Continued stabilization of trabecular metal tibial monoblock total knee arthroplasty components at 5 years-measured with radiostereometric analysis

• Published in: Acta orthopaedica Vol. 83; no. 1; pp. 36 - 40
• Main Authors: Wilson, David A J, Richardson, Glen, Hennigar, Allan W, Dunbar, Michael J
• Format: Journal Article
• Language: English
• Published: Basingstoke Nordic Orthopaedic Federation 01-02-2012; Taylor & Francis; Informa Healthcare
• Subjects: Aged; Aged, 80 and over; Arthroplasty, Replacement, Knee - methods; Biological and medical sciences; Bone Cements; Cementation; Diseases of the osteoarticular system; Female; Follow-Up Studies; Humans; Male; Medical sciences; Middle Aged; Orthopedic surgery; Osteoarthritis - surgery; Polyethylenes; Prosthesis Design; Radiostereometric Analysis; Sample Size; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Tibia; Time Factors; Treatment Outcome; Total knee arthroplasty; Orthopedic surgery; Treatment; Metal; Stabilization; Orthopedics
• ISSN: 1745-3674; 1745-3682
• DOI: 10.3109/17453674.2011.645196

Background and purpose The trabecular metal tibial monoblock component (TM) is a relatively new option available for total knee arthroplasty. We have previously reported a large degree of early migration of the trabecular metal component in a subset of patients. These implants all appeared to stabilize at 2 years. We now present 5-year RSA results of the TM and compare them with those of the NexGen Option Stemmed cemented tibial component (Zimmer, Warsaw IN).
Patients and methods 70 patients with osteoarthritis were randomized to receive either the TM implant or the cemented component. RSA examination was done postoperatively and at 6 months, 1 year, 2 years, and 5 years. RSA outcomes were translations, rotations, and maximum total point motion (MTPM) of the components. MTPM values were used to classify implants as "at risk" or "stable".
Results At the 5-year follow-up, 45 patients were available for analysis. There were 27 in the TM group and 18 in the cemented group. MTPM values were similar in the 2 groups (p = 0.9). The TM components had significantly greater subsidence than the cemented components (p = 0.001). The proportion of "at risk" components at 5 years was 2 of 18 in the cemented group and 0 of 27 in the TM group (p = 0.2).
Interpretation In the previous 2-year report, we expressed our uncertainty concerning the long-term stability of the TM implant due to the high initial migration seen in some cases. Here, we report stability of this implant up to 5 years in all cases. The implant appears to achieve solid fixation despite high levels of migration initially.