Effects of a less-invasive surgical technique on cement mantle quality in total knee arthroplasty

The purpose of this study was to assess the effects of a less-invasive midvastus exposure during total knee arthroplasty (TKA) on cement mantle grade compared with a standard parapatellar arthrotomy and standard TKA. Fifty consecutive cemented minimally invasive TKAs using a midvastus approach, patellar subluxation without eversion, and less-invasive instrumentation were compared radiographically with a control cohort of 50 consecutive cemented standard TKAs. To eliminate patient selection bias, the standard cohort included consecutive surgeries completed before 2004, prior to the advent of minimally invasive techniques in TKA. Analog supine anteroposterior and lateral radiographs were evaluated using Ewald's criteria. Lucent lines, cement voids, and cement debris were recorded for each group. Radiographic analysis revealed compromised femoral component cement mantle grades in the minimally invasive group. The number of anterior femoral cement voids (zone 1) was significantly higher in the minimally invasive group, and peripatellar and tibial cement debris was also more common in the minimally invasive group. Based on these findings, the midvastus approach compromises the surgeon's ability to duplicate a consistent femoral cement mantle obtained using a standard exposure.