short arc motion, and PIP joint immobilization followed by mobilization with a dynamic spring coil finger splint (Pratt et al., 2002). There was limited evidence to define roles for the different regimens. Evans’ comparative study investigating outcomes after prolonged immobilization and early short arc motion (SAM) reported significantly better functional results in the SAM cohort (Evans, 1994). However, Pratt et al. (2002) demonstrated a comparable angular outcome with a mean PIP joint active flexion of 94° (compared to 88° in Evans’ SAM cohort) following the implementation of hourly DIP joint flexion exercises throughout the PIP joint immobilization period. This was followed by dynamic splinting initiated after three weeks, potentially challenging the superiority of SAM. The comparison is limited by discrepancies in cohort size, demographics and operative strategies between the two studies. Furthermore, Maddy et al. (1997) used a similar rehabilitation strategy to Pratt et al., implementing dynamic splinting from the fourth postoperative week (after immobilization), but this yielded less mean total active motion. There was no evidence to support the use of prolonged immobilization (more than three weeks).

Given the barriers to combining the findings of different studies here, this may be the main conclusion for clinical practice at present. There is a lack of standardized outcome measurement, but the existing evidence is largely based on angular measurements. Despite the growing use of PROMs in hand surgery research in general, only one study comprising four patients reported PROMs and used the QuickDASH. Functional measures and range of motion, such as the Strickland-Glogovac formula (Strickland and Glogovac, 1980), were widely reported; whether these endpoints are of relevance to patients is not clear.

Our results must be considered in view of the study limitations. Although a sensitive strategy was used, it is possible that relevant publications may not have been identified. Further, this study considers management strategies reported within the literature and may not reflect current clinical practice. The current evidence base for the management of central slip injuries is limited. All current studies reported operative repair, and the role of non-operative management remains equivocal. Evidence from individual studies tentatively supports the use of early mobilization and does not support prolonged immobilization.

Supplemental Material

Supplemental material for Central slip extensor tendon injuries: a systematic review of treatments

Supplemental Material for Central slip extensor tendon injuries: a systematic review of treatments by Luke Geoghegan, Justin Conrad Rosen Wormald, Raina Zarb Adami and Jeremy N Rodrigues in Journal of Hand Surgery (European Volume)

Footnotes

Declaration of conflict of interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: JCRW is an NIHR Academic Clinical Fellow. JNR is an NIHR Postdoctoral Fellow. This article presents independent research funded by the National Institute for Health Research (NIHR). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

References

Colzani

Tos

Battiston

Merolla

Porcellini

Artiaco

. Traumatic extensor tendon injuries to the hand: Clinical anatomy, biomechanics, and surgical procedure review. J Hand Microsurg. 2016, 8: 2–12.

De Jong

Nguyen

Sonnema

AJM

Nguyen

Amadio

Moran

. The incidence of acute traumatic tendon injuries in the hand and wrist: A 10-year population-based study. Clin Orthop Surg. 2014, 6: 196–202.

Dekkers

Egger

Altman

Vandenbroucke

. Distinguishing case series from cohort studies. Ann Intern Med. 2012, 156: 37–40.

El-Sallakh

Aly

Amin

Hegazi

. Surgical management of chronic boutonnière deformity. Hand Surg. 2012, 17: 359–64.

Evans

. Early active short arc motion for the repaired central slip. J Hand Surg Am. 1994, 19: 991–7.

Evans

Thompson

. An analysis of factors that support early active short arc motion of the repaired central slip. J Hand Ther. 1992, 5: 187–201.

Feuvrier

Loisel

Pauchot

Obert

. Emergency repair of extensor tendon central slip defects with oberlin's bypass technique: Feasibility and results in 4 cases with more than 5 years of follow-up. Chir Main. 2014, 33: 315–19.

Gagnier

Kienle

Altman

Moher

Sox

Riley

. The care guidelines: Consensus-based clinical case reporting guideline development. Glob Adv Health Med. 2013, 2: 38–43.

Higgins

Altman

Gøtzsche

, et al. The Cochrane Collaboration’s tool for assessing risk of bias in randomized trials. BMJ. 2011, 343: d5928.

10.

Hou

Zhao

Xiao

Zhou

. Successful surgical repair of central slip rupture in finger extensor tendon. In Vivo. 2014, 28: 599–603.

11.

Imatami

Hashizume

Wake

Morito

Inoue

. The central slip attachment fracture. J Hand Surg Br. 1997, 22: 107–9.

12.

Maddy

Meyerdierks

. Dynamic extension assist splinting of acute central slip lacerations. J Hand Ther. 1997, 10: 206–12.

13.

Massengill

. The boutonnière deformity. Hand Clin. 1992, 8: 787–801.

14.

Matzon

Bozentka

. Extensor tendon injuries. J Hand Surg Am. 2010, 35: 854–61.

15.

McAuliffe

. Early active short arc motion following central slip repair. J Hand Surg Am. 2011, 36: 143–6.

16.

Mehdi

Masood

Lawlor

Eadie

. Repair of the central slip of extensor tendon and the open mallet using Mitek mini bone anchors. Eur J Plast Surg. 2011, 34: 13–17.

17.

National Institutes of Health. 2014. Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Available at: https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools.

18.

O’Dwyer

Quinton

. Early mobilization of acute middle slip injuries. J Hand Surg Am. 1990, 15: 404–6.

19.

Pratt

Burr

Grobbelaar

. A prospective review of open central slip laceration repair and rehabilitation. J Hand Surg Am. 2002, 27: 530–4.

20.

Saldana

Choban

Westerbeck

Schacherer

. Results of acute zone III extensor tendon injuries treated with dynamic extension splinting. J Hand Surg Am. 1991, 16: 1145–50.

21.

Sterne

Hernán

Reeves

, et al. ROBINS-I: a tool for assessing risk of bias in non-randomized studies of interventions. BMJ. 2016, 355: i4919.

22.

Strickland

Glogovac

. Digital function following flexor tendon repair in zone ii: A comparison of immobilization and controlled passive motion techniques. J Hand Surg Am. 1980, 5: 537–43.

23.

Weiland

. Boutonnière and pulley rupture in elite baseball players. Hand Clin. 2012, 28: 447.

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