EXTENSOR TENDON INJURY: OVERVIEW & MANAGEMENT

Compiled by Prof Pragashnie Govender (Presented by Mr Monareng, 2026)

TENDON STRUCTURE

• Microfibril
• Sub-fibril
• Fibril
• Fascicle
• Tropocollagen
• Fibroblasts
• Crimp
• Fascicular membrane
• Tendon Structure:
  • Epitenon: The outer layer of the tendon, a connective tissue that surrounds the entire tendon.
  • Endotenon: Connective tissue that surrounds individual fascicles within the tendon.
  • Paratenon: A sheath-like structure surrounding some tendons, allowing for gliding and movement.

EXTENSOR TENDONS

• Defined as tendons that extend across joints, particularly in the fingers, to allow for straightening of the digits.

EXTENSOR TENDON INJURY ZONES

Identifying the specific zone of injury is critical for management and treatment:

• Zone I: Over the Distal Interphalangeal Joint (DIPJ)
• Zone II: Over the middle phalanx
• Zone III: Over the apex of the Proximal Interphalangeal Joint (PIPJ)
• Zone IV: Over the proximal phalanx
• Zone V: Over the apex of the Metacarpophalangeal Joint (MCPJ)
• Zone VI: Over the dorsum of the hand
• Zone VII: Under the extensor tendon retinaculum
• Zone VIII: The distal forearm
• Thumb Zone IV: Over the first metacarpal
• Thumb Zone V: Under the extensor tendon retinaculum
• Thumb Zone VI: The distal forearm

SPLINTS FOR MALLET INJURIES

• Types of splints:
  • A: Aluminium and foam, with foam trimmed to approximately 5-mm thick
  • B: Stack splint for Zone I mallet injuries

STATIC SPLINTING

• Utilized for a closed rupture in Zone III.
• Bunnell’s splint:
  • Purpose: To overcome flexion deformity of the proximal interphalangeal joint after boutonnière deformity has developed.
  • Feature: The buckle can be tightened as flexion at the proximal interphalangeal joint lessens.

SHORT-ARC ACTIVE MOTION PROTOCOL

For extensor injuries in Zones III and IV:

• A: Resting splint
• B: Distal interphalangeal exercises while holding the proximal interphalangeal in full extension; this aids in lateral band gliding and their normal positioning to assist in PIP extension.
• C: Active flexion of the distal interphalangeal and PIP to the position molded by the splint
• D: Active extension to 0 degrees

HAND-BASED DYNAMIC EXTENSION SPLINT

Two types of dynamic splints for Zones III and IV:

• A: Hand-based dynamic extension splint
• B: Wrist-based dynamic extension splint for Zones III through VIII

PROXIMAL ZONES

• Static splinting for extensor injuries in the proximal zones is critical to prevent complications and ensure proper healing.

IMMEDIATE CONTROLLED ACTIVE MOTION (ICAM)

• SURGICAL TECHNIQUE
  • Relative Motion Splint: Designed to facilitate postoperative rehabilitation after repair of extensor tendon injuries at the dorsum of the hand and forearm.
  • Applications: Used for rehabilitation of sagittal band injuries and after repair of closed attrition extensor tendon ruptures in rheumatoid arthritis.
  • Advantages: Less cumbersome than other braces, can be worn during normal activities.
• Recent Applications: Has also been extended to both operative and nonsurgical rehabilitation for boutonnière deformity.
• Key Reference: Merritt, Wyndell H. (2014). J Hand Surg Am. 39(6):1187-1194.

WYNDELL MERRITT ICAM

• ICAM Digital Yoke Orthosis:
  • Features: Allows for full composite active motion of the uninjured digits while allowing 10–15° less MP flexion to the digit with the repaired tendon.
  • Purpose: Relieves tension on the extensor tendon repair without using dynamic motion.

ICAM SPLINT PROGRAMME: PATIENT OUTCOMES

• Background: Developed in the 1980s, the ICAM programme has been successful in managing extensor tendon repairs from Zones IV to VII.
• Study Aim: Describes the application of the ICAM splint programme at a specialized hand unit in South Africa.
• Methodology: Mixed methods design involving:
  • Retrospective file audit of n=75 patients
  • Interviews with therapists (n=3), surgeons (n=2), and focus group with therapists (n=7).
• Results:
  • Majority of patients (83%) were male, 40% aged 26-35.
  • Injuries predominantly violence-related (69%) compared to accidental (31%).
  • Commonly involved extensor tendon zones V (40%) and VI (47%).
  • Adherence impacted by financial status, education, and language barriers.
• Conclusions: ICAM is beneficial for managing repairs from zones IV to VII; education and adherence strategies are critical for success.

FURTHER READING

Study on Early Controlled Active Motion:

• Case Report: Focused on rehabilitation outcomes after replantation with early controlled active motion beginning 6 days post-surgery.
• Results: Nearly full active range of motion accomplished; favorable functional outcomes noted.
• Conclusion: Future research needed to assess the effects of bone shortening on tendon tension and early active motion.

EVIDENCE AND PROTOCOLS

• Evidence: Moderate quality supports early active motion as the superior motion protocol for tendon repairs.
• Recommendations: Future research should aim at patient-reported outcomes and designs of orthoses that effectively enable early active motion.

IMPORTANT RESEARCH TOPICS IN TENDON INJURIES

• Trends in rehabilitation for both flexor and extensor tendon injuries.
• Role of early motion and accurate splint design in enhancing recovery outcomes.
• Need for individualized rehabilitation programs based on specific zones of injury and healing phases.

KEY TERMS AND DEFINITIONS

• Early Active Motion (EAM): A rehabilitation approach that promotes early movement following tendon repair to enhance healing and improve outcomes.
• Immediate Controlled Active Motion (ICAM): A splinting protocol enabling early active movement while protecting the repair site.
• Splint Controlled Motion: Methods that involve the use of splints to limit but not restrict joint movement, facilitating rehabilitation.

REFERENCES

• 2020 South African Journal of Occupational Therapy. DOI: http://dx.doi.org/10.17159/2310-3833/2020/vol50no2a4
• Journal of Hand Therapy, Elsevier, 2020.