Exposures for Revision Knee Arthroplasty

Introduction

The number of revision total knee arthroplasty (TKA) procedures is expected to increase exponentially in the coming decades, and surgeons must be prepared to meet the demand. Understanding the basic techniques to facilitate exposure in revision TKAs is an essential skill. Adequate exposure allows for the safe removal of well-fixed femoral and tibial components and minimizes the associated risks of fracture and extensor mechanism injury.

In many cases of exposure for revision TKA, adequate visualization can be achieved with the steps described in this chapter. For example, an extended incision with an aggressive synovectomy and resection of the pseudocapsule, reestablishment of the medial and lateral gutters, and thorough débridement of the scar and pseudocapsule on the deep surface of the extensor mechanism usually provides suitable exposure. A quadriceps snip can be added to improve visualization, but in some cases, this is not enough. In revisions performed in the setting of significant arthrofibrosis, infection, or patella baja, it may be difficult to obtain access to the femoral and tibial components for safe removal and reconstruction.

A more extensile approach is necessary for the revision of a stiff TKA when the initial steps prove inadequate. The approach involves violating the extensor mechanism through the quadriceps tendon proximally or through the patellar tendon and tibial tubercle distally. The V-Y quadricepsplasty ( V-Y plasty) and the tibial tubercle osteotomy (TTO) are the two extensile exposures most commonly used.

Indications and Contraindications

Because of the progressive pain, instability, and radiographic evidence of significant femoral osteolysis, revision TKA was recommended for the patient described in Case 1. Knee aspiration was not performed because she had normal serum erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values, and there was a plausible explanation (i.e., osteolysis) for her effusion and pain.

An extensile exposure for revision TKA becomes necessary when inadequate component visualization and access limits the surgeon’s ability to safely remove the components and perform the reconstruction. Undue stress and retraction on the extensor mechanism can lead to patellar tendon avulsion, and it is better to preemptively extend the exposure with a V-Y plasty or a TTO in those cases to avoid complications.

A V-Y plasty is performed by extending the superior extent of the medial arthrotomy back down along the lateral border of the quadriceps tendon and vastus lateralis muscle toward the superior pole of the patella. The superior portion of the extensor mechanism can be reflected distally and laterally, improving exposure of the knee joint. Adequate exposure usually is obtained with this technique. Postoperative range of motion is limited to allow adequate extensor mechanism healing, which otherwise can lead to more profound extensor lag and extensor mechanism scarring and stiffness. Therefore the V-Y plasty should be used only if necessary.

The TTO is an alternative extensile exposure technique in which a long segment of anterior tibial cortical bone (at least 8 cm) is elevated and hinged laterally with preservation of the muscular soft tissue attachments to preserve vascularity to the fragment. With adequate repair, some surgeons advocate no restrictions in the postoperative period, but others limit knee flexion with a hinged knee brace during the initial 6 weeks postoperatively based on the observed intraoperative tension on the osteotomy fragment.

The TTO and V-Y plasty provide excellent exposure for revision knee surgery. We favor the TTO whenever possible. We tend to place fewer restrictions on patients postoperatively when a TTO is performed and have found fewer problems with extensor lag when this technique is used instead of V-Y plasty. Biomechanical studies have shown higher tensile loads on the quadriceps tendon during knee extension than on the patellar tendon, which makes the TTO theoretically advantageous over the V-Y plasty.

Equipment

Standard equipment for leg positioning and exposure was used in Case 1. Surgical draping should extend far beyond the previous surgical incisions (at least 10 to 15 cm) because the incision during revision TKA is often extended to improve exposure and visualization. Standard tissue rakes and retractors were incorporated in this case, and no special instrumentation was necessary. We prefer to use flexible osteotomes and a reciprocating saw for the removal of well-fixed TKA components.

Standard equipment for leg positioning and exposure should be available for routine revision TKA surgery, as in Case 2. Surgical draping should always extend far beyond the previous scar, especially distally along the tibia, in case a TTO is needed. In addition to the standard retractors and equipment used for routine exposure, an oscillating saw with a thin blade and a pencil-tip bur should be available if a TTO becomes necessary. Broad, flat, straight and curved osteotomes should be available for completion of the osteotomy. A V-Y plasty does not require additional special equipment or instrumentation.

Surgical Techniques

Knee Exposure With a Quadriceps Snip

Anatomy and Approaches

Previous incisions around the knee often dictate the location of the incision for revision TKA. Because the blood supply to the skin flaps around the knee arise medially from branches of the saphenous artery and extend in a lateral direction immediately superficial to the deep fascia around the knee, the lateral-most incision should be used if more than one incision exists. The skin flaps should be made as thick as possible, and extension of the previous incision several centimeters proximally and distally can enable identification of a virgin tissue plane to help achieve the appropriate depth of flaps in the bed of subcutaneous scar tissue. Skin necrosis is a devastating complication after revision knee surgery and may require muscle flap coverage and skin grafting by a plastic surgeon. In the setting of multiple incisions around the knee, we recommend consulting a plastic surgeon, which helps in operative planning and in making the patient understand the potential risk and the treatment necessary if a serious complication such as this were to arise postoperatively.

For revision TKA, the arthrotomy of choice is a medial parapatellar arthrotomy. In straightforward revision TKA cases with good preoperative motion and without extensive scar tissue, this is often the only fascial or retinacular incision that is necessary. In cases that are more difficult (e.g., stiffness, arthrofibrosis, infection, patella baja), the standard medial parapatellar arthrotomy easily can be converted to more extensile approaches. The best-described extensile approaches include the quadriceps snip, the quadriceps turndown, and the TTO. Case 1 highlights the use of the quadriceps snip to help facilitate exposure.

Examination and Imaging

Examination of the 68-year-old patient described in Case 1 found a passive knee range of motion of 0 to 110 degrees of flexion with a firm end point. In the coronal plane, she had about 10 degrees of motion with good end points with varus and valgus stress and neutral mechanical alignment. The previous midline anterior incision was well healed, and she had no skin abnormalities. Her preoperative radiographs showed well-fixed, cemented, posterior-stabilized TKA components with femoral osteolysis (see Fig. 10.1 ).

Procedure: Revision Knee Exposure With a Quadriceps Snip

Step 1. Skin Incision and Flap Elevation

The midline incision of the primary TKA was used and extended proximally and distally by 2 to 3 cm to enable identification of the tissue plane just superficial to the deep fascia. Deep flaps were elevated medially and laterally, exposing the quadriceps tendon proximally, the vastus medialis muscle medially, and the vastus lateralis muscle laterally ( Fig. 10.4 ). These flaps should be mobilized down to the level of the tibial tubercle and patellar tendon insertion.

Step 2. Initial Arthrotomy

In Case 1, a medial parapatellar arthrotomy was performed beginning 5 to 6 cm above the superior pole of the patella and extending around the medial border of the patella down along the medial border of the patellar tendon and tibial tubercle. A small cuff of medial retinacular tissue was left between the arthrotomy and the medial border of the patella for closure.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here