The Clinical Relationship between MCL Complete Detachment and Mechanical Alignment in TKA

Sim, Jae Ang; Lee, Beom Koo; Kwak, Ji Hoon; Yang, Sang Hoon

Abstract

PURPOSE: To evaluate the clinical relationship between medial collateral ligament(MCL) complete detachment and mechanical alignment in total knee arthroplasty.
MATERIALS AND METHODS
From February 2001 to December 2006, we performed 290 TKAs. 9 TKAs(0.03%) happened MCL complete detachment. 1 TKA was excluded for paraplegia. All cases were women. The mean age was 71.1 years old. The mean follow-up period was 41.1 months. There were 7 degenerative osteoarthritis and 1 rheumatoid arthritis. The clinical evaluation included Knee Society Score(KSS), function score and range of motion(ROM) at preoperative, postoperative 3 months, 6 months, 12 months and final follow-up. We measured the femoro-tibial angle and the mecha- nical axis by anterior-posterior and whole lower extremity radiograph. The medial instability obtained serial valgus stress radiograph.
RESULTS
There were 4 neutral and 4 varus alignment. KSS, function score, ROM was significantly improved in both group, and there were no significant differences in both group. On serial valgus stress radiograph, the difference compared with normal side decreased from 5.2 degree(postoperative 3 months) to 3.4 degree(final follow-up) in neutral alignment group, from 2.9 degree to 0.9 degree in varus alignment group. In final follow-up, it revealed that the medial instability of varus alignment group was less than that of neutral alignment group.
CONCLUSION
In MCL complete detachment, some stability obtained by repair of medial collateral ligament and bracing. Whole instability was not gone. Therefore, we should make the varus alignment of prosthesis in mechanical axis line position of 34 to 67% on the medial tibial plateau.