Abstract
Aims
To devise a simple clinical risk classification system for patients undergoing primary total knee arthroplasty (PTKR) to facilitate risk and cost estimation, and aid pre-operative planning.
Methods
We retrospectively reviewed a series of consecutive PTKRs performed by the senior author. A classification system was devised to take account of principal risk factors in PTKR. Four groups were devised: 1) Non complex PTKR (CP0): no local or systemic complicating factors; 2) CPI: Locally complex: Severe or fixed deformity and/or bone loss, previous bony surgery or trauma, or ligamentous instability; 3) CPII Systemic complicating factors: Medical co-morbidity, steroid or immunosuppressant therapy, High BMI, (equivalent to ASA of III or more); 3) CPIII: Combination of local and systemic complicating factors (CPI+CPII). The patients were grouped accordingly and the following were compared: 1) length of stay, 2) post-operative complications, and 3) early post-discharge follow-up assessment. The complications were divided into local (wound problems, DVT, sepsis) and systemic (cardiopulmonary, metabolic, and systemic thromboembolic) complications.
Results
The total number of patients was 119 (CP0=37,CPI=19,CPII=30,CPIII=33). Multiple regression analysis revealed: 1) no significant difference between complication rates in the CP0 and CPI groups, 2) 3-fold and 4-fold increase in the cumulative risk in the CPII and CPIII groups respectively (p<0.001), 3) significantly increased length of stay in the CPII and CPIII groups (p<0.001).
Conclusion
The groups in this classification system correlate well with complication rates from surgery. As such this system has a role in stratifying patients for pre-operative planning and risk counselling. It is reproducible and can be used for larger patient groups via the National Joint Registry. Our findings also have implications for payment by results and fixed tariffs for PTKR, as the higher complication rates in the CPII and CPIII groups are likely to attract greater expense by hospitals in the course of these patients' treatment.
