Tissue Expansion in Total Knee Arthroplasty

Susan Craig Scott

Stage 1 Expander Insertion

Patients requiring tissue expansion prior to joint replacement are those who have had multiple surgical procedures about the knee. Often these patients have numerous healed incisions whose orientation is varied (Fig. 56–1). Some have been skin grafted; some have scar tissue from healing by secondary intention; some have existing transposed muscle flaps. Most commonly motion is not restricted at the knee, although occasionally the patella has been removed. In addition, a rare patient presenting for tissue expansion has a prosthesis in place.

Indications

The indications for soft tissue expansion have evolved over the last decade.

1. The presence of more than one incision on the anterior surface of the knee and, if parallel, the newer of the parallel incisions is unusable for access to the knee.
   
2. Incisions intersecting on the anterior knee in the prepatellar, infrapatellar, or pretibial region
   
3. Marked varus deformity
   
4. Skin graft present without adherence to underlying bone
   
5. Transposed muscle or musculocutaneous flap present
   
6. Extensor mechanism reconstruction in combination with total knee arthroplasty, where soft tissue may not be adequate to cover the volume increase

Contraindications

Absolute

1. Skin graft present, which is densely adherent to underlying bone or bed with no mobility beneath the graft
   
2. The presence of an open wound or any break in skin integrity
   
3. History of irradiation to the area where expansion is desired
   
4. Coagulation disorder or intercurrent anticoagulation

Relative

1. History of local infection with drainage
   
2. History of deep vein thrombosis in the involved extremity

Physical Examination

1. Multiple incisions present on the anterior knee surface; they are carefully measured and documented; a photograph is helpful.
   
2. Mobile plane between soft tissue and underlying bone or deep musculotendinous structures
   
3. Joint motion may or may not be present; this is not a factor in tissue expansion.

Diagnostic Tests

1. Only routine preoperative testing is required prior to expansion; coagulation is assessed with an international normalized ration (INR) and must be normal.
   
2. If there is any question of skin viability during expander insertion, intravenous fluorescein may be injected to assess circulation.

Special Considerations

1. Certain patients present with unusual local considerations. For example, patients sometimes have a muscle flap transposed to aid in previous healing difficulties. It is possible to place a tissue expander beneath a previously transposed local flap, and expand the flap further, if the elevation and insetting of the flap will not provide adequate cover for the planned procedure.

Preoperative Planning and Timing of Surgery

1. A Tuohy needle is used to inject local anesthesia in the plane of dissection to minimize injury to overlying skin during pocket preparation; this needle has a blunt tip with its opening directed at 90 degrees to the long axis of the needle. The proximal end of the needle has a small divot such that the orientation of the tip opening can be constantly assessed during anesthesia injection.
   
2. The blunt tip orientation is important to avoid skin perforation.
   
3. The blunt tip is advanced as the injection proceeds and the fluid opens the plane ahead of the advancing needle tip.
   
4. Tissue expanders, which are available in a wide variety of sizes and shapes (Fig. 56–2): A rectangular shape is most useful for the front of the knee. Each expander is described by its length, width, and projection when filled to maximum. The length and width determine the fit of the expander in the dissected pocket. Expander projection will determine how much expanded tissue will be produced and is the most important dimension.
   
5. Tenotomy scissors of increasing lengths from 4.5 to 12 inches are useful for pocket dissection.

Anesthesia

1. A very dilute solution of local anesthetic in combina tion with intravenous sedation is used. The formula for the local anesthetic is as follows:
   
   
   
   • Lidocaine 1%, 50 cc
     
   • Epinephrine(1/1000), 1 cc
     
   • Ringer’s lactate 1 L (1000 cc)
   
   
2. The usual expander insertion uses ~300 cc of this solution injected into the areolar space prior to cre ation of the pocket for the expander. An excellent local vasoconstrictive effect can be obtained with this solution visible as skin pallor at the expansions site, and minimizing intraoperative bleeding.

Patient and Equipment Positions

1. The patient is supine during expander insertion.
   
2. A tourniquet is placed prior to preparation and draping of the patient, but it is not routinely inflated during the procedure.
   
3. The drape used is identical to that which is used during joint replacement.

Surgical Procedure

1. The incision that will be used for joint replacement is marked. A 1- to 1.5-inch segment of this incision is used as an access incision for expander insertion.
   
2. The access incision is chosen at a distance from the planned site of the expander so as not to subject this incision to expansion force.
   
3. In addition, the access incision is always placed proximal to the expander; a small amount of fluid is produced by the expander in place over several weeks, and this fluid can leak from the access incision if it is placed distal the expander.
   
4. Local anesthesia is injected; the incision is made, and dissection is carried deep to the subcutaneous fat but superficial to the patella and the musculotendinous structures in the areolar plane, which the injection has defined. A pocket of adequate size to allow the expander to unfold and lie flat is created using scissors of increasing length.
   
5. The pocket is irrigated with antibiotic solution, and pressure is then maintained until bleeding is negligible.
   
6. Drains are rarely used; if needed, a fiberoptic retractor is used to inspect the inside of the pocket, and insulated forceps are used for hemostasis
   
7. The expander is inserted and unfolded; its access port is placed in the subcutaneous tissue proximal to the expander and at a level where the port is well covered by soft tissue, but can be easily palpated through the skin (Fig. 56–3).
   
8. Expander is then injected through the access port; this verifies free flow of saline into and out of the expander.
   
9. Expander is inflated to obliterate any dead space in the pocket (Fig. 56–4).
   
10. Multiple expanders may be used; we have placed up to five expanders in one patient.
    
11. Access incision is closed in layers.

Dressings

1. Extremity is dressed in a soft bulky dressing; an Ace bandage is used for gentle compression.
   
2. We routinely use a knee immobilizer postoperatively, and insist on strict elevation with ambulation limited to bathroom privileges only for the first night after surgery.
   
3. Patients spend the first night after expander insertion in the hospital.

Related posts:

The Subvastus Approach Meniscal Injuries/Repair: Staples Arthroscopic Lateral Retinacular Release Meniscal Injuries/Repair: BioStinger Total Knee Replacement: Pearls of Posterior Cruciate Ligament Substitution Ligament Injuries: Anterior Cruciate Ligament Reconstruction with Hamstring Tendons

Stay updated, free articles. Join our Telegram channel

Join