Institute of Bone and Joint Surgery

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Hybrid stem fixation in revision total knee arthroplasty (TKA).

Surg Technol Int. 2004;12:214-20

Authors: Chon JG, Lombardi AV, Berend KR

The purpose of this study was to retrospectively compare the clinical and radiographic results of the Maxim Posterior Stabilized Constrained (PCS) (Biomet Orthopaedics, Inc., Warsaw, IN, USA) knee system using the hybrid fixation versus the fully cemented fixation of stems of the same length. The cohort in this study included 115 knees in 104 patients, with a minimum 2-year follow up postoperatively. All patients were evaluated with the Knee Society clinical rating score and roentgenographic evaluation. Of the 115 revision total knee arthroplasty (TKA) cases, the hybrid-fixation technique was used on both the femoral and tibial components of 75 (Group I-hybrid femur, hybrid tibia); the fully cemented technique was used on both components of 24 (Group II-cemented femur, cemented tibia); the hybrid-fixation technique was used on the femoral component and full cement on the tibial component of 13 (Group III-hybrid femur, cemented tibia); the femoral component was fully cemented, and tibial component had the hybrid-fixation technique used on 3 (Group IV-cemented femur, hybrid tibia). The average follow up was 44 (range: 24-126) months. At the most recent evaluation, the Knee Society score improved from an average preoperative value of 51.7 to 76.7, the pain score improved from 14.0 to 33.3, and the functional score improved from 40.5 to 47.0. The average stem-to-canal fill ratio was 80% in the femur and 85% in the tibia (p<0.05). Stem-to-canal fill ratio did not appear to influence clinical outcome. Radiolucent lines less than 2 cm were observed more frequently in the hybrid-cemented stems (89%) than the fully cemented stems (58%) at an average 8-year follow up postoperatively (p<0.05). A lower, but not statistically significant, failure rate was observed in the hybrid group in comparison with the cemented group.

PMID: 15455329 [PubMed - indexed for MEDLINE]

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The effects of early rollback in total knee arthroplasty on stair stepping.

J Arthroplasty. 2002 Sep;17(6):723-30

Authors: Draganich LF, Piotrowski GA, Martell J, Pottenger LA

We investigated the effects of early compared with late (ie, in flexion) rollback on quadriceps efficiency during stair stepping. We studied 10 patients with the IB II (Zimmer, Warsaw, IN) total knee arthroplasty (TKA), designed to enforce rollback at 73 degrees of knee flexion; 9 patients with the Maxim PS (Biomet, Inc, Warsaw, IN) TKA, designed to enforce rollback between 20 degrees and 30 degrees of flexion; 8 patients with the TRAC PS (Biomet, Inc, Warsaw, IN) mobile bearing TKA, designed to enforce rollback at 8 degrees of flexion; and 21 healthy control subjects during stair stepping. We measured the external knee flexion moments, which must be largely balanced by quadriceps force acting over the quadriceps lever arm, as indicators of quadriceps efficiency. The peak external knee flexion moment generated by the IB II patients during stair stepping was 12.4% and occurred at 65 degrees of knee flexion. This moment was significantly less (P=.006) than the peak moment, 17.6%, generated by the healthy controls. Knee flexion for the IB II patients did not reach 73 degrees, and rollback was not enforced until after the peak moment (ie, maximum demands on the quadriceps) had been attained. The peak moments generated by the TRAC PS patients, 14.2%, and Maxim patients, 14.8%, were not significantly different from that of the controls. These results suggest that early as compared with late rollback returns more normal quadriceps efficiency during stair stepping.

PMID: 12216026 [PubMed - indexed for MEDLINE]

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An algorithm for the posterior cruciate ligament in total knee arthroplasty.

Clin Orthop Relat Res. 2001 Nov;(392):75-87

Authors: Lombardi AV, Mallory TH, Fada RA, Hartman JF, Capps SG, Kefauver CA, Adams JB

The fate of the posterior cruciate ligament in primary total knee arthroplasty is controversial. An algorithmic approach is presented that is based on pathologic criteria for evaluating and treating patients with primary total knee arthroplasty that will aid in the posterior cruciate ligament decision-making process, producing more predictable procedures and outcomes. A consecutive series of the first 120 patients (171 knees) who had primary posterior cruciate-retaining arthroplasty and the first 120 patients (180 knees) who had primary posterior-stabilized arthroplasty with a minimum 5-year followup in which the Maxim Complete Total Knee System and the algorithmic approach were used were compared. No statistically significant differences in outcome between the groups were observed. Among the patients who had posterior cruciate-retaining arthroplasty, no revisions attributable to aseptic loosening have been reported at an average followup of 6.39 years. The average followup Knee Society total score was 162.16 points, with 91 (54.8%) knees having excellent outcome ratings. No revisions attributable to aseptic loosening have been reported among the patients who had posterior-stabilized arthroplasty at an average followup of 5.98 years. The average followup Knee Society total score was 158.05 points, with excellent outcome ratings reported in 96 (54.9%) knees. The use of a standardized algorithm has streamlined the treatment of patients having primary total knee arthroplasty, consistently providing excellent clinical results when either retaining or sacrificing the posterior cruciate ligament.

PMID: 11716428 [PubMed - indexed for MEDLINE]

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Freeman-Samuelson total arthroplasty of the knee.

Clin Orthop Relat Res. 1985 Jan-Feb;(192):46-58

Authors: Freeman MA, Samuelson KM, Bertin KC

Experience with cementless fixation over the last six years indicates that the technique offers greater opportunities for bone conservation. Thus, when cement is used, and especially if it is forced into the skeleton under pressure, the amount of bone incorporated into the implant is considerable. Conversely, if no cement is used, grafting techniques to fill defects are becoming increasingly routine, so that today no bone may be removed from the replaced knee or hip--all fragments that are excised are repositioned as grafts in defects. Thus, cementless fixation meets the fundamental orthopedic maxim of the conservation of bone stock. Given that an implant can be fixed with satisfactory clinical results without cement and without bone ingrowth, it becomes difficult to demonstrate a clinical advantage for the latter. Nevertheless, bone ingrowth is possible both experimentally and (with less confidence) in man. Thus, it is clearly a technique that should be evaluated. However, it is not, in the senior author's view, a technique that should as yet be generally used. Hopefully, investigations of this problem will take place in a restrained scientific way rather than by the current method, which is in response to the dictates of fashion and commerce.

PMID: 3967440 [PubMed - indexed for MEDLINE]