Abstract
Background
Performing total knee replacement needs both bony & soft tissue consideration. Late John Insall advocating spacer blocks with concept of balanced & equal flexion – extension Gap. Although we usually excise both ACL & PCL, still it is possible to retain more soft tissue. Both PCL retaining & sacrificing Require intact collaterals for stability. Superficial MCL & LCL should be preserved, if possible. after PCL removal the following advantages could obtain: More correction of fixed varus or valgus deformity, More surgical exposure. but there are no proved disadvantages like; increasing in stress & loosening of bone-cement-prosthesis interface, specific clinical difference in ROM, forward lean during stepping up, proprioception inferiority. in other hand Over tight PCL cause excessive rollback of tibia & knee hinges open, preventing flexion (booking), and Severe posteromedial poly wear in poor balance PCL might be happened.
Mid range laxity when Post. Capsule is tight, even with correct tensioning in full extension & 90 degree flexion, may occur (and secondary collateral ligaments imbalance throughout ROM). There is a major effect of capsular contracture in coronal mal alignment with flexion contracture. Full MCL releases not only correct fixed varus but also open the medial space in flexion. MCL & post. Capsule has combined valgus resistant effect in extension. PCL release increase flexion gap more, May be necessary to release something that affect extension gap as compensated balancing (Post.medial capsule). Any flexion contracture need to posterior capsulotomy & post. Condyle osteophyte removal before femoral recut.
So it is possible to perform posteromedial capsulotomy prior to superficial MCL release.
Method
From May to Dec. 2009, 22 patients (23 knees) with primary DJD and varus deformity of knees were operated by myself with joint replacement. most patients had some degree of varus correction in flexion, passively. the varus angle was less than 25∗, means mild to severe but not decompensated. For soft tissue balancing during Total knee arthroplasty I consider the following steps;
Medial capsule & deep MCL release, PCL release, Posteromedial capsulotomy, semimembranous release, Superficial MCL release, Pes anserinous release. Post. medial capsulotomy was done in all cases.
The Average Age was 64.74 years, 19 patients were female (83%) and one of them had bilateral TKA simultaneously. Lt Knee was operated in 14 cases (70% of 24). Spinal anesthesia was applied in 82%. 10 patients were operated with MIS technique and 13 patients with Standard medial parapatellar incision. Semi membranous release was necessary in 4 cases (preop varus 17,20,24,25∗). MCL release was mandatory in 2 cases (preop varus 17, 24 ∗ & No Flexibility in 30∗ flexion).for checking balanced medial and lateral subtle laxity (playing), I have used simple blade with 1 & 2 mm thickness in each ends for younger patients, and the other one with 3&4 mm thickness in elder cases.
Results
Average follow up period is 234.45 days. Average Operating time was 1: 32 (h:m). Average Transfusion = 1.22 unit packed cell. No Flexibility in 30∗ flexion was seen in 3 patients.
Average varus malalignment =15.29∗ (2-25∗)/Av. Valgus angle = 7.19∗ (5-10 ∗)/Av. DLFA = 90.47∗ (87-93∗)/Av. PMTA = 83.41∗ (77-88.5∗)/Av. Ext. rotation cut = 3.11∗
Stage l + PCL + Post. Med. Capsular release was performed in 82.61%./Av. Post op alignment: 1.8 ∗ varus (0 -6 ∗) (worse in medial pivot knee).
Av. Polyethylen size: 12.4 (9 in oxynium -19 in plus)/Semi membranous release was necessary in 4 cases (preop varus 17,20,24,25∗) (Post. Op varus 1,6,4,2)./S.MCL release was mandatory in 2 cases (preop varus 17, 24 ∗ & No Flexibility in 30∗ flexion) (Post. Op varus: 1, 4 ∗). pre operation knee society score: stage I = 27.8, stage II = 37.9 increase to stage I = 85.47, stage II = 75.65
Conclusion
In society with more kneeling habitués, during performing total knee arthroplasty with less than 25∗ degree varus malalignment plus some degree flexibility of the deformity in flexion, it is wise to consider posteromedial capsular release prior to semi membranous & S.MCL release to obtain full correction of alignment. But the most important things is reaching to full align limb regardless of which chosen technique.
