Effect of Race, Gender, and Age on Lumbar Spine Muscle Volume

and Fat Infiltration in Degenerative Spine

Tetsuro Hida, Robert K. Eastlack, Tokumi Kanemura, Gregory M. Mundis Jr., Shiro Imagama, Behrooz A. Akbarnia

San Diego Spine Foundation, San Diego, CA, USA.Dept. of Orthopaedic Surgery, Konan Kosei Hospital, Japan

Dept. of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Japan

Lumbar Muscle Degeneration

The effect of age, gender, and race on lumbar muscle volume and fatty degeneration are not well understood.

67y Female Asian 72y Male Caucasian

SUBJECTS

ü Caucasian and Asian Patients from US and Japan.

ü Degenerative lumbar disease underwent single level (L4-5) fusion.

ü Pre-operative MRI Magnetom 1.5T, Siemens

ü Exclusion Criteria: Past Lumbar Surgery

METHODS

Psoas, psoas musclePS, paraspinal muscles (multifidus + erector spinae)

DiscPsoas

Muscle Measurementü Preoperative MRI, T2 axial image at L4/5 ü Cross sectional area(CSA) of muscles and discü Fat infiltration area (red area) with threshold method Lee, et al. Spine 2008

Psoas

PSPS

ü Muscle / Disc Area Ratio (MDAR)

ü % Fat Area

ü Age, gender and race

Statistical AnalysisT test, Chi squared test,Pearson’s correlation,Partial correlation,P<0.05 considered significant

Patient’s Characteristics, N = 140

RESULTS

Muscle Parameters between Races

Muscle / Disc Area Ratio

0

1

2

3

Psoas PS Psoas PS

Male FemaleCaucasian Asian

*

* *

* < 0.05

%Fat Area

0

10

20

30

40

Psoas PS Psoas PS

Male Female

Caucasian Asian

**

Muscle Parameters between Races

* < 0.05

Muscle Area and Age

Muscle / Disc Area Ratio, AgePartial CorrelationControlled by Race and Gender

Psoas: R = -0.39, P <0.001PS: R = -0.60, P <0.001

Negative Correlation

Fatty Degeneration and Age

% Fat Area and Age Partial CorrelationControlled by Race and Gender

Psoas: R = 0.18, P <0.001PS: R = 0.33, P <0.001

Positive Correlation

Muscle Parameters between Races Lumbar Muscle Mass and Qualityw/ controlling for body size

Caucasian > AsianCurrent Study

Lookingbill, J Clin Endocrinol Metab. 1991

ü Genetic Factorü Testosteroneü Daily Activity

Fatty Degeneration

Increased with Aging Lee SH, Spine J 2017

Poor surgical outcome with poor preoperative muscle condition. Yagi, Spine J. 2016

Increased in Degenerative Lumbar Disease

Lee JC, Spine. 2008

DISCUSSION

CONCLUSIONS

ü Lumbar muscle volume was larger and fatty degeneration was less in Caucasian than in Asian.

ü Muscle volume and quality was related to aging independent from race and gender.