How extensive should treatment be for asymptomatic adverse local tissue reaction associated with metal-on-metal hip implants?
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Several factors determine magnitude of revision
The algorithm for revision surgery for after metal-on-metal THA has evolved, and symptomatic patients are encouraged to consider revision. However, for asymptomatic patients with adverse local tissue reaction (ALTR; 31% in one study), shared decision-making between the surgeon and patient is important. In these cases, patients should be counseled about the risks and benefits of revision THA. The magnitude of revision depends on the prosthesis (modular or monoblock) and the extent of soft tissue and implant damage. If the THA is modular, we recommend liner exchange with highly crosslinked polyethylene and placement of a large ceramic head with titanium sleeve, removing all cobalt chrome alloy components. Cup revision is recommended if the primary THA prosthesis is monoblock or with extensive acetabular osteolysis, and we would use a highly porous titanium or tantalum component. With severe damage to the trunnion or extensive femoral osteolysis, we recommend femoral revision with a stem that obtains diaphyseal fixation. If ALTR caused severe abductor muscle or tendon damage, a dual-mobility or constrained liner could be considered. The extent of debridement of damaged tissues or pseudotumor is controversial in asymptomatic patients. Incomplete removal of affected tissue may be associated with pseudotumor recurrence or a nidus for infection. Debridement should not be radical and preserve unaffected tissue and neurovascular structures.
References:
Fehring TK, et al. Clin Orthop Relat Res. 2014;doi:10.1007/s11999-013-3222-1.
Matharu GS, et al. Acta Orthop. 2018;doi:10.1080/17453674.2018.1440455.
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Nicholas M. Hernandez, MD, is a clinical associate in the department of orthopedic surgery at Duke University, Durham, North Carolina.
Paul F. Lachiewicz, MD, is a consulting professor in the department of orthopedic surgery at Duke University in Durham, North Carolina.
Disclosures: Lachiewicz reports he receives royalties from Innomed; is a paid consultant for Guidepoint Global, Gerson Lehrman Group, Heron Therapeutics, Innocoll Pharmaceuticals and Quomeda; was on the speakers bureau for Heron Therapeutics and Ceramtec; is on the editorial board for the Journal of Arthroplasty and Joint Special Operations Association; and receives research support to practice from Zimmer Biomet. Hernandez reports no relevant financial disclosures.
Intervene for Trendelenburg gait, abductor weakness
ALTR to tribocorrosion debris is a well-known failure mechanism for metal-on-metal total hip replacements and surface replacements, as well as metal-on-polyethylene THRs that undergo mechanically assisted crevice corrosion at modular junctions. There is some confusion in the literature on exactly what constitutes an ALTR. In my view, an ALTR is a variable combination of a several different features: soft or hard tissue necrosis; aseptic lymphocyte-dominated vasculitis-associated lesion; osteolysis; and periarticular fluid collections with or without soft-tissue masses (pseudotumors) — in association with the generation of metal tribocorrosion debris from articulating surfaces and/or modular metal-metal junctions. The diagnosis is confirmed by histological analysis and gross or microscopic observation of the bearing surfaces and/or modular junctions. The diagnosis can be strongly suspected based on abnormal findings on cross-sectional imaging metal artifact reduction sequence MRI or ultrasound and elevated blood metal levels. Strictly speaking, the diagnosis of ALTR should not be made if the only finding is a periarticular fluid collection on cross-sectional imaging. If a patient with abnormal cross-sectional imaging findings and elevated metal levels is truly asymptomatic, serial observation is recommended except in cases of progressive osteolysis. If a patient with abnormal imaging findings and elevated metal levels is pain free but demonstrates a Trendelenburg gait, abductor weakness or has experienced a late dislocation, surgical intervention should be strongly considered as these features suggest compromise of the periarticular soft tissues that can be progressive.
Joshua J. Jacobs, MD, is the William A. Hark, MD/Susanne G. Swift Professor and Chair of the department of orthopedic surgery at Rush University Medical Center in Chicago.
Disclosure: Jacobs reports he is a consultant for Zimmer Biomet; has stock options with Hyalex; receives research funding from Zimmer Biomet, Medtronic, NuVasive and the NIH; and is on the Journal of Bone and Joint Surgeons Board of Trustees.
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