Biomechanical Comparison of Four- versus Six-Strand Transosseous Suture Repair for Patellar Tendon Rupture

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Sports medicine

Background:

• Patellar tendon ruptures impair knee extensor function, necessitating surgical repair.
• Conflicting biomechanical data exists comparing transosseous suture and suture anchor repair techniques.
• Inconsistent suture strand counts in prior studies may explain discrepancies.

Purpose of the Study:

• To compare the ultimate load to failure of four- versus six-strand transosseous suture repair.
• To evaluate gap formation after cyclical loading.
• To determine the mode of failure for each repair type.

Main Methods:

• Six pairs of fresh-frozen cadaveric knee specimens were used.
• Specimens were randomly assigned to either four- or six-strand transosseous suture repair.
• Repaired specimens underwent cyclical loading followed by load-to-failure testing.

Main Results:

• The six-strand repair demonstrated significantly higher maximum load to failure (mean difference 319.3 N, 57.9%, p=0.03).
• No significant differences were observed in gap length after cyclical loading or at maximum load.
• Modes of failure did not differ significantly between the four- and six-strand constructs.

Conclusions:

• A six-strand transosseous patellar tendon repair construct is biomechanically stronger than a four-strand construct.
• The addition of one suture strand significantly increases construct strength by over 50%.
• This finding has implications for optimizing surgical techniques for patellar tendon repair.