Revision Total Knee Arthroplasty With Extensor Mechanism Repair

DEFINITION

• Patellar tendon rupture following total knee arthroplasty (TKA) is a devastating complication with a prevalence of 0.17% to 2.5%.1,2

• The patellar tendon is involved more commonly (0.22%) than the quadriceps tendon (0.1%).

• Despite reports of encouraging results following direct repair in native knees, attempts at primary repair following TKA rarely are successful in restoring extensor function.

  ANATOMY

• The patellar tendon connects the tibia and the patella. It originates at the inferior pole of the patella and inserts onto the tibial tuberosity. It is about 5 to 6 cm long and 3 cm wide.

• The extensor mechanism of the knee begins proximally as the quadriceps femoris muscle.

• Anteriorly, the fibers of the rectus femoris tendon traverse the patella and insert on the tibial tubercle inferior to the patella as the patellar tendon.

• The fibers of the vastus lateralis muscle expand to the super-olateral border of the patella and proximal tibia to form the lateral retinaculum.

• The fibers of the vastus medialis muscle insert into the su-peromedial border of the patella and tibia to form the medial retinaculum.

  PATHOGENESIS

• The etiology of extensor mechanism disruption is multifactorial.

• Factors associated with patellar tendon rupture include:

  • Difficult exposure in a stiff knee

  • Extensive release of the patellar tendon at the time of surgical exposure

  • Manipulation for the treatment of limited motion

  • Revision TKA

  • Malrotation of the components

  • Overly aggressive postoperative physical therapy

  • Distal realignment procedures

• Some comorbid conditions may predispose patients to extensor mechanism rupture:

  • Systemic corticosteroid use

  • Diabetes mellitus

  • Chronic renal insufficiency

  • Parkinson disease

  • Gout

  • Morbid obesity

  • Multiple intra-articular corticosteroid injections

    NATURAL HISTORY

• Patellar tendon ruptures are difficult to treat.

• Despite encouraging results reported following direct repair in native knees, attempts at primary repair following TKA rarely are successful in restoring extensor function.

• Augmentation with autograft or allograft tissue often is required.

  PATIENT HISTORY AND PHYSICAL FINDINGS

• Patients with rupture of the patellar tendon present with localized pain, palpable loss of patellar tendon tension during active knee extension, extensor lag, and hemarthrosis.

  IMAGING AND OTHER DIAGNOSTIC STUDIES

• Anteroposterior (AP) and lateral radiographs of the knee should be obtained.

• Comparison with either immediate postoperative or preoperative films is helpful to establish the diagnosis of a complete rupture of the patellar tendon.

• Patella alta will be present and can be evaluated by comparison with earlier radiographs (FIG 1).

  DIFFERENTIAL DIAGNOSIS

• Patellar fracture

• Quadriceps rupture

• Patella contusion

• Patellar tendinitis

• Prepatellar bursitis

  NONOPERATIVE MANAGEMENT

• There is very little role for nonsurgical treatment of patellar tendon ruptures.

• For the rare person with a partial patellar tendon tear with maintenance of patellar height, cast or brace immobilization in

FIG 1 • Knee lateral radiograph demonstrating characteristic patella alta seen in patellar tendon rupture.

full extension for 6 weeks followed by physical therapy to regain motion and strength may be appropriate. Progress must be slow to allow for tendon-to-bone healing. Strengthening exercises should be delayed for at least 3 months.

• Contraindications for surgical reconstruction include:

  • Infection

  • Inability to comply with postoperative immobilization and the physical therapy program

• For these rare instances, cast or brace immobilization in full extension for 6 to 8 weeks followed by a physical therapy program to regain motion and strength may be appropriate.

• Progress must be slow, and strengthening exercises should be delayed for at least 3 months.

  SURGICAL MANAGEMENT

• A deficient extensor mechanism in association with a TKA poses a very challenging problem.

• Direct suture or staple repair alone is often unsuccessful.

• Options for management of patellar tendon rupture after TKA include direct repair, with augmentation with an autogenous semitendinosus tendon graft; an Achilles or whole patellar tendon allograft; or a synthetic ligament.

• In this chapter, we describe the technique that we use in our institution, consisting of reconstruction with Achilles tendon allograft with or without augmentation with an autogenous semitendinosus tendon graft.

  Preoperative Planning

• Initial evaluation of the patient

  • History

  • Physical examination of the knee

  • Radiographs

• Previous operative reports should be obtained. The surgeon should be ready to perform revision surgery of any of the components if there is evidence of malrotation or malalignment.

• Order the Achilles tendon allograft.

  • Fresh-frozen allografts are preferable to freeze-dried allografts

• Before anesthesia induction, the allograft is inspected visually to ensure that the specimen is adequate. A distal calcaneus

   

   

   

   

  FIG 2 • Patient in supine position, with previous incision marked.

   

  bone allograft measuring at least 3 cm must be attached to the Achilles tendon.

  Positioning

• We use a laminar-flow operating room.

• The patient is placed supine on a radiolucent table.

• A regular pneumatic tourniquet around the thigh is used.

  • Alternatively, if the incision extends too proximally, a sterile tourniquet can be used.

• The leg is prepared and draped in the standard sterile fashion for joint replacement surgery.

• Fluoroscopic equipment is in the room with a technician available in case it becomes necessary to use it: eg, for judgment of the joint line, preparation of the tibial box, or placement of the screws to avoid the tibial component.

• Previous incisions are marked (FIG 2).

• The pneumatic tourniquet is inflated (usually to 250 mm Hg) after the leg has been exsanguinated with an Esmarch bandage.

   

   

   

  TECHNIQUES

   

  APPROACH

  • Because the patient already has had a total knee replacement in the past, the previous incision should be used.

  • The dissection is carried down in the midline with conservative elevation of skin and subcutaneous flaps.

  • The retinaculum and extensor mechanism are exposed.

  • The tendon rupture is evaluated.

  • A midline incision is performed through the patellar tendon.

  • Medial and lateral flaps of retinaculum are created.

  • The joint is drained of any hematoma and irrigated using pulsatile lavage (TECH FIG 1).

     

    TECH FIG 1 • Medial and lateral sleeves have been created, allowing direct exposure to the anterior aspect of the tibia and tibial tubercle.

     

    PRIMARY REPAIR   A B C   TECH FIG 2 • A. Two parallel tunnels are made through the patellar bone. B,C. A heavy no. 2 nonabsorbable suture is used to perform the primary repair in a running, locked fashion. D. The repair is augmented with the use D of no. 1 Vicryl in an interrupted figure 8 technique.	TECHNIQUES
    PREPARATION OF THE TIBIA AND ALLOGRAFT × 1.5 cm × 1 cm in the proximal part of the tibia slightly distal and medial to the original insertion site of the patellar tendon (TECH FIG 3).   A B C   TECH FIG 3 • A rectangular cavity is made in the proximal part of the tibia.
    PREPARATION AND INSERTION OF THE CALCANEAL BONE BLOCK (TECH FIG 4C).

    • Create two parallel tunnels trough the patellar bone ■ The repair is augmented with the use of no. 1 Vicryl in an (TECH FIG 2A). interrupted figure 8 technique (TECH FIG 2D).

    • Use heavy no. 2 nonabsorbable suture in a running, locked fashion (TECH FIG 2B,C).

    • A small saw is used to make a rectangular cavity 2.5 cm ■ The Achilles tendon allograft is then prepared.

    • The calcaneal bone block is cut to match the created rec- ■ Two 4.5-mm screws, angled to avoid the tibial compo-tangular space in the proximal tibia (TECH FIG 4A,B). nent, are used to secure the bone block to the tibia

    • The bone block is gently impacted into the proximal tibia (TECH FIG 4D,E).

     

  •  

     

    TECHNIQUES

     

    D

     

    TECH FIG 4 • A,B. The calcaneal bone is cut to match the created rectangular space in the proximal tibia. C. The calcaneal bone block is gently impacted into the proximal tibia. D,E. The calcaneal bone block is fixed to the proximal tibia with the use of two 4.5-mm screws.

     

    PLACEMENT OF THE ALLOGRAFT

  • The Achilles tendon is draped over the anterior tibia and patella while the knee is positioned in full extension.

  • Apply enough tension to the allograft to keep it taut and unwrinkled.

  • The most proximal part of the Achilles tendon allograft is cut to obtain a rectangular patch (TECH FIG 5A).

     

  • The rectangular patch is used to augment the attempted primary repair, and is sutured in place with no. 1 Vicryl, in an interrupted fashion (TECH FIG 5B).

  • The Achilles graft is attached to the underlying extensor mechanism with no. 2 nonabsorbable sutures, in an interrupted fashion (TECH FIG 5C,D).

     

     

     

    TECH FIG 5 • A. The Achilles tendon allograft is cut to obtain a rectangular patch. B. The rectangular patch is used to augment the attempted primary repair. C,D. The Achilles graft is attached to the underlying

    D extensor mechanism.

     

     

     

     

    PEARLS AND PITFALLS

    Indications Graft

     

    Revision of total knee components

    • Primary repair of patellar tendon ruptures following TKA rarely is successful, and in most cases augmentation with autograft or allograft tissue is required.

    • A fresh-frozen, nonirradiated Achilles allograft with calcaneal bone is required.

    • Before anesthesia induction, visually inspect the allograft to ensure that it is adequate, with at least 3 cm distal calcaneus bone allograft attached to the Achilles tendon.

    • Be ready to perform revision surgery of the total knee components if malrotation or loosening is present.

     

     

    WOUND CLOSURE

    Subcutaneous tissues are closed in routine fashion.

    The skin is closed with staples and a compression dressing applied. The tourniquet is deflated.

    A knee immobilizer is applied with the knee in extension.

    Postoperative anteroposterior and lateral radiographs of the knee are obtained in the postoperative care unit (TECH FIG 6).

    TECH FIG 6 • Postoperative AP and lateral radiographs of the knee. A

    B

     

    TECHNIQUES

     

    POSTOPERATIVE CARE

    • The knee is immobilized in full extension for 4 weeks, using a hinged knee brace locked in 0 degrees of extension.

    • Staples are removed 3 weeks after surgery.

    • A brace is used to allow 30 degrees of flexion for 4 weeks.

    • Then a brace is used to allow 60 degrees of flexion for 4 more weeks.

    • A progressive controlled increase in flexion and strengthening exercises is allowed after 12 weeks.

       

      OUTCOMES

    • Short-term results are encouraging, but residual extensor lags of 5 to 20 degrees or more are common.3,4

    • Longer-term follow-up of patients with Achilles allograft reconstruction of patellar tendon ruptures is required.

COMPLICATIONS

• Graft failure

• Infection

   

  REFERENCES

  1. Lynch AF, Rorabeck CH, Bourne RB. Extensor mechanism complications following total knee arthroplasty. J Arthroplasty 1987;2: 135–140.

  2. Cadambi A, Engh GA. Use of a semitendinosus tendon autogenous graft for rupture of the patellar ligament after total knee arthroplasty: a report of seven cases. J Bone Joint Surg Am 1992;74A:974–979.

  3. Crossett LS, Sinha RK, Sechriest VF, et al. Reconstruction of a ruptured patellar tendon with Achilles tendon allograft following total knee arthroplasty. J Bone Joint Surg Am 2002;84A:1354–1361.

  4. Rand JA. Extensor mechanism complications after total knee arthroplasty. Instr Course Lect 2005;54:241–250.