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Central Slip Extensor Tendon Injury Treatment in Delhi

Central Slip Extensor Tendon Injuries
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What is Central Slip Extensor Tendon ?

The central slip of the extensor tendon is a crucial component of the complex extensor mechanism of the fingers. It plays a vital role in straightening the middle joint of the finger (the proximal interphalangeal or PIP joint). Injuries to this tendon can significantly impair finger function and lead to a characteristic deformity if not managed correctly.

Anatomy and Function of the Central Slip

The extensor tendons run along the back of the fingers, connecting the forearm muscles to the finger bones. As the extensor digitorum communis (EDC) tendon reaches the finger, it flattens and forms the extensor hood around the metacarpophalangeal (MCP) joint (knuckle).

At the proximal phalanx, the extensor tendon divides into three parts:

  • Central slip: This is the most dorsal (top) portion, and it inserts onto the base of the middle phalanx. Its primary function is to directly extend (straighten) the PIP joint.
  • Two lateral bands: These pass along each side of the central slip and eventually merge to insert onto the base of the distal phalanx, contributing to extension of the DIP (distal interphalangeal, or fingertip) joint.
  • Triangular ligament: A small ligament that connects the two lateral bands, preventing them from slipping palmarly (towards the palm).

The coordinated action of the central slip, lateral bands, and intrinsic muscles (lumbricals and interossei) allows for the precise and balanced extension of the finger joints.

Causes of Central Slip Extensor Tendon Injury
Central slip injuries most commonly occur due to-
  • Direct blunt trauma: A direct blow to the back of the finger, especially over the PIP joint (e.g., getting hit by a ball, falling, punching).
  • Forced hyperflexion: A sudden, forceful bending of the PIP joint while the finger is extended (e.g., catching a finger in something, sports injuries).
  • Lacerations/Cuts: A sharp object cutting the tendon on the back of the finger.
  • Rheumatoid arthritis: Chronic inflammation can weaken and rupture the tendon.
If left untreated, a central slip injury can lead to a Boutonnière deformity. This deformity is characterized by:
  • Flexion of the PIP joint (the middle joint bends towards the palm).
  • Hyperextension of the DIP joint (the fingertip joint bends backwards).
This occurs because, with the central slip torn, the lateral bands can slip volarly (towards the palm) relative to the PIP joint’s axis of rotation, causing them to act as flexors of the PIP joint instead of extensors. The unopposed pull of the extensor mechanism on the DIP joint then leads to its hyperextension. The deformity may not appear immediately but can develop gradually over days or weeks.
Symptoms of Central Slip Extensor Tendon Injury
  • Pain: Localized pain and tenderness over the back of the PIP joint.
  • Swelling: Swelling around the PIP joint.
  • Inability to fully straighten the PIP joint: The most common and direct symptom.
  • Weakness: Difficulty with grip and fine motor activities.
  • Boutonnière deformity: As described above, this may develop over time.
  • Ecchymosis (bruising): May be present.
Diagnosis for Central Slip Extensor Tendon Injury

History: Mechanism of injury, onset of symptoms, activities that worsen pain.

Physical Examination

  • Inspection: Look for swelling, deformity, or open wounds.
  • Palpation: Assess for tenderness directly over the central slip insertion at the PIP joint.
  • Active Range of Motion (AROM): Assess the ability to actively extend the PIP joint.
  • Elson’s Test: This is a classic test for central slip integrity:
    • The patient places their affected hand on a table with the PIP joint flexed 90 degrees over the edge.
    • The examiner stabilizes the middle phalanx (just below the PIP joint).
    • The patient is asked to extend their finger against resistance.
    • Positive Test (indicating central slip injury): Weak or absent PIP extension, with notable hyperextension and rigidity of the DIP joint (due to the lateral bands pulling only on the DIP joint).
    • Negative Test (intact central slip): Strong PIP extension, with a relaxed or “floppy” DIP joint.

Imaging

  • X-rays: Primarily to rule out associated fractures (e.g., avulsion fractures where a piece of bone pulls away with the tendon).
  • Ultrasound: Can be used to visualize the tendon and confirm a tear, especially in cases of delayed diagnosis.
  • MRI: Less commonly used for acute central slip injuries but can provide detailed soft tissue imaging if needed.
Physiotherapy Management

Physiotherapy is very important in the management of central slip extensor tendon injuries, both for conservative treatment and post-surgical rehabilitation. The primary goals are to promote tendon healing, prevent the development of a Boutonnière deformity, restore range of motion, and regain strength and function.

The rehabilitation protocol is typically structured in phases

Phase 1: Immobilization and Protection (Weeks 0-6)

  • Goal: Protect the healing tendon, prevent Boutonnière deformity.
  • Splinting: The most crucial aspect. A static extension splint (often a custom-made thermoplastic splint) is applied to keep the PIP joint in full extension (straight) at all times. This allows the central slip to approximate and heal without tension.
  • The DIP joint is typically left free to move to prevent stiffness and to encourage the lateral bands to remain in their correct position. Gentle passive or active DIP flexion may be encouraged to prevent contractures.
  • Patient Education: Crucial for adherence. Patients must understand the importance of keeping the PIP joint straight and the potential for Boutonnière deformity if the splint is removed or the joint is allowed to bend.
  • Activity Modification: Avoid any activities that could put stress on the PIP joint, including heavy gripping, lifting, or impact sports.
  • Swelling Management: Elevation, gentle massage, and ice packs can help reduce swelling.

Phase 2: Gradual Mobilization (Weeks 6-12)

  • Goal: Gradually restore PIP joint range of motion while maintaining tendon integrity.
  • Weaning from Splint: The therapist will guide a gradual weaning process from the full-time extension splint. This might involve:
    • Wearing the splint full-time for another few weeks, but removing it for short, controlled exercise sessions.
    • Transitioning to a night splint and wearing the splint intermittently during the day for protection during activities.
  • Controlled Active Range of Motion (AROM) Exercises:
    • DIP flexion and extension: Continue exercises for the fingertip joint.
    • MCP flexion and extension: Ensure the knuckle joint maintains full movement, often performed with the PIP joint still supported in extension.
    • Gentle PIP flexion: Specific, controlled exercises are introduced to gradually increase the range of PIP joint flexion. This often involves using an exercise block or controlled active bending within a pain-free range, progressing the range slowly over weeks.
    • Hook fist: Bending only the PIP and DIP joints while keeping the MCP joints straight. This helps promote tendon glide.
    • Composite flexion: Gradually working towards a full fist.
  • Passive Range of Motion (PROM): Gentle passive stretching may be introduced by the therapist if active motion is limited.
  • Tendon Gliding Exercises: These are essential to prevent adhesions (scar tissue) from forming around the tendon, which can restrict movement.

Phase 3: Strengthening and Functional Integration (Weeks 12+ and onwards)

  • Goal: Regain full strength, endurance, and functional use of the hand and finger.
  • Progressive Strengthening:
    • Isometric exercises: Gentle contractions against resistance.
    • Therapy putty: Squeezing, pinching, and rolling putty for hand and finger strengthening.
    • Light weights/resistance bands: For forearm and grip strengthening.
    • Finger exercises: Focus on all planes of motion and grip variations.
  • Fine Motor Control: Activities requiring dexterity (e.g., picking up small objects, writing, buttoning).
  • Functional Activities: Gradually reintroducing daily tasks, work-related activities, and sports-specific movements.
  • Scar Management: If surgery was performed, scar massage and silicone sheeting may be used to improve scar mobility and appearance.

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