Surgery for removal of metallic implants after fracture union: Is it necessary?

Surgery for removal of metallic implants after fracture union: Is it necessary?

                                   Dr. KS Dhillon, MBBS, FRCS, LLM

Introduction

After fracture union metallic implants used for stabilization of the fracture serves no purpose, hence in the past, it was advocated that all such implants should be removed. This was partly due to fears of corrosion associated with the commonly used stainless steel alloy implants. However, subsequent research found such claims to be unfounded.

There are two broad class of fixation devices used in orthopaedic surgery for fixation of limb bones. The first group consists of wire or pins and the other includes screws, plates, and nails. In the past, most of the implants were made of stainless steel alloy. Now, however, titanium alloy implants are becoming more popular.

There are no clear guidelines in the medical literature on indications for removal of metallic internal fixation devices after fracture union. Surgeons have been making decisions about implant removal arbitrarily because of lack of evidence-based literature to guide them. The general rule has been that all wires should be removed while plates, nails, and screws may or may not be removed depending on prevailing circumstances.

The presence of metallic implants in the body usually does not produce any symptoms. However, under some circumstance, they can be a source of pain and or limitation of movement of the joints. In such circumstances, doctors are often compelled to remove the implants although not all such patients will be relieved of their symptoms after the surgery. Surgery for removal implants is not as innocuous as we often assume.

This review will probe what the current state of knowledge is regarding the need for implant removal after fracture union.

Types of implants used for internal fixation of limb fractures

Kirschner wires

 These are non-malleable stainless steel wires which come in different sizes and usually vary in diameter from between 0.7 mm to about 1.6 mm and in lengths of between 4 to 12 inches. There are usually used to fix small bone fragments which are not suitable for fixation with other devices such as screws, plates, and nails. Wires are frequently used to fix peri-articular fractures in children and also in adults, where non-invasive close reduction of the fracture can be carried out and the fracture stabilized with percutaneous wires. The frequent sites where wires are used for fixation of fractures include the elbow, wrist, hand, fingers, foot and the toes.

Cerclage wires

 These are malleable stainless steel wires which can be twisted around bones and tied in a knot. They are often used to fix fractures of the patella and the olecranon. They can also be used at other sites to complement fixation of bones with other devices.

Plates, screws, and nails

Various designs of plates, screws, and nails are available for internal fixation of fractures. These are usually made of stainless steel alloy or titanium alloy. The stainless steel implants are iron-carbon alloys with some element of chromium, molybdenum, and manganese. The titanium implants are alloys of titanium, aluminum and niobium.

Indications of implant removal

There is usually no disagreement among surgeons that K-wires that are used for temporary fixation of fractures should be removed after fracture union. K-wires protruding under the skin can cause skin irritation and pain. They can also migrate, if they are not securely fixed across two bone cortices, causing damage to other body structures. Cerclage wires can also cause skin irritation and pain if they are not buried in deep tissues and under such circumstance they should be removed. Screws that are subcutaneous and causing skin irritation should be removed.

Deep implants such as plates, nails, and screws may or may not be symptomatic and the removal such implants has been an area of debate and controversy. The questions that arise are whether the implants will cause harm if left in the body and do they cause any functional disability.

Do implants cause harm?

Biocompatibility of metallic implants has always been a concern because of the release of biologically active small particles due to oxidation of metal and the possibility of toxicity of these particles to the human body. Stainless steel alloys do corrode in the body but the implants become covered with a layer of fibrous tissue often as thick as 2 mm depending on the amount of corrosive material released and the amount of movement between the implant and the surrounding tissues.

Titanium alloys, on the other hand, do not corrode but they release ions which diffuse into the surrounding tissues [1]. It was believed in the 1970’s and 1980’s that these corrosive materials and metallic ions may be carcinogenic and predispose patients to cancers. However, experimental studies have not revealed any association between metallic implants and the development of any cancers [2]. Presently the possibility of corrosion and cancer are no longer considered to be an indication for removal of the implant [2]. Allergic reactions to metals in the body are rare and data substantiating implant related allergic reactions is scarce [2].

Another reason why plate removal was recommended in the past was due to the widely held belief that the presence of plates on the bone leads to bone atrophy. However, more recent studies have shown that if the plates are left in the body long enough the density of the bone returns to normal. Rosson et al studied the bone density in patients with forearm fractures and found that the bone density returns to normal after 21 months [3]. Similarly, studies of the tibia after plate removal have failed to show significant bone atrophy [4]. Hence plates can be left in the body without fear of plates causing bone atrophy or stress protection.

Essentially implants, left in the body after fracture union, do not cause any bodily harm. The next question that needs to be answered is whether implant produces symptoms or functional disability.

Do implants cause symptoms and when should they be removed?

There are very few circumstances under which implants would definitely need to be removed (absolute indications). K-wires can migrate and cause harm to other body structures and K-wires that are under the skin can produce pain, hence removal of K-wire would be indicated. Screws that perforate the joint should be removed because they can damage the joint when the joint is mobilized. Cerclage wires whose sharp ends are not properly buried under deep tissues can protrude under the skin leading to pain. Such wires obviously need to be removed. Implants such as plates adjacent to joints which are imperfectly positioned can obstruct joint motion and it would be necessary to remove them to improve joint function. Implants that are loose can migrate or produce irritation of adjoining soft tissues and such implants would also need to be removed.

Indication for removal of implants under most other circumstances is controversial and debateable. Some patients complain of pain or discomfort in the limb even when the implants are securely fixed and well positioned. The cause of such pain remains unclear and it is difficult to determine whether the implant is the cause of the pain or it is due to the injury itself [2]. In patients with such pain, the results of implant removal are ‘unpredictable and depend on both the implant type and its anatomic location’ [5].

Minkowitz in a study of 57 patients who had implant removal because of complaints of pain found that only 53% of the patients had complete resolution of pain at one year follow up [6].

Brown et al studied 126 patients who complained of lateral ankle pain in the region of the implants. Only 50% (11 out of 22 patients) had improvement of pain after implant removal. The functional scores were no different in patients who had and did not have implant removal [7]. The unpredictability of outcome has to be kept in mind when removal of implants for pain is contemplated.

Removal of implants involves another surgery which is accompanied with the risk of anesthesia-related complications as well as complications associated with the surgery itself. Cost of the surgery and hospitalization, as well as time off work, has to be borne in mind. Not only is the results of the surgery unpredictable, but the surgery itself can also sometimes be difficult and frustrating, resulting in broken implants and retrieval instruments. Surgical complications include bleeding, wound infections, neurovascular injury, refractures, recurrence of deformity, incomplete removal of hardware and sometimes poor cosmetic results because incisions for removal of the minimally invasive plate and nails are not so ‘minimal’.

Sanderson et al in a study of 188 patients who had implant removal found an overall complication rate of 20% and for forearm implant removal the complication rate was 42%. The nerve injuries that occurred were all permanent and were produced by junior doctors [8].

Richards et al in a smaller series of 86 adult patients who had a routine removal of implants in both symptomatic and asymptomatic patients reported a much lower rate of complications (3%) which included a nerve injury, a refracture, and a hematoma. However, the authors recommended that it would be appropriate to leave asymptomatic implants in situ [9].

Removals of implants from forearm bones are associated with higher complication rates. Langkamer et al [10] reported a 40% complication rate after forearm implant removal. Chia et al [11] reported a 27% and Bednar et al [12] reported a 10% complication rate following removal implants from the forearm.

Brown et al reported a 19% rate of significant complications in patients who had implant removal. They also found that patients who did not have their implants removed had no ‘appreciable problems’ and the authors recommended that implants should only be removed if there is a clear indication for the removal [13].

Karladani et al in a study of 71 patients who had removal of the tibial nail for pain found that only 39 of the 71 patients had improvement of pain and they were not totally pain-free after the surgery. In 14 patients the pain was the same and in 18 patients the pain was worse after the removal of the nail. Four of the 6 patients who had a previous fasciotomy were unhappy with the outcome of the surgery to remove the nail. The authors concluded that the outcome of tibial nail removal for pain is poor and that the nail should not be removed unless there are convincing reasons to do so [14].

There have been concerns that athletes with implants in situ, who participate in contact sports run the risk of a refracture because the implant can act as a ‘stress riser’. Evans and Evans did a retrospective study of 15 elite rugby players who returned to competitive sports while having implants in situ. Two of the players’ sustained implant related complications and the other 13 continued playing for up to 6 years without any symptoms. One of the players needed removal of wires which produced pain after the tension band wiring for a fracture of the patella while another player sustained an undisplaced fracture of the radius and had to be treated in a cast for one month. The authors concluded that an early return to sports after fracture union is feasible and it is not necessary to remove the implants which would further delay return to sports [15].

Routine removal of implants in pediatric patients is a common practice among many orthopaedic surgeons [16]. Kahle in arguing against routine removal of implants in children did a retrospective survey of 138 patients who had removal of implants and found a complication rate of 13%. Seven percent of the patients had an incomplete removal of the implant and 1.4% had a refracture. The study showed no evidence to support the policy of routine removal of implants [17].

Davids et al in a retrospective survey of 801 children with 1223 implants removed over a 17 years period reported a 12.5% complication rate of which 6% were major and 6.5% minor complications [18].

There appears to be no compelling reason to remove implants in children as is the case in adults after fracture union when the patient is asymptomatic.

Routine implant removal after fracture surgery consumes a remarkable portion of resources allocated for elective orthopedic surgery and is a potentially reducible consumer of hospital resources in trauma units [19].

The medical literature provides only level IV or level V evidence regarding removal of implants after fracture healing. Vos DI et al [20] have carried out a prospective multicentre clinical cohort study to evaluate the outcome of implant removal after fracture healing. The study included 288 adult patients, 146 patients had removal of upper limb implants and 142 patients had removal of lower limb implants. Removal of implants of the clavicle, humerus, radius/ulna, tibia, and femur was included.
The most frequent indication for implant removal was pain (63%) and limitation of joint motion (56%).

For removal of femoral nails, an extension of the scar was necessary in 62% of the patients and for tibial nails in 35% of the patients. For removal of upper limb implants, the estimated blood loss was between 0 to 300 ml and the operating time varied between 3 mins to 90 mins. For removal of lower limb implants, the blood loss was between 0 ml to 500 ml and the operating time was between 13 mins to 120 mins.

Thirty percent of the patients had one or more surgery-related complications. The complications included post-operative bleeding (11%), refractures (1%), nerve injuries (6) other complication in 9% of the patients. The complication rate for upper limb procedures was 22% while for the lower limbs it was 37%.

The number of patients with pre-operative complaints who had complete follow up was 214 (88%) and 6 months after the surgery the number of patients with complaints was reduced to 49% (P<0.0005). Despite the significant number of patients (39%) who had improved after implant removal there were 8 patients, who had no pre-operative complaints but developed 25 new post-operative complaints such as paraesthesia, pain, loss of strength and limited joint motion.

There appears to be no indication for removal of implants in patients, both adults, and children when there are no symptoms. In symptomatic patients the outcome of implant removal is unpredictable and the patient should be advised accordingly if implant removable is contemplated. In about half the patients the symptoms will not improve after the surgery. Furthermore, the surgery is not innocuous and between 3% to over 40% of the patients can develop complications depending on the type and location of the implant.

Conclusion

In the past routine removal of implants after fracture union was a common practice. This was because the metallic implants used for stabilization of the fracture served no purpose after the fracture had united and there were fears of carcinogenic toxicity of ions release form oxidative corrosion of the stainless steel alloy implants that were commonly used for fracture stabilization. However subsequent research has found that such claims are unfounded. Fears of bone atrophy and stress shielding related to the implants have also been found to be unfounded provided the implants are left in situ long enough. Hence implants need not be removed for these reasons.

However, under some circumstances, there are definite indications for removal of implants. There is no controversy or debate about removing K-wires, Cerclage wires, implants that penetrate joints and those that are imperfectly position and obstruct joint motion.

 In most other situations the indications for removal of implants are relative. Even stable infected implants, before fracture union occurs, are often left in situ but infected implants after fracture union should be removed to control infection. Implants that are loose which can sometimes migrate and cause symptom may have to be removed.

Deep-seated stable implants are usually asymptomatic and most authors recommend that they should be left in situ even in children. Removal of implants is not as innocuous as is often believed. Besides anesthesia-related complications, there are surgery-related complications in 3% to over 40% of the patients. Implant removal is also associated with increased cost and time off work.

In many patients who complain of pain around the site of the implant, the actual cause of the pain is often not known and it could be due to the effect of the injury rather than the implant itself. In symptomatic patients removal of implants resolve the symptoms in only about 50 % of the patients.

Before undertaking surgery to remove implants, it is imperative that the surgeon informs the patient about complications that can arise from the surgery. The patient also needs to be made aware of the unpredictability of the outcome of such surgery. Most authors are of the opinion that asymptomatic implants should not be removed and in other situations, the implants should only be removed if there is a definite compelling reason to do so.

References

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