Closed rupture of flexor digitorum profundus in zone III
- 1 Orthpaedic Surgery, Tripler Army Medical Center, Honolulu, Hawaii, USA
- 2 F Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
- Correspondence to Dr Ryan James Bickley; ryan.j.bickley@gmail.com
Abstract
Closed ruptures of the flexor digitorum profundus (FDP) tendon cause a loss of active flexion at the distal interphalangeal joint. Commonly referred to as a ‘jersey finger’ because of its association with tackling sports, the distal aspect of FDP is avulsed from its insertion on the distal phalanx in zone I, with or without a fragment of bone. Because of this classic injury mechanism and pattern, providers may not seek advanced imaging beyond plain radiographs. Although rare, injury to FDP more proximally may occur. More often this injury is associated with a weak underlying tendon because of repetitive microtrauma or anomalous anatomy, for example. We present a case of a closed rupture of the FDP in zone III, and stress the importance of maintaining a high clinical suspicion and the potential use of adjunct ultrasound imaging to localise the site of injury.
Background
Closed ruptures of the flexor digitorum profundus (FDP) tendon are relatively common injuries that result in loss of active flexion at the distal interphalangeal joint (DIPJ). This injury is colloquially referred to as a ‘jersey finger’, as it is commonly occurs during tackling in sports. Classically, the distal aspect of FDP is avulsed from its insertion on the distal phalanx (in zone I, distal to the insertion of flexor digitorum superficialis), with or without a fragment of bone. The ubiquity of this injury in its classic pattern has led some authors to recommend that only plain radiography, without advanced imaging, should be required for presumed diagnosis of FDP rupture.1
However, injury to the FDP may occur more proximally. These uncommon injuries occur more often in men, and have been associated with underlying pathologies known to weaken the tendon, namely repetitive microtrauma, vascular disease, steroid or fluoroquinolone use, and rheumatoid arthritis.2–4 Due to the rarity of spontaneous closed FDP rupture proximal to zone I, this pathology may not be recognised until surgical exposure reveals the tendon to be intact at that level.5 6 We present a case of a closed rupture of the FDP in zone III, proximal to the A1 pulley.
Case presentation
A 64-year-old man presented with inability to flex his long finger DIPJ after feeling a painful pop in his hand when lifting heavy mechanical equipment. Though he denied prior injuries or prodromal pain, he endorsed many years of working as a manual labourer, with frequent heavy lifting using a crimp or slope grip. The patient denied history of rheumatoid arthritis, vascular disease or the use of corticosteroids or fluoroquinolone antibiotics.
Examination revealed intact skin over the hand, with tenderness along the long finger extending into the palm. The affected digit rested in extension with diminished tenodesis effect compared with the others. He could not actively flex at the DIPJ, though active flexion remained intact at the proximal interphalangeal (PIP) joint on sublimis test. Plain radiography of the right hand showed no osseous abnormalities.
Treatment
The patient was diagnosed with FDP tendon rupture, and elected to undergo surgical repair. A Brunner-style incision was made overlying the long finger FDP insertion, which was found to be intact. A sterile ultrasound probe was then used to track the tendon more proximally, where the FDP was found to have ruptured in zone III and its proximal portion had retracted to the proximal margin of the carpal tunnel. A second Brunner-style incision was made, extending into an incision overlying the carpal tunnel. The carpal tunnel was released and the proximal end of the FDP tendon was identified (figure 1). Careful attention was paid to protecting adjacent neurovascular structures, especially the superficial arterial arch and common digital nerves branching from the median nerve in the carpal tunnel. The tendon end was then shuttled underneath the superficial palmar arterial arch into zone III (figure 2). We then performed a repair with a six-stranded modified Becker technique (figure 3). The tendon was passively moved through a full arc of motion, and no impingement or triggering at the A1 pulley was observed.
Forceps hold the distal aspect of the tendon, and the retracted portion is visible within the wound proximally (thick arrow).
The retracted, proximal portion of the flexor digitorum profundus tendon was shuttled beneath the superficial palmar arch, back to the zone of injury.
Six-stranded modified Becker repair of flexor digitorum profundus.
Outcome and follow-up
Postoperatively, the patient was immobilised in a dorsal blocking splint with interphalangeal joints extended, the metacarpophalangeal joints at 70° of flexion and the wrist at 20° of flexion. A modified Duran rehabilitation protocol was used, beginning with passive digital flexion in the splint every 2 hours throughout the day beginning on postoperative day 3.7 Equal emphasis was placed on passive flexion and passive extension. Active range of motion (AROM) exercises within the splint were started 3.5 weeks postoperatively. After 4.5 weeks postoperatively, AROM exercises were allowed outside of the splint every hour or 2. The splint was discontinued 6 weeks postoperatively, and the patient continued with AROM exercises, progressing to strengthening exercises. The patient resumed work 10 weeks after surgery. At his most recent follow-up 8 months after surgery, the patient had 45° of active flexion at the DIPJ, 95° at the PIP joint, 80° at the metacarpophalangeal joint and he was able to make a composite fist. Grip strength was measured at 40 pounds. Subjectively, the patient did report stiffness, but was pleased with his outcome and did not have any limitations with his daily activities.
Discussion
Closed ruptures of FDP proximal to zone I are rare, often presenting in the setting of underlying pathology or associated repetitive gripping activities.3 4 8–12 Review of the English literature revealed 43 cases of closed spontaneous FDP ruptures outside of zone I (table 1). Lee et al described 13 cases of midsubstance ruptures in farmers with a known background of long-term manual labour that involved repetitive strain on the flexors of the hand.8 The most commonly affected digit is the small finger, followed by the ring and long fingers.9 This pattern is consistent with their contribution to power grip.
Spontaneous flexor digitorum ruptures outside zone I
| Authors | Injury location(s) | Number of cases | Population | Finger distribution | Risk factors |
| Lee et al 8 | Zone III Zone IV Zone V |
1 4 12 |
Elderly farmers | 1 MF, 4 RF, 12 SF | Repetitive hand movements |
| Melamed et al (2015)10 | Zone III | 1 | Labourer | 1 RF | Repetitive hand movements |
| Davis and Armstrong11 | Zone III | 2 | Retired elderly patients | 2 SF | Anomalous tendon bifurcation |
| Simman and Fietti6 | Zone II | 1 | Pedestrian | 1 SF | None reported |
| Naam9 | Zone II Zone III |
1 12 |
Labourers | 1 LF, 7 RF, 5 SF | Repetitive heavy lifting |
| Bois et al 3 | Zone III | 5 | Labourers | 1 LF, 4 SF | Anomalous tendon anatomy |
| Schweizer and Bayer12 | Zone II | 3 | Athletes | 1 IF, 2 MF | Crimp gripping |
| Li et al 4 | Zone III | 1 | Writer | Bilateral SF | Repetitive hand movements |
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IF, index finger; LF, long finger; MF, middle finger; RF, ring finger; SF, small finger.
When insufficiency of the FDP is encountered in the setting of a closed injury, one may assume that the tendon is injured in zone I. However, preoperative recognition of a more proximal rupture may prevent unnecessary surgical exploration outside of the true zone of injury. While some authors report that advanced imaging is not required following the clinical diagnosis of FDP rupture, we submit that tenderness proximal to the typical zone of injury is an indication to obtain more information prior to surgical treatment.13
Khaleghian et al originally demonstrated the usefulness of ultrasound in the hand and wrist.14 Though operator dependent, bedside ultrasound can be accomplished by the surgeon in the clinic or operating room, and carries little additional cost or risk.15
Several rehabilitation protocols have been proposed for flexor tendon repairs, including early passive and early AROM.7 16 17 A systematic review by Starr et al examined rehabilitation protocols in a total of 3010 flexor tendon repairs, and found that early passive protocols had fewer tendon ruptures, but increased risk of reduced postoperative range of motion. Additionally, a statistically significant trend was observed that overall rupture rates have decreased over time, regardless of rehabilitation protocol. Choosing a rehabilitation protocol requires intraoperative judgement of the integrity of the repair.18
Patient’s perspective
When my injury happened I was working with yard tools as I normally do in my job as a landscaper and I was lifting a heavy gasket handle when I felt a ‘pop’ in my hand. It hurt a lot, and afterwards I could not make a fist because my middle finger would not bend. It took me a few days to get into see the orthopedic surgeon because I do not live on the island of Oahu where the hospital is. I always felt like something was wrong in my palm and not the fingertip because that is where the pain was the worst. I was happy with the surgery and the therapy afterwards, but sometimes I had difficulty with therapy because the therapists on Maui were not as familiar with the rehab as the ones on Oahu. Still, I am very happy with my outcome and I have been able to return to my work and all the normal things I like to do.
Learning points
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Spontaneous ruptures of the flexor digitorum profundus proximal to zone 1 are uncommon.
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The importance of maintaining high clinical suspicion is stressed, given the risk of misdiagnosis and associated additional morbidity.
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Ultrasound is a useful tool for localising injury, especially in order to prevent misidentification of injury location.
Footnotes
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Contributors RJB cared for this patient as the junior resident on call, participated in his initial surgery and aftercare, and primarily wrote this manuscript. JBD cared for this patient as the senior resident on call, participated in his initial surgery and aftercare, and heavily edited this manuscript. RLF assisted in the care for this patient, as well as helped primarily write the manuscript. WED cared for this patient as the staff surgeon on call, participated in his initial surgery and aftercare, and heavily edited this manuscript.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Disclaimer The views expressed in this manuscript are those of the authors, and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the US Government.
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Competing interests None declared.
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Patient consent for publication Obtained.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.
References
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