Operative Techniques in Orthopaedic Surgery (4 Volume Set) 1st Edition

106. Revision Total Knee Arthroplasty With Extensor Mechanism Repair

Fabio Orozco and Alvin Ong

DEFINITION

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

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

images 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

images 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.

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

images 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.

images The fibers of the vastus lateralis muscle expand to the superolateral border of the patella and proximal tibia to form the lateral retinaculum.

images The fibers of the vastus medialis muscle insert into the superomedial border of the patella and tibia to form the medial retinaculum.

PATHOGENESIS

images The etiology of extensor mechanism disruption is multifactorial.

images Factors associated with patellar tendon rupture include:

images Difficult exposure in a stiff knee

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

images Manipulation for the treatment of limited motion

images Revision TKA

images Malrotation of the components

images Overly aggressive postoperative physical therapy

images Distal realignment procedures

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

images Systemic corticosteroid use

images Diabetes mellitus

images Chronic renal insufficiency

images Parkinson disease

images Gout

images Morbid obesity

images Multiple intra-articular corticosteroid injections

NATURAL HISTORY

images Patellar tendon ruptures are difficult to treat.

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

images Augmentation with autograft or allograft tissue often is required.

PATIENT HISTORY AND PHYSICAL FINDINGS

images 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

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

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

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

DIFFERENTIAL DIAGNOSIS

images Patellar fracture

images Quadriceps rupture

images Patella contusion

images Patellar tendinitis

images Prepatellar bursitis

NONOPERATIVE MANAGEMENT

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

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

images

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

images Contraindications for surgical reconstruction include:

images Infection

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

images 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.

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

SURGICAL MANAGEMENT

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

images Direct suture or staple repair alone is often unsuccessful.

images 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.

images In this chatper, 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

images Initial evaluation of the patient

images History

images Physical examination of the knee

images Radiographs

images 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.

images Order the Achilles tendon allograft.

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

images Before anesthesia induction, the allograft is inspected visually to ensure that the specimen is adequate. A distal calcaneus bone allograft measuring at least 3 cm must be attached to the Achilles tendon.

images

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

Positioning

images We use a laminar-flow operating room.

images The patient is placed supine on a radiolucent table.

images A regular pneumatic tourniquet around the thigh is used.

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

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

images 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.

images Previous incisions are marked (FIG 2).

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

TECHNIQUES

APPROACH

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

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

images  The retinaculum and extensor mechanism are exposed.

images  The tendon rupture is evaluated.

images  A midline incision is performed through the patellar tendon.

images  Medial and lateral flaps of retinaculum are created.

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

images

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

images  Create two parallel tunnels trough the patellar bone (TECH FIG 2A).

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

images  The repair is augmented with the use of no. 1 Vicryl in an interrupted figure 8 technique (TECH FIG 2D).

images

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 of no. 1 Vicryl in an interrupted figure 8 technique.

PREPARATION OF THE TIBIA AND ALLOGRAFT

images  A small saw is used to make a rectangular cavity 2.5 cm × 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).

images  The Achilles tendon allograft is then prepared.

images

TECH FIG 3  A rectangular cavity is made in the proximal part of the tibia.

PREPARATION AND INSERTION OF THE CALCANEAL BONE BLOCK

images  The calcaneal bone block is cut to match the created rectangular space in the proximal tibia (TECH FIG 4A,B).

images  The bone block is gently impacted into the proximal tibia (TECH FIG 4C).

images  Two 4.5-mm screws, angled to avoid the tibial component, are used to secure the bone block to the tibia (TECH FIG 4D,E).

images

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

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

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

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

images  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).

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

images

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 extensor mechanism.

Wound Closure

images  Subcutaneous tissues are closed in routine fashion.

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

images  A knee immobilizer is applied with the knee in extension.

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

images

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

images

POSTOPERATIVE CARE

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

images Staples are removed 3 weeks after surgery.

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

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

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

OUTCOMES

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

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

COMPLICATIONS

images Graft failure

images 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.



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