[Total knee arthroplasty. Prognosis after restoring the joint line]

The overall increase in the population's life expectancy resulting from technologic development and health advances, among other things, has led to an increased demand for primary total knee arthroplasty in recent decades. The patient's preoperative clinical status should be assessed and preoperative planning should be performed. The importance of the knee joint line has been underestimated in the patient's clinical course; restoring it is vital for the survival of a recently placed prosthesis. The purpose of this study is to clinically and radiographically correlate the importance of restoring the joint line in total knee arthroplasties performed at Hospital Regional "Lic. Adolfo López Mateos".

A prospective study was conducted of patients who underwent total knee arthroplasty at Hospital Regional "Lic. Adolfo López Mateos" from January to July 2010. Patients underwent X-rays preoperatively and 6 months after surgery to determine whether the joint line had been restored using Hoffman's method. Restoration was considered as acceptable when a +/- 4mm balance was obtained.

Thirty-two patients were studied, 17 males and 15 females; in 18 the postoperative alignment was considered as normal (+/- 4 mm), group 1, and in 14 the alignment was outside of this range, group 2. One patient had a -4 mm postoperative alignment and 13 were within the +4 mm range. The joint line is an indispensable parameter in the clinical course of patients who underwent total knee arthroplasty, as this allows for an appropriate range of motion, better collateral ligament stability, better weight bearing of loading surfaces and, as a result of this, a longer duration of the primary knee prosthesis.