helica hip

veterinary implants

Surgery Manual

HELICAHip Prosthesis

Preoperative Planning

Surgery Manual

2

The choice of the best stem size is limited by the lenght and the diameter.The HD X-Ray image gives the information about the lenght of the stem. The Frog positioned X-ray image gives the limit of the stem diameter in the section of the smallest neckdiameter.

The choice of the best screw cup size can be measured by one of the images and is limited by the medial acetabular cortex.

max. diameter

max. length

Pre-planning of the operation is essential for optimal implant seating. The cup and stem sizes required, as well as the anticipated head length, are established using X-ray templates. To this end, templates in a ratio of 1.15:1 and 1:1 are available to the operator.

HELICA Hip Prosthesis

Length

ø

ø

Length

ø

Modular System Size Range

ø09 mm x 28 mm

ø08 mm x 26 mm

ø10 mm x 28 mm

ø11 mm x 32 mm

ø12 mm x 32 mm

ø26 mm

ø28 mm

ø30 mm

ø32 mm

ø18 mm, Short (+0 mm)

ø18 mm, Middle (+3 mm)

ø18 mm, Long

ø18 mm, XLong

ø18 mm, XXLong

(+6 mm)

(+9 mm)

(+12 mm)

Operative Approach to the Hip Joint

The standard longitudinal lateral approach with exposure of the anterior aspect of the joint should be used for this hip operation.nted.

Femoral Stems

Femoral Heads

Acetabular Cups

3

Resection of the Femoral Head

In the Helica Hip System, the resection line is located upside of the bone-cartilage interface direct through the femoral head. The resection cut is made perpendicular to the femoral neck.

Surgery Manual

Preparation of the Bed for the Screw Cup

4

Reaming of the acetabulum is performed in stages using acetabular reamers, starting with the smallest and progressing to the largest. Once the planned socket size has been achieved, punctuate bleeding should ideally be seen from all around the subchondral region. The size of the last acetabular reamer used determines the size of the screw socket to be implanted.

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Sample of the Preparation of the acetabular Bed

Step 1:Drilling a through boringup to the medial acetabularcortex and measuring thethickness.

Step2:Start reaming with the 24 mm“depth reamer”. Go sure bymeasurement that you are intothe required depth. Thisprocedure normally takes3 or 4 times of measuring.

Step 3:Using the final reamer for surfacingthe required diameter. For examplethe 26 mm reamer is the final andsurfacing reamer for the 26 mmscrew cup. The same applies for theother sizes.

Step 1 Step 2 Step 3

5

Implantation of the Screw Cup

Surgery Manual

The first step is to attach the insertion plate corresponding to the size of socket to be used to the square-section T-grip. The screw socket is attached to the insertion plate and introduced into the prepared acetabulum. Depending upon operator requirements, a navigation aid can be attached to the T-grip.

The next step is to align the screw socket in the acetabulum. The angle of inclination is determined with the navigation aid. With the patient in the lateral position, the alignment should result in the alignment shaft being parallel to the surface of the operating table. The operator establishes the anteversion angle by reference to the local anatomic conditions. Once correct alignment has been achieved, the screw socket is screwed into the Acetabulum using the T-grip and light presure (turning clockwise).

The screw on the socket taps itself into the acetabulum. The screwing step is finished once the pole of the socket has reached the base of the acetabulum. Over-tightening should be avoided.

6

7


Tip:All drills should be coupled by a machine adaptor to a power drill with a three-jaw chuck suitable for 6 mm bits.

The marrow cavity is initially opened using a small drill (2,0 or 2,5 mm). This drill is positioned centrally on the resection surface and should go trough the lateral cortex. The long axis of the drill must follow the midline axis of the femoral neck, so that a CCD angle of 145° to 147° is achieved. The waisted course of the femoral neck must be followed while doing this. The next step is to open the boring step by step starting with the smallest drill and ends with the drill that is provided for the implant size.

Preparation of the Marrow Cavity for the Femoral Shaft

Drill Size Implantat Size

ø4,5 mm

ø5,5 mm

ø6,5 mm

ø7,5 mm

ø8,5 mm

ø08 mm x 26 mm

ø09 mm x 28 mm

ø10 mm x 28 mm

ø11 mm x 32 mm

ø12 mm x 32 mm

Table 1: Implant size in relation to drilldiameter to use

If required (taking into account the operative planning), the marrow canal can be widened using sequentially bigger drills. A variety of drill diameters are available to the operator for this step. The last drill used determines the size of the implant to be used (see Table 1).

Face-milling of the Femoral Neck

Following drilling out of the marrow cavity, the femoral neck is milled flat. This step provides optimal seating of the segmented flange of the Stem onto the stump of the femoral neck.

The face-milling tool consists of a milling plate and a guide pin. The diameter to which the marrow cavity has been drilled out determines the diameter of the guide pin to be used. The selected guide pin is screwed into the milling plate. The construct is then connected to the drill via the machine adaptor.

Surgery Manual

During the milling process, the guide pin must run in the marrow cavity without bending. The milling process is complete when the milling plate lies snugly on the resection surface of the femoral neck circumferentially.

The length of the guide pin is harmonised with the length of the corresponding HELICA Stem. So it is ensured not to deep can be milled.

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9

Implantation of the HELICA Stem

There is a seating instrument available for implantation of the HELICA femoral stem. This is attached to the three-edged wedge on the conical end of the prosthesis. Next, the implant is placed on the prepared femoral neck and oriented so that the long axis of the implant follows the course of the drilling in the femoral neck. Then the femoral shaft is screwed in with light pressure (turning clockwise).

Tip:In order to support the self-tapping action of the thread on the HELICA prosthesis during insertion, it may be necessary to back out the screw by about a quarter turn for each full turn of insertion.

The insertion process is complete when the segmented collar of the implant sits snugly on the stump of the femoral neck. A gentle press-fit should be obtained.

Trial Relocation

In order to permit optimal restoration of joint function, trial femoral heads and trial cup inlays are available in each size. The length of the heads changes in 3 mm steps. By trial relocation while using a variety of trial femoral heads, the tendency to sublux and the range of motion can be assessed. Tip:In contrast to the implantable femoral heads, the trial heads do not result in conical jamming onto the femoral shaft and also do not generate a snap-on effect during relocation.

Surgery Manual

10

Insertion of the Cup Inlay

Insertion of the Cup Inlay is achieved with the aid of the seating instrument. The inlay is attached to the adaptor and inserted into the screw Cup. A light tap on the strike plate of the seating instrument snaps the inlay into the screw Cup. It is important to ensure that the rim of the inlay sits flush with the socket margin.

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Aftercare of the Patient

Careful education of the owner regarding the degree of exertion of the dog following the operation is very important for success.

There should be complete rest for the first 6 weeks following the operation. The daily walks should be short and stairs should be completely avoided.

Correct positioning of the implant is confirmed by check X-ray under sedation 6 weeks after the operation. Thereafter, the loading can be increased and after a further 2 weeks, no more restriction of movement is necessary.

After trial relocation and selection of the appropriate size, the corresponding femoral head is placed on the conical end of the femoral shaft. A light tap using the seating instrument achieves fixation. Finally, the joint is relocated. During this step, the femoral head must snap into the inlay.

Tip:It is important to ensure that the cushion of air between the femoral head and the inlay is expelled. This can be achieved by repeated pressing of the head into the inlay, as well as by abduction/ adduction movements.

Selection and Implantation of the Femoral Head

HELICA Instrument Set

12

Description

Femoral Head Seating InstrumentFemoral Shaft Seating InstrumentTrial Femoral Head ø18 mm, ShortTrial Femoral Head ø18 mm, MiddleTrial Femoral Head ø18 mm, LongMarrow Cavity Drill ø4,5 mmMarrow Cavity Drill ø5,5 mmMarrow Cavity Drill ø6,5 mmMarrow Cavity Drill ø7,5 mmMarrow Cavity Drill ø8,5 mmCentering Pin ø4,5 mm for Plane Milling ToolCentering Pin ø5,5 mm for Plane Milling ToolCentering Pin ø6,5 mm for Plane Milling ToolCentering Pin ø7,5 mm for Plane Milling ToolCentering Pin ø8,5 mm for Plane Milling ToolPlane Milling Tool

REF-Nr.

300-SK-0300-SH-0300-PH-S300-PH-M300-PH-L300-VB-45300-VB-55300-VB-65300-VB-75300-VB-85300-ZS-45300-ZS-55300-ZS-65300-ZS-75300-ZS-85300-PF-0

Position

12345678910111213141516

Set 1:HELICA Hip Stem

2

13 4 5

67

89

10

1112

1314

1516

Surgery Manual

13

Description

Screw Cup Insertion Plate ø26 mmScrew Cup Insertion Plate ø28 mmScrew Cup Insertion Plate ø30 mmScrew Cup Insertion Plate ø32 mmT- Handle for Screw Cup Insertion PlateSeating Instrument Cup InlayAcetabular Reamer ø24 mmAcetabular Reamer ø26 mmAcetabular Reamer ø28 mmAcetabular Reamer ø30 mmAcetabular Reamer ø32 mmNavigational Aid for Screw Cup Insertion ToolTrial Cup Inlay ø26 mmTrial Cup Inlay ø28 mmTrial Cup Inlay ø30 mmTrial Cup Inlay ø32 mm

REF-Nr.

300-ES-26300-ES-28300-ES-30300-ES-32300-TE-0300-SI-0300-AR-24300-AR-26300-AR-28300-AR-30300-AR-32300-NP-0300-PI-26300-PI-28300-PI-30300-PI-32

Position

17181920212223242526272829303132

Set 2:Acetabular Cup

27

29

28

30

313225

2324

22

21

19

17 1826

20


veterinary implants

INNOPLANT veterinaryHöfestraße 2530163 HannoverGermany

Phone:Fax:Mail:www.innoplant-vet.de

[email protected]

IN-M02-0002-01-O

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