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8/10/2019 Motec Wrist Joint Prosthesis Brochure
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Motec
Wrist Joint Prosthesis
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MotecWrist Joint Prosthesis
The MotecWrist Joint Prosthesis has been designed specifically
for high demand patients, with the objective to provide a strong,
stable, mobile and pain free wrist while minimizing the risk of
luxation, loosening and osteolysis.
Fixation is achieved by threaded implants made of titanium alloy,
blasted and coated with Bonit, which promotes osseointegration
between titanium oxide and bone.
The articulation is modular and can be configured depending on
surgeon and patient preference, either with CoCrMo articulating on
ceramic coated CoCrMo or CoCrMo articulation on carbon fiber
reinforced PEEK Motis.
Each component is available in different sizes, to allow firm seating
and close replication of the patients normal range of motion.
IndicationsThe system is indicated in cases of pain and reducedmotion in the wrist caused by:
ll Rheumatoid arthritis
ll Degenerative arthritis (osteoarthritis)
ll Post-traumatic arthritis (secondary arthritis) after failed treatment of:
l Scaphoid fractures
l Scapholunate dissociation
l
Kienbcks disease of the lunate
l Fracture dislocation of the wrist
l Intra-articular fractures of the distal radius
l Intercarpal fusions
l Proximal row carpectomy
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Features and benefitsThe Motec Wrist Joint Prosthesis has the following
features and benefits:
l
l Modular design
ll State-of-the-art articulation
ll Limited bone resection
ll Preserves soft tissue and ligament structures
ll Improved short term fixation
ll Optimized long term fixation through osseointegration
ll Compatible wrist arthrodesis solution
l
l Straightforward operative procedure
Patent number SE 528 545 C2
Patent application PM 30191 SE 00
Patent application PM 30191 SE 01
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Modular design
The Motec Wrist Joint Prosthesis is completely modular in its
design to give the surgeon maximum flexibility in matching the
anatomy of the patient.
ll The primary fixation in bone is achieved by threaded
implants which are available in different sizes.
ll The head component is available with several different
neck lengths to enable fine tuning of the joint tension.
ll The cup component is available in different materials
depending on surgeon and patient preference.
See page 6-7 for details.
l
l In case of failure of the prosthesis due to loosening of
the Metacarpal Threaded Implant, continuing pain orabnormal soft tissue balance, the fully compatible Motec
Wrist Joint Arthrodesis solution is available as a salvage
procedure. See page 12 for details.
Metacarpal Threaded Implant
is available in two diameters and in
six different lengths.
The Metacarpal Head Implant
is available in two diameters and in
four neck lengths allowing the surgeon
to adjust the tension of the joint.
The Radius Threaded Implant is
available in three different sizes to allow
matching of the radius anatomy.
The Radius Cupis available in
CFR-PEEK as well as in ceramic
coated CoCrMo.
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Ball-and-socket design
l
l Allows 136160 range of motion (ROM).
l
l Increased stability, especially in patients with poor soft
tissue.
ll The ball and socket articulation prevents loosening of the
osseointegrated implants by preventing transfer of
rotational forces.
ll Can resist forces that cause luxation (no luxation have
been reported in more than 400 patients).
Closely replicates the anatomical
center of rotationThe anatomical center point of rotation, in both radial-ulnar
deviation and flexion-extension is located in the proximal part of
the head of the capitate, near the lunate.
The Motec Wrist Joint Prosthesis places the center of rotation
very close to the anatomical center point. (Ref. 3)
Centerpoint of Motec
Wrist Joint Prosthesis
Anatomical centerpoint
Center point of the Motec Wrist Joint Prosthesis
... rotation occurs about a fixed
axis located within the head of the
capitate, and the location of each
axis is not changed by the position
of the hand in either plane.
Youm Y, McMurthy RY, Flatt AE, Gillespie TE.
An experimental study of radial-ulnardeviation and flexion-extension.
J Bone Joint Surg Am. 1978 Jun;60(4):423-31
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Motis is a trademark of Invibio Biomaterial Solutions.
The Radius Cupis made from carbon fiber
reinforced PEEK, specifically developed for
bearing applications against hard counterfaces.
State-of-the-art articulation
Metal on carbon fiber
reinforced PEEKThe Motec Wrist Joint Prosthesis also offers an articulation
option where the Metacarpal Head is made from CoCrMo,
and the Radius Cup is made from carbon fiber reinforced
polyetheretherketone (PEEK Motis). PEEK Motis has been
specifically developed for bearing applications against hard
counterfaces, such as CoCrMo.
Benefits of carbon fiber reinforced PEEK
l
l Exceptional wear performance supported by research and
published data
ll Extensive testing to ISO 10993 standards demonstrates
biocompatibility and biostability for use in long term
implant applications
ll The thin components allows preservation of bone
ll Reduced stress shielding and improved stress distribution
ll An alternative to metal-on-metal combinations, which
eliminates metal ion concerns
l
l Demonstrated resistance to gamma sterilization(does not become brittle over time like polyethylene)
Pin-on-plate screening of polymer against hard counterface
combinations.
Source: Invibio Biomaterial Solutions
MOTIS- HC CoCrMo
UHMWPE- CoCrMo
CFR-PEEK represents an alternative load-bearing material because of its superior
mechanical and chemical behaviour without any increased biological activity of the
wear particles, compared with a standard load-bearing material.
Utzschneider S, Becker F, Grupp TM, Sievers B, Paulus A, Gottschalk O, Jansson V.
Inflammatory response against different carbon fiber-reinforced PEEK wear particles compared with UHMWPE in vivo.
Acta Biomater. 2010 Nov;6(11):4296-3046
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The Radius Cupis made from a CoCrMo alloy
coated with a ceramic CrN coating for extended wear
performance and improved biocompatibility.
Metal on ceramic coated metal
The articulation components have been optimized for
biocompatibility and minimized wear rate, to reduce the risk
of osteolysis typically associated with polyethylene and
conventional metal-on-metal bearings.
The Motec Wrist Joint Prosthesis offers an articulation option
where the Metacarpal Head is made of cobalt chromium
molybdenum alloy (CoCrMo) and the Radius Cup is made of
CoCrMo coated with ceramic chromium nitride (CrN).
Benefits of metal on ceramic coated metal
l
l Wear rate is reduced with up to 90% compared toconventional CoCrMo articulation
l
l In over 400 patients, with up to 12 years of follow-up,
no cases of loosening caused by osteolysis have been
reported
ll The thin components allows preservation of bone
ll Reduced stress shielding and improved stress
distribution
ll Demonstrated resistance to gamma sterilization
(does not become brittle over time like polyethylene)
ll Metal ions released in blood have been monitored in
Motec patients at two independent hospitals. The mean
follow up time is 4.6 years. The data shows that the
mean amount of cobalt and chromium in blood was 0.7
g/l. According to MHRA guidelines, the levels of metal
ions released in the blood should not exceed 7ug/L for
metal-on-metal hip prosthesis. (Ref. 19)
Total wear loss of conventional CoCrMo on CoCrMo vs.
CoCrMo on CrN.
Source: IonBond AG
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Limited bone resection
ll Saves joint space
The ball-and-socket components are very much
less bulky than conventional polyethylene on metal
components. This lack of bulk results in minimal bone
resection, specifically the lunate, two thirds of the
scaphoid and the cartilage of the CMC-3 joint. In some
cases the tip of the radial styloid and/or the triquetrum
need to be removed as well.
ll Compatible arthrodesis
The limited bone resection ensures that a secondary
arthrodesis procedure can be performed without
problems. This procedure can also be further simplified
by the Motec Wrist Arthrodesis device, which utilizes the
existing threaded implants for fixation whenever possible.
(See page 12 for details)
ll Maintained joint stability
Most of the soft tissue and ligament structures between
the radius, ulna and the carpal bones are preserved,
maintaining the natural stability of the wrist. The distal
radio-ulnar joint is unaffected by the presence of the
wrist prosthesis. The peripheral rim of the distal radius is
preserved, along with its important ligamentous and soft
tissue attachments.
Preserves soft tissue and ligament structures
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ll Immediate primary fixation in cortical bone
Immediate primary fixation is achieved by threaded
implants. The design of the threaded implants has been
optimized for maximum bone purchase.
ll Cementless fixation
The cementless fixation of the components simplifies
the surgical procedure and eliminates potential cement
related complications.
ll Promoting bone formation
The conical shape distributes the forces evenly into the
cancellous and cortical bone, thereby promoting bone
formation.
ll Prevents fractures
The non-threaded distal 1/3 of the threaded implants
prevents fractures by being non-threaded, especially at
the isthmus in the third metacarpal. The rounded tip of
the threaded implants reduces stress concentration.The threads of the conical Radius Threaded Implant engage
into the cortical bone, volarly and dorsally, preventing the
implant from sinking.
The threads of the conical Metacarpal Threaded Implant
engage into the cancelleous and cortical bone of the capitate
and the third metacarpal, ensuring a stable fixation. Fusion of
the midcarpal bones is only needed between the capitate and
the third metacarpal.
Improved short term fixation
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The implants are coated with a Bonit layer of 20-30 m.
ll Optimal blasting of titanium alloy implants improves
long term fixation and osseointegration (Ref. 4,17).
The titanium surface is blasted with extra pure Al2O3
using a specific technique and to a specific roughness
value to maximize the bone ingrowth.
ll The titanium alloy threaded implants are coated with
Bonit, a resorbable calcium phosphate combination with
proven osteoconductive properties, improving long term
fixation.
Without Bonit
Without Bonit there would be a significant reduction in stability
2-5 weeks postoperatively. This dip coincides with the release
of the plaster, thereby increasing the risk of loosening.
With Bonit
Bonit promotes early formation of new bone, thereby reducing
the risk of loosening. (Ref. 5)
Secondary
stability
(new bone)
Stabilitydip
Primary
stability
(old bone)
Total stability
Secondary
stability(new bone)
Reducedstability
dipTotal stability
Primary
stability(old bone)
Bonitis a registered trademark of DOT GmbH.
Optimized long term fixation and osseointegration
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In vivo biomechanical comparison
of Bonit versus HydroxyapatiteTitanium screws coated with Bonit and screws coated with
hydroxyapatite (HA) were implanted in the proximal tibia of a
rabbit, for the purpose of comparing the increase of fixation
over time.
The fixation of the Bonit coated screws increased significantly
over time (6 to 12 to 52 weeks) whereas the screws coated
with HA showed no increase in fixation after 6 weeks.
After 52 weeks, the Bonit layer was fully resorbed (Ref. 6).
HA coating
52 weeksIn contrast to the fully resorbable Bonit,
the HA-layer and particles are loosening
from the titanium surface. Giant cell,
macrophages are visible.
Problems with long term fixation using HA
coating on implants have also been shown
in a thesis by M. Rkkum (Ref. 18).
52 weeks12 weeks
The Bonit layer is partly resorbed. The Bonit layer is no longer visible. The Bonit layer is fully resorbed.
Osseointegration has taken place
between the titanium oxide layer and
bone.
Bonit
6 weeks
Implant in black and bone in purple.
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Motec Wrist Joint Arthrodesis
In case of failure of the prosthesis due to loosening
of the Metacarpal Threaded Implant, continuing
pain or abnormal soft tissue balance, the fully
compatible Motec Wrist Joint Arthrodesis
solution is available as a salvage procedure.
The Motec Wrist Joint Arthrodesis has been
developed to overcome the problem of soft
tissue irritation and thereby minimize the need for
unnecessary implant removal procedures. It has
been designed to use the existing osseointegrated
implants when possible.
The angle of the Motec Wrist Joint Arthrodesis can be
adjusted to 0, 15 and 30 for flexibility.
The Motec Wrist Joint Arthrodesis can also be used
as a primary solution for wrist fusion.
Radius Connectoris fixedto the Radius Threaded Implant
by a Locking Screw.
A Metacarpal Nail or a MetacarpalTaper is connected to the Radius
Connector by a pair of small Screws.
The Metacarpal Nailis used whenthe Metacarpal Threaded Implant has to
be removed due to loosening.
Metacarpal taperis used when the Metacarpal
Threaded Implantis fixed in the metacarpal bone.
Fully compatible salvage procedure
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Case
Pre-op. Male 66 years old. Previously operated with lunatum
silicon prosthesis. AROM 98. Jamar: 22 kg grip strength in
the operated hand and 38 kg in the other hand.
Post-op.
3 years post-op. Jamar: 36 kg grip strength. AROM 124. The
patient has regained his grip strength, has no pain and is very
pleased.
ResultsThe overall clinical results achieved with the Motec Wrist Joint
Prosthesis are very promising. In the end of 2012, more than
400 patients have been operated. The longest follow-up time is
twelve years.
Promising one- to six-year results with the
Motec wrist arthroplasty in patients with
post-traumatic osteoarthritis
Reigstad O, Ltken T, Grimsgaard C, Bolstad B, Thorkildsen R,
Rkkum M.
J Bone Joint Surg Br. 2012 Nov;94(11):1540-5
Abstract
The Motec cementless modular metal-on-metal ball-and-socket
wrist arthroplasty was implanted in 16 wrists with scaphoid
nonunion advanced collapse (SNAC; grades 3 or 4) and 14 wrists
with scapholunate advanced collapse (SLAC) in 30 patients (20
men) with severe (grades 3 or 4) post-traumatic osteoarthritis of
the wrist. The mean age of the patients was 52 years (31 to 71).
All prostheses integrated well radiologically. At a mean follow-up
of 3.2 years (1.1 to 6.1) no luxation or implant breakage occurred.
Two wrists were converted to an arthrodesis for persistent
pain. Loosening occurred in one further wrist at five years
postoperatively. The remainder demonstrated close boneimplant
contact. The clinical results were good, with markedly decreased
Disabilities of the Arm Shoulder and Hand (DASH) and pain scores,
and increased movement and grip strength. No patient used
analgesics and most had returned to work.
Good short-term function was achieved using this wrist
arthroplasty in a high-demand group of patients with post-traumatic
osteoarthritis.
Kaplan-Meier survival curve
Time (years)
6543210
Cumulativesurviva
l
1.0
0.8
0.6
0.4
0.2
0.0
CensoredSurvival function
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ReferencesArticles
1. Reigstad O, Ltken T, Grimsgaard C, Bolstad B,
Thorkildsen R, Rkkum M. Promising one- to six-year
results with the Motec wrist arthroplasty in patients withpost-traumatic osteoarthritis. J Bone Joint Surg Br. 2012
Nov;94(11):1540-5.
2. Reigstad A, Reigstad O, Grimsgaard C, Rkkum M. New
concept for total wrist replacement. J Plast Surg Hand
Surg. 2011 Jun;45(3):148-56.
3. Youm Y, McMurthy RY, Flatt AE, Gillespie TE. Kinematics
of the wrist. I. An experimental study of radial-ulnar
deviation and flexion-extension. J Bone Joint Surg Am.
1978 Jun;60(4):423-31.
4. Lundborg G, Besjakov J, Brnemark PI.Osseointegrated
wrist-joint prostheses: a 15-year follow-up with focus on
bony fixation. Scand J Plast Reconstr Surg Hand Surg.
2007;41(3):130-7.
5. Reigstad O, Franke-Stenport V, Johansson CB,
Wennerberg A, Rkkum M, Reigstad A. Improved bone
ingrowth and fixation with a thin calcium phosphate coating
intended for complete resorption. J Biomed Mater Res B
Appl Biomater. 2007 Oct;83(1):9-15.
6. Reigstad O, Johansson C, Stenport V, Wennerberg A,
Reigstad A, Rkkum M.Different patterns of bone fixation
with hydroxyapatite and resorbable CaP coatings in the
rabbit tibia at 6, 12, and 52 weeks. J Biomed Mater Res B
Appl Biomater. 2011 Oct;99(1):14-20.
7. Barbour PS, Stone MH, Fisher J.A hip joint simulator
study using simplified loading and motion cycles
generating physiological wear paths and rates. Proc Inst
Mech Eng H. 1999;213(6):455-67.
8. Firkins PJ, Tipper JL, Ingham E, Stone MH, Farrar R,
Fisher J.Influence of simulator kinematics on the wear
of metal-on-metal hip prostheses. Proc Inst Mech Eng H.2001;215(1):119-21.
9. McKellop H, Park SH, Chiesa R, Doorn P, Lu B,
Normand P, Grigoris P, Amstutz H.In vivo wear of
three types of metal on metal hip prostheses during two
decades of use. Clin Orthop Relat Res. 1996 Aug;(329
Suppl):S128-40.
10. Ingham E, Fisher J. Biological reactions to wear debris
in total joint replacement. Proc Inst Mech Eng H.
2000;214(1):21-37. Review.
11. Fisher J, Hu XQ, Tipper JL, Stewart TD, Williams
S, Stone MH, Davies C, Hatto P, Bolton J, Riley M,
Hardaker C, Isaac GH, Berry G, Ingham E.An in vitro
study of the reduction in wear of metal-on-metal hip
prostheses using surface-engineered femoral heads. Proc
Inst Mech Eng H. 2002;216(4):219-30.
12. Scholes SC, Unsworth A. Pitch-based carbon-fibre-
reinforced poly (ether-ether-ketone) OPTIMA assessed
as a bearing material in a mobile bearing unicondylar knee
joint. Proc Inst Mech Eng H. 2009 Jan;223(1):13-25.
13. Utzschneider S, Becker F, Grupp TM, Sievers B, Paulus
A, Gottschalk O, Jansson V.Inflammatory response
against different carbon fiber-reinforced PEEK wear
particles compared with UHMWPE in vivo. Acta Biomater.
2010 Nov;6(11):4296-304.
14. Scholes SC, Unsworth A. Wear studies on the likely
performance of CFR-PEEK/CoCrMo for use as artificial
joint bearing materials. J Mater Sci Mater Med. 2009
Jan;20(1):163-70.
15. Kabir K, Schwiesau J, Burger C, Pflugmacher R, Grupp
T, Wirtz DC. Comparison of Biological Response to
UHMWPE and CFR-PEEK Particles in Epidural Space.
Universittsklinikum Bonn, Department for Orthopaedics
and Trauma Surgery, Bonn, Germany, Aesculap AG
Research & Development, Tuttlingen, Germany. 2011.
16. Grupp TM, Utzschneider S, Schrder C, Schwiesau J,
Fritz B, Maas A, Blmer W, Jansson V.Biotribology of
alternative bearing materials for unicompartmental knee
arthroplasty. Acta Biomater. 2010 Sep;6(9):3601-10.
Erratum in: Acta Biomater. 2012 Apr;8(4):1659.
Theses
17. Wennerberg A.On surface roughness and implant
incorporation. Department of Biomaterial/Handicap
Research, Gteborg, Sweden. 1996.
18. Rkkum M. On Late Complications With Ha Coated Hip
Arthroplasties, Department of Biomaterials/Handicap
Research, Institute for Surgical Sciences, Faculty of
Medicine, University of Gteborg, Gteborg, Sweden and
Orthopaedie University Clinic, National Hospital, Oslo,
Norway, Gteborg 2001.
Internal document
19. Metal ions released in blood.
P125-TF-07.2-rev1 Summary of validation.
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Pre-operative planningIt is recommended as an important part of the preoperative
planning process that the surgeon should be familiar with
the anatomy of the carpal area with special attention to the
neuromuscular system.
Indications
The system is indicated in cases of pain and reduced
motion in the wrist caused by:
ll Rheumatoid arthritis
ll Degenerative arthritis (osteoarthritis)
ll Post-traumatic arthritis (secondary arthritis)
after failed treatment of:
l Scaphoid fractures
l Scapholunate dissociation
l Kienbcks disease of the lunate
l Fracture dislocation of the wrist
l Intra-articular fractures of the distal radius
l Intercarpal fusions
l Proximal row carpectomy
Contraindications
The physicians education, training and professional judgement
must be relied upon to choose the most appropriate device
and treatment. Conditions presenting an increased risk
of failure include:
ll Previous open fracture or infection in the joint.
ll Physical interference with another prosthesis
during implantation or use.
ll Inadequate skin, bone or neurovascular status.
ll Irreparable tendon system.
ll Inadequate bone stock or soft tissue coverage.
ll Any mental or neuromuscular disorder which would
create an unacceptable risk or complication during
the postoperative care.
ll Other medical or surgical conditions which would
preclude the potential benefit of surgery.
Surgical technique1. Position the patient
The patient is placed supine on the operating table with the arm
abducted 90 degrees over an arm table. The C-arm is placed at
the end of the operating table.
Either axillary block or general anaesthesia is recommended.
Preoperative antibiotics are recommended.
A tourniquet is applied and inflated. The patients arm is
prepared and draped according to common practice.
Note! The following images are from a cadaver specimen.
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2. Make incision
A 60 mm dorsal incision is made and the extensor retinaculum
is exposed.
The extensor retinaculum is split at the Listers tubercle.
The two radial wrist extensors and the long thumb extensor
are held radially and the finger extensors ulnarly. The capsule is
freed dorsally.
The capsule is opened.
There is an alternative surgical approach, called the Proximal
Flap Procedure, described by M.D. Greg Packer. A step-
by-step description of this approach can be obtained from
Swemac separately (P125-28-2-20130118).
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3. Bone resection
The lunate and two thirds of the scaphoid are removed.
Preserve the resected bones on a sterile tissue to allow
collection of bone chips if needed.
Two thirds of the scaphoid is removed with a 30 degree volar
angle. This preserves blood supply, retains the volar ligaments
and prevents impingement between the radial styloid and the
remaining volar scaphoid.
4. Preparation of the capitate andthe third metacarpal
To facilitate fusion of the two bones, all subchondral sclerosis
and cartilage must be removed, using either an oscillating
saw or a Gouge forceps. The normal CMC3 joint has a volar
angle of approximately 15 degrees. To allow the capitate to be
aligned with the third metacarpal, a 15 degree wedge of bone
should be resected. Make sure to avoid damaging the volar
ligaments.
The wrist is angled volarly and the Hohmann Earwig Retractor
is placed beneath the capitate to lift it up. This will close the
gap between the capitate and the third metacarpal.
The capitate should be fully aligned with the third metacarpal
when the above procedure is completed.
Note: When using the oscillating saw, it is important to keep
the saw blade cold by spraying sterile water on it.17
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5. Guide Wire insertion
A sharp tip Guide Wire is used to create a central canal through
the capitate and about 10-20 mm into the intramedullary canal of
the third metacarpal bone.
When inserting the Guide Wire, make sure to penetrate the
capitate pole in the center or slightly volarly. If going too
dorsally, there is a risk that the capitate will crack during drilling.
If the canal through the capitate needs to be adjusted, this is
best achieved using an Awl.
To ensure proper orientation of the Guide Wire, it is important to
have a true A/P and lateral view.
Note: The surgeon can use his thumb to put pressure on the
CMC-3 joint. This will align the capitate and the third metacarpal.
The sharp tip Guide Wire is then removed and a blunt tip Guide
Wire is mounted in the Guide Wire T-handle. It is introduced
through the capitate and into the intramedullary canal of the
third metacarpal. The Guide Wire should be advanced all the
way to the distal subchondral bone.
The advantage of using a blunt tip Guide Wire is that it will not
penetrate the cortical wall of the third metacarpal.
The guide wire is introduced until the end of the intramedullary
canal.
Sharp tip Round tip
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6. Drilling of the capitate andthe third metacarpal
Start by drilling with the small diameter Cannulated Metacarpal
Drill. The drill is introduced over the Guide Wire and advanced
at reamer speed.
Keep the drill cold by spraying sterile water on it. It is easy
to drill through the capitate but the hard bone in the third
metacarpal is difficult to open up. The drill must be cleaned
several times. It is recommended to drill further than the
isthmus.
To ensure proper orientation of the drill, it is important to have
a true A/P and lateral view.
7. Measuring the drill depth
Drill depth can be taken directly from the cutting flutes of
the Cannulated Metacarpal Drill. If no cortical resistance is
felt during drilling of the third metacarpal, the drill should be
exchanged to the large diameter drill. Push forward to eliminate
any gap between the capitate and the third metacarpal when
measuring.
It is important that the threads of the implant engage into the
cancellous and cortical bone of the third metacarpal, ensuring
stable fixation. Always try to pass the isthmus. The Cannulated
Metacarpal Drill and the Guide Wire are then removed.
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8. Introducing the MetacarpalThreaded Implant
The Metacarpal Threaded Implant should always be implanted
at this stage. This will minimize any possible damage to the
bone during preparation of the radius.
When introducing the Metacarpal Threaded Implant, it is
important to push the implant forward, closing the gap between
the capitate and the third metacarpal.
Avoid touching the implant surface. Use a sterile cloth to avoid
contact with the patients skin and avoid touching the implant
with surgical gloves. Use the screwdriver to pick up the implant
from the sterile packaging.
The Metacarpal Threaded Implant is inserted until its edge is
flush with the proximal pole of the capitate. Insertion is carried
out by hand only.
9. Preparation of the radius
The Awl is introduced under image intensification through the
joint surface of the radius. It should be placed central in the
A/P view and slightly volar in the lateral view.
Note: If the radius is deformed or the bone channel is too
narrow, it is possible to use the metacarpal drill with the
corresponding Metacarpal Threaded Implant.
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10. Guide Wire insertion
The Hohmann Earwig Retractor is placed beneath the edge of
the volar ridge to lift the radius. This will facilitate the insertion
of the Guide Wire and protect the capitate from the power drill.
The Guide Wire is introduced through the hole made by the
Awl in the joint surface of the radius.
The orientation of the guide wire is checked under image
intensification in both A/P view and lateral view.
11. Drilling of the radius
The Cannulated Radius Drill is introduced over the Guide Wire
and drilling is carried out at reamer speed. Gather the bone
chips that are collected in the cutting flutes of the drill on a
sterile cloth.
If the radius is deformed or the intramedullary canal is very
narrow, it is possible to use the Metacarpal Threaded Implant
in the radius. In such a case, use one of the Cannulated
Metacarpal Drills.
To ensure proper orientation of the drill it is important to check
the position under image intensification during drilling. Continue
drilling until cortical resistance is felt.
Drill depth
44 mm
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12. Reaming of the radius
In most cases, the space between the capitate and the joint
surface of the radius is too narrow to allow insertion of the
prosthesis. In such a case, it is necessary to ream a cavity for
the Radius Cup in the radius.
The appropriate Radius Cup size (15 mm or 18 mm) is selected
based on the height of the distal radius. The edge of the cup
(15 mm or 18 mm) should not rise above the dorsal radius.
The Driver Handle and the appropriate Radius Spherical Drill
(15 or 18 mm) are used to ream a cavity for the cup. The
Reamer has a mechanical stop that prevents over-reaming.
Note! The Radius CFR-PEEK Cup is only available in 15 mm.
13. Determining the correctRadius Threaded Implant size
If the radius was reamed: In most cases, use an implant
that is one step smaller than the drill depth measured against
the joint surface of the radius (e.g. If you drilled 44 mm you
would use a 38 mm implant). If uncertain, it is possible to insert
the drill and measure against the inner edge created by the
reamer.
If the radius was not reamed: Use the same implant size
as the obtained drill depth measured against the joint surface
of the radius (e.g. If you drilled 44 mm, you would use a 44 mm
implant).
Note! In the cadaver specimen illustrated in this surgical
technique there was no actual need for reaming of the radius
(enough space for the ball and socket). Therefore the radius
implant was inserted flush with the joint surface.
One implant size
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14. Insertion of theRadius Threaded Implant
The Radius Threaded Implant is introduced as far as it will go.
Avoid touching the implant surface. Use a sterile cloth to avoid
contact with the patients skin and avoid touching the implant
with surgical gloves. Use the screwdriver to pick up the implant
from the sterile packaging.
15. Insertion of the trials
The Radius Cup Trial is inserted in the Radius Threaded
Implant. Do not use the Impactor on the trial.
To determine the correct Metacarpal Head Trial, start by
inserting the shortest trial. Increase the trial size until the right
tension has been achieved.
When pulling the fingers, the Metacarpal Head Trial should
only just lift from the bottom of the cup. If one size up feels
too tight, or if one size down feels too loose, it is possible to
slightly adjust the Metacarpal Threaded Implant by introducing
it further into the bone. Keep in mind that tension will increase
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17. Insertion of the MetacarpalHead
Before introducing the chosen Metacarpal Head, make sure
that the internal Morse taper of the Metacarpal Threaded
Implant is clean. The Metacarpal Head is then inserted into
the Metacarpal Threaded Implant. Tap the Impactor gently to
ensure firm seating.
Reduce the joint and evaluate stability and range of motion
under image intensification.
Note! It is mechanically possible to reverse the prosthesis,
placing the Metacarpal Head in the Radius Implant. This has
however not been investigated and can not be recommended.
16. Insertion of the Radius Cup
Before introducing the Radius Cup, make sure that the internal
Morse taper of the Radius Threaded Implant is clean. The
Radius Cup is then inserted into the Radius Threaded Implant.
Tap the Impactor gently to ensure firm seating of the Radius
Cup.
Note! Make sure that the Morse taper of the Radius Cup is
firmly seated in the Radius Threaded Implant. There should be
a 1-2 mm gap between the cup and the bone.
Optional ceramic
coated metal cup
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18. Packing the gap betweencapitate and third metacarpal
Successful fusion of the capitate and the third metacarpal is
absolutely crucial for the long term fixation of the Metacarpal
Threaded Implant. To ensure successful fusion, pack the gap
using the bone chips that were gathered during drilling of the
radius. If necessary, collect additional bone chips from the
resected lunate or scaphoid.
If the capitate cracked
If a crack occurred in the capitate during the procedure, pack
the crack with bone chips and increase the cast period with
about two weeks.
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19. Final reduction
The joint is reduced and stability and range of motion is
evaluated under image intensification. Haemostasis is obtained
after releasing the tourniquet.
In this case there were no signs of impingement during final
reduction.
20. In case of impingement
If needed to avoid impingement, the tip of the radial styloid
and/or the triquetrum bone is also removed.
When resecting the radial styloid, use a periost elevator
to gently loosen the soft tissue. This will help preserve the
stability of the wrist.
Extension
Flexion
Radial deviation
Ulnar deviation
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Postoperative care
0-6 weeks:Casting for 6 weeks is recommended (first 2
weeks a plaster slab is used) with the wrist in slight extension
excluding the elbow, and allowing free forearm rotation, thumb
and finger motion. Start early hand therapy during the hospital
stay, with finger, forearm, elbow and shoulder motion.
At approximately 2 weeks the slab and sutures are removed
and a circular cast applied for additional 4 weeks. If there is any
problem with upper extremity motion the patient receive hand
therapy.
6 weeks: The cast is removed (and radiographs taken), and
active and passive wrist motion in all directions is instructed
and encouraged. Free weight-bearing is allowed if possible.
6 months:Radiographs are taken and ROM/grip strength/
VAS pain is recorded. If the patient have a slow progression,
the hand therapist is involved.
The patient is further followed at 1 year and yearly thereafter
with radiographs and recording of ROM/grip strength/VASpain. The improvement halts between the 2 and 3 year. Further
follow up according to the doctors preference, but should
include a 5 and 10 year appointment.
Note: The postoperative regime has been recommended by
Dr. O. Reigstad, Rikshospitalet, Hand and Microsurgery
Section, Orthopaedic Department N-0027 Oslo, Norway.
21. Closure
The dorsal capsule is closed as good as possible. The extensor
retinaculum is sutured back and a subcutaneous drainage is
introduced before the incision is closed.
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Implants
Radius Cup| CrN-CoCrMo| 15 mm 40-1015S
Radius Cup| CrN-CoCrMo| 18 mm (optional) 40-1018S
Radius Cup| CFR-PEEK| 15 mm 40-1915S
Metacarpal Head| 15 mm| Short Neck 40-1115S
Metacarpal Head| 18 mm| Short Neck (optional) 40-1118S
Metacarpal Head| 15 mm| Medium Neck 40-1715S
Metacarpal Head| 18 mm| Medium Neck (optional) 40-1718S
Metacarpal Head| 15 mm| Long Neck 40-1215S
Metacarpal Head| 18 mm| Long Neck (optional) 40-1218S
Metacarpal Head| 15 mm| Extra Long Neck 40-1315S
Radius Threaded Implant| length 32 mm 40-1332S
Radius Threaded Implant| length 38 mm 40-1338S
Radius Threaded Implant| length 44 mm 40-1344S
Metacarpal Threaded Implant| length 45 mm| Large 40-1445S
Metacarpal Threaded Implant| length 50 mm| Large 40-1450S
Metacarpal Threaded Implant| length 55 mm| Large 40-1455S
Metacarpal Threaded Implant| length 60 mm| Large 40-1460S
Product informationNeeded for CFR-PEEK articulation
Needed for CrN-CoCrMo articulation
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Metacarpal Threaded Implant| length 65 mm| Large (optional) 40-1465S
Metacarpal Threaded Implant| length 70 mm| Large (optional) 40-1470S
Metacarpal Threaded Implant| length 45 mm| Small 40-1475S
Metacarpal Threaded Implant| length 50 mm| Small 40-1480S
Metacarpal Threaded Implant| length 55 mm| Small 40-1485S
Metacarpal Threaded Implant| length 60 mm| Small 40-1490S
Metacarpal Threaded Implant| length 65 mm| Small (optional) 40-1495S
Metacarpal Threaded Implant| length 70 mm| Small (optional) 40-1400S
Trials
Trial CrN-CoCrMo Radius Cup| 15 mm 40-1522
Trial CrN-CoCrMo Radius Cup| 18 mm (optional) 40-1521
Trial CFR-PEEK Radius Cup| 15 mm 40-1541
Trial Metacarpal Head| 15 mm| Short Neck 40-1529
Trial Metacarpal Head| 18 mm| Short Neck (optional) 40-1527
Trial Metacarpal Head| 15 mm| Medium Neck 40-1524
Trial Metacarpal Head| 18 mm| Medium Neck (optional) 40-1523
Trial Metacarpal Head| 15 mm| Long Neck 40-1528
Trial Metacarpal Head| 18 mm| Long Neck (optional) 40-1526
Trial Metacarpal Head| 15 mm| Extra Long Neck 40-1602
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Instruments
Hohmann Earwig Retractor 40-1503
Hex Driver Tip | 3.5 mm 40-1513
Impactor 40-1516
Guide Wire T-handle 40-1518
Cup Remover 40-1519
Cannulated Radius Drill 40-1546
Cannulated Metacarpal Drill| Large 40-1551
Cannulated Metacarpal Drill| Small 40-1552
Guide Wire with sharp tip| 2 mm 40-1561
Guide Wire with round tip | 2 mm 40-1563
Radius Spherical Drill| 18 mm (optional) 40-1566
Radius Spherical Drill| 15 mm 40-1567
Tri-lobe Driver Handle 45-2585
Tri-lobe Ratchet Driver Handle (optional) 40-2593
Adapter| Tri-lobe to AO-coupling (optional) 40-5000
Hammer 52-2211
Awl 23.4997
Tray and lid 40-1600
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Swemac develops and promotes innovative
solutions for fracture treatment and joint
replacement. We create outstanding value
for our clients and their patients by being a
very competent and reliable partner.
Manufacturer: Swemac Innovation AB 0413
Industrigatan 11 SE-582 77 Linkping Sweden
Sales and distribution: Swemac Orthopaedics AB
Industrigatan 11 SE-582 77 Linkping Sweden
Phone +46 13 37 40 30 Fax +46 13 14 00 26
E-mail info@swemac.com www.swemac.com
Motec Wrist Joint Prosthesis
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