To investigate the therapeutic effect of patient-gap balancing combine with measured resection in total knee arthroplasty (TKA) and assess the value of patient -gap balancing.

Seventy-eight cases (82 knees) underwent TKA in Pu Yang Traditional Chinese Medicine hospital for osteoarthritis from January 2012 to June 2015 were retrospectively analyzed. Inclusion criteria: primary total knee arthroplasty; flexion contracture deformity angle≤ 15°; varus deformity angle≤ 20°; Kellgren-Lawrence stage of knee osteoarthritis is Ⅲ、Ⅳ.Exclusion criteria: total knee arthroplasty in patients with knee inflammatory disease; serious medical diseases; data incomplete and without posterior stabilized fixed platform prosthesis from the same manufacturer. Thirty-eight cases (40 knees) used gap balancing technique. Another 40 patients (42 knees)underwent measured resection technology . The data of surgery, imaging , knee function and patient satisfaction rate were compaerd.Using t test of group design data for statistical analysis.

All the patients were followed up for 6 to 12months, average(7.6± 2.4)months. The preoperative parameters such as age, gender, body mass index, limb alignment and Knee society score(KSS) were not statistical different(P>0.05) .The one side knee surgery time of the two groups showed no significant difference (P>0.05). There was no significant difference in the bone resection thickness of the distal femoral lateral condyle and lateral tibial plateau between two groups(P>0.05), while the bone resection thickness of the femoral posterior lateral condyle in gap balancing group was significant smaller than that in measured resection group(t=4.36, P<0.05) .The 9 mm polyethylene insert was used in 29 cases of the gap balancing group and in 13 cases of the measured resection group, which showed significant difference(Z=-5.28, P<0.05). Intraoperative two pinholes B line connect with AP vertical A line angle<2°, measured resection groups external rotation angle (1.1±0.5)°, gap balancing groups internal rotation angle (1.2±0.5)°.Postoperative knee straight stress X-ray shown medial- lateral tibiofemoral joint angle of the two groups showed no significant difference (P>0.05), but bent-knee 90°stress was greater in the measured resection groups(Medial t=6.76, Lateral t=7.18, P<0.05). After operation limb alignment and crus anatomic axis angle, There was no significant difference between the two groups(P>0.05). Knee society score(KSS) at three months after operation of the two groups showed significant difference(t=4.86, P<0.05). The patient satisfaction rate was 87.5%(35/40 cases)in gap balancing group, 71.4%(30/42 cases)in measured resection group.

Gap balancing technique in limb alignment and flexion and straight gap balance is better than measured resection technique, but it can cause femoral prosthesis internal rotation intraopertively, attention should be paid to adjust two pinholes of attachment B line with A line angle.