SA Orthopaedic Journal
On-line version ISSN 2309-8309
VAN GRAAN, W and VAN DER MERWE, W. The influence of posterior condylar offset on maximum knee flexion: a retrospective analytical study. SA orthop. j. [online]. 2014, vol.13, n.1, pp. 65-68. ISSN 2309-8309.
BACKGROUND: Achieving maximum knee flexion following total knee replacement (TKR) remains a major goal for every knee arthroplasty surgeon. Studies to understand the kinematics of the knee therefore remain of utmost importance. Speculation remains regarding what the correct posterior condylar ratio should be after surgery and whether a change in posterior condylar offset will have an impact on the amount of flexion achieved. OBJECTIVES: The aim of this study was to determine the role of the posterior condylar offset on knee flexion and whether a change in posterior condylar offset influenced the amount of flexion achieved. Since multiple causes for a change in knee flexion have been identified before, we have tried to eliminate as many variables as possible to keep our focus on the influence on posterior condylar offset on knee flexion. METHODS: Our study was unique in that all our surgery was performed using computer-assisted surgery (CAS), which ensured our measurements were very accurate and allowed us to eliminate more of the variables that could influence the results. Pre- and post-operative flexion were determined and compared to the pre- and postoperative posterior condylar offset ratio (PCOR) as measured by the Bristol knee group. RESULTS: We found an almost uniform increase in the posterior condylar offset post surgery, although a poor correlation between the pre- and post-operative flexion achieved was observed. CONCLUSION: An increase in PCOR after surgery does not lead to an increase in flexion achieved post-surgically. The pre-operative flexion a patient has is still the benchmark in predicting post-surgical outcome.
Keywords : posterior condylar offset; PCOR; flexion; computer-assisted surgery; TKA.