The early changes in trunk muscle strength and disability following lumbar spine fusion.
OBJECTIVE
To analyze trunk muscle function pre- and postoperatively in patients undergoing lumbar spine fusion. Associations between changes in trunk muscle strength and disability were also studied.


METHODS
A total of 114 patients undergoing lumbar spine fusion participated in the study. The flexion and extension strength of the trunk was measured preoperatively and 3 months after surgery using a strain-gauge dynamometer. Disability and pain during the past week was evaluated with the Oswestry disability index (ODI) and visual analog scale (VAS), respectively.


RESULTS
Preoperative trunk extension and flexion strength levels were 319 N and 436 N in males, respectively, and 160 N and 214 N in females, respectively. In females 3 months postoperatively, the trunk extension strength increased by 39 N (p < 0.001) and flexion by 38N (p < 0.001), whereas it remained unchanged in males. The preoperative extension/flexion strength ratio was 0.79 in females and 0.76 in males. Three months postoperatively, the strength ratio decreased to 0.66 in males (p = 0.02). The mean ODI improved by 47% and back pain decreased by 65% (both p < 0.001). The changes in the ODI correlated with changes in trunk extension (r = -0.38) and flexion (r = -0.43) strength.


CONCLUSIONS
Patients undergoing lumbar spine fusion had low trunk muscle strength and strength imbalance. Back fusion surgery leads to considerable relief of pain and disability, but patients still have low trunk extension and flexion strength levels 3 months postoperatively. Therefore, there is need for a proper progressive strength training protocols to normalize back function.
Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland. sami.tarnanen@jyu.fi
Sami
S
Tarnanen
Marko H
MH
Neva
Hannu
H
Kautiainen
Jari
J
Ylinen
Liisa
L
Pekkanen
Tiina
T
Kaistila
Mirja
M
Vuorenmaa
Arja
A
Häkkinen
D000328:Adult; D000368:Aged; D001416:Back Pain / Q000503:physiopathology / Q000534:rehabilitation*; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000534:rehabilitation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000209:etiology / Q000534:rehabilitation; D011446:Prospective Studies; D016059:Range of Motion, Articular; D020127:Recovery of Function; D013123:Spinal Fusion / Q000009:adverse effects / Q000379:methods*; D011795:Surveys and Questionnaires; D013997:Time Factors; D060726:Torso; D016896:Treatment Outcome