Salvage Procedures: Knee Arthrodesis, Resection Arthroplasty, Amputation

James B. Stiehl, MD, MBA

INTRODUCTION

Complex problems of the knee such as severe trauma, chronic infection, or failed total joint arthroplasty require salvage techniques. This chapter considers current trends and experience with amputation, resection, and knee arthrodesis. My prior chapter discussed the introduction of new surgical techniques to improve the outcomes of knee arthrodesis, and while numbers were small, most series showed successful fusion in over 85% of cases.¹,²,³,⁴,⁵,⁶ It seemed that we were on the verge of eliminating amputations as few were being reported in the literature. However, Big Data has changed all that, and while I can show that we are performing more secondary revision arthroplasties and fewer salvage procedures, arthrodesis, amputation, and resection arthroplasty, all have important roles. The major advance has been to understand our patient’s overall health, and that guides our choice of treatment. Effort will be made to include many of those concepts. We can now profile high-risk and extraordinary-risk patients where the best options may be the unspoken “A” words. Discussion of surgical technique has changed little, but I will try to include as many “pearls” as possible.

INDICATIONS

Primary Arthrodesis

With the evolutionary success of total knee arthroplasty, primary arthrodesis of the arthritic knee has become an unusual operation; however, there are several settings where primary fusion remains an attractive or at least a reasonable option.⁷ The first is a young patient with severe extremity trauma to the knee joint complicated with chronic sepsis and extensor mechanism loss. In this instance, the consideration is to prevent the poor outcome of a potentially functional young male from becoming “depressed, divorced, and destitute.” Knee arthrodesis has been shown by numerous authors to be durable in the long term even if interposing grafts are needed. Wolf et al followed up patients with arthrodesis following tumor limb salvage finding independent ambulation in 86%. At a mean follow-up of 17 years, the majority continued to have satisfactory function.⁸ Bensen et al compared failed knee arthroplasty arthrodesis with primary total knee arthroplasty finding nearly identical SF 36 scores. Physical mobility was better with knee arthroplasty but pain was better with arthrodesis.⁹

Other indications include serious general conditions such as neuropathic Charcot joint. The limb may be insensible, and the patient often has very poor control of knee function due to severe spinal cord involvement or a myelopathic process.¹⁰,¹¹ Knee arthrodesis for treatment of primary malignant bone tumors may be the best option using such augments as autologous grafts or vascularized fibular transplants. Chronic poliomyelitis syndrome is another neurological condition where there is severe instability in extension. For virtually all other circumstances, primary arthrodesis has been displaced by total knee arthroplasty. The functional outcome is significantly inferior with arthrodesis and most older patients will require ambulatory aids such as a cane or crutches, and lifestyle compromise for some may be severe.

Secondary Arthrodesis

The most common current circumstance for arthrodesis is chronic sepsis following total knee arthroplasty in a patient who is not a candidate for reimplantation. This is typically a type B or C host, where the risk of infection recurrence is high, especially when combined with extensor mechanism problems such as patellar tendon rupture. Type B hosts have significant local and systemic factors that impair the normal immune processes. Local factors include chronic lymphedema, major vessel disease, venous stasis, extensive scarring, or radiation fibrosis. Systemic problems include malnutrition, malignancy, extremes of age, hepatic or renal failure, diabetes mellitus, and alcohol abuse. Type C hosts are sufficiently fragile such that undertaking aggressive treatment could endanger the patient. We are particularly concerned about patients who have evidence of chronic malnutrition; become infected from a chronic source such as a stoma, urine, or diverticulum; have multiple organism infections; have chronic
infections that respond poorly to débridement and antibiotic therapy with persistent signs of inflammation; or have life-threatening infections from methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VREC). Inflammatory/nutrition markers such as serum prealbumin, serum albumin, sedimentation rate, C-reactive protein, and depressed lymphocyte counts offer clear estimation of chronic risks. A recent study has shown that there is at least a 50% chance of recurrence following an attempted two-stage débridement and reimplantation of a previously revised total knee for chronic sepsis. Careful judgment is needed for each patient, especially for multiple failed revisions, and close consultation with medical infectious disease specialists is required to balance the risk of long-term antibiotic treatment or suppressive antibiotic therapy versus the surgical choices of fibrous resection arthroplasty, total knee reimplantation, arthrodesis, or amputation. With chronic infections, surgical débridement may create the best end point to eradicate biofilm-forming bacteria, and this may include amputation.

Another important total knee complication that should be considered for knee arthrodesis is the failed extensor mechanism. When combined with periprosthetic joint infection, the balance clearly tips to salvage knee arthrodesis. Friederich et al evaluated the results of 37 such cases, finding that 87% were infection free as follow-up. However, persistent problems with the fusion site required implant removals and the 6-year survivorship table revealed that 74% of implants remained intact. However, the overall clinical results were acceptable considering factors of pain and functional outcome.¹²

Amputation

There are severe circumstances where amputation becomes the best option. Patients with recalcitrant infection, high risk reconstructive options, and serious comorbidities are considered for amputation. The decision is usually multifactorial, but serious skin deficiency problems, arterial calcifications that rule out free tissue transfer, and bone defects that limit bone healing point toward amputation. Patients with morbid obesity, chronic diabetes and other medical issues, multiple failed knee revisions, and deep vein thrombosis should be considered for amputation. Son et al demonstrated that the Charlson comorbidity score was substantially higher in those undergoing amputation versus arthrodesis (hazard ratio for score of 5+ was 2.56 [confidence interval: 2.12-3.14]).¹³ Also, patients undergoing amputation had a higher risk of death from amputation versus arthrodesis, again confirming the fact that these patients are sicker and more fragile.

There is a discussion that most surgeons dread, and that is the need for amputation following a popliteal vessel injury. First, the surgeon should always consider the potential injury to these vessels as they lay directly behind the posterior cruciate ligament that may be incised. Anatomical studies show that the distance is about 10-11 mm from the posterior ledge of the proximal tibia. Placing a Hohmann or Chandler retractor on this ledge virtually eliminates the potential of damaging the vessels but there is no place for saws, drills, or surgical dissection beyond the posterior tibia. If there is a sudden “flood of blood,” quick action is needed including putting up the tourniquet, packing the wound, and calling a vascular surgical consult. That surgeon will usually perform intraoperative arteriograms and will solve the vessel problem. If pulses return and the possibility of compartment syndrome is slight, the surgeon may complete the surgical procedure. Otherwise, the wound should be closed over packing and the leg be observed. Prompt restoration of blood flow is highly effective, but delay beyond 2 hours may lead to a poor outcome. Vigilance, anticipation, and expedient action are the solutions to this problem.

TECHNIQUE

External Fixation⁷,¹⁴

A publication now 20 years old demonstrated 100% solid fusion using an anterior unilateral frame for arthrodesis. This contrasts to the 40% to 80% failure of earlier methods that attempted something near the Charnley compression technique. Inadequate stability, which is the key element, probably explained the large failure rates. I would hesitate to recommend external fixators particularly in older patients with soft osteopenic bone. The best construct is a double frame technique where two or three threaded pin groups are applied proximally and distally in sound cortical bone of the femur and tibia. Optimum apposition with a good degree of compression is desired. Careful pin site care is desired and late bone osteomyelitis is a risk of long-term pin use. Patients are best kept non-weight-bearing for extended periods of 3 to 5 months (Fig. 78-1).

FIGURE 78-1 Failed total knee arthroplasty following chronic sepsis and extensor mechanism loss treated with a double plane external fixation device.

Double Plate Fixation (Nichols)¹⁵

This technique uses two broad AO DCP plates with 10 to 18 holes (average 12 holes). Bone cuts are made such that the normal femorotibial valgus of 7° is restored. One plate is placed anteromedial while the other is anterolateral. Careful contouring of the plates is usually needed. The patella may be osteotomized and applied to the anterior surface of the femur and tibia as a graft. Sepsis requires a two-stage technique with fusion done after 6 weeks of antibiotics. Postoperative management includes a long leg cast until the fusion is ascertained to be solid (average 5.6 months; range 3 to 10). The biggest liability is the fairly extensive amount of dissection that is needed (Fig. 78-2).

Intramedullary Nail Fixation (Stiehl)³

Several different rod configurations have been developed with particular advantages noted with each. My original experience was with a simple Kuntscher nail that was inserted anterograde through a separate incision with the use of a medial AO DCP 10-hole compression plate. This technique is particularly valuable if a long interposing allograft is required as rigid fixation of the graft is essential for union. The patient is placed supine on a fluoroscopic imaging operating table with 45° bump under the affected buttock. The pelvis and lower extremity are draped such that proximal hip exposure will allow entry, and reaming of the femur anterograde is done under fluoroscopic view. It is important to have the fluoroscope placed such that one can follow the nail insertion all the way down the leg, especially distal as rods have passed out of the soft distal tibia. A sterile tourniquet is used to minimize blood loss. The fusion site is entered with a longitudinal anterior knee incision. The knee implant is removed or the previously debrided infected knee is assessed and the fusion site is prepared. At this point, incision is made over the greater trochanter with split of the gluteus medius muscle to expose the piriformis fossa. The proximal femoral canal is entered as for a femoral fracture and a guidewire is passed down to the knee joint. At this point, the surfaces may be cut using the axis of the guide pin to create maximally abutting surfaces. Anterograde reaming is done over the guidewire. Generally, this can be done to 12 or 13 mm which is the nominal size of the tibial reaming and provides a suitable nail size for strength. The guide pin is passed down the tibia and fluoroscopic control is used to make certain that the center of the ankle joint is reached. Depending on the nail used, one may overream 0.5 mm on the tibial side and 1 mm on the femoral side. Nail dimension is determined on the tibial size. Length of the nail is based on guide pin measurement from the tip of the greater trochanter to a point 2 cm above the ankle joint. The bowed fusion nail is then carefully inserted over the guide pin down to the knee joint and passed across to the tibia with an assistant holding the fusion site opposed. The anterior bow of the femoral shaft will determine the position of the nail and tends to direct the nail out the very anterior cortex of the distal femur. One must carefully assess insertion distally into the tibia to prevent perforation and to ensure distal positioning about 2 cm above the ankle joint. The proximal end of the nail should be within 1 cm of the tip of the greater trochanter (Fig. 78-3). At this point, adjunct fixation
may be considered. This may include a 10-hole medial AO neutralization plate, crossed cancellous screws, or proximal and distal locking screws in the nail. Additional bone graft and enhancing substances may be added to the fusion site. Closure of the wound may be problematic because of the shortening of the leg and chronic scar tissue, hence a consideration for avoiding additional plates. Postoperatively, no external splints or casts are needed, but the patient must be non-weight-bearing for 6 to 10 weeks, depending on the progression of healing (Fig. 78-4). I would add that there are many makers of suitable nails, including international groups who may favor the SIGN nail.¹⁶ Importantly, the surgeon must consider specific details of the nail design, and the SIGN nail actually should be inserted through the greater trochanter. Again, I consider this an evolution from earlier methods, and still relevant, but combining intramedullary nailing with an intrinsic compression method that does not add surgical dissection is most desirable.

FIGURE 78-2 A: Healed intra-articular distal femoral and proximal tibial 3C open fracture complicated with extensor mechanism loss and chronic sepsis in a 22-year-old male factory worker. B: Successful double plate fixation after failed attempt at external fixation.

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