The effect of a radial neck notch on press-fit stem stability: A biomechanical study on 7 cadavers

Dave R. Shukla, Dipit C. Sahu, James S. Fitzsimmons, Kai Nan An, Shawn W. O'Driscoll

Research output: Contribution to journalArticle

Abstract

Background: Minimal micromotion is necessary for osteointegration of cementless radial head prostheses. When radial head fractures extend longitudinally, where the neck cut for prosthetic replacement should be made is uncertain. We hypothesized that complete resection of the notched portion of a radial neck confers no advantage in initial stability compared with not resecting the defect and inserting the implant into a notched radial neck. Materials and methods: The radii of 7 cadavers underwent radial head resection and implantation with a 25-mm-long press-fit radial head stem. Before implantation, a 5-mm-long notch that was less than 1-mm wide was made in the radial neck. After the stem-bone micromotion was recorded, the proximal 5 mm of radial neck, incorporating the entire notch, was cut away, the stem was inserted 5 mm further, and the resulting micromotion was recorded. Results: The mean micromotion measured in the presence of a cortical notch was 51 ± 6 μm. After the neck was circumferentially cut and the stem was advanced, the micromotion (46 ± 9 μm) was not statistically significantly different. Discussion: Initial stability of an adequately sized cementless stem in the presence of a 5-mm-long cortical notch was well within the threshold needed for bone ingrowth (<100 μm). In addition, there was no reduction of micromotion after the notch-containing portion of the radial neck was resected and the stem was advanced. Making a neck cut distal to a 5-mm-long, 1-mm-wide cortical notch does not confer added stability. Thus, surgeons can preserve bone stock and avoid an aggressive neck cut.

Original languageEnglish (US)
JournalJournal of Shoulder and Elbow Surgery
DOIs
StateAccepted/In press - Jan 1 2017

Fingerprint

Cadaver
Neck
Bone and Bones
Prostheses and Implants

Keywords

  • Basic Science Study
  • Biomechanics
  • Biomechanics
  • Fracture
  • Implant ingrowth
  • Micromotion
  • Radial head implant
  • Radial neck notch

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine

Cite this

The effect of a radial neck notch on press-fit stem stability : A biomechanical study on 7 cadavers. / Shukla, Dave R.; Sahu, Dipit C.; Fitzsimmons, James S.; An, Kai Nan; O'Driscoll, Shawn W.

In: Journal of Shoulder and Elbow Surgery, 01.01.2017.

Research output: Contribution to journalArticle

Shukla, Dave R. ; Sahu, Dipit C. ; Fitzsimmons, James S. ; An, Kai Nan ; O'Driscoll, Shawn W. / The effect of a radial neck notch on press-fit stem stability : A biomechanical study on 7 cadavers. In: Journal of Shoulder and Elbow Surgery. 2017.
@article{e31e800ded5e4f45af21ba3b64d2977d,
title = "The effect of a radial neck notch on press-fit stem stability: A biomechanical study on 7 cadavers",
abstract = "Background: Minimal micromotion is necessary for osteointegration of cementless radial head prostheses. When radial head fractures extend longitudinally, where the neck cut for prosthetic replacement should be made is uncertain. We hypothesized that complete resection of the notched portion of a radial neck confers no advantage in initial stability compared with not resecting the defect and inserting the implant into a notched radial neck. Materials and methods: The radii of 7 cadavers underwent radial head resection and implantation with a 25-mm-long press-fit radial head stem. Before implantation, a 5-mm-long notch that was less than 1-mm wide was made in the radial neck. After the stem-bone micromotion was recorded, the proximal 5 mm of radial neck, incorporating the entire notch, was cut away, the stem was inserted 5 mm further, and the resulting micromotion was recorded. Results: The mean micromotion measured in the presence of a cortical notch was 51 ± 6 μm. After the neck was circumferentially cut and the stem was advanced, the micromotion (46 ± 9 μm) was not statistically significantly different. Discussion: Initial stability of an adequately sized cementless stem in the presence of a 5-mm-long cortical notch was well within the threshold needed for bone ingrowth (<100 μm). In addition, there was no reduction of micromotion after the notch-containing portion of the radial neck was resected and the stem was advanced. Making a neck cut distal to a 5-mm-long, 1-mm-wide cortical notch does not confer added stability. Thus, surgeons can preserve bone stock and avoid an aggressive neck cut.",
keywords = "Basic Science Study, Biomechanics, Biomechanics, Fracture, Implant ingrowth, Micromotion, Radial head implant, Radial neck notch",
author = "Shukla, {Dave R.} and Sahu, {Dipit C.} and Fitzsimmons, {James S.} and An, {Kai Nan} and O'Driscoll, {Shawn W.}",
year = "2017",
month = "1",
day = "1",
doi = "10.1016/j.jse.2017.09.037",
language = "English (US)",
journal = "Journal of Shoulder and Elbow Surgery",
issn = "1058-2746",
publisher = "Mosby Inc.",

}

TY - JOUR

T1 - The effect of a radial neck notch on press-fit stem stability

T2 - A biomechanical study on 7 cadavers

AU - Shukla, Dave R.

AU - Sahu, Dipit C.

AU - Fitzsimmons, James S.

AU - An, Kai Nan

AU - O'Driscoll, Shawn W.

PY - 2017/1/1

Y1 - 2017/1/1

N2 - Background: Minimal micromotion is necessary for osteointegration of cementless radial head prostheses. When radial head fractures extend longitudinally, where the neck cut for prosthetic replacement should be made is uncertain. We hypothesized that complete resection of the notched portion of a radial neck confers no advantage in initial stability compared with not resecting the defect and inserting the implant into a notched radial neck. Materials and methods: The radii of 7 cadavers underwent radial head resection and implantation with a 25-mm-long press-fit radial head stem. Before implantation, a 5-mm-long notch that was less than 1-mm wide was made in the radial neck. After the stem-bone micromotion was recorded, the proximal 5 mm of radial neck, incorporating the entire notch, was cut away, the stem was inserted 5 mm further, and the resulting micromotion was recorded. Results: The mean micromotion measured in the presence of a cortical notch was 51 ± 6 μm. After the neck was circumferentially cut and the stem was advanced, the micromotion (46 ± 9 μm) was not statistically significantly different. Discussion: Initial stability of an adequately sized cementless stem in the presence of a 5-mm-long cortical notch was well within the threshold needed for bone ingrowth (<100 μm). In addition, there was no reduction of micromotion after the notch-containing portion of the radial neck was resected and the stem was advanced. Making a neck cut distal to a 5-mm-long, 1-mm-wide cortical notch does not confer added stability. Thus, surgeons can preserve bone stock and avoid an aggressive neck cut.

AB - Background: Minimal micromotion is necessary for osteointegration of cementless radial head prostheses. When radial head fractures extend longitudinally, where the neck cut for prosthetic replacement should be made is uncertain. We hypothesized that complete resection of the notched portion of a radial neck confers no advantage in initial stability compared with not resecting the defect and inserting the implant into a notched radial neck. Materials and methods: The radii of 7 cadavers underwent radial head resection and implantation with a 25-mm-long press-fit radial head stem. Before implantation, a 5-mm-long notch that was less than 1-mm wide was made in the radial neck. After the stem-bone micromotion was recorded, the proximal 5 mm of radial neck, incorporating the entire notch, was cut away, the stem was inserted 5 mm further, and the resulting micromotion was recorded. Results: The mean micromotion measured in the presence of a cortical notch was 51 ± 6 μm. After the neck was circumferentially cut and the stem was advanced, the micromotion (46 ± 9 μm) was not statistically significantly different. Discussion: Initial stability of an adequately sized cementless stem in the presence of a 5-mm-long cortical notch was well within the threshold needed for bone ingrowth (<100 μm). In addition, there was no reduction of micromotion after the notch-containing portion of the radial neck was resected and the stem was advanced. Making a neck cut distal to a 5-mm-long, 1-mm-wide cortical notch does not confer added stability. Thus, surgeons can preserve bone stock and avoid an aggressive neck cut.

KW - Basic Science Study

KW - Biomechanics

KW - Biomechanics

KW - Fracture

KW - Implant ingrowth

KW - Micromotion

KW - Radial head implant

KW - Radial neck notch

UR - http://www.scopus.com/inward/record.url?scp=85036541878&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85036541878&partnerID=8YFLogxK

U2 - 10.1016/j.jse.2017.09.037

DO - 10.1016/j.jse.2017.09.037

M3 - Article

C2 - 29198812

AN - SCOPUS:85036541878

JO - Journal of Shoulder and Elbow Surgery

JF - Journal of Shoulder and Elbow Surgery

SN - 1058-2746

ER -