Relationship between Preoperative Femoro-tibial Angle (FTA) and Postoperative Recovery

after Total Knee Replacement �Shinichi Maeno, Kenshi Sakayama, Setsuya Kamei, Seiji Saito,

Nobuyuki Fujita, Masahiro Ishizaka, Kimura Kazuki, Maeda Kazuya, Ko Onoda, Kaori Sadakiyo, Masaki Akutsu,

Toshiro Otani, Ko Masumoto

Shioya Hospital, International University of Health and Welfare Keio University

Matsumura Surgery and Orthpaedic Clinic Masumoto Orthopaedic Clinic Minami-Matsuyama Hospital

Disclosure Statement

•  No Financial support for this study was obtained

•  No Shares held in any of the companies

•  Consultant Fees and Royalties received from - Japan MDM

•  The content of this study was approved through IUHW University medical ethics review board

•  Informed consent was obtained from each patient.

Introduction TKR in

Severe varus deformity (> 20 deg. varus)

vs. Less deformed knees (< 5 deg.)

-  Longer operation time (30 min. longer)

-  Less acquired ROM (flexion 98 deg. vs. 107 deg.)

-  Malpositioning of the implants

(3 deg. varus vs 0 deg. varus)

（Teeny SM, 1991） TKR

pre-op

Introduction ・ “the resulting alignment in conventional TKA is

influenced by large preoperative angular deformity” (Hsu WH, 2010)

・”preoperatively deformed knees did not do as well as

preoperatively undeformed knees.” (Sorrells RB, 2007)

Can less deformed knees get better result ??? Should TKR be done earlier ???

Purpose •  Assess deformity dependent functional

improvement following TKR through investigation of;

-walking　speed -stride length -balancing -movement -VAS and ROM

•  Determine appropriate time for operation

Method

•  Single surgeon

•  Mid vastus approach

•  Cemented PS implant　

(BKSR, Orthodevelopment,

Draper) with patellar resurfacing

•  Full weight bearing from the

　next day

•  44 consecutive knees of 44 patients, with medial

osteoarthritis ( 9 males, 35 females, average age of 73.2)

Assessment Walking ability: - walking speed

- stride length Balancing: - Functional Reach (FR) (Duncan PW, 1990)

- possible period standing on single leg (single leg standing) - Timed Up and Go Test (TUG) (Podsiadlo D, 1991)

ROM　 VAS (pain)

Assessment: pre-op., and 4 weeks post op. �

Functional Reach Test Timed Up and Go Test (TUG)

Analysis

Groups: -FTA:174-180 degrees (11 knees) - 181-189 degrees (17 knees) - > 190 degrees (16 knees)

The recovery rate (%) : post-op 4w/ pre-op x100 �����One way ANOVA

Bonferroni method

Result Post-op FTA

164

168

172

176

180

184

174<FTA<180 � 181<FTA<189 � 190<FTA �

N.S.�

VAS ROM

0%

40%

80%

120%

174<FTA<180 � 181<FTA<189 � 190<FTA �0%

40%

80%

120%

174<FTA<180 � 181<FTA<189 � 190<FTA �

N.S.�

＊＊�＊�

＊�

*p<0.05,**p<0.01

0%

50%

100%

150%

FTA 174-180° FTA 181-189° FTA 190°以上�

**p<0.01

174<FTA<180 � 181<FTA<189 � 190<FTA �

Timed Up and Go Test ＊＊�

*p<0.05

FTA<180 � 181<FTA<189 � 190<FTA �

Walking Speed ＊�

0%

50%

100%

150%

200%

FTA<180 � 181<FTA<189 � 190<FTA �

Stride length

0%

50%

100%

150% N.S.�

0%

50%

100%

150%

FTA180°以下� FTA180-189° FTA190°以上�FTA<180 � 181<FTA<189 � 190<FTA �

Functional Reach N.S.�

0%

100%

200%

300%

400%

<180 � 181<FTA<189 � 190<�

Single leg standing Operative side

0%

100%

200%

300%

400%

<180 � 181<FTA<189 � 190<�

Contralateral side

N.S.� N.S.�

Discussion ・”Patients with excessive preoperative alignment (>8° of varus or

>11° of valgus) have a greater risk of failure (2.3%)” (Ritter MA, 2013)

・”Preoperative severe varus deformities can be successfully managed

and do not have any detrimental effect on the longevity and clinical outcomes after a modern posterior stabilized TKA.” (Lee BS, 2011)

・”TKA … with severe deformity significantly improves patients‘

complaints and functional results. (Güçlü B, 2008)

Discussion ・”Varus gonarthrosis predisposes to varus malalignment in

TKA” (Heise TJ, 2009)

・”The severity of preoperative varus deformity influences

postoperative alignment despite using CAS (Computer Assisted Surgery)” (Bee DK, 2013)

In our series, the same tendency (though N.S.) (pre-op varus →post op residual varus) �

Discussion ・In our present study, severely deformed knees did Significantly better in;

- ROM recovery - Timed Up and Go test - Walking speed

Not significant, but better tendency in;

- VAS recovery - Stride length - Functional Reach - One leg standing

Encouraging results for the severely deformed knees �

Conclusion

・With regard to knee function, the recovery rate

compared to preoperative level was mostly better in

severely deformed knees postoperatively in TKR.

・ Time to take TKR cannot be too late in terms of

knee function recovery.