Plates and non-locked screws used in the treatment of osteoporotic bone fractures frequently become loose due to everyday mechanical demands. Currently, locking plates and screws are the gold standard treatment for these fractures. However, their use has several limitations and complications as they are technically demanding, and their cost is very expensive. To improve the fixation strength of traditional unlocked plate and screw constructs, we have developed a new fixation system based on a very old concept. The system consists of a screw locking element (SLE) manufactured from PEEK, which is attached to the end of the screw shaft once it has traversed both bone cortices. A specially designed tool is used to facilitate its attachment to the screw. This tool makes it possible for the screw to traverse an osteosynthesis plate or lockwasher as well as both bone cortices and to easily find the SLE, fixing it against the far cortex. We tested the pull-out strength of SLEs and compared the results with previously published data for human femoral cortex pull-out strength. Our laboratory tests demonstrate that the mean SLE pull-out strength was 3864 ± 47.61 N, while that observed for a human femoral diaphysis cortex was 4071.54 ± 1461.69 N. This difference was not significant (p > 0.05). This new system can easily be used with any type of osteosynthesis in osteoporotic or osteopenic bones, with the screws being placed on weakened areas of the bone (e.g., fissure lines, previous orifices, or thinned metaphyseal bone cortex), or to replace over-torqued screws. It is particularly suitable for veterinary trauma, where immediate weight-bearing protection after fracture treatment is nearly impossible.

References

References
1.
Barrios
,
C.
,
Broström
,
L. A.
,
Stark
,
A.
, and
Walheim
,
G.
, 1993, “
Healing Complications After Internal Fixation of Trochanteric Hip Fractures: The Prognostic Value of Osteoporosis
,”
J. Orthop. Trauma
,
7
(
5
), pp.
438
442
.
2.
Kim
,
W.
,
Han
,
C.
,
Park
,
J.
, and
Kim
,
J.-Y.
, 2001, “
Failure of Intertrochanteric Fracture Fixation With a Dynamic Hip Screw in Relation to Pre-Operative Fracture Stability and Osteoporosis
,”
Int. Orthop.
,
25
(
6
), pp.
360
362
.
3.
Sodergard
,
J.
,
Sandelin
,
J.
, and
Bostman
,
O.
, 1992, “
Mechanical Failures of Internal Fixation in T and Y Fractures of the Distal Humerus
,”
J. Trauma
,
33
(
5
), pp.
687
90
.
4.
Flahiff
,
C. M.
,
Gober
,
G. A.
, and
Nicholas
,
R. W.
, 1995, “
Pullout Strength of Fixation Screws From Polymethylmethacrylate Bone Cement
,”
Biomaterials
,
16
(
7
), pp.
533
536
.
5.
Matsuda
,
M.
,
Kiyoshige
,
Y.
,
Takagi
,
M.
, and
Hamasaki
,
M.
, 1999, “
Intramedullary Bone-Cement Fixation for Proximal Humeral Fracture in Elderly Patients: A Report of 5 Cases
,”
Acta Orthop. Scand.
,
70
(
3
), pp.
283
285
.
6.
McKoy
,
B. E.
, and
An
,
Y. H.
, 2000, “
An Injectable Cementing Screw for Fixation in Osteoporotic Bone
,”
J. Biomed. Mater. Res.
,
53
(
3
), pp.
216
220
.
7.
Struhl
,
S.
,
Szporn
,
M. N.
,
Cobelli
,
N. J.
, and
Sadler
,
A. H.
, 1990, “
Cemented Internal Fixation for Supracondylar Femur Fractures in Osteoporotic Patients
,”
J. Orthop. Trauma
,
4
(
2
), pp.
151
157
.
8.
Curtis
,
R.
,
Goldhahn
,
J.
,
Schwyn
,
R.
,
Regazzoni
,
P.
, and
Suhm
,
N.
, 2005, “
Fixation Principles in Metaphyseal Bone - A Patent Based Review
,”
Osteoporosis Int.
,
16
(SUPPL. 2), pp.
S54
S64
.
9.
Jensen
,
T. T.
,
Overgaard
,
S.
, and
Mossing
,
N. B.
, 1990, “
Partridge Cerclene System for Femoral Fractures in Osteoporotic Bones With Ipsilateral Hemi/Total Arthroplasty
,”
J. Arthroplasty
,
5
(
2
), pp.
123
126
.
10.
Mears
,
D. C.
, 1999, “
Surgical Treatment of Acetabular Fractures in Elderly Patients With Osteoporotic Bone
,”
J. Am. Acad. Orthop. Surg.
,
7
(
2
), pp.
128
141
.
11.
Drew
,
T.
, and
Allcock
,
P.
, 2002, “
A New Method of Fixation in Osteoporotic Bone: A Preliminary Report
,”
Injury
,
33
(
8
), pp.
685
689
.
12.
King
,
T. J.
, and
Cebon
,
D.
, 1993, “
An Alternative to Screws for Plating Osteoporotic Bone
,”
J. Biomed. Eng.
,
15
(
1
), pp.
79
82
.
13.
Schandelmaier
,
P.
,
Partenheimer
,
A.
,
Koenemann
,
B.
,
Grün
,
O. A.
, and
Krettek
,
C.
, 2001, “
Distal Femoral Fractures and LISS Stabilization
,”
Injury
,
32
(SUPPL. 3), pp.
55
63
.
14.
Schütz
,
M.
,
Müller
,
M.
,
Krettek
,
C.
,
Höntzsch
,
D.
,
Regazzoni
,
P.
,
Ganz
,
R.
, and
Haas
,
N.
, 2001, “
Minimally Invasive Fracture Stabilization of Distal Femoral Fractures With the LISS: A Prospective Multicenter Study. Results of a Clinical Study With Special Emphasis on Difficult Cases
,”
Injury
,
32
(SUPPL. 3), pp.
48
54
.
15.
Frigg
,
R.
, 2003, “
Development of the Locking Compression Plate
,”
Injury
,
34
(SUPPL. 2), pp.
491
494
.
16.
Gautier
,
E.
, and
Sommer
,
C.
, 2003, “
Guidelines for the Clinical Application of the LCP
,”
Injury
,
34
(SUPPL. 2), pp.
63
76
.
17.
Miller
,
D. L.
, and
Goswami
,
T.
, 2007, “
A Review of Locking Compression Plate Biomechanics and Their Advantages as Internal Fixators in Fracture Healing
,”
Clin. Biomech.
,
22
(
10
), pp.
1049
1062
.
18.
Wagner
,
M.
, 2003, “
General Principles for the Clinical Use of the LCP
,”
Injury
,
34
(SUPPL. 2), pp.
31
42
.
19.
Melton
,
L. J.
, III
,
Johnell
,
O.
,
Lau
,
E.
,
Mautalen
,
C. A.
, and
Seeman
,
E.
, 2004, “
Osteoporosis and the Global Competition for Health Care Resources
,”
J. Bone Miner. Res.
,
19
(
7
), pp.
1055
1058
.
20.
Anglen
,
J.
,
Kyle
,
R. F.
,
Marsh
,
J. L.
,
Virkus
,
W. W.
,
Watters
,
W. C.
, III
,
Keith
,
M. W.
,
Turkelson
,
C. M.
,
Wies
,
J. L.
, and
Boyer
,
K. M.
, 2009, “
Locking Plates for Extremity Fractures
,”
J. Am. Acad. Orthop. Surg.
,
17
(
7
), pp.
465
472
.
21.
Gardner
,
M. J.
,
Evans
,
J. M.
, and
Dunbar
,
R. P.
, 2009, “
Failure of Fracture Plate Fixation
,”
J. Am. Acad. Orthop. Surg.
,
17
(
10
), pp.
647
657
.
22.
Haidukewych
,
G.
, and
Ricci
,
W.
, 2008, “
Locked Plating in Orthopaedic Trauma: A Clinical Update
,”
J. Am. Acad. Orthop. Surg.
,
16
(
6
), pp.
347
355
.
23.
Tan
,
S. L. E.
, and
Balogh
,
Z. J.
, 2009, “
Indications and Limitations of Locked Plating
,”
Injury
,
40
(
7
), pp.
683
691
.
24.
Eschbach
,
L.
, 2000, “
Nonresorbable Polymers in Bone surgery
,”
Injury
,
31
(SUPPL. 4), pp.
D22
D27
.
25.
Kurtz
,
S. M.
, and
Devine
,
J. N.
, 2007, “
PEEK Biomaterials in Trauma, Orthopedic, and Spinal Implants
,”
Biomaterials
,
28
(
32
), pp.
4845
4869
.
26.
Snow
,
M.
,
Thompson
,
G.
, and
Turner
,
P. G.
, 2008,
“A Mechanical Comparison of the Locking Compression Plate (LCP) and the Low Contact-Dynamic Compression Plate (DCP) in an Osteoporotic Bone Model,”
J. Orthop. Trauma
,
22
(
2
), pp.
121
125
.
27.
ASTM International, (2007), “ASTM Standard 543-07e1 Standard Specification and Test Methods for Metallic Medical Bone Screws,” http://www.astm.org/Standards/F543.htmhttp://www.astm.org/Standards/F543.htm
28.
Stromsoe
,
K.
,
Kok
,
W. L.
,
Hoiseth
,
A.
, and
Alho
,
A.
, 1993, “
Holding Power of the 4.5 mm AO/ASIF Cortex Screw in Cortical Bone in Relation to Bone Mineral
,”
Injury
,
24
(
10
), pp.
656
659
.
29.
Zdero
,
R.
,
Rose
,
S.
,
Schemitsch
,
E. H.
, and
Papini
,
M.
, 2007, “
Cortical Screw Pullout Strength and Effective Shear Stress in Synthetic Third Generation Composite Femurs
,”
J. Biomech. Eng.
,
129
(
2
), pp.
289
293
.
30.
Yánez
,
A.
,
Carta
,
J. A.
, and
Garces
,
G.
, 2010, “
Biomechanical Evaluation of a New System to Improve Screw Fixation in Osteoporotic Bones
,”
Med. Eng. Phys.
,
32
(
5
), pp.
532
541
.
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