Moderate to large engaging Hill-Sachs defects: an in vitro biomechanical comparison of the remplissage procedure, allograft humeral head reconstruction, and partial resurfacing arthroplasty.
BACKGROUND
The management of engaging Hill-Sachs defects (HSD) is controversial. The purpose of this study was to biomechanically compare 3 treatment strategies.


METHODS
Eight specimens were tested on a shoulder simulator. The protocol involved testing 2 unrepaired HSD (30% and 45%), which were then treated with remplissage, humeral head allograft (HHA), and partial resurfacing arthroplasty (PRA). Stability (defect engagement and glenohumeral stiffness) and range of motion (ROM) were measured.


RESULTS
All 30% and 45% HSDs engaged and dislocated. Remplissage and HHA effectively prevented engagement in all specimens; however, 62% of PRA engaged. No repair exhibited stiffness significantly greater than intact, but 30% and 45% remplissage produced a 74% and 207% increase, respectively, and were significantly greater than the unrepaired states (P ≤ .047). Stiffness results for HHA and PRA closely matched those of intact. In adduction, remplissage reduced internal-external ROM compared with both defects (P ≤ .01), but only 30% remplissage caused a significant decrease compared with intact (P = .049). In abduction, all repairs reduced ROM compared with HSD (P ≤ .04), but none compared with intact (P ≥ 0.05). In extension, remplissage had significantly less ROM than either HHA or PRA (P ≤ .02).


CONCLUSIONS
All procedures improved stability; however, unlike remplissage, results from HHA and PRA closely resembled intact. Remplissage (30% and 45%) improved stability and eliminated engagement but caused reductions in ROM. HHA and PRA re-established intact ROM, but PRA could not fully prevent engagement. The effects of each technique are not equivalent and further studies are required.
Department of Mechanical and Materials Engineering, The University of Western Ontario, London, Ontario, Canada.
Joshua W
JW
Giles
Ilia
I
Elkinson
Louis M
LM
Ferreira
Kenneth J
KJ
Faber
Harm
H
Boons
Robert
R
Litchfield
James A
JA
Johnson
George S
GS
Athwal
D000368:Aged; D001178:Arthroplasty / Q000379:methods; D001696:Biomechanical Phenomena; D016025:Bone Transplantation; D002102:Cadaver; D006801:Humans; D058430:Humeral Head / Q000002:abnormalities* / Q000601:surgery*; D012783:Shoulder Dislocation / Q000601:surgery*