CA1112803A - Internal fracture plate assembly with releasing feature - Google Patents

Internal fracture plate assembly with releasing feature

Info

Publication number
CA1112803A
CA1112803A CA315,489A CA315489A CA1112803A CA 1112803 A CA1112803 A CA 1112803A CA 315489 A CA315489 A CA 315489A CA 1112803 A CA1112803 A CA 1112803A
Authority
CA
Canada
Prior art keywords
plate
bone
set out
apparatus
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA315,489A
Other languages
French (fr)
Inventor
George W. Bagby
Original Assignee
George W. Bagby
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US93436178A priority Critical
Priority to US934,361 priority
Application filed by George W. Bagby filed Critical George W. Bagby
Application granted granted Critical
Publication of CA1112803A publication Critical patent/CA1112803A/en
Application status is Expired legal-status Critical

Links

Abstract

TITLE: INTERNAL FRACTURE PLATE ASSEMBLY WITH RELEASING FEATURE
Abstract of the Disclosure A fracture plate assembly for fixation of bone fractures during a normal period of healing, including a permanent plate having front and back faces. At least one aperture is formed through the plate between its front and back faces to receive a metal pin or screw which anchors the plate to the bone. A nonmetallic member is interposed between the plate, the pins or screws, and the bone. This is in the form of a layer or gasket of material that is deformable following a normal healing period to release the mechanical engagement between the plate and the pins or screws. A preferred form utilizes a layer of silicone rubber interposed between the plate and the bone.

Description

~ZS~3 As lnternal ~racturc platcs for holcling l)one -fractures have been developecl over a period of almost one hundre~ years, one of the major problems has been to create a p]ate strong enough to hold the bone members in place with or without an external cast, and at the same time to be of suitable size to be practical in its application. Too large a plate to produce the required strength might deprive the bone fragments of blood supply or make wound closure difficult. More recently, as alloys have improved, bone plates have been developed having both ~he desired strength properties and relatively small mass. However, this in turn has created a complication in the develo-pment of osteopenia in the bone area underlying the plate. Osteopenia is a term applied to the decreased calcification of density of bone. It is a condition of weakened bone, localized under a plate. Osteopenia constitutes a speci-fic instance of osteoporosis, which is a generalized term applied to abnormal rare factions of bone due to failure of the osteoblast to lay down bone matrix.
The development of osteopenia under the plate is a si~n that although the fracture has healed satisfactorily, it does not progress to regain its normal strength. This is explainable because the plate is so strong that it carries the load normally applied to the bone area, thus relieving the underlying bone of stress. The demand, according to Wolff's law for strength, is therefore taken from the bone and the bone does not have the normal physiological stimulus to become normally strong once more.
As a result of this weakening of the bone, fractures have actually recurred in the osteopenia site, either with the bone plate left in place or after it has been removed. It has been a practice with such rigid plates that produce this complication to remove the plate, returning the patient to crutches or some form of protection for a period of several weeks as the bone is allowed to gradually return to its normal strength. This requires a second operation to remove the plate, which should normally be avoided if possible. It also requires that the q~

patient return to a relatively sedentary existence while the bone regains its strength.
~lost approaches to this problem have involved attempts to reduce the modulus of elasticity in the bone plates, either through new alloys or resort to plates made of plastic resin. This in turn defeats the desire for a strong plate during the initial healing process.
The present apparatus has been developed so as to provide a supporting plate with adequate strength to allow the patient to be mobile ideally free of a cast, while establishing a release mechanism so that sometime six to twelve months following the fracture the plate would gradually be free of engagement with the bone. The gradual release of the plate allows the strength of the bone to gradually return by normal physiological processes. ~IUS, the reinforcement of the plate is provided during the normal healing period, but is gradually released thereafter, when it is no longer needed or desired.
Fig. 1 is a fragmentary view of a fractured bone with a plate according to this invention;
Fig. 2 is a sectional view taken along line 2-2 in Pig. l;
Fig. 3 is an enlarged fragmentary sectional view taken along line 3-3 in Fig. l;
Fig. 4 is a perspective view of the gasket shown in Figs. 1 through 3;
Fig. 5 is a fragmentary view of a fractured bone with a com-pression plate;
Fig. 6 is a sectional view taken along line 6-6 in Fig. 5;
Fig. 7 is an enlarged fragmentary sectional view taken along line 7-7 in Fig. 5;
Fig. 8 is a perspective view of the gasket shown in Figs. 5 through 7;
Fig. 9 is an enlarged sectional view similar to Fig. 2, show-ing another form of the invention;
Fig. 10 is an enlarged sectional view similar to Fig. 2, showing another modification of the invention;
Fig. ll is a perspective view illustrating an encapsulated plate;
Fig. 12 is a sectional view similar to Fig. 6, illustrating use of the plate shcwn in Fig. ll; and Fig. 13 is a sectional view similar to ~ig. 7, illustrating the plate shcwn in Fig. ll.
The internal fracture plate assembly shcwn in the drawings ; is directed at avoiding the complication of osteopenia under a bone plate after the fracture of the bone has healed. It can be utilized in conjunction ~ith conventional bone plates, whether of the compression or noncompression type. A release means in the fo~m of a nonmetallic layer of material is interposed between the plate, and the fractured bone, or between the plate and the screws which hold it to the bone.
The interposed layer of material must be designed so as to maintain the desired campressive engagement between the plate and screws during the normal healing period, and to gradually release such compressive engagement subsequent to the normal healing period, leaving the per-manent screws and plate adjacent to the bone in a loosened mechanical interconnection.
In the embodiment shcwn in Figs. 1 through 4, the bone frag-ments lO and ll are illustrated with a transverse fracture 12. m e bone has been reset and reinforced by mechanical interconnection to a con-ventional simple metal bone plate 13 held in place by six recessed screws 14 inserted through complementary apertures formed between the opposed faces of the plate 13. The details of such plates and screws are well known in orthopedic surgery and are not necessary to an understanding of the present disclosure.
Interposed between plate 13 and the bone fragments lO, ll is a release means, shown as a layer of silicone rubber, this layer being designated by the reference n~meral 15. The layer 15 presents a "gasket"

covering the bone surfaces overlaid by the plate. The layer 15 is ~lZ~3~)3 preferably fonmed frcm a continuous sheet being properly apertured to receive the screws 14. Hcwever, the layer 15 might alternately be in the form of smaller individual sections or "washers" surrounding each of the screws 14 beneath the plate 13.
Initial experimentation has shcwn that suitable mechanical release of the bone plate can be achieved by use of an interposed layer of "Silastic" (Trademark) silicone rubber, produced and sold by Dow Com ing Corporation of Midland, Michigan. A layer of "Silastic" silicone rubber sheeting of the type used for surgical implants and having a thickness of 0.040 to 0.080 inches has been found to evidence significant release of the bone plate four months after its surgical installation.
When the plate 13 is secured to the bone bv the screws 14, it is important that there be compressive engagement between the plate and screws in order to immobilize the bone during the healing period.
Because of the compressible layer of material 15, it is desirable to measure the tor~ue applied to each screw 14, although the screws 14 can be driven into the bone by hand without mechanical measurement of torque.
It is preferable that each conventional screw 14 be applied with about 14 inch-pounds of torque. By measuring the torque applied to the screws, even compression of the layer 15 can be accomplished along the full length of the plate 13.
The layer 15 has two actions which are desirable in this usage. First, the compressible material is resilient and has an initial resistance to compression set, maintaining its elastcmeric properties over the usual period in which healing of the bone occurs. Thus, should movement or use of the limb tend to slightly loosen the compressive engagement between the plate 13 and screws 14, the resiliency of layer 14 will as Æ e that such ccmpressive engagement is maintained by the resultant expansion of the laver 15. Hawever, the layer of material eventually exhibits reversion - softening, loss of tensile strength, and high ccmpression set - when maintained in close confingement under elevated temperatures in the normal range of body temperatures in which ~128~3 the plate 13 would be used. The "Silastic" silicone rubber sheetingexhibits both of these tendencies in a time frame corresponding to the healing period of a fracture in the body. The exact period over which reversion occurs is variable by control of the material camposition and choice of curing temperatures in relation to normal body temperatures.
The release means or layer of material 15 can either be bonded or attached to the underside of the plate 13 or can be installed on the bone as a separable element. Bonding between the plate 13 and layer lS
does not appear to be of structural importance, although it might be of value in simplifying the installation procedures.
Figs. 5 through 8 show a second embodiment wherein the bone fragments 40 and 41 are illustrated with a transverse fracture 42. The bone has been reset and reinforced by a mechanical interconnection to a campression bone plate 43 held in place by six recessed screws 14 inserted through slotted apertures formed between the faces of plate 43. The illustrated plate is known ccmmercially as the "Bagby Compression Plate".
One example of this plate, made of Vitallium ~Trademark), is manufactured by Howmet Corporation of Rutherford, New Jersey. &ch compression bone plates have slotted apertures including distal ends located tcward the plate ends to create campresssive opposition of fractures by engagement of the screws at the distal ends of the slotted apertures. An exemplary plate is 2.2 to 3.9 inches in length and has either four or six slots for reception of conventional screws. An example of a bone screw used in conjunction with this plate is the "Duo-Drive" bone screws, also manufactured by Hcwmet Corporation and identified as Catalog No. 6646.
These screws are 5/32 inches in diameter. A similar plate in stainless steel is also available from Zimmer-U.S.A. of Warsaw, Indiana~ Titanium plates might also ~e used.
As before, a layer of "Silastic" silicone rubber described above is interposed between plate 43 and the bone fragments 40, 41.

Layer 45 presents a "gasket", which is shown in Fig. 8. It covers the bone surfaces overlaid by the plate 43~

The interposition of the release means or layer 45 is partic-ularly advantageous with this type of compressive bone plate. There is concern that the compressive forces which are exerted on the fracture line 42 vary during the healing period as the screws 44 loosen slightly in the bone structure. The silicone rubber, having a strong initial resistance to compression set, retains its elastomeric properties during the normal healing period. Then as the effect of body temperatures on the rubber material results in the exhibition of reversion under the close confinement between the plate 13 and the bone, the strength and resiliency of the material will be reduced, thereby releasing or sub-stantially reducing the compressive engagement between the screws 44and plate 43.
Fig. 9 shcws a m3dification of the device, with the bone plate 23 being located in its usual position in direct contact with the bone fragment 20. However, a release means shcwn as a layer of "Silas-tic" silicone r~bber 25 is used as a lining about the apertures that receive each screw 24. After the screws 24 have been turned dcwn into the bone 20, the layer of material 25 will again gradually exhibit rever-sion and ultimately release the mechanical connection between the plate 23 and the screws 24.

Fig. 10 shcws another modification, wherein the release means or layer of silicone rubber 35 is coated about the enlarged head fonmed integrally with the threaded shank of each screw 34. Again, as the screw 34 is inserted through the apertures in the plate 33 and fixed to the bone 30, there will be an interposed layer of material subject to reversion to gradually permit the plate 33 to be freed frcm the screws 34.

It is important to note that the penmanent plate and the per-manent screws are never entirely freed from the bone. Instead, the plate 23 will be loosely located by the screws 34, which will remain securely attached to the bone fragments at each side of the healed fracture. m is will eliminate any possibility of the plate being carried or m~ved from ~.~2~3 the healed fracture zone. In actual practice, the plate will be enveloped within tissue that will grow about it during the healing process and no actual movement will occur between the plate and the screws. However, the loading stresses upon the bone will no longer be transferred to the plate after healing, which will permit the bone to react physiologically in its normal fashion to regain all or at least a substantial part of its original strength.
Figs. 11, 12 and 13 illustrate another form of the bone plate, wherein a conventional plate 50 is encapsulated o~ coated by a release means shcwn as silicone rubber material of the type described in detail above. The plate 50 can be either a ccmpression plate or a conventional plate of the non-compressive type. The layer of silicone rubber material shcwn at 51 covers all of the exterior plate surfaces including the exposed surfaces of the apertures or slots formed through the plate for reception of bone screws. The use and operation of the modified plate is basically as described above, with the yieldable material surface being inte osed between both the plate 50 and the bone as well as between plate 50 and each screw.
Variols detailed modifications might be made with respect to this develoFment without deviating from the general concept of a releas-able mechanical interconnection between the plate and bone. For these reasons, the follcwing claims are intended as definitions of the inven-tion described herein.

Claims (12)

The embodiment of the invention, in which an exclusive property or privilege is claimed, is defined as follows:
1. An internal fracture plate assembly with releasing feature, said assembly being adapted to reinforce bone fragments during healing of a bone fracture in a live body, comprising:
a permanent structural plate of rigid material capable of withstanding normal bone loadings when fixed to bone fragments in a position overlying said fracture;
said plate having a plurality of apertures formed through it;
screw means for threadably engaging the bone fragments while said screw means is in engagement with the boundaries of the apertures formed through the plate for operatively securing the plate to the bone fragments by compressive engagement between the screw means and the plate;
and release means in the form of a layer of material in con-tact with said plate for maintaining the compressive engagement between the screw means and the plate during the normal healing period and for gradually releasing such compressive engagement subsequent to the normal healing period for the fracture, leaving the screw means and plate adjacent to the bone in a loosened mechanical interconnection.
2. The apparatus set out in claim 1 wherein the layer of material is adapted to be interposed between the plate and the bone fragments.
3. The apparatus as set out in claim 1 wherein the layer of material is adapted to be interposed between the plate and said screw means.
4. The apparatus as set out in claim 1 wherein the layer of material has the characteristic of exhibiting reversion when maintained in close confinement at a normal range of body temperature for said body.
5. The apparatus as set out in claim 1 wherein the plate is a compression bone plate having slotted apertures including distal ends located toward the plate ends to create compressive opposition of fractures by engagement of said screw means at the distal ends of the slotted apertures.
6. The apparatus set out in claim 1 wherein said screw means comprises:
a threaded shank;
an enlarged integral head at one end of said shank having outwardly facing surface areas for engagement within the apertures of said plate;
said release means being bonded to the outwardly facing sur-face areas of said head.
7. The apparatus set out in claim 1 wherein said plate comprises:
a metal member having a surface adapted to conform longi-tudinally to the bone fragments;
a plurality of apertures formed perpendicularly to said surface;
said release means being in contact with said surface.
8. An apparatus as set out in claim 7 wherein said release means is fixed to said surface of the member.
9. An apparatus as set out in claim 7 wherein said release means is fixed to the plate and covers the surface areas of said plate apertures.
10. An apparatus as set out in claim 7 wherein said release means encapsulates said member.
11. An apparatus as set out in claim 1 wherein the release means comprises a layer of silicone rubber material.
12. An apparatus as set out in claim 1 wherein the release means comprises a layer of "Silastic" silicone rubber material.
CA315,489A 1978-08-17 1978-10-31 Internal fracture plate assembly with releasing feature Expired CA1112803A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US93436178A true 1978-08-17 1978-08-17
US934,361 1978-08-17

Publications (1)

Publication Number Publication Date
CA1112803A true CA1112803A (en) 1981-11-24

Family

ID=25465420

Family Applications (1)

Application Number Title Priority Date Filing Date
CA315,489A Expired CA1112803A (en) 1978-08-17 1978-10-31 Internal fracture plate assembly with releasing feature

Country Status (1)

Country Link
CA (1) CA1112803A (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4838252A (en) * 1985-08-30 1989-06-13 Synthes Osteosynthetic compression plate
US5053036A (en) * 1987-11-03 1991-10-01 Synthes (U.S.A.) Point contact bone compression plate
US5487741A (en) * 1992-11-16 1996-01-30 Taguchi Medical Co., Ltd. Bone plate
US8147493B2 (en) 2003-09-08 2012-04-03 Synthes Usa, Llc Bone-fixation device
US8246661B2 (en) 2003-10-30 2012-08-21 Synthes Usa, Llc Bone plate
US8574268B2 (en) 2004-01-26 2013-11-05 DePuy Synthes Product, LLC Highly-versatile variable-angle bone plate system
US8758346B2 (en) 2009-09-14 2014-06-24 DePuy Synthes Products, LLC Variable angle compression plate
US8845698B2 (en) 2003-08-26 2014-09-30 DePuy Synthes Products, LLC Bone plate
US10231768B2 (en) 2003-05-30 2019-03-19 DePuy Synthes Products, Inc. Methods for implanting bone plates
US10335211B2 (en) 2016-03-18 2019-07-02 DePuy Synthes Products, Inc. Highly-versatile variable-angle bone plate system

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4838252A (en) * 1985-08-30 1989-06-13 Synthes Osteosynthetic compression plate
US5053036A (en) * 1987-11-03 1991-10-01 Synthes (U.S.A.) Point contact bone compression plate
US5487741A (en) * 1992-11-16 1996-01-30 Taguchi Medical Co., Ltd. Bone plate
US10231768B2 (en) 2003-05-30 2019-03-19 DePuy Synthes Products, Inc. Methods for implanting bone plates
US9295505B2 (en) 2003-08-26 2016-03-29 DePuy Synthes Products, Inc. Bone plate
US8876873B2 (en) 2003-08-26 2014-11-04 DePuy Synthes Products, LLC Bone plate
US8852245B2 (en) 2003-08-26 2014-10-07 DePuy Synthes Products, LLC Bone plate
US8845698B2 (en) 2003-08-26 2014-09-30 DePuy Synthes Products, LLC Bone plate
US8147493B2 (en) 2003-09-08 2012-04-03 Synthes Usa, Llc Bone-fixation device
US8246661B2 (en) 2003-10-30 2012-08-21 Synthes Usa, Llc Bone plate
US8574268B2 (en) 2004-01-26 2013-11-05 DePuy Synthes Product, LLC Highly-versatile variable-angle bone plate system
US9314284B2 (en) 2004-01-26 2016-04-19 DePuy Synthes Products, Inc. Highly-versatile variable-angle bone plate system
US8758346B2 (en) 2009-09-14 2014-06-24 DePuy Synthes Products, LLC Variable angle compression plate
US10335211B2 (en) 2016-03-18 2019-07-02 DePuy Synthes Products, Inc. Highly-versatile variable-angle bone plate system

Also Published As

Publication number Publication date
CA1112803A1 (en)

Similar Documents

Publication Publication Date Title
US3659595A (en) Compensating plates for bone fractures
US3477429A (en) Extra-cortical clamp with detachable tensioning tool for internal fixation of bone fractures
JP3009232B2 (en) Hip intramedullary screw
US9492215B2 (en) Method of osteosyntheses or arthrodeses of two- bone parts, in particular of the hand and / or foot
US5873848A (en) Orthopedic brace
US4756689A (en) Connecting devices
Claes The mechanical and morphological properties of bone beneath internal fixation plates of differing rigidity
US5230699A (en) Phalanx splint
US5954769A (en) Surgical drill positioning guide
US6319255B1 (en) Prophylactic implant against fracture of osteoporosis-affected bone segments
US5527310A (en) Modular pelvic fixation system and method
US5013313A (en) Device for fixation of part on a support, especially of an implant on a bone
US5474553A (en) System for setting tubular bone fractures
CA2158890C (en) Spherical washer for use with a bone screw
US6270500B1 (en) Device for postoperative fixation back into the cranium of a plug of bone removed therefrom during a surgical operation
JP2511564B2 (en) Dynamic external fixation device
EP0486483A1 (en) Intramedullary intertrochanteric fracture fixation appliance and fitting device
US4746293A (en) Connecting devices
US3741205A (en) Bone fixation plate
CN1268295C (en) Fixation device
US6146384A (en) Orthopedic fixation device and method of implantation
US5803924A (en) External fixator
AU626377B2 (en) Apparatus for treating a fracture
US4655203A (en) Bone fracture surgical device
US5607430A (en) Bone stabilization implant having a bone plate portion with integral cable clamping means

Legal Events

Date Code Title Description
MKEX Expiry