Abstract
Introduction
Fracture around the knee can lead to posttraumatic osteoarthritis (PTOA) of the knee. Malunion, malalignment, intra-articular osseous defects, retained internal fixation devices, and compromised soft tissues may affect the outcome of total knee replacement (TKR). On average, the posttraumatic patient subsets were 10.4 years younger than those for primary knee OA. Recently, there were several studies reporting the outcome of THA for posttraumatic OA hip. However, no current literature defines the comparative functional outcome between PTOA and primary OA knee.
The purpose of our study was to compare the midterm outcomes of patients undergoing TKR following periarticular knee fractures/ligamentous injuries versus primary osteoarthritis (PO) of the knee.
Materials and methods
Retrospective chart reviews of patients underwent TKR between 2008 and 2013 were identified. 136 patients underwent open reduction and internal fixation with plate and screws or ligament reconstruction while 716 patients were primary OA. Mean follow up time was comparable in both groups. Demographic data, medical comorbidities, WOMAC, visual analogue scale, and complications were recorded.
Results
There were significantly different in age (56.5 vs 63.8 years, p<0.0001), gender (48.5% vs 63.1% of female, p=0.0014), and obese (62.3% vs 76.0%, p=0.025) between PTOA and PO groups, respectively. The PO group had higher comorbidities than PTOA group including anticoagulant usage (51% vs 30.9%, p=0.0002), number of disease ≥ 4 (69.6% vs 45.3%, p<0.0001), ASA class ≥3 (38.8% vs 21.6%, p<0.0001), and Charlson Comorbidity Index (3.6 vs 2.8, p<0.0001).
The PTOA group had longer operative time (110.9 vs 100.1 minutes, p<0.0001) than PO group. Preoperatively anatomical axis of the knee was approximately valgus in PTOA but varus alignment in PO group (p<0.0001). However, postoperatively anatomical and mechanical axis was comparable in both groups.
Postoperative VAS (1.8 vs 1.2, p=0.002) at 1 year follow up and pain component of WOMAC (77.8 vs 85.7, p=0.013) in PTOA group was worse than PO group, respectively. On the contrary, there was no difference in postoperative complication and readmission rate between groups.
Conclusion
Total knee replacement for Post-traumatic OA was associated with poorer functional outcome compared to those for primary osteoarthritis in midterm follow up.
