[Cumulative sum control chart analysis of soft tissue balance in total knee replacement assisted by electronic...

To explore the training ability of pad to guide the balance of soft tissue by drawing cumulative sum (CUSUM) control chart total knee arthroplasty (TKA) sensor.

The data of 73 knees of TKA assisted by electronic gasket initially completed by a senior physician were analyzed retrospectively. There were 8 males (8 knees) and 52 females (65 knees), with an average age of (67.5±5.9) years (57-82 years). The balance of the internal and external space of knee joint was measured at 0°, 45°, 90°, and 120°, in order to observe the pressure distribution of the medial and la-teral compartments, and CUSUM learning curve was drawn.

In 0° extension, the medial pressure was higher than the lateral (P < 0.01), when flexion began, the medial and lateral pressures decreased, and became stable and approximately equal during 45°-120°. In the learning curve, by knee 34, CUSUM 0° curve crossed the acceptable control line from above, which showed that it was easy to grasp the soft tissue balance at 0° position through sensor learning. CUSUM 45° curve was above the unacceptable control line in the end, which meant that it was difficult to grasp the technique at the mid-flexion angle. CUSUM 90° and 120° crossed the acceptable control line from above by knee 68 and 57 respectively, which showed that the technique of balance could be improved with the aid of more cases.

The electronic pressure sensor can effectively guide the soft tissue balance in TKA. The learning process is simple and does not increase the risk of complications. It can be used as a tool for learning TKA soft tissue balance technology to guide joint surgeons to further master or improve the soft tissue balance technology.