THE LONG-TERM RESULTS OF THE LIVERPOOL MARK II KNEE PROSTHESIS

We have reviewed 105 Liverpool Mark II knee replacements in 71 patients to assess survival and long-term results. Assessment was both clinical and radiological, using a modification of the British Orthopaedic Association knee function assessment chart, and analysis was by the survivorship method as advocated by Tew and Waugh. The follow-up period was between 13 and 1 13 months with 42 prostheses being in situ for over six years. Eight knees (7.6%) have been revised or arthrodesed because of infection or loosening, giving a cumulative success rate of 89 % after seven years based on prosthesis survival alone. Of the remaining knees, 7 1. 1 % were either free of pain or caused only minimal pain. The cumulative success rate as judged by the stricter criteria of the prosthesis being in situ and causing little or no pain suggested a 50 % survival between 73 and 96 months. Most patients (77.3%) were enthusiastic or satisfied with their results. Complications included deep wound infection (8.6%), and loosening which needed further surgery (11.4%). Since 1974 the Liverpool Mark II knee prosthesis has been in regular use at Whiston and St Helens Hospitals. Its unconstrained, ligament-sparing design is based on Gunston’s concept (Gunston 1971) and on lessons learnt from the earlier Mark I prosthesis (Cavendish and Wright I 974). This present bicondylar prosthesis consists of two metal femoral components which are designed for near-normal articulation with two high-density poly-ethylene tibial components (Fig. 1). The requirements and design criteria have been previously discussed (Cavendish and Wright 1976, 1977; Elloy, Wright and Cavendish 1976). Insertion is through two para-patellar incisions using stereotactic jigs to ensure accuracy of alignment. A preliminary report of 62 replaced knees showed encouraging results (Cavendish and Wrigh