Smith & Nephew RT-PLUS User manual

Surgical Technique
Intramedullary Procedure
Rotating Hinge Knee System
Sawblade Thickness: 1.00mm
Optional Thickness: 1.27mm
Product Identifiers – Knees II
Page 2 of 2 As of 06/02/2008
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RT-PLUS™
Rotating Hinged Knee
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RT-PLUS™
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TC-PLUS™ REVISION
Revision Knee System
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TC-PLUS™ REVISION
Revisions-Kniesystem
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RT-PLUS™
Rotating Hinged
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RT-PLUS™
Modular achsgeführtes Rotations nie-K
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RT-PLUS™
Modular Rotating Hinged
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RT-PLUS™
MODULAR
Modulaire rotatoire à charnière
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RT-PLUS™
IM Procedure
Table of Contents
Introduction........................................................................... 2
General Warnings and Comments ........................................ 3
Concept/Description............................................................. 4
Indications ............................................................................ 8
Contraindications.................................................................. 8
Case Study............................................................................ 9
Preoperative Planning ......................................................... 10
Surgical Technique.............................................................. 13
- Femoral Preparation...................................................... 17
- Tibial Preparation.......................................................... 27
- Patellar Preparation ...................................................... 35
- Implanting the Components ......................................... 37
Postoperative Treatment ..................................................... 41
Sterilization ......................................................................... 42
Implants .............................................................................. 44
Instruments ........................................................................ 46
Product Overview (Combination Tables).............................. 57
1
Nota Bene
The technique description herein is made available to the healthcare
professional to illustrate the author’s suggested treatment for the procedure.
In the final analysis, the preferred treatment is that which addresses the
needs of the patient.
Disclaimer
The following technique is for informational and educational purposes only. It
is not intended to serve as medical advice. It is the responsibility of treating
physicians to determine and utilize the appropriate products and
techniques according to their own clinical judgment for each of their
patients. For more information on the RT PLUS™, including its indications for
use, contraindications, and product safety information, please refer to the
product’s label and the Instructions for Use packaged with the product.

2
The RT-PLUS prosthesis, that is in clinical use
since 19961-9, is a valuable addition to
bicondylar surface replacement.
With the rising number of implantations we are
increasingly being confronted by cases which
are difficult to treat and which require the use
of special prosthetic systems using a higher
degree of coupling. The RT-PLUS prosthesis
has been designed to take this development
into account.
For a rotating hinge knee, the functional design
allows sparing resections. The joint
components feature anatomical geometry, as
also current primary knees, and can be either
used for primary or revision cases.
Special attention was also paid to the
development of a user-friendly instrument set.
Introduction

Warnings
They are written in orange. They must be followed as they relate to
critical functions or this information should be noted as it contains
valuable advice which helps the user to clinically apply the system.
Training
Only adequately trained operators should use the RT-PLUS™ knee
systems. This Surgical Technique must be fully read and understood as
part of the training. If any part of this documentation is not clear,
please contact your Smith & Nephew representative.
Implants
RT-PLUS knee system components are only designed for use with the
indicated Smith & Nephew implants and instruments. Implants and
instruments must be used in accordance with the instructions in all
other relevant Surgical Techniques.
Responsibility
It is the responsibility of the user of the RT-PLUS knee systems to
review all relevant information concerning the product before use. All
the information provided in the Instructions for Use and in the Surgical
Technique are to help the user in preparing for use of the product. The
user must check all recommendations concerning the product in the
Instructions for Use and in the Surgical Technique and is responsible
for all clinical decisions taken.
Cleaning and Sterilization
All instruments must be sterilized before use. Detailed information on
cleaning and sterilization of instruments is contained in the separate
cleaning and sterilization instructions No. 03389.
Additional Warnings
Warnings and comments cited in other Surgical Techniques relating to
RT-PLUS knee systems must also be followed.
General Warnings and Comments
3

4
Concept/Description
The RT-PLUS™ is a constrained rotating knee prosthesis for cemented implantation.
The prosthesis is designed to allow an internal/external rotation of approximately 10° in
each direction, which is locked by the tibial insert when extended. The peg design
provides the prosthesis with elongation capability, i.e., for distraction between the femoral
and tibial components. In an extreme flexed position, the femoral component can be lifted
off the tibial insert, which is intended to reduce the saggital leverage forces that have an
effect on the prosthesis stem in this load situation.
The implant allows sparing resections. The cut compatibility with the tricompartmental
prosthesis TC-PLUS permits, if necessary, an intraoperative switchover from the
resurfacing to the constrained rotating knee.
The femoral and tibial components of RT-PLUS are identical to those of RT-PLUS Modular,
with the exception of the additional option to connect stems and augmentation blocks.
Since the tibial inserts are the same, the femoral and tibial components in both these
systems are entirely cross-compatible.
The implants are available in five size (corresponding to TC-PLUS sizes 2, 4, 6, 8 and 10).
Apart from size 2, the sizes can be combined with the next size up or down (see product
overview on page 57).
The femoral and tibial components are anchored in the bone by cementable
intramedullary stems. These are comparatively slim and short in design, in order to enable
anchoring in narrow or dysplastic medullary cavities.
In the RT-PLUS knee system, the required stability and absorbtion of acting forces are
assured by the joint mechanism between tibial and femoral components, the condylar
articulating surfaces, the anchoring elements in the tibia and the femur and the still intact
soft tissue structures.
Important
RT-PLUS requires condylar support for the femoral/tibial components. The forces have to
be absorbed by both the condyles and the stems.

5
Product Description
Femoral component
The femoral component, which is
asymmetrical, is manufactured using a
CoCrMo alloy.
The femoral patellar groove is deeply
hollowed out and present a 6° oblique
patella tracking.
The joint mechanism is contained in a narrow
box (only 25mm) that keep an anterior bone
bridge and require minimum bone resection,
thereby reducing the risk of femoral condyle
fracture.
The 40mm rotation peg enables a stable
distraction up to 20 mm, thus providing
protection against dislocation and ensuring
smooth coupling characteristics of
the components.
The special joint mechanisms are designed
to enable a physiological roll-back of 9mm,
which is intended to improve the flexion
capacity of the joint. Furthermore, the
rotation peg enables physiological internal
and external rotation of 10° from 15° flexion.
The joint mechanism has been designed in
such a way, that all metal components
(rotation peg and transversal axis) are lined
with UHMWPE to absorb the stress forces.
The slender tapered femoral stems allows a
stable anchorage, even when the medullary
cavity is restricted.
The femoral component is available in sizes
2, 4, 6, 8, and 10.
Patellar component
The all-poly (UHMW-polyethylene) patellar
component has a symmetrical biconcave
surface for better tracking.
The patellar component are identical to those
in the TC-PLUS portfolio.
Please see the available sizes in the implant table (on page 44 ff).

6
Tibial insert
The simple anchored tibial insert is
manufactured from UHMW polyethylene and
in order to restore the joint line,
independently to the degree of tibial bone
loss, three different heights (8, 11 and 14 mm)
of tibial inserts are available.
Important
The tibial components thickness of 3mm
need to be added to the tibial insert height of
8mm resulting in a total tibial height of 11mm,
14mm for a tibial insert of 11mm and 17mm for
a tibial insert of 14mm, respectively.
The minimum effective PE thickness in the
load zone is 8mm.
The special anchorage design of the
polyethylene insert and method to place into
the tibial component, enables an easy
coupling of the prosthesis, for which only
minimal distraction is required.
While the tibial insert is in place, it is
additionally secured by a clamp that is
locked with a PE pin.
The tibial inserts are identical to those in the
RT-PLUS™ Modular portfolio.
Tibial component
The symmetrical tibial component is
manufactured from CoCrMo alloy. In order to
minimize polyethylene wear inside the tibial
component, the base plate is polished on
the inside and the insert is completely
enclosed along its entire circumference.
To improve flexion, the tibial component is
designed with 3° posterior slope and need
therefore to be aligned in rotation.
The slender tapered femoral and tibial stems
allows a stable anchorage, even when the
medullary cavity is restricted.
The tibial component is available in sizes 2,
4, 6, 8, and 10.

7
Please see the available sizes in the implant table (on page 44 ff).
Tibial blocks (PE)
In order to compensate tibial bone defects,
there are proximal tibial blocks available in
height of 10mm.
The tibial blocks are manufactured from
UHMW PE and are cemented both side (on
bone & tibial component).
Before applying the cement on the tibial
block, make sure that the component is clean
of any fluid and particles.

8
The principal preoperative planning factor is correct diagnosis. The surgeon must
determine if the bone condition and stability require a constrained prosthesis implant.
The main indications for an RT-PLUS™ implant are:
• High grade joint destruction, with considerable loss of function and the need for
additional stabilization using stems
• Severe joint instability that predictably cannot be corrected through suitable bone
reconstruction (bone grafts) or soft tissue intervention
• Marked contractures and axial displacements exceeding 15-20°
• Failure after surface replacement (e.g., infection, loosening)
• Revision of a primary prosthesis
• Trauma induced femoral or tibial fractures
Important
Due to the design, it is possible to switch with relatively little effort, even intraoperatively,
from the TC-PLUS knee system to the RT-PLUS Modular knee system, since the resections
and prosthesis sizes match.
Contraindications
Contraindications are:
• Acute or chronic local or systemic infections (or if a corresponding anamnesis occurs)
• Severe muscle, nerve, or vascular diseases that endanger the affected extremity
• A lack of bone substance or inadequate bone quality that endangers stable seating of the
prosthesis
• Severe obesity
• All concomitant diseases that may endanger implant function. These include, in
particular, extreme insufficiency of the knee extensor mechanism, which can lead to
excessive joint distortion, or severe obesity, which can lead to dorsal impingement and
possible uncoupling of the components. Use of a hinged or tumour prosthesis may be
advisable in these cases
• Patient hypersensitivity or allergy to the materials used
• Strenuous physical activity (e.g., competitive sport, hard physical work)
Indications

9
Case Study
Patient presenting with severe joint instability (valgus gonarthrosis), with a valgus angle of 25° and
medial joint destruction.
Preoperative picture
Postoperative result
Immediately postoperatively: functional and pain-free reconstruction with RT-PLUS™ knee.

10
A full leg x-ray, with the patient in standing position, is recommended for preoperative
planning purposes. If this is not possible, an x-ray of the thigh, including the femoral head,
should be taken. X-ray images of the knee joint at three levels should be available for
planning the surgery. A tangential patellar view, a frontal view, and a view sagittal to the leg
axis must be recorded.
X-ray templates with scales of 1.15:1 (Lit. No. 1069) and 1:1 (Lit. No. 1585) (see page 56) are
available for preoperative planning. The lateral view of the condyles is decisive. If these are
no longer completely intact, the condylar width can be used instead. In doubtful cases, the
smaller implant should be selected to prevent the prosthesis components from protruding.
The size determination and the correct positioning of the prosthesis are normally controlled
intraoperatively using the relevant instruments, and planning may also be possible on the
unrestored opposite leg.
Important
All femoral and tibial component sizes can be combined with the next size up or down (see
product overview, starting page 57). This does not apply to combinations of sizes 2 and 4.
Large deviations of the femoral neck angle as well as severe deformities of femur and tibia
(e.g., posttraumatic axial deformities) must be taken into consideration while planning the
surgery.
Additional corrective osteotomies may be indicated, in rare cases of deformities away from
the knee joint that negatively influence the mechanical leg axis.
Preoperative Planning

11
The following procedure is recommended
for the anterior-posterior whole leg imaging
process:
1. Femoral axis “A” (anatomical axis) is drawn
onto the radiograph.
2. A line is drawn from the femoral head to the
centre of the knee (mechanical axis “D”) on
the radiograph.
3. Angle measured between anatomical and
mechanical axes: Angle determines the
valgus angle.
4. Tibial axis “B” is drawn in and tibial resection
plane “E” is determined, in order to avoid
excessive resection, especially if defects are
present.
5. Component sizes and resection depths are
determined preoperatively, using the x-ray
templates (See page 57) in the A/P and
lateral planes.
6. Mechanical leg axis “C” should merge with
lines “D” and “B” after correction.
Planning the Surgery Using the Radiograph
A Anatomical femoral axis
B Anatomical tibial axis
C Mechanical leg axis
D Mechanical femoral axis
E Tibial resection depth (mm)
Valgus angle
Pre-op Post-op

12

Surgical Technique
13
Positioning the patient for surgery
Surgery is performed while the patient is
supine.
The operation can be performed with or
without tourniquet. It is recommended to use
a flexible cover for the leg which allows a
stable positioning of the knee joint in 90° of
flexion.
Most of the surgical steps are performed in
this position.
Surgical procedure
The skin incision can be a midline or a
parapatellar incision.
If scars are present from skin incisions made
during previous operations, use these for
access is advisable in order to reduce the
risk of cutaneous blood flow disorders.
Medial arthrotomy or an approach adapted
to the pathologic situation is recommended.
After the usual preparation (meniscus
resection, removal of osteophytes and
synovectomy if necessary), the cruciate
ligaments are sectioned and, if needed, the
collateral ligaments are removed close
to the bone.
Implant components removal
In case of an implant revision, where
components must be removed at the
beginning of the surgery, Smith & Nephew
with the RENOVATION™ Knee set, offers the
surgeons a knee specific implant extraction
system that contents different instrument
options to facilitate the removal of different
femur and tibia components (loose first and
then extract).
The instrument set consists of a basic set
(no. SAP 75210243 / 0944290) and sterile
packaged, single-use chisel-blades and
saw-blades (see surgical technique Lit. No.
04044 (2025).

Overview of the Resection Sequences for Primary Application
14
It is important to have identical flexion and extension gaps.
1. Distal femoral resection.
2. A/P femoral resection.
3. Chamfer resections and cutting out the
box. Remove residual posterior condyles if
present.
Important
To avoid the risk of a condyle fracture, we
recommend preparing the box after tibial
preparation.
4. Tibial resection and optional augment
resection.
5. Patellar resection (optional).
Important
For the standard instrument set, use 1.00 mm saw blades for all bone resections!
For the 1.27 mm instrument slot option, use the corresponding 1.27 mm saw blades.
See Lit. No. 01218 for corresponding connection.

Overview of the Resection Sequences for Revision Application
15
The bone resections are refreshed after extraction of the primary implants.
1. Distal femoral resection.
2. A/P femoral resection.
3. Chamfer resections and cutting out the
box. Remove residual posterior condyles if
present.
Important
To avoid the risk of a condyle fracture, we
recommend preparing the box after
tibial preparation.
4. Tibial resection and optional augment
resection.
5. Patellar resection (optional).
Important
For the standard instrument set, use 1.00 mm saw blades for all bone resections!
For the 1.27 mm instrument slot option, use the corresponding 1.27 mm saw blades.
See Lit. No. 01218 for corresponding connection.

16
Use of Speed-pins
We also offer speed-pins as an alternative for
fixing the instrument to the bone.
The speed-pins are available in different
lengths and types:
Speed-Pins with Rim Ø 3.2 / 30 mm
– 6x PAC (Art. No. 42000089)
Speed-Pins with Rim Ø 3.2 / 45mm
– 6x PAC (Art. No. 42000176/75018973)
Speed-Pins Ø 3.2 / 65 mm
– 6x PAC (Art. No. SYS251354)
Speed-Pins Ø 3.2 / 80 mm
– 6x PAC (Art. No. SYS251355)
Speed-Pins Ø 3.2 / 110 mm
– 6x PAC (Art. No. SYS251356)
AO Adapter for Speed-Pins
(Art. No. SYS251316)
The speed-pins are delivered non-sterile and
for multiple use. The limitation use of the
speed pin is defined as the standard pin,
until the functionality is no longer ensured.

Femoral Preparation
17
Access: For initial access to the knee, refer to the relevant surgical textbooks.
Important
In addition to the bone resections, it is important to correct any ligament imbalance using
appropriate soft tissue procedures. If necessary, a general release should be performed on
the side of the contracture prior to the bone resections.
The leg is flexed and any osteophytes on the femur and tibia are removed. This will provide
good exposure of the knee joint and thus facilitate size determination.
Femoral size determination
The femoral sizers (2, 4, 6, 8, and 10) are
used to determine the size sagittally,
based on the inside/outside contours, and
ventrally, based on the anterior/posterior
resections and the medial/lateral contours.
The additional marking lines correspond to
the augmentation blocks.
Important
The red line in the sagittal view, as well as
the hole in the frontal view of the femoral
sizer, shows the position of the femoral IM
canal, i.e., the position of the stem.
While taking measurements, note the marks
corresponding to medial and lateral:
LEFT and medial.
Femur opening
Set the adjustable IM femoral drill guide to
the planned size of the femoral component
(size marking 2, 4, 6, 8, or 10) and insert
under the quadriceps into the centre of the
femur. The distal stop should rest on the
medial condyle. Make sure the gauge lies flat
against the anterior femoral cortical bone in
the direction of the femoral axis.

18
Important
To ensure optimal positioning of the femoral
drill guide on the condyles, gently tap the
M/L area – not the drill guide section of the
instrument.
Open the femoral IM canal as far as the stop,
using the ∅8/14 mm IM stepped drill. The
drill direction is along the femoral axis.
Important
The femoral IM canal, which determines the
position of the implant stem, must be opened
carefully (reference for the femoral position)
so as to prevent development of a relative
extension position (risk of notching) or flexion
position (projecting patella).
Using the modular handle, carefully insert
the ∅8 mm IM rod approximately up to the
isthmus of the femoral IM canal and then
remove.
It is important to work carefully, to prevent
excessive pressure in the IM canal.
Preparing the femoral anchorage
Open the femoral IM canal with the long
∅14 mm reamer until the mark on the
reamer reaches the intercondylar notch, or
the bone resection if performing a revision.
The reamer should be aligned parallel to the
femoral anatomical axis, both anteriorly and
laterally. Now remove the modular handle.
If an intramedullary obstacle is encountered
(e.g., a hip implant), the short reamer may be
used as an alternative.