RECONSTRUCTION 2023, Jan, 08 | 12:00 am

Total Knee Replacement in the Varus Knee

Indications

  • End-stage arthritis associated with pain and dysfunction that has failed nonoperative treatment.

    Examination/Imaging

    Physical Examination

  • Gait, alignment, range of motion, and stability are assessed, and a neurovascular exam is performed.

  • Examination of the knee with valgus stress is useful to determine if the varus deformity is fixed or correctable. A correctable deformity may not need a significant medial release intraoperatively.

    Imaging

  • Plain radiographs: anteroposterior (AP) (Fig. 1A), lateral (Fig. 1B), and Merchant’s (Fig. 1C) views are obtained.

 

 

 

A B

 

 

 

C

FIGURE 1

 

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  • Coronal stress radiographs may be helpful to determine ligamentous integrity and the degree to which the varus deformity may be passively corrected (Fig. 2).

    Treatment Options

    • Nonoperative treatment, including physical therapy, activity modification, gait aids, bracing, nonsteroidal anti-inflammatory drugs, analgesics, corticosteroid injections, and hyaluronic acid injections

    • Arthroscopic débridement

    • Unicompartmental knee arthroplasty

    • Proximal tibial osteotomy

     

  • A full-length standing hip-to-ankle view is helpful in determining the overall limb alignment and to template the tibial and distal femoral cuts (Fig. 3).

 

 

 

FIGURE 2 FIGURE 3

 

Surgical Anatomy (Fig. 4A and 4B)

  • Pes anserinus

  • Superficial medial collateral ligament (MCL)

  • Deep MCL

  • Joint capsule

  • Semimembranosus

  • Posterior oblique ligament

     

     

     

     

    Adductor tubercle

     

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    Total Knee Replacement in the Varus Knee

     

    Patellofemoral

    ligament

    Superficial medial collateral ligament

    Anterior joint

    capsule

     

    Gracilis

    Semimembranosus Posterior oblique

     

    Semitendinosus Sartorius (cut)

     

    A

     

    Vastus medialis

    Sartorius (cut)

    Gracilis (cut)

    Semitendinosus (cut)

    Medial patellar retinaculum (cut)

    Semimembranosus

    Deep medial collateral ligament

    Superficial medial collateral ligament

    Capsule

    Gastrocnemius, medial head

    Popliteus

    B

     

     

    FIGURE 4

     

    Positioning

    • The patient is positioned supine on the operating table. All other extremities should be well padded and protected.

    • A tourniquet should be placed high on the thigh.

    • A lateral hip rest (Fig. 5), in conjunction with a foot bump (Fig. 6) or sandbag, can be secured to the table with the knee flexed to 90° to allow ease of positioning of the leg by the assistant intraoperatively (Fig. 7).

    • The presence and degree of a flexion contracture are sometimes difficult to appreciate after draping and should be noted prior to preparation.

       

       

       

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      Total Knee Replacement in the Varus Knee

       

      FIGURE 5

       

       

       

       

      FIGURE 6

       

       

      FIGURE 7

       

       

      P EARLS

      • Pathology (see Video 2)

        • Medial cartilage narrowing

        • Medial bone loss

        • Ligament asymmetry

      • Goals

         

        • Rectangular extension and flexion gaps (Fig. 9)

           

        • Symmetric medial and lateral soft tissue tension (Fig. 10A and 10B; see Video 3)

       

      Portals/Exposures

  • An anterior midline incision is made, and a medial parapatellar arthrotomy is performed (see Video 1).

  • Assess the severity of deformity with valgus stress to determine if the deformity is a passively correctable or fixed deformity.

  • Using a scalpel, perform a subperiosteal elevation of the medial sleeve, including the anterior joint capsule and the deep MCL (Fig. 8).

  • Use a periosteal elevator and a mallet to carefully continue the elevation of the medial sleeve at the metaphyseal flare of the tibia.

     

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    Total Knee Replacement in the Varus Knee

     

    FIGURE 8

     

     

     

    FIGURE 9

     

    Trapezpoidal extension space

     

     

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    Total Knee Replacement in the Varus Knee

     

    A

     

     

    Released ligament medial

    Rectangular symmetric extension space

     

    FIGURE 10 B

    • Place a bent Hohmann retractor in the path created by the elevator.

    • With gentle retraction by the assistant, continue the elevation of the joint capsule sharply with a scalpel at the level of the joint line to the posteromedial corner.

       

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      Total Knee Replacement in the Varus Knee

       

      Procedure

      Step 1: Medial Release (see Video 4)

  • After the medial exposure, the knee should be examined to assess the severity of the varus deformity.

  • If greater medial release is required, the knee can be flexed to gain exposure to the posteromedial corner.

  • With coordinated gentle external rotation of the tibia by the assistant, continued medial subperiosteal elevation can be performed.

  • The semimembranosus insertion can be released at the posteromedial corner (Fig. 11).

    Step 2: Tibial Cut

  • The tibial cut should then be performed before any further releases are made (see Video 5).

  • After the proximal tibial and distal femoral cuts are made, assessment of the extension gap should be performed using a spacer block (Fig. 12) or laminar spreaders.

     

     

     

     

     

    FIGURE 11

     

    FIGURE 12

     

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    Total Knee Replacement in the Varus Knee

     

    Step 3: Superficial MCL Release (see Video 6)

    • If further release is required medially, a ½-inch osteotome can be used with a mallet to perform a controlled subperiosteal release of the superficial MCL (Fig. 13).

      Step 4: Pes Anserinus Release (see Video 7)

    • If still further medial release is required, a straight

½-inch osteotome with a mallet can be used to subperiosteally release the pes anserinus insertion (Fig. 14A and 14B).

 

 

 

 

 

 

FIGURE 13

 

 

 

 

A B

FIGURE 14

 

Medial collateral ligament

Pes anserinus

 

Total Knee Replacement in the Varus Knee

 

Step 5: Lateralization of the Tibial Component with Osteophyte Removal

  • If subtle medial tightness is present, the tension of the medial soft tissue sleeve can be alleviated by positioning the tibial component with a slight lateral bias.

  • A slightly smaller tibial tray size should be selected without significantly compromising adequate tibial coverage.

  • The tray should be positioned as far laterally as possible without lateral overhang (Fig. 15).

  • The uncovered medial aspect of the tibia can be marked (Fig. 16).

  • The medial osteophyte is then removed (Fig. 17).

  • Final tibial preparation can then be performed.

     

     

     

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    FIGURE 15 FIGURE 16

     

     

     

    FIGURE 17

     

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    Total Knee Replacement in the Varus Knee

     

    Postoperative Care and Expected Outcomes

    • With a well-balanced and stable knee, there is no contraindication to full weight bearing and early range of motion.

    • It is imperative for the patient to participate with a physical therapist to work on motion to obtain full extension and maximum flexion, gait training, and muscle strengthening.

    • Patients should use a walker or crutches for approximately 3 weeks, followed by a single cane for an additional 3 weeks.

    • Patients should anticipate feeling “recovered” by 3 months postoperatively.

    • Postoperative radiographs in the AP (Fig. 18A) and lateral (Fig. 18B) views and a full-length standing hip-to-ankle view (Fig. 19) can be used to assess results.

       

       

       

       

       

       

      A

      FIGURE 18

       

      B

       

       

       

       

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      Total Knee Replacement in the Varus Knee

       

      FIGURE 19

       

  • Studies have demonstrated that total knee arthroplasties in knees with severe preoperative angular deformities perform as well as those in deformity-free knees.

 

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Evidence

Dixon MC, Parsch D, Brown RR, Scott RD. The correction of severe varus deformity in total knee arthroplasty by tibial component downsizing and resection of uncapped proximal medial bone. J Arthroplasty 2004;19:19-22.

 

A technique is described of downsizing and lateralizing the tibial component and removing the proximal medial tibia flush with the implant.

 

Engh GA. The difficult knee: severe varus and valgus. Clin Orthop Relat Res. 2003;(416):58-63.

 

Several techniques are described to release soft tissues contributing to fixed varus deformity.

 

Griffin FM, Insall JN, Scuderi GR. Accuracy of soft tissue balancing in total knee arthroplasty. J Arthroplasty 2000;15:970-3.

 

Rectangular flexion and extension gaps can be achieved within 1 mm in 84–89% of patients.

 

Krackow KA, Mihalko WM. The effect of medial release on flexion and extension gaps in cadaveric knees: implications for soft-tissue balancing in total knee arthroplasty. Am J Knee Surg. 1999;12:222-8.

 

A cadaveric study was performed that demonstrated the amount of varus correction with sequential releases of the posteromedial capsule oblique ligament complex, superficial medial collateral ligament, pes anserinus, and semimembranosus tendons.

 

Laskin RS. The Insall Award: Total knee replacement with posterior cruciate ligament retention in patients with a fixed varus deformity. Clin Orthop Relat Res.

1996;(331):29-34.

 

In patients with a fixed varus contracture, use of a posterior cruciate–retaining implant results in increased pain, increased radiolucencies, decreased motion, increased revision rate, and decreased implant survivorship compared to patients with a posterior cruciate–substituting implant design.

 

Ritter MA, Faris GW, Faris PM, Davis KE. Total knee arthroplasty in patients with angular varus or valgus deformities of greater or equal to 20 degrees. J Arthroplasty 2004;19:862-6.

 

Knees with severe preoperative angular deformities perform as well as deformity-free knees and should not be excluded from surgical treatment.