Overview: Metal-on-metal hips are once again causing a stir in the orthopedic world, as international regulatory agencies issue warnings about the MITCH THR hip replacement system in combination with the Stryker uncemented Accolade stem. After analyzing data from the England and Wales National Joint Registry (NJR), UK regulators have determined that the system fails at a rate “higher than indicated as acceptable by NICE”; the international recall has affected 41 patients in New Zealand.
- The MITCH THR system is failing at high rates, especially when used with the uncemented Accolade stem
- Overseas, regulators have issued warnings and recalled the device
- 41 patients in New Zealand are contacted
- The hip system was distributed in between May 2006 and October 2011 in the UK
Product: MITCH TRH acetabular cups and modular heads/uncemented Accolade femoral stems
Manufacturer: Finsbury Orthopedics (DePuy)/Stryker Orthopedics
Side Effects & Complications
- High failure rate
- Necrosis (tissue death)
- Increased levels of cobalt and chromium ions
- Pain at the implant, sometimes spreading to the groin and back
- Osteolysis (bone loss)
- Fluid collections/solid masses around the hip joint
Regulators in U.K and New Zealand show concern
Two weeks ago, the UK’s Medicines Healthcare and Regulatory Agency (MHRA) issued a medical device alert to warn about the observed failure rate in MITCH THR cups and heads when used with Stryker’s uncemented Accolade stem. While the MITCH THR system can be used with the other stems including the Exeter V40 and ABG II, the agency found that the Accolade stem resulted in the highest failure rate. According the alert, the combination resulted in a 10.7 percent revision rate in 4 years among 271 patients, compared to the 3.7 percent revision rate among 120 patients seen with the Exeter V40.
The MITCH THR system was used in the UK from May 2006 to October 2011.
In the New Zealand, Stryker has contacted the surgeons of 41 patients who received the implant. According to the New Zealand joint registry, three patients required additional surgery after the MITCH system failed. “We are also working closely with the New Zealand Orthopaedic Association and the New Zealand joint registry to ensure people are notified of the recall, given information, and told of the need for further follow-up.” cites Medsafe.
Metal-on-metal hip implants have raised serious concerns because the friction between metal components can produce metallic debris, typically manifesting in elevated cobalt and chromium ion levels.
Depuy acquired Finsbury Orthopedics Ltd. In December 2009, and is subsequently responsible for previously manufactured products.
In September 2010, DePuy, a subsidiary of Johnson & Johnson, recalled its ASR XL total hip replacement and resurfacing systems; the implants were failing at a rate of 13 percent within 5 years. Over 93,000 people received the recalled devices worldwide. Since then, medical professionals everywhere have been on alert over the device.
Last May, the U.S. Food and Drug Administration (FDA) ordered all metal-on-metal hip manufacturers to conduct post-market studies in order to fully assess the devices.