Traumatic Extensor Hood Rupture (Sagittal Band Injury)

Traumatic extensor hood rupture is an uncommon hand injury, particularly reported in boxers and other high-level athletes.¹

Extensor tendon injuries may result from trauma², inflammatory joint disease³ or steroid injections⁴. In boxers, blunt impact is the most common mechanism described.⁵

Illustration: Traumatic rupture of the extensor hood.

Anatomy

The extensor tendons cross the metacarpophalangeal (MCP) joints and are stabilised by transverse fibres forming the sagittal bands. These structures surround the extensor mechanism dorsally and connect toward the volar plate and deep transverse metacarpal ligament.⁶

The sagittal band: – Helps prevent radial or ulnar subluxation of the extensor tendon – Allows dynamic tendon gliding during flexion and extension.

A complete sagittal band rupture may cause instability of the extensor tendon over the MCP joint. Radial tears generally cause more instability than ulnar tears.⁷ During MCP flexion, the tendon may subluxate toward the opposite side of the tear and return toward the midline during extension.⁸

Clinical Presentation and Diagnosis

Initial findings include localised tenderness, pain and functional limitation. Swelling and extensor tendon subluxation may be visible on examination.⁵

One study⁵ used MRI to identify an extensor hood rupture involving the middle finger, with longitudinal splitting of the ulnar sagittal band and capsule.

Ultrasound may demonstrate a hypoechoic or thickened sagittal band and dynamic displacement of the extensor tendon. Persistent instability may also be identified on follow-up.¹⁰

Treatment

Surgical Treatment

Studies have reported favourable outcomes after surgical repair in selected cases, compared with conservative approaches.¹,²,¹¹,¹²

Loosemore and colleagues⁵ described surgical repair with the MCP joint in 90° flexion followed by immobilisation in the Edinburgh position for four weeks. This approach aims to reduce the risk of shortening, stiffness and contracture.¹³

Rehabilitation and Functional Outcomes

Evidence specifically addressing rehabilitation after this injury is limited. Experience with boxers may inform management after other hand procedures, but rehabilitation must be adapted to the injury, repair and individual patient.

A 20-year-old British boxer underwent surgery followed by four weeks of immobilisation with the MCP joint flexed to 90° and the interphalangeal joints extended. After four months he regained full, pain-free movement with the extensor tendon centred. Grip-ball and finger-band strengthening began five months after surgery, followed by gradual return to water-bag boxing at nine months. He returned to international competition after twelve months.⁵

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References

1. Hame SL, Melone CP Jr. Boxer’s knuckle in the professional athlete. Am J Sports Med 2000;28(6):879–82.

2. Posner MA, Ambrose L. Boxer’s knuckle—dorsal capsular rupture of the metacarpophalangeal joint of a finger. J Hand Surg [Am] 1989;14(2 Pt 1):229–36. doi:10.1016/0363-5023(89) 90011-7.

3. Ertel AN. Flexor tendon ruptures in rheumatoid arthritis. Hand Clin 1989;5(2):177–90.

4. Chen SK, Lu CC, Chou PH, Guo LY, Wu WL. Patellar tendon ruptures in weight lifters after local steroid injections. Arch Orthop Trauma Surg. 2008;129(3):369-72. doi: 10.1007/s00402-008-0655-1.

5. Loosemore MJ, Ansdell ML, Charalambous CP, Harrison JW, Hayton MJ. Traumatic Extensor Hood Rupture, 2009;4(2):177–179. https://doi.org/10.1007/s11552-008-9154-7

6. Doyle JR, Botte MJ. Surgical Anatomy of the Hand and Upper Extremity. Philadelphia, Pa: Lippincott Williams & Wilkins; 2003.

7. Young CM, Rayan GM. The sagittal band: anatomic and biomechanical study. J Hand Surg Am. 2000; 25(6):1107-13.

8. Extensor Tendon Lacerations.https://emedicine.medscape.com/article/1286225-overview#a10

9. Reviewed – Withdrawn

10. Willekens I, Kichouh M, deMey J, Brussel BE, Charleroi BE. Injuries of the dorsal extensor hood. ESSR. 2013; p-0142. Doi:http://dx.doi.org/10.1594/essr2013/P-0142

11. Arai K, Toh S, Nakahara K, Nishikawa S, Harata S. Treatment of soft tissue injuries to the dorsum of the metacarpophalangeal joint (Boxer’s knuckle). J Hand Surg [Br] 2002;27(1):90–5. doi:10.1054/ jhsb.2001.0656.

12. Bents RT, Metz JP, Topper SM. Traumatic extensor tendon dislocation in a boxer: a case study. Med Sci Sports Exerc 2003;35(10):1645–7. doi:10.1249/01.MSS.0000089340.89660.EB.

13. James JIP. Fractures of the proximal and middle phalanges of the fingers. Acta Orthop Scand 1962;32:401–12.