2.14.1 Introduction

Implant removal is unfashionable, neglected, occasionally disparaged, often delegated to junior surgeons, but full of surprises and traps for the unwary.

2.14.2 Indications for implant removal

We should start from the position that there is no such thing as “routine” removal of an implant. Asymptomatic metalwork is generally best left in situ because all surgical procedures are risky. There must therefore be a reason to advise a patient to accept these risks. These reasons include:

Prominence: Prominent implant, particularly those adjacent to joints such as the LISS plates and plates on the lateral malleolus of an ankle, may impinge on the soft tissues, cause pain, and inhibit movement.

Loosening and failure: An implant that is loose or has broken generally means that the race between biological success (fracture healing) and mechanical failure of the implant has been lost. Fig 2.14-1 illustrates such a case. The implant must be removed before further treatment is possible.

Infection: Most pathogenic organisms have the ability to adhere to the surface of implants and to protect themselves with a mucopolysaccharide envelope or shelter where they cannot be reached by the body’s defences or antibiotics. Organisms in this “colonic” form remain a constant threat for recurrent infection. To eliminate this risk, it is usually necessary for the implant to be removed.

Pain: Pain may be due to prominence, impingement, or occasionally a biological reaction to the implant. Stainless steel implants are more likely to cause such a reaction than titanium implants. It may be difficult to establish the precise reason for pain in the vicinity of an implant and it may be that it is only the resolution of the pain when the implant has been removed that confirms that it was the implant causing pain.

Proximity to growth plate: Metaphyseal implants in children are generally removed because of fears that they may impede or distort bone growth.

To facilitate other procedures: Implanted metal may interfere with or prevent subsequent surgery. For example, a sliding-hip screw in the proximal femur would prevent hip replacement unless it was removed, and a corrective osteotomy for malalignment may be complicated by a previously implanted fixation device. In some fracture nonunions (Fig 2.14-2), the original implant must be removed before the nonunited fracture can be stabilized.

Biological effects of the products of corrosion: All metals corrode, and the products of corrosion are generally biologically active. Some metals corrode more than others. Stainless steel, particularly if of poor quality, corrodes much more than materials such as titanium. Corrosion may be “fretting” or “galvanic.” Fretting corrosion occurs when two metal fragments rub together and release small particles. Galvanic corrosion occurs when an electrical current is established between two components of the metal implant. This is particularly important if different metals are used within the same implant.

Corrosion results in the release of metal ions into solution. These products of corrosion are biologically active. They may cause an allergic reaction and there is concern that prolonged exposure to some metal ions may be oncogenic, although this has not yet been clearly established. This is an important area of research but has no immediate implications for the enormous benefits of using these materials in fracture fixation, although it may be a reason to consider implant removal in younger people.

2.14.3 Risks of implant removal

The general risks of all surgery, including risks of anesthetic, are inevitable. These include infection, wound breakdown, poor scarring, and deep vein thrombosis (DVT).

The specific risks to implant removal are:

Failure to remove implants: this is a disastrous outcome which occasionally reflects a challenging technical difficulty but more often stems from poor planning and inadequate provision of equipment. Broken implants, mainly locking bolts of intramedullary nails, stripped screw heads, cold-welded implants (particularly sliding hip screws manufactured from steel of different quality), and cross-threaded locking screw heads all pose unusual difficulties. These must be anticipated.

Refracture: defects in the bone from removed implants, mostly screws, weaken the bone by 30% or more. Refracture has been reported to occur in 1–3% of patients following implant removal. Patients must be advised to avoid load bearing or impact for up to 12 weeks following implant removal depending on the circumstances. Equally, premature removal may lead to early refracture. Figures given below for timing of fracture removal are only guides. The fracture must first heal.

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  Metaphyseal fractures: 3–6 months

  
  
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  Diaphyseal plates: 12–18 months

  
  
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  Intramedullary nails: 8–24 months

Nerve injury: removal of forearm plates, mainly from the radius, has been linked to a high level of nerve injury.