Surgical options for addressing taper corrosion
When taper joint corrosion is identified as the root cause of issues such as pain, swelling, and instability, revision is an option. However, surgeons should keep in mind that numerous asymptomatic cases have been documented. We share some considerations to help guide surgical intervention. While all surgery carries inherent risk, corrosion-related tissue damage, when severe, is associated with increased complication rates, making the case for early intervention.
Identifying corrosion as the primary source of painful symptoms in modular total hip replacement patients is a process of elimination . Comprehensive presurgical evaluation that includes clinical examination, serum metal testing, and imaging can be helpful in making a diagnosis [1, 2] [See Part II of this article series]. For those that are asymptomatic, implant failure is usually the first indication of a problem, and adverse local tissue reaction (ALTR) due to corrosion can be unexpectedly encountered during revision .
Read an interview: AO Recon spoke with Moussa Hamadouche, an orthopedic surgeon and professor, about key points to consider when diagnosing taper corrosion. He raises a question about the role of metal sensitivity in patients as a factor compounding adverse local tissue reactions.
The importance of presurgical planning
Developed for the management of patients with metal-on-metal total hip implants (MoM THA), the risk stratification algorithm from Kwon  has been suggested as a useful aid in revision decision making for this patient population  (see Tables 1, 2, 3).
Tables 1, 2, and 3. Used with permission. Source: Kwon YM, Fehring TK, Lombardi AV, et al. Risk Stratification algorithm for management of patients with dual modular taper total hip arthroplasty: consensus statement of the American Association of Hip and Knee Surgeons, the American Academy of Orthopaedic Surgeons, and the Hip Society. J Arthroplasty. 2014;29(11):2060-2064
Once it has been determined that corrosion and associated tissue damage will be encountered during a revision, it is important to systematically plan for the procedure. Conducting a thorough evaluation of patient characteristics, taking into consideration the previous approach and implants used, stocking a supply of implant components that will and may be required, as well as anticipating soft tissue and/or bone damage is suggested .
Weiser and Chen  also advise surgeons to be well versed in techniques and procedures for revision and have a variety of revision instruments on hand, such as: a manufacturer-specific stem extraction device, slap hammer, vice grips, high-speed pencil tip bur, flexible osteotomes, broad osteotomes, bipolar wound sealer, cerclage cables, and standard hip revision instruments. Additionally, they list acetabular explant devices, high-speed burs, and round acetabular osteotomes as helpful tools. Patients, particularly those with recalled implants, may require the return of explanted components for analysis and litigation purposes. This request should be clearly communicated to the surgical team.
Open patient communication
As with any surgical procedure, good patient communication has been shown to improve health outcomes  and total hip arthroplasty (THA) revision is no exception. Patients should be partners in shared decision-making and made aware of the risks and prognosis; revision for corrosion-related ALTR has a higher risk of complications [5, 8].
Evidence is still being gathered, but corrosion appears to permanently impact gait abnormality via periarticular tissue necrosis and cause instability . Patients should also be informed that depending on what is encountered (implant type and ease of removal, necrosis, etc), their procedure may be longer and more involved than originally planned .
McGrory emphasizes “meticulous” surgical technique as a critical element for THA revision surgery . There is a good chance that surgeons will encounter well-fixed components that compound challenging intraoperative decision-making . We have assembled a simplified, condensed overview of what a corrosion-related revision surgery might entail with input from several published sources [1, 2, 5, 11, 12]:
- Perform radical debridement including a complete synovectomy
- Remove all expendable nonviable and suspicious tissue
- Test modular head for loosening
- Assess femoral neck and acetabular cup for loosening before disengagement
- Exclude impingement, which could be a cause of implant failure
- Disengage head
- Inspect head-neck junction for corrosion; grade corrosion (see Table 4)
- Clean and dry the trunnion to remove corrosion
- Assess trunnion for physical damage
- Retain well-fixed femoral component, or
- Perform stem extraction and replacement depending on the track record of the implant
- For extraction, use an extended trochanteric osteotomy (ETO) for well-fixed components if necessary [Video]
- Assess acetabular cup – use matching components
- Isolated liner exchange, or
- Acetabular revision
- Carefully clean, rinse, and dry taper before assembly. Use titanium alloy adaptor sleeve
- Use matching components - avoid angular taper mismatch
- Replace head with sleeved ceramic or oxidized zirconium head
- Affix head with sufficient force
- Restore soft issues
- Reattach indurated and friable abductors; provide hip abductor bracing postoperatively
- Monitor intraoperative cultures for infection for 14 days
Used with permission. Source: Goldberg JR, Gilbert JL, Jacobs JJ, et al. A multicenter retrieval study of the taper interfaces of modular hip prostheses. Clin Orthop Relat Res. 2002 Aug;(401):149-161.
Should femoral stems be retained?
There is some divergence of opinion in the literature about retention of femoral stems. Some, for example Jennings , prefers to leave a well-fixed stem in place when possible and attach a ceramic head with titanium adaptor sleeve, which is expensive , to a well cleaned trunnion. The most common practice is to revise to a ceramic head and ceramic/polyethylene liner . Please note, ceramic heads are allowed for new revised components only or in combination with a titanium sleeve. Hussenbocus  recommends this course of action only when “trunnion corrosion is microscopically mild (visible but not palpable)” as this has been shown to resolve ALTR symptoms and decrease serum metal levels . Ceramic femoral heads are more expensive than cobalt chromium (CoCr) ones and this may present an issue for some hospitals .
Total removal of all CoCr components might be important to the patient, particularly if cobalt hypersensitivity is a concern . There is also the argument that retention of a corroding femoral stem can result in recurrence of ALTR and corrosion. At any rate, benefits of revision of a well-fixed but damaged stem will need to be weighed against potential morbidity related to revision .
Don’t mismatch the components
As a final topic for discussion, it is imperative that the replacement femoral head be compatible with trunnion design . Mismatch risks recreating the conditions that led to taper corrosion in the first place, namely increased micromotion. Trunnions, even if labeled with the same name (eg, 12/14), possess subtle, yet different dimensions and cone angles between companies, and even implants from the same manufacturer [11, 16].
More research to guide decision-making
Research into the modular implant corrosion issues continues to grow and protocol for diagnosis and treatment will improve as evidence is gathered. At present, determining the best course of action is left up to a surgeon's best judgement. Revision of modular total hip replacements due to corrosion-related ALTRs carries a higher risk of complications and morbidity. However, in many cases, revision successfully lowers serum metal levels and patients regain mobility of their joint. Early diagnosis and intervention will continue to help optimize revision outcomes.
Moussa Hamadouche, MD, PhD is a Professor of Orthopaedic Surgery at the University Paris 5 Hospital in France.
Taper corrosion: what surgeons need to know!
It can be a challenge to diagnose taper corrosion as not all patients with the problem are symptomatic. In conversation with Professor Moussa Hamadouche MD, PhD from Cochin Hospital, University Paris 5, provides insight into the diagnosis of taper corrosion and discusses immunosensitivity to metals as a poorly understood contributing factor to this problem.
Diagnosing taper corrosion: What indicators should surgeons be looking for?
Moussa Hamadouche: Physicians treating patients with suspected trunnionosis must perform a thorough history and physical examination and obtain antero-posterior and lateral x-rays of the hip. Usually patients complain about groin or buttock pain following primary total hip arthroplasty (THA) (mean follow-up in the main series around 5 years). This is somewhat associated with fluid collection and/or swelling around the hip, recurrent instability, and abductor weakness. It is unknown what the relationship is between adverse local tissue reaction (ALTR) and genotoxicity, cytotoxicity, and metal hypersensitivity, but ALTR is often associated with pain in the groin, hip, thigh, and buttock. When suspecting this diagnosis, patients should have metal artifact reducing sequence MRI (MARS MRI) performed to determine if there is fluid collection around the hip.
Also, elevated cobalt (Co) and chromium (Cr) levels will be present. Typically, Co is predominantly elevated over Cr. Thus, the serum chromium level remains normal or only slightly elevated in patients with corrosion at modular junctions, whereas the serum cobalt level rises due to its increased solubility. This fact can be used to distinguish a failed metal-on-metal articulation (eg, trunnionosis), which in general will have an equivalent rise in serum cobalt and chromium levels. A failed modular junction will generally have a differential elevation of serum cobalt levels several fold above that of the serum chromium level. It should be noted that this situation can mimic infection, including elevated C-reactive protein (CRP) level, and aspiration should be proposed.
Are certain patients more affected than others?
The answer is probably yes, as this ALTR to metal ions is probably mitigated by the immune system. However, at this point, there is no specific predictive test that can be performed to predict this situation. It is unknown how adverse reactions to metal debris and ALTR reactions correlate with the biologic issues of genotoxicity, cytotoxicity, and hypersensitivity. Metal allergies are much more common in patients that undergo joint replacement than in the general population of those without an implant. This percentage is even higher in patients with a poorly functioning, painful, metal-on-metal articulation. However, a study performed in Italy showed no proven cause-and-effect relationship between immunosensitization and poor clinical outcomes. Metal hypersensitivity is a well-known and common condition, affecting approximately 10% to 15% of the general population. Nickel, which is used in colbalt-chromium alloys that are used to make metal implants, is the most common and potent immunologic sensitizing metal, followed by cobalt and chromium. Those sensitive to nickel often have cross-reactivity with cobalt and chromium.
What role do implants play?
This complication seems more implant-related rather than patient. Some implants are more prone to this complication than others. The risk factors include: taper geometry and size, taper locking location, and surgical technique. Also, femoral head material and size is of major importance, large CoCr heads on CoCr stems being the worst combination. Steady-state wear is directly related to femoral head size. Although linear wear can be reduced by increasing the size of the femoral head, volumetric wear increases linearly. A 36 mm femoral head has nearly double the volumetric wear of an 18 mm femoral head.
Regarding: revision: What steps can surgeons take to surgically alleviate the problem?
The source of debris from the head neck junction should be eliminated. This can be done with femoral implant revision, when this is a safe option. Indeed, taper damage will be present, and this is a best therapeutic option. A ceramic on polyethylene or ceramic on ceramic combination can be used. If removing a well-fixed femoral component seems too difficult and requires an extended osteotomy, the femoral component can be left in place, the taper cleaned as much as possible, and using a sleeve adapter, a ceramic head can be employed. Some early results show this option can produce satisfactory outcomes.
What educational measures do you consider the most effective to help with this problem?
Surgeons should be aware of this complication and think of this differential diagnosis when evaluating a painful THA, in the absence of a clear reason. Workup should include MARS MRI and serum levels measurement of Co and Cr. Also, surgeons should try to avoid this complication by not using large CoCr heads on CoCr stems. Orthopedic meetings are probably the best way to disperse this information, including interactive discussions with surgeons that have faced this complication. Surgeons should not jump into innovations in the absence of well proven data coming either from registries or robust Level I studies. Algorithms created by the Hip Society provide a good framework for a systematic evaluation. Also, industry has a role to provide surgeons with information regarding implants that have been more prone to this complication.
This series of articles was created with the support of the following specialists (in alphabetical order):
This issue was created by Word+Vision Media Productions, Switzerland
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- Lash NJ, Whitehouse MR, Greidanus NV, et al. Delayed dislocation following metal-on-polyethylene arthroplasty of the hip due to 'silent' trunnion corrosion. Bone Joint J. 2016 Feb;98-B(2):187-193.
- Kwon YM, Fehring TK, Lombardi AV, et al. Risk stratification algorithm for management of patients with dual modular taper total hip arthroplasty: consensus statement of the American Association of Hip and Knee Surgeons, the American Academy of Orthopaedic Surgeons and the Hip Society. J Arthroplasty. 2014 Nov; 29(11):2060-2064.
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