Finger Tips – tendons and ligaments

Cite this article as:
Sinead Fox + Kate Jackson. Finger Tips – tendons and ligaments, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.25422

Little fingers get everywhere, and injuries are common. The mechanism of injury tends to be age-dependent with the under-fives magnetically drawn to door hinges and the over-fives more likely to do some damage during higher impact sport. Below are a few common injuries of the tendons and collateral ligaments of the fingers that you might come across in PED.

  • Ensure adequate analgesia prior to assessment, occasionally the administration of a local anaesthetic is required… don’t forget bubbles too!
  • As tendon/ligament injuries may not occur in isolation, an assessment must include inspection, palpation, (look, feel, move!), assessment of vascular structures, and testing of motor and sensory functions.
  • Children typically tend to display hand dominance between the ages of 2-4 years old; if the child is old enough make sure to record hand dominance in the medical or nursing notes.
  • In older children/adolescents document details of sport participation/ hobbies/professional goals as these may be taken into account by hand surgeons when considering treatment options.

Part 1: Flexor tendon injuries

Anatomy

There are two flexor tendons for each finger and one for the thumb.

The flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) are the flexor tendons of the fingers, and the flexor pollicis longus (FPL) is the only thumb flexor.

The flexor tendons travel distally from the forearm through the carpal tunnel and are named based on the forearm muscles from which they arise.

The flexor digitorum profundus (think profound i.e. deep) arise from the deeper layer of the flexor muscles. The flexor pollicis longus tendon of the thumb also arises from the deeper muscle layer. The flexor digitorum superficialis (think superficial) is the continuation of the more superficial layer.

  • FDP inserts at the base of the distal phalanx and flexes the DIP joint (tip: FDP is at the point of the finger).
  • The FDS tendon divides into two slips that wrap around the FDP to insert into the sides of the middle phalanx. FDS flexes the PIP joint.

The Pulley System

The flexor tendons are enclosed in a synovial sheath that lubricates them and minimizes friction.

It is organized into segments of transverse fibres forming annular pulleys (annular means ring-like; think of the ring-like lesions of annular eczema) and oblique fibres comprising cruciate pulleys (cruciate means crossed, like the cruciate ligaments of the knees).

There are three cruciate pulleys (C1-3) and five annular pulleys (A1-5) pulleys. These pulleys keep the flexor tendons close to the bone and prevent bowstringing of the tendon.

The pulley system

Evaluation

Closed flexor tendon injuries are usually caused by forced extension of the finger in active flexion. The child may present with reduced flexion of the finger or pain when bending the finger and there may be localized swelling or open wounds.

The FDS and FDP tendons should be tested individually; it is not enough just to observe the child make a fist as tendon injuries can be easily overlooked or missed.

  • To check FDS function, hold all adjacent fingers in extension and then release the finger you want to assess. Ask the child to flex the free digit at the PIP joint.
  • To examine the FDP, hold the middle phalanx in extension and ask the child to flex the DIP joint.
Testing FDP
Testing FDS

Examination Pearls

Tendon function can be difficult to assess in a very young or uncooperative child. In these circumstances observation of digital cascade and wrist tenodesis can be useful physical examination tools to assess tendon integrity of hand and fingers.

  1. Digital Cascade

When the child’s hand is in a resting position, the fingers should have a natural cascade of progressively increasing flexion from the index finger through to the little finger.

The digital cascade
  1. Wrist Tenodesis

Squeezing the forearm muscles while observing the fingers can also be used to assess flexor tendon continuity. If flexor tendons are intact, the child’s fingers should flex when the forearm muscles are squeezed.

Wrist tenodesis

A: Extending the wrist flexes the fingers. With intact flexor tendons and a relaxed or distracted patient, passive wrist extension results in finger flexion. If flexor tendons are damaged then the injured finger(s) will rest in an extended position when the wrist is extended.

B: Flexing the wrist extends the fingers. Similarly, with intact extensor tendons, passive wrist flexion results in finger extension. If the extensor tendons are damaged, the injured finger(s) will rest in a flexed position when the wrist is flexed.

Wound Exploration

It is important to remember that tendons move; looking into a wound and seeing an intact tendon does not exclude a tendon injury. If the wound is sustained while the finger is flexed and the finger is examined while it is extended, the level of the tendon injury will not correspond to the level of the skin laceration. Therefore it is important to ask the parent or older child/adolescent about finger position at the time of the injury and put the injured digit through a passive range of movement while examining the wound.  If you are in doubt or cannot rule out a tendon injury refer the patient to the local hand surgery team.

Classification

The sites of the flexor tendon injuries are divided into five zones.

*The term ‘No Man’s Land’ was coined by hand surgeon Mr. Sterling Bunnell in 1918 because at that time it was felt no man (or woman) should attempt repair within this zone due to the complexities of the anatomy and risk of adverse outcomes. While this belief is no longer a common practice, it highlights the intricacies of surgical repair within this zone.

Jersey finger (Zone 1 injury)

Juno is a fifteen-year-old girl who is attending ED with an injury to her left ring finger. She was playing rugby earlier today and her hand got caught in another player’s jersey during a tackle. On examination, you note swelling, bruising, and tenderness to the volar base (on the palmar side) of her distal phalanx on her left ring finger. When you lie her left hand flat on a table with the palm facing upwards and hold the middle phalanx of her ring finger in extension she is unable to flex her distal phalanx at the DIP joint. She also can’t bend the DIP joint when trying to make a fist. You correctly identify that she has an injury to her FDP tendon and make the diagnosis of Jersey Finger. You send Juno to X-ray to assess for a fracture.

Mechanism

Disruption of the FDP tendon is known as Jersey finger. This injury is caused by the forced extension of the DIP joint during active flexion. It commonly occurs when an athlete’s finger catches in another player’s jersey, usually while playing a tackling sport such as rugby or American football. For those that prefer more solo pursuits, it can also be caused by an overly tight crimp grip in climbers.

 

Presentation

A patient with Jersey finger may present with pain and swelling to the volar (the palmar) aspect of the DIP joint and the finger will be extended at rest. The ring finger is commonly affected. The integrity of the FDP should be evaluated as outlined above. An injured FDP will produce very restricted or no movement. An x-ray should be performed to rule out an avulsion fracture at the volar base of the distal phalanx.

X-ray demonstrating an avulsion fracture at the base of the distal phalanx of the little finger in Jersey Finger. Case courtesy of Dr Ian Bickle, Radiopaedia.org. From the case rID: 26251
Jersey finger – disruption of insertion of FDP

Treatment

Early referral to a hand surgeon for assessment and appropriate treatment is paramount.

Operative: The majority of these cases require surgical intervention to reattach the tendon to prevent tendon retraction and optimize function. The prognosis for patients with jersey finger worsens if treatment is delayed and severe tendon retraction is present.

Non- Operative: A partial tear may be managed conservatively (splinting, NSAIDS, physiotherapy). However, from a PED perspective, these injuries should be considered surgical cases until deemed otherwise by a hand specialist.

You do not identify a fracture on Juno’s X-ray and you refer her to the Plastic Surgery team for prompt review as it is possible she may require surgery to repair her FDP tendon.

…A quick overview of Trigger thumb

Trigger thumb, although uncommon, maybe a reason for presentation to the PED, typically when a child is 2 years old. Paediatric Trigger thumb results from a mismatch in the size of the Flexor Pollicis Longus (FPL) and the first annular pulley (A1) disrupting normal tendon gliding. Children find it difficult to extend the IP joint of the thumb, with clicking or snapping felt or heard. Some patients even have a fixed flexion deformity at the IP joint. Characteristically, a palpable mass is felt at the level of the MCP joint crease on the volar (palmar) surface of the thumb representing a nodule in the FPL as well as thickening of the flexor tendon sheath. This is commonly referred to as ‘Notta’s Node’.

Its aetiology is poorly understood. Historically, trigger thumb was thought to be congenital, however, this is controversial and an argument exists that trigger thumb is an acquired condition. Diagnosis is usually based on clinical exam. X-rays or alternate imaging is rarely indicated, although parents will occasionally try attribute symptoms to a recent history of trauma. This is usually a red herring!

Paediatric trigger thumb can be managed surgically or conservatively with splinting and a physiotherapy regime – sometimes it can spontaneously resolve, although the spontaneous resolution of paediatric trigger thumb can be less likely after 2 years old. Surgical release of the first annular pulley may be offered as a treatment option to restore thumb IP joint movement if there is a fixed flexion deformity beyond the age of 12 months or if conservative management fails.

 

Part 2: Extensor Tendon Injuries

Anatomy

Distal to the MCP joint, the common extensor tendon divides into three slips: one central and two lateral bands. The central slip inserts at the base of the middle phalanx and the two lateral bands extend along the radial and ulnar margins of the middle phalanx to converge at the distal third of the middle phalanx to form the terminal extensor tendon, which inserts at the base of the distal phalanx. The central slip extends the middle phalanx at the PIP joint level and the terminal extensor tendon extends the DIP joint. The Extensor Pollicis Longus (EPL) extends the thumb at the IP joint.

Extensor tendon anatomy

Evaluation

The extensor tendons are assessed by applying pressure to the dorsum (back) of the finger while the patient is attempting active extension.

Testing extensor tendons

To test the Extensor Pollicis Longus (EPL), ask the patient to place their hand flat on a table and lift up their thumb against resistance.

Testing EPL

Classification

The extensor mechanism can be divided into 9 anatomical zones. Odd-numbered zones are located over joints, and even-numbered zones are located over bones. Tendon injuries can be categorized according to these anatomical zones.

Extensor tendon zones

A little nugget: an easy way to recall the extensor zones is to remember the odd numbers (I, III, and V) are at the joints (DIPJ, PIPJ, and MCPJ).

Injuries in zone 1 (the DIP joint) and zone III (the PIP joint) cause some unique injury patterns which we’ll explore below.

The thumb has a unique classification system as it has one fewer phalanx.

Mallet Finger: zone I injury (Baseball Finger)

Isabelle is an 8-year-old girl who was playing with her twin sister, Sophie, in their bedroom while their Mummy and Daddy were busy working from home in another room. Sophie accidentally closed the bedroom door catching Isabelle’s finger in the hinge side of the door. In ED you see that Isabelle’s right, dominant index finger is bruised and swollen at the DIP joint and there is a superficial abrasion to the dorsum of the DIP joint. Isabelle’s point of maximal tenderness is to the DIP joint. You try your best to assess finger function but Isabelle is crying and says she is too sore to move her fingers. But you note that the index finger appears flexed at the DIP joint and you suspect a Mallet injury. You give Isabelle analgesia and refer her for an x-ray.

Mechanism

Mallet finger is a partial or complete avulsion of the terminal extensor tendon from its insertion on the distal phalanx, commonly resulting from sudden flexion of an extended DIP joint. It can also occur secondary to a crushing mechanism.

Presentation

Mallet finger can be an open or closed injury with or without a fracture. Patients present with a flexion deformity at the distal phalanx and an inability to extend finger at DIP joint. The DIP joint can be swollen and ecchymosed.

Mallet finger

In children, this injury typically occurs due to an avulsion fracture of the distal phalangeal epiphysis, the insertion point of the terminal extensor tendon.

Case courtesy of Dr Hani Salam, Radiopaedia.org. From the case rID: 12227

Classification

Mallet fingers can be described using a classification scheme (I through IV) developed by Doyle (1993).

Classification of Mallet finger

Treatment

Early referral to a hand surgeon for assessment and advice regarding appropriate treatment is essential.

Non-operative: Closed acute injuries with or without fractures can be managed with 6-8 weeks of extension splinting at DIP joint, followed by gentle active flexion ROM.

A 2004 Cochrane review found insufficient evidence to support the use of any particular splint when treating mallet injuries; all achieve similar outcomes. However, patient compliance is vital to a successful outcome.

Operative:

Open injuries are treated by surgical repair.

Closed injuries may be considered for surgical management if there is joint subluxation or an avulsion fracture of more than 30-50% of the articular surface.

Complications: Swan-neck deformity

Correct management of an acute mallet injury is critical as a poorly managed or untreated chronic terminal extensor tendon injury can lead to swan-neck deformity.

Swan-neck deformity is caused by prolonged DIP flexion with dorsal subluxation of lateral bands and PIP joint hyperextension.

It takes a while before Isabelle and her Mum return to the ED from X-ray. Fortunately, the analgesia seems to have had some effect and Isabelle is more relaxed. You review the X-ray and do not identify a fracture. On examination, you confirm there is a flexion deformity at the DIP joint and note that Isabelle is unable to actively extend at the DIP joint. Suspecting a mallet injury, you apply an extension splint and refer Isabelle to plastics. They opt to treat the injury conservatively with an extension splint at the DIP joint for 6 weeks. They give Mum and Isabelle careful advice about compliance with splinting and give her an appointment for follow up in out-patients.

Central Slip Injuries: zone III injury

Michael is a 15-year-old talented basketball player. He was playing in a school league basketball final three days ago, when he felt a sudden sharp pain in his left middle finger after a failed attempt at catching the ball. He played until the end of the game but attended a minor injuries unit the following day as his finger was swollen and painful at the PIP joint. After a normal X-ray, he was diagnosed as having a soft tissue injury and discharged home with his fingers buddy-strapped. However, his pain has not improved and he’s still unable to fully extend his finger at the PIP joint, so his dad brings him to your ED. He has a digital copy of the X-Ray for you to review.

Mechanism

Central slip injuries are extensor tendon injuries at the middle phalanx most often resulting from forced flexion of an extended PIP joint, a mechanism commonly seen in basketball players. Other injuries that can accompany central slip disruption include volar (palmar) dislocations of the PIP joint, dorsal avulsion fractures of the base of the middle phalanx, and lacerations to the dorsal surface of PIP joint.

Presentation

The PIP joint may be swollen and bruised. The area of maximal tenderness is generally over the dorsal aspect of the PIP joint.

Closed central slip injuries can be easily missed or misdiagnosed as a sprain or soft tissue injury as there is no wound and sometimes no abnormality seen on X-ray.

The physical examination can be challenging- some patients have no loss of active extension at the PIP joint as extension is still provided by the lateral bands of the extensor tendon despite the disruption of the central slip. Even when there is a loss of extension, this can be overlooked or attributed to pain. (Don’t forget to provide adequate analgesia prior to assessment!)

These pitfalls can be avoided by maintaining a high index of suspicion for a central slip injury and undertaking a careful examination including Elson’s test to establish the integrity of the central slip, especially in the patient who presents with a painful, swollen PIP joint without gross deformity. Occasionally, ring blocks are required to allow a proper assessment of ROM.

Elson’s Test

  • Ask the patient to bend the affected PIP joint 90° over the edge of a table and ask them to extend the middle phalanx against resistance.
  • If the central slip is intact (negative test), extension is strong and the DIP remains floppy because the extension force is now placed entirely on maintaining extension of the PIP and the lateral bands cannot act distally in this position.
  • When a rupture of the central slip is present (positive test) there will be weak PIP extension, and the DIP will extend abnormally and become rigid.

There is also a modified version of Elson’s test that can be used. Here’s how the Modified Elson’s Test is done:

  • Ask the patient to place their injured and uninjured contralateral fingers knuckle to knuckle in 90 degree PIP flexion, with the middle phalanges pressed against each other. The patient is then asked to extend both DIP joints.
  • Negative test (normal)- DIP joints symmetrically flexed.
  • A positive test (central slip injury)- Injured DIP joint extends more (See diagram below).
The modified Elson’s test. The top image of uninjured fingers shows a symmetric inability to straighten the DIP joint when the middle IP joints are flush against each other. In a central slip injury (the second image), the DIP joint is pathologically straightened, which is seen in the left hand in this example.

This video from Brian Lin demonstrates both tests beautifully.

These tests can be limited by pain and the patient’s ability to co-operate, if a closed central slip injury is suspected then the PIP joint should be splinted in an extension and follow up in a hand clinic arranged.

Treatment

Early referral to a hand surgeon for assessment and advice regarding appropriate treatment is essential.

Non Operative:

  • Closed injuries
  • Extension splinting of the PIP joint for up to 6 weeks to allow central slip restoration

Operative: Surgical treatment reserved for

  • Open injuries
  • Displaced avulsion fractures of the middle phalanx
  • PIP instability
  • Failed non-surgical treatment

Complications: Boutonnière deformity

Failure to recognize and treat a central slip injury in the ED may result in a problematic Boutonnière deformity later on.

Boutonnière deformity is characterized by flexion of the PIP joint and hyperextension of the DIP joint. It develops secondary to loss of extension force on the PIP joint, with volar subluxation of the lateral bands and subsequent DIP joint hyperextension.

Extensor mechanism over the finger. A) Intact central slip and lateral band mechanism. B) Disrupted central slip leading to a Boutonnière’s deformity.

On examination, you note swelling and bruising to the PIP joint. Michael tells you that he is maximally tender on palpation to the dorsal surface of his PIP joint. He is able to partially extend his finger at the PIP joint but using Elson’s test you note weak PIP extension, and an abnormally extended and rigid DIP joint. You diagnose a central slip injury and explain the diagnosis to Michael and his dad before referring Michael to the plastic surgery team for assessment. Plastics treat Michael in an extension splint for 6 weeks to allow central slip restoration.

Part 3: Collateral Ligament Injuries

Anatomy

The collateral ligaments stabilize the phalanges laterally at the DIP, PIP and MCP joints.

Mechanism

Forced ulnar or radial deviation of any of the IP joints can cause partial or complete collateral ligament tears.

Presentation

Collateral ligament injuries of the fingers present as tenderness on palpation overlying affected ligament, swelling and sometimes bruising.

Evaluation

The integrity of a collateral ligament is assessed by applying valgus and varus stress to the involved joint with the joint in full extension and with the joint in 30 degrees of flexion. Compare the laxity of the injured finger with an unaffected finger. Increased laxity or lack of an endpoint signify an injury.

An x-ray should be performed to out-rule an avulsion fracture at the insertion site of the ligament.

Treatment

If the joint is stable and no large fracture fragments are identified, the injury can be treated with buddy strapping.

Treatment Pearl: Buddy strapping

If the ring finger is involved, it should be secured to the little finger as the little finger is naturally extended and easily injured if exposed.

Ulnar Collateral Ligament Injury of the Thumb (Skier’s Thumb / Gamekeeper’s Thumb)

Tess was very excited as she stepped out onto the fresh crunchy snow all kitted up and raring to go. However, she didn’t count on it being so slippery and fell more or less right away whilst holding her ski poles. She had a lot of pain in her thumb and it looked a bit swollen.

It sounds like Tess has Skier’s Thumb, which is an injury to the ulnar collateral ligament of the MCP joint of the thumb.

Ulnar collateral injury

Mechanism

This injury is usually caused by forced abduction or extension at the MCP joint, typically falling onto an outstretched hand with something in the palm, falling onto an abducted thumb or as a result of a ball or object striking the ulnar aspect of the thumb during sports. This force stretches or tears the ulna collateral ligament, resulting in complete or partial rupture of the and can be associated with an avulsion fracture.

Presentation

Pain, swelling, and bruising are usually noted over the ulnar aspect (the index finger side) of the MCP joint of the thumb. The patient will also be tender on palpation to this area. Occasionally, a mass or a lump can be felt at the site of tenderness, which may suggest a Stener Lesion*. In severe ulnar collateral ligament injuries, the proximal phalanx may become subluxed with radial deviation on the metacarpal head.

*Stener Lesion

  • Normally, the ulnar collateral ligament lies deep to the adductor pollicis tendon.
  • A Sterner Lesion can form when a torn UCL becomes displaced superficially to adductor pollicis longus.
  • The presence of a Stener Lesion is an indication for surgical repair of this injury.

Evaluation

Evaluation of an ulnar collateral ligament injury involves valgus stress (radial deviation) testing of the joint at neutral and 30 degrees of flexion at MCP joint of the thumb. Compare the patient’s injured with their uninjured thumb to find out what is normal for that child. Hold the base of the thumb then apply sideways (lateral) pressure to the tip of the thumb. Increased laxity or lack of an endpoint signify an injury. It may be kindest to put in a ring block to prevent guarding due to pain, to increase the accuracy of the exam.

Functionally it’s important to test the (in)ability to grasp between thumb and finger. A stable pinch mechanism depends on the integrity of the radial collateral ligament of the index finger and the UCL of the thumb.

An X-ray should be performed to out-rule an avulsion fracture.  If an avulsion fracture is present, this will be seen at the ulnar corner of the base of the proximal phalanx. Ultrasound or MRI may be used to identify a tear to the UCL or diagnose the presence of a Stener Lesion.

Avulsion fracture to ulnar corner of proximal phalanx of thumb. Courtesy of Orthobullets.com

Treatment

Non- operative: A partial UCL rupture may be treated conservatively. Conservative management involves immobilization of the MCP joint in a thumb spica cast or thermoplastic thumb splint.

Operative: Complete UCL rupture or the presence of Stener Lesion are indications for surgical repair. Early immobilization with a thumb spica will also prevent further damage and make it more comfortable for the child while awaiting surgical review.

Tess’ thumb is very bruised and extremely tender. You pop in a ring block and with valgus stress you can tell there is increased laxity compared to the other side. There’s no fracture on x-ray. You refer Tess to your colleagues in plastics, who, after an ultrasound, diagnose a partial rupture of her ulnar collateral ligament. Her thumb’s immobilised in a thumb spica. 6 months later she’s back on the slopes!

Selected References

Allan, C. H. (2005). Flexor tendons: anatomy and surgical approaches. Hand clinics21(2), 151-157.

Armstrong, M. B., & Adeogun, O. (2009). Tendon injuries in the pediatric hand. Journal of Craniofacial Surgery20(4), 1005-1010.

Avery, D. M., Inkellis, E. R., & Carlson, M. G. (2017). Thumb collateral ligament injuries in the athlete. Current reviews in musculoskeletal medicine10(1), 28-37.

Dorani, B. (2020). Soft Tissue Injuries of the Hand. Retrieved from https://www.rcemlearning.co.uk/reference/soft-tissue-injuries-of-the-hand/#1583314733632-1b04992c-edab

Elson, R. A. (1986). Rupture of the central slip of the extensor hood of the finger. A test for early diagnosis. The Journal of bone and joint surgery. British volume68(2), 229-231.

Forward, K. E., Yazdani, A., & Lim, R. (2017). Mallet Finger in a Toddler: A Rare But Easily Missed Injury. Pediatric emergency care33(10), e103-e104.

Guly, H.R. (1991). Missed tendon injuries. Archives of Emergency Medicine, (8), 87-91.

Handoll, H. H., & Vaghela, M. V. (2004). Interventions for treating mallet finger injuries. Cochrane Database of Systematic Reviews, (3).

Hatch, D. (2019). Extensor Tendon Injuries. Retrieved from https://www.orthobullets.com/hand/6028/extensor-tendon-injuries

Kalainov, D. M., Hoepfner, P. E., Hartigan, B. J., Carroll IV, C., & Genuario, J. (2005). Nonsurgical treatment of closed mallet finger fractures. The Journal of hand surgery30(3), 580-586.

Leggit, J., & Meko, C. J. (2006). Acute finger injuries: part I. Tendons and ligaments. American family physician73(5), 810-816.

Lo, I. & Richards, R.S. (1995). Combined Central Slip and Volar Plate Injuries at the PIP Joint. Journal of Hand Surgery, 20B (3), 390-391.

Matzon, J. L., & Bozentka, D. J. (2010). Extensor tendon injuries. The Journal of hand surgery35(5), 854-861.

Nugent, N., & O’Shaughnessy, M. (2011). Closed central slip injuries–a missed diagnosis?, Irish Medical Journal, 104 (8):248-250.

Perron, A. D., Brady, W. J., Keats, T. E., & Hersh, R. E. (2001). Orthopedic pitfalls in the emergency department: closed tendon injuries of the hand. The American journal of emergency medicine19(1), 76-80.

Ritting, A. W., Baldwin, P. C., & Rodner, C. M. (2010). Ulnar collateral ligament injury of the thumb metacarpophalangeal joint. Clinical Journal of Sport Medicine20(2), 106-112.

Shah, A. S., & Bae, D. S. (2012). Management of pediatric trigger thumb and trigger finger. JAAOS-Journal of the American Academy of Orthopaedic Surgeons20(4), 206-213.

Sheth, U. (2019). Mallet Finger. Retrieved from https://www.orthobullets.com/hand/6014/mallet-finger

Sullivan, M. A., Cogan, C. J., & Adkinson, J. M. (2016). Pediatric hand injuries. Plastic Surgical Nursing36(3), 114-120.

Thurston, M. and Dawes, L. et. al. Gamekeeper Thumb. Retrieved from https://radiopaedia.org/articles/gamekeeper-thumb

Wahba, G., & Cheung, K. (2018). Pediatric hand injuries: Practical approach for primary care physicians. Canadian Family Physician64(11), 803-810.

Yoon, A. P., & Chung, K. C. (2019). Management of acute extensor tendon injuries. Clinics in plastic surgery46(3), 383-391.

Finger injuries: basics and bones

Cite this article as:
Sinead Fox. Finger injuries: basics and bones, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.27577

Introduction

Injuries to the hand are frequent in the paediatric population and are a common reason for presentation to the PED. Despite the frequency of these presentations, assessment and management of hand and finger injuries can be challenging. But never fear! DFTB have come to the rescue with a comprehensive two-part series related to the assessment and management of paediatric hand and finger injuries including some handy tips.

This first post will cover an overview of the basic anatomy of the hand, professional lingo as well as history taking and the clinical examination. Documentation essentials and common phalangeal and metacarpal fractures seen in PED will also be covered.  

First, let’s take a look at the basic anatomy of the bones of the hand.

Professional Lingo: Get to know your pinkie from your pointer!

Although it is helpful to know your pinkie from your pointer when talking to children, it is also important to have knowledge of the professional language used to document and describe hand injuries appropriately. This is not only important from a medico-legal point of view but having the ability to describe the exact location of clinical findings in professional terms makes communication and referral to specialist services much easier.

Clinical History/Documentation Essentials: Take a HAND history

H-          How the injury happened? Ask about mechanism of injury including the environment in which the injury was obtained.

              Hobbies. Ask about the child’s hobbies, sports, activities, career aspirations (in older child) as these may impact on management.

A-          Altered sensations. Ask about any altered sensations such as paraesthesia which could indicate a nerve injury.

N-          Needles/Needs Tetanus? Ask about vaccinations, is the child’s Tetanus vaccination up to date, especially relevant if open wounds or animal/human bites are present.

NAI        Like all paediatric injuries consider the possibility of NAI, especially in the younger child. A comprehensive history is essential to detect the possibility of intentional injury from physical abuse or an unintentional injury as a result of neglect. Consider injuries that are self-inflicted in the older child/adolescent age group.

D-          Dominance. Ask and record the child’s hand dominance as this can impact injury management.

Physical exam – look, feel, move

Clinical assessment of hand injuries involves a systematic exam of both hands including inspection, palpation, and range of motion (ROM).

1. Look

  • Once the child has received appropriate analgesia and you have established a rapport with the child and their parent, begin by looking at the hand without touching, observe the child’s hand at rest and play, involve a play specialist if available- they always bring the right amount of magic to get even the sorest of little hands and fingers moving!
  • Look for bruising, swelling, abrasions or open wounds. Assess for nail bed injuries.
  • Check for any clinical deformities including a rotational deformity which may not become apparent until the child makes a fist. Minimally displaced fractures may be clinically significant if they result in a rotational deformity, so it is vital to routinely assess for same. It is good practice to include the presence or absence of a rotational deformity in your documentation.
Rotational deformity – the normal cascade should point to the thenar eminence

2. Feel

  • Examine the child’s unaffected hand first and keep the child chatting throughout the exam, it helps reduce the child’s anxiety and allows the child to build trust in you.
  • Remember to examine the whole hand. It is important to develop a systematic approach to the examination of the hand including palpation of the wrist, carpal bones (including anatomical snuff box and scaphoid tubercle) metacarpals, metacarpophalangeal joints (MCPJs), phalanges, proximal interphalangeal joints (PIPJs) and distal interphalangeal joints (DIPJs).  Systematic palpation of the entire hand can help localise underlying fractures and concomitant injuries.
  • Evaluate and document neurovascular status.

Examination Pearl: The Wrinkle Test

Neurological assessment in young children or children/adolescents with difficulties communicating can be particularly challenging as they may be unable to report the presence or absence of sensation. The wrinkle test measures autonomic function of peripheral nerves via placement of the child’s hand in warm water for 10 minutes, wrinkles on the fingers indicate intact neurological function.

3. Move

  • Getting a child to move an injured hand can be challenging but certain familiar gestures such as high fives, thumbs up or fist bumps can be used to assess active range of movement in a young or uncooperative child.
  • A game of paper, rock, scissors is a fun and systematic way to test peripheral nerves in children with upper limb injuries. 
  • Be vigilant for tendon injuries. Check out the DFTB finger tendon and ligament injuries post for further details and clinical pearls related to the assessment of specific tendon functions. These functional tests should be included in every clinical examination of an injured hand.

Phalangeal Fractures

Approximately 20% of hand injuries in children are fractures. In particular, the phalanges are the most frequently injured bones of the hand with distal phalangeal and proximal phalangeal base fractures being the most commonly diagnosed fractures.

Proximal phalangeal base fractures

It’s a sunny June afternoon and Patrick a 9-year-old boy is brought to your ED by his Dad. Patrick reports it is the last day of school term before the summer holidays, he tells you he was so excited that when the final bell rang he threw his book bag in the air but, as the bag landed his left little finger got caught in the strap. It sounds like his finger was forcefully abducted by the weight of the bag. He shows you his swollen, bruised, and painful pinkie.  

Mechanism

Typically, proximal phalangeal base fractures result from a finger being abducted beyond acceptable limits of the MCP joints.

Presentation

A child with a proximal base phalangeal fracture will typically present with swelling, ecchymosis, and focal tenderness on palpation to base of proximal phalanx. A displaced fracture to the base of the proximal phalanx can cause malrotation of the finger. A significantly displaced fracture or a fracture that causes a rotational deformity requires closed reduction to correct the deformity.

Imaging

Oblique, PA, and lateral X-rays of the injured fingers should be obtained. True lateral X-ray is the most effective way to examine joint congruity. Angulation of proximal phalanx fractures is best seen on the lateral projection.

Salter-Harris Classification

Fractures involving the physis are described by the Salter-Harris Classification system as types I-V.  Salter- Harris type II fractures of the proximal phalanx are a common type of finger fracture in children.

  • Salter-Harris type I fractures involve only the physis and can be difficult to diagnose because X-Rays typically appear normal unless there is displacement.
  • Salter-Harris type II fractures involve extension through the physis and metaphysis.
  • Salter-Harris type III fractures extend through the physis and epiphysis.
  • Salter-Harris type IV fractures extend through the physis, metaphysis and epiphysis.
  • Salter-Harris type V fractures involve crush injuries that shatter the physis. 

Treatment

Non- Operative: Un-displaced or minimally displaced Salter-Harris type I or II fractures of the proximal phalanx without clinical deformity are usually managed with buddy taping to an adjacent finger for support and encouragement of early range of motion, typically for 3-4 weeks.

For displaced Salter Harris type II fractures of the proximal phalanx closed reduction can be carried out in ED. Depending on the age and preference of the child, closed reduction can be performed using a ring block +/- procedural sedation. The proximity of the physis assures a high degree of remodelling. The ED practitioner’s thumb or a cylindrical object such as a pen or pencil can be used to achieve adequate reduction. Post reduction stability is maintained by buddy tapping +/- splinting.

Operative: Severely displaced, unstable or open fractures require evaluation by a hand surgeon.

X-ray shows a displaced Salter-Harris type II fracture to the base of Patrick’s proximal phalanx. There is a rotational deformity on clinical exam. You reduce the fracture in ED using a ring block and Nitrous Oxide. On reassessment post reduction the clinical deformity is corrected and check X-rays are satisfactory. You discharge Patrick home with his finger buddy taped and arrange follow up in an outpatient clinic.  

Phalangeal shaft, neck and condylar fractures

Phalangeal shaft fractures

Treatment for fractures along the shaft of the phalanges is dictated by the orientation of the fracture as well as the degree of angulation on initial presentation. Clinical exam is also extremely important as even innocuous appearing fractures along the phalangeal shaft can be clinically significant if they cause a rotational deformity of the injured digit. A rotational deformity must be corrected as failure to do so can lead to long term functional impairments for the child.

Non operative: For length stable fractures with minimal displacement, buddy taping to an adjacent finger for support and to allow early range of motion can be an effective treatment for approximately 3-4 weeks.

Operative: Oblique or spiral fractures requiring closed reduction need more rigid immobilisation such as an ulnar or radial guttar splint or cast. Alignment of these fractures can be difficult to maintain and fixation is often required; surgical opinion is advised.

Surgery is also indicated in cases of open or severely displaced fractures or where there is instability post-reduction.

X-ray of long oblique proximal phalanx shaft fracture Courtesy of Orthobullets: https://www.orthobullets.com/hand/6114/phalanx-fractures

Phalangeal neck fractures

Neck fractures of the proximal and middle phalanges are classic paediatric injuries, rarely seen in adults. They typically result from a crush injury to the finger such as a child getting the finger caught in a closing door.

Non operative: Non-displaced fractures to the neck of the proximal or middle phalanges can usually be managed safely by immobilizing the digit for 3-4 weeks.

Operative: Surgical consultation is recommended for any displaced neck fractures as these are inherently unstable and require close follow up.

Condylar fractures

The condyles are a pair of tuberosities that form the distal articular surfaces of the proximal and middle phalanges. Condylar fractures are intra-articular fractures and can be unstable, therefore surgical consultation is recommended as these fractures require meticulous reduction to ensure proper joint congruity.

Volar plate avulsion injuries

Tori is a 14-year-old girl and a talented soccer goalie. She reports that while trying to save a penalty, her right middle finger was forcefully hyperextended and is now very painful. She shows you her right middle finger which is swollen and bruised at the PIPJ.

An overview of volar plate injuries

The volar plate lies between the flexor tendons and the palmar PIPJ capsule. It originates from the proximal phalanx and inserts into the middle phalanx. The volar plate contributes to the stability of the PIPJ by preventing hyperextension of the PIPJ.  Volar plate injuries encompass a spectrum of soft tissue injuries and can occur with an avulsion fracture at the volar base of the middle phalanx.  Subluxation or dislocation of the PIPJ may also occur.

Mechanism

Volar plate injuries are commonly caused by forced, sudden hyperextension injuries of the PIPJ, seen typically in older children/adolescents involved in hand/contact sports. Occasionally volar plate injuries can be caused by a crush injury to the digit.

Presentation

Diagnosis of a volar plate injury is based on history and clinical examination. Typically, there is swelling of the PIPJ. Bruising to the volar surface of the PIPJ is sometimes observed. Maximal tenderness on palpation is over the volar PIPJ and the patients may report pain on passive hyperextension of the PIPJ. The collateral ligaments should be tested as with collateral ligament injuries to check stability of the PIPJ.

 X-rays may reveal an avulsion fracture at the base of the volar surface of the middle phalanx and can help identify PIPJ subluxation or dislocation.

Case courtesy of Dr Mohammad A. ElBeialy, Radiopaedia.org. From the case rID: 46050

Treatment

Non- operative: A stable joint without a large avulsion fracture (<40% of articular segment) and/or a reducible fracture with 30 degrees of flexion is usually managed conservatively with splinting. In less severe injuries the injured finger can be buddy taped.

Operative: Surgical opinion should be sought if there is instability of the PIPJ or there is a large avulsion fracture.

When you examine Tori’s hand there is an isolated injury to Tori’s right middle finger as evidenced by swelling, bruising and tenderness to the PIPJ. Although active ROM is painful, Tori is able to fully extend and flex the finger. X-ray demonstrates a small avulsion fracture to the volar base of the middle phalanx on her right middle finger and you correctly diagnose her with a volar plate injury. Tori’s injury is stable and suitable for buddy taping to allow for early range of motion and prevent stiffness.

Distal Phalangeal Fractures

Distal tuft fracture

Khalid is a 2-year-old boy. He is brought to ED by his Mum as he caught his right index finger in the hinge side of a closing door. You examine his hands and note swelling and erythema to the distal phalanx of his right index finger. There is no nail bed injury or open wounds and he is moving the finger freely as you observe him playing with a toy tractor which was kindly supplied by the PED play specialist. His Mum appears more upset than he is, so you calmly reassure her that a serious finger injury is unlikely but an X-ray is required to rule out a fracture.

Mechanism

Distal tuft fractures are common in the toddler or pre-school age groups and typically occur as a result of direct crush injuries such as getting little fingers caught in a closing door.

Presentation

A concomitant nail bed laceration or pulp laceration may be present in children who have a distal tuft fracture. In this case the fracture is classed as an open fracture and opinion should be sought from Plastic Surgery Team. Check out the DFTB post on fingertip injuries for more information related to the assessment and management of nail bed injuries. Be alert for injury to flexor/extensor tendons.

Treatment

Non-Operative: Most children who have a closed distal tuft fracture are treated conservatively with splinting or buddy taping.

Operative: Surgical treatment is reserved for patients with distal tuft fractures who have nail bed injuries, subtotal/total amputations, or an unstable transverse fracture pattern.

X-ray demonstrates an un-displaced tuft fracture. You buddy tape Khalid’s fingers and reassure Mum that the fracture is small and unlikely to cause Khalid any functional problems.

Seymour fractures

Jordan is a 12-year-old boy who is brought to the PED with an injury to his left thumb. During a rugby match he was tackled to the ground and an opposition player stood on his thumb. He shows you a swollen, bruised partially flexed thumb. There is blood at the proximal nail fold and the nail plate is partially avulsed. The finger is visibly contaminated with dirt and soil from the rugby pitch, so you irrigate it with saline prior to X-ray and check that Jordan’s vaccination status is up to date.

Mechanism

A Seymour fracture is an injury unique to children. This fracture pattern is usually caused by a crush injury and results in an angulated Salter-Harris type I or Salter-Harris type II fracture with an associated nail bed injury. It is important to recognise this fracture pattern as early referral to a hand surgeon is important to avoid complications.

Presentation

The typical presentation is a swollen, bruised, and painful finger flexed at the DIPJ. There may be blood under the nail or the nail plate can be completely avulsed proximally causing it to sit superficial to the eponynchial fold (aka proximal nail fold). Soft tissue (often the germinal matrix of the nail) can become interposed in the fracture which prevents fracture reduction and healing.

Imaging

PA X-ray views of the injured finger often appear normal. Lateral view X-ray are used to confirm the diagnosis.

Pro tip! Because of the flexed appearance at the DIPJ, a Seymour fracture can be misinterpreted as bony mallet injury; however a mallet finger fracture line enters DIPJ, while Seymour fracture line traverses physis (does not enter DIPJ).

Treatment

Non-Operative: Closed injuries are managed with closed reduction and splinting. The child may be followed up with a weekly X-ray to ensure maintenance of fracture reduction.

Operative: Substantive injuries require open reduction and nail bed repair.

Bottom Line

It is important to seek surgical opinion regarding the management of Seymour fractures as if left untreated possible complications include osteomyelitis, malunion, and pre-closure of the physis.

Jordan’s x-ray shows an angulated Salter-Harris type II fracture to the distal phalanx and you correctly diagnose a Seymour fracture. You refer Jordan to the plastic surgery team who decide to take Jordan to theatre to ensure a thorough washout and repair of the nail bed injury.

Metacarpal Fractures

Katie is a 15-year-old girl who presents to your ED with her father. Her father reports that she had an argument with her Mum and punched a wall at home, he also reports that this is not the first time an incident like this has occurred. Katie shows you her right hand which is grossly swollen and bruised over the dorsal surface. There are no open wounds and she reports focal tenderness on palpation to her 5th metacarpal bone. There is an obvious loss of knuckle height and rotational deformity to her little finger. During the exam she is visibly withdrawn and quiet and you are suspicious that there is more than a hand injury bothering Katie.  

Mechanism

Metacarpal fractures are common in adolescent athletes. The most common type of metacarpal fracture is the so-called ‘‘boxer’s fracture’’, which involves the neck of the ring or small finger metacarpal. This injury usually occurs as a result of direct bony trauma when the child/adolescent strikes a fixed object such as a wall with a closed fist or is struck on a fisted hand with an object such as a bat/hurl/hockey stick for example.

Presentation

The child/adolescent will usually present with bruising, swelling and diffuse pain over the dorsum of the hand. There may be loss of knuckle prominence. Be vigilant for rotational deformity; no degree of malrotation is acceptable.

Ensure to evaluate skin integrity over the injured area, check for and document the presence of open wounds; consider the possibility that these could be so-called ‘’fight bites’’ and will require antibiotics. Substantial injuries or infected open wounds require a surgical opinion as these may require admission for IV antibiotic cover and washout in theatre. Check integrity of flexor/extensor tendons in the presence of open wounds. Remember to check Tetanus vaccination status.

A child/adolescent who presents to the PED with a hand injury because of a fight or an injury mechanism such as puching a wall requires special attention- screening for mental health and/or social problems is paramount. Involvement of medical social worker teams or mental health teams may be necessary. The HEEADSSS screening tool may be useful to guide this line of inquiry.  

Treatment

Treatment is generally based on the level of injury (e.g. head, neck, shaft and base) and clinical findings (rotational deformities, open wounds, fracture stability).  

Un-displaced stable fractures of the neck or shaft (2nd-5th metacarpals)

Non-operative: Can be treated in rest volar splint/back -slab and followed up in clinic

Angulated neck of metacarpal fractures

Most common is fracture of 5th metacarpal or  ‘‘Boxer’s fracture’’

Treatment guided by degree of angulation. Seek surgical opinion

Non-operative: Closed reduction in PED using nerve block +/- procedural sedation and immobilisation in cast

Operative: Surgery may be required in the presence of open wounds, suspected tendon injuries or if angular deformity is substantial and/ or there is a rotational deformity on clinical exam.

Case courtesy of Dr Benoudina Samir, Radiopaedia.org. From the case rID: 23848

Displaced intra articular, unstable, comminuted or unstable fractures

Operative: These fractures all require surgical referral

Metacarpal head fracture (intra-articular) Courtesy of Orthobullets: https://www.orthobullets.com/hand/6037/metacarpal-fractures

Thumb metacarpal fractures

Thumb metacarpal base fractures require surgical opinion. Disruption of carpometacarpal (CMC) joint congruity can result in significant functional impairments for a child/adolescent particularly loss or limitation of pincer or power grip.

Specific names are given to fractures of the base of the 1st metacarpal

  • Bennett fracture: defined as an intra-articular 2-part fracture of the base of 1st metacarpal bone *(see also Reverse Bennett fracture below)
  • Rolando fracture: similar to Bennett fracture but prognosis is worse. Defined as a comminuted intra-articular fracture of the 1st metacarpal, producing at least 3 parts.

X-ray demonstrates a severely angulated fracture to the neck of Katie’s 5th metacarpal bone. Taking this into consideration and the presence of rotational deformity, you refer her to the hand surgery team for management. They decide to admit her for manipulation under anaesthetic (MUA). While awaiting admission you get the opportunity to establish a rapport and talk to Katie about her mental health. You use the HEEADSSS screening tool to guide your inquiry. She reveals information about difficulties at home related to her mother’s substance abuse and reports that she has been missing a lot of school due to bullying. Katie agrees that she needs help dealing with these issues and you refer her to the inpatient mental health team with her permission. Her dad is also informed.

*Reverse Bennett fracture dislocation

An intra-articular fracture dislocation of the base of 5th metacarpal bone is called a reverse Bennett fracture. This fracture pattern is inherently unstable and referral to hand specialist is essential.

Reverse Bennett fracture dislocation Case courtesy of Dr Alborz Jahangiri, https://radiopaedia.org/cases/reverse-bennett-fracture-dislocation-1

References

Andy Neill. AFEM 033 | Hand: Lingo and soft tissues. Retrieved from https://litfl.com/bscc/clinical-anatomy/hand-anatomy/

Abzug, J. M., Dua, K., Bauer, A. S., Cornwall, R., & Wyrick, T. O. (2016). Pediatric phalanx fractures. Journal of the American Academy of Orthopaedic Surgeons24(11), e174-e183.

Sullivan, M. A., Cogan, C. J., & Adkinson, J. M. (2016). Pediatric hand injuries. Plastic Surgical Nursing36(3), 114-120.

Wahba, G., & Cheung, K. (2018). Pediatric hand injuries: Practical approach for primary care physicians. Canadian Family Physician64(11), 803-810.

Weber, D. M., Seiler, M., Subotic, U., Kalisch, M., & Weil, R. (2019). Buddy taping versus splint immobilization for paediatric finger fractures: a randomized controlled trial. Journal of Hand Surgery (European Volume)44(6), 640-647.