Tendon Suturing Techniques in Orthopaedics

Introduction

1. Core suture - provides the main tensile strength
2. Peripheral (epitendinous) suture - smooths the repair surface and adds 10-50% additional strength

Properties of an Ideal Tendon Suture Technique

• Easy and reproducible to perform
• Secure knots with minimal gapping
• Smooth, low-profile repair that glides through pulley systems
• Sufficient strength to allow early active motion (minimum 50 N load-to-failure)
• Minimal interference with tendon vascularity

Suture Materials

• Non-absorbable sutures are preferred: polypropylene (Prolene), polyester (Ethibond), nylon
• Core suture: 3-0 or 4-0; epitendinous: 5-0 or 6-0
• Looped sutures (e.g., looped nylon) improve purchase and strength without extra knots

A. Core Suture Techniques

1. Bunnell Suture

• The classic historical technique (criss-cross or figure-of-eight pattern)
• Uses a zig-zag (crisscross) configuration through the tendon substance
• Two needles are passed in a "to-and-fro" pattern with the knot buried between the cut ends
• Disadvantage: constricts the tendon vascularity ("strangulating"), creates bulkier repair - largely replaced by Kessler and modifications

2. Modified Kessler (Grasping) Suture - Most Widely Used

• A 2-strand core suture that forms a rectangular loop on either side of the repair site
• Technique (per Campbell's Fig. 71.10):
  1. Insert a round-bodied needle as a "grasping" bite transversely near the cut end on one side
  2. Pass the suture longitudinally within the tendon substance 1-1.5 cm back from the cut end
  3. Bring out through the cut face
  4. Mirror this pattern on the other tendon end
  5. Tie the knot between the cut ends (buried knot) - reduces irritation
• Advantage: does not constrict blood supply; better gliding; easy to perform
• Load to failure: ~35-45 N (2-strand)

3. Modified Becker / Massachusetts General Hospital (MGH) Repair

• A 4-strand repair derived from the Kessler
• Uses two separate Kessler-type sutures placed at 90° to each other
• Provides significantly greater strength than 2-strand techniques
• Supports early active motion rehabilitation

4. Cruciate (Cross-Locked) Four-Strand Repair

• Suture passes through the tendon in a cross (cruciate) pattern, locking the suture in the tendon substance
• Shown to provide better resistance to gap formation and greater ultimate tensile strength than Kessler, Strickland, or Savage techniques
• The locked cruciate, modified double Tsuge, and modified Becker repairs are strong enough to support early active motion programs

5. Savage Six-Strand Repair

• Uses three pairs of sutures creating 6 strands across the repair
• One of the strongest end-to-end repair methods
• The "cross-stitch" epitendinous suture with Savage core was found to be 117% stronger than a modified Kessler with conventional epitendinous repair
• Supports early active motion but technically more demanding

6. Tang (Modified Tsuge / Multiple Looped Suture) Repair

• Uses looped nylon sutures (4-0 or 5-0)
• Three threads placed at tips of a triangle in cross-section (palmar and two dorsal placements)
• Knots are arranged in triangular fashion on the tendon surface
• Tang and cruciate repairs show better tensile strength and elastic properties than Silfverskiöld, Robertson, and modified Kessler repairs

7. Tajima (Modified Kessler with Two Separate Sutures)

• Uses two separate sutures inserted from the cut ends
• Provides a 4-strand purchase
• Commonly combined with a running epitendinous stitch for a strong, low-profile repair

B. Peripheral (Epitendinous) Suture

• Epitendinous suture smooths the repair, reduces gapping, and provides up to 50% additional tensile strength
• Preferred suture: 6-0 polypropylene or nylon in a running-lock stitch

C. End-to-Side (Pulvertaft Weave) Technique

• The smaller tendon is passed transversely through the larger tendon 2-3 times in a weaving fashion (Fig. 71.15 in Campbell's)
• Each passage is anchored with one or two sutures
• Provides strong union and allows tension adjustment before final fixation
• Preferred for tendon transfers and grafts

D. Flexor Tendon Zones and Technique Selection

E. Number of Strands and Strength

F. Factors Affecting Repair Strength

1. Purchase length: longer suture purchase (1-1.5 cm) increases strength
2. Suture calibre: larger suture = stronger
3. Locking vs. grasping: locked loops resist gap formation better
4. Knot placement: knot between the cut ends minimizes friction during gliding
5. Epitendinous suture: critical addition to core repair
6. Suture material: non-absorbable braided polyester or looped nylon preferred

G. Postoperative Rehabilitation

• Passive mobilization (Kleinert protocol): rubber-band traction for passive flexion, active extension
• Place-and-hold (Duran): passive flexion held by active muscle contraction
• Early active motion: requires 4-6 strand repair with adequate strength (>50-60 N); reduces adhesions and improves gliding

Summary Table

• Always use a core + epitendinous combination
• Modified Kessler remains the workhorse technique
• For Zone II injuries requiring early active mobilization, use a 4-6 strand repair
• The Pulvertaft weave is specifically for tendon transfers/grafts
• Cruciate four-strand provides the best balance of strength and clinical feasibility