Introduction: This study was carried out to compare the effect of femoral Posterior Condylar Offset (PCO) on clinical results between single-radius (SR) and multi-radius (MR) femoral design components in posterior stabilized total knee arthroplasty. (PS TKA)

Material and methods: This hospital based prospective observational study was conducted at Department of Orthopaedic, Santokba Durlabhji Memorial Hospital, Jaipur, Rajasthan. Between 1 January 2018 to 31 December 2018 with 6 months follow up. 100 Knees were replaced, 50 knees each for single-radius (group A) and multi-radius (group B). Cases were evaluated pre-operatively and 6 months post-operatively by measurement of posterior condylar offset, flexion (non-weight bearing and weight bearing) and knee society scoring system. Posterior condylar offset measurement done by methods used by Bellemans et al. Patients were divided into two groups by chit-based method for randomization. Appropriate statistical tests were used and results were interpreted.

Results: The mean age 65.57± 8.07 years. The Mean age was 64.36 ± 7.63 years in group (A) and 66.78 ± 8.51years in group (B). Female predominance (68%) was observed. The pre-operative mean values for PCO in group (A) and (B) were 27.66 ± 3.20 mm and 27.50 ± 2.24mm respectively. This was statistically not significant. The post-operative mean values for PCO in groups (A) and (B) were 29.42 ± 2.52 mm and 29.20 ± 3.05 mm respectively. This data was statistically not significant. The pre-operative means non-weight bearing flexion in group (A) was 112.70 ± 8.09 degrees and in group (B) was 106.50 ± 12.83 degrees. The post-operative means non-weight bearing flexion in group (A) was 121.60 ± 3.97 degrees and in group (B) was 119.90 ± 3.27 degrees. The pre-operative mean value for knee flexion (weight bearing) in group (A) and (B) were 102.70 ± 7.37 degrees and 96.70 ± 10.13 degrees respectively. The post-operative mean value for knee flexion (weight bearing) in group (A) and (B) were 124.50 ± 3.81 degrees and 123.60 ± 2.86 degrees respectively. The mean difference between post-operative and pre-operative values were significant in all variables in group (A). The mean difference between post-operative and pre-operative values were significant in all variables in group (B). Between the two groups, the mean difference in KSS knee score and flexion (weight bearing and non-weight bearing) were statistically significant (P-value <0.05) whereas mean difference in KSS functional score and PCO were not significant. Between the two groups, statistically significant difference was observed in grading of post-operative KSS knee score. Between the two groups, no significant difference was observed in grading of post-operative KSS functional score. In Group (A), the not significant, negative and poor correlation was observed between change in PCO and other variables like non-weight bearing flexion, KSS knee score, KSS functional score, and weight bearing flexion (Pearson correlation values were -0.004, P value =0.976; -0.224, P value =0.118; -0.036, P value =0.805 and -0.057, P value =0.694 respectively. In Group (B), the not significant, negative and poor correlation was observed between change in PCO and other variables like non-weight bearing flexion, KSS knee score, KSS functional score, and weight bearing flexion (Pearson correlation values were -0.208, P value =0.148; -0.029, P value =0.843; -0.223, P value =0.12and -0.251, P value =0.079 respectively.