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smith&nephew ZUK, Surgical Techniques

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8

Fig. 13

Note: This technique is written  
to cut the tibia after cutting the 
distal femur. If preferred, the  
femoral cuts can be finished first 
(Refer to page 12). 
The ZUK Unicompartmental Knee 
System is designed for an anatomic 
position with a 5° posterior slope. It is 
important that the proximal tibial cut be 
made accurately. The tibial assembly 
consists of a Tibial Resector, a Tibial 
Resector Base, a Tibial Resector Stem, 
a Distal Telescoping Rod, and an Ankle 
Clamp (Fig.12). 

Positioning of the 

Tibial Resector is crucial.
Slide the Ankle Clamp onto the dovetail 
at the bottom of the Distal Telescoping 
Rod, and tighten the knob opposite  
the dovetail to temporarily hold the 
clamp in place. Then insert the 
appropriate length Tibial Resector  
Stem into the proximal end of the Distal 
Telescoping Rod and tighten the knob. 

Attach the appropriate Tibial Resector 
to the corresponding Tibial Resector 
Base. Note that the resector and base 
are available in two configurations: 
LT MED/RT LAT and RT MED/LT LAT. 
Then slide the dovetail on the Tibial 
Resector Base onto the proximal end 
of the Tibial Resector Stem and tighten 
the knob on the stem. The dovetail 
provides a slide adjustment that allows 
M/L positioning.

Secure the distal portion of the 
assembly by placing the spring arms 
of the Ankle Clamp around the ankle 
proximal to the malleoli (Fig.13). Loosen 
the knob at the top of the Distal 
Telescoping Rod, position the Tibial 
Resector proximal to the tibial tubercle 
with the cutting slot at the approximate 
desired level of resection, then 
retighten the knob.

While holding the proximal portion of 
the assembly in place, loosen the knob 
that provides mediolateral adjustment 
of the Distal Telescoping Rod. Adjust 
the distal end of the rod so it lies 
directly over the tibial crest. Then fully 
tighten the knob to secure it in place. 

This will help ensure that  
the proximal portion of the guide 
is parallel to the mechanical axis of 
the tibia. Mediolateral adjustments 
can also be made proximally, but the 
proximal portion will always remain 
parallel to the distal portion and, 
therefore, parallel to the mechanical 
axis of the tibia.

Use the proximal M/L slide adjustment 
at the midshaft of the assembly to 
position the fixation arm of the Tibial 
Resector Base and Tibial Resector  
so it lies just medial to the midpoint  
of the tibial tubercle and is in line 
with the center of the intercondylar 
eminence (Fig.14).

Ankle Clamp

Distal  

Telescoping Rod

Tibial Resector 

Stem

Tibial  

Resector

Tibial Resector 

Base

Fig. 12

Fig. 14

Step Three

Resect The Proximal Tibia

Summary of Contents for ZUK

Page 1: ...Minimally Invasive Surgical Techniques for the Medial Compartment Intramedullary Spacer Block and Extramedullary techniques ...

Page 2: ...se refer to the product s label and the Instructions for Use packaged with the product Indications Unicompartmental knee implants are indicated for restoring either compartment of a knee that has been affected by the following 1 Noninflammatory degenerative joint disease including osteoarthritis traumatic arthritis or avascular necrosis 2 Correction of functional deformity 3 Revision procedures wh...

Page 3: ...l Reduction 18 Step Nine Implant Final Components 19 Closure 20 Spacer Block Surgical Technique 21 Spacer Block Option 21 Extramedullary EM Surgical Technique 23 Introduction 23 Rationale 23 Preoperative Planning 24 Patient Preparation 24 Exposure 25 Step One Assemble Apply the Instrumentation 26 Step Two Align the Joint 30 Step Three Resect the Distal Femoral Condyle 32 Step Four Resect the Proxi...

Page 4: ...ystem IM Extramedullary Instrumentation System EM The same tibial assembly is used for all three options However the distal femoral resection instruments are unique to each of the three techniques This guide to the surgical technique is a step by step procedure written for a medial compartment UKA Many of the same principles can be applied to the lateral compartment but it may be necessary to exte...

Page 5: ... that the methods used to adjust alignment in TKA are very different from those used in unicompartmental arthroplasty In TKA the angle of the femoral and tibial cuts determines the postoperative varus valgus alignment In UKA the angle of the cuts does not affect varus valgus alignment Instead postoperative varus valgus alignment is determined by the composite thickness of the prosthetic unicompart...

Page 6: ...ver if preferred the tibia can be resected first To resect the tibia first begin with Step 3 Resect the Proximal Tibia Then continue with Step 1 Resect the Distal Femur For the Spacer Block technique the tibia must be resected first as the femoral resection is based off the tibial cut If the surgeon prefers to use the Spacer Block technique begin with Step Three Resect the Proximal Tibia Then go t...

Page 7: ...remove peripheral osteophytes that interfere with the collateral ligaments and capsule With medial compartment disease osteophytes are commonly found on the lateral aspect of the medial tibial eminence and anterior to the origin of the ACL Final debridement will be performed before component implantation Careful osteophyte removal may be important in achieving full extension Fig 4 7 12cm Skin Inci...

Page 8: ...e the site for inserting the IM Femoral Resection Guide approximately 1cm anterior to the origin of the posterior cruciate ligament and just anterior to the intercondylar notch in the distal femur Use the 8mm Femoral IM Drill or an awl to create the hole for the guide Hold the drill parallel to the shaft of the femur in both the A P and lateral projections Fig 6 Drill only the cancellous bone of t...

Page 9: ...lock Note If a pin is used for fixation of the IM guide to the distal femur impingement may occur with the saw blade The distal cut may be started with the pin in place but the pin should be removed before contact with the blade occurs Use a narrow 1 27mm 0 050 inch oscillating or reciprocating blade to cut the distal portion of the condyle through the slot of the Distal Femoral Resector Block Fig...

Page 10: ...nt that allows M L positioning Secure the distal portion of the assembly by placing the spring arms of the Ankle Clamp around the ankle proximal to the malleoli Fig 13 Loosen the knob at the top of the Distal Telescoping Rod position the Tibial Resector proximal to the tibial tubercle with the cutting slot at the approximate desired level of resection then retighten the knob While holding the prox...

Page 11: ...of resection with the Resection Guide Fig 16 Fig 15 Secure the assembly to the proximal tibia by inserting a 48mm Headed Screw or predrilling and inserting a Holding Pin through the hole in the fixation arm of the Tibial Resector Base Fig 16 Do not completely seat the screw pin until the final adjustments have been made to the position of the Tibial Resector Use the 2mm tip of the Tibial Depth Res...

Page 12: ...Fig 18 Fig 19 Insert a retractor medially to protect the medial collateral ligament Use 1 27mm 0 050 inch oscillating saw blade through the slot in the cutting guide to make the transverse cut The Tibial Resector must remain against the bone during resection Note Do not use a saw blade with a thickness of less than 1 27mm to avoid inaccurate cuts With the knee flexed use the reciprocating blade at...

Page 13: ...g the thin end of the selected Flexion Extension Gap Spacer into the joint Fig 21 If in both flexion and extension the joint space is too tight to insert the 8mm Flexion Extension Gap Spacer then more tibial bone must be removed Then use the Flexion Extension Gap Spacers to recheck the gaps If in both flexion and extension the joint space is too loose insert progressively thicker Flexion Extension...

Page 14: ...tour of the Femoral Sizer Finishing Guides matches the contour of the corresponding implant Insert the prongs on the Insertion Handle into the corresponding holes of the appropriate left or right Femoral Sizer Finishing Guide Fig 22 Then thread the handle into the guide and tighten it securely Fig 23 2 to 3mm Note Be sure that there is no soft tissue or remaining osteophytes between the Femoral Si...

Page 15: ...l Sizer Finishing Guide does not overhang 2 Insert one 33mm Headed Screw gold head into the angled anterior pin hole which is parallel to the chamfer cut Fig 28 For best fixation seat the screw head slowly This should stabilize the guide sufficiently to finish the femur For additional stability insert a 48mm Headed Screw or predrill and insert a Short Head Holding Pin into the middle hole closest ...

Page 16: ...ional stability 4 Drill the posterior post hole in the same manner This hole is angled the same as the anterior post hole Fig 30 5 Remove the anterior Femoral Holding Peg and cut the posterior chamfer through the cutting slot in the guide If a screw pin was inserted into a middle hole either remove the screw pin or cut around it The remaining island of bone can then be resected after removing the ...

Page 17: ...ebride the joint and inspect the posterior condyle If any prominent spurs or osteophytes are present especially in the area of the superior posterior femoral condyle remove them with an oscillating saw or an osteotome as they could inhibit flexion or extension Fig 33 Technique Tip The Femoral Provisional may be put in place and the knee flexed This would aid in identifying and removing any residua...

Page 18: ... tibia in both the A P and M L dimensions If desired use the resected tibial bone fragment as an aid in sizing If necessary a second sagittal cut can be made to allow for optimal coverage with the next larger size tibial base plate The Tibial Sizer has a sliding ruler which facilitates measuring in the A P dimension Fig 35 Be sure that the head of the sizer rests on cortical bone near the edge of ...

Page 19: ...bial Fixation Plate Provisional in place on the bone There are a number of indicators on the Tibial Sizer If the slider is used without the sizer the etch marks 1 through 6 on the slider indicate the A P length of the corresponding implant If the slider is used with the sizer the A P length is indicated on the sizer handle Fig 37 An additional measurement on the slider at the tip of the sizer hand...

Page 20: ... correct prosthesis should allow the joint space to be opened approximately 2mm when a stress is applied with the knee in full extension and without soft tissue release The knee must also be tested in 90 of flexion to allow a 2mm flexion gap Excessive flexion tightness will prevent postoperative flexion and may cause the tibial prosthesis to lift up anteriorly as the femoral component rolls poster...

Page 21: ...an opened and slightly moist sterile gauze sponge behind the tibia before implanting the components to help collect excess cement behind the tibia Apply cement and press the tibial base plate or the all polyethylene tibial component onto the tibia Position and press down the posterior portion of the component first Then press the anterior portion of the component expressing excess cement anteriorl...

Page 22: ...ticular Surface After the cement has cured remove any remaining excess cement before the final placement of the tibial articular surface Do not proceed with locking the final articular surface component until cement has fully cured With the engraved side down slide the edge of the polyethylene component under the posterior lip of the base plate Then insert the tab on the lower jaw of the Tibial Ar...

Page 23: ... not fit into the joint remove an additional 2mm from the proximal tibia If the 8mm Spacer Block is too loose use a thicker Spacer Block Insert a 48mm Headed Screw or predrill and insert a Short head Holding Pin into the anteromedial angled hole in the Spacer Block Fig 2 Attach the Alignment Tower to the Spacer Block Fig 3 and insert the Alignment Rod through the Alignment Tower Then insert the Ta...

Page 24: ... 5 Then secure the guide by inserting a 48mm Headed Screw or predrill and insert a Holding Pin through the hole Fig 6 Use a 1 27mm 0 050 inch oscillating saw blade to resect the distal femur Fig 7 Do not extend the saw blade posteriorly past the distal femur to avoid damaging the posterior popliteal area If desired the femoral cut can be started in extension and finished in flexion Before flexing ...

Page 25: ... it may be necessary to extend the incision a few centimeters given the proximity of the patella to the lateral condyle Combined with surgeon judgment proper patient selection and appropriate use of the device this guide offers a comprehensive technique that discusses the procedure for component selection bone preparation trial reduction cementing techniques and component implantation It is strong...

Page 26: ...f the femoral head Alternatively the surgeon may prefer to reference the anterior superior iliac spine Technique tip Place a marker such as an EKG electrode over the center of the femoral head Then confirm the location with an A P radiograph or fluoroscopy Preoperative Planning This technique is written with the distal femoral resection performed first However if preferred the tibia can be resecte...

Page 27: ...eniscus The remainder of the meniscus will be removed after bone resection A subperiosteal dissection should be carried out towards the midline ending at the patellar tendon insertion This will facilitate positioning of the tibial cutting guide Debride the joint and inspect it carefully Remove intercondylar osteophytes to avoid impingement with the tibial spine or cruciate ligament Also remove per...

Page 28: ...nsists of an Ankle Clamp a Distal Telescoping Rod a Tibial Resector Stem a Tibial Resector Base a Tibial Resector and a Distal Femoral Resector Fig 5 Positioning of the Tibial Resector and Distal Femoral Resector is crucial Assemble the Instrument Slide the Ankle Clamp onto the dovetail at the bottom of the Distal Telescoping Rod and tighten the knob opposite the dovetail to temporarily hold the c...

Page 29: ...sector into the affected compartment Fig 7 Be sure that the paddle abuts the most distal aspect of the femoral condyle and that the Tibial Resector engages the anterior tibia Then retighten the knob at the top of the Distal Telescoping Rod Technique tip If the Distal Femoral Resector will not fit into the joint while attached to the assembly remove the holding peg and resector Then place the Tibia...

Page 30: ...tal portion and therefore parallel to the mechanical axis of the tibia Use the M L slide adjustment at the midshaft of the assembly to position the fixation arm of the Tibial Resector Base and Tibial Resector so it lies just medial to the midpoint of the tibial tubercle and is in line with the center of the intercondylar eminence Fig 8 In the sagittal plane align the assembly so it is parallel to ...

Page 31: ... opening the extension gap more relative to the flexion gap This can be accomplished by moving the assembly closer to the leg distally Then check the depth and angle of resection with the Resection Guide Secure the assembly to the proximal tibia by inserting a 48mm Headed Screw or predrilling and inserting a Holding Pin through the hole in the fixation arm of the Tibial Resector Base Fig 10 ...

Page 32: ...e guide near the femoral head Fig 11 While maintaining this corrected position use the thumb screw on the Tibial Resector Base to move the cutting guides superiorly until the paddle on the Distal Femoral Resector contacts the distal femoral condyle It is important to manually hold the joint open and raise the paddle to meet the condyle rather than using the paddle to open the joint Once the paddle...

Page 33: ... Screws through the two holes Fig 13 Use electrocautery or the reciprocating saw to score the tibial surface where the sagittal cut will be made Check this point both in extension and flexion If desired the depth of both the femoral and tibial cuts can be verified by inserting the Resection Guide through the cutting slots Fig 14 Fig 13 Fig 14 ...

Page 34: ...osterior margin of the femoral condyle while the knee is in extension Begin the femoral cut with the knee in extension Before flexing the knee use the Removal Hook to remove the Distal Femoral Resector Fig 16 by sliding it over the headless pins or screws or by removing the headed pins or screws Note If completing the distal femoral cut after removing the Distal Femoral Resector the cut must be fi...

Page 35: ...nst the bone during resection Make the sagittal cut with the knee flexed Position the reciprocating saw blade at the base of the tibial eminence and parallel to the eminence in the A P plane Cut along the edge of the ACL down to but not beyond the intended level of the transverse cut Fig 17 Be careful to avoid the ACL attachment When the tibial preparation is complete remove the tibial assembly ...

Page 36: ...hin end of the selected Flexion Extension Gap Spacer into the joint Fig 19 If in both flexion and extension the joint space is too tight to insert the 8mm Flexion Extension Gap Spacer then more tibial bone must be removed Then use the Flexion Extension Gap Spacers to recheck the gaps Fig 18 Fig 19 If in both flexion and extension the joint space is too loose insert progressively thicker Flexion Ex...

Page 37: ...e Femoral Sizer Finishing Guides matches the contour of the corresponding implant Insert the prongs on the Insertion Handle into the corresponding holes of the appropriate left or right Femoral Sizer Finishing Guide Fig 20 Then thread the handle into the guide and tighten it securely Fig 21 Step Six Size the Femur Fig 20 Fig 21 ...

Page 38: ...maller size This helps prevent the patella from impinging on the prosthesis Note Be sure that there is no soft tissue or remaining osteophytes between the Femoral Sizer Finishing Guide and the cut distal condyle It is important that the Femoral Sizer Finishing Guide sits flush against the bone Any gaps between the guide and the bone will compromise the accuracy of the cuts and subsequently compone...

Page 39: ...nish the Femur 2 Insert one 33mm Headed Screw gold head into the angled anterior pin hole which is parallel to the chamfer cut Fig 26 For best fixation seat the screw head slowly This should stabilize the guide sufficiently to finish the femur For additional stability insert a 48mm Headed Screw or predrill and insert a Short Head Holding Pin into the middle hole closest to the intercondylar notch ...

Page 40: ...ional stability 4 Drill the posterior post hole in the same manner This hole is angled the same as the anterior post hole Fig 28 5 Remove the anterior Femoral Holding Peg and cut the posterior chamfer through the cutting slot in the guide If a screw pin was inserted into a middle hole either remove the screw pin or cut around it The remaining island of bone can then be resected after removing the ...

Page 41: ...ebride the joint and inspect the posterior condyle If any prominent spurs or osteophytes are present especially in the area of the superior posterior femoral condyle remove them with an oscillating saw or an osteotome as they could inhibit flexion or extension Fig 31 Technique Tip The Femoral Provisional may be put in place and the knee flexed This would aid in identifying and removing any residua...

Page 42: ... tibia in both the A P and M L dimensions If desired use the resected tibial bone fragment as an aid in sizing If necessary a second sagittal cut can be made to allow for optimal coverage with the next larger size tibial base plate The Tibial Sizer has a sliding ruler which facilitates measuring in the A P dimension Fig 33 Be sure that the head of the sizer rests on cortical bone near the edge of ...

Page 43: ...bial Fixation Plate Provisional in place on the bone There are a number of indicators on the Tibial Sizer If the slider is used without the sizer the etch marks 1 through 6 on the slider indicate the A P length of the corresponding implant If the slider is used with the sizer the A P length is indicated on the sizer handle Fig 35 An additional measurement on the slider at the tip of the sizer hand...

Page 44: ...correct prosthesis should allow the joint space to be opened approximately 2mm when a stress is applied with the knee in full extension and without soft tissue release The knee must also be tested in 90 of flexion to allow a 2mm flexion gap Excessive flexion tightness will prevent postoperative flexion and may cause the tibial prosthesis to lift up anteriorly as the femoral component rolls posteri...

Page 45: ...an opened and slightly moist sterile gauze sponge behind the tibia before implanting the components to help collect excess cement behind the tibia Apply cement and press the tibial base plate or the all polyethylene tibial component onto the tibia Position and press down the posterior portion of the component first Then press the anterior portion of the component expressing excess cement anteriorl...

Page 46: ...ticular Surface After the cement has cured remove any remaining excess cement before the final placement of the tibial articular surface Do not proceed with locking the final articular surface component until cement has fully cured With the engraved side down slide the edge of the polyethylene component under the posterior lip of the base plate Then insert the tab on the lower jaw of the Tibial Ar...

Page 47: ...7220 4149 Dyonics Single sided Tibia Resector 5 Spacer Block 5 Spacer Block Femoral Resector Femoral Sizer Finishing Guide 7401 3401 30mm Rimmed SPEED PIN 00 5791 044 00 Headed Screw 33mm 7401 3471 45mm Rimmed SPEED PIN 00 5791 041 00 Headed Screw 48mm 2mm Recut Block 7401 3471 45mm Rimmed SPEED PIN 00 5791 041 00 Headed Screw 48mm EM Femoral Resector 7401 3471 45mm Rimmed SPEED PIN 00 5791 041 00...

Page 48: ...8 www smith nephew com The color Pantone 151 Orange for medical instruments is a U S registered trademark of Smith Nephew Trademark of Smith Nephew All Trademarks acknowledged Supporting healthcare professionals for over 150 years References 1 Cartier P Seinouiller JL Grelsamer RP Unicompartmental knee arthroplasty 10 year minimum follow up period J Arthroplasty 1996 11 7 782 788 ...

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