Total Knee Arthroplasty: Medial Parapatellar and Extensile Approaches



Total Knee Arthroplasty: Medial Parapatellar and Extensile Approaches


Michael R. Dayton, MD

Giles R. Scuderi, MD


Dr. Dayton or an immediate family member serves as a paid consultant to or is an employee of Exactech, Inc. and Smith & Nephew; has received research or institutional support from Exactech, Inc. and Stryker; and serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons and the American Orthopaedic Association. Dr. Scuderi or an immediate family member has received royalties from Biomet and Zimmer; is a member of a speakers’ bureau or has made paid presentations on behalf of Biomet, Convatec, Medtronic, Pacira, and Zimmer; serves as a paid consultant to or is an employee of Acelity, Biomet, Medtronic, Pacira, and Zimmer; has stock or stock options held in Force Therapeutics; has received research or institutional support from Pacira; and serves as a board member, owner, officer, or committee member of Operation Walk USA.

This chapter is adapted from Incavo SJ, Dayton MR, Exaltacion JJF: Total knee arthroplasty via the medial parapatellar approach, in Flatow E, Colvin AC, eds: Atlas of Essential Orthopaedic Procedures. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2013, pp 341-344 and Seidenstein A, Scuderi S, Scuderi GR: Revision total knee arthroplasty via quadriceps snip, in Flatow E, Colvin AC, eds: Atlas of Essential Orthopaedic Procedures. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2013, pp 359-362.



A standard anterior midline skin incision with a medial parapatellar arthrotomy continues to be the most widely used method of exposure for total knee arthroplasty (TKA). The extensor mechanism of the knee, which is composed of the quadriceps muscle and tendon, patella, and patellar tendon, comprises a complex interaction of structures providing continuity for effective knee function. Proper preservation of the extensor mechanism is vital to successful recovery in TKA. The main advantage of the anterior approach to the knee is that it provides excellent visualization and access to the distal femur, proximal tibia, and patella. Although not extensile in the classic sense, it is more extensile than most approaches for TKA.






ALTERNATIVE APPROACHES

Surgical approaches that vary from the medial parapatellar approach must be able to satisfactorily allow
soft-tissue releases that correctly align the knee (Table 1). While allowing appropriate tissue releases, the approach must also avoid undesirable loosening or attenuation of tissue in areas already weakened by disease.


Subvastus Approach

Although the original description of this technique dates back to 1929, it has been recently used with increasing popularity as described by Hoffman.5 Similar indications exist for this approach as for the medial parapatellar. Theoretical advantages include decreased patellar subluxation and vascular devitalization. This remains a topic of debate. Disadvantages include the potentially increased technical difficulty, particularly in muscular patients and in short individuals.


Midvastus Approach

The midvastus approach emerged in popularity in the 1990s. This technique, theoretically combining advantages of the medial parapatellar and subvastus approaches, divides the vastus medialis obliquus (VMO) in line with the fibers in their midsubstance.6 A unique feature of this approach, in contrast to the medial parapatellar, is the lack of disruption of the vastus medialis insertion into the quadriceps tendon. Another theoretical advantage of this muscle splitting approach with regard to healing potential is that the quadriceps tendon receives its nutrition mainly from the overlying paratenon and soft tissue and takes more time to heal. Medial capsular advancement may be difficult to perform with this approach at the time of closure. Compared with the subvastus approach, however, this option allows easier eversion and lateral displacement of the patella. Both of these techniques are relatively contraindicated in muscular and short patients, patients with previous high tibial osteotomy, previous revision surgery, or aggressive ossific osteoarthritis.


Lateral Parapatellar

This approach is most commonly used in the presence of valgus knee deformity, where lateral intra-articular adhesions or contractures may be present.7 This approach may also be useful when lateral retinacular release is necessary. Laterally based dissection avoids the attenuation of medial tissue that accompanies medial exposure. The lateral tissue, however, is considerably thinner in the capsule, potentially hampering the integrity of the capsular closure. This is a more technically demanding exposure, particularly given the inconsistency with which valgus knees may present. Anatomy is reversed with this approach, and difficulty may be encountered with medial patellar reflection even in the primary total knee setting since the tibial tubercle is lateral to the midline of the tibia. Medial patellar reflection may also be difficult in the setting of revision TKA.


TECHNIQUE


Medial Parapatellar


Room Setup/Patient Positioning

The patient is placed in the supine position, with a bump under the ipsilateral hip if excessive lower extremity external rotation is present. A device to alternately hold the foot in flexion and extension may be helpful. Application of a proximal thigh tourniquet is standard, and routine prep and drape should allow full exposure of relevant anatomy and landmarks, including tibial tubercle, patella, and distal quadriceps.


Instruments/Equipment/Implants

The medial parapatellar approach generally does not require specific instrumentation or equipment. Some retraction tools, however, may be very helpful. A bent Hohmann is useful for lateral tissue distraction whether the patella is everted or not. A marking tool may be helpful to note the extent of the arthrotomy from the medial side of the quadriceps tendon and medial border of the patella (ensuring at least 5 mm from the medial patellar edge) distally to the medial border of the patellar tendon. This is to ensure reapproximation in identical points at time of closure. In cases of a tight extensor mechanism, a pin through the patellar tendon and into the proximal tibia may be helpful to avoid avulsion of the former from its attachment into the tibial tubercle. If extremely tight, however, the surgeon should not hesitate to employ the use of an extensile technique.


Surgical Technique

With the knee in extension, the anterior skin incision is marked 4 cm proximal to the patella to 1 cm distal to the tibial tubercle (Figure 2, A). The knee is placed in the flexed position for the skin incision (Figure 2, B). Often, with the knee flexed, the entire length of the marked skin incision is not entirely necessary because of the stretching of the skin. Enough proximal incision should be used to provide exposure of at least 2 to 3 cm of the quadriceps tendon. The dissection should occur through the fat just deep to the muscle fascia to minimize disruption to the skin blood supply (Figure 3). Medial and smaller lateral full thickness skin flaps are developed. The arthrotomy is then started 2 to 3 cm proximal to the patella curving along the medial patella and then parallel to the patellar ligament to the tibial tubercle. The arthrotomy should maintain a 5 mm cuff of soft tissue lateral to the vastus medialis insertion and medial to the patella and patellar ligament (Figure 4).

The knee is then extended and the proximal medial tibia is exposed by elevating the medial capsular flap and deep MCL from the bone to the mid coronal plane for most cases (Figure 5). If more medial release is required

this can be continued further to the posteromedial corner of the knee joint. The anterolateral tibia is exposed by retracting the patellar ligament anteriorly (Figure 6). The patella can then be subluxated laterally (Figure 7) or everted (Figure 8) when the knee is flexed with care being taken to not place undue tension on the patellar tendon insertion. A Hohmann retractor is placed under the lateral meniscus after the anterior portion of this has been cut. If additional lateral exposure is desired after patellar eversion, the patellofemoral ligament can be cut in its midsubstance with gentle retraction by the lateral retractor (Figure 9).








TABLE 1 Results for Various Arthrotomy Techniques Versus Medial Parapatellar Approach


































































Author(s)/Year


Number of Knees


Procedure or Approach


Mean Patient Age (Range)


Mean Follow-up (Range)


Results


Dalury and Jiranek (1999)


48 (24 knees on each group)


Bilateral TKA: midvastus vs. paramedian


70


12 wk


Decreased early pain, time to straight leg raise (SLR), increased strength in midvastus


No differences in releases, range of motion (ROM)


White et al (1999)


218 (109 knees each group)


Bilateral TKA: midvastus vs. medial parapatellar


68 (44-87)


6 mo


Decreased time to SLR at 8 d, decreased pain up to 6 wk with midvastus; increase in releases with medial parapatellar. No differences in ROM, estimated blood loss (EBL), tourniquet time, SLR at 6 mo


Parentis et al (1999)


51 (22 midvastus, 29 medial parapatellar)


Vastus splitting (midvastus) vs. medial parapatellar


68.2 (midvastus)


65.5 (medial parapatellar)


5.8 mo


Increased lateral release, EBL with medial parapatellar. 43% abnormal electromyogram with midvastus only. No differences in ROM, knee scores, tourniquet time, proprioception or patellar tracking


Matsueda and Gustilo (2000)


336: 169 medial parapatellar (1988-92); 167 subvastus (1992-96)


Medial parapatellar vs. subvastus


67 (30-88) for medial parapatellar


69 (32-86) for subvastus


6 mo


Decreased lateral release, increased central patellar tracking with subvastus. No difference in ROM, stair-climbing, knee scores


Note: Groups done in different time periods


Keating et al (1999)


200 (100 knees in each group)


Bilateral TKA: midvastus vs. medial parapatellar


70.23 (42-86)


Post-op day 3 (discharge)


No differences in lateral release, POD 2 ROM, discharge day ROM, day able to do SLR, leg circumference, extensor lag


Lin et al (2008)


60 patients (80 knees, 40 in each group)


Minimal incision medial parapatellar vs. quadriceps sparing (QS)


MP: 70.2


QS: 69.6


2 mo


With QS TKA, tourniquet and surgical times were lengthened, varus postoperative alignment tended to increase. Muscle strength, post-op pain, and functional outcomes did not differ


Liu et al (2014)


Meta-analysis: 2451 TKAs in 32 RCTs


Midvastus vs. subvastus vs. medial parapatellar


Mean age range: 62.5 to 75


1 wk to 3 y


Midvastus better in pain and ROM at 2 wk, subvastus better ROM, SLR, and absence of retinacular release at 1 week. Midvastus associated with longer surgical time


Berstock et al. (2018)


Meta-analysis: 1893 primary TKAs in 20 RCTs


Medial subvastus vs. medial parapatellar


Range: 57 to 76


Day 0 to 78 mo


Superior results for subvastus for SLR, pain day 1, ROM at 1 wk, and decreased lateral release, perioperative blood loss, longer surgical time. No technique difference in long-term follow-up

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Feb 2, 2020 | Posted by in ORTHOPEDIC | Comments Off on Total Knee Arthroplasty: Medial Parapatellar and Extensile Approaches
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