Faculty Collaboration Database

Biomechanical Comparison of Tension Band Fixation of Patella Transverse Fracture: Headless Screws Versus Headed Screws. J Orthop Trauma 2019 Jun;33(6):e240-e245

Date

02/06/2019

Pubmed ID

30720558

DOI

10.1097/BOT.0000000000001447

Scopus ID

2-s2.0-85066866013 (requires institutional sign-in at Scopus site)   9 Citations

Abstract

OBJECTIVE: This study aimed to investigate the stability and strength of tension band wire fixation using headless compression screws versus headed screws for transverse patella fractures.

METHODS: Six matched pairs of fresh-frozen cadaveric knees with transverse osteotomies created at the midpoint of the patella were surgically fixed, with one knee randomly receiving fixation with headless screws (Acumed Acutrak 4/5) and the other with headed screws (Synthes 4.0 partially threaded cannulated screws). The specimens were mounted onto a servohydraulic load frame in a 45-degree flexed position and loaded through the quadriceps tendon. Interfragmentary movement was recorded with a motion analysis system. The initial fixation stiffness, range of interfragmentary motion, and strength of the headless screw construct were compared with the headed screw construct. Failure was defined as either a sudden drop in applied tendon force or 2 mm of separation on the anterior surface of the patella (ie, clinical failure), whichever occurred first.

RESULTS: Mean primary interfragmentary motion was 0.31 ± 0.28 degrees for the headed screws and 0.10 ± 0.06 degrees for headless screws under 150 N load (P = 0.03). Mean construct stiffness was 277 ± 243 N/degrees for the headed screws and 510 ± 362 N/degrees for the headless screws (P = 0.03). None of the constructs from either group displayed structural failure before reaching the clinical failure gap of 2 mm. The mean clinical failure strength was 808 ± 183 N for the headless screws construct and 520 ± 241 N for the headed screws construct (P = 0.03).

CONCLUSIONS: Headless screw tension band fixation demonstrated superior biomechanical behaviors over standard headed screw fixation with higher construct rigidity, smaller interfragmentary motion, and greater fixation strength.

Author List

Martin JM, Applin DT, McGrady LM, Wang M, Schmeling GJ

Authors

Gregory J. Schmeling MD Vice Chair, Professor in the Orthopaedic Surgery department at Medical College of Wisconsin
Mei Wang PhD Associate Professor in the Orthopaedic Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adult
Aged
Biomechanical Phenomena
Bone Screws
Cadaver
Female
Fracture Fixation, Internal
Fractures, Bone
Humans
Male
Middle Aged
Patella
Prosthesis Design