Abstract
Total knee arthroplasty (TKA) is an effective, durable treatment for knee osteoarthritis.
However, a subset of patients experiences incomplete pain relief and ongoing dysfunction.
Posterior condylar offset (PCO) has previously been shown to be associated with postoperative
range of motion (ROM) following TKA; however, an association with patient-reported
outcome measures (PROMs) has not been established. The purpose of this study was to
evaluate the association between PCO and postoperative ROM and PROMs. A retrospective
review of 970 posterior-stabilized single design TKAs was performed. Preoperative
and postoperative radiographs were analyzed to measure the change in PCO and anteroposterior
(AP) femoral dimension. Clinical outcome measures, including Short Form-12 physical
and mental component summaries, Western Ontario and McMaster Universities Arthritis
Index, and Knee Society Score were reviewed to determine if these were influenced
by changes in PCO and AP dimension. PCO was increased by more than 3 mm in 15.1%,
maintained (within 3 mm) in 59.6%, and decreased by more than 3 mm in 25.3% of patients.
Comparing between these groups, there were no significant differences in postoperative
ROM or PROM. AP dimension increased in 24.4%, maintained in 47.8%, and decreased in
27.8%. Similarly, there were no significant differences in ROM or PROM between these
groups. Spearman's correlation analyses failed to identify an association between
PCO and ROM or PROMs. In conclusion, increasing or decreasing PCO or AP femoral dimension
with this PS TKA design did not significantly affect postoperative ROM or PROM. Similarly,
maintenance of PCO within one implant size with this system compared with optimal
sizing had no deleterious effect on TKA outcomes.
Keywords
total knee arthroplasty - posterior femoral offset - posterior condylar offset - outcomes
