Document Detail

Does hyperflex total knee design improve postoperative active flexion?
MedLine Citation:
PMID:  20598269     Owner:  NLM     Status:  MEDLINE    
INTRODUCTION: The rotating platform flexion (RPF) Sigma total knee prosthesis (DePuy; Warsaw, Indiana) was designed for maintaining the contact of the condyles with their corresponding tibial plateau throughout the high-flexion range. However, this requires an additional 3-mm bone cut of the posterior condyles. Compared to the conventional design, this modification is intended to improve the flexion range. This hypothesis was tested by studying the increase in flexion (flexion gain, range of motion [ROM], active flexion) of 59 consecutive patients who had received the hyperflex design implant (RPF), whose preoperative mobility values were retrospectively compared to these same values in another 59 consecutive matched patients who had received an implant with the conventional design of the same implant (rotating platform [RP]) between June 2005 and June 2006. Postoperative mobility was measured visually with a goniometer.
PATIENTS AND METHODS: Only osteoarthritic knees were eligible to be included. Knees with more than 20 degrees flexion contracture or less than 90 degrees flexion, and patients with a body mass index (BMI) greater than 30 were excluded. Both groups were comparable with regard to age, preoperative mobility values, and BMI. The sex ratio differed significantly, but preoperative mobility did not differ significantly in male and female patients in the RP and in the RPF groups. The difference in sex ratio did not appear to be a bias influencing preoperative mobility.
RESULTS: Overall, the flexion gain was correlated to preoperative flexion (r=-0.75, p<0.001). The flexion gain in the RPF group was significantly greater than in the RP group (13+-20 versus 6+-13; p=0.02) as was the ROM gain (10+/-17 degrees versus 4+/-12 degrees; p=0.02). However, the one-year active mean flexions were not significantly different (118+/-14 degrees versus 116+/-6 degrees; p=0.47). In patients whose preoperative flexion was less than 120 degrees (18 and 27 RPF prostheses), the flexion and ROM gains were significantly greater in the RPF group (23+/-16 degrees versus 14+/-16 degrees; p=0.03 and 26+/-18 degrees versus 17+/-9 degrees; p=0.05), and the mean one-year active flexion was also greater in the RPF group (124+/-13 degrees versus 116+/-8 degrees, p=0.02). In patients with more than 120 degrees of preoperative flexion, the flexion and ROM gains and the final mean flexions in both groups were comparable. In particular, there were nine patients in the RP group and ten patients in the RPF group whose flexion decreased.
CONCLUSION: Thus, the Sigma RPF prosthesis provided a significant additional flexion gain in patients with 90-120 degrees preoperative flexion, and less than 20 degrees flexion contracture. Patients with a preoperative flexion greater than 120 degrees were exposed to a decrease in flexion range whichever implant was used, RP or RPF.
LEVEL OF EVIDENCE: Level 3, therapeutic study.
P Massin; F-R Dupuy; H Khlifi; C Fornasieri; T De Polignac; P Schifrine; C Farenq; P Mertl
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2010-04-15
Journal Detail:
Title:  Orthopaedics & traumatology, surgery & research : OTSR     Volume:  96     ISSN:  1877-0568     ISO Abbreviation:  Orthop Traumatol Surg Res     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-07-05     Completed Date:  2010-11-01     Revised Date:  2013-10-31    
Medline Journal Info:
Nlm Unique ID:  101494830     Medline TA:  Orthop Traumatol Surg Res     Country:  France    
Other Details:
Languages:  eng     Pagination:  376-80     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier Masson SAS. All rights reserved.
Department of Orthopaedic Surgery, Bichat Hospital, North-Paris Teaching Hospitals Group, Paris Diderot Medical School, Paris, France.
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MeSH Terms
Aged, 80 and over
Arthroplasty, Replacement, Knee / instrumentation*
Knee Prosthesis*
Middle Aged
Osteoarthritis, Knee / physiopathology,  radiography,  surgery*
Prosthesis Design
Range of Motion, Articular / physiology
Retrospective Studies
Treatment Outcome
Erratum In:
Orthop Traumatol Surg Res. 2011 Sep;97(5):577

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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