Finger and Hand 14

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M. De Maeseneer, MD, PhD

Division of Radiologic Sciences, Wake Forest University Hospital, Medical Center Boulevard,Winston-Salem, North Carolina, NC 27157, USA

F. Ebrahim, MD

University of Michigan Hospitals, Ann Arbor, Michigan, USA

Finger and Hand 14

Michel De Maeseneer and Farhad Ebrahim

Box 14.1. Radiography

● Of value if bony injury or change in bony alignment

● Normal if bone changes are absent

14.1

Introduction and Technical Considerations With technical advances in imaging systems, injuries of hand and ﬁ ngers can be accurately evaluated with ultrasound and magnetic resonance. Although such injuries can be assessed by expert clinical examination, additional information obtained from imaging can help in optimizing treatment planning.

For ultrasound, linear or dedicated hand transducers can be used. High resolution is essential. As a rough guideline, transducers of 12 MHz or higher are

Box 14.2. Ultrasound

● Excellent for ﬁ ne hand soft tissue structures

● Quick, and inexpensive

● Requires excellent knowledge of anatomy and ultrasound approach

● Dynamic examination possible

● Competitive with MRI for hand soft tissue injury

Box 14.3. MRI

● Excellent for soft tissue and bone marrow changes

● Good system and technique mandatory for hand imaging

● May be time consuming and expensive

C O N T E N T S

14.1 Introduction and

Technical Considerations 225

14.2 Extensor Tendon Rupture 226 14.3 Dorsal Hood Rupture 227 14.4 Flexor Tendon Rupture 227 14.5 Annular Pulley Rupture 229 14.6 Volar Plate and

Collateral Ligament Injury 230

14.7 Ulnar Collateral Ligament of the Thumb 231 14.8 De Quervain Tendons 232

14.9 Other Sport Related Injuries of the Hand 232 14.10 Conclusion 233

Things to Remember 233 References 233

ideal. Frequency ranges above 12 MHz are offered by many vendors.

For magnetic resonance, high resolution images can be obtained with dedicated fi nger coils. A drawback of these coils is the very small fi eld of view offered. Wrist coils or circular coils also give excellent results. Meticulous attention to patient immobilization, choice of the smallest fi eld of view obtainable, and optimizing signal to noise ratio by carefully selecting imaging parameters will yield

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weighted images. These sequences offer high detail, however, excellent knowledge of normal anatomy is essential to assess pathological changes. “Fluid- sensitive” sequences will consist of STIR weighted images or T2 fat saturated images and will empha- size high signal intensity changes. These sequences offer less imaging detail in the ﬁ ngers due to the small ﬁ eld of view. Gradient echo sequences are an alternative to spin echo sequences, but susceptibil- ity artefacts related to bone-soft tissue interfaces, and chemical shift artifact related to muscle-fat interfaces, adversely affect image quality in the hands.

14.2

Extensor Tendon Rupture

The extensor tendon system has a distal insertion terminating on the base of the distal phalanx and a proximal insertion terminating on the base of the middle phalanx (Figs. 14.1 and 14.2.). The extensor system receives contributions from the interosseus muscles as well as from the lumbrical muscles (Landsmeer 1949). A rupture of the distal insertion is designated “mallet fi nger” or “baseball fi nger” and typically results in pain and swelling, and inability to extend the distal phalanx (Klein- baum 2005)fl exion deformity is present at the DIP joint. The diagnosis is usually made clinically. Ultra- sound may be performed to establish the degree of retraction, diagnose associated collections or tiny avulsion fractures which may be underestimated clinically (Fig. 14.3). Ruptures of the central insertion are more commonly recognized in the setting of infl ammatory conditions but may also relate to trauma. A rupture of the central slip insertion typically leads to boutonnière deformity. This usually results from sudden DIP extension, and leads to hyperextension at the MCP, fl exion at the PIP, and hyperextension at the DIP joints. Diagnosis of tendon rupture is straightforward with ultrasound.

Ultrasound can show the tendon rupture dynamically, as well as demonstrate the extensor ﬁ bers that

slide to the side of the PIP joint (Fig. 14.4). More proximal ruptures of the extensor system over the midhand can also occur (Fig. 14.5). MR may also be employed to diagnose extensor rupture, but lacks the dynamic capability and imaging detail of ultrasound.

Fig. 14.1. Extensor system. Line drawing shows lateral aspect of ﬁ nger. Extensor tendon combines with interosseus tendons to terminate in central insertion (arrow, C), and distal inser- tion (arrow, D)

Fig. 14.2. Central extensor insertion. Sagittal proton density weighted MR image. Termination of the central insertion is shown (arrow)

Fig. 14.3. Mallet ﬁ nger. Sagittal ultrasound image. Note complete tear of distal insertion (Mallet ﬁ nger) appearing hypoechoic, and retracted tendon end (arrows)

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14.3

Dorsal Hood Rupture

At the level of the metacarpophalangeal joint the extensor tendon is kept in place by dorsal reinforcements designated dorsal hoods (Fig. 14.6). The dorsal hood consists of lateral bands attaching to and cover- ing the extensor tendons at the metacarpal head level.

Ruptures of the sagittal bands leads to displacement of the extensor tendons from their central positions over the metacarpal heads (Fig. 14.7). Usually the second and third digits are involved secondary to

direct trauma such as in boxing. On ultrasound the tendon can be shown dynamically to displace from its normal central position. A hypoechoic cleft also may be apparent in the normal location of the sagittal bands. At MR disruption of the sagittal bands may be depicted as a hyperintense signal intensity area adjacent to the tendons.

14.4

Flexor Tendon Rupture

At midhand level the fl exor tendons are easily depicted. The fl exor superfi cialis tendon is located more ventrally (Fig. 14.8). On the radial side of the

Fig. 14.5. Extensor rupture. Sagittal ultrasound image shows proximal rupture of extensor tendon over midhand (arrow- heads)

Fig. 14.6. Dorsal hood. Transverse ultrasound image shows triangular sagittal bands (arrowheads) at both sides of exten- sor tendon

Fig. 14. 7. Dorsal hood injury. Transverse ultrasound shows displacement of extensor tendon (arrowheads) relative to central position over metacarpal head (arrow)

Fig. 14.4a,b. Boutonniere deformity. a Sagittal ultrasound image. Note avulsion of ﬁ bers at insertion of central slip (arrowhead). b Coronal ultrasound image at lateral aspect of ﬁ nger shows laterally located components (arrows) of exten- sor system that are thickened and scarred down adjacent to the bone

a

b

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to the extensor system. Tears of the lumbricals have been described in rock climbers leading to rupture and hematoma in the muscle belly (Schweizer 2003).

Such muscle tears are most easily demonstrated with ultrasound (Fig. 14.11). “Fluid sensitive” magnetic resonance sequences also may show muscle tears as hyperintense areas.

The relationship of the fl exor superfi cialis tendon and the fl exor profundus tendon varies considerably throughout the fi nger. The fl exor profundus tendon passes through an opening in the fl exor superfi cialis tendon and continues to insert onto the base of the distal phalanx. The fl exor superfi cialis tendon inserts at the level of the middle aspect of the middle phalanx (Fig. 14.12). Flexor tendon disruption may

Fig. 14. 8. Flexor tendons. Sagittal anatomical slice shows insertion of fl exor profundus (arrow) and of fl exor superfi - cialis (arrowhead)

Fig. 14. 9. Lumbricals. Anatomical dissection shows lumbrica- lis muscle (arrowheads) adjacent to radial side of ﬂ exor ten- dons (F)

Fig. 14. 10. Lumbricals. Transverse proton density MR image shows lumbricals (L) at radial aspect of ﬂ exor tendons (arrows)

Fig. 14.11. Lumbrical tear. Transverse ultrasound image.

Normal ﬂ exor tendons are seen (F). Normal hypoechoic lum- brical (thin arrow) is seen, as well as hyperechoic lumbrical (thick arrow) corresponding to recent tear

be related to transsection. Avulsive injuries in blunt trauma typically involve the distal insertion (ﬂ exor profundus) and this condition is also designated rugger jersey ﬁ nger (Fig. 14.13) (Cohen et al. 2004).

Tendon ruptures can be demonstrated both by ultrasound and magnetic resonance.

Fig. 14. 12. Flexor tendons. Sagittal proton density MR. Normal insertion of fl exor profundus tendon (arrowhead), and fl exor superfi cialis tendon (bold arrow) is seen

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14.5

Annular Pulley Rupture

The fl exor tendons are covered by fi brous reinforcements that are termed annular or cruciform pulleys (Fig. 14.14) (Parellada 1996; Kovacs 2002).The cruciform reinforcements are less important and are even diffi cult to recognize on anatomic dissection.

The annular reinforcements are strong bands easily recognizable at dissection . They are classiﬁ ed as ﬁ ve

different bands, termed the A1 to the A5 pulleys. Usu- ally, when an injury occurs, it extends from proximal to distal involving the A1 pulley fi rst, and then con- tinuing distally involving the A2 pulley. The A3 pulley is located in regard of the proximal interphalangeal joint. The A4 pulley is located at the middle aspect of the middle phalanx, and the A5 pulley is located in regard of the distal interphalangeal joint. The purpose of the annular pulleys is to keep the tendon in close contact with the bone during fl exion of the fi nger.

The pulleys cannot be seen consistently using US, but may occasionally be evident as hypoechoic interfaces at the superﬁ cial aspect of the tendons. Annular pulley rupture has typically been described in rock climbers. Dynamic ultrasound shows the increased distance of the tendon to the bone in comparison to the normal side (Fig. 14.15). This displacement, also designated “bowstring deformity” may also be shown using magnetic resonance.

Fig. 14.13. Flexor rupture. Sagittal ultrasound image. Hypo- echoic cleft corresponding to avulsion of ﬂ exor profundus (arrowheads) is seen

Fig. 14.14. Annular pulleys. Line drawing shows ventrally located annular pulleys A1 to A5 (arrows)

Fig. 14.15. Pulley rupture. Composite image of sagit- tal ultrasound images. A ﬂ exor system in close prox- imity to bone (long arrow), above. A pulley tear with bowstring appearance; ﬂ exor system is displaced from adjacent bone (arrowheads), below

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shape of the head of a phalanx, but also to the pres- ence of thick volar plates at the level of the interphalangeal and metacarpophalangeal joints (Figs. 14.16 and 14.17). The volar plates are ﬁ brous structures attached to the distal phalanx and extending proximally (Nance et al. 1979). The oblique bands of the collateral ligaments of the joint connect to the volar plates. Hence, volar plate injuries are often associated with injuries of the collateral ligaments. Volar plate

Fig. 14.16. Volar plate. Sagittal anatomic slice shows ﬂ exor tendons (F), superﬁ cial to volar plate (arrows)

Fig. 14.17. Volar plate. Sagittal ultrasound image shows hyper- echoic volar plate (arrow)

Fig. 14.18. Volar plate avulsion. Lateral radiographs shows avulsion (arrowhead) of ventral aspect of base of phalanx, typical of volar plate avulsive injury

Fig. 14.19. Volar plate tear. Sagittal ultrasound image shows hypoechoic cleft (arrow) in thickened volar plate correspond- ing to tear

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14.7

Ulnar Collateral Ligament of the Thumb The metacarpophalangeal area of the thumb is vul- nerable to a spectrum of injuries, sometimes designated ski thumb, or gamekeepers thumb. Such injury may occur by thumb hyperextension or radial deviation. Injuries of the ligament may result in loss of grasp function between thumb and index fi nger (Figs. 14.22 and 14.23). The ulnar collateral ligament may show partial or complete tears (Fig. 14.24). Plain radiographs may show an avulsion fracture at the base of the proximal phalanx (Fig. 14.25). A specifi c complication occurs when the ulnar collateral ligament retracts and becomes located superfi cially to the adductor pollicis aponeurosis. This complication is designated “Stener lesion” (O’Callaghan et al.

1994).

Fig. 14.20. Volar plate injury. Sagittal ultrasound image shows hyperechoic bone fragment (arrow), in the setting of volar plate avulsion

Fig. 14.21. Volar plate injury. Sagittal proton density MR image shows thickened volar plate (arrow) of increased intensity cor- responding to tear

Fig. 14.22. Ulnar collateral ligament of thumb. Transverse ana- tomical slice shows adductor aponeurosis (arrow) overlying ulnar collateral ligament of thumb (arrowheads)

Fig. 14.23. Ulnar collateral ligament of thumb. Coronal MR image shows hypointense adductor aponeurosis and deeper ulnar collateral ligament (arrow)

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Diagnosis of different stages of UCL tear and Stener lesion can be accomplished by ultrasound (Fig. 14.26). Magnetic resonance can also differenti- ate between ulnar collateral ligament tear and Stener lesion. In Stener lesion a proximally located soft tissue nodule is apparent which has been designated the “jojo” sign.

Fig. 14.25. Gamekeepers thumb. AP radiograph shows avul- sion (arrow) at base of proximal phalanx corresponding to gamekeepers thumb

Fig. 14.26. Stener lesion. Coronal ultrasound image shows lobulated and swollen appearance of proximal aspect of torn ulnar collateral ligament of thumb, typical of Stener lesion (arrowheads)

Quervain 2005). Inﬂ ammation results in tendon thickening, synovial sheath and retinaculum thickening. It may be caused by overuse such as in racquet sports, or sports requiring repetitive rotating of the wrist. Diagnosis can be made either by ultrasound or magnetic resonance (Fig. 14.27).

14.9

Other Sport Related Injuries of the Hand In a study of 100 consecutive hand injuries in boxing, Noble (1987) found that 35% of the injuries occurred at the base of the 2nd to 5th metacarpals, includ- ing the wrist joint. Mechanism of injury was forced ﬂ exion of the wrist. Other boxing injuries affecting the hand occurred in the thumb area (39%) and the phalanges and the rest of the metacarpals (Fig. 14.28), excluding the bases (26%). Other soft tissue structures of the wrist may also be traumatized.

Fig. 14.24. Ulnar collateral ligament of thumb injury. Line drawing shows spectrum of injury. In 1, sprain of the ligament is seen (arrowheads). In 2, a partial tear (arrowhead) is illus- trated. In 3, a complete tear and a small bony avulsion is seen (arrow). In 4, proximal retraction and displacement superﬁ cial to the adductor aponeurosis, corresponding to Stener lesion, is shown (arrowhead)

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Fig. 14.28. Spiral fracture of the third meta- carpal shaft in a boxer, as seen on a PA radiograph of the hand (Courtesy of W. Peh)

Fig. 14.27. de Quervains tenosynovitis. Composite transverse ultrasound image. A normal ﬁ rst extensor group is seen above. Note thickened aspect of tendons, synovium and retinaculum on abnormal side, below (arrows)

14.10 Conclusion

Ultrasound and MRI are important tools for diag- nosing sports related injuries of the ligaments and tendons of the hand. Important injuries may involve the ﬂ exor and extensor tendons, collateral ligaments, annular pulleys, volar plate, and dorsal hood.

Things to Remember

1. Rupture of central extensor insertion can lead to “boutonniere”, distal insertion to “mallet”

ﬁ nger.

2. With dorsal hood injury extensor tendons can be displaced from their central position over the MCP heads.

3. Flexor avulsion typically involves the ﬂ exor profundus and is designated rugger jersey ﬁ nger.

4. With rupture of the pulleys, bowstring deformity can occur.

5. Volar plate and collateral ligament injuries are often associated.

6. When the proximal portion of the UCL of the thumb becomes located superﬁ cial to the adductor aponeurosis, Stener lesion is diag- nosed.

7. Racquet sports may be a risk factor for devel- oping De Quervain tenosynovitis.

References

Cohen SB, Chabra AB, Anderson MW et al. (2004) Use of ultrasound in determining treatment for avulsion of the ﬂ exor digitorum profundus (rugger jersey ﬁ nger): a case report.

Am J Orthop 33:546–549

De Quervain F (2005) On the nature and treatment of ste- nosing tendovaginitis on the styloid process of the radius.

(Translated article: Muenchener Medizinische Wochen- schrift 1912, 59, 5–6). J Hand Surg 30:392–394

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Rec 104:31–44

Nance EP Jr, Kaye JJ, Milek MA (1979) Volar plate fractures.

Radiology 133:61–64

imaging. AJR Am J Roentgenol. 167:347–349

Schweizer A (2003) Lumbrical tears in rock climbers. J Hand Surg 28:187–189