Is patient self-assessment of flexion after TKR able to identify risk of manipulation under anaesthesia?

Patient self-assessment of postoperative knee flexion following knee replacement was introduced at our institution. This protocol had a dual objective: improve follow-up and act as an early indicator to identify patients at risk of requiring a manipulation under anaesthesia. The aim of our study was to audit the use of this patient self-assessment tool and evaluate whether these outcomes were being achieved.

A prospective audit of patients admitted for total knee replacements under the care of one orthopaedic consultant between April and October 2009. Participants were asked to measure and record daily maximum knee flexion whilst sitting, from discharge through to six-week follow-up. Patients were advised to contact the arthroplasty team if flexion reduced by 10° or more for three consecutive days. Patient's documented knee flexion was compared to that measured on discharge and at six weeks postoperatively by clinicians.

Seventy-nine participants (82 knees) were included with 61 participants (64 knees) returning data for analysis (78% compliance rate). Comparison of patient and clinician measurements showed a mean difference of +2° with limits of agreements from -12° to +15°. At a mean follow-up of six weeks maximum flexion (measured by clinician) was 99° (95%CI 97°, 102°) and 92% had a 90°flexion or greater. During the audit period, six patients met the criteria to contact the arthroplasty team, however none of them followed this instruction.

Patient self-assessment of knee flexion at home with a simple goniometer was accurate enough to be useful and 92% of patients reached 90° maximum flexion at six weeks. However this self-assessment method was not successful as an early indicator to identify patients at risk of requiring a manipulation under anaesthesia. Future studies into alternative identifiers are required.

Level III. Investigating a diagnostic test.