Introduction In the past years a lot of interest has been raised on the mini-invasive surgical techniques in many fields of orthopaedic surgery.However,true innovative techniques have been rarely proposed,other then reducing the length of the incision with the aid of specially designed tools,particularly in the hip surgery.In the knee also, shorter scars should not be considered as the main purpose of the so called MIS(minimally invasive surgery)but as the side beneficial effect and the natural consequence of a more conservative technique,sparing soft tissues such as the quadriceps tendon,the extensor mechanism and the suprapatellar pouch,as well as nervous tissue and vascular supply.Considering this,the Mis-Quad Sparing technique is a really new technique,that has in view the object to preserve anatomic structures,and in particularly the extensor apparatus.

Patients and methods From june 2003 to june 2004 we’ve studied two homogeneous cohorts of patients uniform for age,gender,BMI and local and radiographic objectivity(Baseline characteristics have been compared between groups by means of Student T test or Fisher exact test)operated with the same implant(Zimmer, NexGen CR),one with QS technique(30 patients)and one with the standard approach(26 patients).

For the post-operative evaluation and for the critical comparison of the two groups we’ve considered the following parameters:length of operation,blood loss,ROM(at discharge,at 1 month,at 3 months,at 6 months),functional scores(using the Knee Society Assessment& Function Score),implants position and postoperative pain.In order to evaluate the differences among the two groups over time,we adopted a general linear model for repeated measures with calculation of Huber White robust standard errors to account for intra-patients correlation over time: a 2 sided p-value< 0.0125 was considered significant and Bonferroni correction was applied for post-hoc test.

Results and discussion The study has demonstrated that the Mis-QS technique allows less blood loss(p< 0.001 at all times considered),less pain (mean 10 points less with VAS),more rapid and better functional restoration (significant differences,p< 0.001,observed between groups and over time),with the same length of operation(at mean QS required only 10′ more than standard)and the same implant’s precision(p> 0.30 for all implant’s angles considered).Therefore,the supposed advantages of the QS technique can be considered real,based on our statistical comparison