MHRA DSI/2026/010: Cobalt-Chrome Modular Neck Hip Replacements — Metal Wear and Revision Risks Trigger Clinical Follow-Up

MHRA Publishes DSI/2026/010 on Cobalt-Chrome Modular Neck Hip Prostheses

On 26 August 2026, the UK Medicines and Healthcare products Regulatory Agency (MHRA) issued Device Safety Information DSI/2026/010 concerning the risk of metal wear and revision surgery associated with cobalt-chrome (Co-Cr) modular neck hip prostheses. The MHRA's investigation found that a number of femoral stem components using cobalt-chrome modular necks carry an increased risk of wear and corrosion, which may lead to additional revision surgery as a result of adverse local tissue reactions (ALTR).

The issue relates to the dual-taper modular neck design. This design creates two contact interfaces: one between the modular neck and the femoral stem, and another between the modular neck and the femoral head. The greater the number of interfaces, the greater the number of locations where wear and corrosion may occur. The design was originally intended to facilitate intraoperative adjustment of neck length and angle, to better match individual patient anatomy and to restore more natural biomechanics — but these benefits must be weighed against the risks associated with the two interfaces.

Scope of the Investigation and Affected Systems

The scope of the MHRA investigation covered all cobalt-chrome modular neck hip prostheses that have previously been available on the UK market, involving:

• Aesculap AG (part of B. Braun) — Metha modular
• LimaCorporate (part of Enovis) — H-Max-M
• Smith and Nephew — SMF
• Stryker — ABG II modular
• Symbios — HARMONY modular and SPS modular

All of these devices were withdrawn from the UK market before 2019, and none is currently on sale. Symbios modular neck product codes listed in the DSI include 3314 0002, 3314 0003, 3314 1082, 3314 1083 and 3314 2152, among others; all lots are affected.

Evidence from the National Joint Registry

The data are drawn from the June 2026 extract of the UK National Joint Registry (NJR). According to Table 1 of the DSI, the SPS modular system had the largest implant volume (597 cases, plus 25 cases with material not stated), with 38 revisions, 12 of which were due to ALTR. Statistically, its ALTR-related revision rate is approximately twice that expected, and a Field Safety Notice (FSN) has already been issued on this issue. Metha modular, H-Max-M and ABG II modular show limited evidence of ALTR-related revisions; for SMF and HARMONY modular, no confirmed ALTR-related revisions were identified at the time of writing. Notably, the investigation did not find any system with a revision rate higher than expected due to device fracture, which differs from the conclusions of the earlier DSI/2025/005 (Profemur systems).

Clinical Follow-Up Requirements

On this basis, the MHRA has set out a series of clinical follow-up requirements. Hospitals and trusts should review local and national databases (for example, the NJR) to identify patients implanted with the affected devices. Identified patients should be proactively contacted and invited to attend a remote or face-to-face clinical review, and should be informed of the risks set out in the DSI. Where symptoms or clinical findings suggest a soft tissue reaction or other metal-related effects, whole blood cobalt and chromium testing is recommended — using laboratories participating in UK NEQAS in England, Northern Ireland and Wales, and the local trace element reference laboratory in Scotland. MARS MRI or ultrasound should also be performed in accordance with institutional policy, with each patient assessed individually.

Revision Decision-Making and Patient Follow-Up Pathways

The decision on whether to revise should take into account factors including imaging abnormalities, blood metal levels that are higher than expected or rising over time, and deterioration in hip function or patient-reported outcome measures (PROMs). The MHRA specifically notes that there is currently no accepted whole blood metal level threshold that can be used to predict outcomes or to directly determine whether revision is required; the judgement must also consider patient factors, implant type and implant position. After review, annual follow-up during the lifetime of the implant is recommended for symptomatic patients. Asymptomatic patients may enter a patient-initiated follow-up (PIFU) pathway, which should remain open for the lifetime of the implant; where PIFU is not available, the written contact details of the implanting unit must be provided and the patient's general practitioner must be informed.

Additional Background

Two further points of context are relevant. First, ABG II modular and SMF were previously subject to manufacturer field safety corrective actions in July 2012 and November 2016 respectively; patients already monitored in line with the manufacturer's recommendations may therefore not require additional follow-up. Second, most patients implanted with these hip prostheses have good hip function and are considered to be at low risk of serious problems. Affected patients who have not yet been contacted should be proactively contacted by their operating surgeon or implanting hospital; patients do not need to make contact themselves. The MHRA's clinical orthopaedic experts and the interim device working group consider that the above recommendations will help to achieve better outcomes where revision is required.

Sources and Applicability

Source: Medicines and Healthcare products Regulatory Agency (MHRA), Device Safety Information DSI/2026/010, "Cobalt-chrome modular neck hip replacements: risk of metal-wear effects and revision surgery", published on 26 August 2026.

• Official page: https://www.gov.uk/drug-device-alerts/cobalt-chrome-modular-neck-hip-replacements-risk-of-metal-wear-effects-and-revision-surgery-dsi-slash-2026-slash-010
• Original PDF: https://assets.publishing.service.gov.uk/media/6a8db7c6f5b35599aec18d48/Cobalt-chrome_modular_neck_hip_replacements_risk_of_metal-wear_effects_and_revision_surgery__DSI2026010_.pdf
• Prior investigation DSI/2025/005 (Profemur cobalt-chrome modular neck): https://assets.publishing.service.gov.uk/media/68b956273f3e5483efdba994/DSI_-_MPO_Profemur_final.pdf

Verification scope and access date: This verification is based on the above MHRA official page and PDF, cross-checked against the GOV.UK device safety information listing page, with an access date of 11 October 2026. The implant volumes, revision numbers and ALTR-related revision data in Table 1 are as reported in the DSI from the June 2026 extract of the UK National Joint Registry (NJR).

Applicability note: This article is an interpretation of publicly available regulatory information and does not constitute a conclusion or commitment regarding any specific product, company or registration application. Device names, product codes and data are subject to the official source text, and the information may change with subsequent official updates.

AIMEILI Regulatory Interpretation

DSI/2026/010 is significant less for the market status of the devices named — all were withdrawn from the UK before 2019 and none is currently on sale — than for what it signals about the MHRA's long-term post-market posture on modular hip designs and metal-on-metal or metal-bearing articulations. The action is retrospective and patient-facing rather than product-facing: it obliges hospitals and trusts to search local and national registries, re-contact patients, and provide structured follow-up pathways, including PIFU where appropriate. This is a lifecycle obligation imposed on the healthcare system, but manufacturers of comparable modular-neck or metal-bearing hip systems should read it as a forward-looking expectation for their own post-market clinical follow-up (PMCF) planning.

Three technical points deserve particular attention from a regulatory standpoint. First, the MHRA explicitly reaffirms that no accepted whole blood metal ion threshold exists for predicting outcomes or determining revision, which means clinical decision-making remains multifactorial and cannot be reduced to a single laboratory cut-off; any manufacturer communications or IFUs implying otherwise may be inconsistent with the regulator's position. Second, the DSI distinguishes ALTR-driven revision risk from fracture-driven revision risk, and notes that no system in this review showed a fracture-related revision rate above expectation — a contrast with the earlier DSI/2025/005 on Profemur. This distinction matters for post-market surveillance (PMS) reporting, as ALTR signals typically emerge from registry linkage and patient-reported outcomes rather than from field failure or complaint data. Third, the SPS modular finding — an ALTR revision rate roughly twice the expected level, following a previously issued FSN — illustrates how registry-based signal detection can escalate an already-escalated signal, and how a single system can dominate the risk profile of an entire device family.

From a classification and evidence perspective, modular neck hip prostheses remain high-risk Class III (or Class IIb in some jurisdictions) implants, and the two-interface dual-taper configuration is inherently more demanding in terms of tribological and corrosion characterisation. Notified bodies and regulators increasingly expect biomechanical and retrieval-analysis data covering the modular junction, corrosion-related failure modes, and metal ion release, supported by clinically relevant endpoints rather than bench data alone. Sponsors with modular designs in their portfolios should expect such questions during technical documentation review and in PMCF plan assessment.

Business Impact for Manufacturers, Distributors, CROs and Regulatory Teams

• Portfolio screening: Manufacturers should confirm whether any currently marketed or recently withdrawn product incorporates a cobalt-chrome modular neck with a dual-taper junction. Even where a product was never placed on the UK market, similar designs may attract equivalent scrutiny in other jurisdictions following the MHRA signal.
• Post-market surveillance review: Companies should verify that PMS and PMCF plans capture ALTR-related endpoints, registry linkage and patient-reported outcome data, not only fracture, mechanical failure and complaint rates. Registry-derived ALTR signals can precede or bypass conventional complaint trending.
• Field safety corrective action readiness: The SPS modular case shows that an FSN does not necessarily close the issue; a later registry analysis can quantify an elevated revision rate and prompt renewed regulatory action. Corrective action files should be structured to accommodate subsequent evidence.
• Distributor and hospital communication: Distributors operating in markets with registry infrastructure should anticipate hospital requests for implant identification support, product code lists and patient traceability data, and should route such requests through the manufacturer's regulatory function rather than responding ad hoc.
• Registry and real-world data strategy: CROs and regulatory affairs teams should treat national joint registries as core evidence sources. DSI/2026/010 was driven substantially by NJR data, reinforcing the value of registry access, data linkage capability and statistical expertise in estimating expected versus observed revision rates.
• Labeling and clinical documentation: Claims about modularity benefits (intraoperative flexibility, anatomical fit, biomechanical restoration) should be balanced against device-specific residual risks, with the two-interface wear and corrosion mechanism adequately characterised for the intended market.
• Cross-jurisdiction monitoring: Although this DSI is UK-specific, its reasoning on dual-taper modular junctions and metal ion release is relevant to submissions and post-market obligations in the EU (MDR), the US (FDA) and other major markets. Regulatory intelligence workflows should flag DSI/2026/010 alongside DSI/2025/005 as related precedent.