Abstract
The use of Patient Reported Outcome Measures (PROMS) has been critical to the success of total joint arthroplasty (TJA). They have made possible the evaluations of new implants, materials and surgical techniques that have been essential to the development of these technologies. PROMS have had a major impact on the decisions that surgeons make regarding treatment and care of patients. However, there are serious limitations of PROMS. They are useless in the first few weeks after surgery. They provide very little objective functional information to which health care providers can respond in the early, critical post-operative period. PROMS do not objectively measure specific outcome measures (e.g. ROM, distance walked). PROMS are also cumbersome and time consuming to use. Joint specific surface sensors are emerging to allow objective measurements of specific functional outcomes of knee surgery. This allows an examination of the factors that might affect these functional outcomes. The purpose of this study was to examine the relationship of age, gender, BMI and pain following TKA on ROM and activity measured using a joint specific surface sensor.
Methods
40 patients who underwent primary cruciate retaining TKA using the same implant system and patient specific instrumentation (PSI) were followed for 3 weeks with a knee specific surface sensor (TracPatchtm). The device was applied one day following surgery. Standard post-TKA care protocols were used. The ROM and distance walked was measured by the device. The relationship of these outcomes to patients’ age, gender, BMI and pain were examined.
Results
All but one patient tolerated the device. This patient had a superficial, transient skin reaction to the adhesive and was not included in the study. Patients under 60 regained more motion and were more active in the first 3 weeks after surgery than patients 60–69 and patients 70+. Gender had no significant impact on ROM or activity for each age group. BMI under 30 had no impact on ROM or activity. BMI over 40 had a significant impact on both ROM and activity. Pain had very little impact on ROM and moderate impact on activity in the first 3 weeks after surgery.
Summary
Joint specific sensors are becoming available to provide objective measurements of a joint's function. The knee specific sensors used in this study measured the number of steps taken and ROM in patients who underwent a primary, cruciate retaining TKA. The device was liked and well tolerated by patients. ROM was affected by age and BMI, but not by gender or, to a significant degree, by pain. The device will be useful in focusing therapy on those patients who most need it. Use of the device has the potential of making post-surgical care more effective and cost efficient.
