Abstract
Purpose
To review the outcomes of patients undergoing manipulation under anaesthetic (MUA) after primary total knee arthroplasty (TKA) and predict those that may require such a procedure.
Methods
Prospective analysis of patients who required MUA post TKA performed by two surgeons using the same prosthesis from 2003 to 2008. Compared to a control group of primary TKA matched for age, gender and surgeon. All patients in both groups had pre- and post-operative measurements of range of movement. Risk factors were identified including warfarin and statin use, diabetes and body mass index.
Results
Seventy-two patients required an MUA out of 1313 TKAs (5.5%) compared to a control group of 50 patients. The mean arc of motion preoperatively was 89.0° (MUA group) vs 92.2° (control) (p=0.47), at discharge 71.0° vs 76.8° (p< 0.05) and 6 weeks follow-up 64.0° vs 97.3° (p< 0.0001). Post manipulation the mean arc of motion was 108° on table, 83.1° at 3 months follow-up and 81.9° at 12 months. Patients whose manipulation was within 3 months of TKA (23 patients) improved their mean arc of motion from 53.6° to 78.0° (p< 0.0025), those 3–12 months (42 patients) from 67° to 83.0° (p< 0.0001) and those >12 months (7 patients) 81° to 89° (p=0.32). Mean increase of extension was 3.7° on table and 3.6° at 12 months. Mean flexion increase was 40.5° on table and 15.7° at 12 months. The relative risk factor for requiring an MUA was 6.97 warfarin (p< 0.05), 1.58 statins, 2.85 diabetes and 1.17 obesity.
Conclusions
MUA following primary TKA improves their range of motion if done within 12 months, however only 50% improvement is maintained. Patients with less than 75° flexion at discharge or those on warfarin therapy are likely to require a manipulation to improve their range of movement.
