Abstract
Introduction Patients are not universally pleased with their total knee replacements and satisfaction rates of 77% are quoted. This is in spite of quoted 10 year survivals for implants being in excess of 95%. We have looked at mal-alignment as a potential cause of the painful TKR.
Methods Twenty-five patients (21 male), mean age 78 (range 68 to 88 years), are presented. Each consulted the author because of pain in their total knee replacement. Twenty had had a primary replacement and five had at least one further procedure after the replacement. There was no evidence of infection in any of these. The Perth CT Protocol was used to investigate the alignment of the knees.
Results This group of patients had, on average, 8.6° of cumulative mal-alignment with 2.6 (of six) parameters being more than two degrees mal-aligned. The greatest deviations were in femorotibial matching (error rate 80%) with femoral rotation (error rate 68%) mal-alignment being the next most common. In a consecutive series of 42 primary, computer assisted knee replacements the mean mal-alignment index was 2.3:1.3. In patients with a cumulative error of six or less other causes of pain were found.
Conclusions It is suggested that mal-alignment of a knee replacement is a potential cause of pain and that a cumulative score of more than six probably represents the symptom threshold.
In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.
The abstracts were prepared by Mr Jerzy Sikorski. Correspondence should be addressed to him at the Australian Orthopaedic Association, Ground Floor, William Bland Centre, 229 Macquarie Street, Sydney NSW 2000, Australia.
