Above Knee Amputation in the Treatment of Failed Septic Total Knee Arthroplasty

Fig. 21.1

Residual limb after amputation secondary to an infected TKA. Taking into account that surgery was performed 3 weeks before, the stump still shows edema but not hematomas. Note that the stump has an epithelized scar and cylindrical shape. It is well cushioned with soft tissues, without bony prominences, and with an adequate length

Newer techniques of osteointegration have been developed. In this technique a female coupling is inserted into the residual bone of the stump and fixed with cement. The exoskeletal prosthetic system is then united by means of a male coupling inserted into its female counterpart. The major complication is persistent infection requiring ongoing antibiotic suppression. The residual limb can also fracture above the female device inserted into the bone [26].

Stump revision may be required for several indications: bony painful sharp edges, symptomatic neuroma, deficit in soft tissue coverage, need of increasing the length of the residual limb, excessive soft tissues, heterotopic ossification, and adhered scars. All the aforementioned conditions may interfere with the prosthesis fitting process.

The goal of physical medicine and rehabilitation is to encompass the whole process, from surgery to the resumption of independent living. Preoperative evaluation is paramount. Its aims are to determine the best possible level of amputation, to inform the patient about the postoperative rehabilitation process, and to agree the mid- and long-term objectives. It will help diminish the patient’s anxiety about their future and provide adequate patient education.

21.4.1 Prosthesis Fitting Phases

The primary goal of a transfemoral amputee after an infected TKA is to resume functional gait. To achieve this goal, it is paramount to consider three essential phases from the point of view of physical medicine and rehabilitation:

1.

Preprosthetic Phase

In this first phase, the main goals are to get a good control of phantom limb pain and stump edema, an adequate healing of the surgical wound, a well-aligned and well-conformed painless stump, and a good muscular and articular status both of the residual limb and the contralateral limb (Fig. 21.2). These are paramount in order to progress to the second phase. Tools employed to achieve them include the provision of adequate analgesia, daily conforming bandages of the stump (Fig. 21.3), postural recommendations, muscle-strengthening exercises (mainly pelvitrocantheric), and weight bearing on the healthy limb (Fig. 21.4).

Most amputees do not have pain interfering with their quality of life or requiring regular analgesia beyond 6 months after the amputation surgery [27].

It is important to differentiate phantom limb sensation (that does not require treatment) and phantom limb pain. It is common for the distal part of the phantom limb to approach the distal end of the residual limb and then to fully disappear, in a process called telescoping. We must also differentiate ghost limb pain and stump pain. Treatment of these painful conditions is different and has been reported [28]. With ghost limb pain, in addition to pharmacological measures (because it is a neuropathic pain), attention must be paid to potential signs of depression, anxiety, and sleep disturbances. Smoking cessation must also be encouraged [29].

2.

Prosthesis Fitting Phase

Fig. 21.2

Residual limb during the preprosthetic phase. It is painless, with reduced edema, adequate healing of the surgical wound, and well conformed and aligned and with a good articular and muscular status

Fig. 21.3

Shaper bandages of the stump during the preprosthetic phase. They are capelin and ear bandages with decreasing compression that must be put daily. Their objectives are to help cure the surgical wound, reduce the sensation of ghost limb, and provide a cylindrical shape to the stump

Fig. 21.4

Amputee performing monopedestation during the preprosthetic phase. The goals are to maintain patient’s verticality, preserve the alignment of the residual limb, maintain the functional status of the contralateral limb, and reduce the sensation of ghost limb

This must be started as soon as possible, provided the patient fulfills the objectives of the aforementioned phase. In this stage the physician will decide, agreeing with the patient, what components must be part of the prosthesis according to the patient’s expected level of activity. The length of the stump is important. A very short residual limb will provide poor stability and a lower lever arm to propel the prosthesis during swing phase. However, an overlong stump will not allow space for the components of the prosthetic knee. The recommended length to allow the use of prosthetic knees with a microprocessor is 10.2 cm from the articular line of the amputated knee to the bony end of the stump. In this phase it is important to obtain the cooperation of a prosthetic technician with experience in the manufacturing of this type of exoprosthesis. At the time of prescribing the prosthesis for a transfemoral amputee, the following components must be considered (Fig. 21.5):

(a)

Inner liner: This is directly in contact with the stump; it can be made of different materials such as urethane, silicone, or gel. It covers the residual limb and facilitates suspension with the outer liner. It has to be carefully unwound over the residual limb. Moreover, it requires constant care and hygiene, may produce heat, and needs replacement every 6–12 months.
(b)

Outer liner: This is a rigid case, usually made of different thermoplastics or carbon fiber, that picks up the residual limb and serves as a structure of union with the exoskeleton. It is important to mention that in transfemoral amputations, weight bearing is via the ischial spine (in contact with the outer liner), never over the distal part of the stump. Even so, stump pain is usually caused by problems related to the liner. In transfemoral amputees, the usual point of pain is the lateral zone of the distal femoral end which is in contact with the wall of the liner [30]. Other causes of pain are the presence of a neuroma, edema, bony prominences, or vascular claudication.
(c)
Suspension system: There are three types of suspension systems:
Atmospheric: Based on the presence of an air chamber between the surfaces of the two aforementioned liners (inner and outer). Within this category can be included vacuum systems.

Anatomical: Implies that the prosthesis is united to the pelvis by means of a belt system connected to the liner. These are usually employed when an atmospheric suspension system is impossible to use. On occasions these are used when the atmospheric suspension system is not enough to get a good union between the residual limb and the liner, reinforcing this suspension system.

Osteointegration: Eliminates the need for a liner, because it couples the prosthetic components directly with an implant, which is integrated in the bone. Among the reported benefits of this system are facility of use, decrease of energy consumption, and improvement of the range of motion of the hip [31].
(d)

Prosthetic knee: Prosthetic knees are currently divided into those with mechanical control and those with electronic control [32]. Mechanical knees can have one axis or multiple axes, and mechanisms can be of constant friction or hydraulic. Moreover, they have some characteristics that differentiate them such as a manual block, assistance with extension, and weight-activated stance control and stance flexion. The indication for the type of knee will depend on the patient’s functional level and economic considerations. Electronic knees (controlled by a microprocessor) allow a gait with lower attention and lower energy consumption [33]. Some of the reported benefits of this type of knee are facilitation of rising from a seated position and the use of stairs [34]. Another benefit is the decreased load on the healthy knee during stair ascent [35]. Despite the evident advantages of knees with a microprocessor, they require maintenance work, an electric recharging, and imply an added weight and a high economic cost.
(e)

Prosthetic foot and ankle: Prosthetic feet classically have been divided into a number of categories: SACH (solid ankle cushion heel) foot, flexible foot, dynamic response foot, single axis foot, and multiple axes foot. However, the aforesaid categories do not classify their mechanical properties [36]. Moreover, there is no scientific evidence to endorse the prescription of a particular type of foot [37]. It has even reported that feet belonging to the same category do not present the same mechanical properties [38]. At the time of prescribing a particular foot, we must take into consideration the weight it bears and the space needed to accommodate its mechanism. The keel of the foot is its most important component; it is the part of the prosthetic foot that simulates the anatomical structures responsible for providing stability and mobility during support and movement. Modern materials allow the accommodation of the prosthetic foot to the ground and absorb impacts and the return of mechanical energy, to facilitate the takeoff during the gait. The movement that the human ankle usually performs is commonly incorporated into the foot design itself. Hydraulic mechanisms that regulate ankle movement can be employed, controlled by a microprocessor. These sophisticated feet allow the patient to walk with a similar gait to nonamputees [39].

Fig. 21.5

Components of a transfemoral prosthesis: liner, outer lace, suspension system, knee, and prosthetic foot

The choice of components will depend on the level of activity of the patient that is going to use it and also on their esthetic preferences [40]. In every case, the indication must be individualized and agreed by the physician in charge, the patient, and the prosthetic technician.

3.

Post-prosthesis Fitting Phase

The patient must learn to use his/her prosthesis. That is to say, to put it and remove it by himself/herself, reeducate stability in bipedal gait, with or without technical aids (Fig. 21.6). Moreover, the patient must learn how to climb stairs and ramps, as well as get up after a fall. Such training will have to be made in the therapy room with the help of an experienced physiotherapist. In addition, during this phase the patient must be instructed on the need of adaptations at home to facilitate the activities of daily living in an autonomous way and reduce the risk of accidents.