A Comparison of 2 Tibial Inserts of Different Constraint for Cruciate-Retaining Primary Total Knee Arthroplasty: An Additional Tool for Balancing the Posterior Cruciate Ligament.
BACKGROUND
Frequently, a normal posterior-cruciate ligament (PCL) is removed at the surgeon's discretion, converting the normal 4-ligament knee to a 2-ligament knee, thus eliminating the need to balance all 4 ligaments. The development of modular tibial components has led to the availability of differing polyethylene inserts that permit adjustment to the flexion gap independent of the extension gap, permitting PCL balancing not previously available. The purpose of this study is to analyze a specific cruciate-retaining (CR) prosthesis which has 2 polyethylene inserts intended for CR knee use.


METHODS
Between February 2004 and February 2013, the senior author (R.H.E.) has performed 930 total knee arthroplasties using the CR flat insert and 424 knees using the CR lipped insert. The inserts were selected during surgery, based on the assessed tension and function of the PCL. The patients were followed up as part of a prospective total joint program with the Knee Society clinical scoring, range of motion, complications, revisions, preoperative coronal deformity, gender, body mass index, and status of the anterior-cruciate ligament intraoperatively.


RESULTS
The average Knee Score was 92.4 for the flat group and 92.1 for the lipped group. Average knee flexion was 116.2° for the flat group and 114.4° for the lipped group (P=.2). Average knee extension (flexion deformity) was 2.1° for the flat group and 0.9° for the lipped group


CONCLUSIONS
The results reported here show that clinical outcomes and survivorship were no different for either insert option, leading to indirect evidence that appropriate soft tissue balance had been achieved.
Texas Center for Joint Replacement, Plano, Texas.
Roger H
RH
Emerson
Plano Orthopedic Sports Medicine & Spine Center, Plano, Texas.
John W
JW
Barrington
Texas Center for Joint Replacement, Plano, Texas.
Seun A
SA
Olugbode
Texas Center for Joint Replacement, Plano, Texas.
Omar K
OK
Alnachoukati
D000368:Aged; D016118:Anterior Cruciate Ligament / Q000601:surgery; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007595:Joint Prosthesis; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis / Q000706:statistics & numerical data*; D008297:Male; D020959:Polyethylene; D016119:Posterior Cruciate Ligament / Q000601:surgery*; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D012086:Reoperation / Q000706:statistics & numerical data; D012189:Retrospective Studies; D013977:Tibia / Q000601:surgery*
D020959:Polyethylene
Vanguard knee; anterior-cruciate ligament (ACL); cruciate-retaining (CR); posterior-cruciate ligament (PCL); total knee arthroplasty